Substrate processing apparatus and substrate processing method

1. A substrate processing apparatus, comprising:

a processing chamber in which a substrate is processed with a processing liquid;

a nozzle having a discharge port from which the processing liquid is discharged, the discharge port being formed in a distal end portion of the nozzle;

a nozzle bath including an accommodation chamber formed in the nozzle bath and an entrance through which the nozzle is inserted into the nozzle bath and pulled out of the nozzle bath, wherein the distal end portion of the nozzle is accommodated in the accommodation chamber at a standby time at which the processing liquid is not supplied to the substrate;

a circulation line configured to connect the nozzle and the nozzle bath to each other;

a first gas flow restrainer configured to restrain a gas flow between an outside of the nozzle bath and an inside of the nozzle bath, and including an atmosphere replacer configured to replace an atmosphere in a gap formed between the nozzle bath and the nozzle accommodated in the accommodation chamber of the nozzle bath; and

a controller configured to control the substrate processing apparatus,

wherein the atmosphere replacer includes:

a supply port formed in an inner circumferential surface of the nozzle bath and configured to supply a purge gas from the outside of the processing chamber into the gap; and

a suction port formed in the inner circumferential surface of the nozzle bath at a location closer to the entrance of the nozzle bath than the supply port and configured to discharge a gas present in the gap outward of the processing chamber, and

wherein the controller is programmed to perform, during the standby time, a control to execute:

accommodating the distal end portion of the nozzle in the accommodation chamber;

circulating the processing liquid between the nozzle and the nozzle bath by discharging the processing liquid from the nozzle accommodated in the accommodation chamber to the nozzle bath and returning the processing liquid present inside the nozzle bath to the nozzle via the circulation line; and

while the distal end portion of the nozzle is accommodated in the accommodation chamber and the processing liquid is circulated, restraining the gas flow between the outside of the nozzle bath and the processing liquid present inside the nozzle bath by replacing the atmosphere in the gap by supplying the purge gas into the gap from the supply port and discharging the gas present in the gap from the suction port.

2. The apparatus of claim 1 , wherein the first gas flow restrainer further includes a seal configured to seal the gap formed between the nozzle bath and the nozzle accommodated in the accommodation chamber of the nozzle bath.

3. The apparatus of claim 2 , wherein the seal includes an expansion seal configured to expand by a fluid supplied thereinto and to seal the gap.

4. The apparatus of claim 2 , wherein the seal includes an elastic seal configured to be compressed by the nozzle bath and the nozzle to seal the gap.

5. The apparatus of claim 2 , wherein the seal includes a seal formation portion which forms a liquid seal for sealing the gap.

6. The apparatus of claim 2 , further comprising:

an outer bath disposed outside the nozzle bath and including an intermediate chamber formed therein to surround the entrance of the nozzle bath; and

a second gas flow restrainer configured to restrain a gas flow between the outside of the outer bath and the inside of the nozzle bath.

7. The apparatus of claim 6 , wherein the second gas flow restrainer includes a movable lid configured to open and close an entrance of the outer bath, wherein the nozzle is inserted into the outer bath and pulled out of the outer bath through the entrance of the outer bath.

8. The apparatus of claim 7 , wherein the second gas flow restrainer further includes a suction nozzle configured to discharge a gas from the intermediate chamber outward of the processing chamber.

9. The apparatus of claim 8 , wherein the second gas flow restrainer further includes a purge nozzle configured to supply a purge gas into the intermediate chamber from the outside of the processing chamber.

10. The apparatus of claim 1 , wherein the supply port of the atmosphere replacer has a ring shape so that the purge gas is supplied into the gap from an entire circumferential region of the inner circumferential surface of the nozzle bath.

11. The apparatus of claim 1 , wherein the suction port of the atmosphere replacer has a ring shape so that the gas present in the gap is suctioned from an entire circumferential region of the inner circumferential surface of the nozzle bath.