Abstract: In the 28nm CMOS technologynode, Silicon germanium technology produces compressive stress in the device channel to improve PMOS electrical performance.Germanium are doped in stepped way based on selective silicon germanium epitaxial process, it can avoid the occurrence of dislocations due to higher dose of germanium and further improve the overall stress effect.Besides research, The thickness of the thin film stack and the concentration of germanium are important factors affecting device performance.Simultaneously changing the thickness of the stacked layer and the germanium concentration is better than the performance ofdevice obtained by separately changing one of the influencing factors.On state current and off state current performance(Idsat-Ioff) can improve 7%, simultaneously, Vtsat-Idsat performance, Vt-Ioff performance and DIBL also have obvious improvement.