Selective in situ cobalt residue removal

• US 10,049,891 B1
• Filed: 05/31/2017
• Issued: 08/14/2018
• Est. Priority Date: 05/31/2017
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Wang, Xikun, Ingle, Nitin
• Primary Examiner(s): Hoang, Quoc
• Application Number:
  US15/609,372
• Time in Patent Office: 440 Days
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/32138 pre- or post-treatments, e.g. anti-corrosion processes
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material

Abstract

Exemplary methods for removing cobalt material may include flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber. The methods may include forming a plasma of the chlorine-containing precursor to produce plasma effluents. The methods may also include contacting an exposed region of cobalt with the plasma effluents. The methods may include flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber. The methods may further include contacting the cobalt chloride with the nitrogen-containing precursor. The methods may also include recessing the cobalt, which leaves a residue behind. The methods may include forming a remote plasma of a hydrogen-containing precursor. The methods may also include removing the cobalt residue using plasma effluents of the hydrogen-containing precursor.

Claims

1. An etching method comprising:

flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber;

forming a plasma of the chlorine-containing precursor to produce plasma effluents;

contacting an exposed region of cobalt with the plasma effluents;

flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber;

contacting the cobalt chloride with the nitrogen-containing precursor;

recessing the cobalt, wherein cobalt residue remains subsequent the recessing;

forming a remote plasma of a hydrogen-containing precursor; and

removing the cobalt residue using plasma effluents of the hydrogen-containing precursor.

2. The etching method of claim 1, wherein a plasma power of the plasma formed from the chlorine-containing precursor is less than about 200 W.

3. The etching method of claim 1, wherein a temperature of the substrate is maintained between about 175°

C. and about 300°

C. during the etching method.

4. The etching method of claim 1, wherein a pressure within the semiconductor processing chamber is maintained below about 5 Torr.

5. The etching method of claim 1, wherein the etching method removes at least about 5 Å

of cobalt.

6. The etching method of claim 1, further comprising depositing additional cobalt in the trench.

7. The etching method of claim 1, wherein the etching method is repeated for at least two cycles.

8. The etching method of claim 7, wherein a total removal of cobalt after the at least 2 cycles is at least about 20 Å

.

9. The etching method of claim 1, further comprising forming a bias plasma during the cobalt residue removal within the processing region of the semiconductor processing chamber.

10. The etching method of claim 1, wherein the method removes less than 5% of material proximate a bottom region of the trench.

11. The etching method of claim 1, wherein the etching method has a selectivity of cobalt to titanium nitride greater than or about 50:

1.

12. The etching method of claim 1, wherein the etching method has a selectivity of cobalt to silicon nitride and silicon oxide greater than or about 100:

1;

1.

13. The etching method of claim 1, wherein the processing region is maintained plasma-free while contacting the cobalt chloride with the nitrogen-containing precursor.

14. A method of producing a gap-free cobalt fill, the method comprising:

depositing a first amount of cobalt into a trench defined on a substrate, wherein the deposition forms an overhang of cobalt at an opening of the trench;

flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber, wherein the processing region houses the substrate;

forming a plasma of the chlorine-containing precursor to produce plasma effluents;

contacting the overhang of cobalt with the plasma effluents to produce cobalt chloride at the overhang of cobalt;

flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber;

contacting the cobalt chloride with the nitrogen-containing precursor;

recessing the overhang of cobalt;

contacting the substrate with effluents of a hydrogen-containing plasma; and

removing recessing residue from the cobalt.

15. The method of producing a gap-free cobalt fill of claim 14, further comprising depositing a second amount of cobalt into the trench, wherein the deposition forms an additional overhang of cobalt at the opening of the trench.

16. The method of producing a gap-free cobalt fill of claim 14, wherein the method is repeated at least twice.

17. The method of producing a gap-free cobalt fill of claim 14, wherein a plasma power of the plasma formed from the chlorine-containing precursor is less than or about 200 W, wherein the flow rate of the chlorine-containing precursor is below or about 30 sccm, and wherein the chlorine-containing precursor is flowed into the processing region for a time period of less than or about 20 seconds.

18. The method of producing a gap-free cobalt fill of claim 14, further comprising forming a bias plasma in the processing region to direct the effluents of the hydrogen-containing plasma.

19. The method of producing a gap-free cobalt fill of claim 14, wherein the cobalt is deposited on a metallic nitride liner formed within the trench.