Elimination of Protruding O-Ring Girdle at Waist of Dry Etched Via: A Methodological Study

We experimentally addressed the problem that the protruding O-ring girdle defect formed at the waist of via,fabricated by inductively coupled plasma etching of the PVX-layer on glass substrate pre-covered with patterned organic film,for fabrication of thin film transistor liquid crystal display.The influence of the etching conditions,including the pressure,plasma energy,flow-rate of oxygen and ratio of SF₆/O₂ flow-rates,on formation of the protruding O-ring was investigated with scanning electron microscopy.The results show that the O₂-plasma had a major impact.Specifically,the O₂-plasma,forming in O₂-rich atmosphere,turned the SiNx(in MultiGI and 1^st-GI layers) into etch-resistant SiON and SiO₂ layer,resulting in formation of the hard protruding,irregular etch-resistant O-ring girdle.We suggest that optimization of the SF₆/O₂ flow-rate ratio and partial pressure and concentration of O₂ may be the total solution.