Directional SiO
Methods for processing a substrate are described herein. Methods can include positioning a substrate with an exposed surface comprising a silicon oxide layer in a processing chamber, biasing the substrate, treating the substrate to roughen a portion of the silicon oxide layer, heating the substrate to a first temperature, exposing the exposed surface of the substrate to ammonium fluoride to form one or more volatile products while maintaining the first temperature, and heating the substrate to a second temperature, which is higher than the first temperature, to sublimate the volatile products.
1. A method, comprising:
positioning a substrate in a processing chamber, the substrate comprising:
an exposed surface having one or more features formed in the exposed surface, the features comprising a bottom surface; and
an oxide layer formed on the exposed surface;
biasing the substrate;
exposing the substrate to an inert plasma to selectively form an activated material on the oxide layer on the exposed surface and the bottom surface of the features;
heating the substrate to a first temperature;
exposing the substrate to a processing gas comprising ammonium fluoride (NH 4 F) or NH 4 F(HF) to form one or more volatile products on the activated material; and
heating the substrate to a second temperature, which is higher than the first temperature, to sublimate the one or more volatile products.
2. The method of claim 1 , wherein the first temperature and the second temperature are within 10° C. of one another.
3. The method of claim 1 , wherein the first temperature is a temperature of at least 65° C.
4. The method of claim 1 , wherein the first temperature is a temperature of between 70° C. and 90° C.
5. The method of claim 1 , wherein the second temperature is a temperature of greater than 100° C.
6. The method of claim 1 , wherein the first and second temperatures are both greater than 100° C., and wherein simultaneous etching and sublimation of etch byproducts occurs.
7. The method of claim 1 , wherein heating the substrate to a second temperature further comprises exposing the exposed surface of the substrate to a low energy inert plasma.
8. The method of claim 1 , wherein a plasma is formed from the processing gas, and wherein the plasma is formed remotely.
9. The method of claim 8 , wherein the plasma comprising ammonium fluoride is a non-sputtering plasma.
10. The method of claim 1 , wherein the processing gas is a gas mixture comprising ammonia (NH 3 ) and nitrogen trifluoride (NF 3 ).
11. The method of claim 10 , wherein the gas mixture is a 1:1 or higher ratio of ammonia (NH 3 ) and nitrogen trifluoride (NF 3 ) respectively.
12. The method of claim 11 , wherein the ratio of NH 3 to NF 3 is 5:1 or higher.
13. The method of claim 1 , wherein NH 4 F is formed in a plasma remote from the processing chamber from a formation gas comprising NH 3 , NF 3 , HF, F 2 , H 2 , He, Ar or combinations thereof.
14. The method of claim 1 where NH 4 F is formed in a plasma inside the processing region of the processing chamber from a formation gas comprising NH 3 , NF 3 , HF, F 2 , H 2 , He, Ar or combinations thereof.
15. The method of claim 1 , further comprising:
maintaining the substrate at a first temperature during the exposure to the processing gas;
moving the substrate to a second chamber; and
sublimating one or more etch byproducts.
16. The method of claim 1 , wherein the exposing the substrate to an inert plasma, the heating the substrate to a first temperature, the exposing the substrate to NH 4 F, NH 4 F(HF) or combinations thereof, and heating to a second temperature are repeated one or more times.
17. A method comprising:
positioning a silicon-containing substrate in a processing chamber, the silicon-containing substrate comprising:
an exposed surface;
one or more features formed in the exposed surface; and
a layer of surface contaminants formed on the exposed surface;
heating the substrate to a first temperature;
exposing the layer of surface contaminants on the exposed surface of the substrate to ammonium fluoride (NH 4 F), (NH 4 F)HF, HF or combinations thereof at the first temperature;
biasing the substrate;
exposing the substrate to an inert plasma to selectively form one or more volatile products on the exposed surface and bottom surfaces of the features;
exposing the substrate to low pressure at a second temperature, wherein non-reacted NH 4 F is sublimated from the exposed surface of the substrate; and
heating the substrate to a third temperature, which is higher than the first temperature and the second temperature, to sublimate the one or more volatile products.
18. The method of claim 17 , wherein the exposed surface is exposed to a gas mixture comprising ammonia (NH 3 ) and nitrogen trifluoride (NF 3 ), and wherein the gas mixture is a 1:1 or higher ratio of ammonia (NH 3 ) and nitrogen trifluoride (NF 3 ) respectively.
19. The method of claim 17 , wherein NH 4 F is formed in a plasma remote from the processing chamber from a formation gas comprising NH 3 , NF 3 , HF, F 2 , H 2 , He, Ar, or combinations thereof.
20. A method, comprising:
positioning a semiconductor substrate in a processing chamber, the semiconductor substrate comprising:
an exposed surface having one or more features formed in the exposed surface; and
an oxide layer formed on the exposed surface;
biasing the substrate;
performing a contaminant removal process, comprising:
exposing the substrate to an inert plasma to selectively form an activated material on the oxide layer on the exposed surface and bottom surfaces of the features;
heating the substrate to a first temperature;
exposing the surface of the substrate to a processing gas comprising ammonium fluoride (NH 4 F) or NH 4 F(HF) to form one or more volatile products on the oxide layer on the exposed surface and bottom surfaces of the features; and
heating the substrate to a second temperature, which is higher than the first temperature, to sublimate the one or more volatile products; and
repeating the contaminant removal process one or more times.