Development of a low angle forward reflected neutral oxygen beam for materials processing

In the fabrication of new silicon-based devices any process-related damage such as electrical charging and surface modification, remaining during the processing, may cause problems due to the size limitation of the devices. Therefore, less damaging etching processes are required. In this study, a neutral oxygen beam was formed using a low angle forward reflected neutral beam technique and studied to determine the possibility of it being used as an anisotropic etching technique without charging. The degree of neutralization and etch characteristics were also investigated. When an ion beam was reflected at a reflection angle <15° (the angle between ion beam direction and the reflector surface), most of the ions reflected were neutralized and lower reflection angles gave higher degrees of neutralization. Complete neutralization of the ions in the reflected beam could be made by installing a retarding grid system between the sample and the reflector and by applying a potential higher than the maximum ion energy of the beam. Photoresist (PR) etching was carried out with the neutralized oxygen radical flux and anisotropic etch profiles could be obtained suggesting a directional neutral beam.