A Study of the Dissociation State and the SiO2 Etching Reaction for HF Solutions of Extremely Low Concentration

The conductivities of HF, VF, and KHF 2 solutions have been measured at very low concentrations. The concentration of HF 2 - ion, a dominant ion in the SiO 2 etching process, has been calculated from the measured F - concentration in HF and KHF 2 solutions. The dissociation state of HF in HF solution has been classified into three regions as a function of initial HF concentration. Etching caused by a high concentration of F - ions was followed along with the conductivity of KF solution for a thermal SiO 2 film. Further, with HF and KHF 2 , solutions, the etching rate for a thermal SiO 2 film was a function of the HF 2 - concentration