Vacuum processing method capable of preventing foreign matter from adhering to a wafer due to titanium (Ti)-based reaction products

Provided is a vacuum processing method capable of preventing foreign matter from adhering to a wafer due to titanium (Ti)-based reaction products. The vacuum processing method applicable to a plasma processing apparatus includes: a process of etching a titanium (Ti)-containing film; and a process of cleaning the processing chamber by using a mixed gas of nitrogen trifluoride (NF3) gas, argon gas and chlorine gas. The plasma processing apparatus is provided with a sample stage which is disposed in a processing chamber inside a vacuum container and, on which a wafer having a titanium (Ti)-containing film is placed; a coil to which high-frequency power for forming plasma in the processing chamber is supplied; and a heating device that emits electromagnetic waves in order to heat the wafer placed on the upper side of the sample stage.