Methods for Fabricating Micro-Electro-Mechanical Devices
First Claim
1. A method for fabricating a micro-electro-mechanical device having a movable mechanical part to transform energy, the method comprising the steps of:
- providing a substrate wafer, a middle spring layer and a top plate layer;
forming at least one cavity on either a front side of a substrate wafer or a bottom side of the middle spring layer, wherein each cavity has at least one sidewall;
forming at least one connector of a desired height on either a top side of a middle spring layer or a bottom side of a top plate layer;
forming or effectuating a transducing member on the top plate layer; and
joining the substrate wafer, the middle spring layer and the top plate layer such that the bottom side of the top plate layer faces the top side of the middle spring layer and a bottom side of the middle spring layer faces the front side of the substrate wafer, whereby the connector stands out from the middle spring layer to define a transducing space between the top plate layer and the middle spring layer, and the connector is horizontally distanced from the sidewall by a sufficient length to define a cantilever anchored at the sidewall with an exerting end at the connector, wherein the cantilever and the cavity enable a vertical displacement of the connector to transport the top plate layer substantially vertically with a piston-like motion to change the transducing space and activate the transducing member.
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Abstract
A method for fabricating a micro-electro-mechanical device (such as a cMUT) is disclosed. The method combines a substrate, a middle spring layer and a top plate using wafer bonding technology or sacrificial technology. A cavity is formed on either the top of the substrate or the bottom of the middle spring layer. A connector is formed on either the top of the middle spring layer or the bottom of the top plate. Upon joining the three layers, the connector defines a transducing space between the top plate and the middle spring layer. The connector is horizontally distanced from the sidewall to define a cantilever anchored at the sidewall. The cantilever and the cavity allow a vertical displacement of the connector, which transports the top wafer in a piston-like motion to change the transducing space. Multiple device elements can be made on the same substrate.
242 Citations
62 Claims
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1. A method for fabricating a micro-electro-mechanical device having a movable mechanical part to transform energy, the method comprising the steps of:
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providing a substrate wafer, a middle spring layer and a top plate layer; forming at least one cavity on either a front side of a substrate wafer or a bottom side of the middle spring layer, wherein each cavity has at least one sidewall; forming at least one connector of a desired height on either a top side of a middle spring layer or a bottom side of a top plate layer; forming or effectuating a transducing member on the top plate layer; and joining the substrate wafer, the middle spring layer and the top plate layer such that the bottom side of the top plate layer faces the top side of the middle spring layer and a bottom side of the middle spring layer faces the front side of the substrate wafer, whereby the connector stands out from the middle spring layer to define a transducing space between the top plate layer and the middle spring layer, and the connector is horizontally distanced from the sidewall by a sufficient length to define a cantilever anchored at the sidewall with an exerting end at the connector, wherein the cantilever and the cavity enable a vertical displacement of the connector to transport the top plate layer substantially vertically with a piston-like motion to change the transducing space and activate the transducing member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46)
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40. The method of 38 wherein the connector is formed at a location directly above the post.
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47. A method for fabricating a micro-electro-mechanical device, such as a capacitance micromachined ultrasonic transducer (cMUT), which has a movable mechanical part to transform energy, the method comprising the steps of:
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providing a substrate wafer having a front side and a back side; depositing a first sacrificial layer on the front side of the substrate wafer; patterning the first sacrificial layer to form a first provisional cavity; depositing a first thin film material over the first sacrificial layer to fill the first provisional cavity and to further form a membrane layer covering a top surface of the first sacrificial layer; removing the first sacrificial layer to form a first cavity on top of the substrate wafer, wherein the first cavity is defined by at least one sidewall having a top surface, the sidewall being made of the first thin film material deposited in the first provisional cavity; forming at least one connector of a desired height on either a top side of the membrane layer or a bottom side of a top plate layer; and placing the top plate layer over the connector to define a transducing space between the top plate layer and the membrane layer, wherein the connector stands out from the membrane layer and is horizontally distanced from the sidewall of the first cavity by a sufficient length to define a cantilever anchored at the sidewall to allow a vertical displacement of the connector, and whereby the vertical displacement of the connector transports the top plate layer substantially vertically with a piston-like motion, thus changing the transducing space. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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Specification