Kinetic model for cavity filling in CECVD of copper

Abstract

A kinetic model is presented to describe the bottom up filling of submicron features in catalyst-enhanced chemical vapor deposition (CECVD) of copper using (hfac)Cu(VTMS) as a copper precursor and iodine as a catalytic surfactant. This model is based on the recently proposed mechanism that explains the accelerated copper film growth at the bottom of the submicron features owing to the accumulation of iodine onto the bottom surface by area reduction as film grows. The dependence of film growth rate on surface coverage of iodine is investigated in advance for quantitative prediction. The growth rate has shown to be proportional to surface coverage of iodine. From XPS analysis and arrhenius plot, kinetic parameters necessary for the linear expression of dependence of growth rate on the iodine coverage was obtained. In this modeling, there is assumed that total amount of iodine is conserved without consumption and surface diffusion of iodine is negligible. Also, saturation of iodine coverage to 1 monolayer and enough supply of copper precursor without depletion within the submicron features are assumed. Based on the assumptions, the geometrical evolution of the bottom up filling in trenches was described by model. Modeling the progression of the first stage of bottom up filling; inclined surfaces growth from bottom corners due to inception of iodine accumulation, impingement at the center of bottom surface, new bottom surface growth up to meet the sidewall at the center of bottom due to impingement of inclined surfaces, and the formation of trench geometry again, was accomplished by considering conservation of adsorbed iodine and symmetry of geometry. After completion of first stage of bottom up filling, because the bottom surface has much higher coverage of iodine than on the sidewall, the shape of bottom growth was approximated by simply planar geometry. By applying kinetic model, the dependence of filling capability on parameters such as iodine coverage, tempera...