Experimental validity of double-curling probe method in film-depositing plasma

Abstract

This journal article shows our recent research about the validity of the double-curling method while a film deposition occurs. Curling probe is one of the microwave resonators mainly utilized to measure the electron density in plasma. The double-curling probe method is an application of the probe that allows us to make in-situ measurements of both electron density and deposited film thickness on the probe using the two different-sized curling probes. In this journal article, we firstly researched the validity of the method in a simulated condition where the probes were in argon plasma and where the probe surface is covered with a polyimide film (12.5–50 μm thickness). This first research showed that the electron density and the film thickness derived with the method were decently close to the values measured with the Langmuir probe and micrometer, respectively. We then researched the validity of the double-curling probe method in the situation where the hydrogenated-amorphous-carbon film deposition occurs on the probe surface. This second measurement demonstrated that the double-curling probe method can derive a constant electron density and a growing film while the film was depositing. These overall results verified the decent validity of the double-curling probe method for making an in-situ measurement of both electron density and depositing film thickness.