Reference element for high accuracy silicon capacitive pressure sensor
First Claim
1. A silicon capacitive pressure sensor, comprising:
- a. a header;
b. a sensing element having a conductive silicon sensing substrate and a conductive silicon sensing diaphragm separated by a first dielectric spacer, and having a conductive silicon sensing transition element separated from the sensing diaphragm by a second dielectric spacer, wherein the sensing transition element is mounted to a surface of the header, and wherein the sensing substrate and sensing diaphragm are arranged to form the parallel plates of a sensing capacitor; and
c. a reference element having a conductive silicon reference substrate and a conductive silicon reference diaphragm separated by a third dielectric spacer, and having a conductive silicon reference transition element separated from the reference diaphragm by a fourth dielectric spacer, wherein the reference transition element is mounted to the surface of the header, and wherein the reference substrate and reference diaphragm are arranged to form the parallel plates of a reference capacitor.
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Abstract
A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.
28 Citations
20 Claims
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1. A silicon capacitive pressure sensor, comprising:
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a. a header; b. a sensing element having a conductive silicon sensing substrate and a conductive silicon sensing diaphragm separated by a first dielectric spacer, and having a conductive silicon sensing transition element separated from the sensing diaphragm by a second dielectric spacer, wherein the sensing transition element is mounted to a surface of the header, and wherein the sensing substrate and sensing diaphragm are arranged to form the parallel plates of a sensing capacitor; and c. a reference element having a conductive silicon reference substrate and a conductive silicon reference diaphragm separated by a third dielectric spacer, and having a conductive silicon reference transition element separated from the reference diaphragm by a fourth dielectric spacer, wherein the reference transition element is mounted to the surface of the header, and wherein the reference substrate and reference diaphragm are arranged to form the parallel plates of a reference capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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- 16. In a silicon capacitive pressure sensor including a sensing element having a silicon sensing substrate and a silicon sensing diaphragm separated by a first dielectric spacer, and having a silicon sensing transition element separated from the sensing diaphragm by a second dielectric spacer, wherein the improvement comprises a reference element having a silicon reference substrate and a silicon reference diaphragm separated by a third dielectric spacer, and having a silicon reference transition element separated from the reference diaphragm by a fourth dielectric spacer.
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20. In a capacitive pressure sensor that transduces the pressure value of an applied fluid into a corresponding capacitance value, having a sensing element made up of a sensing substrate and a sensing diaphragm separated by a first dielectric spacer, the sensing element also having a sensing transition element separated from the sensing diaphragm by a second dielectric spacer, the sensing element mounted to a leader, wherein the improvement comprises a reference element having a reference substrate and a reference diaphragm separated by a third dielectric spacer, the reference element also having a reference transition element separated from the reference diaphragm by a fourth dielectric spacer, the reference element being mounted to the header.
Specification