The Korean Society of Surface Science and Engineering

This study investigates the effect of PF₅–C₄F₈ mixed-gas composition on the SiO₂ etching characteristics in an inductively coupled plasma (ICP) etching system operated at a low temperature of –30 ℃. The behavior of reactive species in the plasma was analyzed using optical emission spectroscopy (OES), while neutral and ionic species that are difficult to detect with OES were identified using quadrupole mass spectrometry (QMS). The analysis revealed that PF₅ generated high-mass PF_x ions together with fluorine radicals, inducing physical bombardment on the substrate surface. Meanwhile, C₄F₈ exhibited a high dissociation rate, producing F and CF_x radicals that enhanced chemical etching reactions. In addition, increasing the bias power elevated the physical contribution of PFx ions, resulting in a higher overall etch rate. These observations quantitatively demonstrate the etching behavior and plasma chemistry occurring under PF₅–C₄F₈-based low-temperature plasma conditions.

키워드 Reactive Ion Etching, Plasma, Low-Temperature