Sub-pad for polishing pad, polishing pad including same, and method for manufacturing sub-pad for polishing pad

Abstract

A sub-pad for a polishing pad is disclosed. The sub-pad is stacked under a top pad that is brought into contact with a wafer to perform polishing, and includes a nanofiber nonwoven fabric pad. The nanofiber nonwoven fabric pad has a nanofiber density of an outer circumferential part that is formed to be 1.2 to 5 times higher than the nanofiber density of other portions inside the outer circumferential part. A polishing pad including the sub-pad and a method for manufacturing the sub-pad for the polishing pad are disclosed.

1 . A sub-pad for a polishing pad, the sub-pad being stacked under a top pad that is brought into contact with a wafer to perform polishing, and including a nanofiber nonwoven fabric pad, wherein the nanofiber nonwoven fabric pad has a nanofiber density of an outer circumferential part that is formed to be 1.2 to 5 times higher than the nanofiber density of other portions inside the outer circumferential part. 
     
     
         2 . The sub-pad for the polishing pad according to  claim 1 ,
 wherein the nanofiber density of the outer circumferential part is 1.5 to 5 times higher than the nanofiber density of other portions inside the outer circumferential part.   
     
     
         3 . The sub-pad for the polishing pad according to  claim 1 ,
 wherein the nanofiber nonwoven fabric pad includes a hydrophobic polymer.   
     
     
         4 . The sub-pad for the polishing pad according to  claim 3 ,
 wherein the hydrophobic polymer is at least one selected from a group consisting of polystyrene and Teflon (PTFE, Polytetrafluoroethylene).   
     
     
         5 . The sub-pad for the polishing pad according to  claim 1 ,
 wherein the outer circumferential part of the sub-pad functions to prevent penetration of a polishing slurry due to a low porosity.   
     
     
         6 . A polishing pad, comprising:
 a top pad that is brought into contact with a wafer to perform polishing; and   the sub-pad of  claim 1  stacked under the top pad.   
     
     
         7 . The polishing pad according to  claim 6 ,
 wherein a cross section of the outer circumferential part of the sub-pad is exposed to the outer circumferential surface of the polishing pad.   
     
     
         8 . A method for manufacturing the sub-pad for the polishing pad of  claim 1 , the method comprising the steps of:
 a) electrospinning a polymer solution;   b) recovering the nanofiber nonwoven fabric formed by the electrospinning; and   c) thermally compressing the nanofiber nonwoven fabric,   wherein the collector during electrospinning of the step a) includes a circular electrode corresponding to the outer circumferential part of the sub-pad.   
     
     
         9 . The method for manufacturing the sub-pad for the polishing pad according to  claim 8 ,
 wherein the collector includes an electrospinning-induced film, and   the circular electrode is formed on the surface of the electrospinning-induced film.   
     
     
         10 . The method for manufacturing the sub-pad for the polishing pad according to  claim 9 ,
 wherein the circular electrode is printed on the surface of the electrospinning-induced film.   
     
     
         11 . The method for manufacturing the sub-pad for the polishing pad according to  claim 9 ,
 wherein two or more nanofiber nonwoven fabrics recovered in the step b) are stacked such that high density portions of the nanofiber formed on the top of a circular electrode overlap each other, and the stacked nanofiber nonwoven fabrics are thermally compressed in the step c).   
     
     
         12 . The method for manufacturing the sub-pad for the polishing pad according to  claim 9 ,
 wherein a plurality of circular electrodes are formed on the surface of electrospinning-induced films, and the plurality of circular electrodes are electrically connected by a conductive material,   the electrospinning-induced film collects nanofibers spun while moving horizontally, or   the electrospinning-induced film collects nanofibers spun while rotating in the state of being wound around a circular drum.