Semiconductor Device with Improved Contacts

• US 20070284740A1
• Filed: 05/08/2007
• Published: 12/13/2007
• Est. Priority Date: 08/11/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ano, Kazuaki
• Granted Patent: US 7,893,544 B2
• Time in Patent Office: Days
• US Class Current: 257/738
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05548 Bonding area integrally formed with a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05567 the external layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/13022 the bump connector being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/48599 Principal constituent of the connecting portion of the wire connector being Gold (Au)
• CPC Class Codes: H01L 2224/48644 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48799 Principal constituent of the connecting portion of the wire connector being Copper (Cu)
• CPC Class Codes: H01L 2224/48844 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/85444 Gold (Au) as principal constituent
• CPC Class Codes: H01L 23/498 Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers shape of the substrate H01L23/13
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• 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 2924/00011 : Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• 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 2924/01051 : Antimony [Sb]
• 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 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H05K 3/244 : Finish plating of conductors, especially of copper conductors, e.g. for pads or lands selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3457, e.g. by plating H05K3/3473
• CPC Class Codes: H05K 3/3463 : Solder compositions in relation to features of the printed circuit board or the mounting process

Abstract

A device with a solder joint made of a copper contact pad (210) of certain area (202) and an alloy layer (301) metallurgically attached to the copper pad across the pad area. The alloy layer contains copper/tin alloys, which include Cu₆Sn₅ intermetallic compound, and nickel/copper/tin alloys, which include (Ni,Cu)₆Sn₅ intermetallic compound. A solder element (308) including tin is metallurgically attached to the alloy layer across the pad area. No fraction of the original thin nickel layer is left after the reflow process. Copper/tin alloys help to improve the drop test performance, nickel/copper/tin alloys help to improve the life test performance.

Claims

1. A device comprising:

a semiconductor chip;

a substrate, on which the chip is assembled, having contacts for external connections;

each contact including;

a contact area with copper;

an alloy layer covering the contact area, the alloy layer including copper/tin alloys and copper/nickel/tin alloys, metallurgically attached to the copper area and substantially free of regions of unalloyed nickel;

the copper/nickel/tin alloys including(Cu, Ni, Au)₆Sn₅ intermetallic compound;

a reflow element comprising tin metallurgically attached to the alloy layer; and

the substrate further having a second contact area with copper and a region over the copper including nickel and an gold member;

the semiconductor chip mechanically assembled on the substrate via the gold member.

2. The device according to claim 1 wherein the copper/tin alloys include Cu₆Sn₅ intermetallic compound.

3. The device according to claim 1 wherein the reflow element further comprises one or more metals selected from a group consisting of lead, silver, bismuth, indium, zinc, copper, nickel, and antimony.

4. The device according to claim 1 wherein the substrate contacts are defined by windows in a solder mask.

5. The device according to claim 1 wherein the reflow elements are attached to the alloy layer area across the entire contact area.

6. The device according to claim 1, wherein copper/nickel/tin alloys are adjacent the copper contact area.

7. The device according to claim 6, wherein the copper/tin alloys are adjacent the copper/nickel/tin alloys near the copper contact area.

8. The device of claim 1, in which the gold member is a section of a gold wire.

9. The device of claim 8, in which the gold wire forms a stitch bond at the second contact area.

10. The device of claim 1, in which the gold member is affixed on the contact pad forming a gold to gold bond.

11. The device of claim 1, in which the gold member is affixed on the semiconductor chip bond pad.

12. The device of claim 10, in which the second contact area is free of solder material.