Chemical mechanical polishing apparatus and method

Abstract

The present disclosure describes a method and apparatus to remove consumable (e.g., sacrificial) polishing pad layers from a multilayer polishing pad. For example, the method includes measuring a thickness profile of a top polishing pad layer of a multilayer polishing pad and comparing the thickness profile to a threshold. The method, in response to the thickness profile being above the threshold, rinses the top polishing pad layer of the multilayer polishing pad and removes, after the top polishing pad layer has been rinsed, the top polishing pad layer to expose an underlying polishing pad layer of the multilayer polishing pad.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a wafer polisher comprising a polishing pad, wherein the polishing pad comprises a top polishing layer;   a wafer carrier on the wafer polisher and configured to hold a wafer against the top polishing layer;   a sensor above the wafer polisher and configured to measure a surface profile of the top polishing layer; and   a laser configured to produce a laser beam aligned with the top polishing layer to remove the top polishing layer.   
     
     
         2 . The apparatus of  claim 1 , wherein the sensor is further configured to measure a vertical distance between a global high surface point of the top polishing layer and a global low surface point of the top polishing layer. 
     
     
         3 . The apparatus of  claim 2 , wherein the laser is further configured to provide the laser beam for a duration based on the vertical distance to remove the top polishing layer. 
     
     
         4 . The apparatus of  claim 1 , wherein the polishing pad further comprises:
 a second polishing layer under the top polishing layer; and   a separation layer between the top polishing layer and the second polishing layer.   
     
     
         5 . The apparatus of  claim 4 , wherein the laser is further configured to:
 remove the top polishing layer at a first removal rate; and   remove the separation layer at a second removal rate greater than the first removal rate.   
     
     
         6 . The apparatus of  claim 1 , wherein the laser is further configured to produce the laser beam with a beam size of about 3 mm. 
     
     
         7 . The apparatus of  claim 1 , wherein the laser is further configured to produce the laser beam with a power between about 300 Watt and about 800 Watt. 
     
     
         8 . An apparatus, comprising:
 a wafer polisher comprising a polishing pad, wherein the polishing pad comprises a plurality of polishing layers and a plurality of separation layers separating the plurality of polishing layers;   a sensor above the wafer polisher and configured to measure a surface profile of the top polishing layer; and   a laser comprising a laser beam output projecting along a top polishing layer of the plurality of polishing layers.   
     
     
         9 . The apparatus of  claim 8 , wherein the laser is configured to provide a laser beam to remove the top polishing layer at a first removal rate. 
     
     
         10 . The apparatus of  claim 9 , wherein the laser is further configured to provide the laser beam to remove a top separation layer of the plurality of separation layers at a second removal rate different from the first removal rate. 
     
     
         11 . The apparatus of  claim 10 , wherein the second removal rate is about ten times greater than the first removal rate. 
     
     
         12 . The apparatus of  claim 8 , wherein the laser is configured to provide a laser beam to remove the top polishing layer from a side surface of the top polishing layer. 
     
     
         13 . The apparatus of  claim 8 , wherein the sensor is further configured to measure a vertical distance between a global high surface point of the top polishing layer and a global low surface point of the top polishing layer. 
     
     
         14 . The apparatus of  claim 13 , wherein the laser is configured to, in response to the vertical distance being greater than a threshold value, provide a laser beam for a duration to remove the top polishing layer, wherein the duration is based on the vertical distance. 
     
     
         15 . An apparatus, comprising:
 a wafer polisher comprising a polishing pad, wherein the polishing pad comprises a top polishing layer;   a sensor above the wafer polisher and configured to measure a vertical distance between a global high surface point of the top polishing layer and a global low surface point of the top polishing layer; and   a laser on a side of the wafer polisher and configured to perform a removal process to remove the top polishing layer.   
     
     
         16 . The apparatus of  claim 15 , wherein the laser is further configured to provide a laser beam for a duration based on the vertical distance. 
     
     
         17 . The apparatus of  claim 15 , wherein the laser is further configured to perform the removal process for a plurality of durations, and wherein the sensor is configured to re-measure the vertical distance at intervals between the plurality of durations. 
     
     
         18 . The apparatus of  claim 15 , wherein the laser is further configured to, in response to the vertical distance being greater than a threshold value, provide a laser beam to perform the removal process. 
     
     
         19 . The apparatus of  claim 15 , wherein the laser is further configured to provide a laser beam to project along the top polishing layer from the side of the wafer polisher. 
     
     
         20 . The apparatus of  claim 15 , wherein the polishing pad further comprises a separation layer below the top polishing layer, and wherein the laser is further configured to, after performing the removal process, perform another removal process to remove the separation layer.