JP2008249406A - Magnetic impedance effect element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in a bias magnetic field due to a leakage magnetic field in a magnetic impedance effect element. <P>SOLUTION: This magnetic impedance effect element 10 is provided with a thin-film magnet 12 composed of a hard magnetic substance film formed on a nonmagnetic substrate 11, an insulating layer 13 covering the upside of the thin-film magnet 12, a magnetosensitive part 14 composed of one or a plurality of rectangular soft magnetic substance films formed on the insulating layer 13 and imparted with uniaxial anisotropy, and a conductor film 16 for connecting the plurality of soft magnetic substance films of the magnetosensitive part 14 electrically. In a longitudinal direction of the magnetosensitive part 14, both ends of the thin-film magnet 12 are located outside both ends of the magnetorsensitive part 14. The insulating layer 13 has openings 13a above the respective ends of the thin-film magnet 12. On the insulating layer 13, a yoke section 15 composed of a soft magnetic substance film is formed ranging from the ends of the thin-film magnet 12 over to the vicinities of the ends of the magnetosensitive part 14 via the openings 13a of the insulating layer 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thin film type magneto-impedance effect element known as a high-sensitivity magnetic sensor. Conventionally, this type of element is, for example, an electronic compass that detects geomagnetism and indicates a direction, a rotary encoder, a biomagnetic measurement, etc. It is used for.

  Conventionally, a magneto-impedance effect element has a characteristic that impedance changes symmetrically with respect to positive and negative magnetic fields. Therefore, in order to detect a positive / negative magnetic field near the magnetic field 0, it is necessary to apply a bias magnetic field to the magneto-impedance effect element so that the impedance change becomes linear. As a bias magnetic field application method, a method using a wound coil, a thin film coil, a sheet magnet, a bulk magnet, or a thin film magnet is known (see Patent Documents 1 to 11).

The problems in each method are as follows.
1. When a bias magnetic field is applied by a winding coil, it is difficult to reduce the size of the element, and there is a problem that the structure becomes complicated and the power consumption increases.
2. When a bias magnetic field is applied by a thin film coil, there are problems that the structure becomes complicated and the power consumption increases.
3. When a bias magnetic field is applied by a sheet magnet or a bulk magnet, it is difficult to control the magnetic field strength, the assembly process is complicated, the mechanical strength is difficult to obtain, and the leakage magnetic field is large.
4). When a bias magnetic field is applied by a thin film magnet, there is a problem that it is difficult to control the magnetic field strength. Moreover, there is a leakage magnetic field though it is small.
Japanese Patent No. 3210933 Japanese Patent No. 3650575 Japanese Patent No. 3656018 Japanese Patent No. 3606028 JP 2004-333217 A JP 2002-55148 A JP 2002-43649 A JP 2002-43648 A JP 2002-43647 A JP 2002-33210 A International Publication No. 2004/086073

  When the coil is used, it is necessary to supply a current necessary for generating the bias magnetic field to the coil, which causes a problem that power consumption increases. Further, since the process of forming the coil wiring becomes complicated, the cost is high, and there are problems in terms of yield and reliability.

  When a magnet is used, the magnitude of the bias magnetic field is determined by the size, shape, and characteristics of the magnet, which makes it difficult to apply an accurate bias magnetic field, and it is particularly difficult to finely adjust the bias magnetic field after sensor fabrication. . Further, when it is necessary to arrange a plurality of sensor chips in one package such as an electronic compass due to a leakage magnetic field from a magnet, a bias magnetic field fluctuates after mounting due to a leakage magnetic field from an adjacent sensor chip. However, the arrangement of the sensor chip at the time of mounting is limited, the degree of freedom in designing the package is low, and miniaturization and integration are difficult.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the magneto-impedance effect element which can suppress the fluctuation | variation of the bias magnetic field by a leakage magnetic field, and its manufacturing method.

  In order to solve the above-described problems, the present invention provides a thin film magnet made of a hard magnetic film formed on a nonmagnetic substrate, an insulating layer covering the thin film magnet, and a uniaxially different film formed on the insulating layer. A magnetic sensing portion made of one or a plurality of rectangular soft magnetic films provided with anisotropy, and a conductor film that electrically connects the plurality of soft magnetic films of the magnetic sensing portion, In the longitudinal direction of the magnetic part, both ends of the thin film magnet are located outside both ends of the magnetic sensitive part, and the insulating layer has an opening on each end of the thin film magnet. On the insulating layer, a yoke portion made of a soft magnetic film that forms a magnetic path between the thin film magnet and the magnetic sensing portion is provided through the opening of the insulating layer. The magneto-impedance effect is characterized in that the magneto-impedance effect is formed over the vicinity of the end of the magnetosensitive portion To provide a child.

It is preferable that the yoke portion is in direct contact with the end portion of the thin film magnet and is not electrically connected to the magnetic sensitive portion.
It is preferable that the yoke part has an interval of 1 to 100 μm between the longitudinal part of the magnetic sensing part.

  In the magneto-impedance effect element of the present invention, the magnetic sensitive part has a plurality of the soft magnetic films, and the thin film magnet corresponds to each soft magnetic film of the magnetic sensitive part in one-to-one correspondence. The hard magnetic film is composed of a plurality of hard magnetic films having a shape extending in the longitudinal direction, and these hard magnetic films may be patterned at the same pitch as the soft magnetic film of the magnetic sensitive portion. .

  Further, in the magneto-impedance effect element of the present invention, the thin film magnet is composed of one hard magnetic film formed over a region wider than the magnetic sensing part in the width direction of the magnetic sensing part, The yoke portion has the same width as the width of the thin film magnet at the end on the thin film magnet side or wider than the width of the thin film magnet, and the same width as the entire width of the magnetic sensing portion at the end on the magnetic sensitive portion side. It can also be.

  Examples of the hard magnetic film constituting the thin film magnet include a metal film containing Co or Fe as a main component and one or both of Pt and Cr.

  The present invention also provides a method of manufacturing the above-described magneto-impedance effect element, the step of forming a hard magnetic film having in-plane isotropy on a nonmagnetic substrate, and covering the hard magnetic film. And a step of forming an insulating layer having the opening, a step of forming a soft magnetic film serving as the magnetic sensitive portion and the yoke portion on the insulating layer, a heat treatment in a rotating magnetic field, and a subsequent heat treatment in a static magnetic field. By applying uniaxial anisotropy to the soft magnetic film to form a magnetically sensitive portion, and magnetizing the hard magnetic film in a static magnetic field or a pulsed magnetic field to form a thin film magnet And a method of manufacturing a magneto-impedance effect element comprising the steps.

According to the magneto-impedance effect element of the present invention, since the thin film magnet is formed below the magnetic sensitive part via the insulating layer, the magnetic sensitive part is biased with no power by the magnetic field generated by the thin film magnet. A magnetic field can be applied, and a linear output can be obtained near zero magnetic field.
In addition, a soft magnetic film is formed from the end of the thin film magnet to the vicinity of the end of the magnetosensitive part at the end of the thin film magnet disposed on the lower side, and a magnetic path is provided between the thin film magnet and the magnetosensitive part. By forming the yoke portion to be formed, the magnetic flux emitted from the end portion of the thin film magnet can be focused and guided to the vicinity of the end portion of the magnetic sensitive portion, and the generated magnetic flux can be efficiently used as a bias magnetic field.

  By assuming that the yoke portion is in direct contact with the end portion of the thin film magnet, most of the magnetic flux generated in this portion is sucked into the yoke portion, and the leakage magnetic field can be reduced. Further, since the thin film magnet and the yoke part are electrically insulated from the magnetic sensitive part, it is possible to apply a bias magnetic field without impairing the characteristics as the magneto-impedance effect element.

  If the thin-film magnet has a structure in which thin, substantially rectangular hard magnetic films are arranged in the same manner as the soft magnetic film of the magnetic sensitive part, the demagnetizing field generated inside the thin-film magnet can be reduced. The efficiency of magnetic field generation from the thin film magnet can be increased.

  A thin-film magnet is constituted by a single hard magnetic film formed over a region wider than the magnetic-sensitive portion in the width direction of the magnetic-sensitive portion, and the yoke portion is a thin-film magnet at the end on the thin-film magnet side. The width of the thin film magnet (the width of the end) is increased by making the width of the thin film magnet the same as or wider than the width of the magnet, and at the end on the side of the magnetic sensitive portion to be approximately the same as the width of the entire magnetic sensitive portion. By increasing the generated magnetic flux and further constricting the magnetic flux in the yoke portion that narrows toward the magnetic sensitive portion, the magnetic flux density applied to the magnetic sensitive portion can be increased.

The present invention will be described below with reference to the drawings based on the best mode.
1 and 2 show one embodiment of the magneto-impedance effect element of the present invention. Here, in FIG. 2A, since the thin film magnet is hidden under the insulating layer and the yoke portion, the range in which the thin film magnet is provided is indicated by a one-dot chain line. Further, in FIG. 2B, in order to explain the arrangement of the thin film magnet and the yoke portion on the nonmagnetic substrate, it is represented as a plan view in a state where the thin film magnet is provided on the nonmagnetic substrate. A range in which the yoke portion is provided is indicated by a two-dot chain line.

  The magneto-impedance effect element 10 of this embodiment is formed on a thin film magnet 12 made of a hard magnetic film formed on a nonmagnetic substrate 11, an insulating layer 13 covering the thin film magnet 12, and the insulating layer 13. A magnetic sensing portion 14 made of a plurality of rectangular soft magnetic films provided with uniaxial anisotropy, and a conductor film 16 that electrically connects the plurality of soft magnetic films of the magnetic sensing portion 14. In the longitudinal direction of the magnetic sensing part 14, both end portions of the thin film magnet 12 are located outside the both end portions of the magnetic sensing part 14, and the insulating layer 13 has openings 13 a on the respective end portions of the thin film magnet 12. A yoke portion 15 made of a soft magnetic film is provided on the insulating layer 13 from the end of the thin film magnet 12 through the opening 13 a of the insulating layer 13. It is formed in the vicinity of the part. In this embodiment, the magnetic sensitive part may be composed of one soft magnetic film.

  The nonmagnetic substrate 11 is not particularly limited as long as it is a substrate made of a nonmagnetic material. Examples include a semiconductor substrate such as silicon and a substrate such as glass.

  The thin film magnet 12 is formed by magnetizing a thin film made of a hard magnetic material, and is provided to apply a bias magnetic field to the soft magnetic material film of the magnetic sensing portion 14. As a material constituting the hard magnetic film, a metal film containing Co or Fe as a main component and containing one or both of Pt and Cr is preferable. Specific examples thereof include FePt, CoPt, CoCrPt, and CoCr. A hard magnetic metal (alloy) is mentioned. In particular, by using a hard magnetic film having isotropic magnetic characteristics in the film surface, such as FePt, CoPt, CoCrPt, and CoCr (in these formulas, the composition ratio of the alloy is not particularly shown), a bias is obtained. The magnetic field can be controlled more accurately.

The insulating layer 13 is made of a non-magnetic insulator in order to insulate between the thin film magnet 12 and the magnetic sensing part 14. Examples of the insulator include metal oxides such as SiO ₂ and Al ₂ O ₃ , metal nitrides such as Si ₃ N ₄ and AlN, and the like.

The soft magnetic film serving as the magnetic sensitive part 14 is a rectangular soft magnetic film provided with uniaxial anisotropy. The soft magnetic material constituting the soft magnetic film is not particularly limited as long as it can impart uniaxial anisotropy, and examples thereof include Co ₈₅ Nb ₁₂ Zr ₃ .
In this embodiment, as shown in FIG. 2 (a), a plurality of rectangular soft magnetic films are arranged with their longitudinal directions parallel to each other, and adjacent soft magnetic films are folded at their ends. It is electrically connected in a width direction (vertical direction in FIG. 2A) perpendicular to the longitudinal direction through a conductive film (connection pad) 16 so as to have a shape. In addition, electrode pads 17 are provided at both ends of the plurality of soft magnetic films connected in series to be electrically connected to the outside. The connection pad 16 and the electrode pad 17 can be made of a good conductor such as copper (Cu), gold (Au), or aluminum (Al).

  Since the thin film magnet 12 made of the hard magnetic film is formed below the magnetic sensitive part 14 made of the soft magnetic film via the insulating layer 13, the magnetic field generated by the thin film magnet 12 causes the magnetic sensitive part 14 to On the other hand, a bias magnetic field can be applied with no power, and a linear output can be obtained in the vicinity of zero magnetic field.

  In the magneto-impedance effect element 10 of the present embodiment, both end portions of the thin film magnet 12 are located outside both end portions of the magnetosensitive portion 14 in the longitudinal direction of the magnetosensitive portion 14 (left and right direction in FIG. 2A). The insulating layer 13 has an opening 13 a on each end of the thin film magnet 12, and a yoke portion 15 made of a soft magnetic film is formed on the insulating layer 13. The thin film magnet 12 is formed from the end portion of the thin film magnet 12 to the vicinity of the end portion of the magnetosensitive portion 14 through the opening portion 13a. Here, the longitudinal direction is the longitudinal direction of the rectangular soft magnetic film of the magnetic sensitive portion 14.

  Here, since the yoke portion 15 is made of a soft magnetic material having a high magnetic permeability, a magnetic path is formed from the thin film magnet 12 through the yoke portion 15, and the generated magnetic flux from the thin film magnet 12 is transferred to the end of the magnetic sensing portion 14. It works to induce. Thereby, the magnetic field generated from the thin film magnet 12 can be efficiently applied to the magnetic sensing unit 14, and the leakage magnetic field from the thin film magnet 12 can be reduced. Even when it is necessary to arrange multiple sensor chips in one package, the fluctuation of the bias magnetic field due to the leakage magnetic field from the adjacent sensor chips can be reduced, so that it is possible to deal with arrangements where the interval between sensors is narrow, and design freedom The degree of improvement, miniaturization and integration can be achieved.

  The yoke portion 15 is preferably in direct contact with the end of the thin film magnet 12 and is not electrically connected to the magnetic sensitive portion 14. Thereby, it can suppress that the magnetic flux generated from the thin film magnet 12 becomes a leakage magnetic field without being guided to the yoke portion 15. Examples of the distance between the yoke portion and the end portion in the longitudinal direction of the magnetic sensitive portion include 1 to 100 μm. The soft magnetic material film used as the yoke portion 15 is preferably made of the same material as the soft magnetic material film of the magnetic sensitive portion 14, and in this case, the magnetic sensitive portion 14 and the yoke portion 15 can be manufactured by the same process. .

  Further, as shown in FIG. 1, the end portion of the yoke portion 15 on the thin film magnet 12 side covers the outside of the end portion in the longitudinal direction of the thin film magnet 12 (the end portion of the thin film magnet 12 and the insulating layer 13. The soft magnetic film that forms the yoke portion 15 is interposed between the side surface of the opening portion 13a), so that the magnetic flux generated from the end portion of the thin film magnet 12 is efficiently attracted and guided to the magnetic sensitive portion 14. Can do. Even when the yoke portion 15 is not in direct contact with the thin film magnet 12, the generated magnetic flux is efficiently attracted by covering the direction in which the magnetic flux generated from the end portion of the thin film magnet 12 goes out with the yoke portion 15. It can guide to the part 14 and can eliminate the leakage of the magnetic flux to the outside.

  Further, since the end portion of the yoke portion 15 on the magnetic sensing portion 14 side is formed on the upper surface of the same insulating layer 13 as the magnetic sensing portion 14, the height of the yoke portion 15 and the magnetic sensing portion 14 is aligned. . For this reason, the direction in which the bias magnetic flux is output from the end of the yoke portion 15 toward the end of the magnetic sensing portion 14 can be more accurately set as the in-plane direction.

  In addition, in the opening 13a of the insulating layer 13, since the inclined surface 13b is formed at a position where the yoke portion 15 rides on the insulating layer 13 from the end side of the thin film magnet 12, the height of the yoke portion 15 changes gently. In addition, magnetic flux leakage and internal distortion of the soft magnetic film can be reduced.

  Further, in a plan view of the nonmagnetic substrate 11 as viewed from above (see FIG. 2A), the region where the thin film magnet 12 is formed is in a wider range than the region where the magnetosensitive portion 14 is formed. In addition, the region where the magnetic sensitive part 14 is formed entirely overlaps the region where the thin film magnet 12 is formed. Thereby, it is possible to avoid the influence of the demagnetizing field generated at the end of the thin-film magnet 12 from being exerted on the magnetic sensing part 14, and a uniform bias magnetic field can be applied to the magnetic sensing part 14.

  In the magneto-impedance effect element 10 described above, one thin film magnet 12 is provided. However, in the present invention, a plurality of thin film magnets may be provided. For example, in the magneto-impedance effect element 20 shown in FIG. 3 (the cross section along the soft magnetic film of the magnetic sensing portion 24 is the same as the first embodiment (see FIG. 1B)). The magnetic sensing part 24 is composed of a plurality of soft magnetic films, and the thin-film magnet 22 has a plurality of hard films having a shape extending in the longitudinal direction corresponding to each soft magnetic film of the magnetic sensing part 24. These hard magnetic films are made of a magnetic film, and are patterned at the same pitch as the soft magnetic film of the magnetic sensing portion 24. Thereby, since the demagnetizing field generated inside the thin film magnet 22 can be reduced, the magnetic field generation efficiency can be increased. In each soft magnetic film of the magnetic sensing section 24, a magnetic field can be applied uniformly in the width direction, and in order to suppress magnetic field leakage due to the spread of the magnetic field in the width direction, the soft magnetic film and the thin film magnet of the magnetic sensing section 24 It is preferable that the 22 hard magnetic films have the same width.

  In the case of the magneto-impedance effect element 20 shown in FIG. 3, the soft magnetic material film of the magnetic sensing portion 24 and the hard magnetic material of the thin film magnet 22 are also used for the yoke portion 25 made of the soft magnetic material film formed on the insulating layer 23. The same number is arranged at the same pitch in the width direction of the film, and the thin film magnet 22, the yoke part 25, and the magnetic sensitive part 24 correspond to each other one to one. As a result, the magnetic flux generated from each thin film magnet 22 is guided to the end of the magnetic sensing portion 24 through the separate yoke portion 25, so that the magnetic flux is prevented from spreading in the width direction, and the induction efficiency of the generated magnetic field is reduced. Can be increased.

  In the example of FIG. 3, the opening 23 a of the insulating layer 23 is formed at one place on both sides in the longitudinal direction of the magnetic sensing portion 24, and a soft magnetic film that becomes the yoke portion 25 is formed in one opening 23 a. It is assumed that a plurality are provided. This simplifies the patterning of the opening 23a. As a modification, a plurality of openings may be arranged in the width direction, and a soft magnetic film serving as a yoke part may be provided in each opening.

  In the above example, the yoke portions 15 and 25 have a uniform width in the width direction. However, as another example, as shown in FIG. The thin film magnet 32 is composed of one hard magnetic film formed over a wide area, and the yoke portion 35 is equal to or smaller than the width of the thin film magnet 32 at the end on the thin film magnet 32 side. The width of the entire magnetic sensing part 34 is wide at the end of the magnetic sensing part 34 (in the case where the magnetic sensing part 34 is made of a single soft magnetic film, the width of the soft magnetic film is the When the portion 34 is composed of a plurality of soft magnetic films, it is not the width of one soft magnetic film but the entire width including the region where all the soft magnetic films are provided. It can also be set as the structure which is. In this embodiment, the magnetic sensitive part may be composed of one soft magnetic film.

  In the case of such a magneto-impedance effect element 30, the generated magnetic flux is increased by increasing the width of the thin film magnet 32, and the yoke portion 35 is focused at a portion 35a that is gradually narrowed toward the magnetic sensing portion 34 side. By doing so, the magnetic flux density applied to the magnetic sensing part 34 can be increased. In this example, in order to increase the generated magnetic field, it is preferable that the thin film magnet 32 has the same width as that of the nonmagnetic substrate 31 (slightly narrower than the chip width). The thin film magnet 32 may be provided on the entire surface of the nonmagnetic substrate 31.

  In the example of FIG. 4, the opening 33 a of the insulating layer 33 is formed to have a uniform width that can receive the maximum width of the yoke portion 35. As a modified example, the width of the opening 33a may be changed corresponding to the portion 35a where the width of the yoke portion 35 is narrow.

  3 and 4, the non-magnetic substrates 21 and 31, the thin film magnets 22 and 32, the insulating layers 23 and 33, the magnetic sensing portions 24 and 34, the yoke portions 25 and 35, and the connection pads. 26 and 36 and electrode pads 27 and 37 are made of materials and manufacturing methods such as the non-magnetic substrate 11, the thin film magnet 12, the insulating layer 13, the magnetic sensing part 14, the yoke part 15, and the magneto-impedance effect element 10 shown in FIGS. The connection pads 16 and the electrode pads 17 can be the same, and redundant description is omitted. 3 and 4 are the same as those in FIG. 1 except that the reference numerals of the corresponding portions are different, and the cross-sectional views thereof are omitted.

Next, an example of a method for manufacturing the above-described magneto-impedance effect element will be described.
First, a hard magnetic film having in-plane isotropy is formed on a nonmagnetic substrate made of silicon or glass. As a method of forming a hard magnetic film having a desired planar shape, for example, a resist pattern having an opening corresponding to the hard magnetic film is provided on a nonmagnetic substrate by photolithography, and by sputtering a hard magnetic metal, etc. There is a method of forming a hard magnetic film and then patterning by lift-off after removing the resist.

  The hard magnetic film is annealed in a reducing atmosphere at a temperature of about 600 to 800 ° C. after forming the film, so that it takes a regularized structure and exhibits more isotropic magnetic characteristics, thereby increasing the coercive force. To do.

Next, an insulating layer covering the hard magnetic film and having the opening is formed. In this insulating layer, as a method of forming an insulating layer covering the hard magnetic film, an insulating film is formed on the entire surface by a method such as plasma CVD, and then an opening is formed by etching or the like. Examples thereof include a method of exposing an end portion of the film, a method of providing a resist at a position where an opening is provided, and a method of forming an insulator on the other portion. For example, an SiO ₂ film having an opening is formed by forming a SiO ₂ film on the entire surface by plasma CVD using tetraethoxysilane (TEOS) and then a fluorine-based gas such as tetrafluoromethane ((CF ₄ )). The opening is formed by the reactive ion etching method using the, and the end of the hard magnetic film is exposed.

Next, a soft magnetic film is formed on the insulating layer to serve as a magnetic sensitive part and a yoke part.
As a method of forming the soft magnetic film, for example, a resist pattern is provided on the insulating layer by photolithography, and after forming the soft magnetic film by sputtering of a soft magnetic metal, the resist is removed and patterning is performed by lift-off. A method is mentioned. The pattern of the yoke part is a pattern that is in direct contact with the end of the hard magnetic film inside the opening and reaches the vicinity of the end of the magnetic sensing part from the opening on the insulating layer.

Further, the connection pads and the electrode pads at both ends, which are connected in series between the plurality of soft magnetic films, are formed of a conductor film. As a method of forming a conductor film pattern, a good conductor such as Al, Cu, Au or the like is formed by sputtering or the like, a resist pattern is provided on the obtained conductor film by photolithography, and then the conductor film is formed by wet etching. The method of patterning is mentioned.
In the case where the magnetic sensitive part is made of one soft magnetic film, a connection pad for conducting and connecting in series between the plurality of soft magnetic films can be omitted.

  Next, uniaxial anisotropy along the width direction of the soft magnetic film is imparted to the soft magnetic film. Examples of the method for imparting uniaxial anisotropy include a method of performing a heat treatment in a rotating magnetic field at 400 ° C. and 3 kG, and subsequently performing a heat treatment in a static magnetic field at 400 ° C. and 3 kG. In the heat treatment in the rotating magnetic field, the non-uniform anisotropy introduced into the soft magnetic film during film formation can be relaxed. In the heat treatment in the static magnetic field, the direction of the magnetic field applied to the soft magnetic film is uniaxially different. A directionality can be imparted. As a result, a magnetosensitive part made of a soft magnetic film to which uniaxial anisotropy is imparted can be obtained. At this time, the same uniaxial anisotropy is imparted to the soft magnetic film serving as the yoke portion, but the yoke portion is not a portion through which an electric current is passed, so regardless of whether or not the uniaxial anisotropy is imparted. Acts as a yoke part.

  Next, the hard magnetic film is magnetized in a static magnetic field or a pulsed magnetic field. Examples of the method of magnetizing the hard magnetic film include a method of applying a pulsed or DC magnetic field that is larger than the coercive force of the hard magnetic film. Through this magnetization process, the hard magnetic film becomes a thin permanent magnet (thin film magnet), and has a function of applying a bias magnetic field to the magnetosensitive portion.

  In the magneto-impedance element thus obtained, a yoke portion made of a soft magnetic film is provided at the end of a thin film magnet made of a hard magnetic film, and the magnetic flux generated from the end of the thin film magnet is transferred to the magnetosensitive portion. It works to guide to the vicinity. That is, this yoke portion forms a magnetic path between the end of the thin film magnet and the end of the magnetic sensing portion so that a bias magnetic field is efficiently applied to the magnetic sensing portion and reduces the leakage magnetic field. be able to.

  The magneto-impedance effect element of the present invention can be used as a highly sensitive magnetic sensor, for example, for an electronic compass, a rotary encoder, a biomagnetic measurement and the like that detect the geomagnetism and indicate its direction.

It is sectional drawing which follows the II line | wire of Fig.2 (a) which shows one example of the magneto-impedance effect element of this invention. (A) is a top view which shows one example of the magneto-impedance effect element of this invention, (b) is explanatory drawing which shows arrangement | positioning of the thin film magnet and yoke part on a nonmagnetic board | substrate. (A) is a top view which shows the 2nd form example of the magneto-impedance effect element of this invention, (b) is explanatory drawing which shows arrangement | positioning of the thin film magnet and yoke part on a nonmagnetic board | substrate. (A) is a top view which shows the 3rd form example of the magneto-impedance effect element of this invention, (b) is explanatory drawing which shows arrangement | positioning of the thin film magnet and yoke part on a nonmagnetic board | substrate.

Explanation of symbols

10, 20, 30 ... magneto-impedance effect element, 11, 21, 31 ... non-magnetic substrate, 12, 22, 32 ... thin film magnet (hard magnetic film), 13, 23, 33 ... insulating layer, 13a, 23a, 33a ... opening, 13b, 23b, 33b ... slope, 14, 24, 34 ... magnetic sensitive part (soft magnetic film), 15, 25, 35 ... yoke part (soft magnetic film), 35a ... width changes , 16, 26, 36... Connection pads (conductor film), 17, 27, 37... Electrode pads (conductor film).

Claims (7)

A thin film magnet made of a hard magnetic film formed on a nonmagnetic substrate, an insulating layer covering the thin film magnet, and one or a plurality of uniaxial anisotropies formed on the insulating layer A magnetic sensing portion comprising a rectangular soft magnetic film, and a conductor film for electrically connecting a plurality of soft magnetic films of the magnetic sensing portion;
In the longitudinal direction of the magnetic sensing portion, both end portions of the thin film magnet are located outside both end portions of the magnetic sensing portion, and the insulating layer has an opening on each end portion of the thin film magnet. On the insulating layer, a yoke portion made of a soft magnetic film that forms a magnetic path between the thin film magnet and the magnetically sensitive portion is disposed through the opening of the insulating layer. A magneto-impedance effect element formed from the end of a thin film magnet to the vicinity of the end of the magnetosensitive portion.   2. The magneto-impedance effect element according to claim 1, wherein the yoke portion is in direct contact with an end portion of the thin film magnet and is not electrically connected to the magnetic sensing portion.   3. The magneto-impedance effect element according to claim 2, wherein the yoke portion has an interval of 1 to 100 μm between an end portion in a longitudinal direction of the magnetic sensing portion.   The magnetic sensing part has a plurality of soft magnetic films, and the thin film magnet has a plurality of shapes extending in the longitudinal direction corresponding to each soft magnetic film of the magnetic sensing part. 4. The magneto-impedance effect element according to claim 3, wherein the hard magnetic film is patterned at the same pitch as the soft magnetic film of the magnetic sensitive part. The thin film magnet is composed of one hard magnetic film formed over a region wider than the magnetic sensing part in the width direction of the magnetic sensing part,
The yoke portion is equal to or wider than the width of the thin-film magnet at the end on the thin-film magnet side, and is approximately the same as the width of the entire magnetic-sensitive portion at the end on the magneto-sensitive portion side. The magneto-impedance effect element according to claim 3.   6. The hard magnetic film constituting the thin film magnet is a metal film containing Co or Fe as a main component and containing one or both of Pt and Cr. Magnetic impedance effect element. It is a manufacturing method of the magneto-impedance effect element according to any one of claims 1 to 6,
Forming a hard magnetic film having in-plane isotropy on a non-magnetic substrate;
Forming an insulating layer covering the hard magnetic film and having the opening;
Forming a soft magnetic film to be the magnetically sensitive portion and the yoke portion on the insulating layer;
A step of imparting uniaxial anisotropy to the soft magnetic film by a heat treatment in a rotating magnetic field and a subsequent heat treatment in a static magnetic field to form a magnetosensitive part;
Magnetizing the hard magnetic film in a static magnetic field or a pulsed magnetic field to form a thin film magnet;
A method for manufacturing a magneto-impedance effect element, comprising:

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