The Korean Society of Surface Science and Engineering

To ensure the reliability of the atomic layer etching (ALE) process, it is essential to employ real-time monitoring of the adsorption (deposition) step. In this study, a quartz crystal–based polymer sensor was developed to enable real-time detection of radical adsorption. The operational characteristics of the sensor were evaluated using an ALE system equipped with a radical generation module designed to allow energetic radicals and neutral species to reach the substrate. The sensor frequency changed linearly in response to variations in the amount of radicals adsorbed and deposited on the sensor surface, confirming its ability to monitor process conditions. The frequency shift exhibited a linear proportional relationship with adsorption (deposition) time, and XPS analysis revealed that the amount of radicals generated from the decomposition of the etching gas C₄H₂F₆ increased with longer adsorption time. Furthermore, this increase in radical adsorption was found to proportionally enhance the etch per cycle (EPC).

키워드 Diagnostics; Plasma; ALE (Atomic Layer Etching); Radical.