Planarization with reduced dishing

• US 20040238492A1
• Filed: 04/23/2003
• Published: 12/02/2004
• Est. Priority Date: 04/23/2003
• Status: Active Grant

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Cui, Hao, Catabay, Wilbur G., Hsia, Wei-Jen
• Granted Patent: US 7,029,591 B2
• Time in Patent Office: Days
• US Class Current: 216/88
• CPC Class Codes: B23H 5/08 Electrolytic grinding
• CPC Class Codes: C23F 1/02 Local etching
• CPC Class Codes: C23F 4/00 Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
• CPC Class Codes: C25F 3/02 Etching
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/32115 Planarisation
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/7684 Smoothing; Planarisation

Abstract

A method of forming a planarized layer on a substrate, where the substrate is cleaned, and the layer is formed having a surface with high portions and low portions. A resistive mask is formed over the low portions of the layer, but not over the high portions of the layer. The surface of the layer is etched, where the high portions of the layer are exposed to the etch, but the low portions of the layer underlying the resistive mask are not exposed to the etch. The etch of the surface of the layer is continued until the high portions of the layer are at substantially the same level as the low portions of the layer, thereby providing an initial planarization of the surface of the layer. The resistive mask is removed from the surface of the layer, and all of the surface of the layer is planarized to provide a planarized layer.

Claims

1. A method of forming a planarized layer on a substrate, the method comprising the steps of:

cleaning the substrate,

forming the layer having a surface with high portions and low portions,

forming a resistive mask over the low portions of the layer and not over the high portions of the layer,

etching the surface of the layer, where the high portions of the layer are exposed to the etch and the low portions of the layer underlying the resistive mask are not exposed to the etch,

continuing the etch of the surface of the layer until the high portions of the layer are at substantially a same level as the low portions of the layer, thereby providing an initial planarization of the surface of the layer,

removing the resistive mask from the surface of the layer, and

planarizing all of the surface of the layer to provide a planarized layer.

2. The method of claim 1, wherein the layer is a metal layer.

3. The method of claim 1, wherein the layer is a copper layer.

4. The method of claim 1, wherein the resistive mask is photoresist.

5. The method of claim 1, wherein the step of etching comprises electropolishing the layer.

6. The method of claim 1, wherein the step of etching comprises wet etching the layer.

7. The method of claim 1, wherein the step of etching comprises dry etching the layer.

8. The method of claim 1, wherein the step of planarizing the surface comprises chemical mechanical polishing the surface.

9. The method of claim 1, wherein the step of planarizing the surface comprises electropolishing the surface.

10. The method of claim 1, wherein the step of forming the layer comprises:

depositing a barrier layer of at least one of tantalum nitride, tantalum, titanium nitride, and magnesium,

depositing a seed layer of copper, and

electroplating copper.

11. The method of claim 1, wherein the step of cleaning the substrate comprises a sputter clean using at least one of argon, hydrogen, and a fluorinated hydrocarbon.

12. A method of forming a planarized layer on a substrate, the method comprising the steps of:

cleaning the substrate,

forming the layer having a surface with high portions and low portions,

forming a resistive mask over the high portions of the layer and not over the low portions of the layer,

treating the surface of the layer to make it more resistive to planarization, where the low portions of the layer are exposed to the treatment and the high portions of the layer underlying the resistive mask are not exposed to the treatment,

removing the resistive mask from the surface of the layer, and

planarizing the surface of the layer, where the high portions of the layer are eroded at a first rate and the low portions of the layer are eroded at a second rate that is less than the first rate due to the treatment received by the low portions of the layer, to provide a planarized layer.

13. The method of claim 12, wherein the step of treating the surface of the layer comprises implanting at least one of carbon, nitrogen, tantalum, tantalum nitride, titanium, and titanium nitride.

14. The method of claim 12, wherein the step of treating the surface of the layer comprises plasma treatment with at least one of carbon, nitrogen, tantalum, tantalum nitride, titanium, and titanium nitride.

15. The method of claim 12, wherein the layer is a copper layer.

16. The method of claim 12, wherein the step of planarizing the surface comprises at least one of chemical mechanical polishing the surface and electropolishing the surface.

17. A method of forming a planarized layer on a substrate, the method comprising the steps of:

cleaning the substrate,

forming the layer having a surface with high portions and low portions,

forming a planar layer over the layer,

planarizing the planar layer down to the high portions of the surface of the layer, and

planarizing the planar layer and the surface of the layer using a process that planarizes both the planar layer and the layer at a substantially equal rate, until at least the planar layer is substantially completely removed, to provide a planarized layer.

18. The method of claim 17, wherein the step of forming the planar layer comprises depositing at least one of spin on glass and flow fill dielectric.

19. The method of claim 17, wherein the step of planarizing the planar layer comprises chemical mechanical polishing the planar layer.

20. The method of claim 17, wherein the step of planarizing the planar layer and the surface of the layer comprises at least one of chemical mechanical polishing and electropolishing.