Method of improving the bondability between Au wires and Cu bonding pads

• US 20020086533A1
• Filed: 10/05/2001
• Published: 07/04/2002
• Est. Priority Date: 08/30/1999
• Status: Active Grant

• Current Assignee: Chen-Hua Yu, Chung-Shi Liu, Jane-Bai Lai, Mong-Song Liang, Syun-Ming Jang
• Original Assignee: Chen-Hua Yu, Chung-Shi Liu, Jane-Bai Lai, Mong-Song Liang, Syun-Ming Jang
• Inventors: Lai, Jane-Bai, Liu, Chung-Shi, Yu, Chen-Hua, Jang, Syun-Ming, Liang, Mong-Song
• Granted Patent: US 6,753,259 B2
• Time in Patent Office: Days
• US Class Current: 438/689
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05006 Dual damascene structure
• CPC Class Codes: H01L 2224/05083 Three-layer arrangements
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13099 Material
• 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 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48647 Copper (Cu) 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 2224/48724 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48747 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 24/03 Manufacturing methods
• 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 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire 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 2924/00014 : 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 2924/01007 : Nitrogen [N]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/181 : Encapsulation

Abstract

Cu, for its rather low resistivity, will be widely used in sub-quarter micron meter ULSI devices. However, it is well known that Cu is easy to be corroded as exposed in air. In packaging of chips the bonding pads making of Cu will thus oxides. In addition, the reaction between Au-ball and Cu pads is very poor. On the other hand, a native AlOx layer, about 3-4 nm in thickness, will form as Al exposes in air; the formed layer is inert and is capable of protecting Al from corrosion. Furthermore, the reaction between Au-ball and Al was very well. Therefore, with the methods of the present invention, Al or AlCu as a glue and protection layer is implemented on Cu bonding pads for successful Au wiring.

Claims

1. A method of improving the bondability between Au wires and copper (Cu) pads used in semiconductor manufacturing process, comprises

forming a Cu bonding pad on the top level of the metallization;

chemical mechanical polishing (CMP) said Cu bonding pad;

etching back said Cu bonding pad;

depositing a barrier layer over said Cu bonding pad; and

depositing AlCu or Al over said barrier layer to cover said Cu bonding pads;

2. A method according claim 1, wherein the material of said barrier layer is TiN.

3. A method according claim 2, wherein said TiN barrier layer is deposited by Chemical Vapor Deposition (CVD) process.

4. A method according claim 2, wherein the thickness of said TiN barrier layer is less than 20 nm.

5. A method according claim 1, wherein the steps of said depositing a Al or AlCu layer is a self-aligned depositing a Al or AlCu upon said barrier layer.

6. A method according claim 1, wherein further comprises

CMP Al or AlCu over said Cu bonding pad;

depositing a passivation layer over said top level metallization; and

roughen the surface of said passivation layer.

7. A method of improving the bondability between Au wires and Cu pads, used in semiconductor manufacturing process, comprises

etching a passivation layer to expose the underlying Cu bonding pads of the top level metallization;

depositing a tungsten (W) barrier layer upon said Cu bonding pads; and

depositing a Al layer on said W barrier layer.

8. A method according to claim 7, wherein said W barrier layer is selectively depositing upon said Cu bonding pads.

9. A method according to claim 7 or 8, wherein said W barrier layer is depositing by CVD process.

10. A method according to claim 7, wherein the thickness of said W barrier layer is thinner than 20 nm.

11. A method according to claim 7, wherein the steps of said depositing a Al or AlCu layer is selectively depositing a Al or AlCu layer upon said W barrier layer.

12. A method according claim 7, wherein further comprises the steps of roughening the surface of said passivation layer.

14. A method according claim 13, wherein further comprises steps of roughening the surface of said passivation layer.

13. A method of improving the bondability between Au wires and Cu pads used in semiconductor processing, comprises

forming a Cu bonding pad upon the top level metal;

depositing a passivation layer over Cu bonding pad of the top level metallization;

etching said passivation layer to expose said underlying Cu bonding pad through a contact window;

depositing blanket aluminum (Al) on top of said barrier layer;

performing Al CMP to remove Al on top of said passivation layer and leave Al only on the bonding pad of said contact window;