Based on Lissajous Hierarchical Local Scan to Realize High Speed and Large Range Atomic Force Microscopy

Atomic force microscopy (AFM) is a very useful measurement instrument. It can scan the conductive and nonconductive samples and without any restriction in the environments of application. Therefore, it has become an indispensable micro/nano scale measurement tool. However, because the raster scan method of the conventional AFM could easily induce the mechanical resonance of the scanner and cannot remove the scan area which is not our interest. Under a requirement for a large range and high resolution sample image which however needs excessive scan time, how to overcome such hurdles becomes the main challenge for AFM applications. In this thesis, we try to approach and resolve these problems with self-designed AFM system from three aspects.
First, we use a smooth Lissajous scan trajectory, and apply an advanced controller to realize this kind of trajectory. Since vibration of the lateral scanner will not be induced easily, the scan rate and scan accuracy can thus be increased accordingly. Next, based on the path characteristics of the smooth Lisajous trajectory, we propose a suitable scan algorithm, which initially employs the information on the sample height which the probe is traversing the scan area, and them select the sub-areas of our interest for next phase scan. Overall, such two phase scan reduce the scan time. Finally, considering the varying of sample topography, we provide higher resolution scan on the severe area to improve the scan performance so that a better scan image can be obtained. To validate the effectiveness of the proposed scan methodology, we have conducted extensive experiments and promising results have been acquired.