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:
Dec. 08, 1992
Filed:
Mar. 14, 1991
Herbert Goebel, Reutlingen, DE;
Robert Bosch GmbH, Stuttgart, DE;
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).