In Situ Monitoring of Etching Characteristic and Surface Reactions in Atomic Layer Etching of SiN Using Cyclic CF4/H2 and H2 Plasmas

• DOI: 10.1021/acsami.3c04705
• Publication Date: 2023-07-13T12:56:08Z
• Authors: Shih-Nan Hsiao; Makoto Sekine; Masaru Hori
• Keywords: Plasma Etching; Deposition

Cyclic atomic layer etching (ALE) of SiN with high selectivity to SiO2, utilizing a hydrofluorocarbon deposition followed by exposure hydrogen plasma, is presented. The surface reaction mechanism and behavior were investigated in situ attenuated total reflectance Fourier transformation infrared spectroscopy (ATR-FTIR) spectroscopic ellipsometry. In the step, film was deposited on top films using CF4/H2 plasmas varying H2 contents (33 85%). Subsequently, surface-modified exposed plasma for etching. self-limiting observed, where etch depth solely depended F concentration once its thickness exceeded critical value. A approximately 8.6 over SiO2 achieved. ATR-FTIR spectra revealed that during besides formation C-H peak associated deposition, appearance N-H4 absorbance band indicated an ammonium fluorosilicate SiN. subsequent both modification pre-deposited removed. removal rate exposure. These findings indicate importance achieving ALE dissociation released reactants interacted SiN, leading new layer. process significantly slowed down completely