Role of ammonia and carbonates in scavenging hydroxyl radicals generated during megasonic irradiation of wafer cleaning solutions

Chemical formulations used for megasonic cleaning typically contain hydroxides, peroxides, carbonates, and others which can affect particle removal efficiency and feature damage. The current study is focused on investigating the role of carbonates in modulating the oxidation power of megasonic irradiated alkaline solutions through the scavenging of hydroxyl radicals as determined by fluorescence spectroscopy. Although studies exist in literature that report the scavenging of OH by carbonates, these studies have been conducted for waste water treatment applications using advanced oxidation processes. This work focuses on understanding the role of alkaline chemical formulations containing varying levels of carbonates and bicarbonates and solution temperatures on net generation of hydroxyl radicals for applications in semiconductor industry. Investigations were carried out at an acoustic frequency of ∼1 MHz and different power densities (2, 4 and 8 W/cm²).