Chemical mechanical polishing system with polishing pad height measurement sensor system

Abstract

A chemical mechanical polishing (CMP) system for semiconducting wafer substrates includes a polishing pad mounted upon a platen, a wafer carrier configured to hold a substrate on its backside and press the substrate against the polishing pad, and a pad conditioner that includes a conditioning disk and a conditioner head that holds the conditioning disk. The system also includes at least one polishing pad height measurement sensor to measure the profile of the polishing pad. The height measurement sensor can be mounted upon the wafer carrier or the pad conditioner, and is used to produce a uniform height across the surface of the polishing pad.

What is claimed is: 
     
         1 . A method for leveling a polishing pad of a chemical mechanical polishing (CMP) system for semiconducting wafer substrates, comprising:
 creating a height profile of the polishing pad using at least one height measurement sensor system;   identifying at least one protrusion from a polishing pad height specification;   determining at least one polishing parameter for the at least one protrusion; and   conditioning the polishing pad based on the at least one polishing parameter to reduce a height of the at least one protrusion;   wherein the at least one height measurement sensor system is mounted upon a pad conditioner or a wafer carrier.   
     
     
         2 . The method of  claim 1 , wherein the at least one height measurement sensor system is mounted on a rotatable component of the pad conditioner or the wafer carrier. 
     
     
         3 . The method of  claim 1 , wherein the at least one height measurement sensor system comprises a plurality of ultrasonic or infrared sensors. 
     
     
         4 . The method of  claim 3 , wherein the ultrasonic or infrared sensors in the plurality are evenly spaced about a perimeter of the pad conditioner or the wafer carrier. 
     
     
         5 . The method of  claim 3 , wherein the plurality of ultrasonic or infrared sensors contains from 2 to 8 sensors. 
     
     
         6 . The method of  claim 1 , wherein the at least one height measurement sensor system comprises an annular ultrasonic or infrared sensor. 
     
     
         7 . The method of  claim 1 , wherein a first height measurement sensor system is mounted upon the pad conditioner and a second height measurement sensory system is mounted upon the wafer carrier. 
     
     
         8 . The method of  claim 1 , further comprising polishing a wafer substrate using the polishing pad, wherein the polishing pad is conditioned concurrently with or prior to the polishing of the wafer substrate. 
     
     
         9 . The method of  claim 1 , wherein the at least one protrusion is identified by identifying a pad height that is outside of a specified range variation, or by identifying a pad height that is outside of a specified profile range. 
     
     
         10 . The method of  claim 1 , wherein the at least one polishing parameter comprises a pad conditioner down force, a pad conditioner rotation speed, or a pad conditioner dwell time. 
     
     
         11 . The method of  claim 1 , wherein the pad conditioner is gimbaled between a pad conditioner body and a pad conditioner head, and includes an electronic level on the pad conditioner head. 
     
     
         12 . The method of  claim 11 , further comprising tilting the pad conditioner head to change an area of a pad conditioning disk that contacts the polishing pad. 
     
     
         13 . A chemical mechanical polishing (CMP) system for semiconducting wafer substrates, comprising:
 a polishing pad;   a pad conditioner;   a wafer carrier; and   at least one height measurement sensor system mounted upon a rotatable component of the pad conditioner or the wafer carrier.   
     
     
         14 . The CMP system of  claim 13 , wherein the pad conditioner is mounted upon a movable arm that can move between a center and a perimeter of the polishing pad; and
 wherein the pad conditioner comprises a rotatable pad conditioner head and a pad conditioning disk affixed to an underside of the pad conditioner head.   
     
     
         15 . The CMP system of  claim 13 , wherein the at least one height measurement sensor system comprises one or more ultrasonic or infrared sensors. 
     
     
         16 . The CMP system of  claim 13 , wherein a first height measurement sensor system is mounted upon the pad conditioner and a second height measurement sensory system is mounted upon the wafer carrier. 
     
     
         17 . The CMP system of  claim 13 , wherein the pad conditioner is gimbaled between a pad conditioner body and a pad conditioner head, and includes an electronic level on the pad conditioner head. 
     
     
         18 . A method for planarizing a top layer of a wafer substrate, comprising:
 pushing the top layer against a polishing pad using a wafer carrier to which the wafer substrate is attached; and   in-situ conditioning the polishing pad using a pad conditioner while the top layer is being polished by the polishing pad;   wherein at least one height measurement sensor system is mounted upon the pad conditioner or the wafer carrier.   
     
     
         19 . The method of  claim 18 , wherein the at least one height measurement sensor system is mounted on a rotatable component of the pad conditioner or the wafer carrier. 
     
     
         20 . The method of  claim 18 , wherein the at least one height measurement sensor system is mounted on a rotatable pad conditioner head of the pad conditioner or upon a rotatable wafer carrier head of the wafer carrier.