Method to create a controllable and reproducible dual copper damascene structure

• US 6,184,138 B1
• Filed: 09/07/1999
• Issued: 02/06/2001
• Est. Priority Date: 09/07/1999
• Status: Expired due to Term

• Current Assignee: Chartered Semiconductor Manufacturing Incorporated (Mamoura Diversified Global Holding PJSC)
• Original Assignee: Chartered Semiconductor Manufacturing Incorporated (Mamoura Diversified Global Holding PJSC)
• Inventors: Zhou, Mei Sheng, Gupta, Subhash, Ho, Paul Kwok Keung
• Primary Examiner(s): Booth, Richard
• Assistant Examiner(s): NGUYEN, HA T
• Application Number:
  US09/390,782
• Time in Patent Office: 518 Days
• Field of Search: 438/687, 438/688, 438/631, 438/633-640, 438/642-645, 438/647, 438/652-654, 438/678, 438/685
• US Class Current: 438/687
• CPC Class Codes: H01L 21/7684 Smoothing; Planarisation
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76874 for electroless plating
• CPC Class Codes: H01L 21/76876 for deposition from the gas phase, e.g. CVD
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76879 by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288

Abstract

A new method is provided to construct a copper dual damascene structure. A layer of IMD is deposited over the surface of a substrate. A cap layer is deposited over this layer of IMD, the dual damascene structure is then patterned through the cap layer and into the layer of IMD. A barrier layer is blanket deposited, a copper seed layer is deposited over the barrier layer. The dual damascene structure is then filled with a spin-on material. The barrier layer and the copper seed layer are removed above the cap layer; the cap layer can be partially removed or can be left in place. The spin on material remains in place in the via and trench opening during the operation of removing the copper seed layer and the barrier layer from above the cap surface thereby protecting the inside surfaces of these openings. The spin-on material is next removed from the dual damascene structure and copper is deposited. The cap layer that is still present above the surface of the IMD protects the dielectric from being contaminated with copper solution during the deposition of the copper. The excess copper is removed using a touch-up CMP. The cap layer over the surface of the IMD can, after the copper has been deposited, be removed if this is so desired. As a final step in the process, a liner or oxidation/diffusion protection layer is deposited over the dual damascene structure and its surrounding area.

Claims

1. A method of creating a copper dual damascene structure on the surface of a semiconductor substrate, comprising the steps of:

providing a semiconductor substrate the surface of said substrate to contain metal contact points;

forming an opening for a dual damascene structure on the surface of said substrate said opening to be formed in a layer of Inter Metal Dielectric (IMD) over which a cap layer has been deposited;

depositing a diffusion barrier layer inside said opening and over the surface of its surrounding area;

depositing a copper seed layer over said diffusion barrier layer;

depositing a spin-on layer over said copper seed layer;

removing said spin-on material from above said opening and from above the surface of said surrounding area thereby leaving in place said spin-on material inside the opening of said dual damascene structure;

removing said copper seed layer from above the surface of said surrounding area;

removing said barrier layer from above the surface of said surrounding area;

removing said spin-on material from said opening of said dual damascene structure;

selectively electroless depositing a layer of copper over said dual damascene opening;

removing excess copper from above the dual damascene opening by a touch-up CMP; and

depositing an oxidation/diffusion protection layer over the surface of said dual damascene structure and its surrounding area.

2. The method of claim 1 wherein forming an opening for a dual damascene structure, said structure to contain a via or bottom part and an conducting line or upper part said via part to match and mate with said metal contact points in the surface of said substrate, is:

depositing a first stop layer of SiN over the surface of said substrate said first stop layer to serve as etch stop for the via opening;

depositing a first layer of dielectric on top of said first stop layer said first layer of dielectric to form the inter-metal dielectric layer said first layer to contain SiO₂ said first layer of dielectric to serve as the via dielectric;

depositing a second stop layer of PE-CVD SiN on top of said first layer of dielectric said layer of SiN to serve as an second etch stop layer for said conducting line part of said dual damascene structure;

depositing a second layer of dielectric on top of said second stop layer of SiN said second layer of dielectric to serve as interconnect line dielectric;

depositing a cap layer over the surface of said second layer of dielectric;

forming a via pattern in said first layer of dielectric by patterning and etching through said cap layer furthermore etching through said second layer of dielectric furthermore etching through said second stop layer of SiN furthermore etching through said first layer of dielectric;

removing said first stop layer from the bottom of said via pattern thereby forming the via; and

forming a conducting line pattern by patterning and etching said cap layer furthermore etching through said second layer of dielectric thereby using said second stop layer of SiN as etch stop layer thereby forming a conducting line pattern.

3. The method of claim 1 wherein said diffusion barrier layer contains material selected from the group comprising Ta and W and Ti and their compounds.

4. The method of claim 1 wherein said spin-on material contains an element selected from the group of Spin On Glass (SOG), a resist, polyimide or any other suitable material whereby furthermore said spin-on material may be partially or completely cured thereby providing protection of the inside surfaces of said dual damascene structure during subsequent processing steps.

5. The method of claim 1 wherein said spin-on layer contains resist whereby:

said removal of said spin-on material from above said opening and from above the surface of said surrounding area is an O₂ or H₂ based dry etch;

said removal of said copper seed layer from above the surface of said surrounding area is an anisotropic Cl or F based dry etch;

said removal of said barrier layer from above the surface of said surrounding area is an anisotropic Cl or F based dry etch with overetch into said cap layer; and

said removal of said spin-on material from said opening of said dual damascene structure is a H₂ based dry etch.

6. The method of claim 1 wherein said spin-on layer contains resist whereby:

said removal of said spin-on material from above said opening and from above the surface of said surrounding area is an O₂ or H₂ based dry etch;

said removal of said copper seed layer from above the surface of said surrounding area is a HF or HF mixture;

said removal of said barrier layer from above the surface of said surrounding area is a selective DMSO/CCl₄ or HF/CH₃COOH wet etch with overetch into said cap layer; and

said removal of said spin-on material from said opening of said dual damascene structure is a H₂ based dry etch.

7. The method of claim 1 wherein said spin-on layer contains SOG whereby:

said removal of said spin-on material from above said opening and from above the surface of said surrounding area is a CMP process;

said removal of said copper seed layer from above the surface of said surrounding area is a CMP process;

said removal of said barrier layer from above the surface of said surrounding area is a CMP process with overetch into said cap layer; and

said removal of said spin-on material from said opening of said dual damascene structure is a HF or DHF or BOE based etch.

8. The method of claim 1 wherein said spin-on layer contains polyimide whereby:

said removal of said spin-on material from above said opening and from above the surface of said surrounding area is a CMP process;

said removal of said copper seed layer from above the surface of said surrounding area is a CMP process;

said removal of said barrier layer from above the surface of said surrounding area is a CMP process with overetch into said cap layer; and

said removal of said spin-on material from said opening of said dual damascene structure is a H₂ based dry etch.

9. The method of claim 1 wherein said depositing a layer of copper is a selective electroless plating process.

10. The method of claim 1 wherein said depositing a layer of copper is a selective CVD process.

11. The method of claim 1 wherein said removing excess metal from the surface of said second layer of dielectric is further extended to continue said removal below the surface of said barrier layer and to thereby partially remove said barrier layer in a planar manner from the surface of said second layer of dielectric.

12. The method of claim 1 wherein said removal of excess copper from the surface of said second layer of dielectric is by touch-up CMP.

13. The method of claim 1 wherein said depositing an oxidation/diffusion protection layer over the surface of said layer of IMD is depositing a layer of Si₃N₄ or any other suitable material that can provide protection of a copper surface against oxidation and/or chemical or mechanical damage.