Development Of Scanning Tunneling Microscope And Application For Ultra-precision Surface Measuring

This paper describes the self-developed Scanning Tunneling Microscope (STM) that used for the ultra-precision surface measuring and correlative measuring technology. The instrument have some characteristics such as the simpleness in structure and working mode, the convenience in use, high resolution, the three-dimension image and so on . The main content of this thesis can be described as following:The measuring principle of STM used for the nan- topography measuring on the ultra-precision surface and the measuring methods with different resolution have been dealt with by adjusting the bias and tunnel gap.Based on the relationship of the drive voltage and the displacement of the scanning table, a scanning method with high repeated accuracy , the so called one -way scanning ,is studied by statistical analysis, a real -time scanning technique with function of compensating nonlinear error has been developed and applied. The nonlinear error has been reduced less than 4%.By comparing and analyzing, a control circuit and device have been developed: a scheme of applying analog circuit to realize the feedback control of STM is proposed, at the same time, the design and principle of each element of the feedback circuit are discussed in detail and the parameters of feedback circuit have been compensated; High stabile volts d.c. has been achieved by the prep inter-symmetry circuit that makes up of monopole N-MOS power and P-MOS equivalent circuit which is composed of N-MOS power and amplifier.A new etching circuit of tips for STM and the experiment about this circuit are reported, by experiment several factors, which affect the curvature radius of the tips, are analyzed. The best way to make the tips under the concerned conditions is found.By using the self-developed STM, it is successful to measure sometypical samples, such as: the polished surface of standard samples, hard alloy, grating, different kinds of grinding samples, etc .the nm scale resolution of STM has been verified.By measuring the nan- topography on the ultra-precision surface, we can observe the configuration and limited character of the nan- topography, and know about the ultra-precision machining mechanism and the effect of the factor on the micro-surface that made the machining limitation, and identify the character of the nan- topography. The instrument provided the credible measuring means for ultra-precision surface quality evaluation.According to the several resolutions technique of STM, we have discussed ultra-precision surface character with the technique of fractal dimension and surface quality evaluation.The measuring experimentations have indicated that it is feasible, significative and well-founded for ultra-precision surface quality measuring by STM.