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 ...
Plasma-assisted etch � Plasma-assisted etch is a sequence of chemical reactions between etched material and plasmagenerated chemical species resulting products generation of volatile � In order to initiate and sustain etch process the etchant species should be continuously generated and delivered to those surface segments where the material removal takes place – the bottoms of etched features. � In order to have a uniform across-chip etch rate, the combination of fluxes of neutrals and ions impinged the etched surface should be a constant. + Copyright ©2008, Mentor Graphics. 4
Effects of Aspect Ratio & Microloading Etch rate variation across layout caused by: � Across-layout variation in concentration of neutrals in the above-wafer plasma region - Microloading � Variation in resistance to the interfeature transport of neutrals - AR � Variation in plasma visibility - AR Neutrals concentration across layout Variation of solid angle of visibility Ω Ω Proc. of SPIE Vol. 6520 65204D-1 � AR variations are responsible for the distortion in etch rate, sidewall slope and etch depth developed in neighboring features � Microloading is responsible for those distortions developed in the identical features located in different neighborhoods characterized by different pattern densities Layout and averaged patter density Copyright ©2008, Mentor Graphics. 5
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- Page 15 and 16: Thin & Thick Polymer Regimes T. Tat
- Page 17 and 18: Approximation of “Thin Polymer”
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- Page 23 and 24: Calculation of Gas Kinetic Paramete
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- 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
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Plasma-assisted <strong>etch</strong><br />
� Plasma-assisted <strong>etch</strong> is a sequence<br />
of chemical reactions between<br />
<strong>etch</strong>ed material and plasmagenerated<br />
chemical species<br />
result<strong>in</strong>g<br />
products<br />
generation of volatile<br />
� In order to <strong>in</strong>itiate and susta<strong>in</strong> <strong>etch</strong><br />
process the <strong>etch</strong>ant species should be<br />
cont<strong>in</strong>uously generated and delivered<br />
to those surface segments where the<br />
material removal takes place – the<br />
bottoms of <strong>etch</strong>ed features.<br />
� In order to have a uniform across-chip<br />
<strong>etch</strong> rate, the comb<strong>in</strong>ation of fluxes of<br />
neutrals and ions imp<strong>in</strong>ged the <strong>etch</strong>ed<br />
surface should be a constant.<br />
+<br />
Copyright ©2008, Mentor Graphics.<br />
4
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