| 摘要 |
PURPOSE:To increase the adhesive strength for the case located on the reverse side by a method wherein, at the same time when the diffusion process for high density impurity is performed on the surface, photoetching is performed on the semiconductor wafer having a high density diffusion layer of 10<20>atom/cm<3> generated on the back side, and the density of the back side is reduced to 10<20>atom/ cm<3> or below. CONSTITUTION:A P type base layer 3 is formed by diffusion on the N<-> type epitaxial layer 2 which was surrounded by an SiO2 film 8 to be used for insulation isolation, an N<+> type emitter layer 4 and an N<+> type collector contact layer 5 are provided in the base layer 3 and an NPN transistor, having a layer 2 as a collector, is constituted. Then, the reverse side of a semiconductor chip 20 is fixed by adhesion on the bottom face of the case, but as the impurity density of the N<+> diffusion layer 6, located on the reverse side of a P type substrate 1, generated when the layers 4 and 5 were formed, is 10<20>atom/cm<3> or above, no excellent adhesive strength is obtained. Therefore, the impurities are removed until the surface having 10<20>atom/cm<3> or below is exposed by performing photoetching on the layer 6, and the adhesive strength is increased by reducing the density of impurities. |
