Method for producing optical semiconductor device

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

• determining a wafer size to make a section arrangement including a plurality of sections in one of which the optical semiconductor device is formed, the optical semiconductor device including a trench and a semiconductor mesa defined by the trench;
• obtaining an in-plane distribution of a thickness of a resin layer by measuring a thickness of a resin layer formed on a first arrangement structure on a wafer having the wafer size, the first arrangement structure including a plurality of mesas defined by trenches having a predetermined trench width;
• obtaining a correlation between a thickness of a resin layer and a trench width by measuring a thickness of a resin layer formed on a second arrangement structure on a wafer having the wafer size, the second arrangement structure including a plurality of mesas defined by trenches having trench widths different from each other;
• forming a trench width map on a wafer having the wafer size by determining a trench width of the trench in the optical semiconductor device by using the in-plane distribution of the thickness and the correlation between the thickness of the resin layer and the trench width;
• preparing an epitaxial substrate by forming a stacked semiconductor layer on a substrate having the wafer size, the substrate having the section arrangement including the plurality of sections;
• forming, on the epitaxial substrate, a mask including a pattern for the semiconductor mesa and for the trench of the optical semiconductor device, the trench of the device having a trench width based on the trench width map;
• forming a trench structure including the semiconductor mesa and the trench by etching the stacked semiconductor layer using the mask;
• forming a resin layer on the trench structure, the resin layer being formed on an upper surface and a side surface of the semiconductor mesa;
• and
• forming an opening on the semiconductor mesa by etching the resin layer, the upper surface of the semiconductor mesa being exposed through the opening.