AnsweredAssumed Answered

Parasitics capacitance of metal interconnections

Question asked by lpalocko on Nov 1, 2014
Latest reply on Nov 4, 2014 by samantha_lizak

Hi everyone,


I design some cells (SRAM cells and etc.) based on Generic Design Kit, but I was a little confused, that cells has poor operating frequency. I investigated this problem and when I find files which defines parasitic value, I was very surprised. Parasitic capacitance are extremely high.


For example:


Technology GDK

- Feature size 130 nm

Capacitance intrinsic plate Poly  Mask  0.2 * area()

Capacitance intrinsic plate M1  Mask  0.1 * area()

Capacitance intrinsic plate M2  Mask  0.06 * area()


File defines unit capacitance as pF.


In comparison with:


Technology SCN018 (TSMC 0.18u)


- Feature size 180 nm


Capacitance Poly (Area) to substrate - 101 aF/um2

Capacitance M1 (Area) to substrate -  34 aF/um2

Capacitance M2 (Area) to substrate -  14 aF/um2


Resistances are the same in both technology.


Is not problem in unit capacitance? File defines unit capacitance as pF, it shouldn't be fF?


Thanks a lot!