Effects of ions and electrons in electron-beam-excited plasma assisted CVD on nanocrystalline silicon film properties

Abstract

Nanocrystalline silicon (Si) films are grown from SiH 4 using electron-beam-excited plasma-assisted chemical vapor deposition (EBEP-CVD). In the EBEP-CVD, many ionized radicals are produced due to the high-energy (100 eV) electrons. By analyzing the deposition rate profile in the trench, it is indicated that about 70% of the film is deposited from ionized intermediates. Because many ions contribute to the film deposition, their kinetic energies affect the crystalline properties of the deposited film. Moreover, in the present CVD system, the substrate surface is irradiated with many high-energy electrons, and this irradiation deteriorates the film properties. Therefore, controlling the ion energy and preventing electron irradiation during the deposition are important to obtain good quality thin films, and the highest crystalline ratio (89%) is realized at −15 V substrate-bias voltage by avoiding the high-energy electron irradiation.