Methods of fabricating integrated, aligned tunneling tip pairs

• US 5,449,903 A
• Filed: 06/15/1993
• Issued: 09/12/1995
• Est. Priority Date: 05/14/1991
• Status: Expired due to Term

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Yao, Jun J., Arney, Susanne C., MacDonald, Noel C.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): NGUYEN, KIET TUAN
• Application Number:
  US08/076,906
• Time in Patent Office: 819 Days
• Field of Search: 250/306, 250/302, 156/625
• US Class Current: 850/58
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 20/04 Self-detecting probes, i.e. wherein the probe itself generates a signal representative of its position, e.g. piezoelectric gauge
• CPC Class Codes: G01Q 60/16 Probes, their manufacture, or their related instrumentation, e.g. holders
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type
• CPC Class Codes: Y10S 977/874 Probe tip array

Abstract

Self-aligned, opposed, nanometer dimension tips are fabricated in pairs, one of each pair being located on a movable, single crystal beam, with the beam being movable in three dimensions with respect to a substrate carrying the other tip of a pair. Motion of one tip with respect to the other is controlled or sensed by transducers formed on the supporting beams. Spring means in each beam allow axial motion of the beam. The tips and beams are fabricated from single crystal silicon substrate, and the tips may be electrically isolated from the substrate by fabricating insulating segments in the beam structure.

Claims

1. A submicron tip structure, comprising:

first and second spaced surfaces;

first and second opposed tips on said first and second surfaces, respectively, each tip having an end portion with at least one dimension in the nanometer size range, said tips being spaced apart to define a gap.

2. The device of claim 1, wherein said tips are generally conical, and taper inwardly to a minimum diameter in said nanometer size range.

3. The device of claim 1, wherein said spaced surfaces and tips are integrated on a silicon chip forming said substrate.

4. The device of claim 3, further including capacitor means formed integrally with said spaced surfaces and a substrate for sensing and controlling motion of said one of said tips.

5. The device of claim 3, wherein said substrate, said spaced surfaces, and said tips are single crystal silicon.

6. The device of claim 3, wherein said substrate includes a recess having a peripheral wall and a generally planar floor portion, and wherein a first one of said spaced surfaces is integral with said peripheral wall.

7. The device of claim 6, wherein said first spaced surface comprises a cantilever beam extending into said recess parallel to said floor, and wherein said first tip is mounted on a lower surface of said beam and said second tip is mounted on said floor portion, said gap between said opposed tips being sufficiently small to permit current tunneling therebetween.

8. The device of claim 7, wherein said beam is sufficiently flexible to permit relative motion between said tips.

9. The device of claim 1, further including means supplying electrical current to at least one of said tips.

10. The device of claim 1, wherein one of said spaced surfaces comprises a beam movable with respect to the other of said spaced surfaces to provide relative motion between said first and second tips.

11. The tip structure of claim 1, wherein each said tip is tapered and has a minimum diameter in the nanometer range.

12. The tip structure of claim 1, wherein each said tip is conical and has an axis passing through a terminal end thereof, said tips being coaxial with their respective terminal ends being spaced by said gap.

13. The tip structure of claim 1, further including means mounting said tips for relative motion.

14. The tip structure of claim 1, further including means applying a potential between said tips, and circuit means responsive to changes in said potential connected to at least one of said tips.

15. The tip structures of claim 1, wherein each tip has a terminal end terminating in a single atom.

16. The tip structure of claim 1, wherein said gap is on the order of a few Angstroms.

17. The tip structure of claim 1, further including means connected to said tips to produce a tunnelling current on the order of picoamperes therebetween.

18. The tip structure of claim 1, further including means measuring capacitance between said tips.

19. A submicron tip structure, comprising:

first and second spaced surfaces;

first and second opposed, tapered tips integral with respective ones of said first and second surfaces, said tips having aligned terminal ends spaced apart to form a gap, the terminal end of at least one of said tips having a dimension in the nanometer size range.

20. The tip structure of claim 19, wherein said first and second spaced surfaces are relatively movable to provide relative motion of said tips to vary said gap.

21. The tip structure of claim 20, further including means for sensing relative motion of said tips.

22. The tip structure of claim 21, wherein both of said tips have terminal end dimensions in the nanometer size range.

23. The tip structure of claim 22, wherein said first surface includes a tip support mounted on a substrate for motion with respect to said second surface.