Patent application number | Description | Published |
20080253178 | MRAM with enhanced programming margin - An MRAM that is not subject to accidental writing of half-selected memory elements is described, together with a method for its manufacture. The key features of this MRAM are a C-shaped memory element used in conjunction with a segmented bit line architecture. | 10-16-2008 |
20090096043 | MRAM with means of controlling magnetic anisotropy - We describe the manufacturing process for and structure of a CPP MTJ MRAM unit cell that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The strength of the switching field, H | 04-16-2009 |
20090268512 | MRAM with cross-tie magnetization configuration - The incidence of half-select errors during MRAM programming has been significantly reduced by giving the free layer a shape that approximates an X so that, when the free layer switches, the magnetization in the arms of the X guides the magnetization in the central section (the X's intersection area) causing it to rotate towards the hard axis in two opposing directions. This raises the free layer's switching energy barrier, thereby reducing half-select errors. | 10-29-2009 |
20100128518 | Novel spin momentum transfer MRAM design - We describe the structure and method of formation of a STT MTJ or GMR MRAM cell element that utilizes transfer of spin torque as a mechanism for changing the magnetization direction of a free layer. The critical current is reduced by constructing the free layer as a lamination comprising two ferromagnetic layers sandwiching a coupling valve layer. When the Curie temperature of the coupling valve layer is above the temperature of the cell, the two ferromagnetic layers are exchange coupled in parallel directions of their magnetization. When the coupling valve layer is above its Curie temperature, it no longer exchange couples the layers and they are magnetostatically coupled. In the exchange coupled configuration, the free layer serves to store data and the cell can be read. In its magnetostatically coupled configuration, the cell can be more easily written upon because one of the layers can assist the spin torque transfer by its magnetostatic coupling. If the free layer is formed as a multi-layered lamination of N periodically repeating combinations of a ferromagnetic layer and a coupling valve layer, the critical current can be reduced by a factor of N. | 05-27-2010 |
20100176429 | MRAM with storage layer and super-paramagnetic sensing layer - 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. | 07-15-2010 |
20100178715 | MRAM with storage layer and super-paramagnetic sensing layer - 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. | 07-15-2010 |
20100232215 | MRAM with coupling valve switching - The free layer in a magneto-resistive memory element is stabilized through being pinned by an antiferromagnetic layer. A control valve layer provides exchange coupling between this antiferromagnetic layer and the free layer. When writing data into the free layer, the control valve layer is heated above its curie point thereby temporarily uncoupling the free layer from said antiferromagnetic layer. Once the control valve cools, the free layer magnetization is once again pinned by the antiferromagnetic layer. | 09-16-2010 |
20100315869 | Spin torque transfer MRAM design with low switching current - The invention discloses a method to store digital information through use of spin torque transfer in a device that has a very low critical current. This is achieved by adding a spin filtering layer whose direction of magnetization is fixed to be parallel to the device's pinned layer. | 12-16-2010 |
20110014500 | Structure and method to fabricate high performance MTJ devices for spin-transfer torque (STT)-RAM application - A STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by natural oxidation and containing an oxygen surfactant layer to form a more uniform MgO layer and lower breakdown distribution percent. A CoFeB/NCC/CoFeB composite free layer with a middle nanocurrent channel layer minimizes Jc | 01-20-2011 |
20110062536 | Design and fabrication methods of partial cladded write line to enhance write margin for magnetic random access memory - 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. | 03-17-2011 |
20110284977 | Array of magnetic tunneling junction film structures with process determined in-plane magnetic anisotropy - An MRAM array of MTJ memory cells is provided wherein each such cell is a layered MTJ structure located at an intersection of a word and bit line and has a small circular horizontal cross-section of 1.0 microns or less in diameter and wherein the ferromagnetic free layer of each such cell has a magnetic anisotropy produced by a magnetic coupling with a thin antiferromagnetic layer that is formed on the free layer. The array of MTJ memory cells so provided is far less sensitive to shape irregularities and edge defects of individual cells than arrays of the prior art. | 11-24-2011 |
20120058574 | MRAM with storage layer and super-paramagnetic sensing layer - 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. | 03-08-2012 |
20120063214 | Pulse field assisted spin momentum transfer MRAM design - An MRAM array structure and a method of its operation that is not subject to accidental writing on half-selected elements. Each element of the MRAM is an MTJ (magnetic tunneling junction) cell operating in accord with an STT (spin torque transfer) scheme for changing its free layer magnetization state and each cell is patterned to have a C-shape in the horizontal plane. The cell thereby operates by C-mode switching to provide stability against accidental writing by half-selection. During operation, switching of a cell's magnetization is accomplished with the assist of the pulsed magnetic fields of additional word lines that are formed either orthogonal to or parallel to the existing bit lines and that can carry currents in either direction as required to provide the assist. | 03-15-2012 |
20120127611 | Modified shield design to eliminate the far-field WATE problem - A shield design for a magnetic write head is described that eliminates the far-field WATE problem while still maintaining side shielding ability. This is achieved by moving all but the central sections of the three shields (LS, SS, and WS) and, optionally, the top yoke a short distance further away from the recording medium than the ABS. | 05-24-2012 |
20120257305 | PMR WRITE HEAD WITH ASSISTED MAGNETIC LAYER - A PMR writer is disclosed wherein a magnetic assist layer (MAL) made of an anisotropic (−Ku) or (+Ku) magnetic material is formed along a main pole trailing side to optimize the vertical magnetic field and field gradient at the air bearing surface. A Ru seed layer is formed between the main pole and (−Ku) MAL to induce a hard axis direction toward the main pole. A (−Ku) MAL is preferably comprised of hcp-CoIr while CoPt and FePt are examples of a (+Ku) MAL. The MAL has a down-track thickness from 5 to 20 nm, a width equal to the track width in a cross-track direction, and extends 100 to 500 nm in a direction toward a back end of the main pole. As a result, flux leakage from the main pole to trailing shield is reduced and aerial density is increased. A method for fabricating the PMR writer is provided. | 10-11-2012 |
20120295132 | Writer design with enhanced writability - A perpendicular magnetic recording (PMR) head is fabricated with a main pole and a trailing edge shield having surfaces and interior portions that may include synthetic antiferromagnetic multi-layered superlattices (SAFS) formed on and/or within them respectively. The SAFS, which are multilayers formed as periodic multiples of antiferromagnetically coupled tri-layers, provide a mechanism for enhancing the component of the writing field that is vertical to the magnetic medium by exchange coupling to the magnetization of the pole and shield and constraining the directions of their magnetizations to lie within the film plane of the SAFS. | 11-22-2012 |
20120295133 | Writer with an AFM write gap - A perpendicular magnetic recording (PMR) head is fabricated with main pole and a trailing edge shield antiferromagnetically coupled across a write gap by either having the write gap layer formed as a synthetic antiferromagnetic tri-layer (SAF) or formed as a monolithic layer of antiferromagnetic material. The coupling improves the write performance of the writer by enhancing the perpendicular component of the write field and its gradient. Methods of fabricating the writer are provided. | 11-22-2012 |
20130027809 | HIGH DATA RATE MAGNETIC WRITER DESIGN - A high speed magnetic data writer containing a stitched pole tip that works in conjunction with the main pole is disclosed, together with a process for their manufacture. The material composition of each of these two sub-structures is slightly different; one sub-structure is optimized for high magnetic damping while the other sub-structure is optimized for high saturation magnetization. | 01-31-2013 |
20140037861 | Method of Forming a Writer with an AFM Write Gap - A perpendicular magnetic recording (PMR) head is fabricated with main pole and a trailing edge shield antiferromagnetically coupled across a write gap by either having the write gap layer formed as a synthetic antiferromagnetic tri-layer (SAF) or formed as a monolithic layer of antiferromagnetic material. The coupling improves the write performance of the writer by enhancing the perpendicular component of the write field and its gradient. Methods of fabricating the writer are provided. | 02-06-2014 |
20140078619 | Shield Designs with Internal Magnetization Control for ATE Improvement - A magnetic recording head is fabricated with a pole tip shielded laterally on its sides by a pair of symmetrically disposed side shields formed of porous heterogeneous material that contains non-magnetic inclusions. The non-magnetic inclusions, when properly incorporated within the magnetic matrix of the shields, promote the formation of flux loops within the shields that have portions that are parallel to the ABS and do not display locally disorganized and dynamic regions of flux during the creation of magnetic transitions within the recording medium by the magnetic pole. These flux loop portions, combine with the magnetic flux emerging from the main pole to create a net writing field that significantly reduces adjacent track erasures (ATE) and wide area erasures (WATE). | 03-20-2014 |
20140099735 | Structure and Method to Fabricate High Performance MTJ Devices for Spin-Transfer Torque (STT)-RAM Application - A STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by natural oxidation and containing an oxygen surfactant layer to form a more uniform MgO layer and lower breakdown distribution percent. A CoFeB/NCC/CoFeB composite free layer with a middle nanocurrent channel layer minimizes Jc | 04-10-2014 |
20140307348 | High Data Rate Writer Design - A magnetic write head is fabricated with its main pole attached to and magnetically coupled to a tapered yoke. The tapered yoke can be a top yoke (on the trailing side of the pole), a bottom yoke (on the leading side of the pole) or a combination of top and bottom configurations. The tapered portion of the yoke is at the distal end of the yoke and it is an extension of an otherwise uniformly thick yoke. It is found that the taper enables the yoke to be close to the ABS for better response times and a high data rate, while simultaneously being distant, producing less field disturbance by the shields and corresponding improvement of BER, and ATE/WATE. A taper of 45° is optimal for its production of uniform magnetization of the pole and optimal response times. | 10-16-2014 |