面向极紫外：光刻胶的发展回顾与展望

半导体行业中的大规模集成电路均采用光刻技术进行加工,光刻的线宽极限和精度直接决定了集成电路的集成度、可靠性和成本。光刻技术是指利用光刻胶在紫外光或电子束下发生溶解性变化,将设计在掩膜版上的图形转移到曝光衬底上的微加工技术。随着半导体加工的光源不断进步,从g线、i线到KrF(248 nm)再到ArF(193 nm),与之匹配的光刻胶也在不断变化,以满足灵敏度、透光性以及抗刻蚀等需求。如今,极紫外(EUV)光刻已经成为公认的下一代光刻技术,然而与之对应的光刻胶还面临着不少挑战。本文简要回顾了光刻光源的发展以及对应光刻胶的变化历史,而后从极紫外光刻的原理与设备性能指标角度,结合高能光子辐射条件下的反应机理,分析了极紫外光刻胶研究中面临的灵敏度、分辨率和抗刻蚀性等方面前所未有的挑战,同时提出了对极紫外光刻胶关键性能指标与未来研究方向的展望。     

光刻胶成膜剂：发展与未来

随着集成电路制程向着3 nm乃至1 nm推进,光刻胶作为集成电路制造中最为繁杂的光刻工艺所需的重要耗材,愈发显示其重要性及挑战性。光刻胶随曝光光源的进步经历了从紫外到深紫外再到极紫外的发展,本文从成膜剂角度首先综述了紫外光刻胶及深紫外光刻胶的发展应用情况,接着对极紫外光刻胶的性能需求作了简述,最后重点针对极紫外光刻胶中的分子玻璃体系作了介绍及展望。     

电沉积技术制作高聚物微流控芯片模具

利用电沉积技术制作微流控芯片金属模具,方法是:使用新型超厚光刻胶SU8胶作近紫外光刻,并在光刻后的图案上电沉积金属Ni,之后去胶,最终获得金属模具.该法减小了电沉积工作量.采用反向电流预处理基底、并适当增加电铸液的添加剂以及脱模后真空退火,即可明显提高电沉积微结构与基底的结合力.用此金属模具成功热压了PMMA,制成了微流控芯片.     

多光子光刻用的杯[4]芳烃分子玻璃正性光刻胶

分子玻璃材料和多光子光刻技术分别是近年来光刻胶和光刻技术领域的研究热点.本文对分子玻璃正性光刻胶在多光子光刻中的应用进行了探索,设计合成了叔丁氧基羰基保护的杯[4]芳烃衍生物分子玻璃材料,将其作为主体材料与光生酸剂三氟甲磺酸三苯锍鎓盐进行复配,制备了分子玻璃正性光刻胶,探讨并优化了光刻胶的成分配比及其在紫外光曝光下的显影工艺.利用780nm波长飞秒激光对所制备的分子玻璃正性光刻胶进行了多光子光刻特性的评价,实验得到了最低线宽180nm的线条和复杂的二维微结构图形,结果表明杯[4]芳烃衍生物分子玻璃正性光刻胶有望应用于多光子光刻技术.     

上海光源极紫外光刻胶检测平台

极紫外光刻技术作为下一代光刻技术,被行业赋予了拯救摩尔定律的使命。极紫外光刻胶是极紫外光刻技术的核心子技术之一,其分辨率、粗糙度、灵敏度以及放气情况等指标的检测是开展极紫外光刻胶研发的必要条件和实现极紫外光刻胶配方优化的重要环节。基于同步辐射的极紫外干涉光刻技术是目前最适合开展的一种用于极紫外光刻胶性能检测的方法。上海光源根据相关的研发需求,已建立了一个基于该方法的极紫外光刻胶检测平台。通过不断改善装置的稳定性,发展自主的分束光栅掩膜制作技术,以及不断摸索和优化相应的干涉曝光工艺,目前检测平台的曝光分辨率测试水平已能达到20 nm以下,基本满足极紫外光刻7 nm工艺节点的相应要求。     

光胶做挡光层的紫外光刻掩膜用于高聚物芯片表面选择性光化学改性

紫外光谱研究表明,AZ正性光胶当厚度大于10μm时,在200～285nm的紫外光区几乎不透光。本研究据此研制了一种以固化后的AZ光胶做挡光层、石英玻璃做底板的紫外光刻掩膜。应用AZ光胶掩膜对聚碳酸酯(PC)表面进行以低压汞灯(主要辐射254nm紫外光)为光源的选择性光化学改性,在光照区域形成化学镀所需的催化中心后,采用化学镀技术,在PC毛细管电泳芯片上制备安培检测用的集成化金微电极。本掩膜材料简单,制作方便,无须洁净实验室和贵重的设备,成本低廉。     

光刻技术:发展路径及未来趋势

光刻技术在半导体器件大规模生产中发挥重要作用.今天,多数先进半导体生产都已经应用ArF准分子激光浸润光刻技术.双重图像曝光和侧壁图像转移技术使ArF准分子激光浸润光刻技术延伸到32纳米半节距(HP)器件的制造成为可能.为了制造更小尺寸的器件,必须开发新的制造工艺.极端紫外线光刻是制造22纳米半节距甚至更小尺寸半导体器件的先进下一代光刻技术解决方案.另外,其他技术解决方案,如纳米压印光刻技术和无掩模直描光刻技术等也被考虑用于制造更小节点尺寸的器件,但是目前这些方案仅仅处在研发阶段,而且在现阶段就已经呈现出在大规模生产中的诸多困难.本文从材料的角度对光刻技术进行一个整体描述,并对光刻技术未来趋势进行讨论.     

先进光刻技术：导向自组装

导向自组装(Directed Self-Assembly, DSA)光刻技术是一种极具发展潜力的新型图形化工艺,已被国际器件与系统路线图(International Roadmap for Devices and Systems, IRDS)列为下一代光刻技术的主要候选方案。DSA光刻技术是基于嵌段共聚物(Block Copolymer, BCP)自组装构建高分辨图案,能够突破传统光学光刻的衍射极限,具有高通量、低成本和延续性好等显著优势,已成为半导体工艺技术中的研发热点。将DSA与其它光刻技术如极紫外(Extreme Ultraviolet, EUV)光刻、深紫外(Deep Ultraviolet, DUV)光刻、紫外光刻和纳米压印光刻(Nanoimprint Lithography, NIL)等相结合,能极大地提高加工结构的分辨率以及器件的密度。目前,DSA光刻技术已被应用于鳍式场效应晶体管(Fin Field-Effect Transistor, FinFET)、存储器和光电子器件等领域,以期实现高密度集成和高效率低成本制造。本文对DSA光刻技术的原理、材料、工艺、应用以及在工业化进程中所面临的机遇和挑战进行全面的综述。     

高分辨率极紫外光刻胶的研究进展

自集成电路芯片诞生半个多世纪以来,芯片尺寸在不断减少,以极紫外光刻为代表的光刻技术也有了显著的发展。同时,实现更高精度的光刻图案需要更加先进的光刻胶材料。传统的聚合物光刻胶材料因其相对分子质量大、高精度条纹易坍塌等缺陷使其使用受到限制。以分子玻璃和无机金属配合物光刻胶为代表的相对分子质量小、结构均一的新型光刻胶材料在国内外得到了广泛发展。本文对现阶段新型极紫外光刻胶材料的发展现状和趋势做了评述。     

基于尼龙微孔薄膜的微流控芯片的制作及对葡萄糖的显色响应

以尼龙微孔薄膜为基质材料, 采用光刻法将正性紫外光刻胶转移到薄膜上形成目标微通道图形, 制作了一种新型薄膜微流控芯片. 对尼龙微孔薄膜芯片的制作工艺进行了优化和改进, 使其制作时间控制在1 h内, 且制作步骤大为简化, 可实现快速、 批量地制作尼龙薄膜芯片. 在该芯片上进一步固定葡萄糖氧化酶和辣根过氧化物酶后, 利用二步酶促化学反应开展了葡萄糖的显色响应研究. 结果表明, 所制作的尼龙薄膜芯片对不同浓度的葡萄糖均能产生明显的颜色响应, 具有较宽的浓度响应范围和良好的重复性, 并可用于实际样品中葡萄糖的显色响应研究.     

用于浸没式工艺的光刻胶研究进展

浸没式光刻技术是在原干法光刻的基础上采用高折射率浸没液体取代原来空气的空间,从而提高光刻分辨率的一种先进技术.此项技术的实际应用,为当前IC产业的飞速发展起到了关键的作用.本文概述了浸没式光刻技术的发展历程和浸没式光刻胶遇到的挑战及要求;对浸没式光刻胶主体树脂、光致产酸剂及添加剂的研究进展进行了综述;最后对浸没式光刻胶的研究发展方向作了进一步的探讨及初步预测.     

Polymers in conventional and alternative lithography for the fabrication of nanostructures

This review provides a survey of lithography techniques and the resist materials employed with these techniques. The first part focuses on the conventional lithography methods used to fabricate complex micro- and nano-structured surfaces. In the second part, emphasis is placed on patterning with unconventional lithography techniques such as printing, molding, and embossing, and on their development into viable, high-resolution patterning technologies.     

先进光刻胶材料的研究进展

本文简述了光刻技术及光刻胶的发展过程,并对应用于193纳米光刻和下一代EUV光刻的光刻胶材料的研究进展进行了综述,特别对文献中EUV光刻胶材料的研发进行了较为详细的介绍,以期对我国先进光刻胶的研发工作有所帮助.     

光刻胶用底部抗反射涂层研究进展

随着微电子工业的蓬勃发展,光刻技术向着更高分辨率的方向迈进,运用底部抗反射涂层有效消除光刻技术中的驻波效应、凹缺效应,提高关键尺寸均一性和图案分辨率,引起了广大研究者的关注。本文简要介绍了光刻胶和光刻技术,底部抗反射涂层的分类、基本原理、刻蚀工艺以及其发展状况。重点对底部抗反射涂层的最新研究进展进行了总结,尤其是碱溶型底部抗反射涂层在光刻胶中的应用研究,最后对底部抗反射涂层的发展前景和方向进行了展望。     

Cell patterning using a template of microstructured organosilane layer fabricated by vacuum ultraviolet light lithography

Micropatterning techniques have become increasingly important in cellular biology. Cell patterning is achieved by various methods. Photolithography is one of the most popular methods, and several light sources (e.g., excimer lasers and mercury lamps) are used for that purpose. Vacuum ultraviolet (VUV) light that can be produced by an excimer lamp is advantageous for fabricating material patterns, since it can decompose organic materials directly and efficiently without photoresist or photosensitive materials. Despite the advantages, applications of VUV light to pattern biological materials are few. We have investigated cell patterning by using a template of a microstructured organosilane layer fabricated by VUV lithography. We first made a template of a microstructured organosilane layer by VUV lithography. Cell adhesive materials (poly(d-lysine) and polyethyleneimine) were chemically immobilized on the organosilane template, producing a cell adhesive material pattern. Primary rat cardiac and neuronal cells were successfully patterned by culturing them on the pattern substrate. Long-term culturing was attained for up to two weeks for cardiac cells and two months for cortex cells. We have discussed the reproducibility of cell patterning and made suggestions to improve it.     

Vacuum-UV influenced design of polymers and dissolution inhibitors for next generation photolithography

An overview of our 157 nm photoresist development activities is presented. Examination of the vacuum ultraviolet (VUV) absorbances of fluorinated monomers and polymers has provided knowledge that influenced copolymer design so that resist transparency in the vacuum-UV can be maximized. Partially fluorinated norbornenes and tricyclononenes (TCNs) have been incorporated into copolymers using metal-catalyzed addition and radical initiators. These materials have orders of magnitude higher transparency at 157 nm compared to their hydrocarbon analogues as measured by variable angle spectroscopic ellipsometry (VASE). We have also synthesized fluorinated dissolution inhibitors for use in a three-component resist system. The results of preliminary lithographic evaluations of resists formulated from these polymers are presented.     

High-refractive index acrylate polymers for applications in nanoimprint lithography

The development of polymeric optical materials with a higher refractive index,transparency in the visible spectrum region and easier processability is increasingly desirable for advanced optical applications such as microlenses,image sensors,and organic light-emitting diodes.Most acrylates have a low refractive index(around 1.50)which does not meet the high perfo rmance requirements of advanced optical materials.In this research,three novel acrylates were synthesized via a facile one-step approach and used to fabricate optical transparent polymers.All of the polymers reveal good optical properties including high transparency(≥90%)in the visible spectrum region and high refractive index values(1.6363)at 550 nm.Moreover,nanostructures of these acrylate polymers with various feature sizes including nanogratings and photonic crystals were successfully fabricated using nanoimprint lithography.These results indicate that these acrylates can be used in a wide range of optical and optoelectronic devices where nanopatterned films with high refractive index and transparency are required.     

氩离子激光固化环氧树脂制作三维微结构

利用激光束进行三维成像是通过逐层光引发聚合形成宏观尺度的三维实体 .最近出现的激光全息光刻技术是利用激光束的干涉产生三维全息图案 ,让感光树脂在全息图案中曝光 ,从而一次形成三维周期有序微结构 .通过调节激光干涉及波长可控制三维结构的形状及尺寸 .利用该技术获得亚微米尺度上周期性重复的三维微结构 ,可用于制作三维光子晶体 [1,2 ]等具有独特性能的聚合物材料 .本文用铁芳烃化合物与特种环氧树脂配制成阳离子型可见光固化树脂 ,在氩离子激光器产生的多束可见连续激光相干形成的空间干涉光场中曝光 ,成功地制备出亚微米量级的三…     

Imaging by sensitized oxygenations of photochromic anthracene films: examination of effects that improve performance and reversibility

The aliphatic anthracene compound 1 and the oligomeric anthracene 2 were synthesized. Thin films of 1 and 2 mixed with the sensitizers tetraphenylporphyrin (TPP) and methylene blue (MB) were irradiated with visible light in air. Upon formation of singlet oxygen, the anthracene units were converted quantitatively to the corresponding endoperoxides. Heating of the irradiated samples afforded the parent anthracenes with high yields. Here, we demonstrate that the kinetics and reversibility of this reaction strongly depend on the microenvironment of the anthracene groups in the two compounds. The photooxidation of thin films of 1 is accompanied by interesting changes in the morphology of the film and allows the first application of 1 as a nondestructive negative-tone photoresist for lithography and as an oxidizing ink. The morphology of 2 remained unchanged after photooxidation as a result of the stabilizing oligomer backbone. This stabilizing effect significantly improves the photochromic performance of 2. The reversibility of the photooxidation is very high (>90 %) for oligomeric films of 2 after several cycles of irradiation and heating. Decomposition of the anthracene and a loss of the activity of the sensitizer diminish slightly the performance of the monomeric species.