| 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. |
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