Method of fabricating a microelectronic device package with an integral window

• US 6,531,341 B1
• Filed: 05/16/2000
• Issued: 03/11/2003
• Est. Priority Date: 05/16/2000
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Peterson, Kenneth A., Watson, Robert D.
• Primary Examiner(s): Fahmy, Wael
• Assistant Examiner(s): Kebede, Brook
• Application Number:
  US09/573,424
• Time in Patent Office: 1,029 Days
• Field of Search: 438/106-117, 438/118, 438/119, 438/124, 438/125, 438/126, 438/123, 438/122, 257/678, 257/680, 257/681, 257/704, 257/703, 174/52.4
• US Class Current: 438/123
• CPC Class Codes: B81B 7/0067 for controlling the passage of optical signals through the package
• CPC Class Codes: H01L 21/48 Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49109 outside the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 2225/0651 Wire or wire-like electrical connections from device to substrate
• CPC Class Codes: H01L 2225/06513 Bump or bump-like direct electrical connections between devices, e.g. flip-chip connection, solder bumps
• CPC Class Codes: H01L 2225/06582 Housing for the assembly, e.g. chip scale package [CSP]
• CPC Class Codes: H01L 2225/1035 the device being entirely enclosed by the support, e.g. high-density interconnect [HDI]
• CPC Class Codes: H01L 2225/1058 Bump or bump-like electrical connections, e.g. balls, pillars, posts
• CPC Class Codes: H01L 23/053 the container being a hollow construction and having an insulating or insulated base as a mounting for the semiconductor body
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 25/0657 Stacked arrangements of devices
• CPC Class Codes: H01L 25/105 : the devices being of a type provided for in group H01L27/00
• CPC Class Codes: H01L 25/50 : Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• CPC Class Codes: H01L 27/14618 : Containers
• CPC Class Codes: H01L 27/14625 : Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/1469 : Assemblies, i.e. hybrid integration
• 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 2924/00012 : 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 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01025 : Manganese [Mn]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/04941 : TiN
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 : Monolayer substrate
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/16195 : Flat cap [not enclosing an internal cavity]
• CPC Class Codes: H01L 2924/16235 : Connecting to a semiconductor or solid-state bodies, i.e. cap-to-chip
• CPC Class Codes: H01L 2924/1627 : stacked type assemblies, e.g. stacked multi-cavities
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H01L 31/0203 : Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/02327 : the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216

Abstract

A method of fabricating a microelectronic device package with an integral window for providing optical access through an aperture in the package. The package is made of a multilayered insulating material, e.g., a low-temperature cofired ceramic (LTCC) or high-temperature cofired ceramic (HTCC). The window is inserted in-between personalized layers of ceramic green tape during stackup and registration. Then, during baking and firing, the integral window is simultaneously bonded to the sintered ceramic layers of the densified package. Next, the microelectronic device is flip-chip bonded to cofired thick-film metallized traces on the package, where the light-sensitive side is optically accessible through the window. Finally, a cover lid is attached to the opposite side of the package. The result is a compact, low-profile package, flip-chip bonded, hermetically-sealed package having an integral window.

Claims

1. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising applying a surface treatment to a mating surface to improve wettability and adhesion to said corresponding mating surface.

2. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising applying an anti-reflection coating to said window.

3. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

attaching said first plate to said second plate by joining said second surface to said third surface;

wherein forming said package comprises laminating a plurality of electrically insulating sheets; and

wherein said laminating step comprises;

personalizing said sheets;

stacking and registering said personalized sheets to form a stack of personalized sheets;

holding said stack of personalized sheets as a rigid assembly; and

baking and firing said rigid assembly, whereby said stacked sheets are cofired and laminated together to form a unitized, monolithic package.

4. The method of claim 3, wherein said personalizing step comprises cutting out an individual sheet, having an outside perimeter and an interior aperture, from a larger piece of electrically insulating material.

5. The method of claim 4, wherein said personalizing step further comprises machining a hole for an electrically conductive via.

6. The method of claim 4, wherein said personalizing step further comprises depositing a conductive paste or ink on a surface of said individual sheet.

7. The method of claim 3, further comprising inserting said window into an opening within said stack of personalized sheets, concurrently while stacking and registering said personalized sheets.

8. The method of claim 3, wherein said rigid assembly is fired at a high temperature in the range of 1300 C. to 1800 C.

9. The method of claim 3, wherein said rigid assembly is fired at a low temperature in the range of 600 C. to 1300 C.

10. The method of claim 3, further comprising attaching a cover lid to said package, thereby forming a sealed package.

11. The method of claim 10, wherein attaching said cover lid further comprises using a process selected from the group consisting of brazing, hermetically sealing with frit glass, reflow soldering, plasma-assisted dry soldering, and adhesively attaching.

12. The method of claim 10, further comprising attaching a second window to said cover lid before attaching said cover lid to said package.

13. The method of claim 10, further comprising attaching a second window to said cover lid after attaching said cover lid to said package.

14. The method of claim 3, further comprising:

fabricating a second electrically conductive metallized trace disposed on said fourth surface of said second plate;

forming a third plate, having a third aperture disposed through said third plate, wherein said third aperture is larger than said second aperture; and

attaching said third plate to said fourth surface of said second plate.

15. The method of claim 14, wherein said third aperture is substantially aligned with said second aperture.

16. The method of claim 3, wherein said second aperture is substantially aligned with said first aperture.

17. The method of claim 3, further comprising:

providing a microelectronic device;

mounting said microelectronic device within said package; and

attaching a cover lid to said package, whereby said device is housed inside of a package having an integral window.

18. The method of claim 12, wherein said microelectronic device comprises a light-sensitive side.

19. The method of claim 18, further comprising orienting said light-sensitive side facing said window.

20. The method of claim 17, further comprising flip-chip mounting said microelectronic device to said electrically conductive metallized trace disposed on said second surface.

21. The method of claim 20, wherein flip-chip mounting further comprises using a process selected from the group consisting of brazing, reflow soldering, plasma-assisted dry soldering, thermocompression without vibration, thermocompression with vibration, and attachment with a conductive adhesive.

22. The method of claim 17, wherein said microelectronic device comprises a CCD chip.

23. The method of claim 17, wherein said microelectronic device comprises a MEMS or IMEMS device.

24. The method of claim 17, further comprising applying a seal in-between said microelectronic device and said second surface.

25. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising attaching a cover lid to said package, thereby forming a sealed package; and

further comprising substantially removing ambient air from inside said package; and

then replacing it with at least one gas other than air, before attaching said cover lid to said package.

26. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture;

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising fabricating said window with an integral lens.

27. The method of claim 26, wherein fabricating said window with an integral lens comprises fabricating an array of binary optic lenslets integral with said window.

28. The method of claim 26, wherein fabricating said window with an integral lens comprises casting or molding said window with said integral lens.

29. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture;

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising attaching a lens to said window.

30. A method of fabricating a microelectronic package having an integral window, comprising:

forming a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

fabricating an electrically conductive metallized trace on said second surface of said first plate;

attaching a window to said first plate;

forming a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture;

attaching said first plate to said second plate by joining said second surface to said third surface; and

further comprising attaching an electrically-switched optical modulator to said package, for modulating light passing through an aperture.

31. The method of claim 30, wherein said electrically-switched optical modulator comprises a lithium niobate window.

32. A method for packaging at least one microelectronic device in a package having an integral window, comprising:

providing a package comprising;

a first electrically insulating plate having a first surface, an opposing second surface, and a first aperture disposed through said first plate;

a first electrically conductive metallized trace on said second surface of said first plate;

an integral window attached to said first plate;

a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

wherein said second surface of said first plate is attached to said third surface of said second plate; and

further comprising;

a second electrically conductive metallized trace disposed on said fourth surface of said second plate;

a third electrically insulating plate, having a third aperture disposed through said third plate, wherein said third aperture is larger than said second aperture; and

wherein said third plate is attached to said fourth surface of said second plate;

providing a first microelectronic device;

flip-chip mounting said first microelectronic device to said first electrically conductive metallized trace disposed on said second surface;

providing a second microelectronic device;

mounting and electrically interconnecting said second microelectronic device to said second electrically conductive metallized trace disposed on said fourth surface; and

attaching a cover lid to said package.

33. The method of claim 32, wherein electrically interconnecting said second microelectronic device comprises flip-chip mounting said second microelectronic device to said second electrically conductive metallized trace disposed on said fourth surface, before attaching said cover lid to said package.

34. The method of claim 32, further comprising:

bonding together back-to-back said first microelectronic device and said second microelectronic device; and

then

wirebonding said second microelectronic device to said second electrically conductive metallized trace disposed on said fourth surface, before attaching said cover lid to said package.

35. The method of claim 34, wherein said second microelectronic device comprises a light-sensitive side facing towards said cover lid;

and further wherein said cover lid comprises a transparent material.

36. The method of claim 34, wherein bonding together back-to-back said first microelectronic device and said second microelectronic device comprises using a process selected from the group consisting of anodic bonding, eutectic bonding, soldering, and adhesive attachment.

37. A method of fabricating a microelectronic package having an integral window, comprising:

a) laminating together a plurality of individual layers of an electrically insulating material to form a first electrically insulating plate comprising a multilayered material, a first surface, an opposing second surface, and a first aperture disposed through said first plate;

b) fabricating a first electrically conductive metallized trace on said second surface of said first plate;

c) joining a window, disposed across said first aperture, to said first plate;

d) providing a second electrically insulating plate having a third surface, an opposing fourth surface, and a second aperture disposed through said second plate;

wherein said second aperture is larger than said first aperture; and

e) joining the second surface of said first plate to said third surface of said second plate.

38. The method of claim 37, wherein joining said window comprises using a joining process selected from the group consisting of casting, brazing, frit glass sealing, reflow soldering, plasma-assisted dry soldering, and attaching with adhesives.

39. The method of claim 37, further comprising attaching an electrical lead to said first metallized trace at an exterior location.

40. The method of claim 37, wherein fabricating said first electrically conductive metallized trace comprises using a screen-printed thick-film metallization process or an etched foil process.

41. The method of claim 37, wherein attaching said first plate to said second plate comprises using a process selected from the group consisting of brazing, frit glass sealing, reflow soldering, plasma-assisted dry soldering, and attaching with adhesives.

42. The method of claim 37, wherein said first electrically conductive metallized trace if fabricated after attaching said window to said first plate.

43. The method of claim 37, wherein joining said window to said first plate comprises using frit glass sealing.

44. The method of claim 37, wherein said multilayered material is selected from the group consisting of a printed wiring board composition, a low-temperature cofired ceramic composition, and a high-temperature cofired ceramic composition.

45. The method of claim 37, wherein said window is disposed inside of said first aperture.

46. The method of claim 45, wherein said window is joined to a lip recessed inside of said first plate.

47. The method of claim 37, wherein joining said window to said first plate occurs simultaneously during step a) while laminating together said plurality of individual layers of electrically insulating material.

48. The method of claim 47, wherein the geometrical relationship between said window and said first plate comprises an encased joint geometry.

49.The method of claim 48, said window is joined to said first plate without using a separate sealing material disposed in-between said window and said plate.

49. The method of;

claim 37, wherein said window substantially fills said first aperture.

51. The method of claim 37, wherein said window is a material selected from the group consisting of borosilicate glass, quartz glass, fused silica, optical quality glass, a transparent ceramic, sapphire, an optically transparent polymer, an UV transparent polymer, PMMA, an IR transparent material, silicon, a metal, a metal alloy, a material that switches from being optically transparent to being opaque at voltages around 5-6 volts, and lithium niobate.

52. The method of claim 37, further comprising flip-chip mounting a first microelectronic device to said first electrically conductive metallized trace after said window has been joined to said first plate.

53. The method of claim 37, further comprising:

f) providing an unreleased MEMS device;

g) mounting said MEMS device to said third surface of said second plate;

h) electrically interconnecting said MEMS device to said first electrically conductive metallized trace; and

i) releasing said MEMS device after mounting said MEMS device in step h).

50. The method of claim 50, wherein joining said window to said first plate comprises casting a castable window material directly into said first aperture;

wherein the castable window material is selected from the group consisting of a molten glass that solidifies after casting and a liquid polymer that hardens after casting.

54. The method of claim 54, wherein joining said window in step c) is performed after releasing said MEMS device in step i).

55. The method of claim 54, further comprising:

j) attaching a cover lid to said fourth surface of said second plate.

58. The method of claim 54, wherein said unreleased MEMS device comprises MEMS structures having a sacrificial protective coating disposed said MEMS structures.

56. The method of claim 56, wherein attaching said cover lid in step j) is performed after releasing said MEMS device in step i).

57. The method of claim 56, wherein attaching said cover lid in step j) is performed before mounting said MEMS device in step g).

59. The method of claim 59, wherein said sacrificial protective coating comprises a vacuum-deposited conformal coating.

61. The method of claim 59, wherein said vacuum-deposited conformal coating comprises parylene.

60. The method of claim 60, wherein releasing said MEMS device in step i) comprises using a dry plasma etching process to remove said vacuum-deposited conformal coating.

62. A method of fabricating a package with an integral window for housing a microelectronic device, comprising:

a) personalizing a first set of individual layers of an electrically insulating multilayer material by removing a cutout shape from each layer;

wherein removal of said cutout shape from each layer of said first set of individual layers defines a first aperture; and

wherein said first set of individual layers comprises a top layer;

b) personalizing a second set of individual layers of an electrically insulating multilayer material by removing a cutout shape from each layer;

wherein removal of said cutout shape from each layer of said second set of individual layers defines a second aperture; and

further wherein said second aperture is wider than said first aperture;

c) depositing a first electrical conductor on said top layer of said first set of individual layers;

d) stacking and registering said second set of individually personalized layers on top of said first set of individually personalized layers, including placing a window at a specified location in said first set;

thereby making an assembled stack of said first and second sets including said window;

wherein said window is disposed across said first aperture; and

e) processing said assembled stack of said first and second sets including said window by applying sufficient pressure and temperature to said assembled stack for sufficient time to form a consolidated monolithic multilayered body having an integral window;

wherein said window is bonded directly to said consolidated monolithic multilayered body without having a separate layer of sealing material disposed in-between said window and said body.

63. The method of claim 63, further comprising:

f) providing an unreleased MEMS device;

g) mounting said MEMS device to said top layer of said first set of individual layers;

h) electrically interconnecting said MEMS device to said first electrical conductor; and

i) releasing said MEMS device after mounting said MEMS device in step g).