接近式光刻图形失真的部分相干光理论分析

光刻过程中由于光的衍射效应产生的非线性畸变对光刻面形质量具有严重影响，是造成光刻微结构图形失真的主要原因之一，为此，研究了接近式紫外光刻中部分相干光的传播过程，建立了相应的光刻理论模型，对光刻成像中的误差产生机理进行分析．该模型综合考虑光源和照明系统对掩模微结构附近光场相干性的影响，将光刻模拟分为3部分．首先根据VanCittert-Zernike定理确定了光源经扩束准直系统传播到蝇眼透镜入射面时光场上任2点的互强度．然后应用部分相干光的传播理论，由Hopkins公式得到部分相干光经蝇眼透镜传播到掩模平面后其上任一点对的复相干度的分布规律．最后根据互强度传播定律，分析从掩模面到光刻胶表面的衍射效应，得到光刻胶表面的光强分布及变化规律，并且通过误差的仿真分析模拟得到光刻胶图形轮廓．结果表明，理论模拟结果与实验较为吻合．该方法能准确地得到衍射光场的分布，进行光刻误差分析，从而能较好地发现曝光图形缺陷．     

Si衬底表面圆柱孔形抗反射周期微结构的设计及制造

在本征硅片表面设计并制作了一种圆柱孔形抗反射微结构。基于严格耦合波分析方法,通过数值计算及模拟仿真确定了微结构最优参数组合,设计反射率小于3%。应用二元曝光、湿法腐蚀和反应离子刻蚀技术制作了单面和双面抗反射周期阵列微结构。根据测试结果判断反应气体流量、射频功率及工作气压等工艺参数对微结构形貌及侧壁陡直度具有很大影响,经过实验分析确定了最佳工艺参数组合。采用热场发射扫描电子显微镜和白光干涉仪对该结构进行形貌表征,利用显微成像红外光谱仪对其反射率进行测量。最终结果表明,相比于单面微结构和无结构本征硅片,双面微结构抗反射效果最好,得到反射率为8%左右,基本达到抗反射设计要求。     

Pt(111)小面微结构的反射电子显微分析方法

介绍了反射电子显微术的成像原理和实现这种技术的方法,报道了用JEM-200CX电镜对Pt(111)小面微结构观察的结果。利用反射电子束成像可以揭示平坦小面的微观结构,如单原子高度的台阶,位错露头和滑移迹线等;利用背散射电子成像,可以揭示Pt(111)小面微结构的转变。实验结果表明,反射电子显微术是分析表面微结构的有效方法。     

SU-8的紫外深度光刻模拟

在微电子机械系统 (MEMS)中 ,大高宽比微结构被广泛应用。由于紫外光衍射效应比较大 ,通过紫外光刻获得高精度的大高度微结构并不容易。本文主要研究了衍射效应对深紫外光刻精度的影响 ,并与实验结果进行了比较 ,理论模拟结果和实验比较吻合。因此 ,通过模拟结果得到不同厚度光刻胶的最佳曝光剂量 ,以便得到更好的微结构图形     

基于电子束曝光的微区加热技术

提出了基于电子束曝光的微区加热技术.在研究样品吸收能量密度的基础上,在FEI820 Dual Beam FIB/SEM系统上对30 keV电子束曝光Pb、Bi、Sn、Al金属薄膜以及15 keV电子束曝光S1805正性抗蚀剂微结构时的微区加热效应进行了实验研究.结果表明,在一定的曝光剂量下样品表面出现了熔化现象,证明采用电子束曝光可以使某些材料微小区域表面达到相变温度或熔点以上,为使用电子束曝光技术完成某些材料的微纳区域表面热处理以及制备具有光滑曲面的微结构提供了新途径.     

大尺寸仿生微结构表面防污涂层制备及性能研究

鲨鱼、海豚等海洋生物的表皮结构具有防污功能,猪笼草的口缘区具有液膜单向传递特征,这些表面结构形貌可为船舶涂层的防污和减阻设计提供重要依据。根据鲨鱼皮表面肋条状结构、猪笼草口缘区单向沟槽和弧形结构,设计简化单向V型沟槽微结构形貌,并结合CFD模拟计算分析V型沟槽减阻性能,确定了仿生微结构的形貌及尺寸。利用皮秒激光刻蚀技术,在铝合金基材表面刻蚀微结构形貌模板,然后在未完全固化的防污涂层表面压印,通过对软/硬模板、固化时间、压印压强等工艺条件参数的考察及优化,制备出较大尺寸的仿生微结构表面涂层。使用三维形貌测试仪、接触角测试仪等表征仿生微结构涂层表面,并进行多海域实海浸泡性能实验。结果显示,该仿生涂层表面微沟槽间距为90.8 μm,深度为60.3 μm,其表面接触角为121.7°,微结构形貌均匀,具有良好的实海防污性能。      

3D打印HA微球支架的制备与表征

生物材料表面微结构对于成骨具有重要的影响, 该研究以不同粒径(< 60 μm)的羟基磷灰石(HA)微球状粉体为原料, 通过3D打印技术制备了一系列(HA0、HA10、HA30、HA50)生物陶瓷支架。不同支架具有相似的理化性能, 由于微球粒径不同形成了不同的微结构, 对其生物学性能造成不同的影响。相比传统非微球颗粒打印的支架(HA0), HA微球构成的支架能够提供更多细胞粘附和生长位点, 24 h的粘附实验显示HA30支架能显著促进骨髓间充质干细胞的伪足伸长; 培养5 d的细胞增殖实验显示, 微球支架上的细胞数量与HA0支架出现显著性差异, 表面微球结构与细胞尺度相当的HA30支架具有最好的促增殖效果。因此, 3D打印技术在可控制备HA支架宏观结构的同时, 还可以通过控制生物陶瓷粉体的颗粒形貌, 调控3D打印支架的表面微结构, 从而优化其生物学效应, 在骨组织工程领域具有良好的应用前景。     

浅水爆炸下高桩钢管柱表面作用荷载实验研究

通过不同炸药量、不同爆炸距离、不同起爆深度的水中爆炸模型实验,研究了浅水爆炸条件下高桩钢管柱表面压力特征和空间分布规律,分析了比例爆距对冲击波峰值及空间分布影响,给出了钢管柱表面冲击波反射系数、绕射系数和抗爆设计中实际作用冲击波的工程算法。研究结果表明:水中爆炸作用下,反射和绕射冲击波近似同时作用在钢管柱表面,峰值沿柱身高度方向非均匀分;冲击波受水面影响程度相对较小,二次气泡脉动受水面影响程度较大;反射和绕射冲击波峰值均随炸药量增加、作用距离减小而增加。比例爆距相同,反射冲击波峰值相同,但炸药量小、爆炸距离近的实验工况绕射冲击波峰值相对较小;钢管柱表面冲击波反射系数和绕射系数随比例爆距增加而减小。比例爆距≥1.71时,钢管柱实际作用冲击波峰值可近似按自由场冲击波峰值的1.37倍计算。     

SU—8的紫外深度光刻模拟

在微电子机械系统（MEMS）中，大高宽比微结构被广泛应用，由于紫外光衍射效应比较大，通过紫外光刻获得高精度的大高度微结构并不容量，本主要研究了衍射效应对深紫外光刻精度的影响，并与实验结果进行了比较，理论模拟结果和实验比较吻合，因此，通过模拟结果得到不同厚度光刻胶的最佳曝光剂量，以便得到更好的微结构图形。     

复合材料层板铺层方式对超声检测结果的影响

对T700/6421炭纤维复合材料在RTM工艺下制作的不同铺层方式的试样,进行两种频率的脉冲反射法超声检测实验,研究纤维铺层方式对超声检测结果的影响,并得到以下结论:纤维铺层方式对声波在材料中传播的声速和衰减有一定影响,在进行缺陷深度定位和材质衰减测量时,应予以修正;纤维铺层方式对复合材料上下表面检测分辨率、层间分层缺陷的可检性和缺陷大小的评定没有明显影响。     

激光声表面波检测铝板表面凹痕的数值研究

采用平面应变的有限元模型数值模拟了热弹机制下线型脉冲激光辐照金属铝板表面激发高频声表面波,及声表面波经过表面矩形凹痕时发生反射的过程.计算结果表明: 声表面波中的瑞利波经过表面凹痕时发生明显的反射,并产生两个相继出现且具有相同的传播速度的反射表面波成分;随着凹痕深度的增加,两个反射瑞利脉冲出现的时间间隔将增大;数值计算从理论的角度有力地证实了前一反射瑞利波产生于凹痕的顶端,而后者源于其底部的论断,从而为定量检测金属表面缺陷的深度提供了理论依据.     

Quantitative use of Rayleigh waves to locate and size subsurface holes

An ultrasonic inspection method is used to obtain the circumference of a subsurface hole and the depth of the hole below the surface. A pitch-catch Rayleigh wave transducer set-up was used to launch a Rayleigh surface wave at the flaw and to capture and record the scattered waves. The frequency spectrum of the scattered waves can be used to obtain the depth of the hole. The ligament of material between the hole and the surface is sent into resonance, and this feature can be extracted from the scattered waves' frequency spectrum. The frequency is a function of the ligament length; thus the hole depth can be obtained. The circumference of the hole is found from a time of flight measurement. A Rayleigh wave is formed that travels around the hole's surface. The length of time required for the wave to travel around the hole is a measure of the circumference.     

Rayleigh波作用下地下结构的动力反应分析

基于粘弹性人工边界提出了Rayleigh波的时域波动输入方法,在此基础上研究了Rayleigh波作用下地下隧道的动力反应特性,重点研究了埋深对结构动力反应的影响。结果表明提出的波动输入方法具有良好的模拟精度;Rayleigh波对浅埋地下结构的动力反应影响显著;存在临界埋深D0,当结构埋深D>D0时,随着埋深的增加,结构动力反应逐渐减小;当D相似文献   

Elastodynamic Doppler effects by a moving stress-free edge

Wave reflection by a uniformly moving stress-free edge is discussed for all three types of incident plane SH, P and SV-waves, and the Rayleigh surface wave on the moving edge is also discussed. Focusing on the Doppler effect and ray angles for the reflected wave, all frequency shifts and reflection angles are expressed in the closed form of simple algebraic equations. It is found that the Rayleigh surface wave on the moving stress-free edge has its complex velocity. This complex velocity means that the Rayleigh wave decays when the edge is expanding, but grows exponentially when the edge is shrinking. This is a completely new result.     

Ray representation of longitudinal lateral waves in acoustic microscopy

For object materials having a large enough Rayleigh velocity, the V(z) (where V is the output voltage and z is the defocus distance) variation is mainly due to interference between the fields of the geometrically reflected wave and the leaky Rayleigh wave. However, for materials, such as organic compounds, having a low Rayleigh velocity, the leaky Rayleigh wave is not excited. For this case, the lateral wave resulting from propagation along the surface of the longitudinal wave plays a significant role in determining the V(z) dependence. The effect of the lateral wave contribution on V(z) is studied. Ray optics is to derive an expression giving the influence of the longitudinal lateral wave. Good agreement is found between the theory and measurements for z not near zero. Because of the ease with which the longitudinal wave velocity can be obtained from V(z), one can conveniently determine the elastic constant c(11 ) of isotropic materials using the acoustic microscope.     

On dispersion relations of Rayleigh waves in a functionally graded piezoelectric material (FGPM) half-space

For propagation of Rayleigh surface waves in a transversely isotropic graded piezoelectric half-space with material properties varying continuously along depth direction, the Wentzel–Kramers–Brillouin (WKB) technique is employed for the asymptotic analytical derivations. The phase velocity equations for both the electrically open and shorted cases at the free surface are obtained. Influences of piezoelectric material parameters graded variations on Rayleigh wave dispersion relations, particles’ displacements magnitude and corresponding decay properties are discussed. Results obtained indicate that coupled Rayleigh waves can propagate at the surface of the graded piezoelectric half-space, and their dispersion relations and the particles displacements ellipticity at the free surface are dependent upon the graded variation tendency of the material parameters. By the Rayleigh surface waves phase velocities relative changing values combined with the relationship between the wave number and the material graded coefficient, a theoretical foundation can be provided for the graded material characterization by experimental measurement.     

Quantitative imaging of Rayleigh wave velocity with a scanning acoustic microscope

An acoustic microscope operating with impulse excitation has been used to perform measurements of the Rayleigh wave velocity by measuring the time difference between the direct reflected signal and the Rayleigh wave signal. The accuracy and precision of the methodology have been examined by performing measurements at a single location on an elastically isotropic sample of E6 glass. The accuracy of the Rayleigh wave velocity measurement has been determined to be better than 0.5%. The measured Rayleigh wave velocity of (3035±5) m/s differs by 0.3% from measurements reported in the literature for a similar sample, using two different techniques. The methodology has been extended to acquire the Rayleigh wave velocity while raster scanning the sample to develop a quantitative velocity image. The background noise in the Rayleigh wave velocity image has been investigated by mapping the velocity on elastically isotropic E6 glass. Possible reasons for background noise in the images is discussed. The methodology has been extended to acquire quantitative Rayleigh wave velocity images on Ti-6Al-4V. The contrast in the images is attributed to the variation of the Rayleigh wave velocity in individual grains or regions. Applicability of the technique to investigate crystallographic texture in materials is discussed     

Condition assessment of concrete in hydraulic structures by surface wave non-destructive testing

Maintenance and rehabilitation of concrete structures affected by alkali-aggregate reaction (AAR) require conducting detailed assessment of the concrete conditions, mainly close to the surface where the damage is more severe. This paper presents in situ investigations by surface wave testing of near-surface AAR damage in two hydraulic structures. The survey was carried out using a non-intrusive multi-sensor method that involves frequency–wavenumber analysis of surface waves. The method allows solving Rayleigh surface wave propagation modes required for the determination of the shear wave velocity in terms of depth. The variation of Young’s modulus with concrete depth can be estimated from the obtained shear wave velocity profile. Two different cases of surface wave propagation, typical of concrete structures, are discussed in this paper. The tests were conducted from the concrete surface only and the subsurface quality was mapped up to a depth of 1.50 m. The applications show that the proposed surface wave method is a potential non-destructive evaluation method that can be used to detect and locate near surface damage in concrete structures.

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Subsurface crack determination by one-sided ultrasonic measurements

Corrosion of steel reinforcement in concrete is a common type of damage. The cracks propagate from the steel bar to the surface without giving any visual sign prior to surface crack formation. As long as the surface material is intact, the sensitivity of the longitudinal wave velocity to the subsurface cracks is doubtful. In this paper, cracks were created in steel fiber reinforced concrete specimens by four point bending. Wave measurements took place on the intact surfaces (compression side) using common acoustic emission transducers. Although there was no visual sign of the crack, Rayleigh as well as longitudinal wave velocities clearly decreased relative to those of the sound material. Other parameters like the amplitude and the experimental scatter of the waves were much more sensitive to damage. Numerical simulations were conducted in order to make a parametric study concerning the depth of the sound layer, the propagating wavelength and the measured wave parameters and propose a firm methodology. It is concluded that by scanning a surface with simple acoustic one-sided measurements, the identification of the location of the subsurface damage is possible, while the propagating wave gives information about the depth of the crack.     

层状场地脉动卓越频率对应的理论计算深度研究*

地脉动观测是一种简便有效的场地土层动力特性测试方法。本文依据场地脉动能量中瑞利波为主的特性,基于层状场地瑞利波弥散特征曲线,研究了不同场地条件下脉动卓越频率对应的瑞利波波长与场地自振频率理论计算深度之间的关系。计算结果表明：场地一定深度范围内土层剪切波速差异特性是其主要影响因素。如果土层波速差别较小或者某一波速占主导地位,则理论计算深度与瑞利波波长比值约为1/4a(a为瑞利波波速与剪切波速之比),与均匀场地结果接近;反之,土层波速差异越大,两者比值与1/4a偏离越远,且1/4a为比值上限。