Patent ID: 7614253
Filing Date: 2009-11-10
Classification: C23C,G02B

Abstract:
1. A method of making an optical waveguide having a plurality of layers with different refractive indices, comprising carrying out the following steps in sequence: a) fabricating a first structure resistant to wafer warp during thermal processing by PECVD (Plasma Enhanced Chemical Vapor Deposition), said first structure being fabricated by: b) reducing optical absorption and compressive stress in said buffer layers by subjecting said first structure to a first thermal treatment in the presence of an inert gas, said first thermal treatment comprising: c) depositing a silica core layer having a different refractive index from said first and second buffer layers on said second buffer layer by PECVD to form a second structure comprising in order said first silicon nitride layer, said first buffer layer, said silicon wafer, said second silica nitride layer, said second buffer layer, and said silica core layer; d) reducing optical absorption and tensile stress in said core layer by subjecting said second structure to a second thermal treatment in the presence of an inert gas, said second thermal treatment comprising: