| 摘要 |
PURPOSE:To provide an electrode structure which suppresses a noxious eutectic layer growing on an interface between a silicon element surface and a gold-gallium alloy layer, by defining a ratio of a thickness of a silver layer and that of the gold-gallium alloy layer directly coated on the silicon element, above a specified value. CONSTITUTION:Formed over an n<++> type silicon substrate 1 is an n<+> type epitaxial layer 2 over which a protective film 3 is formed. In an exposed section of the n<+> type epitaxial layer 2 where a portion of the protective film 3 is being removed, a p<+> type region 4 and an n<+> type region 5 are formed in the direction of the device thickness to constitute a p-n junction 6. On the surface of the p<+> type region, a gold-gallium alloy layer 7 with a predetermined thickness below 1,500Angstrom is evaporated, and a silver layer 8 with a thickness of 10,000Angstrom is formed thereon. In this way, by defining a ratio of a thickness of the silver layer 8 and that of the gold-gallium alloy layer 7 above 6.6, when the silicon element is heated to a sealing temperature, Ag-Au-Si ternary eutectic is formed, so that a growth of an eutectic layer to be formed on the interface between the p<+> type region and the gold-gallium alloy layer can be suppressed and thus increase of the leak current can be prevented. |
