Transparent window in a polishing pad

Abstract

A polishing pad assembly for a chemical mechanical polishing apparatus includes a polishing pad having a polishing surface and a surface opposite the polishing surface for attachment to a platen, and a solid light-transmissive window formed in the polishing pad. The light-transmissive window is more transmissive to light than the polishing pad. The light-transmissive window has a light-diffusing bottom surface.

What is claimed is: 
     
         1 - 16 . (canceled) 
     
     
         17 . A polishing article for a chemical mechanical polishing apparatus, comprising:
 a polishing pad having a polishing surface, a bottom surface, and an aperture extending from the polishing surface to the bottom surface, the aperture including a first section with a first lateral dimension and a second section with a different second lateral dimension, the first section being closer to the polishing surface than the second section; and   a window positioned at least in the first section of the aperture, the window having a top surface and a lower surface, and wherein at least some of the lower surface is recessed relative to the bottom surface of the polishing pad.   
     
     
         18 . The polishing article of  claim 17 , wherein the window includes a first portion positioned in the first section of the aperture and a second portion positioned in the second section of the aperture. 
     
     
         19 . The polishing article of  claim 18 , wherein the first lateral dimension is larger than the second lateral dimension. 
     
     
         20 . The polishing article of  claim 18 , wherein the first lateral dimension is smaller than the second lateral dimension. 
     
     
         21 . The polishing article of  claim 17 , wherein the first lateral dimension is larger than the second lateral dimension. 
     
     
         22 . The polishing article of  claim 17 , wherein the polishing pad includes a covering layer with the polishing surface and a backing layer with the bottom surface. 
     
     
         23 . The polishing article of  claim 22 , wherein the covering layer is secured to the backing layer with an adhesive. 
     
     
         24 . The polishing article of  claim 22 , wherein the backing layer is softer than the covering layer. 
     
     
         25 . The polishing article of  claim 22 , wherein the first section of the aperture is formed through the covering layer and the second section of the aperture is formed through the backing layer. 
     
     
         26 . The polishing article of  claim 25 , wherein the window includes a first portion positioned in the first section of the aperture and a second portion positioned in the second section of the aperture. 
     
     
         27 . The polishing article of  claim 26 , wherein the first lateral dimension is larger than the second lateral dimension. 
     
     
         28 . The polishing article of  claim 26 , wherein the first lateral dimension is smaller than the second lateral dimension. 
     
     
         29 . The polishing article of  claim 25 , wherein the first lateral dimension is larger than the second lateral dimension. 
     
     
         30 . The polishing article of  claim 17 , wherein the plug is a polyurethane material. 
     
     
         31 . The polishing article of  claim 17 , wherein the window is secured in the aperture by an adhesive. 
     
     
         32 . The polishing article of  claim 17 , wherein the window is molded to the polishing pad. 
     
     
         33 . The polishing article of  claim 17 , wherein the top surface of the window is substantially coplanar with the polishing surface. 
     
     
         34 . The polishing article of  claim 17 , wherein the polishing pad comprises a first material having pores, and the window comprises the first material substantially without pores.