Methods of forming cmos integrated circuit devices having stressed nmos and pmos channel regions therein and circuits formed thereby

Abstract

Methods of forming CMOS integrated circuit devices include forming at least first, second and third transistors in a semiconductor substrate and then covering the transistors with one or more electrically insulating layers that impart a net stress (tensile or compressive) to channel regions of the transistors. The covering step may include covering the first and second transistors with a first electrically insulating layer having a sufficiently high internal stress characteristic to impart a net tensile (or compressive) stress in a channel region of the first transistor and covering the second and third transistors with a second electrically insulating layer having a sufficiently high internal stress characteristic to impart a net compressive (or tensile) stress in a channel region of the third transistor. A step may then performed to selectively remove a first portion of the second electrically insulating layer extending opposite a gate electrode of the second transistor. In addition, a step may be performed to selectively remove a first portion of the first electrically insulating layer extending opposite a gate electrode of the first transistor and a second portion of the second electrically insulating layer extending opposite a gate electrode of the third transistor.