Non-contact surface cleaning is a desirable process in many surface cleaning applications in the semiconductor, hard disk, and nat panel display industries. The effects of power, temperature, and time on the removal efficiency of silica particles from silicon wafers are presented. Results show that removal efficiencies near 100% could be achieved using deionized water and SC1 under the right conditions. Megasonic power exerts a greater influence on particle removal efficiency than does temperature, both in water and in SC1 solution. Particle removal efficiency decreases when the ammonia content is decreased slightly from the 5:1:1 ratio, but increases again as ammonia content is further decreased. The efficiency then remains high, even for R as low as 0.01.