Back to results
US 7,248,773 B2Granted
Method to trim and smooth high index contrast waveguide structures
AssigneeAgency for Science, Technology and Research
InventorsChang Kuo Chang, Chi Fo Tsang, My The Doan, Ramana Murthy Badam, Vladimir Bliznetsov
Life of this patent
Estimating the term…
Abstract
Formation, through etching, of structures whose minimum width is less than can be achieved by optical means alone has been achieved by inserting a layer of sandwiching material between the photoresist (or hard mask if used) and the structure. By adjustment of the relative etch rates of this layer and the structure, a uniform lateral width reduction and surface smoothing of the structure is achieved.
Claims15
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.
4 more elements
Dependencies are inferred from the claim text.