Importance

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Abstract

A capacitive pressure sensor that is fabricated by a batch process affords isolation for the sensing element and leads from the pressure media and provides stress isolation as well. The pressure sensor is made up of a sandwich construction including a silicon wafer which is etched from one side to make cavities in a plurality of desired locations to form deflecting diaphragms, one surface of which acts as a capacitor plate. A glass layer is metalized on both sides and has holes drilled in locations that align with the diaphragms formed on the silicon wafer. The glass layer is anodically bonded to the wafer to form capacitance gap of a few microns relative to the one surface of each diaphragm. The assembly of the metalized glass layer and the silicon wafer is in a preferred form sandwiched between two additional layers, and bonded together in a vacuum atmosphere. The four layer sandwich is then cut up into individual sensors. The initial assembly can be formed to provide dampening of the diaphragm response times and to minimize the likelihood of false signals at high frequency inputs.

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First Claim