| 摘要 |
PURPOSE:To compose a clamp diode of high reliability by a method wherein one region of one conductivity type which composes the diode is formed narrower than the other region, in the product which forms the clamp diode in a semiconductor substrate. CONSTITUTION:The transistor part A is composed by successively forming the base layer 3 and the emitter layer 5 on an epitaxial layer 1 formed on the substrate serving as the collector. On the other hand, the region 2' of high concentration and one conductivity type and the region 4 of high concentration and reverse conductivity type are formed in the epitaxial layer 1, in contact with the base layer 3. Parts B and B' composed of the base layer and these regions 2' and 4' compose a clamp diode and absorb the high voltage generated at the time of switching. In this diode part, the region 4 of reverse conductivity type which serves as the second base is so composed as to form a planar form wider than the region 2' of the conductivity type. Since the breakdown at the diode part can be generated over the entire surface of the junction, a clamp diode of high reliability can be composed. |
