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.

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).

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.

多轴向高速旋转DSA在颅内动脉瘤诊疗中的应用研究

目的:探讨多轴向高速旋转DSA(下称MAHS-RDSA)诊疗颅内动脉瘤的应用价值。材料和方法:对疑有颅内动脉瘤的42例(对照组)行常规DSA检查,41例(实验组)行MAHS-RDSA检查,并将MAHS-RDSA与常规DSA对颅内动脉瘤的显示及其成像技术指标进行对比。结果:对照组42例45个动脉瘤中,检出动脉瘤43个;实验组41例患者42个动脉瘤中检出动脉瘤42个。两组病例显示颅内动脉瘤的阳性率及显示载瘤动脉没有显著差异(P>0.05),MAHS-RDSA对瘤颈的显示明显优于常规DSA(P<0.01),对瘤体的显示优于常规DSA(P<0.05),X线吸收剂量、面积剂量乘积及体位数明显低于常规DSA(P<0.01),造影剂用量少于常规DSA(P<0.05)。结论:MAHS-RDSA能清楚显示颅内动脉瘤及其毗邻关系,可减少X线辐射剂量及造影剂用量,对诊疗颅内动脉瘤有重要的应用价值。

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.

DSA电极的制备及应用的研究进展

对DSA电极制备方法和应用方向的研究现状进行了系统的综述,从DSA电极的制备条件、表面形貌、稳定性能等方面对不同的制备方法进行分析,并总结了不同制备方法对电极性能的影响。阐述了DSA电极在水体处理、化工原料制备、电镀以及湿法冶金等方面的具体应用,并根据催化层的组分对DSA电极进行分类,分析不同组分的DSA电极与其应用方向之间的关系。从DSA电极的制备和应用方向两个方面对近年来国内外的研究现状进行总结,展望了DSA电极在催化机理、制备方法以及应用方向的发展趋势。

基于DSA-FEM的航空发动机复合材料机匣优化方法

阐述了一种基于直接搜索模拟退火算法(direct simulated annealing,DSA)和有限元方法(finite element method,FEM)的复合材料层合结构的优化方法。对某型航空发动机机匣质量进行质量优化,优化目标为在保证机匣安全的前提下,尽可能减轻机匣质量,优化变量为铺层数和铺层角度。本文详细阐述了DSA优化方法结合FEM的实施步骤,并提出了一种基于多铺层组的复合材料优化技术。结果表明:DSA优化算法非常有效地减轻了机匣的质量。

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.

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.

一种简化的差应变地应力测量技术

差应变分析法是一种理论基础可靠的常用地应力测量方法,然而受测试条件限制以及测试技术难度等因素的影响,目前该方法的实际应用受到了一定限制。针对这一现状,在差应变分析法的理论基础上,以古地磁岩心定向技术为基础,引入岩石波速各向异性分布特征与地应力方向的相关原理,提出了一套简易可行的室内地应力测量新方法,即:主方向差应变分析法。该方法根据岩石波速分布特征确定出水平主应力的方向,依据水平主应力方向来制备差应变实验岩样并进行实验。和常规差应变分析法测量结果相比,该方法测量所得地应力大小的相对误差一般小于3%,地应力方向的误差一般小于5°。实例研究表明,该方法降低了实验技术难度,测量精度满足工程技术要求,具有推广价值。

便携式现场和室内两用直剪仪的研制

介绍了一种既能够在现场测试原位土体强度又能在室内测试原状土样、重塑土样的便携式现场和室内两用直剪仪。该直剪仪包括取样设备、移动式垂直加压系统和水平张拉受剪系统。采用水平张拉受剪系统克服了常规直剪试验仪中刚性顶推方式所产生的剪切盒内壁摩擦力影响问题,采用移动式垂直加压系统可确保剪切过程中垂直压力不会偏心。通过试验测试与工程应用,表明该试验仪的测试结果可信,精度能满足工程设计要求。该仪器结构简单,操作方便,便于搬运。

直接搜索—模拟退火算法在水质模型参数识别中的应用

在研究新近发展起来的模拟退火算法及其各种改进算法的基础上,提出并构造了一种能识别水质模型参数的、以记忆为基础的直接搜索—模拟退火算法,并在O connor水质模型参数识别的实例应用中,得到了更优的全局最优解,为水质模型参数识别提供了一条新途径。

双基地分布式阵列MIMO雷达的DOA和DOD估计方法

结合分布式阵列和双基地多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达的特点,提出了一种新的双基地分布式阵列MIMO雷达的接收角(Direction of Arrival,DOA)和发射角(Direction of Departure,DOD)估计方法.根据发射阵列和接收阵列的空域旋转不变特性,利用旋转不变估计技术(Estimation of Signal Parameters via Rotational Invariance Techniques,ESPRIT)获取无模糊DOA粗估计和高精度周期性模糊的DOA、DOD精估计;再利用无模糊DOA粗估计、目标的双基地距离信息以及双基地MIMO雷达的几何特点,解除DOA、DOD精估计的周期性模糊,得到高精度且无模糊的DOA和DOD估计.最后,根据ESPRIT算法原理和估计误差的概率统计特性进行算法的性能分析,给出算法基线模糊门限的近似计算方法.该算法有效地放宽了发射阵列孔径扩展程度的限制,从而提高了阵列在大孔径下的角度估计精度,且能够实现DOA和DOD估计的自动配对.仿真结果验证了所提算法和性能分析方法的有效性.

化学外延方式的嵌段共聚物定向自组装

定向自组装(DSA)是一种新型的光刻分辨率增强技术,为了探究制约DSA应用于大规模集成电路制造的因素,采用仿真手段评估了DSA工艺条件以及不同版图设计对DSA的影响。基于Cahn-Hilliard方程,模拟了不同"吸附"强度及退火时间下的线条图形光刻轮廓,分析了上述工艺条件对光刻结果的影响,发现增加退火时间、增强衬底的"吸附"强度可以有效减小电路制造缺陷。基于7 nm设计规则,改变引导图形周期,得到线条图形线宽粗糙度(LWR)以及通孔图形的光刻轮廓图,分析了引导图形周期和LWR及轮廓图质量的关系,得出当引导图形周期为2倍共聚物自然周期(2L0)时,可以得到更好的光刻图形质量,并通过2L0周期扰动实验进一步验证了该结论。

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.

Unconventional 2D Periodic Nanopatterns Based on Block Molecules

This review summarizes the self-assembly of block molecules forming unconventional two-dimensional(2D)periodic nanopatterns.Especially,we emphasize the structural evolution from simple columnar phases to complex 2D tiling morphologies in soft materials including block copolymers,liquid crystals,giant molecules,etc.Then,the state-of-the-art nanofabrication technologies for making sophisticated nanostructures with specific functions via combining both bottom-up assembly and top-down lithography-based methods are discussed,highlighting the use of directed self-assembly processes.Finally,we provide our perspective on this area.By further increasing the complexity of block molecules and the designability of lithography,low-dimensional ordered morphologies will be particularly promising for further application in nanotechnology.

气候变化对北方农牧交错带界线变迁影响的定量探测方法研究

气候对北方农牧交错带界线变迁的定量影响是目前生态脆弱敏感区对气候变化响应领域的研究热点问题。前人已在气候变化对农牧交错带界线的定性影响方面有较为深刻的认识,但仍缺乏在时间和空间上对气候贡献率进行有针对性的定量辨识。本文利用1970年以来长时间序列的国家气象站点数据和土地利用遥感解译数据,分别提取了基于气候要素和土地利用的20世纪70年代、80年代、90年代和21世纪前10年4个时期的北方农牧交错带界线,通过垂直和水平方向变动探测方法(Fish Net)和界线变迁方向变动探测方法(DSAS)对气候界线与土地利用界线的时空变化进行探测,定量分析了不同时期气候对农牧交错带界线变迁影响的贡献率。结果表明,气候与土地利用界线空间分布格局及气候贡献率在不同时期、不同区域差异较大,在西北地区变幅最小,东北地区变幅最大。在大兴安岭东南缘农田控制水源涵养生态功能区西北段以及内蒙古高原东南缘农、林、牧业生态—生产功能区西北段,气候与土地利用界线空间耦合关系最为密切,在该地区基于Fish Net方法下水平方向上气候贡献率达10.7%~44.4%,垂直方向上达4.7%~55.9%;基于DSAS方法下气候贡献率为1.1%~16.8%。两种方法探测结果大部分趋于一致,但DSAS方法精度高,适用于小范围精确探测;Fish Net方法更简单,适用于精度要求不高、快速直观的统计分析。本研究可为北方农牧交错带内农牧业生产适应气候变化、合理开发土地生产潜力、保护农牧交错带区内生态环境提供科学依据和指导。