Influence of the Redeposition effect for Focused Ion Beam 3D Micromachining in Silicon

The influence of the redeposition effect on the focused ion beam 3D micromachining process of silicon is discussed. Milling of some typical patterns in which redeposition is serious has been carried out. Experimental results are analysed in combination with a theoretical model. It can be seen from the analysis that the order of recycle-milling is very important for 3D microfabrication owing to redeposition during the process. In addition, the parameters of beam current, ion beam spot size, etc. are also key factors in the process. A groove and dome shape will be formed at the root of the sidewall and the bottom of the pattern, respectively, because of the ion sputtering yield bariation and sidewall redeposition. Finally, avoidance methods are suggested as a result of the analysis.