Etching characteristics of thin SiON films using a liquefied perfluorocarbon precursor of C_6F_(12)O with a low global warming potential

Perfluorocarbon gas is widely used in the semiconductor industry.However,perfluorocarbon has a negative effect on the global environment owing to its high global warming potential(GWP) value.An alternative solution is essential.Therefore,we evaluated the possibility of replacing conventional perfluorocarbon etching gases such as CHF_3 with C_6F_(12)O,which has a low GWP and is in a liquid state at room temperature.In this study,silicon oxynitride(SiON) films were plasma-etched using inductively coupled CF4+C_6F_(12)O+O_2 mixed plasmas.Subsequently,the etching characteristics of the film,such as etching rate,etching profile,selectivity over Si,and photoresist,were investigated.A double Langmuir probe was used and optical emission spectroscopy was performed for plasma diagnostics.In addition,a contact angle goniometer and x-ray photoelectron spectroscope were used to confirm the change in the surface properties of the etched SiON film surface.Consequently,the etching characteristics of the C_6F_(12)O mixed plasma exhibited a lower etching rate,higher SiON/Si selectivity,lower plasma damage,and more vertical etched profiles than the conventional CHF_3 mixed plasma.In addition,the C_6F_(12)O gas can be recovered in the liquid state,thereby decreasing global warming.These results confirmed that the C_6F_(12)O precursor can sufficiently replace the conventional etching gas.