A model study of capacitive micromachined ultrasonic transducers fabricated using atomic layer deposition process

In this paper, we present the model study of capacitive micromachined ultrasonic transducers (CMUTs) fabricated by atomic layer deposition (ALD) technology, which uses a self-limiting binary reaction process to produce ultra-thin membranes. Advantages of ALD include precise control of membrane thickness, lower cost due to a reduction in the number of fabrication steps, the potential to use a large variety of materials, and increased reliability due to the enhanced surface quality of the membranes. These capabilities promise fabrication of transducers with superior operating characteristics. However, no study has yet documented sensitivity and power requirements for CMUTs created using ALD. We present here a first-order mechanical and equivalent circuit analysis along with a fabrication process to create and characterize CMUTs using ALD. Simulation results show that these systems have the potential for excellent sensitivity and decreased power requirements. Work to test the fabricated elements is currently underway.