Substrate treatment device

A substrate treatment device, comprising:

• a placement stand having a plate shape, and being configured to rotate;
• a plurality of support portions provided on one surface of the placement stand and supporting a substrate, a planar shape of the substrate being a substantially quadrangle, each of the plurality of support portions supporting a corner part of the substrate;
• a liquid supplier configured to supply a liquid onto a surface of the substrate supported by the support portions, the surface of the substrate being a surface opposite to the placement stand side of the substrate, a film of the liquid being formed by the liquid supplied onto the surface of the substrate;
• a cooling part configured to supply a cooling gas into a space between the placement stand and a back surface of the substrate supported by the support portions, the film of the liquid becoming supercooled by the supplied cooling gas and then freezing;
• a protrusion provided on the one surface of the placement stand, the protrusion provided at a position on or near a boundary line of a region where the substrate supported by the plurality of support portions is provided in a plan view, the protrusion extending along the boundary line, the protrusion being not provided at a position of the corner part of the substrate, a gap being configure to be formed between a top portion of the protrusion and the back surface of the substrate;
• and
• a controller controlling the liquid supplier and the cooling part, the controller being configured to perform following steps;
• a liquid film forming step of forming a liquid film by supplying the liquid toward the surface of the substrate,
• a supercooling step in which the liquid film on the surface of the substrate being supercooled state by the cooling part.