Abstract: A hard bias structure for biasing a free layer in a MR element within a magnetic read head is comprised of a soft magnetic underlayer such as NiFe and a hard bias layer comprised of Co78.6Cr5.2Pt16.2 or Co65Cr15Pt20 that are rigidly exchange coupled to ensure a well aligned longitudinal biasing direction with minimal dispersions. The hard bias structure is formed on a BCC seed layer such as CrTi to improve lattice matching. The hard bias structure may be laminated in which each of the underlayers and hard bias layers has a thickness that is adjusted to optimize the total HC, Mrt, and S values. The present invention encompasses CIP and CPP spin values, MTJ devices, and multi-layer sensors. A larger process window for fabricating the hard bias structure is realized and lower asymmetry output and NBLW (normalized base line wandering) reject rates during a read operation are achieved.

Abstract: A composite hard mask is disclosed that enables sub-100 nm sized MTJ cells to be formed for advanced devices such as spin torque MRAMs. The hard mask has a lower non-magnetic metallic layer such as Ru to magnetically isolate an overlying middle metallic spacer such as MnPt from an underlying free layer. The middle metallic spacer provides a height margin during subsequent processing to avoid shorting between a bit line and the MTJ cell in the final device. An upper conductive layer may be made of Ta and is thin enough to allow a MTJ pattern in a thin overlying photoresist layer to be transferred through the Ta during a fluorocarbon etch without consuming all of the photoresist. The MTJ pattern is transferred through the remaining hard mask layers and underlying MTJ stack of layers with a second etch step using a C, H, and O etch gas composition.

Abstract: An MTJ pattern layout for a memory device is disclosed that includes two CMP assist features outside active MTJ device blocks. A first plurality of dummy MTJ devices is located in two dummy bands formed around an active MTJ device block. The inner dummy band is separated from the outer dummy band by the MTJ ILD layer and has a MTJ device density essentially the same as the MTJ device block. The outer dummy band has a MTJ device density at least 10% greater than the inner dummy band. The inner dummy band serves to minimize CMP edge effect in the MTJ device block while the outer dummy band improves planarization. A second plurality of dummy MTJ devices is employed in contact pads outside the outer dummy band and is formed between a WL ILD layer and a BIT ILD layer thereby minimizing delamination of the MTJ ILD layer.

Abstract: We describe the structure and method of forming a STT-MTJ MRAM cell that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes an IrMn pinning layer, a SyAP pinned layer, a naturally oxidized, crystalline MgO tunneling barrier layer that is formed on an Ar-ion plasma smoothed surface of the pinned layer and, in one embodiment, a free layer that comprises an amorphous layer of Co60Fe20B20. of approximately 20 angstroms thickness formed between two crystalline layers of Fe of 3 and 6 angstroms thickness respectively. The free layer is characterized by a low Gilbert damping factor and by very strong polarizing action on conduction electrons. The resulting cell has a low critical current, a high dR/R and a plurality of such cells will exhibit a low variation of both resistance and pinned layer magnetization angular dispersion.

Abstract: A hard bias structure for biasing a free layer in a MR element within a magnetic read head is comprised of a soft magnetic underlayer such as NiFe and a hard bias layer comprised of Co78.6Cr5.2Pt16.2 or Co65Cr15Pt20 that are rigidly exchange coupled to ensure a well aligned longitudinal biasing direction with minimal dispersions. The hard bias structure is formed on a BCC seed layer such as CrTi to improve lattice matching. The hard bias structure may be laminated in which each of the underlayers and hard bias layers has a thickness that is adjusted to optimize the total Hc, Mrt, and S values. The present invention encompasses CIP and CPP spin values, MTJ devices, and multi-layer sensors. A larger process window for fabricating the hard bias structure is realized and lower asymmetry output and NBLW (normalized base line wandering) reject rates during a read operation are achieved.

Abstract: The conventional free layer in a CPP GMR or TMR read head has been replaced by a tri-layer laminate comprising Co rich CoFe, moderately Fe rich NiFe, and heavily Fe rich NiFe. The result is an improved device that has a higher MR ratio than prior art devices, while still maintaining free layer softness and acceptable magnetostriction. A process for manufacturing the device is described.

Abstract: In this invention, we replace low resistivity NiFe with high-resistivity FeNi for the FL2 portion of a composite free layer in a CIP GMR sensor in order to minimize current shunting effects while still retaining both magnetic softness and low magnetostriction. A process for manufacturing the device is also described.

Abstract: An MTJ pattern layout for a memory device is disclosed that includes two CMP assist features outside active MTJ device blocks. A first plurality of dummy MTJ devices is located in two dummy bands formed around an active MTJ device block. The inner dummy band is separated from the outer dummy band by the MTJ ILD layer and has a MTJ device density essentially the same as the MTJ device block. The outer dummy band has a MTJ device density at least 10% greater than the inner dummy band. The inner dummy band serves to minimize CMP edge effect in the MTJ device block while the outer dummy band improves planarization. A second plurality of dummy MTJ devices is employed in contact pads outside the outer dummy band and is formed between a WL ILD layer and a BIT ILD layer thereby minimizing delamination of the MTJ ILD layer.

Abstract: A MTJ that minimizes error count (EC) while achieving high MR value, low magnetostriction, and a RA of about 1100 ?-?m2 for 1 Mbit MRAM devices is disclosed. The MTJ has a composite AP1 pinned layer made of a lower amorphous Co60Fe20B20 layer and an upper crystalline Co75Fe25 layer to promote a smoother and more uniform AlOx tunnel barrier. A “stronger oxidation” state is realized in the AlOx layer by depositing a thicker than normal Al layer or extending the ROX cycle time for Al oxidation and thereby reduces tunneling hot spots. The NiFe free layer has a low Fe content of about 8 to 21 atomic % and the Hf content in the NiFeHf capping layer is from 10 to 25 atomic %. A Ta hard mask is formed on the capping layer. EC (best) is reduced from >100 ppm to <10 ppm by using the preferred MTJ configuration.

Abstract: A TMR read head with improved voltage breakdown is formed by laying down the AP1 layer as two or more layers. Each AP1 sub-layer is exposed to a low energy plasma for a short time before the next layer is deposited. This results in a smooth surface, onto which to deposit the tunneling barrier layer, with no disruption of the surface crystal structure of the completed AP1 layer.

Abstract: A TMR read head with improved voltage breakdown is formed by laying down the AP1 layer as two or more layers. Each AP1 sub-layer is exposed to a low energy plasma for a short time before the next layer is deposited. This results in a smooth surface, onto which to deposit the tunneling barrier layer, with no disruption of the surface crystal structure of the completed AP1 layer.

Abstract: The conventional free layer in a CPP GMR read head has been replaced by a tri-layer laminate comprising Co rich CoFe, moderately Fe rich NiFe, and heavily Fe rich NiFe. The result is an improved device that has a higher MR ratio than prior art devices, while still maintaining free layer softness and acceptable magnetostriction. A process for manufacturing the device is also described.

Abstract: A TMR read head with improved voltage breakdown is formed by laying down the AP1 layer as two or more layers. Each AP1 sub-layer is exposed to a low energy plasma for a short time before the next layer is deposited. This results in a smooth surface, onto which to deposit the tunneling barrier layer, with no disruption of the surface crystal structure of the completed AP1 layer.

Abstract: A high performance MTJ, and a process for manufacturing it, are described. A capping layer of NiFeHf is used to getter oxygen out of the free layer, thereby increasing the sharpness of the free layer-tunneling layer interface. The free layer comprises two NiFe layers whose magnetostriction constants are of opposite sign, thereby largely canceling one another.

Abstract: A method to fabricate an MTJ device and its connections to a CMOS integrated circuit is described. The device is built out of three layers. The bottom layer serves as a seed layer for the center layer, which is alpha tantalum, while the third, topmost, layer is selected for its smoothness, its compatibility with the inter-layer dielectric materials, and its ability to protect the underlying tantalum.

Abstract: The effectiveness of an IrMn pinning layer in a CPP GMR device at high switching fields has been improved by replacing the conventional single layer seed by a layer of tantalum and either ruthenium or copper. The tantalum serves to cancel out the crystallographic influence of underlying layers while the ruthenium or copper provide a suitable base on which to grow the IrMn layer.

Abstract: The effectiveness of an IrMn pinning layer in a CPP GMR device at high switching fields has been improved by replacing the conventional single layer seed by a layer of tantalum and either ruthenium or copper. The tantalum serves to cancel out the crystallographic influence of underlying layers while the ruthenium or copper provide a suitable base on which to grow the IrMn layer.

Abstract: In magnetic read heads based on bottom spin valves the preferred structure is for the longitudinal bias layer to be in direct contact with the free layer. Such a structure is very difficult to manufacture. The present invention overcomes this problem by introducing an extra layer between the bias electrodes and the free layer. This layer protects the free layer during processing but is thin enough to not interrupt exchange between the bias electrodes and the free layer. In one embodiment this is a layer of copper about 5 ? thick and parallel exchange is operative. In other embodiments ruthenium is used to provide antiparallel exchange between the bias electrode and the free layer. A process for manufacturing the structure is also described.

Abstract: A sensor array comprising a series connection of parallel GMR sensor stripes provides a sensitive mechanism for detecting the presence of magnetized particles bonded to biological molecules that are affixed to a substrate. The adverse effect of hysteresis on the maintenance of a stable bias point for the magnetic moment of the sensor free layer is eliminated by a combination of biasing the sensor along its longitudinal direction rather than the usual transverse direction and by using the overcoat stress and magnetostriction of magnetic layers to create a compensatory transverse magnetic anisotropy. By making the spaces between the stripes narrower than the dimension of the magnetized particle and by making the width of the stripes equal to the dimension of the particle, the sensitivity of the sensor array is enhanced.

Abstract: A hard bias layer that forms an abutting junction with a free layer in a GMR element and is comprised of FePtCu or FePtCuX where X is B, C, O, Si, or N is disclosed. The FePtCu layer has a composition of about 45 atomic % Fe, 45 atomic % Pt, and 10 atomic % Cu and does not require a seed layer to achieve an ordered structure. The FePtCu layer is annealed at a temperature of about 280° C. and has an Hc value more than double that of a conventional CoCrPt hard bias layer with a similar thickness. Since the FePtCu hard bias layer adjoins a free layer, it has a higher sensor edge pinning efficiency than a configuration with a CoCrPt layer on a seed layer. The novel hard bias layer is compatible with either a top or bottom spin valve structure in a GMR sensor.