A semiconductor device includes a heat-dissipating base, a first conductive layer bonded to the top surface of the heat-dissipating base, an AlN insulating substrate bonded to the top surface of the first conductive layer, and an electrode terminal having one edge bending to form a bonding edge whose bottom surface faces the top surface of the second conductive layer and is solid-state bonded to a portion of the top surface of the second conductive layer. The crystal grain diameter at the bonded interface of the second conductive layer and electrode terminal is less than or equal to 1 μm, and indentations from the ultrasonic horn are left in the top surface of the bonding edge.