Low-resistance phosphorus-doped Si films through blue laser diode annealing

AbstractThe effect of activated annealing on Si films using a new semiconductor blue laser was studied for application to the thin-film transistor (TFT) system on a panel. As a result of the blue laser diode annealing of the continuous-wave (CW) scanning mode at 500 mm/s for 50-nm-thick heavily phosphorus-doped Si films, drastic crystallization occurred while maintaining the surface's smoothness. By irradiating the laser power between 5 and 8 W for chemical vapour deposition films, the grain size was successively controlled by forming micrograins to large grains as well as to anisotropic long crystal grains. Correspondingly, the resistivity decreased depending on the increase in the electron mobility while the high carrier concentration values were retained for the various grained structures. The dopant activation rate was estimated to be 100% in the Si network in spite of the polycrystalline phase. The heavily doped Si film is expected to be applied to electrodes in high-performance TFTs as an advanced low-temperature polysilicon process on glass or flexible plastic sheets.