Research on atomic force microscope using photothermal vibration and optical detection of micro cantilever

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In this research, a new atomic force microscope based on a photothermal vibration of force sensing cantilever was developed. A surface profile of sample is obtained by scanning the fine needle tip over the sample so as to maintain a force derivative applied to the tip. The force derivative is detected by the use of loCK-in amplifier of which reference frequency is that of photothermal vibration of the cantilever. In the term of research project, we have obtained the results as follow.1) The cantilever was fabricated by a laser assisted etching.2) The atomic force microscope (AFM) system was constructed. The tripod scanner composed of stacking PZTs is used as a fine positioner, and the motorized micrometer is also used as a coarse positioner. The vibration of the cantilever caused by a amplitude modulated laser diode was detected by the optical deflection method with He-Ne laser. The system was mounted on the vibration isolation table. The feedback circuit including the interface of personal computer was constructed.3) In order to estimate the lateral and vertical resolution of the AFM, the samples of known structure around the size of submicrometer was observed by the AFM. As a result the lateral and vertical resolution of the AFM was 2 and 50 nm, respectively.