저온하이브리드본딩을위한후속열처리및고온/고습 조건에 따른 SiO2-SiO2 접합부의계면접착에너지에관한연구

다국어 초록 (Multilingual Abstract)

As modern digital devices continue to shrink in size, the semiconductors integrated within electronic systems must also be aggressively miniaturized. However, the physical limits of semiconductor device scaling have been reached, making alternative approaches necessary. In this context, three-dimensional (3D) integrated circuit (IC) packaging has attracted significant attention as a promising solution. Compared with conventional two-dimensional planar packaging, 3D integration enhances performance by reducing RC delay and power consumption, enabling device miniaturization, and achieving high input/output (I/O) signal density. It also allows the stacking of heterogeneous devices, the integration of otherwise incompatible process technologies, and structural optimization for modular applications. A key enabler of 3D IC packaging is the through-silicon via (TSV) process. In current TSV technology, bonding is typically achieved using Sn-based solder and Cu. However, interdiffusion between Cu and Sn leads to the formation of intermetallic compounds (IMCs), which severely deteriorate the mechanical and electrical reliability of the bonding interface. To overcome these limitations and meet the demands for high-density, high-performance device integration, Cu/dielectric hybrid bonding has emerged as a next-generation packaging solution, enabling bumpless Cu pad bonding. Hybrid bonding requires a chemical mechanical polishing (CMP) process to planarize the surface and secure bonding quality. After CMP, the Cu surface exposed to the atmosphere rapidly reacts with oxygen, forming a Cu oxide layer. Furthermore, achieving Cu–Cu bonding typically requires bonding temperatures exceeding 400 °C, which imposes a significant thermal budget on other devices within 3D packaging structures. Therefore, in low-temperature hybrid bonding, pretreatment processes for activating the Cu and SiO2 surfaces, generating a hydrophilic SiO2 surface, and suppressing Cu oxidation are essential. In this study, a two-step Ar/N2 plasma treatment was employed. In the first step, the SiO2 surface was activated using Ar plasma, and in the subsequent step, N2 plasma treatment was applied to form Si-N bonds on the surface. To evaluate the effect of the plasma treatment, surface XPS analysis and surface energy measurements were carried out. The results confirmed the formation of various Si-N bonding states after plasma exposure, accompanied by an increase in surface energy. Subsequently, the influence of post-bond annealing conditions on the quantitative interfacial adhesion energy of the SiO2-SiO2 bonding interface was investigated. The interfacial adhesion energies of the specimens annealed at 200, 250, 300, and 350 °C were determined to be 1.27, 1.40, 2.02, and 2.22 J/m², respectively. Fracture surface analysis revealed that delamination occurred along the SiO2/SiO2 bonding interface under all annealing conditions. The observed increase in interfacial adhesion energy with increasing annealing temperature is attributed to the dehydration of Si-OH groups at the bonding interface and their subsequent conversion into Si-O-Si bonds as the post-bond annealing temperature rises. To evaluate the effect of moisture on the SiO2/SiO2 bonding interface, temperature/humidity testing was conducted under 85 °C/85% RH for 96 h, followed by interfacial adhesion energy measurements. The results showed that the interfacial adhesion energy decreased for all post-bond annealing conditions. This reduction is attributed to the penetration of moisture into the bonding interface during the temperature/humidity test, which is believed to convert Si-O-Si bonds formed at the interface back into Si-OH bonds, thereby lowering the interfacial adhesion energy.
Therefore, in SiO2-SiO2 bonding, the two-step Ar/N2 plasma treatment can enhance the bonding quality and increase the interfacial adhesion energy. For low-temperature hybrid bonding, it is therefore crucial to determine the optimal post-bond annealing conditions and to clarify the mechanisms by which moisture degrades interfacial reliability.

목차 (Table of Contents)

• 제 1 장 서 론 1
• 제 2 장 이론적 배경 4
• 2.1 하이브리드 본딩 기술 4
• 2.2 표면처리 연구 동향 8
• 2.3 박막의 계면접착력 평가 방법 11
• 2.3.1 접착력의 정의 11
• 2.4.2 박막의 접착력 측정 방법 14
• 제 3 장 실험 방법 26
• 3.1 저온 하이브리드 본딩을 위한 SiO2-SiO2 접합 시편 계면접착에너지 평가 26
• 3.1.1 2단계 Ar/N2 플라즈마 처리 유무에 따른 접합 단면 분석 시편 제작 26
• 3.1.2 후속 열처리 조건에 따른 계면접착에너지 평가 시편 제작 28
• 3.2 정량적 계면접착에너지 평가 방법 29
• 3.3 시편 표면 및 파면 분석 방법 32
• 3.4 접합 단면 분석 방법 34
• 3.5 고온/고습 조건에 따른 계면접착에너지 평가 및 박리파면 방법 35
• 제 4 장 실험 결과 및 고찰 36
• 4.1 2단계 Ar/N2 플라즈마 처리 유무에 따른 SiO2 표면 분석 36
• 4.1.1 SiO2 표면 분석 36
• 4.1.2 접합 단면 분석 48
• 4.1.3 계면접착에너지 평가 50
• 4.2 후속 열처리 조건에 따른 SiO2 표면 분석 및 계면접착에너지 평가 · 52
• 4.2.1 SiO2 표면 분석 52
• 4.2.2 접합 단면 분석 및 계면접착에너지 평가 55
• 4.2.3 계면접착에너지 평가 및 박리 파면 분석 59
• 4.3 고온/고습 조건에 따른 계면접착에너지 평가 및 박리파면 분석 65
• 4.3.1 고온/고습 실험에 따른 계면접착에너지 평가 65
• 4.3.2 계면접착에너지 평가 이후 박리 파면 분석 67
• 제 5 장 결론 71
• 참고 문헌 73
• Abstract 76
• 감사의 글 79