JPH06181348A - Magnetoelectric conversion element - Google Patents

Abstract

PURPOSE:To enable a magnetic conversion element to be protected against damage and continuously kept stable in characteristics when an operating electric power is abruptly applied by a method wherein a P/N junction is provided to one of a pair of N-type ohmic electrodes. CONSTITUTION:Zn ions are implanted into a P-type GaAs layer forming region 205, which is thermally treated (for instance, in an atmosphere contains arsine gas of prescribed partial pressure) to provide a P/N function to the input electrode 201-a out of a pair of N-type GaAs input electrodes 201-a and 201-b. Furthermore, in an N-type GaAs layer region which is formed into the input power sections 201-a and 201-b and an output power section 202, the N-type GaAs layer is exposed. For instance, Au-Ge alloy is vacuum-evaporated to come into ohmic contact with N-type GaAs for the formation of two pairs of four input electrodes 206-a, 206-b, and 207s. By this setup, a magnetoelectric conversion element of this design can be protected against damage and continuously kept high in characteristics when an operating power is abruptly applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoelectric conversion element using a III-V group compound semiconductor material, and particularly to a highly reliable III-V group compound magnetoelectric conversion element having high surge resistance.

[0002]

2. Description of the Related Art A Hall element is known as one of so-called magnetoelectric conversion elements that detect a magnetic field and convert it into an electric signal with its strength. Hall elements have conventionally been single semiconductors made of a single element such as silicon (Si) and germanium (Ge), and gallium arsenide (GaAs).
And indium phosphide (InP), which are elements of Group III and Group V of the periodic table,
It is a kind of sensor that is obtained by using a III-V group compound semiconductor and has a detected amount of a Hall voltage generated by the movement of electrons when a magnetic field is applied to these semiconductor materials. It has been widely used in various industrial fields such as the measurement of the rotational speed of a rotating body as well as the measurement of the magnetic field strength.

In addition to the Si simple substance semiconductor as described above, III-V group compound semiconductors such as InSb, InAs and GaAs are used for the Hall element. In the actual manufacture of the Hall element, for example, a bulk crystal made of InSb itself may be used as a magnetic sensing portion of the Hall element, but in many cases, it is formed by ion implantation on a high-resistance GaAs single crystal substrate or by GaAs single crystal. VPE, MOCV on the substrate
A GaAs layer formed by a vapor phase growth method such as D or MBE method or a liquid phase growth method is used as a magnetic sensing part. A conventional general method for manufacturing a hall element is to form an electrode having ohmic characteristics, which is an input / output electrode of an electric signal, on the layer which becomes the magnetically sensitive portion thus formed, Configure the element.

The ohmic electrode is an essential constituent element in the structure of the Hall element. As shown in FIG. 1, the normal Hall element is formed of a pair of input electrodes 101 and a pair of output electrodes 102 provided on the surface of the GaAs epitaxial growth layer which becomes the magnetic sensitive section 103. Generally, the high electron mobility of the semiconductor layer that becomes the magnetic sensing layer 103 determines the sensitivity characteristic of the Hall element, so that even if the same semiconductor material is used as the magnetic sensing section, an n-type conductivity type instead of a p-type conductivity type is used. The n-type semiconductor layer shown is used. For this reason, for such n-type conductors, gold-germanium alloys, which are likely to be ohmic electrodes, are mainly used as electrode materials.

In actually operating the Hall element, a voltage is appropriately applied to, for example, a pair of ohmic input electrodes made of the above-described gold-germanium alloy. However, in the ohmic electrode formed on the semiconductor magnetic sensitive layer which simply exhibits n-type conduction, a surge voltage exceeding an allowable value when an operating voltage is applied, or a sudden phenomenon that occurs during the operation of the device. However, even if an excessive operating voltage is applied, the function of the Hall element is destroyed. For this reason, in order to prevent the destruction of the Hall element due to such a surge-like input voltage, the electric circuit for driving the Hall element is equipped with an electric component such as a diode that absorbs the surge-like input. Incorporation of a circuit has been a general method that has been conventionally performed (see, for example, "Reliability countermeasures for latest car electronics and on-vehicle electronic devices" P.255-227, published by Technical Information Society of 1989).

[0006]

However, the conventional method as described above simply increases the number of components of the electric component and complicates the constitution on the electric circuit, and as a result, obstructs the miniaturization of the Hall element. Therefore, there is a problem in that the magnetic field measurement in a minute area and the two-dimensional magnetic field strength distribution measurement are hindered.

In view of the above-mentioned drawbacks, the present inventor does not need a special external circuit for protecting the element from the sudden input of the power source for operation, and is highly reliable and miniaturized for stable operation. In order to provide an easy magnetoelectric conversion element,

[0008]

Means for Solving the Problems The present inventor has studied a means for forming a pair of input electrodes that form ohmic contact with an n-type semiconductor layer that forms a magnetically sensitive portion, which is found in conventional Hall elements. As a result, in a Hall element made of a compound semiconductor, a p / n junction is provided on one of a pair of ohmic input electrodes to protect the element from the sudden input of operating power supply and to maintain stable characteristics. It is intended to provide a compound semiconductor Hall element having high reliability capable of exhibiting the above.

The p / n junction can be easily formed by, for example, joining the n-type semiconductor layer on which the input electrode is formed and interposing the p-type semiconductor. For example, GaAs, In
Hall elements using P, indium arsenide (InAs), indium antimonide (InSb), or other III-V group binary compounds or mixed crystal semiconductors thereof are listed in the periodic table of elements. Zinc (Z
It is possible to form a compound semiconductor layer having a p-type conductivity type in an n-type semiconductor region by performing so-called ion implantation in which an appropriate amount of n) or magnesium (Mg) ions are implanted, and then performing appropriate heat treatment. I can. On the other hand, a III-V group binary compound having an n-type conductivity or a mixed crystal semiconductor thereof is a silicon (Si) or germanium (Ge) belonging to Group IV of the periodic table of elements in the p-type semiconductor layer region. Alternatively, it can be easily obtained by ion-implanting an element such as sulfur (S) or selenium (Se) of Group VI. Also, the above p
The n-type or n-type compound semiconductor layer is not limited to the ion implantation method, but is also a vapor phase growth method such as metalorganic pyrolysis vapor phase epitaxy (MOCVD) method, molecular beam epitaxy (MBE) method, or liquid phase epitaxial method. Can also be formed by the growth method.

Even in the Hall element made of a single semiconductor such as Si or Ge, the p / n junction can be formed by the above method. However, in these Group VI semiconductors, unlike the above-mentioned III-V group compound semiconductors, elements belonging to Group III are used for forming the p-type layer, and phosphorus (P) is used for forming the n-type layer. , An arsenic (As) or other group V element is ion-implanted or doped (added) to obtain an epitaxial growth method.

Further, the present invention will be described by taking as an example the case where a Hall element made of GaAs is obtained by utilizing the ion implantation method. To obtain a Hall element made of GaAs as in the conventional case, a semi-insulating so-called high-resistance GaAs single crystal is used as a substrate. First, a region other than a region where elements are formed on the surface of the high-resistance GaAs substrate, that is, a region other than a region that serves as an input / output electrode portion and a magnetic sensitive portion is subjected to a general resist agent and oxidation according to a known photolithography method, etching method, or the like. Cover with a film of silicon (SiO ₂ ), silicon nitride (SiN), or the like. After that, S that becomes an n-type impurity for GaAs
Implant an appropriate amount of i ions. Next, the film material that covers the area other than the functional portion of the element is removed by etching. Thereafter, the GaAs crystal substrate into which Si ions are implanted is subjected to appropriate heat treatment to electrically activate the implanted Si ions to form a magnetic sensitive portion made of n-type GaAs, and a pair of input and output electrode portions. To form. Then S
i is ion-implanted into one of the pair of input electrode portions,
A p-type impurity such as Zn ions is implanted so as to form a / n junction. After that, appropriate heat treatment is performed again to electrically activate the implanted Zn ions to form a p / n junction. Finally, if electrodes are formed by depositing an electrode material, such as gold-germanium alloy, which causes ohmic contact with n-type GaAs on each pair of input / output electrode portions by vacuum deposition or the like, the The Hall element according to the invention can be obtained.

In the above example, the n-type impurity Si is first implanted, and the heat treatment for activation is performed, and then the Zn ions of the p-type impurity are implanted and the heat treatment is performed. The Hall element according to the present invention is not particularly limited to this procedure. Contrary to the above example, p-type impurities are implanted and heat-treated, and then n-type impurities are implanted and heat-treated. Is also good. Further, the Hall element according to the present invention can be obtained by a simplified process in which p-type and n-type impurities are first ion-implanted and then heat-treated at the same time, instead of performing heat-treatment each time each ion is implanted. .

As described above, GaAs is used as an example of the compound semiconductor.
, And Si as an example of a single semiconductor, the outline of the new Hall element according to the present invention is described.
Even if nP, InAs, InSb, or a mixed crystal thereof is used as a material, or a single semiconductor other than Si such as Ge, a new Hall element having the p / n junction according to the present invention is formed by the above-described method. It is possible to get.

[0014]

By providing the p / n junction described in the present invention to one of the pair of input electrodes, the p / n junction is provided.
The input of the operation / control voltage for operating the Hall element is not hindered, and the input of an operating voltage exceeding the permissible level can protect the element from functional breakdown.

[0015]

EXAMPLES Hereinafter, Hall elements according to the present invention will be described.
A detailed description will be given based on examples. (Example 1) Here, G, which is a III-V group binary compound, is used.
A hall element using aAs as a base material will be described as an example. First, a schematic plan view of a Hall element according to the present invention is shown in FIG. 2, and a sectional view thereof is shown in FIG. As described above, in the Hall element made of GaAs, chromium (C
A high resistance GaAs crystal having a semi-insulating property, which is formed by adding a transition metal such as r) or oxygen (O ₂ ) or is not added (undoped), is used as a substrate. In the present embodiment, a non-doped semi-insulating GaA having a specific resistance of about 10 ⁷ Ω · cm is added.
s single crystal was used as the substrate 204. Also the substrate
The plane orientation of 204 was within the range of (100) ± 0.5 degrees. However, the specific resistance value and the plane orientation of the substrate to be used are not limited to the above values, and for example, the specific resistance is 10
It may be about ⁶ Ω · cm, and the orientation of the plane may be an orientation inclined by about 2 degrees from the (100) plane.

Next, the above-mentioned GaAs single crystal substrate 204
GaA that exhibits an n-type conductivity type on the surface to be the magnetic sensing portion 203, the input electrode portion 201, and the output electrode portion 202
In order to form the s layer, the surface of the GaAs crystal 204 is entirely covered with a general photoresist material, and thereafter, a portion (201 to 201) corresponding to an element formation region portion is formed by making full use of a known photolithography method and etching method. The photoresist of 203) is selectively removed, and GaA is removed in the same area.
The surface of the s crystal 204 was exposed.

After that, the GaAs crystal 204 processed as described above is placed in a general ion implantation apparatus, and Si ions having a mass number of 28 or 29 are accelerated at an acceleration voltage of 200K.
An n-type GaAs injection layer was formed by selectively implanting into the device forming regions (202 to 204) under the conditions of V and a dose amount of 2 × 10 ¹² cm ^-2 . Next, after peeling off the photoresist material used as the masking material, the ion-implanted GaAs crystal 204 is heated at a temperature of 850 ° C. for 15 minutes in an atmosphere containing arsine (AsH ₃ ) gas at a predetermined partial pressure. Heat treated.

Next, a photoresist material is applied to the entire surface of the GaAs crystal 204 again to form a pair of n-type GaAs.
In order to form a p / n junction with the one 201-a of the input electrodes 201 made of p-type GaAs, a corresponding region 205 in which a p-type GaAs layer is to be formed is processed by a known photolithography method and etching method to form the p-type GaAs. The photoresist material in the area (205) was selectively removed. After that, Zn ions were implanted with an acceleration voltage of 100 KV and a dose of 8.0 × 10 ¹³ cm ^-2 . After stripping the photoresist material as described above, the GaAs crystal was subjected to the second heat treatment at a temperature of 650 ° C. for 20 minutes in an atmosphere containing a predetermined partial pressure of arsine gas.

Further, the surface of the GaAs crystal 204 implanted with Si and Zn ions is entirely covered with a general photoresist material to form an n-type GaAs layer region which becomes the input electrode portion 201 and the output electrode portion 202. Only the photoresist material covering the
01 and 202) were processed so that the n-type GaAs layer was exposed. After that, a gold-germanium (Au-Ge) alloy that causes ohmic contact with n-type GaAs is vacuum-deposited, and a total of four input electrodes 206 each forming a pair.
And an output electrode 207. Here, an Au-Ge alloy having a Ge content of 12% by weight was used as the n-type ohmic electrode material, but the Ge content in the Au-Ge alloy is not fixed to this, and Au is not fixed.
A material other than the Ge alloy may be used.

In the p-type GaAs implantation region 205, a p-type Ga made of heat-treated gold-zinc (Au-Zn) alloy is formed.
An ohmic input electrode 209 for As was provided. Next, as shown in FIG. 2, the wiring 208 made of Au is connected to Z
The p-type ohmic electrode 209 formed by n-ion implantation and the input electrode 206 were connected to the input electrode 206-b on the side where the p-type implantation layer 205 was not provided.

Comparative Example Further, in order to compare the effects of the present invention better, a conventional Hall element not including the p / n junction according to the present invention was prepared. The procedure is p-type GaA
The implantation of the s-implanted layer was not performed, and the other conditions were the same.

Table 1 shows the characteristics of the Hall element according to the present invention,
In particular, the anti-surge characteristics will be summarized in comparison with those of the conventional Hall element.

[0023]

[Table 1]

Regardless of the presence / absence of the p / n junction according to the present invention, no significant difference was observed in the characteristics of the input and output resistance values, the product sensitivity, the temperature dependence of the Hall voltage, and the unbalance rate of the Hall voltage. . On the other hand, as a result of investigating the surge resistance to the input voltage by the method of instantly applying a predetermined voltage to the input electrode, it was found that the Hall element having the p / n junction according to the present invention has a conventional Hall element without the same junction. Compared to the device, it showed significantly better surge resistance. As an example, p
In the conventional Hall element that does not include the / n junction, when the pulse voltage of 25 V is applied, 52
%, The number of samples caused the instability of the Hall output voltage, the deterioration of the uniformity of the input resistance value, etc., which are considered to be due to the destruction of the electrode part. In addition, when a pulse voltage of 35 V was input, 83% of the subjects had abnormal electrical characteristics. On the contrary, in the Hall element having the p / n junction according to the present invention on the input electrode side, even if the instantaneous input of the pulse voltage of 35 V is applied, there is some difference in the element characteristics among the total number of specimens 7500. None of them had any abnormalities.

In the embodiment according to the present invention, GaAs is used.
Although the hall element made of a semiconductor is taken as an example, the effect of the present invention can be exhibited even when a binary compound semiconductor such as InP, InAs, InSb, or a single semiconductor such as Si or Ge is used. Is clear.

[0026]

In the Hall element incorporating the p / n junction according to the present invention, it is obvious that the surge resistance is improved as described above, and a Hall element exhibiting a high reliability which has never been obtained is obtained. It has an effect to give. in addition,
By incorporating a function with surge resistance in the element, it is not necessary to provide an external electric circuit having a surge absorbing function as in the conventional case, and therefore the element itself can be downsized, and therefore, in a minute area. It is applied to the industrial field as a magnetic field sensor, rotation sensor, etc., and contributes to the development of the field of control engineering that requires high reliability and high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration example of a conventional Hall element.

FIG. 2 is a plan view showing an outline of a Hall element including a p / n junction according to the present invention.

FIG. 3 is a sectional structural view of the plan view of FIG. 2 taken along the line AA ′.

[Explanation of reference numerals] 101 ... Input electrode 102 ... Output electrode 103 ... Magnetism sensitive portion 104 ... Crystal substrate 201 ... Input electrode formation region 202 ... Output Electrode forming region 203 ... Magnetosensitive portion 204 ... Crystal substrate 205 ... P-type layer forming region 206 ... N-type input electrode 207 ... N-type output electrode 208. ... Au wiring 209 ... P-type input electrode

Claims (1)

[Claims] 1. A III-V compound semiconductor magnetoelectric conversion element, wherein the input electrode includes a p / n junction.