Huang Yongli, Haeggström Edward, Bayram Baris, Zhuang Xuefeng, Ergun Arif Sanli, Cheng Ching-Hsiang, Khuri-Yakub Butrus T
Kolo Technologies, Inc., San Jose, CA 95135, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2006 Oct;53(10):1918-33. doi: 10.1109/tuffc.2006.125.
We report experimental results from a comparative study on collapsed region and conventional region operation of capacitive micromachined ultrasonic transducers (CMUTs) fabricated with a wafer bonding technique. Using ultrasonic pulse-echo and pitch-catch measurements, we characterized single elements of 1-D CMUT arrays operating in oil. The experimental results from this study agreed with the simulation results: a CMUT operating in the collapsed region produced a higher maximum output pressure than a CMUT operated in the conventional region at 90% of its collapse voltage (3 kPa/V vs. 16.1 kPa/V at 2.3 MHz). While the pulse-echo fractional bandwidth (126%) was higher in the collapsed region operation than in the conventional operation (117%), the pulse-echo amplitude in collapsed region operation was 11 dB higher than in conventional region operation. Furthermore, within the range of tested bias voltages, the output pressure monotonously increased with increased bias during collapsed region operation. It was also found that in the conventional mode, short AC pulses (larger than the collapse voltage) could be applied without collapsing the membranes. Finally, while no significant difference was observed in reflectivity of the CMUT face between the two regions of operation, hysteretic behavior of the devices was identified in the collapsed region operation.
我们报告了一项关于采用晶圆键合技术制造的电容式微机械超声换能器（CMUT）的坍塌区域和传统区域操作的对比研究的实验结果。通过超声脉冲回波和间距-捕获测量，我们对在油中工作的一维CMUT阵列的单个元件进行了表征。本研究的实验结果与模拟结果一致：在坍塌区域工作的CMUT在其坍塌电压的90%（2.3 MHz时为3 kPa/V对16.1 kPa/V）下产生的最大输出压力高于在传统区域工作的CMUT。虽然坍塌区域操作中的脉冲回波分数带宽（126%）高于传统操作（117%），但坍塌区域操作中的脉冲回波幅度比传统区域操作高11 dB。此外，在测试的偏置电压范围内，坍塌区域操作期间输出压力随偏置增加而单调增加。还发现，在传统模式下，可以施加短交流脉冲（大于坍塌电压）而不会使膜坍塌。最后，虽然在两个操作区域之间未观察到CMUT表面反射率的显著差异，但在坍塌区域操作中识别出了器件的滞后行为。
