PURPOSE: To form a highly reliable element excellent in the adhesion to the silicon surface of a substrate, by treating a silicon substrate on the surface of which a silicon oxide film is formed, by using hydrogen fluoride vapor, exposing the silicon surface of the substrate by etching said silicon oxide film, and treating the silicon substrate by using hydrogen or nitrogen gas plasma.

CONSTITUTION: Hydrogen radicals or nitrogen radicals contained in an plasma atmosphere are made to react with fluorine atoms bonded to a silicon substrate, by treating the substrate with hydrogen or nitrogen gas plasma. Thereby fluorine is made to leave the silicon surface of the substrate and turned into hydrogen fluoride or nitrogen trifluoride. As a plasma process equipment, a cylindrical type plasma equipment or the like is used, and the plasma process conditions are the following when, e.g. a leaf type automatic plasma equipment is used; the high frequency power output is 100-1000W, the degree of vacuum (the pressure of hydrogen gas or nitrogen gas) is 50-200Torr, the stage temperature is 20-30°C, and the process time is 10-60sec.