Rapid Crystallization And Low Temperature Growth Of Polycrystalline Silicon Films Through Mesoplasma Method

Polycrystalline silicon thin film is considered as the key material of the information industry and solar photovoltaic industry,because of its remarkable advantages in optical and electrical properties,and economic cost.Rapid preparation of high quality polycrystalline silicon thin film at low temperature is an important development trend in this field.In many processes at low temperature,H atom is widely identified to play an important role in polysilicon thin film preparation.The mesoplasma process developed recently has been demonstrated to provide the high density of H atoms,which shows great potential in the preparation of polysilicon thin film at low temperature.In this paper,through using the mesoplasma method,a new rapid crystallization process of amorphous silicon thin film without hydrogen has been developed.The important effect of H atoms in crystallization process has also been confirmed.According to the active characteristics of atomic H and unique clusters-assisted rapid deposition,the deposition procedure of polycrystalline silicon films on cheap substrate at low-temperature was investigated.(1)Microcrystalline silicon thin film of high crystallinity can be obtained in a few seconds by annealing one-micron-thick amorphous silicon thin film under Ar-H2 plasma condition,and the substrate temperature is below 600 ?.It was found that both of the high thermal kinetic energy of mesoplasma and high density of atomic H contribute to the rapid crystallization of a-Si films by the thermal and H-induced chemical annealing.The influences of H2 concentration,plasma power density and annealing time on the morphology and crystallinity of the thin films were also investigated.It is suggested that reasonable plasma power density and H atom concentration are the keys to get highly crystalline film in short time.A seriously etched film would be resulted in under the effect of overactive atomic H and prolonged annealing time.The mechanism during the processing was also clarified.(2)Another experiment is about using mesoplasma to prepare polycrystalline silicon thin films on glass substrate at low temperature.Polysilicon thin film with smooth surface can be obtained at 110 ?,and the deposition rate reaches 7.4 ?m/min,about more than an order of magnitude higher than that of conventional CVD technology.The influence of deposition parameter on film quality and deposition rate was also been investigated.Higher radio frequency power can improve the quality of thin films and increase their deposition rate.The film quality firstly increases and then decreases with increasing SiH4 flow rate.If the activity of plasma particles increased,a good-quality polysilicon thin film could be obtained at a lower overall substrate temperature of 85 ?.On the basis of the results of the above-mentioned two series of experiments,it can be concluded that mesoplasma has great advantages in rapid preparation of polycrystalline silicon thin film at low temperature.