Study On The Preparation Process Of Field Emission Seanning Electron Microscopes Cathode

As an important tool for studying the microscopic world, the field emissionscanning electron microscope (FESEM) provides a powerful means to study thestructure of matter in the micro/nano scale, and is widely applied in materialsscience and many other disciplines and quality process control. In recent years,electronic microscopy has made certain progress in China. However, compared withthe overseas, China is relatively weak on the development of electron microscopyespecially stability, reliability and resolution. At present, China has not yet formed anindustrial chain of FESEM. Therefore, there is great significance on the developmentof the high-resolution FESEM. The thesis is about the preparation the field emissionelectron gun cathode emitters, which is an important part of the manufacture thefield emission scanning electron microscope.This paper optimizes the preparation of the cathode process parameters,explores the key technologies to achieve a small radius of curvature of field emissioncathode, assembles Schottky thermal field emitter, and prepares silicon emissioncathode on the basis of the summarization of the related research in the electron guncathode preparation. The main contents are as follows:1. The requirements of the field emission scanning electron microscope tocurvature radius in theoretical calculation: the curvature radius is200~300nm inthe thermal field emission, it is less than100nm in the cold field emission.2. Optimize corrosion process parameters in the case of DC and AC from the aspect of the corrosion voltage, etching solution concentration, electrode distanceand the depth immersed in the solution respectively utilizing electrochemical etchingmethod. We have explored voltage transformation method and the second etchingmethod in the AC and prepared the cathode tungsten tip whose radius of curvatureless than100nm to meet the requirement of the cathode tip curvature radius in thecase of cold field emission.3. In the process of assembling Schottky field emission cathode, we designedthe arc welding method to make the problem of soldering high melting pointmaterial W been solved. In addition, we coated ZrO on the cathode tungsten tipusing the spin coating method, so it reduced the work function cathode emission,increased the emission current and improved the quality of the cathode emitter.4. We have prepared the pyramid-shaped Si based cathode field emitters usingthe conventional semiconductor photolithography and wet etching. Its tip curvatureradius is about100~300nm, and can meet the requirement of the cathode tipcurvature radius of the field emission scanning electron microscope.