Atomic layer etching (ALE) is a promising technique with atomic-level thickness controllability and high selectivity based on self-limiting surface reactions. ALE is performed by sequential exposure of the film surface to reactants, which results in surface modification and release of volatile species. Among the various ALE methods, thermal ALE involves a thermally activated reaction by employing gas species to release the modified surface without using energetic species, such as accelerated ions and neutral beams. In this study, the basic principle and surface reaction mechanisms of thermal ALE?processes, including “fluorination-ligand exchange reaction”, “conversion-etch reaction”, “conversion-fluorination reaction”, “oxidation-fluorination reaction”, “oxidation-ligand exchange reaction”, and “oxidation-conversion-fluorination reaction” are described. In addition, the reported thermal ALE processes for the removal of various oxides, metals, and nitrides are presented.

Abstract
1. 서 론
2. ALE의 원리 및 반응 메커니즘
    2.1. ALE의 원리
    2.2. ALE 반응의 메커니즘
3. 산화물, 금속, 질화물의 열 원자층 식각 공정
    3.1. 산화물 thermal ALE
    3.2. 금속의 thermal ALE
    3.3. 질화물의 thermal ALE
4. 결 론
감사의 글
References

• 조현희(서울과학기술대학교 신소재공학과) | Hyeonhui Jo (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 이서현(서울과학기술대학교 신소재공학과) | Seo Hyun Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 윤은서(서울과학기술대학교 신소재공학과) | Eun Seo Youn (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 서지은(서울과학기술대학교 신소재공학과) | Ji Eun Seo (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 이진우(서울과학기술대학교 신소재공학과) | Jin Woo Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 한동훈(서울과학기술대학교 신소재공학과) | Dong Hoon Han (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 남서아(서울과학기술대학교 신소재공학과) | Seo Ah Nam (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 한정환(서울과학기술대학교 신소재공학과) | Jeong Hwan Han (Department of Materials Science and Engineering, Seoul National University of Science and Technology) Corresponding author