Method for producing a fine structure

The deep narrow microstructure GaN-based semiconductor, to provide a method of manufacturing a microstructure is possible to accurately form. A method of manufacturing a microstructure to form a fine structure on a semiconductor on a substrate, a first for forming the first GaN-based semiconductor layer of step and the first formed in the first step a GaN-based semiconductor layer, a second step of forming a first pores by etching, the diameter of said second of said first pores formed in step, in the plane direction of the substrate to form the second pores thinner than the diameter of said first pores have in a gas atmosphere containing nitrogen 850 ° C. or higher, and a third step of performing heat treatment the temperature of 950 ° C. or less, the configuration to.