Molybdenum thin films by oxidation-reduction
A method of forming a molybdenum film by oxidation and reduction is disclosed. A molybdenum oxide film is formed by CVD or ALD using a halide free organometallic molybdenum precursor. The molybdenum oxide film contains low amounts of carbon impurities. The molybdenum oxide film is reduced to form a highly pure molybdenum film. The molybdenum film has low resistance and properties similar to bulk molybdenum.
1. A method of forming a molybdenum film, the method comprising:
exposing a substrate surface to an organometallic molybdenum precursor and an oxidant to form a molybdenum oxide film, the organometallic molybdenum precursor comprising one or more of CpMo(CO) 2 (NO) or MeCpMo(CO) 2 (NO); and
reducing the molybdenum oxide film to form a molybdenum film.
2. The method of claim 1 , wherein the organometallic molybdenum precursor comprises substantially no halogen atoms.
3. The method of claim 1 , wherein the organometallic molybdenum precursor comprises at least one molybdenum-carbon bond.
4. The method of claim 3 , wherein the molybdenum oxide film has a carbon content of less than or equal to about 5 atomic percent.
5. The method of claim 1 , wherein the oxidant comprises one or more of oxygen, ozone, water or a plasma of one or more thereof.
6. The method of claim 1 , wherein the substrate surface is maintained at a temperature in a range of about 100° C. to about 500° C. during formation of the molybdenum oxide film.
7. The method of claim 1 , wherein the substrate surface is exposed to the organometallic molybdenum precursor and the oxidant simultaneously.
8. The method of claim 1 , wherein the substrate surface is exposed to the organometallic molybdenum precursor and the oxidant sequentially.
9. The method of claim 8 , wherein exposing the substrate surface to the organometallic molybdenum precursor and the oxidant defines an ALD cycle and multiple ALD cycles are performed before the molybdenum oxide film is reduced.
10. The method of claim 1 , wherein the molybdenum oxide film has a thickness in a range of about 0.5 nm to about 10 nm.
11. The method of claim 1 , wherein the substrate surface is maintained at a temperature in a range of about 250° C. to about 500° C. during formation of the molybdenum film.
12. The method of claim 1 , wherein reducing the molybdenum oxide film comprises exposing the molybdenum oxide film to a reductant comprising an alcohol or hydrogen gas.
13. The method of claim 12 , wherein the alcohol comprises one or more of methanol, ethanol, propanol, isopropanol or t-butanol.
14. The method of claim 12 , wherein the reductant comprises a plasma formed from hydrogen gas.
15. The method of claim 1 , wherein the molybdenum film has an impurity content of less than or equal to about 5 atomic percent.
16. The method of claim 1 , wherein the molybdenum film has a bulk resistivity similar to a molybdenum film deposited by physical vapor deposition.
17. A method of forming a molybdenum film, the method comprising:
exposing a substrate surface maintained at a temperature in a range of about 100° C. to about 500° C. to a plurality of ALD cycles to form a molybdenum oxide film with a thickness in a range of 0.5 nm to about 10 nm, each cycle comprising exposure to an organometallic molybdenum precursor and an oxidant, the organometallic molybdenum precursor comprising one or more of CpMo(CO) 2 (NO) or MeCpMo(CO) 2 (NO); and
exposing the molybdenum oxide film maintained at a temperature in a range of about 250° C. to about 500° C. to an alcohol to form a molybdenum film.
18. The method of claim 17 , wherein the molybdenum film has an impurity content of less than or equal to about 5 atomic percent.
19. A method of forming a molybdenum film, the method comprising:
exposing a substrate surface to a plurality of ALD cycles to form a molybdenum oxide film with a thickness in a range of 0.2 nm to about 100 nm, each cycle comprising exposure to an organometallic molybdenum precursor and an oxidant, the organometallic molybdenum precursor comprising one or more of CpMo(CO) 2 (NO) or MeCpMo(CO) 2 (NO), the molybdenum oxide film having a carbon content of less than or equal to about 5 atomic percent; and
exposing the molybdenum oxide film to a reductant to form a molybdenum film, the molybdenum film having an impurity content of less than or equal to about 5 atomic percent.