In situ nucleation for nanocrystalline diamond film deposition
Methods of depositing a nanocrystalline diamond film are described. The method may be used in the manufacture of integrated circuits. Methods include treating a substrate with a mild plasma to form a treated substrate surface, incubating the treated substrate with a carbon-rich weak plasma to nucleate diamond particles on the treated substrate surface, followed by treating the substrate with a strong plasma to form a nanocrystalline diamond film.
1. A method of forming a nanocrystalline diamond film, the method comprising:
exposing a silicon substrate to a first plasma from a plasma source with a first plasma power in a range of from 50 W to 12 kW, the first plasma source comprising one or more of C x H y wherein y≥x, carbon dioxide (CO 2 ), hydrogen (H 2 ), nitrogen (N 2 ), and argon (Ar) to provide a treated substrate;
incubating the treated substrate with a gas stream and a second plasma to nucleate diamond particles on a top surface of the substrate, the gas stream comprising a hydrocarbon and the second plasma having a power less than or equal to 15 kW; and
exposing the diamond particles to a third plasma having a power greater than 50 W to form a nanocrystalline diamond film on the top surface of the substrate, the third plasma comprising a microwave plasma with a duty cycle greater than or equal to 60%.
2. The method of claim 1 , wherein the hydrocarbon has a general formula of C m H n , where m is in a range of from 1 to 120, and n is in a range of from 2 to 242.
3. The method of claim 2 , wherein the gas stream further comprises one or more of carbon dioxide (CO 2 ), hydrogen (H 2 ), nitrogen (N 2 ), and argon (Ar).
4. The method of claim 3 , wherein the gas stream comprises from 5% to 90% of the hydrocarbon.
5. The method of claim 1 , wherein the gas stream is ignited at a power of less than 12 kW.
6. The method of claim 1 , wherein the treated substrate is incubated with the gas stream and the second plasma for a time period of less than 4 hours.
7. The method of claim 1 , wherein the treated substrate is maintained at a temperature of less than 450° C. during incubation.
8. The method of claim 1 , wherein the diamond particles are maintained at a temperature in a range of from 100° C. to 750° C. during formation of the nanocrystalline diamond film.
9. The method of claim 1 , wherein incubating the treated substrate is conducted with a duty cycle of less than 100%.
10. The method of claim 1 , wherein the third plasma has a duty cycle greater than 70%.
11. The method of claim 1 , wherein the substrate is exposed to the first plasma at a temperature in a range of from 20° C. to 600° C.
12. The method of claim 1 , wherein the substrate is exposed to the first plasma at a distance of greater than 2 cm.
13. The method of claim 1 , wherein when the treated substrate is incubated with the gas stream, the gas stream is about 2 cm to 10 cm away from the top surface of the treated substrate.
14. The method of claim 1 , wherein when the diamond particles are exposed to the third plasma, the third plasma is less than 10 cm away from the top surface of the substrate.