Piezoelectric MEMS microphone
First Claim
1. A piezoelectric MEMS device comprising:
- a substrate comprising an opening in the substrate;
a suspension element;
a multi-layer, piezoelectric microphone diaphragm configured to respond to a pressure differential at one or more acoustic frequencies, with the pressure differential being between a top portion of the multi-layer, piezoelectric microphone diaphragm and a bottom portion of the multi-layer, piezoelectric microphone diaphragm, with the multi-layer, piezoelectric microphone diaphragm being suspended above the opening in the substrate via the suspension element, the multi-layer, piezoelectric microphone diaphragm comprising at least three layers including a first electrode layer, a piezoelectric layer deposited over the first electrode layer, and a second electrode layer deposited over the piezoelectric layer, with the first electrode layer comprising an upper central electrode and an upper outer ring electrode, with the second electrode layer comprising a lower central electrode and a lower outer ring electrode;
wherein a first end of the suspension element is affixed to the substrate and wherein a second end of the suspension element is affixed to a first portion of the multi-layer, piezoelectric microphone diaphragm at or adjacent the lower outer ring electrode; and
a removable connection between the substrate and attached to the multi-layer, piezoelectric microphone diaphragm at one or more second re-attached portions of the lower outer ring electrode.
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Accused Products
Abstract
A piezoelectric MEMS microphone comprising a multi-layer sensor that includes at least one piezoelectric layer between two electrode layers, with the sensor being dimensioned such that it provides a near maximized ratio of output energy to sensor area, as determined by an optimization parameter that accounts for input pressure, bandwidth, and characteristics of the piezoelectric and electrode materials. The sensor can be formed from single or stacked cantilevered beams separated from each other by a small gap, or can be a stress-relieved diaphragm that is formed by deposition onto a silicon substrate, with the diaphragm then being stress relieved by substantial detachment of the diaphragm from the substrate, and then followed by reattachment of the now stress relieved diaphragm.
39 Citations
22 Claims
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1. A piezoelectric MEMS device comprising:
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a substrate comprising an opening in the substrate; a suspension element; a multi-layer, piezoelectric microphone diaphragm configured to respond to a pressure differential at one or more acoustic frequencies, with the pressure differential being between a top portion of the multi-layer, piezoelectric microphone diaphragm and a bottom portion of the multi-layer, piezoelectric microphone diaphragm, with the multi-layer, piezoelectric microphone diaphragm being suspended above the opening in the substrate via the suspension element, the multi-layer, piezoelectric microphone diaphragm comprising at least three layers including a first electrode layer, a piezoelectric layer deposited over the first electrode layer, and a second electrode layer deposited over the piezoelectric layer, with the first electrode layer comprising an upper central electrode and an upper outer ring electrode, with the second electrode layer comprising a lower central electrode and a lower outer ring electrode; wherein a first end of the suspension element is affixed to the substrate and wherein a second end of the suspension element is affixed to a first portion of the multi-layer, piezoelectric microphone diaphragm at or adjacent the lower outer ring electrode; and a removable connection between the substrate and attached to the multi-layer, piezoelectric microphone diaphragm at one or more second re-attached portions of the lower outer ring electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11, 12, 18, 19, 20, 21, 22)
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8. A method of manufacturing a piezoelectric MEMS microphone, comprising:
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depositing, onto a substrate, alternating layers of electrode and piezoelectric materials to form a piezoelectric diaphragm; releasing a portion of the deposited layers of the piezoelectric diaphragm from the substrate; and reattaching the released portion of the piezoelectric diaphragm to the substrate about a periphery of the substrate such that the piezoelectric diaphragm has a first peripheral portion that is attached to the substrate as a direct deposition of at least one of the deposited layers onto the substrate, and has a second peripheral portion attached to the substrate by reattachment of the second peripheral portion onto the substrate. - View Dependent Claims (9)
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13. A piezoelectric MEMS device comprising:
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a substrate; a suspension element; and a multi-layer, piezoelectric microphone diaphragm suspended above the substrate and configured to respond to a pressure differential across the multi-layer, piezoelectric microphone diaphragm at one or more acoustic frequencies, the multi-layer, piezoelectric microphone diaphragm being configured to resist airflow through the piezoelectric MEMS device at one or more frequencies by being suspended over the substrate via the suspension element, with the multi-layer, piezoelectric microphone diaphragm comprising at least three layers that include a first electrode layer, a piezoelectric layer deposited over the first electrode layer, and a second electrode layer deposited over the piezoelectric layer, with the first electrode layer comprising an upper central electrode and an upper outer ring electrode, with the second electrode layer comprising a lower central electrode and a lower outer ring electrode; wherein a first end of the suspension element is affixed to the substrate and wherein a second end of the suspension element is affixed to a first portion of the multi-layer, piezoelectric microphone diaphragm at or adjacent the lower outer ring electrode; and a removable connection between the substrate and attached to the multi-layer, piezoelectric microphone diaphragm at one or more second re-attached portions of the lower outer ring electrode. - View Dependent Claims (14, 15, 16, 17)
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Specification