METHOD FOR MONITORING A PLASMA, DEVICE FOR CARRYING OUT THIS METHOD, USE OF THIS METHOD FOR DEPOSITING A FILM ONTO A PET HOLLOW BODY

摘要

The invention relates to a method for monitoring the composition of a plasma, this plasma being generated from determined precursors for depositing a film onto a polymer material. This method involves receiving light intensities emitted by the plasma and comprises: a step for selecting a first reference wavelength range that is selected within a plasma emission spectral region in which no significant signal of a parasitic chemical species can exist, i.e. which is not part of the determined precursors and which is thus normally not present in the plasma and whose presence in the plasma influences the nature of the deposited film; a step for selecting a second wavelength range which is selected within a plasma emission spectral region in which a significant signal of a parasitic chemical species is likely to exist; a step for simultaneously acquiring light intensities emitted by the plasma in each of the two selected wavelength ranges emitted by the plasma in each of the two selected wavelength ranges, and; a step for calculating, on the basis of these light intensities, at least one monitoring coefficient.