Oxide semiconductor thin film transistors (TFTs) are promising materials for adoption in display and memory devices due to their large-area uniformity and low off-current characteristics. Because of the scaling down of devices, a uniform deposition technique is required to fabricate devices of high aspect ratio. Atomic layer deposition (ALD) is based on self-limited reaction, which enables conformal coating of high-aspect-ratio substrates. In this study, highly oriented crystalline indium−gallium−zinc oxide (IGZO) thin films and TFTs incorporating such films are fabricated by using plasmaenhanced ALD (PEALD). The postannealing process is conducted at 400−700 °C with 100 °C intervals. As the annealing temperature increases, the device performances and reliability gradually degrade. High density and highly ordered crystalline IGZO thin films are obtained at high annealing temperature. However, the device characteristics using such films are degraded due to the dramatically reduced hydrogen content in the oxide semiconductor at high annealing temperature. This study shows that highly ordered IGZO thin films can be deposited by ALD. If the process used to fabricate highly ordered IGZO thin films could retain moderate hydrogen content, it would be possible to manufacture oxide TFTs with excellent electrical performances.

No abstract

No abstract

As the scale‐down and power‐saving of silicon‐based channel materials approach the limit, oxide semiconductors are being actively researched for applications in 3D back‐end‐of‐line integration. For these applications, it is necessary to develop stable oxide semiconductors with electrical properties similar to those of Si. Herein, a single‐crystal‐like indium–gallium–zinc–oxide (IGZO) layer (referred to as a pseudo‐single‐crystal) is synthesized using plasma‐enhanced atomic layer deposition and fabricated stable IGZO transistors with an ultra‐high mobility of over 100 cm2 Vs−1. To acquire high‐quality atomic layer deposition‐processed IGZO layers, the plasma power of the reactant is controlled as an effective processing parameter by evaluating and understanding the effect of the chemical reaction of the precursors on the behavior of the residual hydrogen, carbon, and oxygen in the as‐deposited films. Based on these insights, this study found that there is a critical relationship between the optimal plasma reaction energy, superior electrical performance, and device stability.