Patterned MR device with controlled shape anisotropy
AssigneeHeadway Technologies, Inc.
InventorsYuchen Zhou, Yimin Guo
Life of this patent
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Abstract
A magnetic sensor with increased sensitivity, lower noise, and improved frequency response is described. The sensor's free layer is ribbon shaped and is closely flanked at each long edge by a ribbon of magnetically soft, high permeability material. The side stripes of soft magnetic material absorb external field flux and concentrate the flux to flow into the sensor's edges to promote larger MR sensor magnetization rotation. The free layer may be deposited simultaneously with the soft magnetic layer when they are aligned in the same plane. When the flux absorbing stripes are positioned above or below the MR sensor, then the free layer and flux absorbing stripes are deposited in separate steps.
Claims13
A method of fabricating a magnetic sensor, comprising:
- depositing a plurality of magneto-resistive (MR) device layers;
- patterning said MR device layers to form a MR stripe having a first bottom surface, a top layer that is a magnetically free layer having a first top surface, a first thickness, an aspect ratio of at least 5, a pair of opposing first edges that are equidistant from a center plane that bisects the MR stripe in a lengthwise direction;
- depositing and patterning a layer of soft magnetic material to form a pair of flux absorbing stripes each having a second edge facing the center plane, a second top surface, a second bottom surface, and a second thickness, a product of flux absorbing stripe magnetization times the second thickness is greater than a product of free layer magnetization times the first thickness;
- and
- positioning said flux absorbing stripes so that the second edge of a first flux absorbing stripe is offset from one of the opposing first edges of the free layer along a second direction that is orthogonal to the center plane, and the second edge of a second flux absorbing stripe is offset from another of the opposing first edges of the free layer along the second direction, and with adjacent pairs of opposing first edges and second edges aligned parallel to each other such that a portion of the free layer and MR stripe is aligned above each second top surface, or a portion of the free layer and MR stripe is aligned below each second bottom surface.
A method of fabricating a magnetic sensor;
- comprising:
- depositing a layer of magneto-resistive (MR) device material;
- patterning said device layer to form a MR stripe having a first bottom surface, a top layer that is a magnetically free layer having a first top surface, an aspect ratio of at least 5, a pair of opposing first edges that are equidistant from a center plane that bisects the MR stripe in a lengthwise direction, and a first thickness;
- depositing and patterning a layer of soft magnetic material to form a pair of flux absorbing stripes each having a second top surface, a second bottom surface, a second thickness, a second edge facing a side of the MR stripe that is parallel to the center plane, and at least a tapered third edge that connects the second edge to the second bottom surface, a product of flux absorbing stripe magnetization times the second thickness is greater than a product of free layer magnetization times the first thickness;
- and
- positioning said flux absorbing stripes so that the second edge of a first flux absorbing stripe is offset from one of the opposing first edges of the free layer along a second direction that is orthogonal to the center plane, and the second edge of a second flux absorbing stripe is offset from another of the opposing first edges of the free layer in a direction opposite to the second direction such that adjacent pairs of opposing first edges and second edges are aligned parallel to each other.
Dependencies are inferred from the claim text.