Impact of sputtering and redeposition on the morphological profile evolution during ion-beam etching of blazed gratings

Abstract

Ion-beam etching (IBE) is widely used in the fabrication of high-quality blazed gratings due to its high resolution and directionality, which allows for the control of blazed angles and smooth surface profiles. Throughout the ion-beam etching process, the redeposition of sputtered species onto the wafer occurs, affecting the profile evolution and blazed angle. To investigate this phenomenon in the fabrication of blazed gratings, a self-consistent simulation model utilizing the cellular method has been developed to analyze the etching and redeposition mechanisms in the IBE process. The model yields good agreement with the experimentally observed evolution of the etching profile. By examining the density and velocity distributions of the sputtered species, the coexistence of etching and redeposition is confirmed and explained, highlighting the visually significant role of redeposition. Our model takes into account the “footing effect” that is unavoidable in mask manufacturing, and its impact on the morphology evolution during blazed grating IBE is studied.