RF 바이어스 제어에 따른 이온 에너지 분포 및 식각 특성에 관한 연구 = A Study on Ion Energy Distribution and Etching Characteristics under RF Bias Control

다국어 초록 (Multilingual Abstract)

As semiconductor devices continue to scale toward high density and three-dimensional architectures, precise control of ion energy has become a critical requirement for reliable plasma etching. In particular, the ion energy distribution function (IEDF), rather than the average ion energy alone, plays a key role in determining etching behavior, including profile stability and plasma-induced damage. Conventional process analyses based solely on average bias power or voltage are therefore insufficient to fully describe etching characteristics governed by IEDF shape.
In this study, ion energy distribution modulation under RF bias control in an Inductively Coupled Plasma (ICP) etching system was systematically investigated. The effects of bias frequency and bias pulse duty ratio on the IEDF were directly measured using a Retarding Field Energy Analyzer (RFEA). The results show that changes in bias frequency significantly influence the IEDF distribution width and peak separation, while bias pulsing effectively modifies the relative contribution of high and low energy ion components. In particular, reducing the bias duty ratio suppresses high energy ion flux and enhances low energy ion dominance by limiting the effective ion acceleration time during the bias on phase. The impact of IEDF modulation on etching behavior was examined through cross-sectional SEM analysis of 100 nm SiO2 patterned structures with Amorphous Carbon Layer (ACL) masks. Compared to the continuous-wave bias condition, reduced duty ratio operation led to a more stable bottom profile with suppressed profile distortion near the pattern bottom. This behavior is attributed to mitigation of charge accumulation effects during the bias off phase, which relaxes localized electric field distortion at the pattern bottom. Overall, this study demonstrates that bias frequency and pulse duty ratio provide effective and independent control of IEDF shape, and that duty-cycle-based IEDF control is a viable strategy for stabilizing etch profiles in fine pattern plasma etching processes.

목차 (Table of Contents)

• 목 차 ⅰ
• 그림목차 ⅲ
• Ⅰ. 서 론 01
• 1. 연구의 필요성 01
• Ⅱ. 이론적 배경 04
• 1. 플라즈마(Plasma) 04
• 1) 플라즈마 생성 04
• 2) 플라즈마 종류 07
• (1) 용량 결합형 플라즈마(Capacitively Coupled Plasma, CCP) 07
• (2) 유도 결합형 플라즈마(Inductively Coupled Plasma, ICP) 09
• 2. 식각 공정(Etching Process) 11
• 1) 습식 식각(Wet etching) 11
• 2) 건식 식각(Dry etching) 11
• 3. 쉬스와 전하 수송 메커니즘 13
• 4. 이온 에너지 분포(Ion Energy Distribution Function, IEDF) 16
• 5. 바이어스 펄싱(Bias Pulsing)의 개념 18
• Ⅲ. 연구 방법 20
• 1. 실험 장치 구성 20
• 2. 실험 조건 선정 및 공정 설계 기준 23
• 3. 측정 및 분석 장비 25
• 1) RFEA(Retarding Field Energy Analyzer) 25
• 2) FE-SEM(Field Emission Scanning Electron Microscope) 28
• Ⅳ. 연구 결과 및 고찰 30
• 1. Ion Energy Distribution Function 30
• 1) Source Power 30
• 2) Bias Frequency 33
• (1) Bias Voltage 변화에 따른 주파수별 IEDF 33
• (2) 동일 Bias Voltage 조건에서 주파수별 IEDF 37
• 3) Bias Pulsing Duty Ratio 39
• 2. Etch Profile 42
• Ⅴ. 결 론 46
• 참 고 문 헌 48
• 영 문 초 록 49