Acoustic bubble array-induced jet flow for cleaning particulate contaminants on semiconductor wafers

Abstract

The demand for semiconductors and the necessity of developing the next-generation semiconductor have skyrocketed with recent technological advancements, such as next-generation mobile networks, cloud computing, the Internet of Things, and artificial intelligence. Accordingly, a new type of semiconductor cleaning technique that can minimize environmental impact and physical harm to the exceedingly thin structures in semiconductor chips must be developed. This work proposes a cleaning strategy for particle contamination on semiconductor wafer surfaces by utilizing jet flow created by bubble oscillation constrained in arrays of microcylinders. The variation in the maximum jet flow velocity caused by single bubble oscillation constrained in a microcylinder, which is affected by physical factors, such as applied voltage, frequency, and microcylinder dimensions, has been investigated. A wafer cleaning apparatus that comprised 9×9 arrays of microcylinders was designed based on experimental data on single bubble oscillation constrained in a microcylinder. The maximum jet flow velocity for the multi-arrays of microcylinders can be attained up to 148.5 mm/s, which is nearly five times the maximum value obtained from a single cylinder, even with a lower voltage applied than with a single microcylinder. The wafer cleaning apparatus removes particulates with different wettabilities and sizes from contaminated semiconductor wafers successfully with a high cleaning efficiency of up to 92.5%. The current effort makes an important contribution to the development of semiconductor cleaning techniques that can meet the requirements of current and next-generation semiconductor manufacturing in terms of yield, stability, and environmental pollution.