Nonequilibrium Nitrogen Spike Annealing for Crystallization Enhancement Achieves High Mobility and Reliability in IGO TFTs

Abstract Poly‐crystallized In‐Ga‐O (IGO) semiconductor has the potential for application in high‐density memory and back end of line (BEOL) integration with CPU. Since the development of In 2 O 3 ‐based multi‐cation oxides, i.e., IGZO, such material is very difficult to be poly‐crystallized under the limitation of BEOL temperature. Here, a novel Nitrogen‐Spike Annealing (NSA) method is demonstrated, this nonequilibrium annealing process utilizes a transient high temperature to induce crystallization while reducing the overall thermal budget. During NSA, the O atoms are more intended to bond with Ga, resulting in a more rigid framework that stabilizes the O atoms. The crystal orientation of the NSA treated IGO film is more concentrated compared with the conventional equilibrium annealed one. Furthermore, poly‐IGO thin‐film transistors (TFTs) with high crystallinity and more centered crystal orientation are demonstrated through material characterization. Electrical characteristics revealed that the poly‐IGO TFT exhibits high mobility of ≈86.2 cm 2 V s −1 and enhanced reliability after NSA treatment. These findings will advance the design and improvement of oxide semiconductor memory applications.