Is it possible gate oxide thickness of NMOS n PMOS are different in same technology?

[Nurahmad]

When I am using BSIM4 level=60 MOS model, I read these:

NMOS: toxe=2.4948e-009
PMOS: toxe=2.5555e-009

Same technology, but gate oxide (SiO2) thickness are different, does it possible?

Than means gate oxide capacitance per unit area (Cox) are also different for NMOS n PMOS...

 

[dick_freebird]

This looks like a trivial difference to me, possibly just statistical.

But there are phenomena which change the "electrical Tox"
relative to "optical Tox", such as poly depletion (tending to be
worse in the P type poly since boron is up-taken by the glass).

If the models are fitted individually in isolation then it's possible
that such fundamental params could diverge beyond realistically.
This comes down to philosophy and execution. Forcing the fit
process to keep common params common, wants some higher
level thought.

 

[erikl]

... there are phenomena which change the "electrical Tox"
relative to "optical Tox", such as poly depletion (tending to be
worse in the P type poly since boron is up-taken by the glass).

Also, the (silicon-extracted) toxe value considers the interstate (SiO₂-Si) fixed charge density, which could well be different on p- and n-Si .