Water and Bubble Motions Under Megasonic Wave in a Silicon Wafer Wet Cleaning Bath

Abstract

The influences of a megasonic wave on water and bubble motions in a wet cleaning bath used for 300 mm-diameter silicon wafers were studied. The water motion in the entire bath was observed using a tracer of water-soluble blue-colored ink. The megasonic wave accelerated the water motion in the entire bath, although the water motion under no megasonic wave tended to be localized. The motion of small bubbles generated by the megasonic wave was also traced over the entire wafer surface. The bubble transport rate was shown to be increased by the megasonic wave and water flow.