| 摘要 |
PURPOSE:To reduce the ON-resistance present when a transistor is in operation as well as to make the area of element smaller by a method wherein a Zener diode, which bypasses a surge, is formed between the drain and source in a horizontal type MOS (metal oxide semiconductor) transistor. CONSTITUTION:An N<+> buried layer 29 of high impurity density is provided between a P-type substrate 1 and an N-type epitaxial layer 2 which will be turned to a drain region. Also, a P-type channel region 7 reaching a layer 29 is formed and, at the same time, a P<+> Zener voltage region 28 of high impurity density is formed almost in the center part of the region 7. The upper part of the region 28 is connected to a source electrode 12 through the intermediary of a channel contact region 27, the lower part in wide area of the region 28 is brought to come in contact with the layer 29, a P<+>-N<+> junction is formed between the region 28 and the layer 29, and a Zener diode, having the prescribed Zener voltage and current capacity characteristics between the drain and the source located in a horizontal MOS transistor, is formed. |
