Composite free layer within magnetic tunnel junction for MRAM applications

摘要: A MTJ in an MRAM array is disclosed with a composite free layer having FL1/FL2/FL3 configuration where FL1 and FL2 are crystalline magnetic layers FL3 amorphous NiFeX for improved bit switching performance. CoFe which affords high magnetoresistive (MR) ratio when forming interface MgO tunnel barrier. Fe to improve thickness X Hf preferably between 20 40 Angstroms substantially reduce line current number of shorted bits. Annealing at 330°C 360°C provides MR 190%. Furthermore, low He Hk simultaneously achieved performance fewer shorts without compromising other properties such as ratio. As result lower bit-to-bit resistance variation, higher reading margin realized.