Electronic device including MEMS devices and holed substrates, in particular of the LGA or BGA type

• US 7,875,942 B2
• Filed: 01/04/2008
• Issued: 01/25/2011
• Est. Priority Date: 01/04/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV), STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV), STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Cortese, Mario, Combi, Chantal, Myers, Edward, Baldo, Lorenzo, Azzopardi, Mark Anthony
• Primary Examiner(s): Smith; Bradley K
• Assistant Examiner(s): MILLER, JAMI VALENTINE
• Application Number:
  US12/006,819
• Publication Number:
  US 20080179697A1
• Time in Patent Office: 1,117 Days
• Field of Search: 257/415, 257/698, 257/E23.19, 257/E21.5, 257/E29.324, 438/51, 438/125
• US Class Current: 257/415
• CPC Class Codes: B81B 7/0061 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: H01L 2224/0554 External layer
• CPC Class Codes: H01L 2224/0555 Shape
• CPC Class Codes: H01L 2224/0556 Disposition
• CPC Class Codes: H01L 2224/0557 the external layer being disposed on a via connection of the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05571 the external layer being disposed in a recess of the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/056 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/1461 MEMS

Abstract

An electronic device includes a substrate provided with a passing opening and a MEMS device including an active surface wherein a portion of the MEMS device is integrated sensitive to chemical/physical variations of a fluid. The active surface of the MEMS device faces the substrate and is spaced therefrom, the sensitive portion being aligned to the opening. A protective package incorporates at least partially the MEMS device and the substrate, leaving at least the sensitive portion of the MEMS device, and the opening of the substrate exposed. A barrier element is positioned in an area which surrounds the sensitive portion to realize a protection structure for the MEMS device, so that the sensitive portion is free.

Claims

1. An electronic device, comprising:

a substrate provided with a passing opening,

a MEMS device comprising an active surface wherein a portion of said MEMS device is integrated to be sensitive to chemical/physical variations of a fluid,

wherein said active surface of said MEMS device faces said substrate and is spaced therefrom, said sensitive portion being aligned to said opening, and in that it also comprised;

a non-semiconductor protective package, which incorporates at least partially said MEMS device and said substrate, leaving at least said sensitive portion of said MEMS device, and said opening of the substrate exposed; and

a barrier element positioned in an area which surrounds said sensitive portion for realizing a protection structure for said MEMS device, so that said sensitive portion is free.

2. The electronic device according to claim 1, wherein said barrier element comprises a ring that is in contact with the surface of said substrate and with the active surface of said MEMS device, and whose external edge is completely coated by said protective package.

3. The electronic device according to claim 1, wherein said barrier element comprises welding paste.

4. The electronic device according to claim 1, wherein said barrier element comprises an irregular area formed on the surface of the substrate.

5. The electronic device according to claim 4, wherein this irregular area extends on the surface of said substrate in correspondence with said sensitive portion.

6. The electronic device according to claim 4, wherein this irregular area is obtained by modifying the chemical properties of the surface of the substrate.

7. The electronic device according to claim 4, wherein said irregular area is formed by a non-wettable material.

8. The electronic device according to claim 1, wherein electric connections which electrically couple said MEMS device with said substrate are present outside said barrier element with respect to said sensitive portion.

9. The electronic device according to claim 8, wherein an underfiller incorporates said electric connections.

10. The electronic device according to claim 8, wherein said electric connections comprise bumps.

11. The electronic device according to claim 1, wherein said MEMS device is mounted on said substrate by means of the known “

flip-chip”

assembling method.

12. The electronic device according to claim 1, wherein said MEMS device is completely enclosed in said protective package.

13. The electronic device according to claim 1, wherein said protective package leaves also the non active surface of said MEMS device exposed.

14. The electronic device according to claim 9, wherein said underfiller shows a tapered profile outside said peripheral area, while it shows a substantially vertical profile in correspondence with said area which surrounds said sensitive portion.

15. The electronic device according to claim 1, further comprising integrated circuits mounted flanked or piled onto the MEMS device.

16. The electronic device according to claim 15, wherein said integrated circuits are electrically connected to conductive tracks present on said substrate, by means of further electric connections.

17. The electronic device according to claim 15, wherein said protective package incorporates said integrated circuits and said further electric connections.

18. The electronic device according to claim 1, wherein said substrate is of the LGA type.

19. The electronic device according to claim 1, wherein said substrate is of the BGA type.

20. The electronic device according to claim 1, wherein said MEMS device comprises a pressure sensor.

21. The electronic device according to claim 1, wherein said MEMS device comprises a gas sensor.

22. The electronic device according to claim 1, wherein said MEMS device comprises a chemical sensor.

23. The electronic device according to claim 1, wherein the protective package is realized through molding.

24. The electronic device according to claim 1, wherein said barrier element comprises an irregular area formed on the active surface of the MEMS device.

25. The electronic device according to claim 24, wherein this irregular area extends on the sensitive portion of the MEMS device.

26. The electronic device according to claim 24, wherein this irregular area is obtained by modifying the chemical properties around/of the active surface of the MEMS device.

27. The electronic device according to claim 24, wherein this irregular area is formed by non wettable material.

28. The electronic device according to claim 27, wherein the MEMS device comprises a protection layer on the active surface wherein said irregular area is formed by means of removal of said protection layer from the sensitive portion of the MEMS device exposing said layer of non wettable material.

29. The electronic device according to claim 28, wherein said protection layer is Polyimide and said layer of non wettable material is oxide.

31. The electronic device according to claim 4, wherein a layer of non wettable material is formed in correspondence with said sensitive portion of said MEMS device.

32. The electronic device according to claim 9, wherein a barrier element protects the sensitive portion during the formation of said underfiller.

30. An electronic device, comprising:

a substrate provided with a passing opening,

a MEMS device comprising an active surface wherein a portion of said MEMS device is integrated to be sensitive to chemical/physical variations of a fluid,

wherein said active surface of said MEMS device faces said substrate and is spaced therefrom, said sensitive portion being aligned to said opening, and in that it also comprised;

a protective package, which incorporates at least partially said MEMS device and said substrate, leaving at least said sensitive portion of said MEMS device, and said opening of the substrate exposed; and

a barrier element comprising an irregular area formed on the surface of the substrate positioned in an area which surrounds said sensitive portion for realizing a protection structure for said MEMS device, so that said sensitive portion is free;

wherein said irregular area comprises trenches which form preferred paths during the formation steps of the protective package.

33. An electronic device, comprising:

a substrate including a passing opening;

a die coupled to the substrate, the die including an active surface and the active surface including a sensitive portion positioned adjacent the passing opening of the substrate and the die being operable to sense a physical parameter of a medium to which the sensitive portion is exposed through the passing opening;

a protective package housing the substrate and the die; and

a barrier element formed surrounding the sensitive portion to isolate the sensitive portion from the protective package.

34. The electronic device of claim 33, wherein the barrier element comprises a ring formed adjoining a surface of the substrate and the active surface of die.

35. The electronic device of claim 34, wherein the barrier element includes a periphery surface that is completely covered by the protective package.

36. The electronic device of claim 33, wherein the barrier element comprises an irregular area formed on a surface of the substrate surrounding and adjacent to the passing opening.

37. The electronic device of claim 33, wherein the barrier element comprises an irregular area formed on the active surface of the die surrounding the sensitive portion.

38. The electronic device of claim 33, wherein the die comprises a MEMS device.

39. The electronic device of claim 33, wherein the medium comprises a fluid.

40. The electronic device of claim 39, wherein the physical parameter of the fluid comprises a chemical property of the fluid.

41. The electronic device of claim 33, further comprising at least one additional die electronically coupled to the substrate.

42. The electronic device of claim 41, wherein at least one additional die is formed on the substrate flanking the die.

43. An electronic system, comprising:

electronic circuitry including a sensor, the sensor including,

a substrate including a passing opening;

a die coupled to the substrate, the die including an active surface and the active surface including a sensitive portion positioned adjacent the passing opening of the substrate and the die being operable to sense a physical parameter of a medium to which the sensitive portion is exposed through the passing opening;

a protective package housing the substrate and the die; and

a barrier element formed surrounding the sensitive portion to isolate the sensitive portion from the protective package.

44. The electronic system of claim 43, wherein the sensor comprises one of a microphone, pressure sensor, gas sensor, flow sensor, and pH sensor.

45. The electronic system of claim 43, wherein the electronic circuitry comprises one of barometric circuitry, audio circuitry, computer circuitry, control circuitry, test equipment circuitry, or safety system circuitry.