Method of fabricating a structure by anisotropic etching, and silicon substrate with an etching mask

A fabrication method of fabricating a structure, the method comprising:

• a first step of forming a basic etching mask corresponding a target shape with a first shape having a convex corner, a second shape adjacent to the first shape with a space therebetween, and a correction etching mask with a first portion extending from a portion corresponding to the convex corner of the first shape, a second portion connected to the first portion, and an opening portion on a single-crystal silicon substrate with a (100) principal face;
• and
• a second step of subjecting the single-crystal silicon substrate with the basic etching mask and the correction etching mask formed thereon to an anisotropic etching and penetrating the single-crystal silicon in a position where corresponding to the space to form the single-crystal silicon substrate having the target shape,
• wherein, in the first step, the first portion of the correction etching mask extends in a <110> direction from the portion of the basic etching mask corresponding to the convex corner of the first shape, connected to the portion of the basic etching mask corresponding to the second shape and connects with the second portion at an end of the first portion extending in the <110> direction, the second portion has at least one convex corner, and the opening portion is surrounded by the first portion, the second portion and the portion corresponding to the second shape of the basic etching mask, and extends straddling a boundary between the end extending in the <110> direction of the first portion and the connected section of the second portion.