layout question(10points) for correct answer

[vlsitechnology]

Why std cell height is to be a multiple of M1 pitch and why the width has to be a multiple of M2 pitch?? Any strong reason??

Can anyone explain with an example or any book for this? particular topic?

What happens if we do not maintain this? and plz explain with images so tht i can understand clearly.......


Reply me

 

[ashish_chauhan]

This is kind of convention which comes from the fact that generally during Place and Route process we make horizontal connections with M1 and vertical ones with M2 ... so to make easier for tool to take care of drc stuff its better to make height calculations in terms of M1 pitch ...

 

[suituse]

It is related to the efficient usage of routing resouse. You can find some reasons in the cadence's LEF/DEF 5.x document.

 

[vlsitechnology]

How do we get drc violation ? Can anyone explain this with example?

 

[ashish_chauhan]

DRC voilations are basically related to the resolution limit of the foundary.

When ever ur fab tries to make a metal route (for that matter anything) it has its own tolerence band of accuracy... which simply defines how accurately the machine can route the metal without touching some other metal route on its side.

So to take care of these tolerance bands we define drc rules which say that OK two Parallel M1 lines must have a minimum difference of 'x' microns for fabrication to be successful (without shorting the two metal lines)

Hope this gives you the basic idea!!