Patent ID: 7238968

Claim:
A unitary semiconductor device, comprising: a semiconductor element including a flat surface formed by removing an apex part of a substantially spherical semiconductor crystal made of a p − type or n − type semiconductor; a first exterior layer comprising a diffusion-mask film formed over the flat surface and extending beyond said flat surface over a neighboring area of said semiconductor element; a second exterior layer comprising a diffusion layer or semiconductor thin-film deposition layer formed on an outer surface of the semiconductor element excluding the flat surface and a substantially spherical pn junction formed with the semiconductor element via contact of the diffusion layer or semiconductor thin-film deposition layer, said substantially spherical pn junction being separated from a perimeter of said flat surface by a portion of said outer surface of said semiconductor element lacking a pn junction; a third exterior layer comprising an antireflective coating formed over the second exterior layer and not over the first exterior layer; a first electrode penetrating said first exterior layer so as to directly contact the flat surface of the semiconductor crystal; a second electrode penetrating said third exterior layer so as to directly contact said second exterior layer at an apex on the opposite side of the flat surface; and said first and second electrodes facing each other with a center of the semiconductor element interposed therebetween.