Composition Optimization and Device Understanding of Si-Ge-As-Te Ovonic Threshold Switch Selector with Excellent Endurance

In this work we explore the composition space of the Ovonic Threshold Switch (OTS) selector device based on Si-Ge-As-Te material system. Physical Vapor Deposition (PVD) co-sputtering capabilities enabled the tuning of the As/Te ratio, Ge and Si content to increase the crystallization temperature TX>450°C. Guided by ab initio calculations, we optimize the composition and achieve stable endurance characteristics of more than 10
¹¹
cycles on 65nm devices fabricated on 300mm wafers. Finally, we propose a switching model that can predict the statistical distribution of the threshold voltage (VTH), explaining V
_TH
drift and time-dependent instabilities.