On the effect of film deposition on probe surface in measurement by the insulated pulse probe method

Calculation using a simple model showed that measurement by the insulated pule probe method is essentially stable even if a contaminating film is deposited on the probe surface in reactive plasmas, in contrast with measurement by the conventional Langmuir probe method, which is very sensitive to changes in the probe surface condition. In the case where the contaminating film is conductive, the probe current response hardly changes. In the case where the contaminating film is insulative. the time constant of the probe current decay decreases with the accumulation of the contaminating film, which becomes an index of the thickness of the contaminating film. The reliability of measurement against the probe surface contamination is experimentally demonstrated in comparison with the conventional Langmuir probe method by exposure to plasmas containing oxygen and methane, respectively.