Photocoupler having element isolation layers for low cross-talk low stress and high break down voltage
US5838174A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1996 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Nov 25, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10H29/10
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.