Forming an Annular Array from 2D Capacitive Micromachined Ultrasonic Transducer (CMUT) Array Elements by Using a Metal Redistribution Layer

Different array geometries are desired for a variety of applications in diagnostic imaging as well as therapeutic interventions. One of the advantages of CMUT technology is the ability to develop transducers with complex geometries for diverse applications. In this paper, using a sacrificial release-based fabrication process, we implemented 8-concentric rings to form an annular array by connecting elements in a 32×32 2D CMUT array canvas. The 32×32-element 2D arrays were developed on a glass substrate to form the 2D array canvas, and with an additional metal layer (Metal-3 layer), we formed an 8-element annular array. Preliminary results show the successful development of the fabrication process. This concept offers the advantages of developing different CMUT geometries on a glass substrate by using a 2D CMUT array canvas.