Temperature Effects and Mechanisms of the Action of O, N, and F Atoms on SiOCH Nanoporous Dielectrics

Understanding the detailed mechanisms of the action of active radicals on SiOCH nanoporous dielectrics with low permittivity k used as interlayer SiOCH low-k dielectrics in a new generation of integrated circuits is important for developing recipes for reducing the degradation of low-k dielectrics in technological processes of plasma-chemical processing. In this work, the features of these mechanisms of interaction of fluorine, nitrogen, and oxygen atoms with low-k dielectrics with different pore sizes and degrees of porosity are studied experimentally and theoretically. The samples were treated at low temperatures with O, N, and F atoms in plasma downstream of an inductive discharge in O2, N2, and SF6 gases, respectively. Lowering the temperature led to different (for different atoms) slowdowns in the degradation of surface CH3 groups, which ensured the hydrophobicity of the porous medium and low-k values of dielectrics. An analysis of the results obtained using DFT (density functional theory) calculations and ab initio MD (molecular dynamics) modeling of reaction mechanisms revealed branched reactions of atoms with surface Si–CH3 groups and with other sequentially formed groups.