In a method for using a film formation apparatus for a semiconductor process, process conditions of a film formation process are determined. The process conditions include a preset film thickness of a thin film to be formed on a target substrate. Further, a timing of performing a cleaning process is determined in accordance with the process conditions. The timing is defined by a threshold concerning a cumulative film thickness of the thin film. The cumulative film thickness does not exceed the threshold where the film formation process is repeated N times (N is a positive integer), but exceeds the threshold where the film formation process is repeated N+1 times. The method includes continuously performing first to Nth processes, each consisting of the film formation process, and performing the cleaning process after the Nth process and before an (N+1)th process consisting of the film formation process.