PURPOSE: To enable a time constant circuit composed of a resistor and a capacitor to be formed on a semiconductor substrate uniform in quality without being affected by a temperature change.

CONSTITUTION: An N-type epitaxial layer 6 is formed on a P-type semiconductor substrate 1, the N-type epitaxial layer 6 is independently isolated by an insulating layer 3 forced in by LOCOS oxidation, two P-type diffusion layers 8 are provided to the isolated region, and a nitride film 5 is formed thereon. An aluminum layer 9 is formed on the nitride film 5 provided onto the one of the P-type diffusion layers 8, an N-type polysilicon layer 10 is formed on the other P-type diffusion layer 8, MOS capacitors composed of the P-type diffusion layers 8, the aluminum layer 9, and the N-type polysilicon layer 10 are utilized, the P-type diffusion layers 8 under the N-type polysilicon layer 10 and the aluminum layer 9 are made to serve as resistors respectively, whereby a time constant circuit can be formed on a semiconductor uniform in quality without being affected by temperature changes.