Method of sputtering copper to fill trenches and vias

• US 6,605,197 B1
• Filed: 05/13/1997
• Issued: 08/12/2003
• Est. Priority Date: 05/13/1997
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Chiang, Tony, Ding, Peijun, Chin, Barry L.
• Primary Examiner(s): VERSTEEG, STEVEN H
• Application Number:
  US08/855,059
• Time in Patent Office: 2,282 Days
• Field of Search: 204/192.12, 204/192.15, 204/192.17, 204/192.3
• US Class Current: 204/192.15
• CPC Class Codes: H01L 21/2855 by physical means, e.g. sputtering, evaporation H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material

Abstract

The present disclosure pertains to a method of filling features (typically trenches or vias) on a semiconductor workpiece surface with copper using sputtering techniques previously believed incapable of achieving a copper fill. In particular, when the feature is to be filled with a single, continuous application of sputtered copper, the surface of the substrate to which the sputtered copper is applied should range between about 200° C. and about 600° C.; preferably the surface temperature of the substrate ranges between about 300° C. and about 500° C. When the feature is to be filled using a thin wetting layer of copper, followed by a fill layer of copper, the wetting layer may be applied by sputtering techniques or by other methods such as evaporation or CVD, while the fill layer of copper is applied using sputtering techniques. The thin wetting layer of copper is applied at a substrate surface temperature ranging between about 20° C. to about 250° C., and subsequently the temperature of the substrate is increased, with the application of the sputtered copper fill layer beginning at above at least about 200° C. and continuing while the substrate temperature is increased to a temperature as high as about 600° C. Preferably the substrate temperature during application of the sputtered fill layer ranges between about 300° C. and about 500° C.

Claims

1. A method of providing a complete copper fill of a trench or via or other feature upon a surface of a semiconductor workpiece, said method comprising the steps of:

sputter depositing at least one wetting layer of copper to wet and bond to said surface while said surface is at a temperature ranging from about 20°

C. to about 250°

C., followed by sputter depositing at least one fill layer of copper over said surface while said surface is at a temperature ranging between about 200°

C. and about 600°

C.

2. The method of claim 1, wherein said at least one fill layer of copper is sputter deposited while said surface is at a temperature ranging between about 250°

C. and about 500°

C.

3. The method of claim 2, wherein said at least one fill layer of copper is sputter deposited while said surface is at a temperature ranging between about 300°

C. and about 500°

C.

4. The method of claim 1, or claim 2, or claim 3, wherein said at least one wetting layer of copper is applied using a sputtering technique selected from the group consisting of non-collimated magnetron sputtering where a mean free path for collision within a process gas is greater than a distance between a sputtering target and a substrate;

collimated deposition sputtering;

ion deposition sputtering; and

sputtering directly from a target to a substrate where the percentage of sputtered material which is ionized at time of contact with said substrate is less than 10%;

or, is applied using at least two of these sputtering techniques in sequence.

5. The method of claim 4, wherein said at least one fill layer of copper is applied using a sputtering technique selected from the group consisting of non-collimated magnetron sputtering where a mean free path for collision within a process gas is greater than a distance between a sputtering target and a substrate;

collimated deposition sputtering;

ion deposition sputtering; and

sputtering directly from a target to a substrate where the percentage of sputtered material which is ionized at time of contact with said substrate is less than 10%;

or, is applied using at least two of these sputtering techniques in sequence.

6. The method of claim 1, wherein, subsequent, to application of said at least one wetting layer of copper, the temperature of said surface is adjusted downward to a temperature below 200°

C. and then adjusted upward to said temperature ranging between about 200°

C. and about 600°

C. during application of said at least one fill layer of copper.

7. The method of claim 1, wherein said surface has at least one barrier layer present thereon at the time of sputter deposition of said wetting layer of copper.

8. The method of claim 7, wherein said barrier layer is selected from the group consisting of tantalum, tantalum nitride, tantalum-silicon nitride, titanium nitride, titanium-silicon nitride, tungsten nitride, and tungsten-silicon nitride.

9. The method of claim 7, wherein a wetting layer other than copper overlays said barrier layer at the time of sputter deposition of said wetting layer of copper.

10. The method of claim 9, wherein said at least one wetting layer other than copper is comprised of aluminum, or titanium, or a combination thereof.

11. The method of claim 1, wherein said copper wetting layer and said copper fill layer are applied in a single process chamber.

12. The method of claim 1, wherein said trench, or said via, or said other feature being filled has a feature size of 0.75 μ

m or less and an aspect ratio of 1;

1 or greater.

13. The method of claim 12, wherein said trench, or said via, or said other feature being filled has a feature size of 0.5 μ

m or less.

14. The method of claim 12, wherein said trench, or said via, or said other feature being filled has an aspect ratio of 3:

1 or greater.