An apparatus for ashing a photoresist is provided to heat a semiconductor substrate at desired temperature by controlling a gap between a substrate and a heating plate. A process for removing a photoresist layer formed on a substrate(100) is performed in a process chamber(102) by using ashing gas. A heating plate(104) is installed within the process chamber to heat the substrate at the predetermined temperature. A supporting unit(110) supports the substrate to position an upper part of the heating plate. A temperature control unit(106) controls a gap between the substrate and the heating plate to maintain the desired temperature of the substrate.
