Nanofabrication of GLAD Structures – A Comparison of Ion and Electron Beam Deposition Techniques

In this work we have grown slanted columnar thin films, by method of glancing angle deposition, from titanium (Ti) on silicon (Si) substrates using ion beam sputtering (IBS) and electron beam evaporation (EBE) to produce a particle flux which hits the substrate at an angle of approximately 85 degrees. Due to mechanisms of atomic shadowing and limited surface diffusion, these films exhibit a high porosity. Particle fluxes created by IBS and EBE show some significant differences regarding the particle energy distribution, flux rate, and flux angle divergence. We show a comparison between the growth rate, porosity, and slanting angles of the films for different growth methods. To achieve this data, the deposited films were optically analyzed by spectroscopic ellipsometry using an RC2. A model containing an ABEMA layer was built and fitted to the experimental data, providing the physical properties of the thin film. The structural properties from the optical analysis were supported by high resolution SEM images.

In conclusion, EBE provides a higher deposition rate than IBS, but the films show a higher porosity and the columnar structures tend to have a more pronounced fanning, limiting the usability and thickness of the film.