Layout of a n-well resistor CMOS

[biolycans]

Hi,

I designed a n well resistor and in the sofware I am using there is an option to see this layout in 3D. I did this and I saw two things:

1) The N-well material
2) A metal 1 - N-well contact

I don´t understand and I can´t find in any book clearly why in the contact I have around the diffusion N-type a p-type diffusion.

Thank you !

Regards

JC

- - - Updated - - -

I recently found that that heavily type N diffusion in the Nwell has the objetive to be an ohmic contact for metal 1, because if I connect the metal 1 directly to the Nwell, then I generate a schottky diode. But I can´t find the reason of the type P around this heavily type N diffusion in the Nwell.

Regards

JC

 

[erikl]

I can´t find the reason of the type P around this heavily type N diffusion in the Nwell.

I can't, either. Is the P diffusion inside the Nwell, or outside? Can you show a picture?