Capacitive absolute pressure sensor
First Claim
1. A capacitive pressure sensor comprising:
- a substrate having
1) an electrode disposed thereon,
2) a first portion and a second portion spanned by the electrode, and
3) an insulating layer disposed over the electrode in the first portion only;
a diaphragm assembly on the substrate including a frame structure and a dividing wall defining a first region, across which a diaphragm is disposed, and a second open region; and
,the first and second regions being arranged on the substrate such that
1) the first portion of the substrate is aligned with the first region and the diaphragm so the diaphragm, the substrate, the dividing wall, and corresponding frame structure defining the first region, form an evacuated chamber and
2) the second portion of the substrate is aligned with the second open region to facilitate access to the electrode,the dividing wall generally separating the first and second regions and contacting the insulating layer on the electrode in the first portion, the insulating layer and the electrode being of a predetermined thickness and, the insulating layer deforming around the electrode to seal and maintain a vacuum state in the evacuated chamber.
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Accused Products
Abstract
A capacitive absolute pressure sensor. The sensor includes a substrate having an electrode deposited thereon and a diaphragm assembly disposed on the substrate. As pressure increases, the diaphragm deflects, touches the electrode (in the touch mode), and changes the capacitance of the sensor. The changed capacitance is sensed to thus sense pressure changes. A buried feedthrough is used to sense the change in a capacitance in a chamber under the diaphragm and thus determine the pressure sensed. A vacuum in the chamber is maintained by proper selection of a thickness of a sensing electrode and an insulating layer, exposition thereof to a thermal cycle, and the hermetic bonding of the diaphragm assembly to the substrate.
94 Citations
12 Claims
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1. A capacitive pressure sensor comprising:
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a substrate having
1) an electrode disposed thereon,
2) a first portion and a second portion spanned by the electrode, and
3) an insulating layer disposed over the electrode in the first portion only;a diaphragm assembly on the substrate including a frame structure and a dividing wall defining a first region, across which a diaphragm is disposed, and a second open region; and
,the first and second regions being arranged on the substrate such that
1) the first portion of the substrate is aligned with the first region and the diaphragm so the diaphragm, the substrate, the dividing wall, and corresponding frame structure defining the first region, form an evacuated chamber and
2) the second portion of the substrate is aligned with the second open region to facilitate access to the electrode,the dividing wall generally separating the first and second regions and contacting the insulating layer on the electrode in the first portion, the insulating layer and the electrode being of a predetermined thickness and, the insulating layer deforming around the electrode to seal and maintain a vacuum state in the evacuated chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification