Method for front end of line fabrication
In one embodiment, a method for removing native oxides from a substrate surface is provided which includes supporting a substrate containing silicon oxide within a processing chamber, generating a plasma of reactive species from a gas mixture within the processing chamber, cooling the substrate to a first temperature of less than about 65° C. within the processing chamber, and directing the reactive species to the cooled substrate to react with the silicon oxide thereon while forming a film on the substrate. The film usually contains ammonium hexafluorosilicate. The method further provides positioning the substrate in close proximity to a gas distribution plate, and heating the substrate to a second temperature of about 100° C. or greater within the processing chamber to sublimate or remove the film. The gas mixture may contain ammonia, nitrogen trifluoride, and a carrier gas.
1. A method for removing silicon oxides from a substrate surface, comprising:
positioning a substrate comprising exposed silicon oxide in a first position within a processing chamber, the first position spaced a first distance from a gas distribution plate coupled to the chamber;
generating a plasma of reactive species from a gas mixture within the processing chamber;
contacting the exposed silicon oxide on the substrate with reactive species while forming a film on the substrate at a first temperature of less than about 65° C.;
moving the substrate into a second position within the processing chamber, the second position located a second distance from the gas distribution plate, the second distance being less than the first distance; and
heating the substrate to a second temperature of about 100° C. or greater within the processing chamber at the second position to sublimate the film.
2. The method of claim 1 , wherein the film comprises ammonium hexafluorosilicate.
3. The method of claim 1 , wherein the gas mixture comprises ammonia, nitrogen trifluoride, and a carrier gas.
4. The method of claim 3 , wherein the gas mixture comprises a total volume of the ammonia and the nitrogen trifluoride within a range from about 0.05% to about 20%.
5. The method of claim 1 , wherein the first temperature is about room temperature or less.
6. The method of claim 5 , wherein the first temperature is about 22° C. or less.
7. The method of claim 1 , wherein the first temperature is within a range from about 15° C. to about 50° C.
8. The method of claim 7 , wherein the first temperature is within a range from about 22° C. to about 40° C.
9. The method of claim 1 , wherein heating the substrate comprises positioning the substrate adjacent a heated gas distribution plate disposed within the processing chamber.
10. The method of claim 9 , wherein the second temperature is within a range from about 115° C. to about 200° C.
11. The method of claim 9 , wherein the second temperature is about 120° C.
12. The method of claim 9 , wherein the second position is located within a range from about 10 mils to about 200 mils from the heated gas distribution plate.
13. The method of claim 1 , wherein the gas mixture comprises a molar ratio of ammonia to nitrogen trifluoride of at least 3:1.
14. The method of claim 13 , wherein the molar ratio of ammonia to nitrogen trifluoride is within a range from about 5:1 to about 30:1.
15. The method of claim 1 , wherein the gas distribution plate is heated to a temperature within a range from about 100° C. to about 150° C. while heating the substrate within the processing chamber to sublimate the film.
16. The method of claim 15 , wherein the substrate is located from the gas distribution plate a distance within a range from about 10 mils to about 200 mils.
17. A method for removing silicon oxides from a substrate surface within a processing chamber, comprising:
generating a plasma of reactive species from a gas mixture within the processing chamber, wherein the plasma comprises ammonium fluoride or ammonium hydrogen fluoride;
exposing a silicon oxide surface on a substrate located in a first position to the plasma at a first temperature of less than about 65° C. while forming a film comprising ammonium hexafluorosilicate, the first position spaced a first distance from a gas distribution plate coupled to the chamber;
heating the gas distribution plate within the processing chamber;
positioning the substrate in a second position, the second position located a second distance from the gas distribution plate, the second distance being less than the first distance and within a range from about 10 mils to about 200 mils from the gas distribution plate; and
heating the substrate to a second temperature of about 100° C. or greater within the processing chamber at the second position to sublimate the film.
18. The method of claim 17 , wherein the gas mixture comprises ammonia, nitrogen trifluoride, and a carrier gas.
19. The method of claim 18 , wherein the gas mixture comprises a total volume of the ammonia and the nitrogen trifluoride within a range from about 0.05% to about 20%.
20. The method of claim 17 , wherein the first temperature is about 22° C. or less.
21. The method of claim 17 , wherein the first temperature is within a range from about 15° C. to about 50° C.
22. The method of claim 21 , wherein the second temperature is about 120° C.
23. The method of claim 17 , wherein the gas mixture comprises a molar ratio of ammonia to nitrogen trifluoride of at least 3:1.
24. The method of claim 23 , wherein the molar ratio of ammonia to nitrogen trifluoride is within a range from about 5:1 to about 30:1.
25. A method for removing silicon oxides from a substrate surface, comprising:
supporting a substrate in a first position, the substrate comprising a silicon oxide surface within a processing chamber, the first position spaced a first distance from a gas distribution plate coupled to the chamber;
generating a plasma of reactive species from a gas mixture within the processing chamber, wherein the gas mixture comprises ammonia, nitrogen trifluoride, and a carrier gas and the gas mixture comprises a total volume of the ammonia and the nitrogen trifluoride within a range from about 0.05% to about 20%;
cooling the substrate to a first temperature of less than about 65° C. within the processing chamber;
exposing the silicon oxide surface on the cooled substrate to reactive species while forming a film on the substrate;
moving the substrate to a second position within the processing chamber, the second position located a second distance from the gas distribution plate, the second distance being less than the first distance; and
heating the substrate to a second temperature of about 100° C. or greater within the processing chamber to sublimate the film.
26. The method of claim 25 , wherein the second temperature is within a range from about 115° C. to about 200° C., and the operating pressure within the chamber is within a range from about 500 milliTorr to about 30 Torr while heating substrate.
27. The method of claim 26 , wherein the second distance is within a range from about 10 mils to about 200 mils from the gas distribution plate.
28. The method of claim 27 , wherein the first temperature is within a range between about 22° C. and 40° C., and the second temperature is within a range from about 115° C. and 200° C.