SHALLOW P-TYPE LAYERS IN SI BY RAPID VAPOR-PHASE DOPING FOR HIGH-SPEED BIPOLAR AND MOS APPLICATIONS

Ultrashallow p-type layers have been formed using an one-wafer type re actor for rapid vapor-phase doping (RVD) with lamp annealing system. B ipolar and MOS transistors were fabricated using the system for the fi rst time. The process includes the injection of the B2H6 diffusion sou rce gas with hydrogen carrier gas at room temperature and rapid therma l annealing using lamps. Ultrashallow boron doping was achieved at 900 degrees C for 60 seconds; that is, the junction depths were less than 60 nm with a peak boron concentration of between 10(19) and 10(20) cm (-3). The sheet boron concentrations is controlled by adjusting the fl ow rate of B2H6 TO show the potential of the process, bipolar and MOS transistors were fabricated. The base regions of conventional bipolar transistors were formed by rapid vapor-phase doping. Transistors with 20-nm base and emitter were fabricated and they showed current gain of 150. Shallow source and drain of PMOS transistors were also formed. T he threshold voltage roll-off was suppressed down to gate length of 0. 22 mu m, while devices with BF2-implanted source and drain showed the roll-off below 0.5 mu m. Devices with RVD-source and drain thus have d rain current 1.5 times higher than those with BF2 ion implantation. RV D provides both good short-channel characteristics and high current dr ivability.