Electron impact ionization cross-sections of carbon-fluorine environmental gases for photolithography

Abstract Fluorocarbon working gases have been extensively utilized in ‘dry’ patterning techniques during photolithography in recent years. The ionization cross-sections of these gases are essential for simulating plasma processes in commonly used in plasma modeling software, such as COMSOL Multiphysics, ANSYS Fluent and BOLSIG +. While the electron impact ionization (EII) of C x F y molecules has been widely studied, there is still limited data on the EII cross-sections for C x F y molecules containing oxygen and nitrogen atoms. Using density functional theory, we adopted the binary-encounter-Bethe (BEB) method to calculate the EII cross-sections of seven C x F y molecules with oxygen and nitrogen atoms, resulting in a total of 21 molecules analyzed. We examined the effect of the electron propagator theory (EPT) correction on the EII cross-sections of these 21 fluorocarbon compounds. Our findings indicate that utilizing the Hartree–Fock wavefunction to calculate the molecular orbital binding energies, and substituting the first orbital binding energy with the ionization energy derived from a complete basis set, yields BEB cross-sections that align closely with experimental data, even without the EPT correction. We present a portion of the EII cross-sections for these C x F y molecules containing oxygen and nitrogen atoms. The discrepancies at the peak of the two BEB cross-sections for molecules with oxygen and nitrogen atoms remained within 5.8%.