Fabrication of three-dimensional microstructures by two-dimensional slice by slice approaching via focused ion beam milling

A direct programming control approach for fabrication of three-dimensional (3D) microstructures by-use of focused ion beam (FIB) milling is put forth in this article. The previously reported Vasile mathematical model was simplified by our model of constant dwell time and sputter yield during the milling process. Milling of the 3D microstructures can be transferred to the milling of many discrete two-dimensional (2D) slices with thin and constant thickness. The 3D milling can be completed by the direct FIB 2D milling slice by slice with the same layer thickness. The number of the slices can be determined according to maximum depth of the 3D microstructures. The milling depth for each slice depends on the slice thickness. The simplified model and process parameters can be written in a program code running in the FIB equipped computer. The whole process can be performed automatically after adjusting the focusing status of the ion beam on the sample. It was shown by the experimental results that the method has the advantages of simple mathematical model, less memory space used, and fast milling speed. (C) 2004 American Vacuum Society.