The concept of plasma cleaning in glow discharge spectrometry

A plasma cleaning procedure to improve elemental depth profiling of shallow layered materials by glow discharge spectrometry is proposed. The procedure is based on two approaches applied prior to depth profiling, either individually or sequentially. The first approach employs a plasma generated at low power, i.e. a "soft'' plasma, for removal of contaminants adsorbed on the surface of the target material. In the second approach, sacrificial material is sputtered under normal conditions, e. g. those used for depth profiling, to clean the inner surface of the anode of the glow discharge source. It is demonstrated that plasma cleaning in glow discharge optical emission spectrometry and glow discharge time-of-flight mass spectrometry improves significantly the spectrum of the target material, particularly at the commencement of sputtering due to stabilisation of the plasma as a result of removal of contaminants. Furthermore, modelling and validation studies confirmed that the soft plasma cleaning does not sputter the target material.