Method of forming a protecting element comprising a first high concentration impurity region separated by an insulating region of a substrate

Abstract

With a microwave FET, an incorporated Schottky junction capacitance or PN junction capacitance is small and such a junction is weak against static electricity. However, with a microwave device, the method of connecting a protecting diode cannot be used since this method increases the parasitic capacitance and causes degradation of the high-frequency characteristics. In order to solve the above problems, a protecting element, having a first n-type region—insulating region—second n-type region arrangement is connected in parallel between two terminals of a protected element having a PN junction, Schottky junction, or capacitor. Since discharge can be performed between the first and second nregions that are adjacent each other, electrostatic energy that would reach the operating region of an FET can be attenuated without increasing the parasitic capacitance.