chap3_2 - Principles of VLSI Design CMOS Processing...

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Unformatted text preview: Principles of VLSI Design CMOS Processing Technology CMPE413 1 UMBC U M B C U N IV E R S I T Y O F M A R Y L A N D B A L T IM ORE COU NTY 1 9 6 6 CMOS Processing Technology P-well process: Similar to n-well process except a p-well is implanted rather than an n- well. Produces n- and p-transistors that are more balanced. Transistors that reside in the native substrate tend to have better characteristics. In general, p-devices are lower gain than n-devices. Therefore, p-well process naturally moderate the differences. n-substrate p-well lightly doped p-well region for n-transistors Principles of VLSI Design CMOS Processing Technology CMPE413 2 UMBC U M B C U N IV E R S I T Y O F M A R Y L A N D B A L T IM ORE COU NTY 1 9 6 6 CMOS Processing Technology Twin-tub process: Allows independent optimization of gain, threshold voltage, etc. of n- type and p-type devices. Both types of substrate contacts are REQUIRED in this process. n+ n+ n+ p+ p+ p+ p-well n+ substrate epitaxial layer n-well High purity silicon grown with accurately determined dopant concentrations Epitaxy: V DD GND Principles of VLSI Design CMOS Processing Technology CMPE413 3 UMBC U M B C U N IV E R S I T Y O F M A R Y L A N D B A L T IM ORE COU NTY 1 9 6 6 CMOS Processing Technology Silicon-On-Insulator (SOI) process: Instead of silicon substrate, use an insulating substrate. Silicon can be grown on: Sapphire or SiO 2 which in turn has been grown on silicon. Sapphire lightly doped n-type Si (n-) 1) Principles of VLSI Design CMOS Processing Technology CMPE413 4 UMBC U M B C U N IV E R S I T Y O F M A R Y L A N D B A L T IM ORE COU NTY 1 9 6 6 CMOS Processing Technology Sapphire n- n- Sapphire p- n- p-island Sapphire photoresist Thinox p- n- Sapphire p- n- poly Sapphire Sapphire Oxidation + metalization 2) 3) 4) 5) 6) 7) n-island n- n+n+ p+p+ n+n+ Principles of VLSI Design...
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This note was uploaded on 08/23/2009 for the course CMSC 711 taught by Professor Chintanpatel during the Fall '04 term at UMBC.

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chap3_2 - Principles of VLSI Design CMOS Processing...

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