Capacitive micromachined ultrasound transducer and methods of making the same

Abstract

A method of making a capacitive micromachined ultrasound transducer cell is provided. The method includes providing a carrier substrate, where the carrier substrate comprises glass. The step of providing the glass substrate may include forming vias in the glass substrate. Further, the method includes providing a membrane such that at least one of the carrier substrate, or the membrane comprises support posts, where the support posts are configured to define a cavity depth. The method further includes bonding the membrane to the carrier substrate by using the support posts, where the carrier substrate, the membrane and the support posts define an acoustic cavity.

Description

technical field [0001] The present invention relates generally to the field of diagnostic imaging and, more particularly, to capacitive micromachined ultrasound transducers (cMUTs) and methods for their manufacture. Background technique [0002] A transducer is a device that converts an input signal of one form into an output signal of another form. Commonly used transducers include light sensors, thermal sensors, and acoustic sensors. An example of an acoustic sensor is an ultrasound transducer, which can be used in medical imaging, non-destructive assessment, and other applications. [0003] Currently, one form of ultrasound transducer is the capacitive micromachined ultrasound transducer (cMUT). A CMUT cell generally includes a substrate, a bottom electrode coupled to the substrate, a diaphragm suspended above the substrate by pillars, and a metallization layer that functions as the top electrode. The bottom electrode, diaphragm and top electrode define the vertical ex...

AI Technical Summary

Problems solved by technology

If there is a mismatch in the coefficients of thermal expansion (CTE) of the various layers of the cMUT cell, such high temperature processing will tend to cause substrate distortion and film peeling, reducing device yield

In addition to low device yield, the thermal stress generated at the interface of each layer will change the boundary conditions of the diaphragm, making the diaphragm design (such as resonant frequency and collapsed voltage) unpredictable

Some methods such as high-temperature annealing must be used to mitigate the above-mentioned high-temperature induced effects, but these processes require additional steps

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