Formation of Low-Defect-Concentration Polycrystalline Silicon Films by Thermal Plasma Jet Crystallization Technique

概要

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Defect concentration in polycrystalline silicon (poly-Si) films formed by thermal plasma jet (TPJ) annealing and excimer laser annealing (ELA) has been investigated on basis of the electrical property and spin density ($N_{\text{s}}$). Phosphorus-doped Si films with an average concentration of $4.3 \times 10^{17}$ cm-3 and crystallized by TPJ annealing showed electrical conductivity ($\sigma$) values of $2.0 \times 10^{-3}--7.8 \times 10^{-2}$ S/cm, whereas ELA Si films show much lower $\sigma$ values of $(1.6--4.5) \times 10^{-6}$ S/cm regardless of irradiated laser energy density. $N_{\text{s}}$ values in TPJ annealed Si films were $(2.3--4.5) \times 10^{17}$ cm-3, which are roughly one order of magnitude lower than those of ELA films. These results indicate that dangling bonds in crystallized films are the predominant traps and they strongly govern the electrical property. TPJ crystallization offers the possibility of fabricating poly-Si films with a low defect concentration presumably owing to the much lower cooling rate (${\sim}10^{5}$ K/s) during crystalline growth than that of ELA (${\sim}10^{10}$ K/s). By treating TPJ annealed films with hydrogen plasma for 10 min at 250 °C, a defect density as low as $5.0 \times 10^{16}$ cm-3 is achieved.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-08-25