the process corner on the same wafer

[chang830]

hi,
When testing our silicon, I supprisly found that in the same die, some transistors seemed in SF corner while others in FS corner. I am confused with it. I tested others dies from the same wafer, they all have the same phenomena.

I wonder is it possible for a single die, the same type MOS transistors is in the different corners?

 

[derekqiao]

In same wafer the process conditions are different. But in a die, the transistors are in same corner because they are close.

 

[jcpu]

That shall be unusual.

Fisrt thing you can do,
is ask the fab to mapping those WAT key for
Vth and IDsat (40~50 shots/wafer) measurement.
See if variation match with your conclusion.

Good Luck,