2004 年 70 巻 11 号 p. 1418-1422
Using the atmospheric pressure plasma CVD (AP-PCVD) technique, polycrystalline silicon (poly-Si) films were deposited at high rates ranging from 0.4 to 7.6nm/s. In order to clarify the deposition process of poly-Si films, the influences of VHF power, concentration of the reactive gases (H2, SiH4), substrate temperature (Tsub) and deposition gap on the deposition rate were studied. Simultaneously increasing VHF power and hydrogen dilution ratio of SiH4 (H2/SiH4 ratio) was found to be the crucial method to improve the crystallinity and also to increase the deposition rate of the film. In addition, it was found that LP was sensitive to H2 concentration in the plasma atmosphere, while it was not affected by SiH4 concentration within the present deposition conditions. These facts suggested that supplying sufficient VHF power enhanced dissociation of H2 molecules, which leaded to effective generation of atomic hydrogen in the plasma, and that the atomic hydrogen played important roles in both dissociation of SiH4 molecules and crystalline Si film growth. It became clear that the deposition rate had positive temperature dependence with extremely small activation energy of 0.036eV. Additionally, the extremely small activation energy implied that a Tsub-independent process partly contributed to the surface reaction. It was also revealed that the deposition rate increased exponentially with decreasing the deposition gap, indicating that the deposition precursors were supplied to the surface by diffusion.
