FORMATION OF DIELECTRIC MULTILAYER FILM

摘要

PURPOSE:To form a dielectric multilayer film without increasing leak current by evaporating a protective thin film between a dielectric film which is difficult to be formed by evaporation such as an SixNyOz film and the end surface of a semiconductor optical element. CONSTITUTION:On a semiconductor substrate 1 (assume, refractive index n1 = 3.46), an Si3N4 layer 3 (refractive index n3 = 1.89) of h3 thick is formed after an SiO2 evaporation film 2 (refractive index n2 = 1.50) of h2 thick for protective thin film is loaded. Consequently, even if the protective thin film 2 of several hundreds Angstrom thick with material such as SiO2 wherein the refractive index is smaller than that of the Si3N4 or the semiconductor substrate is evaporated between the Si3N4 film 3 and the semiconductor substrate 1, reflection factor of 0.1% or less can easily be realized.