Plasma-chamber wall interaction and its impact on polymer deposition in inductively-coupled C₄F₈/Ar plasmas

Plasma processing chambers, key tools in semiconductor device fabrication, must be meticulously maintained to ensure tool-to-tool matching. Processing chamber walls are liable to contamination with fluorocarbon (C_xF_y) film, which acts as a source and/or sink for active species during plasma processes. This contamination potentially affects processing quality and alters the plasma properties, increasing deviations between processing chambers. However, quantitative studies on the impact of wall contamination on the substrate deposition outcomes have been limited. Additionally, spatially resolved investigations are crucial for understanding the plasma-wall interaction. Therefore, this study evaluated the influence of polymer (C_xF_y) film wall contamination on plasma deposition via various plasma diagnostics and surface analyses. When the chamber inner wall was coated with polymer film, the thickness, surface roughness, and chemical composition of the deposited film on the bottom substrate were more uniform. These results were linked to alterations in the uniformity of active species in the plasma, such as CF₂ and F, resulting from interaction with the polymer film on the wall's surface. The C–F_x and C–CF_x composition ratios in the wall-coated films dramatically reduced, indicating that this film supplied the depositing precursors to the plasma. These results suggest that controlling the chamber wall conditions is important to maintain tool-to-tool matching and modulate the processing performance.