ANOMALOUS REVERSE SHORT-CHANNEL EFFECT IN P+ POLYSILICON GATED P-CHANNEL MOSFET

Abstract

The boron-penetration-dependent Reverse Short Channel Effect (RSCE) on the threshold voltage is observed for short channel p+ poly-gate PMOSFET's. The RSCE is found to be more significant as the boron penetration becomes more severe. The RSCE is significant in BF2 doped poly-gated MOS devices and is alleviated in buffered poly-gated MOS devices. Fluorine enhanced boron diffusion in the gate oxide during high temperature process is believed to account for the RSCE, which is also confirmed by using a two-dimensional process simulator.