Atomic layer deposition of metal films
Provided herein are low resistance metallization stack structures for logic and memory applications and related methods of fabrication. In some embodiments, thin metal oxynitride or metal nitride nucleation layers are deposited followed by deposition of a pure metal conductor. The nucleation layer is amorphous, which templates large pure metal film grain growth and reduced resistivity. Further, certain embodiments of the methods described below convert most or all of the metal oxynitride nucleation layer to a pure metal layer, further lowering the resistivity.
1. A method comprising:
depositing a first layer from a first metal oxychloride precursor and ammonia using a first atomic layer deposition (ALD) process; and
depositing an elemental metal layer on the first layer from a second metal oxychloride precursor and hydrogen using a second ALD process, wherein the first layer is a metal oxynitride or metal nitride layer, and further comprising converting the first layer to a second elemental metal layer underlying the elemental metal layer.
2. The method of claim 1 , wherein the first layer is converted to the second elemental metal layer during or prior to the second ALD process.
3. The method of claim 2 , wherein the second elemental metal layer contains less than 1 (atomic) % impurities.
4. The method of claim 1 , wherein the first layer is an amorphous layer.
5. The method of claim 4 , wherein the elemental metal layer on the first layer is crystalline.
6. The method of claim 1 , wherein the first and second ALD processes are performed in a first chamber and without exposure to air.
7. The method of claim 1 , wherein the first layer is a template for metal grain growth in the elemental metal layer.
8. The method of claim 1 , wherein the elemental metal layer contains less than 1 (atomic) % impurities.
9. The method of claim 1 , wherein the elemental metal layer is elemental tungsten.
10. The method of claim 1 , wherein the elemental metal layer is elemental molybdenum.
11. The method of claim 1 , wherein the first layer is one of molybdenum oxynitride and molybdenum nitride.
12. The method of claim 1 , wherein the first ALD process is performed at a temperature less than 400° C.
13. The method of claim 12 , wherein the second ALD process is performed at a temperature greater than 400° C.
14. The method of claim 1 , wherein deposition of the first layer and deposition of the elemental metal layer are performed in a same chamber.
15. The method of claim 14 , wherein deposition of the first layer and deposition of the elemental metal layer are performed in different stations of the same chamber.
16. The method of claim 1 , wherein deposition of the first layer is performed in a first chamber and deposition of the elemental metal layer is performed in a second chamber.
17. The method of claim 1 , further comprising exposing the first layer to air prior to deposition of the elemental metal layer.
18. The method of claim 1 , wherein the second metal oxychloride precursor is the same precursor as the first metal oxychloride precursor.
19. The method of claim 1 , wherein the second metal oxychloride precursor is a different precursor than the first metal oxychloride precursor.
20. A method comprising:
depositing a first layer from a first metal oxychloride precursor and ammonia using a first atomic layer deposition (ALD) process; and
depositing an elemental metal layer on the first layer from a second metal oxychloride precursor and hydrogen using a second ALD process, wherein the first layer is an amorphous layer.
21. The method of claim 20 , wherein the elemental metal layer on the first layer is crystalline.
22. A method comprising:
depositing a first layer from a first metal oxychloride precursor and ammonia using a first atomic layer deposition (ALD) process; and
depositing an elemental metal layer on the first layer from a second metal oxychloride precursor and hydrogen using a second ALD process, wherein the first layer is a template for metal grain growth in the elemental metal layer.