JPS55115377A - Manufacture of silicon avalanche photodiode - Google Patents

Abstract

PURPOSE: To very easily manufacture a p-type side light incidence planar Si avalanche photodiode, by utilizing the fact that the impurity diffusion velocity in polycrystalline Si is much higher than that in single crystal Si.

CONSTITUTION: An annular polycrystalline Si growing nucleus 12 is made of a thin oxide film or the like on an n₊-type single crysral Si substrate 1. Epitaxial growth is caused while a p-type impurity is doped into the entire surface, thereby producing a polycrystalline Si layer 13 on the nucleus 12 and a p-type single crystal Si layer 2 on the exposed substrate 1. An n-type impurity is selectively diffused into the layer 13. The layer 13 is all changed into the n-type by utilizing the fact that the diffusion velocity in the layer is high. At the same time, the impurity in the substrate 1 is diffused into the layer 2 to produce an n-type region 9 surrounding the layer 13 and the nucleus 12. A challow p⁺-type region 3 is thus produced by diffusion in the surface part of the layer 2 while a pn junction is prevented from exerting an influence. An electrode 7 is fitted on the region 3 while a reflection preventing film 14 is coated on the region 3. An insulating film 10 is coated on the surface except for the film 14.

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