| 摘要 |
PROBLEM TO BE SOLVED: To enable flat surface grinding to be carried out without transferring almost no waving on the surface of work by performing polishing work through reduction of negative pressure to suctionwise fix the thin plate-like work at the terminal time of grinding. SOLUTION: A wafer 1 is suctionwise retained by a high vacuum pressure type negative pressure source 23 until fine grinding operation is performed, and at the transfer time to the spark-out changeover is made to a low vacuum negative pressure source 24 to perform low negative pressure suction is carried out. As a result, until the fine grinding work for performing grinding wheel cutting in is made, a work is retained with the firm suction force close to the vacuum contition, but after the transferred time of spark out at which the feeding pressure of grinding wheel is reduced or close to almost the nothing level, the suction force is reduced so that the retaining force is maintainable. Flat surface grinding can be made under the condition where the elastic deformation force of wafer 1 is released substantially until the fine grinding work and waving which can not remove due to the elastic deformation is removed, thereby maintaining the wafer shape without waving or with a less waving after being subjected to surface grinding even if the suction is released. |
