Fabrication of Nanostructure via Localized Focused Ion Beam-Chemical Vapor Deposition (FIB-CVD)

Abstract

In the time since focused ion beam-induced chemical vapor deposition (FIB-CVD) process was first introduced in the 1980s, it has become widely used not only for repair of semi-conductors, but also in the fabrication of various micro/nano structure devices including electronic components, sensors/actuators, and even nanomaterials. As the usability of the process increases, many researchers have studied the fundamentals of the process to improve process performances such as precision, efficiency, and purity of the deposited material. Despite these studies, however, due to the sensitive process parameters, and the complicated deposition mechanisms interacting with ions, electrons, precursor gases and a solid substrate, the fundamental mechanism of the process has not been yet clearly defined. The FIB-CVD process is a process in which some components of a precursor compound are deposited on the substrate by chemical reaction of the precursor gas. In general, temperature condition is an important factor in determining the chemical reaction rate. The temperature is inevitably one of the crucial process parameters. Previous studies on the effect of temperature on the process have been reported on the deposition characteristics according to the temperature of the precursor reservoir and the substrate temperature. However, even though the temperature of the precursor gas is directly related to the chemical reaction, little research on this has been done. This is mainly due to the fact that it is difficult to construct an experiment in which only the temperature of the precursor gas is used as a dependent variable at a gas injection system (GIS) responsible for supplying precursor gas. In this study, the effect of precursor gas temperature on FIB-CVD process was investigated from the viewpoint of deposition rate. In order to experimentally explore the influence of the gas temperature, a GIS which can independently control the precursor gas temperature was developed. With the developed GIS, the effect of the precursor gas temperature on the deposition rate of C14H10 precursor in FIB-CVD process was investigated. In addition, to theoretically understand the experimental results, a numerical model of the FIB-CVD deposition mechanism was developed. In order to solve the difficulties of the distance calculation between the deposition surface evolved in real time and the emitted electrons, which was difficult to consider in the conventional numerical methods, the Hausdorff distance concept generally used for object recognition in image processing was firstly adapted. Finally, the shape memory (SMA) based micro bending actuator was fabricated by modifying the deflection behavior of a SMA linear actuator with a localized carbon block deposited via FIB-CVD process using optimized precursor gas temperature.