Control of Hydrogen in Si and its Application to Thin Film Transistor

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We have investigated hydrogen states in silicon and have developed a control method of hydrogen in Si for making the quality of Si films for various devices such as thin film transistors on glass much better. One of the most important results obtained in this study is that B acceptor is more easily passivated by hydrogen atom than P donors in crystalline Si. This was demonstrated by the experimental results that several B-related Si-H bonding centers were observed for me first time by Raman scattering measurements after hydrogen atom treatment, but no P-related Si-H bonds were detected. Secondly, we found that some kinds of multivacancies are stable up to 600 ℃ by measuring Raman scattering of hydrogen molecules and Si-H in hydrogenated Si after thermal annealing of ion implanted samples. According to theoretical calculations, the candidates of the multivacancies are 6 or 10 vacancies. We have also investigated the correlation between H amount measured by SIMS and S-H bonding centers done by Raman scattering method for amorphous Si including various levels of high density of hydrogen. It is found that Raman scattering measurement can be a simple method for estimating approximately the amount of incorporated hydrogen. However, it was impossible to detect Si-H after polycrystallization attained by excimer laser annealing, probably due to surface roughness produced by laser annealing of amorphous Si on glass.