Study on The Theory and Model of Overcut Effect of Focused Ion Beam Etching Process

In focused ion beam (FIB) fabrication process, the scan method is seldom cared about. the choice of scan method can make a difference in the microstructure. In this paper, a proximity effect that is caused by the scan strategy is observed. In order to control the proximity effect, the model of this phenomenon needs to be clarified. To this end, this study proposed a numerical model considering the scan method and dwell time. By catching the transient profile in the fabrication process, a new incident angle relating to the scan method and dwell time is gained, with which the model is expected to estimate the size of the effect. In reality, the calculation results show a good match with experiments of crossed rectangles. Based on the model, we successfully fabricate a slightly complicated but controllable structure that has application prospects in the optical area.