Ru Thickness Research Articles

Application of Cu Reflow Process on Ru Liner for Advanced Nanoscale Interconnects

Abstract A novel physical vapor deposition (PVD) Cu reflow process with chemical vapor deposition (CVD) Ru liner was optimized for 10 nm generation interconnects and beyond. For these and future device generations, void-free Cu interconnects are a key requirement, and the PVD Cu reflow process improvements reported here provide significant advancement in enabling excellent Cu reflow performance. The Ru liner exhibited much better Cu reflow performance than a Ta liner by effectively suppressing Cu agglomeration during the Cu reflow process, likely due to a better adhesion to Cu. Reflow temperature and Ru thickness (continuity) are critical parameters for achieving good Cu reflow performance, and this optimized Cu reflow process with Ru liner did not show line top voids or sidewall voids, which are the two major void types often observed at this dimension when pursuing Cu fill with the conventional Cu seed and Cu plating fill scheme. Furthermore, this novel Cu reflow process exhibited an electromigration (EM) performance enhancement due to having better Cu fill quality.

Ru Passivation Layer Enables Cu-Cu Direct Bonding at Low Temperatures with Oxidation Inhibition.

Stacking semiconductor chips allows for increased packing density within a given footprint and efficient communication between different functional layers of the chip, leading to higher performance, improved speed, and reduced power consumption. In such vertical stacking, achieving homogeneous electrical and mechanical bonding between heterogeneous chips is crucial, which is termed Cu to Cu direct bonding (CCDB) technology. However, conventional CCDB required a high temperature of over 250 °C to allow Cu diffusion and a vacuum condition for inhibiting Cu oxidation, limiting its practical utilization. Here, we propose that the covering of the Ru layer enables a reliable CCDB as low as 200 °C without concerns regarding oxidation. The bonding strength was as high as 2.24 MPa, and it was endurable at the -45 and 125 °C temperature cycle test for 500 cycles. Through microscopic analysis, we have identified that Cu diffuses through the intercluster boundaries of the Ru layer and moves to the surface, and these atomic Cu ions are recrystallized at the bonding interface, enabling stable bonding at lower temperatures. Specifically, we observed a trade-off between Cu diffusion distance and oxidation inhibition capability depending on the thickness of Ru and found that a 6 nm-thick Ru is optimal, balancing these factors.

A study of Ru–Cr protective coatings for precision glass molding

This study evaluates the performance of Ru–Cr nanolayers used as protective coatings for precision glass molding (PGM) applications. Because the direct growth of Cr-oxide from Cr at high temperatures does not yield a dense oxide scale, Ru is employed as a diffusion barrier to stabilize the growth process. The fabricated coatings were subjected to annealing at 750 °C for different durations, with the coverage of aluminosilicate glass (ASG) pieces. During the annealing process, the outward diffusion of Cr resulted in the formation of thin and stable chromium oxide (Cr2O3) films, which remained unadhered to the glass pieces. Therefore, the Ru–Cr bilayer is a cost-effective coating design to protect mold surfaces in PGM. Detailed analysis using transmission electron microscopy (TEM) revealed that while columnar grains with vertical grain boundaries facilitate the outward diffusion of Cr, a thick Ru layer can effectively hinder Cr diffusion leading to a stable oxide film at a high temperature. A diffusion-oxidation phase-field model quantitatively elucidates oxide film thickness dependence on Ru thickness (>600 nm). Thinner Ru layers (<600 nm) display limited Ru thickness influence and some metallic Cr content in the scales, causing incomplete densification.

High Efficiency and Flexible Modulation of Spintronic Terahertz Emitters in Synthetic Antiferromagnets.

Spintronic terahertz (THz) emitters based on synthetic antiferromagnets (SAFs) of FM1/Ru/FM2 (FM: ferromagnet) have shown great potential for achieving coherent superposition and significant THz power enhancement due to antiparallel magnetization alignment. However, key issues regarding the effects of interlayer exchange coupling and net magnetization on THz emissions remain unclear, which will inevitably hinder the performance improvement and practical application of THz devices. In this work, we have investigated the femtosecond laser-induced THz emission in Pt (3)/CoFe (3)/Ru (tRu = 0-3.5)/CoFe (tCoFe = 1.5-10)/Pt (3) (in units of nm) films with compensated and uncompensated magnetic moments. Antiferromagnetic (AF) coupling occurs in the Ru thickness ranges of 0.2-1.1 and 1.9-2.3 nm, with the first peak (tRu = 0.4 nm) of the AF coupling field (Hex) significantly higher than that of the second peak (2.0 nm). Rather high THz amplitude is found for the samples with strong AF coupling. Nevertheless, despite the same remanence ratio of zero, the THz amplitude for the symmetric SAF films declines significantly as the tRu decreases from 0.8 to 0.4 nm, which is mainly ascribed to the noncolinear magnetization vectors due to the increased biquadratic coupling term. Specifically, we demonstrate that an asymmetric SAF structure with a dominant FM layer is more favored than the completely compensated one, which could generate significantly enhanced THz electric field with well-controlled polarity and intensity. In addition, as the temperature decreases, the THz emission intensity increases for the SAF samples of tRu = 0.9 nm with negligible biquadratic coupling, which is contrary to the decreasing trend of the tRu = 0.4 nm sample and has been attributed to the greatly enhanced Hex.

Study of Synthetic Antiferromagnetic Nanostructures Based on CoFeB/Ru/CoFe

A study of the magnetic properties of synthetic antiferromagnetic nanostructures (SAF) has been carried out. In the SAF structure, two ferromagnetic layers separated by a nonmagnetic metal are coupled by the exchange RKKY interaction (Ruderman— Kittel—Kasuya—Yoshida), which has an oscillating character. The total magnetic moment of the SAF structure is minimal with an antiparallel configuration of the magnetization of the ferromagnetic layers, due to which the effect on the magnetic layers in the structure is reduced. The structures under study have a number of unique properties and are used in the elements of nonvolatile magnetoresistive memory, in magnetic field transducers, and in spin logic devices. The characteristics of the SAF of CoFeB/Ru/CoFe nanostructures with the Ru layer thickness corresponding to the second antiferromagnetic maximum are obtained. The magnetization reversal curves of SAF structures with Ru thickness of 2.1 nm, 2.3 nm and 2.5 nm have been studied. The optimal ratio of ferromagnetic layers was selected to reduce the magnetic moment of the SAF structure. A study of the effect of thermomagnetic treatment on the properties of the SAF nanostructure was carried out, which showed that there are no significant changes in the magnetization reversal, and the magnetic saturation field slightly increases. The curves of magnetization reversal of CoFeB/Ru/CoFe structures fixed by the antiferromagnetic layer are presented. In addition, magnetization reversal curves of spin-tunnel magnetoresistive nanostructures with an antiferromagnetic layer and a SAF structure are presented, and an analysis of the thermal stability of the structures with SAF is also carried out.

Unusual Magnetic Hysteresis and Transition between Vortex and Double Pole States Arising from Interlayer Coupling in Diamond-Shaped Nanostructures.

Controlling the magnetic ground states at the nanoscale is a long-standing basic research problem and an important issue in magnetic storage technologies. Here, we designed a nanostructured material that exhibits very unusual hysteresis loops due to a transition between vortex and double pole states. Arrays of 700 nm diamond-shaped nanodots consisting of Py(30 nm)/Ru(tRu)/Py(30 nm) (Py, permalloy (Ni80Fe20)) trilayers were fabricated by interference lithography and e-beam evaporation. We show that varying the Ru interlayer spacer thickness (tRu) governs the interaction between the Py layers. We found this interaction mainly mediated by two mechanisms: magnetostatic interaction that favors antiparallel (antiferromagnetic, AFM) alignment of the Py layers and exchange interaction that oscillates between ferromagnetic (FM) and AFM couplings. For a certain range of Ru thicknesses, FM coupling dominates and forms magnetic vortices in the upper and lower Py layers. For Ru thicknesses at which AFM coupling dominates, the magnetic state in remanence is a double pole structure. Our results showed that the interlayer exchange coupling interaction remains finite even at 4 nm Ru thickness. The magnetic states in remanence, observed by magnetic force microscopy (MFM), are in good agreement with corresponding hysteresis loops obtained by the magneto-optic Kerr effect (MOKE) and micromagnetic simulations.

Highly efficient spin-orbit torque in a perpendicular synthetic ferrimagnet

Perpendicular synthetic ferrimagnet (pSFi) due to the low stray field and net magnetization is expected to replace single ferromagnet as a free layer to optimize the memory devices for high storage density and low-energy consumption. Here, we investigate the dependence of exchange-coupling strength on the thickness of the spacer Ru and current-induced magnetization reversal due to spin-orbit torque in $\mathrm{Ta}/\mathrm{Pt}/{[\mathrm{Pt}/\mathrm{Co}]}_{2}/\mathrm{Ru}/{[\mathrm{Co}/\mathrm{Pt}]}_{4}/\mathrm{Pt}$ structure with a perpendicular magnetic anisotropy. An oscillating interlayer exchange coupling as a function of Ru spacer layer thickness with a period of 1.16 nm is determined by combining the anomalous Hall effect and the polar magnetic-optical Kerr effect. Furthermore, current-controllable magnetization reversal experiments reveal that the magnetizations of top and bottom layers with antiferromagnetic coupling switch simultaneously due to the combination of spin-orbit torque generated from the two adjacent heavy-metal layers and the interlayer exchange torque. The SOT efficiency $\ensuremath{\chi}\ensuremath{\sim}57.52\phantom{\rule{0.16em}{0ex}}\mathrm{Oe}/({10}^{6}\phantom{\rule{0.16em}{0ex}}\mathrm{A}/\mathrm{c}{\mathrm{m}}^{2})$, corresponding to an effective spin Hall angle $\phantom{\rule{4pt}{0ex}}{\ensuremath{\xi}}_{DL}\ensuremath{\sim}0.68$, is estimated by analyzing current-dependent anomalous Hall resistance with our proposed quasistatic balance equation of magnetic moments. In addition to the advantage of minimizing stray field acting on the storage layer, the observed low switching current density and high spin-orbit torque efficiency suggest that the pSFi structure with a high thermal stability factor has great potential to realize the high-density and low-power consumption of nonvolatile magnetic memory devices.

Ru thickness-dependent interlayer coupling and ultrahigh FMR frequency in FeCoB/Ru/FeCoB sandwich trilayers

The antiferromagnetic (AFM) interlayer coupling effective field in a ferromagnetic/non-magnetic/ferromagnetic (FM/NM/FM) sandwich structure, as a driving force, can dramatically enhance the ferromagnetic resonance (FMR) frequency. Changing the non-magnetic spacer thickness is an effective way to control the interlayer coupling type and intensity, as well as the FMR frequency. In this study, FeCoB/Ru/FeCoB sandwich trilayers with Ru thickness (t Ru) ranging from 1 Å to 16 Å are prepared by a compositional gradient sputtering (CGS) method. It is revealed that a stress-induced anisotropy is present in the FeCoB films due to the B composition gradient in the samples. A t Ru-dependent oscillation of interlayer coupling from FM to AFM with two periods is observed. An AFM coupling occurs in a range of 2 Å ≤ t Ru ≤ 8 Å and over 16 Å, while an FM coupling is present in a range of t Ru < 2 Å and 9 Å ≤ t Ru ≤ 14.5 Å. It is interesting that an ultrahigh optical mode (OM) FMR frequency in excess of 20 GHz is obtained in the sample with t Ru = 2.5 Å under an AFM coupling. The dynamic coupling mechanism in trilayers is simulated, and the corresponding coupling types at different values of t Ru are verified by Layadi’s rigid model. This study provides a controllable way to prepare and investigate the ultrahigh FMR films.

Supercurrent transmission through Ni/Ru/Ni synthetic antiferromagnets

Josephson junctions containing ferromagnetic materials are generating interest for use in superconducting electronics and cryogenic memory. Optimizing the performance of such junctions is an ongoing effort, requiring exploration of a broad range of magnetic systems. Here, we study supercurrent transmission through Ni/Ru/Ni synthetic antiferromagnets with the idea that their magnetic properties may be superior to those of isolated Ni layers. We find that the decay of the supercurrent as a function of Ni thickness is very slow with a decay length of 7.5 ± 0.8 nm. We also characterize the magnetic properties of the synthetic antiferromagnets as a function of Ni and Ru thicknesses.

Interlayer exchange coupling modulated spin-orbit torque and multi-state switching in GdCo/Ru/GdCo heterostructures

The interlayer exchange coupling (IEC) in a synthetic antiferromagnet (SAF) contributes to the spin-orbit torque (SOT) effect. In this work, we study the SOT switching mechanism in a GdCo/Ru/GdCo SAF structure by varying the thickness of Ru (t Ru). It is found that the IEC changes from ferromagnetic to antiferromagnetic and then back to ferromagnetic coupling with increasing t Ru. By performing harmonic Hall measurements, it is confirmed that the antiferromagnetic IEC between two GdCo layers through Ru can significantly enhance the SOT, and a spin torque efficiency of up to 0.71 is obtained. Depending on the sign and strength of the IEC, the combination of SOT and IEC leads to various current-induced switching models. For samples with strong ferromagnetic and antiferromagnetic IEC, the magnetization switching between two parallel or antiparallel states is achieved. The current-induced multi-state switching processes, including four-steps-four-states and six-steps-four-states, are observed for samples with weakened IEC when t Ru is thicker than 0.57 nm. Our results enrich the SOT switching mechanism in SAF structures composed of rare-earth-transition-metal alloys.

Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering

Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)2Te3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λIEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λIEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin–orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λIEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.

Atomic layer deposition and selective etching of ruthenium for area-selective deposition: Temperature dependence and supercycle design

For future sub-5 nm technology nodes, the fabrication of semiconductor devices will likely involve the use of area-selective atomic layer deposition (ALD). While area-selective ALD processes have been reported for a variety of materials, most approaches yield a limited selectivity, for example, due to growth initiation at defects or impurities on the non-growth area. Recently, we demonstrated that Ru ALD can be combined with selective etching to achieve area-selective ALD of metal-on-metal with high selectivity. Cycles consisting of an O2 plasma and an H2 gas dose were integrated in an ALD-etch supercycle recipe to remove unwanted nuclei on the SiO2 non-growth area, while obtaining deposition on the Pt or Ru growth area. The current work discusses the challenging compromise that needs to be made between selectivity and net deposition, considering that the material is also removed from the growth area. After investigating deposition between 100 and 200 °C on SiO2, Al2O3, Pt, and Ru in terms of selectivity and net deposition, a substrate temperature of 150 °C was selected since the difference in Ru thickness on Pt and SiO2/Al2O3 was maximum at this temperature, even though still some deposition occurred on the SiO2 and Al2O3 non-growth areas. Different ALD-etch supercycles were studied, using varying O2 plasma etch times and etch frequencies. The amount of the (undesired) material deposited on the SiO2 non-growth area was quantified, demonstrating that the selectivity improved for longer O2 plasma times. On the basis of the results, a simple mathematical description of the nucleation, growth, and etching effects during ALD-etch supercycles is discussed, which can assist the design of future area-selective deposition processes. Overall, this work illustrates how ALD and etch processes can be tuned to simultaneously obtain a high selectivity and a high net deposition of the material at the desired locations.

Dynamic interlayer exchange coupling in magnetic anisotropic FeCoB/Ru/FeCoB sandwich trilayers

Transverse and longitudinal vector network analyzer ferromagnetic resonance (VNA-FMR) spectroscopy, which can easily distinguish the optical and acoustic modes of FMR, is used to study the dynamic interlayer exchange coupling (IEC) in the oblique sputtered Fe56Co24B20(26.5 nm)/Ru(tRu)/Fe56Co24B20(26.5 nm) trilayers with various Ru thicknesses tRu. Comparing with the static IEC research method, the dynamic method not only analyzes the frequency response characteristics caused by IEC, but also identifies the nature of IEC. In the studied system, an oscillatory interlayer coupling shows up in the VNA-FMR dynamic measurement. An antiferromagnetic (AFM) coupling appears at 0.35 nm < tRu≤0.9 nm, while a strong ferromagnetic coupling dominates at tRu≤0.3 nm and a weak ferromagnetic coupling dominates at tRu≥1 nm. The strongest AFM coupling with coupling coefficient J1 of −0.87 erg/cm2 occurs at the intermediate thickness oftRu ~0.5 nm, while a strong FM coupling with J1 as large as 1.1 erg/cm2 dominates in the relatively thin 0.23 nm Ru spacers. The coupling mechanism is simulated with Layadi’s rigid model and the oscillatory behavior of the bilinear IEC coefficient J1 versus tRu is obtained.

Performance and Stability Enhancement of Ni-Based Cermet Anode Using Atomic Layer Deposited Ruthenium for Direct Methane-Fueled Low-Temperature Solid Oxide Fuel Cell

Nickel (Ni) based cermet, e.g., Ni-doped zirconia(e.g., YSZ) and Ni-doped ceria(e.g., GDC), is the most widely used anode material for solid oxide fuel cell (SOFC). SOFC has been considered as a promising energy converter because of its high efficiency, eco-friendliness, and fuel flexibility. However, recently, SOFC operating below 500°C with more conventional fuels such as hydrocarbon or alcohol are actively studied for overcoming the limitations of high temperature SOFC, e.g., durability, cost, and limited application. Therefore, the necessity of improving the performance and stability of Ni-based anode is aroused because it shows relatively slow hydrocarbon and alcohol oxidation kinetics in the low-temperature regime and vulnerable to carbon deposition. To improve kinetics and stability of Ni-based anode upon hydrocarbon fuel-based operation, various kinds of metal catalysts, e.g., copper, palladium, iron, etc., have been applied using fabrication techniques such as wet synthesis, infiltration, vapor deposition, etc. In this study, ruthenium (Ru) having high catalytic activity and carbon coking toleration is applied to Ni-based cermet anode used in methane-fueled low-temperature SOFC. In particular, atomic layer deposition (ALD), which can deposit nanoparticles conformally on porous structures, is used for depositing Ru nanoparticles on nano-structured Ni-based cermet anode. ALD Ru nanoparticles fabricated in such a way are well-dispersed on the surface of Ni-based cermet anode and effectively improve the performance and stability of the anode when it is operated with methane-fuel. Especially, Ni-based anode with optimal ALD Ru thickness, i.e., 10nm in thickness, shows 40% higher maximum power density than those without ALD Ru overcoating when operated with methane fuel.

Structural color and near-infrared tunability of ruthenium-coated anodic aluminum oxide by atomic layer deposition

Here, we systematically investigate optical behaviors of ruthenium (Ru)-coated nanoporous anodic aluminum oxide (AAO) nanoarchitectures in the visible and near-Infrared (NIR) regions, where they are fabricated by an atomic layer deposition (ALD) process. Depending on the Ru thickness and the AAO dimensions, the Ru nanoarchitectures could be completely changed (tubular-type or wire-type Ru nanostructures), and the corresponding optical properties are critically affected. Brilliant structural colors are found from the Ru-coated AAO nanostructures, in which the color display covers the full visible range. Beyond the visible region, we also examine the optical behaviors of Ru-coated AAO nanostructures in the NIR region.

Structural Color and Nir Tunability of Ruthenium-Coated Anodic Aluminum Oxide by Atomic Layer Deposition

Here, we systematically investigate optical behaviors of ruthenium (Ru)-coated nanoporous anodic aluminum oxide (AAO) nanoarchitectures in the visible and NIR regions, where they are fabricated by using an atomic layer deposition (ALD) process. Depending on the Ru thickness and the AAO dimensions, the Ru nanoarchitectures could be completely changed (tubular-type or wire-type Ru nanostructures), and the corresponding optical properties are critically affected. Brilliant structural colors are found from the Ru-coated AAO nanostructures, in which the color display covers the full visible range. Beyond the visible region, we also examine the optical behaviors of Ru-coated AAO nanostructures in the NIR region.

Interlayer exchange coupling in Pt/Co/Ru and Pt/Co/Ir superlattices

Magnetic multilayer thin films with perpendicular magnetic anisotropy (PMA) and interfacial Dzyaloshinskii-Moriya interaction (iDMI) are of intense interest for realizing magnetic skyrmions and modifying topological spin textures. We systematically investigate interlayer exchange coupling (IEC) in Pt/Co/Ru(Ir) superlattices that have PMA and large iDMI. The IEC is greatly tunable by varying Ru(Ir) or Pt thickness and the antiferromagnetic IEC is as large as $1.3\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$ that is on the same order of magnitude as the iDMI. We find unusual magnetic hysteresis loop crossing between field-ascending and -descending magnetization curves. Furthermore, we identify magnetic phase diagrams for antiferromagnetic IEC and hysteresis loop crossing with respect to Ru(Ir) and Pt thickness. Our experimental findings may open a way in the development of synthetic antiferromagnetic spintronics and/or the realization of antiferromagnetic skyrmions.

Simultaneous Control of Interlayer Exchange Coupling and the Interfacial Dzyaloshinskii–Moriya Interaction in Ru-Based Synthetic Antiferromagnets

We present a Ru-based synthetic antiferromagnet (SAF) made with asymmetric ferromagnetic building blocks (Pt/Co/Ir or Ir/Co/Pt) to couple their interfacial Dzyaloshinskii-Moriya interaction (DMI) with strong interlayer exchange coupling (IEC). This combination may lead to new types of antiferromagnetic domain walls (DWs), which are conceptually presented in this letter. These include an energetically frustrated configuration and an “isolated” spin chain where a net magnetization exists only at the DW. While most SAF designs incorporate a Co/Ru/Co IEC layer, chiral SAFs require Pt and/or Ir at the Ru/Co interface. In all cases except Pt/Ru/Pt, a significant IEC field is preserved over a range of Ru thicknesses, with the largest occurring for Ir/Ru/Ir. These results demonstrate that ferromagnetic film stacks with purportedly strong DMI can be incorporated into SAFs without compromising IEC.

Temperature-dependent interlayer exchange coupling strength in synthetic antiferromagnetic [Pt/Co]2/Ru/[Co/Pt]4 multilayers**Project supported by the National Natural Science Foundation of China (Grant No. 11704191), the Jiangsu Specially-Appointed Professor, the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20171026), and the Six-Talent Peaks Project in Jiangsu Province, China (Grant No. XYDXX-038).

In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field (Hex) and strength (–Jiec) in synthetic antiferromagnetic (SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[Co(0.6)/Pt(0.6)]4 multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium (Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The Hex were studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the –Jiec. It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The Hex exhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K (Hex = 3.19 KOe, –Jiec = 1.97 erg/cm2 for tRu = 0.6 nm, the unit 1 Oe = 79.5775 A·m–1), which was higher than the previous studies.

Antiparallel-Pinned Spin Valves With Modified Artificial Antiferromagnetic Layer for Full-Bridge Magnetic Sensors

A full-bridge magnetoresistive spin valve (SV) sensor scheme for applications of linear magnetic measurement is fabricated and analyzed with the sign of magnetoresistance (MR) can be tuned by the modified the artificial antiferromagnetic (AAF) layer. In the last two decades, SV sensors have shown their crucial roles in the life. The common applications of SV sensors are used in position, angle sensors [1], [2], electronic compasses, and contactless current sensors [3]. To build a sensor, especially for resistive sensors, a Wheatstone-bridge is always a good solution for its advantages of the lessening dc-offset, and temperature errors [4]. In the MR sensor fabrication, the bias direction is also the main factor that decides the sensor architectures. For instance, a half-bridge was realized by two active cells, whereas shielding the other two cells [5], [6] or killing their sense by the roughened surfaces [7]. However, the effective sensitivity and linearity of the sensor are reduced [8]. There are several methods to form a full-bridge that provides a maximum output of the sensor. For example, the current strap was directly fabricated on the surface of the device to induce the local bias magnetic field during the cool-field post-annealing process [9]. Using an appropriate location of MR cells within the gap of the flux guide, a full-bridge could be established [10]. An antiparallel alignment of the pinned direction of the two pairs of MR cells was carried out by a microscopic focused laser heating during cool-field treatment [11]. Another method is that the usage of two deposition processes for two pairs of MR cells in the opposite applied magnetic field [12]. In this work, we propose a method to tune the bias direction of two neighboring meanders in the full-bridge by varying the thickness of Ru in AAF layers of patterned SV cells with a single post-field annealing step. In order to implement the proposed design, the two deposition processes were carried out. First one, two normal magnetoresistance SV cells are the structure of (Si/SiO 2 ) /Ta(50A)/NiFe(30A)/Co(15A)/Cu(24A)/CoFe(25A)/ IrMn(100A)/Ta(50A), whereas, the other two cells are the inverse magnetoresistance with an AAF layer of structure of (Si/SiO 2 ) /Ta(50A)/NiFe(30A)/ Co(15A)/Cu(24A)/[CoFe(15A)/Ru(7A)/CoFe(25A)]/IrMn(100A)/Ta(50A). The normal MR and inverse MR curves of the different SV structures are shown in Fig. 1. The SV films were prepared by RF magnetron sputtering. The conventional lift-off method was used to pattern the MR cells. A tiny permanent magnet was used to adjust the sensor operating point. To estimate an appropriate MR ratio for an expectation sensitivity, the hyperbolic tangent model was introduced by author et al. [13], a required MR correspondences a sensitivity and a saturation field range was given by MR =(2.({dV/V/dB}).$B_{s}$)/ (G_{m} -$(dV/V/dB).$B_{s})(1)$ where $MR$ is the magnetoresistance ratio, dV/V/dB is the sensitivity of the bridge (V/V/Oe), $B_{s}$ is the saturation field, and $G_{m}$ is the flux amplification factor. Suppose, $G_{m}$ \quad =1(no gain flux density), and the $B_{s}$ is about 50 Oe, in order to yield a sensitivity of 1 mV/V/Oe, the MR ratio should be at least 10.5 %. The SV cells were patterned to the dimensions of $200 \mu \mathrm{m}\times 2 \mu \mathrm{m}$. The resistance of individual SV cell is about 10 kv Ω. The cut chip dimension is 2 mm \times 1 mm was attached to a printed circuit (PCB) board using the aluminum wire bonding method. The voltage output of the bridge was amplified by a preamplifier using AD620 from Analog Device, Inc., and connected to a data acquisition device (MyDAQ). The data was recorded using a software coded in the LabVIEW. The performance of the SV full-bridge was verified by setting up the sensor in a sweeping magnetic field of \pm 150 Oe induced by a Helmholtz coil. The response curve of the full bridge to the external fields are shown in Fig. 2. The obtained sensitivity is 0.23 mV/V/Oe with $B_{s}$ is about 100 Oe and a patterned MR ratio of 4.5 % is in agreement with the hyperbolic tangent model in Eq. (1) [13]. Further experiments to increase the resistance of GMR elements using the advanced microfabrication methods are still ongoing. The sensitivity of the bridge can be further enhanced by the patterning SV cells in series [14] or the usage of a flux amplification (flux concentrators) [15].