A method for manufacturing an LD is disclosed. The LD has a striped structure including an optical active region. The striped structure is buried with resin, typically benzo-cyclo-butene (BCB). The method to form an opening in the BCB layer has tri-steps etching of the RIE. First step etches the BCB layer partially by a mixed gas of CF4 and O2, where CF4 has a first partial pressure, second step etches the photo-resist patterned on the top of the BCB layer by a mixed gas of CF4 and O2, where CF4 in this step has the second partial pressure less than the first partial pressure, and third step etches the BCB left in the first step by mixed gas of CF4 and O2, where CF4 in this step has the third partial pressure greater than the second partial pressure.