Magnetoresistive element, and production method for magnetoresistive element
Provided is a production method for a magnetoresistive element including treating a stacked layer into a predetermined shape. The stacked layer includes a magnetoresistive layer whose resistance changes depending on a magnetic field and a cap layer above the magnetoresistive layer and having a thickness in a range of 10 nm to 60 nm. The method further includes covering and protecting the stacked layer with an insulating layer, forming an opening in the insulating layer by reactive etching and exposing a surface of the cap layer at the opening, etching the cap layer in a range less than a total thickness of the cap layer by ion milling of the surface, and depositing an upper layer to be a part of the magnetoresistive element. The upper layer is in contact with the surface of the cap layer after the etching.
1. A production method for a magnetoresistive element, comprising:
treating a stacked layer into a predetermined shape, the stacked layer including a magnetoresistive layer whose resistance changes depending on a magnetic field and a cap layer which is above the magnetoresistive layer and which has a layer thickness in a range of 10 nm to 60 nm;
covering and protecting the stacked layer with an insulating layer;
forming an opening in the insulating layer by reactive etching and exposing a surface of the cap layer at the opening;
etching the cap layer in a range less than a total layer thickness of the cap layer by ion milling of the surface of the cap layer which is exposed at the opening in the exposing; and
depositing an upper layer to be a part of the magnetoresistive element, the upper layer being in contact with the surface of the cap layer which is left after the etching.
2. The production method for a magnetoresistive element according to claim 1 , wherein, in the etching, a layer thickness of the cap layer etched by ion milling is in a range of 0.5 nm to 59.5 nm.
3. The production method for a magnetoresistive element according to claim 1 , wherein one or more materials of the cap layer are selected from the following: Ru, Ta, Al, Ag, Au, Si, Ti, V, Zr, Nb, Mo, Hf, and W.
4. The production method for a magnetoresistive element according to claim 1 , wherein a material of the insulating layer is thermally oxidized silicon, and a gas for processing used in the reactive etching is a mixed gas including fluorine and oxygen.
5. The production method for a magnetoresistive element according to claim 1 , wherein an outer edge of the opening formed in the forming is inside an outer edge of the cap layer which has been treated in the treating.
6. A magnetoresistive element comprising:
a magnetoresistive layer whose resistance changes depending on a magnetic field;
a cap layer above the magnetoresistive layer; and
an upper layer which is a part of the magnetoresistive element and in contact with the surface of the cap layer,
wherein the cap layer has a hollow structure which is a hollow surface on an opposite side of the magnetoresistive layer,
wherein the upper layer which is a part of the magnetoresistive element is in contact with an inner bottom surface of the hollow surface, and
wherein the cap layer has a layer thickness in a range of 10 nm to 60 nm around the inner bottom surface of the hollow structure.
7. The magnetoresistive element according to claim 6 , wherein a distance between the inner bottom surface of the hollow structure and an upper edge around the inner bottom surface is in a range of 0.5 nm to 59.5 nm.
8. The magnetoresistive element according to claim 6 , wherein one or more materials of the cap layer are selected from the following: Ru, Ta, Al, Ag, Au, Si, Ti, V, Zr, Nb, Mo, Hf, and W.
9. The magnetoresistive element according to claim 6 , wherein an insulating layer covers and protects a periphery of the magnetoresistive layer, a periphery of the cap layer, an upper edge surface around the inner bottom surface of the hollow structure, and a periphery of the upper layer which is a part of the magnetoresistive element.
10. The magnetoresistive element according to claim 9 , wherein a material of the insulating layer is thermally oxidized silicon.
11. The magnetoresistive element according to claim 6 , wherein the upper layer which is a part of the magnetoresistive element is an electrode layer.
12. The magnetoresistive element according to claim 6 ,
wherein the cap layer is in contact with a ferromagnetic layer of the magnetoresistive layer, and
wherein the upper layer which is a part of the magnetoresistive element is a soft magnetic layer.
13. The magnetoresistive element according to claim 12 , wherein a layer thickness of the cap layer between the soft magnetic layer and the ferromagnetic layer is less than 1 nm.