2. features of phoenics-cvd - CHAM and PHOENICS

Documentation for PHOENICS 

TR 314 

PHOENICS-CVD 

USER GUIDE 

A customised CFD code for the 

simulation of CVD processes 

Version 2.0 

(PHOENICS 2006)

Title: PHOENICS-CVD User Guide. 

CHAM Ref: CHAM/TR314 

Document rev: 2 

Doc. release date: 18 October 2006 

Software version: PHOENICS 2006 

Responsible author: J C Ludwig 

Other contributors: J R Heritage 

Editor: J C Ludwig 

Published by: CHAM 

Confidentiality: 

Classification: Unclassified 

The copyright covers the exclusive rights to reproduction and distribution including reprints, 

photographic reproductions, microform or any other reproductions of similar nature, and 

translations. No part of this publication may be reproduced, stored in a retrieval system or 

transmitted in any form or by any means, electronic, electrostatic, magnetic tape, 

mechanical, photocopying, recording or otherwise, without permission in writing from the 

copyright holder. 

© Copyright Concentration, Heat and Momentum Limited 2006 

CHAM, Bakery House, 40 High Street, Wimbledon, London SW19 5AU, UK 

Telephone: 020 8947 7651 Fax: 020 8879 3497 

E-mail: phoenics@cham.co.uk

Web site: http://www.cham.co.uk

PHOENICS-CVD User Guide: TR314 

Contents 

1. INTRODUCTION................................................................................................................1 

2. FEATURES OF PHOENICS-CVD......................................................................................1 

3. OPTIONS AVAILABLE......................................................................................................1 

3.1. Diffusion.....................................................................................................................1 

3.2. Chemistry...................................................................................................................2 

3.3. Material properties .....................................................................................................2 

3.4. Radiation....................................................................................................................2 

3.5. Plasma.......................................................................................................................2 

4. IMPLEMENTATION IN PHOENICS-CVD...........................................................................3 

4.1. Use of the menu.........................................................................................................3 

4.1.1. Preliminary activities...........................................................................................3 

4.1.2. General menu points..........................................................................................3 

4.1.3. Starting a new CVD case...................................................................................3 

4.1.4. Starting the CVD Menu.......................................................................................4 

4.1.5. The CVD Menu Panels.......................................................................................4 

4.1.6. Object Settings.................................................................................................10 

4.1.7. Menu Operation Example.................................................................................13 

4.2. The 'q1' input file......................................................................................................17 

4.2.1. Variables..........................................................................................................17 

4.2.2. Diffusion settings..............................................................................................18 

4.2.3. Material property settings.................................................................................19 

4.2.4. Chemistry settings............................................................................................20 

4.2.5. Radiation settings.............................................................................................21 

4.2.6. Plasma settings................................................................................................23 

4.2.7. Additional features ...........................................................................................24 

4.2.8. Summary of 'q1' settings..................................................................................26 

4.2.9. Object-related settings .....................................................................................28 

4.3. Species data file (SPECIDAT)..................................................................................30 

4.4. Chemistry data file (CHEMIDAT)..............................................................................30 

4.4.1. Data file entry format........................................................................................30 

4.4.2. Reaction rate calculations................................................................................31 

4.5. Optical properties data file (OPTICDAT)..................................................................32 

4.6. Transport and thermodynamics data files (TRANSDAT and THERMDAT)..............33 

5. EXAMPLES.....................................................................................................................34 

In separate volumes: 

Appendix 1; Model Descriptions 

Appendix 2; Sample ‘Q1’ Files

This page intentionally left blank.

1. INTRODUCTION 

TR314 PHOENICS CVD User Guide 

This User Guide accompanies the PHOENICS-CVD code (Version 2.0, PHOENICS 2006). Its 

purpose is to enable users to set up and run CVD simulations. 

PHOENICS-CVD is an add-on to the general PHOENICS code and matches it in general 

structure; the experienced PHOENICS user will therefore only require the information about 

the additional CVD features of the code which this guide contains. Less experienced users 

may require help with respect to the use of PHOENICS itself; they should refer to the standard 

PHOENICS documentation (including the on-line information system, POLIS). 

The features of PHOENICS-CVD will first be described in general terms, with a description of 

the different options available. Activation of the features will then be addressed, followed by a 

discussion of examples that provide the basis from which further cases can be developed. 

2. FEATURES OF PHOENICS-CVD 

The code is designed to model the behaviour of CVD reactors. This necessitates the 

modelling of fluid flow and heat transfer relating to a multi-component gas, including both gasphase 

and surface chemical reactions. Additionally, the incorporation of plasma effects can 

be included. 

The code can simulate up to 30 gas species undergoing multi-component diffusion in addition 

to the conventional convection and diffusion effects. Heat transfer by convection, diffusion 

and conduction is linked with surface-to-surface radiation, including the effects of semitransparent 

solid materials. Chemical reactions, both gas and surface, are included by means 

of a data file containing information about the reactions. Up to 30 reactions of each type are 

permitted. Plasma-enhanced CVD modelling is achieved using an effective drift-diffusion 

model, providing a computationally efficient means of modifying chemical reaction rates to 

take account of the plasma. 

Note that the restrictions on numbers of gas species and reactions can be modified by 

straightforward coding changes and recompilation; however, computational speed is likely to 

be a restricting factor. 

The code also has a menu-driven user-interface, rendering it easy to use without the need for 

extensive CFD experience. 

3. OPTIONS AVAILABLE 

A range of options is provided for each of the features provided within the code. The 

theoretical basis of these different approaches is described in Appendix 1; this document is 

primarily related to implementation. 

3.1. Diffusion 

Multi-component diffusion can be modelled in several ways. In increasing order of accuracy 

(and computational expense) these are Fick, Wilke and Stefan-Maxwell models; in each case 

the binary diffusion coefficients can be based on either the actual gas temperature or a 

specified reference temperature. 

Thermal (Soret) diffusion is included using either the Clark Jones or exact formulation, 

incorporating the rigid spheres approximation or the use of Lennard-Jones parameters. 

1 PHOENICS CVD user Guide


Again, the increasing accuracy of the more sophisticated models is achieved at the expense 

of computation time. 

3.2. Chemistry 

For gas-phase chemistry the following options are provided for the reaction rate calculation: 

o extended Arrhenius dependence 

o Lindemann form 

o Troe form (9 parameters) 

o Troe form (10 parameters); 

in addition, provision has been made for user coding. 

For surface chemistry the choice is between the Langmuir-Hinshelwood formulation and a 

reactive sticking coefficient expression. The complexity of surface chemistry is such that 

many models do not fit easily into standard formats; in this case the use of user-defined 

reaction rates is again permitted and the Kleijn and Roenigk & Jensen models (for silicon and 

tungsten deposition respectively), among others, have been included in the code to exemplify 

this option. Complex surface chemistry, involving adsorbed species, is available using user 

coding; several examples are provided as guidance. 

Specification of the chemistry is by means of a data file in which each required reaction is 

included, with the model type and all necessary parameters; this will be described further in 

Section 4.4. 

3.3. Material properties 

The properties of the gas mixture (density, kinematic viscosity, specific heat and thermal 

conductivity) depend on the local composition, in terms of mass fractions of the different 

species, and the local conditions, primarily temperature and pressure. For economy, two 

simpler alternatives are also provided; in these the properties are based on the carrier gas, 

using either the actual temperature or a reference value. 

3.4. Radiation 

A surface-to-surface radiation model based on viewfactors is included. The radiation 

contributions are used in the conventional conjugate heat transfer solution of the energy 

equation. The model has the ability to incorporate semi-transparent solid materials although 

the gas itself is assumed to be transparent. Optical surface properties are derived from 

information in a data file (see Section 4.5 for further detail) and can be dependent on both 

temperature and wavelength; the use of spectrally varying properties can be of great 

importance in CVD applications. 

3.5. Plasma 

Plasma modelling is achieved by means of the effective drift-diffusion model. This involves 

making assumptions that are generally appropriate in CVD applications; it is then possible to 

simulate the plasma by solving equations for the electron density, the electron temperature 

and the real and imaginary parts of a complex potential (see Appendix 1 for more information). 

In this implementation the parameters affecting the plasma are specified in advance; the 

plasma therefore affects the gas flow (through the chemistry, which will depend on the state of 

the plasma) but there is no reciprocal interaction. 



The plasma model is only for capacitively-coupled rather than inductively-coupled devices. 

4. IMPLEMENTATION IN PHOENICS-CVD 

Standard features of PHOENICS are also available within the PHOENICS-CVD code. Here, 

only the items specific to PHOENICS-CVD will be described; general PHOENICS information 

can be found by using POLIS, the PHOENICS On-Line Information System. 

The primary means of problem specification is the 'q1' input file; it is this that is interpreted by 

the main PHOENICS processing module (EARTH). The 'q1' file is written in a special form 

using PIL (PHOENICS Input Language); this can be produced directly by the user or created 

automatically at the end of a menu session. Although it is possible to use the menu alone 

without having any understanding of the 'q1' file it is strongly recommended that users develop 

at least a working knowledge of 'q1' file structure. In this way it is possible to verify that 

problem details have been correctly set-up within the menu and also to modify settings without 

the need to re-enter the menu each time. Additionally there are some more advanced 

features of the code that require the user to make 'q1' settings outside the menu framework. 

In addition to the 'q1' input file use is made of data files specific to the individual code 

features. 

This section will cover in turn: problem set-up using the menu, 'q1' file settings for CVD 

problems and data specification in the data files. Examples of 'q1' files are provided in the 

CVD Input Library. 

4.1. Use of the menu 

4.1.1. Preliminary activities 

Before starting to use the menu it is advisable to make sure that all the information that will be 

needed is available. The geometrical information is particularly important and thought should 

be given at this stage to the way in which objects in the solution domain will be defined. 

Additionally, the various data files should be checked to ensure that they contain the 

appropriate data. These files are described in detail in Sections 4.3-4.6. The built-in material 

property file (phoenics/d_earth/props) should contain the required solids. 

4.1.2. General menu points 

The menu is made up of two linked parts; the first is specific to CVD applications and the 

second is based on the general PHOENICS menu system. This reflects the fact that many of 

the settings required for a CVD simulation are also required for other types of modelling. The 

most efficient procedure is to define the gas species immediately (because they will be 

needed in the general menu for initialization and the setting of boundary conditions); the 

plasma solution should also be activated if required. The remaining CVD settings are best left 

until the geometry has been defined. 

4.1.3. Starting a new CVD case 

To start a new CVD case in VR-Editor, click on File, Start new case and select CVD from the 

list of SPPs. 



The data files CHEMIDAT, OPTICDAT, THERMDAT, SPECIDAT and TRANSDAT do not have 

to be copied to the working directory. If they are there, they will be used. If they are not, the 

copies in /phoenics/d_earth/d_opt/cvd/inplib will be used. This allows users to modify the files 

locally without the danger of damaging the default files. 

4.1.4. Starting the CVD Menu 

The CVD menu is entered from the Main Menu, Models panel. 

Existing CVD Q1 files will be recognised as CVD, and the relevant menu panels will be shown. 

In many cases, the individual surface chemistry and plasma boundary condition patches will 

be absorbed into the equivalent settings for the blockage or plate objects to which they refer. 

Radiative surface patches will be transformed into radiative surface objects. 

4.1.5. The CVD Menu Panels 

Main CVD Panel 

The main CVD panel looks like this (the date may differ): 


The items on this panel are as follows: 


Reference pressure sets PRESS0, the reference pressure. This is always added to the 

solved pressure, P1, before use in obtaining pressure-dependent properties. It can also be set 

from the Main Menu, Properties panel. 

The first four ‘Settings’ sections should be visited before the case geometry has been created. 

Some of the settings made here are required for inlet and outlet boundary conditions. 

It is of course possible, though less efficient, to create the geometry, then activate the 

variables here and re-visit the boundary conditions which need to be set. 

The radiation section should be visited after the geometry creation is complete, as radiative 

transfer zones must be created on all internal and external surfaces. 

These sections are now described in turn. 

Gas Species 

Gas species ‘Settings’ leads to this panel: 

From here the species database can be inspected, and the required species selected from a 

scrolling list by clicking ‘Select’. The list is read from the SPECIDAT data file. 



Selections are made using standard Windows techniques – +click for multiple selection, 

+click to select a range. 

The solution of the selected species is automatically activated on exit from the CVD part of the 

menu. 

Clicking ‘View’ displays a list of the currently selected species. They can be de-selected here. 

All but one of the selected species are solved for. The remaining one is deduced from 

continuity. It is usual to select the most prevalent species as the deduced, or carrier species. 

The carrier is selected from the list of selected species by clicking ‘Modify’: 

Diffusion and gas properties 

Diffusion and gas properties ‘Settings’ leads to this panel: 



The thermal (Soret) diffusion can be activated, and the thermal diffusion option selected: 

The options for thermal diffusion are, in order of increasing complexity: 

o Clark-Jones form using rigid spheres approximation 

o Clark-Jones form using Lennard-Jones parameters 

o Exact form using rigid spheres approximation 

o Exact form using Lennard-Jones parameters 

For economy an update frequency is included: this is the frequency with which the thermal 

diffusion source terms will be updated. 

The options for the multi-component diffusion treatment are: 

o Fick 

o Wilke 

o Stefan-Maxwell 

The gas mixture properties and binary diffusion coefficients can be evaluated at the actual 

local gas temperature, or at a fixed reference temperature. 

Chemistry 

Chemistry ‘Settings’ leads to this panel: 



From here the reaction database can be inspected, and the required reactions selected from a 

scrolling list. The reaction database is read from the CHEMIDAT data file. 

The G in column 1 indicates a Gas phase reaction, an S indicates a surface reaction. 

Surface reactions take place on selected PLATE objects, and on selected faces of 

BLOCKAGE objects. 

Under-relaxation based on the chemistry sources can be useful in avoiding convergence 

problems caused by strong chemical reactions; this is activated here if required, and the linear 

relaxation factor set. 

The use of a stiff solver is possible for cases where the chemistry is much more important than 

the flow effects. 

Surface-to-Surface Radiation Model 

Radiation ‘Settings’ (for a new case, or a case with the Surface-to-Surface radiation model 

turned off) leads to this panel: 


When the model is turned on, the panel changes to this: 


When the radiation model is first turned on, radiation surfaces are created on all internal 

surfaces of BLOCKAGE and PLATE objects, and on the domain boundaries. 

The default boundary conditions are taken from the values set at the top of the panel. If heat 

sources have already been set on the parent objects, these will be used instead of the default 

thermal condition. 

The default material for optical properties is selected from a list, read from the OPTICDAT 

data file. 

The default external thermal condition can be fixed flux or fixed temperature. 

If the radiation model is turned off, the radiation zones are only deleted on exit from the CVD 

part of the menu. 

All the zones can be deleted and new zones generated by clicking on ‘Generate’. This may be 

necessary if the geometry has been changed, and the existing zones no longer fit the 

surfaces of the objects. 

The radiative surfaces appear in the Object Management Dialog and on screen as 

RAD_SURF objects. The default settings made can then be changed as required. 


Plasma Model 

The Plasma ‘Settings’ panel looks like: 

The settings for the equations allow the required parameters to be set. 


The boundary condition patches are created from selected surfaces of BLOCKAGE and 

PLATE objects. 

4.1.6. Object Settings 

Radiation Surfaces 

In the CVD-VR system, a new object type RAD_SURF has been introduced. These objects 

are automatically created to cover all internal surfaces and exposed parts of the domain 

boundaries when the radiation model is turned on, or when the ‘Generate’ button is pressed 

on the Radiation – Settings panel. 

The Attributes dialog for a RAD_SURF object looks like: 

For ‘external’ surfaces (domain edge and on non-participating solids), the boundary condition 

can be Fixed temperature or Fixed Flux. On ‘internal’ surfaces (on participating solids) only a 

zero-applied-heat-flux condition is allowed. 

The surfaces can be subdivided to make a finer radiation ‘grid’. 

It is also possible to create RAD_SURF objects manually, just as any other object. In that case 

care must be taken to set the ‘Internal’/’External’ flag correctly, and the ‘Side’ flag such that 

the source is inside participating objects and outside non-participating ones. 


Surface Chemistry and Plasma boundary conditions 


Surface chemistry patches are created on the outer surfaces of BLOCKAGE or PLATE 

objects. 

Clicking the CVD Settings button on a BLOCKAGE leads to: 

From here, surface chemistry can be activated on any exposed face of the blockage. Note 

that: 

West – East is in the X direction 

South – North is in the Y direction 

Low – High is in the Z direction 

In a similar fashion, the plasma conditions can be selected. The default is ‘Insulated’. The 

other options are ‘Electrode’ and ‘Earthed’. The voltage at all ‘Electrode’ surfaces is set in the 

main CVD Menu Plasma settings pages. 

For internal or external PLATE objects, the settings are directly on the Attributes dialog: 



The ‘Plasma boundary conditions’ only appear if the Plasma model has been turned on from 

the CVD-Menu Plasma settings page. 


4.1.7. Menu Operation Example 


The simplest way to understand menu operation is to work through one or more examples; in 

this case we shall use an ASM single wafer reactor being used for silicon deposition (a 

diagram of the geometry is provided as Figure 1). 

| INLET FLOW |**********************| 

C| PLUG PROFILE |**********************| 

E|||||||||||||||||||||||**********************| 

N|VVVVVVVVVVVVVVVVVVVVV|***** BLOCKAGE BL2****|W 

T| |**********************|A 

R| | |**********************|L 

E| V | ___________________|L 

| |**| | 

L| |F*| | 

I| | |I*| | 

N| V |N*| | 

E| |__| | 

| | 

| | |W 

C| V |A 

E| --> --> | |L 

N| V |L 

T| | 

R| | 

E|___________________________ | 

|****** WAFER **************| | | 

L|***************************|_______ V | 

I|***********************************| | 

N|***********************************| |W 

E|***********************************| |A 

|***********************************| | |L 

|************ BLOCKAGE BL1**********| V |L 

|***********************************| | 

|***********************************| | 

|***********************************| | 

|***********************************|PRESSURE| 

|***********************************| OUTLET | 

Figure 1. Reactor geometry 

Start the VR-Editor then click on ‘File – Start New Case – CVD’ 

Open the Main Menu ( on the hand-set or on the toolbar), then click on ‘Models, 

CVD settings’. 

Set the Reference pressure to 133Pa (equivalent to 1 torr). 

Gas Species 

Click on Gas species ‘Settings’ to define the gas composition. No species are currently 

selected so click on ‘Select’ to choose from the species data file (SPECIDAT). 

Select the following species (keep the key pressed to enable multiple selection): 

N2, H2, SIH4, SIH2, SI2H6, SI2H4, SI3H8. 

As each is selected it will be highlighted. Make a note of the identification numbers: they will 

be used throughout to identify the species (with a preceding 'S' in the general part of the 

menu). At this point you may click View to check your selection. 

One species must be selected as the carrier gas. The mass fraction of this species will be 

deduced from the others rather than being solved directly; it is also used in some simplifying 

assumptions if these are selected later. The carrier should be the dominant species (in mass 

or molar fraction terms). Click ‘Modify’ and specify N2 as the carrier gas. Click ‘Previous 

panel’. 


Diffusion 


Click on Diffusion and gas properties ‘Settings’ to select the models for multi-component 

diffusion and gas properties. Leave thermal diffusion inactive. 

The default Multi-component diffusion setting is the Wilke approximation which is satisfactory. 

The binary diffusion coefficient option can be left as ‘Actual gas temperature’. 

The default for the gas mixture properties is to use the gas composition at the prevailing 

temperature but two simpler options are also provided. Return to the main CVD panel. 

Chemistry 

Click Settings for Chemistry. The first task is to choose the reactions: click ‘Select’ to see what 

is available. The list comes from the CHEMIDAT file: G refers to gas phase reactions and S to 

surface reactions. The Kleijn model for silicon deposition is represented by reactions 6, 7, 9, 

10-16; select these and return to the menu. 

As surface reactions are included we must define the surfaces on which they occur: this will 

be done later when the geometry is being defined. 

We will now set a relaxation patch based on the chemistry (in addition to the flow based 

relaxation already activated): click in the tick-box by ‘Activate relaxation patch’ to activate the 

patch. The default factor of 0.5 is satisfactory so return to the main CVD panel. 

Geometry and boundary conditions 

At this point we need to create the geometry, so click Previous panel to return to the Top 

menu, then OK to leave the menu. 

Turn the mesh toggle on, and click in the domain to bring up the Mesh Settings dialog. 

Switch to cylindrical-polar co-ordinates, and set the domain size to: 

0.01 radians in X, 

0.21m in Y, and 

0.34m in Z. 


Leave the grid set to AUTO in all directions. Close the Mesh Settings dialog. 


The next task is to set up objects to which initial or boundary conditions will be attached; in the 

ASM geometry we need to identify solid regions (FIN & WAFER), blank regions (BL1 & BL2), 

inlet, outlet, wall and wafer as shown in the diagram. 

To create the objects, click on Object ( on the hand-set or on the toolbar) to bring 

up the Object Management Dialog. On the menu bar of that dialog click ‘Object, New, New 

Object’. 

Set name to BL1. Set Size and Position as 0.01, 0.155, 0.1, 0.0, 0.0, 0.24 

Click ‘General’ then ‘Attributes’. Leave the material as the default ‘Solid with smooth wall 

friction’. The volume covered by this object will be blanked out of the solution. Set a surface 

temperature of 290K on the North and Low faces. Click OK to close the Attributes dialog and 

OK to close the Object Specification dialog. 

Click ‘Object, New, New Object’. Set name to BL2. Set Size and Position to 0.01, 0.11, 0.1, 

0.0, 0.1, 0.0. Set a surface temperature of 290K on the South and High faces. Click OK to 

close the Attributes dialog and OK to close the Specification dialog. 

Click ‘Object, New, New Object’. Set name to FIN. Set Size and Position to 0.01, 0.005, 0.04, 

0.0, 0.1, 0.1. In General, Attributes, change the material to 111 Steel. Click on ‘Other 

materials’, select ‘Solids’, then ‘111 Steel at 27 deg C’. Click OK to close the Attributes dialog 

and OK to close the Specification dialog. 

Click ‘Object, New, New Object’. Set name to WAFER. Set Size and Position to 0.01, 0.12, 

0.005, 0.0, 0.0, 0.235. In General, Attributes, change the material to ‘111 Steel’. Activate 

Surface chemistry on the Low face. Click ‘CVD Settings – Surface Chemistry / Plasma’, then 

toggle ‘No’ to ‘Yes’ for the Low face. Click ‘OK’ to close the dialog. Set the heat source to 

Fixed temperature of 900K. Click on ‘Adiabatic’ next to Heat source. From the list of energy 

sources select ‘Fixed Temperature’, then enter 900 in the ‘Value’ input box. Click OK to close 

the Attributes dialog and OK to close the Specification dialog. 

Click ‘Object, New, New Object’. Set name to INLET. Set Size and Position to 0.01, 0.1, 0.0, 

0.0, 0.0, 0.0. In General, set the Type to INLET. In Attributes, set the inlet density to user-set, 

1.573E-3 kg/m 3 , the temperature to 290K, the Z velocity to 1.344 m/s, and the inlet value of 

S140 (SIH4) to 0.113. Click OK to close the Attributes dialog and OK to close the Specification 

dialog. 

Click ‘Object, New, New Object’. Set name to OUTLET. Set Size and Position to 0.01, 0.055, 

0.0, 0.0, 0.155, 0.34. In General, set the Type to OUTLET. Click OK to close the 

Specification dialog. 

Click ‘Object, New, New Object’. Set name to WALL. Set Size and Position to 0.01, 0.0, 0.24, 

0.0, 0.21, 0.1. In General set the Type to PLATE. In Attributes, set a surface temperature of 

290K. Click OK to close the Attributes dialog and OK to close the Specification dialog. 

Title 

Click on Menu. On the top page, enter a suitable title for the case. 

Initialisation 

Solution is made more efficient if realistic initial values can be specified for the solved 

variables. In Initialisation set S116 (N2) to 0.887, S140 (SIH4) to 0.113 and TEM1 to 290. 

The initial values for the species equations must be in mass fractions, not molar fractions. 


Variables 


On the Models panel, click on Settings by Solution control/Extra variables. This confirms that 

the correct velocity components, pressure, temperature and species are being solved; it also 

shows the stored variables, including the carrier species, the deposition rate variable, DEPO 

and PRPS (to define material properties); click Previous panel If additional variables were 

required this would provide the route for setting them. 

Numerical Controls 

In Numerics, set 400 sweeps. The default relaxation settings will suffice. (Note: plasma 

variables, if active, will usually require a very small setting of FALSDT. This is because they 

are unaffected by the gas flow that normally determined the appropriate relaxation level.) 

Radiation 

Go to ‘Models, CVD, Radiation Settings’. The optical property temperature determines the 

temperature at which the properties will be calculated: Set the default reference temperature 

for optical properties to 290K. 

The optical property index defaults to 198, which represents black body. In this case the outer 

walls are steel, which has an index of 111: Change the default material for optical properties 

to ‘111 Steel (spectral set equal to iron)’. 

The default setting for an 'outside' zone is Fixed heat flux of 0W (adiabatic). Change this to 

‘Fixed temperature’ and set the default external temperature to 290K. 

Activate radiation. 12 radiation surfaces should be created, each using the set default values. 

It will be necessary to modify some of these later. Leave the CVD menu and the Main Menu. 

In the Object Management Dialog, select all the blockage, plate, inlet and outlet objects, and 

hide them. The radiation surfaces will now be visible. It may help to go to Settings, Editor 

parameters and increase the X scale factor to 10. 

Select the 3 surfaces which cover the FIN object (B10-12), and from the right-click context 

menu open the dialog box. In Attributes, change the optical property temperature to 300. 

Close the dialog, and click YES to propagate the change. 

Select the 2 surfaces covering the WAFER object (B13-14), and in the same way change the 

optical property temperature to 900. 

Monitoring controls 

The print-out controls can be left at their default settings but it is sensible to match the 

monitoring (probe) location to the problem. While the code is running the values of selected 

variables in the monitoring cell will be displayed. It is worth selecting a 'sensible' cell for the 

probe which will provide useful information on the progress of the solution. 

Move the probe to 0.005,0.05,0.16. (The Position buttons on the hand-set move the probe 

when no object is selected). 

Solution 

Run the solver by clicking on Run - Solver. 

The solution should look something like this in the VR-Viewer post processor: 



This example has demonstrated the general use of the menu. There are many more options 

that have not been used and you might like to investigate them further. It is advisable to save 

the 'q1' file just created before doing so: click File – Save as a case and enter a descriptive 

case name. All the input and output files will be saved using the given name as a base. 

4.2. The 'q1' input file 

In this section the 'q1' settings required to activate the different model options are described; a 

working knowledge of the PHOENICS Input Language is assumed. Sample 'q1' files are 

included in the CVD Input Library and should be referred to in conjunction with the 

descriptions below. The first corresponds to the same problem as used for the menu 

description above but it was created without using the menu; experienced PHOENICS users 

might like to compare it with the 'q1' file created by the menu and convince themselves that 

the two, although different in format, are equivalent in content. 

The CVD options are activated by setting NAMGRD=CVD; this line should therefore always be 

included. 

4.2.1. Variables 

The primary variables are the mass fractions of the gas species. These should be identified 

as scalar variables between C1 and C30 inclusive (corresponding to integers 16 to 45) and it 

is essential that no other variables should occupy any of these allocations. One (and only 

one) of the mass fractions should be stored rather than solved; its value will then be deduced 

by the requirement that the mass fractions must sum to unity. It is recommended that the 

dominant species (in terms of mass or molar fraction) should be the one to be stored; the 

stored species will also be the one used internally if material properties are based on the 

carrier gas rather than the local mixture. All solved species should be solved whole-field by 

use of the SOLUTN setting. 

Certain other variables must also be stored: 

(i) the appropriate flow variables - pressure (P1), velocities (U1,V1,W1 depending on 

problem dimensionality) and temperature (TEM1) 



(ii) material identifier (PRPS) and deposition rate (DEPO) in Angstrom/minute. 

Additional variable names are also recognised if storage is activated for them in the 'q1' file; 

the appropriate values will be inserted automatically within the code and can then be printed in 

the 'result' file or viewed using the VR-Viewer post-processor. These are FR01-FRnn, MD01- 

MDnn, SP01-SPnn, SN01-SNnn, SPHT and KOND; they refer to molar fractions for each 

species, multi-component diffusion coefficients for each species, positive and negative gasphase 

chemistry sources for each species, mixture specific heat and mixture thermal 

conductivity respectively. Here 'nn' is the total number of gas species. (Note that the molar 

fractions, diffusion coefficients and sources will be in an internal order - this will be different 

from the order used in the 'q1' file only if the first species named in the 'q1' file, C1, is not the 

one that is stored rather than solved.) Care must be taken when using the optional storage to 

ensure that only species mass fractions occupy the positions 16 to 45 in the variable list. Note 

that SPHT will contain an effective specific heat, defined as (h-h0)/T, where h is enthalpy, T 

temperature and subscript 0 refers to 250K. 

The different gas species involved in the simulation must be identified using the NAME 

command. The available species are listed in the data file SPECIDAT which can be modified 

to suit the user's requirements (subject to a limit of 300 species and the proviso that the 

corresponding species must all appear in the transport and thermodynamics data files 

(TRANSDAT and THERMDAT). The name of a species is made up of 'S' followed by the 

identifying number in SPECIDAT (so S80 is hydrogen if the default SPECIDAT is used). 

In the VR Editor 

The solution for pressure, velocity, temperature and all the selected species is activated 

automatically by the Editor, together with storage for DEPO and EMIS. Storage of other 

derived variables, such as the molar fractions, can be activated from Main menu – Models – 

Solution control/Extra variables’. 

4.2.2. Diffusion settings 

Settings are required in the 'q1' file to determine which of the various models will be used for 

multi-component and thermal diffusion. These make extensive use of the SPEDAT command, 

the use of which can be understood from the 'q1' files provided and the examples below. 

In the first case the choice is between Fick, Wilke and Stefan-Maxwell. Multi-component 

diffusion is activated by the PRNDTL command for the mass fraction variables; the 

appropriate setting is -GRND8. Model selection is specified by the variable MCDOPT using 

the SPEDAT command - values of 1, 2 and 3 respectively should be used. For Stefan- 

Maxwell diffusion it is often necessary to implement linear relaxation, using SPEDAT to define 

the relaxation factor, SMRLX. The binary diffusion coefficient can be calculated using actual 

temperature or a reference value, selected by values of 4 and 2 respectively for BINOPT 

(again specified using SPEDAT); if a reference temperature is required it must be allocated to 

TMP1A. 

Thermal diffusion options also make use of SPEDAT to define THMDIF, THMOPT and 

THMFRQ. The first of these should be set to T to activate thermal diffusion; the second 

determines the model to be used: 

1 - Clark Jones form using rigid spheres approximation 

2 - Clark Jones form using Lennard-Jones parameters 

3 - exact form using rigid spheres approximation 

4 - exact form using Lennard-Jones parameters. 



These are in increasing order of computation time; as a computational economy it is possible 

to update the thermal diffusion source terms less frequently than every sweep by setting 

THMFRQ to a value greater than 1. 

Both Stefan-Maxwell and thermal diffusion require the settings USOURC=T and UDIFNE=T; 

these settings should anyway be made to include the energy transport caused by diffusion 

fluxes, as should DIFCUT=0.0. (Note that it is possible, though not recommended, to leave 

out these settings if neither Stefan-Maxwell nor thermal diffusion is active; in that case the 

energy flux associated with diffusion fluxes will also be omitted.) 

As an example the settings 

SPEDAT(SET,CVD,MCDOPT,I,3) 

SPEDAT(SET,CVD,SMRLX,R,0.5) 

SPEDAT(SET,CVD,BINOPT,I,4) 

SPEDAT(SET,CVD,THMDIF,L,T) 

SPEDAT(SET,CVD,THMOPT,I,3) 

SPEDAT(SET,CVD,THMFRQ,I,3) 

(in addition to the appropriate PRNDTL, USOURC, UDIFNE and DIFCUT settings) activate 

thermal diffusion based on the exact form using the rigid spheres approximation with source 

updates every three sweeps, binary diffusion coefficient calculation based on actual 

temperature and Stefan-Maxwell diffusion with a relaxation factor of 0.5. 


The Editor makes all the above settings based on the choices made in the Diffusion panel of 

the CVD Menu. 

4.2.3. Material property settings 

Material property settings are implemented by storing the variable PRPS and the specification 

of the selected property values in the 'q1' file. Density (RHO1), specific heat (CP1), laminar 

viscosity (ENUL), and thermal diffusion coefficient (PRNDTL(TEM1)) settings will then be 

taken from the property information table. The commands FIINIT(PRPS)=70 and CSG10='q1' 

enable the user to specify this property information in the 'q1' file (provided that property 

setting 70 has not been added to the 'props' file in the PHOENICS d_earth directory). The 

following indented lines should then be included in the 'q1' file: 

MATFLG=T; IMAT=1 

70 GRND8 GRND8 GRND8 GRND8 1.000 

0 0 

0 0 

0 0 

0 0 

The method to be used for the calculation of mixture properties is given by a SPEDAT 

command for the variable MCPROP: 1 refers to the carrier gas at a reference temperature, 2 

to the carrier gas at actual temperature and 3 to the actual gas composition at the actual 

temperature. Again TMP1A determines the reference temperature to be used, if required. 

One line of zeros should be included for each GRNDn entry in the property definition line. 

Additional materials can also be specified here if IMAT is suitably increased. 


The Editor automatically inserts the material property lines for material 70, and makes it the 

domain material. The mixture property settings are made based on the choices made in the 

Diffusion panel of the CVD menu. 


4.2.4. Chemistry settings 


Gas-phase chemistry is activated by means of a PATCH which will normally cover the whole 

solution domain (solid regions will be excluded automatically by the code). The patch name 

should start with 'CHEM' and the type should be VOLUME. To allow for source linearisation 

both coefficient and value must be set to GRND1; COVAL statements are required for all 

species and the temperature TEM1. 

Surface chemistry is activated by means of a PATCH having a name that starts with 'SURF' 

(note that there must be at least one additional character); the patch type should be the 

appropriate area (e.g. SOUTH) and the patch should only extend over the gas cells adjacent 

to the solid surface. COVAL statements should be provided for all species (including those 

that are not involved in the surface reactions), TEM1 and P1; this ensures that the Stefan 

velocity (flux to the surface) is correctly included. The coefficient should be set to FIXFLU and 

the value to GRND1 in all cases except P1; there the coefficient should be set to the 'batch 

factor'. For a conventional surface chemistry patch this will be 1.0. A higher number can be 

used if the computational surface represents several physical surfaces; by this means a batch 

reactor can be approximately simulated without modelling each wafer individually (useful if a 

parametric study is being undertaken for which run times would otherwise be unacceptable). 

If the coefficient is given an inappropriate setting (e.g. FIXFLU) a batch factor of 1.0 will be 

assumed. 

Automatic under-relaxation based on the chemistry sources can be useful in avoiding 

convergence problems caused by strong chemical reactions; this is introduced by means of a 

PATCH called RELT having PHASEM type. COVAL statements should be provided for all 

species involved in the chemistry, with a coefficient of GRND1 and a value of SAME. A linear 

relaxation factor, CHMRLX, can then be specified using SPEDAT: values are between 0 and 

1, with low values signifying tight relaxation. Note that conventional relaxation may also be 

needed, particularly for any species that do not participate in the chemistry. Linear relaxation 

is recommended for TEM1 and a small value (say 0.3) may be necessary to ensure stability. 

The reactions to be included in the simulation are specified using their identification numbers 

in the CHEMIDAT data file; additionally, the total number of gas-phase and surface reactions, 

NGREAC and NSREAC respectively, must be given. In all cases SPEDAT is used. The 

individual reaction numbers are specified using GREAC and SREAC in the two cases. As an 

example, 

SPEDAT(SET,CVD,NGREAC,I,2) 

SPEDAT(SET,CVD,GREAC(1),I,6) 

SPEDAT(SET,CVD,GREAC(2),I,7) 

SPEDAT(SET,CVD,NSREAC,I,1) 

SPEDAT(SET,CVD,SREAC(1),I,12) 

declares two gas-phase reactions (6 and 7) and one surface reaction (12). 

An output file 'data' is created by the code, containing information about the species present 

and the reactions that have been selected. This should always be checked for consistency; 

any mass imbalance in a selected reaction will in any case cause the code to issue a warning 

message. 


The whole-domain gas-phase chemistry ‘CHEM’ patch is created automatically by the Editor. 

The surface-reaction ‘SURF’ patches are automatically generated from each BLOCKAGE and 

PLATE object based on the settings for the faces. The relaxation patch is created if the 

relaxation option is selected on the Chemistry page of the CVD menu. 


4.2.5. Radiation settings 


Radiation is implemented by setting S2SR=T in the 'q1' file; additionally it is necessary to 

provide storage for variable EMIS which is used internally to define surface optical properties. 

To ensure that the correct surface-to-surface radiation formulation is used, the 'q1' file should 

also contain the line: 

SPEDAT(SET, CVD, RADCVD, L,T). 

The model is based on a surface-to-surface viewfactor approach, i.e. it is assumed that the 

gas is transparent. Thermal zones must be defined to cover all solid surfaces and viewfactors 

are then calculated between all pairs of thermal zones (taking account of any semi-transparent 

solid regions). From these a radiation exchange matrix is calculated that fully defines the 

energy transfer between surfaces in terms of the surface temperatures, which are calculated 

unless they are defined as fixed. Each thermal zone requires PATCH and COVAL commands 

to define the location, type and boundary conditions for the zone. The patch names must start 

with @RI; the patch type must always be an area, e.g. SOUTH. For zones on the surfaces of 

solids for which conjugate heat transfer is being employed (referred to below as internal 

surfaces) the patch should be on the solid side of the surface; otherwise (for example, at the 

domain edge) the patch should be on the gas side of the surface. 

For each thermal zone there must be a COVAL command for TEM1; the coefficient and value 

determine the type of thermal boundary condition: 

Coefficient Value Boundary condition 

GRND1/2 GRND1 Zero applied heat flux (internal surface) 

GRND1/2 VAL Fixed heat flux of VAL (external surface) 

0.0 VAL Fixed temperature of VAL (external surface) 

Zero applied heat flux is the only permitted setting for an internal surface. External surfaces 

(i.e. surfaces of non-participating solids) normally have a specified surface temperature or 

heat flux. GRND1/2 indicates that either GRND1 or GRND2 can be used: GRND1 is usually 

preferred although in some circumstances the less stable GRND2 can be more efficient. 

In addition to its radiation patch, a fixed temperature thermal zone should be accompanied by 

an appropriate laminar wall boundary condition for temperature in the conventional manner 

(see examples); the menu will do this automatically. 

A COVAL command is also necessary for the variable EMIS at each thermal zone. The 

coefficient determines the solid material according to the numbering system in the data file 

OPTICDAT. The value, if positive, specifies a reference temperature which will be used to 

calculate optical properties; a negative value is used to indicate the thickness of a semitransparent 

coating. If a semi-transparent coating is indicated, the EMIS coefficient will 

determine the optical properties in the layer; the optical properties of the background material 

will be determined by the PRPS value there: it is therefore necessary to ensure that 

consistency is maintained between PRPS values and the material labels in the optical data 

file. The temperatures specified for the surface property calculation can only be a guess 

before the run has been carried out; for the highest accuracy it would be necessary to carry 

out additional runs for which the thermal zone temperatures are taken from the result file for 

the preceding run (these values are listed at the end of the result file). Typically one or two 

continuation runs would be sufficient. 

In order that the accuracy of the viewfactor calculation can be seen by the user, two energy 

conservation checks are provided. The first relates to the viewfactors themselves and the 

second to the radiation exchange matrix; in each case the calculated value is printed out for 

each thermal zone (to the screen and also to the output file 'rad.dat' (see below)), together 

with the correct value. Errors of more than 1-2% should be regarded with suspicion: first 



check that the radiation patches have been correctly specified, then try increasing the number 

of test rays used (see below) and then increase the number of thermal zones until satisfactory 

agreement is achieved. In any case, each thermal zone should be defined so that the surface 

temperature does not vary significantly over it. 

An output file 'rad.dat' is created by the code; in addition to information about the thermal 

zones that have been defined it contains the array of viewfactors between the thermal zones, 

the accuracy checks referred to above and the radiation exchange matrix elements. This file 

should be saved if further simulations using the same geometry and thermal zones are to be 

carried out. It can then be renamed as RADI.DAT; if a file of that name is present in the 

current directory when a run is started the information it contains will be used and no 

viewfactor calculation will be carried out. This can be a significant time-saving feature but 

requires care. Use of the wrong RADI.DAT will usually cause an error because the number of 

thermal zones will be incorrect; however, if the number of thermal zones in RADI.DAT is the 

same as that in the case being run the simulation will continue based on incorrect information. 

If a second run is carried out using the same thermal zone definition but with differing surface 

properties it is possible (provided that no semi-transparent solids are present) to use the 

previous viewfactor calculation as the basis for the derivation of the new radiation exchange 

matrix; to achieve this it is necessary to modify 'rad.dat' to remove everything below the 

viewfactor array listing before renaming it as 'RADI.DAT'. 

Several additional settings are available within the surface-to-surface radiation model; these 

make use of the SPEDAT command. XMIR, YMIR and ZMIR are logicals which, if set to T, 

indicate symmetry in the corresponding coordinate directions (only available in 3-D); AXIBFC 

enables a 2-D BFC case to be specified as axisymmetric. By default the spectral variation of 

surface optical properties from OPTICDAT is used; the constant values in the file can be 

chosen instead by setting NOSPCT to T. In 3-D viewfactor calculations a coarse calculation is 

used in the construction of the viewfactors if an internal accuracy check is satisfied; this can 

result in view factor symmetries being only approximately satisfied. The logical FINE3D can 

be used to force the fine calculation under all circumstances; this should restore the 

symmetries, albeit at a cost in computation time. The viewfactors are usually renormalised 

before the radiation exchange matrix is derived as a means of ensuring good energy 

conservation; again, this may remove certain symmetries and lead to small anomalies in the 

results. VFNORM can be set to F to remove the renormalisation (energy conservation will 

then be imposed by modifications to the radiation exchange matrix instead). The accuracy of 

the viewfactor calculation can improved by increasing the number of test rays used in the 

determination of each zone-to-zone, or cell-to-cell, viewfactor; the number of rays is specified 

using NUMRAY. Note though that there is an internal limit of 5, and that NUMRAY has no 

effect in 3-D cases for which only one ray is used for each cell as a computational economy. 

View factors in cyclic geometries can be calculated but only if BFC=T. If a polar grid is used it 

is necessary to carry out a preliminary calculation for which BFC=T is set in the 'q1' file after 

the geometry has been defined; the 'rad.dat' file can then be used as input for the real case 

(BFC=F) as already described. 


The ‘@RI’ patches required to calculate the viewfactors are automatically generated from the 

RAD_SURF objects which are themselves generated when the radiation model is turned on, 

or whenever the ‘Generate’ button is clicked on the Radiation page of the CVD menu. 

The other additional settings described can be activated from the ‘Other settings’ page of the 

CVD menu Radiation page. 


4.2.6. Plasma settings 


If the plasma model is activated it is necessary to solve for an additional four variables: T0, 

NE, PHI1 and PHI2; these are respectively the electron temperature, the electron density and 

the real and imaginary parts of the complex potential (note that electron density is quoted in 

units of 10 16 electrons/m 3 to avoid excessively large numbers). As for the other scalar 

variables, whole-field solution should be activated. 

Additional variable names are also recognised if storage is activated for them in the 'q1' file: 

PHIT and GAMM are the amplitude and phase angle of the complex potential and GION is the 

ionization rate. 

The diffusive nature of the equations in the effective drift-diffusion model requires the 

modification of the standard PHOENICS transport equations to remove the other terms; this is 

achieved by setting TERMS(...,N,N,Y,P,Y,N) for each plasma variable. The diffusion 

coefficient is set by PRNDTL(...)=-GRND7 in each case. 

The source terms in the T0 and NE equations are set up using two patches which cover the 

whole domain (solid regions being dealt with internally); the patch names are 'COOL' and 

'IONIZE'. Each patch has type VOLUME and COVAL statements are required for T0 and NE; 

in each case both coefficient and value should be set to GRND7. Other parameters in the 

plasma equations are specified using arrays T0PAR, NEPAR and PHIPAR in SPEDAT 

statements; the meanings are as follows: 

NEPAR(1):Bohm velocity (m 2 /s) 

NEPAR(2):Ionization rate - upper bound on Arrhenius term (/s) 

NEPAR(3):Ionization rate - multiplying factor in Arrhenius term 

(/s) 

NEPAR(4):Ionization rate - activation energy in Arrhenius term (K) 

NEPAR(5):Ionization rate - field independent rate (/(m 3 /s)) 

T0PAR(1):Ohmic heating coefficient ((m 2 K)/(V 2 s)) 

T0PAR(2):Diffusion coefficient (m 2 /s) 

T0PAR(3):Cooling source term - time constant (/s) 

T0PAR(4):Cooling source term - equilibrium temperature (K) 

PHIPAR(1):Sheath parameter (m 4 /10 16 electrons) 

PHIPAR(2):Electron mobility (m 2 /(Vs)) 

PHIPAR(3):Phase angle of externally applied potential (radians) 

PHIPAR(4):Magnitude of externally applied potential (V). 

In addition to the terms in the plasma equations it is also necessary to specify appropriate 

boundary conditions. For T0 no action is required; this ensures zero energy flux across 

boundaries. For the potentials, patches will be required for electrodes and earthed surfaces; 

all these patches should have the appropriate area type and COVAL statements for PHI1 and 

PHI2 with a coefficient of FIXFLU and value of GRND7. Electrode patches should have a 

name starting with 'ELE'; the externally applied potential referred to above will be applied 

there. All other PHI1 and PHI2 patches of area type will be at zero potential (corresponding to 

earthed surfaces). NE boundary conditions should be specified at any surface through which 

electron flux is permitted. The patch type should again be an area, so the potential patches 

can be used for this purpose; the coefficient for NE should be GRND7 and the value 0.0. 

Realistic initialisation for plasma variables can be very beneficial; in particular, an 

inappropriate value for T0 can have severe consequences because it is used in an 

exponential term in the electron density equation. 

The plasma variables influence the chemistry and thus the flow; however, the flow only 

influences the plasma via the parameters in the plasma equations, which are dependent on 



gas composition. In the current release these parameters are taken to be constant and the 

plasma equations are then independent of the other variables. It is therefore possible to solve 

for the plasma first, in isolation, and then restart with solution for gas species and flow 

variables once a reasonable plasma solution has been obtained. This can be economical 

because no time is spent on the flow and chemistry solution while the plasma variables (and 

thus the reaction rates) are still unrealistic. 

The use of linear relaxation for plasma variables can cause convergence difficulties when 

block correction is implemented. False timestep is then recommended; the appropriate value 

can be small, typically O(10 -6 ). 


The solution for the plasma variables, and the whole-domain ‘COOL’ and ‘IONIZE’ patches are 

automatically created when the plasma model is turned on. The appropriate boundary 

condition patches are created from BLOCKAGE and PLATE objects based on the settings 

made. The parameters in the plasma equations are set from the Plasma settings pages of the 

CVD menu. The plasma variables can be initialised from the Main menu – Initialisation page. 

4.2.7. Additional features 

To facilitate CVD modelling two additional features have been provided; the first relates to 

inlets and the second to shower plates. 

Inlets are normally defined in terms of mass flow (per unit area), with incoming velocity, 

temperature and species mass fractions also being specified. As an alternative it is possible 

to give the flow in terms of sccm (standard cubic centimetres per minute) over an area that 

must also be given; the incoming gas composition must then be defined in terms of molar, 

rather than mass, fractions. To select this option the patch name must begin with 'VIN'. 

COVAL statements are required for P1 and all other variables defining the incoming stream; 

the coefficients are FIXFLU for P1 and ONLYMS for other variables, as usual for an inlet. The 

value for P1 is the inflow (in sccm), the value for the velocity normal to the inlet face is the 

corresponding area and the values for the gas species are molar fractions. Thus 

PATCH(VIN1,LOW,........) 

COVAL(VIN1,P1,FIXFLU,100.0) 

COVAL(VIN1,W1,ONLYMS,0.1) 

COVAL(VIN1,S80,ONLYMS,0.2) 

specifies an inflow of 100sccm over an inlet area of 0.1m 2 ; the gas composition is 20% S80 

(hydrogen) by volume. Note that this feature cannot be used in BFC cases. 

Shower plates are common in CVD reactors and a special patch has been defined to model 

them. The region in question should first be defined to have the appropriate solid properties 

(using PRPS); an additional patch should then be defined in the same place having a name 

beginning with 'SHWR' and an area type that indicates the plane of the plate. COVAL 

statements are required for all solved scalar variables in addition to the velocity component 

normal to the plate. All values should be GRND7 and the coefficients should be ONLYMS, 

with the exception of those for P1 and the normal velocity which have a special meaning. The 

coefficient for the normal velocity should be the open area fraction (porosity) of the plate and 

that for P1 should be a loss parameter. This is defined as dp/(dynamic viscosity x mean 



velocity), where dp is the pressure drop across the plate; for circular holes this will be equal to 

32l/a 2 , where l is the thickness of the plate and a is the diameter of the holes. As an example, 

PATCH(SHWR1,HIGH,........) 

COVAL(SHWR1,P1,32000.0,GRND7) 

COVAL(SHWR1,W1,0.5,GRND7) 

COVAL(SHWR1,S80,ONLYMS,GRND7) 

COVAL(SHWR1,TEM1,ONLYMS,GRND7) 

CONPOR(PLAT1,-1,........) 

COVAL(PLAT1,PRPS,0.0,111) 

represents a steel plate with 50% open area and a loss parameter of 32000 (possibly 

representing a plate 1mm thick with holes of 1mm diameter). Note that a new PRPS number 

should really be specifically defined so that the plate would have the properties that take 

account of its porous nature; the two patches should cover the same range of cells. 

The use of a stiff solver is possible for cases where the chemistry is much more important than 

the flow effects; this can be activated by setting USOLVE=T. Using this approach involves 

solving for all species, including the carrier; the code will automatically make this adjustment 

but the user should ensure that all appropriate COVAL statements are provided for the 

species that is nominally stored (such statements would not be needed under normal 

circumstances). 


The CVD sccm inlet using ‘VIN’ as a patch name has not been implemented in the CVD menu. 

The USER_DEFINED object type can be used to create such a patch if required. 

The shower plate has not been implemented as a special object type. Again, the 

USER_DEFINED object can be used to create the patch commands listed above. 

The stiff solver can be turned on from the Chemistry settings page of the CVD menu. 


4.2.8. Summary of 'q1' settings 


This section contains a review of the settings described in the preceding sections. 

Group 7: 

Group 8: 

Group 9: 

Group 13: 

Variables to be solved or stored: 

Flow variables, including: TEM1 

Mass fractions C1-C30 (one stored, rest solved) 

Radiation variable (if used) EMIS 

Other required stored variables: PRPS, DEPO 

Optional stored variables: FR01-FRnn, MD01-MDnn, 

SP01-SPnn, SN01-SNnn, 

SPHT, CNDT 

Plasma variables (if used): T0, NE, PHI1, PHI2 

Use whole-field solver (default) for all solved scalar variables 

Species identification: 

NAME(C*) = Snnn (nnn is the identifier in SPECIDAT) 

USOURC = T, UDIFNE = T, DIFCUT = 0.0 

TERMS(...,N,N,Y,P,Y,N) for each plasma variable 

USOLVE = T if stiff solver used 

PRNDTL(Cn) = -GRND8 

PRNDTL(...) = -GRND7 for each plasma variable 

Property information as required, using CSG10 = 'q1' 

Gas phase chemistry (only seen in Q1EAR and RESULT): 

PATCH(CHEM*,VOLUME, ........ ) 

COVAL for solved species and TEM1 

Surface chemistry (only seen in Q1EAR and RESULT): 

PATCH(SURF*,area type, ........ ) 

COVAL for all solved species, P1 and TEM1 

Under-relaxation based on chemistry: 


Group 17: 

Group 19: 

PATCH(RELT,PHASEM, ........ ) 

COVAL for each solved species 

Radiation (only seen in Q1EAR and RESULT): 

PATCH(@RI***, area type, ........ ) 

COVAL for EMIS and TEM1 

Plasma sources: 

PATCH(COOL,VOLUME, ........) 

COVAL for T0 and NE 

PATCH(IONIZE,VOLUME, ........) 

COVAL for T0 and NE 


Plasma boundary conditions (only seen in Q1EAR and RESULT): 

PATCH(ELE*, area type, ........) 

COVAL for PHI1, PHI2 and NE 

PATCH(***, area type, ........) 

COVAL for PHI1, PHI2 and NE 

Linear relaxation for TEM1 

S2SR = T (if radiation activated) 

SPEDAT(SET, CVD, RADCVD, L, T). 

SPEDAT(SET,CVD,parameter,type,value) for (some of) the following 

parameters: 

Diffusion: 

MCDOPT integer 

SMRLX real 

BINOPT integer 

THMDIF logical 

THMOPT integer 

THMFRQ integer 

Gas properties: 

MCPROPinteger 

Chemistry: 

CHMRLX real 

NGREAC integer 

GREAC(1:n) integer(s) 

NSREAC integer 

SREAC(1:n) integer(s) 


ANJAC logical 

Radiation: 

XMIR logical 

YMIR logical 

ZMIR logical 

AXIBFC logical 

NOSPCT logical 

FINE3D logical 

VFNORM logical 

NUMRAY integer 

Plasma: 

NEPAR(1:5)real 

T0PAR(1:4)real 

PHIPAR(1:4)real 

4.2.9. Object-related settings 


Additional parameters are written for the BLOCKAGE and PLATE objects to capture the 

surface chemistry and plasma boundary condition settings made. The radiation surfaces are 

captured as RAD_SURF objects. 

Blockage 

The extra lines written for a BLOCKAGE object for surface chemistry are: 

> OBJ, SUF_REAC_dir, YES 

> OBJ, BATCH_F_dir, batch_factor 

Where: 

o dir is E,W,N,S,L,H for East, West, North, South, High or Low. If the line is missing, or 

the setting is NO there is no surface chemistry on that face. 

o Batch_factor is the batch enhancement factor for that face. 

The extra settings made for plasma boundary conditions are: 

> OBJ, PLASMA_dir, status 

Where: 

o dir is as above 

o status can be one of EARTHED, ELECTRODE or INSULATED. 

If the line is missing, INSULATED is assumed. 

Plate 

The extra lines written for an external PLATE object for surface chemistry are: 

> OBJ, SUF_REAC, YES 

> OBJ, BATCH_F, batch_factor 

Where: 

o Batch_factor is the batch enhancement factor for that face. 


If the line is missing, NO surface chemistry is assumed. 

The extra settings made for plasma boundary conditions are: 

> OBJ, PLASMA, status 


Where status can be one of EARTHED, ELECTRODE or INSULATED. If the line is missing, 

INSULATED is assumed. For internal plates, _L is appended to SUF_REAC, BATCH_FAC 

and PLASMA for Low-side conditions, and _H for High-side conditions. 

Radiation Surface 

The attributes for a RAD_SURF object are: 

Object type: 

> OBJ, TYPE, RAD_SURF 

Manually or automatically generated: 

> OBJ, SETTING, AUTO 

If the object has been generated automatically, the user is prevented from changing the object 

side and whether the surface is ‘internal’ or ‘external’. ‘Internal’ surfaces lie on participating 

solids. All other surfaces are ‘external’. 

External linkage coefficient: 

> OBJ, TEMP_COEF, temp_coef 

Temp_coef can be GRND1 or GRND2 

External heat flux (for ‘external’ object only): 

> OBJ, HEATFLUX, Qsurf 

Qsurf is the external heatflux in W/m 3 

Or external temperature (for ‘external’ object only): 

> OBJ, SURF_TEMP, Tsurf 

Alternatively, Tsurf the external surface temperature in K. 

Material for optical properties: 

> OBJ, OPTIC_INDX, imat 

imat is the index of the material in the OPTICDAT file 

Temperature for evaluating optical properties: 

> OBJ, OPTIC_TEMP, Topt 

Topt is the temperature in K at which the optical properties of the surface will be evaluated 

Or thickness of optical coating: 

> OBJ, COAT_THICK, coat 

Alternatively, coat is the thickness of a semi-transparent coating in m. 

Object side: 

> OBJ, SIDE, HIGH 

If the line is absent LOW is assumed. This is only required for RAD_SURF objects not lying on 

the domain boundaries. 


4.3. Species data file (SPECIDAT) 


The species data file is used to list the species that are available, up to a limit of 300. A 

sample demonstrates the format: 

140 G SIH4 

141 G SIH3 

142 G SIH2 

The identification numbers must run consecutively, starting at 1. The following letter indicates 

a gas species (G) or a surface adsorbed species (A); the species name which follows must be 

exactly the same as that used in other data files. Adsorbed species can be used if 

appropriate surface chemistry is selected. 

4.4. Chemistry data file (CHEMIDAT) 

4.4.1. Data file entry format 

The chemistry data file, CHEMIDAT, contains all the information required to calculate the 

reaction source terms in the species mass fraction equations. The reactions are identified by 

a character (G for gas-phase or S for surface) and an integer (the reaction number). Each 

reaction is allocated a number of lines with these identifiers at the start of the first line. 

Comments can be included between entries using ! as the first character on such lines. 

A sample from the file indicates the nature of the entries: 

!-----G5------------- 

G 10 3 SI2H6SI2H4+H2 2.100E+10 0.000E+00 1.930E+05 

5.000E-01 

3 SI2H6 -1 SI2H4 1 H2 1 

0 

0 0 

!---------------------------------------------------------------------------- 

------ 

! Kleijn model: surface reactions 

! the parameters for the sticking coefficients of S1 and S3 were taken from 

! C.R. Kleijn, "Transport Phenomena in CVD reactors", PhD thesis, TU Delft, 

1991 

!---------------------------------------------------------------------------- 

------ 

!-----S1------------- 

S 11 5 SIH4SI+2H2 0.000E+00 0.000E+00 0.000E+00 

0.000E+00 

3 SIH4 -1 SI 1 H2 2 

0 

-101 7 8.000E-02-7.500E+03 1.200E-06 4.990E+04 1.700E+04-1.538E+05 

6.100E-01 

SI 2.300E+03 2.809E-02 2.252E-05 

The format of the first line is A1,I3,I2,1X,A32,1P4E10.3. The entries are, in order: the 

character identifier, the reaction number, the number of additional lines in the entry, the 

reaction in symbols (for information only) and the four Arrhenius parameters. 

The format of the second line is 1X,I2,4(1X,A16,I3). The entries are, in order: the number of 

species in the reaction (maximum 8), the name and stoichiometric coefficient for each species 

(up to 4). If more than 4 species are involved a continuation line should be inserted with 



format 3X,4(1X,A16,I3). There is no need to fill either line if the number of species does not 

require it. 

The format of the third line is 1X,2I4. This line will be used for third-body enhancement factors 

but is currently not used: zeros should be inserted. 

The format of the fourth line is 1X,2I4,1P6E10.3. The entries are, in order: IRT (defining the 

reaction type - see below), the number of additional parameters (maximum 90) and the values 

of those parameters (up to 6). If more than 6 additional parameters are used a continuation 

line should be inserted with format 9X,1P6E10.3; again there is no need to fill the line. 

For surface reactions there is another line; its format is 1X,A16,1P3E10.3. The entries are the 

name of the deposited species, followed by its density and molecular mass; the final entry is 

the surface concentration of vacant sites (mol/m2) which is only required if adsorbed species 

are being used. Users intending to use adsorbed species in their surface chemistry modelling 

should consult CHAM for advice before proceeding. 

4.4.2. Reaction rate calculations 

The formulation to be used for a reaction is specified in the data file by means of the integer 

IRT (on line 4). A negative value indicates the use of user-coding; this should be inserted in 

functions GAF and GAR, for forward and reverse gas-phase chemistry, or GFLUX, for surface 

chemistry (both these routines are in the 'cvdchm' file). Non-negative values select built-in 

options as described in Appendix 1; only the specification of the parameters is described here. 

All the options are selected by the value of IRT, modulo 100; that leaves the 'hundreds 

column' free to be used for passing additional information about the reaction 

(a) Gas-phase reactions 

The built-in reaction are: 

0 - extended Arrhenius (4 parameters) 

1 - Lindemann form (6 parameters) 

2 - Troe form (9 parameters) 

3 - Troe form (10 parameters). 

The Arrhenius parameters appear on line 1 of the data file entry in the order Ak, bk, Ek, ck, with 

ck only used in the extended Arrhenius option; for all other choices the first three parameters 

are Ak,inf, bk,inf, Ek,inf. The line of additional parameters contains as many as necessary of, in 

order, 

Ak,0, bk,0, Ek,0, ak, T1,k, T3,k, T2,k; 

the Lindemann form requires only the first three, the 9 parameter Troe form requires the first 

six, and the 10 parameter Troe form requires all the parameters. 

The 'hundreds column' of IRT is used to determine whether gas or plasma temperature should 

be used in calculating reaction rates, and whether the reaction is reversible; a value of 5 

indicates plasma temperature, 0 represents a reversible reaction and 1 an irreversible one. 

As examples, IRT=3 activates the 9 parameter Troe form using gas temperature, IRT=501 the 

Lindemann form using plasma temperature and IRT=-2 user-coding. 

(b) Surface reactions 


The built-in options are: 

0 - sticking coefficient formulation 

1 - Langmuir-Hinshelwood formulation. 


The Arrhenius parameters in the sticking coefficient appear on line 1 of the data file entry in 

the order Ak, bk, Ek (the fourth entry is not used, but should be present); if Ak=0, a sticking 

coefficient of unity is used. 

User-coding has been included for the Kleijn model for SiH4 and Si2H6, the Roenigk and 

Jensen model for SiH4 and the Kleijn et al model for tungsten production from WF6 and H2; 

these correspond to 'units column' values of 1 to 4 respectively. A plasma model has been 

added for demonstration purposes only; it uses a value of 5. 

The 'hundreds column' of IRT is used to determine the rate-determining mechanism for the 

surface deposition: 

1 - kinetics limited 

2 - diffusion limited 

3 - diffusion/kinetics limited 

4 - no deposition. 

As examples, IRT=100 activates the sticking coefficient form with the reaction limited by 

kinetics and IRT=-301 the Kleijn model for SiH4 deposition, taking account of both kinetics and 

species diffusion to the surface in determining the reaction rate. 

The use of diffusion limitation should be used with care as it can result in significant 

underestimation of reaction rates. It can be necessary when the surface reaction formulation 

specifies a sub-linear dependence on reactants which would become unrealistic at low 

concentration levels. 

4.5. Optical properties data file (OPTICDAT) 

The optical data file, OPTICDAT, defines the surface properties for use in the surface-tosurface 

radiation model. The bulk of the information it contains for each material relates to the 

temperature dependence of the refractive index and absorption coefficient in each of the 60 

spectral intervals. If the spectral variation is not activated only the first line of each entry is 

used (although the others must be present). 

The first entry is the material label; this should be between 100 and 199 for opaque solids, 

and between 200 and 299 for semi-transparent materials. The next two entries are the 

constant values of emissivity and reflectivity respectively. The rest of the line relates to the 

Monte Carlo model which is not part of this release. 

A sample entry follows: 

# Al=ALUMINIUM Data from E.D.Palik 

100 0.1 0.9 0 0.000 0.000 0.000 0.000 

1 99.000 0.000 0.000 0.000 0.000E+00 0.208E+03 

0.000E+00 0.000E+00 1 

1 99.000 0.000 0.000 0.000 0.000E+00 0.223E+03 

0.000E+00 0.000E+00 2 



1 99.000 0.000 0.000 0.000 0.000E+00 0.204E+03 

0.000E+00 0.000E+00 3 

1 99.000 0.000 0.000 0.000 0.000E+00 0.205E+03 

0.000E+00 0.000E+00 4 

1 99.002 0.000 0.000 0.000 0.000E+00 0.212E+03 

0.000E+00 0.000E+00 5 

1 98.991 0.000 0.000 0.000 0.000E+00 0.205E+03 

0.000E+00 0.000E+00 6 

. . . . . . . 

. . . 

. . . . . . . 

. . . 

4 0.120 0.000 0.000 0.000 0.000E+00 0.230E+01 

0.000E+00 0.000E+00 55 

4 0.095 0.000 0.000 0.000 0.000E+00 0.199E+01 

0.000E+00 0.000E+00 56 

4 0.075 0.000 0.000 0.000 0.000E+00 0.172E+01 

0.000E+00 0.000E+00 57 

4 0.059 0.000 0.000 0.000 0.000E+00 0.145E+01 

0.000E+00 0.000E+00 58 

4 0.046 0.000 0.000 0.000 0.000E+00 0.121E+01 

0.000E+00 0.000E+00 59 

4 0.035 0.000 0.000 0.000 0.000E+00 0.968E+00 

0.000E+00 0.000E+00 60 

For each spectral interval (numbered on the right hand end of the line) there are 8 real 

parameters. These are used to define the complex refractive index of the material, n + ik; the 

first 4 parameters relate to the real part and the second 4 to the imaginary part, as follows: 

n = n0 + n1T* + n2T* 2 + n3T* 3 

k = exp(k0T*) (k1 + k2T* + k3T* 2 ) 

where T* = (T-300)/1000. The spectral intervals cover the range of wavenumbers from 10 2 to 

10 5 cm -1 . The viewfactor approach splits the spectral range into a smaller number of bands 

within which the properties can be regarded as approximately constant; the numbers in the left 

hand column define appropriate bands for each material, 

Users can add to the optical data file in order to simulate the behaviour of materials that are 

not already included, bearing in mind the compatibility with PRPS values. The version of the 

data file provided with the code demonstrates this: substances such as aluminium, which are 

included in the built-in PHOENICS property table, are given the same material number in the 

optical properties data file; others, such as tungsten, which are not, have been allocated 

higher numbers and their material properties should be defined in the 'q1' file or by adding to 

the 'props' file. 

4.6. Transport and thermodynamics data files (TRANSDAT and 

THERMDAT) 

These data files are in the same format as that adopted by the CHEMKIN package. A sample 

from THERMDAT follows: 

SIH4 121386SI 1H 4 G 0300.00 4000.00 

1000.00 1 

0.06893873E+02 0.04030500E-01-0.04183314E-05-0.02291394E-08 

0.04384766E-12 2 

0.11070374E+04-0.01749116E+03 0.02475166E+02 0.09003721E-01 

0.02185394E-04 3 



-0.02681423E-07-0.06621080E-11 0.02925488E+05 0.07751014E+02 

4 

The first line contains the species name, a number which is not used and then the elemental 

composition of the species; the numbers at the end of the line are the low, high and transition 

temperatures respectively. The next three lines contain polynomial coefficients used to 

determine enthalpy, entropy and specific heat as a function of temperature within the two 

ranges thus defined. The first 7 parameters apply to the high temperature range and the 

remaining parameters to the low temperature range. An exception is made for adsorbed 

species in the Arora & Pollard surface chemistry model. In that case the high data are used 

instead for adsorption data and the high and transition temperatures are set equal. 

An extract from TRANSDAT follows: 

SIH4 2 207.6 4.084 0.000 0.000 1.000 ! mec 

SIH3 2 170.3 3.943 0.000 0.000 1.000 ! mec 

SIH2 2 133.1 3.803 0.000 0.000 1.000 ! mec 

Here only the numbers in the third and fourth columns are used: they are the Lennard-Jones 

parameters e/k and σ respectively for the species named in the first column. 

As with the other data files, the user is expected to add entries for missing materials in the 

standard format. Note that the names of any species must be consistent in all data files in 

which they appear. 

5. EXAMPLES 

Three input 'q1' files are presented in Appendix 2. These have been constructed for the 

simulation of an ASM single-wafer reactor for silicon deposition, a tungsten reactor and a 

parallel plate plasma reactor, also for silicon deposition. All geometries are axisymmetric and 

laminar, steady-state conditions are assumed. Although these examples are based on real 

cases it should be noted that some of the parameters are selected for demonstration 

purposes. The 'q1' files are also provided in the code installation as library cases. 

In the first case the inlet flow is 88.7% nitrogen and 11.3% silane by mass, at a temperature of 

290K. The susceptor is held at a temperature of 900K and all outside walls are cooled to a 

temperature of 290K. Five gas-phase and five surface reactions are activated. 

The tungsten reactor has a showerhead inlet, the details of which are not modelled; instead a 

uniform inlet is specified. The inlet flow is 6% hydrogen and 94% tungsten hexafluoride by 

mass, corresponding to approximately 90% hydrogen by volume. Gas-phase chemistry is less 

important in this case and only a single surface reaction is used in the simulation. The 

showerhead structure is a very significant part of the problem because of its thermal effect: it 

is heated radiatively by the hot tungsten susceptor (733K) and in turn passes heat to the gas 

by convection and to the outer wall by radiation. 

The plasma enhanced reactor is for silicon deposition from pure silane. Three gas-phase and 

two surface reactions are included, all dependent on the state of the plasma. The gas-phase 

reaction rates all exhibit dependence on ionization rate while the surface reaction rates all 

have an Arrhenius formulation, based on surface temperature, multiplied by the ion flux to the 

surface. (The reactions defined in CHEMIDAT for this simulation are for demonstration 

purposes only.)

2. features of phoenics-cvd - CHAM and PHOENICS

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