Measurement Of Atomic-force Microscope

Atomic Force Microscope (AFM) is one of most important tools in nanotechnology. This thesis is concentrated on the theoretical and experimental researches on metrological AFM, which include the building of metrological atomic force microscope, the analysis of error sources, the calibration of metrological atomic force microscope, and the manufacture and measurement of nano geometric references. The main work of the thesis includes the follows.1. The measuring mode, measuring method of the cantilever position, scanner and the metrological system are theoretically analyzed. It is pointed out that a metrological atomic force microscope should 1) use the scanner consisting of flexure hinges and piezo stacks; 2) have three dimensional laser interferometer system.2. A metrological atomic force microscope has been developed. A confocal sensor for positioning the cantilever, a scanner with three dimensional monolithic flexure hinges have been theoretically and experimentally analyzed. An Abbe-error free three dimensional laser interferometer has been realized. Because of using the distributed control system, the measuring speed has been improved. A new scanning method for the x direction has been proposed, which can be called self-adaptive speed scanning method and can use different scanning speeds according to the surface topography. The new method reduces the requirement for the frequency response in z direction greatly and ensures relative high measuring speed in the mean time.3. The influences of environment, such as temperature, humidity, vibration etc, have been analyzed. It is especially pointed out that the variation of temperature influences the instrument rather than the artifacts. The measuring error coming from geometric shape of the tip has been analyzed. The surface reconstruction methods have been expatiated and the calculation formulas have been given.4. The calibration and compensation of positioning errors have been fully analyzed and studied. The moving mode of the scanner has been built. A new concept - total space calibration has been proposed. Both the single axis calibration and the total space calibration have been used in the metrological atomic force microscope, and work quite well. The calibration method for the cantilever has been proposed and realized. Thus all the data obtained from metrological atomic force microscope can be traced to the laser wavelength.5. Sets of step height references and line width references have been developed. The comparison measurements have been carried out among Physikalish Technishche Bundesanstalt (PTB), Germany, National Institute of Metrology (NIM), China, Microelectronic Center of Chinese Academy of Science and Huajing Microelectronic Co. The metrological atomic force microscope has been used for the international comparison of step height references and two dimensional gratings. The standard calculation methods and the standard measurement uncertainty evaluation procedures have been proposed for above two types of artifacts.6. The metrological atomic force microscope has been assessed by the experts from the State General Administration for Quality Supervision and Inspection and Quarantine, China, and will work as the highest national metrological reference instrument for the calibration of step heights and pitches.