Directional SiO

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 one or more features comprising a bottom surface; and

an oxide layer formed on the exposed surface;

biasing the substrate;

exposing the substrate to a low energy inert plasma to selectively form physically or chemically activated material on the exposed surface and the bottom surface of the one or more 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 exposed surface and the bottom surface of the one or more features; 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 the 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 the plasma is formed remotely.

9. The method of claim 8 , wherein the plasma comprises ammonium fluoride and is a non-sputtering plasma.

10. The method of claim 1 , wherein the processing gas is formed from 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 , wherein NH 4 F is formed in a plasma inside a 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 the first temperature during the exposing the substrate 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 a low energy inert plasma, the heating the substrate to a first temperature, the exposing the substrate to a processing gas comprising NH 4 F or NH 4 F(HF), and the heating the substrate 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;

cooling the substrate to a first temperature;

exposing 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 a low energy inert plasma to selectively form one or more volatile products on the exposed surface and bottom surfaces of the one or more 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:

a top surface having one or more features formed in the top surface; and

an oxide layer formed on the top surface;

biasing the substrate;

performing a contaminant removal process, comprising:

exposing the substrate to a low energy inert plasma to selectively form physically or chemically activated material on the top and bottom surfaces of the one or more 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 top 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.