Heterogeneous 3-D Sequential CFET With Strain-Engineered Ge (100) Top-Channel pMOSFET on Bulk Si (100) nMOSFET

Abstract

In this work, we first demonstrated heterogeneous 3-D (H3D) sequential complementary field-effect transistors (seqCFETs) highlighting biaxially compressively strained Ge (sGe) (100) channel, which potentially solves a critical bottleneck in CFET development: high mobility top strained p-channel limited by the difficulty of SiGe stressor growth. Leveraging high-quality heteroepitaxial growth and direct wafer bonding (DWB), we achieved similar to 0.6% biaxially compressively sGe on a 6-in Si wafer by growing Ge virtual substrate, Si0.5Ge0.5 stressor/etch stopper, and sGe channel layer. Finally, we first demonstrated the H3D seqCFET with biaxially compressively sGe (100) p-channel MOSFETs, featuring good voltage transfer curve (VTC) characteristics with high voltage gain (V-gain) of 51 V/V at supply voltage (V-DD) = 1.25 V. We believe that the sGe channel realized by the method shown in this work will be a very promising technology to realize high-performance vertically 3-D stacked CFET in the future.