design and implementation of vlsi systems (en1600) lecture05 sherief reda division of engineering,...
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Design and Implementation of VLSI Systems(EN1600)lecture05
Sherief RedaDivision of Engineering, Brown University
Spring 2008
[sources: Weste/Addison Wesley]
Summary of Terminology• body• diffusion (n/p)• source• drain • well• tap• contact• metal track• via• polysilicon gate length/width• gate oxide• channel
All these structures must obey the dimensions and separation rules dictated by the process fabrication facility
Process design rules
• Design rules change from fab to fab
• Fab examples: IBM, Intel, TI, TSMC, UMC, MOSIS
• Design rules change according to the process technology
Lambda rules
• Feature Size: minimum distance between source and drain of transistor
• Feature size = 2λ (@ 90nm feature size λ=45)
• According to Moore’s Law, how much does the feature size scale by every ~2 years?
Design rules and gate layout
• Lambda rules are conservative
More design rules
More and more design rules
Inverters with taps
Layout of a 3-input NAND gate
Stick diagrams
• No need to be drawn to scale
Pitch of routing tracks
Gate area estimation
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