Ionic fluid in supercritical fluid for semiconductor processing

• US 20050227187A1
• Filed: 01/12/2005
• Published: 10/13/2005
• Est. Priority Date: 03/04/2002
• Status: Abandoned Application

• Current Assignee: Supercritical Systems, Inc. (Tokyo Electron Limited)
• Original Assignee: Supercritical Systems, Inc. (Tokyo Electron Limited)
• Inventors: Schilling, Paul E.
• Application Number:
  US11/034,585
• Publication Number:
  US 20050227187A1
• Time in Patent Office: Days
• US Class Current: 430/329
• CPC Class Codes: C23C 26/00 Coating not provided for in groups C23C2/00 - C23C24/00
• CPC Class Codes: C23C 30/00 Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: C23C 8/10 Oxidising
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/02101 only involving supercritical fluids
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02343 treatment by exposure to a liquid
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/31058 of organic layers
• CPC Class Codes: H01L 21/3121 Layers comprising organo-silicon compounds
• CPC Class Codes: H01L 21/3125 layers comprising silazane compounds
• CPC Class Codes: H01L 21/316 composed of oxides or glassy oxides or oxide based glass
• CPC Class Codes: H01L 21/31629 Deposition of halogen doped silicon oxide, e.g. fluorine doped silicon oxide
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC

Abstract

A method of removing post-etch residue from a patterned low-k dielectric layer is disclosed. The low-k dielectric layer preferably comprises a porous silicon oxide-based material with the post-etch residue thereon. The post-etch residue is a polymer, a polymer contaminated with an inorganic material, an anti-reflective coating and/or a combination thereof. In accordance the method of the present invention, the post-etch residue is removed by treating the patterned low-k dielectric layer to a cleaning solution comprising supercritical carbon dioxide and an amount of an ionic fluid that preferably includes a salt with cyclic a nitrogen cation structure, such as an imidazolium or pyridinium ion, and a suitable anion, including but not limited to, a chloride, a bromide, a tetrafluoroborate, a methyl sulfate and a hexafluorophosphate anion.

Claims

1. A method of removing a residue from a substrate structure, the method comprising:

maintaining the substrate structure in a supercritical cleaning solution comprising supercritical CO₂ and an amount of an ionic fluid; and

removing the supercritical cleaning solution, thereby removing a first portion of the residue from the substrate structure.

2. The method of claim 1, wherein the ionic fluid comprises a heterocyclic salt.

3. The method of claim 2, wherein the heterocyclic salt is selected from the group consisting of imidazole salt and a pyridine salt.

4. The method of claim 3, wherein the heterocyclic salt comprises an imidazolium ion and at least one anion selected from the group consisting of a chloride anion, a bromide anion, a tetrafluoroborate anion, a methyl sulfate anion, and a hexafluorophosphate anion.

5. The method of claim 4, wherein the imidazolium ion is functionalized with at least one of a hydrogen atom, an organic group, or a combination thereof.

6. The method of claim 5, wherein the organic group comprises at least one of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and aromatic hydrocarbon group, or a combination thereof.

7. The method of claim 3, wherein the heterocyclic salt comprises an pyridinium ion and at least one anion selected from the group consisting of a chloride anion, a bromide anion, a tetrafluoroborate anion, a methyl sulfate anion, and a hexafluorophosphate anion.

8. The method of claim 7, wherein the pyridinium ion is functionalized with at least one of a hydrogen atom, an organic group, or a combination thereof.

9. The method of claim 8, wherein the organic group comprises at least one of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and aromatic hydrocarbon group, or a combination thereof.

10. The method of claim 1, wherein the cleaning solution further comprises a carrier solvent.

11. The method of claim 10, wherein the carrier solvent is selected from the group consisting of N,N-dimethylacetamide (DMAc), gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO), ethylene carbonate (EC), N-methylpyrrolidone (NMP), dimethylpiperidone, propylene carbonate, alcohol, and combinations thereof.

12. The method of claim 1, wherein the residue comprises a post-etch residue, or a post-ash residue, or a combination thereof.

13. The method of claim 1, wherein the substrate structure is maintained at temperatures in a range of approximately 40 degrees Celsius to approximately 250 degrees Celsius.

14. The method of claim 1, wherein the supercritical cleaning solution is maintained at temperatures in a range of approximately 40 degrees Celsius to approximately 250 degrees Celsius.

15. The method of claim 1, wherein the substrate structure comprises a low-k dielectric layer, or an ultra low-k layer or a combination thereof.

16. The method of claim 1, wherein the substrate structure comprises a material selected from the group consisting of carbon-doped oxide (COD), spin-on-glass (SOG), and fluoridated silicon glass (FSG).

17. The method of claim 1, further comprising washing the substrate structure with a supercritical rinsing solution after removing the supercritical cleaning solution and the residue away from the substrate material.

18. The method of claim 17, wherein the supercritical rinsing solution comprises CO₂ and an organic solvent.

19. The method of claim 18, wherein the organic solvent is selected from the group consisting of N, N-dimethylacetamide (DMAc), gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO), ethylene carbonate (EC), N-methylpyrrolidone (NMP), dimethylpiperidone, propylene carbonate, alcohol, and combinations thereof.

20. The method of claim 1, wherein the first portion of the residue comprises substantially all of the residue.

21. The method of claim 1, further comprising:

providing an additional amount of the supercritical cleaning solution to the substrate structure; and

removing the additional amount of the supercritical cleaning solution, thereby removing a second portion of the residue from the substrate structure.

36. The method of claim 1, wherein the supercritical cleaning solution is maintained at pressures in a range of approximately 1,000 psi to approximately 9,000 psi.

22. A method of forming a patterned dielectric layer, the method comprising;

depositing a continuous layer of dielectric material;

forming a photoresist mask over the continuous layer of dielectric material;

patterning the continuous layer of dielectric material through the photoresist mask thereby forming a post-etch residue; and

removing the post-etch residue using a supercritical cleaning solution comprising supercritical carbon dioxide and an amount of an ionic fluid.

23. The method of claim 22, wherein the ionic fluid comprises a heterocyclic salt.

24. The method of claim 23, wherein the heterocyclic salt is selected from the group consisting of imidazole salt and a pyridine salt.

25. The method of claim 24, wherein the heterocyclic salt comprises an imidazolium ion and at least one anion selected from the group consisting of a chloride anion, a bromide anion, a tetrafluoroborate anion, a methyl sulfate anion, and a hexafluorophosphate anion.

26. The method of claim 25, wherein the imidazolium ion is functionalized with at least one of a hydrogen atom, an organic group, or a combination thereof.

27. The method of claim 26, wherein the organic group comprises at least one of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and aromatic hydrocarbon group, or a combination thereof.

28. The method of claim 24, wherein the heterocyclic salt comprises an pyridinium ion and at least one anion selected from the group consisting of a chloride anion, a bromide anion, a tetrafluoroborate anion, a methyl sulfate anion, and a hexafluorophosphate anion.

29. The method of claim 28, wherein the pyridinium ion is functionalized with at least one of a hydrogen atom, an organic group, or a combination thereof.

30. The method of claim 24, wherein the organic group comprises at least one of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and aromatic hydrocarbon group, or a combination thereof.

31. The method of claim 22, wherein the cleaning solution further comprises a carrier solvent.

32. The method of claim 31, wherein the carrier solvent is selected from the group consisting of N, N-dimethylacetamide (DMAc), gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO), ethylene carbonate (EC), N-methylpyrrolidone (NMP), dimethylpiperidone, propylene carbonate, alcohol, and combinations thereof.

33. The method of claim 22, wherein the dielectric material comprises a low-k dielectric layer, or an ultra low-k layer or a combination thereof.

34. The method of claim 22, wherein the dielectric material is maintained at temperatures in a range of approximately 40 degrees Celsius to approximately 250 degrees Celsius.

35. The method of claim 22, wherein the supercritical cleaning solution is maintained at temperatures in a range of approximately 40 degrees Celsius to approximately 250 degrees Celsius.

37. A method of forming a patterned dielectric layer, the method comprising;

depositing a continuous layer of dielectric material;

forming a photoresist mask over the continuous layer of dielectric material;

patterning the continuous layer of dielectric material through the photoresist mask;

removing the photoresist mask, thereby forming a post-ash residue; and

removing the post-ash residue using a supercritical solution comprising supercritical carbon dioxide and a ionic fluid.