JPS61234084A - Magnetoresistance element - Google Patents

Abstract

PURPOSE:To improve the sensitivity of an element by devising the disposition and the shape of a short piece for a long piece in which main magnetoresistance variation occurs thereby cancelling the resistance variation in the short piece relatively by itself. CONSTITUTION:Angles A-D between long and short pieces are all set to 135 deg., and short pieces 14, 15 are bent at the intermediate at 90 deg.. Accordingly, when the direction of a magnetic field B with respect to the long piece forms theta, 14-1 of the half of the piece 14 forms an angle of theta+45 deg., and 14-2 of the other half forms an angle of theta+135 deg.. The magnetoresistance change of the short piece itself is cancelled by both side portions 14-1 and 14-2 bent at 90 deg..

Description

[Detailed Description of the Invention] A.6 Purpose of the Invention E.1. INDUSTRIAL APPLICATION FIELD This invention relates to a magnetoresistive element that utilizes the anisotropic magnetoresistive effect of a ferromagnetic material.

E2. Conventional magnetoresistive elements are produced by depositing a thin film of ferromagnetic material on a flat insulating substrate by vacuum evaporation or sputtering, forming a resistor pattern by photolithography and etching, and then forming a resistor pattern. The electrodes were formed in the same manner as the electrodes were formed. Since the electrical resistance of this magnetoresistive element changes depending on the direction of the magnetic field applied to the element, it is used to measure physical quantities such as the rotation and movement of a magnet.

The ferromagnetic resistance effect is produced by using a ferromagnetic thin film (with a fourth
As shown in the figure, a current (1) is applied, and a large magnetic field (B) that sufficiently saturates the magnetoresistive effect is applied in the plane of the thin film to the current (i).
This is a phenomenon in which the resistance value R of a ferromagnetic material changes according to θ when the angle θ is applied to the ferromagnetic material. When the resistance value when the angle θ is 45 is Ro, and the resistance change caused by the rotation of the magnetic field is ΔR, the resistance R is expressed by the following equation (1).

R=Ro +'AΔRcos 2θ −−・−(1) Magnetic field CB) direction, that is, this relationship between angle θ and resistance R is the fifth
As shown in the figure, the current (i) is a waveform that repeats every 180
Even if the direction of the magnetic field (B) is reversed, the resistance value R remains the same.

In order to increase the resistance value of the element, a practical magnetoresistive element has a zigzag-like (folded) resistance structure consisting of a large number of long pieces arranged in parallel and a number of short pieces that connect these long pieces in series. It forms a body pattern, and is published in Japanese Patent Application Laid-Open No. 50-2898.
9 and Japanese Unexamined Patent Publication No. 148577/1983. A part of this zigzag resistor pattern is shown in FIG. 6, where the long piece (2) and the short piece (3+ (4)) are arranged at right angles, and the short pieces (3) and (4) are parallel. The value is R
When an element is formed by connecting n long pieces (2) and short pieces (3) with a resistance value r, the total resistance value of the element is n
(R+r).

The resistance value R of the long piece is R=Ro+%ΔRcos 2θ, and the resistance value r of the short piece is r=ro+%Δrcos2(θ+90), so R+r=Ro +r, +'A (ΔR−Δr)co
s2θ...(2) The rate of change in magnetoresistance of this element is (ΔR-Δr
) / (Ro + r, ), which is smaller than the rate of magnetoresistance change ΔR/R of the material itself shown in FIG.

The reason for the decrease is that the short pieces are arranged at right angles to the long pieces, so that the resistance value of the short pieces changes in a direction that reduces the resistance change of the long pieces, depending on the direction θ of the magnetic field.

In the above conventional technology, the long piece and the short piece are at right angles, but US Pat.
No. 405,355 discloses a magnetoresistive element in which a long piece and short pieces arranged at an angle of 45 or 135 degrees form a zigzag resistor pattern. Since all the short pieces of this material are parallel, the change in resistance of the short pieces cancels out the change in resistance of the long pieces, making the sensitivity smaller than the sensitivity of the material itself.

E31 Problems to be Solved by the Present Invention As described above, in the prior art, the resistance change of the short pieces constituting the resistor pattern acts to reduce the resistance change of the long pieces, and moreover, all the short pieces Since they are parallel, the effects of reduction are added, and all of them work in a negative direction.

Therefore, there was a drawback that the sensitivity of the element was reduced.

The purpose of this invention is to reduce the drawbacks of the prior art by devising the arrangement and shape of the short piece relative to the long piece that causes the main magnetic resistance change so that the short piece itself cancels out the resistance change caused by the short piece. be.

The magnetoresistive element of the present invention has a zigzag structure formed by a plurality of long pieces arranged in parallel and a plurality of short pieces connecting the long pieces in series. The angle between the long piece and the short piece of the shaped resistor pattern is set to either '-'45''7 or -135,
It is characterized in that one short piece is bent into a beam 90 in the middle.

Rho 20 action When the direction of the magnetic field, that is, the angle θ changes, the resistance value of each long piece of the resistor pattern changes accordingly, but since the short pieces are bent at right angles in the middle, both sides of the bending point Changes in the resistance value of each part cancel each other out and do not appear as changes in the resistance value of the element. Therefore, the resistance value of the magnetoresistive element that changes depending on the direction θ of the magnetic field is only the change due to the long piece.

Row 3. Example In the example shown in FIG. 1, (5) is an insulating substrate, (6)
is a resistor pattern, and (7) is another resistor pattern having a long piece arranged at right angles to the long piece constituting the resistor pattern (6), which is electrically connected in series with the resistor pattern (6). ing. (8), (9), αω is an electrode.

The resistor pattern consists of a plurality of long pieces (11) arranged in parallel.
, (12), (13), ... and multiple short pieces (14), (15), (16)
, . . . are connected in series as shown in the figure, and the whole is formed in a zigzag shape.

The angles A, B, C, and D between the long piece and the short piece are all 135°.
The short pieces (14) and (15) are 90 mm in the middle.
'It's bent. Therefore, when the direction of the magnetic field B with respect to the long piece forms an angle θ, the direction of the magnetic field B with respect to the long piece is half that of the short piece (14).
-1) forms an angle θ+45' (7) with the magnetic field, and the other half (14-2) forms an angle θ+135°.

The resistance value R of the long piece (11) is R-RO+'AΔRcos 2θ The resistance value rμ of the short piece (14-1) is half that of the short piece (14) 1='A r, +WΔrcos 2 (θ+45)
The resistance value t of the other half (14-1) is r, = l r, + %Δrcos 2 (θ+
135). However, 〃r6 is the resistance value when half (14-1) (14-2) of the short piece (14) forms a 45' (7) angle with the magnetic field, and 〃ΔR is the resistance value when the short piece (14) when the magnetic field rotates.
The resistance change is half (14-1) (14-2) of 14).

The sum of the resistances of the long piece (11) and the short piece (14) is R+r,
+ r, -Ro + rt, +'/, ΔRcos 2
θ-...(3), and the magnetic resistance change of the short piece itself is 90
It is canceled out by the bent side parts (14-1) and (14-2), and the rate of change in magnetoresistance of the sum of resistances R+r, +r is ΔR/ (Ro +r,,), which is different from the conventional technology. It is larger than (ΔR - Δr) / (Ro + rD) in FIG.

Normally, the rate of change in magnetoresistance ΔR/Ro of the material itself is about 5%, but in the prior art shown in FIG.
:l, the rate of change in magnetoresistance is (ΔR−Δr)
/ (R+ r,) = 0.0409 or 4.09%
becomes. On the other hand, in the case of the example, assuming that the resistor pattern is formed on the same substrate size, the ratio of R and r+r is 9.
: 1.414, so the rate of change in magnetoresistance as an element is ΔR/ (Ro + r,) = 0.05X9
/ (9+1.414)=0.0432, that is, 4.32%, which is 0.23% larger than the conventional element.

In the above embodiment, the angle between the long piece and the short piece is 135'.
However, the same effect can be obtained even if it is 45 as shown in FIG.

C0 Effects of the Invention Since there is no reduction in the sensitivity of the element due to changes in the magnetic resistance of the short pieces of the resistor pattern itself, there is an effect that the sensitivity of the element is improved accordingly.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, with the insulating coating on the surface omitted. FIG. 2 is a diagram showing the resistor pattern (
6), Figure 3 is a diagram showing the angular relationship between the resistor pattern in Figure 2 and the magnetic field, Figure 4 is an oblique view explaining the magnetoresistive effect, and Figure 5 is Figure 4. Figure 6 is a partially enlarged plan view of a conventional resistor pattern, and Figure 7 is a part of a resistor pattern of another embodiment. FIG.

Claims (1)

[Claims] The angle between the long pieces and the short pieces of a zigzag resistor pattern formed by a plurality of long pieces arranged in parallel and a plurality of short pieces connecting the long pieces in series is approximately 45° or 135°. one short piece is approximately 90° in the middle.
A magnetoresistive element characterized by being bent.