Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers

Abstract

Singulation of MEMS is a critical step in the transition from wafer-level to die-level devices. As is the case for capacitive micromachined ultrasound transducer (CMUT) ring arrays, an ideal singulation must protect the fragile membranes from the processing environment while maintaining a ring array geometry. The singulation process presented in this paper involves bonding a trench-patterned CMUT wafer onto a support wafer, deep reactive ion etching (DRIE) of the trenches, separating the CMUT wafer from the support wafer and de-tethering the CMUT device from the CMUT wafer. The CMUT arrays fabricated and singulated in this process were ring-shaped arrays, with inner and outer diameters of 5 mm and 10 mm, respectively. The fabricated CMUT ring arrays demonstrate the ability of this method to successfully and safely singulate the ring arrays and is applicable to any arbitrary 2D shaped MEMS device with uspended microstructures, taking advantage of the inherent planar attributes of DRIE.

Underwater Imaging Using a 1 × 16 CMUT Linear Array

“…Ultrasound imaging has played an important role in various areas, such as medical diagnosis, medical treatment, nondestructive testing, and ultrasound microscopy [ 1 , 2 , 3 ]. The ultrasonic transducer is the core component of ultrasound imaging, and currently piezoelectric micro-machined ultrasonic transducers (PMUTs) based on the piezoelectric effect are widely used [ 4 , 5 ]. However, PMUT performance in underwater and medical applications is limited by material properties and impedance matching issues [ 2 , 6 , 7 ].…”

Design and fabrication of high frequency BNT film based linear array transducer

“…In the practical application, since the diameter of the catheter in intravascular ultrasound (IVUS) system is considerably small (usually less than 1 mm), it is challenging to fabricate such miniaturized transducers with high center frequency using mechanical dicing and filling method [11][12][13][14]. Microelectromechanical systems (MEMS) techniques, on the other hand, give a new way such as photolithography or deep reactive techniques to fabricate such miniaturized devices [15]. Generally, ICP reactive ion etching has been employed extensively in the fabrication of high frequency transducers.…”