The behavior of incorporated impurities in tantalum anodic oxide films at the dielectric breakdown

Distribution profiles of incorporated impurities in anodic oxide films of tantalum were investigated before and after the dielectric breakdown of the film as a function of the depth of the film for incorporation of phosphorus, sulfur and chlorine. The in-depth distribution profiles of the incorporated impurities dramatically changed at the breakdown of the oxide films. However, the trend of the change was quite different among the incorporated impurities; chlorine is concentrated in the interior of the film, but phosphorus and especially sulfur showed tendencies to be swept into electrolytes. The ionization of the film seems to be responsible for these phenomena.