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The impact of the Si cap/SiGe layer on the Hf-based high-k /metal gate SiGe channel pMOSFET performance and reliability has been investigated. We proposed an optimized strain SiGe channel with a Si cap layer to overcome the Ge diffusion and confine the channel carriers in the strained SiGe layer without the formation of a significant parasitic channel at the interface. With this optimized Si/SiGe stack channel, a high-performance Hf-based high-k/metal gate SiGe pMOSFET can be obtained with an appropriate VTH (~0.3 V), low C -V hysteresis ( <; 5 mV), and better ION - IOFF , VTH rolloff, and VTH stability. By the way, the related interface trap density in the high-k gate stack layer can also be reduced, thus improving the device's NBTI and HCI stressing-induced reliability.