Glenn W. Gale

REMOVAL OF PARTICULATE CONTAMINANTS USING ULTRASONICS AND MEGASONICS: A REVIEW

Sonic cleaning is a commonly used technique for removal of particles from surfaces. The theory of particle removal using ultrasound is reviewed. Effects of cavitation and acoustic streaming are discussed. Experimental results using ultrasonics and megasonics (ultrasonic cleaning near 1 MHz) from the literature are reviewed. Emphasis is placed on removal of fine particles from silicon surfaces for semiconductor manufacturing applications.

ROLES OF CAVITATION AND ACOUSTIC STREAMING IN MEGASONIC CLEANING

Despite wide use of megasonics in the semiconductor industry, the physics of megasonic particle removal remains largely unexplained. Mechanisms of particle removal in sonic baths are discussed, including the effects of operating parameters such as frequency, temperature, and power density. Experimental results are related to the theory, showing both cavitation and acoustic streaming as important components of the megasonic process.