Method of making a multi-layer silicon structure
US5169472A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 14, 1991 |
| Grant date | Dec 8, 1992 |
| Priority date | — |
| Expiry date | Mar 14, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S148/159
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Multi-layer silicon structures particularly micromechanical sensors, can be made by cleaning and polishing respective surfaces of two silicon wafers, assembling the wafers together under clean room conditions and adhering them together by temperature treatment. This method is improved by the pretreatment of the wafer surfaces using fuming nitric acid (e.g., 100% HNO.sub.3), rinsing with de-ionized water, drying, and temperature treatment at a lower temperature than was previously thought necessary, namely between 100.degree. and 400.degree. C. This has the advantage that such gentler treatment preserves previously-applied integrated circuit structures, which can therefore be applied before the wafer assembly steps. The method is particularly suitable for producing pressure sensors having a pressure-responsive silicon membrane, and an evaluation circuit integrated on the silicon wafer. Such sensors are suitable for use in motor vehicles for measuring engine pressures and for measuring brake fluid pressures in anti-lock braking systems (ABS).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.