Integrated circuit comprising a VDMOS transistor protected against overvoltages between source and gate

摘要

The n-channel VDMOS transistor described is formed in an n-type active region of an integrated circuit with junction isolation. To prevent over-voltages between source and gate which could damage or destroy the gate dielectric, a p-channel MOS transistor is formed in the same active region (13) and has its gate electrode connected to the gate electrode (17) of the VDMOS transistor, its source region in common with the source region (9) of the VDMOS transistor, and its drain region (30, 31) connected to the p-type junction-isolation region (14). The p-channel MOS transistor has a threshold voltage below the breakdown voltage of the gate dielectric of the VDMOS transistor so that it acts as a voltage limiter.