Back to results
US 8,659,292 B2Granted
MR sensor with flux guide enhanced hard bias structure
AssigneeHeadway Technologies, Inc.
InventorsYuchen Zhou, Tong Zhao, Kunliang Zhang
Life of this patent
Estimating the term…
Abstract
A CPP MR sensor interposes a tapered soft magnetic flux guide (FG) layer between a hard magnetic biasing layer (HB) and the free layer of the sensor stack. The flux guide channels the flux of the hard magnetic biasing layer to effectively bias the free layer, while eliminating instability problems associated with magnetostatic coupling between the hard bias layers and the upper and lower shields surrounding the sensor when the reader-shield-spacing (RSS) is small.
Claims43
A CPP MR sensor, comprising:
- a lower shield;
- an upper shield, formed a vertical distance RSS above said lower shield;
- a CPP MR stack formed between said lower shield and said upper shield, wherein said CPP MR stack is a vertical lamination of contiguous horizontal layers whose widths in a lateral direction are defined by patterned lateral sides, wherein said CPP MR stack includes a free layer and a barrier layer or a conductive layer formed beneath said free layer;
- wherein said free layer and said barrier layer or conductive layer have widths that are narrower than the widths of the remaining laminated layers;
- and
- a flux guide formed of soft magnetic material positioned adjacent to each side of said free layer;
- wherein
- said flux guide has a first lateral side that is positioned opposite to a side of said free layer and wherein said flux guide has a second lateral side that is opposite to said first lateral side;
- wherein
- said first lateral side is separated from said free layer by an insulating layer;
- and wherein
- a biasing layer formed of hard magnetic material is positioned adjacent to said second lateral side of said flux guide;
- wherein
- said second lateral side of said flux guide is larger in its depth dimension than said first lateral side and is positioned conformally opposite to said biasing layer, whereby a back side of said flux guide is tapered corresponding to said increase in its depth dimension from said first lateral side to said second lateral side and wherein
- Mst of said first lateral side of said flux guide is equal to or larger than the Mst of said free layer.
12 more elements
A method of forming a CPP MR sensor comprising;
- providing a substrate;
- forming on the substrate a CPP MR sensor stack, wherein said sensor stack is a laminate including a top layer that is a free layer and a layer immediately beneath said free layer that is a barrier layer or a conductive layer;
- patterning the CPP MR sensor stack by a method comprising:
- etching vertically downward completely through said free layer and through said barrier layer or conductive layer, thereby defining parallel vertical sides and a narrow width for said free layer and for said barrier or conductive layer and removing portions of said free layer and said barrier or conductive layer laterally disposed from said vertical sides thereby exposing horizontal surfaces of said barrier or conductive layer laterally disposed away from said vertical sides;
- then
- depositing a thin insulating layer conformally covering said etched vertical sides and said horizontal surfaces;
- and
- depositing a thin layer of soft magnetic material to refill the region removed by the etching process and to form flux guide layers;
- then
- etching lateral sides of said fabrication to form a final patterned sensor structure;
- then
- depositing underlayers for growth of hard magnetic biasing layers and depositing said hard magnetic biasing layers laterally outside said flux guide
- layers and abutting said flux guide layers;
- then
- etching back surfaces of the fabrication to form a back edge of said free layer and said barrier or conductive layer and, at the same time, a tapering slope of said flux guide layer;
- whereby
- said flux guide layer is further etched back for a distance not to exceed the magnetic exchange length of said flux guide material.
14 more elements
A method of forming a CPP MR sensor comprising;
- providing a substrate;
- forming on the substrate a CPP MR sensor stack, wherein said sensor stack is a laminate including a top layer that is a free layer and a layer immediately beneath said free layer that is a barrier layer or a conductive layer;
- patterning the CPP MR sensor stack by a method comprising:
- etching doubly sloped lateral sides of said sensor stack wherein a first slope defines lateral edges of said free layer and, partially, of said barrier or conductive layer and a second slope defines lateral sides of remaining layers of said laminate thereby removing lateral portions of said sensor stack;
- depositing a thin insulating layer conformally covering said etched doubly sloped sides;
- and
- depositing a thin layer of soft magnetic material to refill the region of said sensor stack removed by the etching process and to form flux guide layers, whereby inner lateral edges of said flux guide layers have a first slope that is conformal to and adjacent to said lateral edges of said free layer and a second slope that is conformal to and adjacent to said lateral sides of said remaining layers of said laminate;
- then
- etching outer lateral edges of said flux guide layer to form a final patterned sensor structure;
- then
- optionally depositing underlayers for growth of hard magnetic biasing layers and depositing said hard magnetic biasing layers laterally outside said outer lateral edges of said flux guide layers and abutting said flux guide layers;
- then
- etching back surfaces of the fabrication to form a back edge of said free layer and said barrier or conductive layer and, at the same time, a tapering slope of said flux guide layer;
- whereby
- said back surface of said flux guide layer is further etched back for a distance not to exceed the magnetic exchange length of said flux guide material.
12 more elements
Dependencies are inferred from the claim text.