Apparatus and method for polishing semiconductor wafer

Abstract

By almost completely removing foreign matter adhering to the wafer holding unit of a polishing head in a CMP process, a wafer yield is improved. An apparatus for polishing a semiconductor wafer is provided with a wafer holder to which the wafer is attached, a polishing unit which polishes the wafer with a polishing slurry supplied to the wafer, a wafer attaching and detaching unit at which the wafer is attached to or detached from the wafer holder, and a washing unit which washes the wafer holder. The wafer holder has a wafer contact surface, which contacts the backside of the wafer, and a supporting unit which prevents the jump out of the wafer. The washing unit has nozzles which supply a washing solution to the wafer contact surface and the supporting unit, and the nozzles are composed of a plurality of outlets capable of supplying at least two different liquids. As a result, it is possible to almost completely remove the foreign matter adhering to the wafer holder to always keep the wafer holder clean.

1 . A method for polishing a semiconductor wafer, wherein a wafer holder, to which a wafer is attached, moves between a wafer attaching and detaching unit and a washing unit via a polishing unit to polish the semiconductor wafer and to wash the wafer holder and which comprises: a step of attaching the wafer to the wafer holder at the wafer attaching and detaching unit and of conveying the wafer to the polishing unit; a step of polishing the wafer through the use of the polishing unit, moving the polished wafer to the wafer attaching and detaching unit, and detaching the wafer from the wafer holder; and a step of moving the wafer holder, from which the wafer has been detached, to the washing unit and of washing the wafer holder with at least two different liquids supplied.  
   
   
       2 . The method for polishing a semiconductor wafer according to  claim 1 , wherein the washing unit washes the wafer holder through the use of an ultrasonic oscillation mechanism, a brush washing mechanism, a high-pressure spray mechanism, or a megasonic oscillation mechanism.  
   
   
       3 . The method for polishing a semiconductor wafer according to claim  2 , areas washed by the ultrasonic wave of the ultrasonic oscillation mechanism, the brush of the brush washing mechanism, the high-pressure spray of the high-pressure spray mechanism, or the megasonic vibration of the megasonic oscillation mechanism are each concentrically selected to the wafer contact surface of the wafer holder.  
   
   
       4 . The method for polishing a semiconductor wafer according to  claim 1 , wherein the washing process is performed immediately before the wafer is attached or immediately after the wafer is detached.  
   
   
       5 . The method for polishing a semiconductor wafer according to  claim 1 , wherein the number of times the washing process is performed is determined according to the number of times the wafer holder is attached or detached or to a time period in which the wafers are polished.  
   
   
       6 . The method for polishing a semiconductor wafer according to  claim 1 , wherein the washing process is performed during the idling of the polishing apparatus.