Mixing device, substrate processing apparatus including the same, and substrate processing method

An apparatus for processing a substrate, the apparatus comprising:

• a mixing nozzle having a mixing space that is shaped as an inverted cone, the mixing nozzle comprises a first inlet installed on a side surface of the mixing space, a second inlet positioned higher than the first inlet and installed on a top surface of the mixing space, a third inlet positioned higher than the first inlet and installed on the top surface of the mixing space, and an outlet installed at a lower portion of the mixing space;
• a first chemical supply unit connected to the first inlet and configured to supply a first chemical solution into the mixing space through the first inlet;
• a second chemical supply unit connected to the second inlet and configured to supply a second chemical solution into the mixing space through the second inlet;
• a supply tank connected to the outlet, the outlet supplying the supply tank with a solution mixture formed of the first chemical solution and the second chemical solution that are mixed in the mixing space;
• a third chemical supply unit that is connected to the third inlet and configured to supply a third chemical solution through the third inlet into the mixing space;
• and
• a fourth chemical supply unit configured to directly supply a fourth chemical solution to the supply tank through a second inlet of the supply tank different from a first inlet of the supply tank that is connected to the outlet of the mixing nozzle,
• wherein the supply tank is installed with a circulation flow path that is used to mix the fourth chemical solution with the solution mixture already within the supply tank.