Transistor mobility improvement by adjusting stress in shallow trench isolation

摘要

A method of improving the carrier mobility of a transistor is presented. A trench is formed in a substrate. The trench is filled with a dielectric. A CMOS transistor is formed adjacent to the trench. A silicide layer is formed on the source/drain region. After the step of forming the silicide layer, a recess is formed by etching the dielectric so that the surface of the dielectric is substantially lower than the surface of the substrate. Recessing the STI causes the removal of the compressive stress applied to the channel region by the STI material. A contact etch stop layer (CESL) is formed over the gate electrode, spacers, source/drain region and the dielectric. The CESL applies a desired stress to the channel region. Trench liners may optionally be formed to provide a stress to the channel region. A trench spacer may optionally be formed in the STI recess.