dioxide film 64 is formed in each of these regions passivation film 63 comprising phosphosilicate glass psg is formed on the p type silicon substrate 51 and then windows not shown for producing the collector base and emitter electrodes are formed through the passivation film 63 the collector electrode and conductor 67 the base electrode and conductor 68 and the emitter electrode and conductor 69 are then formed in such a manner that an end of each of these electrodes and conductors is positioned in each of the windows not shown mentioned above in fig7 a through 7d a cmos having a nonuniform deep bulk defect region is produced by an embodiment of the process of the present invention in which the ion implantation or diffusion technique is utilized on the surface portion of fz wafer 70 fig7 a a high oxygen concentration region 71 is formed by means of the ion implantation or diffusion technique the high oxygen concentration region 71 preferably has a thickness of 5 to 10 microns and an oxygen concentration of 1 4 to 1 9 u00d7 10 18 cm 3 an epitaxial silicon layer 72 fig7 b having a thickness of 7 to 8 microns is formed on the high oxygen concentration region 71 a photoresist film 73 fig7 c is then selectively formed on the epitaxial silicon layer 72 and a high oxygen concentration epitaxial silicon region 72a is selectively formed by means of the ion implantation technique also the oxygen may be selectively diffused to form the high oxygen concentration epitaxial silicon region 72a subsequently heat treatment is carried out at a temperature of 550 u00b0 c to 900 u00b0 c so as to precipitate the oxygen as crystal defects as a.