Photolithographic fabrication of luminescent images on porous silicon structures

US5318676A · kind A · utility

Assignee

• The Regents of the University of California · US

Inventors

• Michael J. Sailor · Village of La Jolla, US
• Vincent V. Doan · San Diego, US

Key dates

• Filing date: Jun 22, 1992
• Grant date: Jun 7, 1994
• Expiry date: Jun 22, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25F3/12
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A polished wafer of single-crystal silicon (Si) is ohmically contacted on its backside to a copper wire to provide a working electrode. The wafer and a counterelectrode are immersed in a solution of aqueous HF and ethanol within an optical quality cuvette. Lithographic images are projected onto the silicon wafer within the solution, and the wafer is etched galvanostatically at a low current density until a predetermined charge density is attained. The areas of an n-type silicon wafer exposed to the light during the etch will exhibit visible luminescence when the wafer is illuminated with an ultraviolet (UV) lamp or other short wavelength visible light. The areas of the wafer that were not exposed to the pattern during etch will not luminesce.