Liquid supply unit having tank provided with circulation line, apparatus for treating substrate, including the same, and method of treating substrate

1 . An apparatus for treating a substrate, the apparatus comprising:

a cup providing a treatment space therein;

a support unit for supporting the substrate and rotating the substrate in the treatment space;

a nozzle for supplying a treatment liquid to the substrate;

a liquid supply unit for supplying the treatment liquid to the nozzle,

wherein the liquid supply unit includes:

a tank for storing the treatment liquid and including:

a housing having a space for storing the treatment liquid therein;

a circulation line including an inlet coupled to the housing and an outlet disposed within the space of the housing and configured to circulate the treatment liquid from the housing, wherein the inlet of the circulation line receives the treatment liquid in the housing, and the outlet of the circulation line returns the treatment liquid in the circulation line to the space of the housing, wherein a pump unit is installed in the circulation line;

a heater unit installed in the circulation line to heat the treatment liquid; and

a drain line for discharging the treatment liquid remaining in the circulation line to an outside of the apparatus for treating the substrate and provided with a drain valve, wherein the treatment liquid remaining in the circulation line is discharged via the drain valve to the outside, wherein the drain line is connected to the circulation line between the pump unit and the heater unit; and

a controller for controlling the liquid supply unit,

wherein the liquid supply unit further includes:

a cooling gas supply line which supplies a cooling gas to the heater unit, and a cooling valve is installed in the cooling gas supply line,

wherein the controller controls the liquid supply unit to heat the treatment liquid with the heater unit while circulating the treatment liquid in the housing through the circulation line in a state in which the drain valve is closed in a normal mode, and to change a state of the drain valve to an open state to discharge the treatment liquid remaining in the circulation line to the drain line, and to open the cooling valve to supply the cooling gas to the circulation line in an emergency mode, and

wherein in the emergency mode, an operation of the pump unit is stopped.

2 . The apparatus of claim 1 ,

wherein the cooling gas supply line is coupled to the circulation line.

3 . The apparatus of claim 2 ,

wherein the cooling gas supply line is coupled to the circulation line downstream of the heater unit.

4 . The apparatus of claim 3 ,

wherein the cooling gas supply line is connected to the circulation line to supply the cooling gas in a direction toward the heater unit.

5 . The apparatus of claim 1 ,

wherein the cooling gas supply line is coupled to the housing.

6 . The apparatus of claim 1 ,

wherein the circulation line includes:

a first line of which a longitudinal direction is provided in a vertical direction;

a second line extending from the first line and connected to the housing so as to be provided upstream of the first line; and

a third line extending from the first line and coupled to the housing so as to be provided downstream of the first line,

wherein the pump unit is installed in the first line,

wherein the cooling gas supply line is connected to the third line, and

wherein the drain line is connected to the first line.

7 . The apparatus of claim 1 ,

wherein the cooling gas supply line is coupled to the housing, and

a vent line for exhausting an internal atmosphere is coupled to the housing.