A9 半導体超音波洗浄における超音波キャビテーションとOHラジカル生成
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概要
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The new semiconductor cleaning system by means of radicals generated by acoustic cavitation has been studied. In the high temperature and high pressure field generated by cavitation collapse, water is thermally decomposed to OH radical and H radical. In order to make radicals more effectively, it is very important to analyze in detail the relationship between the generation of radicals and the behavior of acoustic cavitation. In this study, we measure the amount of OH radicals generated by acoustic cavitation, and observe cavitation by using high-speed camera. First, the amount of OH radicals in the focused ultrasound field was measured with KI dosimetry. This time, the ultrasound was irradiated to Ar-saturated and He-saturated water. In both cases, the amount of radicals increased as the amplifier output increased. Comparing both cases, the amount of radicals in the case of Ar was larger than that in the case of He. Second, the acoustic cavitation was observed by high-speed camera. When ultrasound amplifier output increased from low level, cavitation occurred at the focal point of ultrasound firstly. As the output power became larger, the cavitation generated from the front of geometric focal point of the transducer. At much higher output, cavitation density became very high, and the density at the geometric focal point decreased. Comparing the cavitation behavior in Ar-saturated water to that in He-saturated water, the outline of cavitation distribution was almost same. But in the case of Ar, the cavitation density was larger. It is indicated that this result is related to solubility; the solubility of Ar is higher than that of He. This is one of the reasons that more amount of radicals is generated in Ar-saturated water than in He-saturated water.
- 日本ソノケミストリー学会の論文
- 2005-10-14