PURPOSE: To obtain semiconductor device which maintains high speed operation and provides fine Schottky barrier diodes by reducing the area of guard ring and self-alignment of the guard ring to the Schottky barrier.

CONSTITUTION: A patterned negative resist film 23 is formed and the boron ion is implanted, thereafter a positive resist film 25 is formed in the area near the region other than that where the Schottky barrier diode is to be formed, only the oxide film 15 just under the negative regist film 23 exposed from the positive resist film 25 is etched by the HF gas and thereby an aperture 26 is formed, and the Schottky metal layer 28 is then formed in such aperture 26. Thereby, the P+ type guard ring 27 and Schottky metal layer 28 are formed through self-alignment. As a result, the area of Schottky barrier can be reduced and the integration density can also be improved. Moreover, since the area of guard ring can be reduced, the junction area between the guard ring and substrate can also be reduced and accordingly deterioration of the high speed characteristic of the Schottky barrier diode can be prevented.