Formulation and Evaluation of Diluted Sulfuric-Peroxide-HF (DSP+) Mixtures for Cleaning High-Aspect Ratio Contacts in 3D NAND

Abstract

In this study, organic strip, particle removal efficiency and wettability were investigated at different mixing concentrations of diluted Sulfuric-Peroxide-HF (DSP+ ) solutions with and without the addition of IPA. Organic strip evaluation was carried out with KrF photoresist (PR), and the strip rate was increased rapidly with the increase in H2SO4 concentration mixed with DI water (DIW). The effects of H2O2 and IPA addition on diluted H2SO4 were observed below 30 vol% of H2SO4. The thickness of PR was increased with the addition of H2O2 to the solutions and the strip rate was increased when IPA was added. Silica particles were used to evaluate particle removal efficiency. The concentration of HF was the predominant factor of increasing PRE, and the addition of H2SO4 and H2O2 assisted in obtaining high PRE, while IPA addition reduced PRE. Decreasing of contact angle was observed with an increase of IPA addition to DSP+ solutions, and improved wettability of DSP+ solutions was expected to effectively clean particles in high-aspect-ratio (HAR) contact holes.