Optimization of Plasma Enhanced Chemical Vapor Deposition Conditions for Growth of N+A-SI Layer

The N+A-SI:H(NP) monolayer films,a key material in fabrication of thin film transistor liquid crystal display(TF-LCD),were synthesized by plasma enhanced chemical vapor deposition(PECVD) on glass substrate on industrial scale.The influence of the growth conditions:including,but not limited to the RF power,pressure,flow-rate ratio of PH₃/SiH₄,diffuser/susceptor spacing and deposition rate,on the mechanical and electronic properties of the NP layer,such as the stress distribution,thickness,refractive index,transmittance,uniformity of Si-H bond,contents of Si-H/N-H bonds,was investigated with a 4-factor 4-level Taguchi design and experimentally evaluated for optimization of the film growth conditions.The results show that high quality NP layer can be routinely deposited by PECVD on the production line under the optimized conditions:a pressure of 385.7 Pa,a spacing of 20.32 mm,a RF power of 13000 W and a PH₃/SiH₄ flow-rate ratio of 3.12.