Abstract: Tunneling magnetoresistive (TMR) elements and associated methods of fabrication are disclosed. In one embodiment, the TMR element includes a ferromagnetic pinned layer structure, a tunnel barrier layer, and a free layer having a dual-layer structure. In one embodiment, the free layer includes a first amorphous free layer and a second amorphous free layer. In another embodiment, the free layer includes a first polycrystalline free layer and a second amorphous free layer. The compositions of the first free layer and the second free layer of the dual layer structure differ to provide improved TMR performance and controlled magnetostriction. In one example, the first free layer may have a composition optimized for TMR while the second free layer may have a composition optimized for magnetostriction.

Abstract: Tunneling magnetoresistive (TMR) electrical lapping guides (ELG) are disclosed for use in wafer fabrication of magnetic sensing devices, such as magnetic recording heads using TMR read elements. A TMR ELG includes a TMR stack comprising a first conductive layer, a barrier layer, and a second conductive layer of TMR material. The TMR ELG also includes a first lead and a second lead that connect to conductive pads used for applying a sense current to the TMR ELG in a current in plane (CIP) fashion. The first lead contacts one side of the TMR stack so that the first lead contacts both the first conductive layer and the second conductive layer of the TMR stack. The second lead contacts the other side of the TMR stack so that the second lead contacts both the first conductive layer and the second conductive layer of the TMR stack.

Abstract: A tunneling magnetoresistive (TMR) sensor includes a first ferromagnetic (FM) layer (e.g. a sense or reference layer), a barrier layer formed over the first FM layer, and a second FM layer (e.g. a sense or reference layer) formed over the barrier layer. The barrier layer is made of magnesium-oxide (Mg—O). The sense and reference layers of the TMR sensor exhibit controlled magnetic properties, the barrier layer provides a low junction resistance-area product, and the TMR sensor exhibits a high TMR coefficient. The junction resistance is sufficiently low so as to prevent electrostatic discharge (ESD) damage to submicron-sized TMR sensors used for magnetic recording at ultrahigh densities.

Abstract: The GMR read head includes a GMR read sensor and a longitudinal bias (LB) stack in a read region, and the GMR read sensor, the LB stack and a first conductor layer in two overlay regions. In its fabrication process, the GMR read sensor, the LB stack and the first conductor layer are sequentially deposited on a bottom gap layer. A monolayer photoresist is deposited, exposed and developed in order to open a read trench region for the definition of a read width, and RIE is then applied to remove the first conductor layer in the read trench region. After liftoff of the monolayer photoresist, bilayer photoresists are deposited, exposed and developed in order to mask the read and overlay regions, and a second conductor layer is deposited in two unmasked side regions. As a result, side reading is eliminated and a read width is sharply defined by RIE.

Abstract: The GMR read head includes a GMR read sensor and a longitudinal bias (LB) stack in a read region, and the GMR read sensor, the LB stack and a first conductor layer in two overlay regions. In its fabrication process, the GMR read sensor, the LB stack and the first conductor layer are sequentially deposited on a bottom gap layer. A monolayer photoresist is deposited, exposed and developed in order to open a read trench region for the definition of a read width, and RIE is then applied to remove the first conductor layer in the read trench region. After liftoff of the monolayer photoresist, bilayer photoresists are deposited, exposed and developed in order to mask the read and overlay regions, and a second conductor layer is deposited in two unmasked side regions. As a result, side reading is eliminated and a read width is sharply defined by RIE.

Abstract: A giant magnetoresistance (GMR) magnetic head that includes a GMR read sensor with a stitched longitudinal bias (LB) stack. The GMR read sensor includes seed, pinning, pinned, spacer, sense and cap layers in a read region, and its seed and pinning layers are extended into two side regions. The LB stack is fabricated on the pinning layer in the two side regions and includes separation, seed and LB layers. The separation layer, preferably made of an amorphous film, separates the pinning layer from the seed and LB layers and thereby prevents unwanted crystalline effects of the pinning layer. Monolayer photoresist patterning and chemical mechanical polishing may be incorporated into the fabrication process of the GMR head to attain uniform thicknesses of the separation, seed and LB layers, and to align the midplane of the LB layer at the same horizontal level as the midplane of the sense layer.

Abstract: A dual spin valve (SV) sensor is provided with a longitudinal bias stack sandwiched between a first SV stack and a second SV stack. The longitudinal bias stack comprises an antiferromagnetic (AFM) layer sandwiched between first and second ferromagnetic layers. The first and second SV stacks comprise antiparallel (AP)-pinned layers pinned by AFM layers made of an AFM material having a higher blocking temperature than the AFM material of the bias stack allowing the AP-pinned layers to be pinned in a transverse direction and the bias stack to be pinned in a longitudinal direction. The demagnetizing fields of the two AP-pinned layers cancel each other and the bias stack provides flux closures for the sense layers of the first and second SV stacks.

Abstract: The pinned layer structure in a self-pinned spin valve is deposited using a DC aligning field. The deposition of each of the Reference and Keeper layer in the pinned layer occurs within two different polarity DC aligning fields. Thus, a first portion of the Reference layer is deposited with a DC alignment field of a first polarity, i.e., either positive or negative, and a second portion of the Reference layer is deposited in a DC alignment field of opposite polarity. The Keeper layer is similarly deposited, with a first portion of the Keeper layer deposited in a first polarity DC alignment field and the second portion deposited in the opposite polarity DC alignment field. By splitting the deposition of the Reference and Keeper layers into portions using DC aligning fields the pinned layer structure is highly repeatable while providing a good thickness uniformity of the structure.

Abstract: A current-perpendicular-to-plane (CPP) spin valve (SV) sensor and fabrication method with a contiguous junction type geometry that increases sensor resistance by up to two orders of magnitude over conventional CPP GMR geometry for a particular track read-width. The superior CPP GMR coefficient (?r/R) is implemented at an increased sensor resistance by using two small self-aligned SV stacks disposed with the sense current flowing perpendicular thereto when also flowing parallel to the free layer deposition plane. With the CPP geometry of this invention, thicker conductive spacer layers may be used without unacceptable sense current shunting, so the two self-aligned SV stacks may be completed following the free-layer track-mill step. The two SV stacks may be connected in parallel or back-to-back in series to provide different sense voltages.

Abstract: An anti-parallel pinned sensor is provided with a spacer that increases the anti-parallel coupling strength of the sensor. The anti-parallel pinned sensor is a GMR or TMR sensor having a pure ruthenium or ruthenium alloy spacer. The thickness of the spacer is less than 0.8 nm, preferably between 0.1 and 0.6 nm. The spacer is also annealed in a magnetic field that is 1.5 Tesla or higher, and preferably greater than 5 Tesla. This design yields unexpected results by more than tripling the pinning field over that of typical AP-pinned GMR and TMR sensors that utilize ruthenium spacers which are 0.8 nm thick and annealed in a relatively low magnetic field of approximately 1.3 Tesla.

Abstract: A read head for use with an interconnect transmission line having a characteristic impedance of Z0 includes a tunnel valve device and a shunt resistor RS that is connected in parallel across the tunnel valve device. The tunnel valve device has a device resistance RT corresponding to a predetermined resistance-area (RA) product. The value of the shunt resistance is based on the parallel combination of RT and RS substantially equaling the characteristic impedance Z0 of the interconnect transmission line. The predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-?m2. Alternatively, the predetermined resistance-area (RA) product is about equal to a “corner” value of RAc for the tunnel valve device.

Abstract: An antiferromagnetic stabilization scheme is employed in a magnetic head for magnetically stabilizing a free layer of a spin valve. This is accomplished by utilizing an antiferromagnetic oxide film below a spin valve sensor in a read region and first and second lead layers in end regions and a ferromagnetic film in each of the lead layers that exchange couples to the antiferromagnetic oxide film in the end regions. The ferromagnetic films are pinned with their magnetic moments oriented parallel to an air bearing surface (ABS) of the magnetic head. The ferromagnetic film magnetostatically couples to the free layer which causes the free layer to be in a single magnetic domain state. Accordingly, when the free layer is subjected to magnetic incursions from a rotating disk in a disk drive, the free layer maintains a stable magnetic condition so that resistance changes of the free layer are not altered by differing magnetic conditions of the free layer.

Abstract: The invention is a method for reactive sputter deposition of an ultra-thin film of an oxide of a first metal onto a film of a second metal. The method can be part of the fabrication of a magnetic tunnel junction (MTJ) with the metal oxide film becoming the tunnel barrier of the MTJ. The metal oxide film is reactively sputter deposited in the presence of reactive oxygen gas (O2) from a target consisting essentially of the first metal, with the sputtering occurring in the “high-voltage” state to assure that deposition occurs with the target in its metallic mode, i.e., no or minimal oxidation. When the metal oxide film is for a MTJ tunnel barrier, then the target is formed of a metal of Al, Ti, Ta, Y, Ga or In; an alloy of two or more of these metals; or an alloy of one or more of these metals with Mg; and the film of the second metal is an iron-containing film, typically a film of Fe or a CoFe alloy.

Abstract: As part of the fabrication of a magnetic tunnel junction (MTJ), a magnesium oxide (MgO) tunnel barrier is reactively sputter deposited from a Mg target in the presence of reactive oxygen gas (O2) in the “high-voltage” state to assure that deposition occurs with the Mg target in its metallic mode, i.e., no or minimal oxidation. Because the metallic mode of the Mg target has a finite lifetime, a set of O2 flow rates and associated sputter deposition times are established, with each flow rate and deposition time assuring that deposition occurs with the Mg target in the metallic mode and resulting in a known tunnel barrier thickness. The commencement of undesirable Mg target oxidation is associated with a decrease in target voltage, so the sputtering can also be terminated by monitoring the target voltage and terminating application of power to the target when the voltage reaches a predetermined value.

Abstract: A magnetoresistive sensor having an in stack bias structure. The sensor includes a bias spacer that allows biasing of free layer magnetic moment in a direction orthogonal to the magnetic moment of the biasing layer.

Abstract: The GMR read head includes a GMR read sensor and a longitudinal bias (LB) stack in a read region, and the GMR read sensor, the LB stack and a first conductor layer in two overlay regions. In its fabrication process, the GMR read sensor, the LB stack and the first conductor layer are sequentially deposited on a bottom gap layer. A monolayer photoresist is deposited, exposed and developed in order to open a read trench region for the definition of a read width, and RIE is then applied to remove the first conductor layer in the read trench region. After liftoff of the monolayer photoresist, bilayer photoresists are deposited, exposed and developed in order to mask the read and overlay regions, and a second conductor layer is deposited in two unmasked side regions. As a result, side reading is eliminated and a read width is sharply defined by RIE.

Abstract: The pinned layer structure in a self-pinned spin valve is deposited using a DC aligning field. The deposition of each of the Reference and Keeper layer in the pinned layer occurs within two different polarity DC aligning fields. Thus, a first portion of the Reference layer is deposited with a DC alignment field of a first polarity, i.e., either positive or negative, and a second portion of the Reference layer is deposited in a DC alignment field of opposite polarity. The Keeper layer is similarly deposited, with a first portion of the Keeper layer deposited in a first polarity DC alignment field and the second portion deposited in the opposite polarity DC alignment field. By splitting the deposition of the Reference and Keeper layers into portions using DC aligning fields the pinned layer structure is highly repeatable while providing a good thickness uniformity of the structure.

Abstract: A giant magnetoresistance (GMR) magnetic head that includes a GMR read sensor with a stitched longitudinal bias (LB) stack. The GMR read sensor includes seed, pinning, pinned, spacer, sense and cap layers in a read region, and its seed and pinning layers are extended into two side regions. The LB stack is fabricated on the pinning layer in the two side regions and includes separation, seed and LB layers. The separation layer, preferably made of an amorphous film, separates the pinning layer from the seed and LB layers and thereby prevents unwanted crystalline effects of the pinning layer. Monolayer photoresist patterning and chemical mechanical polishing may be incorporated into the fabrication process of the GMR head to attain uniform thicknesses of the separation, seed and LB layers, and to align the midplane of the LB layer at the same horizontal level as the midplane of the sense layer.

Abstract: In fabricating the magnetic head, a first magnetic shield layer (S1) is fabricated upon a substrate base, followed by a thin first insulation layer (G1). A photoresist mask is fabricated upon the G1 layer and electrical lead recesses are milled through the G1 layer and into the S1 layer. An insulation layer is deposited into the electrical lead recesses, followed by the fabrication of electrical leads within the recesses. The photoresist is removed and a magnetoresistive (MR) sensor is subsequently fabricated on top of the G1 layer, such that portions of the MR sensor are fabricated on top of portions of the electrical leads. Hard bias elements are then fabricated at outboard edges of the MR sensor. A thin second insulation layer (G2) is fabricated on top of the MR sensor and hard bias elements, and a second magnetic shield layer (S2) is fabricated on top of the G2 layer.

Abstract: An antiferromagnetic stabilization scheme is employed in a magnetic head for magnetically stabilizing a free layer of a spin valve. This is accomplished by utilizing an antiferromagnetic oxide film below a spin valve sensor in a read region and first and second lead layers in end regions and a ferromagnetic film in each of the lead layers that exchange couples to the antiferromagnetic oxide film in the end regions. The ferromagnetic films are pinned with their magnetic moments oriented parallel to an air bearing surface (ABS) of the magnetic head. The ferromagnetic films magnetostatically couple to the free layer which causes the free layer to be in a single magnetic domain state. Accordingly, when the free layer is subjected to magnetic incursions from a rotating disk in a disk drive, the free layer maintains a stable magnetic condition so that resistance changes of the free layer are not altered by differing magnetic conditions of the free layer.