GMR sensor having a capping layer treated with nitrogen for increased magnetoresistance
View Patent ↗A magnetoresistive sensor having a Ta cap layer with nitrogen added in situ during deposition. The nitrogen in the cap layer can be formed by depositing a Ta cap layer in a sputter deposition chamber having a small amount of nitrogen in an Ar atmosphere. The resulting nitrogenated cap layer exhibits reduced specular scattering, which results in improved magnetic performance of the magnetoresistive sensor.
1. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer comprises Ta and 30 to 50 atomic percent N.
2. A magnetoresistive sensor as in claim 1 wherein the cap layer comprises Ta having atoms of nitrogen interspersed therein.
3. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer comprises Ta and N and one or more layers comprising Ta and O.
4. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer further comprises:
a first layer comprising TaNO;
a second layer comprising TaN; and
a third layer comprising TaO.
5. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer comprises Ta and N and has a composition that varies at different levels within the cap layer.
6. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer has a first level that comprises TaNO and a second level that comprises TaN.
7. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer has a first level that comprises TaNO and a second level that comprises TaNO with 30-50 atomic percent N.
8. A magnetoresistive sensor as in claim 7 wherein the first level of the cap layer is closest to the free layer.
9. A magnetoresistive sensor comprising:
a magnetic pinned layer structure;
a magnetic free layer structure;
a non-magnetic layer sandwiched between the magnetic pinned layer structure and the magnetic free layer structure; and
a cap layer comprising N disposed over the magnetic free layer structure, magnetic pinned layer structure and non-magnetic layer, wherein the cap layer has a variable composition having a first level closest to the free layer that comprises TaNO, a second layer comprising TaN and a third layer comprising TaO.
10. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer;
exposing the free layer to oxygen; and
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N.
11. A method as in claim 10 wherein the atmosphere further comprises Ar.
12. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer;
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N; and
after depositing the cap layer, exposing the cap layer to oxygen.
13. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer;
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N; and
oxygenating the cap layer in the deposition chamber.
14. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer;
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N; and
exposing the cap layer to atmospheric oxygen resulting in a top portion of the cap layer comprising TaO.
15. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer; and
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N, wherein the top portion of the cap layer includes trace amounts of N.
16. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer; and
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N, wherein a first portion of the cap layer is exposed to oxygen, a second portion of the cap layer is exposed to nitrogen and a third portion of the cap layer is exposed to oxygen.
17. A method for manufacturing a magnetoresisive sensor, comprising
depositing a magnetic pinned layer structure;
depositing a non-magnetic layer over the magnetic pinned layer structure;
depositing a magnetic free layer over the non-magnetic layer; and
depositing a cap layer in a deposition chamber using a Ta target in an atmosphere that includes N, wherein the first portion of the cap layer is deposited first, the second portion of the cap layer is exposed second and the third portion of the cap layer is exposed third.