End point detection method applying resonance phenomenon, end point detection apparatus, chemical mechanical polishing apparatus on which the detection apparatus is loaded, and semiconductor device fabricated by the chemical mechanical polishing apparatus

Abstract

To provide an end point detection method applying a resonance phenomenon, an end point detection apparatus, and a chemical mechanical polishing apparatus on which the detection apparatus is loaded for monitoring variation in the thickness of an electrically conductive film in real time, reliably detecting a polishing end point of the electrically conductive film at high accuracy, without generating noise, low power consumption, and capable of reducing the cost. In order to achieve above described objects, the present invention provides an end point detection method applying a resonance phenomenon in which a polishing end point is detected when the electrically conductive film is polished and removed to an appropriate thickness, wherein a sensor 37 composed of an oscillation circuit of the Colpitts type or the like having a planar inductor and a concentrated constant capacitor is used, and the variation in the thickness of the electrically conductive film is monitored in real time from the variation in the oscillation frequency of the sensor 37 caused along with the variation in the thickness of the electrically conductive film opposed to the planar inductor.

1 . An end point detection method applying a resonance phenomenon in which an electrically conductive film is polished and a polishing end point at which an appropriate thickness of the film is removed is detected, wherein
 a sensor composed of an oscillation circuit of a Colpitts type or the like having a planar inductor and a concentrated constant capacitor is used, and variation in the thickness of the electrically conductive film is monitored in real time from variation in an oscillation frequency of the sensor caused along with the variation in the thickness of the electrically conductive film opposed to the planar inductor.   
   
   
       2 . The end point detection method applying the resonance phenomenon according to  claim 1 , wherein the sensor uses digital output using a counter as a transmission method of the oscillation frequency. 
   
   
       3 . The end point detection method applying the resonance frequency according to  claim 1  or  2 , wherein an oscillation frequency band of the sensor is 30 MHz. 
   
   
       4 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 , or  3 , wherein the concentrated constant capacitor in the sensor has a variable capacitance, and the sensor can select an oscillation frequency band. 
   
   
       5 . The end point detection method applying the resonance phenomenon according to  1 ,  2 ,  3 , or  4 , wherein the electrically conductive film is formed of Cu, W, Ta, Cr, Al, Ti, or TiN and a pattern of a film type including them. 
   
   
       6 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 , or  5 , wherein the electrically conductive film is removed by chemical mechanical polishing. 
   
   
       7 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 ,  5 , or  6 , wherein one or more the sensor is embedded in an upper surface portion of a platen constituting a chemical mechanical polishing apparatus. 
   
   
       8 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 ,  5 , or  6 , wherein one or more the sensor is embedded in a polishing head constituting the chemical mechanical polishing apparatus. 
   
   
       9 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 , or  8 , wherein the variation in the oscillation frequency of the sensor caused along with the variation in the thickness of the electrically conductive film is not monotonous increase or decrease but has a peak, and the polishing end point is detected based on the peak. 
   
   
       10 . The polishing end point applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 , or  10 , wherein the variation in the oscillation frequency of the sensor caused along with the variation in the thickness of the electrically conductive film is not monotonous increase or decrease but has a peak, and the polishing is stopped by using either a point at which the peak is detected or a point at which a predetermined amount of polishing is performed after the peak is detected as a polishing end point depending on the film type of the electrically conductive film. 
   
   
       11 . The end point detection method applying the resonance phenomenon according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 , or  10 , wherein the fact that an oscillation frequency peak value generated at the point when polishing reaches the thickness of the electrically conductive film is constant, a threshold value is set based on the oscillation frequency peak value in accordance with the film type, and the polishing is stopped at a polishing end point when the oscillation frequency reaches the threshold value before the peak or after the peak. 
   
   
       12 . The end point detection method applying the resonance frequency according to  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 , or  11 , wherein the electrically conductive film is formed on a surface of a wafer, and the planar inductor is in the vicinity of either the electrically conductive film of the wafer surface portion or the back surface of the wafer. 
   
   
       13 . An end point detection apparatus utilizing a resonance phenomenon, wherein the apparatus executes the end point detection method applying the resonance phenomenon described in  claim 1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 , or  12 , the apparatus having a sensor composed of an oscillation circuit of a Colpitts type or the like having a planar inductor and a concentrated constant capacitor. 
   
   
       14 . A chemical mechanical polishing apparatus, wherein the end point detection apparatus applying the resonance phenomenon according to  claim 13  is loaded. 
   
   
       15 . A semiconductor device fabricated by the chemical mechanical polishing apparatus according to  claim 14 .