Why do we always use P-sub instead of N-sub?

[road_0506]

Hello!
Why do we always use P-sub instead of N-sub?
What are its pros and cons?
Any idea would be greatly appreciated.
thanks in advance.
regards.

 

[k_90]

Re: CHIP SUBSTRATE

Hello!
Why do we always use P-sub instead of N-sub?
What are its pros and cons?
Any idea would be greatly appreciated.
thanks in advance.
regards.

*************

Substrate normally doped to be p -type for a number of reasons

In CMOS circuits the n-well and the p-substrate form a diode. This helps prevent latch up.

Substrate is resistive
Lightly doped - High resistance- useful in analog applications where noise isolation is important
Heavily doped - low resistance- useful in large scal digital where latch up may be an issue.

P -type is cheaper to make and easier to fabricate.

I can add more later once Ive finished my power point slides....68 so far!

 

[caplash_vlsi]

Re: CHIP SUBSTRATE

p-mos is preffed as a substrate to n-mos because of a lot of reasons.first of all ease of fabrication.another big reason is that mobility of charge carriers in p-mos is less then that in n-mos....so it helps in preventing i.c to form latch up state and thus prevents i.c. from malfunctioning......also leakage current is reduced using this configuration