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Description
Capacitively coupled discharges are extensively employed in industrial applications such as deep reactive ion etching and plasma-enhanced chemical vapor deposition (PECVD) owing to their excellent plasma uniformity, precise controllability, and strong ion directionality toward the electrodes. Optimization of plasma parameters is essential for improving process efficiency and productivity; however, real-time invasive diagnostic techniques often degrade plasma stability, process performance, and product quality. As a result, there is an increasing shift toward non-invasive diagnostic approaches.
In the present work, a non-invasive diagnostic technique based on the homogeneous discharge model is employed to externally estimate key plasma parameters. The obtained results are validated through comparison with electron density and temperature measurements acquired using a Langmuir probe. Within this framework, the plasma is modeled as an equivalent series RLC circuit consisting of sheath capacitance (Cₚ), bulk plasma resistance (Rₚ), and plasma inductance (Lₚ). The model is analytically solved in conjunction with a power balance equation expressed in terms of electron temperature and density. By using experimentally accessible parameters such as RF power, discharge voltage, discharge current, and phase difference as inputs, the model enables the determination of fundamental plasma parameters, including electron density and temperature [1]. Furthermore, the analytical approach is applicable over a broad range of operating pressures, extending up to atmospheric pressure.