Adhesion improvement for low k dielectrics

1. A method for processing a substrate, comprising:

positioning the substrate in a processing chamber, wherein the substrate has a barrier layer comprising at least silicon and carbon;

introducing an organosilicon compound and an oxidizing gas at a first ratio of organosilicon compound to oxidizing gas into the processing chamber;

generating a plasma of the oxidizing gas and the organosilicon compound to form an initiation layer on the barrier layer;

introducing the organosilicon compound and the oxidizing gas at a second ratio of organosilicon compound to oxidizing gas greater than the first ratio into the processing chamber; and

depositing a first dielectric layer adjacent the dielectric initiation layer, wherein the dielectric layer comprises silicon, oxygen, and carbon and has a dielectric constant of about 3 or less.

2. The method of claim 1 , wherein the barrier layer further comprises oxygen or nitrogen.

3. The method of claim 1 , wherein the organosilicon compound is selected from the group of trimethylsilane, 2,4,6,8-tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, and combinations thereof, and the oxidizing gas is selected from the group of oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, and combinations thereof.

4. The method of claim 1 , wherein the depositing the initiation layer comprises generating a plasma by a dual-frequency RF power source.

5. The method of claim 1 , wherein the depositing the first dielectric layer comprises generating a plasma by a dual-frequency RF power source.

6. The method of claim 1 , wherein the first ratio of the organosilicon compound to the oxidizing gas comprises a ratio of about 1:1 and the second ratio of the organosilicon compound to the oxidizing gas comprises a ratio greater than or equal to about 10:1.

7. The method of claim 1 , further comprising introducing an inert gas with the organosilicon compound and the oxidizing gas.

8. The method of claim 1 , further comprising exposing the barrier layer to a plasma of an inert gas, an oxidizing gas, or both, prior to introducing the oxidizing gas and the organosilicon compound.

9. A method for processing a substrate, comprising:

positioning the substrate in a processing chamber, wherein the substrate has a barrier layer comprising silicon, nitrogen, and carbon;

introducing an inert gas into the processing chamber;

generating a first plasma from a single-frequency RE power source to modify a surface of the barrier layer;

introducing an organosilicon compound and an oxidizing gas in a ratio of about 1:1 into the processing chamber;

generating a second plasma from a dual-frequency RE power source to form an initiation layer on the barrier layer;

introducing the organosilicon compound and the oxidizing gas in a ratio of greater than or equal to about 10:1 into the processing chamber; and

depositing a first dielectric layer adjacent the dielectric initiation layer, wherein the dielectric layer comprises silicon, oxygen, and carbon and has a dielectric constant of about 3 or less.

10. The method of claim 9 , wherein the inert gas comprises helium, argon, or combinations thereof.

11. The method of claim 9 , wherein the organosilicon compound is selected from the group of trimethylsilane, 2,4,6,8-tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, and combinations thereof, and the oxidizing gas is selected from the group of oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, and combinations thereof.

12. The method of claim 11 , wherein an inert gas is introduced with the organosilicon compound.

13. A method for processing a substrate, comprising:

positioning the substrate in a processing chamber, wherein the substrate has a barrier layer comprising at least silicon and carbon;

introducing an oxidizing gas into the processing chamber;

generating a plasma of the oxidizing gas and treating a surface of the barrier layer;

introducing an organosilicon compound at a first flow rate;

depositing an initiation layer on the barrier layer from the oxidizing gas and the organosilicon compound;

introducing the organosilicon compound at a second flow rate greater than the first flow rate;

depositing a first dielectric layer adjacent the dielectric initiation layer from the oxidizing gas and the organosilicon compound, wherein the dielectric layer comprises silicon, oxygen, and carbon and has a dielectric constant of about 3 or less.

14. The method of claim 13 , wherein the barrier layer further comprises oxygen or nitrogen.

15. The method of claim 13 , wherein the organosilicon compound is selected from the group of trimethylsilane, 2,4,6,8-tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, and combinations thereof, and the oxidizing gas is selected from the group of oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, and combinations thereof.

16. The method of claim 13 , wherein the generating the plasma of the oxidizing gas comprises generating a plasma by a single-frequency RF power source and the depositing the initiation layer comprises generating a plasma by a dual-frequency RF power source.

17. The method of claim 13 , wherein an inert gas is introduced with the organosilicon compound.

18. The method of claim 13 , wherein the depositing the initiation layer comprises the organosilicon compound and oxidizing gas present in a ratio of about 1:1.

19. The method of claim 13 , wherein the depositing the first dielectric layer comprises the organosilicon compound and oxidizing gas present in a ratio of greater than or equal to about 10:1.

20. A method for processing a substrate, comprising:

positioning the substrate in a processing chamber, wherein the substrate has a barrier layer comprising at least silicon and carbon;

introducing an oxidizing gas into the processing chamber;

generating a plasma of the oxidizing gas; and

forming an initiation layer on the barrier layer by exposing the barrier layer to the plasma of the oxidizing gas;

introducing an organosilicon compound into the processing chamber after forming the initiation layer;

reacting the organosilicon compound and the oxidizing gas; and

depositing a first dielectric layer adjacent the initiation layer, wherein the dielectric layer comprises silicon, oxygen, and carbon and has a dielectric constant of about 3 or less.