What is Nwell Antenna Effect
Nwell is fabricated by ion Implantation, During the fabrication process, some charges are accumulated on Nwell. The charge build-up may not be from the gate to the body in CMOS, but It can also be the body(nwell) to the gate of a MOSFET. So we can say that during fabrication, before contact and metal, there can be a charge build-up on the body of a pMOS transistor (nwell) relative to the gate. Now after nwell fabrication, the next step is gate(poly) fabrication for self-alignment purposes, now if the charge on nwell is huge, then it may, damage the gate oxide under the poly, this is called as nwell antenna Effect in VLSI.
![NWELL Antenna Effect](https://siliconvlsi.com/wp-content/uploads/2022/07/NWELL-Antenna-Effect1.png)
How to Solve Nwell Antenna Effect
- We should put N+(bulk connection) to Nwell.
- The N+/P diode should provide enough leakage to prevent any damage to the gate oxide.