Polishing tool, polishing method and polishing apparatus

Abstract

A polishing tool includes a polishing surface having a spherical zone shape and having a plurality of non-contact portions provided from an inner edge to an outer edge of the polishing surface so as not to contact with a workpiece. The plurality of non-contact portions is a plurality of grooves whose widths in a circumferential direction increase from the inner edge toward the outer edge. A polishing method using the polishing tool includes: rotating the polishing tool about the central axis of rotation; and simultaneously with rotating the polishing tool, swinging relatively at least one of the workpiece and the polishing tool with a predetermined swing width, around a position where a line passing through a center of the workpiece and intersecting with the central axis of rotation passes through a center in a width direction of a spherical zone of the polishing surface, thereby polishing the workpiece.

What is claimed is: 
     
         1 . A polishing tool comprising:
 a polishing surface having a spherical zone shape and having a plurality of non-contact portions provided from an inner edge to an outer edge of the polishing surface so as not to contact with a workpiece, wherein   the plurality of non-contact portions is a plurality of grooves whose widths in a circumferential direction increase from the inner edge toward the outer edge.   
     
     
         2 . The polishing tool according to  claim 1 , wherein
 the plurality of grooves is provided radially from the inner edge toward the outer edge.   
     
     
         3 . The polishing tool according to  claim 1 , wherein
 the plurality of grooves forms a spiral pattern from the inner edge toward the outer edge.   
     
     
         4 . The polishing tool according to  claim 2 , wherein
 the polishing surface further has a plurality of second grooves extending in the circumferential direction of the polishing surface in regions of the polishing surface excluding the plurality of grooves.   
     
     
         5 . The polishing tool according to  claim 3 , wherein
 the polishing surface further has a plurality of second grooves extending in the circumferential direction of the polishing surface in regions of the polishing surface excluding the plurality of grooves.   
     
     
         6 . The polishing tool according to  claim 4 , wherein
 the plurality of second grooves is provided in every other region in the circumferential direction.   
     
     
         7 . The polishing tool according to  claim 5 , wherein
 the plurality of second grooves is provided in every other region in the circumferential direction.   
     
     
         8 . The polishing tool according to  claim 1 , wherein
 on a projection plane on which the polishing surface is projected and which is perpendicular to a central axis of rotation of the polishing surface:   an effective circumferential length of the polishing surface is defined as a circumferential length at an arbitrary diameter by removing the plurality of non-contact portions; and   if the effective circumferential length at the outer edge is different from the effective circumferential length at the inner edge, the effective circumferential length at the arbitrary diameter linearly changes from the inner edge toward the outer edge.   
     
     
         9 . A polishing method using the polishing tool according to  claim 1 , the method comprising:
 rotating the polishing tool about the central axis of rotation; and   simultaneously with rotating the polishing tool, swinging relatively at least one of the workpiece and the polishing tool with a predetermined swing width, around a position where a line passing through a center of the workpiece and intersecting with the central axis of rotation passes through a center in a width direction of a spherical zone of the polishing surface, thereby polishing the workpiece.   
     
     
         10 . A polishing apparatus comprising:
 the polishing tool according to  claim 1 ;   a pressure applying unit configured to bring the workpiece into contact with the polishing surface of the polishing tool, thereby to apply pressure to the workpiece;   a rotating unit configured to rotate the polishing tool about the central axis of rotation; and   a swinging unit configured to swing relatively at least one of the workpiece and the polishing tool with a predetermined swing width, around a position where a line passing through a center of the workpiece and intersecting with the central axis of rotation passes through a center in a width direction of a spherical zone of the polishing surface, thereby to polish the workpiece.   
     
     
         11 . A polishing tool comprising:
 a polishing surface having a spherical zone shape and having a plurality of non-contact portions provided from an inner edge to an outer edge of the polishing surface so as not to contact with a workpiece, wherein   the plurality of non-contact portions is formed by a plurality of holes, and   a density per unit area of the plurality of holes increases from the inner edge toward the outer edge.   
     
     
         12 . The polishing tool according to  claim 11 , wherein
 on a projection plane on which the polishing surface is projected and which is perpendicular to a central axis of rotation of the polishing surface:   an effective circumferential length of the polishing surface is defined as a circumferential length at an arbitrary diameter by removing the plurality of non-contact portions; and   if the effective circumferential length at the outer edge is different from the effective circumferential length at the inner edge, the effective circumferential length at the arbitrary diameter linearly changes from the inner edge toward the outer edge.   
     
     
         13 . A polishing method using the polishing tool according to  claim 11 , the method comprising:
 rotating the polishing tool about the central axis of rotation; and   simultaneously with rotating the polishing tool, swinging relatively at least one of the workpiece and the polishing tool with a predetermined swing width, around a position where a line passing through a center of the workpiece and intersecting with the central axis of rotation passes through a center in a width direction of a spherical zone of the polishing surface, thereby polishing the workpiece.   
     
     
         14 . A polishing apparatus comprising:
 the polishing tool according to  claim 11 ;   a pressure applying unit configured to bring the workpiece into contact with the polishing surface of the polishing tool, thereby to apply pressure to the workpiece;   a rotating unit configured to rotate the polishing tool about the central axis of rotation; and   a swinging unit configured to swing relatively at least one of the workpiece and the polishing tool with a predetermined swing width, around a position where a line passing through a center of the workpiece and intersecting with the central axis of rotation passes through a center in a width direction of a spherical zone of the polishing surface, thereby to polish the workpiece.