| 摘要 |
PURPOSE: To obtain a ground layer that can be subjected to anode oxidation preferentially by forming it of a silicon material containing germanium and holding it between doped silicon layers, forming an amount of distortion, and generating an excessive amount of hole carriers. CONSTITUTION: A distortion layer 32 formed on a substrate 30 is mainly made of single-crystal silicon substrate and contains a small amount of electrically inactive germanium. A device semiconductor layer 34 that is deposited on the distortion ground layer 32 is preferably doped with N-type impurity, and hole electric charge developed into the inside from two adjacent N-type layers 30 and 34 is distributed essentially uniformly over the entire distortion ground layer 32. Then, a wafer is covered with a thin layer 36 of silicon nitride and is further covered with a dummy silicon oxide layer 38. The oxide dummy layer 38 and the silicon nitride layer 36 have an opening at the substrate 30 and a trench 42 for separation is formed at the opening, thus forming a ground layer that is effective for selective anode oxidation. |
