Study on CF₄/O₂ plasma resistance of O-ring elastomer materials

The CF₄/O₂ plasma resistance of the O-ring elastomer samples was investigated using a microwave-excited surface-wave plasma source. The elastomer samples include a fluoroelastomer (FKM) and a perfluoroelastomer (FFKM), both of which are widely used for plasma process equipment. In semiconductor manufacturing, the CF₄/O₂ plasma was widely used for plasma etching and cleaning processes. To investigate the relation between the plasma resistance of the elastomers and plasma parameters, the Langmuir probe measurement was carried out. The kinetic energy of bombarding ions was increased by applying an rf power to a wafer substrate in some of the experiments. The results suggested that both FKM and FFKM were eroded by the low-energy (less than 10 eV) ion bombardment. The kinetic energy of bombarding ions was also a dominant factor to determine the amount of erosion of both the FKM and the FFKM elastomers. In addition, it is suggested that neutral radical attacks were also a dominant factor to increase the erosion of the elastomer for the FKM elastomer, whereas the stability of the FFKM elastomer against neutral radicals was much better than that of the FKM elastomer.