Hermetically sealed microstructure package

• US 6,828,674 B2
• Filed: 06/05/2002
• Issued: 12/07/2004
• Est. Priority Date: 04/10/2000
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Karpman, Maurice
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): Sarkar, Asok Kumar
• Application Number:
  US10/164,064
• Publication Number:
  US 20030006502A1
• Time in Patent Office: 916 Days
• Field of Search: 257/678, 257/680, 257/704, 257/710, 257/711, 257/737, 257/738, 257/773, 257/774, 257/777, 257/778, 257/784, 257/787, 257/788, 257/790, 257/794, 438/25-33, 438/110, 438/113, 438/114, 438/460-462, 438/465, 438/613
• US Class Current: 257/711
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00357 involving bonding one or several substrates on a non-temporary support, e.g. another substrate
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/16235 Connecting to a semiconductor or solid-state bodies, i.e. cap-to-chip
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/207 Diameter ranges

Abstract

A hermetically sealed wafer scale package for micro-electrical-mechanical systems devices. The package consists of a substrate wafer which contains a microstructure and a cap wafer which contains other circuitry and electrical connectors to connect to external applications. The wafers are bonded together, and the microstructure sealed, with a sealant, which in the preferred embodiment is frit glass. The wafers are electrically connected by a wire bond, which is protected by an overmold. Electrical connectors are applied to the cap wafer, which are electrically linked to the outputs and inputs of the microstructure. The final package is small, easy to manufacture and test, and more cost efficient than current hermetically sealed microstructure packages.

Claims

1. A process for manufacturing microstructure packages, comprising steps of:

hermetically sealing a plurality of microstructures on a substrate, each microstructure being hermetically sealed within an individual cavity that is not completely filled during the sealing process, thereby allowing movement of the microstructure within the cavity;

providing electrical connections to the individual microstructures;

disposing a protective dielectric substance over the electrical connections while the substrate is intact; and

dividing the substrate having the microstructures sealed thereon into sections so as to form individual microstructure assemblies.

2. The process of claim 1, wherein the step of providing electrical connections comprises electrically connecting each microstructure to circuitry on or in an upper portion of the seal for that microstructure.

3. The process of claim 2, wherein the step of electrically connecting comprises:

electrically connecting each microstructure to corresponding circuitry on or in the substrate; and

electrically connecting the corresponding circuitry on or in the substrate for each microstructure to the circuitry on or in the upper portion of the seal for that microstructure.

4. The process of claim 3, wherein the step of electrically connecting further comprises using wire bonds to electrically connect the circuitry on or in the substrate for each microstructure to the circuitry on or in the upper portion of the seal for that microstructure.

5. The process of claim 4, wherein the step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold over the wire bonds.

6. The process of claim 1, wherein the step of hermetically sealing comprises:

surrounding each microstructure with a coolable material;

attaching a cap to the coolable material surrounding each microstructure; and

allowing the coolable material to cool thereby forming hermetically sealed cavities containing the microstructures.

7. The process of claim 6, wherein the coolable material comprises flit glass.

8. The process of claim 6, wherein the cap comprises a wafer that has circuitry fabricated thereon at the time the step of attaching the cap to the coolable material is performed.

9. The process of claim 6, wherein the cap comprises a wafer with an attached flex circuit.

10. The process of claim 1, wherein the step of dividing comprises using a wafer saw to separate-the microstructure assemblies.

11. The process of claim 1, wherein the step of providing electrical connections comprises using wire bonds to electrically connect circuitry on or in the substrate to circuitry on or in upper portions of the seals of the microstructures.

12. The process of claim 1, wherein the step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold between the microstructure cavities.

13. The process of claim 1, wherein the step of providing electrical connections is performed after the step of hermetically sealing the plurality of microstructures has been performed.

14. The process of claim 1, wherein the plurality of microstructures comprises MEMS devices.

15. The process of claim 1, wherein the step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold over the electrical connections.

16. The process of claim 1, wherein:

the step of hermetically sealing comprises using a single wafer cap to simultaneously hermetically seal the plurality of microstructures on the substrate; and

the process further comprises a step of removing portions of the single wafer cap while the substrate is intact to provide access to areas thereunder.

17. The process of claim 16, wherein the step of hermetically sealing further comprises attaching the wafer cap to glass surrounding the plurality of microstructures.

18. The process of claim 1, wherein:

the step of hermetically sealing comprises attaching a wafer cap to glass surrounding each microstructure.

19. A process for manufacturing wafer-scale microstructure packages, comprising steps of:

hermetically sealing a plurality of microstructures on a substrate while the substrate is intact, each microstructure being hermetically sealed within a cavity that is not completely filled during the sealing process, thereby allowing movement of the microstructure within the cavity;

separating the substrate having the microstructures sealed thereon into sections so as to form individual microstructure packages; and

before separating the substrate to form the individual microstructure packages, securing electrically conductive leads to each of the packages, the leads being configured and arranged to directly contact circuitry on a circuit board and to electrically connect the microstructure in the package to that circuitry.

20. The process of claim 19, wherein the step of hermetically sealing comprises sealing the microstructures within the cavities so that the microstructures are free to move within the cavities.

21. The process of claim 19, wherein the plurality of microstructures comprises MEMS devices.

22. The process of claim 19, wherein:

the step of hermetically sealing comprises using a single wafer cap to simultaneously hermetically seal the plurality of microstructures on the substrate; and

the process further comprises a step of removing portions of the single wafer cap while the substrate is intact to provide access to areas thereunder.

23. The process of claim 22, wherein the step of hermetically sealing further comprises attaching the wafer cap to glass surrounding the plurality of microstructures.

24. The process of claim 19, wherein:

the step of hermetically sealing comprises attaching a wafer cap to glass surrounding each microstructure.

25. A microstructure package manufactured according to a process, the process comprising steps of:

hermetically sealing a plurality of microstructures on a substrate, each microstructure being hermetically sealed within an individual cavity that is not completely filled during the sealing step, thereby allowing the microstructure to move within the cavity;

providing electrical connections to the individual microstructures;

disposing a protective dielectric substance over the electrical connections while the substrate is intact; and

dividing the substrate having the microstructures sealed thereon into sections so as to form individual microstructure assemblies.

26. The microstructure package manufactured according to the process of claim 25, wherein the process step of providing electrical connections comprises electrically connecting each microstructure to circuitry on or in an upper portion of the seal for that microstructure.

27. The microstructure package manufactured according to the process of claim 26, wherein the step of electrically connecting comprises:

electrically connecting each microstructure to corresponding circuitry on or in the substrate; and

electrically connecting the corresponding circuitry on or in the substrate for each microstructure to the circuitry on or in the upper portion of the seal for that microstructure.

28. The microstructure package manufactured according to the process of claim 27, wherein the step of electrically connecting further comprises using wire bonds to electrically connect the circuitry on or in the substrate for each microstructure to the circuitry on or in the upper portion of the seal for that microstructure.

29. The microstructure package manufactured according to the process of claim 28, wherein the step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold over the wire bonds.

30. The microstructure package manufactured according to the process of claim 25, wherein the process step of hermetically sealing comprises:

surrounding each microstructure with a coolable material;

attaching a cap to the coolable material surrounding each microstructure; and

allowing the coolable material to cool thereby forming hermetically sealed cavities containing the microstructures.

31. The microstructure package manufactured according to the process of claim 30, wherein the cap comprises a wafer that has circuitry fabricated thereon at the time the step of attaching the cap to the coolable material is performed.

32. The microstructure package manufactured according to the process of claim 30, wherein the cap comprises a wafer with an attached flex circuit.

34. The microstructure package manufactured according to the process of claim 25, wherein the process step of dividing comprises using a wafer saw to separate the microstructure assemblies.

35. The microstructure package manufactured according to the process of claim 25, wherein the process step of providing electrical connections comprises using wire bonds to electrically connect circuitry on or in the substrate to circuitry on or in upper portions of the seals of the microstructures.

36. The microstructure package manufactured according to the process of claim 25, wherein the process step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold between the microstructure cavities.

37. The microstructure package manufactured according to the process of claim 25, wherein the step providing electrical connections is performed after the step of hermetically sealing the plurality of microstructures.

38. The microstructure package manufactured according to the process of claim 25, wherein the plurality of microstructures comprises MEMS devices.

39. The microstructure package manufactured according to the process of claim 25, wherein the step of disposing the protective dielectric substance over the electrical connections comprises disposing an overmold over the electrical connections.

40. The microstructure package manufactured according to the process of claim 25, wherein:

the process step of hermetically sealing comprises using a single wafer cap to simultaneously hermetically seal the plurality of microstructures on the substrate; and

the process further comprises a step of removing portions of the single wafer cap while the substrate is intact to provide access to areas thereunder.

41. The microstructure package manufactured according to the process of claim 40, wherein the process step of hermetically sealing further comprises attaching the wafer cap to glass surrounding the plurality of microstructures.

33. The microstructure package manufactured according to the process of claim wherein the coolable material comprises frit glass.

42. The microstructure package manufactured according to the process of claim therein the process step of hermetically sealing comprises attaching a wafer cap to glass surrounding each microstructure.

43. A microstructure package manufactured according to a process, the process comprising the following steps:

hermetically sealing a plurality of microstructures on a substrate while the substrate is intact, each microstructure being hermetically sealed within a cavity that is not completely filled during the sealing process, thereby allowing the microstructure to move within the cavity;

separating the substrate having the microstructures sealed thereon into sections so as to form individual microstructure packages; and

before separating the substrate to form the individual microstructure packages, securing electrically conductive leads to each of the packages, the leads being configured and arranged to directly contact circuitry on a circuit board and to electrically connect the microstructure in the package to that circuitry.

44. The microstructure package manufactured according to the process of claim 43, wherein the plurality of microstructures comprises MEMS devices.

45. The microstructure package manufactured according to the process of claim 43, wherein:

the process step of hermetically sealing comprises using a single wafer cap to simultaneously hermetically seal the plurality of microstructures on the substrate; and

the process further comprises a step of removing portions of the single wafer cap while the substrate is intact to provide access to areas thereunder.

46. The micro structure package manufactured according to the process of claim 45, wherein the process step of hermetically sealing further comprises attaching the wafer cap to glass surrounding the plurality of microstructures.

47. The microstructure package manufactured according to the process of claim 43, wherein the step of hermetically sealing comprises attaching a wafer cap to glass surrounding each microstructure.

48. A process for manufacturing MEMS device packages, comprising steps of:

hermetically sealing a plurality of MEMS devices on a substrate, each MEMS device being hermetically sealed within an individual cavity;

providing electrical connections to the individual MEMS devices;

disposing a protective dielectric substance over the electrical connections while the substrate is intact; and

dividing the substrate having the MEMS devices hermetically sealed thereon into sections so as to form individual MEMS device assemblies.

49. A process for manufacturing MEMS device packages, comprising steps of:

hermetically sealing a plurality of MEMS devices on a substrate while the substrate is intact;

separating the substrate having the MEMS devices hermetically sealed thereon into sections so as to form individual MEMS device packages; and

before separating the substrate to form the individual microstructure packages, securing electrically conductive leads to each of the packages, the leads being configured and arranged to directly contact circuitry on a circuit board and to electrically connect the microstructure in the package to that circuitry.