| 摘要 |
PURPOSE:To largely take the withstand voltage difference between the breakdown voltage at guard ring parts and that at a light-receiving part and to lessen the dark current of a diode by a method wherein a low-concentration region is formed in the vicinity of the surface of the semiconductor substrate. CONSTITUTION:An SiO2 film of a prescribed thickness is formed on an N type germanium substrate 1 added with antimony and a thermal treatment is performed for a fixed time by a vacuum closed tube method for forming a low-concentration region 10 in the vicinity of the surface of the substrate 1. After that, an arsenic ion implantation is performed and an N region 2 is formed via the prescribed ion activation annealing process. Then, a beryllium ion implantation is performed, and guard ring parts 3 and a P<+> region 4 are formed via the prescribed ion activation annealing process respectively. After then, a CVD-SiO2 film 5, which is used in common as a surface protective film and a non-reflected coating, is formed. Electrodes 6 are formed on the P side and an electrode 7 on the N side, and an avalanche photodiode is constituted. As a result, the withstand voltage difference between the breakdown voltage at the guard ring parts and that at the light-receiving part can be largely taken and the dark current of the diode can be lessened. |
