title: 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.
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Chienliu
authors.initials: C
authors.lastname: Chang
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Moini
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Amin
authors.initials: A
authors.lastname: Nikoozadeh
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Ali Fatih
authors.initials: AF
authors.lastname: Sarioglu
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Apte
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhuang
authors.affiliation: Edward L Ginzton Laboratory, Center for Nanoscale Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Butrus T
authors.initials: BT
authors.lastname: Khuri-Yakub
keywords: bonding; capacitive micromachined ultrasonic transducer (CMUT); deep reactive ion etching (DRIE); ring arrays; singulation; tether; ultrasound imaging