MEMS压电超声换能器二维阵列的制备方法

针对超声换能器阵列中阵元密度难以提升和工艺重复性差等问题,提出了一种基于硅-硅键合技术的MEMS压电超声换能器二维阵列的制备方法,并采用该方法制备了阵元间距小至150μm的密排二维换能器阵列。阵列中每个声学单元均为由上电极、压电材料(PZT)层、下电极和支撑层组成的多层膜结构,并通过其弯曲振动模式实现超声波的发射和接收。制备样品的测试结果表明,采用该方法制作MEMS压电超声换能器阵列,具有阵元间距小、工艺流程可靠、成品率高、一致性好、工作频率(2.45MHz)与设计值(2.5MHz)的吻合度高等优点,适用于医学成像等高频超声成像系统。     

Preparation and Characteristics of Nanoscale Diamond-Like Carbon Films for Resistive Memory Applications

We propose diamond-like carbon （DLC） as the resistance change material for nonvolatile memory applications. Nanosecale DLC films are prepared by filtered cathodic vacuum arc technique and integrated to W//DLC/W structure devices. The deposited DLC film has a thickness of about 20nm and high spa fraction content. Reversible bistable resistive switching from a high resistance state to a low resistance state, and vice versa, is observed under appropriate unipolar stimulation pulses. High resistance switching ratio （larger than a thousand times） and low level of switching power （about 11 μW） are demonstrated. We propose that the mechanism of the repetitive resistive switching is the growth and breakage of conductive sp2-like filaments in the predominantly sp3-type insulating carbon upon applications of voltage pulses, which is consistent with the experimental results.