Process for manufacturing a magnetic tunnel junction (MTJ) device
View Patent ↗A process for manufacturing a high performance MTJ it is described: A first cap layer of NiFeHf is deposited on the free layer, followed by a second cap layer of Ru on Ta. The device is then heated so that oxygen trapped in the free layer diffuses into the NiFeHf layer, thereby sharpening the interface between the tunnel barrier layer and the free layer.
1. A process for the manufacture of a magnetic tunnel junction (MTJ) device, that includes a free layer having a magnetic moment, the method comprising:
providing a substrate and depositing thereon a magnetic pinning layer;
depositing a magnetically pinned layer on said pinning layer;
depositing a tunnel barrier layer on said pinned layer;
depositing on said tunnel barrier layer a free layer of NiFe and a first cap layer of NiFeHf;
depositing on said first cap layer a second cap layer of Ru on Ta; and
then heating said device for a time and at a temperature that are sufficient for oxygen trapped in said NiFe free layer to diffuse into said NiFeHf layer, thereby sharpening an interface between said tunnel barrier layer and said NiFe free layer.
2. The process described in claim 1 wherein said heating time is between about 1 and 10 hours and said heating temperature is between about 250 and 300° C.
3. The process described in claim 1 wherein said NiFeHf layer contains about 15 atomic percent of hafnium and wherein said NiFeHf layer is formed through co-sputtering from a NiFe target, containing about 12 atomic percent iron, and a Hf target onto said substrate while said substrate rotates.
4. The process described in claim 1 wherein said tunnel barrier layer is selected from the group consisting of AIOx, MgO, AlHfOx, AlTiOx, and TiOx.