【作者】 陈欢；

【导师】 张冬仙； 章海军；

【作者基本信息】 浙江大学 ， 光学工程， 2014， 硕士

【摘要】 近年来,纳米科技一直是快速发展的前沿课题之一。原子力显微镜(AFM)因具有极高的分辨率,而且不受样品导电性的限制,而成为纳米科技领域的重要工具。传统AFM的扫描速度慢,严重限制了AFM的应用范围。这主要是由于压电陶瓷扫描器的X、Y、Z向之间存在交叉耦合,使得AFM在快速扫描中获得的图像扭曲失真。针对这种情况,本文在平板扫描器(XY和Z向分离,消除XY和Z向的交叉耦合)的基础上提出了一种基于梳状柔性结构扫描器的快速AFM系统,减小了X和Y向交叉耦合误差,提高了AFM系统在快速扫描下的成像性能。本文从多个方面对该快速AFM系统进行了详细的论述,包括理论方法、系统设计、性能分析和优化及实验应用,主要研究内容和工作如下：首先优化和发展了一种基于柔性结构扫描器的快速AFM的新方法。该方法的优点是用柔性结构扫描器来扫描样品,在实现了XY扫描平面和Z向反馈分离的同时,也减小了X和Y向交叉耦合误差,从而在原理和设计方法上确保了原子力显微镜在快速扫描时能够得到理想图像。基于上述原理和方法,成功研制了新型快速AFM系统。首先,设计并研制了基于柔性结构扫描器的AFM探头,主要包括柔性结构扫描器,Z向反馈控制器。其次,研制了性能良好的Z向反馈控制电路,PSD前置放大电路,压电驱动电路。然后,设计研发了快速数据处理和成像的软硬件系统,采用快速及高精度的数据采集卡来完成样品形貌数据的读入和扫描控制信号的输出、转换,提高数据处理速度。在软件方面,完成基于快速数据采集卡的程序接口移植,由于该卡提供了不同操作系统的驱动,从而确保了AFM系统在不同操作系统之间的可移植性,为AFM的进一步普及打下了良好的基础。对新型快速AFM系统进行了性能分析,并提出了相应的措施来改善系统性能。最后,进行了大量的实验测试工作。包括,对多孔氧化铝、金属玻璃及二维光栅进行慢速高分辨率的扫描成像,对标准光栅进行不同范围的扫描成像,成功获得样品表面微纳米结构图。实验结果证明本系统具有传统AFM精确无误,分辨率高、重复性好等优良性能。最后,对锗量子点进行了快速扫描成像实验,在保证较高分辨率(400×400像素)的情况下,单幅图像的扫描速度最快可以达到20s。针对速度要求更高的应用场景,提出了先进行大范围低分辨率快速扫描,对需要详细观察的部分采用慢速高分辨率扫描的方法,进一步提高系统的扫描速度,拓宽了系统的应用范围。更多还原

【Abstract】 In recent years, nanotechnology has been the rapid development of one of the frontier. Atomic force microscope (AFM) has a very high resolution, and is not limited by conductivity of the sample, and it makes AFM an important analytic tool for nanotechnology. Because of the cross-coupling error between X Y Z directions in piezoelectric scanner, the sample image detected by traditional AFM is warped and distorted in fast speed scanning mode, thus severely limiting the AFM observation of dynamic process. For this case, we proposed a new fast scanning AFM system based on a new kind of comb flexure mechanism scanner, which on the basis of planar scanner that separates the X-direction(or Y-direction) and Z-direction to eliminate the cross-coupling between XY and Z. The new comb flexure mechanism scanner can reduce the cross-coupling error between X and Y directions, to improve the AFM’s performance under fast scanning mode.In this paper, we expound the new fast scanning AFM system in the aspects of theoretical methods, system design, performance analysis, system optimization and experimental technology, the main research works and significance are as follows:In terms of principle and the design, we optimize and develop a new method of fast scanning AFM based on comb flexures mechanism scanner. A significant feature of this method is to use a comb flexure mechanism scanner to driver the sample scan, which not only achieves the separation of the XY plane and Z, but also reduces the cross-coupling error between X-direction and Y-direction.Based on the above principles and new methods, we have developed a fast scanning AFM system on the basis of comb flexure mechanism scanner. Firstly, we developed the AFM probe, including the comb flexure mechanism scanner and the Z-direction feedback controller. Secondly, we designed the PID feedback circuit, the PSD pre-amplifier circuit and the scanning drive circuit. Then, we designed and developed the hardware and software system of fast data processing and imaging. A new data acquisition card with fast-speed and high-precision has been used to achieve the data’s input and output and conversion of the control signals. In addition, we complete the program interface migration based on the new fast data acquisition card. Due to the different operating system driver the card has provided, thus raising the AFM system compatibility with different computer and operating system, this has laid a good foundation for the popularization of AFM.We give the performance analysis of the new fast scanning AFM system and present the optimization scheme, which is certified to further enhance and improve the system’s performances. To test the performance of the system, a large number of experimental tests has been done, which including high resolution imaging of prorous alumina, metglass, two-dimensional grating and different range imaging of standard grating, the images successful show the micro/nano structure of the sample surface. The result shows that the system is accurate, high resolution, good repeatability just as the conventional AFM. At last, we made a series of fast scanning imaging experiments on Ge quantum point. The experimental result shows that we can get the sample image in20s at the resolution of400×400pixels. To meet the demand of imaging faster, we provided a new method, which do the fast scanning in a wide range at low resolution, and for detailed observations of the part on slow high resolution scanning. Thus method further improves the scanning speed of the system, and makes it more useful.更多还原