Electrostatic Comb Driver Actuator/Transducer and Fabrication of the Same
AssigneeKolo Technologies, Inc.
InventorYongli Huang
Life of this patent
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Abstract
An electrostatic actuator/transducer has a comb driver and can be adapted for a variety of applications, particularly as a capacitive micromachined ultrasonic transducer. The comb driver has two electrodes each connected to a set of comb fingers. The two sets of comb fingers interdigitate with each other, and in one embodiment each has a saw-toothed shape. One electrode is connected to a spring structure and movable along a vertical direction to engage and disengage the two sets of comb fingers. The movable portion is adapted to perform an actuation function and/or a sense of function. Fabrication methods for making the electrostatic actuator/transducer are also disclosed.
Claims24
A micromachined ultrasonic transducer comprising:
- a base portion having a first electrode including a first plurality of comb fingers;
- and
- an upper portion having a second electrode, the second electrode including a second plurality of comb fingers interdigitatedly engaging with the first plurality of comb fingers, wherein the second electrode is connected to a spring structure and movable along a z-direction to engage and disengage the second plurality of comb fingers and the first plurality of the comb fingers, and the upper portion is adapted to interface with a medium to transmit and/or receive an ultrasonic signal.
An electrostatic actuator/transducer comprising:
- a base portion having a first electrode including a first saw-tooth shaped comb finger with a first skewed side at a first skew angle relative to a z-direction;
- and
- an upper portion having a second electrode including a second saw-tooth shaped comb finger with a second skewed side at a second skew angle relative to the z-direction facing the first skewed side of the first saw-tooth shaped comb fingers, wherein the second electrode is connected to a spring structure and movable along the z-direction to engage and disengage the second comb finger and the first comb finger, and the upper portion is adapted to perform an actuation function and/or a sensor function.
A method for fabricating an electrostatic actuator/transducer, the method comprising:
- providing a first wafer, a second wafer and a third wafer;
- forming a first comb finger anchor on the first wafer;
- forming a second comb finger anchor on the second wafer;
- placing the third wafer over the first comb finger anchor on the first wafer;
- forming a first set of comb fingers and a second set of comb fingers in the third wafer, the first set of comb fingers and the second set of comb fingers interdigitating with each other, and the first set of comb fingers being connected to the first comb finger anchor;
- placing the second wafer over the first set of comb fingers and the second set of comb fingers such that the second comb finger anchor connects to the second set of comb fingers;
- and
- forming a spring layer from the first wafer, the spring layer supporting the first comb finger anchor, and being further connected to the second wafer through spring anchors to form a spring structure, such that the spring layer and the first set of comb fingers are movable in relation to the second set of comb fingers.
A method for fabricating an electrostatic actuator/transducer, the method comprising:
- providing a first wafer and a second wafer;
- forming a first comb finger anchor on the first wafer;
- placing the second wafer over the first comb finger anchor on the first wafer;
- forming a first set of comb fingers and a second set of comb fingers in the second wafer, the first set of comb fingers and the second set of comb fingers interdigitating with each other, and the first set of comb fingers being connected to the first comb finger anchor;
- placing a sacrificial material over the first set of comb fingers and the second set of comb fingers;
- forming openings through the sacrificial material to expose the second set of comb fingers;
- depositing a membrane material over the sacrificial material and the openings;
- and
- removing the sacrificial material, such that the membrane material deposited in the openings forms a second comb finger anchor connected to the second set of comb fingers, and membrane material deposited over the sacrificial material forms a membrane which is anchored to the second wafer through membrane anchors formed thereon, wherein the membrane and the second set of comb fingers are movable in relation to the first set of comb fingers.
A method for fabricating an electrostatic actuator/transducer, the method comprising:
- providing a substrate wafer having a top surface;
- forming a first set of comb fingers defined by a plurality of trenches formed in the substrate wafer through the top surface;
- depositing a sacrificial material over surfaces of the plurality of trenches and the top surface of the substrate wafer;
- depositing a membrane material over the sacrificial material and in the plurality of trenches;
- and
- removing the sacrificial material, such that the membrane material deposited in the plurality of trenches forms a second set of comb fingers interdigitating with the first set of comb fingers, and the membrane material deposited over the sacrificial material on the top surface of the substrate wafer forms a membrane which is suspended from the top surface of the substrate wafer and anchored to the substrate wafer through membrane anchors formed thereon, wherein the membrane and the second set of comb fingers are movable in relation to the first set of comb fingers.
Dependencies are inferred from the claim text.