Method of detecting chemical mechanical polishing conditioning disk orientation

Abstract

A method and apparatus for determining a polishing pad thickness profile are described herein. A set of displacement sensors, including an arm displacement sensor and one or more conditioning disk displacement sensors are utilized to determine the orientation of a conditioning disk and the thickness of the polishing pad. The displacement sensors are non-contact sensors, such as a laser sensor, a capacitive sensor, or an inductive sensor. Once the thickness profile of the polishing pad is determined, one or more process conditions is altered to improve substrate polishing.

What is claimed is: 
     
         1 . A pad conditioning assembly for a chemical mechanical polishing (CMP) apparatus, comprising:
 a conditioning disk;   a first actuator coupled to the conditioning disk;   a second actuator disposed radially outward of the conditioning disk;   a conditioner arm coupling the first actuator and the second actuator;   an arm displacement sensor coupled to the conditioner arm; and   one or more conditioning disk displacement sensors coupled to the first actuator.   
     
     
         2 . The pad conditioning assembly of  claim 1 , wherein the conditioning disk displacement sensors are configured to measure a distance between each of the conditioning disk displacement sensors and a portion of the conditioning disk. 
     
     
         3 . The pad conditioning assembly of  claim 2 , wherein the conditioning disk displacement sensors are one of an inductive sensor, a capacitive sensor, or a laser sensor. 
     
     
         4 . The pad conditioning assembly of  claim 2 , wherein the one or more conditioning disk displacement sensors comprises two or more conditioning disk displacement sensors. 
     
     
         5 . The pad conditioning assembly of  claim 1 , wherein the arm displacement sensor is an inductive sensor, a capacitive sensor, or a laser sensor. 
     
     
         6 . The pad conditioning assembly of  claim 5 , wherein the arm displacement sensor is configured to measure a distance between the arm displacement sensor and a top surface of a polishing platen disposed beneath the conditioner arm. 
     
     
         7 . The pad conditioning assembly of  claim 1 , wherein the conditioning disk further comprises a conditioning disk holder, and a conditioning disk pad disposed within the conditioning disk holder, the conditioning disk pad configured to be urged against a polishing pad. 
     
     
         8 . The pad conditioning assembly of  claim 1 , wherein the pad conditioning assembly is configured to move the conditioning disk across a polishing surface of a polishing pad using the second actuator. 
     
     
         9 . An apparatus for substrate processing, comprising:
 a polishing platen;   a substrate carrier; and   a pad conditioning assembly, the pad conditioning assembly comprising:
 a conditioning disk; 
 a first actuator coupled to the conditioning disk; 
 a second actuator disposed radially outward of the conditioning disk; 
 a conditioner arm coupling the first actuator and the second actuator; 
 an arm displacement sensor coupled to a bottom conditioner arm surface of the conditioner arm and configured to measure a first distance between the arm displacement sensor and a top surface of the polishing platen; and 
 one or more conditioning disk displacement sensors disposed on a bottom actuator surface of the first actuator and configured to measure a second distance between each of the conditioning disk displacement sensors and a portion of the conditioning disk. 
   
     
     
         10 . The apparatus of  claim 9 , wherein each of the arm displacement sensor and the one or more conditioning disk displacement sensors is an inductive sensor, a capacitive sensor, or a laser sensor. 
     
     
         11 . The apparatus of  claim 9 , wherein the one or more conditioning disk displacement sensors comprises two or more conditioning disk displacement sensors, each oriented at a different angular position with respect to a rotation axis of the conditioning disk. 
     
     
         12 . The apparatus of  claim 11 , wherein the two or more conditioning disk displacement sensors comprise three conditioning disk displacement sensors. 
     
     
         13 . The apparatus of  claim 11 , wherein the two or more conditioning disk displacement sensors comprises four conditioning disk displacement sensors. 
     
     
         14 . The apparatus of  claim 9 , wherein the conditioning disk further comprises a conditioning disk holder, and a conditioning disk pad disposed within the conditioning disk holder, the conditioning disk pad configured to be urged against a polishing pad and the one or more conditioning disk displacement sensors configured to measure the first distance between each of the conditioning disk displacement sensors and a portion of the conditioning disk pad. 
     
     
         15 . The apparatus of  claim 9 , further comprising a controller, the controller configured to:
 determine an orientation of the conditioning disk with input from each of the one or more conditioning disk displacement sensors and the arm displacement sensor.   
     
     
         16 . The apparatus of  claim 15 , wherein the controller is further configured to:
 determine a thickness profile of a polishing pad disposed on the polishing platen; and   change one or more conditioning parameters after determining the thickness profile.   
     
     
         17 . A method of substrate processing comprising:
 urging a conditioning disk against a surface of a polishing pad;   measuring a distance between a conditioning arm and a polishing platen disposed beneath the polishing pad, the conditioning arm coupled to the conditioning disk via a first actuator;   determining an orientation of the conditioning disk using one or more conditioning disk displacement sensors;   determining a thickness profile of the polishing pad from the orientation of the conditioning disk; and   changing one or more conditioning parameters after determining the thickness profile.   
     
     
         18 . The method of  claim 17 , wherein determining the orientation of the conditioning disk further comprises using an arm displacement sensor disposed on a bottom arm surface of the conditioning arm. 
     
     
         19 . The method of  claim 18 , wherein each of the arm displacement sensor and the one or more conditioning disk displacement sensors are an inductive sensor, a capacitive sensor, or a laser sensor. 
     
     
         20 . The method of  claim 17 , wherein the one or more conditioning parameters is a dwell time of the conditioning disk on different radial positions of the polishing pad or downforce of the conditioning disk on the different radial positions of the polishing pad.