Plasma ashing process

1. A plasma ashing process for selectively removing photoresist and/or organic overlayers from a semiconductor substrate including a low k material, the process comprising:

forming reactive species by exposing a plasma gas composition to an energy source to form a plasma, wherein the plasma is substantially free from reactive nitrogen species and reactive oxygen species; and

exposing the substrate having the photoresist and/or the organic overlayers thereon to the reactive species to selectively remove the photoresist and/or the organic overlayers and leave the low k material substantially the same as before exposing the substrate to the reactive species.

2. The plasma ashing process according to claim 1 , wherein the plasma gas composition consists essentially of hydrogen-bearing gas and a noble gas.

3. The plasma ashing process according to claim 2 , wherein the noble gas is helium.

4. The plasma ashing process according to claim 2 , wherein the hydrogen-bearing gas is selected from the group consisting of hydrocarbons, hydrofluorocarbons, and hydrogen gas.

5. The plasma ashing process according to claim 2 , wherein the hydrogen bearing gas is hydrogen gas.

6. The plasma ashing process according to claim 1 , wherein the low k material comprises a carbon containing material having a dielectric constant less than 3.0.

7. The plasma ashing process according to claim 1 , wherein the low k material essentially does not change during the plasma ashing process.

8. The plasma ashing process according to claim 1 , wherein the plasma that is substantially free from reactive nitrogen species and reactive oxygen species in an amount that removes less than about 50 angstroms of the low k dielectric material after the plasma ashing process and a subsequent wet treatment process, wherein the wet treatment process comprises wetting the substrate with a solution comprising a 100:1 hydrofluoric acid to deionized water solution for a period of 30 seconds.

9. The plasma ashing process according to claim 1 , further comprising exposing the substrate to a wet treatment process, wherein a critical dimension of a feature in the substrate essentially does not change during the wet treatment process.

10. A plasma ashing process for selectively removing photoresist and/or organic overlayers from a semiconductor substrate including a low k material, the process comprising:

forming reactive species by exposing a plasma gas composition to an energy source to form a plasma, wherein the plasma is substantially free from reactive nitrogen species and reactive oxygen species;

introducing oxygen into the plasma in an amount effective to increase the ashing rate relative to not introducing oxygen into plasma; and

exposing the substrate having the photoresist and/or organic overlayers thereon to the reactive species to selectively remove the photoresist and/or organic overlayers, wherein loss of the low k dielectric material is less than 50 angstroms after further exposure to a dilute hydrofluoric acid wet treatment process comprising wetting the substrate with a 100:1 hydrofluoric acid to deionized water solution for a period of 30 seconds.

11. A post etch plasma ashing process for selectively removing photoresist, organic overlayers, and polymers/residues from a semiconductor substrate, wherein the substrate includes a layer comprising a carbon containing low k dielectric material having a dielectric constant less than 3.0, the plasma ashing process comprising:

placing the substrate including photoresist, and/or organic overlayers and/or polymers/residues on the surface of the substrate into a reaction chamber;

forming reactive species by generating a plasma from a substantially nitrogen and oxygen free gas composition;

exposing the substrate to the reactive species formed in the plasma from the substantially nitrogen and oxygen free gas composition; and

selectively removing the photoresist, organic overlayers, and polymers/residues from the surface by forming volatile compounds, rinse removable compounds and mixtures thereof, wherein the trace levels of oxygen and/or nitrogen introduced into the plasma are in an amount that removes less than about 50 angstroms of the low k dielectric material after further exposure to a wet treatment process.

12. The post etch plasma ashing process according to claim 11 , wherein the gas composition comprises hydrogen gas and helium gas.

13. The post etch plasma ashing process according to claim 11 , wherein the gas composition further comprises a fluorine bearing gas.

14. The post etch plasma ashing process according to claim 12 , wherein the hydrogen gas is in an amount ranging from about 1 percent to about 99 percent of the total gas composition.

15. The post etch plasma ashing process according to claim 12 , wherein the hydrogen gas is in an amount ranging from about 3 percent to about 30 percent of the total gas composition.

16. The post etch plasma ashing process according to claim 12 , wherein the hydrogen gas is in an amount ranging from about 1 percent to about 5 percent of the total gas composition.

17. The post etch plasma ashing process according to claim 12 , wherein the plasma ashing process produces an ashing selectivity between the photoresist and the substrate of greater than 50:1.

18. The post etch plasma ashing process according to claim 11 , wherein the dielectric constant essentially does not change during the plasma ashing process.

19. The post etch plasma ashing process according to claim 11 , wherein the chemical composition of the low k dielectric material essentially does not change during the plasma ashing process.

20. The post etch plasma ashing process according to claim 11 , wherein a critical dimension of a feature on the substrate essentially does not change during the wet treatment process.

21. The post etch plasma ashing process according to claim 11 , wherein the wet treatment process comprises immersing the substrate in a wet chemical bath.

22. The post etch plasma ashing process according to claim 21 , wherein the wet chemical bath selectively removes a carbon depleted portion of the carbon containing low k dielectric material.

23. The post etch plasma ashing process according to claim 21 , wherein the wet chemical bath comprises an aqueous hydrofluoric acid solution.

24. A method of manufacturing a microelectronic device, the method comprising:

forming a photoresist mask on a surface of a semiconductor substrate, wherein the substrate includes a carbon containing low k dielectric layer;

etching and removing portions of the substrate through openings in the photoresist mask to permanently transfer an image into the substrate and expose a surface of the low k dielectric layer, wherein the etching forms polymers/residues on the substrate; and

selectively ashing the photoresist mask, and removing or rendering removable the polymers/residues from the substrate with a substantially oxygen and nitrogen free plasma generated from a gas mixture comprising hydrogen and helium.

25. The method according to claim 24 , wherein the low k dielectric layer has a dielectric constant less than 3.0.

26. The method according to claim 24 , wherein the low k dielectric layer comprises a polymer having a backbone containing silicon.

27. The method according to claim 24 , wherein the low k dielectric layer comprises a carbon doped oxide.

28. The method according to claim 24 , further comprising a wet treatment of the substrate subsequent to ashing the photoresist from the substrate, wherein a critical dimension of the image in the substrate essentially does not change during the wet treatment.

29. The method according to claim 24 , further comprising a wet treatment of the substrate subsequent to ashing the photoresist from the substrate, wherein the polymers/residues are substantially removed during the wet treatment.

30. The method according to claim 28 , wherein the wet treatment of the substrate comprises immersing the substrate in a wet chemical bath.

31. The method according to claim 30 , wherein the chemical bath comprises a chemical that removes only the carbon depleted portion of the low k dielectric material.

32. The method according to claim 31 , wherein the chemical comprises an aqueous hydrofluoric acid solution at a concentration of hydrofluoric acid to water of about 100:1 to about 5000:1.

33. A plasma ashing process for selectively stripping photoresist and/or organic overlayers and/or polymers/residues from a surface of a substrate, the method comprising:

placing a substrate having the photoresist and/or organic overlayers and/or polymers/residues thereon into a reaction chamber;

generating a substantially oxygen and nitrogen free plasma from a gas mixture comprising hydrogen and helium, wherein the gas mixture comprises levels of oxygen and/or nitrogen containing gas in an amount that removes less than about 50 angstroms of a low k dielectric material after ashing the photoresist and/or organic overlayers and/or polymers/residues and a subsequent wet treatment process, and wherein the plasma contains both electrically neutral and charged particles;

substantially removing the charged particles from the plasma;

exposing the substrate and the photoresist and/or organic overlayers and/or polymers/residues to the electrically neutral species in the plasma, wherein the substrate exposed to the plasma includes a carbon containing low k dielectric material; and

ashing the photoresist and/or organic overlayers and/or polymers/residues to selectively remove the photoresist and/or organic overlayers and/or polymers/residues from the substrate, wherein the chemical composition of the low k dielectric material is substantially the same as before the step of exposing the substrate to the plasma.

34. A plasma ashing process for selectively removing photoresist and/or organic overlayers from a semiconductor substrate including a low k material, the process comprising:

forming reactive species by exposing a plasma gas composition to an energy source to form a plasma, wherein the plasma is substantially free from reactive nitrogen species and reactive oxygen species;

introducing oxygen gas or an oxygen containing compound into the plasma in an amount effective to increase the ashing rate relative to not introducing oxygen into plasma;

exposing the substrate having the photoresist and/or organic overlayers thereon to the reactive species to selectively remove the photoresist and/or organic overlayers, wherein loss of the low k material is less than 50 angstroms after further exposure to a wet treatment process comprising wetting the substrate with a solution comprising 100:1 hydrofluoric acid to deionized water solution for a period of 30 seconds.

35. A plasma ashing process for selectively stripping photoresist, organic overlayers, and/or polymers/residues from a surface of a substrate including a low k material, the method comprising:

placing the substrate having the photoresist, organic overlayers, and/or polymers/residues thereon into a reaction chamber;

exposing the substrate at a first temperature to a plasma substantially free from oxygen and nitrogen species;

adding trace amounts of oxygen and/or nitrogen to the plasma for a first period of time; and

increasing the first temperature to a second temperature and stopping the addition of the trace amounts of oxygen and/or nitrogen to the plasma, and exposing the substrate for a second period of time, wherein a total amount of oxygen and/or nitrogen in the plasma and a total amount of the time is effective to remove less than about 50 angstroms of the low k material after further exposure to a wet treatment process comprising wetting the substrate with a solution comprising a 100:1 hydrofluoric acid to deionized water solution for a period of 30 seconds.

36. The plasma ashing process of claim 35 , wherein the substantially oxygen and nitrogen free plasma is formed from a gas mixture comprising hydrogen and helium.

37. The plasma ashing process of claim 35 , wherein the first temperature is about 100° C. to about 300° C. and the second temperature is about 250° C. to about 350° C.

38. A plasma ashing process for selectively stripping photoresist, organic overlayer, and/or polymers and residues from a surface of substrate including a low k material, the method comprising:

placing the substrate having the photoresist, organic overlayer, and/or polymers and residues thereon into a reaction chamber;

exposing the substrate at a first temperature to a plasma substantially free from oxygen and nitrogen species;

adding trace amounts of oxygen and/or nitrogen to the plasma for a period of time; and

decreasing the first temperature to a second temperature and adding trace amounts of oxygen and/or nitrogen to the plasma for a period of time, and exposing the substrate for a second period of time, wherein a total amount of oxygen and/or nitrogen in the plasma and a total amount of the time is effective to remove less than about 50 angstroms of the low k material after further exposure to a wet treatment process comprising wetting the substrate with a solution comprising a 100:1 hydrofluoric acid to deionized water solution for a period of 30 seconds.

39. The plasma ashing process of claim 38 , wherein the substantially oxygen and nitrogen free plasma is formed from a gas mixture comprising hydrogen and helium.

40. The plasma ashing process of claim 38 , wherein the first temperature is about 250° C. to about 350° C. and the second temperature is about 100° C. to about 300° C.