Method for fabricating a hybrid optical integrated circuit employing SOI optical waveguide

A method for fabricating a hybrid optical integrated circuit, the method comprising the steps of:

• a) providing a SOI wafer including a silicon substrate, a buried insulating layer and a single crystal silicon layer;
• b) selectively etching the single crystal silicon layer, thereby forming a SOI slab;
• c) forming a silicon nitride layer and an etching mask layer on the resulting structure, wherein the silicon nitride layer is formed by a low pressure chemical vapor deposition process;
• d) selectively etching the etching mask layer and the silicon nitride layer to expose the single crystal silicon layer in the SOI slab except a rib area and simultaneously forming a V-groove etch window for aligning an optical fiber and marks for aligning an optical device, wherein the a rib region in the SOI slab is covered with the silicon nitride layer and the etching mask layer;
• e) selectively etching the exposed single crystal silicon layer to form a SOI rib;
• f) selectively etching the etching mask layer and the silicon nitride layer on the SOI rib;
• g) forming a cladding layer for an optical waveguide on a surface of the SOI slab and the SOI rib;
• h) anisotropically etching the silicon substrate exposed through the V-groove etch window to form an optical fiber guiding V-groove;
• and
• i) selectively removing the etching mask layer positioned at both end facets of the SOI slab and exposing the silicon nitride layer.