Studies of the Mechanism of Electron Beam Induced Deposition (EBID)

The controlled deposition of metals resulting from the passage of an ion beam through an atmosphere of a suitable precursor gas is a well-established procedure for micro scale materials manipulation. While the ion beam technique is rapid and reliable it has the disadvantage that the beam itself can ablate and contaminate the target with Gallium or other materials, and the fact that ion optics are less widely accessible than electron optical columns. We have therefore been investigating the theory and practice of depositing metal using an electron beam and variety of precursor gases. The aim of this work is to develop techniques that can be applied to the repair of the optical, ultra-violet (UV) and extreme ultra-violet (EUV) masks used in high performance photo-lithography. This thesis is concentrated on electron beam induced deposition (EBID) performed in a commercial Scanning Electron Microscope (SEM). For EBID experiments, we have developed a gas injection system for the specimen chamber of a standard SEM which is able to control the pressure and the delivery flow rate of gas for experiment. Studies of factors that control the properties of the deposition - such as the electron-gas interactions, the effects of gas pressure, and the temperature of the substrate – have been made and experiments to determine the fundamental mechanisms of EBID - such as which types of electrons are responsible for the initial interaction event with the precursor – have been carried out and analyzed and systematically studied to determine the optimum conditions for the practical application of the EBID approach. Finally the practical applications of the EBID have been applied to repair of masks.