Simultaneous ion and electron beam etching for charge-free and low-damage silicon processing

Abstract

The effects of simultaneously generated ion and electron beams on silicon etching in an inductively coupled plasma system equipped with DC-biased grids were investigated. By adjusting the grid voltages, the energies of both ion and electron beams were precisely controlled, enabling charge-free etching through their simultaneous bombardment. Etching experiments on patterned silicon wafers with SiO2 masks revealed that concurrent ion-electron beam irradiation effectively suppresses plasma charging, thereby reducing bowing-like sidewall distortions in the etch profile. Furthermore, surface roughness measurements demonstrated that simultaneous ion and electron beam irradiation significantly decreased surface roughness compared to ion-beam-only etching. These findings indicate that the combined use of ion and electron beams mitigates plasma-induced damage and improves etching profile control, offering a promising method for high-aspect-ratio silicon etching.