Development of high reflectance insulating film materials for packaging semiconductor optical devices

The high reflectance insulating layer protective film used in semiconductor or display optical devices is made of Bragg Reflection structures formed by repeated overlapping coating of high index metal-containing and low index silicon-containing insulating layers. In this paper, the manufacturing process, baking process, optimization of surfactant formulation of ultralow refractive index Spin-on Glass (SOG) encapsulation insulating layer material, the effect of aging in air on coating defects, and the effect of filtering SOG solution for fine dust on film surface are reported. The minimum refractive index (n) of SOG reported in this paper can be lower than 1.2@633nm wavelength, and the optimum baking process is three steps of low, middle and high temperature baking 80°C/150°C/300°C, respectively. The optimal material weight ratio of surfactant is 1 basic unit. Isolation of water and/or oxygen in the air can eliminate spin coating defects. The fine dusts in the SOG solution resulting in defects on coated film surface is eliminated by re-filtrating the liquid after taken out from warehouse. At present, the SPC data of this material has reached the mass production specification.