| 摘要 |
PURPOSE:To form a gate insulating film, an epitaxial film or other CVD film of high quality by disposing a semiconductor substrate in an atmosphere containing a halogen, emitting an ultraviolet ray to etch the surface of the substrate, and then cleaning it with solution. CONSTITUTION:A semiconductor substrate is disposed in an atmosphere containing a halogen, an ultraviolet ray is emitted to etch the surface of the substrate, and the substrate is then cleaned with a solution. For example, a P-type silicon substrate is placed at a predetermined position in a chamber, chlorine gas of high purity for etching gas is introduced into the chamber. Then, an ultraviolet light having 150-350nm of wavelength is emitted toward the substrate in the gas atmosphere. Thus, the excited chlorine gas becomes chlorine of radical state to etch the surface of the substrate in depth of 10-100nm. Then, it is cleaned with flowing water, and boiled with pure water. Thereafter, a normal solution containing fluoric acid solution, hydrogen peroxide, ammonium is used for cleaning. Subsequently, the substrate is oxidized to form a thermal oxide film having approx. 20nm of thickness.
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