TMR device with Hf based seed layer
US7476954B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 2007 |
| Grant date | Jan 13, 2009 |
| Priority date | — |
| Expiry date | Aug 1, 2027 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/1291
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A MTJ structure is disclosed in which the seed layer is made of a lower Ta layer, a middle Hf layer, and an upper NiFe or NiFeX layer where X is Co, Cr, or Cu. Optionally, Zr, Cr, HfZr, or HfCr may be employed as the middle layer and materials having FCC structures such as CoFe and Cu may be used as the upper layer. As a result, the overlying layers in a TMR sensor will be smoother and less pin dispersion is observed. The Hex/Hc ratio is increased relative to that for a MTJ having a conventional Ta/Ru seed layer configuration. The trilayer seed configuration is especially effective when an IrMn AFM layer is grown thereon and thereby reduces Hin between the overlying pinned layer and free layer. Ni content in the NiFe or NiFeX middle layer is above 30 atomic % and preferably >80 atomic %.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.