| 학회 | 한국재료학회 |
| 학술대회 | 2019년 가을 (10/30 ~ 11/01, 삼척 쏠비치 호텔&리조트) |
| 권호 | 25권 2호 |
| 발표분야 | A. 전자/반도체 재료 분과 |
| 제목 | Mechanistic Study of Different Cleaning Methods to Remove Ceria Particles from Silicon Oxide Surface |
| 초록 | During shallow trench isolation (STI) chemical mechanical polishing (CMP), the interaction between Ceria (cerium oxide, CeO2) abrasive particle and silicon oxide (SiO2) surface is crucial for increasing process yields. Especially, removal of ceria particle is very critical to consider in post CMP cleaning. It is hypothesized that Ceria particles are strongly attached to silicon oxide surface by Ce-O-Si bonding. In this study, cleaning process was evaluated to remove ceria particle on SiO2 surface after CMP with different pH ceria slurries. Physical and chemical cleaning methods were compared to observe the effect of process on ceria removal. To prepare the polished samples, 300 mm TEOS wafer was sliced into 4x4 cm coupons. 100 nm ceria particles (US Research Nanomaterials Inc., USA) were used as abrasive. 0.1wt% ceria slurries were prepared in DI water without additives at pH 4 & 8 for all experiments. CMP experiments were carried out on a friction polisher (Poli-500, G&P Tech., Korea). After polishing, the contaminated samples were cleaned using physical cleaning methods (brush/ megasonic) as well as conventional chemistries such as SC1(Standard Clean), SPM(Sulfuric acid Peroxide Mixture) and DHF(Dilute Hydrogen Fluoride). To observe the effect of brush scrubbing, a lab designed pin type brush equipment was used at the optimized conditions, whereas megasonic cleaning was performed using rod type single wafer cleaner (Akrion Systems LLC, USA). Standard conditions were maintained for evaluating the effect of chemistries. Polished samples were dipped in SC1(1:1:5 at 70℃) for 10 minutes whereas in DHF (1:100 at RT) and SPM (4:1 at 90~110℃) for 60 seconds. Samples and slurryies were analyzed using FESEM (MIRA3, TESCAN), XPS (K-alpha plus, Thermo Scientific, U.S.A.) and zeta-potential analyzer (ELS-Z, Otsuka electronics, Japan), before and after cleaning. As a result, Megasonic was found to be inefficient for successful removal whereas brush scrubbing effectively removed weakly attached particles (electrostatic attraction). Physical cleaning methods failed to break Ce-O-Si bonding whereas only a strong chemistry such as DHF and SPM could effectively remove ceria, as confirmed by FESEM & XPS. |
| 저자 | 한소영1, 박진구1, Samrina Sahir2, Nagendra Prasad Yerriboina1, 한광민1 |
| 소속 | 1한양대, 2재료화학공학과 |
| 키워드 | Ceria post CMP cleaning; Ce-O-Si bonding; Chemical cleaning |
