Patent ID: 8436437
Filing Date: 2013-05-07
Classification: B82Y,G11C,H01F,H01L

Abstract:
1. An STT-MTJ MRAM cell operating in a CPP configuration and utilizing the transfer, by torque, of conduction electron spin angular momentum to change a free layer magnetization direction, comprising: a substrate; an MTJ element formed on said substrate, said MTJ element comprising a vertically stacked lamination of horizontal parallel layers including, therein, in the following order: an antiferromagnetic pinning layer formed of MnIr, an SyAP pinned layer processed by a plasma process to have a smooth/flat interfacial surface, a tunneling barrier layer formed on said smooth/flat interfacial surface, said tunneling barrier layer having a crystalline structure and comprising a naturally oxidized, sputtered layer of Mg, a ferromagnetic free layer formed on said tunneling barrier layer, said ferromagnetic free layer having a low magnetic damping factor and producing enhanced polarization of conduction electrons, and a capping layer formed on said ferromagnetic free layer, and wherein said ferromagnetic free layer is a composite tri-layer comprising a first interfacial crystalline layer of Fe on which is formed an amorphous ferromagnetic layer of CoFeB, on which is formed a second interfacial crystalline layer of Fe, wherein said first and second interfacial crystalline layers of Fe provide said enhanced polarization of conduction electrons and wherein said amorphous ferromagnetic layer of CoFeB sandwiched therebetween provides said low magnetic damping factor and whereby, a reduction is thereby obtained in the magnitude of a critical spin-polarized current of conduction electrons in the vertical direction required to change the direction of magnetization of said ferromagnetic free layer relative to the magnetization direction of said SyAP pinned layer by means of a torque between the polarized magnetic moments of said conduction electrons and the magnetization of said ferromagnetic free layer without the action of external magnetic fields to produce said change in magnetization.