Physical modeling of side wall deposition by inclined electron beam evaporation

Inclined electron beam evaporation is typically used to deposit high-purity metal seed layers for electroplating on complex three-dimensional (3D) structures in semiconductor production. The inclination angle is a key factor in achieving conformal film deposition. Therefore, understanding of the relationship between the inclination angle and the deposited film conformality is of utmost importance for the development of adequate deposition processes. In this work, we have successfully developed a physical model that predicts the conformality of thin films on the sidewalls of various 3D structures deposited using inclined electron beam evaporation. The model covers structures such as bars, circular holes, and square holes. In addition to modeling, inclined electron beam evaporation was experimentally conducted on representative 3D structures. The film conformalities were evaluated from the images of cross sections of the structures in scanning electron microscopy after focused ion beam cutting. The experimental results align well with the outcome of the model. We demonstrate the feasibility to forecast the thin film step coverage on 3D structures deposited by the inclined electron beam evaporation, that is fundamental for selecting the optimal inclination angle.