飞秒激光超精细"冷"加工技术及其应用(Ⅰ)

飞秒激光的超快速时间和超高峰值特性将其能量全部、快速、准确地集中在限定的作用区域,实现对几乎所有材料的非热熔性冷处理,获得传统激光加工无法比拟的高精度、低损伤等独特优势。通过与长脉冲作用情形的比较,详细阐述飞秒激光作用的基本原理及其本质特征。介绍了目前应用飞秒激光这一独特优势在材料的超微细加工和结构处理、光子器件新型制作、高密度数据全新存储、医疗和生物工程等方面取得的最新进展,揭示了飞秒激光在工业加工、微电子、光通讯、光信息和生命科学等高技术领域有着非常广泛的应用前景。     

硅基微机械加工技术

阐明了微机电系统（MEMS）的学科内涵,概述了体微机械加工技术、表面微机械加工技术和复合微机械加工技术的特点,运用具体实例对三种硅基微机械加工技术的基本制作工艺过程进行了讨论。     

GaAs基微机械加工技术

为了进一步提高传感器的灵敏度,提出了利用GaAs半导体材料来突破硅的极限,阐明了GaAs材料的优越特性和发展GaAs基MEMS的必要性.概述了GaAs微机械加工的刻蚀技术、体微机械加工技术和表面微机械加工技术的特点,对相应的GaAs微机械加工工艺进行了举例分析,并介绍了国内首次制作的GaAs基MEMS微结构,为GaAs MEMS的进一步发展奠定了基础.     

新型快速准分子激光微加工方法制备毛细管电泳芯片的研究

选用聚合材料聚甲基丙烯酸甲酯(PMMA)代替玻璃,石英等作为毛细管电泳芯片的基片材料.在19 kV,5 Hz及5mm/min的加工参数下,采用新型快速准分子激光微加工方法完成了毛细管电泳芯片的制备.实验结果表明该方法加工过程简单,耗时短,自动化程度高,有效提高了芯片成品率和加工质量.芯片与相同尺寸的盖片在105℃、160 N、恒温20 min条件下通过热压键合在一起,得到密闭性好的整体芯片.最后在芯片上应用激光诱导荧光检测法对Cy5染料完成了分离检测,获得了重复性很好的检测信息.     

微型模具制造技术研究与发展

介绍了微型制件及微型模具成形特点，全面分析了各种微细加工方法的技术特点及其在微型模具制造中的应用状况，同时分析了各种微细加工技术的适用范围与发展前景，并重点阐述了以LIGA技术为代表的光加工技术在未来微型模具制造技术发展中的重要作用。     

激光微孔加工中调节孔锥度的算法研究

基于超快激光倒锥孔微加工技术需要,提出了一种利用电光晶体的电光偏转原理调节光束产生动态精密微位移的方法。通过四块楔形电光晶体的特定方式组合,调节施加在电光晶体上的电压大小,可使出射光束产生动态的横向位移。在此方法的基础上施加旋转运动,可实现激光加工锥度可控的倒锥孔。本文介绍了横向位移的产生方法,分析了产生最大横向位移的影响参数,举例使用KDP,D-KDP,RTP等电光晶体,讨论了不同长度下,所产生的动态横向微位移范围。入射光束直径3 mm,电光晶体厚度3 mm,宽度30 mm,总长为210 mm,楔角α为0.3 rad,调节电压从0～90000 V时,RTP电光晶体可产生0～700μm的动态横向位移。     

Effect of curing parameters and configuration on the efficacy of ultraviolet light curing self-adhesive masks used for abrasive jet micro-machining

Abrasive jet micro-machining (AJM) uses a high speed jet of particles to mechanically etch features such as micro-channels into a wide variety of target materials. Since the resulting air-particle jet is divergent, erosion resistant masks are required for patterning. Because of their ease of application, 50 and 100 μm thick commercially available ultraviolet (UV) light curing self-adhesive masks are potentially very useful in AJM. However, optimum curing parameters have until now been specified in terms of a curing time for a specific recommended curing unit, making extrapolation to other curing units impossible. Using masks to create straight 250–600 μm wide reference channels in borofloat glass, this paper quantified the optimum curing UV light energy density, and investigated the effect of differing UV exposure units (flat and cylindrical-backed), UV light energy densities, and mask configuration during curing, on the pattern transfer accuracy (before AJM), and the eroded micro-channel feature size. As expected, as long as the masks were cured at the same energy density, the pattern transfer accuracy did not depend on the curing unit. The most accurate pattern transfer to the mask film (widths within 5–7% of design) corresponded to energy densities between 516–774 and 387–516 mJ/cm² for the thick (100 μm) and thin (50 μm) masks, respectively. Under these conditions and for both exposure units, the average widths of the eroded channels after AJM were found to be within 3–9% of the intended design. Curing the masks outside this range resulted in eroded features that were approximately 15–20% and ∼5% larger than intended, for the thick and thin masks, respectively. The orientations of the channel patterns with respect to the curing cylinder axis did not affect the pattern transfer. However, when compared to the cylinder ends, curing at the midpoint along the cylinder length improved the pattern accuracy by approximately 3%, resulting in eroded features that were 10–20% closer to the design width. Finally, it was found that patterning multiple layers of masks improved the erosion resistance without compromising the feature width, enabling the AJM of higher aspect ratio features.     

Electrochemical slurry jet micro-machining of tungsten carbide with a sodium chloride solution

Electrochemical slurry jet micro-machining (ESJM) is a new non-conventional process that couples abrasive slurry jet machining (ASJM) and electrochemical jet machining (ECJM) concurrently. A micro-jet of abrasive particles and electrolytic solution is made to impinge on the target while applying a DC potential between the jet nozzle and the workpiece. ESJM can be used to remove material that is difficult to machine through a combination of erosion, corrosion and synergistic effects. This study focuses on ESJM of tungsten carbide (WC) using a pH-neutral NaCl electrolyte rather than an alkaline solution which is more commonly used in the electrochemical processing of WC. For the studied process parameters, it was shown that the erosion due to ASJM alone was not able to erode the WC, and that the corrosion under ECJM was slow and produced unacceptably wide channels. The combined ESJM process however, was found to involve erosion of the developed oxide layer and subsequent exposure of un-corroded WC, leading to a much higher machining current density, corrosion rate, and machining localization than using ECJM alone. It was also found that the total abrasive kinetic energy, working voltage and solution concentration strongly affected the machining current density, material removal rate and aspect ratio (depth to width ratio). The results indicate that ESJM has a high potential to machine difficult-to-cut metals efficiently and economically.     

A systematic study of DRIE process for high aspect ratio microstructuring

Various MEMS devices like Accelerometers, Resonators, RF- Filters, Micropumps, Microvalves, Microdispensers and Microthrusters are produced by removing the bulk of the substrate materials. Fabrications of such Microsystems requires the ability to engineer precise three-dimensional structures in the silicon substrate. Fabrication of MEMS faces multiple technological challenges before it can become a commercially viable technology. One key fabrication process required is the deep silicon etching for forming high aspect ratio structures. There is an increasing interest in the use of dry plasma etching for this application because of its anisotropic etching behavior, high etch speed, good uniformity and profile control, high aspect ratio capabilities without having any undesired secondary effects i.e. RIE lags, Loading, microloading, loosing of anisotropic nature of etching as aspect ratio increases, micro-grass and even etch stalling. Developing a DRIE micro-machining process requires a thorough understanding of all plasma parameters, which can affect a silicon etching process and their use to suppress the secondary effects. In this paper our intention is to investigate the influence of etching gas flow, etching gas pressure, passivation gas pressure, ICP coil power, Platen power and etch and passivation time sequence on etch rate and side wall profile. Parameter ramping is a powerful technique used to achieve the requirements of high aspect ratio microstructures (HARMS) for MEMS applications by having high etch rate with good profile/CD control. The results presented here can be used to rationally vary processing parameters in order to meet the microstructural requirements for a particular application.     

基于线电极原位制作的微细电解线切割加工

微细电解线切割加工是一种微细加工新方法。从理论上分析了线电极直径大小对微细电解线切割加工精度的影响,提出了原位制作微米尺度线电极的方法,并制作出直径5μm的钨丝线电极。通过电解线切割加工试验,加工出缝宽为20μm左右的微型桨叶结构和曲率半径在1μm以下的微细尖角结构。