I know the channel width can't be smaller, but what about drain and source? Say, in 0.18u technology, what would be a typical drain/source length?
MOSFET – Can Drain and Source Length Be Smaller Than Minimum Channel Length in CMOS Technology?
chip-designcmosintegrated-circuitmosfetsemiconductor-process-technology
Best Answer
Be careful...I think you may be mixing up the "width" and "length" terms. Usually, the "length" of the transistor is the smaller dimension and is the dimension we are referring to when we talk about a "180nm process".
The long dimension of the source and drain will be the same as the long dimension (the width) of the transistor's gate, by definition.
The shorter dimension of the source and drain will be determined by design rules that are somewhat independent of the rules for the gate layer, but they will be on the same order of magnitude. However, the minimum size of a source or drain will typically be larger if there are contacts to the silicon. If the source/drain region is shared between two transistors in series then it may not have contacts and may be relatively thinner.