Quantitative analysis of ionization rates of depositing particles in reactive plasma deposition using mass-energy analyzer and Langmuir probe

The ionization rates of depositing particles in reactive plasma deposition (RPD) were quantitatively investigated using a measurement system composed of a mass-energy analyzer and a Langmuir probe in order to clarify the formation mechanisms of high-quality transparent conductive oxide films. The detection efficiencies of neutral particles and ions in the mass-energy analyzer were calibrated by the Langmuir probe. The species ionization rates were measured during indium tin oxide (ITO) deposition. The ionization rates associated with changes in the deposition chamber pressure were also measured. During ITO deposition, the lower limits of the following ionization rates were determined: indium ionized at a rate of 74–87%, oxygen atoms at 0.5–0.6%, and oxygen molecules at 0.01–0.02%. These rates may increase depending on the pressure in the deposition chamber. This method would also be applicable for measuring general plasma processes.