Substrate treatment apparatus and substrate treatment method

A substrate treatment apparatus for treating a substrate with a treatment liquid, the apparatus comprising:

• a substrate rotating unit which horizontally holds and rotates the substrate;
• a nozzle having an opposing surface to be brought into spaced opposed relation to a region of a front surface of the substrate rotated by the substrate rotating unit, the region of the front surface of the substrate being defined within a peripheral edge of the substrate and containing a rotation center of the substrate, the nozzle further having an outlet port provided in the opposing surface to be brought into opposed relation to the rotation center;
• a first liquid supplying unit which supplies a first liquid as the treatment liquid to the outlet port;
• a second liquid supplying unit which supplies a second liquid between the front surface of the substrate and the opposing surface;
• a second liquid supply control unit which controls the second liquid supplying unit to fill a space defined between the region and the opposing surface with the second liquid in a liquid filled state, and then stop supplying the second liquid to form a liquid puddle in the space;
• and
• a first liquid supply control unit which controls the first liquid supplying unit to spout the first liquid from the outlet port after the formation of the liquid puddle.