Patent ID: 7977129

Claim:
A method for manufacturing a semiconductor optical device having an optical grating, comprising the steps of: forming a semiconductor layer on a semiconductor substrate; forming an insulating layer on the semiconductor layer; forming a first resin layer not containing silicon (Si) on the insulating layer; forming a second resin layer containing silicon (Si) on the first resin layer, the second resin layer having a pattern corresponding to the optical grating; etching the first resin layer using the second resin layer as a mask by a reactive ion etching that uses a mixed gas of oxygen (O 2 ) and nitrogen (N 2 ), the first resin layer being cooled downto a first temperature during etching to form a protective layer on a side face of the etched first resin layer; increasing the temperature of the first resin layer upto a second temperature higher than the first temperature; etching the insulating layer using the patterned first resin layer as a mask; and forming the optical grating on the semiconductor layer by etching the semiconductor layer using the patterned insulating layer as a mask.