放电功率对VHF-PECVD微晶硅薄膜生长过程的影响

Effect of Discharge Power on the Growth Process of VHF-PECVD Microcrystalline Silicon Films

采用基于有限元的数值模拟方法,研究了VHF-PECVD法制备微晶硅薄膜的等离子体放电和气相反应过程,模拟了放电功率对等离子体特性及气相化学的影响,并与光发射谱(OES)在线监测结果进行了比较。模拟结果表明:当放电功率从30 W增大至70 W时,等离子体中心区域的电子温度T e基本保持不变,电子浓度n e和等离子体电势Φ线性增大;气相中H和SiH3等基元浓度逐渐增大,二者的浓度比n H/n SiH3亦随功率单调增大,模拟结果与OES测量结果吻合的很好。最后,根据数值模拟结果,对实验上不同放电功率下微晶硅薄膜的生长特性进行了解释。

The plasma discharge and gas-phase reaction processes during microcrystalline silicon films deposition by VHF-PECVD were investigated using numerical simulations based on finite element method （FEM）. The effect of discharge power on plasma characteristics and the concentration of species were simulated. The results showed that with the increase of power from 30 W to 70 W, the electronic concentration ne and plasma potential φ in the middle of bulk plasma increases linearly, but the electronic temperature Te keeps constant; the concentrations of both H and Sill3 increases, and the ratio of nH/NSiH3 increase monotonously with the power increasing, which is consistent with the results from optical emission spectroscopy （OES） measurement. At last, according to the numerical results, the characteristics of microcrystalline silicon films growth at different power are clarified.