Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
1999-09-30
2001-03-20
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
C438S048000, C360S112000, C365S008000
Reexamination Certificate
active
06204071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to Striped Magnetoresistive (SMR) heads and Dual Stripe Magnetoresistive (DSMR) heads and more particularly to methods of manufacturing of exchange biasing configurations therefor, as well as devices manufactured by such methods.
2. Description of Related Art
As the continuous trend in magnetic recording requires increased area density, track widths of magnetic recording heads are being reduced. Commonly assigned U.S. patent application Ser. No. 09/182,775, filed Oct. 30, 1998 of Yimin Guo et al. for “Anti-Parallel Longitudinal Patterned Exchange Biased Dual Stripe Magnetoresistive (DSMR) Sensor Element and Method for Fabrication Thereof” describes a narrow track width DSMR head with dual sensors. The head, which increases signal amplitude is stabilized by anti-parallel biasing, i.e. with biasing which is parallel, but in the opposite directed or oriented. In such a biasing scheme, the magnetic centers of dual sensors self-align each other.
Accordingly, no track-offsetting is needed as disclosed in commonly assigned U.S. Pat. No. 5,783,460 of Han et al. for “Method of Making Self-Aligned Dual Stripe MagnetoResistive (DSMR) Head for High Density Recording” which shows a DSMR process using a lift off stencil to form a patterned dielectric layer edge. To achieve this quiescent biasing scheme, one can produce both sensors with Anti-Parallel EXchange-biasing (APEX) by means of exchange coupling between Anti-Ferro-Magnetic (AFM) and Ferro-Magnetic (FM) material.
U.S. Pat. No. 5,408,377 of Gurney et al. for “Magnetoresistive Sensor with Ferromagnetic Sensing Layer” shows a Ruthenium (Ru) AFM coupling film in a spin valve sensor.
U. S. Pat. No. 5,644,456 of Smith et al. for “Magnetically Capped Dual Magnetoresistive Reproduce Head” shows a cap layer in a DSMR that breaks exchange coupling between the magnetically permeable layer and MR elements.
U.S. Pat. No. 5,684,658 of Shi et al. for “High Track Density Dual Stripe Magnetoresistive (DMSR) Head” shows a DSMR having first and second anti-Ferro-Magnetic longitudinal biasing layers.
U.S. Pat. No. 5,731,936 of Lee et al. for “Magnetoresistive (MR) Sensor with Coefficient Enhancing that Promotes Thermal Stability” provides chromium based spacer layers for an MR layer of NiCr or NiFeCr compositions in place of Ta spacers to avoid a reported problem of degrading the magnetic moment of the MR stripe when high heat at the interface between the Ta spacer layer and the Permalloy (MR stripe) causing interdiffusion therebetween.
See Parkin, “Systematic Variation of the Strength and Oscillation Period of Indirect Magnetic Exchange Coupling through the 3d, 4d and 5d Transition Metals”, Physical Review Letters Vol. 67, No. 25, pp. 3598-3601 (Dec. 16, 1991)
U.S. Pat. No. 5,766,780 of Huang et al. for “Reversed Order NiMn Exchange Biasing for Dual Magnetoresistive Heads” teaches a DSMR with a Mo layer as the conductor/seed layer on an alumina base coat. A NiMn exchange bias layer is formed on the Mo layer. A NiFe MR sensor layer is formed on the surface of the NiMn exchange bias layer.
SUMMARY OF THE INVENTION
This invention teaches a Ruthenium/Ferro-Magnetic/AFM three layer structure to replace an AFM in a sensor in an MR or DSMR. In the case of a DSMR, when one magnetically aligns both AFM in the same direction, the biasing direction of the MR sensor under the ruthenium will be anti-parallel to the other one. A key element of the invention is the Ru spacer that shows increased coupling strength.
In accordance with this invention a method is provided for forming a longitudinally magnetically biased dual stripe magnetoresistive (DSMR) sensor element comprises forming a first patterned magnetoresistive (MR) layer. Contact the opposite ends of the patterned magnetoresistive (MR) layer with a first pair of stacks defining a track width of the first magnetoresistive (MR) layer, each of the stacks including a first Anti-Ferro-Magnetic (AFM) layer and a first lead layer. Then anneal the device in the presence of a longitudinal external magnetic field. Next, form a second patterned magnetoresistive (MR) layer above the previous structure. Contact the opposite ends of the second patterned magnetoresistive (MR) layer with a second pair of stacks defining a second track width of the second patterned magnetoresistive (MR) layer. Each of the second pair of stacks includes spacer layer composed of a metal, a Ferro-Magnetic (FM) layer, a second Anti-Ferro-Magnetic (AFM) layer and a second lead layer. Then anneal the device in the presence of a second longitudinal external magnetic field.
In accordance with another aspect of this invention, a longitudinally magnetically biased dual stripe magnetoresistive (DSMR) sensor element is provided including a first patterned magnetoresistive (MR) layer. There are a pair of opposite ends of the first patterned MR layer being in contact with a first pair of stacks defining a first track width of the patterned MR layer. Each of the stacks includes a first AFM layer and a first lead layer. The device has a first longitudinal magnetic field bias in the first AFM layer. There is a second patterned MR layer contacted at its opposite ends by a second pair of stacks defining a second track width of the second patterned MR layer. Each of the second pair of stacks includes a spacer layer composed of a metal, a Ferro-Magnetic (FM) layer, a second AFM layer and a second lead layer. The device has a second longitudinal magnetic field bias in the second AFM layer. Preferably, the spacer layer is composed of a metal selected from the group consisting of ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr). It is also preferred that the Ferro-Magnetic layers are composed of a metal selected from the group consisting of NiFe, Co, Fe, NiCo and CoFe. Moreover, it is preferred that the AFM layers are composed of a metal selected from the group consisting of IrMn, NiMn, PtMn, PdPtMn and FeMn.
REFERENCES:
patent: 5408377 (1995-04-01), Gurney et al.
patent: 5573809 (1996-11-01), Nix et al.
patent: 5644456 (1997-07-01), Smith et al.
patent: 5668688 (1997-09-01), Dykes et al.
patent: 5684658 (1997-11-01), Shi et al.
patent: 5731936 (1998-03-01), Lee et al.
patent: 5766780 (1998-06-01), Huang et al.
patent: 5783460 (1998-07-01), Ham et al.
patent: 5828531 (1998-10-01), Gill
patent: 5959810 (1999-09-01), Kakihara et al.
patent: 5991125 (1999-11-01), Iwasaki et al.
patent: 5998016 (1999-12-01), Sasaki et al.
Parkin, “Systematic Variation of the Strength and Oscillation Period of Indirect Magnetic Exchange Coupling Through the 3d. 4d and 5d Transition Metals,” Physical Review Letters vol. 67, No. 25, pp. 3598-3601 (Dec. 16, 1991).
Chang Jei-Wei
Chen Mao-Min
Horng Cheng T.
Ju Kochan
Ackerman Stephen B.
Headway Technologies Inc.
Jones II Graham S.
Saile George O.
Simkovic Viktor
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