Mitigation of accumulated electric charge by deposited fluorocarbon film during SiO₂ etching

The charge accumulated potential of a practical SiO₂ contact structure was measured using plasma discharge with wafer monitors. The localized electric potential at the bottom of SiO₂ contact hole differed from that in the surface region. The deposited fluorocarbon in the SiO₂ contact hole functions was determined as an electrical current path between the surface region and the bottom of the contact hole. The result suggest that deposited fluorocarbon film in SiO₂ contact holes could prevent localized charge accumulation in high-aspect contact holes due to the simultaneous occurance of deposition and ion irradiation during plasma etching.