| 摘要 |
PURPOSE:To easily obtain the low density layer in an excellent reproducible manner by a method wherein the surface of a semiconductor substrate is covered by a protective material and a heat treatment is performed on the substrate. CONSTITUTION:A CVD SiO2 film of 500 deg.C is superposed on an Sb-added N type Ge 11, and when a heat treatment is performed at 650 deg.C for 36hr using a vacuum sealing method, a low density region 10 can be formed in the vicinity of the surface without roughening the surface of the substrate. Then, Be ions and B ions are implanted, and a protective ring 13 and a P<+> layer 12 are formed by performing a process at 650 deg.C in N2 for 30min. Subsequently, a CVD SiO2 film 14 is covered, and a P-side Al electrode 15 and an N-side AuGe electrode 16 are attached. According to this kind of constitution, a low density layer 10 can be accomplished in an excellent reproducible manner, and the generation of recombination center on the obtained P<+>N<-> type Ge avalanche photodiode is markedly reduced, thereby enabling to eliminate the deterioration of voltage and current characteristics. |
