FIELD-EFFECT TRANSISTOR AND METHOD FOR MANUFACTURING FIELD-EFFECT TRANSISTOR

In a field-effect transistor of the present invention, the gate electrode is a metal gate electrode containing ruthenium and the gate insulating film is composed of an oxide of a rare earth element, a silicate or an aluminate of a rare earth element, or an oxide containing a rare earth element, aluminum and silicon. With this constitution, the field-effect transistor has attained such effects that the threshold voltage of a P-channel MOSFET is within the range from -0.5 V to 0 V, the threshold voltage of an N-channel MOSFET is within the range from 0 V to +0.5 V, and the On/Off current ratio is not less than 104.