Micromachined silicon potentiometer responsive to pressure
First Claim
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1. A force sensor having an elastic beam and comprising:
- a first surface and a second surface separated by a gap and each said surface being formed in a silicon substrate, the first surface capable of flexing in response to an external force, the second surface stationary relative to the first surface and acting as a deflection stop;
a resistor formed on one of the surfaces and having two terminals with a current path between the two terminals; and
an electrode on the other surface acting as a shunt for that portion of the resistor which comes into contact with said electrode, wherein one of the surfaces includes a central beam located on a diaphragm, said central beam being at least about four times thicker than adjacent portions of said diaphragm;
whereby when flexing of the first surface occurs, a resistance in the current path between said two terminals changes in response to said external force.
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Abstract
A silicon pressure chip operates in a two-wire resistive mode. A thin-film resistor located on a long silicon beam which is the thicker portion of a thin diaphragm is partially shorted out by a metallized deflection stop. The pressure response of the resistor is determined by the resistor layout.
51 Citations
9 Claims
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1. A force sensor having an elastic beam and comprising:
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a first surface and a second surface separated by a gap and each said surface being formed in a silicon substrate, the first surface capable of flexing in response to an external force, the second surface stationary relative to the first surface and acting as a deflection stop; a resistor formed on one of the surfaces and having two terminals with a current path between the two terminals; and an electrode on the other surface acting as a shunt for that portion of the resistor which comes into contact with said electrode, wherein one of the surfaces includes a central beam located on a diaphragm, said central beam being at least about four times thicker than adjacent portions of said diaphragm;
whereby when flexing of the first surface occurs, a resistance in the current path between said two terminals changes in response to said external force.
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2. A silicon pressure sensor having an elastic beam and comprising:
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a first silicon chip in which is formed a diaphragm capable of flexing in response to pressure changes; a second silicon chip separated by a gap from said diaphragm and bonded to said first chip; a resistor formed between two terminals on a surface of said first chip facing said gap wherein said diaphragm includes a beam portion clamped at both ends and located at a central portion of said diaphragm, and said beam portion being at least about four times thicker than a remainder of said diaphragm, said resistor being formed on a surface of said beam portion; and a conductive electrode formed on a surface of the second chip facing said gap; whereby, in response to pressure changes, the two surfaces make contact of a varying length and a resistance between said two terminals changes in response to pressure. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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Specification