Silicon on insulator type semiconductor device

Abstract

The present invention provides a silicon on insulator type semiconductor device including a transistor, a diode and a power source line. The transistor includes an insulator, a silicon film with which the insulator is selectively covered to form a device formation region, a gate insulating film with which the device formation region is covered, a gate electrode formed on the gate insulating film, a region having first conductivity and formed in the silicon film below the gate electrode across the gate insulating film, and source and drain regions both having second conductivity and formed in the silicon film in self-aligned fashion about the gate electrode so that the region is sandwiched between the source and drain regions. The diode is in electrical connection with the transistor through the drain region. Both the diode and the source region of the transistor are electrically connected to the power source line. Thus, the diode is forward biased to provide a path for electric charges running therethrough when an excessive negative or positive potential is applied to the drain region of the transistor. As a result, the invention provides an SOI semiconductor device having improved resistance to electrostatic breakdown relative to a conventional SOI semiconductor device.