Electron Beam Induced Etching

The mechanisms of electron beam induced etching have been studied both experimentally and theoretically. Specifically, a steady-state and a time-dependent continuum model of the process have been developed which uniquely includes the effect of the etch product desorption and diffusion. Both analytical and numerical methods were employed for the modeling, and various experimental designs were used for validation. Initially, a steady-state model was developed to understand an observed so-called “moat” profile which could adequately be described by a finite etch product surface residence time. Subsequently a thorough time-dependent model was written to investigate scanning parameter effects on EBIE. A design of experiments was performed to validate the model and to extract the fundamental parameters for the etching of silica by xenon difluoride. Finally, two technical applications were explored: spontaneous etching passivation on Ta-based extreme ultraviolet lithography masks and carbon nanotube etching.