Vibrating beam accelerometer and method for manufacturing the same
First Claim
1. An accelerometer comprising:
- a substrate comprising a semiconducting material and defining first and second opposite surfaces, the substrate having a frame and a proof mass suspended from the frame by one or more flexures;
first and second active layers of semiconducting material coupled to the first and second surfaces of the substrate, respectively, wherein the first active layer comprises a first vibratory force transducer and the second active layer comprises a second vibratory force transducer, said first and second vibratory force transducers are mechanically coupled to the proof mass and the frame for detecting a force applied to the proof mass;
an insulating layer between each active layer and the substrate to insulate the vibratory transducers from the substrate, anda circuit coupled to the vibratory force transducers for driving and sensing the vibratory force transducerwherein the vibratory force transducers each comprise first and second parallel beams each having a first end portion fixed to the proof mass, a second end portion fixed to the frame and a resonating portion between said first and second end portions, and first and second electrodes positioned adjacent to and laterally spaced from the first and second beams,wherein the beams each have one or more fingers extending laterally outward from the beams, the electrodes each comprising one or more fingers projecting laterally inward toward the beams and intermeshed with the beam fingers.
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Accused Products
Abstract
An accelerometer formed from a semiconducting substrate and first and second active layers coupled to the opposite surfaces of the substrate. The substrate has a frame and a proof mass suspended from the frame by one or more flexures for rotation about an input axis in response to an applied force. The active layers each include a vibratory force transducer mechanically coupled to the proof mass for detecting a force applied to the proof mass. With this configuration, the transducers are located on either side of the substrate, which improves the differential design symmetry of the force detecting apparatus. This reduces the common mode non-linear response characteristics of the accelerometer, particularly in high dynamics applications, where high performance is required.
58 Citations
14 Claims
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1. An accelerometer comprising:
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a substrate comprising a semiconducting material and defining first and second opposite surfaces, the substrate having a frame and a proof mass suspended from the frame by one or more flexures; first and second active layers of semiconducting material coupled to the first and second surfaces of the substrate, respectively, wherein the first active layer comprises a first vibratory force transducer and the second active layer comprises a second vibratory force transducer, said first and second vibratory force transducers are mechanically coupled to the proof mass and the frame for detecting a force applied to the proof mass; an insulating layer between each active layer and the substrate to insulate the vibratory transducers from the substrate, and a circuit coupled to the vibratory force transducers for driving and sensing the vibratory force transducer wherein the vibratory force transducers each comprise first and second parallel beams each having a first end portion fixed to the proof mass, a second end portion fixed to the frame and a resonating portion between said first and second end portions, and first and second electrodes positioned adjacent to and laterally spaced from the first and second beams, wherein the beams each have one or more fingers extending laterally outward from the beams, the electrodes each comprising one or more fingers projecting laterally inward toward the beams and intermeshed with the beam fingers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for making an accelerometer for detecting an applied force comprising:
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forming insulating layers on opposite surfaces of a semiconductor wafer; forming first and second active layers on the formed insulating layers on opposite surfaces of the semiconductor wafer; suspending a proof mass from a stationary frame on the semiconductor wafer, the proof mass having first and second opposite surfaces; forming a first vibratory force transducer in the first active layer; forming a second vibratory force transducer in the second active layer, wherein forming each of the first and second vibratory force transducers further comprises forming first and second parallel beams with a first end portion fixed to the proof mass, a second end portion fixed to the frame and a resonating portion between said first and second end portions and forming one or more fingers extending laterally outward from the beams; mechanically coupling the first vibratory force transducer to the frame and to the first opposite surface of the proof mass; mechanically coupling the second vibratory force transducer to the frame and to the second opposite surface of the proof mass; electrically coupling the first and second vibratory force transducers to a circuit adapted for driving and sensing the vibratory force transducer; and forming first and second electrodes adjacent to and laterally spaced from the first and second beams, wherein the electrodes are formed with one or more fingers protecting laterally inward toward the beams and intermeshed with the beam fingers; wherein the vibratory force transducers are each capable of detecting a force applied to the proof mass.
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Specification