Design specific variation in pattern transfer by via/contact etch ...
Design specific variation in pattern transfer by via/contact etch ... Design specific variation in pattern transfer by via/contact etch ...
Calibration Methodology � Allocate a number of vias/contacts not less than the number of model parameters. The best practice is to pick the features from the regions characterized by different pattern densities � Measure either etch rates, post-etch via depth, or CD for these features � Run the VCE and extract from the data-base the relative fluxes of all radicals coming to the measured features: γ ij � Run a optimization module to extract parameters values providing the best fit between calculated and measured characteristics. Calculated depths 184 180 176 172 R 2 = 0.9226 168 164 168 172 176 180 184 Measured depths Correlation of 92% was achieved for process node: 55 nm; test chip size of 25.2x30.7 mm (a) (b) Measured values (plotted by triangles) and calculated values (squares) of vias (a) with top diameter 110 nm, and (b) with top diameter 67 nm. Copyright ©2008, Mentor Graphics. 26
VCE Capability Based on accurate calculation of an across-die flux variation of radicals participating in etch reactions we can predict: Across-die etch rate variation Via 3 layer Via5 layer Copyright ©2008, Mentor Graphics. 27
- Page 1 and 2: Design Design Design specific speci
- Page 3 and 4: Etch Step in Pattern Transfer Simul
- Page 5 and 6: Effects of Aspect Ratio & Microload
- Page 7 and 8: • Neutral radical generation •
- Page 9 and 10: Mass-balance Differential equation
- Page 11 and 12: Radical Flux to the Feature � Whe
- Page 13 and 14: Die-level analysis: Calculation of
- Page 15 and 16: Thin & Thick Polymer Regimes T. Tat
- Page 17 and 18: Approximation of “Thin Polymer”
- Page 19 and 20: Etch Stop Condition � Etch stops
- Page 21 and 22: VCE Input/Output Copyright ©2008,
- Page 23 and 24: Calculation of Gas Kinetic Paramete
- Page 25: Calibration Methodology � The maj
- Page 29 and 30: VCE Capability Across-die etch hot-
- Page 31 and 32: APPLICATIONS of VCE Copyright ©200
- Page 33 and 34: Process-Aware Design Optimization v
- Page 35 and 36: Process optimization • VCE predic
- Page 37 and 38: F Concentration, mass fraction Redu
- Page 39 and 40: Averaged pattern density R=1000µm
- Page 41 and 42: OBSERVATION: FIB inspection of 0.26
- Page 43 and 44: CF2 flux F flux SEMbar (1) in all01
- Page 45 and 46: Calibration/Prediction - Resist Mod
- Page 47 and 48: Calibration/Prediction - Main Etch
- Page 49: Mentor Graphics Corp., San Jose, CA
Calibration Methodology<br />
� Allocate a number of <strong>via</strong>s/<strong>contact</strong>s not less than the number of model parameters. The best practice<br />
is to pick the features from the regions characterized <strong>by</strong> different <strong>pattern</strong> densities<br />
� Measure either <strong>etch</strong> rates, post-<strong>etch</strong> <strong>via</strong> depth, or CD for these features<br />
� Run the VCE and extract from the data-base the relative fluxes of all radicals com<strong>in</strong>g to the<br />
measured features: γ ij<br />
� Run a optimization module to extract parameters values provid<strong>in</strong>g the best fit between calculated<br />
and measured characteristics.<br />
Calculated depths<br />
184<br />
180<br />
176<br />
172<br />
R 2 = 0.9226<br />
168<br />
164 168 172 176 180 184<br />
Measured depths<br />
Correlation of 92% was achieved for process node:<br />
55 nm; test chip size of 25.2x30.7 mm<br />
(a) (b)<br />
Measured values (plotted <strong>by</strong> triangles) and calculated<br />
values (squares) of <strong>via</strong>s (a) with top diameter 110 nm, and<br />
(b) with top diameter 67 nm.<br />
Copyright ©2008, Mentor Graphics.<br />
26
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