Exploration of Chemical Composition of In–Ga–Zn–O System via PEALD Technique for Optimal Physical and Electrical Properties

Abstract

In–Ga–Zn–O (IGZO) material has been researched due to its favorable electrical characteristics for application in thin‐film transistor (TFT) applications such as low off current and relatively high mobility. However, most recently, as the developing and expanding application fields, conventional IGZO is a challenging aspect because higher mobility and excellent step‐coverage are required to be applied to high‐resolution displays and 3D NAND. In this regard, atomic layer deposition (ALD) is suggested as a novel deposition method for tackling issues. Here, this work systematically synthesizes IGZO films with various compositions by the supercycle technique of plasma‐enhanced ALD (PEALD) to determine the optimum metal cation composition range of the IGZO system for high‐mobility TFTs. The trends in the metal composition dependent electrical properties of ALD processed IGZO films are comparable to the previously reported results, while the structural properties are exclusive. Since both microstructure and carrier concentration affect to device characteristics complexly, the optimal In–Ga–Zn region is newly demonstrated via PEALD (XIn: 0.56–0.63, XGa: 0.13–0.17, XZn: 0.17–0.34). In this region, the device exhibits a remarkably high µFE of 41.4–43.7 cm2 V−1 s−1, a low subthreshold swing (SS) of 0.24–0.25 V decade−1, an initial threshold voltage (Vth) of −0.9 to −1.0 V, and a slight Vth shift (0.01 V) under the positive bias temperature stability (PBTS).

Oxide and 2D TMD semiconductors for 3D DRAM cell transistors

“…Researchers have explored diverse compositional tuning to extend the application of OSs beyond a -IGZO, aiming to maximize mobility and to improve reliability. 21,22 Beyond IGZO, a variety of OSs with different combinations, including binary oxides (In 2 O 3 , ZnO), 23,24 ternary oxides (IGO, IZO), 25–27 and further combinations like IZTO 28 and IGZTO, 29 has been researched. It is noteworthy that the majority of research and development in the field of OS thin-film transistors (TFTs) has been directed towards their application in flat-panel displays, where the physical channel length tends to be longer, exceeding 1 μm.…”

Strong Immunity to Drain-Induced Barrier Lowering in ALD-Grown Preferentially Oriented Indium Gallium Oxide Transistors

“…To date, numerous studies have been reported to increase the μ FE in oxide TFTs using various approaches such as Sn-doped InGaZnO (IGZO), − optimization of the cation composition, − crystallization, − heterojunctions, − dual-gate structures, adjusting channel thickness, and postdeposition annealing (PDA) temperature. , Among them, the crystallization via the PDA is one of the simplest and the most effective approaches to improve the μ FE . However, the crystallization of oxide semiconductors with a ZnO component is generally accomplished at a high temperature (>700 °C) due to its corner-sharing crystal configuration different from In 2 O 3 and Ga 2 O 3 with an edge-sharing configuration crystal structure .…”

Effects of Oxygen Flows and Annealing Temperatures on Optical, Electrical, and Structural Properties of Co-Sputtered In2O3-Ga2O3-Zn Thin Films

“…The study revealed that effective passivation through the use of an octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) substantially improved the electrical performance of IGZO TFTs. Hong et al [24] recently investigated the metal cation composition range of the IGZO system through atomic layer deposition (ALD) to achieve high mobility and robust device stability. The IGZO films with various compositions by sequential plasma-enhanced ALD (PEALD) were synthesized to evaluate the microstructure, physical, and electrical properties.…”