阅读说明：本技术 磁装置 (Magnetic device ) 是由 林相镐 金时年 于 2019-03-18 设计创作，主要内容包括：本发明提供一种磁装置,包含：钉扎层,具有平面内磁化方向；自由层,具有平面内磁化方向,与钉扎层竖直间隔开以与钉扎层对准；导电间隔物层,安置在钉扎层与自由层之间；反铁磁层,安置以固定钉扎层的磁化方向且与钉扎层竖直间隔开以与钉扎层对准；以及贵金属间隔物层,安置在钉扎层与反铁磁层之间。(The present invention provides a magnetic device comprising: a pinned layer having an in-plane magnetization direction; a free layer having an in-plane magnetization direction, vertically spaced apart from the pinned layer to be aligned with the pinned layer; a conductive spacer layer disposed between the pinned layer and the free layer; an antiferromagnetic layer disposed to fix a magnetization direction of the pinned layer and vertically spaced apart from the pinned layer to be aligned with the pinned layer; and a noble metal spacer layer disposed between the pinning layer and the antiferromagnetic layer.)

1. A magnetic device, comprising:

a pinned layer having an in-plane magnetization direction;

a free layer having an in-plane magnetization direction, the free layer being vertically spaced apart from the pinned layer to align with the pinned layer;

a conductive spacer layer disposed between the pinned layer and the free layer;

an antiferromagnetic layer disposed to pin the magnetization direction of the pinned layer and vertically spaced apart from the pinned layer to be aligned with the pinned layer; and

a noble metal spacer layer disposed between the pinned layer and the antiferromagnetic layer.

2. The magnetic device of claim 1 wherein the noble metal spacer layer is a single layer thin film of copper or platinum, or a multilayer thin film of copper and platinum, and

the noble metal spacer layer has a thickness of 0.1 to 0.8 nanometers.

3. The magnetic device of claim 1, wherein the free layer has a shape magnetic anisotropy, and

the magnetic device is connected with a Wheatstone bridge structure.

4. The magnetic device of claim 1, wherein the conductive spacer layer comprises copper and has a thickness of 2.2 nanometers.

5. The magnetic device of claim 1, wherein the noble metal spacer layer comprises Pt₂Cu₁、Cu₂Pt₁Or Cu₃Pt₂，

Where each subscript indicates thickness in angstroms.

6. The magnetic device of claim 1, wherein the pinned layer comprises CoFe, and

the free layer includes a first ferromagnetic layer of NiFe and a second ferromagnetic layer of CoFe.

7. A magnetic device, comprising:

a pinned layer having an in-plane magnetization direction;

a free layer having an in-plane magnetization direction, the free layer being vertically spaced apart from the pinned layer to align with the pinned layer;

a tunneling insulating layer disposed between the pinned layer and the free layer;

an antiferromagnetic layer disposed to pin the magnetization direction of the pinned layer and vertically spaced apart from the pinned layer to be aligned with the pinned layer; and

a noble metal spacer layer disposed between the pinned layer and the antiferromagnetic layer.

8. The magnetic device of claim 7, wherein the noble metal spacer layer is a single-layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and

the noble metal spacer layer has a thickness of 0.1 to 0.8 nanometers.

9. The magnetic device of claim 7, wherein the free layer has a shape magnetic anisotropy, and

the magnetic device is connected with a Wheatstone bridge structure.

10. The magnetic device of claim 7 wherein the tunneling insulating layer includes MgO, AlOx, or GdOx.

11. The magnetic device of claim 7, wherein the noble metal spacer layer comprises Pt₂Cu₁、Cu₂Pt₁Or Cu₃Pt₂，

Where each subscript indicates thickness in angstroms.

12. The magnetic device of claim 7, wherein the pinning layer comprises CoFe, and

the free layer includes a first ferromagnetic layer of NiFe and a second ferromagnetic layer of CoFe.

Technical Field

The present disclosure relates to magnetic devices, and more particularly, to a magnetic device using the giant magnetoresistance effect or a magnetic device having the tunneling magnetoresistance effect, which includes an ultra-thin noble metal spacer layer interposed between an antiferromagnetic layer and a pinning layer.

Background

The Giant Magnetoresistance (GMR) effect is a phenomenon in which resistance decreases when magnetization directions of a free layer and a pinned layer are parallel to each other and resistance increases when the magnetization directions of the free layer and the pinned layer are antiparallel to each other in a spin valve structure. The GMR effect is an important core technology for magnetic sensors in micro-electromechanical systems (MEMS), such as biosensors, hard disk read head sensors, and vibration sensors. Giant magneto-resistive (GMR) elements can be used as magnetic sensors.

Disclosure of Invention

Technical challenge

An aspect of the present disclosure is to provide a magnetic device that suppresses (applying) a signal generated by an external magnetic field in an easy magnetization direction in a magnetic sensor having a Wheatstone (Wheatstone) bridge structure and improves signal sensitivity depending on the external magnetic field in a hard magnetization direction.

Another aspect of the present disclosure is to provide a magnetic device that increases a sensing range of an external magnetic field along a hard magnetization direction in a magnetic sensor having a wheatstone bridge structure.

Technical solution

According to an aspect of the present disclosure, a magnetic device includes: a pinned layer having an in-plane magnetization direction; a free layer having an in-plane magnetization direction, vertically spaced apart from the pinned layer to be aligned with the pinned layer; a conductive spacer layer disposed between the pinned layer and the free layer; an antiferromagnetic layer disposed to pin a magnetization direction of the pinned layer and vertically spaced apart from the pinned layer to be aligned with the pinned layer; and a noble metal spacer layer disposed between the pinning layer and the antiferromagnetic layer.

In example embodiments, the noble metal spacer layer may be a single-layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and may have a thickness of 0.1 to 0.8 nanometers (nm).

In an example embodiment, the free layer may have shape magnetic anisotropy, and the magnetic device may be connected with a Wheatstone bridge structure.

In an example embodiment, the conductive spacer layer may include copper and may have a thickness of 2.2 nanometers.

In example embodiments, the noble metal spacer layer may include Pt₂Cu₁、Cu₂Pt₁Or Cu₃Pt₂With each subscript indicating the thickness in angstroms.

In example embodiments, the pinned layer may include CoFe and the free layer may include a first ferromagnetic layer of NiFe and a second ferromagnetic layer of CoFe.

According to an aspect of the present disclosure, a magnetic device includes: a pinned layer having an in-plane magnetization direction; a free layer having an in-plane magnetization direction, vertically spaced apart from the pinned layer to be aligned with the pinned layer; a tunneling insulating layer disposed between the pinned layer and the free layer; an antiferromagnetic layer disposed to pin a magnetization direction of the pinned layer and vertically spaced apart from the pinned layer to be aligned with the pinned layer; and a noble metal spacer layer disposed between the pinning layer and the antiferromagnetic layer.

In example embodiments, the noble metal spacer layer may be a single-layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and may have a thickness of 0.1 to 0.8 nanometers (nm).

In an example embodiment, the free layer may have shape magnetic anisotropy, and the magnetic device may be connected with a Wheatstone bridge structure.

In example embodiments, the tunneling insulating layer may include MgO, AlOx, or GdOx.

In example embodiments, the noble metal spacer layer may include Pt₂Cu₁、Cu₂Pt₁Or Cu₃Pt₂With each subscript indicating the thickness in angstroms.

In example embodiments, the pinned layer may include CoFe and the free layer may include a first ferromagnetic layer of NiFe and a second ferromagnetic layer of CoFe.

Advantageous effects

As described above, in a magnetic device according to example embodiments, a noble metal spacer layer may be inserted between an antiferromagnetic layer and a pinning layer to adjust a sensitivity value in a hard magnetic axis direction of the magnetic device.

In a magnetic device according to example embodiments, a noble metal spacer layer may be interposed between the ferromagnetic layer and the pinned layer to increase a sensing range of a bias magnetic field in a hard magnetic axis direction of the magnetic device.

In a magnetic device according to example embodiments, a noble metal spacer layer may be inserted between the ferromagnetic layer and the pinned layer to reduce a bias magnetic field in a magnetic easy axis direction of the magnetic device.

In the magnetic device according to example embodiments, a noble metal spacer layer may be interposed between the antiferromagnetic layer and the pinned layer to increase the density of the neel domain wall, enable improvement of magnetostatic interaction caused by a magnetic domain wall, and increase magnetic flux closure so that the magnetization reversal field of the free layer (in which magnetization reversal occurs from an antiparallel state to a parallel state) is significantly increased. Therefore, the bias magnetic field of the free layer can be reduced to improve the sensitivity in the hard axis direction.

In the ultra-thin noble metal spacer layer of the magnetic device according to example embodiments, a noble metal spacer layer may be interposed between the antiferromagnetic layer and the pinned layer so that the density of the neel domain wall of the pinned layer may be adjusted to control the bias magnetic field of the free layer. In addition, the noble metal spacer layer may cause specular scattering on the upper and lower boundaries to increase the magnetic resistance value.

Drawings

FIG. 1 is a conceptual diagram of a Wheatstone bridge GMR magnetic sensor according to an example embodiment of the present disclosure.

Fig. 2 shows the resistance depending on the external magnetic field in the direction of the hard magnetic axis in the first GMR resistor in fig. 1.

Fig. 3 illustrates a magnetization direction of a pinned layer and a shape magnetic anisotropy direction of a free layer of the first GMR resistor in fig. 1.

Fig. 4 shows the magnetization direction of the free layer depending on the outer direction along the hard magnetic axis direction in the first GMR resistor in fig. 1.

Fig. 5 shows the resistance depending on the external magnetic field in the direction of the hard magnetic axis in the second GMR resistor of fig. 1.

Fig. 6 illustrates a magnetization direction of a pinned layer and a shape magnetic anisotropy direction of a free layer of the second GMR resistor in fig. 1.

Fig. 7 shows the magnetization direction of the free layer depending on the direction of the external magnetic field in the direction of the hard magnetic axis in the second GMR resistor in fig. 1.

Fig. 8A to 8D show resistances depending on external magnetic fields in the magnetic easy axis directions from the first GMR resistor to the fourth GMR resistor in fig. 1.

Fig. 9A to 9D show resistances depending on external magnetic fields in the hard magnetic axis directions from the first GMR resistor to the fourth GMR resistor in fig. 1.

Fig. 10A and 10B illustrate voltages between the first terminal (a) and the third terminal (c) depending on external magnetic fields in the magnetic easy axis direction and external magnetic fields (Hx, Hy) in the wheatstone bridge magnetic sensor in fig. 1.

Fig. 11A is a plan view of a GMR element according to an example embodiment of the present disclosure.

Fig. 11B is a cross-sectional view of a GMR element according to an example embodiment of the present disclosure.

Fig. 12A to 12D illustrate magnetization characteristics depending on an external magnetic field in a magnetically easy axis direction of a material in a magnetic device according to an example embodiment of the present disclosure and a thickness of a noble metal spacer layer.

Fig. 13 illustrates Magneto-optical Kerr effect (MOKE) microscope images and hysteresis characteristics depending on whether a noble metal spacer layer is present in a magnetic device according to an example embodiment of the present disclosure.

Fig. 14A to 14D are graphs representing test results showing a magnetoresistance ratio depending on an external magnetic field in a magnetic easy axis direction in a magnetic device according to an example embodiment of the present disclosure.

FIG. 15 is a view from FIG. 14A to FIG. 15Cu in FIG. 14D₃Pt₂The plot of magnetoresistance ratios is magnified below.

Fig. 16A to 16D are graphs representing test results showing magnetoresistance ratios depending on external magnetic fields in the hard magnetic axis direction in a magnetic device according to an example embodiment of the present disclosure.

FIG. 17 is a graph illustrating sensitivity (S) and bias magnetic field (H) of a free layer in a magnetic device according to an example embodiment of the present disclosure_bias) A graph of the correlation between.

FIG. 18 is a cross-sectional view of a magnetic device according to another example embodiment of the present disclosure.

Detailed Description

Giant magnetoresistive (Giant magnetoresistive) magnetic sensors have characteristics that improve signal-to-noise ratio and thermal stability. When the thin film of the spin valve structure is provided in the form of a Wheatstone push-pull bridge (Wheatstone push-pull bridge) pattern, the unipolar signal is converted into a bipolar signal. Based on this fact, a GMR magnetic sensor is used as the magnetic sensor. A non-hysteresis curve is also observed when a magnetic field is applied in the direction of the hard axis (magnetic hard axis) of the free layer. Using this fact may allow ensuring the linear characteristics of the sensor. The slope or Sensitivity Value (Sensitivity Value) occurring in the low magnetic field region in the direction of the hard magnetic axis is a very important factor affecting the Sensitivity characteristics of the GMR sensor. The Sensitivity Value (Sensitivity Value) appearing in the low magnetic field region in the direction of the hard axis needs to be increased. Further, when the magnetic easy axis signal is generated by a magnetic field in the magnetic easy axis direction, the magnetic hard axis signal generated by the magnetic field in the magnetic hard axis direction overlaps with the magnetic easy axis signal to be distorted. Therefore, there is a need for a method of containing the magnetically easy axis signal generated by the magnetic field in the magnetically easy axis direction within the sensing range to be measured.

In the tunneling magnetoresistive magnetic sensor, when the magnetic easy axis signal is generated by the magnetic field in the magnetic easy axis direction in the same manner, the magnetic hard axis signal generated by the magnetic field in the magnetic hard axis direction is distorted.

According to example embodiments, a noble metal spacer layer may be interposed between a pinned layer and an antiferromagnetic layer of a magnetoresistive element to suppress a magnetic easy axis signal generated by a magnetic field in a magnetic easy axis direction within a magnetic field range.

Embodiments of the present disclosure will now be described more fully with reference to the accompanying drawings. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

FIG. 1 is a conceptual diagram of a Wheatstone bridge GMR magnetic sensor according to an example embodiment of the present disclosure.

Fig. 2 shows the resistance depending on the external magnetic field in the hard magnetic axis direction in the first GMR resistor in fig. 1.

Fig. 3 illustrates a magnetization direction of a pinned layer and a shape magnetic anisotropy direction of a free layer of the first GMR resistor in fig. 1.

Fig. 4 shows the magnetization direction of the free layer depending on the outer direction along the hard magnetic axis direction in the first GMR resistor in fig. 1.

Fig. 5 shows the resistance depending on the external magnetic field in the direction of the hard magnetic axis in the second GMR resistor of fig. 1.

Fig. 6 illustrates a magnetization direction of a pinned layer and a shape magnetic anisotropy direction of a free layer of the second GMR resistor in fig. 1.

Fig. 7 shows the magnetization direction of the free layer depending on the direction of the external magnetic field in the direction of the hard magnetic axis in the second GMR resistor in fig. 1.

Fig. 8A to 8D show resistances depending on external magnetic fields in the magnetic easy axis directions from the first GMR resistor to the fourth GMR resistor in fig. 1.

Fig. 9A to 9D show resistances depending on external magnetic fields in the hard magnetic axis directions from the first GMR resistor to the fourth GMR resistor in fig. 1.

Fig. 10A and 10B illustrate voltages between the first terminal (a) and the third terminal (c) depending on external magnetic fields in the magnetic easy axis direction and external magnetic fields (Hx, Hy) in the wheatstone bridge magnetic sensor in fig. 1.

Referring to fig. 1 to 7, 8A to 8D, 9A to 9D, and 10A and 10B, the wheatstone bridge magnetic sensor (10) includes first to fourth GMR resistors (12a to 12D). A Wheatstone bridge magnetic sensor (10) includes first to fourth terminals (a, b, c, d), a voltage between the first terminal (a) and the third terminal (c) being indicative of an output voltage. The second terminal (b) may be connected to an external DC voltage, and the fourth terminal (d) may be grounded. The first GMR resistor (12a) and the fourth GMR resistor (12d) may be positioned side by side to be spaced apart from each other. The second GMR resistor (12b) and the third GMR resistor (12c) are rotatable around the first GMR resistor (12a) and are positionable side by side to be spaced apart from each other.

Each of the GMR resistors (12 a-12 d) may extend in a length direction and return after being spaced apart, and may have a meandering shape to have a shape magnetic anisotropy, for example. The shape magnetic anisotropy direction of the GMR resistor may be an extension direction of the GMR resistor. The magnetization direction of the pinned layer may be the same for all GMR resistors and may be the x-axis direction rotated at a 45 degree angle in the extension direction. All GMR resistors may have in-plane magnetic anisotropy.

The magnetization direction of the pinned layer may match the magnetic easy axis of the free layer. The external magnetic field may include a magnetic easy axis magnetic field applied in a magnetic easy axis direction (x-axis direction) and a magnetic hard axis magnetic field applied in a magnetic hard axis direction (y-axis direction).

The magnetic device includes a seed layer (Ta (5.0 nm)), a free layer (Ta (5.0 nm)), a metal spacer layer (Cu (2.2 nm)), and a pinned layer (Co₉₀Fe₁₀) Antiferromagnetic layer (Ir)₂₁Mn₇₉(6.0 nm)) and a capping layer (Ta (5.0 nm)).

Referring to fig. 2, 3, and 4, when an external magnetic field (Hy) is applied to the first GMR resistor (12a) in the hard axis (y-axis) direction, the free layer may be aligned in the external magnetic field direction in the case where the external magnetic field (Hy) is sufficiently high in strength. Meanwhile, when the external magnetic field (Hy) is low in intensity, the free layer can rotate in the direction of shape magnetic anisotropy (extension direction). In addition, when the external magnetic field (Hy) is removed, the free layer may be aligned in the shape magnetic anisotropy direction.

Referring to fig. 5, 6, and 7, when an external magnetic field (Hy) is applied to the second GMR resistor (12b) in the direction of the magnetic hard axis (y-axis), the free layer may be aligned in the direction of the external magnetic field in the case where the external magnetic field (Hy) has a sufficiently high strength. Meanwhile, in the case where an external magnetic field (Hy) has a low intensity, the free layer may rotate in a shape magnetic anisotropy direction. In addition, when the external magnetic field (Hy) is removed, the free layer may be aligned in the shape magnetic anisotropy direction.

Referring to fig. 8A to 8D, the value of the first GMR resistor (12a) indicates hysteresis depending on the strength and sign of the external magnetic field (Hx) in the direction of the magnetic easy axis (x-axis). The strength of the external magnetic field having a sharp slope in the hysteresis may be point a and point B. In addition, the intermediate value between the points A and B may be the bias magnetic field (H)_bias). Point a may be about 25 o (Oe), point B may be about 10 o, and the bias magnetic field (H)_bias) May be about 17 ao.

Referring to fig. 9A to 9D, the value of the first GMR resistor (12a) has a single value depending on the strength and sign of the external magnetic field (Hy) in the direction of the magnetic hard axis (y-axis), and may have a minimum value when the external magnetic field (Hy) is close to zero.

Referring to fig. 10A and 10B, the voltage (Vac) between the first terminal (a) and the third terminal (c) of the external magnetic field (Hx) depending on the magnetic easy axis direction in the wheatstone bridge magnetic sensor (10) indicates a negative maximum value (about 25 ° o) at the point a and a positive maximum value (about 10 ° o) at the point B. The earth's magnetic field is 1 or less than 1, and the sensing range for measuring the earth's magnetic field can be from positive to negative.

However, in the sensing range from positive to negative ao, the voltage (Vac) between the first terminal (a) and the third terminal (c) depending on the external magnetic field (Hx) in the magnetic easy axis direction may have a value depending on the peak value or the external magnetic field (Hx). The voltage signal (Vac) generated by the external magnetic field (Hx) in the direction of the magnetic easy axis may cause signal distortion in the direction of the magnetic hard axis to be measured.

Therefore, in the GMR resistor, the points a and B where the resistance hysteresis depending on the external magnetic field (Hx) in the magnetic easy axis direction has to be designed to deviate from the sensing rangeThe maximum slope. In detail, the bias magnetic field (H)_bias) (intermediate values for points a and B) may have a value of zero. The voltage (Vac) between the first terminal (a) and the third terminal (c) depending on the external magnetic field (Hx) in the direction of the magnetic easy axis needs to have a zero value or a constant value within the sensing range.

According to an example embodiment, a method of adjusting a bias magnetic field (H) is provided_bias) The GMR resistive element structure of (1). In the magnetoresistive element according to the example embodiment, the points a and B are positioned outside the sensing range (e.g., negative to positive).

According to example embodiments, the sensitivity value in the direction of the hard axis may be increased.

Fig. 11A is a plan view of a GMR element according to an example embodiment of the present disclosure.

Fig. 11B is a cross-sectional view of a GMR element according to an example embodiment of the present disclosure.

Referring to fig. 11A and 11B, the magnetic device (100) may be a GMR element. The magnetic device (100) comprises: a pinned layer (152) having an in-plane magnetization direction; a free layer (130) having an in-plane magnetization direction, vertically spaced from the pinned layer (152) to align with the pinned layer (152); a conductive spacer layer (140) disposed between the pinned layer (152) and the free layer (130); an antiferromagnetic layer (156) disposed to fix a magnetization direction of the pinned layer (152) and vertically spaced from the pinned layer (152) to align with the pinned layer (152); and a noble metal spacer layer (154) disposed between the pinned layer (152) and the antiferromagnetic layer (154). The noble metal spacer layer (154) may be a single layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and may have a thickness of 0.1 nanometers (nm) to 0.8 nm. The magnetic device (10) may be connected to a Wheatstone bridge configuration to form a magnetic sensor.

The magnetic device (100) may have a winding structure formed on the substrate (100) by repeatedly extending a positive first direction, then extending in a second direction, and then extending in a negative first direction. The opposite ends of the magnetic device (100) may be connected to the electrode pads by electrodes (102a, 102 b).

The magnetization direction of the pinned layer (152) of the magnetic device may be rotated 45 degrees in a first direction (the extending direction of the magnetic device) to be disposed within a plane. The magnetization direction of the pinned layer (152) of the magnetic device may be the magnetic easy axis direction. The free layer (130) of the magnetic device may have a magnetic easy axis that is the same as a magnetic easy axis of the pinned layer (152). The shape anisotropy direction of the magnetic device may be a first direction. Accordingly, the free layer (130) may be aligned in a shape anisotropy direction (first direction) when an external magnetic field is not applied.

The substrate (110) may be a silicon substrate or a semiconductor substrate. The substrate 110 may comprise an insulating layer, such as a silicon oxide layer. More specifically, the substrate may be a substrate obtained by oxidizing a P-type silicon substrate in a hydrated manner.

A seed layer (120) is disposed on a substrate (110). The seed layer (120) may be tantalum (Ta). The seed layer (120) may have a thickness of 5.0 nanometers. The seed layer (120) may provide a smooth surface to a Giant Magnetoresistive (GMR) film of the spin valve structure.

A free layer (130) may be disposed on the seed layer (120). The free layer (130) may include a first ferromagnetic layer (132) and a second ferromagnetic layer (134) stacked in sequence. The first ferromagnetic layer (132) may be Ni₈₀Fe₂₀. The first ferromagnetic layer (132) may have a thickness of 3.0 nanometers. The second ferromagnetic layer (134) may be Co₉₀Fe₁₀. The second ferromagnetic layer (134) may have a thickness of 1.8 nanometers. The free layer (130) is relatively free to provide magnetization switching for an applied magnetic field. The free layer (130) may include Co, Ni, Fe, or an alloy thereof, and may have a single-layer or multi-layer structure. More specifically, the free layer (130) may include NiFe, CoFe, or CoFeB. The free layer (130) may have in-plane magnetic anisotropy, and the magnitude of the in-plane magnetic anisotropy may be adjustably controlled depending on the thickness of the free layer (130) and the crystalline structure and planar direction of atomic accumulation during deposition.

A conductive spacer layer (140) may be disposed on the free layer (130). The conductive spacer layer (140) may be copper. The conductive spacer layer (140) may have a thickness of 2.0 nanometers. The conductive spacer layer (140) may facilitate the GMR effect by spin-dependent scattering.

The conductive spacer layer (140) may be converted to a tunneling barrier layer having insulating properties required for tunneling magnetoresistance similar to the GMR effect, such as MgO, AlOx, GdOx, or the like.

The pinning layer (152) may be disposed on the conductive spacer layer (140). The pinning layer (152) may be Co₉₀Fe₁₀. The pinned layer may have a thickness of 2.0 nanometers. The pinning layer (152) may include Co, Ni, Fe, or an alloy thereof, and may have a single layer or a multi-layer structure. More specifically, the pinning layer (152) may include NiFe, CoFe, or CoFeB. The pinned layer (152) may have in-plane magnetic anisotropy, and the magnitude of the in-plane magnetic anisotropy may be adjustably controlled depending on the thickness of the pinned layer (152) and the crystalline structure and planar direction of atomic accumulation during deposition.

A noble metal spacer layer (154) may be disposed on the pinning layer (152).

The noble metal spacer layer (154) may be Pd, Ag, Au, Ru, Cu, or Pt. The noble metal spacer layer (154) may be a single layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and may have a thickness (t) of 0.1 to 0.8 nanometers. When the thickness of the noble metal spacer layer (154) is greater than 0.8 nm, the interaction between the antiferromagnetic layer (156) and the pinned layer (152) may be reduced, and thus, the magnetization direction of the pinned layer (152) may not be pinned. The noble metal spacer layer (154) may increase the density of Neel domain walls in the pinned layer (152) between the pinned layer (152) and the antiferromagnetic layer (156). The noble metal spacer layer (154) may reduce the bias magnetic field (H) depending on an external magnetic field in the magnetic easy axis direction_bias). Accordingly, signal distortion of the wheatstone bridge circuit caused by the external magnetic field in the magnetic easy axis direction can be reduced. In addition, the noble metal spacer layer (154) may increase the sensitivity of the magnetic signal depending on the external magnetic field in the direction of the hard axis.

An antiferromagnetic layer (156) can be disposed on the noble metal spacer layer (154). The antiferromagnetic layer (156) may be Ir₂₁Mn₇₉. The antiferromagnetic layer (156) may have a thickness of 6.0 nanometers. An antiferromagnetic layer (156) may pin the magnetization direction of the pinned layer (154) in the direction of the exchange bias magnetic field.

A capping layer (160) may be disposed on the antiferromagnetic layer (156). The capping layer (160) may be tantalum (Ta). The cap layer (160) may have a thickness of 5.0 nanometers. A capping layer (160) prevents oxidation of the GMR film of the spin valve structure.

Phases stacked on a magnetic device (100)The reactive layer may be deposited by DC magnetron sputter deposition. In a chamber equipped with a plurality of sputtering targets, the degree of vacuum was about 7X 10^-8Ture. Can be controlled at 2X 10 by injecting argon (Ar) gas^-3The deposition is performed in a torr atmosphere. All layers are deposited successively in a vacuum state. The sputtering target can be Ta, Ni₈₀Fe₂₀、Co₉₀Fe₁₀Cu, Pt and Ir₂₁Mn₇₉. Permanent magnets comprising iron oxide are disposed around the substrate holder on which the thin film is deposited to induce magnetic anisotropy of the free layer (130) and pinned layer (152) during deposition. The permanent magnet applies a uniform magnetic field of 80 ao to the free layer (130) or the pinned layer (152) in a single direction.

After deposition of the cap layer (160) is complete, the substrate (110) is transferred to a new chamber. The new chamber has a size of 1 × 10^-6A degree of vacuum of torr, and a post annealing process was performed at a temperature of 250 deg.c for 10 minutes under a uniform magnetic field of 2 kilo-ohms in the same direction as the direction in which the magnetic anisotropy was formed. Accordingly, the post annealing process may generate an exchange bias magnetic field of the pinning layer (152) and may stabilize the stress generated between the thin films during the deposition process.

Properties such as exchange bias magnetic field and magnetic anisotropy of the pinned layer (152) and bias magnetic field and magnetic anisotropy of the free layer may be adjusted by the magnitude of the magnetic field applied during deposition of the free layer (130) and the pinned layer (152) and the temperature and magnetism of the magnetic field applied during the post annealing process.

The magnetic properties of the GMR film are measured using a vibrating sample magnetometer. Further, the four-probe method was used to measure the magnetoresistance characteristics. Magnetic domain wall behavior in the free layer (130) and pinned layer (152) was observed using a magneto-optical kerr effect (MOKE) microscope.

By adjusting the thicknesses of the free layer (130), antiferromagnetic layer (156), and noble metal spacer layer (154), the interface roughness during deposition, the crystal structure and planar direction of atomic accumulation, and the width and density of the Neel Domain walls, and the like, the magnetostatic interaction caused by the Domain walls can be controlled to adjust the bias magnetic field (H) of the free layer (130)_bias) The size of (2).

The thickness and material of the noble metal spacer layer (154) interposed between the antiferromagnetic layer (156) and the pinning layer (152) can control the width and density of the Neel domain wall of the antiferromagnetic layer (156). The noble metal spacer layer (152) controls magnetostatic interactions induced by domain walls and controls the bias field (H) of the free layer (130)_bias) The size of (2).

According to a modified embodiment, the noble metal spacer layer (152) may similarly be applied to the tunneling magnetoresistance effect using a tunneling barrier layer.

It is expected that the Value of Sensitivity Value along the direction of the magnetic hard axis will be affected in the spin valve structure by various parameters such as (1) the Value of magnetic anisotropy (magnetic anisotropy) of the pinned layer (152) or the exchange bias magnetic field, (2) the Value of magnetic anisotropy or the interlayer exchange coupling field (interlayer exchange coupling field) of the free layer (130), and the like. The value of the sensitivity along the hard axis may be influenced in large part by the value of the interlayer exchange coupling field of the free layer (130).

In the spin valve structure according to example embodiments, a value of an interlayer exchange coupling field of the free layer (130) may depend on an influence of a Stray field (Stray field) of a Ruderman-Kittel-Kasuya-Yosida (RKKY) type exchange coupling (exchange coupling), Neel orange peel coupling (Neel orange peel coupling), or a pinned layer (152). The interlayer exchange coupling field indicates a degree to which a magnetic hysteresis curve occurring when an external magnetic field is applied in a magnetic easy axis (magnetic axis) direction of the free layer (130) deviates from an origin. The interlayer exchange coupling field can be expressed as a bias magnetic field (H) of the free layer (130)_bias)。

According to an example embodiment, the layer expected to have the greatest effect on interlayer exchange coupling of the free layer (130) in the spin valve structure is a metal spacer layer (140) interposed between the free layer (130) and the pinned layer (152).

The metal spacer layer (140) is formed of copper (Cu). When the thickness of the metal spacer layer (140) reaches about 2.2 nm, no Pinhole coupling (Pinhole coupling) due to strong ferromagnetic coupling occurs. Further, the metal spacer layer (140) has a thickness at which a second highest antiferromagnetic coupling occurs according to exchange coupling of the Rudman-Kertel-Cuk-Fangtian (RKKY) type so as to cancel ferromagnetic coupling of the bias magnetic field of the free layer to reduce a value of the bias magnetic field. However, the value of the interlayer exchange coupling constant of the metal spacer layer (140) is small, and when the metal spacer layer (140) has a thickness of 2.2 nanometers, the effect of the antiferromagnetic coupling is significantly lower than the effect of the ferromagnetic coupling caused by the Neel orange peel coupling. Thus, the bias magnetic field of the free layer (130) is much offset from the origin and has a value that favors ferromagnetic coupling.

An effect of magnetostatic interaction effect by a domain wall exists as an extrinsic component acting outside a bias magnetic field of the free layer (130). Magnetostatic interaction forms flux-closure (flux-closure) due to interaction between the Neel domain walls present in the free layer (130) and the pinned layer (152). Magnetostatic interaction is used as a fixture (texture) in the magnetization reversal process of the free layer (130) to disturb the magnetization reversal process. The strength of the magnetostatic interaction can be tuned by the size of the Neel domain walls present in the free (130) and pinned (152) layers, their relative size to each other, the amount or density of magnetic domain walls, and the like.

If the magnitude of the bias magnetic field of the free layer (130) is reduced, the sensitivity characteristic in the magnetic hard direction can be improved, and noise caused by the magnetic easy axis can be suppressed when used as a GMR sensor.

Bias magnetic field (H) of free layer (130)_bias) The Domain wall induced magnetostatic interaction (Domain wall induced magnetostatic interaction) effect can be used for tuning. This effect can be controlled by adjusting the type and thickness of the free layer (130) or pinned layer (152), the thickness of the metal spacer layer (140), the type and thickness of the noble metal spacer layer (154), and the like, on the spin valve structure.

Conventionally affecting the bias magnetic field (H) of the free layer (130)_bias) In reducing the bias magnetic field (H) of the free layer (130) (e.g., RKKY type exchange coupling, Neel orange peel coupling, and stray magnetic field of the pinned layer)_bias) The upper limit. However, the free layer (130) may be made using magnetostatic interaction generated by domain wallsBias magnetic field (H)_bias) More effectively reduced.

Bias magnetic field (H) of free layer (130)_bias) Can be controlled by adjusting the magnitude of the magnetization-reversing magnetic field of the free layer (130), which determines the bias magnetic field (H) of the free layer (130)_bias) And a coercive force. The magnetization reversal of the free layer (130) can be divided into two cases. First, magnetization reversal of the free layer (130) occurs to change the states of the free layer (130) and pinned layer (152) from an anti-parallel state to a parallel state. Second, magnetization reversal of the free layer (130) occurs to change the states of the free layer (130) and pinned layer (152) from a parallel state to an anti-parallel state.

When the magnetostatic interaction generated by the domain wall is used, the magnitude of a magnetic field in which magnetization reversal occurs from the parallel state to the antiparallel state is almost constant, whereas the magnitude of a magnetic field in which magnetization reversal occurs from the antiparallel state to the parallel state may be changed. Therefore, when the magnitude of the magnetic field generated from the parallel state by the anti-parallel state during magnetization reversal of the free layer increases, the magnitude of the bias magnetic field of the free layer may decrease.

Fig. 12A to 12D illustrate magnetization characteristics depending on an external magnetic field in a magnetically easy axis direction of a material in a magnetic device according to an example embodiment of the present disclosure and a thickness of a noble metal spacer layer.

Referring to FIG. 12A, the GMR magnetic device of the spin valve structure includes Ta (5.0 nm)/Ni₈₀Fe₂₀(3.0 nm)/Co₉₀Fe₁₀(1.8 nm)/Cu (2.2 nm)/Co₉₀Fe₁₀(2.0 nm)/noble metal spacer layer/Ir₂₁Mn₇₉(6.0 nm)/Ta (5.0 nm). The noble metal spacer layer (154) may be copper (Cu) or platinum (Pt). The subscripts indicate the thickness in angstroms. The x-axis represents the magnetic field in the auser unit and the y-axis represents the magnetization normalized to the saturation magnetization. An external magnetic field is applied in the direction of the magnetic easy axis of the free layer. GMR magnetic devices exhibit hysteresis characteristics.

w/o is a sample in which no noble metal spacer layer is inserted. Pt₁Cu₀Represents a noble metal spacer layer (154), Pt is represented by 1 angstrom, and Cu is not represented by 0 angstrom. Hysteresis characteristicThe magnetic properties are exhibited near a position where the external magnetic field in the magnetic easy axis direction is zero (0).

When the wheatstone bridge sensor is configured, it is necessary to suppress a signal caused by an external magnetic field (Hx) in the magnetic easy axis direction. In order to suppress a signal caused by an external magnetic field (Hx) in the magnetic easy axis direction, it is necessary to dispose a point (A, B) at which the hysteresis slope is maximum outside the sensor region. Bias magnetic field (H)_bias) It needs to be close to zero, the bias magnetic field being the midpoint between the points (A, B) where the hysteresis slope is greatest.

Referring to FIG. 12B, Pt₁Cu₁Has a wider sensing area than a sample (w/o) in which the noble metal spacer layer (154) is not inserted. Bias magnetic field (H)_bias) Having a minimum value, the bias magnetic field being the midpoint between points a and B where the hysteresis slope is greatest.

Continuing with reference to FIG. 12B, Pt₂Cu₁Has a wider sensing area than a sample (w/o) in which the noble metal spacer layer (154) is not inserted. Bias magnetic field (H)_bias) Has a minimum value, and the bias magnetic field is a midpoint between points (A, B) where the hysteresis slope is greatest.

Referring to FIG. 12C, Cu₂Pt₁Has a wider sensing area than a sample (w/o) in which the noble metal spacer layer (154) is not inserted. Bias magnetic field (H)_bias) Has a minimum value, and the bias magnetic field is a midpoint between points (A, B) where the hysteresis slope is greatest.

Referring to FIG. 12D, Cu₃Pt₂Has a wider sensing area than a sample (w/o) in which the noble metal spacer layer (154) is not inserted. Bias magnetic field (H)_bias) Has a minimum value, and the bias magnetic field is a midpoint between points (A, B) where the hysteresis slope is greatest.

When a noble metal spacer layer (154) is interposed between the antiferromagnetic layer (156) and the pinned layer (152), the magnitude of the free layer magnetization reversal magnetic field is adjusted from the antiparallel state to the parallel state. Therefore, the bias magnetic field (H) of the free layer (130)_bias) Can be reduced. In particular, greater effect may be obtained when using a bilayer than when using a monolayer.

Fig. 13 illustrates magneto-optical kerr effect (MOKE) microscope images and hysteresis characteristics depending on whether a noble metal spacer layer is present in a magnetic device according to an example embodiment of the present disclosure.

Referring to fig. 13, the behavior of a domain wall of a giant magnetoresistance film having a spin valve structure during a magnetization reversal process of a free layer (130) from an anti-parallel state to a parallel state was observed in the range of several to several tens of and a MOKE microscope showing the behavior. The process is shown briefly in the right figure. In fig. 13, (a) to (d) are samples in which the noble metal spacer layer (154) is not inserted, (e) to (h) are samples in which the noble metal spacer layer (154) in the form of a bilayer including a Pt layer having a thickness of 2 angstroms and a Cu layer having a thickness of 1 angstroms is inserted, and (i) to (1) are samples in which the noble metal spacer layer (154) in the form of a bilayer including a Cu layer having a thickness of 3 angstroms and a Pt layer having a thickness of 2 angstroms is inserted. The pinning layer (152) is tightly pinned by an antiferromagnetic layer (156) in the direction of the exchange bias magnetic field. Thus, the density of the free layer (130) is higher than the density of the antiferromagnetic layer (156) because the free layer (130) exhibits single magnetic domain behavior.

Referring to (a) to (d), when the noble metal spacer layer (154) is not inserted, there is no foreign matter in the antiferromagnetic layer (156). Therefore, since the density of the neel magnetic wall is not high, the magnetic flux closure that fixes the migration of the magnetic domain wall in the magnetization reversal process is small. Therefore, the size of the magnetic domain is generally large, and the magnetic domain wall smoothly migrates.

Referring to (e) to (h) and (i) to (l), when the noble metal spacer layer (154) is inserted, the noble metal atoms of the noble metal spacer layer (154) serve as foreign substances in the antiferromagnetic layer (156). Thus, the noble metal spacer layer (154) increases the density of the Neel domain walls, and the increased Neel domain walls in the antiferromagnetic layer (156) form flux closures due to the Neel domain walls in the free layer (130) and the magnetostatic interaction caused by the domain walls. Thus, the noble metal spacer layer (154) acts as a pinning site in the free layer magnetization reversal process from an anti-parallel state to a parallel state. Therefore, the magnitude of the magnetization reversal magnetic field from the antiparallel state to the parallel state of the free layer (130) is increased, so that the bias magnetic field (H)_bias) And decreases.

Fig. 14A to 14D are graphs representing test results showing a magnetoresistance ratio depending on an external magnetic field in a magnetic easy axis direction in a magnetic device according to an example embodiment of the present disclosure.

FIG. 15 is Cu in FIGS. 14A to 14D₃Pt₂The plot of magnetoresistance ratios is magnified below.

Referring to fig. 14A to 14D and fig. 15, a magnetoresistance ratio depending on the presence or absence of the noble metal spacer layer (154) is shown. An external magnetic field (Hx) is applied along the magnetic easy axis direction of the free layer (130). When the noble metal spacer layer (154) is inserted, the magnitude of the magnetization reversal magnetic field of the free layer from the antiparallel state to the parallel state is increased by the magnetostatic interaction effect caused by the Neel magnetic wall. Thus, the resulting bias field (H) of the free layer_bias) And decreases. Further, when the noble metal spacer layer (154) is inserted, the magnitude of the giant magnetoresistance ratio is increased by electron specular scattering (electronic specularization) of electrons on the upper and lower boundaries of the noble metal spacer layer (154).

When the structure of the noble metal spacer layer (154) is Cu₃Pt₂In the case of (2), the magnetoresistance ratio exhibits hysteresis characteristics. The region with rapidly increased magnetoresistance ratio is arranged outside the sensing region (-6 to + 6) centered at 0 DEG, and the bias magnetic field (H)_bias) Is 0.5 ao, close to 0. Therefore, in the wheatstone bridge configuration, a signal generated by the external magnetic field (Hx) in the magnetic easy axis direction can be suppressed. In the wheatstone bridge configuration, only signals generated by an external magnetic field (Hy) in the direction of the hard axis can be measured.

Fig. 16A to 16D are graphs representing test results showing magnetoresistance ratios depending on external magnetic fields in the hard magnetic axis direction in a magnetic device according to an example embodiment of the present disclosure.

Referring to fig. 16A through 16D, magnetoresistance ratios depending on the presence or absence of the noble metal spacer layer (154) are shown. An external magnetic field (Hy) is applied in the direction of the hard axis of the free layer (130). In the range of external magnetic fields from 0 to 10, the slope of the magnetoresistance ratio has a direct effect on the sensitivity (S). Bias magnetic field (H) of free layer (130)_bias) The larger the magnitude of (c), the higher the slope of the magnetoresistance ratio. By passing through magnetic domain wallsThe magnetostatic interaction effect is generated to increase the magnetization reversal field of the free layer from the anti-parallel state to the parallel state. Therefore, even if the coercive force of the free layer (130) is increased, the sensitivity of the GMR element is set to the bias magnetic field (H) of the free layer (130)_bias) And increases when decreasing.

FIG. 17 is a graph illustrating sensitivity (S) and bias magnetic field (H) of a free layer in a magnetic device according to an example embodiment of the present disclosure_bias) A graph of the correlation between.

Referring to FIG. 17, the sensitivity (S) and bias magnetic field (H) of the free layer (130)_bias) Have strong negative correlation with each other. When the noble metal spacer layer (154) is not inserted, a bias magnetic field (H)_bias) It was 5.3 ao and the sensitivity (S) was 6.01 mV/mA.o. When inserting [ Pt ]₂/Cu₁]When the double layer is used as the noble metal spacer layer (154), the bias magnetic field (H)_bias) Was 0.25 ao and the sensitivity (S) was 8.02 mV/mA-ao. When inserting [ Cu ]₃/Pt₂]When the double layer is used as the noble metal spacer layer (154), the bias magnetic field (H)_bias) Was 0.5 ao and the sensitivity (S) was 12.01 mV/mA.o.

FIG. 18 is a cross-sectional view of a magnetic device according to another example embodiment of the present disclosure.

Referring to fig. 18, the magnetic device (200) includes: a pinned layer (152) having an in-plane magnetization direction; a free layer (130) having an in-plane magnetization direction, vertically spaced from the pinned layer (152) to align with the pinned layer (152); a tunneling insulating layer (140) disposed between the pinned layer (152) and the free layer (130); an antiferromagnetic layer (156) disposed to pin a magnetization direction of the pinned layer (152) and vertically spaced from the pinned layer (152) to align with the pinned layer (152); and a noble metal spacer layer (154) disposed between the pinned layer (152) and the antiferromagnetic layer (156). The noble metal spacer layer (154) may be a single layer thin film of copper or platinum, or a multi-layer thin film of copper and platinum, and may have a thickness of 0.1 to 0.8 nanometers. The free layer (130) has shape magnetic anisotropy, and the magnetic device (200) may be connected with a Wheatstone bridge structure.

Metal spacer layer for magnetic devices (100) using the giant magnetoresistance effect in magnetic devices (200) using the tunneling magnetoresistance effect(140) The tunneling insulating layer 240 may be replaced. The electrodes (202a, 202b) may be disposed on a top surface and a bottom surface of the magnetic device (200). In the magnetic device (200), a noble metal spacer layer (154) is inserted to reduce a bias magnetic field (H) in a magnetic easy axis due to an effect similar to that of a giant magnetoresistive element_bias)。

The tunneling insulating layer 240 may be MgO, AlOx, or GdOx. The tunneling insulating layer 240 may have a thickness of a few nanometers (nm).

The noble metal spacer layer (154) is Pt₂Cu₁、Cu₂Pt₁Or Cu₃Pt₂And the subscripts indicate thickness in angstroms.

The pinned layer (154) may be CoFe, and the free layer (130) may include a first ferromagnetic layer (132) of NiFe and a second ferromagnetic layer (134) of CoFe.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.