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US 5,870,351 AGranted
Broadband microfabriated ultrasonic transducer and method of fabrication
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorsIgal Ladabaum, Butrus Thomas Khuri-Yakub
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Abstract
A broadband microfabricated ultrasonic transducer which includes a plurality of resonant membranes of different sizes and/or shapes supported above a conductive substrate.
Claims16
A broadband microfabricated ultrasonic transducer comprising:
- a substrate;
- a plurality of resonant membranes of different sizes with each size selected for its resonant frequency supported spaced from the substrate by an insulating support;
- and means for applying voltages between said membranes and said substrate.
A transducer array comprising:
- a substrate;
- a plurality of ultrasonic transducers on said substrate, each of said transducers including a plurality of resonant membranes of different sizes with each size selected to resonate at a selected frequency or frequencies, said membranes each supported spaced from said substrate by an insulating support;
- and means for applying voltages between selected membranes and said substrate whereby to focus and/or scan the ultrasonic energy from said plurality of membranes.
A broadband microfabricated ultrasonic transducer comprising:
- a conductive semiconductor substrate;
- a plurality of silicon nitride membranes of different sizes with each size selected for its resonant frequency, said membranes supported spaced from said substrate at their edges by an insulating support;
- and a conductive film formed on the surface of said membranes whereby a voltage can be applied between said membranes and said conductive semiconductor substrate.
The method of forming a broadband ultrasonic transducer which comprises the steps of:
- selecting a semiconductor conductive substrate forming a thin sacrificial insulating layer on one surface of said substrate;
- forming a thin silicon nitride layer on the surface of said insulating layer;
- forming a number of etchant access holes in said silicon nitride layer, said holes being closely spaced and arranged in patterns each including a plurality of spaced access holes;
- etching the sacrificial insulating layer through said access holes for a period of time which etches away the sacrificial material layer to form a membrane at each pattern of holes.
1 more element
Dependencies are inferred from the claim text.