Microcantilever with integral self-aligned sharp tetrahedral tip

US5021364A · kind A · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• Shinya Akamine · Palo Alto, US
• Calvin F. Quate · Stanford, US

Key dates

• Filing date: Oct 31, 1989
• Grant date: Jun 4, 1991
• Expiry date: Oct 31, 2009

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S977/879
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Apparatus and method for forming a microfabricated cantilever with a single crystal, integral silicon tip on a nitride cantilever. A nitride-silicon-nitride sandwich structure is patterned and etched to form a cantilever structure, exposing sidewall portions of the silicon layer. The exposed sidewall portions of the silicon layer are oxidized to form oxide sidewalls. The top nitride layer is removed and the silicon layer is anisotropically etched and removed except fo a tetrahedral silicon tip formed on the rear nitride layer. The tetrahedral silicon tip has one exterior surface bounded by a (111) plane with two additional exterior surfaces bounded by the oxide sidewall. The oxide sidewall is removed to provide a tetrahedral silicon tip at the free end of the nitride cantilever. Alternative cantilever materials such as polysilicon and deposited oxide can be substituted for nitride. Doping the surface region of the cantilever form a P-N junction which provides a stop for electrochemical anisotropic etching of the silicon layer when an electrical potential is applied across the P-N position.