SOI by CVD: Epitaxial Lateral Overgrowth (ELO) process—Review

Abstract

The ELO process (Epitaxial Lateral Overgrowth), based on the growth of silicon film over an SiO 2 mask by the CVD technique, has been reviewed. The silicon film is locally seeded in openings of the SiO 2 mask from which it overgrows the oxide. The key to success is selective deposition; growth conditions which give growth of silicon over exposed silicon surfaces and at the same time prevent nucleation of silicon over oxide. These conditions, together with growth and surface morphology of obtained ELO films, are discussed as a function of gas composition, growth temperature, growth procedure and type of reactor. Defect structure and electric properties of ELO films are also reviewed together with performance of devices made in these films. Data obtained so far showed that monocrystalline silicon films with smooth mirror-like surfaces and low defect density can be grown over 20 μm wide SiO 2 islands by the optimized ELO process. The performance of devices made in these ELO films was similar to devices made in homoepitaxial layers. On the basis of these data it is believed that the ELO technique is a promising approach for the fabrication of SOI films.