Study on The Stability of Lightly Doped Phosphine N+A-SI Film Formation In PECVD Process

We experimentally addressed herein the common deposition interruption problem in synthesis of lightly PH₃-doped a-Si:H(N+A-SI) coating,an Ohm contact material for fabrication of Thin Film Transistor-Liquid Crystal Display,by plasma enhanced chemical vapor deposition.The influence of the phosphine(PH₃) flow-rate,electrode-distance and characteristics of RF power supply on the largest reflected power was investigated.The results show that the electrode-distance significantly affected the Max reflected power.So,the electrode-distance should be slowly decreased,0.25 mm at a step,to somewhere in 20.875~21.875 mm range depending on the specific situation.Test result show the optimized electrode-distance is capable of keeping the largest reflected power below 3000 W and of effectively solving the deposition interruption problem.