Wafer cleaning system

• US 6,059,888 A
• Filed: 11/13/1998
• Issued: 05/09/2000
• Est. Priority Date: 11/14/1997
• Status: Expired due to Fees

• Current Assignee: Creative Design Corp.
• Original Assignee: Creative Design Corp.
• Inventors: Hillman, Gary
• Primary Examiner(s): Till, Terrence R.
• Assistant Examiner(s): ALDAG, ANDREW J
• Application Number:
  US09/191,691
• Time in Patent Office: 543 Days
• Field of Search: 15/77, 15/21.1, 15/88.2, 15/88.3, 15/88.4, 15/97.1, 15/102, 134/153, 134/902, 134/6
• US Class Current: 134/6
• CPC Class Codes: B08B 1/32 using rotary cleaning members
• CPC Class Codes: H01L 21/67046 using mainly scrubbing means, e.g. brushes

Abstract

A wafer scrubbing system includes a upper and lower elongated scrubbers extending generally parallel with one another, the scrubbers being driven in rotation about their own axes. The wafer is disposed between the scrubbers so that the top and bottom surfaces of the wafer engage the scrubbers. The scrubbers are arranged to provide different frictional forces with the wafer at opposite ends of the scrubbers, and thereby provide a torque on the wafer about a central axis transverse to the top and bottom surfaces of the wafer and transverse to the scrubber axes.

Claims

1. A double sided scrubber system for cleaning a wafer having a top surface and a bottom surface, the scrubber system comprising:

a) a frame;

b) a first scrubber set comprising an upper scrubber having an upper scrubber axis and a lower scrubber having a lower scrubber axis, said upper scrubber and said lower scrubber each having a first end and a second end, said scrubbers being supported on said frame so that said scrubbers can be disposed in operative positions, said scrubbers in said operative positions extending generally codirectionally with one another with the first ends of said scrubbers disposed adjacent one another and with the second ends of said scrubbers disposed adjacent one another, said scrubbers being constructed and arranged so that when said scrubbers are in said operative positions and a wafer is disposed between said scrubbers, said scrubbers extend across the top and bottom surfaces of the wafer and engage the wafer with a first frictional force adjacent the first ends of the scrubbers and with a second frictional force different from said first frictional force adjacent the second ends of the scrubbers to thereby provide a frictional force difference;

c) a rotational drive connected to said scrubbers of said first set operative to turn said scrubbers of said first set around said scrubber axes in opposite directions about their respective scrubber axes; and

d) a constraint structure disposed adjacent said scrubbers for retaining the wafer between the scrubbers, said constraint structure allowing the wafer to rotate while preventing translational movement of the wafer from between the scrubbers.

2. The double sided scrubber system of claim 1 further comprising an upper scrubber carrier and a lower scrubber carrier, each one of said scrubber carriers being mounted to said frame for movement between a first position and a second position, said upper scrubber of said first set being mounted to said upper scrubber carrier, said lower scrubber of said first set being mounted to said lower scrubber carrier, said scrubbers of said first set being in said operative positions when said scrubber carriers are in said first positions.

3. The double sided scrubber system of claim 2 wherein said upper scrubber carrier is mounted to said frame for rotational movement about an upper scrubber carrier axis and said lower scrubber carrier is mounted to said frame for rotational movement about a lower scrubber carrier axis.

4. The double side scrubber system of claim 3 wherein said scrubber carrier axes are generally codirectional with said scrubber axes of said first set of scrubbers.

5. The double sided scrubber system of claim 4 further comprising a second set of scrubbers mounted on said scrubber carriers, said second scrubber set comprising an upper scrubber having an upper scrubber axis and a lower scrubber having a lower scrubber axis, said upper scrubber of said second set being mounted to said upper scrubber carrier, said lower scrubber of said second set being mounted to said lower scrubber carrier, said scrubber axes of said second set being generally codirectional with said scrubber carrier axes, said scrubbers of said second set being in said operative positions when said scrubber carriers are in said second positions.

6. The double sided scrubber system of claim 1, further comprising means for applying a liquid on the surfaces of the wafer to prevent surface damage by the scrubbers.

7. The double sided scrubber system of claim 1, wherein said scrubber axes converge when the scrubbers are in said operative positions.

8. The double sided scrubber system of claim 1 wherein at least a part of said frictional force difference is created by providing at least one of said scrubbers with a lower radial compressibility adjacent one end than adjacent the other end.

9. The double sided scrubber system of claim 1 wherein at least a part of said frictional force difference is created by providing at least one of said scrubbers with a first material in engagement with the wafer at the first end of such scrubber and a second material different from said first material at the second end of such scrubber.

10. The double sided scrubber system of claim 9 wherein said at least one of said scrubbers has a foam material covering one end of the scrubber and bristles at the other end of the scrubber.

11. The double sided scrubber system of claim 1, wherein said constraint structure comprises a movable support structure disposed on an indexing conveyor.

12. The double sided scrubber system of claim 1, wherein at least one of said scrubbers is tapered such that one end of such scrubber has a larger diameter than the other end of such scrubber.

13. The double sided scrubber system of claim 1, wherein at least one of said scrubbers is formed of a sponge material.

14. The double sided scrubber system of claim 1, wherein at least one of said scrubbers includes a layer of bristles.

15. The double sided scrubber system of claim 14, wherein said layer of bristles comprises bristles having varying degrees of stiffness.

16. The double sided scrubber system of claim 1, wherein when said scrubbers are brought into contact with the wafer surfaces said scrubbers contact the top and bottom surfaces of the wafer in regions of contact extending entirely across the wafer.

17. A method of cleaning a wafer having a top surface and a bottom surface comprising the steps of:

a) engaging an upper scrubber and a lower scrubber of a first scrubber set with top and bottom surfaces of the wafer, each of said scrubbers having a first end, a second end and an axis extending between the first and second ends, said axes of said scrubbers extending across the top and bottom surfaces of the wafer so that first ends of the scrubbers are disposed on one side of the center of the wafer whereas second ends of the scrubbers are disposed on the other side of the center of the wafer, said scrubbers engaging the wafer with a first frictional force adjacent the first ends of the scrubbers and with a second frictional force different from said first frictional force adjacent the second ends of the scrubbers to thereby provide a frictional force difference; and

b) driving the scrubbers in rotation about their respective axes in opposite rotational directions so that differences in frictional forces applied by said scrubbers to the wafer impel the wafer in rotation about a central axis transverse to the axes of the scrubbers and transverse to the top and bottom surfaces of the wafer.

18. The method of cleaning a wafer as claimed in claim 17 further including the step of providing a liquid on the surfaces of the wafer to prevent surface damage by the scrubbers.

19. The method of cleaning a wafer as claimed in claim 17 further including the step of moving a second scrubber set into engagement with the wafer surfaces after ceasing rotation of the first scrubber set.

20. The method of cleaning a wafer as claimed in claim 17, wherein said frictional force difference is created by engaging the scrubbers with said wafer so that the scrubbers axes converge at one end.

21. The method of cleaning a wafer as claimed in claim 17 wherein said frictional force difference is created by providing at least one of said scrubbers with a lower radial compressibility adjacent one end than adjacent the other end.