Development of Silica Polyvinyl Alcohol Wheels for Wet Mirror Grinding of Silicon Wafer

It is strongly desired to develop a cup grinding wheel which enables mirror finishing of a device wafer on the same machine after back grinding. Silica wheels have the capability of mirror finish in a dry condition but there remain serious problems in flatness and thermal damage to a dicing tape. A new silica wheel which can be used in a wet condition has been developed. The PVA (polyvinyl alcohol) was adopted as the bonding agent, by which the absorbent swell resulted in disturbance of water infiltration to the inside in cup grinding. A series of experiments show that mirror finishing will be achieved within 2 min. This could not be accomplished utilizing phenol wheels.