Patent ID: 7248773
Filing Date: 2007-07-24
Classification: B82Y,G02B,H01L

Abstract:
1. A method of forming a thick waveguide having a tapered region that includes a fine tip, comprising: on a substrate, providing a film stack that includes a high refractive index core and a low refractive index cladding layer; depositing a dielectric sandwich layer on said stack; depositing a hard metal mask on said dielectric sandwich layer; depositing and patterning a photoresist layer on the metal hard mask layer and then forming a metal hard mask having a first minimum width; anisotropically etching all exposed areas in a vertical direction and then removing any residual photoresist; and then removing said metal hard mask and isotropically etching, using a wet chemistry etchant that preferentially etches said film stack relative to said sandwich layer, whereby said film stack acquires a second minimum width that is less than said first minimum width.