A method for processing a substrate is provided. The method includes supplying a first flow of a chemical solution into a processing chamber, configured to process the substrate, via a first dispensing nozzle. The method further includes producing a first thermal image of the first flow of the chemical solution. The method also includes performing an image analysis on the first thermal image. In addition, the method includes moving the substrate into the processing chamber when the result of the analysis of the first thermal image is within the allowable deviation from the baseline.