JP2002084015A - Magneto-electric conversion element and magnetic sensor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-electric conversion element which is excellent in characteristic stability and reliability. SOLUTION: The magneto-electric conversion element 1 includes a magnetoresistive effect film 12 in which plural short-circuit films 14 are formed on one surface, plural terminals 20 which are connected electrically with the other surface of the film 12, and a substrata 18 disposed on the one surface side of the film 12. The short-circuit film 1 is formed by laminating an upper layer 14b composed of noble metal excellent in anticorrosion on a connection layer 14a composed of metal excellent in adhesion to the film 12. In the short- circuit film 14, a diffusion preventing layer 14c may be laminated between the connection layer 14a and the upper layer 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-electric transducer, and more particularly, to a magneto-electric transducer used for an angle sensor, a rotation sensor, or the like, which applies a property that a resistance value changes with respect to an external magnetic field.

[0002]

2. Description of the Related Art A conventional magnetoelectric conversion element which is the background of the present invention is disclosed in Japanese Patent Application Laid-Open No. 9-8379. A conventional magnetoelectric conversion element has a meanderline-shaped magnetoresistance effect film. A large number of short-circuit films are formed at the folded portion on one surface of the magnetoresistive effect film and at some points on the way. This short-circuit film is formed by laminating a metal film made of Ti, which has a high adhesive strength to InSb, and a metal film made of Al, which is easily formed and has high reliability. Then, the surface of the magnetoresistive film on which the short-circuit film is formed is bonded to the magnetic substrate by a resin layer such as an epoxy resin. A solder-plated terminal is thermocompression-bonded to the other surface of the magnetoresistive film. Further, a protective film made of an organic material such as an epoxy resin or an inorganic material such as silica or alumina is formed thereon.

[0003]

However, in the above-described conventional magnetoelectric conversion element, since the upper layer of the short-circuit film is formed of Al, it may be corroded by a corrosive gas or the like and may not operate as a magnetoelectric conversion element. there were. Further, there is a case where Al in the upper layer of the short-circuit film diffuses into the connection layer or the magnetoresistive effect film, so that the characteristics of the magnetoelectric conversion element may fluctuate.

[0004] Therefore, a main object of the present invention is to provide a magnetoelectric conversion element having stable characteristics and high reliability.

[0005]

A magnetoelectric conversion element according to the present invention comprises a magnetoresistive film having a plurality of short-circuit films formed on one surface, and a plurality of magnetoresistive films electrically connected to the other surface of the magnetoresistive film. And a substrate provided on one side of the magnetoresistive film, wherein the short-circuit film is formed by laminating an upper layer made of a noble metal on a connection layer made of a metal having good adhesion to the magnetoresistive film. This is a magneto-electric conversion element. The magnetoelectric conversion element according to the present invention includes a magnetoresistive film having a plurality of short-circuit films formed on one surface, a plurality of terminals electrically connected to the other surface of the magnetoresistive film, A magnetoelectric conversion element including a substrate provided on one side of the film, wherein the short-circuit film is formed between a connection layer made of a metal having good adhesion to the magnetoresistive effect film and an upper layer made of a metal having good conductivity. And a magneto-electric conversion element provided with a diffusion prevention layer for preventing diffusion of the upper metal. Further, in the magnetoelectric conversion element according to the present invention, a magnetoresistance effect film is provided on one substrate in series and / or parallel connection,
It is preferable to connect terminals between the magnetoresistive films. A magnetic sensor according to the present invention is a magnetic sensor including the above-described magnetoelectric conversion element, a magnet that applies a bias magnetic field to the magnetoelectric conversion element, and a case that houses the magnetoelectric conversion element and the magnet. .

In the magnetoelectric conversion element according to the present invention, since the upper layer of the short-circuit film is formed of a noble metal, it is hardly corroded by corrosive gas, and the durability and reliability are improved. Further, when the short-circuit film has a three-layer structure of a connection layer, a diffusion prevention layer, and an upper layer, the components constituting the upper layer are prevented from diffusing into the connection layer and the magnetoresistive film, so that the magnetoelectric conversion element is prevented. Is prevented from changing. Further, when a magnetoresistive film is provided in series and / or in parallel on one substrate, and terminals are respectively connected between the magnetoresistive films,
An element in which a plurality of magnetoresistive films are connected on one chip can be obtained. In this case, since patterns can be formed collectively for each wafer at the time of manufacture, resistance variations are reduced and output characteristics are stabilized. Further, cost can be reduced by reducing the number of terminal junction points and the number of chip mounting steps.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.

[0008]

FIG. 1 is a schematic plan view showing a surface of a magnetoelectric conversion element according to a first embodiment of the present invention which is bonded to a substrate. The magnetoelectric conversion element 1 includes magnetoresistive films 12a and 12b made of a semiconductor material such as InSb.
including. Each of the magnetoresistive films 12a and 12b has a meandering line shape, and a plurality of short-circuit films 14, 14 are formed on one surface thereof. These short-circuit films 1
4,... 14 short-circuit the current flowing through the magnetoresistive films 12a and 12b, thereby forming the magnetoresistive films 12a and 12b.
12b is electrically divided into a large number, and the multiple magnetoresistive films 12a and 12b are equivalently connected in series. The short-circuit film 14 is connected to the connection layer 14a.
And the upper layer 14b are laminated. Connection layer 14a
Is formed of a metal film such as Ti having a high adhesive strength to the semiconductor material forming the magnetoresistive films 12a and 12b. The upper layer 14b is formed of a noble metal film such as Au, which is hardly corroded by corrosive gas or the like.

FIG. 2 is an illustrative sectional view taken along line II-II in FIG. Short-circuit film 1 of magnetoresistive films 12a and 12b
The surface on which 4,, and 14 are formed is bonded to a substrate 18 made of a magnetic material by a resin layer 16 such as an epoxy resin.
Solder-plated terminals 20a, 20b, 20c are thermocompression-bonded to the other surfaces of the magnetoresistive films 12a, 12b.
At this time, the terminal 20 a is connected between the magnetoresistive films 12 a and 12 b connected in series on one substrate 18. Further, a terminal 20b is connected to the magnetoresistive effect film 12a,
The terminal 20c is connected to the magnetoresistive film 12b. Then, a protective film 22 made of an organic material such as an epoxy resin or an inorganic material such as silica or alumina is formed thereon.

FIG. 3 is an equivalent circuit diagram of the magnetoelectric conversion element 1 shown in FIG. The magneto-electric transducer 1 has two magneto-resistive elements connected in series on a single substrate 18 to obtain a one-phase output. By forming a voltage dividing circuit by connecting two magnetoresistive elements in series on one substrate 18 and extracting a differential output, the temperature change of the magnetoresistive element alone is canceled out, and the temperature characteristics are improved. Further, since the structure of pattern wiring on one substrate 18 can be formed collectively for each wafer, resistance variation between the two magnetoresistive elements is reduced, and output characteristics are stabilized. Also, the number of connection points can be reduced and the number of steps can be reduced as compared with the case where a single magnetic resistance element is connected in series to form a voltage dividing circuit, so that the manufacturing cost can be reduced.

A method for manufacturing the magneto-electric transducer 1 of the first embodiment will be described below. First, a bulk made of, for example, InSb having a magnetoresistance effect is prepared. Next, in a first step, magnetoresistive films 12a and 12b are formed on one surface of the bulk by photolithography. Next, in a second step, a connection layer 14a of Ti and an upper layer 14b of Au are formed on the magnetoresistive films 12a and 12b by vapor deposition. Next, in a third step, the connection layer 14a and the upper layer 14b are intermittently formed by photolithography and etching to form a plurality of short-circuit films 14. Next, in a fourth step, the surface on which the short-circuit film 14 is formed is bonded to the substrate 18 via a resin layer 16 made of epoxy resin or the like. Next, in a fifth step, the bulk is polished while leaving the magnetoresistive films 12a and 12b. Next, in a sixth step, the substrate 18 is cut into individual elements, and further, in the seventh step, the terminals 20a to
20c is electrically connected by thermocompression to the ends of the surfaces of the magnetoresistive films 12a and 12b opposite to the surface on which the short-circuit film 14 is formed. Then, in the eighth step, the magnetoresistance effect film 12 is formed.
A protective film 22 made of an organic material such as an epoxy resin or a polyimide resin or an inorganic material such as silica or alumina is formed on a and 12b to obtain the magnetoelectric conversion element 1.

FIG. 4 is a schematic plan view showing another pattern of the magnetoresistive film in the magnetoelectric conversion element of the first embodiment shown in FIG. In this pattern, linearly formed magnetoresistive films 12a and 12b are connected in series, and a terminal 20a is connected between them. The terminal 20b is connected to the magnetoresistive film 12a, and the terminal 20c is connected to the magnetoresistive film 12c. Magnetoresistance effect film 12a, 12b
The short-circuit film 14 having the same laminated structure as that of the embodiment shown in FIGS. 1 and 2 is formed on the surface connected to the substrate 18. The magnetoelectric conversion element 2 using the pattern of FIG. 4 also has the equivalent circuit shown in FIG.

FIG. 5 is a schematic plan view showing still another pattern of the magnetoresistive film in the magnetoelectric transducer of the first embodiment. FIG. 6 is an equivalent circuit diagram of the magnetoelectric conversion element 3 according to the pattern shown in FIG. In this pattern, the magnetoresistive films 12a and 12b connected in series and the magnetoresistive films 12c and 12d connected in series are connected in parallel, and the terminals 20a, 20b, 20c, and Terminal 20d is connected. Magnetoresistance effect films 12a-1
A plurality of short-circuit films 14 similar to the embodiment shown in FIGS. 1 and 2 are intermittently formed on the surface connected to the 2d substrate 18. The magnetoelectric conversion element 3 using this pattern
Since a two-phase output can be obtained, for example, the rotation direction (forward or reverse) of the gear can be detected with one chip.

FIG. 7 is an illustrative sectional view showing a second embodiment of the magnetoelectric transducer according to the present invention. The magnetoelectric conversion element 4 shown in FIG. 7 differs from the magnetoelectric conversion element shown in FIGS. 1 to 6 only in the structure of the short-circuit film 14. The short-circuit film 14 of the magnetoelectric conversion element 4 has a three-layer structure in which a diffusion preventing layer 14c is stacked between a connection layer 14a and an upper layer 14b. The upper layer 14b is made of, for example, Al, Ag, Cu, A
It is formed of a highly conductive metal such as u or Pt. The connection layer 14a is formed of a metal having good adhesion to the magnetoresistive films 12a to 12d, such as Cr, NiCr, and Ti. The diffusion preventing layer 14c is made of, for example, Cr, Ni,
It is formed of a metal having a high interlayer diffusion preventing effect, such as W or Mo.

FIG. 8 is an illustrative sectional view showing an example of a magnetic sensor using the magnetoelectric conversion element according to the present invention. The magnetic sensor 5 includes a circuit board 32. On one surface of the circuit board 32, the magnetoelectric conversion element 1 (2, 3, or 4) is fixed with an adhesive or the like. A magnet 34 for applying a bias magnetic field to the magnetoelectric conversion element 1 is provided on the other surface of the circuit board 32.
Is fixed with the filler 36. The magnetoelectric element 1, the circuit board 32, and the magnet 34 are housed in a non-magnetic protective case 30. The lead terminals 38 are fixed to the circuit board 32. The heads of the lead terminals 38, 38 and the terminals 20a, 20b, 2 of the magnetoresistive element 1 (2, 3, or 4)
0c is electrically connected to each other through connectors 40, such as wires and lead frames.

In this embodiment, the case where the substrate is made of a magnetic material has been described. However, the present invention is not limited to the magnetic material, and may be a dielectric, an insulator, or a semiconductor.
Further, the substrate made of a magnetic material may be used as a ferrite top and adhered to the magnetoresistive film with a resin layer. In such an example, the protective film need not be formed.
Furthermore, as a method of manufacturing a magnetoresistive effect film, a method of polishing and forming a bulk of InSb has been described. May be formed. Further, a pattern in which two sets of magnetoresistive elements connected in series are connected in parallel on one substrate 18 may be formed so as to obtain a four-phase output.

[0017]

According to the present invention, since the substrate has a structure in which the substrate is adhered to the surface of the magnetoresistive film on which the short-circuit film is formed and the terminal is connected to the opposite surface, the wettability to the solder is improved. Can be formed without considering the above. Further, since the magnetoresistive film functions as a protective film, the moisture resistance of the magnetoelectric conversion element is improved. In particular, by forming the upper layer of the short-circuit film with a noble metal film, the weather resistance, durability, and reliability of the magnetoelectric conversion element are improved. Also, the short-circuit layer is a connection layer,
In the case of a three-layer structure including a diffusion prevention layer and an upper layer, the components constituting the upper layer are prevented from diffusing into the connection layer and the magnetoresistive layer, so that a change in characteristics is prevented, and the Reliability is improved. Further, when a magnetoresistive film is connected in series and / or in parallel on one substrate, and terminals are respectively connected between the magnetoresistive films, a pattern is collectively formed for each wafer during manufacturing. As a result, resistance variations are reduced and output characteristics are stabilized. Further, since the number of terminal joints and the number of chip mounting steps can be reduced, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a surface of a magnetoelectric conversion element according to a first embodiment of the present invention which is bonded to a substrate.

FIG. 2 is an illustrative sectional view taken along line II-II shown in FIG.

FIG. 3 is an equivalent circuit diagram of the magnetoelectric conversion element according to the patterns shown in FIGS. 1 and 4.

FIG. 4 is an illustrative plan view showing another pattern of the magnetoresistive film in the magnetoelectric transducer of the first embodiment.

FIG. 5 is an illustrative plan view showing still another pattern of the magnetoresistance effect film in the magnetoelectric transducer of the first embodiment.

FIG. 6 is an equivalent circuit diagram of the magnetoelectric conversion element according to the pattern shown in FIG.

FIG. 7 is an illustrative sectional view showing a second embodiment of the magnetoelectric conversion element according to the present invention.

FIG. 8 is an illustrative sectional view showing one example of a magnetic sensor using a magnetoelectric conversion element according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2, 3, 4 Magnetoelectric conversion element 5 Magnetic sensor 12 Magnetoresistive film 14 Short circuit film 14a Connection layer 14b Upper layer 14c Diffusion prevention layer 16 Resin layer 18 Substrate 20a, b, c terminal 22 Protective film 30 Nonmagnetic protective case 32 Circuit board 34 Magnet 36 Filler 38 Lead terminal 40 Connector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 43/02 G01B 7/30 101B // G01B 7/30 101 G01D 5/245 R G01D 5/245 G01P 3 / 488 D G01P 3/488 G01R 33/06 R (72) Inventor Tamotsu Minamiya 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. F-term (reference) 2F063 AA35 CA40 DA05 EA03 GA52 GA79 KA02 2F077 AA41 PP14 VV01 VV33 2G017 AC06 AC09 AD55 AD61 AD65 AD66 5D034 BA02 BA03 BA08 BA21 BB02 DA07 5E049 AA01 AA07 AA09 AA10 AC05 BA16 CB01

Claims (4)

[Claims] 1. A magnetoresistive film having a plurality of short-circuit films formed on one surface, a plurality of terminals electrically connected to the other surface of the magnetoresistive film, and one surface of the magnetoresistive film. And a substrate provided on the side, wherein the short-circuit film is formed by laminating an upper layer made of a noble metal having good corrosion resistance to a connection layer made of a metal having good adhesion to the magnetoresistive effect film, Magnetoelectric conversion element. 2. A magnetoresistive film having a plurality of short-circuit films formed on one surface, a plurality of terminals electrically connected to the other surface of the magnetoresistive film, and one surface of the magnetoresistive film. And a substrate provided on the side, wherein the short-circuit film is disposed between a connection layer made of a metal having good adhesion to the magneto-resistance effect film and an upper layer made of a metal having good conductivity. A magnetoelectric conversion element having a diffusion preventing layer for preventing diffusion of an upper metal layer. 3. The device according to claim 1, wherein the magnetoresistive films are connected in series and / or in parallel on one substrate, and the terminals are respectively connected between the magnetoresistive films. Item 3. The magnetoelectric conversion element according to Item 2. 4. A magnetoelectric conversion element according to claim 1, a magnet for applying a bias magnetic field to the magnetoelectric conversion element, and a case for housing the magnetoelectric conversion element and the magnet. And a magnetic sensor.