Patent ID: 8536053

Claim:
A method for restricting lateral encroachment of a metal silicide into a channel region, comprising: providing a semiconductor substrate, a gate stack being formed on the semiconductor substrate, a source region being formed in the semiconductor on one side of the gate stack, and a drain region being formed in the semiconductor substrate on the other side of the gate stack; forming a sacrificial spacer around the gate stack and on the semiconductor substrate; depositing a metal layer for covering the semiconductor substrate, the gate stack and the sacrificial spacer; performing a thermal treatment on the semiconductor substrate, thereby causing the metal layer to react with the sacrificial spacer to produce non-metal-silicide products and causing the metal layer to react with the semiconductor substrate in the source region and the drain region to produce metal-silicide products; and removing the sacrificial spacer, the non-metal-silicide products of the sacrificial spacer and the metal layer, and a part of the metal layer which does not react with the sacrificial spacer.