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 GMR sensor stripe 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 stripe free layer is eliminated by a combination of biasing the sensor stripe 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 connecting the stripes in an array and 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: The invention discloses a method and apparatus for determining the rotational status of a gear wheel whether or not it is actually turning. A key feature is the magnetic angle sensor that is used. Said sensor comprises a bridge structure of four MR devices in a square array. The direction of the pinned reference layer is the same for all four devices and lies along one of the diagonals of said square array. A single wafer process is used to manufacture the invented device.

Abstract: A STT-MRAM integration scheme is disclosed wherein the connection between a MTJ and CMOS metal is simplified by forming an intermediate via contact (VAC) on a CMOS landing pad, a metal (VAM) pad that contacts and covers the VAC, and a MTJ on the VAM. A dual damascene process is performed to connect BIT line metal to CMOS landing pads through VAC/VAM/MTJ stacks in a device region, and to connect BIT line connection pads to CMOS connection pads through BIT connection vias outside the device region. The VAM pad is a single layer or composite made of Ta, TaN, or other conductors which serves as a diffusion barrier, has a highly smooth surface for MTJ formation, and provides excellent selectivity with refill dielectric materials during a chemical mechanical polish process. Each VAC is from 500 to 3000 Angstroms thick to minimize additional circuit resistance and minimize etch burden.

Abstract: A MTJ for a spintronic device is disclosed and includes a thin composite seed layer made of at least Ta and a metal layer having fcc(111) or hcp(001) texture as in Ta/Ti/Cu to enhance perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (CoFe/Ni)x, (Co/NiFe)x, (Co/NiCo)x, (CoFe/NiFe)x, or (CoFe/NiCo)x composition where x is from 5 to 30. In one embodiment, a CPP-TMR spin valve has one or both of a laminated free layer and laminated reference layer with the aforementioned compositions. The MTJ includes an interfacial layer made of CoFeB, CoFeB/CoFe, or CoFe/CoFeB between each laminated structure and the tunnel barrier. The laminated layers are deposited by a low power and high Ar pressure process to avoid damaging interfaces between adjoining layers. Annealing occurs at 220° C. to 400° C. A laminated layer with high PMA may also be included in one or more layers of a spin transfer oscillator.

Abstract: An MRAM is disclosed that has a MTJ comprised of a ferromagnetic layer with a magnetization direction along a first axis, a super-paramagnetic (SP) free layer, and an insulating layer formed therebetween. The SP free layer has a remnant magnetization that is substantially zero in the absence of an external field, and in which magnetization is roughly proportional to an external field until reaching a saturation value. In one embodiment, a separate storage layer is formed above, below, or adjacent to the MTJ and has uniaxial anisotropy with a magnetization direction along its easy axis which parallels the first axis. In a second embodiment, the storage layer is formed on a non-magnetic conducting spacer layer within the MTJ and is patterned simultaneously with the MTJ. The SP free layer may be multiple layers or laminated layers of CoFeB. The storage layer may have a SyAP configuration and a laminated structure.

Abstract: A process for manufacturing a high performance MTJ it is described: A first cap layer of NiFeHf is deposited on the free layer, followed by a second cap layer of Ru on Ta. The device is then heated so that oxygen trapped in the free layer diffuses into the NiFeHf layer, thereby sharpening the interface between the tunnel barrier layer and the free layer.

Abstract: A cladding structure for a conductive line used to switch a free layer in a MTJ is disclosed and includes two cladding sidewalls on two sides of the conductive line, a top cladding portion on a side of the conductive line facing away from the MTJ, and a highly conductive, non-magnetic spacing control layer formed between the MTJ and conductive line. The spacing control layer has a thickness of 0.02 to 0.12 microns to maintain the distance separating free layer and conductive line between 0.03 and 0.15 microns. The spacing control layer is aligned parallel to the conductive line and contacts a plurality of MTJ elements in a row of MRAM cells. Half-select error problems are avoided while maintaining high write efficiency. A spacing control layer may be formed between a word line and a bottom electrode in a top pinned layer or dual pinned layer configuration.

Abstract: A STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by a NOX process, a CoFeB/FeSiO/CoFeB composite free layer with a middle nanocurrent channel layer to minimize Jc0, and a Ru capping layer to enhance the spin scattering effect and increase dR/R. Good write margin is achieved by modifying the NOX process to afford a RA less than 10 ohm-?m2 and good read margin is realized with a dR/R of >100% by annealing at 330° C. or higher to form crystalline CoFeB free layers. The NCC thickness is maintained in the 6 to 10 Angstrom range to reduce Rp and avoid Fe(Si) granules from not having sufficient diameter to bridge the distance between upper and lower CoFeB layers. A FeSiO layer may be inserted below the Ru layer in the capping layer to prevent the Ru from causing a high damping constant in the upper CoFeB free layer.

Abstract: A MRAM structure is disclosed that includes a metal contact bridge (MCB) which provides an electrical connection between a MTJ top electrode and an overlying bit line. The MCB has a width greater than a MTJ top electrode and serves as an etch stop during bit line etching to prevent sub-trenches from forming adjacent to the top electrode and causing shorts. MCBs also prevent insufficient etching that causes open circuits. A MCB is preferably a metal, metal compound, or alloy such as Ta with low resistivity and high conductivity. The MCB layer is patterned prior to using a dual damascene process to form a bit line contacting each MCB and a bit line pad connection to a word line pad. MCB thickness is thin enough to allow a strong bit line magnetic field for switching a free layer and large enough to function as an efficient oxide etch stop.

Abstract: A scheme for forming a thin metal interconnect is disclosed that minimizes etch residues and provides a wet clean treatment for via openings. A single layer interlayer dielectric (ILD), BARC, and photoresist layer are successively formed on a substrate having a copper layer that is coplanar with a dielectric layer. In one embodiment, the ILD is silicon nitride with 100 to 600 Angstrom thickness. After a via opening is formed in a photoresist layer above the copper layer, a first RIE process including BARC main etch and BARC over etch steps is performed. Then a second RIE step transfers the opening through the ILD to uncover the copper layer. Photoresist and BARC are stripped with oxygen plasma and a low DC bias. Wet cleaning may involve a first ST250 treatment, ultrasonic water treatment, and then a third ST250 treatment. A bottom electrode layer may be deposited in the via opening.

Abstract: A method for forming a MTJ in a STT-MRAM is disclosed in which the easy-axis CD is determined independently of the hard-axis CD. One approach involves two photolithography steps and two etch steps to form a post in a hard mask which is transferred through a MTJ stack of layers by a third etch process. Optionally, the third etch may stop on the tunnel barrier or in the free layer. A second embodiment involves forming a first parallel line pattern on a hard mask layer and transferring the line pattern through the MTJ stack with a first etch step. A planar insulation layer is formed adjacent to the sidewalls in the line pattern and then a second parallel line pattern is formed which is transferred by a second etch through the MTJ stack to form a post pattern. Etch end point may be controlled independently for hard-axis and easy-axis dimensions.

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 process is described for making contact to the buried capping layers of GMR and MTJ devices without the need to form and fill via holes. CMP is applied to the structure in three steps: (1) conventional CMP (2) a Highly Selective Slurry (HSS) is substituted for the conventional slurry to just expose the capping layer, and (3) the HSS is diluted and used to clean the surface as well as to cause a slight protrusion of the capping layers above the surrounding dielectric surface, making it easier the contact them without damaging the devices below.

Abstract: By subdividing the free layer of a GMR/TMR device into multiple sub-elements that share common top and bottom electrodes, a magnetic detector is produced that is domain stable in the presence of large stray fields, thereby eliminating the need for longitudinal bias magnets. Said detector may be used to measure electric currents without being affected by local temperature fluctuations and/or stray fields.

Abstract: A 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: An MRAM is disclosed that has a MTJ comprised of a ferromagnetic layer with a magnetization direction along a first axis, a super-paramagnetic (SP) free layer, and an insulating layer formed therebetween. The SP free layer has a remnant magnetization that is substantially zero in the absence of an external field, and in which magnetization is roughly proportional to an external field until reaching a saturation value. In one embodiment, a separate storage layer is formed above, below, or adjacent to the MTJ and has uniaxial anisotropy with a magnetization direction along its easy axis which parallels the first axis. In a second embodiment, the storage layer is formed on a non-magnetic conducting spacer layer within the MTJ and is patterned simultaneously with the MTJ. The SP free layer may be multiple layers or laminated layers of CoFeB. The storage layer may have a SyAP configuration and a laminated structure.

Abstract: We describe a CPP MTJ MRAM element that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes a tunneling barrier layer of MgO and a non-magnetic CPP layer of Cu or Cr and utilizes a novel synthetic free layer having three ferromagnetic layers mutually exchange coupled in pairwise configurations. The free layer comprises an inner ferromagnetic and two outer ferromagnetic layers, with the inner layer being ferromagnetically exchange coupled to one outer layer and anti-ferromagnetically exchange coupled to the other outer layer. The ferromagnetic coupling is very strong across an ultra-thin layer of Ta, Hf or Zr of thickness preferably less than 0.4 nm.

Abstract: An 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 is 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 has a low Gilbert damping factor and a 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: In a method of vacuum packaging a MEMS device, at least one MEMS device is attached on a substrate. A solder preform is printed on the substrate at the perimeter surrounding the substrate. A lid is attached to the solder preform wherein the lid provides a cavity enclosing the at least one MEMS device. A first reflowing step reflows the solder at a first temperature, partially sealing the lid/substrate interface and at the same time does the outgassing and baking procedure for the packaging. Flux is applied onto an outer ring of the solder preform and a second step reflows the solder at a second temperature, completely sealing the lid/substrate interface and providing a vacuum cavity enclosing the at least one MEMS device.