Variable thickness diaphragm for a wideband robust piezoelectric micromachined ultrasonic transducer (PMUT)
AssigneeThe Regents of the University of California
InventorsBernhard Boser, David Horsley, Richard Przybyla, Ofer Rozen, Stefon Shelton
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Abstract
A diaphragm for a piezoelectric micromachined ultrasonic transducer (PMUT) is presented having resonance frequency and bandwidth characteristics which are decoupled from one another into independent variables. Portions of at least the piezoelectric material layer and backside electrode layer are removed in a selected pattern to form structures, such as ribs, in the diaphragm which retains stiffness while reducing overall mass. The patterned structure can be formed by additive, or subtractive, fabrication processes.
Claims35
An apparatus for ultrasonic device, the apparatus comprising:
- (a) at least one elastic layer;
- (b) at least one piezoelectric material layer mechanically coupled to the elastic layer;
- and
- (c) electrodes disposed in electrical contact with each side of the piezoelectric material;
- (d) wherein a combination of the elastic layer, piezoelectric material layer and electrodes, form an ultrasonic diaphragm;
- (e) wherein the diaphragm has a surface patterned with selective thinned areas through a combination of at least the piezoelectric material layer and the electrodes to vary the diaphragm thickness at specific locations to independently select mass and stiffness toward increasing bandwidth and reducing sensitivity to residual stress;
- and
- (f) wherein the elastic layer comprises an active piezoelectric material.
An apparatus for ultrasonic device, the apparatus comprising:
- (a) at least one elastic layer;
- (b) at least one piezoelectric material layer mechanically coupled to the elastic layer;
- and
- (c) electrodes disposed in electrical contact with each side of the piezoelectric material;
- (d) wherein a combination of the elastic layer, piezoelectric material layer and electrodes, form an ultrasonic diaphragm;
- (e) wherein the diaphragm has a surface patterned with selective thinned areas through a combination of at least the piezoelectric material layer and the electrodes to vary the diaphragm thickness at specific locations to independently select mass and stiffness toward increasing bandwidth and reducing sensitivity to residual stress;
- and
- (f) wherein the patterning of the diaphragm comprises material layer remnants of the diaphragm after open areas in the piezoelectric layer and the electrode have been removed.
An apparatus for ultrasonic device, the apparatus comprising:
- (a) at least one elastic layer;
- (b) at least one piezoelectric material layer mechanically coupled to the elastic layer;
- and
- (c) electrodes disposed in electrical contact with each side of the piezoelectric material;
- (d) wherein a combination of the elastic layer, piezoelectric material layer and electrodes, form an ultrasonic diaphragm;
- (e) wherein the diaphragm has a surface patterned with selective thinned areas through a combination of at least the piezoelectric material layer and the electrodes to vary the diaphragm thickness at specific locations to independently select mass and stiffness toward increasing bandwidth and reducing sensitivity to residual stress;
- and
- wherein the diaphragm is patterned with multiple ribs, and wherein each of the ribs tapers in an isosceles triangle shape or isosceles trapezoid shape.
Dependencies are inferred from the claim text.