Method of fabricating laser controlled nanolithography

• US 5,360,764 A
• Filed: 02/16/1993
• Issued: 11/01/1994
• Est. Priority Date: 02/16/1993
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Commerce
• Original Assignee: THE GOVERNMENT OF THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY OF COMMERCE
• Inventors: McClelland, Jabez J., Celotta, Robert J.
• Primary Examiner(s): Kunemund, Robert
• Assistant Examiner(s): Paladugu, Ramamohan Rao
• Application Number:
  US08/018,455
• Time in Patent Office: 623 Days
• Field of Search: 427/259, 156/643, 437/80, 437/81, 437/948, 437/173, 148/DIG. 105, 148/DIG. 106, 148/DIG. 143, 250/251
• US Class Current: 427/596
• CPC Class Codes: C23C 14/048 using irradiation by energy or particles
• CPC Class Codes: C30B 23/002 Controlling or regulating
• CPC Class Codes: G03F 1/78 by charged particle beam [CPB], e.g. electron beam patterning of masks
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: G03F 7/2043 with the production of a chemical active agent from a fluid, e.g. an etching agent; with meterial deposition from the fluid phase, e.g. contamination resists
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

Abstract

A method of depositing atoms on a substrate in which a beam of atoms is optically focused utilizing a laser beam. The laser beam is used to form a standing wave above the surface of a substrate. As the beam of atoms is passed through the standing wave, the atoms are focused by dipole force interactions. The deposition of atoms is focused into parallel lines which coincide with the minima of the standing wave. The use of two standing waves allows for focusing the atoms into discrete dots or spots. Relative movement between the substrate and the standing wave(s) allows for depositing atoms in a scanning manner. Various nanostructures can be made by the disclosed method.

Claims

1. In a process of molecular beam epitaxy wherein a flow of atoms is directed toward a surface for deposition thereon, the improvement which comprises, optically focusing and scanning said flow of atoms over said surface.

2. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of chromium atoms;

collimating said beam of chromium atoms to form a collimated beam of atoms;

providing at least one laser beam above said surface of said substrate for optically focusing said collimated beam of chromium atoms; and

directing said collimated beam of chromium atoms through said at least one laser beam and onto said surface of said substrate.

3. A method of depositing atoms on a substrate according to claim 2, wherein each of said at least one laser beams comprise a standing wave.

4. A method of depositing atoms on a substrate according to claim 3, wherein said at least one laser beam comprises two standing waves.

5. A method of depositing atoms on a substrate according to claim 4, wherein said two standing waves are orthogonal to each other.

6. A method of depositing atoms on a substrate according to claim 2, wherein said beam of chromium atoms is both collimated and laser cooled prior to being directed through said at least one laser beam and onto said surface of said substrate.

7. A method of depositing atoms on a substrate according to claim 2, wherein said chromium atoms are deposited onto said surface of said substrate to form a primer layer which is subsequently covered with an additional layer.

8. A method of depositing atoms on a substrate according to claim 2, wherein said chromium atoms are deposited onto said surface of said substrate in a pattern which is used as a mask in a subsequent process step.

9. A method of depositing atoms on a substrate according to claim 8, wherein said subsequent process step comprises etching portions of said substrate which are not covered by said chromium atoms.

10. A method of depositing atoms on a substrate according to claim 9, wherein said etching comprises plasma etching.

11. A method of depositing atoms on a substrate according to claim 2, wherein said chromium atoms provide a doped region on said substrate.

12. A method of depositing atoms on a substrate according to claim 2, wherein said substrate is moved with respect to said at least one laser beam during the deposition.

13. A method of depositing atoms on a substrate according to claim 2, wherein said at least one laser beam is moved with respect to said substrate during the deposition.

14. A method of depositing atoms on a substrate according to claim 2, wherein at least one filter having at least one aperture is provided between said collimated beam of atoms and said at least one laser beam.

15. A method of depositing atoms on a substrate according to claim 14, wherein said at least one aperture comprises a plurality of apertures.

16. A method of depositing atoms on a substrate according to claim 13, wherein at least one filter having at least one aperture is provided between said collimated beam of atoms and said at least one standing wave and said at least one filter is moved together with said at least one laser beam.

17. A method of depositing atoms on a substrate according to claim 16, wherein said at least one aperture comprises a plurality of apertures.

18. A method of depositing atoms on a substrate according to claim 17, wherein said at least one filter comprises two filters.

19. A method of depositing atoms on a substrate according to claim 2, wherein said deposited atoms comprise a chromium oxide magnetic material.

20. A method of depositing atoms on a substrate according to claim 19, wherein said chromium oxide magnetic material is deposited in a pattern.

21. A method of depositing atoms on a substrate according to claim 20, wherein said pattern comprises a series of dots.

22. A method of depositing atoms on a substrate according to claim 20, wherein said pattern comprises a strip.

23. A method of depositing atoms on a substrate according to claim 19, wherein said chromium oxide magnetic material is formed by co-depositing chromium atoms and oxygen atoms.

24. A method of depositing atoms on a substrate according to claim 19, wherein said chromium oxide magnetic material is formed by depositing chromium atoms and thereafter oxidizing said deposited chromium atoms.

25. A method of depositing atoms on a substrate according to claim 2, wherein an additional atomic or molecular species is added together with said chromium atoms.

26. A method of depositing atoms on a substrate according to claim 25, wherein said additional atomic or molecular species is not optically focused by said at least one standing wave.

27. A method of depositing atoms on a substrate according to claim 2, wherein said deposition of atoms is observed during the deposition utilizing a scanning electron microscope.

28. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate so as to form a mask pattern on said surface of said substrate which is used in a subsequent process step.

29. A method of depositing atoms on a substrate according to claim 28, wherein said subsequent process step comprises etching portions of said substrate which are not covered by said mask pattern.

30. A method of depositing atoms on a substrate according to claim 29, wherein said etching comprises plasma etching.

31. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate to form a doped region on said substrate.

32. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms;

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate; and

moving one of said substrate or said at least one standing wave with respect to the other.

33. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms;

providing at least one filter having at least one aperture between said collimated beams of atoms and said at least one standing wave; and

directing said collimated beam of atoms through said at least one filter and said at least one standing wave and onto said surface of said substrate.

34. A method of depositing atoms on a substrate according to claim 33, wherein said at least one aperture comprises a plurality of apertures.

35. A method of depositing atoms on a substrate according to claim 33, wherein said at least one filter comprises two filters.

36. A method of depositing atoms on a substrate which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate, whereby said atoms are deposited as a magnetic material on said substrate.

37. A method of depositing atoms on a substrate according to claim 36, wherein said magnetic material is deposited in an array of dots on said substrate.

38. A method of depositing atoms on a substrate according to claim 36, wherein said magnetic material is deposited in a strip on said substrate.

39. A method of depositing atoms on a substrate according to claim 36, wherein said magnetic material is selected from the group consisting of ferro magnetic materials, ferri magnetic materials, and antiferro magnetic materials.

40. A method of forming a calibration standard which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate so as to deposit said atoms in an absolute pattern for use as a microscopic calibration standard

41. A method of forming an optical grating which comprises:

providing a substrate having a surface;

forming a beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate so as to form an optical grating structure.

42. A method of forming an optical grating according to claim 41, wherein said substrate is moved with respect to said at least one standing wave during the formation of said optical grating structure.

43. A method of forming an optical grating according to claim 41, wherein said at least standing wave is moved with respect to said substrate during the formation of said optical grating structure.

44. A method of forming probe structures on a substrate which comprises:

providing a substrate having a surface;

forming beam of atoms;

collimating said beam of atoms to form a collimated beam of atoms;

providing at least one standing wave above said surface of said substrate for optically focusing said collimated beam of atoms; and

directing said collimated beam of atoms through said at least one standing wave and onto said surface of said substrate and thereby form probe structures which extend from said surface of said substrate.

45. In a method of surface analysis wherein atomic or molecular species from a surface are received by a detector the improvement comprising providing at least one laser beam which directs said atomic or molecular species to said detector.

46. A method of surface analysis according to claim 45, wherein said detector comprises a microscope.