LOW-TEMPERATURE (LESS-THAN-OR-EQUAL-TO-550-DEGREES-C) FABRICATION OF CMOS TFT ON RAPID-THERMAL CVD POLYCRYSTALLINE SILICON-GERMANIUM FILMS

N-channel and p-channel metal-oxide-semiconductor (MOS) thin-film tran sistors (TFT's) have been fabricated on rapid thermal chemical vapor d eposition (RTCVD) polycrystalline silicon-germanium (poly-Si0.88Ge0.12 ) films by a low temperature (less than or equal to 550 degrees C) pro cess. These devices employ in-situ n(+) doped poly-Si0.65Ge0.35 films as gate electrodes to reduce the process time and temperature, dual-of fset spacers to reduce the electric field in the drain junction region , and silicon capping layers to protect the poly-Si1-xGex films agains t oxygen. The I-d-V-g characteristics in n-channel TFT's, as well as i n p-channel TFT's, exhibit good behavior after remote-PECVD hydrogenat ion. Further improvements on electrical properties in n-channel TFT's are limited by trap-inducing Ge behaviors in poly-Si1-xGex films.