ScholarWorks@성균관대학교

초록

This study investigates the roles of F radicals and F2 molecules in SiGe and Si etching using an NF3-based pulsed remote plasma. By applying pulsed RF operation, the relative ratio of F and F2 was controlled, allowing the relationship between plasma species chemistry and etching behavior to be examined. Plasma diagnostics showed that reducing the duty ratio of the NF3 pulsed remote plasma increased the F2-to-F ratio, while RF power modulation under continuous-wave (CW) plasma caused little change in the species ratio. Temperature-dependent etching experiments and Arrhenius analysis revealed that Si etching exhibited similar activation energies regardless of plasma mode, indicating that the reaction is mainly governed by F radicals and shows little contribution from F2. In contrast, SiGe etching showed a reduced activation energy under pulsed plasma conditions, suggesting that F2 molecules act as a co-etchant by providing an additional reaction pathway. As a result of these species-dependent kinetic differences, pulsed plasma etching at −20 °C achieved SiGe/Si selectivity above 160. These results provide insight into plasma–surface reaction mechanisms and offer a strategy for designing highly selective SiGe etching processes for advanced three-dimensional device fabrication.

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