Ion-species distribution in a high-current broad beam

Abstract

Summary form only given. A high-current broad ion beam which is extracted with multi-aperture electrodes from a large-volume plasma has come to be required not only for processing the size-growing silicon wafers but also for industrial applications to non-semiconductor materials. In order to study the spatial distributions of fragment ions from the chemical compound as the source material, we constructed a new apparatus equipped with a quadruple mass spectrometer to measure the ion-species distribution in the source plasma. The spectrometer is moved in vacuum, and local ratios of the fragment ions are measured by extracting the ions through small holes which are made on the wall separating the plasma and the spectrometer room. The experiment was carried out with CF/sub 4/ as the source material. The results suggest that the ion-species distributions are not consistent with the electron-density distribution. The ion-species distributions are strongly dependent on the molecule flow of the source material in the plasma chamber, but the electron-density distribution is not.