Fabrication and characterization of bipolar transistors with in-situ doped low-temperature (800 degrees C) epitaxial silicon

The authors report the fabrication of bipolar transistors at a maximum process temperature of 800 degrees C, utilizing in situ doped low-temperature epitaxial silicon deposited by ultralow-pressure chemical vapor deposition (U-LPCVD), and their subsequent characterization. The epitaxial silicon layers form the collector, base, and emitter layers. To attain a high donor concentration in the epitaxial emitter layer, the U-LPCVD process is plasma enhanced. Transistors having excellent DC characteristics down to collector currents of approximately 10 pA/ mu m/sup 2/ are obtained, which indicates that the bulk quality of the epitaxial films is good enough for device fabrication.<>