Patent ID: 8227279

Claim:
A manufacturing method of a semiconductor element comprising the steps of: preparing a gallium nitride-containing semiconductor layer forming the semiconductor element; forming an electrode layer on said gallium nitride-containing semiconductor layer; forming a first film on said electrode layer; forming a second film having a pattern and made of a material of which rate of etching with alkaline etchant is smaller than that of a material of said first film; forming a coating film on said first film after the step of forming said first film and before the step of forming said second film; forming a ridge portion in said gallium nitride-containing semiconductor layer in a region located under said second film by performing the etching to remove partially said first film, said electrode layer and said gallium nitride-containing semiconductor layer masked with said second film; retreating a position of an end surface of said first film with respect to a position of an end surface of said second film by removing the end of said first film located on said ridge portion by the etching using said alkaline etchant; forming, on the side surface of said ridge portion and the top surface of said second film, a protective film made of a material of which rate of etching with said alkaline etchant is smaller than that of the material forming said first film; removing said first film by the etching using said alkaline etchant, and thereby removing said second film and a portion of said protective film formed on the top surface of said second film; and partially removing said coating film to have substantially the same pattern as said second film, wherein said step of partially removing said protective film also removes said coating film located on said first film.