亚纳米精度长度溯源计量型动态模式原子力显微镜

通过与长度溯源三轴激光干涉仪测量系统结合,设计开发计量型动态模式原子力显微镜(AFM).此AFM系统中,三轴激光干涉仪系统用于实时测量AFM测头与试样的相对位移.激光干涉仪系统的x,y,z测量轴正交于AFM探针顶端附近的一点,基本可以避免系统的阿贝误差,使AFM具有极高的测量精度.除此之外,扫描过程中三轴激光干涉仪系统还用于工作台x,y方向位移的反馈控制,完全克服AFM中压电器件的缺陷对水平尺寸测量的影响.分析表明,在对纳米标准栅的平均栅距测量中,AFM系统达到亚纳米的测量精度.     

复合型超精密表面形貌测量仪

研制了基于同一显微镜基体实现原子力探针扫描测量与非接触光学测量两种功能的复合型超精密表面形貌测量仪.分析了基于白光显微干涉原子力探针的测量方法、探针微悬臂变形量与白光干涉条纹移动量的关系以及探针微悬臂测量非线性误差的修正方法,和通过融合垂直扫描系统的位移量和悬臂梁变形量得到了原子力探针的工作方式.研制了三维精密位移系统...     

双成象单元扫描探针显微镜在纳米计量中的应用

研制了用于纳米计量的双成象单元扫描隧道显微镜一原子力显微镜，由扫描隧道显微镜参考单元和原子力显微镜被测单元组合而成。两者共用同一XY扫描器，同时对参考样品石墨和被测样品扫描成象。得到的石墨原子晶格参考图象与被测样品图象横向尺度相同，计数前者的原子晶格个数，即可精确测定被测样品图象的尺寸。利用本方法可对任何样品表面的超微观结构进行严格的纳米计量。     

基于三次样条插值法的干涉仪反射镜面型值误差分析

根据激光干涉仪测量位移的原理,分析了工件台干涉仪系统的测量位移的原理,由于激光干涉仪反射镜因为加工制造有缺陷从而会产生测量误差,以及设计出了干涉仪反射镜面型误差计算方法。最后利用三次样条插值函数算法对模拟的运动台位置进行仿真分析,得到在±0.2m行程范围内,YMX面型值的最大误差在1.68×10-10m,XΦZ最大误差的值是1.06×10-6rad,这种方法可以为实际工程应用提供参考价值。     

基于AFM的微位移测量新方法研究

提出了一种测量物体微位移的新方法。原子力显微镜作为测量工具,样品和扫描器置于待测物体上,物体每移动一定距离就由AFM扫描获得一幅样品图像,由此获得一系列连续的序列图像。采用模板匹配方法检测相邻序列图像的偏移,从而可计算出物体的微位移。实验结果表明,用该方法还可实现物体二维方向的微位移测量,且精度达到纳米量级。     

微尺寸探针测量技术

原子力微探针具有极高的垂直方向位置灵敏度,其针尖半径可达几十纳米量级,这就为微纳米尺度的三维坐标测量提供了可能性.本文基于原子力微探针瞄准原理并结合二维微位移系统和高精度电容传感器,研制了微尺寸测量系统.     

基于压电陶瓷管扫描器的大范围纳米定位系统

提出一种基于压电陶瓷管扫描器的X-Y二雏大范围纳米级定位系统,该系统利用摩擦力和惯性使样品产生步进式的微位移.阐述了该系统的设计和工作原理,并给出了它在原子力显微镜中用于探针一样品间的定位控制的应用实例,取得了理想效果.     

激光追踪仪的基本原理及应用

介绍了激光追踪仪(Laser Tracer)的工作原理、结构特点以及误差修正方法。在工作原理方面,内部的激光干涉仪测量出Laser Tracer与安装在数控装备运动轴上靶镜之间位移的变化量,来对数控装备的运动误差进行计算。在结构特点方面,通过使用标准球反射镜与万向节式回转轴系,减小系统误差对测量精度的影响。在误差修正方面,利用多基站下的全球定位系统(Global Positioning System,GPS)原理确定各基站在数控装备坐标系下的坐标,并通过对数控装备运动误差的计算,分离出每一根轴的各项几何误差,同时合成数控装备在空间任意位置的误差,从而实现对数控装备误差的修正。     

双探针原子力显微镜视觉对准系统

传统的原子力显微镜（AFM）受针尖形状和放置方式的影响很难测量线条的宽度和两个侧壁的形状,故本文提出采用双探针对顶测量方案来消除AFM针尖形状对测量结果的影响。介绍了一种基于机器视觉的双探针原子力显微镜对准系统,该系统将两个探针接触到一起,实现了双探针在三维方向上的对准。系统采用具有亚微米级分辨率的镜头,配合高分辨率的CCD来获得探针的清晰图像,用于在水平和垂直两个方向实时监控双探针的运动情况。采用基于石英音叉式的自传感自调节的原子力探针,无需外加光学探测系统,缩小了系统体积,避免了杂散光对视觉对准系统的干扰。最后对针尖进行了亚像素边缘提取,精确地获取了探针之间的相对位置,实现了亚微米级的双探针对准（1 μm以内）。该结论由探针之间距离与幅度/相位曲线得到了验证。     

纳米管探针机械性能在纳米表征中的优势研究

碳纳米管探针是原子力显微镜新一代探针,在纳米表征领域有重要的应用价值.本文系统的研究了碳纳米管原子力显微镜探针和普通硅探针的机械性能对探针表征能力的影响.通过对比两种探针的耐磨损实验及对小鼠IgG蛋白成像研究发现,碳纳米管探针具有良好的弹性弯曲能力,耐磨损,而且能显著减小成像时对柔软的生物样品的损伤.发现纳米管探针具有很好的塑性,利用聚焦离子束的照射可以精确优化纳米管探针的角度,解决了碳纳米管探针角度精确调控的技术瓶颈,充分发挥纳米管探针的高分辨率优势.     

Multi-probe scanning system comprising three laser interferometers and one autocollimator for measuring flat bar mirror profile with nanometer accuracy

This paper describes a multi-probe scanning system comprising three laser interferometers and one autocollimator to measure a flat bar mirror profile with nanometer accuracy. The laser interferometers probe the surface of the flat bar mirror that is fixed on top of a scanning stage, while the autocollimator simultaneously measures the yaw error of the scanning stage. The flat bar mirror profile and horizontal straightness motion error are reconstructed by an application of simultaneous linear equations and least-squares method. Measurement uncertainties of the flat bar mirror profile were numerically evaluated for different installation distances between the laser interferometers. The average measurement uncertainty was found to be only 10 nm with installation distances of 10 and 21 mm between the first and second, and first and third interferometers, respectively. To validate the simulation results, a prototype system was built using an X–Y linear stage driven by a stepper motor with steps of 1 mm along the X direction. Experiments were conducted with fixed interferometers distances of 10 and 21 mm, as in the simulation, on a flat bar mirror with a profile known to an accuracy of λ = 632.8 nm. The average value of two standard deviations (95%) of the profile calculated over ten experiments was approximately 10 nm. Other results from the experiment showed that the system can also measure the yaw and horizontal straightness motion errors successfully at a high horizontal resolution. Comparing with the results measured by ZYGO's interferometer, our measured data excluding some edge points showed agreement to within approximately 10 nm. Therefore, we concluded that our measurement profile has an accuracy in the nanometer range.     

An integrated approach to piezoactuator positioning in high-speed atomic force microscope imaging

In this paper, an integrated approach to achieve high-speed atomic force microscope (AFM) imaging of large-size samples is proposed, which combines the enhanced inversion-based iterative control technique to drive the piezotube actuator control for lateral x-y axis positioning with the use of a dual-stage piezoactuator for vertical z-axis positioning. High-speed, large-size AFM imaging is challenging because in high-speed lateral scanning of the AFM imaging at large size, large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects--the nonlinear hysteresis and the vibrational dynamics of the piezotube actuator. In addition, vertical precision positioning of the AFM probe is even more challenging (than the lateral scanning) because the desired trajectory (i.e., the sample topography profile) is unknown in general, and the probe positioning is also effected by and sensitive to the probe-sample interaction. The main contribution of this article is the development of an integrated approach that combines advanced control algorithm with an advanced hardware platform. The proposed approach is demonstrated in experiments by imaging a large-size (50 microm) calibration sample at high-speed (50 Hz scan rate).     

Metrological atomic force microscope using a large range scanning dual stage

We developed a metrological atomic force microscope (MAFM) using a large range scanning dual stage and evaluated the performance in the measurement of lateral dimension. AFMs are widely used in nanotechnology for very high spatial resolution, but the limitation in measurement range should be overcome to expand its application in nanometrology. Therefore, we constructed new MAFM having a large measurement of 200 mm × 200 mm by using a dual stage and an AFM head module. The dual stage is composed of a coarse and a fine stage to obtain large scanning range and high resolution simultaneously. Precision surfaces and PTFE sliding pads guide the motion of coarse stage, drove by a fine pitch screw and DC motors. Flexure hinges and PZT actuators are utilized for the fine stage. Multi-axis interferometers measure the five degrees of freedom motion of the dual stage for the position control and the compensation of parasitic angular motions. The vertical displacement of AFM tip is measured by a built-in capacitive sensor in the AFM head module within the range of 38 μm. The performance of the dual stage was evaluated and the expanded uncertainty (k = 2) in the measurements of 1-D displacement L was estimated as $ U(L) = \sqrt {(2.8nm)^2 + (3.0 \times 10^{ - 7} \times L)^2 } $ U(L) = \sqrt {(2.8nm)^2 + (3.0 \times 10^{ - 7} \times L)^2 } . The relative uncertainty in pitch measurement was less than 0.02 % and the improvement of accuracy was verified by comparing with other MAFM, which are mostly due to the expansion of scan range and the compensation of angular motion. To enhance the performance, we will reduce the vibration and examine the motion of stage in the vertical direction during a long range scan.     

原子力显微镜管式扫描器运动学建模与误差分析

针对样本扫描模式原子力显微镜,对其管式扫描器-样本-探针系统进行了运动学分析,建立了该系统的运动学模型,该模型表明:对于给定原子力显微镜扫描器,样本上与探针接触点的横向和纵向位移取决于探针尖端相对于扫描管轴心的偏置量、所加电压(或名义扫描范围)及样本厚度。据此模型,对由于弯曲运动模式所产生的两种重要误差—交叉耦合误差及扫描范围误差进行了定量分析,分析表明:扫描范围误差主要受样本厚度及名义扫描范围影响,而Z向交叉耦合误差主要受探针偏置量及名义扫描范围影响,实验验证了所建立的运动学模型和误差计算公式的正确性;另外,还提出了相应的减小误差的方法。     

Traceable calibration of transfer standards for scanning probe microscopy

A Metrological Atomic Force Microscope (MAFM) has been constructed for the traceable calibration of transfer standards for scanning probe microscopy. It uses optical interferometry to generate image scales with direct traceability to the national standard of length. Three interferometers monitor the relative displacements of the AFM tip and sample in the x, y and z directions and the interferometer data is used directly to construct 3D images of sample surfaces. Traceable dimensional measurement of surface features may then be derived from the image data. This paper describes the MAFM instrument and presents a measurement uncertainty budget. Examples are given of measurements of pitch and step height on calibration transfer standards for scanning probe microscopy.     

光纤F-P微位移测量实验研究

利用光纤自聚焦透镜作为F-P干涉仪的反射面,根据F-P干涉光谱相邻波峰之间的波长差与其干涉腔长之间的关系,实现微位移的测量。克服了光强型F-P传感器测量结果受光源波动影响、难以识别位移方向等缺点,可直接测量绝对位移,并可识别位移方向。经实验得到其位移测量误差小于2.5nm。     

纳米精度二维工作台测量镜的面形误差在线检测

针对二维工作台测量镜本身的面形误差以及装调等因素引起面形变化对二维工作台定位精度的影响,提出了一种用于纳米精度二维工作台测量镜面形误差的在线检测方法。利用两路激光干涉仪检测面形微分数据的基本原理,分析了零点误差和积分累计误差对测量镜面形误差检测的影响并提出了改进方法。利用三路激光干涉仪组成两组不等跨度的检测机构,得到两组工作台测量镜面形的原始数据,通过这两组数据之间的关系修正跨度间的面形细节误差,得到了精确的测量镜面形误差量。对此方法进行了理论推导、仿真计算和实验验证,并将结果与Zygo干涉仪测量得到的离线检测结果进行了对比,结果显示其差异在±10nm之间,且趋势有较好的一致性。得到的结果验证了提出的方法可正确测量和真实地还原测量镜的面形误差。     

基于 LSTM 的矩形纳米光栅 AFM 图像复原方法

原子力显微镜(AFM)利用探针与待测物之间的交互作用力进行成像,通过获取矩形纳米光栅计量标准器具的高分辨率成像得到相关的几何量参数并进行标定,实现从标准计量器具到工作计量器具的量值传递。在AFM扫描过程中,由于针尖的影响作用,使得扫描所获图像是探针和样品共同作用的结果,而不是样品形貌的真实描述。针对这一现象,本文提出了一种基于长短期记忆网络(LSTM)的AFM图像复原方法,该方法对通过膨胀法获得的仿真图像各扫描行进行训练,进而获得适用于矩形纳米光栅AFM图像复原模型。实验结果表明,针对线宽20 nm,高40 nm的矩形纳米光栅,经过该方法复原后光栅线宽的相对误差为7.40%,相较于传统的复原方法进一步提高了测量准确度。     

Development of a one-dimensional differential deposition system for X-ray mirror figure correction

A thin-film deposition system was developed for the surface coating of X-ray mirrors of up to 1 m in length. With two coating process areas and four sputtering cathodes, various combinations employing a single layer, multilayered, and co-sputtered thin films are possible. Furthermore, it is possible to correct and modify the mirror surface shape by controlling the speed of the substrate stage. In this study, to evaluate the performance of the proposed coating system, the static coating distribution was measured to check the vertical direction. In a 10 mm area, a 0.9% peak-to-valley error and 0.2% root mean square error occurred. A differential deposition test was also performed for the horizontal direction (stage scan direction). In this study, arbitrary shapes were deposited on 100-mm and 400-mm-long mirrors. After removing the measurement error, the deposition error was less than 1 nm (peak-to-valley). The results demonstrate that this system can correct the surface of an X-ray mirror with ultra-high precision.     

考虑摩擦力及试样表面倾角的原子力显微镜扫描模式

原子力显微镜(Atomic force microscopes,AFM)接触模式下的测量结果因受样本表面倾角和针尖一样本表面间摩擦力的影响而存在较大的测量误差.为避免针尖-表面间的摩擦力对AFM测量试样表面形貌的影响,并能够准确测量表面倾角,提出了一种新的AFM工作模式--消除倾角和摩擦力影响模式.在这种工作模式中,扫描方向垂直悬臂的长轴方向,通过测量悬臂的竖向和横向偏转而得到针尖所受的竖向和横向力,并计算得到针尖-试样表面间的van der Waals力及试样表面局部倾角,然后结合针尖项点和扫描器的位置及针尖-试样表面间距可以得到试样表面形貌的测量结果.在上述工作模式下,针尖-试样表面间的摩擦力是可控的,能够避免针尖或试样的损伤.仿真结果证明了这种方法的可行性.