COLLECTING METHOD FOR POLISHED WAFER

PURPOSE:To prevent breakage and damage of a wafer by separating upper and lower fixing boards in a water or the other liquid bath at the time of collecting a polished wafer. CONSTITUTION:A wafer 5 held by a carrier 4 is clamped by upper and lower surface plates 1, 2 under suitable pressure, and while an abrasive liquid is supplied from an abrasive liquid supply port 8, the surface plates 1, 2 are relatively rotated. After the completion of polishing, the rotation of the surface plates 1, 2 is stopped, and enough quantity of water 12 to force the upper and lower surface plates 1, 2 which still clamp the wafer 5 to sink is supplied in a pan 11. After the water is supplied into the pan 11, the upper and lower surface plates 1, 2 are lowered to be sunk in the water 12, and when the water 12 enough permeates into a polishing area between the surface plates 1, 2, the lower surface plate 1 is a little lowered to be sunk. At this time, the wafer 5 follows the lower surface plate 1 and sinks together with the carrier 4. The abrasive liquid remaining in a water bath is diluted by the water 12 to weaken the surface tension. Subsequently, after the surface plate 2 is raised largely, the lower surface plate 1 is raised to let the wafer 5 escape upward from the bath of water 12 to be collected.