Method of fabricating an electronic circuit device

• US 5,865,365 A
• Filed: 12/06/1996
• Issued: 02/02/1999
• Est. Priority Date: 02/19/1991
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Iwata, Yasuhiro, Hara, Masahide, Tamura, Mitsunori, Takehara, Hiroko, Nishikawa, Toru, Yamada, Osamu, Satoh, Ryohei, Hayashida, Tetsuya, Ijuin, Masahito, Shirai, Mitugu
• Primary Examiner(s): Heinrich, Samuel M.
• Application Number:
  US08/761,430
• Time in Patent Office: 788 Days
• Field of Search: 228/180.22, 228/205-207, 228/219-221, 228/223, 228/224, 148/23, 148/25, 29/841, 29/855-856
• US Class Current: 228/223
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2224/11003 for holding or transferring the bump preform
• CPC Class Codes: H01L 2224/11334 using preformed bumps
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/29099 Material
• CPC Class Codes: H01L 2224/29109 Indium [In] as principal constituent
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/81075 being inert
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/83805 involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 23/49816 : Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 24/11 : Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/12 : Structure, shape, material or disposition of the bump connectors prior to the connecting process
• 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 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 2924/0001 : Technical content checked by a classifier
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01083 : Bismuth [Bi]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H05K 2203/0278 : Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive
• CPC Class Codes: H05K 2203/041 : Solder preforms in the shape of solder balls
• CPC Class Codes: H05K 2203/0435 : Metal coated solder, e.g. for passivation of solder balls
• CPC Class Codes: H05K 2203/086 : Using an inert gas
• CPC Class Codes: H05K 2203/087 : Using a reactive gas
• CPC Class Codes: H05K 2203/095 : Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes
• CPC Class Codes: H05K 2203/1157 : Using means for chemical reduction
• CPC Class Codes: H05K 3/3426 : characterised by the leads
• CPC Class Codes: H05K 3/3489 : Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces

Abstract

A method of soldering used in fabricating an electronic circuit device employs an organic material supplied to at least one of the connecting members to be bonded. The connecting members are positioned in an oxidizing atmosphere, and heated in a nonoxidizing atmosphere to remove oxide and/or contamination layers present on the surface of presoldered portions or metallized bonding portions. By this method, fluxless soldering is performed, positional shifts are reduced, and high reliability of the soldering connections with reduction in residues after reflow are obtained.

Claims

1. A method of soldering for use in fabricating an electronic circuit device, comprising the steps of:

presoldering a first member to be bonded to a second member;

supplying an organic material to the surface of solder material on said first member and to the surface of said second member to be bonded thereto;

aligning said solder material and said second member in an oxidizing atmosphere; and

heating said solder material in a nonoxidizing atmosphere to melt it and to remove an oxide layer and contamination layer from the surface of said solder material.

2. A method of soldering as claimed in claim 1, wherein after said aligning step, said organic material remains on said first and second members.

3. A method of soldering as claimed in claim 2, wherein after said heating step, said organic material evaporates.

4. A method of soldering as claimed in claim 1, wherein the melting point of said organic material is higher than that of said solder material.

5. A method of soldering as claimed in claim 1, wherein said organic material is in a solid state at room temperature.

6. A method of soldering as claimed in claim 1, wherein said organic material is in a liquid state at room temperature.

7. A method of soldering as claimed in claim 1, wherein said organic material has a hydroxyl group in its molecules.

8. A method of soldering as claimed in claim 7, wherein after said heating step, there remains on said solder material surface only an organic acid-metal salt formed by reaction between said organic material and said solder material.

9. A method of soldering as claimed in claim 7, wherein after said heating step, there remains on said solder material surface only an organic acid-metal salt formed by reaction between said organic material, said solder material, and a surface oxide film formed on said second member.

10. A method of soldering for use in fabricating an electronic circuit device, comprising the steps of:

supplying a solder to a first member to be bonded to a second member, in the form of solder plating, vapor deposition, or a ball-like solder;

supplying an organic material to at least one of said first and second members;

aligning said first and second members in an oxidizing atmosphere; and

heating said first and second members in a nonoxidizing atmosphere to remove at least an oxide layer and a contamination layer from the surface of at least one of said solder and said second member, and for bonding said first and second members to each other.

11. A method of soldering as claimed in claim 10, wherein said solder is at least one selected from a group consisting of alloys of Pb and Sn, alloys of Sn and Ag, alloys of Au and Pb, alloys of Au and Ge, and alloys of Au and Si.

12. A method of soldering as claimed in claim 10, wherein said nonoxidizing atmosphere is prepared by supplying a nonoxidizing gas to a vacuum atmosphere.

13. A method of soldering as claimed in claim 12, wherein said nonoxidizing gas is an inert gas.

14. A method of soldering as claimed in claim 13, wherein said inert gas is selected from the group consisting of N₂, Ar, He, and a mixture of N₂, Ar, and He.

15. A method of soldering as claimed in claim 13, wherein said inert gas is selected from the group consisting of N₂, Ar, He, and a mixture of N₂, Ar, and He, and wherein said atmosphere during the heating is controlled by controlling said vacuum pressure and concentration of said inert gas.

16. A method of soldering as claimed in claim 12, wherein said nonoxidizing gas is a reducing gas.

17. A method of soldering as claimed in claim 12, wherein said nonoxidizing gas is an active gas.

18. A method of soldering as claimed in claim 17, wherein said active gas is selected from the group consisting of (1) a mixture of N₂ and said inert gas and (2) N₂.

19. A method of soldering as claimed in claim 12, wherein said nonoxidizing gas is a fluorocarbon vapor.

20. A method of soldering as claimed in claim 10, wherein after said aligning step, said organic material remains on said first and second members.

21. A method of soldering as claimed in claim 20, wherein after said heating step, said organic material evaporates.

22. A method of soldering as claimed in claim 10, wherein the melting point of said organic material is higher than that of said solder.

23. A method of soldering as claimed in claim 10, wherein said organic material is in a solid state at room temperature.

24. A method of soldering as claimed in claim 10, wherein said organic material is in a liquid state at room temperature.

25. A method of soldering as claimed in claim 10, wherein said organic material has a hydroxyl group in its molecules.

26. A method of soldering as claimed in claim 12, wherein said atmosphere during the heating step is controlled by controlling said vacuum pressure and concentration of said gas, and wherein after said heating step, said organic material evaporates.

27. A method of soldering as claimed in claim 10, wherein said step of supplying a solder supplies the solder in the form of solder plating or vapor depositioning.

28. A method of soldering as claimed in claim 10, wherein after said heating step, there remains on said solder surface only an organic acid-metal salt formed by reaction between said organic material and said solder.

29. A fluxless bonding method for bonding together first and second members of an integrated circuit, comprising the steps of:

supplying a solder to at least one of the first and second members in the form of solder plating, vapor depositioning, or a ball-like solder;

supplying an organic material to at least one of said first and second members;

aligning said first and second members in an oxidizing atmosphere; and

heating said first and second members in a nonoxidizing atmosphere to remove an oxide layer and a contamination layer from the surface of one of said solder and said first and second members, and for bonding said first and second members to each other.

30. A method of soldering as claimed in claim 29, wherein after said aligning step, said organic material remains on said first and second members.

31. A method of soldering as claimed in claim 30, wherein after said heating step, said organic material evaporates.

32. A method of soldering as claimed in claim 29, wherein the melting point of said organic material is higher than that of said solder.

33. A method of soldering as claimed in claim 29, wherein said organic material is in a solid state at room temperature.

34. A method of soldering as claimed in claim 29, wherein said organic material is in a liquid state at room temperature.

35. A method of soldering as claimed in claim 29, wherein said organic material has a hydroxyl group in its molecules.

36. A method of soldering as claimed in claim 29, wherein said step of supplying a solder supplies said solder by solder plating or vapor depositioning.

37. A method of soldering as claimed in claim 29, wherein after said heating step, there remains on said solder surface only an organic acid-metal salt formed by reaction between said organic material and said solder.