Wet etching methods for copper removal and planarization in semiconductor processing

• US 9,074,286 B2
• Filed: 12/21/2012
• Issued: 07/07/2015
• Est. Priority Date: 10/20/2003
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Porter, David W., Mayer, Steven T., Webb, Eric
• Primary Examiner(s): Vinh, Lan
• Application Number:
  US13/725,308
• Publication Number:
  US 20130207030A1
• Time in Patent Office: 928 Days
• Field of Search: 252/79.1, 252/79.2, 252/79.3, 252/79.4, 252/79.5, 438/745, 438/750
• US Class Current: 1/1
• CPC Class Codes: C23F 1/02 Local etching
• CPC Class Codes: C23F 1/18 for etching copper or alloys thereof
• CPC Class Codes: C23F 1/34 for etching copper or alloys thereof
• CPC Class Codes: C23F 3/04 Heavy metals
• CPC Class Codes: C25D 17/001 Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• CPC Class Codes: C25D 5/48 After-treatment of electroplated surfaces
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: H01L 21/02074 the processing being a planarization of conductive layers
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/32115 Planarisation
• CPC Class Codes: H01L 21/32134 by liquid etching only
• CPC Class Codes: H01L 21/67051 using mainly spraying means, e.g. nozzles
• CPC Class Codes: H01L 21/6708 using mainly spraying means, e.g. nozzles
• CPC Class Codes: H01L 21/76849 the layer being positioned on top of the main fill metal
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76858 by diffusing alloying elements
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• 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

Exposed copper regions on a semiconductor substrate can be etched by a wet etching solution comprising (i) one or more complexing agents selected from the group consisting of bidentate, tridentate, and quadridentate complexing agents; and (ii) an oxidizer, at a pH of between about 5 and 12. In many embodiments, the etching is substantially isotropic and occurs without visible formation of insoluble species on the surface of copper. The etching is useful in a number of processes in semiconductor fabrication, including for partial or complete removal of copper overburden, for planarization of copper surfaces, and for forming recesses in copper-filled damascene features. Examples of suitable etching solutions include solutions comprising a diamine (e.g., ethylenediamine) and/or a triamine (e.g., diethylenetriamine) as bidentate and tridentate complexing agents respectively and hydrogen peroxide as an oxidizer. In some embodiments, the etching solutions further include pH adjustors, such as sulfuric acid, aminoacids, and carboxylic acids.

Claims

1. A concentrated solution for preparing a wet etching solution for copper etching, the concentrated solution consisting essentially of:

(a) water;

(b) one or more polyamines selected from the group consisting of a bidentate diamine, a tridentate triamine and a quadridentate tetramine, wherein the concentration of aminogroups derived from these polyamines is at least about 1.5 M; and

(c) one or more pH adjustors selected from the group consisting of sulfuric acid, an alkylsulphonic acid, a carboxylic acid, and an aminoacid, wherein the concentrated solution has a pH of between about 8.5 and 11.5 at 21°

C.

2. The concentrated solution of claim 1, wherein the concentrated solution has a pH of between about 9 and 11.5 at 21°

C.

3. The concentrated solution of claim 1, wherein the concentration of aminogroups derived from the polyamines is at least about 3 M.

4. The concentrated solution of claim 1, wherein the concentration of aminogroups derived from the polyamines is at least about 4 M.

5. The concentrated solution of claim 1, wherein the concentrated solution comprises a single polyamine, wherein the single polyamine is ethylenediamine.

6. The concentrated solution of claim 1, wherein the concentrated solution comprises a single polyamine, wherein the single polyamine is ethylenediamine, and wherein the pH adjustor comprises glycine.

7. The concentrated solution of claim 1, wherein the concentrated solution comprises a single polyamine, wherein the single polyamine is ethylenediamine, and wherein the pH adjustor comprises sulfuric acid.

8. The concentrated solution of claim 1, wherein the concentrated solution comprises a single polyamine, wherein the single polyamine is ethylenediamine, and wherein the pH adjustor comprises acetic acid.

9. The concentrated solution of claim 1, wherein the concentrated solution comprises a single polyamine, wherein the single polyamine is ethylenediamine, and wherein the pH adjustor comprises methanesulfonic acid.

10. The concentrated solution of claim 1, wherein the concentrated solution consists essentially of water, ethylenediamine, and sulfuric acid.

11. The concentrated solution of claim 1, wherein the concentrated solution consists essentially of water, ethylenediamine, and glycine.

12. The concentrated solution of claim 1, wherein the concentrated solution consists essentially of water, ethylenediamine, glycine, acetic acid and sulfuric acid.

13. The concentrated solution of claim 1, wherein the concentrated solution consists essentially of water, ethylenediamine, and acetic acid.