The wafer is bisected along a center line 21 of a nondiffusing layer 20, and a diffusion wafer 22a having a double-layer structure of the high concentration impurity diffusion layer 19 and the nondiffusing layer 20 is formed as two wafers. そして、非拡散層20の中央線21に沿って二分割し、高濃度不純物拡散層19と非拡散層20の2層構造の拡散ウェーハ22aを2枚に形成する。 - 特許庁