Method for singulating a released microelectromechanical system wafer

• US 7,297,567 B2
• Filed: 01/10/2006
• Issued: 11/20/2007
• Est. Priority Date: 01/10/2006
• Status: Expired due to Fees

• Current Assignee: Knowles Electronics Llc (Knowles Corporation)
• Original Assignee: Knowles Electronics Llc (Knowles Corporation)
• Inventors: Loeppert, Peter V.
• Primary Examiner(s): Smith; Matthew
• Assistant Examiner(s): SINGAL, ANKUSH K
• Application Number:
  US11/275,503
• Publication Number:
  US 20070161139A1
• Time in Patent Office: 679 Days
• Field of Search: 438/48
• US Class Current: 438/48
• CPC Class Codes: B81C 1/00896 Temporary protection during separation into individual elements

Abstract

A plurality of MEMS structures is formed on a wafer. The wafer is mounted on a dicing frame assembly having a dicing frame and a dicing tape attached to the dicing frame. A protective layer is applied to cover the entire surface of the wafer or may be limited to the portion of the surface of the wafer that includes the MEMS structures by any suitable means of coating techniques to protect the MEMS structures during dicing operation. The protective layer base material to be provided on the wafer may include linear carbon chain molecules containing 12-18 carbon atoms. The dicing operation is performed to divide the wafer into individual die. The protective layer is removed by any suitable process including decomposition, vaporized, sublimation or the like. For example, the protective layer may be evaporated through the application of heat after the die attachment process is completed. The heat application may be part of the cure cycle required for die bonding or may be a separate operation. Finally, the individual die are wire bonded and sealed to complete the packaging operation.

Claims

1. A method for protecting a MEMS structure on a wafer, the method comprising:

providing a protective layer on the plurality of MEMS structures attached to the wafer;

dicing the wafer into a plurality of MEMS die; and

removing the protective layer from individual MEMS die;

wherein the protective layer is a water insoluble coating and is selected from the group of materials consisting of linear carbon chain molecules containing 12-18 carbon atoms.

2. The method of claim 1, wherein the water insoluble coating is soluble in isopropyl alcohol.

3. The method of claim 1, wherein dicing the wafer comprises sawing the wafer using a saw.

4. The method of claim 1, wherein removing the protective layer comprises heating the protective layer.

5. A method for protecting a MEMS structure on a wafer, the method comprising:

providing a protective layer on a plurality of MEMS structures attached to the wafer;

dicing the wafer into a plurality of MEMS die; and

removing the protective layer from individual MEMS die;

wherein the protective layer is a water insoluble consists at least one Dodecanol, Heptadecanal, Heptadecanol, chlorinated material, Cetyl alcohol or polynorborene (PNB) material.

6. The method of claim 5, wherein the chlorinated material is 2,6-dichloro-2,6-dimethylheptane.

7. The method of claim 5, wherein the water insoluble coating is soluble in isopropyl alcohol.

8. The method of claim 5, wherein removing the protective layer comprises heating the protective layer.

9. The method of claim 5, wherein dicing the wafer comprises sawing the wafer using a saw.

10. A method for singulating a wafer, the method comprising:

providing a protective layer having a boiling point greater than about 100°

C.;

providing a dicing frame assembly including a dicing frame and a dicing tape attached to the dicing frame;

mounting the wafer to the dicing frame assembly; and

dicing the wafer;

wherein the protective layer is water insoluble and is selected from the group of materials consisting of linear carbon chain molecules containing 12-18 carbon atoms.

11. The method of claim 10, wherein the wafer is provided with a plurality of MEMS structures, and either or both of the wafer and the MEMS structure is or arc covered by the protective layer, respectively.

12. The method of claim 11, wherein the wafer or MEMS structures are at least partially covered by the protective layer.

13. The method of claim 11, wherein the wafer or MEMS structures are completely covered by the protective layer.

14. The method of claim 10, wherein dicing the wafer comprises dicing the wafer into a plurality of MEMS die.

15. A method for singulating a wafer, the method comprising:

providing a protective layer having a boiling point greater than about 100°

C.;

providing a dicing frame assembly including a dicing frame and a dicing tape attached to the dicing frame;

mounting the wafer to the dicing frame assembly; and

dicing the wafer;

wherein the protective layer consists of at least one of Dodecanol, Heptadecanal, Heptadecanol, or chlorinated material.

16. The method of claim 15, wherein the chlorinated material is 2,6-dichloro-2,6-dimethylheptane.

17. A method for protecting a plurality of MEMS structures on a MEMS wafer during dicing, the method comprising:

mounting a blank face of the MEMS wafer onto a dicing frame assembly including a dicing frame and a dicing tape;

coating a circuit forming face of the MEMS wafer with a protective layer; and

dicing the MEMS wafer with the protective layer and the plurality of MEMS structures into a plurality of MEMS die;

wherein the protective layer comprises a material of linear carbon chain molecules containing 12 to 18 carbon atoms consisting of Dodecanol, Heptadecanal, Heptadecanol, or 2,6-dichloro-2,6-dimethylheptane.

18. The method of claim 17, wherein the protective layer is insoluble in water.

19. The method of claim 17, wherein the protective layer is a soft solid material.

20. The method of claim 17, wherein the protective layer is one of a wax or gel.

21. The method of claim 17, wherein the protective layer has a melting point of about 50°

C.

22. The method of claim 17, wherein the protective layer has a boiling point of about 100°

C.

23. A method for protecting a plurality of MEMS structures on a circuit forming face of a wafer from damage due to sawing the wafer, the method comprising:

mounting a blank face of the wafer onto a dicing frame assembly;

coating the wafer with a protective layer;

dicing the wafer into a plurality of MEMS die; and

removing the protective layer from individual die by heating;

wherein the protective layer is water insoluble and is selected from the group of materials consisting of 12-18 carbon atoms.

24. The method of claim 23, wherein the dicing frame assembly comprises a dicing frame and a dicing tape attached to the dicing frame.

25. The method of claim 23, wherein the circuit forming face of the wafer is covered by the protective layer.

26. The method of claim 23, wherein the protective layer has a boiling point of about 150°

C. to 350°

C.

27. The method of claim 23, wherein the protective layer has a melting point of about 30°

C. to 60°

C.

28. The method of claim 23, wherein removing the protective layer is through evaporation, decomposition or sublimation.

29. A method for protecting a plurality of MEMS structures on a circuit forming face of a wafer from damage due to sawing the wafer, the method comprising:

mounting a blank face of the wafer onto a dicing frame assembly;

coating the wafer with a protective layer;

dicing the wafer into a plurality of MEMS die; and

removing the protective layer from individual MEMS die by heating;

wherein the protective layer consists of at least one of Dodecanol, Heptadecanal, Heptadecanol, or chlorinated material.

30. The method of claim 29, wherein the protective layer has a boiling point of about 150°

C. to 350°

C.

31. The method of claim 29, wherein the protective layer has a melting point of about 30°

C. to 60°

C.

32. The method of claim 29, wherein removing the protective layer is through evaporation, decomposition or sublimation.