Meaning of overhang in the vlsi layout

[VirtuosoDracula]

Hi,

Can anybody please explain me the meaning of overhang with reference to the vlsi layout?

Thanks,
VD!

 

[erikl]

Find here a definition from the Library Compiler Physical Libraries User Guide: View attachment overhang-definition.pdf

 

[VirtuosoDracula]

Thanks erikl!

I also read somewhere, that metal gate had to overhang to cover source and drain properly, which leads to increase in overlap parasitic capacitances.

Thanks once again for your help!

 

[erikl]

... which leads to increase in overlap parasitic capacitances.

That's correct, but unavoidable, because overhang/overlap has to balance for inaccuracies of lithography and mask misalignment.