Method of manufacturing a plasmon generator

A manufacturing method for a plasmon generator comprising a wide portion and a narrow portion protruding from the wide portion, wherein

• the narrow portion has a proximal end which is a boundary with the wide portion, and a near-field light generating surface which is a protruding end,
• the proximal end is located at a distance from an imaginary plane including the near-field light generating surface,
• the wide portion is greater than the narrow portion in maximum width in a first direction parallel to the imaginary plane, and
• the plasmon generator is configured to excite a surface plasmon from light on the wide portion, and to generate near-field light from the surface plasmon at the near-field light generating surface,
• the manufacturing method comprising the steps of:
• forming an initial plasmon generator;
• forming an etching mask on the initial plasmon generator, the etching mask including a first mask layer for defining the shape of one of the narrow portion and the wide portion and a second mask layer for defining the shape of the other of the narrow portion and the wide portion;
• and
• etching the initial plasmon generator into the plasmon generator by using the etching mask,
• wherein the step of forming the etching mask includes the steps of:
• forming a first initial mask layer;
• forming a first initial hard mask on the first initial mask layer;
• forming a first resist mask on the first initial hard mask by photolithography, the first resist mask being intended for defining the shape of the first mask layer;
• etching the first initial hard mask into a first hard mask by using the first resist mask;
• forming a second initial mask layer on the first initial mask layer and the first hard mask;
• forming a second initial hard mask on the second initial mask layer;
• forming a second resist mask on the second initial hard mask by photolithography, the second resist mask being intended for defining the shape of the second mask layer;
• etching the second initial hard mask into a second hard mask by using the second resist mask;
• and
• etching the first and second initial mask layers into the first and second mask layers, respectively, by using the first and second hard masks.