Atomic layer deposition of tungsten barrier layers using tungsten carbonyls and boranes for copper metallization

• US 20030203616A1
• Filed: 04/24/2002
• Published: 10/30/2003
• Est. Priority Date: 04/24/2002
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Chung, Hua, Chen, Ling, Ganguli, Seshadri
• Application Number:
  US10/133,787
• Publication Number:
  US 20030203616A1
• Time in Patent Office: Days
• US Class Current: 438/627
• CPC Class Codes: C23C 16/16 from metal carbonyl compounds
• CPC Class Codes: C23C 16/45553 characterized by the use of precursors specially adapted for ALD
• CPC Class Codes: H01L 21/28562 Selective deposition
• 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

Abstract

A method of tungsten layer deposition for copper metallization in semiconductor devices includes reacting a tungsten carbonyl compound and a borane compound using a cyclical deposition technique. In one embodiment, the tungsten barrier layer is formed on a patterned dielectric layer by alternately adsorbing the tungsten carbonyl compound and the borane compound onto a semiconductor substrate. The tungsten layers have substantially uniform dimensions and excellent adhesion to copper such as copper seed layers or direct electroplating of copper onto the tungsten layer.

Claims

1. A method of copper metallization, comprising:

depositing a tungsten layer on a semiconductor substrate using a cyclical deposition process; and

depositing copper on the tungsten layer.

2. The method of claim 1, wherein the cyclical deposition process comprises alternately adsorbing monolayers of a tungsten carbonyl compound and a borane compound on the substrate.

3. The method of claim 2, wherein the tungsten carbonyl compound is selected from tungsten hexacarbonyl (W(CO)₆), tungsten pentacarbonyl compounds (RW(CO)₅), and tungsten tetracarbonyl compounds (R₂W(CO)₄), wherein R is one or more ligands replacing one or more carbonyl groups.

4. The method of claim 3, wherein each R is an alkylisonitrile group (R¹—

N═

C═

), wherein each R¹ is an alkyl group having from 4 to 8 carbon atoms.

5. The method of claim 3, wherein each R is an alkylisonitrile group (R¹—

N═

C═

), wherein each R¹ is n-butyl, 1-ethylpropyl, 1,2-dimethylpropyl, isopentyl, 2-methylbutyl, 1-methylbutyl, n-pentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, or n-octyl.

6. The method of claim 2, wherein the tungsten carbonyl compound is tungsten hexacarbonyl.

7. The method of claim 2, wherein the borane compound is selected from the group of borane, diborane(6), triborane(8), tetraborane(10), pentaborane(9), pentaborane(11), hexaborane(10), octaborane(10), octaborane(12), nonaborane(15), decaborane(14), decaborane(16), and combinations thereof.

8. The method of claim 7, wherein the borane compound is diborane.

9. The method of claim 1, wherein the copper is deposited by electroplating.

10. The method of claim 1, wherein the copper is deposited as a seed layer by CVD or PVD.

11. The method of claim 10, wherein additional copper is electroplated onto the seed layer.

12. The method of claim 2, wherein the cyclical deposition process comprises a plurality of cycles, wherein each cycle comprises establishing a flow of a purge gas to the process chamber and modulating the flow of the purge gas with an alternating period of exposure to one of either the tungsten carbonyl compound or the borane compound.

13. The method of claim 12, wherein the period of exposure to the tungsten carbonyl compound, the period of exposure to the borane compound, a period of flow of the purge gas between the period of exposure to the tungsten carbonyl compound and the period of exposure to the borane compound, and a period of flow of the purge gas between the period of exposure to the borane compound and the period of exposure to the tungsten carbonyl compound are adjusted to expose the tungsten carbonyl compound to excess borane compound.

14. The method of claim 13, wherein excess tungsten carbonyl and excess borane compound are substantially purged by the purge gas.

15. A method of copper metallization, comprising:

depositing a tungsten layer on a patterned dielectric layer by alternately adsorbing monolayers of tungsten hexacarbonyl and diborane; and

depositing copper on the tungsten layer.

16. The method of claim 15, wherein the copper is deposited by electroplating.

17. The method of claim 15, wherein the method comprises a plurality of cycles, wherein each cycle comprises establishing a flow of a purge gas to a process chamber and modulating the flow of the purge gas with an alternating period of exposure to the tungsten hexacarbonyl or the diborane.

18. The method of claim 17, wherein the period of exposure to the tungsten hexacarbonyl, the period of exposure to the diborane, a period of flow of the purge gas between the period of exposure to the tungsten hexacarbonyl and the period of exposure to the diborane, and a period of flow of the purge gas between the period of exposure to the diborane and the period of exposure to the tungsten hexacarbonyl are adjusted to expose absorbed tungsten hexacarbonyl to excess diborane.

19. A method of copper metallization, comprising:

depositing a tungsten layer on a semiconductor substrate by alternately adsorbing a monolayer of tungsten hexacarbonyl, purging excess tungsten hexacarbonyl, absorbing a monolayer of excess diborane, and purging excess diborane; and

electroplating copper on the tungsten barrier layer.

20. The method of claim 19, wherein the purge gas is adjusted to expose the tungsten hexacarbonyl to excess diborane

21. A semiconductor device having a copper metallization structure, comprising:

a tungsten layer deposited on a patterned dielectric layer by alternately adsorbing monolayers of tungsten hexacarbonyl and diborane; and

a copper layer deposited on the tungsten layer.

22. The semiconductor device of claim 21, wherein the copper is deposited by electroplating.

23. The semiconductor device of claim 22, wherein the tungsten layer is deposited by a plurality of cycles, wherein each cycle comprises establishing a flow of a purge gas to a process chamber and modulating the flow of the purge gas with an alternating period of exposure to the tungsten hexacarbonyl or the diborane.

24. The semiconductor device of claim 23, wherein the period of exposure to the tungsten hexacarbonyl, the period of exposure to the diborane, a period of flow of the purge gas between the period of exposure to the tungsten hexacarbonyl and the period of exposure to the diborane, and a period of flow of the purge gas between the period of exposure to the diborane and the period of exposure to the tungsten hexacarbonyl are adjusted to expose absorbed tungsten hexacarbonyl to excess diborane.

25. A method for depositing tungsten on a substrate, comprising a plurality of cycles, wherein each cycle comprises establishing a flow of a purge gas to the process chamber and modulating the flow of the purge gas with alternating periods of exposure to a tungsten carbonyl compound and a borane compound.

26. The method of claim 25, wherein the tungsten carbonyl compound is selected from tungsten hexacarbonyl (W(CO)₆), tungsten pentacarbonyl compounds (RW(CO)₅), and tungsten tetracarbonyl compounds (R₂W(CO)₄), wherein R is one or more ligands replacing one or more carbonyl groups.

27. The method of claim 26, wherein each R is an alkylisonitrile group (R¹—

N═

C═

), wherein each R¹ is an alkyl group having from 4 to 8 carbon atoms.

28. The method of claim 26, wherein each R is an alkylisonitrile group (R¹—

N═

C═

), wherein each R¹ is n-butyl, 1-ethylpropyl, 1,2-dimethylpropyl, isopentyl, 2-methylbutyl, 1-methylbutyl, n-pentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, or n-octyl.

29. The method of claim 26, wherein the tungsten carbonyl compound is tungsten hexacarbonyl.

30. The method of claim 25, wherein the borane compound is selected from the group of borane, diborane(6), triborane(8), tetraborane(10), pentaborane(9), pentaborane(11), hexaborane(10), octaborane(10), octaborane(12), nonaborane(15), decaborane(14), decaborane(16), and combinations thereof.

31. The method of claim 25, wherein the borane compound is diborane.

32. The method of claim 25, wherein the period of exposure to the tungsten carbonyl compound, the period of exposure to the borane compound, a period of flow of the purge gas between the period of exposure to the tungsten carbonyl compound and the period of exposure to the borane compound, and a period of flow of the purge gas between the period of exposure to the borane compound and the period of exposure to the tungsten carbonyl compound are adjusted to expose absorbed tungsten carbonyl compound to excess borane compound.