Abstract: According to the present invention, a method of manufacturing a semiconductor apparatus is provided which comprises the steps of (a) depositing a boron layer on a silicon substrate, and (b) thermally diffusing boron from said boron layer into said silicon substrate. The present invention, which is characteristically based on the solid phase diffusion process, enables even a thin layer to be deposited. Further, unlike the ion implantation process, the present invention enables an impurity to be uniformly diffused even into an inclined plane. Unlike the case where boron-containing glass is used as a diffusion source, the invention enables a sufficient amount of boron to be diffused even at a temperature lower than 1000.degree. C.