Techniques for precision pattern transfer of carbon nanotubes from photo mask to wafers

• US 7,538,040 B2
• Filed: 12/08/2005
• Issued: 05/26/2009
• Est. Priority Date: 06/30/2005
• Status: Expired due to Fees

• Current Assignee: Nantero Incorporated
• Original Assignee: Nantero Incorporated
• Inventors: Carter, Richard J., Elmer, James, McGrath, Peter G., Rueckes, Thomas, Gu, Shiqun
• Primary Examiner(s): DANG, TRUNG Q
• Application Number:
  US11/298,274
• Publication Number:
  US 20070004191A1
• Time in Patent Office: 1,265 Days
• Field of Search: 438/717, 438/743, 257/E21.023, 257/E21.029, 977/742
• US Class Current: 438/717
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/32139 using masks
• CPC Class Codes: H01L 21/76838 characterised by the formation and the after-treatment of the conductors etching for patterning the conductors H01L21/3213
• CPC Class Codes: H10K 71/233 by photolithographic etching
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs

Abstract

A method for patterning CNTs on a wafer wherein a CNT layer is provided on a substrate, a hard mask film is deposited on the CNT layer, a BARC layer (optional) is coated on the hard mask film, and a resist is patterned on the BARC layer (or directly on the hard mask film if the BARC layer is not included). Then, the resist pattern is effectively transferred to the hard mask film by etching the BARC layer (if provided) and etching partly into, but not entirely through, the hard mask film (i.e., etching is stopped before reaching the CNT layer) Then, the resist and the BARC layer (if provided) is stripped, and the hard mask pattern is effectively transferred to the CNTs by etching away (preferably by using Cl, F plasma) the portions of the hard mask which have been already partially etched away.

Claims

1. A method of patterning CNTs on a substrate comprising:

providing the substrate, wherein the substrate has a CNT layer thereon;

depositing a hard mask film on the CNT layer;

coating a BARC layer on the hard mask film;

patterning a resist on the BARC layer;

etching the BARC layer;

etching partly into, but not entirely through, the hard mask film, whereby etching is stopped before reaching the CNT layer;

stripping the resist and the BARC layer; and

etching away portions of the hard mask which have been already partially etched away.

2. A method as recited in claim 1, wherein the step of etching the BARC layer comprises using O₂ plasma or other plasma such as Cl, F.

3. A method as recited in claim 1, wherein the step of etching partly into, but not entirely through, the hard mask film, comprises using F or Cl based plasma.

4. A method as recited in claim 1, wherein the step of stripping the resist and the BARC layer comprises using O₂ plasma.

5. A method as recited in claim 1, wherein the step of etching away portions of the hard mask which have been already partially etched away comprises using no O₂ plasma.

6. A method as recited in claim 1, wherein the step of etching away portions of the hard mask which have been already partially etched away comprises using low O₂ plasma.

7. A method as recited in claim 1, wherein the step of depositing a hard mask film on the CNT layer comprises depositing a single layer hard mask, and wherein said step of etching partly into, but not entirely through, the hard mask film comprises etching away less than all of a thickness of said single layer.

8. A method as recited in claim 1, wherein the step of depositing a hard mask film on the CNT layer comprises depositing a multiple layer hard mask, and wherein said step of etching partly into, but not entirely through, the hard mask film comprises etching away less than all the layers of the hard mask film.

9. A method of patterning CNTs on a substrate comprising:

providing the substrate, wherein the substrate has a CNT layer thereon;

depositing a hard mask film on the CNT layer;

patterning a resist on the CNT layer;

etching partly into, but not entirely through, the hard mask film, whereby etching is stopped before reaching the CNT layer;

stripping the resist; and

etching away portions of the hard mask which have been already partially etched away.

10. A method as recited in claim 9, wherein the step of etching partly into, but not entirely through, the hard mask film, comprises using F or Cl-based plasma.

11. A method as recited in claim 9, wherein the step of stripping the resist and comprises using O₂ plasma.

12. A method as recited in claim 9, wherein the step of etching away portions of the hard mask which have been already partially etched away comprises using no O₂ plasma.

13. A method as recited in claim 9, wherein the step of etching away portions of the hard mask which have been already partially etched away comprises using low O₂ plasma.

14. A method as recited in claim 9, wherein the step of depositing a hard mask film on the CNT layer comprises depositing a single layer hard mask, and wherein said step of etching partly into, but not entirely through, the hard mask film comprises etching away less than all of a thickness of said single layer.

15. A method as recited in claim 9, wherein the step of depositing a hard mask film on the CNT layer comprises depositing a multiple layer hard mask, and wherein said step of etching partly into, but not entirely through, the hard mask film comprises etching away less than all the layers of the hard mask film.