Lec_20 - EE143 F2010 Lecture 20 Importance of...

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Professor N Cheung, U.C. Berkeley Lecture 20 EE143 F2010 Importance of Layer-to-Layer Alignment marginal contact Design Rules are needed : • Interface between designer & process engineer • Guidelines for designing masks Example of Design Rule: If the minimum feature size is 2 l , then the safety margin for overlay error is l . Example: metal line to contact hole no contact! safety margin to allow for misalignment
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Professor N Cheung, U.C. Berkeley Lecture 20 EE143 F2010 IC RESISTOR MASK LAYOUTS – REGISTRATION OF EACH MASK Registration of mask patterns is critical show separate layouts to avoid ambiguity Oxide mask (dark field) Al mask (clear field) Contact mask (dark field) A A B B 0 1 2 “registration” shows overlay of patterns scale in m for B-B “cut” Registration of one mask to the next (also called “alignment” and “overlay”) is a crucial aspect of lithography
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Professor N Cheung, U.C. Berkeley Lecture 20 EE143 F2010 Same Layout but with misregistration (misalignment) perfect registration A A B B 0 1 2 scale in m for B-B “cut” A A B B 0 1 2 scale in m for B-B “cut” Contact mask misaligned by 2 m Lets look again at cross-section A-A to understand the consequence of this misalignment. Note contact mask 2 m
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This note was uploaded on 03/03/2012 for the course EECS 142 taught by Professor Ee142 during the Spring '04 term at University of California, Berkeley.

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Lec_20 - EE143 F2010 Lecture 20 Importance of...

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