Diagnosis of electron density and temperature by using collisional radiative model in capacitively coupled Ar plasmas I: triple-frequency discharges

TL;DR

This paper develops an 18-level argon collisional radiative model combined with optical emission spectroscopy and Langmuir probe calibration to diagnose electron density and temperature in triple-frequency capacitively coupled plasmas, revealing how different frequency powers influence plasma parameters.

Contribution

It introduces a novel diagnostic method integrating CRM with OES and probe calibration for triple-frequency CCPs, highlighting the control of plasma parameters by different frequency powers.

Findings

High frequency power mainly controls electron density.

Low frequency power mainly controls electron temperature.

Increasing intermediate frequency power affects control dynamics.

Abstract

An 18-level argon collisional radiative model (CRM) suitable for low pressure was established. The model can be solved by combining the optical emission spectroscopy (OES) with Langmuir probe calibration. In the capacitively coupled plasmas (CCPs) with different frequency and power, the electron temperature and density obtained by the model were compared with those measured by Langmuir probe. It is found that the calibration point at any frequency or power is suitable for the fixed pressure. This method was then applied to the diagnosis of triple-frequency (TF) CCPs, it is shown that the high frequency (HF) power mainly controls the electron density, the low frequency (LF) power mainly controls the electron temperature, and the intermediate frequency (IF) power was between the two. Compared with the dual-frequency (DF) CCPs, it is found that with the increase of IF power, the HF power can control the electron density more independently with less influence on the electron temperature.