Method of using heat-depolymerizable polycarbonate sacrificial layer to create nano-fluidic devices

• US 6,743,570 B2
• Filed: 05/24/2002
• Issued: 06/01/2004
• Est. Priority Date: 05/25/2001
• Status: Expired due to Fees

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Coates, Geoff, Craighead, Harold G., Harnett, Cindy K.
• Primary Examiner(s): Young, Christopher G.
• Application Number:
  US10/155,855
• Publication Number:
  US 20030012866A1
• Time in Patent Office: 739 Days
• Field of Search: 430/296, 430/330, 430/320, 430/942
• US Class Current: 430/296
• CPC Class Codes: G03F 7/039 Macromolecular compounds which are photodegradable, e.g. positive electron resists G03F7/075 takes precedence; macromolecular quinonediazides G03F7/023
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: Y10S 430/143 Electron beam

Abstract

A polycarbonate polymer such as poly(cyclohexene carbonate) acts as a positive electron beam resist, is substantially transparent to ultra violet light and that depolymerizes when heated. The polymer acts as a positive electron beam resist at 5 kV, and depolymerizes at temperatures between approximately 200-300° C. The polymer is removable from underneath other layers by heating, facilitating fabrication of overhanging structures such as tubes by depositing layers on top of the polymer.

Claims

1. A method of forming nano-fluidic devices, the method comprising:

forming a layer of polycarbonate on a substrate;

patterning the polycarbonate using electron beam lithography;

coating the patterned polycarbonate with another material; and

heating to a temperature high enough to vaporize the patterned polycarbonate.

2. The method of claim 1 wherein vents are formed to allow the vapor to escape from the device.

3. The method of claim 1 wherein the polycarbonate comprises poly(cyclohexene carbonate).

4. The method of claim 1 wherein the substrate is heated to between approximately 250°

C. to 300°

C.

5. The method of claim 1 wherein the polycarbonate layer is patterned over an accelerating voltage range of approximately 2 to 20 kV.

6. The method of claim 1 wherein the polycarbonate layer is between approximately 50 nm to 250 nm thick.

7. The method of claim 1 wherein the polycarbonate layer is formed by:

dissolving the polycarbonate in toluene;

spinning the toluene/polycarbonate mixture onto a silicon chip; and

baking at approximately 100°

C.

8. A method of forming nano-fluidic devices, the method comprising:

forming a layer of polycarbonate on a substrate;

patterning the polycarbonate;

coating the patterned polycarbonate with another material; and

heating the substrate to a temperature high enough to vaporize the patterned polycarbonate.

9. The method of claim 8 wherein the polycarbonate comprises poly(cyclohexene carbonate).

10. The method of claim 8 wherein the substrate is heated to between approximately 250°

C. to 300°

C.

11. A method of forming nano-fluidic devices, the method comprising:

forming a layer of polycarbonate on a substrate;

patterning the polycarbonate layer using electron beam lithography;

coating the patterned polycarbonate with another material;

forming holes in the material; and

heating the substrate to a temperature high enough to vaporize the patterned polycarbonate.

12. The method of claim 11 wherein the holes are positioned to allow the vapor to escape from the device.

13. The method of claim 11 wherein the polycarbonate comprises poly(cyclohexene carbonate).

14. The method of claim 11 wherein the substrate is heated to between approximately 250°

C. to 300°

C.

15. The method of claim 11 wherein the polycarbonate layer is patterned over an accelerating voltage range of approximately 2 to 20 kV.

16. The method of claim 11 wherein the polycarbonate layer is between approximately 50 nm to 250 nm thick.

17. The method of claim 11 wherein the polycarbonate layer is formed by:

dissolving the polycarbonate in toluene;

spinning the toluene/polycarbonate mixture onto a silicon chip; and

baking at approximately 100°

C.

18. A method of forming nano-fluidic devices, the method comprising:

forming a layer of polycarbonate on a substrate;

patterning the polycarbonate using electron beam lithography;

coating the patterned polycarbonate with an oxide to form a lining material;

coating the patterned polycarbonate and oxide with a supporting material; and

heating to a temperature high enough to vaporize the patterned polycarbonate.

19. The method of claim 18 wherein the supporting material comprises a polymer film.

20. The method of claim 19 wherein the polymer film is spun onto the substrate.