Semiconductor device having thermally conductive electrodes

A semiconductor device includes a semiconductor part, a first electrode at a back surface of the semiconductor part; a second electrode at a front surface of the semiconductor part; third and fourth electrodes provided between the semiconductor part and the second electrode. The third and fourth electrodes are arranged in a first direction along the front surface of the semiconductor part. The third electrode is electrically insulated from the semiconductor part by a first insulating film. The third electrode is electrically insulated from the second electrode by a second insulating film. The fourth electrode is electrically insulated from the semiconductor part by a third insulating film. The fourth electrode is electrically isolated from the third electrode. the third and fourth electrodes extend into the semiconductor part. The fourth electrode includes a material having a larger thermal conductivity than a thermal conductivity of a material of the third electrode.