Patent ID: 7267742

Claim:
An etching apparatus comprising: a chamber containing an etching solution including a first component, a second component, and water, a concentration of the water in the etching solution is at a specified level or lower; a circulation path configured to circulate the etching solution; a concentration controller configured to sample the etching solution from the circulation path and control concentrations of the first and second components and water respectively; a refilling chemical liquid feeder configured to feed a refilling chemical liquid including the first component having a concentration higher than the first component in the etching solution; a lot guide connected to the concentration controller and configured to guide a lot including a plurality of wafers, each of the wafers having a thin film on a surface, into the etching solution; and a lot determinator configured to determine whether the lot exists in the lot guide, wherein the concentration controller detects concentrations based on a determination of the lot determinator.