KR20130010611A - Flexible magnetoresistance sensor and manufacturing method thereof - Google Patents

Abstract

PURPOSE: An organic thin film magnetoresistance sensor and a manufacturing method thereof are provided to increase the sensitivity of a sensor by reducing the thickness of a protection layer. CONSTITUTION: A flexible substrate(20) is made with melt extrusion technology or solvent casting technology and is composed of PC(polycarbonate) substrate, PET(polyethylene terephthalate) substrate, PES(polyethersulfone) substrate, PI(Polyimide) substrate, PEN(Polyethylene Naphthalate) substrate, AryLite substrate or COC substrate. An electrode layer(21) is formed by partially compressing the flexible substrate. A magnetic sensor layer(22) is formed on the electrode layer and the flexible substrate. A protection layer(23) covers a part of the magnetic layer and the entire of the magnetic sensor layer. [Reference numerals] (20) Flexible substrate; (21) Electrode; (22) Magnetic sensor; (23) Protection layer

Description

Flexible thin film magnetoresistance sensor and its manufacturing method {Flexible magnetoresistance sensor and manufacturing method

The present invention relates to a technique for forming a thin film magnetoresistive sensor on a flexible substrate, and more particularly, to a thin film magnetoresistive sensor formed by depositing and patterning a magnetic multilayer thin film on a flexible film and a method of manufacturing the same.

In addition, the term "flexible thin film magnetoresistance sensor" used in the present invention means that the thin film magnetoresistance sensor is formed on a flexible substrate.

In general, the magnetoresistance refers to an electrical resistance or an electrical resistivity that changes when a magnetic field is applied to a magnetic material. The magnetoresistance is divided into anisotropic magnetoresistance, giant magnetoresistance, tunneling magnetoresistance, and supergiant magnetoresis, depending on the type. The magnetoresistive material is made of a magnetic thin film of nano-thickness, and the magnetoresistance property is maintained even in the nano-sized shape, thus making it possible to manufacture a micro low-power magnetic field sensor. In addition, the output can be converted into a voltage signal from the change of the electric resistance according to the strength of the magnetic field, so it is not only possible to detect the ultra-fine magnetic field but also the change of the resistance makes the AC frequency characteristic excellent. It is possible. Therefore, the magnetoresistance phenomenon is used for a head of a hard disk, a magnetic field sensor, a biosensor, a direction sensor, a low frequency eddy current sensor for nondestructive testing, and a high speed magnetoresistance RAM.

The degree of change in resistance (ΔR) according to the strength of the magnetic field of the magnetoresistive material is referred to as the magnetoresistance ratio (MR (%)), and expressed as a percentage (%) as MR (%) = ΔR / Rx100.

Anisotropic magnetoresistance is a phenomenon that occurs in a single magnetic layer. The anisotropic magnetoresistance is dependent on the angle between the direction of the current and the magnetization. The magnetoresistance is about 2 to 5% at room temperature.

The large magnetoresistance with ferromagnetic-metal-ferromagnetic structure depends on the angle between the magnetization directions of the two ferromagnetic layers and is independent of the direction of the current. That is, the current causes resistance change by spin scattering depending on the magnetization direction of the two ferromagnetic layers. When the magnetization directions of the two ferromagnetic layers are parallel, the resistance is the smallest and the resistance is the maximum when the magnetization directions of the two ferromagnetic layers are anti-equilibrium. do. In the case of such a giant magnetoresistance, the magnetoresistance ratio is about 10-50%.

Tunneling magnetoresistance with ferromagnetic-insulator-ferromagnetic structures also depends on the angle between the magnetization directions of the two ferromagnetic layers and is independent of the direction of the current. In other words, the current flowing through tunneling the insulator between two ferromagnetic materials causes a change in resistance by spin scattering depending on the magnetization direction of the two ferromagnetic layers. At this anti-equilibrium, the resistance is maximum. In the case of the tunneling magnetoresistance, a material having a magnetoresistance ratio of more than 500% has already been developed, and the ultra-large magnetoresistance expects a magnetoresistance ratio of 1000% or more.

In the case of using a magnetoresistive material as the magnetic sensor, the output signal is proportional to the magnetoresistance ratio. Therefore, in order to improve the sensitivity by increasing the output characteristics according to the strength of the magnetic field, the magnetoresistance ratio is large and the linearity of the output signal according to the strength of the magnetic field must be secured. However, a large magnetoresistance material or a tunneling magnetoresistance material has an advantage of increasing output signal characteristics due to a large magnetoresistance ratio, but has a disadvantage of poor linearity.

Therefore, these large magnetoresistance materials and tunneling magnetoresistance materials are used for heads or low-resistance memory elements that detect signals from hard disks that do not require linearity guarantee by using excellent signal characteristics. However, when a large magnetoresistance material or a tunneling magnetoresistance material is used as a magnetic sensor, an area where linearity is secured is distributed over a predetermined magnetic field region. Therefore, the offset voltage of the output signal must be removed while a predetermined magnetic field is applied externally. However, there is a disadvantage that the structure of the magnetic sensor is complicated and the sensitivity is deteriorated by these additional devices.

On the other hand, the anisotropic magnetoresistance material has a smaller magnetoresistance ratio than the giant magnetoresistance material or the tunneling magnetoresistance material, but the linearity of the output signal according to the strength of the magnetic field is excellent. In addition, it is possible to adjust the direction of the current by changing the shape structure of the magnetic sensor based on the principle of the magnetoresistance characteristic in which the output signal characteristic of the magnetic sensor depends on the direction of the current and the direction of magnetization. And it is possible in principle to improve the sensitivity, which is a measure of measuring the magnetic field by increasing the output signal characteristics of the magnetic sensor by improving the magnetoresistance ratio characteristics of the material.

Magnetic sensors that detect magnetic fields using the principle of anisotropic magnetoresistance are generally anisotropic magneto-resistance (AMR) sensors and planar hall resistance (PHR) sensors using the planar hole effect. Are classified. In the anisotropic magnetoresistive sensor, the direction of the voltage measurement and the direction of the flowing current are parallel to each other to measure the voltage due to the magnetoresistance caused by the magnetic field.In the planar Hall resistance sensor, the direction of the voltage measurement and the direction of the flowing current are perpendicular to each other. do. That is, the magnetoresistance is measured using the voltage generated by the plane hole effect in which the flowing measurement current is affected by the external magnetic field.

A magnetic sensor using only anisotropic magnetoresistance or planar hole characteristics uses a single ferromagnetic thin film layer, and such a magnetic sensor may cause an inversion of the output signal due to the hysteresis characteristic of the magnetoresistance when a strong magnetic field is applied from the outside. In order to complement the characteristics, a driving device for stabilizing an output signal by aligning magnetic domains in one direction by applying a strong magnetic field to the magnetic thin film layer during initial driving has been added.

In addition, since the range of the magnetic field that can be measured when using a single ferromagnetic layer is limited to the strength of the anisotropic magnetic field of the magnetic layer, for example, when using a NiFe thin film, the measurement range is limited to a magnetic field range of about 50 Oe. Therefore, it is impossible to measure the micro magnetic field which is changed under the magnetic field above (H> 5 Oe for NiFe). Therefore, if an anisotropic magnetoresistive sensor using a NiFe single layer is used to measure the earth's magnetic field in the mobile phone, the earth's magnetic field cannot be measured because of the internal magnetic field of 5-10Oe generated in the internal circuit of the mobile phone.

The anisotropic magnetoresistive sensor decreases the signal characteristics when the resistance of the sensor decreases. Therefore, when the size of the sensor is reduced to measure the magnetic bit of the micro size, the signal decreases. As a biosensor for micro magnetic bead measurement, There is a limit to using. Therefore, a magnetic sensor using a planar hall characteristic having an output signal irrespective of the size of the sensor is used as a biosensor for measuring micro magnetic beads.

Since the anisotropic magnetoresistance or planar hole characteristic depends on the direction of the current and the direction of the magnetic domain, it is possible to adjust both characteristics by changing the shape of the magnetic sensor. Since the properties can be improved, the bead detection capability of the microsensor bead measuring biosensor can be improved. When the exchange coupling force is attached to the ferromagnetic layer, the magnetic field measurement range can be adjusted and the magnetic history characteristics can be removed. It can be used as a magnetic sensor or a direction sensor used in a mobile phone or an electronic device because it is manufactured with a micro sensor of low power and low power type.

The following patent document 1-4 discloses the manufacturing method of a magnetic sensor as mentioned above.

The magnetic sensor as described above, as shown in Figure 1, to produce a sensor using a Si substrate or a glass substrate. That is, a magnetic sensor is manufactured by raising a magnetic sensor and an electrode on a Si substrate or a glass substrate and applying a protective layer.

The sensor shown in FIG. 1 forms the magnetic sensor 11 on the Si substrate or the glass substrate 10, and then forms the electrode layer 12 on the Si substrate or the glass substrate 10 and the magnetic sensor 11. . Thereafter, a protective layer 13 for protecting a part of the magnetic sensor 11 and the electrode layer 12 is formed.

Therefore, the conventional magnetic sensor as shown in FIG. 1 has a problem that the thickness of the protective layer is inevitably increased due to a step difference caused by the electrode because the electrode of the sensor is about 200nm.

In addition, the magnetic sensor produced as described above is inflexible, the application field is limited.

) Republic of Korea Patent Publication No. 2009-0049721 (published May 19, 2009) ) Republic of Korea Patent Publication 2008-0100900 (2008.11.21 published) ) Republic of Korea Patent Publication 1999-0083593 (published on November 25, 1999) US Patent Publication 20060006864 (published Jan. 12, 2006)

An object of the present invention is to solve the problems described above, to provide a flexible thin film magnetoresistance sensor having both anisotropic magnetoresistance characteristics and planar Hall resistance characteristics, and having a flexibility and a method of manufacturing the same.

Another object of the present invention is to provide a flexible thin film magnetoresistive sensor and a method of manufacturing the same, which reduces the thickness of the magnetoresistive sensor to increase the sensitivity of the sensor.

In order to achieve the above object, the flexible thin film magnetoresistive sensor includes a flexible substrate, an electrode layer provided on the flexible substrate, a magnetic sensor layer formed on the flexible substrate and the electrode layer, a part of the magnetic layer, and all of the magnetic sensor layers. It is characterized by including a protective layer covering.

In the flexible thin film magnetoresistive sensor according to the present invention, the flexible substrate is a film (PC) substrate, a PET (polyethylene terephthalate) substrate, a PES (polyethersulfone) substrate, a PI (Polyimide) substrate, PEN (polyethylene naphthalate) A substrate, an AryLite substrate, or a COC (cyclic olefin copolymer) substrate.

In the flexible thin film magnetoresistive sensor according to the present invention, the magnetic sensor layer is a magnetic layer having a closed loop shape, and the electrode layer is in contact with the closed loop to face each other, and a pair of currents are input / output. A current terminal and a pair of voltage terminals which are in contact with the closed loop facing each other, detects the output voltage.

In the flexible thin film magnetoresistive sensor according to the present invention, the magnetic sensor layer is formed in the closed loop in the same shape as the closed loop, spaced apart from the closed loop by a predetermined distance, and has a magnetic layer in the shape of the closed loop. It characterized in that it comprises a second magnetic layer made of the same material as.

In the flexible thin film magnetoresistive sensor according to the present invention, the magnetic sensor layer may be a magnetic layer having a polygonal structure, a circular structure or a cross structure.

In the flexible thin film magnetoresistance sensor according to the present invention, the flexible thin film magnetoresistance sensor may be a magnetic field sensor, a bio sensor, a permeability sensor, an eddy current sensor for nondestructive inspection, a magnetic field imaging sensor, or a NMR (nuclear magnetic resonance) sensor. do.

In addition, in order to achieve the above object, a method of manufacturing a flexible thin film magnetoresistive sensor according to the present invention includes the steps of preparing a flexible substrate, forming an electrode layer on the flexible substrate, and forming a magnetic sensor layer on the flexible substrate and the electrode layer. And forming a protective layer covering a part of the magnetic layer and all of the magnetic sensor layer, wherein the electrode layer is formed by partially compressing the flexible substrate.

In the method for manufacturing a flexible thin film magnetoresistive sensor according to the present invention, the magnetic sensor layer is formed on the same plane of the flexible substrate and the electrode layer.

In the method for manufacturing a flexible thin film magnetoresistive sensor according to the present invention, the flexible substrate is a film (PC) substrate, a PET (polyethylene terephthalate) substrate, a PES (polyethersulfone) substrate, a PI (Polyimide) substrate, PEN (Polyethylene Naphthalate) substrate, an AryLite substrate, or a COC (cyclic olefin copolymer) substrate.

In the method of manufacturing a flexible thin film magnetoresistive sensor according to the present invention, the magnetic sensor layer is a magnetic multilayer film of an antiferromagnetic layer (AM layer) -ferromagnetic layer (FM layer), characterized in that formed by a DC magnetron sputter. do.

As described above, according to the flexible thin film magnetoresistive sensor and the manufacturing method thereof according to the present invention, since the sensor can be formed on a flexible substrate, for example, the effect can be easily applied to a measurement object made of a curved surface. Obtained.

In addition, according to the flexible thin film magnetoresistive sensor and the manufacturing method thereof according to the present invention, since the thickness of the protective layer can be reduced during the production of the magnetic sensor, the effect of increasing the sensitivity of the sensor is obtained.

In addition, according to the flexible thin film magnetoresistive sensor and the manufacturing method thereof according to the present invention, since the substrate on which the sensor is formed has flexibility, an effect that can be easily mounted on an existing measurement object is also obtained.

1 is a view for explaining a manufacturing process of a conventional magnetic sensor,
2 is a view showing an example of a magnetic sensor applied as an example of the present invention;
3 is a view showing another example of a magnetic sensor applied as an example of the present invention;
4 is a view showing an operation example of a magnetic sensor applied as an example of the present invention;
5 is a view for explaining a manufacturing process of the magnetic sensor according to the present invention;
6 is a view showing a hysteresis curve and a magnetoresistance change using a PEN film as a flexible substrate;
7 is a view showing the surface roughness of the magnetic multilayer thin film using the PEN film of FIG.
8 is a photograph showing a flexible biochip sensor manufactured on a flexible substrate according to the present invention,
9 is a view showing the PHR sensor fabrication and signal characteristics results on the PEN film,
10 is a view showing a signal change due to an external stress of the PEN sensor,
11 is a view showing a surface roughness irradiation result after depositing a magnetic thin film on a conventional Si substrate and the PEN substrate of the present invention.

These and other objects and novel features of the present invention will become more apparent from the description of the present specification and the accompanying drawings.

First, the structure of the magnetic sensor to which the present invention is applied will be described.

The magnetic sensor according to the present invention can sense the size and change of magnetic field sensitively with high sensitivity by using both anisotropic magnetoresistance (AMR) and planar Hall resistance (PHR) characteristics according to the strength of the magnetic field, the same structure It is effective to have both characteristics of planar Hall resistance sensor using only planar Hall resistance characteristics or anisotropic magnetoresistance sensor using only anisotropic magnetoresistance characteristics.

The magnetic sensor according to the present invention has a simple structure consisting of a closed loop magnetic layer and four terminals, which is easy to manufacture and mass-produced, and employs lithography and thin film deposition techniques commonly used in semiconductor processes. It is possible to manufacture the pattern of the micro closed loop, so that the microminiaturization is possible, and the resistance characteristic is used, so that it is easy to integrate with other devices or circuits.

In addition, the closed-loop magnetic layer applied to the present invention has a circumference as the r / w ratio of the closed loop (r / radius of the loop and w / width) increases. The anisotropic magnetic field in the direction increases to increase hysteresis characteristics and decrease the sensitivity.However, in the case of the shape pattern of the closed loop, the same magnetic layer is placed inside or outside and the magnetic layer is induced in these inner or outer magnetic layers and the magnetic layer of the closed loop. Interaction with the stabilized magnetization of the closed loop improves hysteresis and sensitivity due to the shape anisotropy of the closed loop.

In addition, in the above description, the magnetic layer of the ring-type closed loop has been described as a structure combining the phenomenon of anisotropic magnetoresistance and plane hole magnetoresistance, but the flexible substrate magnetoresistive sensor according to the present invention has a rectangular structure, a circular shape, It is possible to realize other phenomena such as giant magnetoresistance phenomenon by forming in cross shape.

Next, an example of the structure of the magnetic sensor applied to the present invention as described above will be described with reference to FIGS.

2 shows an example of a magnetic sensor applied to the present invention, FIG. 3 shows another example of the magnetic sensor applied to the present invention, and FIG. 4 shows an operation example of the magnetic sensor applied to the present invention. It is shown.

 As shown in FIGS. 2 to 4, the magnetic sensor applied to the present invention includes a closed loop magnetic layer 110, a pair of current terminals 121 and 122 and a sensor for current input / output. A pair of voltage terminals 131 and 132 for measuring the output voltage of the. On the other hand, as shown in Figure 3, it may be configured to include a magnetic layer (211 ~ 214) of the inner 210 or the outer separated from the closed loop.

The magnetic layer 110 of the closed loop is characterized in that the closed loop shape is connected to both ends of the strip having a constant width (w of Figure 4), circular closed loop (Fig. 2 (a)), elliptical closed loop (Fig. 2 (b) or a polygonal closed loop (FIG. 2C).

As described above, the magnetic sensor applied as an example of the present invention includes a magnetic layer having a closed loop shape, a magnetic layer inside or outside the closed loop separated from an input terminal and an output terminal of the closed loop, a pair of current terminals, and a pair. Anisotropic magnetoresistance (AMR) and planar Hall resistance (PHR) of the magnetic layer 110, which are resistances that change according to the change in the strength of the magnetic field, are measured by the output signal of the sensor (a pair of voltage terminals). Voltage).

Preferably, the magnetic layer 110 is a circular closed loop as shown in FIG. The magnetic sensor having a circular closed loop shape provides an exchange coupling force to the ferromagnetic layers constituting the magnetic layer 110, thereby removing hysteresis characteristics of the output voltage, excellent linearity of the output voltage with respect to the magnetic field, and increasing strength of the exchange coupling force. By adjusting, the magnetic field can be detected in a wide range from mT to pT. In addition, the magnetic layer 110 of the circular closed loop has an advantage that it is easy to form a pattern using lithography, so that a micro-sensor having a nano or micro order size can be manufactured.

The structural features of the magnetic layer 110 of the circular closed loop as described above will be described in more detail as follows.

The magnetic layer 110 having a circular closed loop shape applied as an example of the present invention is characterized by a closed loop shape in which both ends of a band having a central radius R and a predetermined width w are connected, and anisotropic magnetoresistance (AMR). ) And planar Hall resistance (PHR) both contribute to the output signal of the sensor (voltage measured through a pair of voltage terminals), the range of r / w is characterized by more than 0.5, substantially 0.5 to 10000. At this time, if the r / w of the circular closed loop increases, the demagnetization factor in the circumferential direction increases due to the shape of the magnetic layer, thereby forming a domain according to the strength of the magnetic field, and It causes the hysteresis characteristic. In this case, a magnetic layer of the same material as the closed loop is placed inside the closed loop 210 and / or outside 211 to 214 so as to be separated from the closed loop (and a pair of voltage terminals and a pair of current terminals). By reducing the magnetic anisotropy factor of the closed loop by the interaction between the magnetic field induced in the inner or outer magnetic layer separated from the magnetic layer and the magnetic layer of the closed loop, the magnetic domain formation of the closed loop is eliminated and the rotation of the magnetization contributes to the output signal. Stabilizing the output characteristics, and improves the hysteresis characteristics and sensitivity characteristics.

The magnetic layer (second magnetic layer 210) provided in the closed loop 110 spaced apart from the closed loop by a predetermined distance has a concentric structure with the closed loop 110 and preferably has a shape similar to the closed loop. That is, the magnetic layer (second magnetic layer 210) provided in the closed loop 110 may have a circular, elliptical or polygonal shape corresponding to the shape of the closed loop, and may be spaced apart from the closed loop by a predetermined distance and have the same shape.

Each of the magnetic layers (third magnetic layers 211 to 214) provided outside the closed loop 110 at a predetermined distance from the closed loop, the pair of voltage terminals, and the pair of current terminals are vertically and horizontally symmetrical in structure. Preferably, when the air gap for the separation between the closed loop, the pair of voltage terminals and the pair of current terminals is not considered, the overall shape is square (Fig. 3 (b)) or circular (Fig. 3). It is preferable to have (c)).

In order to stabilize the output characteristics by reducing the shape anisotropy factor of the closed loop and to contribute to the output signal through the rotation of the magnetization, it is provided inside the closed loop to stabilize the hysteresis characteristics and the sensitivity characteristics. The separation distance between the magnetic layer 210 and the closed loop, and the separation distance between the magnetic layers 211 ˜ 214 and the closed loop, the pair of voltage terminals, and the pair of current terminals provided outside the closed loop are 50. It is preferable that it is nm-0.5 mm.

As shown in FIG. 4, a magnetic sensor applied as an example of the present invention is a pair of inputting a direct current, an alternating current, or a pulsed current I _in to the magnetic layer 110 that is a circular closed loop and providing a current movement path. And a pair of voltage terminals 131 and 132 for measuring a direct current, alternating current, or pulsed output voltage V _out , which is an output signal of a sensor to a magnetic field change. It is composed.

The pair of current terminals 121 and 122 are in contact with the magnetic layer 110 which is the closed loop and are provided such that the two current terminals 121 and 122 face each other, and the pair of voltage terminals 131 and 132 are also In contact with the magnetic layer 110 which is a closed loop, the two voltage terminals 131 and 132 are provided to face each other.

In detail, as shown in FIG. 4, when the current terminals 121 and 122 and the voltage terminals 131 and 132 are in contact with the outer circumferential surface of the closed loop 110, AMR and PHR of the magnetic layer forming the closed loop, respectively The characteristic is optimized so that the output voltage characteristic is maximized, and it is preferable that the current terminals 121 and 122 or the voltage terminals 131 and 132 do not overlap the closed loop 110. .

That is, the extension lines of the pair of current terminals 121 and 122 facing each other and the extension lines of the pair of voltage terminals 131 and 132 facing each other are perpendicular to each other, along the outer circumferential surface of the closed loop 110. And the current terminal 121-the voltage terminal 131-the opposite current terminal 122-the opposing voltage terminal 132, alternate with respect to the center of the closed loop 110 (O in FIG. 3) The terminal is characterized by having an angle of 90 degrees.

In this case, as shown in FIG. 4, the current terminals 121 and 122 are connected to an external current source I to input a current to the magnetic layer 110, and the voltage terminals 131 and 132 are connected to an external source. It is connected to the voltage measuring device (V) and outputs a potential difference between two voltage terminals.

As described above, one end of each of the current terminals 121 and 122 and the voltage terminals 131 and 132 is in contact with the magnetic layer 110, and the other end thereof is the current source I or the voltage measuring device (V). The current terminals 121 and 122 and the voltage terminals 131 and 132 provide a low impedance path between the external device and the magnetic layer 110 to apply external current without loss and to lose the output signal of the sensor. Since it is to output without, it can be formed using a conventional electrode or wiring material.

In terms of minimizing contact resistance and surface resistance, the current terminals 121 and 122 and the voltage terminals 131 and 132 are preferably nonmagnetic metal materials having a small specific resistance.

As described above, the magnetic sensor applied as an example of the present invention has a characteristic of detecting a magnetic field by using both anisotropic magnetoresistance characteristics and planar hole resistance characteristics of the magnetic layer. Accordingly, as shown in FIG. Voltage and plane Hall resistance due to anisotropic magnetoresistance that contributes to the output signal of the sensor by controlling the ratio of the center radius of the closed loop 110 (r of FIG. 4) to the width of the closed loop 110 (w of FIG. 4). It is to control the relative ratio of voltage by.

That is, as shown in FIG. 4, when the magnetic layer 110 has a large r / w, the output signal of the sensor is mainly a voltage signal due to anisotropic magnetoresistance, and is similar to a magnetoresistive sensor using only anisotropic magnetoresistance characteristics. With characteristics. In addition, as shown in FIG. 4, when the magnetic layer 110 has a small r / w, the output of the sensor mainly has a voltage due to the planar Hall resistance, and thus has a sensor characteristic similar to that of a Hall sensor using only the planar Hall resistance characteristic. do.

In the present invention, the output voltage V _out of the magnetic sensor is the sum of the voltage due to the anisotropic magnetoresistance and the voltage due to the planar Hall resistance. In the structure according to the present invention having the structure and 90˚ angle between each of the terminals of the magnetic layer 110 of the circular closed loop, so the maximum voltage (V △ _AMR) by the anisotropic magneto-resistance is dependent on the resistance in accordance with the r / w becomes different, the voltage plane by a Hall resistance (△ V _PHR) it is not dependent on so dependent on the material properties of the magnetic layer (110) size.

In consideration of the field of application of the magnetic sensor applied to the present invention, such as a magnetic field sensor, a biosensor, a direction sensor, an eddy current detection sensor, the r / w, the material and the laminated structure of the magnetic layer, and the center radius R of the per loop can be determined. , At this time, the radius of the closed loop (R) may be a nanometer order (order) to millimeter order (order), the magnetic sensor of the present invention is not limited by the size.

In the magnetic sensor of the present invention that detects a magnetic field using both the anisotropic magnetoresistance property and the planar Hall resistance property of the magnetic layer, the magnetic layer has an exchange coupling force in order to remove the ferromagnetic material and hysteresis characteristic of large change in anisotropic magnetoresistance. Any composite thin film laminate structure including an antiferromagnetic layer or the like can be used.

In detail, the magnetic layer provided in the magnetic sensor according to the present invention includes a ferromagnetic thin film, and at least one thin film selected from an antiferromagnetic thin film, an insulator thin film, a nonmagnetic thin film and a metal thin film and the ferromagnetic thin film The laminated multilayer thin film is a magnetic layer in which an output signal having a low peak and a high peak during magnetic field sweep (magnetic field intensity sweep) is obtained.

For example, the magnetic layer may include a laminated thin film structure of a ferromagnetic thin film-antiferromagnetic thin film, a laminated thin film structure of a ferromagnetic thin film-metal thin film-antiferromagnetic thin film, a laminated thin film structure of a ferromagnetic thin film-metal thin film-ferromagnetic thin film, and a ferromagnetic thin film (I). It is a multilayer thin film comprising at least one of an insulator thin film-ferromagnetic thin film (II) laminated structure or a ferromagnetic thin film (I) -metal thin film-ferromagnetic thin film (II) -antiferromagnetic thin film structure. Not magnetic layer.

In addition, in the magnetic sensor applied to the present invention, the magnetic layer 110 is preferably a laminated thin film of a ferromagnetic thin film-antiferromagnetic thin film structure having exchange coupling force so that the range of the magnetic field to be measured can be easily controlled. In this case, the range of the magnetic field to be measured is controlled by using the strength of the exchange coupling force according to the thickness of the ferromagnetic thin film.

)를 보이는 NiFe 또는 NiCo 합금인 것이 보다 바람직하다. The ferromagnetic thin film is a ferromagnetic, oxide magnetic or half-metal thin film, and in detail, it is preferable that the ferromagnetic material is an alloy of one or more materials selected from Ni, Fe, and Co. (

It is more preferable that it is NiFe or NiCo alloy which shows).

)과, 분극률(

)에 비례한다(

). 따라서 분극율이 큰 재료를 강자성 박막으로 사용이 가능하며, 분극율이 100%인(

=0) 반금속(half-metal)을 강자성 박막으로 사용하는 것도 바람직하다. 또한 자기저항변화는 재료의 저항(

) 및 자기저항비에 비례하므로(

) 저항이 큰 산화물 자성재료를 사용하는 것도 바람직하다.The change of magnetoresistance of ferromagnetic material is influenced by spin-orbit scattering

) And polarization rate (

Is proportional to

). Therefore, a material with a large polarization rate can be used as a ferromagnetic thin film, and the polarization rate is 100% (

= 0) It is also preferable to use a half-metal as a ferromagnetic thin film. In addition, the change in magnetoresistance is the resistance of the material (

) And the magnetoresistance ratio

It is also preferable to use an oxide magnetic material having high resistance.

The antiferromagnetic thin film causes exchange coupling force by the interfacial effect of the ferromagnetic thin film. As the antiferromagnetic thin film material, Mn-based material having a large exchange coupling force is used. The Mn-based antiferromagnetic material is preferably IrMn in terms of thermal stability and low temperature process, and in view of improving output signal characteristics, it is preferable that the Mn-based antiferromagnetic material is a transition metal oxide having an insulator and antiferromagnetic properties as an oxide material. Includes NiO or FeO.

In this case, the laminated thin film may further include one or more underlayers for promoting bonding with the substrate, the crystal direction of the magnetic layer, and crystallization. For example, NiFe, which is a ferromagnetic thin film, and IrMn, which is an antiferromagnetic thin film, may be used. In the above, the underlayer is preferably Ta.

In addition, the magnetic layer 110, a pair of current terminals 121 and 122, and a pair of voltage terminals 131 and 132 may be formed on a non-conductive substrate for physical support, and the non-conductive substrate may be magnetic. It includes a flexible substrate having no.

The magnetic layer 110 may be formed using sputtering, molecular beam deposition (MBE), organometallic chemical vapor deposition (MOCVD) or electroplating, and the closed loop 110, the terminals 121, 122, 131 and 132 and the magnetic layers 210 and 211 to 214 inside and outside the closed loop may be formed by applying photoresist to the substrate and patterning them through lithography exposing and developing using a mask. .

In addition, the three magnetic sensors according to the present invention can be used in the small three-axis magnetic field sensor by arranging in the three-axis direction of x, y, z, and by placing two magnetic sensors of the present invention on the xy plane, the x, y-axis magnetic field When using the 3-axis magnetic field sensor that measures the magnetic field in the z-axis direction perpendicular to the xy plane using the Hall sensor using the Hall effect of the semiconductor, the volume of the 3-axis magnetic field sensor can be minimized. It can be used for electronic devices such as mobile phones and parts requiring ultra-low power three-axis magnetic field direction sensor.

Since the magnetic sensor applied to the present invention can be miniaturized, it can be used as a biosensor for measuring magnetic beads having a nano or micro order size. Magnetic beads use superparamagnetic materials so that very small stray magnetic fields increase with the strength of the externally applied magnetic field. Therefore, an external magnetic field is applied to measure the micro stray field of the magnetic beads which are then induced. In this case, since the magnetic sensor is measured by mixing a signal from an externally applied magnetic field and a signal from the micro stray magnetic field, there is a limit in extracting only the influence from the micro stray magnetic field. Therefore, by using the current driving characteristics of the magnetic sensor applied to the present invention using a metallic magnetic material, there is an advantage that can improve the measurement performance of the magnetic beads. That is, the driving current of the direct current or alternating current flowing through the closed loop forms a direct current or alternating magnetic field around the closed loop, and this magnetic field acts to magnetize the magnetic beads located near the closed loop to form the direct and alternating stray magnetic fields. . At this time, the strength of the driving current has the effect of improving the signal characteristics of the magnetic sensor as well as the strength of the stray magnetic field.Because the driving current itself is applied without applying an external magnetic field, it is possible to detect only the micro stray magnetic field of the magnetic bead. There is an advantage to enabling the sensor.

Magnetic sensor applied to the present invention can measure the permeability (permeability) according to the frequency of the magnetic thin film or magnetic material located on the closed loop using its own magnetic field by the AC drive current. The magnetic sensor applied to the present invention uses a magnetoresistance characteristic, and the measurement frequency f ranges from a direct current (f = 0) to a ferromagnetic resonance frequency (f = GHz band) of the magnetic layer, and thus a permeability sensor using a coil. Compared with the low frequency characteristic, a wideband permeability sensor is possible.

The magnetic sensor applied to the present invention has an effect of overcoming the detectable defect size and the low frequency limit of the coil sensor, which is conventionally used as an eddy current sensor in nondestructive inspection because of its excellent miniaturization and low frequency characteristics. Therefore, there is an advantage that a non-destructive inspection eddy current sensor capable of detecting a micro-order size defect present in the thick film in a thick metal thick film such as a gas pipeline is possible.

In addition, the magnetic sensor applied to the present invention has excellent sensitivity and can be used as a resonance signal measuring sensor of a nuclear magnetic resonance device (NMR). Conventional high magnetic field (H ~ T order) NMR devices use a coil sensor because the number of nuclear magnetic resonance frequencies is 100MHz order, and ultra low magnetic field (H = μT order) NMR devices have low resonance frequency and small signal, so the resolution of fT Low frequency AC SQUID device is used. Therefore, the magnetic field sensor according to the present invention, which is capable of detecting a wideband magnetic field in the pT range, can be used in a middle magnetic field (μT <H <T) NMR apparatus.

In addition, the magnetic sensor applied to the present invention can improve the magnetic bead detection ability by using an array type biosensor composed of sensors in an array, and the array sensor can be used as a two-dimensional or three-dimensional magnetic field imaging sensor. It is possible.

Next, the manufacturing process of the magnetic sensor as described above will be described with reference to FIG.

5 is a view for explaining the manufacturing process of the magnetic sensor according to the present invention.

A flexible biochip sensor is described as an example by depositing and patterning a magnetic multilayer thin film such as NiFe / IrMn or NiFe / Cu / IrMn on a flexible substrate, for example, a polyethylene naphthalate (PEN) film, but is not limited thereto.

First, the flexible substrate 20 is prepared. As the flexible substrate 20, when the electrode layer 21 is formed, it is preferable to use one in which the flexible substrate 20 itself can be compressed.

Accordingly, the flexible substrate 20 is produced by a melt extrusion technology or a solvent casting technology, for example, a PC (polycarbonate) substrate having excellent optical and mechanical properties, meltability at a relatively low temperature Polyethylene terephthalate (PET) substrate, polyethersulfone (PES) substrate, polyimide (PI) substrate with strong heat and chemical resistance, polyethylene naphthalate (PEN) substrate with optical anisotropy, optically developed by Ferrania Image System of Italy As the substrate, an AryLite substrate or a COC (cyclic olefin copolymer) substrate having excellent thermal, optical and chemical properties can be used. That is, the flexible substrate 20 applied to the present invention may use any one of the substrates described above according to the application target of the magnetic sensor.

Next, the output voltage of the sensor and the pair of current terminals 121 and 122 for current input / output as shown in FIG. 3 or 4 are measured on the flexible substrate 20 as described above. A pair of electrode layers 21 for the voltage terminals 131 and 132 are formed. In this case, the electrode layer 21 is formed by partially compressing the flexible substrate 20, and as shown in FIG. 5, the planes of the portion where the electrode layer 21 is formed and the remaining portions of the flexible substrate 20 are substantially coplanar. Is achieved. On the other hand, the conditions for compressing the electrode layer 21 and the flexible substrate 20 to form the same plane can be changed depending on the material and thickness of the flexible substrate 20 is not particularly limited.

Next, the magnetic sensor layer 22 is formed on the electrode layer 21 and the flexible substrate 20.

Thereafter, a protective layer 23 covering a part of the magnetic layer 21 and the entirety of the magnetic sensor layer 22 is formed.

Therefore, the magnetic sensor according to the present invention can be miniaturized by reducing the thickness of the protective layer 23, as can be seen in comparison with FIG.

That is, in the process using the flexible substrate 20, first, the electrode of the sensor is partially compressed by manufacturing the electrode layer 21 by partially compressing the flexible substrate 20 of the electrode part using a nanoimprinting technique, and then a protective layer by manufacturing a magnetic sensor. The thickness of 23 can be reduced. When the magnetic sensor is used as a biosensor, for example, the sensitivity of the sensor may be always increased by reducing the thickness of the protective layer 23.

In other words, a magnetic multi-layer thin film of an antiferromagnetic layer (AM layer) -ferromagnetic layer (FM layer) is deposited on a PEN film, for example, a flexible substrate 20, using a DC magnetron sputter system, and patterned to be flexible biochip. Sensors can be manufactured.

In the characteristic description of the flexible thin film magnetoresistive sensor manufactured as described above, the case where the PEN film is applied to the flexible substrate 20 will be described, but is not limited thereto.

First, before the sensor performance test according to the present invention, an antiferromagnetic layer (AM layer) and a ferromagnetic layer (FM layer) were deposited on a PEN film to measure magnetic properties and surface roughness. The result is as shown in FIG. FIG. 6 is a diagram showing magnet hysteresis curve and magnetoresistance change using a PEN film as the flexible substrate 20.

Figure 6 (a) shows the magnetization history curve of the thin film using a Virating Sample Magnetometer (VSM), Figure 6 (b) shows a change in magnetoresistance. The interaction between the antiferromagnetic and ferromagnetic layers shifts the center of the hysteresis phenomenon by the exchange bias field (Hex) so that H = 0. The exchange field (Hex) using PEN film is 120Oe, which shows the same results as a general silicon wafer. The magnetoresistance measurement shows 0.55% change in magnetoresistance.

Next, the surface roughness of the AM-FM magnetic thin film deposited on the PEN film using an AFM (Atomic Force Microscope) was investigated. The result was that the surface roughness was 3.3 nm, as shown in FIG. 7 is a view showing the surface roughness of the magnetic multilayer thin film using the PEN film of FIG.

A flat Hall effect (PHR) sensor was manufactured using the thin film measured in FIG. 7 to manufacture a chrome mask using the diagram of FIG. 8, and a sensor was manufactured using an etching process (photolithography). 8 is a photograph showing a flexible biochip sensor manufactured on a flexible substrate according to the present invention.

In particular, the electrode of the sensor, as shown in Figure 9, was manufactured to be inserted into the ready-made connector, and used to measure the signal without hysteresis (hysteresis). 9 is a view illustrating a PHR sensor fabrication and signal characteristic results on a PEN film.

In order to analyze the signal change caused by the stress of the sensor fabricated on the flexible PEN film, an external stress was applied to the sensor, and then the signal was measured as shown in FIG. 10. 10 is a diagram illustrating a signal change caused by external stress of the PEN sensor.

When the sensor was bent at 20 degrees and 45 degrees, as shown in FIG. 10, there was a slight signal change (expected to be a change in signal when the height of the sensor was detected), but no hysteresis occurred. When the stress (sensor deflection) was removed, the sensor signal was returned to the origin again.

Next, after the magnetic thin film was deposited on the Si substrate and the PEN substrate, surface roughness was observed using an AFM (atomic force microscope). As shown in FIG. 11A, the RMS roughness 0.18 A characteristic of ˜0.22 nm was obtained, and in the case of the PEN substrate according to the present invention, as shown in FIG. 11 (b), RMS roughness of 3.3 to 4.5 nm was obtained. 11 is a view showing a surface roughness irradiation result after depositing a magnetic thin film on a conventional Si substrate and the PEN substrate of the present invention.

In addition, the magnetization history curves of the conventional Si substrate and the PEN substrate of the present invention were compared, that is, the magnetization history curves of the thin films were measured using the VSM (Virating Sample Magnetometer). Again no problem was found.

Meanwhile, in the above description, the magnetic layer of the ring closed loop is formed to combine the phenomenon of anisotropic magnetism and planar hole magnetoresistance, but in addition to the ring type as described above in the flexible substrate magnetoresistance sensor according to the present invention, the magnetic layer shape is large Corresponding to the phenomenon of magnetoresistance, tunnel magnetoresistance, super giant magnetoresistance, the same function as described above can be achieved by forming a polygonal structure such as a triangle or a square, a circular structure, a cross structure, or the like.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The flexible thin film magnetoresistive sensor and a method of manufacturing the same according to the present invention are applied to a magnetic field sensor, a biosensor, a permeability sensor, an eddy current sensor for nondestructive inspection, a magnetic field imaging sensor, or a nuclear magnetic resonance (NMR) sensor.

20: flexible substrate
21: electrode layer
22: magnetic sensor layer
23: protective layer

Claims (10)

Flexible substrate,
An electrode layer provided on the flexible substrate,
A magnetic sensor layer formed on the flexible substrate and the electrode layer;
And a protective layer covering a part of the electrode layer and all of the magnetic sensor layer. The method of claim 1,
The flexible substrate may be a film (PC) polycarbonate substrate, polyethylene terephthalate (PET) substrate, polyethersulfone (PES) substrate, polyimide (PI) substrate, polyethylene naphthalate (PEN) substrate, AryLite substrate, or COC (cyclic olefin copoly) E) A flexible thin film magnetoresistance sensor, characterized in that any one of the substrate. The method of claim 1,
The magnetic sensor layer is a closed loop magnetic layer,
The electrode layer is provided with a pair of current terminals in contact with the closed loop opposite to each other, and a current input / output and a pair of voltage terminals in contact with the closed loop facing each other, and detects the output voltage Flexible thin film magnetoresistance sensor. The method of claim 3,
The magnetic sensor layer is formed inside the closed loop in the same shape as the closed loop, spaced apart from the closed loop by a predetermined distance, and includes a second magnetic layer made of the same material as the magnetic layer in the shape of the closed loop. Flexible thin film magnetoresistance sensor. The method of claim 1,
The magnetic sensor layer is a flexible thin film magnetoresistance sensor, characterized in that the magnetic layer of a polygonal structure, circular structure or cross-shaped structure. The method of claim 1,
The flexible thin film magnetoresistance sensor is a flexible thin film magnetoresistance sensor, characterized in that the magnetic field sensor, bio sensor, permeability sensor, non-destructive inspection eddy current sensor, magnetic field imaging sensor or NMR (nuclear magnetic resonance) sensor. Preparing a flexible substrate,
Forming an electrode layer on the flexible substrate,
Forming a magnetic sensor layer on the flexible substrate and the electrode layer; and
Forming a protective layer covering a portion of the magnetic layer and all of the magnetic sensor layer,
The electrode layer is a method of manufacturing a flexible thin film magnetoresistance sensor, characterized in that formed by partially compressing the flexible substrate. The method of claim 7, wherein
The magnetic sensor layer is a flexible thin film magnetoresistance sensor manufacturing method, characterized in that formed on the same plane of the flexible substrate and the electrode layer. The method of claim 7, wherein
The flexible substrate may be a film (PC) polycarbonate substrate, polyethylene terephthalate (PET) substrate, polyethersulfone (PES) substrate, polyimide (PI) substrate, polyethylene naphthalate (PEN) substrate, AryLite substrate, or COC (cyclic olefin copoly) E) A method of manufacturing a flexible thin film magnetoresistive sensor, characterized in that it is one of the substrates. The method of claim 7, wherein
The magnetic sensor layer is a magnetic multilayer thin film of an antiferromagnetic layer (AM layer)-ferromagnetic layer (FM layer) is a method of manufacturing a flexible thin film magnetoresistance sensor, characterized in that formed by a DC magnetron sputter.

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