Method for manufacturing diffraction grating of Laser Diode

A method for manufacturing a diffraction grating of a laser diode, the diffraction grating being selectively formed on predetermined parts of a semiconductor substrate, the method comprising the steps of:

• forming a first photoresist pattern on an entire upper surface of a semiconductor layer where a diffraction grating is to be formed, the first photoresist pattern is arranged at an interval corresponding to a predetermined grating cycle;
• forming a diffraction-grating layer by etching the semiconductor layer under the first phototesist pattern while utilizing the first photoresist pattern as an etching mask;
• forming a mask pattern on the diffraction-grating layer except for a predetermined diffraction-grating area;
• removing the mask pattern formed on parts of the diffraction-grating layer;
• and,
• removing the parts of the diffraction-grating layer left exposed upon removal of the mask pattern.