PURPOSE: To improve the switching speed of a semiconductor device by forming an ion implanted layer not affected by conductivity type at predetermined portion in a semiconductor substrate and collecting diffused gold in the layer.

CONSTITUTION: A P-type impurity is adhered at 4 through an opening 3 of the insulator film 2 of an N-type substrate 1, argon (Ar) ion or the like is implanted without adverse effect to its conductivity to thereby form an ion implanted layer 8 in parallel with the main surface in predetermined depth. It is diffused from the layer 4 by heat treatment, a P-type base layer 5 is formed so as not to reach the layer 8. Then, phosphorus is diffused in part of the layer 5 to thereby form an N- type emitter layer 6 thereat, gold 7 is deposited on the substrate 1. Then, it is thermally treated to thereby diffuse gold in the layer 7 into the entire substrate. Finally, electrodes are provided on the substrate 1 and the layers 5, 6. According to this configuration, the gold is collected greater in the layer 8 due to infinitesimal crystal strain residued thereat even after the heat treatment so that the life of minority carrier is short in the layer 8. Accordingly, in operation, the life of the minority carrier of the collector layer is sufficiently short to thereby improve the switching speed of the semiconductor device.