Method of room temperature covalent bonding

• US 7,109,092 B2
• Filed: 05/19/2003
• Issued: 09/19/2006
• Est. Priority Date: 05/19/2003
• Status: Expired due to Term

• Current Assignee: Invensas Bonding Technologies, Inc. (Adeia Inc.)
• Original Assignee: Ziptronix Incorporated (Adeia Inc.)
• Inventors: Tong, Qin-Yi
• Primary Examiner(s): Vu, David
• Application Number:
  US10/440,099
• Publication Number:
  US 20040235266A1
• Time in Patent Office: 1,219 Days
• Field of Search: 438/107, 438/406, 438/455, 438/459, 438/974, 257/777, 257/782, 156/60, 156/272.2
• US Class Current: 438/406
• CPC Class Codes: B32B 2250/04 4 layers
• CPC Class Codes: B32B 7/04 Interconnection of layers
• 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: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/019 characterised by the material or arrangement of seals between parts
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/08059 comprising protrusions or indentations
• CPC Class Codes: H01L 2224/29186 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/80895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• CPC Class Codes: H01L 2224/80896 between electrically insulating surfaces, e.g. oxide or nitride layers
• CPC Class Codes: H01L 2224/80986 Specific sequence of steps, e.g. repetition of manufacturing steps, time sequence
• CPC Class Codes: H01L 2224/81894 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 2224/81895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• 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 2224/9202 : Forming additional connectors after the connecting process
• CPC Class Codes: H01L 2224/9212 : Sequential connecting processes
• CPC Class Codes: H01L 2224/92125 : the second connecting process involving a layer connector
• CPC Class Codes: H01L 24/26 : Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/29 : of an individual layer connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/92 : Specific sequence of method steps
• 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 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01016 : Sulfur [S]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01058 : Cerium [Ce]
• CPC Class Codes: H01L 2924/01067 : Holmium [Ho]
• 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 2924/01082 : Lead [Pb]
• 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 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 2924/3512 : Cracking
• CPC Class Codes: Y10T 156/10 : Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/24355 : Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/31504 : Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A method of bonding includes using a bonding layer having a fluorinated oxide. Fluorine may be introduced into the bonding layer by exposure to a fluorine-containing solution, vapor or gas or by implantation. The bonding layer may also be formed using a method where fluorine is introduced into the layer during its formation. The surface of the bonding layer is terminated with a desired species, preferably an NH₂ species. This may be accomplished by exposing the bonding layer to an NH₄OH solution. High bonding strength is obtained at room temperature. The method may also include bonding two bonding layers together and creating a fluorine distribution having a peak in the vicinity of the interface between the bonding layers. One of the bonding layers may include two oxide layers formed on each other. The fluorine concentration may also have a second peak at the interface between the two oxide layers.

Claims

1. A bonding method, comprising:

forming first and second bonding layers on respective first and second elements, at least one of said bonding layers comprising a fluorinated oxide layer;

heating said fluorinated oxide layer;

after said heating, bringing into contact said first and second bonding layers in ambient at room temperature; and

forming a bond between said first and second layers at room temperature.

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

forming a bond of at least 600 mJ/m² at room temperature.

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

forming a bond of at least 1000 mJ/m² at room temperature.

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

forming a bond of at least 2500 mJ/m² at room temperature.

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

forming each of said first and second bonding layers to have a surface roughness in a range of about 0.1 to 1.5 nm.

6. A method as recited in claim 5, comprising:

activating said first and second bonding layers.

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

activating said first and second bonding layers.

8. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

exposing said oxide layer to a fluorine-containing solution.

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

exposing said oxide layer to a solution containing HF.

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

exposing said oxide layer to a solution containing about 0.025% HF.

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

exposing said fluorinated oxide layer to an RCA solution after said heating.

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

heating said fluorinated oxide layer at a temperature of in a range of about 100–

300°

C.

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

heating said fluorinated oxide layer at a temperature of about 250°

C.

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

exposing said fluorinated oxide layer to an RCA solution after said heating.

15. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

exposing said oxide layer to a fluorine-containing gas.

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

exposing said oxide layer to HF vapor.

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

exposing said oxide layer to a plasma containing one of SF₆ and CF₄.

18. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises depositing an oxide using a gas containing F.

19. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises depositing a PECVD oxide using a gas containing one of SiF₄ and CF₄.

20. A method as recited in claim 1, wherein forming at least one of said bonding layers comprising a fluorinated oxide layer comprises:

forming an oxide layer; and

implanting a F-containing species into said oxide layer.

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

implanting a F-containing species into said oxide layer to a dose in a range of about 1×

10¹⁵ to 1×

10¹⁶/cm².

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

etching said first and second bonding layers by exposure to an RIE process.

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

exposing said bonding layers to one of an NH₄OH solution and vapor.

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

covering first portions said first bonding layer; and

fluorinating second portions of said first bonding layer not covered in said covering step; and

bonding said second portions to said second bonding layer.

25. A method as recited in claim 1, wherein forming said fluorinated oxide in one of said first and second bonding layers comprises:

exposing a first oxide layer to fluorine; and

forming a second oxide layer on said first oxide layer after said exposing step.

26. A method as recited in claim 25, comprising:

forming said second oxide layer at a temperature in a range of about 100–

300°

C.

27. A method as recited in claim 25, comprising:

forming said second oxide layer at a temperature of about 250°

C.

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

forming at least one of said first and second bonding layers to have a fluorine concentration of at least 10¹⁷/cm³.

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

forming a fluorine concentration having a first peak in the vicinity of an interface between said first and second bonding layers and a second peak in at least one of said first and second layers separated from said first peak.

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

exposing said first oxide layer to a fluorine-containing gas.

31. A method as recited in claim 30, comprising:

exposing said first oxide layer to HF vapor.

32. A method as recited in claim 30, comprising:

exposing said first oxide layer to a plasma containing one of SF₆ and CF₄.

33. A method as recited in claim 1, wherein forming said first oxide layer comprises depositing an oxide using a gas containing F.

34. A method as recited in claim 1, wherein forming said first oxide layer comprises depositing a PECVD oxide using a gas containing one of SiF₄ and CF₄.

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

implanting a F-containing species into said first oxide layer.

36. A method as recited in claim 35, comprising:

implanting a F-containing species into said first oxide layer to a dose in a range of about 1×

10¹⁵ to 1×

10¹⁶/cm².

37. A method of forming a bonded structure, comprising:

forming a first bonding layer comprising;

forming a first oxide layer,

introducing fluorine into said first oxide layer, and

forming a second oxide layer on said first oxide layer after said introducing step;

bonding said first bonding layer to a second bonding layer; and

forming a fluorine concentration having a first peak in the vicinity of an interface between said first and second bonding layers and a second peak in the vicinity of an interface between said first and second oxide layers.

38. A method as recited in claim 37, comprising:

heating said first oxide layer at a temperature of in a range of about 100–

300°

C. before said bonding.

39. A method as recited in claim 37, comprising:

diffusing fluorine from said first oxide layer into said second oxide layer.

40. A method as recited in claim 37, comprising:

exposing said first oxide layer to one of a solution, vapor and gas each containing fluorine.

41. A method as recited in claim 37, wherein:

forming said first oxide layer comprises depositing an oxide using a gas containing fluorine.

42. A method as recited in claim 37, comprising:

exposing said first oxide layer to a plasma containing one of SF₆ and CF₄.

43. A method as recited in claim 37, wherein forming said first oxide layer comprises depositing an oxide using a gas containing F.

44. A method as recited in claim 38, comprising:

exposing said first oxide layer to a fluorine-containing gas.

47. A method as recited in claim 38, wherein forming said first oxide layer comprises depositing an oxide using a gas containing F.

48. A method as recited in claim 38, wherein forming said first oxide layer comprises depositing a PECVD oxide using a gas containing one of SiF₄ and CF_4.

49. A method as recited in claim 38, comprising:

implanting a F-containing species into said first oxide layer.

45. A bonding method, comprising:

forming a first oxide layer on a first element;

exposing said first oxide layer to fluorine;

forming a second oxide layer on said first oxide layer;

forming a third oxide layer on a second element;

bringing into contact a surface of said second oxide layer with a surface of said third oxide layer in ambient at about room temperature; and

forming a bond between said second and third oxide layers at about room temperature.

46. A method as recited in claim 45, wherein forming said third oxide layer comprises:

forming a fourth oxide layer on said second element;

exposing said fourth oxide layer to fluorine; and

forming a fifth oxide layer on said first oxide layer;

said method further comprising;

bringing into contact a surface of said second oxide layer with a surface of said fifth oxide layer in ambient at about room temperature; and

forming a bond between said second and fifth oxide layers at about room temperature.

50. A method as recited in claim 45, comprising:

exposing said first oxide layer to a solution containing about 0.025% HF.