nwell connection of HV MOM capacitor (cfmom) in TSMC 0.18 HV BCD process

[xlowen]

Hi All,

In the pdk of the HV MOM capacitor(cfmom) in tsmc 0.18 BCD process, I cannot find any connection to the nwell. Do I need to make some nwell contact by myself or leave it floating?

Thanks,
xlowen

 

[erikl]

Don't leave it floating - connect it to the highest potential.

 

[xlowen]

Hi erikl,

Have you also used this process before? since the voltage across the cap will be around 70V, the nwell should be HV nwell, How do you make this nwell connection?

Thx

 

[erikl]

Have you also used this process before?

No, never.

since the voltage across the cap will be around 70V, the nwell should be HV nwell

Right!

How do you make this nwell connection?

HV nwell + nwell + n⁺ diffusion + contact(s) + metal1 --> highest potential
This guarantees lowest possible parasitic cap. between bottom cap node and GND - if required.