Electronic device, system, and method comprising differential sensor MEMS devices and drilled substrates

• US 8,134,214 B2
• Filed: 07/24/2009
• Issued: 03/13/2012
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Baldo, Lorenzo, Combi, Chantal, Cortese, Mario Francesco
• Primary Examiner(s): Tran, Tan N
• Application Number:
  US12/508,869
• Publication Number:
  US 20090278215A1
• Time in Patent Office: 963 Days
• Field of Search: 257/415, 257/680, 257/E21.001
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• 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: B81C 2203/0154 Moulding a cap over the MEMS device
• CPC Class Codes: G01L 19/141 Monolithic housings, e.g. molded or one-piece housings
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• 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 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/1461 MEMS

Abstract

Electronic device which comprises a substrate provided with at least one passing opening, a MEMS device with function of differential sensor provided with a first and a second surface and of the type comprising at least one portion sensitive to chemical and/or physical variations of fluids present in correspondence with a first and a second opposed active surface thereof, the first surface of the MEMS device leaving the first active surface exposed and the second surface being provided with a further opening which exposes said second opposed active surface, the electronic device being characterized in that the first surface of the MEMS device faces the substrate and is spaced therefrom by a predetermined distance, the sensitive portion being aligned to the passing opening of the substrate, and in that it also comprises a protective package, which incorporates at least partially the MEMS device and the substrate so as to leave the first and second opposed active surfaces exposed respectively through the passing opening of the substrate and the further opening of the second surface.

Claims

1. An electronic device, comprising:

a substrate provided with at least one passing opening,

a MEMS device with function of differential sensor provided with a first and a second surface comprising at least one portion sensitive to chemical and/or physical variations of fluids present in correspondence with a first and second opposed active surface thereof, said first surface of said MEMS device leaving said first active surface exposed and said second surface being provided with a further opening which exposes said second active opposed surface, wherein said first surface of said MEMS device faces said substrate and is spaced therefrom by a determined distance, said sensitive portion being aligned to the at least one passing opening of said substrate,

the MEMS device further comprising a protective package, which incorporates at least partially said MEMS device and said substrate so as to leave said first and second opposed active surfaces exposed respectively through said passing opening of said substrate and said further opening of said second surface.

2. The electronic device according to claim 1, further comprising a barrier element which surrounds said sensitive portion for realizing a protection structure for said MEMS differential sensor device, so that said first active surface of said sensitive portion is free.

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

4. The electronic device according to claim 2, wherein said barrier element is of welding paste.

5. The electronic device according to claim 2, comprising electric connections which electrically couple said MEMS differential sensor device to said substrate are present outside said barrier element with respect to said sensitive portion.

6. The electronic device according to claim 1, wherein an underfiller incorporates said electric connections.

7. The electronic device according to claim 6, wherein a barrier element protects the sensitive portion during the formation of said underfiller.

8. The electronic device according to claim 6, 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.

9. The electronic device according to claim 2, wherein said barrier element is an irregular area formed on the upper surface of the substrate.

10. The electronic device according to claim 9, wherein this irregular area extends on the upper surface of said substrate in correspondence with said sensitive portion.

11. The electronic device according to claim 9, wherein this irregular area is obtained by modifying the chemical properties of the upper surface of the substrate.

12. The electronic device according to claim 9, wherein said irregular area is formed by non wettable material.

13. The electronic device according to claim 2, wherein said barrier element is an irregular area formed on said first surface of the MEMS differential sensor device.

14. The electronic device according to claim 13, wherein this irregular area extends on the sensitive portion of the MEMS differential sensor device.

15. The electronic device according to claim 13, wherein this irregular area is obtained by modifying the chemical properties around said first surface of the MEMS differential sensor device.

16. The electronic device according to claim 13, wherein said irregular area is formed by non wettable material.

17. The electronic device according to claim 16, wherein said first active surface of said sensitive portion is coated by a non wettable insulating layer and a protection layer, wherein said irregular area is formed through removal of said protection layer from said first surface of the MEMS differential sensor device for exposing said layer of non wettable material.

18. The electronic device according to claim 17, wherein said protection layer is Polyimide and said layer of non wettable material is oxide.

19. The electronic device according to claim 13, wherein said irregular area comprises trenches which form preferred paths during the formation steps of the protective package.

20. The electronic device according to claim 19, wherein a layer of non wettable material is formed in correspondence with said sensitive portion of said MEMS differential sensor device.

21. The electronic device according to claim 13, wherein said electric connections comprise bumps.

22. The electronic device according to claim 1, wherein said MEMS differential sensor device is mounted on said substrate through the known “

flip-chip”

assembling method.

23. The electronic device according to claim 1, further comprising integrated circuits mounted flanked to the MEMS differential sensor device.

24. The electronic device according to claim 23, wherein said integrated circuits are electrically connected to conductive tracks present on said substrate, by means of further electric connections.

25. The electronic device according to claim 24, wherein said protective package incorporates said integrated circuits and said further electric connections.

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

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

28. The electronic device according to claim 1, wherein said MEMS differential sensor device is a pressure sensor.

29. The electronic device according to claim 1, wherein said MEMS device is a gas sensor.

30. The electronic device according to claim 1, wherein said MEMS device is a chemical sensor.

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

32. The electronic device according to claim 1, wherein said protective package also coats said second surface and is provided with a passing opening aligned to the opening present on said second surface of said MEMS differential sensor device.

33. The electronic device according to claim 32, wherein a cylindrical projection is formed on said passing opening of said protective package to facilitate the access to said sensitive portion of said MEMS differential sensor device.

36. The electronic device of claim 18, wherein the die of the differential sensor device comprises a semiconductor die.

37. The electronic device of claim 19, wherein the opening in the die has wall that are substantially orthogonal to the second surface of the die.

38. The electronic device of claim 19, wherein the opening in the die has walls that taper inwardly from the second surface of the die towards the first surface of the die.

34. An electronic device, comprising:

a substrate having at least one passing opening;

a differential sensor MEMS device having at least a first and a second surface leaving exposed a first and second active surface, respectively;

a protective package incorporating at least partially said MEMS device and said substrate so as to leave exposed said first and second active surfaces;

said differential sensor having a portion being sensitive to chemical and/or physical variations of fluids getting in contact with said first and/or second active surface;

said first surface of said MEMS device facing said substrate and being spaced from said substrate by a distance;

said second surface being opposed to said first surface and having an opening for exposing said second active surface;

said sensitive portion being aligned with said passing opening of said substrate.

35. An electronic device, comprising:

a substrate having at least one passing opening formed in the substrate, the passing opening being exposed on a first surface of the substrate and on a second surface of the substrate opposing the first surface, and the substrate including at least one electrically conductive layer;

a differential sensor device including a die having first and second opposing surfaces including first and second active surface portions, respectively, wherein the first surface of the die faces the first surface of the substrate and is spaced a distance from the first surface of the substrate, the second surface of the die having an opening to expose the second active surface portion of the die and the die being physically attached to the substrate to align the first active surface portion of the die with the passing opening of the substrate, and the die being electrically connected to at least some of the electrically conductive layers in the substrate; and

a protective package formed on the substrate and die, the package leaving the first and second active surface portions of the die exposed.

39. The electronic device of claim 35, wherein the die includes conductive lands exposed on portions of the first surface of the die other than the first active surface portion of the die.

40. The electronic device of claim 39, wherein the die is electrically connected to at least some of the electrically conductive layers in the substrate through the conductive lands and conductive bumps formed between the lands and conductive lands formed on the first surface of the substrate.

41. The electronic device of claim 39, wherein the second surface of the substrate includes conductive lands formed thereon.

42. The electronic device of claim 35, wherein the protective package covers a portion of the second surface of the die and includes a further passing opening formed in the package, the further passing opening being aligned with the opening in the second surface the die to expose the second active surface portion.

43. The electronic device of claim 42, wherein the further passing opening is a cylindrical projection formed in the protective package.

44. An electronic system, comprising:

a plurality of electronic devices formed on a substrate, the substrate including, for at least some of the electronic devices, a passing opening formed in the substrate, the passing opening being exposed on a first surface of the substrate and on a second surface of the substrate opposing the first surface, and the substrate including at least one electrically conductive layer;

wherein the electronic devices include a plurality of differential sensor devices, each differential sensor device including a die having first and second opposing surfaces including first and second active surface portions, respectively, wherein the first surface of the die faces the first surface of the substrate and is spaced a distance from the first surface of the substrate, the second surface of the die having an opening to expose the second active surface portion of the die and the die being physically attached to the substrate to align the first active surface portion of the die with a corresponding one of the passing openings in the substrate, and the die being electrically connected to at least some of the electrically conductive layers in the substrate; and

a protective package formed on the substrate and the electronic devices, the package leaving the first and second active surface portions of the die of each differential sensor device exposed.

45. The electronic system of claim 44 where in at least some of the electronic devices comprise MEMS devices.

46. The electronic system of claim 45 wherein at least some of the MEMS devices comprise pressure sensors.

47. The electronic system of claim 45 wherein at least some of the MEMS devices comprise accelerometers.

48. The electronic system of claim 44 wherein the electronic devices including the differential pressure sensor devices collectively function as a one of a vehicle safety system, cellular telephone, personal digital assistant, video game controller, computer system, and control system.