基于光刻版的无留膜紫外纳米压印技术研究

针对纳米压印光刻技术中压印脱模后的留膜去除问题,提出了一种基于光刻版的无留膜紫外纳米压印技术.采用传统的光刻版作为紫外压印模版,由于模版上铬层的遮蔽作用.使得铬层下面的光刻胶不被曝光,从而可以轻易地被去除.实验结果表明,该技术综合了压印与光刻各自的优点,可以获得无留膜厚度的压印图形,省去了压印后的留膜刻蚀工艺.从而避免了由于留膜厚度不均匀所带来的过刻蚀或欠刻蚀的问题.     

台阶处光刻工艺的优化与研究

光刻胶剖面形貌和关键尺寸（CD）是光刻工艺的关键参数,而实际光刻工艺中受到前层次图形的影响,尤其是后端布线工艺受到前面工序高低台阶影响十分严重。文章基于光学干涉原理及King的胶厚理论模型和光刻胶Swing Curve曲线研究了光刻胶跨越高台阶对成像的影响,分析了造成光刻胶剖面和关键尺寸变化的主要原因。一是台阶处衬底的反射影响了光刻胶剖面形貌;二是高台阶处光刻胶厚度比正常厚度变薄导致光刻曝光条件不适用于高台阶处光刻胶。最后通过优化胶厚及增加底部抗反射层有效解决CD差异和改善光刻胶形貌。     

高分辨率SiNx纳米压印模板的快速制备工艺

纳米压印技术是近年来国际新兴的纳米光刻技术,具有高分辨率、高效率和低成本等优点。本文结合电子束光刻技术和干法刻蚀技术开发了简洁的纳米压印SiNx光栅模板制造工艺。为提高工艺效率,引进高灵敏度的化学放大胶NEB-22胶（负性胶）作为电子光刻胶,用电子束光刻技术在NEB-22上刻出光栅图形,再利用其作为掩膜,经反应离子刻蚀后,将光栅图形转移到氮化硅上,得到所需模板。文中详细研究了NEB-22胶的电子束光刻特性及其干法刻蚀特性,指出了它作为电子束光刻胶的优点及它相对于铬掩膜而言作为干法刻蚀掩膜的不足。     

光刻胶在二元光学元件制作工艺中的行为研究

采用大规模集成电路的多次掩模光刻和刻蚀技术制作二元光学元件阵列是较为传统和实用的制作方法,其工艺过程主要包括:利用光刻技术将设计的掩模版图形转印到有光刻胶的衬底表面;利用刻蚀技术将光刻胶的图形转移到衬底表面,形成所需的表面浮雕结构.在工艺中,光刻胶的行为和特性对衬底的最终图形有着极为重要的作用.光刻和刻蚀两道工序都要求实际图形与掩模版的图形达到很高的一致性,这样才能实现元件被高保真地制作到衬底上.在整个工艺过程中,由于不同光刻胶在甩胶、前烘、曝光、显影、坚膜、刻蚀或腐蚀等工艺中表现不同的行为特性:附着性、均匀性、边缘效应、分辨率、感光度、高温形变、耐刻蚀性等等,使得所制作的器件性能有较大的区别.本文详细研究了不同光刻胶在不同工艺过程中的行为.在二元光学元件的制作中,通过选用不同的光刻胶:在第一次光刻刻蚀台阶较深时,选择粘度系数较大,高感光度,耐刻蚀的厚胶;在套刻中,刻蚀台阶较浅时,选用高分辨率、高陡直度、耐高温的薄胶,最终制作出了性能良好的二元光学元件.(OD2)     

正/负双层光刻胶厚膜剥离技术

首次介绍一种正／负双层光刻胶厚膜剥离技术,采用在厚层正型光刻胶上涂薄层负型光刻胶的方法,在光刻胶的边缘形成顶层外悬的屋檐式结构,实现了10μm蒸发膜层的无高沿边缘剥离。对不同的剥离膜厚,选取合适的胶厚,可控制剥离膜的横向尺寸精度。10μm厚蒸发膜层的横向尺寸差可控制在5μm内。     

图形反转方法制备MEMS器件电极的研究

研究了利用AZ5214光刻胶图形反转实现抗腐蚀金属NiCr剥离的关键工艺步骤,该方法可以用于制备金属电极,进而优化器件性能.理论上讨论了图形反转的形成机理,根据Dill理论对光刻胶曝光模型进行了推导,并使用MATLAB模拟工具对其进行了仿真.通过优化各项工艺参数,得到了最佳倒台面结构,并制备了精度达到1μm宽的用于MEMS器件的金属NiCr电极.     

烘焙工艺条件对厚胶光刻面形的影响

采用厚层正性光刻胶AZ P4620进行光刻实验,考察了在前烘和坚膜阶段不同的工艺参数条件下的光刻胶浮雕面形的变化.实验表明,完全显影后光刻胶的浮雕面形受前烘工艺参数的影响很小,但其显影速率有一定差别;当坚膜烘焙后,不同前烘条件下的浮雕面形差别较大;当前烘条件相同时,坚膜参数的变化对光刻胶的浮雕面形影响较大.由此得出,在前烘阶段应采取较高温度、较短时间的烘焙,而在坚膜阶段应采取较低温度、较长时间的烘焙,这样可提高厚胶光刻面形的质量.     

图形反转工艺用于金属层剥离的研究

研究了AZ-5214胶的正、负转型和形成适用于剥离技术的倒台面图形的工艺技术.用扫描电镜和台阶仪测试制作出的光刻胶断面呈倒台面,倾角约为60°,胶厚1.4μm.得到了优化的制作倒台面结构的光刻胶图形的工艺参数:匀胶转速4 000 r/min,前烘温度100 ℃,时间60 s,曝光时间0.3 s,反转烘温度110℃,时间90 s,泛曝光时间2 s,显影时间50 s.用金相显微镜测试了在优化工艺参数条件下制作的光刻胶图形的分辨率,同时对图形反转机理进行了讨论.     

AZ5214光刻胶及像反转特性的实验研究

通过实验研究了ＡＺ５２１４光刻胶分别用作正型抗蚀剂和负型抗蚀剂的光刻工艺，给出了抗蚀剂厚度为１μｍ的最佳光刻工艺参数，介绍了ＡＺ５２１４像反转特性的实验研究结果。     

利用RELACS辅助技术制作"T"型栅

利用RELACS化学收缩辅助技术制作了i线三层胶结构的"T"型栅。首先利用水溶性的化学收缩试剂RELACS,涂在曝光完成的光刻图形上,然后借由混合烘焙让光刻胶中的光酸分子因受热而产生扩散运动并进入到RELACS试剂内,催化RELACS试剂,让RELACS试剂中的高分子与交链分子产生交链反应,使得光刻胶表面形成新的一层不溶于水的交链层而达到光刻图形收缩的目的。此方法增加了细栅光刻的宽容度,降低了细栅光刻制作的难度,极易将0.5μm的栅条收缩到0.3μm,甚至更小,不但有效地减小了栅长,而且提高了细栅光刻的成品率。RELACS技术可以应用于不同光刻胶类型的"T"型栅制作中。     

Optical single layer lift-off process

The lithography of the metal wiring layers is becoming the most confining technology in the era of VLSI (very large-scale integration), as more and more circuits have to be wired on the chip itself. The two competing technologies are subtractive etch (wet or dry), and additive metal lift-off. As lift-off needs no etching, it inherently offers cost and density advantages. It, however, requires an undercut photoresist profile. These undercuts can be achieved with an image-reversal process. The paper describes such a reversal process, especially tuned for lift-off applications. The result is a simple single-layer lift-off technology with excellent image quality.     

声表面波器件制作中的一种剥离技术

介绍了一种适用于LiTaO3、LiNbO3基片的金属剥离工艺技术。该剥离技术利用碱性溶剂浸泡处理光刻胶,光刻胶顶层形成一层有利于剥离的突出遮蔽层。利用该技术可制作线宽小于0.5μm的SAW芯片。该技术无需额外设备,工艺稳定且成本低。     

Image reversal of positive photoresist: Characterization and modeling

We report on an investigation of a so-called image-reversal process where a negative tone image can be obtained with a positive resist. The reversal process is achieved by addition of a base to the exposed photoresist and a subsequent flood exposure. First, we characterize the image reversal by means of the characteristic curves, thus optimizing the process. A simple analytical model and a two-dimensional numerical simulation program have been developed in order to evaluate the dependence of the edge slope of the image-reversed resist line on resist and exposure parameters. Experimental investigation confirmed the simulation result that both positive and negative line edge slopes can be achieved with the image-reversal process by properly adjusting the exposure parameters. Finally, the image-reversal process has been compared experimentally to the standard positive process, considering linewidth control on profiled surfaces.     

Fabrication of metallic nanocavities by soft UV nanoimprint lithography

We propose a process combining UV-assisted nanoimprint lithography (NIL) and shadow mask evaporation techniques to fabricate metallic nanoparticles with cavities. A bi-layer transparent soft stamp with a hard top layer containing the high resolution patterns was obtained by spin coating and casting methods of PDMS. Then, it was used to mold the top photo-curable resist on a thick PMMA layer. After removal of the residual NIL resist layer, high density and high aspect ratio PMMA nanopillar arrays were obtained by reactive ion etching. Afterward, a four step evaporation under oblique angle was performed to deposit the gold nanostructures at the top of nanopillars. After lift-off, uniformly sized gold nanocavities were collected. Dark-field microscopy imaging of the fabricated nanocavities shows a clear geometry dependence of the emission peak wavelength, thereby providing a novel types of bio-sensing nano-objects.     

A single layer hydrogen silsesquioxane (HSQ) based lift-off process for germanium and platinum

Primarily used as etch mask, single layer hydrogen silsesquioxane has never been investigated for lift-off technique. In this article, we propose a new technique where a single layer of hydrogen silsesquioxane, a negative tone electron beam resist, is used to make lift-off of germanium and platinum. Removal of exposed hydrogen silsesquioxane is tested for various concentrations of hydrofluoric acid. Ultrasonic agitation is also used to reduce the formation of flakes due to accumulation of matter (evaporated metal in our case) along the sidewalls of the lift-off narrow slots. Results demonstrate potential in applying the hydrogen silsesquioxane as a negative tone lift-off resist to pattern nanometer scale features into germanium and platinum layers.     

金属剥离与衬底腐蚀等平面自对准OHR技术研究

开发了一套OHR(OverhangResist)技术。在原来剥离工艺的基础上,增加苯处理和高温烘烤工艺,使光刻胶掩膜既保持有利于剥离的形状,腐蚀时又不发生钻蚀,完成自对准腐蚀与等平面的金属剥离。这一技术可以广泛地应用于MEMS和集成电路加工工艺中,使器件工艺简化,降低成本,提高质量。     

Sputtered metal lift-off for grating fabrication on InP based optical devices

Sputtered metal gratings have been realized using lift-off process based on bilayer resist electron beam lithography (EBL). The lithography mask is composed of PMMA (poly(methylméthacrylate)) layer deposited under HSQ (hydrogen silsesquioxane) inorganic resist. EBL is performed in HSQ, whereas PMMA is used to ease final lift-off. We demonstrate the possibility of patterning by lift-off metals with different sputtering yields and deposition conditions. Gratings with period of 200 nm and filling factor of 50% are obtained.     

Novel triple-layer resist system

A triple-layer resist system fabricated by a spin-coating process is described. Spin-on SiO2 film is found to be a desirable intermediate layer for this system. Submicron resolution with essentially vertical walls in the thick organic layer is achieved.     

Metal lift-off using a trilevel resist system for electron beam lithography

Multilayer resist optical lithography is transposed into trilevel resist electron beam lithography. A thin electron-sensitive multilayer resist is exposed in a dedicated scanning transmission electron microscope. The upper resist layer is chemically developed, the underlying layers are patterned by reactive ion etching. Very fine titanium lines (1 μm to 30 nm) are obtained after evaporation and lift-off process.     

采用高压NMP实现全自动去胶技术

LED加工工序中,需要对晶圆表面进行去胶处理。针对LED去胶工序研究了一种去胶方法,并开发出了一种享有专利的晶圆表面金属剥离及光刻胶去除工艺及自动去胶设备,该工艺方法可去除LED表面金属层及光刻胶,并且将人工去胶的三道工艺程序整合到一起。采用该方法的全自动去胶设备,通过实验比对,能够达到良好的LED晶圆去胶良率。结尾列出了利用该方法与目前常见的人工去胶相比的多种优点。