Liquid discharging head, liquid discharging apparatus, and method of manufacturing liquid discharging head

A method of manufacturing a liquid discharging head including a pressure chamber partitioning portion that includes a plurality of partitioning walls that partition a pressure chamber in which a pressure to discharge a liquid is applied to the liquid, a diaphragm that includes a wall surface that faces the pressure chamber, and a piezoelectric substance, the pressure chamber partitioning portion, the diaphragm, and the piezoelectric substance being provided in order in a first direction, in which the plurality of partitioning walls include a first partitioning wall and a second partitioning wall, the pressure chamber is located between the first partitioning wall and the second partitioning wall in a second direction that intersects the first direction, and the wall surface of the diaphragm includes a first portion at a first position, in which a distance between the first position and the first partitioning wall in the second direction is equivalent to or smaller than a distance between the first position and the second partitioning wall in the second direction, and a second portion at a second position between the first position and the first partitioning wall in the second direction, the method of manufacturing comprising:

• an oxide film forming step that forms an oxide film on a surface of the substrate, in which the pressure chamber is formed, so that the oxide film, in the second direction, exists at the first position and does not exist at a position corresponding to the first partitioning wall;
• a thermal oxidation step that forms a thermal oxide layer, the thermal oxide layer being included in the diaphragm, by performing thermal oxidation on the surface of the substrate on which the oxide film is formed so that a position of the second portion in the first direction is positioned on an opposite side in the first direction with respect to a position of the first portion in the first direction;
• and
• a pressure chamber forming step that forms a pressure chamber while leaving behind the thermal oxide layer on the substrate on which the thermal oxide layer is formed.