The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 17, 1998
Filed:
Nov. 25, 1996
Denso Corporation, Kariya, JP;
Abstract
To prevent leakage of light from a waveguide path to an isolation film in a photocoupler, isolation films are formed so that end portions thereof face a substrate, and a photodiode and phototransistor are formed on islands surrounded by these isolation films. Accordingly, a waveguide path optically coupling the photodiode and photocoupler is formed on a silicon oxide film and on the end portions of the isolation films. The isolation films are formed by alternatingly laminating silicon oxide films having a refractive index smaller than the waveguide path and silicon nitride films having a refractive index equal to or greater than the waveguide path. Accordingly, the several film thicknesses of the silicon nitride films are established to be smaller than the wavelength of light within the silicon nitride films. Because of this, leakage of light from the waveguide path to the silicon nitride films of the isolation films can be prevented.