High rate deposition of poly-Si thin films at low temperature using a new designed magnetron sputtering source

We have deposited poly-Si thin films on Si(100) and glass substrates at growth temperature of below 400°C using a newly developed high rate magnetron sputtering method. To improve the sputtering yield and the growth rate, a high power (10–30 W/cm2) magnetron sputtering system was designed and constructed. Based on the results of computer simulation, we built up the magnetron sputter source with unbalanced magnetron and Si ion extraction grid. The maximum deposition rate reached was 0.35 μm/min due to a high ion bombardment. This is five times higher than that of conventional sputtering methods, and the sputtering yield was also increased up to 80%. The best film was obtained on Si(100) surface using Si ion extraction grid under 9.0×10−3 torr of working pressure and 11 W/cm2 of the target power density. The electron mobility of the poly-Si film grown on Si(100) at 400°C with ion extraction grid was 96 cm2/Vs. In this study, however, we found that the target power density is a more important factor than working pressure to influence the growth rate, mobility, and the film quality. During sputtering, moreover, the characteristics of Si sputter source were also analyzed with an in situ Langmuir probe method and optical emission spectroscopy.