Method and apparatus for flag-less water bonding tool

• US 7,479,441 B2
• Filed: 10/13/2006
• Issued: 01/20/2009
• Est. Priority Date: 10/14/2005
• Status: Expired due to Fees

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois J., Kirk, Harry R., Ong, Philip James
• Primary Examiner(s): Nguyen, Tuan H
• Application Number:
  US11/581,065
• Publication Number:
  US 20070087531A1
• Time in Patent Office: 830 Days
• Field of Search: 438/455, 438/457, 438/118, 156/153, 156/349
• US Class Current: 438/455
• CPC Class Codes: H01L 21/187 by direct bonding
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D

Abstract

Embodiments in accordance with the present invention relate to methods and apparatuses for bonding together substrates in a manner that suppresses the formation of voids between them. In a specific embodiment, a backside of each substrate is adhered to a front area of flexible, porous chuck having a rear area in pneumatic communication with a vacuum. Application of the vacuum causes the chuck and the associated substrate to slightly bend. Owing to this bending, physical contact between local portions on the front side of the flexed substrates may be initiated, while maintaining other portions on front side of the substrates substantially free from contact with each other. A bond wave is formed and maintained at a determined velocity to form a continuous interface joining the front sides of the substrates, without formation of voids therebetween. In one embodiment, the chucks may comprise porous polyethylene sealed with polyimide except for a portion of the front configured to be in contact with the substrate, and a portion of the backside configured to be in communication with a vacuum source.

Claims

1. A method for forming multi-layered materials, the method comprising:

providing a first substrate having a first backside surface supported on a first porous chuck, and a first surface region, the first surface region being characterized by a first end and a second end;

providing a second substrate having a second backside surface supported on a second porous chuck, and a second surface region, the second surface region being characterized by a third end and a fourth end;

initiating a physical contact of a first predetermined portion of the first end of the first surface region with a second predetermined portion of the third end of the second surface region, while maintaining utilizing the first and second porous chucks, other portions of the first surface region and the second surface region substantially free from joining the other portions of the first surface region to the second surface region;

causing a bond wave to form by an interface region within a vicinity of the first predetermined portion and the second predetermined portion;

moving, using a controlled process, the bond wave from the first end of the first surface and the third end of the second surface to the second end of the first surface and the fourth end of the second surface while maintaining a determined velocity of the bond wave to form a continuous interface to join the first surface of the first substrate with the second surface of the second surface.

2. The method of claim 1 wherein the first substrate is a silicon wafer.

3. The method of claim 1 wherein the second substrate is a silicon wafer.

4. The method of claim 1 wherein the first substrate is patterned.

5. The method of claim 1 wherein the second substrate is patterned.

6. The method of claim 1 wherein the continuous interface is substantially free from one or more voids.

7. The method of claim 1 wherein the first surface region comprises an activated region.

8. The method of claim 1 wherein the second surface region comprises an activated region.

9. The method of claim 1 wherein the first chuck is flexible and adapted to change in shape to facilitate the controlled process.

10. The method of claim 1 wherein the second chuck is flexible and adapted to change in shape to facilitate the controlled process.

11. The method of claim 1 further comprising performing a plasma activation process on either one or both of the first surface region and the second surface region before initiating the physical contact.

12. The method of claim 1 wherein the first substrate and the second substrate is maintained in a vacuum environment during the formation of the bondwave and formation of the continuous interface.

13. The method of claim 1 further comprising maintaining the first surface region and the second surface region substantially free from any mechanical flags during the movement of the bond wave from the first end of the first surface to the first end of the second surface.

14. The method of claim 1 wherein the first substrate is characterized by a diameter of about 200 mm and greater.

15. The method of claim 1 wherein the first substrate is characterized by a diameter of about 300 mm and greater.

16. The method of claim 1 wherein the second substrate is characterized by a diameter of about 200 mm and greater.

17. The method of claim 1 wherein the second substrate is characterized by a diameter of about 300 mm and greater.

18. The method of claim 1 wherein the controlled processes is provided by mechanical control.

19. The method of claim 1 wherein the controlled process is provided by chemical control.

20. The method of claim 1 wherein the controlled process is provided by thermal control.

21. The method of claim 1 wherein the controlled process is provided by a change in pressure.

22. The method of claim 1 wherein the interface region borders a bonded portion of the first surface region and the second surface region and an unbonded portion of the first surface region and the second surface region.

23. The method of claim 1 wherein the interface region is substantially continuous and free from dislocations.

24. The method of claim 1 wherein the interface region is characterized by a single front.

25. The method of claim 1 wherein the bond wave is characterized by a single front.

26. The method of claim 1 wherein the determined velocity ranges from about 10 to about 0.1 cm/seconds.

27. The method of claim 1 wherein the determined velocity is substantially constant.

28. The method of claim 1 wherein the determined velocity decreases at the second end and the fourth end.

29. The method of claim 1 wherein the first surface region comprises a compliant layer.

30. The method of claim 1 wherein the second surface region comprises a compliant layer.

31. The method of claim 1 wherein the first substrate is selected from silicon or quartz or glass.

32. The method of claim 1 wherein the first substrate is a piece of glass for a flat panel display.

33. An apparatus comprising:

a first porous and flexible chuck in pneumatic communication with a vacuum;

a second porous and flexible chuck in pneumatic communication with the vacuum;

a substrate handing apparatus configured to position a backside of a first wafer in contact with the first chuck, and to position a backside of a second wafer in contact with the second chuck; and

an energy source configured to pinch together first ends of the first and second wafers and thereby initiate a bonding wave.

34. The apparatus of claim 33 wherein the first chuck comprises a porous polymer.

35. The apparatus of claim 34 wherein the first chuck comprises porous polyethylene.

36. The apparatus of claim 34 wherein a surface of the porous polymer is sealed except for a first area configured to be in communication with the vacuum, and a second area configured to contact the backside of the substrate.

37. The apparatus of claim 33 wherein the first chuck exhibits a substantially circular shape.

38. The apparatus of claim 33 wherein the first chuck exhibits a substantially rectangular shape.

39. The apparatus of claim 33 further comprising a vacuum suction cup configured to contact a backside of a most deflected region of the first chuck.