Atomic Level Patterning Process of SiO2 Thin Films for Advanced Nanoelectronics

Abstract

The degree of integration has been improved by fabricating a vertical structure in which two-dimensional cells of a semiconductor device are stacked in a three-dimensional vertical structure. However, as the aspect ratio of the three-dimensional cell increased dramatically, the process was faced with limitations. In the conventional process for area selective deposition, surface deposition molecules such as self assembled monolayer (SAM) were used to prevent deposition by the SAM' s selective deposition characteristics, but at the high aspect ratio of nanoscale 3D structure, there were many limitations in using SAM. On the other hand, in the atomic layer deposition (ALD), since the thin film is grown only by the reaction on the surface, the thin film formation region can be activated /deactivated by effectively controlling the surface properties. So this study investigated the area selective deposition (ASD) using the ALD method without the surface inhibitory molecule. In this study, used precursors with selective adsorption behavior through density functional theory (DFT) calculations and established the ALD process of silicon dioxide thin films using these precursors. HF solution was used to control the surface properties, and the experiment was conducted by controlling the temperature and ozone exposure time during the ALD SiO2 process conditions. To date, the deposition selectivity of ALD SiO2 on two substrates SiO2 and Si3N4 was confirmed as SiO2 : Si3N4 = 4 : 0. In addition, confirmed that the excellent thin film properties of Si3N4 showed a higher selectivity. The more -NH2 surface properties, the higher the selectivity will be. In conclusion, the above process is expected to enable the next generation atomic patterning process by utilizing the selective adsorption / desorption behavior inside the three-dimensional structure.