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利用在线椭偏仪对非晶碳氢膜进行了光学常数、沉积率和刻蚀率的测量。在无直流负偏压或偏压较小时,薄膜呈现聚合物结构,折射率和消光系数较小;当增加直流负偏压时,薄膜的折射率和消光系数显著提高,所成膜为硬质非晶碳氢膜。在以CH4作为气源进行沉积时,随着偏压的增加,沉积率先升高再降低,在偏压为-100V时,沉积率为最大。H2/N2(30%N2)的混合气体的刻蚀率要比单独用H2作为刻蚀气体的刻蚀率要大。对于CH4/N2(30%N2),在偏压从0V增加到300V过程中,在大约50V时,基底上的薄膜有一个从沉积到刻蚀的转化过程。

Deposition and erosion study on amorphous hydrocarbon films by in situ ellipsometry

The deposition and erosion of amorphous hydrocarbon films by a methane plasma with O2,H2,H2/N2(30% N2) and CH4/N2(30% N2) are investigated by in situ ellipsometry.RF bias voltage could make effects on the optical properties of amorphous hydrocarbon films,actually the refractive index and extinction coefficient increase with the increase of bias voltage.The deposition rate of methane plasmas increases when the bias voltage increases from floating potential to 100V,then it decreases from 100V to 200V.Erosion is most effective in pure O2 plasma.For the erosion experiments using CH4/N2 mixtures,transition from deposition to erosion was observed when bias voltage increased from zero to 300V.