IMPROVED SEMICONDUCTOR PRESSURE SENSOR MEANS AND METHOD

摘要

A piezo-resistive pressure sensor element (20) is formed in the front face (26) of a silicon wafer (12). A thin diaphragm (16) is formed under the sensing element (20) by anisotropically etching a cavity (14) from the rear face (23) of the wafer (12). The rear face (23) (cavity-side) rupture pressure of the silicon diaphragm (16) is at least doubled by subjecting the anisotropically etched cavity (14) to a mild isotropic etch. This substantially improves the cavity-side over-pressure rating of the finished pressure sensor (10) without any significant change in the device sensitivity or allows higher sensitivity to be obtained for the same over-pressure rating or intermediate combinations thereof.