Experimental Research On Micro-EDM Of N-type Heavy-doped Silicon

Semiconductor material has a wide range of application in MEMS field because of its uniqueopto-electronic characteristics. However, semiconductor material, e.g., silicon, is hard and brittle, andvery difficult to be machined by traditional machining method. Electrical discharge machining is akind of non-traditional machining method with no contact force.. According to the demand of microfabrication of high aspect ratio structures of n-type heavy doped silicon material, micro EDM isintroduced in this thesis. The main research work is described as follows:1. The contact resistance is reduced by increasing the contact area between the workpiece andfixture. Array wire electrode is designed and the working liquid circulation system is improved aswell. These measures hope to get a better ability of debris removal and minish abnormal discharge.2. N-type heavy-doped silicon(resistivity0.01cm) ingot is selected to be machined bymicro-EDM and the influence on the work surface and product caused by electric parameters andworkpiece material are studied in this thesis.(1) The influence on the machined surface due to different pulse energy (the minimum dischargepulse energy is about10-7J) are investigated by comparing different electric parameters (open voltageis120V,160V, and pulse duration is0.25μs,2.5μs, respectively), and using SEM method tocharacterize and analys the surface morphology. While the machining efficiency and electrode wearof different machining parameters were studied.(2) The purification efficiency of product was improved by optimizing the discharge debrispurification technology. In comparison to the discharge product of variety electrical parameters, it wasobvious that as the single pulse energy decreased, the discharge crater and product size reducedsignificantly while the surface quality was improved as well.