The document discusses the Well Proximity Effect (WPE) where transistors located near the edge of a well will have different thresholds and currents compared to those located remotely from the edge. The WPE effect occurs for all types of MOS transistors including standard, high, low, and thick/thin oxide devices. It provides a diagram from an IC Mask Design course illustrating the WPE effect.

1. WPE (Well Proximity Effect)
NMOS or PMOS that are close to the edge of a well will exhibit a difference in
threshold and Id from that of the device located remotely from the edge.
The WPE effect occurs to every MOS: standard V t , high V t , low V t , thick/thin oxide
MOS.
Below is a diagram which is taken from the IC Mask Design training course on VDSL
(Very Deep Sub Micron Layout)
Fig .1 WPE Effect