Patent ID: 9261649
Filing Date: 2016-02-16
CPC Classification: G02B

Claim Text:
1. A method for manufacturing a semiconductor optical waveguide device, comprising the steps of: preparing a substrate having a principal surface, the principal surface including a first area and a second area sequentially arranged along a waveguide axis; forming a stacked semiconductor layer on the principal surface of the substrate, the stacked semiconductor layer including an upper cladding layer, a first core layer, an intermediate cladding layer, and a second core layer; forming a waveguide mesa having a first portion and a second portion on the first area and the second area of the substrate, respectively, by etching the stacked semiconductor layer through a first mask, the first portion and the second portion including the upper cladding layer and the first core layer; forming a dummy buried region that embeds a top surface and side surfaces of the waveguide mesa; forming a second mask on the dummy buried region, the second mask having an opening on the first portion of the waveguide mesa and having a pattern on the second portion of the waveguide mesa; forming a third mask having an opening that reaches a top surface of the first portion of the waveguide mesa, the third mask including a dummy buried mask formed by etching the dummy buried region through the second mask; forming an upper mesa having a first upper mesa portion and a second upper mesa portion on the first area and the second area of the substrate, respectively, by etching the waveguide mesa through the third mask; and after removing the third mask, forming a lower mesa including the second core layer by etching the stacked semiconductor layer, the lower mesa having a greater width than a width of the upper mesa.