Wafer-Scale Demonstration of Polycrystalline MoS2 Growth on 200 mm Glass and SiO2/Si Substrates by Plasma-Enhanced Atomic Layer Deposition

Abstract

2D materials like transition metal dichalcogenides (TMDCs) have been widely studied and are a gateway to modern technologies. While research today is mostly carried out on a laboratory scale, there is an intensive need for reliable processes on a wafer-scale, starting with monolayer-precise deposition of high-quality films. In this work, a plasma-enhanced atomic layer deposition (PEALD) process is developed on a 200 mm SiO₂/Si substrate. The layers are investigated regarding crystallinity, composition, homogeneity, microstructure, topography, and electrical properties. The process is then applied on 200 mm alkali-free glass wafers aiming toward flexible electronics and compatibility with Si processes. A complete coverage of the wafer with a satisfying uniformity is achieved on both substrates and direct polycrystalline growth of MoS₂ films is verified on the entire wafer at a substrate temperature of T = 230 °C. On glass, the deposited MoS₂ films exhibit a higher crystallinity and are more planar compared to the SiO₂/Si substrate. Furthermore, application relevant few-nanometer thick layers are investigated in detail. This low-temperature process inspires optimism for future direct integration of 2D-materials in an economical bottom-up approach on a wide variety of substrates, thus paving the way for industrial mass production.