A novel poly-silicon-capped poly-silicon-germanium thin-film transistor

Poly-silicon-capped (poly-Si-capped) polysilicon-germanium (poly-Si/sub 1-x/Ge/sub x/) thin-film transistors (TFTs) have been designed and fabricated with the aim to improve performance of load devices in high-density mega-bit SRAM cells. Poly-Si-capped poly-Si/sub 1-x/Ge/sub x/ TFTs utilize the excellent interface between oxide and poly-Si interface as well as the higher mobilities of poly-Si/sub 1-x/Ge/sub x/. P-channel poly-Si-capped poly-Si/sub 1-x/Ge/sub x/ TFTs show superior device results compared to similarly-processed poly-Si TFTs.