| 摘要 |
PURPOSE:To improve the breakdown strength of a guard ring part when a surge voltage is applied by a method wherein a 6th semiconductor layer or a 7th semiconductor layer which is connected to a drain electrode is provided so as to be separated from the 5th semiconductor layer of the guard ring structure by a specific distance. CONSTITUTION:An n--type layer 3 having a required impurity concentration is formed on a p<+>-type layer 4 which is a semiconductor substrate. Then a p-type layer 7, p-type depositions 6 and 6' (a guard ring structure) and a p-type layer 14 are formed simultaneously by a selective diffusion method. The position of the p-type layer 14 is so determined as to have the leading edge of a depletion layer which is spread from the p-type layer 7 into the guard ring region when a voltage which is plus side from the voltage of a source electrode 9 is applied to a drain electrode 1 reach the p-type layer 14 before an avalanche breakdown is produced in the guard ring region. After an n<+>-type layer 8 is formed in the p-type layer, an interlayer insulating film 12 is formed and the source electrode 9 and a metal electrode 15 are formed. Then a drain electrode 1 formed on the rear of the p<+>-type layer 4 is electrically connected to the metal electrode 15. |
