Effect of Flow Ratio of T₂B/H₂ on Glow Discharge Plasma Composition and Surface Roughness of Polymer Thin Film

Using trans-two butylene (T₂B) and hydrogen (H₂) as the work gas, the glow discharge polymer (GDP) thin film was obtained at various flow ratios of T₂B/H₂ by low pressure plasma enhanced chemical vapor deposition (LPPE-CVD). The dependence of plasma composition and ionization ratio on the flow ratio of T₂B/H₂ during the deposition of film was investigated using mass spectrometer. As well as, white-light interferometer (WLI) and scanning electron microscope (SEM) were employed to determine the dependence of the surface roughness and surface morphology of GDP thin film on the flow ratio of T₂B/H₂. The results show that the ionization ratio of plasma increases at first and then decreases with increase of the T₂B/H₂ flow ratio. At the T₂B/H₂ flow ratio of 0.8∶10, the dissociation degree of precursor and the number of ion fragment reach the maximum. With the increase of the T₂B/H₂ flow ratio, the surface roughness decreases at first and then increases. At the T₂B/H₂ flow ratio of 0.6∶10, the surface root-mean-square roughness R_q reaches the minimum of 39.1 nm.