Polishing apparatus and polishing method

Abstract

The present invention relates to a polishing apparatus and a polishing method for polishing a substrate while detecting a film thickness of the substrate by analyzing reflected light from the substrate on a polishing pad. The polishing apparatus includes a polishing table (3) configured to support a polishing pad (2) having a through-hole (61); a pad-height measuring device (32) configured to measure a height of the polishing surface (2a); a pure-water supply line (63) and a pure-water suction line(64) coupled to the through-hole (61) ; a flow-rate adjusting device (71) coupled to the pure-water supply line (63); and an operation controller (35) configured to control an operation of the flow-rate adjusting device (71). The operation controller (35) determines a flow rate of the pure water corresponding to a measured value of the height of the polishing surface (2a) from correlation data, and controls the operation of the flow-rate adjusting device (71) such that the pure water flows through the pure-water supply line (63) at the determined flow rate.

What is claimed: 
     
         1 . A polishing apparatus for a substrate, comprising:  
       a polishing table configured to support a polishing pad, the polishing pad having a through-hole;  
       a polishing head configured to press the substrate against a polishing surface of the polishing pad;  
       a dresser configured to contact the polishing surface of the polishing pad, the dresser being coupled to a dresser shaft; 
       a pad-height measuring device configured to measure a height of the polishing surface, the pad-height measuring device being coupled to dresser via the dresser shaft;  
       a pure-water supply line and a pure-water suction line coupled to the through-hole;  
       an optical film thickness measurement system configured to direct light to the substrate through the through-hole, receive reflected light from the substrate through the through-hole, and determine a film thickness of the substrate based on the reflected light;  
       a flow-rate adjusting device coupled to the pure-water supply line; and  
       an operation controller configured to control an operation of the flow-rate adjusting device,  
       the operation controller including:  
        a memory storing a program and correlation data indicating a relationship between the height of the polishing surface and flow rate of the pure water, the flow rate being such that the through-hole is filled with the pure water and the pure water does not overflow onto the polishing surface, and  
        an arithmetic device configured to perform an arithmetic operation according to an instruction included in the program to determine a flow rate of the pure water corresponding to a measured value of the height of the polishing surface, and control the operation of the flow-rate adjusting device such that the pure water flows through the pure-water supply line at the determined flow rate. 
     
     
         2 . The polishing apparatus according to  claim 1 , wherein the correlation data indicates the relationship in which the flow rate of the pure water decreases as the height of the polishing surface decreases. 
     
     
         3 . The polishing apparatus according to  claim 1 , wherein:  
       the flow-rate adjusting device comprises a feeding pump device;  
       the correlation data indicates a relationship between the height of the polishing surface and rotation speed of the feeding pump device; and  
       the arithmetic operation comprises an arithmetic operation to determine a rotation speed of the feeding pump device corresponding to the measured value of the height of the polishing surface, and to instruct the feeding pump device to rotate at the determined rotation speed. 
     
     
         4 . The polishing apparatus according to  claim 1 , wherein:  
       the flow-rate adjusting device comprises a flow-rate control valve; and  
       the arithmetic operation comprises an arithmetic operation to determine a flow rate of the pure water corresponding to the measured value of the height of the polishing surface, and to instruct the flow-rate control valve to allow the pure water to flow through the pure-water supply line at the determined flow rate. 
     
     
         5 . The polishing apparatus according to  claim 1 , further comprising:  
       an outflow-side pump coupled to the pure-water suction line; and  
       a frequency variable device configured to control a rotation speed of the outflow-side pump.