Characterization of SiO₂ films deposited at low temperature by means of remote ICPECVD

Silicon dioxide films were deposited by means of remote inductively coupled plasma enhanced chemical vapor deposition (ICPECVD) in Ar-N2O-SiH4 plasma at 150 °C and pressures between 1 and 6 Pa. Chemical modeling of our plasma indicated an increased fraction of SiH3 radicals at 6 Pa (compared to SiH2, SiH, and Si species), while at 1 Pa their relative contribution on film growth should be much smaller. Layer growth from SiH3 radicals would result in better dielectric quality. We found that the films contained a high amount of positive charge and exhibited large leakage currents at 1 Pa, while films with lower positive charge and much lower leakage currents were grown at 6 Pa. The deposition rate was ~4.5 nm/min at 1-2 Pa and 3.5 nm/min at 6 Pa. The lower growth-rate at 6 Pa could be ascribed to the formation of denser films, as well as to the changing plasma and surface chemistry. These results were consistent with chemical modeling.