Substrate processing apparatus and substrate processing method

A substrate processing method comprising:

• a processing-liquid supply step of supplying a processing liquid including water to a substrate held horizontally;
• a replacing step of replacing the processing liquid by supplying a low-surface-tension liquid that has surface tension lower than water to the substrate;
• an atmosphere shielding step in which a facing member, which has a facing surface facing a front surface of the substrate, is positioned at a processing position between a lower position close to the substrate and an upper position above the lower position by an elevation driving mechanism which elevates the facing member in a vertical direction, so that a space between the facing member and the front surface of the substrate is shielded from an ambient atmosphere;
• a liquid-film forming step in which, in a state where the facing member is positioned at the processing position and a low-surface-tension liquid nozzle is positioned between the facing surface and the front surface of the substrate, the low-surface-tension liquid is discharged from the low-surface-tension liquid nozzle, so that a liquid film of the low-surface-tension liquid is formed on the front surface of the substrate, the low-surface-tension liquid nozzle being connected to an arm which is driven by an arm driving mechanism;
• an opening forming step in which, while rotating the substrate around a predetermined rotational axis that extends in the vertical direction, an inert gas is discharged from an inert gas nozzle, which has a single discharge port exposed from the facing surface and facing a rotational center position that is a position centered on the rotational axis on the front surface of the substrate, so that an opening, that spreads from the rotational center position, is formed in the liquid film of the low-surface-tension liquid;
• an opening enlarging step of enlarging the opening in a radial direction away from the rotational center position by continuing discharge of the inert gas from the inert gas nozzle;
• and
• a landing-position changing step wherein, by moving the low-surface-tension liquid nozzle by the arm driving mechanism such that a landing position on the front surface of the substrate on which the low-surface-tension-liquid lands is placed outside a peripheral edge of the opening, the landing position is moved successively to at least two positions radially spaced from the rotational center position in accordance with enlargement of the opening, wherein respective distances from the rotational center position to the at least two positions are different,
• wherein the low-surface-tension liquid nozzle is maintained between the facing surface and the front surface of the substrate and the facing member is maintained at the processing position, from a time at which discharging the low-surface-tension liquid from the low-surface-tension liquid nozzle is started in the liquid-film forming step until an entirety of the liquid film of the low-surface-tension liquid is excluded from the front surface of the substrate in the opening enlarging step,
• the liquid film of the low-surface-tension liquid is formed, while supplying the inert gas from the inert gas nozzle to the space between the front surface of the substrate and the facing surface, and
• after the liquid film of the low-surface-tension liquid is formed on the front surface of the substrate, the opening is formed in the liquid film of the low-surface-tension liquid by increasing a flow rate of the inert gas which is discharged from the inert gas nozzle.