A multilayer high reflectance coating consisting of Ag, SiO2, and TiO2 with R-vis of 99.3% was successfully designed by simulation based on Maxwell's equations. The authors found that providing the low refractive index SiO2 layer with non-quarter-wave thickness (0.14 of nd/lambda for 550 nm light) near the Ag layer made a leading contribution to this high reflectance. They successfully made a multilayer high reflectance coating of Ag/SiO2/TiO2 on polyethylene telephthalate film with R-vis of 99.4% based on that simulation. A backlight unit with a coating of Ag/SiO2/TiO2 exhibited high luminance 1.04 times that of Ag alone. Ag atoms are mixed with Si atoms upon deposit of a SiO2 layer on Ag in an atmosphere with O-2. A SiO2-P layer deposited under O-2 free conditions from a SiO2 ceramic target and a TiOx layer deposited from Ti work well for protection of the Ag layer from oxidation upon deposit of SiO2. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3269736]