Wall heating effect on crystallization of low-temperature deposited silicon films from an inductively-coupled plasma

The influence of vessel-wall temperature T-w on the grain size of poly-Si films deposited on a low-temperature (300 degreesC) substrate by an inductively-coupled SiH4/H-2 plasma is investigated. The grain size is reduced after a clean vessel wall at T-w similar to 100 degreesC experiences long SiH4/H-2 discharge. This reduction in the grain size due to SiH4/H-2 discharge duration can be suppressed by heating the wall to T-w similar to 300 degreesC. To understand the mechanism, the H atom density in the plasma is measured from the ratio of H-alpha/H-beta emission intensities. The H atom density is found to decrease monotonically with the discharge time at T-w similar to 100 degreesC, and this H density decrease is suppressed by increasing the wall temperature to similar to 300 degreesC.