Method for making a scissoring-type current-perpendicular-to-the-plane (CPP) magnetoresistive sensor
View Patent ↗A “scissoring-type” current-perpendicular-to-the-plane (CPP) magnetoresistive sensor with dual ferromagnetic sensing or free layers separated by a nonmagnetic spacer layer has improved stability as a result of etch-induced uniaxial magnetic anisotropy in each of the free layers. Each of the two ferromagnetic free layers has an etch-induced uniaxial magnetic anisotropy and an in-plane magnetic moment substantially parallel to its uniaxial anisotropy in the quiescent state, i.e., the absence of an applied magnetic field. The etch-induced uniaxial anisotropy of each of the free layers is achieved either by direct ion etching of each of the free layers, and/or by ion etching of the layer on which each of the free layers is deposited. A strong magnetic anisotropy is induced in the free layers by the etching, which favors generally orthogonal orientation of the two free layers in the quiescent state.
1. A method for making a scissoring-type current-perpendicular-to-the-plane (CPP) magnetoresistive sensor comprising:
providing a substrate;
depositing an underlayer on the substrate;
depositing a first ferromagnetic free layer on the underlayer;
depositing a nonmagnetic spacer layer on the first ferromagnetic layer;
depositing a second ferromagnetic free layer on the spacer layer;
after depositing at least one layer selected from a first group consisting of said underlayer and said first free layer, directing an ion beam to said at least one layer from said first group at an oblique angle relative to a normal to the surface of said at least one layer from said first group to directionally etch the surface of said at least one layer from said first group;
after etching the surface of said at least one layer from said first group, rotating the substrate relative to the ion beam about a normal to the surface of the substrate; and
after depositing at least one layer selected from a second group consisting of said spacer layer and said second free layer, directing an ion beam to said at least one layer from said second group at an oblique angle relative to a normal to the surface of said at least layer from said second group to directionally etch the surface of said at least one layer from said second group.
2. The method of claim 1 wherein directing an ion beam to said at least one layer from said first group at an oblique angle comprises directing at an angle between about 20 and 80 degrees, and directing an ion beam to said at least one layer from said second group at an oblique angle comprises directing at an angle between about 20 and 80 degrees.
3. The method of claim 1 wherein depositing the spacer layer comprises depositing a layer of electrically conducting metal or metal alloy.
4. The method of claim 1 wherein depositing the spacer layer comprises depositing a layer of electrically insulating material.