High aspect-ratio low noise multi-axis accelerometers
First Claim
1. A transducer with a high aspect ratio, comprising:
- a substrate;
a transducer structure mounted on a top surface of the substrate and extending upwardly from the top surface of the substrate, wherein the transducer structure is comprised of a cantilever beam integrally formed with a proof-mass, wherein the proof-mass extends from a top of the cantilever beam downwardly along one or more side surfaces of the cantilever beam towards the top surface of the substrate;
one or more sensing electrodes mounted to the top surface of the substrate and spatially separated from the transducer structure, wherein the one or more sensing electrodes are configured to measure a change in a gap formed between the one or more electrodes and the transducer structure, such that motion of the transducer structure causes a size of the gap to vary in a direction that is parallel with a longitudinal axis of the cantilever beam; and
one or more additional electrodes extending upwardly from the top surface of the substrate and arranged around a periphery of the transducer structure.
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Accused Products
Abstract
The design and fabrication of a multi-axis capacitive accelerometer is presented with sub-μg resolution based on CMOS-compatible fabrication technology that can provide large proof-mass, high-aspect ratio and a large sense electrode area within a smaller footprint that previous accelerometers. In some instances, the device footprint can be reduced by placing the sense electrodes near the top or bottom of the transducer structure such that motion of the transducer causes size of the sense gap to vary in a direction that is parallel with longitudinal axis of the support beam for the transducer structure. An extra mass can also be added to the top of the transducer structure to increase sensitivity.
31 Citations
19 Claims
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1. A transducer with a high aspect ratio, comprising:
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a substrate; a transducer structure mounted on a top surface of the substrate and extending upwardly from the top surface of the substrate, wherein the transducer structure is comprised of a cantilever beam integrally formed with a proof-mass, wherein the proof-mass extends from a top of the cantilever beam downwardly along one or more side surfaces of the cantilever beam towards the top surface of the substrate; one or more sensing electrodes mounted to the top surface of the substrate and spatially separated from the transducer structure, wherein the one or more sensing electrodes are configured to measure a change in a gap formed between the one or more electrodes and the transducer structure, such that motion of the transducer structure causes a size of the gap to vary in a direction that is parallel with a longitudinal axis of the cantilever beam; and one or more additional electrodes extending upwardly from the top surface of the substrate and arranged around a periphery of the transducer structure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A transducer with a high aspect ratio, comprising:
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a substrate; a transducer structure mounted on a top surface of the substrate and extending upwardly from the top surface of the substrate, wherein the transducer structure is comprised of a support beam; one or more stationary electrodes extending upwardly from the top surface of the substrate and arranged around a periphery of the transducer structure, wherein the one or more stationary electrodes are spatially separated from the transducer structure by a channel that extends along an entire height of the transducer structure; and one or more sensing electrodes formed on a top surface of the transducer structure, where the one or more sensing electrodes extend radially outward from the transducer structure and overhang at least a portion of a top surface of the one or more stationary electrodes, thereby defining a gap between the one or more sensing electrodes and the top surface of the one or more stationary electrodes. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A transducer with a high aspect ratio, comprising:
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a substrate; a transducer structure mounted on a top surface of the substrate and extending upwardly from the top surface of the substrate, wherein the transducer structure is comprised of a support beam; one or more stationary electrodes extending upwardly from the top surface of the substrate and arranged around periphery of the transducer structure, wherein the one or more stationary electrodes are spatially separated from the transducer structure by a channel that extends along an entire height of the transducer structure; and one or more sensing electrodes formed on a top surface of the one or more stationary electrodes, where the one or more sensing electrodes extend radially inward from the one or more stationary electrodes and overhang at least a portion of a top surface of the transducer structure, thereby defining a gap between the one or more sensing electrodes and the top surface of the transducer structure.
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15. A transducer with a high aspect ratio, comprising:
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a substrate; a transducer structure mounted on a top surface of the substrate and extending upwardly from the top surface of the substrate, wherein the transducer structure is comprised of a support beam integrally formed with a proof-mass; one or more stationary electrodes extending upwardly from the top surface of the substrate and arranged around periphery of the transducer structure, wherein the one or more stationary electrodes are spatially separated from the transducer structure by a channel that extends along an entire height of the transducer structure, such that a width of the channel proximate to a top of the transducer structure differs from a width of the channel proximate to a bottom of the transducer structure; and an extra mass deposited on the top surface of the transducer structure, where material comprising the extra mass has a higher density than material comprising the transducer structure. - View Dependent Claims (16, 17, 18, 19)
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Specification