微机械加工技术──激光微加工

介绍了激光光刻、激光和各向异性腐蚀相结合加工硅三维结构、激光化学处理加工金属微型结构和激光沉积技术．     

CO2激光直写结合湿法刻蚀加工玻璃基微流控芯片

玻璃是制作微流控芯片的重要材料,其加工工艺主要基于光刻后湿法腐蚀,对设备和实验室要求较高.本文提出以普通指甲油和指甲油/金/铬为牺牲层,利用CO2激光烧蚀开窗口,辅以湿法腐蚀加工玻璃基微流控芯片的方法,并考察了激光加工参数,腐蚀液组成,牺牲层等因素对芯片质量的影响.该方法简便易行,不需要光刻的昂贵设备和繁杂步骤.     

欧盟实现低成本批量生产大面积NSA

正由欧盟第七研发框架计划(FP7)提供490万欧元资助,总研发投入690万欧元,欧盟6个成员国9家企业联合科技界组成的欧洲PHOTOSENS研发团队,从2011年2月开始,致力于纳米结构传感器阵列(NSA)的低成本大规模工业化制造的关键技术与生产工艺突破,利用最先进的纳米压印光刻(Nanoimprint Lithography)技术,整合卷到卷(R2R)生产制造工艺,实现了低成本大批量制造生产大面积NSA的工业流程设计和设备样机开发,奠定了NSA进一步商业化推广应用的基础。     

激光偏振干涉纳米定位系统的设计与实验研究

为适应工业发展和计量界对精密定位提出的越来越高的要求,本文提出了基于偏振激光干涉技术的纳米定位方法。在该干涉测长系统中,用偏振计取代传统单频激光干涉仪的光电传感器并配置偏振分光元件、起偏镜等,可将干涉仪出射光的干涉条纹相位细分为36000份,使用波长为633nm的激光源,可将理论测量分辨率提高到 10pm。将完成的偏振干涉测长系统与商用SIOS干涉仪的实验测量结果做了比对。本文还就完成的实验系统的各误差源做了实验研究,得到量化值。经不确定度评估计算,在标准实验室环境条件下,对于微米级行程的位移,其位置测量不确定度小于1.4nm。该方法可应用于纳米定位的各个领域。     

基于LabVIEW平台的新型二维微位移传感器设计

基于矩形谐振腔的光学等倾干涉原理,设计了一种新型的二维微位移传感器系统,该系统通过电耦合器件( CCD)技术对等倾干涉产生的周期性干涉条纹进行光电转换,然后将电信号导入信号处理系统进行采集与存储,最后由串行通信发送至计算机,在LabVIEW平台进行实时的监测。仿真实验结果显示,系统测量精度可以达到1μm~0.1μm.该系统采用矩形腔等倾干涉和F-P干涉相结合的方法,结构简单,成本低廉,且能够同时对二维微位移进行精确测量,可以应用于水利工程检测维护,大型建筑安全监测、精密加工中的实时控制等很多方面。     

中国微米纳米技术学会：高分辨X射线衍射元件的研制

X射线波带片是纳米X射线成像系统的核心元件之一,为了研制高分辨率X射线波带片,对纳米结构的电子束光刻和高精度电镀进行了实验研究。首先,通过对电子束曝光工艺版图进行优化设计,平衡了邻近效应对纳米结构的影响,有效地控制了光刻胶的扭曲和坍塌。实验结果表明,采用校正的工艺版图,用线曝光方式在800pC/c m2剂量下可以研制出厚度为270nm、最外环宽度为50nm的高分辨率X射线波带片光刻胶结构。然后,在配制的柠檬酸金钾电镀液中,优化了电镀工艺参数。采用金含量为10%的柠檬酸金钾电镀液,各电镀参数PH值为4.2,电镀温度为50℃,电流密度为0.2A/dm2电镀出高分辨率X射线波带片。     

高分辨X射线衍射元件的研制

X射线波带片是纳米X射线成像系统的核心元件之一,为了研制高分辨率X射线波带片,对纳米结构的电子束光刻和高精度电镀进行了实验研究。首先,通过对电子束曝光工艺版图进行优化设计,平衡了邻近效应对纳米结构的影响,有效地控制了光刻胶的扭曲和坍塌。实验结果表明,采用校正的工艺版图,用线曝光方式在800 pC/cm2剂量下可以研制出厚度为270 nm、最外环宽度为50 nm的高分辨率X射线波带片光刻胶结构。然后,在配制的柠檬酸金钾电镀液中,优化了电镀工艺参数。采用金含量为10%的柠檬酸金钾电镀液,各电镀参数pH值为4.2,电镀温度为50℃,电流密度为0.2 A/dm2电镀出高分辨率X射线波带片。     

IT新技术

Interference Photolithography(干涉光刻)研究人员近日找到了通向25nm半导体工艺的路子,这也就是说,半导体厂商可以不必急于上马更昂贵、更复杂的13.5nm远紫外(EUV)光刻技术了。在IBM和Intel加足马力研究22nm工艺的时候,麻省理工学院的成就简单得有些难以置信。     

AlN陶瓷微热板MEMS传感器阵列设计与工艺实现

针对陶瓷基微热板MEMS器件难以微加工,器件表面加热Pt膜使用普通正性光刻胶难以实现光刻剥离的工艺难点问题,提出了激光微加工和柔性机械剥离相结合的微加工方法。以AlN陶瓷为衬底基片,采用激光微加工技术实现热隔离刻蚀体加工,刻蚀梁宽可达0.2 mm。采用柔性机械剥离工艺制备方法解决普通正性光刻胶形成倒梯形凹槽Pt膜难实现图形化问题,可在复杂表面特性的陶瓷基衬底上实现Pt膜剥离线宽10μm。同时利用有限元法进行传感器阵列设计和热结构仿真,验证设计工艺的可行性。     

一种实用纳米级位移测量校准器

提出基于新型共光路激光干涉原理的纳米级位移测量校准器，建立了其测量的数学模型，分析了其误差特性。由于采用相移干涉的相位分析技术实现波长小数测量，该测量校准器的精度好于0．5nm，量程达到几个mm；又由于共光路和紧凑的结构设计，因而具有良好的抗干扰特性，能够应用于一般实验环境。     

Large scale fabrication of asymmetric 2D and 3D micro/nano array pattern structures using multi-beam interference lithography technique for Solar cell texturing application

Microsystem Technologies - A method for the large scale fabrication of nano/micro array patterned structure for solar Photovoltaics (PV) is demonstrated by the use of laser interference lithography...     

Dual layer photoresist complimentary lithography applied on sapphire substrate for producing submicron patterns

In this study, the combined technologies of dual-layer photoresist complimentary lithography (DPCL), inductively coupled plasma-reactive ion etching and laser direct-write lithography are applied to produce the submicron patterns on sapphire substrates. The inorganic photoresist has almost no resistance for chlorine containing plasma and aqueous acid etching solution. However, the organic photoresist has high resistance for chlorine containing plasma and aqueous acid etching solution. Moreover, the inorganic photoresist is less etched by oxygen plasma etching process. The organic and inorganic photoresist deposit sequentially into a composite photoresist on a substrate. The DPCL takes advantages of the complementary chemical properties of organic and inorganic photoresist. We fabricated two structures with platform and non-platform structure. The non-platform structure featured structural openings, the top and bottom diameters and the depth are approximately 780, 500 and 233 nm, respectively. The platform structure featured structural openings, the top and bottom diameters and the depth are approximately 487, 288 and 203 nm, respectively. The precision submicron or nanoscale patterns of large etched area and patterns with high aspect ratio can be quickly produced by this technique. This technology features a low cost but high yield production technology. It has the potential applications in fabrication of micro-/nanostructures and devices for the optoelectronic industry, semiconductor industry and energy industry.     

Fabrication of nanoscale tungsten tip arrays for scanning probemicroscopy-based devices

A new fabrication process for nanoscale tungsten tip arrays was developed for scanning probe microscopy-based devices. It is suitable to make a huge array on a device chip and is potentially compatible with CMOS technology. In this study, tungsten was selected as a tip material because of its hardness and conductivity. The newly developed fabrication process mainly consists of several important techniques: a combination of optical lithography and electron beam (EB) lithography to reduce the total exposure time with high resolution and chromium/tungsten/chromium (Cr/W/Cr) sandwich deposition and etching in which the first chromium layer is used as a mask and a second one is used as an etch stop. A periodic array of dots in an EB resist with a spot diameter of less than 50 nm was obtained by a combination of optical lithography and EB lithography with a positive resist (polymethylmethacrylate) in which all processing conditions were optimized carefully. A thin and uniform chromium film, deposited by ion-beam sputtering, allowed the use of thin polymethylmethacrylate (PMMA) film which led to the high resolution. The conditions of dc magnetron sputtering were also optimized in order to deposit a densely packed and low-resistivity film. The resulting tungsten tip arrays had a cylindrical shape with diameters of less than 60 nm and heights of 300 nm     

Biodegradable submicrometric sieves in PLLA fabricated by soft lithography

Sieves are membranes with a regular array of uniform pores that present low flow resistance. Because of such characteristics they are promising devices for filtration, separation of particles by size and drug delivery control systems. In this paper, we propose and demonstrated the use of a soft lithography process for fabrication of biodegradable sieves in PLLA (poly-l-lactide) with pores in the scale of hundred of nanometers. The fabrication process is suitable for mass production and submicrometric pore diameters can be fabricated with homogeneity of about 15%. The PLLA self sustained sieve can be integrated to PLLA capsules, compounding a drug delivery systems or implants.     

A simple and cost-effective method for fabrication of integrated electronic-microfluidic devices using a laser-patterned PDMS layer

We report a simple and cost-effective method for fabricating integrated electronic-microfluidic devices with multilayer configurations. A CO₂ laser plotter was employed to directly write patterns on a transferred polydimethylsiloxane (PDMS) layer, which served as both a bonding and a working layer. The integration of electronics in microfluidic devices was achieved by an alignment bonding of top and bottom electrode-patterned substrates fabricated with conventional lithography, sputtering and lift-off techniques. Processes of the developed fabrication method were illustrated. Major issues associated with this method as PDMS surface treatment and characterization, thickness-control of the transferred PDMS layer, and laser parameters optimization were discussed, along with the examination and testing of bonding with two representative materials (glass and silicon). The capability of this method was further demonstrated by fabricating a microfluidic chip with sputter-coated electrodes on the top and bottom substrates. The device functioning as a microparticle focusing and trapping chip was experimentally verified. It is confirmed that the proposed method has many advantages, including simple and fast fabrication process, low cost, easy integration of electronics, strong bonding strength, chemical and biological compatibility, etc.     

Low cost transparent SU-8 membrane mask for deep X-ray lithography

Deep X-ray lithography masks require good transparency and mechanical resistance to the intense synchrotron X-ray beam, large active areas (cm)² and compatibility with the standard fabrication processes (optical lithography and gold electroforming). Moreover higher resolution can be achieved with low roughness flat membrane. Furthermore multiple aligned exposures require an optically transparent material. Diamond like Carbon membranes fulfill those requirements but have a prohibitive cost. Our approach consists in using an SU-8 epoxy resin layer as membrane material. In this communication the different steps of the fabrication process will be presented, as well as the results obtained using the mask for particular applications.     

Screen-printing fabrication of electrowetting displays based on poly(imide siloxane) and polyimide

We report a screen-printing fabrication process for large area electrowetting display (EWD) devices using polyimide-based materials. The poly(imide siloxane) was selected as hydrophobic insulator layer, and relatively hydrophilic polyimide as grids material. EWD devices that use poly(imide siloxane) as hydrophobic insulator fabricated with conventional methods showed good and reversible electrowetting performance on both single droplet level and device level, which showed its potential application in EWDs. The compatibility of polyimide-based materials (hydrophobic poly(imide siloxane) and hydrophilic polyimide) guarantee the good adhesion between two layers and the capability of printable fabrication. To this end, the hydrophilic grids have been successfully built on hydrophobic layer by screen-printing directly. The resulting EWD devices showed good switch performance and relatively high yield. Compared to conventional method, the polyimide-based materials and method offer the advantages of simple, cheap and fast fabrication, and are especially suitable for large area display fabrication.     

A post-bonding-free fabrication of integrated microfluidic devices for mass spectrometry applications

This paper presents a novel process for fabricating integrated microfluidic devices with embedded electrodes which utilizes low-cost UV curable resins. Commercial UV glue is sandwiched between two substrates and is used for both the structural material and the bonding adhesive. During the exposure procedure, the pattern of micro-fluidic channels is defined using a standard lithography process while the two substrates are bonded. The un-cured UV glue is then removed by vacuum suction to form the sealed microfluidic channel. With this simple approach, conventional high-temperature bonding processes can be excluded in the fabrication of sealed microfluidic structures such that the developed method is highly advantageous for fabricating microchip devices with embedded electrodes. The overall time required to fabricate the sealed microchip device is less than 10 min since no time-consuming etching and bonding process is necessary. An innovative micro-reactor integrated with an in-channel micro-plasma generator for real-time chemical reaction analysis is fabricated using the developed process. On-line mass-spectrum (MS) detection of an esterification reaction is successfully demonstrated, which results in a fast, label-free, preparation-free analysis of chemical samples. The developed process can thus show its potential for rapid and low-cost microdevice manufacturing.     

Fabrication of comb-drive micro-actuators based on UV lithography of SU-8 and electroless plating technique

Comb-drive microactuators are widely used in MEMS devices. Most of the comb-drive microactuators reported in MEMS field are made using fabrication technology with silicon as the structural material. Recent progress in ultra violet (UV) lithography of SU-8 has made it feasible to fabricate ultra high aspect ratio microstructures with excellent sidewall quality. In this paper, a research work on fabrication and metallization of high aspect ratio SU-8 polymer comb-drive microactuators was reported. The fabrication process combined multi-step and multi-layer UV lithography of SU-8 on a silicon substrate and copper electroless plating to selectively metallize the SU-8 microstructure. The selective electroless plating was achieved by using UV modification of the SU-8 microstructures and the careful control of the exposure dosage. Preliminary experimental results have proved the feasibility of the microactuator and the fabrication technology.     

Full-color reflective display device using holographically fabricated polymer-dispersed liquid crystal (HPDLC)

Abstract— A method of controlling the color of a holographic polymer-dispersed liquid-crystal (HPDLC) reflective display device has been achieved. By merely controlling the optical setup during fabrication, without changing the materials or laser light source, three primary-color devices were fabricated. Since the color of the device can be controlled continuously, a large color-reproducible area on the chromaticity diagram can be obtained. The resulting device was adequately transparent at other wavelengths to enable multiple devices to be stacked to obtain a mixture of colors. There was no significant change in color when applying an electric field. The three devices had similar reflectances and electro-optical characteristics. Therefore, this device has good potential for full-color display applications.