Area-Selective Atomic Layer Deposition of Oxide Thin Films for Atomic Level Patterning of Next-Generation Nanodevices

다국어 초록 (Multilingual Abstract)

In this study, we achieved high selectivity using several approaches for area-selective atomic layer deposition of multiple oxide thin films used in the fabrication of next-generation nanoelectronic devices. For the selective deposition of SiO2 thin films on oxide versus nitride substrates, we developed an area-selective atomic layer deposition method that utilizes the inherent selective adsorption properties of aminosilane precursors. Through density functional theory calculation, we theoretically observed the difference in activation energy required for reaction with the -OH, -NH2 surface functional groups of the aminosilane precursor. And the selective adsorption of the precursor onto the oxide substrate was also experimentally demonstrated through contact angle measurement after exposure of the precursor to the oxide and nitride substrates. In this research, it was confirmed that the selectivity decreases with time due to oxidation of the SiN thin film, So to prevent oxidation of the substrate, the Q-time was adjusted after fabrication of the SiN thin film to reproduce the initial selectivity. Two precursors were used, and the atomic layer deposition process using DIPAS+O3 showed an inherent selectivity of 4 nm, and the atomic layer deposition process using BDIPADS+O3 showed an inherent selectivity of ~1 nm. To further improve the selectivity, a supercycle of repeated atomic layer deposition and etching was used to achieve selectivities of over 10 nm in the DIPAS process and 5 nm in the BDIPADS process. The DIPAS process has demonstrated selectivity of 4 nm not only in two-dimensional patterned substrates but also in three-dimensional patterns. For the selective deposition of Al2O3 thin films on oxide versus metal substrates, we developed an area-selective atomic layer deposition method that suppresses deposition by selectively adsorbing thiol-based self-assembled monolayers on metal substrates. A thiol-based self-assembled monolayer is an organic compound containing sulfur, and the organic monolayer is aligned only on the metal surface through the bond between metal and sulfur. To increase the effectiveness of these inhibitors, the role of precursors and reactants used in atomic layer deposition is also important. In industry, the TMA+O3 process is mainly used to deposit Al2O3 thin films. However, in order to increase the selectivity, the atomic layer deposition of Al2O3 using DMAI, which has lower reactivity and larger molecular size than TMA, was used as the precursor. And H2O was used as the reactant instead of O3, which is a strong oxidant that damages the organic monolayer formed on the surface. Three inhibitors were evaluated for each carbon chain length of the thiol-based self-assembled monolayer, and hexanethiol was found to have the highest contact angle increase and deposition thickness selectivity. Additionally, during the Al2O3 deposition process, we observed through contact angle measurements that the inhibitor degraded on the cobalt substrate after 30 cycles. To improve this, hexanethiol was re-dosed every 30 cycles of the atomic layer deposition process to deactivate the surface, and the deposition of Al2O3 on the cobalt substrate was effectively suppressed, showing a high selectivity of 16 nm.

목차 (Table of Contents)

• Abstract
• Chapter 1. Introduction 1
• 1.1 Need for bottom-up process 1
• 1.2 Atomic Layer Deposition (ALD) 2
• 1.3 Area-Selective Atomic Layer Deposition (AS-ALD) 6
• 1.3.1 Inhibitor-free AS-ALD 9
• 1.3.2 Inhibitor-assisted AS-ALD 11
• 1.3.2.1 Self Assembled Monolayer (SAM) 11
• 1.4 Analysis techniques 13
• 1.4.1 Spectroscopy ellipsometry (SE) 13
• 1.4.2 Contact angle measurement 15
• 1.4.3 X-ray photoelectron spectroscopy (XPS) 16
• 1.4.4 Auger electron spectroscopy (AES) 18
• 1.5 Reference 20
• Chapter 2. Inhibitor-free AS-ALD of SiO2 Thin Films on Oxide
• versus Nitride substrates
• 2.1 AS-ALD SiO2 using aminosilane precursor
• 2.1.1 Introduction
• 2.1.2 Experimental
• 2.1.3 Results and discussion
• 2.1.4 Conclusion
• 2.1.5 Reference
• 2.2 AS-ALD SiO2 using aminodisilane precursor
• 2.2.1 Introduction
• 2.2.2 Experimental
• 2.2.3 Results and discussion
• 2.2.4 Conclusion
• 2.2.5 Reference
• 2.3 Study of selective adsorption Aldehyde inhibitor on Oxide
• versus Nitride substrates
• 2.3.1 Results and discussion
• 2.3.2 Reference
• Chapter 3. AS-ALD of Al2O3 Thin Films for Metal versus
• Dielectric Selectivity using Vapor-Dosed Alkanethiols
• 3.1 AS-ALD Al2O3 using thiol inhibitor
• 3.1.1 Introduction
• 3.1.2 Experimental
• 3.1.3 Results and discussion
• 3.1.4 Conclusion
• 3.1.5 Reference
• Chapter 4. Conclusion
• Abstract (in Korean)
• Acknowledgements