MEMS螺线管型电感器正负胶结合的加工工艺

MEMS螺线管型电感器由于具有很多优点，其用途或潜在用途相当广泛 。为了获得高质量的MEMS螺线管型电感器，在充分利用SU-8特点的基础上，结合使用正胶AZ-4000系列和负胶SU-8系列，新开发了UV-LIGA多层微加工工艺，它主要包括：在基片上溅射Cr/Cu作为电镀种子层，涂布正胶，紫外光刻得到电镀模具，电镀Cu和FeNi分别得到线圈的下层、中层和上层以及铁芯；在完成下层和中层后，分别进行一次负胶工艺以形成电绝缘层和后续结构的支撑平台，即涂布负胶覆盖较下层结构，光刻开通往较上一层的通道并使SU-8聚合、交联以满足性能要求。实验表明该工艺是可行和实用的。它除了可用于螺线管电感器的加工，还可以用来加工其它三维结构的MEMS器件。     

Research on Microelectromagnetic Relays

A new microelectromagnetic relay is presented and fabricated based on micromachining technology, aiming at the miniaturization and high manufacturing efficiency of electromagnetic relays. This microrelay is composed of a lower magnetic circuit, a planar exciting coil, and an upper magnetic armature. A complete magnetic circuit is composed, and the “ON” and “OFF” states are controlled by the current of the exciting coil. The dimension of this microrelay is 5 mm × 5 mm × 0.4–mm. The fabrication process mainly includes lithography, sputtering, electroplating, etching, sacrifice-layer technology, etc. Electromagnetic force is calculated theoretically. The calculation results are used for the optimization design of the armature and the number of turns of the exciting coil. A microelectromagnetic relay is fabricated and the initial test results are given. The resistance of the exciting coil is about 300 Ω. The switch-on state resistance is about 1.7 Ω at an exciting current of about 50–mA. Translated from Journal of Beijing University of Technology, 2004, 30(2) (in Chinese)     

Micrometer-scale machining: tool fabrication and initial results

Conventional milling techniques scaled to ultrasmall dimensions have been used to machine polymethyl methacrylate (PMMA) with micrometer-sized milling tools. The object of this work is to achieve machining of a common material over dimensions exceeding 1 mm while holding submicrometer tolerances and micrometer size features. Fabricating the milling tools themselves was also an object of the study. A tool geometry for nominal 25 micrometer diameter cutting tools was found that cuts PMMA with submicrometer tolerances over trench lengths of 2 mm. The tool shape is a simple planar facet cut by focused ion beam milling on ground and polished 25 micrometer diameter steel tool blanks. Pairs of trenches 24 micrometers wide, 26 micrometers deep, 2.3 mm long, with a 14 micrometer separation were milled under various machining conditions. The results indicate that the limits of the machining process in terms of speed, pattern complexity, and tolerances have not been approached. This is the first demonstration of a generic method for microtool making by focused ion beam machining combined with ultraprecision numerically controlled milling. The method is shown to be capable of producing structures and geometries that are considered inaccessible by conventional materials removal techniques, and generally regarded as applications for deep X-ray lithography.     

微细加工技术在微光开关制造中的应用

微光开关是新一代全光通信网络中的关键器件。利用微细加工技术制造微光开关具有很多突出的优点，受到了广泛的研究。总结了几种典型的微光开关制造中运用的微细加工技术，并介绍了它们的应用和相应的特点。     

Recent Progress in Neural Probes Using Silicon MEMS Technology

Extracellular recordings from the brain are the basis for the fundamental understanding of the complex interaction of electrical signals in neural information transfer. Going beyond wire electrodes and bundles of electrode wires such as tetrodes, multielectrode arrays based on silicon technologies are receiving growing attention, since they enable a pronounced increase in the number of recording sites per probe shaft. In this paper, recent innovations contributed by the authors to the development of probe arrays based on microelectromechanical system (MEMS) technologies within the EU‐funded research project NeuroProbes are described. The resulting structures include passive electrode arrays based on single‐shaft and four‐shaft probes comprising nine planar electrodes per shaft with lengths of up to 8 mm. Further, active probe arrays with complementary metal–oxide–semiconductor (CMOS) circuitry integrated on the probe shaft, enabling the arrangement of 188 electrodes in two columns along a 4‐mm‐long probe shaft with an electrode pitch of only 40 µm, are described. These active probes were developed for an electronic depth control. Further, the paper reports assembly technologies for combining the probe arrays with highly flexible ribbon cables. Applications of the probes in in vivo experiments are summarized. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

微型压力传感器薄膜凹槽的制造技术

压力薄膜及凹槽是微型压力传感器中的关键部分,其制造方法主要有两种:1)对体硅进行选择性移除的体加工;2)对表面淀积的牺牲层进行选择性移除的表面加工.针对薄膜凹槽的制作,介绍了几种典型的体加工和表面加工技术,分析了其中的某些关键步骤及其优缺点,为薄膜凹槽的制作提供指导性意见.     

Fabrication of a MEMS inertia switch on quartz substrate and evaluation of its threshold acceleration

Based on surface micromachining technology, a micro-electro-mechanical system (MEMS) inertia switch with single sensitive direction and reverse impact protection has been designed and fabricated on quartz substrate. The switch is laterally driven (i.e. its sensitive direction is parallel to the substrate plane), in which the conjoined snake springs are used to fix and suspend the movable electrode (i.e. proof mass), and blocks are used to protect the device against reverse impact. The relationship between the threshold acceleration a_th and the intrinsic frequency has been investigated by theoretical analysis and finite element simulation, respectively, based on which the geometrical parameters of the switch can be decided to meet design objective. The proof mass thickness H was chosen as a variable, as the micro-fabrication of the device was carried out by low-cost and convenient multi-layer electroplating technology, where H can be easily adjusted while the plane geometry remains the same. The stress distribution of the switch in the contact process was also simulated. Packaged micro-switches were tested by dropping hammer experiments, which generated half-sine wave acceleration as in reality. The measured threshold acceleration generally met the design objective of 60g and the response time was in the order of 10⁻⁴ s, both agreed with the simulated results.     

High sensitivity nanostructure incorporated interdigital silicon based capacitive accelerometer

Interdigital structures are realized on silicon substrates with high sensitivity to acceleration. The process employs a combination of anisotropic back-side micromachining with front-side vertical deep reactive ion etching of silicon. The incorporation of silicon-based nano-structures on the vertical planes of fingers leads to a significant increase in the capacitance of the device from 0.45 for simple planes to 40 pF for the nano-structured planes. Such structures show high sensitivity to inclination and accelerations, which could be due to field emission of electrons from nano-metric features. Around 8% change in the capacitance is observed upon a tilting sensor from 0° to 90° angle, which makes it proper for possible use as an earthquake sensor. A preliminary model for the capacitance and its dependence on the measurement voltage is presented.     

A study of the characteristics for electrochemical micromachining with ultrashort voltage pulses

Electrochemical micromachining (EMM) has traditionally been used in highly specialized fields, such as those of the aerospace and defense industries. It is now increasingly being applied in other industries, where parts with difficult-to-cut material, complex geometry and tribology, and devices of microscopic-scale are required. EMM, which is not normally considered as a precision process, is presented in this paper. The application of voltage pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with micrometer precision. In this paper, tool electrodes (5 μm in diameter, 1 mm in length) are developed by EMM and microholes are manufactured using these tool electrodes. Microholes with a size of below 50 μm in diameter can be accurately achieved by using ultrashort voltage pulses (1–5 μs).