Patent ID: 11872591
Assignee: STMICROELECTRONICS S.R.L.
Field: Chemical engineering (Chemistry)
Classification: CPC B  G | IPC B  G

Claim 13:
14. A method, comprising:
forming at least one micro-machined ultrasonic transducer, wherein the at least one micro-machined ultrasonic transducer is designed with a predefined resonance frequency, wherein the forming of the at least one micro-machined ultrasonic transducer includes:
forming a membrane element on a substrate, wherein the membrane element is suspended in a flexible manner over the substrate, wherein the membrane element is configured to transmit or receive ultrasonic waves, wherein, during transmission or reception of ultrasonic waves, the membrane element oscillates, about an equilibrium position, at a resonance frequency, wherein the equilibrium position of the membrane element is variable according to a biasing electric signal applied to the membrane element; and
forming a cap structure that overlies the membrane element, wherein the cap structure forms a cavity between the cap structure and the membrane element, wherein a volume of the cavity is variable according to the equilibrium position of the membrane element, wherein the cap structure includes an opening configured to input or output the ultrasonic waves into or from the cavity, wherein the cap structure and the membrane element act as tunable Helmholtz resonator in which the resonance frequency is variable according to the volume of the cavity; and

applying the biasing electric signal to the membrane element of the at least one micro-machined ultrasonic transducer to change the volume of the cavity and thereby setting the resonance frequency at which the membrane element oscillates to a target resonance frequency.