Semiconductor fabricating system having hybrid brush assembly

1 . A method, comprising:

holding a semiconductor wafer via a wafer stage;

pressing a brush assembly against a backside surface of the semiconductor wafer while the wafer stage holds the semiconductor wafer from a front surface of the semiconductor wafer such that the backside surface of the semiconductor wafer faces the brush assembly, and wherein the brush assembly comprises a disk-shaped member, an inner brush member over the disk-shaped member, and an outer brush member over the disk-shaped member and laterally surrounding the inner brush member, and the outer brush member is made of a material having a lower rigidity than the inner brush member, and the disk-shaped member is made of a material having a lower rigidity than the inner brush member;

delivering a cleaning fluid to the inner brush member, wherein the cleaning fluid is absorbed into the inner brush member to cause expansion of the inner brush member toward the outer brush member, thereby reducing a gap between the inner brush member and the outer brush member and enabling fluid communication across grooves formed within the inner brush member and the outer brush member; and

rotating the brush assembly relative to the semiconductor wafer.

2 . The method of claim 1 , wherein the disk-shaped member is made of a same material as the outer brush member.

3 . The method of claim 1 , wherein the outer brush member and the disk-shaped member are formed integrally.

4 . The method of claim 1 , wherein from a cross-sectional view, the outer brush member has a level top surface, a vertical inner surface, and a beveled inner surface connecting the level top surface and the vertical inner surface.

5 . The method of claim 1 , wherein the inner brush member has a level top surface in a position that is higher than a lowermost position of the outer brush member and lower than an uppermost position of the outer brush member.

6 . The method of claim 1 , wherein a vertical dimension of the outer brush member is greater than a vertical dimension of the inner brush member.

7 . The method of claim 1 , wherein the inner brush member comprises a plurality of inner protruding portions arranged around a rotation axis, and the outer brush member comprises a plurality of outer protruding portions arranged around the rotation axis.

8 . The method of claim 4 , wherein the beveled inner surface has a greater horizontal dimension than the level top surface.

9 . The method of claim 4 , wherein the step of pressing the brush assembly against the backside surface of the semiconductor wafer is performed such that when the inner brush member contacts the backside surface of the semiconductor wafer, the outer brush member is bent outwardly by a compression pressure from the backside surface such that the level top surface of the outer brush member becomes substantially perpendicular to the backside surface of the semiconductor wafer and the beveled inner surface of the outer brush member is brought into flush contact with the backside surface of the semiconductor wafer.

10 . A method, comprising:

forming a photoresist layer on a front surface of a wafer;

holding the wafer via a wafer stage;

after forming the photoresist layer, moving a brush assembly toward the wafer to contact a backside surface of the wafer while the wafer stage holds the wafer from the front surface of the wafer such that the backside surface of the wafer faces the brush assembly, wherein the brush assembly comprises an inner brush member and an outer brush member laterally surrounding the inner brush member, and wherein from a cross-sectional view, the outer brush member has a first level top surface, a vertical inner surface, and a beveled inner surface connecting the first level top surface and the vertical inner surface, and the inner brush member has a second level top surface in a position lower than a topmost position of the beveled inner surface and higher than a lowermost position of the beveled inner surface;

rotating the brush assembly relative to the wafer to polish the backside surface of the wafer; and

after moving the brush assembly and rotating the brush assembly, exposing the photoresist layer on the front surface of the wafer.

11 . The method of claim 10 , wherein the brush assembly further comprises a disk-shaped member having a same material as the outer brush member, and the outer and inner brush members are formed over the disk-shaped member.

12 . The method of claim 10 , wherein the inner brush member has a plurality of inner grooves therein, and the outer brush member has a plurality of outer grooves therein.

13 . The method of claim 12 , wherein widths of the outer grooves are greater than widths of the inner grooves.

14 . The method of claim 10 , wherein the beveled inner surface has a greater horizontal dimension than the first level top surface.

15 . The method of claim 11 , further comprising:

when the brush assembly is pressed against the backside surface of the wafer, supplying a cleaning fluid from a dispenser toward a peripheral portion of the outer brush member to deliver the cleaning fluid to the inner brush member, wherein an outlet of the dispenser is oriented toward the peripheral portion of the outer brush member and positioned higher than a top surface of the disk-shaped member and lower than a top surface of the inner brush member.

16 . A method, comprising:

holding a wafer via a wafer stage;

performing a first backside cleaning operation by initiating a relative motion between a first brush assembly and the wafer stage while the wafer stage holds the wafer from a front surface of the wafer such that a backside surface of the wafer faces the first brush assembly, and wherein the first brush assembly is moveably located below the wafer stage, and the first brush assembly comprises:

a plurality of inner protruding portions arranged around a rotation axis; and

a plurality of outer producing portions arranged around the rotation axis and surrounding the inner protruding portions, wherein a distance between two adjacent outer protruding portions is greater than a distance between two adjacent inner protruding portions, wherein in a cross-sectional view, the outer protruding portions each have a level top surface, a vertical inner surface, and a beveled inner surface connecting the level top surface and the vertical inner surface, and the beveled inner surface has a greater horizontal dimension than the level top surface, and wherein the inner protruding portions are composed of a first material having a greater rigidity than a second material composing the outer protruding portions;

rotating the first brush assembly relative to the wafer during the first backside cleaning operation; and

after performing the first backside cleaning operation, performing a second backside cleaning operation using a second brush assembly comprising a single-material cylindrical brush.

17 . The method of claim 16 , wherein the first brush assembly further comprises a disk-shaped member, the disk-shaped member is made of a different material than the inner protruding portions, and the inner and outer protruding portions are disposed over the disk-shaped member.

18 . The method of claim 16 , wherein one of the inner protruding portions has a level top surface in a position that is higher than a lowermost position of the beveled inner surface and lower than an uppermost position of the beveled inner surface.

19 . The method of claim 17 , wherein the disk-shaped member is made of a material having a lower rigidity than the inner protruding portions.

20 . The method of claim 16 , wherein the first backside cleaning operation is performed such that when the inner protruding portions contact the backside surface of the wafer, the outer protruding portions are bent outwardly by a compression pressure from the backside surface such that the level top surfaces of the outer protruding portions become substantially perpendicular to the backside surface of the wafer and the beveled inner surfaces of the outer protruding portions are brought into flush contact with the backside surface of the wafer.