LOW-TEMPERATURE CRYSTALLIZATION OF AMORPHOUS SI FILMS BY METAL ADSORPTION AND DIFFUSION

We developed a new process for low-temperature crystallization of amor phous Si films, by adsorbing metal ions on the films. Amorphous Si fil ms were deposited by low-pressure chemical vapor deposition, spin-coat ed by metal solutions and subsequently annealed in Ar atmosphere. The amorphous Si films coated with Cu and Au from 1000 ppm solutions almos t completely crystallized at 530 degrees C after 20 h. The fractal siz e of the Cu-adsorbed Si films was 30-50 mu m at 530 degrees C within 1 0 h. The application of Ag, Zn, Fe, Cr and Al solutions did not enhanc e crystallization of amorphous Si films. The enhancement of low-temper ature crystallization by Cu and Au adsorption was deduced from the ele ctronegativity, eutectic temperature and diffusion length. Secondary i on mass spectroscopy analysis indicated that the adsorbed Cu induced c rystallization of amorphous Si films. The field-effect mobility of pol ycrystalline silicon thin-film transistors fabricated using the anneal ed Si films with Cu adsorption was 6-10 cm(2)/V . s before hydrogen pa ssivation.