Reduction of Local Mechanical Stress in a Transistor Using Si[sub 3]N[sub 4]/SiO[sub x]N[sub y] Contact ESL

Abstract

We have investigated the influence of a contact etch-stop layer (ESL) on the local mechanical stress in a deep sub-micrometer complementary metal oxide semiconductor (CMOS) field-effect transistor using convergent-beam electron diffraction with nanoscale resolution. By introducing a thin buffer layer of SiO x N y underneath the Si 3 N 4 contact ESL, we have shown that the compressive channel strain can be effectively mitigated, resulting in higher electron mobility and drive current in n-channel metal oxide semiconductor field-effect transistors, without undue impact on the electrical performance of p-channel transistors. Hence, the Si 3 N 4 /SiO x N y film stack is a promising alternative for contact ESL to enable high-performance CMOS devices.