Methods of making and modifying porous devices for biomedical applications

• US 20070007241A1
• Filed: 04/20/2006
• Published: 01/11/2007
• Est. Priority Date: 04/20/2005
• Status: Abandoned Application

• Current Assignee: University of Rochester
• Original Assignee: University of Rochester
• Inventors: DeLouise, Lisa
• Application Number:
  US11/407,988
• Publication Number:
  US 20070007241A1
• Time in Patent Office: Days
• US Class Current: 216/56
• CPC Class Codes: B81B 2201/0214 Biosensors; Chemical sensors
• CPC Class Codes: B81C 1/00626 Processes for achieving a desired geometry not provided for in groups B81C1/00563 - B81C1/00619
• CPC Class Codes: B81C 2201/0115 Porous silicon
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: Y10T 428/24273 including aperture

Abstract

Etchant solutions for making porous semiconductor materials. Also disclosed are methods of making porous semiconductor materials, post etch treatments, and porous semiconductor materials produced by these methods.

Claims

1. An etch solution comprising about 0-50% ethanol, about 0-25% dimethyl formamide, about 0-30% glycerol, about 5-20% hydrofluoric acid, about 0-90% water, and about 0-1% surfactant.

2. The etch solution according to claim 1 comprising about 0-25% ethanol, about 0-25% dimethyl formamide, about 0-30% glycerol, about 7.5-20% hydrofluoric acid, about 0-85% water, and about 0-1% surfactant.

3. The etch solution according to claim 2 comprising about 25% ethanol, about 10% dimethyl formamide, about 20% hydrofluoric acid, and about 45% water.

4. The etch solution according to claim 2 comprising about 10% ethanol, about 10% dimethyl formamide, about 20% hydrofluoric acid, and about 60% water.

5. The etch solution according to claim 2, comprising about 25% ethanol, about 25% dimethyl formamide, about 30% glycerol, and about 20% hydrofluoric acid.

6. The etch solution according to claim 2, comprising about 10% ethanol, about 25% dimethyl formamide, about 5-30% glycerol, about 20% hydrofluoric acid, and about 15-40% water.

7. The etch solution according to claim 6, comprising about 10% ethanol, about 25% dimethyl formamide, about 5-12% glycerol, about 20% hydrofluoric acid, and about 33-40% water.

8. The etch solution according to claim 6, comprising about 10% ethanol, about 25% dimethyl formamide, about 30% glycerol, about 20% hydrofluoric acid, and about 15% water.

9. The etch solution according to claim 1, comprising about 0-35% ethanol, about 0-10% dimethyl formamide, about 0-30% glycerol, about 10-20% hydrofluoric acid, about 0-1% surfactant, and about 4-90% water.

10. The etch solution according to claim 9, comprising about 35% ethanol, about 30% glycerol, about 15% hydrofluoric acid, about 0.1% surfactant, and about 19% water, wherein the surfactant comprises pluronic F108.

11. The etch solution according to claim 1, wherein the surfactant is selected from the group of nonionic surfactants, cationic surfactants, and anionic surfactants.

12. The etch solution according to claim 11, wherein the surfactant is selected from the group of alkylphenol ethoxylate, alcohol ethoxylates, Rheodol series sorbitan esters, ethylene oxide/polyethylene oxide block polymers, pluronic F108, pluronic F108, pluronic F38, pluronic P105, pluronic L101, pluronic L31, Dowfax series polymers, Triton series alkylpolyglucosides, quaternary ammonium compounds, and alkyl, aryl, and ethyl sulfates and phosphates.

13. The etch solution according to claim 1, further comprising an oxidizing agent.

14. The etch solution according to claim 13, wherein the oxidizing agent is selected from the group of chromium trioxide, ammonium persulfate, osmium tetroxide, and potassium permanganate.

15. The etch solution according to claim 1, comprising about 15% hydrofluoric acid, about 85% water, and about 0.1% surfactant.

16. A method of preparing a porous semiconductor structure comprising:

providing a semiconductor material, and

etching the semiconductor material in the etch solution of claim 1 under conditions effective to produce a porous semiconductor structure.

17. The method according to claim 16, said method further comprising treating the semiconductor material with a post electrochemical etch solution after said etching the semiconductor material, wherein the post electrochemical solution is suitable to cause pore opening.

18. The method according to claim 17, wherein the post electrochemical etch solution comprises about 100 μ

M-1 M KOH, about 100 μ

M-1 M NaOH, about 0.001-1% NH₄OH, about 1-100% pyridine, about 1-100% formamide, about 1-100% dimethylformamide, about 1-100% diethylamine, or about 1-100% dimethylacetamide.

19. The method according to claim 16, wherein the etch solution comprises about 25% ethanol, about 10% dimethyl formamide, about 20% hydrofluoric acid, and about 45% water.

20. The method according to claim 16, wherein the etch solution comprises about 10% ethanol, about 10% dimethyl formamide, about 20% hydrofluoric acid, and about 60% water.

21. The method according to claim 16, wherein the etch solution comprises about 25% ethanol, about 25% dimethyl formamide, about 30% glycerol, and about 20% hydrofluoric acid.

22. The method according to claim 16, wherein the etch solution comprises about 10% ethanol, about 25% dimethyl formamide, about 5-30% glycerol, about 20% hydrofluoric acid, and about 15-40% water.

23. The method according to claim 16, wherein the etch solution comprises about 35% ethanol, about 30% glycerol, about 15% hydrofluoric acid, about 0.1% surfactant, and about 19% water, wherein the surfactant comprises pluronic F108.

24. The method according to claim 16, wherein the etch solution comprises about 15% hydrofluoric acid, about 85% water, and about 0.1% pluronic F108.

25. A porous semiconductor structure produced according to the method of claim 16 wherein the porous semiconductor structure has an average pore size of about 3 to about 40 nm and an average porosity of about 34 to about 49%.

26. A porous semiconductor structure produced according to the method of claim 17 wherein the porous semiconductor structure has an average pore size of about 39 nm and an average porosity greater than 71%.

27. A porous semiconductor structure produced according to the method of claim 19, wherein the porous semiconductor structure has an average pore size of at least about 19 nm and an average porosity of at least about 44%.

28. A porous semiconductor structure produced according to the method of claim 20 wherein the porous semiconductor structure has an average pore size of at least about 19 nm and an average porosity of less than about 40%.

29. A porous semiconductor structure produced according to the method of claim 21 wherein the porous semiconductor structure has an average pore size of less than about 12 nm and an average porosity of at least about 49%.

30. A porous semiconductor structure produced according to the method of claim 22 wherein the porous semiconductor structure has an average pore size of less than about 8 nm and an average porosity of less than about 42%.

31. A porous semiconductor structure produced according to the method of claim 23 wherein the porous semiconductor structure has an average pore size of at least about 29 nm and an average porosity of at least about 40%.

32. A porous semiconductor structure produced according to the method of claim 24 wherein the porous semiconductor structure has an average pore size of at least about 82 nm and an average porosity of at least about 79%.