A Non-parametric Gradient-Based Shape Optimization Approach for Solving Inverse Problems in Directed Self-Assemblyof Block Copolymers

We consider the inverse problem of finding guiding pattern shapes that result in desired self-assembly morphologies of block copolymer melts.Specifically,we model polymer selfassembly using the self-consistent field theory and derive,in a non-parametric setting,the sensitivity of the dissimilarity between the desired and the actual morphologies to arbitrary perturbations in the guiding pattern shape.The sensitivity is then used for the optimization of the confining pattern shapes such that the dissimilarity between the desired and the actual morphologies is minimized.The efficiency and robustness of the proposed gradient-based algorithm are demonstrated in a number of examples related to templating vertical interconnect accesses(VIA).

Directed self-assembly of block copolymers for sub-10 nm fabrication

Directed self-assembly(DSA)emerges as one of the most promising new patterning techniques for single digit miniaturization and next generation lithography.DSA achieves high-resolution patterning by molecular assembly that circumvents the diffraction limit of conventional photolithography.Recently,the International Roadmap for Devices and Systems listed DSA as one of the advanced lithography techniques for the fabrication of 3-5 nm technology node devices.DSA can be combined with other lithography techniques,such as extreme ultra violet(EUV)and 193 nm immersion(193i),to further enhance the patterning resolution and the device density.So far,DSA has demonstrated its superior ability for the fabrication of nanoscale devices,such as fin field effect transistor and bit pattern media,offering a variety of configurations for high-density integration and low-cost manufacturing.Over 1 T in-2 device density can be achieved either by direct templating or coupled with nanoimprinting to improve the throughput.The development of high x block copolymer further enhances the patterning resolution of DSA.In addition to its superiority in high-resolution patterning,the implementation ofDSA on a 300 mm pivot line fully demonstrates its potential for large-scale,high-throughput,and cost-effective manufacturing in industrial environment.

Femtosecond-laser direct writing 3D micro/nano-lithography using VIS-light oscillator

Here we report a femtosecond laser direct writing(a precise 3D printing also known as two-photon polymerization lithography) of hybrid organic-inorganic SZ2080^(TM)pre-polymer without using any photo-initiator and applying ~100 fs oscillator operating at 517 nm wavelength and 76 MHz repetition rate. The proof of concept was experimentally demonstrated and benchmarking 3D woodpile nanostructures, micro-scaffolds, free-form micro-object “Benchy” and bulk micro-cubes are successfully produced. The essential novelty underlies the fact that non-amplified laser systems delivering just 40-500 p J individual pulses are sufficient for inducing localized cross-linking reactions within hundreds of nanometers in cross sections. And it is opposed to the prejudice that higher pulse energies and lower repetition rates of amplified lasers are necessary for structuring non-photosensitized polymers. The experimental work is of high importance for fundamental understanding of laser enabled nanoscale 3D additive manufacturing and widens technology’ s field of applications where the avoidance of photo-initiator is preferable or is even a necessity, such as micro-optics, nano-photonics, and biomedicine.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized on L-glutathione self-assembled monolayers

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase （HRP） onto L- glutathione self-assembled monolayers （SAMs）. The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V （vs. saturated Ag/AgCl） in pH 7 phosphate buffer solution （PBS）, the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s^-1. The HRP-SAMs- based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 × 10^-6 mol/L to 1.2 × 10^-3 mol/L with a detection limit of 4 × 10^-7 mol/L. The apparent Michealis-Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.

Interfacial self-transportation via controlled wettability transition for directed self-assembly

Wettability transition is a significant responsive mechanism which is widely applied to construct smart materials and systems.The broad-spectrum responsiveness of the wettability transition makes it a promising way to expand innovative applications.Here,we develop a track-guided self-transportation system mediated by sequential wettability transition accompanied with capillary transportation.Alkaline fuel is loaded into polydimethylsiloxane(PDMS)cuboid to trigger the wettability transition of distributed superhydrophobic tracks laid in shallow water.After the wettability transition,the induced capillary force can propel the repetitive track-to-track transportation of PDMS.Importantly,the spacing between adjacent tracks is rationally designed based on multiple factors including threshold of wettability transition,diffusion kinetics and capillary interaction.Furthermore,the track-guided transportation system is applied to realize directed self-assembly of multiple PDMS building blocks for designated configuration,which increases the complexity and intelligence of self-assembly systems.

Engineering Nano/Microscale Chiral Self‑Assembly in 3D Printed Constructs

Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms.This study advances the integration of helical/chiral assembly and 3D printing technology,providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate geometries.We designed reactive chiral inks based on cellulose nanocrystal(CNC)suspensions and acrylamide monomers,enabling the chiral assembly at nano/microscale,beyond the resolution seen in printed materials.We employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate conditions.These techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks,and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates,as well as their post-flow relaxation.Furthermore,we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting bath.These insights into the interplay between the chiral inks self-assembly dynamics,3D printing flow kinematics and photopolymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments,ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length,as well as random orientation of chiral domains.Our biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

Emerging low-cost,large-scale photonic platforms with soft lithography and self-assembly

Advancements in micro/nanofabrication have enabled the realization of practical micro/nanoscale photonic devices such as absorbers,solar cells,metalenses,and metaholograms.Although the performance of these photonic devices has been improved by enhancing the design flexibility of structural materials through advanced fabrication methods,achieving large-area and high-throughput fabrication of tiny structural materials remains a challenge.In this aspect,various technologies have been investigated for realizing the mass production of practical devices consisting of micro/nanostructural materials.This review describes the recent advancements in soft lithography,colloidal self-assembly,and block copolymer self-assembly,which are promising methods suitable for commercialization of photonic applications.In addition,we introduce low-cost and large-scale techniques realizing micro/nano devices with specific examples such as display technology and sensors.The inferences presented in this review are expected to function as a guide for promising methods of accelerating the mass production of various sub-wavelength-scale photonic devices.

Directional Electromagnetic Interference Shielding Based on Step-Wise Asymmetric Conductive Networks

Some precision electronics such as signal transmitters need to not only emit effective signal but also be protected from the external electromagnetic(EM)waves.Thus,directional electromagnetic interference(EMI)shielding materials(i.e.,when the EM wave is incident from different sides of the sample,the EMI shielding effectiveness(SE)is rather different)are strongly required;unfortunately,no comprehensive literature report is available on this research field.Herein,Nicoated melamine foams(Ni@MF)were obtained by a facile electroless plating process,and multiwalled carbon nanotube(CNT)papers were prepared via a simple vacuum-assisted self-assembly approach.Then,step-wise asymmetric poly(butylene adipate-co-terephthalate)(PBAT)composites consisting of loose Ni@MF layer and compact CNT layer were successfully fabricated via a facile solution encapsulation approach.The step-wise asymmetric structures and electrical conductivity endow the Ni@MF/CNT/PBAT composites with unprecedented directional EMI shielding performances.When the EM wave is incident from Ni@MF layer or CNT layer,Ni@MF-5/CNT-75/PBAT exhibits the total EMI SE(SET)of 38.3 and 29.5 dB,respectively,which illustrates theΔSET of 8.8 dB.This work opens a new research window for directional EMI shielding composites with step-wise asymmetric structures,which has promising applications in portable electronics and next-generation communication technologies.

The 2017 IRDS Lithography Roadmap

Technology roadmaps have been a part of the semiconductor industry for many years.The first roadmap was Moore’s law,which started as an empirical observation that competitive forces then turned into a prediction that became an industry roadmap.Then the ITRS roadmap was developed and for many years was used by leading edge semiconductor producers to drive new technology they needed.Now there is the IRDS roadmap,which projects semiconductor end user requirements and develops a technology roadmap based on those requirements.The 2017 IRDS roadmap was just released.To prepare the roadmap,we received input from experts around the world.The roadmap predicts that the requirements of high performance logic will drive the development of different device structures in logic chips.Memory technology will also advance but is more focused on cost than high performance logic is.Because of this,there may be a split in the patterning roadmaps for different types of devices.Logic will adopt EUV and its extensions,while flash memory will consider nanoimprint.Directed self-assembly and direct write e-beam are also being developed.DSA has the potential to improve CD uniformity and lower costs.Direct write e-beam promises to make personalization of chips more feasible.DRAM memory will trail logic in critical dimensions and will adopt EUV when it becomes cost effective.The lithography community will both have to make EUV work and overcome the challenges of randomness in CDs and resist performance,while memory will try to make nanoimprint a reliable and low defect method of patterning.Long term,logic is expected to start focusing on 3D architectures in the late 2020’s.This will put a tremendous stress on the yield of patterning processes and on reducing the number of process steps that are required.It will also put more focus on hole type patterns,which will become one of the key patterning challenges in the future.

基于飞秒激光的高速双光子刻写技术

基于飞秒激光的双光子聚合(two-photon polymerization,TPP)加工技术一直是三维微纳加工技术中的研究热点。随着生命科学、材料工程、微纳光学等领域对复杂、大面积微型三维器件制备需求的提升,TPP加工效率不足的问题日益严重,加工时间过长不仅造成加工结构的不稳定,更是严重阻碍这些重要三维器件的进一步推广应用。本文以TPP加工效率提升方面的研究工作为主线,分别从单光束刻写、并行多光束刻写、面曝光和体曝光四个方式进行总结与对比,阐述相应的光学系统设计、刻写策略、刻写精度与通量等方面的研究情况,总结各种技术的优势与劣势,同时展望未来发展趋势。

电子束光刻制备In-Ga-Zn-O场效应晶体管

无掩模直写技术制备半导体器件的方法在微电子学领域受到了广泛关注。提出了采用电子束直写技术对SnO_(2)薄膜进行图形化并辐照改性的方法,成功制备了以SnO_(2)为源/漏电极的底栅型铟镓锌氧化物(IGZO)场效应晶体管(FET)并对其进行了测试。测试结果表明,该IGZO FET展现了优良的电学性能:高源漏电流开关比(1.1×10^(6))、高电子迁移率(1.4 cm^(2)/(V·s))、较小的回滞差分电压(<2 V)、极低的栅极漏电流(<1 nA),这为无掩模版制备高性能氧化物半导体器件及柔性全透明集成电路提供了全新的方法。

Directional Photo-manipulation of Self-assembly Patterned Microstructures

Highly intricate surface architectures derived from patterned polymer microstructures have received increasing concern in recent years.Directional photo-manipulation(DPM)of azopolymers is one of the effective strategies to tune the patterned polymer microstructures through directional mass migration(DMM)upon polarized light illumination.In this feature article,we emphasize the latest advances of DPM on azopatterns created by self-assembly.The mechanism of DMM,the photo-manipulation performance,and functions of manipulated patterns are introduced in sequence.As presented,DPM can manipulate the as-prepared microstructures feasibly by taking the advantages of non-contacting and nondestructive characters.Moreover,the challenges and opportunities of DPM strategy are discussed in conclusion.

Kinetically Controlled Supramolecular Block Copolymer Self-Assembly:Multicolor Photonic Crystal Patterns from a Single Formulation

Photonic crystal(PC)patterns with tunable and changeable nonvolatile structural colors printed from a single ink are of great interest for optical products but have rarely been reported because most inks can only output one respective structural color.Herein,we propose a facile yet effective kinetically controlled self-assembly strategy to address this challenge.An ink formulation containing supramolecular block copolymers(SBCPs)is developed.SBCP patterns were printed by direct-ink-writing followed by solvent annealing to generate different structural colors by simply controlling the annealing time.The self-assembly kinetic regime suggests that different colors result from various kinetically trapped metastable states.In turn,the variation in structural color enables“visualization”of the self-assembly dynamics.Furthermore,we demonstrate that these kinetically trapped structures exhibit different responsive color-change behaviors.In addition,this kinetic control strategy can be synergistic with thermodynamic control to extend the color range.This study provides a facile yet effective solution for well-designed PC patterns with tunable,responsive,and unfading colors printed from the simplest single-nozzle printer with a single colorless ink,presenting great potential in broad applications,including information storage,encryption,and anti-fake.

菲涅尔衍射光刻

通过合理选取等间距采样点的数目,利用快速傅里叶变换算法解释了有限通光光阑产生的“内密外疏”菲涅尔衍射条纹.基于菲涅尔衍射,在静态曝光、动态扫描条件下分别实现了约190 nm最小特征尺寸图形制备,以及约350 nm线宽线条直写.菲涅尔衍射光刻无需复杂的光学透镜组合,无需任何微纳衍射光学元件,且具有较大的聚焦容差.该方法有望成为一种新型的,低成本、高灵活度的亚波长图形制备手段.

激光直写光刻中线条轮廓的分析

考虑了光刻胶对光吸收作用 ,在已有描述胶层内光场分布模型的基础上 ,较为准确地推导出光刻胶层内不同深度位置的光场分布 使用迭代方法计算得到了胶层内曝光量空间分布曲线 ,分析了不同曝光量下胶层内的线条轮廓 ,为直写光刻中曝光量的选择提供了依据

二元光学元件激光直接写入设备的研制

本文介绍了二元光学元件制作的基本情况 ,国外制作二元光学元件设备的发展情况及国内制作二元光学元件设备的现状。重点介绍了长春光机所研制的二元光学元件激光直接写入设备中机械总体方面的主要关键技术 ,给出了导轨、传动系统、回转轴系、调焦伺服机构的主要技术指标和完成情况。另外还介绍了临界角法的调焦原理及实现光学调焦的调焦机构。

硅基光子晶体板的光刻和反应离子刻蚀

用光刻和反应离子刻蚀的方法对硅材料光子晶体板的制作进行了研究。实验发现,与激光 直写曝光相比,光刻曝光更有利于胶上图形的陡直度。扫描电子显微镜测试表明,反应离子刻蚀后得到深3.3μm,晶格周期10.95μm,占空比50%的孔状光子晶体板结构,孔的陡直度保持较好,基本满足设计要求。

现代光刻技术

作为当前集成电路制造的主流技术,光学光刻在趋近其分辨力极限的同时,面临着越来越大的挑战,即便在波前工程和分辨力增强技术的帮助下,光学光刻的分辨力也难以满足快速发展的半导体产业的技术需求。接近式 X 射线光刻技术(XRL)、散射角限制电子束投影光刻技术(SCALPEL)、电子束直写光刻技术(EBDW)、极紫外线即软 X 射线投影光刻技术(EUVL)、离子投影光刻技术(IPL)等下一代光刻技术(NGL)将会在特征线宽为 100—70 nm 的技术节点介入集成电路制造的主流技术中。从目前 NGL 技术发展的趋势和市场需求的多元化来看,竞争的结果很可能是各种 NGL 技术并存。当特征尺寸进入纳米尺度(≤100 nm)以后,最终只有那些原子级的成像技术才能成为胜者。

石墨烯微纳结构加工技术的研究进展

简单介绍了石墨烯独特的光电子性质,说明实现其在光电子器件中应用的有效方法是进行微纳加工。接下来对主要的石墨烯微纳加工技术——掩膜光刻、转移压印以及激光直写和干涉进行详细阐述,通过实例对每种加工技术的关键步骤和特点进行说明,并分析比较了不同加工技术的优缺点。然后对近期出现的转移压印辅助光刻和飞秒直写辅助转移压印技术的加工流程进行详细介绍,阐述将两种加工技术相结合应用于石墨烯微纳结构加工的优势。最后,简单展望了石墨烯微纳加工未来的发展趋势,指出需进一步研究的问题,对如何更好地实现石墨烯微纳结构的加工提出一些建议。