Patent ID: 7713843

Claim:
A method of fabricating an optical semiconductor device, comprising: forming a semiconductor layer on an InP region, the semiconductor layer including a plurality of semiconductor films; forming a first etching mask on the semiconductor layer, the first etching mask having a pattern; etching the semiconductor layer through the first etching mask to form a semiconductor mesa and a first marking mesa, each of the semiconductor mesa and the first marking mesa including an active layer and an InP cladding layer, the InP cladding layer being provided on the active layer, the active layer being made of semiconductor material, and the semiconductor material being different from InP; growing an InP burying region through the first etching mask on a side of the semiconductor mesa and a side of the first marking mesa to bury the semiconductor mesa and the first marking mesa; forming a second etching mask on the InP burying region after removing the first etching mask, the second etching mask having an opening, the opening being located above the first marking mesa; and etching InP in the InP burying region and the first marking mesa through the second etching mask to form a second marking mesa, the alignment mark including the second marking mesa, the active layer being exposed on the top of the second marking mesa.