Structure of a three-electrode capacitive pressure sensor

Details Structure of a three-electrode capacitive pressure sensor Structure of a three-electrode capacitive pressure sensor

2000-09-12

2001-05-22

Nelms, David (Department: 2818)

Active solid-state devices (e.g., transistors, solid-state diode

Responsive to non-electrical signal

Physical deformation

C257S414000, C257S415000, C257S416000, C257S417000, C438S050000, C438S051000, C438S053000, C073S024050

Reexamination Certificate

active

06236096

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention is a capacitive pressure sensor. It is a three-electrode capacitive pressure sensor with structure and producing method for of especially integrating and producing both sensor capacitor and reference capacitor into the same pressure sensor cavity for eliminating environment interference of the same mode.
Two parallel electrode plates compose general capacitive pressure sensor. In micro sensor, these two electrode plates generally are a silicon film and a metal film on glass insulation material. Therefore, a dimensional connection of the two upper and lower electrode plates is usually seen in the producing procedure of capacitive pressure sensor. This procedure requires contact base of the two upper and lower electrode plates with optical masking that increases more producing procedure and causes cost enhancement.
For avoiding dimensional connection of upper and lower electrode plates for a single capacitor, one electrode plate can be separated into two parts and then form a planar connection by series of capacitors through another electrode plate. However, this method will reduce its pressure sensitivity because the original capacitor is divided into two smaller capacitors, which then are connected by series method.
The capacitor pressure sensor composed by the dual capacitors, one is sensor capacitor and the other is reference capacitor, can cancel off environment change under same mode through differentiated measurement. Such capacitive structure and design can enlarge at least one time more in sizes in comparison with that of single capacitive. Besides, an additional connection shall be made between electrode plates of such dual capacitors.
SUMMARY OF THE INVENTION
In order to solve these difficulties, a three-electrode capacitive pressure sensor structure and producing method with only a four-course optical masking is therefore developed which can integrate and produce dual capacitors into a pressure sensor cavity without increasing sensor size and complete dual capacitors requirement of differentiated measurement circuitry. Meanwhile, existence of the third electrode not only achieves planar connection production but also enhance its pressure sensitivity.


REFERENCES:
patent: 5503285 (1996-04-01), Warren
patent: 5528452 (1996-06-01), Ko
patent: 5543349 (1996-08-01), Kurtz et al.
patent: 5792957 (1998-08-01), Luder et al.
patent: 5912499 (1999-06-01), Diem
patent: 6036872 (2000-03-01), Wood et al.

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