Patent ID: 7674391

Claim:
A manufacturing method of an optical semiconductor device comprising; (a) a step for preparing a semiconductor substrate which is a first conducting substrate having a first surface and a second surface which becomes an opposite surface of the first surface, (b) a step for performing continuous epitaxial growth so as to deposit a first conducting cladding layer, an active layer, a second conducting first cladding layer, a second conducting etch-stop layer, a second conducting second cladding layer, a second conducting third cladding layer, and a second conducting contact layer, in order, over said first surface of said semiconductor substrate, (c) a step for forming a stripe-shaped etching mask for ridge formation over said contact layer and an etching mask for element fixation which is situated separated by a prescribed distance at the both sides of said etching mask for ridge formation, by a coating film formation and selective etching of said coating film, (d) a step for etching said contact layer from the top face to the bottom surface using both said etching masks as a mask and forming a ridge part contact layer and an element fixation part contact layer below said etching mask for ridge formation and said etching mask for element fixation, (e) a step for dry-etching a second conducting second cladding layer and a second conducting third cladding layer using both said etching masks as a mask to reach said etch-stop layer and forming a ridge, (f) a step for making the width of said ridge a prescribed dimension by wet-etching after removing both said masks, (g) a step for forming an insulating film over the upper surface of said ridge and forming a contact hole at said first surface side of said semiconductor substrate, (h) a step for forming a first electrode contacting said ridge part contact layer through said contact hole over said insulating film, (i) a step for forming a second electrode at said second face side of said semiconductor substrate, wherein, in the epitaxial growth of said step (b), said second conducting second cladding layer is composed of a material which has a greater etching rate compared with the etching rate of said second conducting third cladding layer while wet etching in said step (f).