Submicron metallization using electrochemical deposition

• US 6,806,186 B2
• Filed: 03/23/2001
• Issued: 10/19/2004
• Est. Priority Date: 02/04/1998
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: Chen, Linlin, Ritzdorf, Thomas L., Graham, Lyndon W., Fulton, Dakin, Batz, Robert W. Jr.
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): Brewster, William M
• Application Number:
  US09/815,931
• Publication Number:
  US 20020004301A1
• Time in Patent Office: 1,306 Days
• Field of Search: 438/644, 438/672, 438/675
• US Class Current: 438/644
• CPC Class Codes: C25D 5/02 Electroplating of selected surface areas
• CPC Class Codes: C25D 5/10 Electroplating with more than one layer of the same or of different metals for bearings C25D7/10
• CPC Class Codes: C25D 5/18 Electroplating using modulated, pulsed or reversing current
• CPC Class Codes: C25D 5/50 by heat-treatment
• CPC Class Codes: C25D 5/605 Surface topography of the layers, e.g. rough, dendritic or nodular layers
• CPC Class Codes: C25D 5/611 Smooth layers
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: H01L 21/2885 using an external electrical current, i.e. electro-deposition
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material

Abstract

Methods for depositing a metal into a micro-recessed structure in the surface of a microelectronic workpiece are disclosed. The methods are suitable for use in connection with additive free as well as additive containing electroplating solutions. In accordance with one embodiment, the method includes making contact between the surface of the microelectronic workpiece and an electroplating solution in an electroplating cell that includes a cathode formed by the surface of the microelectronic workpiece and an anode disposed in electrical contact with the electroplating solution. Next, an initial film of the metal is deposited into the micro-recessed structure using at least a first electroplating waveform having a first current density. The first current density of the first electroplating waveform is provided to enhance the deposition of the metal at a bottom of the micro-recessed structure. After this initial plating, deposition of the metal is continued using at least a second electroplating waveform having a second current density. The second current density of the second electroplating waveform is provided to assist in reducing the time required to substantially complete filling of the micro-recessed structure.

Claims

1. A method for depositing a metal into a micro-recessed structure in the surface of a microelectronic workpiece, the method comprising:

making contact between the surface of the microelectronic workpiece and an electroplating solution in an electroplating cell, the electroplating cell including a cathode formed by the surface of the microelectronic workpiece and an anode disposed in electrical contact with the electroplating solution;

depositing an initial film of the metal into the micro-recessed structure using a first current density for a first predetermined period of time, the first current density assisting to enhance deposition of the metal at a bottom of the micro-recessed structure;

continuing deposition of the metal beginning at least some time after the first predetermined period of time using a second current density, the second current density assisting to reduce the time required to substantially complete filling of the micro-recessed structure, the second current density being greater than the first current density.

2. A method as claimed in claim 1 wherein the electroplating solution is substantially free of organic additives and has a first predetermined concentration of the metal that is to be electroplated that is higher than a second predetermined concentration suitable for use in a plating bath including organic additives.

3. A method as claimed in claim 1 wherein the metal that is to be plated comprises copper.

4. A method as claimed in claim 1 wherein the ratio between the first current density and the second current density is about 1:

10.

5. A method as claimed in claim 1 wherein the ratio between the first current density and the second current density is about 1:

8.

15. A method of claim 1, wherein the micro-recessed structure has a sub-micron width.

16. The process of claim 15, wherein the micro-recessed structure has a width of approximately 0.5 microns.

17. The process of claim 15, wherein the micro-recessed structure has an aspect ratio of 2:

1.

6. A method for depositing a metal into a micro-recessed structure in the surface of a microelectronic workpiece, the method comprising:

making contact between the surface of the microelectronic workpiece and an electroplating solution in an electroplating cell, the electroplating cell including a cathode formed by the surface of the microelectronic workpiece and an anode disposed in electrical contact with the electroplating solution;

depositing an initial film of the metal into the micro-recessed structure using a first current density for a first predetermined period of time to enhance growth of the metal at the bottom of the micro-recessed structure;

at least substantially completing the fill of the micro-recessed structure using a second current density for a second predetermined period of time, the second current density being substantially higher than the first current density.

7. A method as claimed in claim 6 wherein the electroplating solution is free of organic additives and has a first predetermined concentration of metal ions that are to be deposited in the micro-recessed structure that is higher than a second predetermined concentration of metal ions that would be used for deposition in the presence of organic additives.

8. A method as claimed in claim 7 wherein the first predetermined period of time is on the order of 30 seconds.

9. A method as claimed in claim 6 wherein the metal that is to be plated comprises copper.

10. A method as claimed in claim 7 wherein the electroplating solution comprises a concentration of the metal that is between about 15 g/L and 36 g/L.

11. A method as claimed in claim 9 wherein the electroplating solution comprises a concentration of copper that is between about 15 g/L and 36 g/L.

12. A method as claimed in claim 6 wherein the ratio between the first current density and the second current density is about 1:

10.

13. A method as claimed in claim 6 wherein the ratio between the first current density and the second current density is about 1:

8.

14. A method as claimed in claim 6 wherein the first electroplating waveform is a pulsed waveform.

18. The process of claim 6, wherein the initial film of metal deposited using the first current density has a first morphology, and the second metal deposited using the second current density has a second morphology that is different than the first morphology.

19. The process of claim 6, further comprising depositing a thin seed layer on the microelectronic workpiece prior to deposition of the initial film deposition of the initial film enhancing the thin seed layer.

20. The method of claim 6, further comprising, after processing the micro-recessed structure with the second electroplating waveform, processing the micro-recessed structure using a third electroplating waveform including a reverse current pulse to remove overfill.

21. A method for depositing a metal onto the surface of a microelectronic workpiece, the method comprising:

placing the surface of the microelectronic workpiece in contact with an electroplating solution including a metal ion to be deposited and that is substantially free of organic additives;

supplying plating power between the surface of the microelectronic workpiece and an anode disposed in contact with the electroplating solution to deposit metal onto the surface of the microelectronic workpiece, wherein metal is first deposited in an initial amount using a first current density for a first predetermined period of time to enhance growth of the metal at the bottom of the micro-recessed structure, and then additional metal is deposited onto the initial amount of metal using a second current density for a second predetermined period of time, the second current density being substantially higher than the first current density, wherein the concentration of the metal ion in the electroplating solution is provided at a first predetermined concentration level that is higher than a second predetermined concentration level that would be utilized for metal deposition in the presence of organic additives.

22. A method of depositing a metal layer on a semiconductor wafer comprising:

depositing a seed layer on a surface of the water;

immersing the water in an electrolytic solution containing metal ions;

biasing the wafer negatively with respect to the electrolytic solution so as to create a current flow at a first nominal current density between an anode and the wafer to thereby deposit a plated layer electrolytically on the seed layer of the wafer for enhancing growth of the metal at the bottom of the micro-recessed structure; and

increasing the current flow to a second nominal current density greater than the first nominal current density after a predetermined time period has elapsed.