Fabrication of a surface micromachined capacitive microphone using a dry-etch process
US5573679A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 19, 1995 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | Jun 19, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB81C2201/0132
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Capacitive microphones are fabricated using etch-release of sacrificial silicon by an isotropic dry etchant. The process allows the production of a microphone largely from CVD processes with flexibility in materials selection. The dry etch chemistry does not require freeze-drying after release. The etchant does not attack electrodes or metallized circuitry and so allows the placement of the electrodes between the backplate and diaphragm dielectric layers. Diffusion barrier layers between the sacrificial and electrode layers protect both materials from interdiffusion during device fabrication. The process is especially fitting for a microphone comprising silicon nitride dielectric layers with aluminum electrodes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.