Wafer grinding method

Abstract

In a holding surface correction processing step, a shape of a holding surface is corrected by an etching mechanism in such a manner as to have a surface shape similar to that of an upper surface of a test grinding wafer having been ground in a test grinding step. As a result, at a time of a grinding step, when a holding section of a chuck table communicates with a suction source and a product wafer is held under suction on the holding surface, the holding surface becomes a substantially flat surface, and a radius part of the holding surface becomes parallel to a lower surface of a wafer grinding grindstone. Hence, it is possible to prevent partial thickness differences from being generated in the product wafer having been ground by the wafer grinding grindstone.

What is claimed is: 
     
         1 . A wafer grinding method in which a chuck table mounted to a table base is made to communicate with a suction source and a wafer held under suction by a holding surface of the chuck table is ground by a wafer grinding grindstone for grinding the wafer, the wafer grinding method comprising:
 a holding surface forming step of grinding an upper surface of the chuck table by use of the wafer grinding grindstone or a table griding grindstone for grinding the table in a state in which the chuck table does not communicate with the suction source, to thereby form the holding surface;   a holding step of causing the holding surface to communicate with the suction source and holding a test grinding wafer under suction by the holding surface, after the holding surface forming step is carried out;   a test grinding step of grinding the test grinding wafer held under suction by the holding surface in the holding step by the wafer grinding grindstone to a predetermined thickness;   a distribution measuring step of measuring a thickness distribution of a whole surface of the test grinding wafer ground in the test grinding step, or an upper surface height distribution of a whole surface of an upper surface of the test grinding wafer;   a holding surface correction processing step of subjecting the holding surface used in the test grinding step to correction processing in such a manner that a holding surface having a surface shape similar to that of the upper surface of the test grinding wafer having been ground is obtained, in reference to the thickness distribution or the upper surface height distribution measured in the distribution measuring step; and   a grinding step of holding a product wafer under suction by the holding surface and grinding the product wafer to a predetermined thickness with the wafer grinding grindstone, after the holding surface correction processing step is carried out.   
     
     
         2 . The wafer grinding method according to  claim 1 ,
 wherein the holding surface of the chuck table includes silicon, and,   in the holding surface correction processing step, partially plasmatized etching gas is jetted from an etching gas jet nozzle to the holding surface to subject the holding surface to correction processing by atmospheric-pressure plasma etching.   
     
     
         3 . The wafer grinding method according to  claim 1 , wherein, in the holding surface correction processing step, the holding surface is ground with a small-diameter grindstone having a diameter smaller than a radius of the holding surface, to thereby subject the holding surface to correction processing.