Polishing endpoint detecting method, device for detecting a polishing endpoint of a polishing process and chemical-mechanical polishing apparatus comprising the same

Abstract

A polishing endpoint detecting device of a polishing apparatus detects a polishing endpoint of a polishing process by measuring light reflected from a surface of a semiconductor substrate being polished. The apparatus also includes a polishing pad and a rotary plate each of a light-transmitting material. The light is directed onto the surface of the semiconductor substrate through the polishing pad and the rotary plate and is scanned across the surface of the semiconductor substrate along a horizontal line which passes through the centers of the polishing pad and the semiconductor substrate. A light-measuring instrument measures a characteristic of the light reflected from the surface of the semiconductor substrate, and a processor detects the polishing endpoint by analyzing signals produced by the light measuring instrument.

What is claimed is:  
     
         1 . A polishing endpoint detecting device for use in detecting a polishing endpoint of a process of polishing a surface of a substrate, comprising: 
 a light source for producing a beam of light to be provided onto a surface of the substrate being polished by a polishing pad that is transparent with respect to the beam of light;    light path changing means for changing a path of the beam of light so that the beam of light scans the surface of the substrate along a horizontal line across the surface of the substrate;    a light measuring instrument operative to produce signals representative of a characteristic of a light reflected from the surface of the substrate and to output the signals; and    a processor connected to the light measuring instrument so as to receive the signals produced by the light measuring instrument and configured to analyze the signals to detect a polishing endpoint of the polishing process.    
     
     
         2 . The polishing endpoint detecting device of  claim 1 , wherein the horizontal line passes through a center of the polishing pad.  
     
     
         3 . The polishing endpoint detecting device of  claim 1 , wherein the light path changing means comprises a reflective splitter, and driving means for rotating the splitter.  
     
     
         4 . The polishing endpoint detecting device of  claim 1 , wherein the light path changing means comprises a supporting member supporting the light source and the light measuring instrument, and driving means for moving the supporting member reciprocally along a straight line.  
     
     
         5 . The polishing endpoint detecting device of  claim 4 , wherein the light path changing means further comprises a reflective splitter oriented to direct the beam of light produced by the light source onto the surface of the substrate.  
     
     
         6 . The polishing endpoint detecting device of  claim 4 , wherein the light path changing means further comprises a reflective splitter oriented to direct the light reflected from the scanned surface of the substrate to the light measuring instrument.  
     
     
         7 . The polishing endpoint detecting device of  claim 6 , wherein the splitter is partially transmitting with respect to the beam of light produced by the light source, and is disposed above the light source so that some of the light produced by the light source directs onto the surface of the substrate through the splitter.  
     
     
         8 . A chemical-mechanical polishing apparatus comprising: 
 a light source that produces a beam of light;    a rotational table rotatable about a central axis of rotation, the rotational table including a rotary plate including a first material that is transparent with respect to the light produced by the light source, and a polishing pad including a second material that is transparent with respect to the light produced by the light source, the polishing pad being attached to the rotary plate;    a polishing head disposed above the polishing pad for holding a substrate such that a surface of the substrate faces the polishing pad and is pressed into contact with the polishing pad, and rotating the substrate while the surface of the substrate is in contact with the polishing pad;    light path changing means for changing a path of the beam of light so that the beam of light scans the surface of the substrate along a horizontal line across the surface of the substrate held against the polishing pad by the polishing head through the rotary plate and the polishing pad;    a light measuring instrument operative to produce signals representative of a characteristic of a light reflected from the surface of the substrate; and    a processor connected to the light measuring instrument so as to receive the signals produced by the light measuring instrument and configured to analyze the signals to detect a polishing endpoint of the polishing process.    
     
     
         9 . The chemical-mechanical polishing apparatus of  claim 8 , wherein the rotational table further includes a rotary shaft having a central longitudinal axis corresponding to the axis of rotation, a base plate mounted to the rotary shaft, and a sidewall extending between and along outer peripheral edges of the rotary plate and the base plate, wherein the rotational table has an inner space delimited by the base plate, the sidewall and the rotary plate, and wherein the light source, the light path changing means and the light measuring instrument are disposed in the inner space as supported by the base plate.  
     
     
         10 . The polishing endpoint detecting device of  claim 9 , wherein the light path changing means comprises a reflective splitter, and driving means for rotating the splitter.  
     
     
         11 . The polishing endpoint detecting device of  claim 8 , wherein the light path changing means comprises a reflective splitter, and driving means for rotating the splitter.  
     
     
         12 . The polishing endpoint detecting device of  claim 8 , wherein the light path changing means comprises a supporting member supporting the light source and the light measuring instrument, and driving means for moving the supporting member reciprocally along a straight line.  
     
     
         13 . The polishing endpoint detecting device of  claim 12 , wherein the light path changing means further comprises a reflective splitter that reflects the beam of light.  
     
     
         14 . The polishing endpoint detecting device of  claim 12 , wherein the splitter is partially transmitting with respect to the beam of light produced by the light source, and is disposed above the light source so that some of the light produced by the light source directs onto the surface of the substrate through the splitter.  
     
     
         15 . The polishing endpoint detecting device of  claim 9 , wherein the light path changing means comprises a supporting member supporting the light source and the light measuring instrument, and driving means for moving the supporting member reciprocally along a straight line.  
     
     
         16 . The polishing endpoint detecting device of  claim 8 , wherein the horizontal line passes through a center of the polishing pad.  
     
     
         17 . The chemical-mechanical polishing apparatus of  claim 8 , wherein the first material includes an acrylic acid resin.  
     
     
         18 . The chemical-mechanical polishing apparatus of  claim 8 , wherein the second material includes polyurethane.  
     
     
         19 . The chemical-mechanical polishing apparatus of  claim 8 , further comprising a display for showing an analysis result of the processor.  
     
     
         20 . The chemical-mechanical polishing apparatus of  claim 8 , further comprising a slurry supply member disposed above the polishing pad for supplying a slurry onto the polishing pad.