Method for fabricating copper-aluminum metallization

• US 5,913,147 A
• Filed: 01/21/1997
• Issued: 06/15/1999
• Est. Priority Date: 01/21/1997
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Ting, Chiu, Dubin, Valery
• Primary Examiner(s): Bowers, Charles
• Application Number:
  US08/786,004
• Time in Patent Office: 875 Days
• Field of Search: 437/189, 437/190, 437/192, 437/195, 427/304, 427/305, 427/306, 438/247, 438/390, 438/392, 438/631, 438/672, 438/635, 438/637, 438/643, 438/650, 438/678, 257/741, 257/774, 257/762
• US Class Current: 438/687
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 23/53233 Copper alloys
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method for fabricating copper-aluminum metallization utilizing the technique of electroless copper deposition is described. The method provides a self-encapsulated copper-aluminum metallization structure.

Claims

1. A method for fabricating copper alloy metallization in a recess defined in a dielectric layer of a substrate, the method comprising the steps of:

depositing a diffusion barrier layer on the surfaces of the recess;

depositing a copper alloy layer on the diffusion barrier layer; and

annealing the copper alloy layer to form a first thin oxide layer on an exposed surface of the copper alloy layer, and a second thin oxide layer at the interface between the copper alloy layer and the diffusion barrier layer.

2. A method as in claim 1, wherein the diffusion barrier layer comprises a metal composite selected from the group of tantalum, tantalum nitride, tungsten, tungsten nitride, titanium tungsten, titanium nitride, tantalum silicon nitride, titanium silicon nitride, or tungsten silicon nitride.

3. A method as in claim 1, wherein the copper alloy layer comprises aluminum.

4. A method as in claim 3, wherein the first thin layer of oxide comprises an aluminum oxide (Al₂ O₃), and the second thin layer of oxide comprises an aluminum oxide and copper-aluminum alloy (Al₂ O₃ +CuAl).

5. A method as in claim 3, wherein the depositing step comprises:

depositing a copper-aluminum alloy film on the diffusion barrier layer; and

depositing electroless copper on the copper-aluminum alloy film.

6. A method as in claim 5, wherein said step of depositing electroless copper is performed in a solution, having a pH of 11.5-13.5, containing:

a) 5-10 g/l CuSO₄.5H₂ O;

b) 5-10 g/l glyoxylic acid, or 5-10 ml/l formaldehyde;

c) 10-35 g/l KOH; and

d) 0.01-10 g.l RE 610, or 0.01-1 g/l polyethylene glycol.

7. A method as in claim 5, wherein the depositing step further comprises the step of:

filling the recess using the technique of copper electroplating.

8. A method as in claim 7, wherein said step of copper electroplating is performed using a 0.1-100 millisecond envelope of cathodic pulses, having a 50-90% duty cycle, followed by a 0.1-10 millisecond envelope of anodic pulses, having a 50-90% duty cycle.

9. A method as in claim 1, wherein the dielectric comprises silicon dioxide.

10. A method as in claim 1, wherein said copper alloy layer is formed by first depositing a CuAl bilayer, followed by an annealing step.

11. A method as in claim 10, wherein said annealing step of said CuAl bilayer is carried out at a temperature between 150°

C. to 500°

C.

12. A method for fabricating copper alloy metallization in a recess defined in a dielectric layer of a substrate, the method comprising the steps of:

depositing a U-shaped diffusion barrier layer on the surfaces of the recess;

depositing a copper alloy layer on the U-shaped diffusion barrier layer; and

annealing the copper alloy layer to form a first thin oxide layer on an exposed surface of the copper alloy layer, and a second thin oxide layer at the interface between the copper alloy layer and the U-shaped diffusion barrier layer.

13. A method as in claim 12, wherein the depositing step comprises:

depositing a copper-aluminum alloy film on the U-shaped diffusion barrier layer; and

depositing electroless copper on the copper-aluminum alloy film.