电子束光刻制造软刻蚀用母板的研究

使用通用电子束曝光机,采用一种新的电子束微三维加工的重复增量扫描方式进行曝光实验,显影后得到轮廓清晰的微三维结构,以此为制作弹性印章的母模板,经硅烷化后可用来制作弹性印章,得到弹性印章后便可再利用软刻蚀相关技术进行微图形的复制.曝光实验的结论表明采用电子束重复增量扫描方式可用来制作微三维弹性印章的母版.     

电子束重复增量扫描生成三维结构的研究

针对三维曝光图形的结构特点,结合自行设计的图形发生器,提出了电子束重复增量扫描方式及曝光剂量与刻蚀深度关系和灵敏度的计算方法.根据计算得到的剂量关系,按照重复增量扫描方式,在SDS-3电子束曝光机上进行了曝光实验,显影后得到了轮廓清晰的梯锥和圆锥的三维结构.因此,重复增量扫描方式可以用于三维结构的加工,并且关于曝光剂量与刻蚀深度关系和灵敏度的计算可以为其提供符合实际曝光的参数.     

电子束重复增量扫描生成三维结构的研究

针对三维曝光图形的结构特点,结合自行设计的图形发生器,提出了电子束重复增量扫描方式及曝光剂量与刻蚀深度关系和灵敏度的计算方法.根据计算得到的剂量关系,按照重复增量扫描方式,在SDS-3电子束曝光机上进行了曝光实验,显影后得到了轮廓清晰的梯锥和圆锥的三维结构.因此,重复增量扫描方式可以用于三维结构的加工,并且关于曝光剂量与刻蚀深度关系和灵敏度的计算可以为其提供符合实际曝光的参数.     

电子束重复增量扫描曝光方式的反应机理研究

从高分子辐射化学的角度分析了电子束曝光的实际反应机理,推导得出曝光辐射剂量与辐射降解程度间的关系,提出了重复增量扫描方式的电子束微三维加工方法。通过在SDS-3型电子束曝光机上对正性抗蚀剂PMMA进行曝光实验,显影后得到轮廓清晰的三维结构,验证了该方法的可行性。     

电子束重复曝光加工PCR微通道的工艺研究

对PCR微流控芯片通道中流体的流动特性进行了分析,发现流体在横截面为圆形的通道中流动时由摩擦引起的等效水头损失及表面张力均小于微矩形通道。以此为依据,将PCR芯片微通道优化设计成圆形通道。在JSM-5CF电子束曝光机上采用束斑尺寸80nm、能量20keV的电子束对1μm厚的聚甲基丙烯酸甲酯进行了单次曝光剂量40μC/cm2的8次重复增量扫描曝光实验,显影后得到的PCR芯片微圆通道轮廓清晰,边缘连续光滑。证明了电子束重复增量扫描曝光方式制作PCR微流控芯片微圆通道的可行性。     

三维结构的邻近效应校正

针对三维曝光图形的结构特点,结合重复增量扫描方式,分别从水平和深度两个方向进行邻近效应校正。水平方向通过预先建立校正过程中需要的各种规则表,使所需参数可以通过查表获得,快速、准确地实现了邻近效应校正,深度方向的校正则是从吸收能量密度与曝光剂量的关系上考虑。利用SDS-3电子束曝光机完成了校正实验。AFM图显示,邻近效应已大大降低,可满足三维加工精度的要求。所提出的扫描方式和校正方法为电子束曝光的三维加工和邻近效应校正提供了一种新方法。     

聚焦离子束对铌酸锂表面加工的形貌控制研究

聚焦离子束是一种高精度、无掩膜的先进微纳加工手段。本文以铌酸锂晶体为研究对象,利用聚焦离子束/电子束双束系统对铌酸锂表面进行图形刻蚀,研究了离子束重复次数/驻留时间、扫描方式、扫描步长及束流大小等刻蚀参数对图形加工造成的影响。结合利用扫描电子成像和原子力显微镜三维形貌测量,对不同参数下的刻蚀形貌进行观察分析。该研究为实现基于铌酸锂材料的超低损耗光存储、光传导器件提供了重要的工艺参考依据。     

低温纳米压印技术制备微纳图案的研究

纳米压印需要将聚合物加热到它的玻璃化温度以上,然后用印章压印使其复制印章图案.采用低玻璃化温度的SU-82000.1和Hybrane胶体转移图案,能够在低温、甚至室温下实现微纳图案的转移.采用的印章制备方法是聚焦离子束(FIB)直接在衬底上制备图案,从而避免了传统工艺中效率较慢的电子束加工和取消了反应离子刻蚀步骤;并且采用FIB方法可同时在衬底上制备微米、纳米尺度的图案.实验结果表明用FIB方法可以得到比较均匀致密的微纳米图案印章,经过低温纳米压印后可成功地实现微纳图案的复制.     

1×11亚波长结构Dammann光栅的研制

论文基于严格耦合波理论（Rigorous Coupled-Wave Analysis,RCWA）,并采用遗传算法进行优化,设计并制作了一种具有高衍射效率的亚波长结构Dammann 光栅。光栅的分束比为111,最小特征尺寸为0.95 m,衍射效率设计值达到95%,优于传统Dammann 光栅约15%,且均匀性设计值小于2%。论文采用电子束光刻直写技术和反应离子刻蚀技术在石英基底上制作出亚波长结构图形。实验结果表明,电子束扫描曝光可以获得纳米级的图形分辨率。对石英基底的反应离子刻蚀中,射频功率、工作气压及气体流量均对刻蚀速率和栅线的表面形貌产生不同程度的影响,论文主要针对该问题进行了讨论。同时,论文也对电子束光刻直写过程中产生的线宽误差因素进行了分析。     

多能点X射线透射光栅的制作技术

针对X射线自支撑透射光栅在多能点单色成像光栅谱仪中的应用,采用电子束和光学匹配曝光、微电镀和高密度等离子体刻蚀技术,成功制备了周期为500nm、金吸收体厚度为350nm、占空比接近1∶1,满足三个能点成像需求的2000lp/mm X射线自支撑透射光栅。首先利用电子束光刻和微电镀技术制备金光栅图形,然后采用紫外光刻和微电镀技术制作自支撑结构,最后通过腐蚀体硅和感应耦合等离子体刻蚀聚酰亚胺完成X射线自支撑透射光栅的制作。在电子束光刻中,采用几何校正和高反差电子束抗蚀剂实现了对纳米尺度光栅图形的精确控制。实验结果表明,同一个器件分布的三块光栅占空比合理,栅线平滑,可以满足单能点单色成像谱仪的要求。     

软印刷技术

软印刷技术是基于弹性体印章/模具来转移图形结构的微纳加工技术。详细介绍了软印刷技术中转移图形结构的多种方式,并探讨软印刷技术在微纳电子学、光学、传感器、生物等领域的广泛应用。对软印刷技术的弹性体印章/模具制备、聚二甲基硅氧烷的属性、理论研究等进行了探讨。     

Triangular Elastomeric Stamps for Optical Applications: Near‐Field Phase Shift Photolithography, 3D Proximity Field Patterning,Embossed Antireflective Coatings,and SERS Sensing

The use of a decal transfer lithography technique to fabricate elastomeric stamps with triangular cross‐sections, specifically triangular prisms and cones, is described. These stamps are used in demonstrations for several prototypical optical applications, including the fabrication of multiheight 3D photoresist patterns with near zero‐width features using near‐field phase shift lithography, fabrication of periodic porous polymer structures by maskless proximity field nanopatterning, embossing thin‐film antireflection coatings for improved device performance, and efficient fabrication of substrates for surface‐enhanced Raman spectroscopic sensing. The applications illustrate the utility of the triangular poly(dimethylsiloxane) decals for a wide variety of optics‐centric applications, particularly those that exploit the ability of the designed geometries and materials combinations to manipulate light–matter interactions in a predictable and controllable manner.     

Pattern‐Transfer Fidelity in Soft Lithography: The Role of Pattern Density and Aspect Ratio

Using high‐aspect‐ratio nanostructures fabricated via two‐photon laser‐scanning lithography, we examine the deformation of elastomeric stamps used in soft nanolithography and the fidelity of patterns and replicas made using these stamps. Two‐photon laser‐scanning lithography enables us to systematically regulate the aspect ratio and pattern density of the nanostructures by varying laser‐scanning parameters such as the intensity of the laser beam, the scanning speed, the focal depth inside the resist, and the scanning‐line spacing. Two commercially available stamp/mold materials with different moduli have been investigated. We find that the pattern‐transfer fidelity is strongly affected by the pattern density. In addition, we demonstrate that true three‐dimensional structures can be successfully replicated because of the flexible nature of elastomeric poly(dimethylsiloxane).     

Direct stamp fabrication for NIL and hot embossing using HSQ

Commonly stamps or masters for nanoimprinting are made by electron beam lithography (EBL) and subsequent reactive ion etching into silicon. Here we present a single step procedure to prepare stamps suitable for nanoimprinting and hot embossing. The stamps are directly fabricated in HSQ (hydrogen silsequioxane), a negative EBL resist, which has a high lateral resolution and good mechanical properties. We demonstrate successful pattern transfer in both bulk PMMA and PCL by hot embossing with features down to 20 nm. Such pattern transfer is useful for biological applications. Also, we demonstrate that this approach can make stamps suitable for nanoimprint lithography and have achieved features as small as 35 nm. It was found that the stability and strength of the HSQ could be improved by annealing and that the application of a non-stick coating was not necessarily required although it aided the demoulding.     

Large area nanosize array stamp for UV-based nanoimprint lithography fabricated by size reduction process

A novel size reduction process using electron beam lithography (EBL) combining with wet etching technique is developed as a possible solution for producing large area and low cost nanopattern stamp for UV-based nanoimprint lithography (UV-NIL). In the first step, a microstructure stamp with 1.4 μm periodical pore array and aspect ratio of 1:1 was formed over a 1 inch² area on a quartz substrate. This process was carried out using common electron beam lithography (EBL) equipment, which was easily available in the modern integrated circuits (IC) semiconductor factory. Afterwards, with a controlled wet etching technique, the pore array was changed into tip patterns with the line width below 100 nm and the period keeping as before. The uniformities and nanopattern accuracies were investigated to identify its possibility as a UV-NIL stamp by AFM and SEM. Finally, as a demonstration, the as obtained stamp was used as a positive stamp to replicate the nanotips into UV-curable resist successfully by a UV-NIL process. The method developed for the mold of nanoimprint lithography would be a simple and low price approach to fabricate large area UV-NIL stamp and the nanotip array structures would be widely used in two dimensional (2D) photonic crystal application.     

Detachment Lithography of Photosensitive Polymers: A Route to Fabricating Three‐Dimensional Structures

A technique to create arrays of micrometer‐sized patterns of photosensitive polymers on the surface of elastomeric stamps and to transfer these patterns to planar and nonplanar substrates is presented. The photosensitive polymers are initially patterned through detachment lithography (DL), which utilizes the difference in adhesion forces to induce the mechanical failure in the film along the edges of the protruded parts of the mold. A polydimethylsiloxane (PDMS) stamp with a kinetically and thermally adjustable adhesion and conformal contact can transfer the detached patterns to etched or curved substrates, as well as planar ones. These printed patterns remain photochemically active for further modification via photolithography, and/or can serve as resists for subsequent etching or deposition, such that photolithography can be used on highly nonconformal and nonplanar surfaces. Various 3D structures fabricated using the process have potential applications in MEMS (micro‐electromechanical systems) sensors/actuators, optical devices, and microfluidics.     

Fabrication of Ordered Nanostructured Arrays Using Poly(dimethylsiloxane) Replica Molds Based on Three‐Dimensional Colloidal Crystals

Hexagonally arrayed structures of colloidal crystals with uniform surface are a good candidate for master molds to be used in soft lithography. Here, the fabrication of periodically arrayed nanostructures using poly(dimethylsiloxane) (PDMS) molds based on three‐dimensionally (3D) ordered colloidal crystals is reported. A robust, high‐quality 3D colloidal‐crystal master molds is prepared using the colloidal suspension containing a water‐soluble polymer. The surface patterns of the 3D colloidal crystals can then be transferred onto a polymer film via soft lithography, by means of the replication of the surface pattern with PDMS. Various hexagonally arrayed nanostructure patterns can be fabricated, including close‐packed and non‐close‐packed 2D arrays and honeycomb structures by the structural modification of the 3D colloidal‐crystal templates. The replicated hexagonally arrayed structures can also be used as templates for producing colloidal crystals with 2D superlattices.     

高线密度X射线透射光栅的制作工艺

采用电子束光刻、X射线光刻和微电镀技术,成功制作了面积为10mm×0.5 mm,周期为500nm,占空比为1∶1,金吸收体厚度为430nm的可用于X射线衍射的大面积透射光栅.首先利用电子束光刻和微电镀技术制备基于镂空薄膜结构的X射线光刻掩模,然后利用X射线光刻经济、高效地复制X射线透射光栅.整个工艺流程分别利用了电子束光刻分辨率高和X射线光刻效率高的优点,并且可以得到剖面陡直的纳米级光栅线条.最后,测量了制作出的X射线透射光栅对波长为11nm同步辐射光的衍射峰,实验结果表明该光栅具有良好的衍射特性.