PREPARATION OF SEMICONDUCTOR DEVICE

摘要

PURPOSE:To improve characteristics of semiconductor device through realization of reduction in the number of manufacturing steps and high integration density by forming the graft base region with self-alignment to the emitter and base regions and through reduction in noise by covering the surface of junction area between the emitter and base regions with the oxide film. CONSTITUTION:An oxide film 22 is formed by oxidizing the n type Si substrate 21 forming the collector contact region 20 by diffusing donner impurity, the BSG film 23 and photo resist film 24 are formed and an aperture 25 is also provided. An aperture 26 is formed laterally and uniformly by overetching. Then, ion is implanted in order to form the base diffusion layer 27. At this time, the ion implanted damaged region 29 is also formed. The base region 27' and emitter region 28 are formed by the thermal treatment and simultaneously the graft base region 30 is also formed by boron diffusion from the BSG film 23. Thereafter, an oxide film 31 is formed by oxidation. The surface of junction area between the emitter region 28' and base region 27' is covered with an oxide film not containing any impurity.