Copper metallurgy in integrated circuits

• US 6,284,656 B1
• Filed: 08/04/1998
• Issued: 09/04/2001
• Est. Priority Date: 08/04/1998
• Status: Expired due to Term

• Current Assignee: Nanya Technology Corporation
• Original Assignee: Micron Technology, Inc.
• Inventors: Farrar, Paul A.
• Primary Examiner(s): CRANE, SARA W
• Application Number:
  US09/128,859
• Time in Patent Office: 1,127 Days
• Field of Search: 438/687, 438/618, 438/622, 438/623, 438/625, 438/628, 438/654, 257/762, 257/642, 257/643
• US Class Current: 438/687
• CPC Class Codes: H01L 21/02118 carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC polymers per se C08G, photoresist per se G03F
• CPC Class Codes: H01L 21/312 Organic layers, e.g. photoresist H01L21/3105, H01L21/32 take precedence; photoresists per se G03C
• CPC Class Codes: H01L 21/76801 characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
• CPC Class Codes: H01L 21/76828 thermal treatment
• CPC Class Codes: H01L 21/76858 by diffusing alloying elements
• 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 typical integrated circuit interconnects millions of microscopic transistors and resistors with aluminum wires buried in silicon-dioxide insulation. Yet, aluminum wires and silicon-dioxide insulation are less attractive than copper wires and polymer-based insulation, which promise both lower electrical resistance and capacitance and thus faster, more efficient circuits. Unfortunately, current techniques cannot realize the promise because copper reacts with the polymer-based insulation to form copper dioxide within the polymer, reducing effectiveness of the copper-polymer combination. Accordingly, the inventor devised a method which uses a non-acid-precursor to form a polymeric layer and then cures, or bakes, it in a non-oxidizing atmosphere, thereby making the layer resistant to copper-dioxidizing reactions. Afterward, the method applies a copper-adhesion material, such as zirconium, to the layer to promote adhesion with a subsequent copper layer. With reduced copper-dioxide, the resulting interconnective structure facilitates integrated circuits with better speed and efficiency.

Claims

1. A method of making copper-polymer-based interconnections in an integrated circuit, the method comprising:

applying a non-acidic polymeric precursor to a surface in the integrated-circuit assembly;

curing the applied non-acidic polymeric precursor in a non-oxidizing atmosphere to form a polymeric layer;

forming a first copper-adhesion layer on the polymeric layer;

forming at least one copper structure on the first copper-adhesion layer; and

forming a second copper-adhesion layer on the one copper structure.

2. The method of claim 1 wherein applying a non-acidic polymeric precursor to a surface in the integrated-circuit assembly;

applying a polyimide ester to a layer in the integrated-circuit assembly.

3. The method of claim 1 wherein the polymeric layer comprises a polyimide.

4. The method of claim 1:

wherein forming the first copper-adhesion layer comprises depositing at least one of zirconium, hafnium, or titanium on the polymeric layer; and

wherein forming the second copper-adhesion layer comprises depositing at least one zirconium, hafnium, or titanium on the one copper structure.

5. The method of claim 4 wherein forming the one copper structure on the polymeric layer comprises depositing copper within an approximate temperature range of 250 to 350°

C.

6. The method of claim 1 wherein the non-oxidizing atmosphere comprises at least one of hydrogen, nitrogen, or argon.

7. The method of claim 1 further comprising:

applying a non-acidic polymeric precursor to a surface over the one copper structure in the integrated-circuit assembly;

curing the applied non-acidic precursor in an argon atmosphere to form another polymeric layer; and

forming another copper structure on the other polymeric layer.

8. The method of claim 1 wherein forming the copper structure occurs after curing the non-acidic polymeric precursor.

9. A method of making copper-polymer-based interconnections in an integrated circuit, the method comprising:

applying a non-acidic polymeric precursor to a layer in the integrated-circuit assembly;

curing the polymeric precursor in a non-oxidizing atmosphere to form a polymeric layer;

applying a copper-adhesion material to the polymeric layer, the copper-adhesion material consisting essentially of hafnium or zirconium; and

forming at least one copper structure that contacts the copper-adhesion material on the polymeric layer.

10. The method of claim 9 wherein applying the non-acidic polymeric precursor comprises applying a polyimide ester to the layer in the integrated-circuit assembly.

11. The method of claim 9 wherein the polymeric layer comprises a polyimide.

12. The method of claim 9 wherein forming the one copper structure on the polymeric layer comprises:

depositing copper on the copper-adhesion layer at a deposition temperature in a range of 250 to 350°

C.

13. The method of claim 9 further comprising:

applying a non-acidic polymeric precursor to a surface over the one copper structure in the integrated-circuit assembly;

curing the applied non-acidic precursor in an argon atmosphere to form another polymeric layer; and

forming another copper structure on the other polymeric layer.

14. The method of claim 9 wherein forming the one copper structure occurs after curing the non-acid-based polymeric layer in a non-oxidizing environment.

15. A method of making copper-polymer-based interconnections in an integrated circuit, the method comprising:

applying a polyimide ester to a layer in the integrated-circuit assembly;

curing the applied polyimide ester in a non-oxidizing atmosphere to form a polyimide layer;

applying a copper-adhesion material to the polyimide layer, wherein the copper-adhesion material comprises at least one of zirconium and hafnium; and

depositing copper on the copper-adhesion material on the polyimide layer; and

applying a copper-adhesion material to the deposited copper, wherein the copper-adhesion material comprises at least one of zirconium and hafnium.

16. The method of claim 15 wherein applying the copper-adhesion material comprises depositing zirconium within an approximate temperature range of 250 to 350°

C.

17. The method of claim 15 wherein depositing copper occurs after curing the polyimide ester.

18. A method of making copper-polymer-based interconnections in an integrated circuit, the method comprising:

forming a first polymeric layer in the integrated-circuit assembly from a non-acidic polymeric precursor;

forming a first copper-adhesion layer on the first polymeric layer;

forming at least one copper structure on the first copper-adhesion layer;

forming a second copper-adhesion layer on the one copper structure;

forming a second polymeric layer in the integrated-circuit assembly from a non-acidic polymeric precursor;

forming a third copper-adhesion layer on the second polymeric layer;

depositing copper on the third copper-adhesion layer at a temperature less than about 450°

C.

19. The method of claim 18 wherein the first, second, and third copper-adhesion layers comprise at least one of zirconium, titanium, and hafnium.

20. The method of claim 18 wherein depositing copper occurs within an approximate temperature range of 250 to 350°

C.

21. The method of claim 18 wherein the non-oxidizing atmosphere comprises at least one of hydrogen, nitrogen, and argon.

22. A method of electrically connecting first and second components in an integrated-circuit assembly, the method comprising:

applying a polyimide ester to a layer over the first and second components;

curing the polyimide ester in a non-oxidizing atmosphere to form a polyimide layer;

forming a trench in the polyimide layer, the trench having respective first and second regions overlying the first and second components;

depositing a copper-adhesion material in the trench;

at least partially filling the trench with copper; and

depositing copper-adhesion material on the copper in the trench.

23. The method of claim 22 wherein the copper-adhesion material comprises at least one of zirconium, hafnium, or titanium.

24. The method of claim 22 wherein depositing the copper-adhesion material and depositing the copper occur within an approximate temperature range of 250 to 350°

C.

25. The method of claim 22 wherein depositing the copper occurs after curing the polyimide ester.