Bump structure, bump forming method and package connecting body

• US 6,229,220 B1
• Filed: 09/11/1996
• Issued: 05/08/2001
• Est. Priority Date: 09/27/1995
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shoji, Reijiro, Saitoh, Kazuto
• Primary Examiner(s): Jackson, Jr., Jerome
• Assistant Examiner(s): Wilson, Allan R.
• Application Number:
  US08/712,542
• Time in Patent Office: 1,700 Days
• Field of Search: 257/738, 257/778, 257/779, 257/780, 257/781
• US Class Current: 257/780
• CPC Class Codes: H01L 2224/03912 the bump being used as a mask for patterning the bonding area
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05155 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05164 Palladium [Pd] as principal constituent
• CPC Class Codes: H01L 2224/05166 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05572 the external layer extending out of an opening
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/1146 Plating
• CPC Class Codes: H01L 2224/1147 using a lift-off mask
• CPC Class Codes: H01L 2224/11849 Reflowing
• CPC Class Codes: H01L 2224/1308 being stacked
• CPC Class Codes: H01L 2224/13082 Two-layer arrangements
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/13109 Indium [In] as principal constituent
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/13116 Lead [Pb] as principal constituent
• CPC Class Codes: H01L 2224/13139 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/13144 : Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/13147 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13155 : Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/1607 : of bonding interfaces, e.g. interlocking features
• CPC Class Codes: H01L 2224/81193 : wherein the bump connectors are disposed on both the semiconductor or solid-state body and another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81801 : Soldering or alloying
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/11 : Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 : of an individual bump connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 2924/00013 : Fully indexed content
• 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 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• 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 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• 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 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys

Abstract

To provide a bump structure for soldering by forming a solder layer on the chip surface while keeping the space between a package substrate and a semiconductor chip large. Form a bump structured in double layers at a chip 1 and connect it to an electrode 11 of a package substrate 10 by soldering. The lower layer 3a in the double-layer structure does not fuse in soldering, and a definite distance between the substrate and the chip can be maintained. The upper layer 3b actually fuses in soldering and operates to electrically connect the bump to the electrode on the package substrate. The melting point of the lower layer is preferably at least 20° C. higher than that of the upper layer.

Claims

1. A bump structure for electrically connecting a semiconductor chip to a package substrate, comprising:

a first part, having a height, H₁, a volume, V₁, and a first diameter and formed on said semiconductor chip and made of metal substantially incapable of melting at a predetermined soldering temperature; and

a second part, having a height H₂, a volume V₂, a second diameter and formed on said first part and capable of melting at the predetermined soldering temperature for electrical connection to a package substrate, wherein the height H₁ of said first part satisfies the relation 90 μ

m>

H₁>

30 μ

m and wherein the first diameter is not equal to the second diameter.

2. The bump structure as set forth in claim 1, wherein said first part maintains the distance between said semiconductor chip and a package substrate equal to or more than a predetermined value.

6. The bump structure as set forth in claim 1, wherein said second part is made of a two-component system eutectic solder alloy.

7. The bump structure as set forth in claim 1, wherein said second part is made of a three-component system eutectic solder alloy containing indium.

9. The bump structure as set forth in claim 1, wherein the height H₁ of said first part satisfies the relation 90 μ

m≧

H₁>

50 μ

m.

10. The bump structure as set forth in claim 9 wherein the height H₂ of said second part satisfies the relation that H₁/H₂ ranges from about 0.55 to about 2.

11. The bump structure as set forth in claim 1, wherein the relation 5>

V₂/V₁>

1.5 is satisfied where V₁ and V₂ are the volume of said first part and volume of said second part respectively.

3. A bump structure for electrically connecting a semiconductor chip to a package substrate, comprising:

a first part, having a height, H₁, a volume, V₁, and a first diameter and formed on said semiconductor chip and made of metal substantially incapable of melting at a predetermined soldering temperature; and

a second part, having a height H₂, a volume V₂, and a second diameter and formed on said first part and capable of melting at the predetermined soldering temperature for electrical connection to a package substrate, wherein the first diameter is not equal to the second diameter and wherein the relation 5>

V₂/V₁>

1 is satisfied where V₁ and V₂ are the volume of said first part and volume of said second part respectively.

12. The bump structure as set forth in claim 3, wherein said second part is made of a two-component system eutectic solder alloy.

13. The bump structure as set forth in claim 3, wherein said second part is made of a three-component system eutectic solder alloy containing indium.

4. A bump structure for electrically connecting a semiconductor chip to a package substrate, comprising:

a first part, having a height, H₁, a volume, V₁, and a first diameter and formed on said semiconductor chip and made of metal substantially incapable of melting at a predetermined soldering temperature; and

a second part, having a height H₂, a volume V₂, and a second diameter and formed on said first part and capable of melting at the predetermined soldering temperature for electrical connection to a package substrate and wherein the first diameter is not equal to the second diameter wherein said first part is made of metal having a melting point 20°

C. higher than that of the composition of said second part.

14. The bump structure as set forth in claim 4, wherein said second part is made of a two-component system eutectic solder alloy.

15. The bump structure as set forth in claim 4, wherein said second part is made of a three-component system eutectic solder alloy containing indium.

5. A bump structure for electrically connecting a semiconductor chip to a package substrate, comprising:

a first part, having a height, H₁, a volume, V₁, and a first diameter and formed on said semiconductor chip and made of metal substantially incapable of melting at a predetermined soldering temperature; and

a second part, having a height H₂, a volume V₂, and a second diameter and formed on said first part and capable of melting at the predetermined soldering temperature for electrical connection to a package substrate wherein the first diameter is not equal to the second diameter wherein said first part is made of a solder including 3% gold or tin by weight and 97% lead by weight.

16. The bump structure as set forth in claim 5, wherein said second part is made of a two-component system eutectic solder alloy.

17. The bump structure as set forth in claim 5, wherein said second part is made of a three-component system eutectic solder alloy containing indium.

8. A package connecting body for a semiconductor chip and a package substrate, comprising:

a first metal part formed on said semiconductor chip, said first metal part having a melting point;

a second metal part formed on said package substrate; and

a third metal part, having a melting point lower than at least said first metal part melting point, having been formed on at least one of said first metal part and said second metal part and interposed at least partly between said first metal part and said second metal part for providing electrical connection therebetween, wherein

the distance between said semiconductor chip and said package substrate, maintained by said first metal part, said second metal part and said third metal part is equal to or greater than 60 μ

m.