Field effect transistors having different stress control liners and method of making the same

Abstract

A first field effect transistor and a second field effect transistor are formed on a substrate. A silicon nitride liner is formed over the first field effect transistor and the second field effect transistor. An upper portion of the silicon nitride liner is converted into a thermal silicon oxide liner. A lower portion of the silicon nitride liner remains as a silicon nitride material portion. A first portion of the thermal silicon oxide liner is removed from above the second field effect transistor, and a second portion of the thermal silicon oxide liner remains above the first field effect transistor. Selective presence of the silicon oxide liner provides differential stress within the channels of the first and second field effect transistors, which can be employed to optimize performance of different types of field effect transistors.