TMR sensor having magnesium/magnesium oxide tunnel barrier
View Patent ↗A tunnel junction magnetoresistive sensor having improved TMR performance (dR/R) and improved area resistance. The sensor includes a barrier layer sandwiched between a magnetic pinned layer structure and a magnetic free layer structure. The barrier layer includes a thin layer of Mg and a layer of MgO x . The barrier layer could also include a second thin layer of Mg such that the MgO x layer is sandwiched between the first and second Mg layers.
1. A tunnel junction magnetoresistive sensor, comprising:
a magnetic pinned layer structure;
a magnetic free layer structure; and
a barrier layer sandwiched between the pinned layer structure and the free layer structure, the barrier-layer structure further comprising:
a first layer of unoxidized Mg;
a layer of MgO x ; and
a second layer of unoxidized Mg, the layer of MgO x being sandwiched between the first and second layers of unoxidized Mg.
2. A sensor as in claim 1 wherein the first and second layers of unoxidized Mg each have a thickness of 1-2.5 Angstroms.
3. A sensor as in claim 1 wherein the first and second layers of unoxidized Mg each have a thickness of 1-2.5 Angstroms and the MgO x layer has a thickness of 2-10 Angstroms.
4. A sensor as in claim 1 wherein the first and second layers of unoxidized Mg each have a thickness of about 2 Angstroms.
5. A sensor as in claim 1 wherein the first and second layers of unoxidized Mg each have a thickness of about 2 Angstroms and the MgO x layer has a thickness of 2-10 Angstroms.
6. A magnetic data recording system, comprising:
a housing;
a magnetic disk rotatably mounted within the housing;
a slider;
an actuator connected with the slider for moving the slider relative to a surface of the disk; and
a tunnel junction magnetoresistive sensor connected with the slider, the sensor further comprising:
a magnetic pinned layer structure;
a magnetic free layer structure; and
a barrier layer sandwiched between the pinned layer structure and the free layer structure, the barrier-layer structure further comprising:
a first layer of unoxidized Mg;
a layer of MgO x ; and
a second layer of unoxidized Mg, the layer of MgO x being sandwiched between the first and second lavers of unoxidized Mg.
7. A data recording system as in claim 6 wherein the first and second layers of unoxidized Mg each have a thickness of 1-2.5 Angstroms.
8. A data recording system as in claim 6 wherein the first and second layers of unoxidized Mg each have a thickness of 1-2.5 Angstroms and the layer of Mg has a thickness of 2-10 Angstroms.
9. A method for manufacturing a tunnel junction magnetoresistive sensor, comprising: placing a wafer into an ion beam deposition chamber;
performing a first ion beam deposition using a Mg target, in the absence of oxygen to form a first thin unoxidized Mg layer;
performing a second ion beam deposition using the Mg target and introducing oxygen into the chamber to form a MgO x layer; and
performing a third ion beam deposition using the Mg target, in the absence of oxygen to form a second unoxidized Mg layer over the MgO x layer;
followed by oxidation.
10. A method as in claim 9 wherein the first and third ion beam depositions are performed sufficiently to form the first and second Mg layers with a thickness of 1-2.5 Angstroms each.