B13-P-03Fabrication and characterization of silicon field emission tips for miniature field emission electron microscope

Abstract

In this study, we used MEMS (Microelectromechanical Systems) process to fabricate an array of field emission tips. It will be applicable to be used for miniature field emission gun scanning electron microscope. Integration the array tip with accelerating electrode and electrostatic lens to complete miniature field emission gun is in progress. Fabrication process of field emission device includes Si tips array and glass anode plate are given followed. First, Si tips array are formed mainly by RIE [ 1 ]. The effect of over-etched on the apex of Si tip is not evident. It has main effect on the shape and the uniformity of Si tips. The aspect ratio and the cone angle of apex can be modified by varying the pressure and the ratio of flow rate of etching gas and diluted gas. Second, different with the standard fabrication process of etched-gate Si tips array [ 2 ] [ 3 ], we design a fabrication process utilizing the wet etching by HF for glass anode plate. The distance from Si tip to glass anode plate can be modified by varying the etched depth in the fabrication process. In the end, experimental field emission device is constituted by the silicon tips and the glass anode plate. The results are analyzed by field emission theory to obtain field enhanced factor (β) and effective emission area (α).