Water soluble negative tone photoresist

1. A method of applying a water soluble negative-tone photoresist for creating closely spaced contact holes, comprising the steps of:

providing a substrate, said substrate having been provided with a first layer of photoresist for creation of a pattern of contact holes;

exposing the surface of said first layer of photoresist with a first mask, said first mask comprising a first and a second pattern of contact holes;

creating openings in said first layer of photoresist in accordance with said first and second pattern of contact holes;

depositing a second layer of negative-tone photoresist over the surface of said first layer of photoresist, including said openings created in said first layer of photoresist, wherein the second layer of negative-tone photoresist comprising a water soluble negative photoresist contains no solvent that damages the first layer of photoresist; and

creating openings in said second layer of negative-tone photoresist in accordance with said second pattern of contact holes,

wherein the water soluble negative photoresist comprises a base polymer, a cross linking element, photo-active compound, a quencher and a solvent, and the base polymer comprises between about 4 to 8% of polyvinylacetal as component of the negative-tone photoresist.

2. The method of claim 1 , said first pattern of holes comprising contact holes.

3. The method of claim 1 , said second pattern of holes comprising dummy holes.

4. The method of claim 1 , with an additional step of cross-linking said first layer of photoresist.

5. The method of claim 1 , with an additional step of hardening the surface of said first layer of photoresist.

6. The method of claim 1 , additionally and prior to depositing a second layer of negative-tone photoresist depositing a layer of photoresist that is compatible with the first layer of photoresist over the first layer of photoresist, followed by cross-linking the first layer of photoresist and the there-with compatible layer, forming an improved packed image in these two layers of photoresist.

7. The method of claim 6 , said cross-linking comprising exposure by a light-source, said light-source is a 365 nm, a 248 nm, a 193 nm, a 157 nm, a EUV or a EB light source.

8. The method of claim 1 , said cross linking element comprising between about 0.5 to 2% of ethyleneurea as component of said negative-tone photoresist.

9. The method of claim 1 , said photo-active compounds comprising between about 0.01 to 0.1% as component of said negative-tone photoresist.

10. The method of claim 9 , said photo-active compound comprising OCH.sub.3, CF.sub.3SO.sub.3, S(CH.sub.3).sub.2 or mixtures thereof.

11. The method of claim 1 , said quencher comprising between about 1 and 30 ppm as component of said negative-tone photoresist.

12. The method of claim 1 , said solvent comprising DIW/IPA, with DIW between about 85 and 90%, IPA between about 4 and 7% as component of said negative-tone photoresist.

13. The method of claim 1 , polyvinylacetal having the chemical composition of:

with n having a value between 0 and about 4.

14. The method of claim 1 , wherein said base polymer is a water soluble polymer, polyvinyl acetal, polyvinyl pyrrolidone, polyallylic acid, polyvinyl alcohol, polyethylemeimine, polyethylene oxide, polyvinylamine, copolymers or mixtures thereof.

15. The method of claim 1 , wherein said photo-active compounds is a water soluble photo acid generator, an onium salt derivative, a triazine derivative or mixtures thereof.

16. The method of claim 1 , wherein said quencher is water soluble amine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, n-propylamine, isopropylamine, s-butylamine, t-butylamine, cycrohexcylamine, ethylenediamine, hexamethylenediamine, monoethanolamine, diethanolamine, triethanolamine, N-buthyldiethanolamine, TMAH, TBAH, choline, TBAH or mixtures thereof.

17. The method of claim 1 , wherein said cross-linking element is a water soluble cross linking agent, urea derivative, melamine derivative, methoxy-methylol-urea or mixtures thereof.

18. The method of claim 1 , wherein said solvent is a non-damageable solvent to PR, DIW or DIW/IPA or mixtures thereof.

19. A method of creating closely spaced contact holes, comprising the steps of:

providing a substrate, said substrate having been provided with a first layer of dual-polarity resist for creation of a pattern of contact holes;

exposing the surface of said first layer of dual-polarity resist with a mask, said mask comprising a first and a second pattern of contact holes, creating a first and a second pattern of exposure in said first layer of dual-polarity resist;

selectively exposing the surface of said first layer of dual-polarity resist to a source of radiation, said selective exposure being in accordance with said second pattern of exposure in said first layer of dual-polarity resist, thereby inhibiting creating openings in said first layer of dual-polarity resist in accordance with said second pattern of exposure;

depositing a second layer of water soluble negative tone photoresist over the first layer of dual-polarity resist, wherein the second layer of negative-tone photoresist contains no solvent that damages the first layer of photoresist; and

developing said second layer of water soluble negative tone photoresist in accordance with said first pattern of exposures,

wherein the water soluble negative photoresist comprises a base polymer, a cross linking element, photo-active compound, a quencher and a solvent, and the base polymer comprises between about 4 to 8% of polyvinylacetal as component of the negative-tone photoresist.

20. The method of claim 19 , said first pattern of exposure comprising contact holes.

21. The method of claim 19 , said second pattern of exposure comprising dummy holes.

22. The method of claim 19 , said selectively exposing comprising exposure by a light-source, said light-source is a 365 nm, a 248 nm, a 193 nm, a 157 nm, a EUV or a EB light source.

23. The method of claim 19 , said cross linking element comprising between about 0.5 to 2% of ethyleneurea as component of said negative-tone photoresist.

24. The method of claim 19 , said photo-active compounds comprising between about 0.01 to 0.1% as component of said negative-tone photoresist.

25. The method of claim 19 , said quencher comprising between about 1 and 30 ppm as component of said negative-tone photoresist.

26. The method of claim 19 , said solvent comprising DIW/IPA, with DIW between about 85 and 90%, IPA between about 4 and 7% as component of said negative-tone photoresist.

27. The method of claim 19 , polyvinylacetal having the chemical composition of:

with n having a value between 0 and about 4.

28. The method of claim 19 , said photo-active compound comprising OCH.sub.3, CF.sub.3SO.sub.3, S(CH.sub.3).sub.2 or mixtures thereof.

29. The method of claim 19 , wherein said base polymer is a water soluble polymer, polyvinyl acetal, polyvinyl pyrrolidone, polyallylic acid, polyvinyl alcohol, polyethylemeimine, polyethylene oxide, polyvinylamine, polyvinylacetal copolymers or mixtures thereof.

30. The method of claim 19 , wherein said photo-active compounds is a water soluble photo acid generator, an onium salt derivative, a triazine derivative or mixtures thereof.

31. The method of claim 19 , wherein said quencher is water soluble amine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, n-propylamine, isopropylamine, s-butylamine, t-butylamine, cycrohexcylamine, ethylenediamine, hexamethylenediamine, monoethanolamine, diethanolamine, triethanolamine, N-buthyldiethanolamine, TMAH, TBAH, choline, TBAH or mixtures thereof.

32. The method of claim 19 , wherein said cross-linking element is a water soluble cross linking agent, urea derivative, melamine derivative, methoxy-methylol-urea or mixtures thereof.

33. The method of claim 19 , wherein said solvent is a non-damageable solvent to PR, DIW or DID/IPA.