Flexible membranes for a polishing head

Abstract

A flexible membrane for a polishing head includes a main part having a first surface configured to make contact with a surface of a substrate and a second surface opposite to the first surface, a plurality of extensions extending substantially perpendicularly from the second surface of the main part so as to define a plurality of independent spaces, respectively, and an inner ring coupled with an inner side of an outermost extension of the extensions to support an edge portion of the main part. A bottom surface of the inner ring is substantially flat.

What is claimed is: 
     
         1 . A flexible membrane for a polishing head, the flexible membrane comprising:
 a main part having a first surface configured to make contact with a surface of a substrate and a second surface opposite to the first surface;   a plurality of extensions extending substantially perpendicularly from the second surface of the main part so as to define a plurality of independent spaces, respectively; and   an inner ring coupled with an inner side of an outermost extension of the extensions to support an edge portion of the main part, wherein a bottom surface of the inner ring being substantially flat.   
     
     
         2 . The flexible membrane of  claim 1 , wherein the main part and the extensions comprise a flexible material. 
     
     
         3 . The flexible membrane of  claim 1 , wherein the inner ring comprises one of a flexible material or a nonflexible material. 
     
     
         4 . The flexible membrane of  claim 1 , wherein the inner ring has a sidewall having a shape corresponding to a shape of a sidewall of the outermost extension, and the sidewall of the inner ring is disposed in the sidewall of the outermost extension. 
     
     
         5 . The flexible membrane of  claim 1 , wherein the inner ring has a same height along a circumference of the inner ring. 
     
     
         6 . The flexible membrane of  claim 1 , wherein an inner wall of the inner ring is vertical. 
     
     
         7 . The flexible membrane of  claim 1 , wherein an inner wall of the inner ring includes a first portion having a vertical slope, a second portion having a non-vertical slope and a third portion having a vertical slope in an upward direction. 
     
     
         8 . The flexible membrane of  claim 1 , wherein the extensions are ring-shaped, and the spaces defined by the extensions are concentric. 
     
     
         9 . The flexible membrane of  claim 1 , wherein an edge-portion space defined by the extensions is divided into a first zone and a second zone under the first zone. 
     
     
         10 . The flexible membrane of  claim 9 , wherein the second zone faces a portion defined from an edge of the main part to a point inwardly spaced from the edge of the main part by about 10% to about 20% of a radius of the main part. 
     
     
         11 . The flexible membrane of  claim 1 , wherein the spaces defined by the extensions are configured to be one of independently pressurized by air or independently evacuated to a vacuum pressure. 
     
     
         12 . The flexible membrane of  claim 1 , wherein the main part is disk-shaped. 
     
     
         13 . The flexible membrane of  claim 1 , wherein a top surface of the inner ring is substantially parallel with the substrate. 
     
     
         14 . A flexible membrane for a polishing head, the flexible membrane comprising:
 a main part having a first surface configured to make contact with a surface of a substrate and a second surface opposite to the first surface;   a plurality of extensions extending substantially perpendicularly from the second surface of the main part so as to define a first space, a second space, a third space, a fourth space, and a fifth space in the membrane which are isolated from each other, wherein the second space is disposed vertically under the first space and the first and second spaces face an edge portion of the substrate, wherein the third space, the fourth space and the fifth space are disposed in a direction from the second space to a center of the main part and wherein the second space, the third space, the fourth space and the fifth space are configured to directly face the substrate; and   an inner ring coupled with an inner side of an outermost extension of the extensions to support an edge portion of the main part, wherein a bottom surface of the inner ring being substantially flat and an inner wall of the inner ring is vertical.   
     
     
         15 . The flexible membrane of  claim 14 , wherein each of the extensions have a protruded ring shape. 
     
     
         16 . The flexible membrane of  claim 14 , wherein the main part and the extensions are formed in one body and are formed of a same material as each other. 
     
     
         17 . The flexible membrane of  claim 14 , wherein an inner volume of a lower portion of the second zone is limited by the bottom surface of the inner ring. 
     
     
         18 . The flexible membrane of  claim 17 , wherein the bottom surface of the inner ring covers about 50% to about 95% of a top width of the second space. 
     
     
         19 . The flexible membrane of  claim 12 , wherein a top surface of the inner ring is substantially parallel with the substrate. 
     
     
         20 . The flexible membrane of  claim 12 , wherein an inner wall of the inner ring includes a portion having a vertical slope.