Method of bonding semiconductor chips to a substrate

• US 5,249,732 A
• Filed: 02/09/1993
• Issued: 10/05/1993
• Est. Priority Date: 02/09/1993
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Thomas, Michael E.
• Primary Examiner(s): Heinrich, Samuel M.
• Application Number:
  US08/015,473
• Time in Patent Office: 238 Days
• Field of Search: 228/179, 228/180.2, 228/246, 228/253, 228/254, 228/4.5, 228/904, 427/123, 427/383.7, 437/183
• US Class Current: 228/179.1
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 24/11 Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/81 using a bump connector
• 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 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01032 Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• 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

Abstract

In a method of bonding a pad on a semiconductor chip to a corresponding pad on a carrier, a wire ball is attached to the pad on the chip by bonding one end of a low melting temperature aluminum alloy bond wire to the chip pad. The wire is then broken off at the bond. A bead is formed on the chip pad by heating the ball to a temperature slightly above the melting point of the bond wire material for a predetermined period of time. The melted bead is then placed into contact with a corresponding pad on the carrier.

Claims

1. A method for bonding a pad on a semiconductor chip to a corresponding pad on a carrier comprising the steps of:

1) providing a bond wire comprising a low melting temperature aluminum alloy material;

2) forming a wire ball attached to a pad on the chip by bonding one end of the bond wire to the pad on the chip;

3) breaking the wire off at the bond;

4) forming a bead on the chip pad by heating the ball to a temperature slightly above the melting point of the bond wire material for a predetermined period of time; and

5) placing the melted bead into contact with a corresponding pad on the carrier.

2. The method in accordance with claim 1 wherein said low melting temperature aluminum alloy material comprises an aluminum-germanium alloy.

3. The method in accordance with claim 1 wherein said low melting temperature aluminum alloy material comprises an aluminum-magnesium alloy.

4. The method in accordance with claim 1 wherein said low melting temperature aluminum alloy material comprises an aluminum-copper alloy.

5. The method in accordance with claim 1 wherein steps 4 and 5 are carried out under reducing or inert conditions.

6. A method for bonding a pad on a semiconductor chip to a corresponding pad on a carrier comprising the steps of:

1) forming a bead on the pad on the chip by dispensing a ball of molten bonding material comprising a low melting temperature aluminum alloy from a heated capillary tube onto the pad on the chip;

2) heating the bead to a temperature slightly above the melting point of the bonding material for a predetermined period of time; and

3) placing the melted bead into contact with a corresponding pad on the carrier.

7. The method in accordance with claim 6 wherein said low melting temperature aluminum alloy comprises an aluminum-germanium alloy.

8. The method in accordance with claim 6 wherein said low melting temperature aluminum alloy comprises an aluminum-magnesium alloy.

9. The method in accordance with claim 6 wherein said low melting temperature aluminum alloy comprises an aluminum-copper alloy.

10. The method in accordance with claim 6 wherein steps 2 and 3 are carried out under reducing or inert conditions.

11. A method for bonding a pad on a semiconductor chip to a corresponding pad on a carrier comprising the steps of:

1) forming at least one aluminum bond pad on a semiconductor chip;

2) forming a protective layer over the surface of the semiconductor chip and said at least one bond pad;

3) forming a window in the protective layer for each aluminum pad exposing said aluminum;

4) providing a bond wire comprising a low melting temperature aluminum alloy material;

5) forming a wire bond ball attached to a pad on the chip by bonding one end of the bond wire to the pad on the chip;

6) breaking the bond wire off at the bond;

7) forming a bead on the chip pad by heating the ball to a temperature slightly above the melting point of the bond wire material for a predetermined period of time; and

8) placing the melted bead into contact with a corresponding pad on the carrier.

12. The method in accordance with claim 11 wherein said low melting temperature aluminum alloy material comprises an aluminum-magnesium alloy.

13. The method in accordance with claim 11 wherein said low melting temperature aluminum alloy material comprises an aluminum-germanium alloy.

14. The method in accordance with claim 11 wherein said low melting temperature aluminum alloy material comprises an aluminum-copper alloy.

15. The method in accordance with claim 11 wherein steps 7 and 8 are performed under reducing or inert conditions.