The stability of SiO 2 films prepared using a magnetron sputter type negative ion source (MSNIS)

Abstract

Aging effect of SiO 2 films was investigated. SiO 2 films were prepared using a magnetron sputter type negative ion source (MSNIS) utilizing the direct ion beam deposition (DIBD) method. Thin SiO 2 films are known as suffering from aging effect after the deposition. To minimize the variation of the refractive index or thickness of the film after the long period of time, a dense film is desirable. The optical properties such as refractive index ( n), extinction coefficient ( k) and thickness were analyzed using an UV spectrometer-combined thin-film measurement system. The surface morphology and roughness were measured using an atomic force microscope (AFM). The thickness and refractive index variance after 1-month period was less than 3% for the 100 nm thickness films. The average roughness of the film on silicon substrate was less than 1 nm in most cases. The resultant films show that the film properties were strongly dependent on the ion beam energy and oxygen partial pressure of deposition. In high power density (3.2 W/cm 2), the aging effect was more noticeable. The wet-etch test of SiO 2 films with respect to Cs flow rate showed that Cs flow rate is an important parameter in operation of a MSNIS.