A variable capacitor made from single crystal silicon fracture surface pairs

Complementary and nano-smooth single-crystal-silicon surfaces have been fabricated by deliberately fracturing a weakened portion of a larger structure whose flexural mechanism refines and concentrates an externally applied load to a notched specimen region pre-.fracture and acts as a precision bearing post-fracture. When material is not ejected, crystalline silicon's extreme brittleness at room temperature results in complementary fracture surfaces; "closed" gaps of 20-30 nanometers are typical. Lithographic, focused ion beam, and anisotropically etched notches as well as crystal orientation and specimen thickness were studied, and a method was developed for fabricating smooth surfaces perpendicular to the wafer plane: 10 micrometer square specimens oriented with the (110) plane are fully notched by anisotropic etching (KOH) and fractured within a structure optimized to apply pure tension. Prototype MEMS variable capacitors employing fracture surfaces as separable parallel plates have been developed. The advantage of fracture surfaces over etched surfaces is their exceptional flatness or complementarity, which allow them to very closely approach each other prior to contact.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Sprunt, Alexander D. (Alexander Dalziel), 1977-

Advisor dc:contributor.advisor

• Alexander H. Slocum.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33917

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33917