Chemical mechanical polishing apparatus with polishing pad including debris discharge tunnels and methods of operating the same

Abstract

A polishing pad for chemical mechanical polishing (CMP) contains a lower polishing pad layer including a bottom surface of the polishing pad, an upper polishing pad layer including a top surface of the polishing pad, tunnels vertically spaced from the top surface of the polishing pad and from the bottom surface of the polishing pad, such that each of the tunnels laterally extends continuously to a respective opening in a peripheral sidewall of the polishing pad, and perforation holes vertically extending from the tunnels to the top surface of the polishing pad.

What is claimed is: 
     
         1 . A polishing pad for chemical mechanical polishing (CMP), comprising:
 a lower polishing pad layer comprising a bottom surface of the polishing pad;   an upper polishing pad layer comprising a top surface of the polishing pad;   tunnels vertically spaced from the top surface of the polishing pad and from the bottom surface of the polishing pad, wherein each of the tunnels laterally extends continuously to a respective opening in a peripheral sidewall of the polishing pad; and   perforation holes vertically extending from the tunnels to the top surface of the polishing pad.   
     
     
         2 . The polishing pad of  claim 1 , wherein the tunnels are arranged in a radial pattern such that each path from a point within the tunnels to the respective opening in the peripheral sidewall comprises a segment that extends along a radial direction from a geometrical center of the polishing pad. 
     
     
         3 . The polishing pad of  claim 2 , wherein a subset of the perforation holes is arranged as rows of perforation holes that are arranged along a respective radial direction and connected to a respective one of the tunnels. 
     
     
         4 . The polishing pad of  claim 1 , wherein the tunnels are arranged in a spiral pattern. 
     
     
         5 . The polishing pad of  claim 1 , wherein the tunnels are arranged as a network in which a first subset of the tunnels that laterally extend along a first horizontal direction intersects a second subset of the tunnels that laterally extend along a second horizontal direction that is different from the first horizontal direction. 
     
     
         6 . The polishing pad of  claim 5 , wherein the second horizontal direction is perpendicular to the first horizontal direction. 
     
     
         7 . The polishing pad of  claim 5 , wherein:
 the perforation holes are arranged as a rectangular array of perforation holes; and   each of the perforation holes is connected to a cross-point of a respective tunnel in the first subset of the tunnels and a respective tunnel in the second subset of the tunnels.   
     
     
         8 . The polishing pad of  claim 1 , wherein each of the tunnels has a uniform height and a uniform width. 
     
     
         9 . The polishing pad of  claim 1 , wherein the perforation holes and the tunnels are located in the upper polishing pad layer. 
     
     
         10 . The polishing pad of  claim 9 , further comprising an adhesive layer located between the upper and the lower polishing pad layers, wherein the lower polishing pad layer is attached to the upper polishing pad layer by the adhesive layer. 
     
     
         11 . The polishing pad of  claim 9 , wherein the upper polishing pad layer and the lower polishing pad layer comprise different materials. 
     
     
         12 . The polishing pad of  claim 9 , wherein the upper polishing pad layer comprises polyurethane, and the lower polishing pad layer comprises a non-woven material. 
     
     
         13 . The polishing pad of  claim 1 , wherein:
 the perforation holes have a respective cylindrical shape having a diameter; and   the tunnels have a respective uniform width that is greater than the diameter of the perforation holes.   
     
     
         14 . A CMP apparatus, comprising:
 a platen;   the polishing pad of  claim 1  located on a top surface of the platen;   a wafer carrier configured to hold a substrate and facing the polishing pad; and   a slurry dispenser configured dispense a slurry over the top surface of the polishing pad.   
     
     
         15 . A method of operating the CMP apparatus of  claim 14 , comprising:
 chemically mechanically polishing a substrate on the polishing pad using the slurry; and   flushing debris through the tunnels and out of the openings in the peripheral sidewall of the polishing pad that are connected to the tunnels.   
     
     
         16 . The method of  claim 15 , wherein flushing the debris comprises applying a water jet from above the polishing pad toward the perforation holes. 
     
     
         17 . A method of forming a polishing pad for chemical mechanical polishing (CMP), comprising:
 providing an upper polishing pad layer;   forming perforation holes from a top surface of the upper polishing pad layer toward a bottom surface of the upper polishing pad layer;   forming grooves by patterning the bottom surface of the upper polishing pad layer, wherein each of the perforation holes is connected to a respective one of the grooves; and   attaching the upper polishing pad layer to a lower polishing pad layer, wherein the grooves become tunnels that are bounded by portions of a planar surface of the lower polishing pad layer, and wherein each of the tunnels laterally extends continuously to a respective opening in a peripheral sidewall of the polishing pad.   
     
     
         18 . The method of  claim 17 , the grooves are arranged in a spiral pattern. 
     
     
         19 . The method of  claim 17 , wherein the grooves are arranged in a radial pattern such that each path from a point within the grooves to the respective opening in the peripheral sidewall comprises a segment that extends along a radial direction from a geometrical center of the upper polishing pad layer. 
     
     
         20 . The method of  claim 17 , wherein the grooves are arranged as a network in which a first subset of the grooves that laterally extend along a first horizontal direction intersects a second subset of the grooves that laterally extend along a second horizontal direction that is different from the first horizontal direction.