Semiconductor pressure sensor

A semiconductor pressure sensor comprising:

• a cavity disposed through digging in a one silicon substrate of a SOI (Silicon-On-Insulator) substrate having two silicon substrates bonded to each other with an oxide film therebetween;
• and
• a diaphragm formed from the other silicon substrate and the oxide film,
• wherein a periodic uneven section is disposed, in the digging direction, on an inner wall surface of the cavity in the one silicon substrate,
• the oxide film, bordering the cavity, of the diaphragm includes an arc-shaped section at a boundary portion to the one silicon substrate defining the inner wall side surface of the cavity, the arc-shaped section having the same width as the width of the cavity at a desired section of the cavity in the one silicon substrate and reducing the width of the cavity from the boundary portion toward the diaphragm center, and
• the arc-shaped section is disposed continuously from the periodic uneven section of the one silicon substrate.