Composite free layer within magnetic tunnel junction for MRAM applications
US9159908B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 5, 2011 |
| Grant date | Oct 13, 2015 |
| Priority date | — |
| Expiry date | Mar 26, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F10/3272
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A magnetic tunneling junction (MTJ) in an MRAM array is disclosed with a composite free layer having a FL1/FL2/FL3 configuration where FL1 and FL2 are crystalline magnetic layers and FL3 is an amorphous NiFeX layer for improved bit switching performance. FL1 layer is CoFe which affords a high magnetoresistive (MR) ratio when forming an interface with a MgO tunnel barrier. FL2 is Fe to improve switching performance. NiFeX thickness where X is Hf is preferably between 20 to 40 Angstroms to substantially reduce bit line switching current and number of shorted bits. Annealing at 330° C. to 360° C. provides a high MR ratio of 190%. Furthermore, low Hc and Hk are simultaneously achieved with improved bit switching performance and fewer shorts without compromising other MTJ properties such as MR ratio. As a result of high MR ratio and lower bit-to-bit resistance variation, higher reading margin is realized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.