Wire bonding method for copper interconnects in semiconductor devices

• US 20050035466A1
• Filed: 09/10/2004
• Published: 02/17/2005
• Est. Priority Date: 12/20/1999
• Status: Abandoned Application

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Inventors: Chittipeddi, Sailesh, Merchant, Sailesh Mansinh
• Application Number:
  US10/939,292
• Publication Number:
  US 20050035466A1
• Time in Patent Office: Days
• US Class Current: 257/780
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05681 Tantalum [Ta] as principal constituent
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/45147 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/45565 Single coating layer
• CPC Class Codes: H01L 2224/456 with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
• CPC Class Codes: H01L 2224/45624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/48599 Principal constituent of the connecting portion of the wire connector being Gold (Au)
• CPC Class Codes: H01L 2224/48681 Tantalum (Ta) as principal constituent
• CPC Class Codes: H01L 2224/48699 Principal constituent of the connecting portion of the wire connector being Aluminium (Al)
• CPC Class Codes: H01L 2224/48781 Tantalum (Ta) as principal constituent
• CPC Class Codes: H01L 2224/78301 Capillary
• CPC Class Codes: H01L 2224/85201 Compression bonding
• CPC Class Codes: H01L 2224/85205 Ultrasonic bonding
• CPC Class Codes: H01L 2224/85375 having an external coating, e.g. protective bond-through coating
• CPC Class Codes: H01L 2224/85948 Thermal treatments, e.g. annealing, controlled cooling
• CPC Class Codes: H01L 24/03 : Manufacturing methods
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• 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 24/78 : Apparatus for connecting with wire connectors
• 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 2924/00014 : 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 2924/00015 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed as prior art
• 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 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01066 : Dysprosium [Dy]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/013 : Alloys
• 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 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor

Abstract

The present invention uses wire bonding technology to bond interconnect materials that oxidize easily by using a wire with stable oxidation qualities. A passivation layer is formed on the semiconductor substrate to encapsulate the bonding pad made from the interconnect material such that the wire bonds with the passivation layer itself, not with the interconnect material. The passivation layer is selected to be a material that is metallurgically stable when bonded to the interconnect material. Since the wire is stable compared with the interconnect material, i.e., it does not readily corrode, a reliable mechanical and electrical connection is provided between the semiconductor device (interconnect material) and the wire, with the passivation layer disposed therebetween.

Claims

1. A wire bonding method, comprising the steps of:

forming a semiconductor substrate with a copper (Cu) interconnect material;

fabricating a copper (Cu) bond pad;

depositing a tantalum (Ta) layer onto the substrate;

patterning and etching the tantalum (Ta) layer; and

bonding an aluminum (Al) wire with the tantalum (Ta) layer;

wherein a portion of the tantalum (Ta) layer bonds with the copper (Cu) bond pad, and another portion of the tantalum (Ta) layer forms a tantalum aluminide (TaAl₃) compound.

2. The method of claim 1, wherein the wire is a wire selected from the group consisting of an aluminum wire, an aluminum alloy wire, and an aluminum-coated gold wire.

3. The method of claim 1, wherein thickness of the tantalum (Ta) layer is controlled such that a portion of the tantalum (Ta) layer bonds with the copper (Cu) bond pad, and another portion of the tantalum (Ta) layer forms a tantalum aluminide (TaAl₃) compound.

4. The method of claim 1, wherein thickness of the tantalum (Ta) layer is between 300 to 1000 angstroms (A).

5. The method of claim 1, wherein the aluminum (Al) wire is bonded onto the tantalum (Ta) layer by wedge bonding.

6. The method of claim 1, further comprising the step of performing a heat treatment after the bonding step.

7. The method of claim 1, further comprising the step of packaging the substrate in a package consisting of a plastic package and a hermetic package.

8. The method of claim 1, wherein the tantalum (Ta) layer is patterned by a method consisting of negative tone pad masking, photoresist patterning, and photolithography.

9. The method of claim 1, wherein the substrate is a multi-layered interconnect structure.

10. A wire bonding method, comprising the steps of:

forming a passivation layer on a semiconductor substrate;

bonding a wire onto the passivation layer; and

encapsulating a bond pad made from an interconnect material, wherein the wire is more metallurgically stable than the interconnect material;

wherein a portion of the passivation layer forms a metallurgical bond with the interconnect material;

wherein a mechanical and electrical connection is provided between the interconnect material and the wire, with the passivation layer disposed therebetween.

11. The method of claim 10, wherein the wire is a wire selected from the group consisting of an aluminum wire, an aluminum alloy wire, and an aluminum-coated gold wire.

12. The method of claim 10, wherein the passivation layer is a tantalum (Ta) layer.

13. The method of claim 10, wherein the wire is bonded onto the passivation layer by wedge bonding.

14. The method of claim 10, further comprising the step of performing a heat treatment after the bonding step.

15. The method of claim 10, wherein the substrate is a multi-layered interconnect structure.

16. A semiconductor device, comprising:

a substrate;

a copper (Cu) bond pad formed on the substrate;

a tantalum (Ta) layer encapsulating the copper (Cu) bond pad;

wherein a portion of the tantalum (Ta) layer bonds with the copper (Cu) bond pad, and another portion of the tantalum (Ta) layer forms a tantalum aluminide (TaAl₃) compound.

17. The device of claim 16, wherein the substrate is a multi-layered interconnect structure.

18. The device of claim 16, wherein the tantalum (Ta) layer is bonded with the copper (Cu) bond pad using wedge bonding.

19. The device of claim 16, wherein the substrate is packaged in one of the group consisting of a plastic package and a hermetic package.

20. The device of claim 16, wherein thickness of the tantalum (Ta) layer is between 300 to 1000 angstroms (Å

).