WO2008016198A1

WO2008016198A1 - 3 axis thin film fluxgate

Info

Publication number: WO2008016198A1
Application number: PCT/KR2006/003054
Authority: WO
Inventors: Hansung Chang
Original assignee: Microgate, Inc.
Priority date: 2006-08-03
Filing date: 2006-08-03
Publication date: 2008-02-07

Abstract

Disclosed herein is a 3 axis thin film fluxgate for detecting magnetic field components in 3 axial directions. The fluxgate includes two single bar type thin film fluxgates for horizontal component detection and a plurality of thin film fluxgates for vertical component detection. The two single bar type thin film fluxgates detecting two horizontal components of a magnetic field and are disposed in the same plane. The thin film fluxgates detect the vertical components of the magnetic field. The fluxgates for vertical component detection are disposed substantially perpendicular to the two fluxgates for horizontal component detection, and include a plurality of magnetic thin films, having a length shorter than that of the fluxgates for horizontal component detection.

Description

[DESCRIPTION] [Invention Title]

3 AXIS THIN FILM FLUXGATE [Technical Field]

<i> The present invention relates to a thin film fluxgate that can measure the direction of the application of a weak magnetic field and, more particularly, to a 3 axis thin film fluxgate that can three-dimensional Iy measure horizontal two axial magnetic field components and a vertical magnetic field component and that can be used in an electronic compass. [Background Art]

<2> A fluxgate is a kind of magnetic sensor, and has been used for searching for buried objects containing steel, such as landmines, an electronic compass and so on.

<3> The basic structure of a fluxgate, as shown in FIGS. 1 and 3, includes a ferromagnetic element 2, a drive coil 4 surrounding the ferromagnetic element 2, and a pickup coil 5. It further includes an Alternating Current (AC) power source 3 for applying AC current to the drive coil, and a voltmeter 6 for detecting voltage induced to the pickup coil.

<4> The operating principle of a fluxgate is as follows. When the drive coil 4 is wound around the ferromagnetic element 2 and AC current is applied to the coil, a time-varying induced magnetic field is generated around the coil, and particularly within the coil due to the current. The ferromagnetic element is magnetized due to the induced magnetic field, thus becoming electromagnets having the N pole and the S pole. In this case, the induced magnetic field has a time-varying characteristic in which the polarity thereof is reversed over time, therefore the magnetic poles of the magnetic element disposed in the coil are alternately reversed over time, with the result that the magnetic field formed around the fluxgate by the ferromagnetic element is also changed over time. Induced current is formed in the pickup coil, which surrounds the magnetic element due to the time- varying magnetic field. As a result, voltage peaks are detected in the pickup coil 5 over time, as shown in FIGS. 2, 4 and 5.

<5> FIG. 1 is a conceptual view showing a conventional 3 axis fluxgate. The conventional fluxgate has a structure in which three two bar type fluxgates 1 are disposed to have an orthogonal structure therebetween in order to measure a magnetic field applied thereto, such as the earth' s magnetic field. The operation of the conventional fluxgate shown in FIG. 1 uses a method in which both a drive coil and a pickup coil are wound around two magnetic elements, that is, a pair of bar type magnetic elements, for each of X, Y, and Z-axis directions, triangular waves or sine waves are input to the drive coil so that the two magnetic elements are magnetized in different directions, and, in this state, voltage waveforms detected in the pickup coil wound around the two magnetic elements are read. FIG. 2(a) is a view showing an input voltage waveform applied to the magnetic elements A and B of the two bar type fluxgate having the structure of FIG. Kb). The current input along the same drive coil 4 is applied in such a way as to magnetize the magnetic elements A and B in different directions.

<6> FIG. 2(b) is a view showing a pickup voltage waveform generated in the pickup coil wound around the magnetic elements A and B of the two bar type fluxgate. Pickup voltages indicate output signals having different signs, as represented in FIG. 2(b). The reason that the output voltages have the same shape as the input voltages, as shown in FIG. 2(b) , is that conventional products are not thin film products using semiconductor technology, unlike the present invention, but are fabricated using a bulk-type ferromagnetic bar, or magnetic material that is formed by binding ferromagnetic powder using epoxy, so that the magnetic characteristics of the magnetic material are not desirable, and thus the magnetization reversal of the magnetic material is not achieved completely, but instead, the magnetic material exhibits electrical behavior like a kind of simple transformer. The conventional products have a characteristic in which output waves are output as triangular waves when input waves are triangular waves, and output waves are output as sine waves when input waves are sine waves. <7> The state of FIG. 2(b) represents output signals in the state in which no external magnetic field is applied at all. Two types of signals having different signs are added through a single coil, and thus have a state of "0 volts over the entire time period. The state of FIG. 2(c) is a view showing output signals that are detected in the magnetic elements A and B, which constitute the conventional two bar type fluxgate, when a magnetic field is externally applied thereto. As the external magnetic field is applied thereto, the output voltage signals are moved horizontally, and have a characteristic in which output voltages are newly generated, unlike the state of "0" volts. The conventional fluxgate has a structure in which two bar type fluxgates are disposed for X, Y and Z axes, and each of the fluxgates uses the principle in which a new output voltage is generated in response to the application of a magnetic field.

<8> The conventional two bar type fluxgate 1 having the above-described operating principle and structure is problematic in that the magnetic characteristics for the X, Y and Z axes are not desirable, so that it must be fabricated to have a large size and two bulky magnetic elements must be formed for operation, with the result that the area occupied by all of the elements is large and the volume of the product is large. A large area fluxgate must be also mounted in the Z-axis direction, so that it cannot be mounted in electronic products, such as mobile phones, which require a small and slim electronic compass. Furthermore, the conventional two bar type fluxgate 1 is problematic in that a signal processing circuit for offsetting signals against each other is additionally required because signals output as shown FIG. 2 have a form similar to that of the output signals of a kind of transformer, and a high capacity amplifier capable of removing noise must be installed because the intensity of signals resulting from offsetting two types of pickup signals is small. To solve these problems, that is, to increase the output signals, it has been necessary to use high current for the operation of the fluxgate. The requirement for a large amount of electricity for accurate directional measurement has been a limiting factor to hinder the conventional fluxgate from being mounted in mobile devices, such as mobile phones, which invariably require low power consumption. [Disclosure] [Technical Problem]

<9> In order to solve the above problems occurring in the prior art, an object of the present invention is to provide a 3 axis thin film fluxgate that enables a 3 axis fluxgate electronic compass to be fabricated to have a small size, so that it can be mounted in a small-sized electronic device such as a mobile phone, and that enables the power necessary for the operation of a device to be minimized. [Technical Solution]

<io> In order to accomplish the above object, the present invention provides a 3 axis thin film fluxgate for detecting magnetic field components in 3 axial directions, the fluxgate including two single bar type thin film fluxgates for horizontal component detection, the two single bar type thin film fluxgates detecting the horizontal two axial components of a magnetic field and being disposed in an identical plane, and a plurality of thin film fluxgates for vertical component detection, the plurality of thin film fluxgates detecting the vertical components of the magnetic field; wherein the plurality of fluxgates for vertical component detection is disposed substantially perpendicular to the two fluxgates for horizontal component detection and includes a plurality of magnetic thin films, having a length shorter than that of the fluxgates for horizontal component detection and a "∞" -shaped magnetic configuration.

<ii> The 3 axis thin film fluxgate according to the present invention is configured such that three thin film fluxgates are disposed for respective X, Y, and Z axes, and detect the horizontal and vertical components of a magnetic field, thereby detecting the accurate direction of the magnetic field and a compass direction on the surface of the earth based on the results of the detection of the magnetic field components.

<i2> In the 3 axis fluxgate of the present invention, the fluxgates for detecting magnetic field components in respective directions are fabricated in a thin film configuration. In particular, the thin film fluxgates for detecting the vertical components of a magnetic field are constructed by winding a drive coil and a pickup coil around a plurality of magnetic thin films, which are arranged in a width direction and have a short length, so that the thin film fluxgates can be fabricated in a flat configuration that allows the thin film fluxgates to be easily mounted in small-sized electronic devices, such as mobile phones. [Advantageous Effects]

<13> According to the present invention, a small-sized electronic compass having low power consumption can be constructed, and, in particular, it can be mounted in a small-sized portable device, such as a mobile phone, and can measure the direction of an external magnetic field with high accuracy. [Description of Drawings]

<14> FIG. 1 is a view showing the basic structure of a conventional two bar type fluxgate;

<i5> FIG. 2 is a view showing examples of voltage waveforms detected in the pickup coil of the conventional fluxgate;

<16> FIG. 3 is a view showing the structure of a single bar type thin film fluxgate according to the present invention;

<17> FIG. 4 is a view showing the operating principle of the thin film fluxgate according to the present invention;

<18> FIG. 5 is a view showing results in which a voltage waveform, detected in a pickup coil of the thin film fluxgate according to the present invention, varies with the externally applied magnetic field;

<19> FIG. 6 is a view showing the structures of X, Y, and Z-axis thin film fluxgates according to the present invention;

<20> FIG. 7 is a view showing the structure of an electronic compass chip fabricated using X, Y, and Z-axis thin film fluxgate devices according to the present invention;

<2i> FIG. 8 is a view showing the magnetic thin films and winding structures of X and Y-axis fluxgates according to the present invention; <22> FIG. 9 is a view showing demagnetizing fields generated within the magnetic thin films of the X and Y-axis thin film fluxgates according to the present invention; <23> FIG. 10 is a view showing a method of fabricating the Z-axis thin film fluxgate according to the present invention; <24> FIG. 11 is a view showing the configuration of the Z-axis thin film fluxgate according to the present invention and the internal structure of the magnetic thin film constituting the fluxgate; <25> FIG. 12 is a view showing the operating principle of the Z-axis thin film fluxgate according to the present invention; and <26> FIG. 13 is a view showing variation in the output signal attributable to the configuration of the magnetic thin film of the Z-axis thin film fluxgate according to the present invention. <27> description of reference numerals of principal elements in the drawings>

<28> 1: two bar type fluxgate <29> 2: ferromagnetic element <30> 3: AC drive power <3i> 4: drive coi 1 <32> 5: pickup coil <33> 6: voltmeter for pickup <34> 7: epoxy molding <35> 8: packaging PCB <36> 9: silicon wafer <37> 10: magnetic thin film <38> 11, 11' , 11" : insulating thin film <39> 12: upper coil <40> 13: lower coil <4i> 14: thin film fluxgate <42> 15: X-axis thin film fluxgate <43> 16: Y-axis thin film fluxgate

<44> 17: Z-axis thin film fluxgate

<45> 18: ASIC for fluxgate electronic compass

<46> 19: bonding wire

<47> 20: wire bonding pad

<48> 21: bottom pad

<49> 22: chip height

<50> 23: pickup area or central area

<5i> 24: drive area or outer area

<52> 25: insulation film for lamination of magnetic films

<53> 26: depression

<54> 27: magnetic flux in drive area

<55> 28: magnetic flux in pickup area

<56> 29: external magnetic field applied to pickup area

<57> 30: external magnetic field applied to drive area [Best Mode]

<58> The construction of the present invention will be described in detail with reference to the accompanying drawings below.

<59> FIG. 3 is a view three-dimensional Iy showing a bar type thin film fluxgate according to the present invention. The thin film fluxgate of the present invention is fabricated on a silicon wafer 9, in which a substrate is coated with an insulating film 11, using a thin film technique and an etching process. In order to fabricate the thin film fluxgate, a lower coil 13 is formed in such a way that a groove is formed so that the lower side of the coil (that is, half of the coil) can be formed in the insulating film 11 on the substrate of the silicon wafer and the groove is filled with a conductive material, such as aluminum. A magnetic thin film 10 surrounded by a lower insulating film 11' and the upper insulating film 11' is formed. Finally, an upper coil 12 is formed. As a result, a drive coil 4 and a pickup coil 5 are allowed to surround the magnetic thin film 10, which is electrically isolated by the insulating thin films 11' and 11" . <60> The detailed structure and sectional structure of the thin film fluxgate according to the present invention are shown in FIG. 3(b) . In order to fabricate the bar type thin film fluxgate, a groove is formed by removing the portion, in which the lower coil 13 will be formed, from the insulating film on a substrate formed on the silicon wafer 9 through a photolithography process and an etching process. The groove is filled with aluminum or an aluminum alloy thin film, that is, a conductive thin film, which is the material of the lower coil 13. This is performed in order to increase flatness in the subsequent processes.

<6i> Thereafter, a primary insulating thin film, that is, the lower insulating thin film 11' , is formed to expose both ends of the lower coil to some extent and to cover the entire length of the fluxgate. The reason that the insulating thin film or the like is not formed at both ends of the lower coil is to produce a winding structure of a type that surrounds the magnetic thin film, surrounded by the insulating thin film, by connecting the ends to each other in an upper coil forming process, which is the final process. Thereafter, the ferromagnetic thin film 10, having a length and width smaller than those of the insulating thin film 19 and a laminated structure, is formed. Subsequently, a secondary insulating thin film, that is, the upper insulating thin film 11" , for preventing electric leakage between the upper coil and the ferromagnetic material, is formed. Thereafter, the thin film of the upper coil 12 is formed, and a terminal at the end of the upper coil is connected to the previously formed terminal of the lower coil 13, thereby completing the bar type thin film fluxgate having a structure in which two types of coils surround the magnetic thin film.

<62> In order to fabricate the thin film fluxgate of the present invention, the lower coil thin film 13, the primary insulating thin film 11' , the magnetic thin film 10, the secondary insulating thin film 11" , and the upper coil thin film 12 must be formed in sequence. In order to secure electrical characteristics and mechanical characteristics for crack prevention or the like, in the fabrication of the respective thin films, it is necessary to use specific materials and also to form the magnetic thin film 10 having a laminated structure. In the present invention, in order to eliminate stress occurring across the entire thin film fluxgate, Siθ2, which has a toughness characteristic higher than those of typical insulating thin films made of Ta₂O₅, Al₂O₃ and TiO₂, is used as the material of the primary insulating thin film 11' , thereby improving the magnetic characteristic of the magnetic thin film 10 formed on the primary insulating thin film. In order to maintain a good magnetic characteristic, the primary insulating thin film 11' is formed to have a thickness of at least 5,000 A. The primary insulating thin film 11' has the best magnetic characteristics in a thickness range of 5,000 A (0.5 μm) to 20,000 A (2 μm) . The magnetic thin film 10 formed on the primary insulating thin film 11' must have magnetic characteristics, such as low coercivity, high permeability and fast saturation magnetization, that is, high squareness, for which the magnetic hysteresis curve of the magnetic material has a narrow width and a square shape, which are required for the fluxgate magnetic thin film. In order to fabricate a magnetic thin film having these magnetic characteristics, a single-layer magnetic thin film configuration is inappropriate, but a laminated thin film, in which a NiFe thin film, generally used as the magnetic thin film, and an Al₂O₃ insulating thin film 25 are alternately formed, is desirable. The NiFe ferromagnetic thin film and the Al₂O₃ insulating thin film, constituting the laminated thin film, have magnetic characteristics suitable for the thin film fluxgate in a thickness range of 600+300 A and in a thickness range of 150+100 A, respectively. When the magnetic thin film and the insulating thin film are formed such that they satisfy the above-described thickness conditions, the magnetic hysteresis curve has a narrow square shape. In order to make detection using a dedicated circuit easy in order to increase the magnitude of output voltage generated from the thin film fluxgate, the number of layers constituting the magnetic element is increased. In order to increase the size of the entire magnetic element, it is preferred that at least three pairs of laminated films be formed when the NiFe ferromagnetic thin film and the AI₂O₃ insulating thin film form a pair.

<63> FlG. 3(C) is a view showing the state of the winding of the bar type thin film fluxgate. As shown in this drawing, the bar type thin film fluxgate has a structure in which both the drive coil 4 and the pickup coil 5 surround the magnetic thin film 10. In order to operate the fluxgate, it is necessary for AC current to flow through the drive coil 4, and for the magnetization direction of the magnetic thin film disposed within the coil to be changed to the right and left using the magnetic field of right and left solenoid coils, which is generated when the AC current flows through the coil. Under this situation, that is, when the magnetization direction of the magnetic element is changed by the drive coil, the independent voltage peaks shown in FIGS. 4(d) and 4(f) are generated in the pickup coil.

<64> FIG. 4 is a view showing a principle according to which an output signal is generated in an isolated or independent peak shape in the thin film fluxgate. The generation of the independent peaks through the pickup coil for detecting an output signal is closely related to the magnetic characteristics of the magnetic thin film constituting part of the fluxgate. In the case where the magnetic behavior of the magnetic thin film fabricated for the fluxgate has a magnetic hysteresis curve having excellent squareness, as shown in FIG. 4(c), triangular waves or sine waves, input to the drive coil of the fluxgate, periodically apply a magnetic field to the magnetic element surrounded by the drive coil. The input AC is subjected to magnetic behavior ranging from φ to ©, indicated in FIG. 4(c). The dotted lines of FIG. 4(c) indicate magnetic behavior when an AC signal is applied to the thin film fluxgate in the state in which there is no externally applied magnetic field, such as the earth' s magnetic field. When the input AC has this magnetic behavior, output peaks have the shapes indicated by the dotted lines of FIG. 4(d). In this case, the locations at which the independent peaks occur lie on an extension line A, indicated in the drawing. Furthermore, the locations at which output peaks having the (-) sign are output lie on an extension line B (B' ), indicated in the drawing. The dotted lines of FIG. 4(f) also indicate the locations at which voltage peaks occur when there is no externally applied magnetic field. The reason that the independent peaks occur at the portions in which magnetization reversal is generated is that the output voltage is directly proportional to a magnetization value, which varies over time, that is, (d(M)dt). The solid lines of FIG. 4(c) indicate changes in the magnetic behavior occurring when a magnetic field is applied from the right in the state in which the bar type fluxgate is placed horizontally, as shown in FIG. 4(a). If a magnetic field having a DC component, such as the earth magnetic field, is applied from the right, the magnetic hysteresis curve shifts to the left. When AC input current flows through the drive coil in the state in which the external magnetic field is applied as described above, a solenoid magnetic field is alternately formed to the right and left within the drive coil in response to the current flow through the drive coil. In this case, since the magnetic hysteresis curve has shifted to the left, the occurrence of voltage peaks has behavior different from that in the case in which there is no applied magnetic field, when magnetization reversal is generated under the same time conditions. The occurrence of the peak of (+) output voltage, attributable to the shift of a magnetic field from a (-) magnetic state to a (+) magnetic state, is generated in a short time compared to that in the case in which there is no applied magnetic field. The occurrence of the peak of an (-) output voltage attributable to the shift of the magnetic field from a (+) magnetic state to a (-) magnetic state is generated in a longer time. Accordingly, the distance between the output peaks is greater than that in the case in which there is no externally applied magnetic field. FIGS. 4(e) and 4(f) are views showing the state in which output peaks occur when an external magnetic field is applied from the left of the fluxgate, which is placed horizontally, as shown in FIG. 4(b). In contrast to the previous case, the distance between the output peaks is reduced. <65> The reason that, according to the present invention, the 3 axis fluxgate can be fabricated using only one magnetic material pole, unlike the conventional two bar type fluxgate 1, is that it is possible to fabricate a ferromagnetic thin film 10 having a narrow and square-shaped magnetic hysteresis curve using magnetic thin film technology. The ferromagnetic element used in the conventional fluxgate does not have a square-shaped magnetic hysteresis curve, as shown in FIG. 4, but has a magnetic hysteresis curve that is inclined in response to an applied magnetic field H. Accordingly, a longer time is taken at the time of magnetization reversal from -M to +M, and, therefore, isolated voltage peaks do not occur. As a result, the ferromagnetic material operates like a kind of transformer and has triangular or sine wave output signals, as shown in FIG. 2(a), with the result that a fluxgate, which uses a method of measuring the distance between independent peaks like that of the present invention, cannot be fabricated using conventional technology.

<66> Since the present invention has the output signals as shown in FIGS. 4(d) and 4(f), that is, a characteristic in which independent voltage peaks occur, it is possible to measure the locations of output voltage peaks. Furthermore, since the peaks shift in proportion to a change in the direction and magnitude of an externally applied magnetic field, it is possible to measure the direction of an externally applied magnetic field, such as the earth' s magnetic field, using a method of measuring the distance (actually, the time) between two independent peaks.

<67> FIG. 5(a) is a view showing the state in which the thin film fluxgate is oriented in a specific direction with respect to an external magnetic field. FIGS. 5(b), 5(c), and 5(d) are views showing the modes of variation in output signal attributable to the direction in which the thin film fluxgate is oriented. When the thin film fluxgate is oriented to the east or west, there is no magnetic field acting in the longitudinal direction of the thin film fluxgate. Accordingly, the output peaks of the thin film fluxgate are (+) and (-) output peaks at locations at which there is no externally applied magnetic field, and the distance between the peaks is 'E' μ sec or 'W μsec, as shown in FIG. 5(b). When the thin film fluxgate is oriented to the north, a magnetic field is applied from a position below the fluxgate device in the longitudinal direction, and thus the distance between the output voltage peaks is reduced to 'N' μsec, as shown in FIG. 5(c). When the thin film fluxgate is oriented to the south, the distance between the output peaks is increased to 'S' μsec, as shown in FIG. 5(d). When the external magnetic field is applied as described above, a peak shift phenomenon, in which the voltage peak moves to the right and left, occurs. Accordingly, if there is no additional external magnetic field other than the earth' s magnetic field, as shown in FIG. 5, it is possible to accurately detect the presence of an external magnetic field and the direction of the application of the magnetic field by analyzing the extent of the peak shift of voltage detected in the pickup coil. The reason that isolated peaks occur in the output signal of the fluxgate according to the present invention is that, since thin film technology based on semiconductor technology is used for the fabrication of the fluxgate according to the present invention, the distance between the coil, which surrounds the magnetic element, and the magnetic element can be considerably reduced compared to those of bulky products, so that the magnetization and magnetization reversal of a magnetic thin film having a small thickness can be easily achieved using only a small current input to the drive coil, and the pickup coil can accurately read the occurrence of weak voltage attributable to the result of magnetization reversal, compared to bulky assembly products.

<68> FIGS. 6(a) and 6(b) are views showing X- and Y-axis single bar type thin film fluxgates according to the present invention. FIGS. 6(c) and 6(d) are views showing Z-axis fluxgates. FIG. 6(a) shows a thin film fluxgate having a structure in which a drive coil and a pickup coil are alternately wound around a bar type magnetic thin film. FIG. 6(b) shows an X- and Y-axis thin film fluxgate having a magnetic thin film design and a winding structure having improved electrical characteristics compared to that of FIG. 6(a). The X- and Y-axis thin film fluxgate of FIG. 6(b) has a design in which depressions are formed in the end portions of a magnetic thin film having a dumbbell shape, and a winding structure in which a drive coil and a pickup coil are not alternately wound for each turn, but the drive coil is wound a specific number of turns and the pickup coil is alternately wound a specific number of turns. FIG. 6(c) is a view showing the construction of the Z-axis thin film fluxgate having a structure in which a drive coil and a pickup coil are alternately wound for each turn around a bar-shaped magnetic thin film having a short length. FIG. 6(d) shows a Z-axis thin film fluxgate having a magnetic thin film design and a winding structure having improved electrical characteristics compared to that of FIG. 6(c).

<69> The magnetic thin film constituting part of the Z-axis thin film fluxgate is fabricated to have a "∞" -shaped structure. The drive and the pickup coil required for the operation of the fluxgate have a structure in which they are not wound to intersect each other in the same area, but are separately wound in different areas. The drive coil 4 is concentratedly wound around a round portion 10' on both sides of the magnetic thin film, constituting part of the Z-axis element, and the pickup coil is concentratedly wound around a rectilinear portion at the center of the magnetic thin film 10. Meanwhile, the use of a method of winding a drive coil a specific number of turns around both ends of a central portion around which the pickup coil is wound helps keep the direction of magnetic flux on the central portion in one direction, thus helping increase the magnitude of output peaks. However, an increase in the number of turns of the drive coil in the same pickup area 10 causes a decrease in the number of turns of the pickup coil 5, thus reducing the magnitude of peaks. Accordingly, it is preferred that a drive coil having a line width of 7 μm be wound ten or less turns.

<70> Depressions are also formed in the end portions of the central portion 10 of the magnetic thin film of the Z-axis thin film fluxgate, as in the magnetic thin film structure of the X- and Y-axis thin film fluxgates of FIG. 6(b). Since the Z-axis thin film fluxgate of FIG. 6(d) determines the overall thickness of the electronic compass chip when the Z-axis fluxgate is erected in a packaging PCB 8 so as to mount it in a mobile device, such as a mobile phone, the overall height of the Z-axis thin film fluxgate must be as small as possible while the output voltage peak generated from the Z-axis thin film fluxgate must be as high as possible. Accordingly, the present invention proposes a Z-axis thin film fluxgate having a structure in which a plurality of fluxgates having a short length of at least 0.9 mm is arranged, and the fluxgates are connected to each other using a single drive coil and a single pickup coil. When a fluxgate is constructed to have the structure of the present invention and then electricity is allowed to flow through a drive coil, magnetization reversal simultaneously occurs in a plurality of magnetic thin films in the same direction, so that pickup voltages generated from thin film fluxgates having a small size are added, and occur in one pickup coil. Accordingly, isolated peaks required for the detection of an externally applied magnetic field exhibit magnitude sufficient to determine a direction.

<7i> FIG. 7(a) is a view showing the structure of an electronic compass chip using a new type of a thin film fluxgate according to the present invention. The present invention is identical to the conventional method in that one fluxgate is disposed for each of X, Y and Z axes, but is different from the conventional method using a two bar type fluxgate for each axis in that the present invention has a structure in which a single bar type fluxgate is disposed in each axis and a plurality of Z-axis fluxgates, including a magnetic thin film having a "∞" shape, is arranged in parallel so as to produce an electronic compass chip having a small thickness. The shape of the entire 3 axis fluxgate can be made flat in such a way that the height of a plurality of divided thin films for measuring a vertical component (Z-axis component) magnetic field is formed to be shorter than that of fluxgates for detecting horizontal component (X and Y axes) magnetic fields.

<72> FIG. 7(b) is a view showing the cross-sectional structure of an electronic compass chip in which a 3 axis fluxgate is mounted. In order to mount an electronic compass chip in a mobile device such as a mobile phone, the height of the compass chip must be smaller than 1.4 mm, which is the highest allowable height, and the thickness of the compass chip must be as small as possible. The electronic compass chip has a construction in which various elements constituting the electronic compass, are placed on the packaging PCB 8, respective electrical terminals 20 are connected using wires 19, and an element protection epoxy molding 7 is formed thereon. In this case, one important thing to consider is that the overall height of the chip must be reduced. Factors determining the overall height of the chip include the thickness of the PCB, the height of the Z-axis fluxgate, the thickness of the epoxy molding, and the thickness of the bottom pad. The heights of the X and Y-axis fluxgate and the ASIC device can be controlled using a method of grinding the rear surfaces of the silicon wafers in which the elements are formed, so that there is no problem in reducing the overall thickness of the chip. Since a rigid PCB ranging from 0.15 mm to 0.2 mm is typically used as the PCB and the thickness of the epoxy molding typically ranges from 0.10 mm to 0.15 mm, the height of the Z-axis thin film fluxgate must be 0.95 mm to 0.85 mm or less in order to fabricate a chip having an overall size of 1.2 mm or less. In order to further decrease the overall height of the chip, it is preferred that the height of the Z-axis thin film fluxgate be 0.85 mm or less.

<73> FIG. 8a is a view showing an X- and Y-axis thin film fluxgate according to the present invention. The X- and Y-axis thin film fluxgates have a magnetic thin film structure in which a magnetic thin film 10 has a dumbbell shape, in which both end portions of the magnetic thin film 10, around which coils are not wound, are wider than the central portion thereof, around which coils are wound, and depressions 26 are formed in the central portions of the both ends. In the winding of the coils required for the operation of the thin film fluxgate, the drive coil and the pickup coil are separately wound, as shown in FIG. 8(a). In this case, the line width of the winding used is 7 ±2 [M, and the number of turns for each winding area ranges from 10 to 30. The reason that the line width of the winding is limited is that, if a high line width is employed, a large amount of current flows through a thick wire and high power consumption is required for the operation of a fabricated thin film fluxgate. The reason that the narrow line width is employed is that, if a thin wire is used, the resistance of the coil itself is increased and current sufficient to generate a magnetic field capable of magnetizing the magnetic thin film does not flow through the wire. In order to obtain as large a number of turns as possible, it is preferable to use winding as dense as possible.

<74> FIG. 8(b) is a view showing a thin film fluxgate having a length of 2.2 mm. FIG. 8(c) is a view showing an output signal that is output along the pickup coil when an AC input voltage of ±2 volts is applied to the drive coil of the thin film fluxgate shown in FIG. 8(b). The magnitude of a voltage peak output from the thin film fluxgate according to the present embodiment is about 10 mV. The reason for the criterion that the output magnitude be set at 10 mV is that the magnitude of the output voltage is sufficient to detect an output signal in a typical driving circuit 18. When the output signal is weak, an electronic compass can be fabricated by improving the performance of the driving ASIC 18. The thin film fluxgate having the configuration of FIG. 8(b) may be fabricated so that the overall chip width of the electronic compass is 4mm x 4mm.

<75> FIG. 8(d) shows a fluxgate for detecting a horizontal magnetic field, in which a drive coil and a pickup coil are separately wound around a dumbbell-shaped magnetic thin film having depressions formed in both ends thereof according to the present invention. FIG. 8(e) is a view showing the magnitude of an output voltage generated from the fluxgate shown in FIG. 8(d). The output voltage has an output voltage peak of 13mV, which is 30% higher than that of a simple bar type thin film fluxgate.

<76> In the thin film fluxgate having the structure shown in FIG. 8(d), sufficient magnetization reversal of a magnetic thin film is achieved based on a small device size and a small number of turns, and the output through the pickup coil has about 30% or higher output voltage peaks, compared to the thin film fluxgate design shown in FIG. 8(b). The reason that the winding structure of FIG. 8(a) can detect a greater output despite the smaller number of turns of the pickup coil is that the magnetization of the magnetic thin film through the drive coil is made relatively easy because the drive coil is concentratedIy wound in the same area, compared to the case where the magnetization of the magnetic thin film through the drive coil is not easy in the structure in which the drive coil and the pickup coil are alternately wound.

<77> FIG. 9 is a view showing the difference between the characteristics of the two types of magnetic thin films shown in FIG. 8 and the effects of a demagnetizing field generated in the magnetic element. As shown in FIG. 9(a), in the case of a simple bar type magnetic thin film, if current flows through a drive coil, the magnetic thin film generates magnetization in the direction in which a magnetic field is applied due to the magnetic field generated according to the flow of current, so that the spins of atoms, constituting the magnetic element, are aligned, thus instantaneously forming a magnet. Once the magnet is formed, magnetic lines extending from one magnetic pole to the other magnetic pole are formed. These magnetic lines are formed within the magnet as well as outside the magnet, so that the magnetic lines oriented toward the opposite magnetic pole through the magnet are formed. This is called a demagnetizing field. The occurrence of the demagnetizing field acts to disturb the magnetization direction at both ends of the magnet, thus resulting in a reduction in the area in which the magnetization direction is uniform over the entire magnet bar. The demagnetizing field is strong at both poles (that is, both ends) of the magnetic element, and is almost "0" at the center of the magnetic element. The effect of the demagnetizing field is relatively great when the length of the thin film fluxgate is short. According, when the fluxgate is formed to be small, the size of portions contributing to complete magnetization reversal is reduced, and thus the magnitude of the output peak through the pickup coil is decreased. In contrast, when the fluxgate is formed to be long, the magnitude of the output increases, but the overall size of the electronic compass product also increases. As a result, it is necessary to form the thin film fluxgate to be as small as possible within a range in which a dedicated circuit used in the electronic compass can perform analysis.

<78> FIG. 9(b) is a view showing the state of the magnetization of the dumbbell-shaped magnetic thin film in which depressions are formed in both ends of the magnetic thin film according to the present invention. When the size of both ends is increased, a phenomenon in which magnetic poles are formed to be large over a wide area occurs. When depressions are additionally formed in both ends, the area in which a demagnetizing field is formed spreads to both ends of the dumbbell shape. Accordingly, the magnitude of the demagnetizing field generated from the magnetic thin film having the shape shown in FIG. 9(b) is reduced to a size smaller than that of the demagnetizing field generated from the simple bar-shaped magnetic element shown in FIG. 9(a). The reason that the output signal of the dumbbell-shaped thin film fluxgate, in which the depressions are formed at both ends according to the present invention is increased is that a reduction in the demagnetizing field, described in conjunction with FIG. 9, has influence thereon.

<79> FIG. 10 is a view showing a method of fabricating the Z-axis thin film fluxgate according to the present invention. The Z-axis thin film fluxgate is fabricated in the same sequence as the X and Y-axis thin film fluxgate, specifically, in the sequence of the lower coil, the insulating thin film, the magnetic thin film, the insulating thin film, and the upper coil. However, in the case of the magnetic thin film, a method of separately fabricating magnetic thin films having different characteristics and overlapping the boundaries of the two magnetic thin films is used.

<80> FIG. lθ(a) is a view showing the state in which a lower coil 4 for the drive coil and a lower coil 5 for the pickup coil are formed on the surface of a silicon wafer. <8i> FIG. 10(b) is a view showing the state in which an insulating thin film 11' for preventing electrical leakage between the lower coil and the magnetic thin film is formed in the portion in which the magnetic thin film is raised.

<82> FIG. HXc) is a view showing the state in which a magnetic thin film used in a pickup area 23 is formed. FIG. 10(d) is a view showing the state in which a magnetic thin film used in a drive area 24 is formed. It must be noted that, at the time of fabricating the magnetic thin film, the boundary surfaces of the magnetic thin film formed in the pickup area and the magnetic thin film formed in the drive area must overlap each other in order to connect the magnetic paths of the magnetic thin films, constituting the Z- axis thin film fluxgate.

<83> FIG. 10(e) is a view showing the state in which the upper insulating thin film 11 is formed so as to prevent electrical leakage between the magnetic thin film, which is previously formed, and the upper coil, which is finally formed.

<84> FIG. 10(f) is a view showing the state in which the upper coil is formed so as to connect the drive coil 4 and the pickup coil 5, which are partially formed in the lower portion, as shown in FIG. 10(a), in the upper portion.

<85> FIG. 11 is a view showing the structure and construction of the shortest axis Z-axis thin film fluxgate according to the present invention. FIG. ll(a) is a view showing the structure of the magnetic thin film and the winding structure of the Z-axis thin film fluxgate. The magnetic thin film of the Z-axis thin film fluxgate has a "°°" -shaped basic structure. The magnetic thin film is divided into a central straight portion 23 and outer curved portions 24. The respective portions are fabricated to have different types of laminated magnetic thin film structures.

<86> In contrast, a coil 4 for driving the magnetic thin film is concentratedly formed in the outer curved portion 24, and a pickup coil 5 is concentratedly formed in the central straight portion 23. Here, it is necessary for each winding to be wound such that the longitudinal direction of each winding is as close to perpendicular to the longitudinal direction of the magnetic thin film as possible. The windings 5 in the pickup area are wound in an equilibrium state, while the windings 4 in the drive area are radially wound along a curved drive area, as shown in FIG. ll(a).

<87> Magnetic lines required for magnetization reversal within part of the magnetic thin film in the central pickup portion 23 for detecting magnetization reversal are configured such that magnetic flux (27 of FIG. 12), which is not generated in the pickup portion, but is generated in the outer drive area 24, flows into the pickup area 23, which is magnetically connected thereto. In other words, the magnetic flux (27 of FIG. 12), which is generated by AC current input to the drive coil 4 wound around the outer portion, is made to flow into the pickup area 23 of the Z-axis thin film fluxgate, thereby generating magnetization reversal within the pickup area. In this case, the pickup coil 5 wound around the pickup area 23, that is, the central portion, detects the magnetization reversal of the central portion.

<88> FIG. ll(b) is a view showing the internal structure of the magnetic thin film constituting part of the Z-axis thin film fluxgate. The magnetic thin films constituting the pickup area 23 and the drive area 24 are each formed to have a laminated structure, but it is important to note that the detailed constructions thereof have different structures. It is necessary for the central area 23 to be formed to have a structure identical to the laminated structure of the X-axis thin film fluxgate. The central area is formed to have a laminated thin film structure in which the NiFe magnetic thin film 10 and the AI2O3 insulating thin film 25 are alternately arranged.

The NiFe ferromagnetic thin film and the AI2O₃ insulating thin film, constituting the laminated thin film, are formed to have a thickness range of 600+300 A and a thickness range of 150+100 A, respectively. In the outer area, a laminated magnetic thin film made of the same material is formed, but the thickness of the magnetic thin film must be varied. In order to allow the occurrence of a pickup voltage of lOraV or higher and the occurrence of a measurable peak shift at the same time, it is required that the NiFe ferromagnetic thin film and the Al₂O₃ insulating thin film formed in the outer area 24 have a thickness range of 1800+200 A and a thickness range of 150+ 100 A, respectively. Furthermore, in order to attain a pickup voltage of at least 10 mV under the condition that the overall height of the Z-axis thin film fluxgate is maintained at 0.9 mm or less, three Z-axis thin film fluxgates are connected in parallel to each other and an input voltage is +2 volts, it is necessary for the magnetic thin film of the central portion 23 to be formed in an eight or more-layer laminated film configuration (eight magnetic thin film layers + seven intermediate insulating thin film layers), and for the outer portion 24 to be formed in a three or more-layer laminated film configuration.

<89> Although a magnetic thin film having a thickness and structure inferior to those of the above-described magnetic thin film is formed, output peaks can be generated. However, in this case, the magnitude of the output signal of the Z-axis thin film fluxgate is reduced, it is necessary to considerably improve the performance of the dedicated driving circuit of an electronic compass. Furthermore, in order to increase the magnitude of an output, it is possible to fabricate a Z-axis thin film fluxgate having a short length by connecting as large a number of unit elements as possible in parallel to each other. However, in this case, the overall length of the Z-axis thin film fluxgate is increased, thus making it difficult to fabricate a small-sized electronic compass chip. FIG. ll(c) is a view showing a Z-axis thin film fluxgate using a method of winding a drive coil having a line width ranging from 5 to 9 μm around both ends of the pickup area 23 at least five to ten turns so as to contribute to the magnetization reversal of the pickup area 23. The additional disposition of the windings of the drive coil at both ends of the pickup area contributes to a significant improvement in the magnitude of output peaks. However, an increase in the number of windings of the drive coil in a limited pickup area results in a relative reduction in the number of windings of the pickup coil, therefore the formation of a drive coil having 10 or more turns at both ends of the pickup area is not desirable. FIG. ll(d) is a view showing a structure in which the central portion of the pickup area is divided longitudinally. The construction of the magnetic thin film is characterized in that it can arbitrarily increase the area of the magnetic thin film, which participates in pickup, without increasing the number of windings of the pickup coil.

<90> FIG. 12 is a view showing the operating principle of the Z-axis thin film fluxgate according to the present invention. FIG. 12(a) is a view showing the state in which the overall magnetic thin film constituting part of the Z-axis thin film fluxgate is formed to have a single identical laminated structure. FIG. 12(c) is a view showing the magnetic characteristics of the magnetic thin films of the pickup area 23 and drive area 24 of the Z-axis thin film fluxgate, which are fabricated using the same thin film. Since the respective areas are formed to have the same magnetic thin film laminated structure, they have the same magnetic hysteresis curve.

<9i> FIG. 12(b) is a view showing a Z-axis device having a construction in which magnetic thin films constituting part of the Z-axis thin film fluxgate have different laminated structures in the pickup area 23 and the drive area 24. FIG. 12(d) is a view showing magnetic hysteresis curves having two different types of slopes, which are caused by forming different laminated films in the respective areas.

<92> The NiFe ferromagnetic thin film and the AI2O3 insulating thin film in the pickup area 23 have a thickness range of 600+300 A and a thickness range of 150+100 A, respectively, and the NiFe ferromagnetic thin film and the A1203 insulating thin film in the drive area 24 have a thickness range of 1800+200 A and a thickness range of 150+100 A, respectively. Since the laminated magnetic thin films are formed in respective areas under different conditions, the magnetic thin films constituting part of the Z-axis thin film fluxgate have different magnetic characteristics according to the area. <93> The forming of magnetic thin films having different magnetic hysteresis curves can be realized by varying a laminated structure while using the same magnetic material. However, different magnetic hysteresis curves in respective areas can also be obtained by forming the magnetic thin films using different magnetic materials. Alternatively, the occurrence of output peaks and a peak shift through the Z-axis fluxgate can be caused by merely changing the area of the component magnetic element. However, it is to be understood that these methods are embodiments that adhere to the principle of the present invention, in which output peaks are shifted through the construction of magnetic thin films having different magnetic characteristics.

<94> In the case of the Z-axis thin film fluxgate fabricated to have the magnetic thin film structure shown in FIG. 12a, magnetic flux 27, which is generated in the drive area 24 due to the flow of current into the drive coil 4, causes magnetic flux to flow along the path, which is magnetically connected to the pickup area 23, while continuously forming a closed loop in the pickup area 23. The direction of the generation of the magnetic flux is determined by the direction of the current flowing into the drive coil wound around the drive area. If an external magnetic field, such as the earth' s magnetic field, is applied from the upper side in the state in which the magnetic flux in the pickup area is oriented upwards by the magnetic flux generated in the drive area, magnetic flux 30 caused by the external magnetic field is additionally applied to the magnetic thin film of the drive area 24, in addition to the magnetic flux 27 caused by the drive coil. This additional magnetic flux is extended to the pickup area 23, so that the magnetic flux is added in the upward direction of the pickup area. In contrast, a magnetic field in a reverse direction, which is caused by the external magnetic field, is added to the magnetic flux 28 generated by the drive coil within the pickup area. In the case where the magnetic thin films constituting part of the Z-axis thin film fluxgate have the same magnetic characteristic, an externally applied magnetic field in the pickup area 23 causes a magnetic field 30 to be applied to the drive area, thereby forming magnetic flux 30' in an upward direction of the pickup area. Furthermore, the externally applied magnetic field causes a magnetic field 29 to be applied in a downward direction, which has a direct effect on the pickup area. As a result, the two magnetic field components are in equilibrium, though it is not perfect. This creates the pickup voltages of an output signal at the same location irrespective of whether an external magnetic field is applied or not, thus resulting in the prevention of the output peaks from moving regardless of the existence of the external magnetic field. That is, the Z-axis fluxgate, fabricated using the same material and construction, cannot detect the direction of the externally applied magnetic field. <95> FIG. 12(b) is a view showing variation in the magnetic flux within the magnetic thin film in response to the application of an external magnetic field in the case where the magnetic thin films constituting part of the Z- axis thin film fluxgate are formed of magnetic thin films having different magnetic characteristics. The magnetic hysteresis curve of the magnetic thin film constituting the drive area 24 has a characteristic in which it is inclined more than the magnetic hysteresis curve of the magnetic thin film of the pickup area. This means that, when an external magnetic field is applied, the variation in magnetization is relatively small. When an external magnetic field is applied to the magnetic thin film having the construction shown in FIG. 12(b), the magnitude of the magnetic flux 30, which is additionally generated in the drive area 24, is relatively smaller than that of the structure of FIG. 12(a). Thus, the magnitude of the magnetic flux 30' , which is additionally applied in the upward direction of the pickup area 23, is relatively smaller than that of the Z-axis fluxgate having the structure of FIG. 12(a). In contrast, the magnitude of the external magnetic field 29, which has a direct effect on the pickup area based on the application of an externally applied magnetic field, has a direct and large effect on the magnetic flux 23 generated due to the drive coil. Accordingly, the size of the offset of the magnetic flux, generated by the externally applied magnetic field, does not become "0," as in FIG. 12(a), but magnetic flux remaining without being offset exists, so that there exists magnetic flux that effects the magnetic flux within the magnetic thin film of the central pickup area. This difference causes the occurrence of the shift of output voltage peaks, which are detected by the pickup coil in the pickup area.

<96> The Z-axis thin film fluxgate according to the present invention does not use a method of measuring the distance between the output peaks depending on the variation in magnetization in the longitudinal direction of a bar shape, but uses a method of applying artificial variation, which changes magnetic characteristics, to specific portions of the magnetic thin films constituting part of the Z-axis thin film fluxgate, so that the respective magnetic thin films have the difference in the degree of reaction to the externally applied magnetic field, thereby finally generating a peak shift, and of detecting the direction of the externally applied magnetic field by measuring the distance between the peaks.

<97> FIG. 13 is a view showing the configurations of the Z-axis thin film fluxgates according to the present invention and corresponding variations in electrical characteristics. FIGS. 13(a) and 13(b) are views showing Z-axis thin film fluxgates, which are fabricated to have the same magnetic thin film structure, and the magnitude of output voltage peaks that vary depending on whether the depression 26 is formed in the end of the pickup area. The magnitude of the pickup voltage is 10 mV or higher, irrespective of whether the depression is formed, but the overall magnitude of the output voltage peak is increased when the depressing is formed in the end of the pickup area. This result has the same effect as the variation in the electrical characteristics of the X- and Y-axis thin film fluxgate shown in FIG. 8. However, since a peak shift is not so great for the application of an external magnetic field in the case of FIGS. 13(a) and 13(b), the constructions shown in FIG. 13(c) and (d) are preferred for an electronic compass.

<98> FIGS. 13(a) and 13(b) are views showing the configurations of Z-axis thin film fluxgates, which are formed of heterogeneous magnetic thin films, according to the present invention and corresponding variations in electrical characteristics. A Z^~axis thin film fluxgate fabricated to have the same magnetic thin film structure rarely shows a peak shift for an externally applied magnetic field, whereas a Z-axis thin film fluxgate fabricated to have two types of laminated magnetic thin film structures generates a great peak shift for the application of an external magnetic field. Furthermore, in the case where the pickup area is divided in the longitudinal direction, as in FIG. 13(d), an output peak having a voltage of 10 mV or higher is generated. The configuration of FIG. 13(d) is characterized in that a pickup area 23, which can take part in pickup, can be widened without increasing the number of windings of a pickup coil. As the pickup area is widened, the magnitude of the output voltage peak increases.

<99> The thin film fluxgate according to the present invention can be fabricated using a fabrication method identical to that described with reference to FIGS. 6 and 7. However, the technical gist of the 3 axis fluxgate according to the present invention resides in that the fluxgate for detecting a vertical magnetic field component is formed of a plurality of short thin film sensors so that the fluxgate can be made flat. Accordingly, methods of fabricating the thin film fluxgate, other than the methods of FIGS. 6 and 7, also fall within the scope of the present invention.

<ioo> In the thin film fluxgate for detecting a vertical magnetic field component, it is preferred that, in order to magnetize the magnetic thin films using an induced magnetic field in the same form, drive coils disposed around a plurality of short magnetic thin films arranged in the width direction thereof be electrically connected to one another, and the plurality of short thin films be magnetized by a single drive coil, as shown in FIG. 6.

<ioi> Although the construction of the present invention has been described with reference to the preferred embodiment and the accompanying drawings, the scope of the protection of the present invention is not limited to these. That is, it will be apparent to those skilled in the art that various modifications and design changes are possible without departing from the technical spirit of the invention. Accordingly, the scope of the protection of the present invention should be determined based on the descriptions of the accompanying claims.

[Industrial Applicability]

<iO2> As described above, according to the present invention, it is possible to fabricate an electronic compass chip using a 3 axis thin film fluxgate, which has a size of at least 4mm (length) x 4mm (width) x 1.2mm (height) so that it can be mounted in a small-sized portable device, such as a mobile phone or a PDA, and which enables three-dimensional measurement. It is also possible to construct an electronic compass, which is capable of detecting an accurate direction on the surface of the earth even at a power of 5V or less, particularly 2V or less.

Claims

[CLAIMS] [Claim 1]

<iO4> A 3 axis thin film fluxgate for detecting magnetic field components in 3 axial directions, the fluxgate comprising two single bar type thin film fluxgates for horizontal component detection, the two single bar type thin film fluxgates detecting two horizontal components of a magnetic field and being disposed in an identical plane, and a plurality of thin film fluxgates for vertical component detection, the plurality of thin film fluxgates detecting vertical components of the magnetic field; wherein the plurality of fluxgates for vertical component detection is disposed substantially perpendicular to the two fluxgates for horizontal component detection and comprises a plurality of magnetic thin films, having a length shorter than that of the fluxgates for horizontal component detection.

[Claim 2]

<1O5> The 3 axis thin film fluxgate as set forth in claim 1, wherein:

<1O6> the fluxgates for horizontal component detection comprise conductive coils for drive and pickup, a magnetic thin film, and an insulating thin film interposed between the coils and the magnetic thin film and configured to prevent electrical leakage between the coils and the magnetic thin film;

<iO7> the conductive coils are formed by electrically bringing an upper coil thin film and a lower coil thin film into contact with each other;

<iO8> the insulating thin film comprises a lower insulating film interposed between the lower coil thin film and the magnetic thin film, and an upper insulating film interposed between the upper coil thin film and the magnetic thin film; and

<1O9> the magnetic thin film is formed by laminating two types of materials having different magnetic characteristics.

[Claim 3]

<iio> The 3 axis thin film fluxgate as set forth in claim 2, wherein the lower coil thin film is formed by forming a groove, into which the lower coil thin film will be inserted, in an insulating film on a substrate formed on a OU

silicon wafer and then forming the lower coil thin film to a depth of the groove.

[Claim 4]

<πi> The 3 axis thin film fluxgate as set forth in claim 2, wherein the lower insulating thin film is formed of SiO₂ to a thickness ranging from 5,000

A (0.

5 μm) to 20,000 A (2 μm) . [Claim 5]

<ii2> The 3 axis thin film fluxgate as set forth in claim 2, wherein the magnetic thin film is formed by forming NiFe, that is, a magnetic material, to a specific thickness and then alternately forming an AI2O3 thin film, that is, an insulating material, the NiFe magnetic material thin film and the Al₂O₃ insulating thin film have a thickness range of 600+300 A and a thickness range of 150+100 A, respectively, and the magnetic thin film comprises at least three pairs of a laminated films when the NiFe magnetic material thin film and the AI2O₃ insulating thin film form a pair.

[Claim 6]

<ii3> The 3 axis thin film fluxgate as set forth in claim 2, wherein the magnetic thin film has a dumbbell shape both ends of which are wider than a central portion.

[Claim 7]

<ii4> The 3 axis thin film fluxgate as set forth in claim 6, wherein the magnetic thin film is provided with depressions formed in both ends thereof.

[Claim 8]

<ii5> The 3 axis thin film fluxgate as set forth in claim 2, wherein the drive coil and the pickup coil have a line width of 7+2 μm and are alternately disposed.

[Claim 9]

<ii6> The 3 axis thin film fluxgate as set forth in claim 2, wherein the drive coil and the pickup coil are disposed in such a way that only the drive coil is disposed in a specific area and only the pickup coil is disposed in a

01.

neighboring area, and the drive coil area and the pickup coil area are alternately arranged.

[Claim 10] <ii7> The 3 axis thin film fluxgate as set forth in claim 1, wherein the fluxgate for vertical component detection is configured such that one connected drive coil and one connected pickup coil are wound around the plurality of magnetic thin films.

[Claim 11] <ii8> The 3 axis thin film fluxgate as set forth in claim 10, wherein the magnetic thin film comprises a straight central portion and two semi-circular outer portions connected to the central portion, and has a "°°" configuration.

[Claim 12] <119> The 3 axis thin film fluxgate as set forth in claim 11, wherein the pickup coil is disposed around the central portion, and the drive coil is disposed around the outer portions.

[Claim 13] <i20> The 3 axis thin film fluxgate as set forth in claim 11, wherein the central portion and the outer portions have different magnetic characteristics.

[Claim 14] <i2i> The 3 axis thin film fluxgate as set forth in claim 13, wherein the central portion is constructed to have a laminated thin film configuration in which an NiFe ferromagnetic thin film has a thickness range of 600+300 A and an AI2O3 insulating thin film has a thickness range of 150+100 A, and each of the outer portions is constructed to have a laminated thin film configuration in which an NiFe ferromagnetic thin film has a thickness range of 1800+200 A and an Al₂O₃ insulating thin film has a thickness range of 150

+ 100 A. [Claim 15] <122> The 3 axis thin film fluxgate as set forth in claim 13, wherein the central portion and the outer portions are formed of laminated thin films using different magnetic materials. [Claim 16]

<123> The 3 axis thin film fluxgate as set forth in claim 13, wherein a magnitude of output peaks or a degree of a peak shift is controlled by adjusting widths of the central portion and the outer portions. [Claim 17]

<124> The 3 axis thin film fluxgate as set forth in claim 11, wherein the central portion is divided into two. [Claim 18]

<125> The 3 axis thin film fluxgate as set forth in claim 11, wherein the pickup coil is disposed around a center part of the central portion, and the drive coil is disposed around both ends of the central portion and the outer portions.