Substrate Contacts of NMOS and PMOS connected in opposite direction?

[sandeepp240]

HI,

PLs can anyone tell me why the Substrate contacts i.e. Bulk connections of both NMOS and PMOS transistors connected in opposite direction?

:roll::roll:

 

[arun2011]

NMOS will be formed in the p-substrate and PMOS will be formed inside the N-well (in a normal N-well process). Bulk which is the fourth terminal of the transistor should be connected in such a way that the S/D terminal and Bulk terminal must be reverse biased , hence they are connected in opposite directions for PMOS and NMOS.

 

[sandeepp240]

Thank you Arun. After I posted the above thread, I have refered some books and I have got the same answer as you posted.
Thanks again.