METHOD OF MAKING A BIPOLAR JUNCTION TRANSISTOR

摘要

A method of making a bipolar junction transistor includes providing a substrate (10) having an n-type collector region (13) therein. A thin layer of polycrystalline or amorphous silicon (19) is formed by LPCVD while in-situ doping the silicon with boron as it is deposited. The deposited layer is thermally annealed to recrystallize the deposited silicon, thereby forming an epitaxial base region (11), having an abrupt junction with the collector region (13). A portion of the deposited silicon is then implanted with boron ions to form a base contact region (37). Next, a layer of LPCVD silicon doped with arsenic or phosphorus is provided and formed to provide an emitter region (51) and a collector contact region (52), a further annealing step increasing the concentration of active donors in these regions (51, 52) while simultaneously annealing the base contact region (37). Controlled annealing can result in the retention of a polycrystalline emitter structure.