실시간 챔버 오염 진단 센서 개발

다국어 초록 (Multilingual Abstract)

In plasma processing, polymer accumulation within the chamber can affect process stability and repeatability; however, there are limitations in diagnosing this behavior in real time during processing. In this study, a polymer thickness sensor based on resonance frequency changes of a quartz crystal was developed to enable real-time, in-situ diagnostics of polymer accumulation behavior inside a plasma chamber, and its applicability was evaluated.
The developed sensor was fabricated using a flexible printed circuit board (FPCB)-based structure, allowing installation at various locations inside a plasma chamber, and it maintained stable frequency response characteristics under repeated exposure to plasma environments. Under inductively coupled plasma (ICP) processing conditions, the sensor exhibited a consistent decrease in frequency corresponding to polymer accumulation even during long-duration processes, and reproducibility was confirmed through repeated measurements. In addition, the correlation between the sensor frequency change and the polymer thickness measured using an Alpha-step profilometer was verified.
Furthermore, analysis using a VI-probe showed that changes in sensor frequency and plasma impedance were observed at similar time points, confirming a relationship between polymer accumulation and variations in plasma state. As an extension of this study, the sensor was applied to an atomic layer etching (ALE) process. During the deposition step, the sensor frequency change exhibited consistent behavior as the deposition time varied, and reversible response characteristics were maintained under repeated deposition–cleaning cycles. Moreover, an increasing trend in the etch per cycle (EPC) of Si3N4 was observed with increasing deposition time.
X-ray photoelectron spectroscopy (XPS) analysis confirmed the formation of fluorocarbon-related species on the substrate surface after the deposition step, supporting that the deposition behavior observed through sensor frequency changes corresponds to actual changes in surface chemical state. These results demonstrate that the polymer thickness sensor developed in this study is an effective tool for in-situ diagnostics of polymer accumulation behavior in plasma processing and ALE processes.

목차 (Table of Contents)

• 목 차 ⅰ
• 그림목차 ⅲ
• Ⅰ. 서 론 01
• 1. 연구 필요성 01
• Ⅱ. 이론적 배경 04
• 1. 플라즈마(Plasma) 04
• 1) 플라즈마 방전 04
• 2) 플라즈마 종류 및 장비 07
• 2. 식각 공정 12
• 1) 습식 식각 12
• 2) 건식 식각 12
• 3) 원자층 식각 공정(Atomic Layer Etching, ALE) 13
• 3. 플라즈마 진단 14
• 4. 플루오로카본 폴리머 형성 매커니즘 15
• Ⅲ. 연구 방법 17
• 1. 폴리머 두께 측정 센서 개발 17
• 1) 폴리머 두께 센서 제작 및 원리 17
• 2) 폴리머 두께 센서 측정 시스템 19
• 2. 실험에 사용된 측정 및 분석 장치 21
• 1) 알파스텝(Alpha-step) 21
• 2) VI-probe 21
• 3) X-ray Photctron Spectroscopy(XPS) 23
• Ⅳ. 연구 결과 25
• 1. 폴리머 두께 센서의 동작 특성 및 신뢰성 평가 25
• 2. 폴리머 두께 센서와 실제 폴리머 두께 간의 상관관계 27
• 3. 폴리머 축적에 따른 플라즈마 전기적 특성 변화 29
• 4. 폴리머 두께 센서와 VI-probe 신호 간의 상관관계 31
• 5. 공정 가스 조건 변화에 따른 폴리머 형성 거동 33
• Ⅴ. 확장 연구 : ALE 공정 적용 35
• 1. ALE 공정 진단을 위한 폴리머 두께 센서 적용 35
• 1) ALE 공정 시스템 구성 및 센서 배치 35
• 2) ALE 공정 사이클 개요 37
• 2. 흡착(증착) 단계에서의 센서 주파수 거동 39
• 3. 증착-세정 공정 반복에 따른 센서 주파수 거동 41
• 4. 증착 시간에 따른 Si3N4 원자층 식각 43
• 5. 흡착 시간에 따른 표면 화학 상태 분석 45
• 1) XPS 전체 스펙트럼 분석 45
• 2) High-resolution C 1s 및 F 1s 분석 47
• Ⅵ. 결 론 49
• 참 고 문 헌 50
• 영 문 초 록 52
• 감 사 의 글 54