Differences between Polysilicon 1 and polysilicon 2

[biolycans]

Hi,

Do you know the differences between the polysilicon 1 and the polysilicon 2 ?

Why I used this two materials to form a capacitor ? is there a reason or an advantage between the other materials (Metal 1, 2, 3 , etc) ?

Thank you !

Regards,

JC

 

[dick_freebird]

Poly1 is the usual CMOS gate electrode. It's going to be
there on any CMOS flow.

Poly2 is a cheap and easy way to get an isolated capacitor
for "mixed signal" applications. You can deposit or grow a
thin dielectric, lay down poly2, and there's your "POP cap".

This dielectric is meant to maximize areal capacitance,
while the poly-M1, M1-M2, M2-M3, ... dielectrics are
aimed at the oppposite (low interlayer capacitance) on
the one hand, but limited by things like via-filling, step
coverage and simple time-in-tube cost to a less than
infinite thickness.