Reduced Switching Current Density and Improved Interface Quality using Oxynitride Tunnel Barrier in Magnetic Tunnel Junctions for MRAM Application

摘要

Magnetic tunnel junctions (MTJs) have recently been commercialized for memory applications, both as read-head sensors and non-volatile magnetic random-access memories (MRAMs) [1]. The key parameters of MTJs are resistance area (RA) product and write/switching current density (J_C), which affect the device failure and decrease the stability due to localized heating. The RA and J_C are critically influenced by the ferromagnet metal (FM)/tunnel barrier (TB) interface, which therefore, requires maintaining high quality while scaling down. Several techniques to reduce RA and J_C include (1) thinning down the tunnel barrier (TB) effective thickness (EOT) [2], (2) adding ultra-thin metal dust in TB, and (3) modulating the TB with different doping [3], (4) using alternate nitrogen containing TB such as TiON, AlON, h-BN, and TiAlON that are deposited with reactive sputtering and reactive ion-beam deposition techniques [4], [5]. On the other hand, room temperature oxynitride-MTJ has not been explored much in terms of TMR and J_C.