Shallow p-Type Layers in Si by Rapid Vapor-Phase Doping for High-Speed Bipolar and MOS Applications (Special Issue on Ultra-High-Speed LSIs)

概要

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Ultrashallow p-type layers have been formed using an one-wafer type reactor for rapid vapor-phase doping (RVD) with lamp annealing system. Bipolar and MOS transistors were fabricated using the system for the first time. The process includes the injection of the B_2H_6 diffusion source gas with hydrogen carrier gas at room temperature and rapid thermal annealing using lamps. Ultrashallow boron doping was achieved at 900℃ for 60 seconds; that is, the junction depths were less than 60 nm with a peak boron concentration of between 1O^lt19gt and 1O^lt20gt cmlt-3gt. The sheet boron concentrations is controlled by adjusting the flow rate of B_2H_6. 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. The threshold voltage roll-off was suppressed down to gate length of O.22 μm, while devices with BF_2-implanted source and drain showed the roll-off below 0.5 μm. Devices with RVD-source and drain thus have drain current 1.5 times higher than those with BF_2 ion implantation. RVD provides both good short-channel characteristics and high current drivability.
社団法人電子情報通信学会の論文
1996-04-25