| 摘要 |
PURPOSE:To surely prevent a latch-up of a CMOS or the like constituting a peripheral circuit by installing a guard ring between a first region and a second region in such a way that the guard ring reaches a recombination layer. CONSTITUTION:A p-type guard ring 33 is formed in such a way that it can reach a recombination layer 35; a VDMOS 10 is formed in a first region 2a in an n<-> region isolated by this p-type guard ring 33; a p-MOS 20 and an n-MOS 30 which constitute a CMOS acting as a peripheral circuit are formed in a second n<-> region 2b. During a transient state such as a switching operation or the like, a flywheel electric current caused by an inductive load flows to a source electrode 8 of the VDMOS 10; holes as a small number of carriers are injected into the first n<-> region 2a from a p-type channel region 3. Out of the injected holes, the holes which have diffused the first n<-> region 2a and have reached the p-type guard ring 33 are absorbed immediately and are sucked out to a ground via a guard ring electrode 34. Accordingly, it is possible to surely prevent a latch-up of the CMOS constituting the peripheral circuit.
|
