Polishing apparatus and polishing method

Abstract

A polishing apparatus that polishes a substrate includes a polishing table for holding a polishing pad and a polishing head configured to press a surface of the substrate against the polishing pad. A plurality of first optical heads detect a signal concerning a film thickness of the substrate while moving across the substrate. One spectrometer receives and processes signals output by at least two first sensor heads among the plurality of first sensor heads. An optical switch selectively connects the sensor heads to the spectrometer. A processor controls the optical switch to switch, at timing when the plurality of sensor heads simultaneously face the substrate, the connection to the spectrometer from one sensor head to another sensor head.

What is claimed is: 
     
         1 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensor heads configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one spectrometer configured to receive and process signals output by at least two sensor heads among the plurality of sensor heads;   a switcher configured to selectively connect the at least two sensor heads to the spectrometer; and   a controller, wherein   the controller controls the switcher to switch, at timing when the at least two sensor heads simultaneously face the substrate, the connection to the spectrometer from one sensor head to another sensor head.   
     
     
         2 . The polishing apparatus according to  claim 1 , wherein the polishing table is configured to rotate around an axis of the polishing table, and the plurality of sensor heads are disposed in a region of the polishing table facing a region including a center of the substrate. 
     
     
         3 . The polishing apparatus according to  claim 2 , wherein
 each two of a predetermined even number of the sensor heads among the plurality of sensor heads form a pair,   the two sensor heads forming the pair are present substantially in positions on opposite sides to each other with respect to the axis, and   the even number of the sensor heads are disposed such that lines connecting the two sensor heads forming each of the pairs are at a same angle interval around the axis.   
     
     
         4 . The polishing apparatus according to  claim 2 , wherein
 in predetermined four sensor heads among the plurality of sensor heads,   two sensor heads are present substantially in positions on opposite sides to each other with respect to the axis, and other two sensor heads are present substantially in positions on opposite sides to each other with respect to the axis, and   an angle formed by a line connecting the two sensor heads and a line connecting the other two sensor heads is larger than 0 degrees and smaller than 180 degrees.   
     
     
         5 . The polishing apparatus according to  claim 1 , wherein the polishing apparatus includes, as the plurality of sensor heads, a first sensor head configured to detect the signal concerning the film thickness of the substrate in a region including a center of the substrate and a second sensor head configured to detect the signal concerning the film thickness of the substrate while moving along a peripheral edge portion of the substrate. 
     
     
         6 . The polishing apparatus according to  claim 5 , wherein
 there are at least two first sensor heads as a plurality of the first sensor heads, and there are at least two sensor heads as a plurality of the second sensor heads,   the two first sensor heads are present substantially in positions on opposite sides to each other with respect to the axis,   the axis is present on a line segment connecting the two second sensor heads, and   an angle formed by a line connecting the two first sensor heads and the line segment connecting the second sensor heads is 0 degrees to 180 degrees.   
     
     
         7 . The polishing apparatus according to  claim 1 , wherein, in a predetermined number of the sensor heads among the plurality of sensor heads and a predetermined number of other sensor heads among the plurality of sensor heads,
 each one of the predetermined number of other sensor heads is disposed on lines respectively connecting the predetermined number of sensor heads and the axis of the polishing table.   
     
     
         8 . The polishing apparatus according to  claim 1 , wherein
 in predetermined two sensor heads among the plurality of sensor heads and other predetermined four sensor heads among the plurality of sensor heads,   the predetermined two sensor heads are present substantially in positions on opposite sides to each other with respect to the axis,   the axis is present on a first line segment connecting two sensor heads among the predetermined four sensor heads,   the axis is present on a second line segment connecting other two sensor heads among the predetermined four sensor heads, and   an angle formed by the first line segment and the second line segment is 0 degrees to 180 degrees.   
     
     
         9 . The polishing apparatus according to  claim 8 , wherein
 the predetermined four sensor heads are disposed symmetrically with respect to a third line connecting the predetermined two sensor heads, and   a minimum angle among angles formed by the third line and the first line segment is smaller than 90 degrees and a minimum angle among angles formed by the third line and the second line segment is smaller than 90 degrees.   
     
     
         10 . A polishing method for polishing a substrate, the polishing method comprising:
 a polishing table holding a polishing pad;   a polishing head pressing a surface of the substrate against the polishing pad;   a plurality of sensor heads detecting a signal concerning a film thickness of the substrate in a region including a center of the substrate while moving across the substrate;   one spectrometer receiving and processing signals output by the plurality of sensor heads;   a switcher selectively connecting at least two of the sensor heads to the spectrometer; and   a controller controlling the switcher to switch the connection to the spectrometer from one sensor head to another sensor head at a time when the at least two sensor heads simultaneously face the substrate.   
     
     
         11 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensors configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one signal processor configured to receive and process signals output by at least two sensors among the plurality of sensors;   a switcher configured to selectively connect the at least two sensors to the signal processor; and   a controller, wherein   the controller controls the switcher to switch, at timing when the at least two sensors simultaneously face the substrate, the connection to the signal processor from one sensor to another sensor.   
     
     
         12 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensor heads configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one spectrometer configured to receive and process signals output by at least two sensor heads among the plurality of sensor heads;   a switcher configured to selectively connect the at least two sensor heads to the spectrometer; and   a controller, wherein   the controller controls the switcher to start, at timing when one sensor head of the at least two sensor heads faces the substrate and another does not face the substrate, switching processing for switching the connection to the spectrometer from the one sensor head to the other sensor head or from the other sensor head to the one sensor head.   
     
     
         13 . The polishing apparatus according to  claim 12 , wherein
 the other sensor head passes an end of the substrate when moving from a position not facing the substrate to a position facing the substrate, and   when the switching processing is started, the other sensor head is located in a vicinity of the end.   
     
     
         14 . The polishing apparatus according to  claim 12 , wherein, before the one sensor head facing the substrate reaches a terminal end of a locus passing under the substrate, the switching processing from the one sensor head to the other sensor head not facing the substrate is started. 
     
     
         15 . The polishing apparatus according to  claim 12 , wherein, after the one sensor head facing the substrate passes a start point of a locus passing under the substrate, the switching processing from the other sensor head not facing the substrate to the one sensor head is started. 
     
     
         16 . The polishing apparatus according to  claim 12 , further comprising a swinging device configured to swing the polishing head on the polishing pad during polishing, wherein
 the timing for starting the switching processing is controlled according to a swinging position of the polishing head.   
     
     
         17 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensor heads configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one spectrometer configured to receive and process signals output by at least two sensor heads among the plurality of sensor heads;   a switcher configured to selectively connect the at least two sensor heads to the spectrometer; and   a controller, wherein   the controller controls the switcher to start, at timing when one sensor head of the at least two sensor heads does not face the substrate, switching processing for switching the connection to the spectrometer from another sensor head to the one sensor head, and the switching processing is completed after the one sensor head passes a start point of a locus passing under the substrate.   
     
     
         18 . The polishing apparatus according to  claim 17 , wherein the switching processing is started at timing when the other sensor head does not face the substrate. 
     
     
         19 . The polishing apparatus according to  claim 17 , further comprising a swinging device configured to swing the polishing head on the polishing pad during polishing, wherein
 the timing for starting the switching processing is controlled according to a swinging position of the polishing head.   
     
     
         20 . A polishing method for polishing a substrate, the polishing method comprising:
 a polishing table holding a polishing pad;   a polishing head pressing a surface of the substrate against the polishing pad;   a plurality of sensor heads detecting a signal concerning a film thickness of the substrate while moving across the substrate;   one spectrometer receiving and processing signals output by at least two sensor heads among the plurality of sensor heads;   a switcher selectively connecting the at least two sensor heads to the spectrometer; and   a controller controlling the switcher to start, at timing when one sensor head of the at least two sensor heads faces the substrate and another sensor head does not face the substrate, switching processing for switching the connection to the spectrometer from the one sensor head to the other sensor head or from the other sensor head to the one sensor head.   
     
     
         21 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensors configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one signal processor configured to receive and process signals output by at least two sensors among the plurality of sensors;   a switcher configured to selectively connect the at least two sensors to the signal processor; and   a controller, wherein   the controller controls the switcher to start, at timing when one sensor of the at least two sensors faces the substrate and another sensor does not face the substrate, switching processing for switching the connection to the signal processor from the one sensor to the other sensor or from the other sensor to the one sensor.   
     
     
         22 . A polishing method for polishing a substrate, the polishing method comprising:
 a polishing table holding a polishing pad;   a polishing head pressing a surface of the substrate against the polishing pad;   a plurality of sensor heads detecting a signal concerning a film thickness of the substrate while moving across the substrate;   one spectrometer receiving and processing signals output by at least two sensor heads among the plurality of sensor heads;   a switcher selectively connecting the at least two sensor heads to the spectrometer; and   a controller controlling the switcher to start, at timing when one sensor head of the at least two sensor heads does not face the substrate, switching processing for switching the connection to the spectrometer from another sensor head to the one sensor head and controlling the switcher such that the switching processing is completed after the one sensor head passes a start point of a locus passing under the substrate.   
     
     
         23 . A polishing apparatus that polishes a substrate, the polishing apparatus comprising:
 a polishing table for holding a polishing pad;   a polishing head configured to press a surface of the substrate against the polishing pad;   a plurality of sensors configured to detect a signal concerning a film thickness of the substrate while moving across the substrate;   one signal processor configured to receive and process signals output by at least two sensors among the plurality of sensors;   a switcher configured to selectively connect the at least two sensors to the signal processor; and   a controller, wherein   the controller controls the switcher to start, at timing when one sensor of the at least two sensors does not face the substrate, switching processing for switching the connection to the signal processor from another sensor to the one sensor and controls the switcher such that the switching processing is completed after the one sensor passes a start point of a locus passing under the substrate.