Polishing pad with two-section window having recess

Abstract

A method of forming a polishing pad with a polishing layer having a polishing surface and a back surface. A plurality of grooves are formed on the polishing surface, and an indentation is formed in the back surface of the polishing layer. A region on the polishing surface corresponding to the indentation in the back surface is free of grooves or has shallower grooves.

1 - 39 . (canceled) 
     
     
         40 . A polishing pad, comprising:
 a polishing article having a polishing surface and a bottom surface, an aperture formed through the polishing article from the polishing surface to the bottom surface, the aperture having a first portion adjacent the polishing surface with a first cross-sectional width and a second portion adjacent the bottom surface with a second cross-sectional width greater than the first cross-sectional width such that a projecting section of the polishing article extends over the second portion of the aperture; and   a transparent body secured in the aperture, the transparent body including a first section positioned in the first portion of the aperture and a second section positioned in the second portion of the aperture, an upper surface of the second section adhesively secured to a lower surface of the projecting section, the transparent body including a recess formed in an underside of the second section, the recess having a cross-sectional width less than the first cross-sectional width of the first portion of the aperture, the recess extending upwardly from the underside of the second section past the upper surface of the second section and into the first section, an entirety of a region of the first section extending from the upper surface of the second section to a ceiling of the recess having straight vertical side walls.   
     
     
         41 . The polishing pad of  claim 40 , wherein the top surface of the first section of the transparent body is substantially coplanar with the polishing surface. 
     
     
         42 . The polishing pad of  claim 40 , wherein the second section of the transparent body has a thickness substantially equal to a depth of the second portion of the aperture. 
     
     
         43 . The polishing pad of  claim 40 , wherein the second section of the transparent body has a thickness less than a depth of the second portion of the aperture. 
     
     
         44 . The polishing pad of  claim 40 , wherein the polishing article comprises a polishing layer having the polishing surface and a backing layer having the bottom surface. 
     
     
         45 . The polishing pad of  claim 44 , wherein the first portion of the aperture is formed in the polishing layer and the second portion of the aperture is formed in the backing layer. 
     
     
         46 . The polishing pad of  claim 45 , wherein the upper surface of the second section is adhesively secured to a back surface of the polishing layer. 
     
     
         47 . The polishing pad of  claim 44 , wherein first section of the transparent body has the same cross-sectional width as the first portion of the aperture. 
     
     
         48 . The polishing pad of  claim 47 , wherein the second section of the transparent body has the same cross-sectional width as the second portion of the aperture. 
     
     
         49 . The polishing pad of  claim 40 , wherein the backing layer is softer than the polishing layer. 
     
     
         50 . The polishing pad of  claim 40 , comprising a plurality of grooves formed in the polishing surface, wherein the grooves are shallower than the first portion of the aperture. 
     
     
         51 . The polishing pad of  claim 50 , wherein the top surface of the transparent body is free of grooves. 
     
     
         52 . A polishing pad, comprising:
 a polishing layer having a polishing surface, a first surface on a side of the polishing layer opposite the polishing surface, and a first aperture formed through the polishing layer from the polishing surface to the first surface, the aperture having a first cross-sectional width;   a backing layer secured to the polishing layer, the backing layer having a bottom surface, a second surface on a side of the backing layer opposite the bottom surface, and a second aperture formed through the backing layer from the second surface to the bottom surface, the second aperture aligned with the first aperture and having a second cross-sectional width greater than the first cross-sectional width such that a projecting section of the polishing layer extends over the second aperture; and   a transparent body secured in the first aperture and the second aperture, the transparent body including a first section positioned in the first aperture and a second section positioned in the second aperture, an upper surface of the second section adhesively secured to the first surface of the polishing layer in the projecting section, the transparent body including a recess formed in an underside of the second section, the recess having a cross-sectional width less than the first cross-sectional width of the first aperture, the recess extending upwardly from the underside of the second section past the upper surface of the second section and into the first section, an entirety of a region of the first section extending from the upper surface of the second section to a ceiling of the recess having straight vertical side walls.   
     
     
         53 . The polishing pad of  claim 52 , wherein the top surface of the first section of the transparent body is substantially coplanar with the polishing surface. 
     
     
         54 . The polishing pad of  claim 53 , wherein the top surface of the transparent body is free of grooves.