Methods and apparatus for deposition of low-k films

1. A method of depositing a film, the method comprising:

providing a substrate having a substrate surface with a plurality of features formed therein, each feature extending a distance from the substrate surface and having a bottom and at least one sidewall;

forming a conformal film on the substrate surface, the conformal film formed comprises SiCN;

exposing the conformal film to a low temperature steam anneal to form an annealed conformal film to convert the SiCN to SiOC, the annealed conformal film having a carbon content within ±20% of a carbon content of the conformal film before the low temperature steam anneal;

subjecting the annealed conformal film to a treatment comprising one or more of rapid thermal processing or ashing; and

exposing the annealed conformal film to a high temperature anneal after treatment to form an annealed low-k film, wherein the low temperature steam anneal occurs at a temperature less than or equal to about 400° C., wherein the conformal film has a thickness in the range of about 10 Å to about 500 Å,

wherein the annealed conformal film has a substantially uniform composition of carbon, nitrogen and oxygen to a film thickness up to about 300 Å, the term “substantially uniform composition” means the composition of the film does not change by more than about 10% relative as a function of depth in the film, and

wherein the high temperature anneal occurs at a temperature greater than or equal to about 400° C., and wherein the low-k film has a dielectric constant less than 5.

2. The method of claim 1 , wherein the conformal film formed comprises SiCN having an initial carbon content, an initial nitrogen content and an initial oxygen content.

3. The method of claim 2 , wherein the low temperature steam anneal increases the oxygen content of the annealed conformal film.

4. The method of claim 1 , wherein the high temperature anneal occurs at a temperature greater than or equal to about 50° C. higher than the low temperature steam anneal.

5. The method of claim 1 , wherein the annealed conformal low-k film has a wet etch rate in dilute HF less than about 20 Å/min for the first minute.

6. The method of claim 5 , wherein the annealed conformal low-k film has a leakage current less than or equal to about 1.5×10 −7 Å/cm 2 .

7. The method of claim 1 , wherein forming the conformal film comprises sequentially exposing the substrate to a silicon precursor and a reactant.

8. The method of claim 7 , wherein the silicon precursor comprises a compound having at least two silicon atoms linked by at least one carbon atom.

9. The method of claim 1 , wherein the high temperature anneal is a high temperature steam anneal.

10. The method of claim 1 , wherein the high temperature anneal is a high temperature thermal anneal.

11. The method of claim 1 , wherein the conformal film is deposited at a temperature of about 250° C., and the high temperature anneal occurs at a temperature that is at least about 10° C. greater than the low temperature steam anneal.

12. The method of claim 7 , wherein the silicon precursor comprises bis(trichlorosilyl)methane and the reactant comprises ammonia.

13. The method of claim 11 , wherein the low temperature steam anneal occur with a partial pressure of water greater than or equal to about 500 Torr.

14. The method of claim 13 , wherein the high temperature anneal is a steam anneal.

15. A method of depositing a film, the method comprising:

providing a substrate having a substrate surface with a plurality of features formed therein, each feature extending a distance from the substrate surface and having a bottom and at least one sidewall;

forming a conformal film on the substrate surface in an atomic layer deposition chamber by sequentially exposing the substrate to a silicon precursor comprising bis(trichlorosilyl)methane and a reactant comprising ammonia to form a film comprising SiCN;

exposing the conformal film to a low temperature steam anneal at a temperature less than or equal to about 400° C. and a partial pressure of water of about 585 Torr to form an annealed conformal film and convert the SiCN to SiOC, the annealed conformal film having a carbon content within ±20% of a carbon content of the conformal film before the low temperature steam anneal;

exposing the substrate with the annealed conformal film to a treatment comprising rapid thermal processing or ashing; and

exposing the treated film to a high temperature anneal at a temperature greater than or equal to about 400° C. to form a film having a wet etch rate in dilute HF less than about 20 Å/min for the first minute, a leakage current less than or equal to about 1.5×10 −7 Å/cm 2 , and a dielectric constant less than 5,

wherein the conformal film has a thickness in the range of about 10 Å to about 500 Å, and

wherein the annealed conformal film has a substantially uniform composition of carbon, nitrogen and oxygen to film thickness up to about 300 Å, the term “substantially uniform composition” means the composition of the film does not change by more than about 10% relative as a function of depth in the film.

16. A method of depositing a film, the method comprising:

providing a substrate having a substrate surface with a plurality of features formed therein, each feature extending a distance from the substrate surface and having a bottom and at least one sidewall;

forming a conformal oxidation barrier on the substrate surface, the oxidation barrier comprising silicon carbonitride;

forming a conformal film on the substrate surface in an atomic layer deposition chamber by sequentially exposing the substrate to a silicon precursor comprising bis(trichlorosilyl)methane and a reactant comprising ammonia;

exposing the conformal film to a low temperature steam anneal at a temperature less than or equal to about 400° C. and a partial pressure of water of about 585 Torr to form an annealed conformal film, the low temperature steam anneal converting the silicon carbonitride to silicon oxycarbide, the annealed conformal film having a carbon content within ±20% of a carbon content of the conformal film before the low temperature steam anneal;

exposing the substrate with the annealed conformal film to a treatment comprising rapid thermal processing or ashing; and

exposing the treated film to a high temperature anneal at a temperature greater than or equal to about 400° C. to form a film having a dielectric constant less than or equal to about 5

wherein the conformal film has a thickness in the range of about 10 Å to about 500 Å, and

wherein the annealed conformal film has a substantially uniform composition of carbon, nitrogen and oxygen to a film thickness up to about 300 Å, the term “substantially uniform composition” means the composition of the film does not change by more than about 10% relative as a function of depth in the film.