Method of forming a robust copper interconnect by dilute metal doping

• US 20040188850A1
• Filed: 03/28/2003
• Published: 09/30/2004
• Est. Priority Date: 03/28/2003
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Su, Hung-Wen, Lee, Hsien-Ming
• Granted Patent: US 7,101,790 B2
• Time in Patent Office: Days
• US Class Current: 257/774
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76874 for electroless plating
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 2221/1089 Stacks of seed layers

Abstract

A copper filled semiconductor feature and method of forming the same having improved bulk properties the method including providing a semiconductor process wafer having a process surface including an opening for forming a semiconductor feature; depositing at least one metal dopant containing layer over the opening to form a thermally diffusive relationship to a subsequently deposited copper layer; depositing said copper layer to substantially fill the opening; and, thermally treating the semiconductor process wafer for a time period sufficient to distribute at least a portion of the metal dopants to collect along at least a portion of the periphery of said copper layer including a portion of said copper layer grain boundaries.

Claims

1. A method of forming a copper filled semiconductor feature having improved bulk properties comprising the steps of:

providing a semiconductor process wafer having a process surface comprising an opening for forming a semiconductor feature;

depositing at least one metal dopant containing layer over the opening to form a thermally diffusive relationship to a subsequently deposited copper layer;

depositing said copper layer to substantially fill the opening; and

,

thermally treating the semiconductor process wafer at a temperature for a time period sufficient to distribute at least a portion of the metal dopants to collect along at least a portion of the periphery of said copper layer including a portion of said copper layer grain boundaries.

2. The method of claim 1, wherein the opening is lined with at least one layer material selected from the group consisting of refractory metals and refractory metal nitrides.

3. The method of claim 1, wherein a copper seed layer is deposited over the at least one metal dopant containing layer prior to the step of depositing said copper layer.

4. The method of claim 1, wherein a copper seed layer is deposited over the opening prior to the step of depositing at least one metal dopant containing layer.

5. The method of claim 4, wherein a second copper seed layer is deposited over the at least one metal dopant containing layer prior to the step of depositing said copper layer.

6. The method of claim 1, further comprising the step of depositing the at least one metal dopant containing layer over the said copper layer following the step of depositing said copper layer and prior to the step of thermally treating.

7. The method of claim 1, wherein the at least one metal dopant containing layer comprises a metal dopant selected from the group consisting of Zr, Mg, Sn, Ag, Ti, Al, Pd, In, Au, Ca, Zn, and Cr.

8. The method of claim 7, wherein the at least one metal dopant containing layer including one or more copper seed layers deposited adjacent the metal dopant containing layer form a metal dopant concentration of about 0.001 weight percent to about 0.2 weight percent with respect to a total atomic weight of the at least one metal dopant containing layers and one or more copper seed layers.

9. The method of claim 1, wherein the step of thermally treating is carried out at a temperature of less than about 350 degrees Centigrade in an ambient substantially free of oxidants.

10. The method of claim 1, wherein the at least one metal dopant containing layer is deposited by an atomic layer chemical vapor deposition process.

11. The method of claim 1, wherein said copper layer is deposited by an electro-chemical deposition process.

12. The method of claim 1, wherein following the step of thermally treating a copper feature is formed having a resistivity value within about 10 percent of a copper feature consisting of substantially pure copper.

16. The method of claim 1, wherein the at least one adjacently deposited copper seed layer is deposited over the opening prior to the step of depositing the first metal dopant containing layer.

17. The method of claim 4, wherein the first metal dopant containing layer is formed sandwiched between a first copper seed layer and a second copper layer.

18. The method of claim 1, wherein the first and second metal dopant containing layers comprise a metal dopant selected from the group consisting of Zr, Mg, Sn, Ag, Ti, Al, Pd, In, Au, Ca, Zn, and Cr.

19. The method of claim 18, wherein the metal dopant concentration is about 0.001 weight percent to about 0.2 weight percent with respect to a total atomic weight of the metal dopant containing layers and copper seed layers.

13. A method of forming a copper filled semiconductor feature having improved bulk properties including electromigration resistance, reduced copper hillock formation, and a comparable resistivity to substantially pure copper comprising the steps of:

providing a semiconductor process wafer having a process surface comprising one or more dielectric insulating layers and an opening formed therein lined with a barrier layer for forming a copper filled semiconductor feature;

depositing a first metal dopant containing layer over the opening to contact at least one adjacently deposited copper seed layer;

depositing a copper filling layer to substantially fill the opening;

optionally depositing a second metal dopant containing layer over the copper filling layer; and

,

thermally treating the semiconductor process wafer for a time period sufficient to distribute at least a portion of the metal dopants to collect along at least a portion of the periphery of the opening including a portion of the copper filling layer grain boundaries.

14. The method of claim 13, wherein the barrier layer includes a member selected from the group consisting of refractory metals and refractory metal nitrides.

15. The method of claim 13, wherein the at least one adjacently deposited copper seed layer is deposited over the first metal dopant containing layer prior to the step of depositing the copper filling layer.