Design, fabrication, and testing of surface acoustic wave devices for semiconductor cleaning applications

•Physical surface cleaning is encountering difficulties in semiconductor manufacturing due to damage to surfaces or fine structures•Research is underway to develop mechanical cleaning techniques which achieve desired particle removal with limited damage•Piezoelectric acoustic transducers operating above 300 MHz were simulated, designed, and fabricated to test ability to remove particles•Removal of 50 nm PSL from bare Si and patterned SiO2 lines was demonstrated, and is discussed with respect to physical mechanisms

Numerous cleaning steps are utilized in the production of IC's in semiconductor facilities, involving the consumption of considerable amounts of energy and chemical cleaning agents. Sonication of surfaces containing particulate defects is one of the cleaning methods used to enhance particulate removal and increase device yield. The mechanisms of action achieving this particle removal are generally considered to involve contributions from two physical phenomena: 1) acoustic cavitation and 2) acoustic streaming. In efforts to reduce damaging effects of sonication, while enhancing the ability to remove particles of decreasing sizes, semiconductor tool manufactures have historically increased the operating frequencies moving from ultrasonics, characterized by frequencies in the kHz range, to megasonics, with frequencies in the low MHz range. This work focuses on the development of various MEMS acoustic transducers designed for efficient operation at frequencies in the hundreds of MHz. Design, fabrication, and results of testing exploring the ability of these devices to remove nano-scale particles is presented and discussed.

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