Samsung developed a perpendicular MTJ element using 17nm technology - the world's smallest. This paves the way towards sub-20nm STT-MRAM. Up until now it was believed that to create such a small P-MTJ you will have to use a multi-layer structure and a rare-earth material for the ferromagnetic electrode. Samsung however used regular materials and structure (Ta/CoFeB/MgO/Ta) and optimized the oxidation process for the tunnel insulator (MgO).
By increasing the anisotropic energy on the joint interface the perpendicular magnetization of the ferromagnetic electrode was stabilized. Samsung reports a thermal stability factor of 34, a TMR ratio of 70% and a writing current of 44microampere with a perpendicular magnetization MTJ element whose cross-section area is 17 x 40nm. There is still room for improvement in the thermal stability factor in order to achieve over 1Gbit capacity at 20nm. This can be realized by making more improvements to the newly developed oxidation process for the tunnel insulator