Back Junction SiGe PMOS - A New Structure with an Improved Effective Channel Mobility

We propose here a back junction SiGe PMOS structure having a cross section of Poly/SiO2/Si-cap/SiGe/n-epi/p-substrate. The electrical coupling between the front gate and the back p-substrate/n-epi junction reduces the vertical field, thus improving the hole confinement and the SiGe channel mobility, resulting in an improved effective channel mobility. Numerical simulation shows that the back junction SiGe PMOS has a higher effective channel mobility compared to the fully-depleted SOI and conventional bulk SiGe PMOS.