Chen Jun, Fei Chunlong, Zhao Jianxin, Quan Yi, Wang Yecheng, Jiang Zhishui, Wen Li
School of Microelectronics, Xidian University, Xi'an 710071, China.
Guangdong JC Technological Innovation Electronics Co., Ltd., Zhaoqing 526000, China.
Micromachines (Basel). 2023 Jan 14;14(1):213. doi: 10.3390/mi14010213.
Acoustic microscopes and acoustic tweezers have great value in the application of microparticle manipulation, biomedical research and non-destructive testing. Ultrahigh frequency (UHF) ultrasonic transducers act as the key component in acoustic microscopes, and acoustic tweezers and acoustic lenses are essential parts of UHF ultrasonic transducers. Therefore, the preparation of acoustic lenses is crucial. Silicon is a suitable material for preparing acoustic lenses because of its high acoustic velocity, low acoustic attenuation and excellent machinability. In previous research, silicon lenses were mainly prepared by etching. However, etching has some drawbacks. The etching of large sizes is complex, time-consuming and expensive. Furthermore, vertical etching is preferred to spherical etching. Thus, a new method of ultra-precision machining was introduced to prepare silicon lenses. In this paper, silicon lenses with an aperture of 892 μm and a depth of 252 μm were prepared. Then, UHF ultrasonic transducers with a center frequency of 157 MHz and a -6-dB bandwidth of 52% were successfully prepared based on silicon lenses. The focal distance of the transducers was 736 μm and the F-number was about 0.82. The transducers had a lateral resolution of 11 μm and could distinguish the 13 μm slots on silicon wafers clearly.
声学显微镜和声学镊子在微粒操控、生物医学研究及无损检测应用中具有重要价值。超高频（UHF）超声换能器是声学显微镜的关键部件，而声学镊子和声学透镜是UHF超声换能器的重要组成部分。因此，声学透镜的制备至关重要。硅因其高声速、低声衰减及优良的可加工性，是制备声学透镜的合适材料。在以往研究中，硅透镜主要通过蚀刻制备。然而，蚀刻存在一些缺点。大尺寸蚀刻复杂、耗时且成本高。此外，垂直蚀刻优于球面蚀刻。因此，引入了一种超精密加工新方法来制备硅透镜。本文制备了孔径为892μm、深度为252μm的硅透镜。然后，基于硅透镜成功制备了中心频率为157MHz、-6dB带宽为52%的UHF超声换能器。换能器的焦距为736μm，F数约为0.82。该换能器横向分辨率为11μm，能清晰分辨硅片上13μm的狭缝。
