Method for low temperature bonding and bonded structure

• US 7,553,744 B2
• Filed: 10/31/2007
• Issued: 06/30/2009
• Est. Priority Date: 02/16/2000
• Status: Expired due to Fees

• Current Assignee: Invensas Bonding Technologies, Inc. (Adeia Inc.)
• Original Assignee: Ziptronix Incorporated (Adeia Inc.)
• Inventors: Enquist, Paul M., Tong, Qin-Yi, Fountain, Gaius Gillman Jr.
• Primary Examiner(s): Richards; N Drew
• Assistant Examiner(s): Garcia; Joannie A
• Application Number:
  US11/980,415
• Publication Number:
  US 20080063878A1
• Time in Patent Office: 608 Days
• Field of Search: 438/406, 438/455, 438/459, 438/974, 148/DIG.12
• US Class Current: 438/455
• CPC Class Codes: H01L 21/0206 during, before or after processing of insulating layers
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/31105 Etching inorganic layers
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/322 to modify their internal properties, e.g. to produce internal imperfections
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 2224/8301 Cleaning the layer connector, e.g. oxide removal step, desmearing
• CPC Class Codes: H01L 2224/8303 Reshaping the layer connector in the bonding apparatus, e.g. flattening the layer connector
• CPC Class Codes: H01L 2224/83031 by chemical means, e.g. etching, anodisation
• CPC Class Codes: H01L 2224/8309 Vacuum
• CPC Class Codes: H01L 2224/83099 Ambient temperature
• CPC Class Codes: H01L 2224/8319 Arrangement of the layer connectors prior to mounting
• CPC Class Codes: H01L 2224/8385 using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 2224/83894 Direct bonding, i.e. joining surfaces by means of intermolecular attracting interactions at their interfaces, e.g. covalent bonds, van der Waals forces
• CPC Class Codes: H01L 2224/83896 between electrically insulating surfaces, e.g. oxide or nitride layers
• CPC Class Codes: H01L 2224/83948 Thermal treatments, e.g. annealing, controlled cooling
• CPC Class Codes: H01L 24/26 Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/75 Apparatus for connecting with bump connectors or layer connectors
• CPC Class Codes: H01L 24/83 using a layer connector
• CPC Class Codes: H01L 25/0657 Stacked arrangements of devices
• 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 27/085 : including field-effect components only
• CPC Class Codes: H01L 29/06 : characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
• CPC Class Codes: H01L 29/16 : including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01007 : Nitrogen [N]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01031 : Gallium [Ga]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/0106 : Neodymium [Nd]
• CPC Class Codes: H01L 2924/01061 : Promethium [Pm]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01084 : Polonium [Po]
• CPC Class Codes: H01L 2924/01093 : Neptunium [Np]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/05442 : SiO2
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/3512 : Cracking
• CPC Class Codes: Y10S 148/012 : Bonding, e.g. electrostatic for strain gauges
• CPC Class Codes: Y10S 438/974 : Substrate surface preparation
• CPC Class Codes: Y10T 156/10 : Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 156/1043 : Subsequent to assembly

Abstract

A method for bonding at low or room temperature includes steps of surface cleaning and activation by cleaning or etching. One etching process The method may also include removing by-products of interface polymerization to prevent a reverse polymerization reaction to allow room temperature chemical bonding of materials such as silicon, silicon nitride and SiO₂. The surfaces to be bonded are polished to a high degree of smoothness and planarity. VSE may use reactive ion etching or wet etching to slightly etch the surfaces being bonded. The surface roughness and planarity are not degraded and may be enhanced by the VSE process. The etched surfaces may be rinsed in solutions such as ammonium hydroxide or ammonium fluoride to promote the formation of desired bonding species on the surfaces.

Claims

1. A bonding method, comprising:

forming first and second bonding surfaces on first and second materials, respectively, at least one of said surfaces comprising an insulating material;

enhancing activation of at least one of said first and second bonding surfaces;

terminating at least one of said first and second bonding surfaces with species allowing formation of chemical bonds;

annealing said first and second materials at a temperature of no more than about 200°

C.; and

forming a bond with a strength of at least 500 mJ/m² between said first and second materials.

2. A method as recited in claim 1, comprising:

forming a bond between said first and second materials with a strength of at least 1000 mJ/m².

3. A method as recited in claim 1, comprising:

forming a bond between said first and second materials with a strength of at least 2000 mJ/m².

4. A method as recited in claim 1, comprising:

after forming said bond, annealing said first and second materials at a temperature in a range of about 75-100°

C.

5. A method as recited in claim 1, wherein:

said enhancing activation includes exposing to a fluorine containing species.

6. A method as recited in claim 1, wherein the other of said first and second surfaces comprises silicon.

48. A method as recited in claim 1, comprising:

terminating said first and second bonding surfaces with species allowing formation of chemical bonds.

49. A method as recited in claim 1, comprising:

enhancing activation of said first and second bonding surfaces.

7. A processing method, comprising:

exposing a first surface of a first element to a plasma to at least enhance activation of said first surface;

terminating said first surface with a species capable of forming a chemical bond after exposure to said plasma; and

bonding said first surface to a second surface of a second element after said terminating step;

heating said first and second elements to a temperature no more than about 200°

C.; and

obtaining a bond strength of at least 500 mJ/m².

8. A method as recited in claim 7, comprising:

heating said first and second elements to a temperature no more than about 100°

C.

9. A method as recited in claim 7, comprising:

heating said first and second elements to a temperature no more than about 75-100°

C.

10. A method as recited in claim 7, wherein said exposing comprises etching said first surface such that a surface roughness of said first surface after said etching is substantially the same as a surface roughness of said first surface before said etching.

11. A method as recited in claim 7, wherein said species is nitrogen-based.

12. A method as recited in claim 7, wherein said species is fluorine-based.

13. A method as recited in claim 7, wherein said second element comprises silicon.

14. A bonding method, comprising:

forming a silicon oxide material on a first element;

enhancing activation of a surface of said silicon oxide material using a plasma RIE process;

exposing said silicon oxide material to an ammonia-based solution after said enhancing;

bringing together said silicon oxide material and a second element, after said enhancing and exposing steps; and

forming a chemical bond between said silicon oxide material and said second element.

15. A method as recited in claim 14, comprising:

enhancing activation of a surface of said second element; and

bringing together said surface of said silicon oxide material and said surface of said second element after each of said enhancing steps and said exposing step.

16. A method as recited in claim 14, wherein said step of enhancing activation of said surface of said silicon oxide material using said plasma RIE process comprises etching said silicon oxide material.

17. A method as recited in claim 16, wherein said etching comprises etching said silicon oxide material such that a surface roughness of said silicon oxide material after said etching is substantially the same as a surface roughness of said silicon oxide material before said etching.

18. A method as recited in claim 14, wherein:

a surface roughness of said silicon oxide material after said enhancing is substantially the same as a surface roughness of said silicon oxide material before said step of enhancing.

19. A method as recited in claim 14, comprising:

forming said bond between said silicon oxide material and said second element to a strength of at least 500 mJ/m².

20. A method as recited in claim 14, comprising:

forming said bond at a temperature less than about 200°

C.

21. A method as recited in claim 20, comprising:

forming said bond at a temperature less than about 100°

C.

22. A method as recited in claim 20, comprising:

heating after said step of bringing together at a temperature in a range of about 75-100°

C.

23. A method as recited in claim 20, comprising:

forming said bond between said silicon oxide material and said second element to a strength of at least 1000 mJ/m².

24. A bonded structure, comprising:

first and second materials having first and second bonding surfaces, respectively, at least one of said surfaces comprising an insulating material and at least one of said surfaces having enhanced surface activation;

at least one of said first and second bonding surfaces terminated with species allowing formation of chemical bonds; and

a chemical bond with a strength of at least 500 mJ/m² formed between said first and second materials after annealing said first and second materials at a temperature of no more than about 200°

C.

25. A structure as recited in claim 24, wherein said species is nitrogen-based.

26. A method as recited in claim 24, wherein said species is fluorine-based.

27. A structure as recited in claim 24, wherein:

said first surface comprises an insulating material; and

said second surface comprises silicon.

28. A structure as recited in claim 27, wherein said insulating material comprises silicon oxide.

29. A structure as recited in claim 24, wherein said insulating material comprises silicon oxide.

30. A structure as recited in claim 24, wherein at least one of said surfaces comprises a polished surface.

50. A device as recited in claim 24, comprising:

said first and second bonding surfaces terminated with species allowing formation of chemical bonds.

51. A device as recited in claim 24, comprising:

said first and second bonding surfaces having enhanced activation.

31. A bonding method, comprising:

forming an insulating material on a first element;

exposing a surface of said insulating material to a plasma RIE process;

terminating said insulating material with a species after said exposing;

bringing together said insulating material, after said exposing and terminating steps, with a second element; and

forming a bond of a strength of at least 500 mJ/m² between said insulating material and said second element.

32. A method as recited in claim 31, comprising:

forming a bond between said insulating material and said second element with a strength of at least 1000 mJ/m².

33. A method as recited in claim 31, comprising:

forming a bond between said insulating material and said second element with a strength of at least 2000 mJ/m².

34. A method as recited in claim 31, comprising:

after forming said bond, annealing said insulating material and said second element at a temperature in a range of about 75-100°

C.

35. A method as recited in claim 31, wherein:

said enhancing activation includes exposing to a fluorine containing species.

36. A method as recited in claim 31, wherein said second element comprises silicon.

37. A method as recited in claim 31, wherein said species is nitrogen-based.

38. A method as recited in claim 31, wherein said species is fluorine-based.

39. A method as recited in claim 31, wherein said insulating material comprises silicon oxide.

40. A method as recited in claim 31, wherein exposing said surface of said insulating material to said plasma RIE process comprises etching said insulating material.

41. A processing method, comprising:

exposing a first surface of a first element to a plasma to at least enhance activation of said first surface;

terminating said first surface with a species capable of forming a chemical bond with a bond strength of at least 500 mJ/m² without heating to a temperature more than about 200°

C. after exposure to said plasma; and

bonding said first surface to a second surface of a second element after said terminating step; and

obtaining a chemical bond with bond strength of at least 500 mJ/m².

42. A method as recited in claim 41, comprising:

heating said first and second elements to a temperature no more than about 100°

C.

43. A method as recited in claim 41, comprising:

heating said first and second elements to a temperature no more than about 75-100°

C.

44. A method as recited in claim 41, wherein said exposing comprises etching said first surface such that a surface roughness of said first surface after said etching is substantially the same as a surface roughness of said first surface before said etching.

45. A method as recited in claim 41, wherein said species is nitrogen-based.

46. A method as recited in claim 41, wherein said species is fluorine-based.

47. A method as recited in claim 41, wherein said second element comprises silicon.