SURFACE TREATMENT

PURPOSE:To form a thin film excelling in adhesion property and insulation property on the surface of a substrate by irradiating the surface of the substrate with accelerated particles while metal is vapor deposited and forming a metal compound whose concentration is decreased from the surface to the inside. CONSTITUTION:In a vacuum chamber 1, metal vapor 7 from an evaporation source 6 is deposited on the surface of a substrate 3 on a substrate holder 2, and also the surface of the substrate 3 is irradiated with accelerated ion beams 5 from an ion source 4. In this way, a metal compound is formed on the surface of the substrate 3, and the concentration of the metal oxide is decreased from the surface of the substrate to the inside to have no distinct boundary of the substrate. As the substrate 3, a practical material consisting of aluminum, copper, iron and their alloy or the like is used. As metal for vapor deposition, aluminum, silicon, copper, their alloy or the like is used. When oxygen ions are used as the accelerated particles, an insulating thin film of oxide such as aluminum oxide is formed as the metal compound.