| 摘要 |
PROBLEM TO BE SOLVED: To provide a clearing method wherein noble metallic particles and such metal which diffuses into silicon at high speed which are difficult to be removed so far are sufficiently removed. SOLUTION: In the presence of ozone or oxygen, the surface of a natural oxide film 2 is irradiated with ultraviolet rays, so that Fe particle 4 and Cu particle 5 are oxidized to provide iron oxide 8 and copper oxide 9. Then the natural oxide film 2 is removed in a wet process, which uses a buffered hydrofluoric acid, etc., while the metal oxide is removed at the same time.
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