X光光刻工艺微针阵列的制备、测试和仿真

为了提高透皮给药的效率,降低传统注射对人体的疼痛感,需要制备微针阵列结构。本文介绍了一种新的微针阵列结构的制造技术。利用日本立命馆大学的同步辐射光源AURORA进行两次X光移动光刻和一次固定X光光刻技术,在PMMA光刻胶上得到微针阵列。通过采用不同的掩膜版图形以及对不同位置的空心孔进行X光光刻,获得了不同规格的空心微针阵列,针对固定X光光刻时对准的问题,自行研制了X光光刻对准装置,实验结果证明,该装置能实现空心微针阵列的制备。并且进行了微针刺穿测试,结果证明微针有足够的强度。为了达到低成本批量复制微针阵列的目的,还进行了微针模具的倒模和复制实验,成功得到金属镍实心微针阵列。最后,针对光刻过程中微针阵列结构的侧面形状发生畸变的情况,对移动X光光刻建立了仿真预测,将仿真预测结果与实验结果进行了比较,结果表明显影深度的误差为5%。     

LIGA技术基础研究

阐述了LIGA技术的组成及特点.对LIGA工艺掩膜、X射线光刻、电铸及塑铸等进行了工艺原理分析.用一次成型法制作了以聚酰亚胺为衬基、以Au为吸收体的X射线光刻掩膜.简单介绍了这种掩膜的制作工艺过程,并用这种掩膜在北京电子对撞机国家实验室进行了同步辐射X射线光刻,得到了深度为500μm,深宽比达8.3的PMMA材料的微型电磁马达联轴器结构.给出掩膜和X射线光刻照片.同时,对Au、Ni等金属材料的厚膜电铸进行了工艺研究.     

基于X-ray光刻的微针阵列及掩膜版补偿

提出了一种聚甲基丙烯酸甲酯（PMMA）微针的微细加工工艺,即基于PCT技术,结合X射线以及光刻掩膜版制作三维微结构。通过移动LIGA掩膜版曝光的方法,可以加工微立体PMMA结构,其加工的形状取决于X光光刻掩膜版吸收体的形状。实验发现,最终的结构形状并非完全与掩膜版上吸收体的形状相一致。如果不对X光光刻掩膜版的吸收体形状进行补偿,将会导致被加工的微结构侧面变形,从而影响微针的性能。本文分析了引起微针阵列侧面的变形的原因,其中主要原因是由于显影时间与曝光量之间的非线性关系,导致结构形状与曝光量分布不完全一致,造成微针结构侧面变形。同时,通过对LIGA掩膜版上的吸收体图形进行适当的补偿,即将吸收体图形从中空的双直角三角形变为中空的半椭圆图形,这样使得带沟道的微注射针阵列的强度得到增强。     

UV-LIGA制作超高微细阵列电极技术

采用UV-LIGA技术制作了超高金属微细阵列电极,并利用电解置桩的方法辅助去除SU-8胶。通过单次涂胶和提高前烘温度、降低后烘温度的方法制作了厚度达1mm的SU-8胶结构;采取反接电极法在金属基底上电解得到微坑,增强电铸金属电极与金属基底的结合力,保证去胶后电铸金属的完整性。选取优化的工艺参数:单次注射式涂胶,前烘110℃/12h,适量曝光剂量,分步后烘50℃/5min、70℃/10min、90℃/30min,反接电极电解10V/15min等,获得了高900μm、线宽300μm的金属微细阵列电极结构。试验表明,UV-LIGA技术是一种高效、经济的制造超高微细阵列电极的有效手段。     

应用X射线光刻的微针阵列及掩模板补偿

提出了一种聚甲基丙烯酸甲酯(PMMA)微针的微细加工工艺,该工艺基于PCT技术,结合X射线以及光刻掩模制作三维微结构。通过移动LIGA掩模板曝光来加工微立体PMMA结构,其加工形状取决于X光光刻掩模板吸收体的形状。实验显示,最终的结构形状并非完全与掩模板上吸收体的形状一致。如果不对X光光刻掩模板的吸收体形状进行补偿,即会使被加工的微结构侧面变形,从而影响微针的性能。分析了微针阵列侧面变形的原因,认为这种变形是由于显影时间与曝光量之间的非线性关系导致结构形状与曝光量分布不完全一致造成的。利用PCT方法制作的PMMA微针其长度为100～750μm,直径为30～150μm,针尖的直径最小可达100nm。通过对LIGA掩模板上的吸收体图形进行适当的补偿,使吸收体图形从中空的双直角三角形变为中空的半椭圆图形,增强了带沟道的微注射针阵列的强度。     

Friction Study of a Ni Nanodot-patterned Surface

Nanoscale frictional behavior of a Ni nanodot-patterned surface (NDPS) was studied using a TriboIndenter by employing a diamond tip with a 1 μm nominal radius of curvature. The Ni NDPS was fabricated by thermal evaporation of Ni through a porous anodized aluminum oxide (AAO) template onto a Si substrate. Surface morphology and the deformation of the NDPS were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), before and after friction/scratch testing. SEM images after scratching clearly showed that, similar to what was assumed at the macroscale, the frictional force is proportional to the real area of contact at the nanoscale. It was found that adhesion played a major role in the frictional performance, when the normal load was less than 20 μN and plastic deformation was the dominant contributor to the frictional force, when the normal load was between 60 μN and 125 μN. Surprisingly, a continuum contact mechanics model was found to be applicable to the nanoscale contact between the tip and the inhomogeneous Ni NDPS at low loads. The coefficient of friction (COF) was also found to depend on the size of the tip and was four times the COF between a 100 μm tip and the Ni NDPS. Finally, the critical shear strength of the Ni nanodots/Si substrate interface was estimated to be about 1.24 GPa.     

A promising thermal pressing used in fabricating microlens array

This paper describes a simple and inexpensive technique for designing and fabricating polygon microlens arrays using a thermal pressing process. Polygon microlens array molds were fabricated using lithography and an electroforming process. The microlens patterns were designed on a photomask and transferred to a substrate through photoresist patterning. Electroforming technology was used to convert the photoresist microlens patterns into metallic molds. A hot pressing machine was then used to produce the microlens array in a polycarbonate (PC) substrate. The experimental variables were compression pressure, temperature, and the pressing time. The surface roughness of the produced microlens array was measured using atomic force microscopy (AFM). The average microlens radii of curvature ranged from 315 to 420 μm and the average sag heights were from 2.98 to 4.03 μm, respectively. The experimental result showed that this fabrication process is useful for microlens array production.     

Research and Application of MEMS Technique at BSRF

LIGA technique has been developed since 1993 at BSRF, including the fabrication of LIGA mask, deep X-ray lithography, electroplating, the pouring molding and the applications in some fields. The LIGA mask with gold absorbing structures of 20μm thickness and 5μm width and Kapton membrane of around 5μm thickness has been successfully fabricated and applied to the deep X-ray lithography with the PMMA structure of 1mm thickness or above. The beamline from a wiggler is used for the deep X-ray lithography of LIGA station and is open to other institutes researching the deep X-ray lithography. The normal process of LIGA technique with the exception of molding has been established with the PMMA structures of 500μm thickness at BSRF. The largest aspect ratio of PMMA structures can reach about 50 with the height of 500μm and the lateral size of 10μm. The nickel and copper structures with the thickness of 0.5mm and 1mm have been made by using the electroplating technique. The SU8 as a resist material of deep etch lithography with UV light is also developed in the fabrication of LIGA mask and some devices at BSRF. Electromagnetic stepping micro motor, heat exchange, accelerator, structures used in the EDM (electro discharge machining) are being developed for the future applications.     

一种新型微流控芯片金属热压模具的制作工艺研究

研究了利用UV-LIGA技术制造PMMA微流控芯片金属热压模具。采用预机械抛光的Ni板作为电铸基底,光刻SU-8 2050后形成电铸型模,然后电铸Ni微通道,去胶后电铸基底与微通道结合形成芯片热压模具。此方法有效地解决了传统UV-LIGA方法中的倒拔模斜度的问题。制作的微流控芯片模具微通道的宽度和高度尺寸偏差分别为1.7%和2.8%,满足微流控芯片的应用要求。     

大高宽比、高线密度X射线透射光栅的制作

利用电子束光刻、X射线光刻和微电镀技术,成功制作了面积为1 mm × 1 mm,周期为300 nm,金吸收体厚度为1 μm的用于X射线显微成像技术的透射光栅。首先利用电子束光刻和微电镀技术在Si3N4薄膜上制作周期为300 nm,厚度为250 nm的高线密度光栅掩模。然后利用X射线光刻和微电镀技术复制厚度为1 μm,占空比接近1：1,高宽比为7的X射线透射光栅。整个工艺流程充分利用了电子束光刻技术制作高分辨率图形和X射线光刻技术制作大高宽比结构的优点     

Fabrication of graphene/nickel composite microcomponents using electroforming

This paper introduces combined processes to fabricate graphene platelet (GPL)/nickel (Ni) composite microcomponents. The process involves co-deposition of Ni and GPL into SU-8 micromolds to form the components, where SU-8 molds of 400 μm in thickness were fabricated using UV lithography and an electrolyte with a GPL concentration of 0.2 g/L was used for the electroforming process. Pure Ni microcomponents were also fabricated under the same condition for comparison. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to examine the surface morphologies and microstructures of the microcomponents. Grain sizes were estimated based on the XRD results. A Raman microscope was used to characterize the GPLs in the GPL/Ni composite microcomponents. Hardness property was characterized using a Vickers hardness tester. Ni and GPL/Ni microcomponents of 200 μm in thickness are successfully electroformed and show good shape retention and high precision. Microscopy examinations show that GPLs are evenly deposited in the Ni matrix and agglomeration of GPLs occurs during the electroforming process. The addition of GPLs leads to significant grain refinement of Ni matrix, and the microhardness value of the composite microcomponents is twofold higher than that of pure Ni microcomponents. The research results prove a novel method to fabricate high-precision microcomponents with excellent mechanical performance by introducing GPLs into Ni matrix.     

Micromachined Si cantilever arrays for parallel AFM operation

Silicon cantilever arrays with a very small pitch for parallel AFM operations were studied. We fabricated 1x104 in eight groups and 1x30 Si probe arrays and produced a smaller pitch (15 μm) between probe tips by using Si anisotropic etching with a vertical wall shaped oxide mask. The vertical controls of Si probes were able to operate individually or in a group by integrating electrostatic actuators into the cantilevers of the probes. The fabricated Si cantilever arrays showed reasonable dynamic characteristics for the probe cantilever and reliable parallel operation of AFM.     

Stencil mask methodology for the parallelized production of microscale mechanical test samples

A new methodology to parallelize the production of micromechanical test samples from bulk materials is reported. This methodology has been developed to produce samples with typical gage dimensions on the order of 20-200 μm, and also to minimize the reliance on conventional focused ion beam fabrication methods. The fabrication technique uses standard microelectronic process methods such as photolithography and deep-reactive ion etching to create high aspect ratio patterned templates-stencil masks-from a silicon wafer. In the present work, the stencil mask pattern consists of a linear row of tensile samples, where one grip of each sample is integrally attached to the bulk substrate. Once fabricated, the stencil mask is placed on top of a pre-thinned substrate, and the pattern and substrate are co-sputtered using a broad ion beam milling system, which ultimately results in the transfer of the mask pattern into the substrate. The methodology is demonstrated using a Si stencil mask and a polycrystalline Ni foil to manufacture an array of metallic micro-tensile samples.     

Fabrication and measurement of the performance of a printed EMI shielding mesh filter on PET film

In this paper, Electromagnetic interference (EMI) shielding mesh filter films are fabricated using the screen printing method. An EMI shielding mesh filter requires fine line patterns under 30 μm, therefore, the screen masks with fine-line screen mesh, as well as suitable ink composed of fine metal particles are required. Moreover, because the printed EMI shielding filter has to be fabricated on a PET film, the ink should be sintered at a temperature below 150°C not to deform the film. For the purposes of this study, a screen mesh with a mask of 20 μm line, and ink made nano silver paste with a sintering temperature of 140°oC, which could guarantee fine-line patterning on the PET, were used. The ink had a viscosity of 90,000–12,000 cps and metal content of 85% in weight. The printed EMI shielding mesh had a line width of about 24 μm and a thickness of about 2.5 μm. The measured surface resistance was 0.5∼0.7 ω/□, offering good electrical performance as an EMI mesh. A simple measurement system was used to evaluate the electrical shielding performance of the printed EMI shielding mesh. A comparison of the printed EMI shielding mesh with pure film without mesh and copper sheet revealed that the printed EMI shielding mesh is indeed capable of providing good electrical performance.     

用于分布反馈光栅的纳米压印模板制作

高质量、低成本的压印模板的获得是采用纳米压印技术制作分布反馈光栅的难点,本文采用双层金属掩模及liftoff金属剥离方法制作了适用于紫外压印技术的石英基压印模板.首先,采用电子柬光刻技术在镀钛的石英基片表面直写出DFB光栅的光刻胶图形,接着,在其表面溅射一层金属镍并进行金属剥离得到与光刻胶相对的图形,最后采用电感耦合等...     

Laser and focused ion beam combined machining for micro dies

We have developed a laser and focused ion beam (FIB) compound process for press mold dies of a micro lens array (MLA) and a micro needle array (MNA) in a glassy carbon (GC). The press mold die of the MLA was roughly fabricated by UV-YAG laser. After this process, we finished this surface by scanning FIB. As a result, higher accuracy and good roughness of surface profile can be realized. An optical glass is used to confirm the shape of lens. Moreover, we fabricated 6 × 6 through-holes in the GC by the spiral drilling in addition to the focus position movement of the UV laser for press mold die of the MNA. After the FIB process, we were able to make the needle die of surface and hole wall roughness less than 0.9 μm. A silicon rubber is used to confirm the shape of the holes.     

Fabrication and characterization of PMN-PT single crystal cantilever array for cochlear-like acoustic sensor

We have successfully fabricated piezoelectric PMN-PT single crystal cantilever array. Each PMN-PT cantilever has a different length to achieve different resonance frequencies. The width and thickness of PMN-PT cantilever array are 200 μm and 10 μm, respectively. Resonance frequencies of PMN-PT cantilevers were measured with laser interferometer, and charge sensitivity was measured with charge-measuring device. PMN-PT cantilever array was installed in a noise-shield case. The array was then exposed to sound pressure frequency corresponding to resonance frequency to measure its sensitivity. The experimental results show that the PMN-PT cantilever array has high sensitivity to the sound pressure. This implies that the single crystal PMN-PT cantilever array is a potential candidate for a cochlear-like acoustic sensor.     

聚甲基丙烯酸甲酯材质硬X射线组合Kinoform透镜的制作

为提高硬X射线聚焦元件的聚焦性能,利用LIGA(Lithographie,Galvanoformung,Abformung)技术,制备了深度为60μm的聚甲基丙烯酸甲酯(PMMA)材质硬X射线组合Kinoform透镜(CKL),并获得了良好的面形。制备的CKL以宽度为几个微米的细窄线条为主要结构,包括曲面和直角面形,线条最窄宽度为2μm。为保证CKL良好的曲面及直角结构,样品制备分为三部分:过渡掩模板的制备,LIGA掩模板的制备,以及最终样品的硬X射线曝光制备。在LIGA掩模板制备过程中,采用制备有纳米柱阵列的硅衬底有效解决了光刻胶脱胶的问题。在最终样品制备过程中,选用分子量较高的PMMA片作衬底,提高了PMMA刚度,有效缓解了细窄线条的倒塌黏连问题,保证了CKL的良好面形。在北京同步辐射光源(BSRF)成像站测试了CKL透镜的性能,结果显示其对于8keV的X射线,聚焦焦斑的半高全宽(FWHM)为440nm。     

Development of rapid mask fabrication technology for micro-abrasive jet machining

Micro-machining of a brittle material such as glass or silicon is important in micro fabrication. Particularly, micro-abrasive jet machining (μ-AJM) has become a useful technique for micro-machining of such materials. The μ-AJM process is mainly based on the erosion of a mask which protects brittle substrate against high velocity of micro-particles. Therefore, fabrication of an adequate mask is very important. Generally, for the fabrication of a mask in the μ-AJM process, a photomask based on the semi-conductor fabrication process was used. In this research a rapid mask fabrication technology has been developed for the μ-AJM. By scanning the focused UV laser beam, a micro-mask pattern was fabricated directly without photolithography process and photomask. Therefore, rapid and economic mask fabrication can be possible for the micro-abrasive jet machining. Two kinds of mask patterns were fabricated by using SU-8 and photopolymer (Watershed 11110). Using fabricated mask patterns, abrasive-jet machining of Si wafer was conducted successfully. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Seung Pyo Lee is a research engineer of GM Daewoo Auto & Technology. He receives his Ms degree in Precision Mechanical Engineering at the Chungbuk National University in 2007. Hyun-Wook Kang is currently a Ph.D. candidate in the Department of Mechanical Engineering at POSTECH, Korea. He received his B.S. degree in the Department of Mechanical Engineering from POSTECH. His current research interests are in the solid freeform fabrication technology for the engineered tissue construction. Seung-Jae Lee received the M.S. degree from the Dept. of Me-chanical Engineering from the POSTECH in 2002, and his Ph.D. degree in Dept. of Mechanical Engineering from POSTECH in 2007. His Ph.D research is the study of Microfabrication and Tissue engineering. In Hwan Lee is a professor of School of Mechanical Engineering at Chungbuk National University, Korea. He receives his Ph.D. degree in Mechanical Engineering from the POSTECH in 2003. His research is focused on micro-manufacturing and bio-system. Tae Jo Ko is a professor of mechanical engineering at Yeungnam University, Korea. Also, he is responsible for the Gyoungbuk Hybrid Technology Institute that is regional research innovation center and initiates the idea for hybrid manufacturing. He earned Ph.D in mechanical engineering from POSTECH, Korea, in 1994. He worked for Doosan Infracore Co. Ltd. (formerly Daewoo) from 1985 to 1995. His research interests include machine tools, metal cutting as well as nontraditional machining. Dong-Woo Cho is a professor in the Department of Mechanical Engineering at the POSTECH. He received his Ph.D. degree in Mechanical Engineering from the University of Wisconsin-Madison in 1986. His research focuses on the manufacturing system for Tissue Engineering.     

同步辐射X射线光刻掩模镀金工艺的研究

介绍了利用北京正负对撞机(BEPC)同步辐射X射线光刻装置,进行LIGA工艺技术深结构光刻实验研究,详细论述了X射线光刻使用的掩模制备过程及掩模镀金工艺,在国内最早曝光出直径为400μm、厚为27～45μm的三维立体齿轮胶图形。