Method for manufacturing optical semiconductor device

A method for manufacturing an optical semiconductor device comprising the steps of:

• preparing a substrate product including a semiconductor layer, a mesa structure disposed on a principal surface of the semiconductor layer, and a protective layer, the protective layer being formed on the principal surface of the semiconductor layer, a side surface of the mesa structure, and an upper surface of the mesa structure;
• forming a buried layer composed of a resin on the substrate product;
• forming a first opening in the buried layer on the mesa structure by etching the buried layer;
• forming a second opening in the buried layer on the semiconductor layer by etching the buried layer;
• exposing the upper surface of the mesa structure and the principal surface of the semiconductor layer by etching the protective layer;
• forming a first electrode in the first opening, the first electrode extending from the surface of the buried layer to the upper surface of the mesa structure;
• and
• forming a second electrode in the second opening, the second electrode extending from the surface of the buried layer to the principal surface of the semiconductor layer,
• wherein the step of forming the second opening includes a first etching step and a second etching step,
• the first etching step includes steps of forming a first resist mask having an opening pattern for forming a recess in the buried layer on the semiconductor layer, etching the buried layer using the first resist mask, and removing the first resist mask, and
• the second etching step includes steps of, after the first etching step, forming a second resist mask having an opening pattern which has an opening width not smaller than an opening width of the recess, the recess being exposed through the opening pattern of the second resist mask, etching the buried layer using the second resist mask, and removing the second resist mask.