Performance enhancement of c-CESL-strained 95-nm-gate NMOSFET using trench-based structure

A stress modulation technology using a trench-based structure for strained NMOSFET is reported in this paper. With this technology, NMOSFET can be improved by a compressive contact etch stop layer (CESL), whereas the traditional CESL-strained NMOSFET requires a tensile one. To confirm this idea, a 95-nm-gate device with a-2.5 GPa strained CESL is simulated to investigate the effects of the trench-based structure on channel stress. It is demonstrated that the average longitudinal channel stress is transformed from-333 into 256 MPa, which leads to a significant improvement of the device's I- V performance. For strained CMOS, this approach provides a potential alternative besides dual stress liner technology.