Method and structure for forming high-K/metal gate extremely thin semiconductor on insulator device

摘要

A semiconductor device is provided that includes a gate structure present on a substrate. The gate structure includes a gate conductor with an undercut region in sidewalls of a first portion of the gate conductor, wherein a second portion of the gate conductor is present over the first portion of the gate conductor and includes a protruding portion over the undercut region. A spacer is adjacent to sidewalls of the gate structure, wherein the spacer includes an extending portion filling the undercut region. A raised source region and a raised drain region is present adjacent to the spacers. The raised source region and the raised drain region are separated from the gate conductor by the extending portion of the spacers.