| 摘要 |
PURPOSE:To release metal in a solid state from a silicon wafer and to recover the metal, by forming a metal film on the silicon wafer, and dissolving silicon oxide which is formed at the interface between the metal film and the silicon wafer. CONSTITUTION:A silicon wafer is made to remain in air for two days after the evaporation of gold. Then the silicon wafer is immersed in an aqueous solution of flouric acid and ammonium fluoride at a ratio of 1:5. A gold evaporated film is released from the rear surface of the silicon wafer after two days, and the solid-state gold can be recovered. It is possible to accelerate the releasing speed of the gold-evaporated film by applying ultrasonic waves or heat to said BF liquid. This method is effective to other noble metals such as silver and platinum in addition to the gold. This method is also effective as a silicon wafer recovering method. Thus, the metal can be released from one main surface of the silicon wafer in the solid state. Complicated steps such as isolation and refining are not required, and the recovery of the metal can be implemented at a low cost and in a short time.
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