Substrate fixing device and electrostatic chuck

A substrate fixing device comprising:

• a baseplate including a gas supply part;
• an electrostatic chuck on the baseplate, the electrostatic chuck including a substrate and configured to attract an object onto a first surface of the substrate, the substrate having a gas hole extending from a second surface of the substrate to the first surface, the second surface facing the baseplate, so that gas is supplied from the gas supply part to the first surface;
• and
• a porous body in the gas hole,
• wherein the gas hole includes
• a first recess formed in the second surface and depressed toward the first surface;
• a second recess formed at a bottom of the first recess and depressed toward the first surface;
• and
• a through hole piercing through the substrate from a bottom of the second recess to the first surface, and
• wherein an entirety of the first recess is filled with the porous body, the second recess is partly filled with the porous body, and a region of the second recess unfilled with the porous body is a recess in the porous body and a space communicating with the through hole, the recess being depressed toward the second surface relative to a position where the bottom of the second recess communicates with the through hole.