Grinding wheel, grinding apparatus and grinding method

Abstract

The present invention provides the grinding wheel, the grinding apparatus and the grinding method of the present invention so that increase in the size of the grinding apparatus can be suppressed, and the back surface grinding of the wafer and the grinding of the peripheral edge part of the wafer are performed at the same time, whereby the peripheral edge part of the extremely thin wafer is prevented from being sharpened, and cracking and chipping of the wafer peripheral edge part can be prevented.

1 . A grinding wheel, comprising: 
 a cup-shaped grindstone; and    a small-diameter grindstone provided at a center part of an inside of the cup-shaped grindstone.    
     
     
         2 . The grinding wheel according to  claim 1 , wherein the small-diameter grindstone is a grindstone in a cylindrical shape or a truncated cone shape.  
     
     
         3 . The grinding wheel according to  claim 1 , wherein the small-diameter grindstone has an entire shape formed into a truncated cone shape, and a clearance groove is formed at a mid-portion of an inclined side surface of the truncated cone.  
     
     
         4 . The grinding wheel according to  claim 1  wherein the small-diameter grindstone is integrally formed at a base of the cup-shaped grindstone.  
     
     
         5 . The grinding wheel according to  claim 2  wherein the small-diameter grindstone is integrally formed at a base of the cup-shaped grindstone.  
     
     
         6 . The grinding wheel according to  claim 3  wherein the small-diameter grindstone is integrally formed at a base of the cup-shaped grindstone.  
     
     
         7 . The grinding wheel according to  claim 1  wherein the small-diameter grindstone is detachably provided at a base of the cup-shaped grindstone.  
     
     
         8 . The grinding wheel according to  claim 2  wherein the small-diameter grindstone is detachably provided at a base of the cup-shaped grindstone.  
     
     
         9 . The grinding wheel according to  claim 3  wherein the small-diameter grindstone is detachably provided at a base of the cup-shaped grindstone.  
     
     
         10 . The grinding wheel according to  claim 1  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         11 . The grinding wheel according to  claim 2  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         12 . The grinding wheel according to  claim 3  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         13 . The grinding wheel according to  claim 4  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         14 . The grinding wheel according to  claim 5  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         15 . The grinding wheel according to  claim 6  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         16 . The grinding wheel according to  claim 7  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         17 . The grinding wheel according to  claim 8  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         18 . The grinding wheel according to  claim 9  wherein the small-diameter grindstone is a composite grindstone with a rough grinding grindstone and a fine grinding grindstone being stacked.  
     
     
         19 . A grinding apparatus which grinds one surface of the wafer, comprising: 
 a chuck table which rotates with a wafer placed thereon;    a hollow spindle which is provided eccentrically with respect to an axis of rotation of the chuck table and mounted with a cup-shaped grindstone on a tip end of the hollow spindle;    a small spindle which is provided by being inserted through the hollow spindle and mounted with a smaller-diameter grindstone than the cup-shaped grindstone on a tip end of the small spindle;    a cup-shaped grindstone driving motor which rotationally drives the hollow spindle;    a small-diameter grindstone driving motor which rotationally drives the small spindle; and    a cut-in driving device which brings the hollow spindle and the small spindle, and the chuck table relatively closer to and away from each other in the rotational axis direction of the chuck table.    
     
     
         20 . The grinding apparatus according to  claim 19 , further comprising a transverse driving device which brings an axis of the hollow spindle and an axis of the small spindle, and a rotational axis of the chuck table relatively closer to and away from each other.  
     
     
         21 . A grinding method for grinding one surface of a wafer placed on a rotating chuck table, comprising the step of: 
 grinding one surface of the wafer with the cup-shaped grindstone and grinding a circumferential side surface of the wafer with the small-diameter grindstone with using the grinding wheel according to  claim 1 .    
     
     
         22 . A grinding method, comprising the steps of: 
 mounting a cup-shaped grindstone at the hollow spindle and a smaller-diameter grindstone than the cup-shaped grindstone to the small spindle;    independently setting a number of rotations of the cup-shaped grindstone and a number of rotations of the small-diameter grindstone respectively; and    grinding one surface of the wafer with the cup-shaped grindstone and grinding a circumferential side surface of the wafer with the small-diameter grindstone with using the grinding apparatus according to  claim 19 .    
     
     
         23 . A grinding method, comprising the steps of: 
 mounting a cup-shaped grindstone at the hollow spindle and a smaller-diameter grindstone than the cup-shaped grindstone to the small spindle;    independently setting a number of rotations of the cup-shaped grindstone and a number of rotations of the small-diameter grindstone respectively; and    grinding one surface of the wafer with the cup-shaped grindstone and grinding a circumferential side surface of the wafer with the small-diameter grindstone with using the grinding apparatus according to  claim 20 .    
     
     
         24 . The grinding method according to  claim 21 , further comprising the steps of: 
 bringing the cup-shaped grindstone and the small-diameter grindstone, and the chuck table relatively close to each other in a rotational axis direction of the chuck table; and    grinding the one surface and the circumferential side surface of the wafer while bringing a rotational axis of the rotating cup-shaped grindstone and small-diameter grindstone, and the rotational axis of the chuck table relatively close to each other, or while bringing the rotational axis of the cup-shaped grindstone and the small-diameter grindstone, and the rotational axis of the chuck table relatively close to and away from each other.    
     
     
         25 . The grinding method according to  claim 22 , further comprising the steps of: 
 bringing the cup-shaped grindstone and the small-diameter grindstone, and the chuck table relatively close to each other in a rotational axis direction of the chuck table; and    grinding the one surface and the circumferential side surface of the wafer while bringing a rotational axis of the rotating cup-shaped grindstone and small-diameter grindstone, and the rotational axis of the chuck table relatively close to each other, or while bringing the rotational axis of the cup-shaped grindstone and the small-diameter grindstone, and the rotational axis of the chuck table relatively close to and away from each other.    
     
     
         26 . The grinding method according to  claim 23 , further comprising the steps of: 
 bringing the cup-shaped grindstone and the small-diameter grindstone, and the chuck table relatively close to each other in a rotational axis direction of the chuck table; and    grinding the one surface and the circumferential side surface of the wafer while bringing a rotational axis of the rotating cup-shaped grindstone and small-diameter grindstone, and the rotational axis of the chuck table relatively close to each other, or while bringing the rotational axis of the cup-shaped grindstone and the small-diameter grindstone, and the rotational axis of the chuck table relatively close to and away from each other.