The use of sonic energy in the 0.8 to 1.0 MHz range, commonly known as megasonic cleaning, has been shown to be effective in the removal of particles from silicon wafers in aqueous baths. Megasonic cleaning at a nominal frequency of 862 kHz is investigated experimentally. The effects of particle size, power, and sonication time on the particle removal efficiency are evaluated for submicron PSL, SiO2, and SigN4 particles on silicon wafers using both DI water and SC1 (NH4OH/H2OJH20 , first used at RCA) chemistry. The removal efficiency is known to be higher in SC1 than in DI water, and in both cases it is a function of irradiation time and particle size. Increased power is also shown to increase removal efficiency.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2015-03-22 to IP

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The use of sulfuric acid to strip photoresist from silicon wafers is a widely employed technique in the semiconductor manufacturing community. In most cases, the acid is combined with hydrogen peroxide to oxidize stripped photoresist material, though the use of sparged ozone in sulfuric solution is also used to remove resist residues on wafers following the ashing process. Although they have been used for many years, sulfuric acid processes also have proven to be costly. This is due to the need for frequent bath change-outs and the use of high temperature which impose safety and environmental concerns. As a result of these and other considerations, the use of mixtures of ozone and de-ionized water for photoresist stripping has been investigated. Results show that the technique effectively removes hard-baked resist (ashed and un-ashed) from bare silicon and patterned wafers and produces cleaner surfaces (i.e. particles and metals), compared to outcomes from SPM processes.