JPS6353713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly sensitive magnetoresistive element having four terminals.

Conventionally, magnetoresistive elements have been formed and used in the form of two terminals or three terminals. The shape of this conventional magnetoresistive element is shown in FIGS. 1, 2, and 3.

Figure 1 shows a simple two-terminal device with ohmic electrodes at both ends of the semiconductor thin film that produces the magnetoresistive effect.
2 and 13 are formed, and between these electrodes 12 and 13, short bars 14 made of ohmic electrodes extending in the width direction are arranged on the semiconductor thin film 11, and the short bars 14 serve to enhance the magnetoresistive effect of the semiconductor thin film 11. . Electrodes 12 and 13 are for external connection.

In FIG. 2, a terminal electrode 15 for external connection made of an ohmic electrode is formed between the terminal electrodes 12 and 13 of the magnetoresistive element shown in FIG. This element is a three-terminal element, and by applying magnetic fields of different values between electrodes 12 and 15 and between electrodes 13 and 15, a differential output can be obtained from electrodes 15.

FIG. 3 shows an element in which the short bar 14 between the terminal electrodes 13 and 15 in FIG. 2 is omitted. In this case, the magnetoresistive effect between the electrodes 12 and 15 is large, whereas the magnetoresistive effect between the electrodes 13 and 15 is small. Therefore, if a uniform magnetic field is applied to the entire element, a differential output can be obtained from the electrodes 15.

The problem with these conventionally used types of magnetoresistive elements is that a large change in resistance value cannot be obtained unless a strong magnetic field is applied, and therefore the output when actually used is small. In the case shown in Fig. 3, the output is not zero even when the magnetic field is zero, and a so-called offset voltage essentially exists.
The problem is that only the differential output cannot be directly extracted from the elements.

It is an object of the present invention to provide a magnetoresistive element which eliminates the drawbacks of the conventional element, has an output twice that of the conventional element, and provides a differential output that can be used with zero offset voltage.

The magnetoresistive element of the present invention has a semiconductor thin film having a magnetoresistive effect formed in a loop shape, and first, second, and third electrodes for external connection consisting of four ohmic electrodes spaced apart on the semiconductor thin film. , a fourth terminal electrode is arranged, shot bars made of ohmic electrodes are formed on each of the semiconductor thin films between the first and second terminal electrodes and between the third and fourth terminal electrodes, and the second and third terminal electrodes The structure is such that no short bar is formed between the fourth terminal electrode and between the fourth and first terminal electrodes.

For example, as shown in FIG. 4, a semiconductor thin film 11 having a magnetoresistive effect is formed in a rectangular loop shape,
Terminal electrodes 16, 17, 18, and 19 are formed on the semiconductor thin film 11 at each corner of the rectangle. Short bars 14 are formed on each semiconductor thin film 11 between electrodes 16 and 17 and between electrodes 18 and 19, respectively. No short bars are formed between the electrodes 17 and 18 and between the electrodes 19 and 16.

In the magnetoresistive element shown in FIG. 4, when a constant voltage is input between terminal electrodes 17 and 19 and a uniform magnetic field is applied to the entire element, each resistance between electrodes 17 and 18 and between electrodes 18 and 19 is The difference between the potential change of the electrode 18 due to the value change and the potential change of the electrode 16 is also taken out between 16 and 18. Moreover, by giving a resistance value between each electrode so that the potential difference between the electrodes 16 and 18 is zero when the magnetic field is zero, only the differential voltage output due to the magnetoresistive effect is generated between the electrodes 16 and 18. It can be taken out.
Also, since this element has a bridge structure, changes between electrodes 17, 18, and 19 and changes in electrode 1
In order to extract the changes between 7, 16, and 19 differentially, a conventional magnetoresistive element, for example, the third
A differential output twice as large as that shown in the figure can be obtained. Moreover, unlike the device shown in FIG. 2, differential output can be obtained by applying a uniform magnetic field to the entire device, so the effect is not lost even if the device is made small.

In a preferred case of the magnetoresistive element of the present invention, when no magnetic field is applied, the electrodes 16,
17 and between electrodes 17 and 18, and between electrodes 18 and 19 and between electrodes 19 and 16.
There is an element that has the same resistance value between the two. In this case, when no magnetic field is applied, the potentials of the electrodes 16 and 18 are equal, and when a magnetic field is applied, only a differential output is generated between the electrodes 16 and 18 due to the magnetoresistive effect.

Moreover, as a more preferable case, there is an element in which all the resistance values between adjacent electrodes are the same. In this case, all the electrodes have a completely symmetrical relationship, with electrodes 17 and 19 serving as input and electrodes 16 and 18 serving as output electrodes, and electrodes 16 and 18 serving as input and electrodes 17 and 19 serving as output electrodes. good.

The basic pattern of the semiconductor thin film 11 in the device of this invention is shown in FIG. 4, but it goes without saying that any modification that does not change the basic structure of this pattern also belongs to this invention.
This does not change depending on the material constituting the element or other requirements. Therefore, in order to manufacture a practical device, the length of the path between adjacent electrodes, the width of the shoot bars 14, the spacing between the shoot bars 14, the width of the semiconductor thin film 11, and the terminal electrodes 16 for external connection are determined.
It goes without saying that the size of 19 can be changed freely, and the resistance value between each electrode can also be freely selected in the design. Examples of various patterns of the semiconductor thin film 11 are shown in FIGS. 5A to 5F. Furthermore, the present invention is not limited to the substrate on which the element is mounted, and the underlying insulating substrate and the semiconductor thin film of the magnetically sensitive part may be formed integrally or may be formed separately. You can.

Next, the semiconductor thin film 1 of the magnetoresistive element of this invention
1. In other words, compound semiconductors are used as the material constituting the magnetically sensitive part, especially InSb, In _x Ga _y Sb _z (x+
y+z=2), GaAs, InAs, InP, etc. are preferable,
Furthermore, the higher the mobility of these materials, the more preferable.
The shot bar 14 is the magnetically sensitive part semiconductor thin film 11.
It is made of metal that makes ohmic contact. The short bar 14 may be constructed of one type of metal, an alloy, or two or three layers of metal, or any suitable combination thereof may be used.

The terminal electrodes 16 to 19 for external connection are made of metal that makes ohmic contact with the magnetically sensitive semiconductor thin film 11, and may of course have the same structure as the shot bar 14. However, the terminal electrodes may be further modified to connect lead wires that are normally used when attaching leads to devices. For this purpose, a metal layer to which solder easily adheres is usually attached to the surface, or a wire bonded metal layer is formed on the surface. Although not shown in the figure, after external lead wires such as lead wires are attached to the terminal electrodes of 47, resin molding is performed as a package normally used for semiconductor devices for protection, or metal packaging is used. It is done.

Next, a method of manufacturing the device of the present invention will be explained using Examples, but the present invention is not limited to these Examples.

Example 1 A 1 nSb thin film having a thickness of 1 μm and an electron mobility of 25000 cm ² /vsec was formed by vacuum evaporation on a mica substrate with a smooth surface. Next, on the surface of this InSb thin film,
Epoxy resin manufactured by Nippon Pernox Co., Ltd., ME-264
was applied onto a square Ni-Zn ferrite substrate with a thickness of 0.3 mm and a side of 37 mm. Then, mica was removed.

Next, Kodatsu Microphotoresist
752 in the usual way, InSb
A photoresist coating was formed on the surface of the thin film. Next, using Muromachi Kagaku's electroless plating liquid MK-400, electroless plating was performed for 30 minutes at a liquid temperature of 28℃ to deposit copper only on the required part with a thickness of 1.0μ, forming the metal layer for the ohmic contact electrode. was formed.

Next, in order to change the electroless plating solution and further thicken the copper, we used an electroless plating solution from one company.
Using CP-802, plating was performed for 30 minutes at a liquid temperature of 50°C, and an additional 2.0μ of copper was deposited. After completing the two-stage pattern plating process in this manner, the photoresist for plating was removed using trichloride.

Next, using the above photoresist again, unnecessary InSb and
A part of the unnecessary copper was removed by etching with a hydrochloric-acidic aqueous solution of ferric chloride to form the magnetically sensitive semiconductor thin film 11 and four terminal electrodes 16 to 19 of the device of the invention shown in FIG. Thereafter, using the photoresist described above, a resist film was formed on the other parts by photolithography, leaving only the electrodes 16 to 19 of the device of the present invention, and then the electrodes were placed in a molten solder bath. 16
I soldered only ~19. Then, the resist was removed, and about 300 elements were formed on a ferrite wafer having a side of 34 mm.

Next, this wafer was cut into square element chips measuring 1.8 mm x 1.7 mm using a dicing cutter.
Solder the four lead wires to each one,
The magnetoresistive element of the present invention was placed in an epoxy resin box with a size of 2.4 mm x 2.8 mm and a height of 1.5 mm, and molded with ME-264, an epoxy resin for molding made by Nippon Vernox Co., Ltd., as shown in Fig. 4. was produced.

The characteristics of the inventive device thus manufactured were as follows.

The resistance value between each adjacent electrode is 500±5Ω,
When a voltage of 1V is applied between electrodes 17 and 19,
The offset potential difference generated between electrodes 16 and 18 is
The value was 0.5±4.1 mV, which was substantially close to zero. When a 3K.G magnetic field is applied to the entire element,
The potential difference (output voltage) between electrodes 16 and 18 is ±
It became 6mV. Moreover, the deviation from the midpoint potential of each electrode 16 and electrode 18 is 500 mV.
It was half of the potential difference between 8 and 8. As described above, in the device of this invention, the output when a magnetic field is applied is twice that of the conventional device (for example, the one in FIG. 3), and the substantial offset voltage, that is, the output between the electrodes 16 and 18 when no magnetic field is applied, The potential difference between is extremely small. Therefore, it is a magnetoresistive element that is extremely useful in practice.

Example 2 A 1 μm thick SiO ₂ thin film layer was formed by sputtering on a 2 inch square ceramic substrate with a smooth surface. Next, the thickness is 1.0μm, the electron mobility is 22000
An InSb thin film of cm ² /vsec was formed by vacuum evaporation.
Next, a magnetoresistive element of the present invention was fabricated using the same method as that applied to the InSb thin film adhered to the ferrite substrate in Example 1. However, in this case, approximately 400 elements were formed on a 37 mm square ferrite wafer. The characteristics of the device of the present invention thus manufactured were as follows.

The mutual resistance value between each electrode is 560±5Ω, and when a voltage of 1V is applied between electrodes 17 and 19, the offset potential difference generated between electrodes 16 and 18 is 0.8
The value was ±3.5mV, which was almost zero.

When a 3K.G magnetic field is applied to the entire element, the potential difference (output voltage) generated between electrodes 16 and 18 is ±
It was 6.5mV. Moreover, the deviation from the midpoint potential of each electrode 16 and electrode 18 from 500 mV is determined by the difference between the electrodes 16 and 18.
It was exactly half of the potential difference of 18. As described above, in the device of the present invention, the output voltage when a magnetic field is applied, that is, the potential difference between the electrodes 16 and 18, is twice that of the conventional device shown in FIG. Also, the actual offset voltage is small as described above. Therefore, it is a highly useful magnetoresistive element in practice.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a pattern of a conventional two-terminal magnetoresistive element, FIGS. 2 and 3 are diagrams each showing an example of a pattern of a conventional three-terminal magnetoresistive element,
FIG. 4 is a diagram showing an example of a pattern of a magnetoresistive element according to the present invention, and FIG. 5 is a diagram showing examples of various modified patterns of the element of this invention. 11: Semiconductor thin film with magnetoresistive effect, 1
4: shot bar, 16-19: terminal electrode.

Claims (1)

[Scope of Claims] 1. A semiconductor thin film having a magnetoresistive effect formed in a loop shape, and first, second, and third electrodes for external connection formed at intervals on the semiconductor thin film and consisting of ohmic electrodes. and a fourth terminal electrode, and a shot bar formed on the semiconductor thin film between the first and second terminal electrodes and between the third and fourth terminal electrodes and consisting of an ohmic electrode;
A four-terminal magnetoresistive element in which no shot bar is formed on the semiconductor thin film between the terminal electrodes and between the first and fourth terminal electrodes. 2. Each resistance value between the first and second terminal electrodes is equal to that between the first and fourth terminal electrodes, and the third,
Claim 1, wherein the resistance values between the fourth terminal electrode and between the third and second terminal electrodes are equal.
Magnetoresistive element as described in section. 3. The magnetoresistive element according to claim 1 or 2, wherein the resistance values between the terminal electrodes that are in phase with each other are all equal.