Laterally diffused MOS transistor device having reduced surface field

摘要

The MOS transistor has a reduced surface field strength and includes an n-type semiconductor layer and a p-type trough formed in the layer. An n-type trough is formed in the initial trough and it contains a source region, a channel region, and a drain region. On the channel region is formed a gate electrode such that the p-type trough serves as a drift region. On voltage application, the MOS transistor is in non-active state. On application to the drain of a HV exceeding a preset value, a current path is formed. This path extends from the p-type trough over the n-type trough and the semiconductor layer.