| 摘要 |
PURPOSE:To prevent the expansion and the shrinkage of an ion injection region formed on activation by protecting the surface of a substrate with an inorganic insulation protective film when the ion injection region formed on a Ge substrate surface is activated by heat treatment. CONSTITUTION:When a Ge-avalanche photo diode is formed, an SiO2 film 2 of 1-2mum thick is covered by a CVD method an N type Ge substrate 1 having rho= 0.4OMEGA.cm. Then, a ring-shaped window 3 is formed at the film 2, P type impurity ions of Be or the like are then injected, and a guard ring 4 is formed. A circular window 5 is formed inside the window 3, and In ions are injected in the density of 1X10<15>/cm<2> or the like to form an In injection region 6. After an insulation protective film 7 of SiO2 of the like is then covered by a CVD method in the thickness of approx. 450Angstrom , the substrate is heat treated in an inert gas atmosphere of 450- 550 deg., thereby accelerating the liquid epitaxial growth of the In injection region. The film 7 may not be limited only to the SiO2, but may be to other inorganic insulation protective film. |
