Challenging issues for terra-bit-level perpendicular STT-MRAM

The current challenging issues for terra-bit-level perpendicular STT-MRAM cells have been reviewed in the view of four critical parameters such as TMR ratio, Δ, J
_ex
, and α. The TMR ratio of p-MTJ spin-valves are reaching to <; 150% at the BEOL of >350°C. A single MgO based p- MTJ spin-valve could not satisfy Δ of > 74, proposing a double MgO based p-MTJ spin-valve. J
_ex
in SyAF layer adequately met > 0.7erg/cm
²
at BEOL of > 350°C. A Co
₂
Fe
₆
B
₂
based p-MTJ spin-valve limits to a of 0.005, necessary to develop a low α material such as full Heusler half-metal. Thus, an essential challenge in the future is to satisfy four critical parameters simultaneously at > 350°C and 300-mm TiN electrode wafers.