Top-pinned perpendicular MTJ structure with a counter bias magnetic field layer for suppressing a stray-field in highly scalable STT-MRAM

We propose a new top-pinned perpendicular MTJ structure that can both achieve the magnetic stability of a pinned layer and reduce a magnetic stray-field to a free layer. The key point of the structure is that there is a large design margin of a pin configuration for the stray-field reduction due to a counter bias magnetic field layer being used instead of a SAF structure. Stable switching performances were successfully obtained without application of an external magnetic field in our 50nmF or less MTJs.