Preventing oxide precipitation in selective wet etching of Si3N4 for 3D-NAND structure fabrication: The role of bubbles

Study on the SiO2 Wet-Etching Mechanism Using γ-Ureidopropyltriethoxysilane as an Inhibitor for 3D NAND Fabrication

“…However, most additives protecting the SiO 2 surface are suitable for neutral or alkaline conditions but unstable in a hot-concentrated PA solution. − Given the strongly acidic properties and high-temperature conditions intrinsic to the PA etching solution, the inhibitors studied are currently are limited. Silicic acid is mostly used by driving the etching reaction (eq ) backward, following Le Chatelier’s principle. ,,− SiO 2 + H 2 O ↔ Si false( normalOH false) 4 Nevertheless, the silicic acid is also a byproduct of Si 3 N 4 etching, which results in SiO 2 redeposition. ,,,− Thus, the uncontrolled silicic acid concentration readily leads to the regrowth of SiO 2 layers, consequently affecting the following processes. Recently, only a few studies have provided evidence suggesting the promising potential for additives inhibiting SiO 2 etching in the concentrated PA solutions. , Therefore, further research focusing on the application and mechanistic analysis of inhibitors compatible with the hot-concentrated PA etching solution for SiO 2 etching is required.…”