[SOLVED] doubt in well proximity effect

[samabraham]

I have seen in PDKs spacing for NMOS from Nwell. Can anyone explain how an NMOS will get affected during Nwell fabrication??:!:
please help...

 

[erikl]

See this freescale presentation:

 

[samabraham]

See this freescale presentation:

Thanks for the document. But how an NMOS will be affected during implantation of Nwell , NMOS portion will be covered by photoresist during fabrication of Nwell.Please check the attachment.

 

[dick_freebird]

Implantati scattering and subsequent side diffusion during
the well drive are statistical processes and some dopant
tail may get to the P- where the NMOS lives, shifting its
threshold (at least, in the regions near the Nwell).

Some finite safe distance for a given max VT shift has to
be declared.

 

[erikl]

... how an NMOS will be affected during implantation of Nwell , NMOS portion will be covered by photoresist during fabrication of Nwell.

I think in this case the reason isn't WPE, but STI stress, s. slides 18 ff. of the a.m. presentation.