Abstract: The present invention relates to a technique for cleaning a thin film forming apparatus. In a typical embodiment, deposits originating from process gases for forming a thin film and deposited on the inner surface of a reaction tube are removed by etching by supplying a cleaning gas into the reaction tube while heating the interior of the reaction tube at a predetermined temperature. The inner surface of the reaction tube roughened by etching is subjected to a planarizing step. The planarizing step is performed by supplying a gas containing hydrogen fluoride into the reaction tube while keeping the interior of the reaction tube 2 at a low temperature, such as a room temperature. The planarizing step is effective in preventing the reduction of deposition rate in a thin film forming process.

Abstract: The present invention relates to a technique for cleaning a thin film forming apparatus. In a typical embodiment, deposits originating from process gases for forming a thin film and deposited on the inner surface of a reaction tube are removed by etching by supplying a cleaning gas into the reaction tube while heating the interior of the reaction tube at a predetermined temperature. The inner surface of the reaction tube roughened by etching is subjected to a planarizing step. The planarizing step is performed by supplying a gas containing hydrogen fluoride into the reaction tube while keeping the interior of the reaction tube 2 at a low temperature, such as a room temperature. The planarizing step is effective in preventing the reduction of deposition rate in a thin film forming process.