Method and device for protecting micro electromechanical systems structures during dicing of a wafer

• US 20020076848A1
• Filed: 12/05/2001
• Published: 06/20/2002
• Est. Priority Date: 12/05/2000
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Spooner, Timothy R., Courage, David S., Workman, Brad
• Granted Patent: US 7,022,546 B2
• Time in Patent Office: Days
• US Class Current: 438/48
• CPC Class Codes: B81C 1/00888 Multistep processes involving only mechanical separation, e.g. grooving followed by cleaving
• CPC Class Codes: B81C 1/00896 Temporary protection during separation into individual elements
• CPC Class Codes: H01L 21/6836 Wafer tapes, e.g. grinding or dicing support tapes adhesive tapes in general C09J7/20
• CPC Class Codes: H01L 2221/68327 used during dicing or grinding

Abstract

A wafer cap protects micro electromechanical system (“MEMS”) structures during a dicing of a MEMS wafer to produce individual MEMS dies. A MEMS wafer is prepared having a plurality of MEMS structure sites thereon. Upon the MEMS wafer, the wafer cap is mounted to produce a laminated MEMS wafer. The wafer cap is recessed in areas corresponding to locations of the MEMS structure sites on the MEMS wafer. The capped MEMS wafer can be diced into a plurality of MEMS dies without causing damage to or contaminating the MEMS die.

Claims

1. A method for protecting a MEMS structure during a dicing of a MEMS wafer to produce individual MEMS dies, comprising the steps of:

(a) preparing a MEMS wafer having a plurality of MEMS structure sites on a first side and a plurality of through holes on a second side;

(b) mounting, upon the first side of the MEMS wafer, a wafer cap to produce a laminated MEMS wafer, the wafer cap being recessed in areas corresponding to locations of the MEMS structure sites on the MEMS wafer;

(c) mounting, upon the second side of the MEMS wafer, a layer of dicing tape;

(d) dicing the laminated MEMS wafer into a plurality of MEMS dies; and

(e) mounting, upon the layer of dicing tape, a layer of transfer tape

2. The method as claimed in claim 1, wherein the layer of dicing tape has a UV releasable adhesive.

3. The method as claimed in claim 1, wherein the layer of dicing tape is applied to a second side of the MEMS wafer after the wafer cap is mounted on the MEMS wafer.

4. The method as claimed in claim 1, wherein the layer of dicing tape is applied to a second side of the MEMS wafer before the wafer cap is mounted on the MEMS wafer.

5. The method as claimed in claim 1, wherein the wafer cap comprises a wafer cover and a spacer layer

6. The method as claimed in claim 5, wherein the spacer layer comprises a flexible film with an adhesive medium on one side.

7. The method as claimed in claim 6, wherein the flexible film is transmissive to UV radiation.

8. The method as claimed in claim 5, wherein the wafer cover is a cover tape.

24. The method as claimed in claim 1, wherein said layer of transfer tape is applied to the dicing tape after said layer of dicing tape and the laminated MEMS wafer are sawn.

25. The method as claimed in claim 1, wherein said layer of dicing tape comprises a static dissipative material.

32. The method as claimed in claim 1 wherein the layer of dicing tape comprises a cover tape and a perforated tape.

33. The method as claimed in claim 32, wherein the cover tape includes an adhesive medium.

34. The method as claimed in claim 33, wherein the adhesive medium is an ultraviolet light releasable medium

35. The method as claimed in claim 33, wherein the adhesive medium is a heat releasable medium.

36. The method as claimed in claim 33, wherein the adhesive medium is a combination of an ultraviolet light and heat releasable medium.

37. The method as claimed in claim 33, wherein the adhesive medium comprises a thermoplastic organic material.

38. The method as claimed in claim 33, wherein the adhesive medium comprises an ultraviolet light sensitive organic material.

39. The method as claimed in claim 32, wherein the cover tape comprises a static dissipative material.

40. The method as claimed in claim 32, wherein the perforated tape comprises a tape having adhesive on two sides and a flexible film.

41. The method as claimed in claim 32, wherein the perforated tape comprises a flexible film with an adhesive medium on one side.

42. The method as claimed in claim 40, wherein the flexible film is transmissive to UV radiation.

43. The method as claimed in claim 41, wherein the flexible film is transmissive to UV radiation.

45. The method as claimed in claim 32, wherein the perforated tape comprises a plurality of layers of perforated tape, an aggregate of the plurality of layers of perforated tape producing the height to prevent electrostatically induced damage.

9. The method as claimed in 5, wherein a height of the spacer layer prevents the wafer cover from deflecting in such a manner to come in contact with the MEMS structures.

10. The method as claimed in 5, wherein a height of the spacer layer prevents electrostatically induced damage to the MEMS wafer.

11. The method as claimed in 5, wherein a height of the spacer layer prevents electrostatically induced damage to the MEMS wafer and prevents the wafer cover from deflecting in such a manner to come in contact with the MEMS structures.

13. The laminated MEMS wafer as claimed in claim 11, wherein said layer of dicing tape has a UV releasable adhesive.

14. The laminated MEMS wafer as claimed in claim 11, wherein said layer of dicing tape is applied to a second side of the MEMS wafer after said removable wafer cap is mounted on the MEMS wafer.

15. The laminated MEMS wafer as claimed in claim 11, wherein said layer of dicing tape is applied to a second side of the MEMS wafer before said removable wafer cap is mounted on the MEMS wafer.

16. The laminated MEMS wafer as claimed in claim 11, wherein said removable wafer cap comprises a wafer cover and a spacer layer

17. The laminated MEMS wafer as claimed in claim 16, wherein said spacer layer comprises a tape having adhesive on two sides and a flexible film.

18. The laminated MEMS wafer as claimed in claim 16, wherein said spacer layer comprises a flexible film with an adhesive medium on one side.

19. The laminated MEMS wafer as claimed in claim 17, wherein said flexible film is transmissive to UV radiation

20. The laminated MEMS wafer as claimed in claim 18, wherein said flexible film is transmissive to UV radiation.

21. The laminated MEMS wafer as claimed in claim 16, wherein said wafer cover is a cover tape.

46. The laminated MEMS wafer as claimed in claim 12, wherein said layer of dicing tape comprises a cover tape and a perforated tape.

12. A laminated MEMS wafer, comprising:

a MEMS wafer having a plurality of MEMS structure sites located on a first side and a plurality of through holes located on a second side;

a removable wafer cap;

a layer of dicing tape mounted upon the second side of the MEMS wafer; and

a layer of transfer tape mounted upon said layer of dicing tape;

said removable wafer cap being bonded to the first side of the MEMS wafer to produce a laminated MEMS wafer, the wafer cap being recessed in areas corresponding to locations of the MEMS structure sites on the MEMS wafer.

22. The laminated MEMS wafer as claimed in 16, wherein a height of said spacer layer prevents said wafer cover from deflecting in such a manner to come in contact with the MEMS structures.

27. The method as claimed in claim 26, wherein the layer of dicing tape has a UV releasable adhesive.

28. The method as claimed in claim 26, further comprising the step of:

(d) removing the individual diced dies from the wafer.

29. The method as claimed in claim 28, wherein individual dies are removed by initially exposing the dicing tape to UV radiation and disengaging the dies from the dicing tape with a die ejection needle assembly.

23. The laminated MEMS wafer as claimed in 16, wherein a height of said spacer layer prevents electrostatically induced damage to said MEMS wafer.

26. A method for protecting a wafer during a dicing, comprising the steps of:

(a) mounting, upon a backside of a wafer, a layer of dicing tape, the wafer having a front patterned side and a plurality of etched ports on a backside, the etched ports providing a possible leak path from a backside of the wafer to the front patterned side of the wafer;

(b) dicing the wafer into a plurality of dies; and

(c) mounting, upon the diced layer of dicing tape, a layer of transfer tape.

30. A wafer, comprising:

a wafer having a front patterned side and a plurality of etched ports on a backside, the etched ports providing a possible leak path from a backside of the wafer to the front patterned side of the wafer;

a layer of dicing tape mounted upon the backside of said wafer; and

a layer of transfer tape mounted upon said layer of dicing tape.

31. The laminated MEMS wafer as claimed in claim 30, wherein said layer of dicing tape has a UV releasable adhesive.

44. The method as claimed in 32, wherein a height of the perforated tape prevents electrostatically induced damage.

47. The laminated MEMS wafer as claimed in claim 46, wherein said cover tape includes an adhesive medium.

48. The laminated MEMS wafer as claimed in claim 47, wherein the adhesive medium is an ultraviolet light releasable medium.

49. The laminated MEMS wafer as claimed in claim 47, wherein the adhesive medium is a heat releasable medium.

50. The laminated MEMS wafer as claimed in claim 47, wherein the adhesive medium is a combination of an ultraviolet light and heat releasable medium.

51. The laminated MEMS wafer as claimed in claim 47, wherein the adhesive medium comprises a thermoplastic organic material.

52. The laminated MEMS wafer as claimed in claim 47, wherein the adhesive medium comprises an ultraviolet light sensitive organic material.

53. The laminated MEMS wafer as claimed in claim 46, wherein said cover tape comprises a static dissipative material.

54. The laminated MEMS wafer as claimed in claim 46, wherein said perforated tape comprises a static dissipative material.

55. The laminated MEMS wafer as claimed in claim 46, wherein said perforated tape comprises a tape having adhesive on two sides and a flexible film.

56. The laminated MEMS wafer as claimed in claim 46, wherein said perforated tape comprises a flexible film with an adhesive medium on one side.

57. The laminated MEMS wafer as claimed in claim 55, wherein said flexible film is transmissive to UV radiation.

58. The laminated MEMS wafer as claimed in claim 56, wherein said flexible film is transmissive to UV radiation.

60. The laminated MEMS wafer as claimed in claim 46, wherein said perforated tape comprises a plurality of layers of perforated tape, an aggregate of the plurality of layers of perforated tape producing the height to prevent electrostatically induced damage.

59. The laminated MEMS wafer as claimed in 46, wherein a height of said perforated tape prevents electrostatically induced damage.