Measurement of hydroxyl radicals in wafer cleaning solutions irradiated with megasonic waves

Graphical abstractDisplay Omitted Generation of OH in alkaline solutions irradiated with 1MHz waves is investigated.Terephthalic acid based fluorescence spectroscopy technique is used.Generation rate of OH increases with power density and solution temperature.Dissolved gases and type of alkali play an important role in OH generation.NH3 (aq.) is an effective scavenger of hydroxyl radicals. Megasonic irradiation of aqueous solutions produces hydroxyl radicals primarily from dissociation of water under extreme transient cavitation temperature conditions. In the current study, the effect of various sound field (~1MHz) and solution parameters on rate of generation of hydroxyl radicals in alkaline cleaning solutions of interest to semiconductor industry has been investigated. These parameters include transducer power density, liquid temperature, nature of dissolved gases, solution pH, and type of alkali. Terephthalic acid based fluorescence spectroscopy technique is used for the measurement of concentration of hydroxyl radicals.

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