A method of manufacturing a substrate for a sensor which includes
- a base section,
- a movable section connected to the base section, the movable section extending from the base section along an extension direction when viewed in a planar view as viewed from a thickness direction of the movable section, the thickness direction being perpendicular to the extending direction;
- a support portion which extends along the movable section from the base section in the extension direction when viewed in the planar view;
- a gap portion formed to have a predetermined gap in a cross direction between the movable section and the support portion when viewed in the planar view, the cross direction being perpendicular to the extension direction and the thickness direction;
- and
- a ridge portion on each of facing surfaces of the movable section and the support portion in the gap portion, each ridge portion being formed as an etching residue and having a top portion on the corresponding facing surface,
- the predetermined gap being a gap between a top portion of a first ridge portion which is the ridge portion formed at one of the movable section and the support portion, and a top portion of a second ridge portion which is the ridge portion formed at the other of the movable section and the support portion,
- the method comprising:
- forming a first corrosion-resistant film and a second corrosion-resistant film on an upper surface and a lower surface, respectively, of a substrate forming material;
- forming a first pattern opening by forming a first photoresist layer and a second photoresist layer respectively on the first corrosion-resistant film and the second corrosion-resistant film, patterning the first photoresist layer to expose a part of the second corrosion-resistant film, and removing the exposed part of the second corrosion-resistant film to expose a part of the lower surface of the substrate forming material;
- first etching for forming a first recessed portion in the substrate forming material by wet-etching the lower surface of the substrate forming material exposed in the first pattern opening;
- covering at least an inner surface of the first recessed portion with a protective film;
- forming a second pattern opening by patterning the second photoresist layer on the first corrosion-resistant film to expose a part of the first corrosion-resistant film and removing the exposed part of the first corrosion-resistant film to expose a part of the upper surface of the substrate forming material;
- and
- second etching for forming the gap portion by penetrating a recess bottom portion of a second recessed portion which is formed by wet-etching the upper surface of the substrate forming material exposed in the second pattern opening, to the first recessed portion,
- when a width in the same direction as the predetermined gap, of each of the first pattern opening and the second pattern opening, is set to be Wp, an etching depth of the substrate forming material in the first etching or the second etching is set to be d, and a limit value of the amount of displacement of the movable section is set to be Wgmax, the relationship of one of the following Expressions (1) to (3) being satisfied:
- 0<Wp≦0.7735d+0.5 (1)
- 0.7735d+0.5≦Wp≦1.9393d+0.2083 (2)
- 1.9393d+0.2083≦Wp≦Wgmax+1.956d (3).