Microfabricated cantilever stylus with integrated pyramidal tip

• US 5,399,232 A
• Filed: 01/07/1994
• Issued: 03/21/1995
• Est. Priority Date: 01/17/1989
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Albrecht, Thomas R., Akamine, Shinya, Carver, Thomas E., Zdeblick, Mark J.
• Primary Examiner(s): DANG, THI D
• Application Number:
  US08/179,756
• Time in Patent Office: 438 Days
• Field of Search: 156/647, 156/644, 156/655, 156/657, 156/629, 156/633, 437/228
• US Class Current: 216/2
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 60/38 Probes, their manufacture, or their related instrumentation, e.g. holders
• CPC Class Codes: G01Q 70/10 Shape or taper
• CPC Class Codes: G01Q 70/14 Particular materials
• CPC Class Codes: G01Q 70/16 Probe manufacture

Abstract

A dielectric cantilever arm stylus with an integrally formed pyramidal tip is provided. The tip is molded in a pyramidal pit etched in a later-removed (100) silicon substrate. An integrally-formed cantilever arm is also formed as the tip is being formed. Various thin film materials form the cantilever arm and the tip. In one embodiment of the invention, the dielectric is silicon nitride. The cantilever arm is anodically bonded to a glass block.

Claims

1. A method of fabricating a micromechanical sensor having a cantilever with a tip at one end, comprising the steps of:

providing a wafer substrate having top and bottom sides;

coating said top side of said wafer substrate with a first insulating layer and coating said bottom side of said wafer substrate with a second insulating layer;

after said coating steps, forming an opening in said first insulating layer;

etching a trench in said top side of said wafer substrate through the opening in said first insulating layer;

removing said first insulating layer;

coating the top side of said wafer substrate and said trench with a desired cantilever beam material;

patterning said cantilever beam material to form a cantilever arm with one end overlapping said trench in said wafer substrate; and

completely removing said second insulating layer and then completely removing said wafer substrate from the bottom side of said wafer substrate.

2. The method of claim 1, wherein the wafer substrate is silicon.

3. The method of claim 1, wherein said etching step consists of anisotropically etching said wafer substrate through said opening to form a pyramidal pit in the surface of said wafer substrate.

4. The method of claim 3, wherein said coating step forms a pyramidal tip projecting into the top surface of said wafer substrate.

5. The method of claim 1, wherein said cantilever beam material is a thin film of silicon nitride.

6. The method of claim 1, wherein said cantilever beam material is selected from the group consisting of deposited SiO₂, Al₂ O₃, Au, Ni, Si₃ N₄, and thermally grown SiO₂.

7. A method of fabricating a micromechanical sensor having a cantilever with a tip at one end comprising the steps of:

providing a wafer substrate having top and bottom sides;

coating said top side of said wafer substrate with a first insulating layer and coating said bottom side of said wafer substrate with a second insulating layer;

after said coating steps, forming an opening in said first insulating layer;

etching a trench in said top side of said wafer substrate through the opening in said first insulating layer;

removing said first insulating layer;

coating said trench in the top surface of said wafer substrate with a desired tip material and coating the top surface of said wafer substrate with a desired cantilever material;

patterning the cantilever and tip materials coated on the top surface of said wafer substrate to form a cantilever arm with one end overlapping said trench in said wafer substrate; and

completely removing said second insulating layer and then completely removing said wafer substrate from the bottom side of said wafer substrate.

8. The method of claim 7, wherein said etching step consists of anisotropically etching said wafer substrate through said opening to form a pyramidal pit in the surface of said wafer substrate.

9. The method of claim 8, wherein said coating step forms a pyramidal tip projecting into the top surface of said wafer substrate.

10. The method of claim 7, wherein the wafer substrate is silicon.

11. The method of claim 7, wherein said cantilever material is a thin film of silicon nitride.

12. The method of claim 7, wherein said cantilever material is selected from the group consisting of deposited SiO₂, Al₂ O₃, Au, Ni, Si₃ N₄, and thermally grown SiO₂.

13. A method of fabricating a micromechanical sensor having a cantilever with a tip at one end, comprising the steps of:

providing a wafer substrate having top and bottom sides;

coating said top side of said wafer substrate with a first insulating layer and coating said bottom side of said wafer substrate with a second insulating layer;

after said coating steps, forming an opening in said first insulating layer;

etching a trench in said top side of said wafer substrate through the opening in said first insulating layer;

removing said first insulating layer;

coating the top side of said wafer substrate and said trench with a desired cantilever beam material;

patterning said cantilever beam material to form a cantilever arm with one end overlapping said trench in said wafer substrate;

connecting a second substrate to an end of said cantilever arm distal said tip, said second substrate being connected to the surface of said cantilever arm so that said tip projects away from said second substrate; and

completely removing said second insulating layer and then completely removing said wafer substrate from the bottom side of said wafer substrate.

14. The method of claim 13, wherein

said etching step consists of anisotropically etching said wafer substrate through said opening to form a pyramidal pit in the surface of said wafer substrate;

and

said coating step forms a pyramidal tip projecting into the top surface of said wafer substrate.

15. The method of claim 13, wherein the wafer substrate is silicon.

16. The method of claim 13, wherein said cantilever beam material is a thin film of silicon nitride.

17. The method of claim 13, wherein said cantilever beam material is selected from the group consisting of deposited SiO₂, Al₂ O₃, Au, Ni, Si₃ N₄, and thermally grown SiO₂.

18. A method of fabricating a micromechanical sensor having a cantilever with a tip at one end, comprising the steps of:

providing a wafer substrate having top and bottom sides;

coating said top side of said wafer substrate with a first insulating layer and coating said bottom side of said wafer substrate with a second insulating layer;

after said coating steps, forming an opening in said first insulating layer;

etching a trench in said top side of said wafer substrate through the opening in said first insulating layer;

removing said first insulating layer;

coating said trench in the top surface of said wafer substrate with a desired tip material and coating the top surface of said wafer substrate with a desired cantilever material;

patterning the cantilever and tip materials coated on the top surface of said wafer substrate to form a cantilever arm with one end overlapping said trench in said water substrate;

connecting a second substrate to an end of said cantilever arm distal said tip, said second substrate being connected to the surface of said cantilever arm so that said tip projects away from said second substrate; and

completely removing said second insulating layer and then completely removing said wafer substrate from the bottom side of said wafer substrate.

19. The method of claim 18, wherein

said etching step consists of anisotropically etching said wafer substrate through said opening to form a pyramidal pit in the surface of said wafer substrate;

and

said coating step forms a pyramidal tip projecting into the top surface of said wafer substrate.

20. A method of producing micromechanical sensors for AFM/STM profilometry, which consist of a cantilever beam with at least one tip at its end and a mounting piece at the opposite, comprising the steps of:

coating the top and bottom sides of a wafer substrate to form first and second insulating layers, respectively;

after said coating step, producing a mask in said first insulating layer on the top side of the wafer substrate;

etching a trench in said wafer substrate utilizing said first layer mask;

removing said first insulating layer from the top side of said wafer substrate by etching;

coating the top surface of said wafer substrate and the trench with a desired cantilever beam material and tip material, respectively;

forming said cantilever beam and tip in a photolithographic step and etching step; and

completely removing said second insulating layer and then completely removing the supporting wafer material substrate from the bottom side of said wafer substrate.

21. The method of claim 20, wherein said trench etching step consists of etching a pyramidal shaped groove into the wafer substrate by anisotropic wet etching with KOH solution.

22. A method of producing micromechanical sensors for AFM/STM profilometry, which consist of a cantilever beam with at least one tip at its end and a mounting piece at the opposite, comprising the steps of:

coating the top and bottom sides of a wafer substrate to form first and second insulating layers, respectively;

after said coating step, producing a mask in said first insulating layer on the top side of the wafer substrate;

etching a trench in said wafer substrate utilizing said first layer mask;

removing said first insulating layer from the top side of said wafer substrate by etching;

coating the top surface of said wafer substrate and the trench with a desired cantilever beam material and tip material, respectively;

forming said cantilever beam and tip in a photolithographic step and etching step;

connecting a second substrate to an end of said cantilever beam distal said tip, said second substrate being connected to the surface of said cantilever beam so that said tip projects away from said second substrate; and

completely removing said second insulating layer and then completely removing the supporting wafer material substrate from the bottom side of said wafer substrate.

23. The method of claim 22, wherein

said trench etching step consists of etching a pyramidal shaped groove into the wafer substrate by anisotropic wet etching with KOH solution;

and

said coating step forms a pyramidal tip projecting into the top surface of said wafer substrate.