Abstract
For over five decades, reactive ion etching (RIE) has been a foundational technique in the semiconductor industry, enabling the high-throughput fabrication of countless wafers. Its effectiveness stems from the synergistic interaction between reactive chemical species and highly energized ions, which has underpinned the advancement of modern microelectronics. However, as device architectures become increasingly complex—with reduced feature sizes and high-aspect-ratio 3D structures—conventional RIE faces significant limitations. The traditional ion-chemical synergy becomes less effective, leading to reduced etching efficiency and throughput. To overcome these challenges, cryogenic plasma etching using hydrogen fluoride (HF)-containing species has emerged as a promising approach, leveraging a unique interplay between ions, physisorbed surface species, and substrate materials. A mini overview is provided for cryogenic plasma etching in SiO2 and SiN, specifically for NAND flash memory applications. As part of this review, the etching mechanisms of HF-based cryogenic plasma etching are discussed on the basis of plasma diagnostics and surface-structure analyses. Finally, the outlook and prospects for cryogenic RIE are also discussed.