| AVS 62nd International Symposium & Exhibition | |
| Selective Deposition as an Enabler of Self-Alignment Focus Topic | Thursday Sessions |
| Session SD+AS+EM-ThM |
| Session: | Fundamentals of Selective Deposition |
| Presenter: | Seunggi Seo, Yonsei University, Republic of Korea |
| Authors: | S. Seo, Yonsei University, Republic of Korea H. Jung, Yonsei University, Republic of Korea I.K. Oh, Yonsei University, Republic of Korea H. Kim, Yonsei University, Republic of Korea J. Yoon, LG Display Co., Ltd., Republic of Korea C. Yoo, LG Display Co., Ltd., Republic of Korea H.-J. Kim, LG Display Co., Ltd., Republic of Korea Y.-B. Lee, LG Display Co., Ltd., Republic of Korea |
| Correspondent: | Click to Email |
Over many past years, area-selective atomic layer deposition (AS-ALD) has been developed for fabricating 3D nanostructures. ALD is a method to deposit thin films by self-limiting surface reactions between supplied gaseous precursors. Since ALD is a surface sensitive deposition technique, surface modification of substrate renders the deposition of films to be area-selective. Most previous studies on AS-ALD have utilized self-assembled monolayer (SAM), which inhibits the chemical reaction between substrate and precursors, so that the film cannot grow on SAM-coated area. AS-ALD has been studied on various materials, such as TiO2, ZnO, and HfO2. Although Al2O3 has been widely used for ALD, there is no experimental report on AS-ALD Al2O3 by using SAM. Rather, a previous report on the calculation of surface reactions between TMA and SAM by density functional theory (DFT) has been presented[1]. That paper describes that CH -terminated SAM shows no thermodynamic driving force for the reaction between them, leading to AS-ALD Al2O3 by using TMA.
In this work, we systematically investigated AS-ALD of Al2O3 on SAM in various conditions, such as SAM coating methods, the kinds of SAM and substrate, and ALD process parameters. Addressing previous calculation report, Al2O3 was deposited on CH3-terminated SAM, octadecyltrichlorosilane (ODTS) and octadecylphosphonic acid (ODPA).
However, we observed Al2O3 layers were formed on SAM coated SiO2 and Ti substrate, which is inconsistent with previous report. To clarify, we investigated ALD Al2O3 on SAM coated substrate by using various analytic techniques such as contact angle measurement, Fourier transform infrared spectroscopy, ellipsometry, X-ray photoelectron spectroscopy (XPS), X-ray-reflectometry (XRR), and α-scanning. We observed TMA was physisorbed on CH3-terminated SAM, leading to Al2O3 deposition. Alternatively, we moved to our research toward the change of SAM coating methods, dipping and stamping, to lift both Al2O3 and underneath SAM coating off. Since stamping method is a faster process than dipping one, so that SAM by stamping might remain randomly distributed as forming weak bonding between SAMs and substrate. Moreover, we chose ODPA as a SAM due to its poor adsorption on SiO2. We observed that both Al2O3 and its underneath ODPA stamped on SiO2 were lifted-off from the substrate, resulting in area-selective Al2O3 pattern. This result opens a new way to patterning techniques for many areas of technology.
[1] Xu et al./ Chem. Mater. 2004, 16, 646-653