Area selective atomic layer deposition (AS-ALD) for electronic device applications
Date of Issue2018
School of Electrical and Electronic Engineering
Due to the continuous shrinking of microelectronic devices, nanoscale materials are being deposited and stacked into the high density multilayer structures (e.g. 3D-FETs, interconnects, core shell structures, etc). However, advanced and novel process methods are required for the fabrication of these devices to meet the deposition of these materials for multilayer structures. Due to unique properties, such as conformality and uniformity, Atomic Layer Deposition (ALD) is a commonly used deposition method in the fabrication of these types of devices. In this work, we describe the area selective atomic layer deposition using self-assembled monolayers, SAMs (DDT, OTS, and ODTS) and atomic layer deposition (ALD). Area selective ALD (AS-ALD) can be used in advanced memory devices (e.g. flash memory, ReRAM, etc.) can also be realized with less number of fabrication steps as compared to traditional VLSI process. The main focus of this study was to perform selective atomic layer deposition of Diethyl Zinc (Precursor for ZnO) and Trimethyl Aluminium (Precursor for Al2O3) using Octyltrichloro silane (OTS), Octadecyltrichloro silane (ODTS) and Dodecyl Thiol (DDT) monolayers as resists. Metal-oxide patterns, metal-dielectric patterns were fabricated and blocking properties of these monolayers were investigated. All the experiments for this study were done on Si/SiO2-Cu and Si/SiO2 blanket substrates and Cu/Si-SiO2 micro-patterns. Throughout this study, we worked with alkyl silane SAMs (OTS and ODTS) and thiol (DDT) SAMs. Here, we used surface characterization techniques such as Water Contact Angle (WCA), Attenuated Total Reflectance Infrared Spectroscopy (ATR-IR), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) to study the SAMs and selective deposition. These results show that ODTS (~3.5nm) is more effective than OTS (2nm) in terms of blocking of Al2O3, and that DDT is good blocking agent for ZnO (15nm) as compared to Al2O3 (1.5nm). These results will be helpful for the selective deposition of materials on variety of patterns and 3-D structures such as capacitors, memory devices, transistors and core-shell structures, etc.
DRNTU::Engineering::Electrical and electronic engineering