Apparatus for treating substrate using liquid and method for controlling liquid

Abstract

The inventive concept provides a liquid treating apparatus. The liquid treating apparatus includes a spin chuck configured to support and rotate a substrate; and a liquid supply unit configured to supply a liquid to the substrate, and wherein the liquid supply unit includes: a first nozzle connected to a first flow path pipe and configured to discharge a first liquid to the substrate; a first valve assembly including a first cut-off valve for cutting-off a flow of the first liquid within the first flow path pipe and a first suck-back valve for sucking-back the first liquid, and installed at the first flow pipe; a second nozzle connected to a second flow path pipe and configured to discharge a second liquid to the substrate; a second valve assembly including a second cut-off valve for cutting-off a flow of the second liquid within the second flow path pipe and a second suck-back valve for sucking-back the second liquid, and installed at the second flow pipe path; a first flow velocity controller configured to adjust an air flow velocity of an air introduced into or outflowed from the first suck-back valve; and a second flow velocity controller configured to adjust an air flow velocity of an air introduced into or outflowed from the second suck-back valve, and wherein a first speed of a suck-back speed provided by the first valve assembly is slower than a second suck-back speed provided by the second valve assembly, and a surface tension of the first liquid is lower than a surface tension of the second liquid.