New Observations in LOD Effect of 45-nm P-MOSFETs With Strained SiGe Source/Drain and Dummy Gate

Length of thin oxide definition area (LOD) effects and the incorporation of the dummy poly gates on the performance of 45-nm P-MOSFETs with and without strained SiGe source/drain (S/D) are systematically investigated. In the non-SiGe devices, the LOD effect is dominated by the STI stress and shows a little dependence of dummy poly gates. However, in the SiGe device, the LOD effect is strongly dependent on the location of the dummy poly gate. For dummy poly gate located outside the active area, the compressive stress from the SiGe S/D dominates the LOD effect, but for dummy poly gate located within the active area, the LOD effect is controlled by both the SiGe S/D stress within the dummy gate and the STI stress. The mechanisms of our new observations are analyzed with TCAD simulations.