WO2020197312A1

WO2020197312A1 - Fluxgate magnetometer and manufacturing method therefor

Info

Publication number: WO2020197312A1
Application number: PCT/KR2020/004183
Authority: WO
Inventors: 장한성; 서주희; 박정원
Original assignee: 일진머티리얼즈 주식회사
Priority date: 2019-03-27
Filing date: 2020-03-27
Publication date: 2020-10-01
Also published as: KR20200115337A

Abstract

A fluxgate magnetometer and a manufacturing method therefor are disclosed. Lower coils, a lower structure, a magnetic bodies, an upper insulating film, and upper coils are sequentially stacked on a substrate insulating film on a substrate. The lower coils are embedded in respective grooves, which are in a plurality of rows for embedding the lower coils provided on the substrate insulating film. Each lower coil has an edge portion that is formed to be lower than the upper ends of the grooves for embedding the lower coils, such that a buffer groove is provided on the upper edge portion thereof. A flattening thin film may be formed by using an SOG composition or a fluid oxide material so as to fill the buffer groove, cover the substrate insulating film and the lower coils, and provide a flat surface, thereby absorbing stress due to differences in the thermal expansion rates of neighboring components. A lower insulating film may be further formed on the flattening thin film. The magnetic substance for a Z-axis fluxgate comprises: a linear pickup region; and a drive region which is branched from both ends of the pickup region to both sides and is formed in any one of an elliptical structure, a track structure formed of a combination of a straight section and a curved section, a rectangular structure, and a double U-shaped structure , and on which at least a drive coil is wound. The drive region may be formed in a two-stage structure such that the cross-sectional area thereof is larger than that of the pickup region.

Description

Fluxgate magnetometer and manufacturing method thereof

The present invention relates to a fluxgate magnetometer and a manufacturing method thereof, and more particularly, to a thin film fluxgate measuring an application direction and intensity of an external magnetic field, and a manufacturing method thereof.

Fluxgate Magnetometer (hereinafter simply referred to as'Fluxgate') is a type of magnetic sensor, and is used to search for buried materials containing steel such as mines or to detect the earth's magnetic field by being implemented as an electronic compass. It is a sensor. A fluxgate sensor including three fluxgates arranged in the X-axis, Y-axis and Z-axis directions, respectively, can detect the direction and strength of a magnetic field applied from the outside.

1A and 1B show a conventional rod-shaped and circular fluxgate, respectively. Referring to FIG. 1, the basic structure of the flux gate is a structure in which a drive coil 3 and a pickup coil 4 are wound around a magnetic body 1 surrounded by an insulating film 2. As an alternating current is applied to the drive coil 3, a voltage is induced in the pickup coil 4. The induced voltage is measured through a voltmeter V to detect the application direction and strength of the external magnetic field.

Typically, when there is no restriction on the height of a sensor to be implemented, a flux gate having a rod-shaped structure as shown in Fig. 1(a) may be used. However, there may be a limit on the height of a sensor to be implemented, such as when mounted on a chip applied to an electronic device such as a mobile phone. In such a case, a flux gate having a circular structure having a small height as shown in Fig. 1(b) is suitable as a flux gate for the Z-axis.

2 shows the internal structure of a conventional fluxgate. In order to manufacture the flux gate as shown in FIG. 2, a silicon wafer substrate formed with an insulating film 2 made of silicon oxide by a method such as high temperature oxidation is used. The lower coil 5 constituting the lower half of the drive coil 3 and/or the pickup coil 4 is formed on the surface of the insulating film 2 of the substrate. The lower coil 5 is formed of a metal material such as aluminum or copper having high electrical conductivity. A lower insulating film 6 made of a material such as SiO ₂ , Ta ₂ O ₅ , or Al ₂ O ₃ is formed on the upper end of the lower coil 5. A magnetic body 1 having ferromagnetic properties is formed on the upper end of the lower insulating film 6. The magnetic body 1 may have a structure in which several layers of NiFe are stacked. An upper insulating film 7 made of a material such as SiO ₂ , Ta ₂ O ₅ , or Al ₂ O ₃ is formed on the upper end of the magnetic body 1. And finally, the upper coil 9 constituting the upper half of the drive coil 3 and/or the pickup coil 4 is formed. Accordingly, a fluxgate magnetometer in which the lower coil 5 and the upper coil 9 surround the magnetic body 1 is completed.

FIG. 2(b) is a cross-sectional view in the direction AA′, which is the longitudinal direction of the flux gate shown in FIG. 2(a). As shown in Fig. 2(b), the flux gate is formed in a structure in which a lower coil 5, a lower insulating film 6, a magnetic material 1, an upper insulating film 7 and an upper coil 9 are stacked. The magnetic body 1 may be formed in a structure in which a plurality of magnetic thin films (eg, NiFe film) and a plurality of insulating interlayers (eg, SiO ₂ film, Ta ₂ O ₅ film, or Al ₂ O ₃ film) are alternately stacked. have. Further, a side insulating film 8 may be formed to prevent an electric short circuit between the side portion of the magnetic body 1 and the upper coil 9.

3 illustrates a three-axis fluxgate sensor (eg, an electronic compass chip) composed of an X-axis fluxgate 14, a Y-axis fluxgate 13, and a Z-axis fluxgate 12. 3, the X-axis fluxgate 14 and the Y-axis fluxgate 13 are implemented in a rod-shaped structure, and the Z-axis fluxgate 12 is implemented in a circular structure. Each fluxgate is combined with the fluxgate driving circuit 15 (ASIC) and die-bonded on the packaging PCB 10, and then epoxy molding 11 is performed to implement the three-axis fluxgate sensor shown in FIG. have.

Background art of the present invention is disclosed in Korean Patent Application Publication No. 10-2009-0029800 (published on March 23, 2009).

An object according to an aspect of the present invention is to introduce a structure capable of buffering the stress caused by the difference in the thermal expansion coefficient between the components, to prevent damage to the device in the manufacturing process and to improve through the implementation of a magnetic body with good characteristics. It is to provide a fluxgate device having performance and a method of manufacturing the same.

Another object of the present invention is to provide a fluxgate device having improved performance and a manufacturing method thereof through a structure capable of increasing the magnitude of a pickup voltage detected from a pickup coil under a condition that the minimum height of the fluxgate is maintained. will be.

The problem to be solved by the present invention is not limited to the above-described problems, and may be variously expanded without departing from the spirit and scope of the present invention.

A fluxgate magnetometer according to embodiments of the present invention for achieving the above objects includes a lower coil, a lower structure, a magnetic material, an upper insulating film, and an upper coil sequentially stacked on a substrate insulating film on a substrate. The lower coil is formed in a form buried in a plurality of rows of grooves for burying the lower coil provided in the substrate insulating film, and each lower coil has its own edge portion lower than the upper end of the lower coil burying groove to bury the lower coil. A buffer groove, which is an empty space, is formed above the edge portion near the upper end of the sidewall portion of the dragon groove. The lower structure is formed by using a spin-on-glass composition or material or a flowable oxide material to provide a flat surface while filling the buffer groove and covering the substrate insulating film and the lower coils. It includes a planarization thin film configured to buffer stress due to a difference in thermal expansion coefficient between neighboring components.

In an exemplary embodiment, each of the plurality of conductive lower coils has a height of a central portion of an upper surface substantially the same as a height of an upper end of the groove for filling the lower coil, and a height of the edge portion is lower than that of the central portion of the upper surface. A buffer groove may be provided.

In an exemplary embodiment, the lower structure may further include a lower insulating layer formed to provide insulation by being stacked on the planarized surface of the planarizing thin film.

In an exemplary embodiment, the lower insulating layer is formed of any of SiO ₂ , Ta ₂ O ₃ and Al ₂ O ₃ to prevent destruction of the planarization thin film due to compressive stress of the magnetic material during the process of the flux gate. It can be formed of one material.

In an exemplary embodiment, the lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape, and are induced by a drive coil for passing a drive current and a magnetic flux passing through it. It may be configured to separately form a pickup coil for detecting the pickup voltage.

In an exemplary embodiment, the magnetic material is a pick-up area magnetic material that extends in a straight line for a predetermined length and at least the pick-up coil is wound, and the pick-up area is branched in both directions from the upper and lower ends of the magnetic material, and has an elliptical structure or a straight section and a curved section. A land track-type structure consisting of a combination of, a square structure, and a drive area in which the pickup area is formed in any one of two U-shaped structures that face each other in an S shape connected to the magnetic body, and at least the drive coil is wound. It may contain a magnetic material.

In an exemplary embodiment, the drive coil may be further wound around the pickup area magnetic material in order to prevent a peak value of the pickup voltage from decreasing due to an externally applied magnetic field.

In an exemplary embodiment, a ratio of the number of turns between the drive coil and the pickup coin wound around the pickup area may be 1:1 or 1:2.

In an exemplary embodiment, the drive area magnetic material is stacked on a first stage drive area magnetic material having substantially the same thickness as the pickup area magnetic material, and the first stage drive area magnetic material, and has a cross-sectional area smaller than that of the first stage drive area magnetic material. It is formed of a two-stage magnetic body including the formed second-stage drive region magnetic body, and a sum of cross-sectional areas of the first and second-stage drive region magnetic bodies may be greater than the cross-sectional area of the pickup region magnetic body.

In an exemplary embodiment, the magnetic material has a structure in which a plurality of sets of magnetic layers are continuously stacked, and a set of magnetic layers may include a magnetic thin layer formed of a magnetic material and an insulating thin layer stacked thereon.

A fluxgate magnetometer according to another exemplary embodiment of the present invention to achieve the above objects includes a lower coil, a lower structure, a magnetic material, an upper insulating film, and an upper coil sequentially stacked on a substrate insulating film on a substrate. The lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape to detect a pickup voltage induced by a magnetic flux passing through a drive coil for passing a drive current. Separately form the pickup coil. The magnetic material is a pick-up area magnetic material that extends for a predetermined length in a straight line and at least the pick-up coil is wound; And a land track-type structure composed of a combination of a straight section and a curved section by branching from the upper and lower ends of the magnetic material in the pickup area, a rectangular structure, and two facing each other in a form connected to the magnetic material in the pickup area forming an S shape. It is formed in any one of the U-shaped structure, and at least includes a drive region magnetic material wound around the drive coil.

In an exemplary embodiment, the lower coil is formed to be buried in a plurality of rows of grooves for filling the lower coil provided in the substrate insulating layer, and each lower coil has its own edge portion lower than the upper end of the lower coil buried groove. It may be formed such that a buffer groove is provided on the edge portion near an upper end of the sidewall portion of the lower coil buried groove. The lower structure part is formed by using an SOG composition or a flowable oxide material to fill the buffer groove and provide a flat surface while covering the substrate insulating film and the lower coils, so that the difference in thermal expansion coefficient between neighboring components It may include a planarization thin film configured to buffer the resulting stress.

A fluxgate magnetometer according to still another embodiment of the present invention for achieving the above objects includes: a substrate; A substrate insulating film stacked on an upper surface of the substrate to provide insulation and having a plurality of rows of grooves for filling the lower coils formed on the upper surface; Each of the plurality of rows of lower coil embedding grooves is buried, and each edge portion is an empty space between the edge portion and the sidewall portion of the lower coil embedding groove by a step formed lower than the upper end surface of the lower coil embedding groove. A plurality of rows of lower coils formed to have buffer grooves; A planarization thin film filling the buffer groove and covering the substrate insulating layer and the plurality of rows of lower coils to provide a flat surface; And a lower insulating layer formed on the planarized surface of the planarizing thin film to provide insulation. A magnetic material stacked on the upper surface of the lower structure; An upper insulating layer covering the side and upper surfaces of the magnetic material to cooperate with the lower structure to insulate the magnetic material from the outside; And it includes a plurality of rows of upper coils formed to surround the upper surface and side surfaces of the upper insulating layer. The lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape to detect a pickup voltage induced by a magnetic flux passing through a drive coil for passing a drive current. Separately form the pickup coil. The magnetic body extends a predetermined length in a straight line, and at least the pickup area magnetic body around which the pickup coil is wound, and the pickup area magnetic body are branched in both directions at the upper and lower ends of the magnetic body in the pickup area, and are formed of an elliptical structure, or a combination of a straight section and a curved section. A track-shaped structure, a quadrangular structure, and a drive area magnetic material connected to the pickup area magnetic material is formed in any one of two U-shaped structures facing each other in an S shape, and at least the drive coil is wound.

In an exemplary embodiment, the planarization thin film is coated on the plurality of lower coils and the substrate insulating film while filling the buffer groove in a spin coating method in a sol state to form a flat surface, and after curing, hard gel It may be made of a material that is transformed into a gel) state and has physical properties capable of buffering the stress caused by the difference in the coefficient of thermal expansion between neighboring components.

In an exemplary embodiment, the planarization thin film may be formed of an SOG composition (spin-on-glass composition or material) or a flowable oxide material.

In an exemplary embodiment, the drive coil wound around the curved section of the magnetic body of the drive area magnetic body of the elliptical structure or the curved section of the drive area magnetic body of the land track structure and the two U-shaped structures is from the center of the radius of curvature to the outside. It may be formed to increase the line width as it goes.

On the other hand, the method of manufacturing a fluxgate magnetometer according to still another embodiment of the present invention for achieving the above objects is to manufacture a fluxgate magnetometer formed by sequentially stacking a lower coil, a lower structure part, a magnetic material, an upper insulating film, and an upper coil. That's the way. The manufacturing method includes the steps of forming a plurality of rows of grooves for burying lower coils in which the lower coils are to be formed in a substrate insulating film formed on a silicon wafer substrate; A plurality of rows of lower coils are formed in the form of being buried in the plurality of rows of lower coil embedding grooves, but the edge of each lower coil is formed lower than the upper end of the lower coil embedding groove, so that the sidewall of the lower coil embedding groove Forming a lower coil such that a plurality of buffer grooves in the form of empty spaces are provided above the edge portion near an upper end; And SOG composition or flowable oxide material is coated on the substrate insulating film and the lower coils while filling the buffer groove, performing spin coating to form a flat surface, and curing to form a hard gel state. And forming an understructure including the formed planarization thin film. The planarizing thin film has physical properties capable of buffering a stress caused by a difference in thermal expansion coefficient between neighboring components.

In an exemplary embodiment, in the forming of the lower coil, a conductive metal is sputtered on the plurality of rows of lower coil embedding grooves while the photoresist is coated, so that the height of the central part is It is substantially the same as the upper end, and the height of the edge portion is lower than the central portion to form a lower coil having a surface profile in which the buffer groove is provided.

In an exemplary embodiment, in the forming of the groove for filling the lower coil, the lower coil is formed by performing a primary etching on an etching region on the substrate insulating layer that is not coated with a photoresist (PR). Forming a primary region; And forming the lower coil embedding groove in a structure in which the inlet edge of the lower coil embedding groove is covered by the photoresist by additionally performing a second etching on the first region to expand the first region. It may include.

In an exemplary embodiment, the first etching may be performed through a dry etching process, and the second etching may be performed through wet etching.

In an exemplary embodiment, in the forming of the groove for burying the lower coil, a portion of the lateral tip of the photoresist covering the inlet of the groove for burying the lower coil is removed through additional dry etching, and then the groove for burying the lower coil is removed. It may include the step of forming the lower coil.

In an exemplary embodiment, the manufacturing method further includes forming a lower insulating layer to be stacked on the planarizing thin film as a part of the lower structure with any one of SiO ₂ , Ta ₂ O ₃ and Al ₂ O ₃ . can do. The lower insulating layer may prevent destruction of the planarization thin film due to compressive stress of the magnetic material during the manufacturing process of the fluxgate magnetometer, and may provide insulation.

In an exemplary embodiment, in the manufacturing method, the magnetic material is formed in a structure in which a plurality of magnetic material films are continuously stacked on the lower structure part, and the magnetic material film of one set is a magnetic thin film formed of a magnetic material and an insulating thin film laminated thereon. Forming the magnetic material to include; And forming the upper insulating layer formed so as to surround the upper surface and the side surface of the magnetic material so as to completely surround and insulate the magnetic material in cooperation with the lower structure.

In an exemplary embodiment, in the manufacturing method, an upper coil connected to the lower coils is formed to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape, and pass through a drive coil for passing a drive current. It may further include a step of separately forming a pickup coil for detecting the pickup voltage induced by the magnetic flux.

In an exemplary embodiment, the forming of the magnetic body includes a pickup area magnetic body in which the magnetic body extends in a linear shape for a predetermined length and at least the pickup coil is wound, and the pickup area magnetic body is branched in both directions at the upper and lower ends of the magnetic body. A structure, or a track-type structure consisting of a combination of a straight section and a curved section, a square structure, and one of two U-shaped structures facing each other in which the shape connected to the pickup area magnetic body forms an S-shape, and at least It may be formed to include a drive area magnetic material wound around the drive coil.

In an exemplary embodiment, in the forming of the magnetic material, the drive area magnetic material is stacked on a first stage drive area magnetic material having a thickness substantially the same as the pickup area magnetic material, and the first stage drive area magnetic material Forming a two-stage magnetic material to include a second-stage drive area magnetic material formed smaller than the first-stage drive area magnetic material, wherein the sum of the cross-sectional areas of the first-stage drive area magnetic material is the pickup area magnetic material Can be larger than the cross-sectional area of

According to an aspect of the present invention, a buffer groove formed through a stepped structure between both ends of a lower coil incompletely buried in a trench structure formed in an insulating layer of a substrate and a sidewall of the trench structure is formed. A lower structure of a two-layer structure comprising a planarization film layer that fills the buffer groove and provides a flat surface and a lower insulating film layer stacked thereon is formed. The planarizing thin film layer of the lower structure can buffer stress caused by a difference in thermal expansion coefficient between the constituent layers in the process of manufacturing the fluxgate. Accordingly, it is possible to improve the performance of the fluxgate by preventing the magnetic properties of the magnetic material from deteriorating due to damage or cracking of components during the manufacturing process.

In addition, the magnetic material of the Z-axis fluxgate is a land track-type structure composed of a bar-structured pickup area and an elliptical structure, or a combination of a straight section and a curved section, and a square structure, and the shape connected to the pickup area magnetic material forms an S-shape. It includes two U-shaped drive areas facing each other. According to the present invention, (i) the radius of curvature or the line width of the drive coil can be optimized, or the drive area can be greatly enlarged so that the drive coil can be wound as much as possible or the winding density can be increased. In particular, a drive region having a straight section orthogonal to the pickup region can maximize an area capable of winding a coil, and thus the amount of driving magnetic flux can be greatly increased. (ii) The drive area has a larger cross-sectional area than the pickup area by introducing the drive area of a two-tiered structure. Thereby, a large amount of magnetic flux can be transmitted to the pickup area. (iii) Wind the pickup coil as well as the drive coil in the pickup area. By employing these various structural features, it is possible to greatly increase the driving magnetic flux generated in the drive area, more driving magnetic flux can be introduced into the pickup area, and the intensity of the pickup voltage detected in the pickup area can be enhanced. Even if an external magnetic field is applied to the pickup region, it is possible to keep the spin direction of the atoms of the magnetic material in the pickup region in the longitudinal direction (Z direction) of the pickup region. As a result, it is possible to improve the performance of the Z-axis fluxgate by increasing the pickup voltage detected by the pickup coil under the condition that the minimum height of the Z-axis fluxgate is maintained.

1 and 2 are exemplary views showing the basic structure of a conventional flux gate.

3 is an exemplary view showing a conventional 3-axis fluxgate sensor composed of an X-axis fluxgate, a Y-axis fluxgate, and a Z-axis fluxgate.

4 is an exemplary view showing an operation process of a flux gate according to an embodiment of the present invention.

5 to 9 are exemplary views showing problems in the process of a conventional flux gate to be solved through the structure of the flux gate according to the first embodiment of the present invention.

10 is a flowchart illustrating a method of manufacturing a fluxgate according to the first embodiment of the present invention.

11 is an exemplary view showing a process of manufacturing a fluxgate according to the first embodiment of the present invention.

12 to 14 are diagrams for explaining in detail a process of forming a lower structure part in a flux gate according to the first embodiment of the present invention, and FIG. 12 is a structure of a magnetic material formed by a planarizing thin film employed to fill a buffer groove. Fig. 13 schematically shows that the flattening thin film may be damaged by compressive stress of a magnetic material, and Fig. 14 is a buffer groove formed by a step difference between the substrate insulating layer and the lower coil, filled with SOC material, etc. An example of a fluxgate structure with improved stress resistance by introducing a planarizing thin film is illustrated.

15 is a view for explaining a structure of a circular magnetic body of a conventional Z-axis fluxgate, a winding form of a drive coil, and a form of generating magnetic lines of force.

Fig. 16 shows the magnetic structure of the Z-axis fluxgate and the winding form of the coil according to the second embodiment of the present invention in comparison with the conventional one.

17 and 18 illustrate a wet etching process for a planarization thin film in a flux gate according to a second embodiment of the present invention.

19 to 24 illustrate a magnetic structure of a Z-axis fluxgate and a winding type of a coil according to various other embodiments of the present invention.

FIG. 25 exemplifies a configuration in which the pickup coil and the drive coil are actually wound in the pickup area of the structure shown in FIG.

Fig. 26 exemplifies a form in which a pickup coil and a drive coil are actually wound in the pickup area of the structure shown in Fig. 22.

Fig. 27 illustrates a structure of a land track type magnetic body in which a drive region is formed of a magnetic thin film having a two-stage structure according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance. In addition, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component.

The first embodiment of the present invention is a thin-film fluxgate capable of improving the performance of a fluxgate by preventing a decrease in magnetic properties of a magnetic material due to cracks or breakages due to a difference in thermal expansion coefficient between components in the process of manufacturing a fluxgate. We present the structure of and how to manufacture it.

4 is a diagram for explaining the operation principle of the flux gate, and FIGS. 5 to 9 illustrate problems in the manufacturing process of the conventional flux gate to be solved through the structure of the flux gate according to the first embodiment of the present invention. It is a drawing to do. In order to aid in understanding the first embodiment, the principle of operation of the fluxgate will be described first with reference to FIG. 4. Hereinafter, the term "fluxgate" refers to a fluxgate magnetometer or an X-axis fluxgate device, a Y-axis fluxgate device, or a Z-axis fluxgate device constituting the fluxgate magnetometer.

In order to operate the fluxgate, an alternating current must flow through the drive coil. Depending on the direction of the current, a magnetic field is formed inside the drive coil according to the right-hand rule of amperes. The magnetic field flows into the magnetic body inside the drive coil, and makes the spin direction of the atoms constituting the magnetic body directed toward the magnetic field created by the drive coil. When the direction of the current flowing through the drive coil is reversed, the direction of the magnetic field of the drive coil is also reversed. Accordingly, the spin direction of the atoms inside the magnetic body is also directed in the opposite direction. At the moment such magnetization reversal occurs, voltage is induced to the pickup coil wound around the pickup area. The pickup voltage is output in the form of an isolated voltage peak through the pickup coil pad 122.

Figures 4(a), (d), and (g) conceptually show the structure of a general rod-shaped and circular fluxgate, and Figures 4(b), (e), and (h) are magnetic materials constituting each fluxgate. Represents a hysteresis loop, or magnetization-magnetic field (MH) loop according to the magnetic characteristics of, and Figs.4(c), (f), and (i) are the pickup voltages generated in the pickup coil (4). Shows the waveform of

First, a case where no externally applied magnetic field exists will be described with reference to FIGS. 4(a), (b), and (c). When an alternating current, for example, a triangular wave current represented by the dotted line in Fig. 4(c) is input to the drive coil 3, a magnetic field is formed inside the drive coil 3, and the direction of the magnetic field is periodically reversed. Whenever the direction of the magnetic field is reversed, a voltage (hereinafter, referred to as “pickup voltage”) is induced in the pickup coil 4. The pickup voltage is output in the form of a voltage peak indicated by a solid line in Fig. 4(c). The reason why the voltage peak in the form of an impulse wave (or triangular wave) is generated is because the waveform of the pickup voltage induced in the pickup coil 4 is proportional to the amount of change in the magnetization value (that is, dM/dt) with respect to time change.

When a triangular wave current is input to the drive coil 3, the magnetization curve of the magnetic body 1 inside the fluxgate follows the trajectory of the order ① to ⑧ in Fig. 4(b). In the section ②~③ where the magnetization direction of the magnetic body (1) changes from -M to +M, the first voltage peak occurs due to a sudden change in magnetization value (2M), and the cycle of triangular wave current is completed. The first voltage peak and the second voltage peak in which the sign is opposite occurs.

4(d), (e), and (f) show a case where an external magnetic field is applied from left to right of the flux gate. When an external magnetic field from left to right is applied to the fluxgate, the MH loop formed in the magnetic body 1 is shifted to the right by the amount of the external magnetic field applied to the magnetic body 1 as shown in Fig. 4(e). shift). In that state, when a triangular wave current is input to the drive coil 3, the distance between the peaks of the first and second voltages detected by the pickup coil 4, that is, the first and second voltages, as shown in Fig. 4(f). The time interval at which the peak occurs decreases.

4(g), (h), and (i) show cases where an external magnetic field is applied from the right to the left of the flux gate. The same principle as in Figs. 4(d), (e), and (f) is applied, and in this case, the distance between the first and second voltage peaks, that is, the first and second voltage peaks, is opposite to the previous case. The time interval will increase.

According to this principle of operation, by using the pickup voltages induced in each of the pickup coils of the X-axis, Y-axis, and Z-axis fluxgates, the X-axis, Y-axis and Z-axis components of the externally applied magnetic field can be measured, from which The external applied magnetic field vector is known.

Next, a technical problem of the flux gate according to the first embodiment of the present invention will be described in detail with reference to FIGS. 5 to 9.

5 shows a general process procedure for manufacturing a fluxgate. Through a photolithography process and a wet etching process for the metal thin film for the lower coil, the lower coil 5 is protruded from the substrate insulating film 17 (Silicon Oxide) on the silicon wafer substrate 16. To form (see Fig. 5(a)). A lower insulating film 6 is deposited on the protruding lower coil 5 (see Fig. 5(b)). At this time, the upper surface of the lower insulating film 6 has an uneven surface by the lower coil 5. The protruding portion of the lower insulating layer 6 is planarized through a chemical mechanical polishing (CMP) process (see FIG. 5(c)). Thereafter, the magnetic body 1 is formed on the planarized lower insulating film 6 (see Fig. 5(d)), and the upper insulating film 7 and the upper coil 9 are sequentially formed thereon (Fig. 5(e)). And (f)) the fluxgate is completed.

FIG. 6 shows the CMP process of FIG. 5C, that is, a process of polishing the protruding portion of the lower insulating layer 6 through the CMP process.

Referring to Fig. 6, the protruding portion of the lower insulating film 6 is disposed to face the CMP plate 19 (lapping plate of CMP equipment) to which the CMP abrasive 20 is supplied. In that state, a heavy CMP load 18 is applied to the back side of the silicon wafer substrate 16 to polish the protruding portion of the lower insulating film 6. When performing the CMP process in this way, the lower insulating film 6 at the upper end of the lower coil 5 formed of a metal material such as aluminum with low hardness is pushed toward the silicon wafer substrate 16, thereby forming the lower insulating film 6 Cracks 21 may occur.

In order to prevent the occurrence of cracks in the lower insulating film 6 according to the CMP process, a method of forming the lower insulating film 6 as thick as possible may be considered. However, in this case, since the distance between the lower coil 5 and the magnetic body 1 is increased, magnetization reversal of the magnetic body by the magnetic field formed in the drive coil 3 becomes difficult. Further, as the distance between the pickup coil 4 and the magnetic body 1 constituted by the lower coil 5 increases, the magnitude of the voltage peak induced into the pickup coil 4 when the magnetization in the magnetic body 1 is reversed is also Becomes smaller. Due to these problems, the ability of the fluxgate to detect changes in the external magnetic field is degraded.

7 shows an additional problem caused by the CMP process described above.

Referring to FIG. 7, when the lower insulating layer 6 in the state of FIG. 7 (a) is planarized by a CMP process, the lower insulating layer 6 that is flattened as shown in FIG. 7 (b) can be obtained. By the way, as for the polishing amount (c) of the CMP process, the polishing amount E1 at the center portion of the silicon wafer substrate 16 is generally greater than the polishing amount E2 at the outer portion. Therefore, the thickness of the lower insulating film 6 of the fluxgate fabricated at the outer portion of the silicon wafer substrate 16 is thicker than the lower insulating film 6 of the fluxgate fabricated at the center portion of the silicon wafer substrate 16. Accordingly, the flux gate manufactured at the outer portion of the silicon wafer substrate 16 has a poorer external magnetic field sensing characteristic than the flux gate manufactured at the central portion of the silicon wafer substrate 16. Even if the outer portion of the silicon wafer substrate 16 is separated by the same distance from the center of the silicon wafer substrate 16, the thickness of the lower insulating layer 6 may not be formed equally due to the difference in the amount of polishing for each outer portion. As such, there may be a problem in that the electrical characteristics of each fluxgate manufactured on the same silicon wafer substrate 16 are not uniform because there is a process variation according to the position.

FIG. 8 is a diagram for explaining a problem of deterioration in performance of a fluxgate due to a difference in thermal expansion characteristics for each component of a fluxgate on an extension of the fluxgate process described with reference to FIGS. 5 to 7.

Referring to FIG. 8, when the magnetic body 1 is formed on the lower coil 5 formed in a protruding shape using a conductive metal such as aluminum or copper on the silicon wafer substrate 16, the lower structure (ie, the lower coil Changes in the magnetic properties of the magnetic body 1 according to changes in (5) and the lower insulating film 6 are shown.

In the state where the lower insulating film 6 is formed on the lower coil 5 (see Fig. 8(a)), the magnetic body 1 may be formed on the lower insulating film 6 through a sputtering process or the like. At that time, a thermal expansion phenomenon may occur (see Fig. 8(b)). The sputtering process, which is mainly used in the process of depositing a thin film of the fluxgate, generates a lot of heat during the process. The lower coil 5 may be mainly formed of aluminum. The coefficient of thermal expansion (α) of aluminum is 2.5*10 ^-5 /℃. Components of other materials around the lower coil 5 made of aluminum have coefficients of thermal expansion that are at least 10 to 100 times smaller than that of aluminum (α _NiFe = 7.7*10 ^-6 /°C, α _SiO2 = 5.5. *10 ^-7 /℃, α _Siwafer = 2.6*10 ^-6 /℃, α _Ta2O5 = 3.6*10 ^-6 /℃, α _Al2O3 = 7.2*10 ^-6 /℃). That is, at the same temperature change, the lower coil 5 made of aluminum undergoes thermal expansion at least 10 to 100 times or more than other elements of other materials around it (①-->② in Fig. 8(b)).

The expanded lower coil 5 expands the lower insulating film 6 continuously formed thereon. The magnetic body 1 is formed on the expanded lower insulating film 6. Since the magnetic material 1 formed at this time is formed through a sputtering process performed in a high temperature environment, the lattice parameter, which is the distance between atoms of the NiFe magnetic material 1, is formed in a state of a wider distance as it is formed at a high temperature. do. When the film formation of the magnetic body 1 is completed, the temperature of the silicon wafer substrate 16 is lowered. At this time, the lower coil 5 formed of aluminum is greatly reduced (condensed), and accordingly, the lower insulating film 6 formed on the lower coil 5 and the magnetic material 1 deposited on the lower insulating film 6 are also condensed. . As a result, compressive stress is generated inside the magnetic body 1 (see Fig. 8(c)). Considering that the NiFe magnetic material 1 is formed in a high-temperature sputtering process environment and its lattice constant is large, when the temperature of the magnetic material 1 decreases after the sputtering process is completed, it has been formed at a large value in the high-temperature sputtering process environment. The lattice constant decreases. Accordingly, in the magnetic body 1, not only compressive stress due to condensation of the lower insulating film 6 but also natural compressive stress due to a decrease in the lattice constant is additionally generated.

8D and 8E show the state of compressive stress for each position of the magnetic body 1 formed on the lower coil 5 and the lower insulating film 6. The magnetic body 22 formed on the lower coil 5 made of a metal material such as aluminum having a high coefficient of thermal expansion (corresponding to the area A'in Fig. 8(d)) is the area of the substrate insulating film 17 where the lower coil 5 is not formed. It is subjected to a higher compressive stress than the magnetic body 23 formed thereon (corresponding to region B'in Fig. 8(d)).

The compressive stress applied to the magnetic body 23 formed in the region B'in Fig. 8(d) is very slight. Therefore, as shown in B'of Fig. 8(e), in a section in which the magnetization direction of the magnetic body 23 changes, the M-H loop has a sharp inclination (that is, a change in magnetization value occurs). On the other hand, the NiFe alloy used as the magnetic body 1 has a characteristic that the M-H loop greatly changes depending on the applied stress. Therefore, when compressive stress is applied to the magnetic body 22 formed in the region A'in Fig. 8(d), the slope of the MH loop in the section in which the magnetization direction of the magnetic body 22 changes is MH corresponding to B' It is gentler than the slope of the loop.

Therefore, as can be seen from Fig. 8(f), the voltage peak of the pickup coil 4 formed by the magnetic body 23 without compressive stress is formed as a high voltage peak value of the shape B'in Fig. 8(f). Since the driving circuit 15 can easily read the position of the high voltage peak, it is possible to improve the ability of the flux gate to sense an external magnetic field. On the other hand, since the voltage peak of the pickup coil 4 formed by the magnetic material 22 processed in the state in which the compressive stress is formed is formed with a greatly reduced voltage peak value in the shape A'in Fig. 8(f), the driving circuit ( 15) It becomes difficult to read the position of the small voltage peak, so the fluxgate's ability to sense the external magnetic field is greatly degraded.

9 shows an example of a manufacturing process of a flux gate different from that of FIG. 5.

Specifically, a plurality of trenches in which the lower coil 5 is to be installed are formed on the surface of the substrate insulating layer 17 formed on the silicon wafer substrate 16 through a photolithography process and a dry etching process. A lower coil 5 made of a conductive metal such as aluminum or copper is formed in the formed groove using a method such as a sputtering process. Using a solvent such as acetone, photoresist (PR: Photo Resist, 24) and the conductive metal deposited thereon are removed together. Then, the protruding portion 25 of the lower coil 5 is removed through a CMP process to planarize the surface.

In this case, the hardness of the lower coil 5, that is, a conductive metal such as aluminum or copper, is lower than that of the substrate insulating film 17 (i.e., silicon oxide) around the lower coil 5, and abrasion resistance to the CMP abrasive 20 is significantly lower. . Therefore, the lower coil 5 is preferentially worn during the planarization process according to the CMP process. After the CMP process, the lower structure of the fluxgate has a wavy structure 26 having an amplitude of at least 500Å, such as a wavy structure. Accordingly, the lower insulating film 6 and the magnetic body 1 formed thereon also have a wavy structure 26 ′, and thus, the consistency of the magnetization reversal of the magnetic body 1 is deteriorated.

Further, during the CMP process, the protruding portion 25 of the lower coil 5 having low hardness and abrasion resistance may fall off. In the process, deep scratches are generated in the lower coil 5 formed on the substrate insulating layer 17. Scratches generated in the lower coil 5 may cause detachment and breakage of the lower insulating film 6 and the magnetic material 1 formed on the lower coil 5 in a subsequent process.

The problems of the conventional fluxgate reviewed above are summarized as follows.

First, the process of the flux gate according to FIGS. 5 to 8 includes a CMP process for removing the protruding portion of the lower insulating layer 6. Due to the CMP process, a crack 21 may occur in the lower insulating film 6 on the upper end of the lower coil 5 with weak hardness, resulting in a problem of destruction. Second, the method of increasing the thickness of the lower insulating film 6 to prevent damage to the lower insulating film 6 is that the sensing ability of the magnetization reversal deteriorates as the coils sensing the magnetization reversal characteristics of the magnetic body 1 are located farther away. Thus, the voltage peak of the pickup coil 4 is reduced. As a result, the ability of the fluxgate to sense an external magnetic field may be degraded. Third, since the amount of polishing by the CMP process varies depending on the position of the silicon wafer substrate 16, the electrical characteristics of each fluxgate manufactured on the same silicon wafer substrate 16 are uneven according to the position on the substrate wafer 16. It is made to be. Fourth, thermal expansion and condensation of the lower coil 5 due to a change in the process temperature caused in the manufacturing process of the fluxgate creates a compressive stress in the magnetic body 1 and deteriorates the magnetization reversal characteristics of the magnetic body 1. The resulting smaller output voltage peak degrades the fluxgate's ability to sense external magnetic fields.

In addition, the manufacturing process of the flux gate shown in FIG. 9 includes a CMP process for removing the protruding portion 25 of the lower coil 5. Due to the CMP process, the lower structure of the fluxgate is formed into wavy structures 26 and 26', resulting in a problem that the consistency of the magnetization reversal of the magnetic body 1 is deteriorated. In addition, the protruding portion 25 of the lower coil 5 removed during the CMP process may cause scratches on the lower coil 5. As a result, the lower insulating film 6 and the magnetic material 1 may be detached and damaged due to peeling.

Accordingly, exemplary embodiments of the present invention eliminate the CMP process in the manufacturing process of the flux gate, prevent formation of the protruding portion 25 of the lower insulating film 6 or the lower coil 5, and flatten the lower structure. We propose a way to achieve this. To this end, exemplary embodiments may improve the magnetization reversal characteristic of the magnetic body 1 by compensating for thermal expansion of each layer due to a change in the process temperature of the flux gate and removing compressive stress of the magnetic body 1. Accordingly, a method of manufacturing a fluxgate capable of improving the external magnetic field sensing performance of the fluxgate as a minimum device size, and a structure of the fluxgate according to the method are presented.

FIG. 10 is a flowchart for explaining a method of manufacturing a flux gate according to the first embodiment of the present invention, and FIG. 11 is an exemplary view showing a process of manufacturing a flux gate according to the first embodiment of the present invention, and FIG. 12 14 to 14 are exemplary views for explaining in detail a process of forming a lower structure part in a flux gate according to the first embodiment of the present invention.

10 to 14, the fluxgate according to the first embodiment has a lower coil 5, a

lower structure

35 and 6, a magnetic body 1, and an upper part on the substrate insulating film 17 on the surface of the substrate 16. The insulating film 7 and the upper coil 9 may be sequentially stacked to be formed.

The lower structure may include a planarization thin film 35 and a lower insulating layer 6 as described later. The lower coil 5, the lower insulating film 6, the magnetic body 1, the upper insulating film 7 and the upper coil 9 may have the same material as the conventional flux gate described through the above-described process. The planarization thin film 35 is coated on the plurality of lower coils and the substrate insulating film while filling the buffer groove in a spin coating method in a sol state to form a flat surface, cured and transformed into a hard gel state. As a result, it can be formed as a material having physical properties capable of buffering the stress caused by the difference in the coefficient of thermal expansion between neighboring components. A method of manufacturing a fluxgate according to the present embodiment will be described based on the above contents.

First, a groove 31 for filling a lower coil having a trench structure in which the lower coil 5 is to be formed is formed in the substrate insulating film 17 (silicon oxide) formed on the silicon wafer substrate 16 (S100) (Fig. 11(a) to (d)). The lower coil (ie, a thin film forming the lower coil, hereinafter referred to as the term of the lower coil) may be embedded in the lower coil buried groove 31 (S200) (Figs. 11(e) to ( g)). As described above, the lower coil 5 may be formed of a conductive material such as aluminum or copper, and the drive coil 3 to which a triangular wave current is applied together with the upper coil 9 and the pickup coil 4 at which a voltage peak is formed. ) Can be configured.

Step S100 will be described in detail with reference to FIG. 11, in a state in which the photoresist 24 is coated on the silicon wafer substrate 16 on which the substrate insulating film 17 is formed (FIG. 11(a)), the lower coil 5 The photoresist 24 on the region to be formed (that is, the groove 31 for filling the lower coil) is removed through a photolithography process (Fig. 11(b)). Thereafter, the groove 31 for filling the lower coil is formed through an etching process (FIGS. 11(c) to (d)). The groove 31 for filling the lower coil may be formed in a plurality of rows.

In an exemplary embodiment, the groove 31 for filling each lower coil may be formed by performing a two-step etching process. First, after applying the photoresist 24 on the surface of the substrate insulating film 17 (Fig. 11(a)), the photoresist applied to the region where the groove 31 for filling the lower coil will be formed through a photolithography process ( 24) is removed (Fig. 11(b)). A first region 30 in which the lower coil 5 is to be formed may be formed by performing a first etching on the region on the substrate insulating layer 17 from which the photoresist 24 has been removed (Fig. 11(c)). )). In an exemplary embodiment, the first etching may be performed by a dry etching process. The primary region 30 is a region in which a region under a portion of the substrate insulating layer 17 to which the photoresist 24 is not applied is etched in a trench structure.

A second etching process may be further performed on the first region 30. The secondary etching may be performed by a wet etching process. Wet etching may be performed, for example, by using a BOE (Buffered Oxide Etcher) solution capable of dissolving the substrate insulating layer 17. The sidewalls and the bottom of the primary region 30 may be further carved out through the secondary etching, so that the width and depth of the groove of the primary region 30 may be expanded. As a result, the groove 31 for filling the lower coil that is enlarged compared to the primary region may be formed (Fig. 11(d)). That is, by the two-step etching, the sidewall of the lower coil burial groove 31 is further penetrated by a predetermined width d below the photoresist 24, so that the inlet edge portion of the lower coil burial groove 31 It may be formed in a groove structure covered by the photoresist 24.

After step S100, a plurality of lower coils 5 may be formed in a form in which each of the plurality of lower coils is buried in the plurality of lower coil buried grooves 31 (S200).

In an exemplary embodiment, the lower coil 5 may be formed by depositing metal particles such as aluminum or copper in the groove 31 for filling the lower coil by a sputtering process. At this time, as shown in Figs. 11(f) and (g), the edge of the lower coil 5 in contact with the sidewall of the substrate insulating film 17 is lower than the top surface of the lower coil buried groove 31 so that a step can be made. I can. Due to the step difference, a buffer groove 32, which is an empty space, may be provided between the edge portion of the lower coil 5 and the sidewall portion of the lower coil filling groove 31. That is, each lower coil 5 may have a higher edge portion surrounding itself in the center portion. That is, each lower coil 5 may have a downwardly inclined surface structure whose height decreases from a center portion to an edge portion. The center portion of each lower coil 5 may be formed substantially equal to the height of the top surface of the lower coil buried groove 31.

In the structure of Fig. 11(d), when the lower coil 5 is formed through a sputtering process, the groove 31 for filling the lower coil without contact with the photoresist 24 and the metal (eg, aluminum) thin film formed thereon It is possible to form the lower coil (5). In this state, when the photoresist 24 is removed using a solvent such as acetone, the lower coil 5 is not formed with the protruding portion 25 as shown in Fig. 9(d), and the lower coil buried groove 31 ) Can be formed. Further, a side end portion of the photoresist 24 covering the edge of the inlet portion of the lower coil buried groove 31 may function as a structural mask for the sputtering process. Due to the mask function, the edge portion of the lower coil 5 is formed in a downwardly inclined surface structure, and a step is formed with the sidewall portion of the substrate insulating layer 17, thereby forming an empty space of the buffer groove 32.

However, when the above-described process is performed, the inner surfaces of the wet-etched substrate insulating layer 17, that is, the sidewall portions of the lower coil burial groove 31 may have a porous surface due to wet etching. When the lower coil 5 is formed immediately after wet etching, the adhesion between the lower coil buried groove 31 and the lower coil 5 may be reduced. If the buffer groove 32 is too large, the structural robustness of the fluxgate element may be disadvantageous. The buffer groove 32 sufficiently prevents cracking or breakage due to the difference in thermal expansion coefficient between the lower coil 5, the

lower structure parts

6 and 35 and the magnetic body 1 in the process of the fluxgate element (to be described later), and a flattening thin film It is necessary to make the appropriate size so that the flattening of the substructure by (35) can be achieved.

In an exemplary embodiment, in order to improve the surface structure of the lower coil embedding groove 31 that reduces the adhesion of the lower coil 5 and minimize the size (width and depth) of the buffer groove 32, the lower coil ( In step S200 of forming 5), a part of the lateral front end of the photoresist 24 covering the inlet of the lower coil buried groove 31 may be removed through dry etching. Then, the lower coil 5 may be formed in the lower coil buried groove 31. That is, after performing the two-step etching process (ie, dry etching and wet etching process) of step S100, a dry etching process may be additionally performed. As a result, the uneven silicon oxide structure of the lower coil buried groove 31 is cleaned, and at the same time, a part of the lateral tip of the photoresist 24, as shown in Fig. 11(e), protrudes by a width d formed by wet etching. Some protrusions of the photoresist 24 may be removed. As much as the final side end of the photoresist 24 retreats toward the boundary of the lower coil embedding groove 31 (that is, the lateral end of the photoresist 24 protrudes toward the side wall of the lower coil embedding groove 31) The size of the structural mask part for the sputtering process for forming the lower coil 5 and the lower coil 5 is reduced, and as a result, the size of the buffer groove 32 can be made narrower by that amount.

FIG. 11(f) shows a structure in which the lower coil 5 is formed in the groove 31 for filling the lower coil formed through the above-described first dry etching, second wet etching, and third dry etching. Thereafter, when the photoresist 24 and the aluminum thin film thereon are removed through a solvent such as acetone, as shown in Fig. 11(g), a buffer groove 32 is formed at the boundary line between the lower coil 5 and the substrate insulating film 17. In the formed state, the lower coil 5 may be formed.

The buffer groove 32 formed as described above may contribute to compensating for a difference in thermal expansion between the lower coil 5, the lower structure, and the magnetic body 1 in a subsequent process of the fluxgate element. That is, in the process of forming the magnetic body 1 through a sputtering process in a high-temperature environment, the lower coil 5 is expanded by the walls on both sides of the substrate insulating film 17 forming the boundary of the lower coil buried groove 31. This can be limited. At this time, the limit of the expansion is buffered by the buffer groove 32, so that the lower coil 5 maintains its physical properties and does not cause expansion of the planarization thin film 35 and the lower insulating film 6 to be described later. It can be expanded to a certain degree. Even if there is a change in the process temperature of the flux gate, expansion and condensation of the magnetic body 1 does not occur due to the buffering function of the buffer groove 32 and the flattening thin film 35. As a result, since the magnetization reversal characteristic of the magnetic body 1 can be improved, the external magnetic field sensing performance of the flux gate can be improved. Fig. 11(h) shows the actual measurement specifications of the lower coil 5 when manufactured according to the actual specifications of the fluxgate. The width and depth of the buffer groove 32 may be adjusted by adjusting the dry etching process time in step S200.

After the lower coil 5 is formed through the step S200, the lower structure may be formed (S300). In an exemplary embodiment, as illustrated in FIG. 12B or 14, the lower structure may include a planarization thin film 35. In step S300, a planarization thin film 35 may be formed using a predetermined planarization material. The flattening thin film 35 may be stacked on the substrate insulating layer and the lower coil 5 while filling the buffer groove 32 formed in step S200 to form a flat surface.

In an exemplary embodiment, the planarization thin film 35 may be an SOG material layer formed by using an SOG material as the predetermined planarization material. SOG materials can be largely classified into silicate-based compounds, organosilicon compounds, and dopant-organic compounds (e.g.) with regard to their constituent materials. All of these SOG compositions can be used in the present invention. The SOG composition made of an organosilicon compound can be seen to have optimal properties for the present invention. The material used to form the planarization thin film 35 may also include a material having substantially equivalent or similar properties to the SOG material. Flowable oxide materials with good gap-fill properties can be viewed as materials with such equivalent properties. Examples of flowable oxides include silicate-based oxides such as TEOS (tetra ethoxysilane), USG (undoped silicate glass), BSG (boron doped silicate glass), PSG (phosphorous doped silicate glass), and BPSG (boron doped phosphosilicate glass). , Or TEOS and USG films, and the like, and commercialized products include, for example, FOx products of Dow Corning. This fluent oxide can also be viewed as an SOG material in the broadest sense.

In an exemplary embodiment, in order to form the planarization thin film 35 from the SOG composition (or its equivalent), first, a liquid SOG composition (glass melted with an organic solvent) is first mixed with the substrate insulating film 17 and the lower coil 5 A thin coating film is formed by spin coating on the uneven surface. At this time, the liquid SOG composition flows into the buffer groove 32 to form a coating film in a state that is completely filled. During the process, the viscosity of the liquid SOG composition increases rapidly, and the surface of the coating film becomes flat despite the uneven surface. Thereafter, through several stages of heat treatment, volatile components such as a solvent constituting the SOG composition are discharged, and the silica (SiO ₂ ) component mainly remains. That is, the SOG composition is applied by rotation in the first sol state, then transformed into a sticky gel state, and finally a hard gel state coating film through high temperature heat treatment at 400 to 500°C. Can be changed to

The SOG flattening thin film 35, which has been changed so hard, may serve as an insulating layer or a dielectric layer inside the fluxgate device, and may also serve as a buffer layer that buffers stress due to a difference in coefficient of thermal expansion between the upper and lower components. By its role, it is possible to prevent the occurrence of cracks in the fluxgate device and ensure a uniform magnetization reversal characteristic of the magnetic body 1. In an exemplary embodiment, as shown in FIG. 14, the lower structure may further include a lower insulating layer 6 stacked on the planarized surface of the planarizing thin film 35. The lower insulating layer 6 may provide insulation. In this case, the planarization thin film 35 formed of an SOG material or an equivalent thereof flattens the surface on which the lower insulating film 6 is stacked, and compensates for the difference in thermal expansion between the lower coil 5 and the lower insulating film 6. Can function.

FIG. 12 shows the effect of the planarization thin film 35 employed to fill the buffer groove 32 formed in step S200 on the formation structure of the magnetic body 1.

The technical significance of interposing the planarization thin film 35 between the lower coil 5 and the lower insulating film 6 will be described with reference to FIG. 12. When the lower insulating film 6 is formed immediately after the lower coil 5 is formed as shown in Fig. 12(a) without interposing the flattening thin film 35, the buffer groove 32 formed in the lower coil buried groove 31 ) Directly affects the shape of the lower insulating film 6 and the magnetic body 1 formed thereon. That is, the lower insulating film 6 has a surface profile including a plurality of grooves by the buffer grooves 32, and the surface profile of the magnetic body 1 is the same. Accordingly, the magnetic body 1 is formed in an uneven structure 32' as shown in Fig. 12(a), and the magnetization reversal of the magnetic body 1 is cut off at the uneven portion 32' or its direction is distorted, so that the magnetic body ( 1) It is difficult to achieve an overall uniform magnetization reversal (see α in Fig. 12(a)). As a result, the magnitude of the voltage peak induced in the pickup coil 4 is formed to be small, and the external magnetic field sensing performance of the fluxgate magnetometer is lowered.

On the other hand, in the case of the structure as shown in Fig. 12(b) adopted in the embodiment of the present invention, the buffer groove 32 is filled with SOG material, etc. to form a planarization thin film 35 having a flat surface on the lower coil 5. By forming, the magnetic body 1 stacked thereon can be formed in a flat structure. As a result, since the magnetization reversal of the magnetic body 1 becomes easy (see α'in Fig. 12(b)), the magnitude of the voltage peak induced in the pickup coil 4 is large, and the fluxgate magnetometer's external magnetic field sensing performance is large. It can be improved.

Meanwhile, in step S300 as described above, after the planarization thin film 35 is formed, the lower insulating film 6 may be formed in a structure that is stacked on the planarized surface of the planarization thin film 35.

Specifically, consider a case in which the magnetic body 1 to which high compressive stress can be applied is formed thickly on the planarizing thin film 35 as shown in FIG. 13. In this case, the compressive stress of the magnetic body 1 may be directly transmitted to the planarizing thin film 35 having low stress resistance, so that cracks or breaks 21 may be caused in the planarizing thin film 35. When such breakage occurs, a phenomenon in which the flattening thin film 35 combined with the magnetic body 1 may be detached may occur.

In order to solve this problem, an exemplary embodiment applies, cures, and cures a flattening thin film 35 filling the buffer groove 32 with a SOC material or an equivalent material thereof, as shown in FIG. A structure in which the lower insulating film 6 is formed of a material having high stress resistance is employed. The flattening thin film 35 by the physical properties of the SOC material or its equivalent material flattens the surface on which the lower insulating film 6 is laminated, and at the same time, the lower coil 5 and the lower insulating film ( 6) It can function to prevent thermal shock damage such as cracks that may occur due to the difference in thermal expansion between them.

The lower insulating layer 6 may be formed of any one of SiO ₂ , Ta ₂ O ₃ and Al ₂ O ₃ . Such a material has advantageous properties in preventing destruction of the planarization thin film 35 due to compressive stress of the magnetic body 1 in the process of the fluxgate device. According to the above-described structure, a flux gate made by mixing at least seven or more materials can have high magnetic field sensing performance without damage.

In an exemplary embodiment, after the lower structure portion is formed, step S400 of sequentially stacking the magnetic body 1, the upper insulating layer 7 and the upper coil 9 may be performed to complete the flux gate. In step S400, a conventional fluxgate manufacturing process may be employed, so a detailed description thereof will be omitted.

Fig. 14 shows a structure of a fluxgate manufactured by a method of manufacturing a fluxgate according to an exemplary embodiment.

Referring to FIG. 14, a flux gate into which a flattening thin film 35 is introduced filled with a buffer groove 32 formed by a step difference between the substrate insulating layer 17 and the lower coil 5 embedded therein. The structure is illustrated. The characteristics of the fluxgate of the present embodiment will be described as follows. In an exemplary embodiment, the fluxgate magnetometer may be formed by sequentially stacking the lower coil 5, the

lower structure parts

35 and 6, the magnetic body 1, the upper insulating film 7 and the upper coil 9. The lower coil 5 may be formed in the groove 31 for filling the lower coil provided in the substrate insulating layer 17 formed on the silicon wafer substrate 16. At this time, as previously described with reference to FIGS. 11(e)-(f), the lower coil 5 may be formed to have a step difference between its edge portion and the sidewall portion of the substrate insulating layer 17 in contact therewith. . A buffer groove 32 may be provided in an upper edge region of the lower coil embedding groove 31 corresponding to the stepped structure.

The buffer groove 32 may function to compensate for a difference in thermal expansion between the lower coil 5, the lower structure, and the magnetic body 1 in the process of the flux gate. Specifically, the lower structure portion is stacked on the flattened surface of the planarization thin film 35 and the planarization thin film 35 formed in a flat structure on the substrate insulating film 17 and the lower coil 5 while filling the buffer groove 32 It may include a lower insulating film 6 is formed. The planarization thin film 35 may be formed of an SOG material or a material having properties equivalent thereto (eg, a fluid oxide). The planarization thin film 35 formed of such a material may planarize the surface on which the lower insulating layer 6 is stacked, and compensate for a difference in thermal expansion between the lower coil 5 and the lower insulating layer 6. The lower insulating film 6 is any one of SiO ₂ , Ta ₂ O ₃ and Al ₂ O ₃ to prevent destruction of the planarization thin film 35 due to the compressive stress of the magnetic body 1 during the manufacturing process of the flux gate. It can be formed of a material. The magnetic body 1, the upper insulating film 7 and the upper coil 9 are sequentially stacked on the lower structure.

According to the first embodiment described above, a planarization thin film 35 made of SOG material is formed to fill the buffer groove 32 formed at the edge of the lower coil 5 in contact with the substrate insulating layer 17. do. The flattening thin film 35 can be used as a lower structure to form a magnetic body 1 thereon. Further, a lower insulating film 6 may be further stacked on the planarizing thin film 35 to employ a lower structure of a double-stacked structure. The planarizing thin film 35 made of an SOG-based material may compensate for a difference in thermal expansion between layers constituting the flux gate. Through this, it is possible to prevent breakage due to stress due to the difference in thermal expansion coefficient of each layer. That is, a fluxgate magnetometer with improved stress resistance can be obtained. In addition, it is possible to improve the performance of the flux gate by preventing the magnetic properties of the magnetic body 1 from deteriorating.

15 and 16 are exemplary diagrams for explaining the structure of a fluxgate magnetometer according to a second embodiment of the present invention, and FIGS. 17 and 18 are diagrams showing an SOG thin film in the fluxgate magnetometer according to the second embodiment of the present invention. This is an exemplary diagram showing the wet etching process for Korea.

In the second embodiment of the present invention, a structure of a Z-axis fluxgate capable of improving the pickup voltage detected by the pickup coil 4 under the condition that the minimum height of the fluxgate magnetometer is maintained is proposed. The Z-axis fluxgate of the second exemplary embodiment described below may be manufactured according to the manufacturing method of the first exemplary embodiment, and the contents described in the first exemplary embodiment may be equally applied to the second exemplary embodiment.

First, referring to FIG. 15, a magnetic field shape of a conventional Z-axis fluxgate that is mounted on a conventional electronic compass chip and measures the strength of the magnetic field of the Z-axis component is shown. As shown in Fig. 15A, in general, when a current flows through the solenoid coil 27, circular magnetic lines of force are formed around the solenoid coil 27. When the winding density of the solenoid coil 27 is increased, magnetic lines of force generated from each coil wound overlap each other in a region separated by a predetermined distance from the solenoid coil 27. A linear magnetic force line or a linear magnetic field is formed in the inner region of the solenoid coil 27.

Fig. 15(b) shows the structure of the drive coil 3 of a conventional Z-axis fluxgate. In the Z-axis fluxgate, the regions of the magnetic body 1 in which the drive coil 3 and the pickup coil 4 are wound are defined as the drive region 28 and the pickup region 29, respectively. As shown in Fig.15(b), the inner part of the drive area 28 is tightly wound (ie, the winding density is high), and the outer part of the drive area 28 is loosely wound (ie. , The winding density is low).

Fig. 15(c) shows the shape of the magnetic field generated according to the position of the drive coil 3 when the drive coil 3 with the same line width is wound on a curved magnetic body (ie, drive area 28). have. As shown in Fig. 15(c), since the winding density of the drive coil 3 is high in the inner portion of the drive region 28, the magnetic lines of force generated from each coil can be easily connected. The magnetic field generated by the connection of the magnetic lines of force forms a strong magnetic flux inside the magnetic body 1 by magnetizing the magnetic body 1 located inside the drive coil 3 in the longitudinal direction. The formed magnetic flux flows to the pickup region 29 where the pickup coil 4 is wound. On the other hand, the outer portion of the drive region 28 has a low winding density of the drive coil 3. For this reason, a region in which magnetic lines of force circulate in a circular shape inside the drive coil 3 is widened. In the magnetic body 1 located inside the drive coil 3 at the outer portion, it is not easy to generate magnetic flux in the longitudinal direction. Accordingly, it is difficult to form a magnetic flux to be transmitted to the pickup area 29 in the outer portion of the magnetic body 1.

16 shows a magnetic structure of a Z-

axis fluxgate

50 and 60 according to a second embodiment of the present invention and a coil winding type (see (b) and (c)) in order to solve the above-described problem. It is shown in comparison with the Z-axis fluxgate (see (a)).

First, as a prerequisite for describing the structure of the Z-

axis fluxgates

50 and 60 of the second embodiment, the detailed configuration of the Z-axis fluxgate is as follows. The lower coil 5 and the upper coil 9 are connected to each other to form a solenoid by winding the magnetic body 1 or 1-1 in a coil shape multiple times. The lower coil 5 and the upper coil 9 are respectively wound around the drive area 28 and the pickup area 29 of the magnetic body 1 or 1-1 to form the drive coil 3 and the pickup coil 4, respectively. . A pickup coil 4 in which an induced voltage is formed according to a change in magnetization characteristics of the magnetic body 1 due to a driving current applied to the drive coil 3 may be configured. In addition, the magnetic body 1 may include a pickup area 29 and a drive area 28. Here, the pickup region 29 is defined as a magnetic region of a rod structure in which the pickup coil 4 is wound, and the drive region 28 is branched from the first end in the longitudinal direction of the pickup region 29 to both left and right, respectively. It is defined as a magnetic region formed in a structure that extends into an arc structure having a defined radius of curvature and then joins at the second end in the longitudinal direction of the pickup region 29. The drive area 28 can be viewed as a rugby ball shape or an ellipse shape as a whole.

First, as shown in FIG. 16(b), the drive area 28-1 may have a first structure in the shape of an elliptical shape or a rugby ball having a radius of curvature equal to or greater than a predetermined critical radius of curvature. In the first structure, under the condition that the length of the pickup area 29 is maintained at a predetermined length, the radius of curvature R ₂ of the drive area 28-1 formed in an elliptical shape is a predefined critical radius of curvature R _T It can be defined as a structure of a fluxgate implemented to have the above value. Here, the critical radius of curvature R _T has a larger value than the radius of curvature R ₁ of the magnetic material portion corresponding to the drive area 28 of the conventional Z-axis fluxgate shown in FIG. 16(a) (R ₂ > R _T > R ₁ ), can be defined by the designer. In an exemplary embodiment, it may be R _T = 1.3 R ₁ . Preferably it may be R ₂ = 1.5 R ₁ . The drive area 28-1 of the first structure may further increase the winding density of the drive coil 27-1 compared to the conventional circular drive area 28.

Next, as shown in Fig. 16(c), the drive area 28 is formed in a circular structure as in the prior art, and the line width of the drive coil 27-2 increases from the center of the radius of curvature of the drive area 28 toward the outer side. This may be a second structure implemented in a wider form. Through the second structure, the line width of the drive coil 27-2 formed at the outer portion of the drive area 28 is increased than the line width of the drive coil 27-2 formed inside the drive area 28. It is possible to minimize a portion in which the drive coil 27-2 is not wound on the outer portion of the drive area 28. As the area where the lower coil 5 and the upper coil 9 are joined increases, the amount of current applied to the drive coil 27-2 increases, and thus the magnetic flux generated in the drive region 28 may increase.

The first and second structures are advantageous in that as much magnetic flux as possible is formed in the drive region 28 or 28-1 and transmitted to the pickup region 29. Accordingly, the magnitude of the voltage peak output from the pickup coil 4 increases, so that the magnetic field sensing capability of the

flux gates

50 and 60 may be improved. In these two structures, a third structure in which the drive coil 27-1 of the first structure is transformed into the drive coil 27-2 of the second structure is also possible.

In addition, the

flux gates

50 and 60 of the second embodiment have the winding density of the pickup coil 4 wound in the pickup area 29 (that is, the number of windings of the pickup coil 4 per unit length of the pickup area 29). ) May be implemented as a structure having a predetermined critical density or higher. Here, the critical density may be defined by the designer in consideration of the winding density of the pickup coil 4 wound in the pickup region 29 of the conventional Z-axis fluxgate 40, that is, the second embodiment By increasing the winding density of the pickup coil 4 wound around 29, the voltage peak of the pickup coil 4 can be increased, thereby improving the magnetic field sensing capability of the flux gate.

17 shows the difference in step coverage of the conductive thin film according to the method of removing the planarization thin film to connect the upper coil to the lower coil.

In manufacturing the thin film fluxgate device according to the present invention, the winding structure is formed by removing the SOG thin film formed at the end of the lower coil and then completing the formation of a solenoid-shaped coil using the upper coil. The planarization thin film 35 formed of an SOG material or the like may be formed to a thickness of about 5,000Å. In order to form the upper coil 9 by forming the conductive thin film 38 while overcoming the high step according to the thickness of the planarizing thin film 35, a film is formed on the planarizing thin film 35 as shown in Fig. 17-(d). The conductive thin film 38 to be formed must be formed to have a thickness of 5,000Å or more and at least 6,000Å so that the flattening thin film 35 can cross a high level of the cross-section. In this case, when the planarization thin film 35 is removed through a dry etching process as shown in FIGS. 17(a) to (d), a thick upper coil 9 is formed as shown in FIG. 17(d). Should be done. Accordingly, the winding pitch of the upper coil 9 is increased compared to the structure in which the thin upper coil 9 is formed as shown in FIG. 18(b), and the number of windings of the upper coil 9 per unit length decreases.

Accordingly, in the second embodiment, the conductive thin film 38 for forming the upper coil 9 may be formed according to the process shown in FIGS. 17(e) to (h). As shown in Fig. 17(e), a photoresist 24 is applied on the surface of the planarization thin film 35 except for the area to be etched to form the upper coil 9. In that state, as shown in Fig. 17(f), a wet etching process using a BOE (Buffered Oxide Etcher) solution is performed. Through this, the planarization thin film 35 in the region where the photoresist 24 is not applied may be removed. After going through the etching process using the BOE solution, the planarization thin film 35 is formed in a shape as shown in FIG. 17(g). In this state, a conductive thin film 38 is formed on the planarizing thin film 35 as shown in Fig. 17(h). By using such a process, it is possible to cross the side of the thin film element composed of a thick thin film without breaking the conductive coil by simply forming the thin conductive thin film 38.

18 (a) and (b) show the winding structure when the coil is manufactured through a wet etching process. Compared with the coil structure of 6 pitches shown in FIG. 18(b), FIG. 18(a) shows that a dense winding structure having 4 pitches can be manufactured. When the dry etching process commonly used in the removal process of the planarization thin film 35 used in the present invention is replaced with a wet etching process, the upper part is formed narrower than the lower part in the shape of the planarization thin film 35 and thus has a thin thickness. Even with a conductive thin film, a winding structure in which the upper coil does not break can be formed. As a result, it is possible to improve the magnetic field sensing capability of the fluxgate element by improving the number of turns per unit length and ultimately increasing the output volt peak of the pickup coil.

When the present invention described above is in accordance with the second embodiment, the method of optimizing the radius of curvature of the drive region 28 of the Z-axis fluxgate or the line width of the drive coil 3, and the winding density of the pickup coil 4 By adopting an increasing method, the performance of the Z-axis fluxgate can be improved by improving the pickup voltage detected by the pickup coil 4 under the condition that the minimum height of the Z-axis fluxgate is maintained.

19 to 24 show a magnetic body of a Z-axis fluxgate and a winding structure of a coil according to various other embodiments of the present invention. First, FIG. 19 shows a structure 100 in which a drive coil and a pickup coil are wound around an eight-shaped magnetic body 110 of a land track type.

Referring to Fig. 19, the magnetic body 100 according to an exemplary embodiment includes a land track type drive area and a straight pick-up area 120 that connects a middle portion between two parallel straight line sections of the drive area. Specifically, the drive region is at the first and second straight sections 130-1a and 130-1b linearly branching from the first end of the pickup region 120 to both left and right, and at the second end of the pickup region 120. A first curved section connected to both ends of the third and fourth straight sections 130-1c and 130-1d, which are linearly branched to the left and right, and the first and third straight sections 130-1a and 130-1c. It may be in the shape of a running track including (130-2a) and a second curved section (130-2b) connected to both ends of the second and fourth straight sections (130-1b, 130-1d). The pickup coil 125 is wound around the pickup area 120 and both ends thereof are connected to the pickup coil pad 122. The drive coils 135a and 135b are wound around the drive area, and both ends thereof are connected to the drive coil pads 132.

The magnetic body and coil winding structure 100 according to this embodiment is compared with the elliptical structure shown in Fig. 16(b), first to fourth straight sections 130-1a, 130-1b, 130-1c, and 130- The drive area of 1d) is further included. These straight sections can be used to wind more drive coils, thus generating more magnetic flux. In addition, as in the structure 100 of this embodiment, if the two drive regions on the left and right are engaged with the pickup region 120 in the center, the pickup region 120 in the center will receive as much magnetic flux from the drive coils on the left and right sides as possible. I can. It is an efficient structure with a large amount of magnetic flux that can be received compared to the occupied area.

20 shows a structure 150 in which a drive coil and a pickup coil are wound around an S-shaped magnetic body 160.

Referring to Fig. 20, the structure 150 according to the exemplary embodiment includes a pickup area 120 extending a predetermined length in a straight line at the center, and two facing each other in a form connected to the pickup area 120 forming an S shape. It includes four U-shaped drive areas. The first U-shaped drive area disposed on the left side of the pickup area 120 includes two parallel straight sections 180-1a and 180-1c and a curved section 180-2a connecting them, and one straight line Only the section 180-1c is connected to the lower end of the pickup area 120, and the other straight section 180-1a extends only to the vicinity of the upper end of the pickup area 120, but is not connected. The second U-shaped drive area disposed on the right side of the pickup area 120 includes two parallel straight sections 180-1b and 180-1d and a curved section 180-2b connecting them, and has one straight line. Only the section 180-1b is connected to the upper end of the pickup area 120, and the other straight section 180-1d extends only to the vicinity of the lower end of the pickup area 120, but is not connected. The pickup coil 175 is wound only in the pickup area 120, and the drive coil 185 is wound only in the two U-shaped drive areas.

The structure 150 according to this embodiment is different from the structure 150 shown in FIG. 19 (a structure in which a drive coil and a pickup coil are connected to rotate a caterpillar), a first drive area --> a pickup area 120 --> The 2nd drive area forms a single line connected in sequence. By greatly increasing the first and second drive regions to the left and right of the pickup region 120, a magnetic flux having a sufficient size can be drawn from there to pass through the pickup region 120 in the center. Even if the magnetic flux generated in the two drive regions is not entered from both left and right sides of the pickup region 120, the intensity of the magnetization reversal of the pickup region can be increased. The connecting portion 184 of the lower end of the pickup area 120 and the third straight section 180-1c of the first drive area may be connected in a smooth curve, and the upper end of the pickup area 120 and the second drive The same applies to the connection portion 184 of the second straight section 180-1 of the region. Such a connection structure can maximize the length of the section in which the direction of the magnetic flux is vertically present in the pickup area 120. That is, this connection structure can increase the length of an effective pickup section that contributes to detection of the pickup voltage.

21 and 22

show structures

200 and 250 in which a drive coil and a pickup coil are wound around an eight-shaped magnetic body 110 of a land track type as shown in FIG. 19.

First, the magnetic body and coil winding structure 200 shown in FIG. 21 employs a magnetic body 110 having the same structure as the magnetic body 110 shown in FIG. 19, and a pickup coil 225 is attached to the pickup area 120. Winding is the same. However, in the magnetic material and coil winding structure 200 according to the present embodiment, the first drive areas 130-1a and 130-2a and the second drive areas 130-1b and 130-2b on the left and right sides of the pickup area 120 In addition, the drive coils 235a, 235b, and 235c are also wound in the pickup area 120, which is different from the magnetic material and coil winding structure 100 of FIG. 19. In the pickup area 120, the pickup coil 225 and the drive coil 235c may be wound alternately by one turn or by k turns (where k is a natural number of 2 or more) as shown.

In the magnetic material and coil winding structure 200 according to this embodiment, as in the structure 100 of FIG. 19, the curved drive area is extended to the left and right away from the pickup area 120, so that the drive coil can be wound a lot. According to this structure 200, since the drive coil can be wound a lot, the amount of drive magnetic flux is increased, and the dynamic range, which is an area in which the output characteristic of the pickup voltage can be measured, can be expanded. In addition, linearity of the amount of change in the magnetic field and the amount of movement of the pickup voltage peak can be ensured.

In addition, a drive coil and a pickup coil are alternately wound around the pickup area 120. The reason that the drive coil 235c is wound around the pickup area 120 is to increase the sensitivity of the fluxgate magnetometer by increasing the peak of the pickup voltage detected by the pickup coil 225. Even if a large magnetic field is applied from the outside, the drive coil 235c wound around the pickup area 120 may continue to generate magnetic flux and drive it in the pickup direction. Accordingly, the atoms in the magnetic body of the pickup region 120 can maintain the spin direction in the length direction of the pickup region 120. Accordingly, a voltage peak output from the pickup coil 225 may be output in the longitudinal direction of the pickup region 120.

The pickup coil 225 only has a function of detecting a simple magnetization inversion without a current flow of itself. If only the pickup coil 225 is wound around the pickup region 120, when a large external magnetic field (for example, 3 Gauss or more) is applied, the spin direction of the atoms inside the magnetic body of the pickup region 120 is changed by the external magnetic field. The direction of the magnetic field is aligned. In this case, the hysteresis loop becomes a shape lying down in the length direction of the pickup area, and the peak of the pickup voltage induced to the pickup coil 225 gradually decreases. In that case, it becomes difficult to detect the position of the bolt peak, which lets you know the direction of the externally applied magnetic field. The drive coil 235c wound around the pickup area 120 can advantageously contribute to preventing this phenomenon.

The magnetic body and coil winding structure 250 shown in FIG. 22 differs only in the winding shape of the pickup coil 275 wound around the pickup region 120 as compared with the magnetic body and coil winding structure 200 of FIG. 21. In an exemplary embodiment, the pickup coil 275 is wound around the pickup area 120 together with the drive coil 235c, and the pickup coils 275a and 275b and the drive coil 235c are at a ratio of 2 turns to 1 turn. Take turns winding.

In an exemplary embodiment, the winding of the first pickup coil 275a may be wound adjacent to the drive coil 235, and the winding of the second pickup coil 275b may be wound next to the first pickup coil 275a. In this form, the drive coil 235, the first pickup coil 275a, and the second pickup coil 275b are repeatedly wound in this order, and then the end of the first pickup coil 275a is pulled down and lowered to By connecting to the beginning of the pickup coil 275b, the first pickup coil 275a and the second pickup coil 275b may function as one pickup coil 275 as a whole.

This winding method of the pickup coil is advantageous in increasing the number of turns of the pickup coil per unit length of the pickup region 120 to increase the peak value of the pickup voltage output from the pickup coil 275. When the peak of the pickup voltage increases, the driving circuit 15 is less affected by noise when reading the point where the peak of the pickup voltage occurs, so that it can be accurately read.

Next, Figs. 23 and 24

show structures

300 and 350 in which a drive coil and a pickup coil are wound around a magnetic body 310 in a square 8 shape.

The magnetic body and coil winding structure 300 shown in FIG. 23 is different from the structure 200 of FIG. 21 in that the drive area of the magnetic body 310 has a rectangular shape. That is, the drive area of the magnetic body 110 of the structure 200 shown in FIG. 21 has a shape of a running track including curved sections 130-2a and 130-2b, whereas the structure 300 of FIG. 23 is curved It consists of straight sections 330-1c and 330-2c instead of sections. These two straight sections 330-1c and 330-2c are respectively connected to the left and right sides of the upper portion of the pickup area 120 and the straight sections 330-1a and 330-2a connected to the left and right sides of the lower portion of the pickup area 120, respectively. They are connected to the ends of the straight sections 330-1b and 330-2b, respectively, to form an overall rectangular drive area.

The drive coils 335a and 335b may be tightly wound over the entire section of the rectangular drive area. You can maximize the number of turns of the drive coil. Further, the drive coil 335c may be cross-wound in the pickup area 120 together with the pickup coil 225 for the same reason and shape as the structure 200 of FIG. 21. By cross-winding the pickup coil 225 and the drive coil 335c in this way, as mentioned above, the dynamic range is increased to prevent the voltage pickup function of the pickup coil 225 from deteriorating in the pickup region 120 by an externally applied magnetic field. Is advantageous.

The magnetic material and coil winding structure 300 shown in FIG. 24 differs only in the winding shape of the pickup coil 275 wound around the pickup area 120 as compared with the magnetic material and coil winding structure 300 of FIG. 23. That is, the pickup coil 275 is wound around the pickup area 120 together with the drive coil 235c, and the pickup coil 275a of 2 turns per turn of the drive coil 235c wound around the

pickup area

120, 275b) is wound. The shape and purpose of windings of the drive coil 235c and the pickup coils 275a and 275b in the pickup area 120 are the same as those in the pickup area 120 of the structure 250 shown in FIG.

In FIG. 25, the pickup coil 225 and the drive coil 235c are actually wound around the pickup area 120 of the structure 200 shown in FIG.

Referring to FIG. 25, the

magnetic material

1 or 110 of the pickup area 120 is surrounded by a lower insulating film 6 and an upper insulating film 7, and a drive coil 235c and a pickup coil 225 are 1 It is wound alternately at the ratio of turn to 1 turn. In FIG. 25, the conductor section marked with hatched corresponds to the drive coil 235c, and the conductor section marked with hatched corresponds to the pickup coil 225. In addition, the conductor section indicated by the dotted line corresponds to the drive coil 235c and the lower coil 5 of the pickup coil 225, and the conductor section indicated by the solid line is the drive coil 235c and the upper coil of the pickup coil 225 ( It corresponds to 9). This description can be applied equally to the structure 300 shown in FIG. 23.

In FIG. 26, the pickup coil 275 and the drive coil 235c are actually wound in the pickup area 120 of the structure 250 shown in FIG.

Referring to FIG. 26, the

magnetic body

1 or 110 of the pickup region 120 is surrounded by a lower insulating film 6 and an upper insulating film 7, and the drive coil 235c and the pickup coil 275 are 1 It is wound alternately at the ratio of turns to 2 turns. In FIG. 26, the conductor section marked with white blanks without marking anything such as hatched corresponds to the drive coil 235c, the conductor section marked with hatched corresponds to the first pickup coil 275a, and the conductor section marked with a net corresponds to the first pickup coil 275a. 2 Corresponds to the pickup coil 275b. In addition, the conductor section indicated by the dotted line corresponds to the drive coil 235c and the lower coil 5 of the pickup coil 275, and the conductor section indicated by the solid line is the drive coil 235c and the upper coil of the pickup coil 275 ( It corresponds to 9). This description can equally be applied to the structure 350 shown in FIG. 24.

Next, Fig. 27 illustrates a magnetic material including a drive region formed of a magnetic thin film having a two-stage structure according to an exemplary embodiment.

Referring to FIG. 27, for example, in forming the magnetic body 210 of the eight-shaped structure of the land track, the lower drive regions 130-1a, 130-1b, 130-2a in the shape of a land track as shown in FIG. 130-1c, 130-1d, 130-2b) and the pickup area 120 connecting the middle of the straight section 130-1a, 130-1b, 130-1c, 130-1d of the lower drive area The lower

magnetic bodies

130L and 130R are firstly formed. Then, with the pickup area 120 as the center, U on the lower drive areas 130-1a, 130-1b, 130-2a on the left and the lower drive areas 130-1c, 130-1d, 130-2b on the right. The first upper magnetic body 210L and the second upper magnetic body 210R of the shape are additionally formed. The upper

magnetic bodies

210L and 210R may be formed of the same laminated structure and the same thickness using the same material as the lower

magnetic bodies

130L and 130R. However, the upper

magnetic bodies

210L and 210R may have a smaller cross-sectional area than the lower

magnetic bodies

130L and 130R.

When the magnetic material is stacked in a two-stage structure, the volume of the magnetic material inside the drive coil wound in the drive area is increased, so that the amount of magnetic flux flowing inside the magnetic material can be much greater than that of a single-layered magnetic material. By increasing the volume of the magnetic material, more magnetic flux can flow from the drive area to the pickup area. In such a magnetic structure, when magnetization reversal occurs due to an alternating current flowing through the drive coil, a much larger amount of induced current flows through the pickup coil wound around the pickup area, thereby increasing the peak height of the independent pickup voltage sensed by the pickup coil. When the peak of the independent pickup voltage increases, the signal-to-noise ratio (SNR) increases, so that the driving circuit 15 can more easily detect the position of the voltage peak. In addition, it is possible to obtain an effect of reducing the overall size of the fluxgate magnetometer.

The magnetic body 210 having a two-stage structure shown in FIG. 27(b) may be made of a laminated thin film structure. Of course, the

magnetic material

1, 110, 160, or 310 according to the various embodiments described above may also be made of the same magnetic thin film structure.

Referring to Fig. 27(b), the structure of the magnetic body used in the present invention will be described by taking the magnetic body 210 having a two-tier structure as an example. The magnetic thin film 210 may be made in a structure in which a plurality of sets of magnetic films 220 are continuously stacked. The set of magnetic layers 220 may include a magnetic thin layer 220-1 formed of a magnetic material such as NiFe, and an insulating thin layer 220-2 stacked thereon. Such a laminated magnetic thin film 210 can be manufactured to have soft magnetic properties of soft magnetic thin films, that is, small coercivity, fast saturated magnetization, and high permeability. have. Since the manufacturing method thereof is already widely known, a detailed description thereof is omitted. In order to increase the magnitude of the output magnetic field or the peak of the pickup voltage in manufacturing the soft magnetic thin film, the number of sets of the stacked magnetic layers 220 may be increased. In an exemplary embodiment, the magnetic thin film 210 is formed of, for example, a magnetic thin film 220-1 made of NiFe to a thickness of about 500Å, and an insulating thin film such as SiO ₂ , AL ₂ O ₃ , Ta ₂ O ₅ ( 220-2) was formed to a thickness of approximately 100 Å. The magnetic thin film 210 may be formed by stacking approximately several to tens of sets of the'magnetic thin film 220-1 + the insulating thin film 220-2'. In the magnetic body 210 having a two-stage structure, both the lower

magnetic bodies

130L and 130R and the upper

magnetic bodies

210L and 210R may be formed in the same structure as the magnetic thin film 210 mentioned above. In the area (drive area) in which the magnetic thin film 210 is to be formed thick, the magnetic thin film 210 having a two-stage structure can be formed by forming a primary magnetic thin film and then forming an additional secondary magnetic thin film thereon. have. In this case, the secondary magnetic material thin film may be formed to have the same vertical structure as the primary magnetic material thin film. The thickness of the magnetic thin film formed in a two-stage structure may be determined according to the output size of the fluxgate magnetometer and the magnetic field sensing performance.

Magnetic bodies according to all other embodiments of the present invention may be adopted by appropriately modifying the drive area of the two-stage structure illustrated in FIG. 27 to suit the shape of the corresponding magnetic body. For example, the drive area of the circular or elliptical shape magnetic body of Fig. 16, the first and second drive areas of the S-shaped magnetic body 160 of Fig. 20, the drive area of the square 8-shaped magnetic body 310 of Figs. 23 and 24, etc. It can be composed of a magnetic thin film with a two-stage structure. Since a person of ordinary skill in the art may implement the two-stage drive area of the magnetic bodies based on the description of FIG. 27, a description thereof will be omitted here.

The various magnetic material and winding

structures

100, 150, 200, 250, 300, and 350 shown in FIGS. 19 to 24 can greatly increase the number of turns of the drive coil, so that the magnetic flux provided to the pickup area 120 The amount increases. In addition, since the

structure

200, 250, 300, and 350 further winding up to the drive coil in addition to the pickup coil in the pickup region 120 can transmit a stronger magnetic flux to the pickup region 120, an external magnetic field in the pickup region 120 Even if applied, the spin direction of the atoms of the magnetic material 1 in the pickup region 120 can be maintained in the longitudinal direction (Z direction) of the pickup region 120. Further, if the drive region of the magnetic material is formed in a two-stage structure to make the cross-sectional area larger than that of the pickup region, the amount of magnetic flux generated in the drive region and applied to the pickup region can be further increased. The structures of various embodiments presented in the present invention may be applied to a fluxgate magnetometer alone or in combination of two or more. A fluxgate magnetometer employing such structures can have an enlarged dynamic range and an improved linearity between the amount of change in the magnetic field and the amount of movement of the voltage peak.

The present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the art to which the present technology pertains, various modifications and other equivalent embodiments are possible. I will understand. Therefore, the true technical protection scope of the present invention should be determined by the following claims.

The present invention can be used to design and manufacture magnetic sensors such as fluxgate magnetometers.

1: magnetic film or magnetic laminated films

2: insulation film

3: drive coil

4: pick-up coil

5: bottom coil

6: bottom oxide film

7: top oxide film

8: side oxide film

9: top coil

10: PCB for packaging

11: epoxy molding

12: Z-axis fluxgate

13: Y-axis fluxgate

14: X-axis fluxgate

15: Fluxgate drive circuit (ASIC for fluxgate)

16: silicon wafer substrate

17: substrate insulating film (silicon oxide, SiO ₂ )

18: load for CMP

19: plate for CMP

20: CMP abrasive (abrasive for CMP)

21: crack, crack

22: magnetic film on the Aluminum bottom coil

23: magnetic film on the silicon oxide formed on the substrate insulating film

24: photo resist

25: protrusion of the bottom coil

26, 26': wavy structure

27: solenoid coil

28: drive area

29: pick-up area

30: first area

31: area for bottom coil

32: buffer groove

32': groove structure

33: magnetic film

34: inter layer

35: planarization thin film (SOG (Spin-On-Glass) film)

36: radius of curvature R ₁

37: radius of curvature R ₂

38: conductive thin film (thin film for current flow)

50, 60: fluxgate

110: land track type 8-shaped magnetic body

120: pickup area

160: S-shaped magnetic body

100, 150, 200, 250, 300, 350: magnetic body and coil winding structure

Claims

A lower coil, a lower structure, a magnetic material, an upper insulating film, and an upper coil sequentially stacked on the substrate insulating film on the substrate,

The lower coil is formed in a form buried in a plurality of rows of grooves for burying the lower coil provided in the substrate insulating film, and each lower coil has its own edge portion lower than the upper end of the lower coil burying groove to bury the lower coil. A buffer groove in the form of an empty space is formed at an upper portion of the edge portion near the upper end of the side wall portion of the dragon groove,

The lower structure is formed by using a spin-on-glass composition or material or a flowable oxide material to provide a flat surface while filling the buffer groove and covering the substrate insulating film and the lower coils. A fluxgate magnetometer comprising a flattening thin film configured to buffer a stress according to a difference in a coefficient of thermal expansion between neighboring components.
The method of claim 1, wherein each of the plurality of conductive lower coils has a height of a central portion of an upper surface substantially equal to a height of an upper end of the groove for filling the lower coil, and a height of the edge portion is lower than that of the center of the upper surface, Flux skate magnetometer, characterized in that the buffer groove is provided.
The fluxgate magnetometer of claim 1, wherein the lower structure portion further comprises a lower insulating layer formed to provide insulation by being stacked on the planarized surface of the planarizing thin film.
The method of claim 3, wherein the lower insulating layer is formed of any one of SiO 2 , Ta 2 O 3 and Al 2 O 3 to prevent destruction of the planarization thin film due to compressive stress of the magnetic material during the process of the flux gate. Fluxgate magnetometer, characterized in that formed of a single material.
The method of claim 1, wherein the lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape, and are induced by a drive coil for passing a drive current and a magnetic flux passing through it. It is configured to separately form a pickup coil for detecting the pickup voltage,

The magnetic body extends a predetermined length in a straight line, and at least the pickup area magnetic body around which the pickup coil is wound; A track-shaped structure, a quadrangular structure, and a drive area magnetic material connected to the pickup area magnetic material is formed in any one of two facing U-shaped structures forming an S-shape, and at least the drive coil is wound. Fluxgate magnetometer.
[6] The fluxgate magnetometer of claim 5, wherein the drive coil is further wound around the pickup area magnetic material to prevent a peak value of the pickup voltage from being reduced by an externally applied magnetic field.
The fluxgate magnetometer of claim 6, wherein a ratio of the number of turns between the drive coil and the pickup coin wound around the pickup area is 1:1 or 1:2.
The method of claim 5, wherein the drive area magnetic material is stacked on a first stage drive area magnetic material having substantially the same thickness as the pickup area magnetic material, and the first stage drive area magnetic material, and has a cross-sectional area smaller than that of the first stage drive area magnetic material. A fluxgate magnetometer, characterized in that it is formed of a two-stage magnetic material including a magnetic material in the second-stage drive area and the sum of the cross-sectional areas of the magnetic material in the first and second-stage drive areas is greater than that of the magnetic material in the pickup area. .
The fluxgate magnetometer of claim 1, wherein the magnetic material has a structure in which a plurality of sets of magnetic material layers are continuously stacked, and the set of magnetic material layers includes a magnetic thin film formed of a magnetic material and an insulating thin film stacked thereon.
A lower coil, a lower structure, a magnetic material, an upper insulating film, and an upper coil sequentially stacked on the substrate insulating film on the substrate,

The lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape to detect a pickup voltage induced by a magnetic flux passing through a drive coil for passing a drive current. The pickup coil is formed separately,

The magnetic material is a pick-up area magnetic material that extends for a predetermined length in a straight line and at least the pick-up coil is wound; And a land track-type structure composed of a combination of a straight section and a curved section by branching from the upper and lower ends of the magnetic material in the pickup area, a rectangular structure, and two facing each other in a form connected to the magnetic material in the pickup area forming an S shape. Fluxgate magnetometer, characterized in that it is formed in any one of the U-shaped structure, at least comprising a drive region magnetic material wound around the drive coil.
11. The fluxgate magnetometer of claim 10, wherein the drive coil is further wound around the pickup area magnetic material to prevent a peak value of the pickup voltage from being reduced by an externally applied magnetic field.
The fluxgate magnetometer of claim 11, wherein a ratio of the number of turns between the drive coil and the pickup coin wound around the pickup area is 1:1 or 1:2.
The method of claim 10, wherein the drive area magnetic material is stacked on a first stage drive area magnetic material having substantially the same thickness as the pickup area magnetic material, and the first stage drive area magnetic material, and has a cross-sectional area smaller than that of the first stage drive area magnetic material. A fluxgate magnetometer, characterized in that it is formed of a two-stage magnetic material including a magnetic material in the second-stage drive area and the sum of the cross-sectional areas of the magnetic material in the first and second-stage drive areas is greater than that of the magnetic material in the pickup area. .
The method of claim 10, wherein the lower coil is formed in a form buried in a plurality of rows of grooves for burying a lower coil provided in the substrate insulating film, and each lower coil has its own edge portion lower than the upper end of the lower coil burying groove. Is formed such that a buffer groove is provided at an upper portion of the edge portion near an upper end of the sidewall portion of the lower coil buried groove;

The lower structure is formed by using a spin-on-glass composition or material or a flowable oxide material to provide a flat surface while filling the buffer groove and covering the substrate insulating film and the lower coils. A fluxgate magnetometer comprising a flattening thin film configured to buffer a stress according to a difference in a coefficient of thermal expansion between neighboring components.
15. The fluxgate magnetometer of claim 14, wherein the lower structure part further comprises a lower insulating layer formed to provide insulation by being stacked on the planarized surface of the planarizing thin film.
Board;

A substrate insulating film stacked on an upper surface of the substrate to provide insulation and having a plurality of rows of grooves for filling the lower coils formed on the upper surface;

Each of the plurality of rows of lower coil embedding grooves is buried, and each edge portion is an empty space between the edge portion and the sidewall portion of the lower coil embedding groove by a step formed lower than the upper end surface of the lower coil embedding groove. A plurality of rows of lower coils formed to have buffer grooves;

A planarization thin film filling the buffer groove and covering the substrate insulating layer and the plurality of rows of lower coils to provide a flat surface; And a lower insulating film formed to provide insulation by being stacked on the planarized surface of the planarizing thin film.

A magnetic material stacked on the upper surface of the lower structure;

An upper insulating layer covering the side and upper surfaces of the magnetic material to cooperate with the lower structure to insulate the magnetic material from the outside; And

It has a plurality of rows of upper coils formed to surround an upper surface and a side surface of the upper insulating film,

The lower coil and the upper coil are connected to each other so as to wind the lower structure part and the magnetic body wrapped with the upper insulating film in a solenoid shape to detect a pickup voltage induced by a magnetic flux passing through a drive coil for passing a drive current. The pickup coil is formed separately,

The magnetic body extends a predetermined length in a straight line, and at least the pickup area magnetic body around which the pickup coil is wound; A track-shaped structure, a quadrangular structure, and a drive area magnetic material connected to the pickup area magnetic material is formed in any one of two U-shaped structures facing each other forming an S-shape, and at least the drive coil is wound. Fluxgate magnetometer.
The method of claim 16, wherein the planarization thin film is coated on the plurality of lower coils and the substrate insulating film while filling the buffer groove in a spin coating method in a sol state to form a flat surface, and after curing, hard gel A fluxgate magnetometer, characterized in that it is made of a material that is transformed into a gel) state and has physical properties capable of buffering stress due to a difference in thermal expansion coefficient between neighboring components.
The flux gate magnetometer of claim 16, wherein the planarization thin film is formed of an SOG composition or a flowable oxide material.
17. The fluxgate magnetometer of claim 16, wherein the drive coil is further wound around the pickup area magnetic material to prevent a peak value of the pickup voltage from being reduced by an externally applied magnetic field.
The fluxgate magnetometer of claim 19, wherein a ratio of the number of turns between the drive coil and the pickup coin wound around the pickup area is 1:1 or 1:2.
The method of claim 16, wherein the drive area magnetic material is stacked on a first stage drive area magnetic material having substantially the same thickness as the pickup area magnetic material, and the first stage drive area magnetic material, and has a cross-sectional area smaller than that of the first stage drive area magnetic material. A fluxgate magnetometer, characterized in that it is formed of a two-stage magnetic material including a magnetic material in the second-stage drive area and the sum of the cross-sectional areas of the magnetic material in the first and second-stage drive areas is greater than that of the magnetic material in the pickup area. .
The drive coil of claim 16, wherein the drive coil wound around the curved section of the magnetic body of the drive area magnetic body of the elliptical structure or the curved section of the drive area magnetic body of the land track structure and the two U-shaped structures is in an outer direction from a center of a radius of curvature. Fluxgate magnetometer, characterized in that formed to increase the line width gradually.
As a method of manufacturing a fluxgate magnetometer formed by sequentially stacking a lower coil, a lower structure part, a magnetic material, an upper insulating film, and an upper coil,

Forming a plurality of rows of grooves for filling the lower coils in which the lower coils are to be formed in a substrate insulating film formed on a silicon wafer substrate;

A plurality of rows of lower coils are formed in the form of being buried in the plurality of rows of lower coil embedding grooves, but the edge of each lower coil is formed lower than the upper end of the lower coil embedding groove, so that the sidewall of the lower coil embedding groove Forming a lower coil such that a plurality of buffer grooves in the form of empty spaces are provided above the edge portion near an upper end; And

SOG composition or flowable oxide material is coated on the substrate insulating film and the lower coils while filling the buffer groove, performing spin coating to form a flat surface, and curing to form a hard gel state. Including the step of forming an underlying structure including a planarization thin film,

The method of manufacturing a fluxgate magnetometer, wherein the planarizing thin film has physical properties capable of buffering a stress according to a difference in coefficient of thermal expansion between neighboring components.
24. The method of claim 23, wherein the forming of the lower coil comprises sputtering a conductive metal with respect to the plurality of rows of lower coil embedding grooves while the photoresist is coated, so that the height of the central part is increased to the lower coil embedding groove. A method of manufacturing a fluxgate magnetometer, characterized in that a lower coil having a surface profile that is substantially the same as an upper end of and the edge portion is lower than that of the central portion and in which the buffer groove is provided is formed.
The method of claim 23, wherein the forming of the groove for filling the lower coil comprises performing a primary etching on an etched region on the substrate insulating layer to which the photoresist is not coated to form a primary region in which the lower coil is to be formed. step; And forming the lower coil embedding groove in a structure in which the inlet edge of the lower coil embedding groove is covered with the photoresist by additionally performing secondary etching on the first region to expand the first region. A method of manufacturing a fluxgate magnetometer comprising a.
The method of claim 25, wherein the first etching is performed through a dry etching process, and the second etching is performed through wet etching.
The method of claim 25, wherein the forming of the groove for burying the lower coil comprises removing a part of the lateral tip of the photoresist covering the inlet of the groove for burying the lower coil through additional dry etching, and then in the groove for burying the lower coil. A method of manufacturing a fluxgate magnetometer, comprising the step of forming the lower coil.
The method of claim 23, further comprising forming a lower insulating layer to be stacked on the planarization thin film as a part of the lower structure with any one of SiO 2 , Ta 2 O 3 and Al 2 O 3 , and the lower portion The method of manufacturing a fluxgate magnetometer, wherein the insulating film prevents destruction of the planarization thin film due to compressive stress of the magnetic material and provides insulation during the manufacture of the fluxgate magnetometer.
The magnetic material of claim 28, wherein the magnetic material is formed on the lower structure in a structure in which a plurality of sets of magnetic layers are successively stacked, wherein the magnetic material layer includes a magnetic thin film formed of a magnetic material and an insulating thin film stacked thereon. Forming a; And forming the upper insulating film formed to surround the upper and side surfaces of the magnetic body and cooperate with the lower structure to completely surround and insulate the magnetic body.
The method of claim 29, wherein an upper coil connected to the lower coils is formed so as to wind the lower structure part and the magnetic material wrapped with the upper insulating film in a solenoid shape, and the drive coil for passing a drive current and a magnetic flux passing through it are formed. A method of manufacturing a fluxgate magnetometer, further comprising the step of separately forming a pickup coil for detecting the induced pickup voltage.
The method of claim 29, wherein the forming of the magnetic body comprises: a pickup area magnetic body in which the magnetic body extends in a straight line for a predetermined length and at least the pickup coil is wound, and the pickup area magnetic body is branched from both upper and lower ends to an elliptical shape. A structure, or a track-type structure consisting of a combination of a straight section and a curved section, a square structure, and one of two U-shaped structures facing each other in which the shape connected to the pickup area magnetic body forms an S-shape, and at least A method of manufacturing a fluxgate magnetometer, characterized in that the drive coil is formed to include a magnetic drive area magnetic material wound thereon.
The method of claim 31, wherein the forming of the magnetic material comprises: the drive area magnetic material is stacked on a first-stage drive area magnetic material having a thickness substantially the same as that of the pickup area magnetic material, and the first-stage drive area magnetic material Forming a two-stage magnetic material to include a second-stage drive area magnetic material formed smaller than the first-stage drive area magnetic material, wherein the sum of the cross-sectional areas of the first-stage drive area magnetic material is the pickup area magnetic material Method of manufacturing a fluxgate magnetometer, characterized in that greater than the cross-sectional area of.