光刻胶光学性质的光谱椭偏测量方法研究

利用相调制型光谱椭偏仪研究了光刻胶光学常数的测量方法,针对测量过程中光刻胶曝光控制优化了测量方案和仪器参数。对常见的S9912正型光刻胶,给出了曝光前后275～650 nm波段的光学常数。并采用动态椭偏法测量了所需波长下曝光前的光学常数。实验结果表明:该测量方法适用于光刻胶在紫外-可见-红外宽波段的光学性质研究,在光刻模拟、新型光刻胶材料研制及其光学性质表征等领域有重要实用价值。     

一种有效提升石墨烯晶体管迁移率的加工方法（英文）

传统光刻工艺加工石墨烯沟道的方法中,石墨烯表面的光刻胶残留严重影响其电学特性,导致载流子迁移率大大降低.为了解决光刻胶残留的问题,采用聚合物聚甲基丙烯酸甲酯(poly(methyl methacrylate),PMMA)作为缓冲层,将石墨烯与光刻胶隔离,可以有效保护石墨烯表面,使石墨烯保持干净的表面.电学测量结果表明,与传统光刻方法相比该方法制备出的石墨烯场效应管的迁移率提升了5倍.此外,通过采用聚合物辅助的转移方法,可实现大面积石墨烯的转移.拉曼光谱数据表明,这种转移方法对石墨烯造成的沾污和破损非常微弱.该加工工艺不仅与CMOS工艺兼容,而且适用于各种基于石墨烯的微电子器件.     

环氧基负性光刻胶加工微结构的试验研究

在正交试验的基础上,将BP神经网应用于负性光刻胶(SU-8)加工高分辨率和高深宽比微结构的工艺研究,建立了光刻图形质量与前烘时间、前烘温度、曝光量、后烘时间之间的预测模型,该模型采用三层前向网络,学习算法为梯度下降法。通过实验,得出:前烘温度与前烘时间对光刻质量影响最大,对120～340μm厚的光刻胶,前烘温度取90℃,前烘时间50~100min时,图形的相对线宽差最小;最佳后烘时间(85～95℃)为30min;超声搅拌能缩短显影时间,改善图形质量。试验结果与网络预测结果吻合。结果表明,将BP神经网络应用于UV-LIGA技术中,可以优化光刻工艺。     

TFT光刻平面倾斜对光刻图形的影响及改善

薄膜晶体管光刻制程中,光刻胶光刻平面位置是决定光刻图形质量的关键因素。为了在光刻机最小分辨率条件下改善光刻图形质量,本文从光刻胶内反射光线的反射特点出发,以减小光刻胶内反射光线对非光刻区域的光刻光强及增加光刻区域的光刻胶底部光刻光强为基础,推导出光刻光线倾斜入射光刻胶平面时,光刻胶光刻平面位置调整量的计算公式,并以该公式计算出的调整量对光刻胶光刻平面进行调整。结果表明：对于最小分辨率为3.0 μm的投影光刻机,进行线间距为2.2 μm的产品光刻时,以该公式计算出的调整量对光刻胶光刻平面调整后,较未调整前,光刻图形坡度角提升了13.3%,光刻胶线宽或线间距宽度(DICD)均一性改善了14.7%,光刻图形光刻胶残留得到解决。     

接近式光刻图形失真的部分相干光理论分析

光刻过程中由于光的衍射效应产生的非线性畸变对光刻面形质量具有严重影响,是造成光刻微结构图形失真的主要原因之一,为此,研究了接近式紫外光刻中部分相干光的传播过程,建立了相应的光刻理论模型,对光刻成像中的误差产生机理进行分析．该模型综合考虑光源和照明系统对掩模微结构附近光场相干性的影响,将光刻模拟分为3部分．首先根据VanCittert-Zernike定理确定了光源经扩束准直系统传播到蝇眼透镜入射面时光场上任2点的互强度．然后应用部分相干光的传播理论,由Hopkins公式得到部分相干光经蝇眼透镜传播到掩模平面后其上任一点对的复相干度的分布规律．最后根据互强度传播定律,分析从掩模面到光刻胶表面的衍射效应,得到光刻胶表面的光强分布及变化规律,并且通过误差的仿真分析模拟得到光刻胶图形轮廓．结果表明,理论模拟结果与实验较为吻合．该方法能准确地得到衍射光场的分布,进行光刻误差分析,从而能较好地发现曝光图形缺陷．     

环氧基紫外负性光刻胶的特性、应用工艺与展望

环氧基紫外负性光刻胶(SU-8)是一种近几年发展起来的新型的光刻胶材料。它是一种双酚A酚醛缩水甘油醚环氧树脂溶解于GBL(r-Butyrolactone)而形成的高分子有机聚合物胶体．SU-8胶作为一种光刻材料，由于其独特的光学性能，力学性能和化学性能等，在MEMS(Micro—electro—mechanic—system)研究领域正受到了越来越多的关注，目前已被广泛的应用于MEMS器件的制备中。本文介绍了它的结构性能以及发展前景并报道了我们在其加工工艺上的研究进展。     

基于多掩膜光刻工艺的MEMS体硅加工

本文提出了一种新颖的MEMS多掩膜工艺,实现了带有大台阶和大深宽比窄槽的衬底上的体硅精细加工。通过薄胶多次光刻在衬底上制作出氧化硅(SiO2)、氮化硅(Si3N4)、光刻胶(photo-resist,PR)等材料的多层掩膜图形,每层掩膜可以进行一次衬底刻蚀或腐蚀,刻蚀或腐蚀完毕后去除该层掩膜。该工艺解决了MEMS工艺中的深坑涂胶和光刻问题,结合深反应离子刻蚀(Deep Re-active Ion Etching,DR IE)、湿法腐蚀等工艺可以用于多级台阶、深坑底部精细结构、微结构释放等MEMS工艺。     

微流控芯片透光性基底SU8曝光工艺

研究了在透光性基底上直接光刻SU8光刻胶制作可实现光集成微流控芯片的工艺,讨论了基底厚度、透光性和样品承载台表面反射性等因素对透光性基底上SU8光刻图形质量的影响.研究结果表明,通过减少样品承载台表面对紫外光的反射,可有效的解决光刻胶内非定义曝光区域出现感光交联的问题.     

GaAs材料ICP刻蚀中光刻胶厚度及刻蚀条件对侧壁倾斜度的影响

使用感应耦合等离子体(ICP)刻蚀技术刻蚀GaAs材料,在光刻过程中采用不同厚度的光刻胶,研究在同一刻蚀条件下不同光刻胶厚度对刻蚀图形侧壁倾斜度的影响,并研究了光刻胶厚度对侧壁倾角影响在不同大小图形刻蚀中的尺寸效应,提出了关于刻蚀机理的尺寸增益现象及可能发生的刻蚀离子的散射模型,解释了光刻胶厚度较大时小线宽图形侧壁倾角...     

聚酰亚胺微悬臂梁理论及实验

设计制作了一种电磁驱动式悬臂梁．为降低驱动电流,选择柔韧性较好的聚酰亚胺（PI）作为梁结构材料,其优良的绝缘性和耐热性保证了驱动线圈的功能实现．通过理论计算及有限元模拟仿真对悬臂梁动力响应及结构模态做了系统分析;根据分析结果,优化得到悬臂梁的结构参数．介绍了悬臂梁的制作工艺及流程,通过PI刻蚀、A7A903光刻胶光刻、电铸等工艺过程,制作出PI悬臂梁及其末端驱动线圈．     

Modeling of three-dimensional photoresist profiles exposed by localized fields of high-transmission nano-apertures

Using a simple theoretical model, we calculate three-dimensional profiles of photoresist exposed by arbitrarily shaped localized fields of high-transmission metal nano-apertures. We?apply the finite difference time domain (FDTD) method to obtain the localized field distributions, which are generated by excitation of localized surface plasmon polaritons underneath a C-shaped or a bow-tie-shaped aperture. Incorporating the results of FDTD simulations with the theoretical model, we visualize three-dimensional exposure profiles of the photoresist as a function of the exposure dose and the gap distance between the aperture and the photoresist. It is found that the three-dimensional exposure profiles provide useful information for choosing process parameters for nanopatterning by plasmonic lithography using the?aperture.     

In Situ Monitoring of Photoresist Thickness Uniformity of a Rotating Wafer in Lithography

The coating of the photoresist on the semiconductor substrate is a common process in lithography sequence. It is important to monitor the uniformity of the photoresist thickness across the substrate as the nonuniformity in photoresist thickness leads to variations in the linewidth/critical dimension (CD). In this paper, we propose a simple in situ photoresist thickness monitoring system. Our approach involves the integration of a single spectrometer to measure the photoresist thickness contour on the wafer during the spin-coating step or the edge-bead removal step. We note that the existing approaches in the monitoring of photoresist thickness are for the cases of nonrotating wafers. Our proposed approach also does not require extra processing steps compared with offline tools, which require the wafer to be moved from the processing equipment to the metrology tool. The experimental results are compared with an offline ellipsometer: the worst-case error is found to be less than 1%.      

Fabrication of three-dimensional photonic crystals by interference lithography with low light absorption

We report on the fabrication of polymer templates of photonic crystals by means of holographic (or interference) lithography. The grating is written in a SU-8 photoresist using a He-Cd laser of wavelength 442 nm. The use of the wavelength found within the photoresist low absorption band enables fabricating structures that are uniform in depth. Parameters of the photoresist exposure and development for obtaining a porous structure corresponding to an orthorhombic lattice are determined.     

Designing of high-resolution photoresists: use of modern NMR techniques for evaluating lithographic performance

Applications of improved 1-D/ 2-D NMR spectroscopic techniques have been reviewed for quantitatively estimating the incorporation of different monomers and degree of linearity in resin microstructure. Comparison of the NMR data with those from lithography leads to a distinct correlation between resin micro-structure and lithographic performance. A novel photoresist mechanism is proposed in a positive photoresist; also, using modern NMR techniques, the crosslinking mechanism in a negative photoresist has been studied.     

Absorbance-modulation optical lithography

We describe a new mode of optical lithography called absorbance-modulation optical lithography (AMOL) in which a thin film of photochromic material is placed on top of a conventional photoresist and illuminated simultaneously by a focal spot of wavelength lambda1 and a ring-shaped illumination of wavelength lambda2. The lambda1 radiation converts the photochromic material from an opaque to a transparent configuration, thereby enabling exposure of the photoresist, while the lambda2 radiation reverses the transformation. As a result of these competing effects, the point-spread function that exposes the resist is strongly compressed, resulting in higher photolithographic resolution and information density. We show by modeling that the point-spread-function compression achieved via AMOL depends only on the absorbance distribution in the photostationary state. In this respect, absorbance modulation represents an optical nonlinearity that depends on the intensity ratio of lambda1 and lambda2 and not on the absolute intensity of either one alone. By inserting material parameters into the model, a lithographic resolution corresponding to lambda1/13 is predicted.     

SU-8光刻胶制作三维光子晶体

针对SU-8光刻胶应用于三维光子晶体的制作研究,本文提出并实现了对SU-8光刻胶的重要成分SU-8环氧树脂采用柱层析和高压液相色谱-尺寸排阻色谱法进行分离,分离结果表明SU-8环氧树脂分子量分布范围很大,从大约100～100000,包括SU-1、SU-2、SU-4、SU-6、SU-8多种组分及其混合物.采用分离后的SU-8和SU-6纯组分配制了性能优化的SU-8光刻胶,并总结了其最佳光刻工艺,结合干涉光刻技术制作了晶格常数为922nm的三维面心立方光子晶体结构.     

Fabrication of microprisms for planar optical interconnections by use of analog gray-scale lithography with high-energy-beam-sensitive glass

For an integrated free-space optical interconnection system we suggest the use of microprisms to achieve large coupling angles at low loss. Prisms were fabricated in photoresist and quartz glass by analog lithography. High-energy-beam-sensitive glass was used as the gray-tone mask. Optical testing of the prisms shows acceptable surface quality and high efficiency (95%).     

Polymer film selection for corrosion protection of data storage magnetic materials

Due to the current requirement of high recording density of hard disk drive, the thickness of DLC layer which is the protective layer is needed to be reduced. Therefore, the corrosion of read-write elements that are fabricated from soft magnetic materials is more critical. During the photolithography process, polymer photoresist is playing the major role on controlling the corrosion of soft magnetic materials. Two different types of polymer photoresists are selected to investigate, noted as wet photoresist and dry photoresist, respectively. Contact angle measurement, AFM and SEM are techniques using to determine the quality of polymer photoresists. Furthermore, the direct corrosion is also studied by using potentiostat/galvanostat-based measurements. The result suggested that the wet photoresist, AZ4999 Clariant, is better as compared to that of dry photoresist. No surface degradation as well as surface defects of the wet photoresist was found after lithography process. The corrosion rate of the specimen coated by this corresponding wet film is found to be only 1.44 x 10(-6) mm/y. In addition, the wet photoresist surface is hydrophobic posed of more than 75 degree of contact angle.