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US 2009/0195941 A1Published application
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. This side pattern absorbs external field flux, concentrating it to flow into the sensor's edges to promote larger MR sensor magnetization rotation.
Claims21
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 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, 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 edge, a second top surface, and a second thickness;
- positioning said flux absorbing stripes so that said MR stripe is located between them, with adjacent pairs of said first and second edges running parallel to each other, said adjacent edge pairs being separated from one another by a distance that is at most 0.1 microns, as measured from a first edge in a direction parallel to said free layer top surface;
- selecting values for said first and second thicknesses so that, at all times, a product of said soft magnetic stripe's magnetization times said second thickness is greater than a product of said MR stripe's magnetization times said first thickness;
- and
- thereby ensuring that said free layer undergoes uniform rotation when its direction of magnetization is reversed, that said free layer primarily comprises a single magnetic domain, and that field concentration and demagnetization cancellation by neighboring soft magnetic patterns are not limited by said free layer's properties whereby said free layer can be independently optimized to increase sensitivity for said MR sensor.
4 more elements
A magnetic sensor, comprising:
- A magneto-resistive (MR) device in the form of a MR stripe having a 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, and a first thickness;
- a pair of flux absorbing stripes made of soft magnetic material each stripe having a second edge, a second top surface, and a second thickness;
- said flux absorbing stripes positioned so that said MR stripe is located between them, with adjacent pairs of said first and second edges running parallel to each other, said adjacent edge pairs being separated from one another by a distance that is at most 0.1 microns, as measured from a first edge in a direction parallel to said free layer top surface;
- said first and second thicknesses having values such that, at all times, a product of said soft magnetic stripe's magnetization times said second thickness is greater than a product of said MR stripe's magnetization times said first thickness;
- and
- whereby said free layer will undergo uniform rotation if its direction of magnetization is reversed, said free layer primarily comprises a single magnetic domain, and field concentration and demagnetization cancellation by neighboring soft magnetic patterns are not limited by said free layer's properties.
3 more elements
Dependencies are inferred from the claim text.