| 摘要 |
PURPOSE:To make it possible to control breakdown voltage merely by the depth of a groove by providing an electrode to cover at least the whole face of the bottom of a groove, and interposing a resistance at the specified value between an electrode and an emitter layer of an auxiliary thyristor. CONSTITUTION:A groove 8 having a square section is formed in a P base layer 3 surrounded by an N emitter layer of an auxiliary thyristor, and the inner face of the groove 8 is covered with an electrode 9 made by deposition of metal, and this electrode is extended to the part 91 covering the surface of a layer 3. The breakdown voltage generated by application of overvoltage to between an anode electrode 5 and a cathode electrode 6 depends upon the depth of the groove 8. Further, a groove 10 is formed between the extension part 91 of the electrode 9 and the auxiliary electrode 7. Since horizontal resistance in a layer 3 right below it becomes high by this groove 10, the breakdown current generated at overvoltage application is given to an auxiliary N emitter layer 41 as a proper gate current. The gate current value varies with the breakdown current value and the depth of the groove 10. Hereby, it becomes a proper gate current and the auxiliary thyristor can be turned on. |
