Polishing head of a chemical and mechanical polishing apparatus

Abstract

A polishing head of a chemical and mechanical polishing apparatus includes a retainer ring which adheres more uniformly to a polishing pad. The retainer ring surrounds and protects a wafer chucked to the polishing head. The bottom surface of the retainer ring is inclined by a predetermined angle from the outer periphery thereof towards the inner periphery thereof. A resilient fixing plate disposed against the upper surface of the inner peripheral portion of the retainer ring provides a seal between the retainer ring and the carrier. Therefore, when the retainer ring is pressed against a polishing pad and the inner peripheral portion of the retainer ring is pushed downwardly due to the resiliency of the fixing plate, the retainer ring flexes such that uniform pressure is produced between the bottom surface of the retainer ring and the polishing pad. Hence, the wafer will be polished uniformly.

What is claimed is:  
     
         1 . A polishing head of a chemical and mechanical polishing apparatus comprising: 
 a housing defining at least one air passage therein and through which air is introduced into and discharged from the polishing head;    a carrier connected to said housing so as to be movable up and down relative to said housing;    a wafer chuck mounted to said carrier and communicating with a said air passage defined in the housing so that a wafer can be chucked thereto by a vacuum created when air is discharged through said air passage;    a flexible retainer ring mounted to said carrier, and extending along an outer peripheral portion of the carrier around said wafer chuck so as to guide the wafer chuck and protect a wafer chucked by the wafer chuck,    the retainer ring having a lowermost surface that extends upwardly at a predetermined inclination relative to the horizontal from the outer periphery thereof towards the inner periphery thereof, in the absence of forces exerted on the retainer ring; and    a resilient member disposed in the polishing head so as to exert a downward force that causes the inner peripheral portion of said retainer ring to be pushed downwardly when the retainer ring is pressed downwardly against a polishing pad, whereby the retainer ring will flex to allow the lowermost surface of the retainer ring to be pressed uniformly against the polishing pad.    
     
     
         2 . A polishing head according to    claim 1   , wherein an air chamber is defined by and between said wafer chuck and said carrier, and said resilient member is a fixing ring interposed between an upper surface of the retainer ring, at the inner peripheral portion thereof, and a lower surface of the carrier so as to seal the air chamber defined between the wafer chuck and the carrier.  
     
     
         3 . A polishing head according to    claim 1   , wherein the lowermost surface of said retainer ring is inclined at an angle of 0.8 to 0.9 degrees relative to the horizontal.  
     
     
         4 . A polishing head according to    claim 1   , wherein said retainer ring is made of a material selected from the group consisting of acethal resin, a polyphenylene sulfide resin, and a polyether sulfone (PES) resin.  
     
     
         5 . A polishing head of a chemical and mechanical polishing apparatus comprising: 
 a housing defining a plurality of air passages therein and through which air is introduced into and discharged from the polishing head;    a carrier connected to said housing so as to be movable up and down relative to said housing;    a wafer chuck including a chucking plate, and a connector connecting the chucking plate to the carrier such that said chucking plate is movable upwardly and downwardly relative to said carrier;    a guide member disposed between said carrier and said chucking plate, said connector defining a first air chamber together with the carrier, the chucking plate, and the guide member, said guide member and said chucking plate defining a second chamber therebetween, said guide member being engaged with said wafer chuck so as to guide said wafer chuck during up and down movement of said chucking plate, and said guide member having a through-hole that places one of said air passages defined in the housing in communication with the air chamber defined between the guide member and the chucking plate;    an air cushion disposed on the lower surface of said carrier, exposed to said first air chamber and communicating with one of said air passages defined in the housing, said air cushion being inflatable and deflatable by air introduced into and discharged from the polishing head via said one of the air passages so as to change the pressure in said first air chamber and thereby selectively move said chucking plate upwardly and downwardly;    a flexible retainer ring mounted to said carrier, and extending along an outer peripheral portion of the carrier around said wafer chuck so as to guide the wafer chuck and protect a wafer chucked by the wafer chuck,    the retainer ring having a lowermost surface that is extends upwardly at a predetermined inclination relative to the horizontal from the outer periphery thereof towards the inner periphery thereof, in the absence of forces exerted on the retainer ring; and    a resilient member disposed in the polishing head so as to exert a downward force that causes the inner peripheral portion of said retainer ring to be pushed downwardly when the retainer ring is pressed downwardly against a polishing pad, whereby the retainer ring will flex to allow the lowermost surface of the retainer ring to be pressed uniformly against the polishing pad.    
     
     
         6 . A polishing head according to    claim 5   , wherein said resilient member is a fixing ring interposed between the inner peripheral portion of the retainer ring and a lower surface of said carrier, and sealing said first air chamber defined by said chucking plate and said carrier.  
     
     
         7 . A polishing head according to    claim 5   , wherein the lowermost surface of said retainer ring is inclined at an angle of 0.8 to 0.9 degrees relative to the horizontal.  
     
     
         8 . A polishing head according to    claim 5   , wherein said retainer ring is made of a material selected from the group consisting of acethal resin, a polyphenylene sulfide resin, and a polyether sulfone (PES) resin.  
     
     
         9 . A retainer ring for use in protecting a wafer chucked by a wafer chuck of a polishing head of a chemical mechanical polishing apparatus, said retainer ring comprising a flexible annular body having an uppermost surface, a lowermost surface, an inner peripheral surface, and an outer peripheral surface, an upper end of said inner peripheral surface adjacent the uppermost surface being stepped, a plurality of screw holes for allowing the annular body to be fixed to a carrier extending into the annular body from said uppermost surface thereof at respective locations adjacent said outer peripheral surface, and said lowermost surface being inclined upwardly at a predetermined inclination towards the uppermost surface from the outer peripheral surface of the annular body towards the inner peripheral surface thereof.  
     
     
         10 . A polishing head according to    claim 9   , wherein the lowermost surface of said retainer ring is inclined at an angle of 0.8 to 0.9 degrees relative to a plane that extends orthogonally to the longitudinal axis of the annular body.  
     
     
         11 . A polishing head according to    claim 9   , wherein said retainer ring is made of a material selected from the group consisting of acethal resin, a polyphenylene sulfide resin, and a polyether sulfone (PES) resin.