Growth of Low-Temperature Polycrystalline Si Film by Direct Negative Si Ion Beams

Abstract

AbstractPolycrystalline Si (Poly-Si) films were successfully grown at temperature less than 500 °C by using a direct Si ion beam deposition technique. In this process, the ion beam energy of Si- is directly coupled to the formation of the films. High substrate temperature (>600 °C), normally required for conventional CVD techniques, has been a major barrier for the Poly-Si Thin Film Transistor Liquid Crystal Display (TFT LCD) which uses a glass substrate. Thus, the ability to produce Poly-Si film below the glass transition temperature and to control the grain size will make this direct Si- ion beam deposition process a potential alternative technique for future TFT LCD. The grain size dependence on the ion beam energy and substrate temperature was investigated using a Transmission Electron Microscope (TEM). The grain size could be controlled from 0.1 μm to 1 μm at ion beam energies from 10 to 50 eV with a substrate temperature less than 500 °C. The resistivity of the as-deposited film was of the order of 100 Ωcm due to in-situ doping effect.