Patent ID: 6445053
Filing Date: 2002-09-03
Classification: G01L

Abstract:
An absolute pressure sensor, comprising:a semiconductor membrane having a welled portion and a substantially planar peripheral surface surrounding and connected to the welled portion; a pad of substantially nonconductive material formed directly on a portion of the peripheral surface of the semiconductor membrane; a bonding layer deposited on the peripheral surface and the nonconductive pad so as to completely surround the welled portion of the semiconductor membrane; a generally planar nonconductive base having an upper surface with spaced apart first and second metal conductors deposited thereon, the upper surface of the nonconductive base being brought into contact with a lower surface of the bonding layer and bonded to the semiconductor membrane in a vacuum so as to form a peripheral seal and a vacuum-sealed reference cavity adjacent the welled portion of the semiconductor membrane; the first conductor includes a capacitor plate disposed within the vacuum-sealed reference cavity and an externally accessible lead attached to the capacitor plate and extending continuously and contiguously along the upper surface of the base through the peripheral seal; the second conductor being in electrical communication with the semiconductor membrane; and the first conductor being electrically isolated from the semiconductor membrane by the pad of substantially nonconductive material.