Low-temperature polysilicon deposition by ionized magnetron sputtering

Ionized magnetron sputtering was successfully applied to polycrystalline si licon thin-film deposition on glass substrate at temperatures lower than 25 0 degrees C maintaining a deposition rate of about 133 Angstrom/min. Hydrog en mixing was effective up to Ar:H-2=10:6 by mass flow rate. Prior to depos ition, Hz inductively coupled plasma was used for precleaning the substrate with -40 V bias. During Si deposition, the substrate biasing scheme was in two steps; +20 V for an initial stage and +20 to -40 V bipolar pulse bias for the rest of the deposition time. The crystallinity was evaluated by bot h x-ray diffraction analysis and Raman spectroscopy; the average crystallin e fraction was calculated as 70%. Grain size was measured in plan-view scan ning-electron micrographs after selective etching of the amorphous phase by chemical solution. In 800-nm-thick samples, grains are 500-700 Angstrom il l diameter. Optical emission spectroscopy was used as real-time diagnostics , and ionization of sputtered silicon atoms distinctly increased as the hyd rogen partial pressure increased. The successful deposition of polycrystall ine silicon was explained as being due to enhanced ionization of sputtered and reflected neutrals and resultant energy control by bipolar substrate bi as. (C) 2000 American Vacuum Society. [S0734-2101(00)13104-5].