JP3221114B2 - Magnetoelectric conversion element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A Hall element is known as one type of a so-called magnetoelectric conversion element which detects a magnetic field and converts it into an electric signal with its strength. Conventionally, a Hall element is a single semiconductor made of a single element such as silicon (Si) or germanium (Ge), or gallium arsenide (GaAs).
Consisting of elements belonging to Groups III and V of the periodic table of the elements, such as and indium phosphide (InP).
It is a type of sensor obtained by using a III-V compound semiconductor and using a Hall (Hall) voltage generated by the movement of electrons generated when a magnetic field is applied to these semiconductor materials as a detected amount, 2. Description of the Related Art Conventionally, it is widely used in various industrial fields, such as measurement of the number of revolutions of a rotating body, as well as measurement of magnetic field strength.

[0003] As described above, a III-V group compound semiconductor such as InSb, InAs, or GaAs is used for the Hall element in addition to the Si elemental semiconductor as described above. In actual manufacture of a Hall element, for example, a bulk crystal of InSb itself may be used as a magnetic sensing part of the Hall element. However, in most cases, a high-resistance GaAs single crystal substrate is ion-implanted or a GaAs single crystal. VPE, MOCV on substrate
A GaAs layer formed by a vapor phase growth method such as a 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 as input / output electrodes for an electric signal on a layer serving as a magnetic sensing portion formed in this way, and to form a hole. Configure the element.

The above-mentioned ohmic electrode is an essential component in the structure of the Hall element. Normally, as shown in FIG. 1, a Hall element is formed from a pair of input electrodes 101 and a pair of output electrodes 102 provided on the surface of a GaAs epitaxial growth layer that will be the magnetically sensitive portion 103. In general, the high electron mobility of the semiconductor layer serving as the magnetosensitive layer 103 determines the sensitivity characteristics of the Hall element. The n-type semiconductor layer shown is used. For this reason, for such an n-type conductor, an ohmic electrode, for example, a gold-germanium alloy, is easily used as an electrode material.

In actually operating the Hall element, a voltage is appropriately applied to a pair of ohmic input electrodes made of, for example, the above-mentioned gold-germanium alloy. However, in the case of an ohmic electrode formed on a semiconductor magneto-sensitive layer simply showing n-type conduction, a surge voltage exceeding an allowable value when an operating voltage is applied, or a sudden occurrence occurring during the operation of the element. There is a problem that the function of the Hall element is destroyed even by applying an excessively high operating voltage. Therefore, in order to protect the Hall element from destruction due to such a surge-input voltage, an electrical component such as a diode for absorbing a surge-like input is provided in an electric circuit for driving the Hall element. Incorporating a circuit has been a general method that has been conventionally performed (for example, see “Reliability Measures for Latest Car Electronics and In-Vehicle Electronic Devices”, pp. 255-227, published by Technical Information Association, 1989).

[0006]

However, the conventional methods as described above simply increase the number of electrical components and complicate the configuration on the electrical circuit, and consequently hinder miniaturization of the Hall element. This has the disadvantage that the measurement of the magnetic field in a minute area and the measurement of the two-dimensional distribution of the magnetic field strength are hindered.

In view of the above drawbacks, the present invention does not require a special external circuit for protecting the element from sudden input of a power supply for operation, and achieves high reliability and downsizing that provides stable operation. It has been made for the purpose of providing easy magnetoelectric transducer.

[0008]

Means for Solving the Problems The present inventor has studied the means for forming a pair of input electrodes forming an ohmic contact with the n-type semiconductor layer forming the magnetically sensitive portion as seen in a conventional Hall element. As a result, by providing a p / n junction at one of a pair of ohmic input electrodes in a Hall element made of a compound semiconductor, the element is protected from a sudden input of an operation power supply, and a stable characteristic is continuously provided. It is intended to provide a compound semiconductor Hall element having high reliability capable of exhibiting the following.

The p / n junction can be easily formed, for example, by bonding the p / n junction to an n-type semiconductor layer on which an input electrode is formed and interposing a p-type semiconductor. For example, GaAs, In
P, a Hall element using a III-V group binary compound such as indium arsenide (InAs) or indium antimonide (InSb), or a mixed crystal semiconductor thereof,
A proper amount of ions of zinc (Zn) or magnesium (Mg), which is a Group II element listed in the periodic table of the elements, is implanted, and then an appropriate heat treatment is applied to the n-type semiconductor region. A compound semiconductor layer having a p-type conductivity can be formed. On the other hand, a group III-V binary compound exhibiting an n-type conduction type or a mixed crystal semiconductor thereof is contained in the p-type semiconductor layer region in the element I of the periodic table.
Silicon (Si) and germanium (G
e) or Group VI sulfur (S) or selenium (Se)
Such an element can be easily obtained by ion implantation.
In addition, the above-mentioned p-type or n-type compound semiconductor is not limited to the ion implantation method but may be a metal organic chemical vapor deposition (MOCV) method.
D) method, a molecular beam Epita key Interstitial method (MBE) method, or the like vapor deposition, or also can be formed by a deposition method such as liquid phase epitaxial method.

A p / n junction can be formed by the above-described method even in a Hall element made of a simple semiconductor such as Si or Ge. However, these group VI semiconductors are different from the above group III-V compound semiconductors in that elements belonging to group III are formed for forming the p-type layer and phosphorus (P) is formed for forming the n-type layer. , Arsenic (As), etc., by ion implantation or doping (addition) by epitaxial growth.

Further, the present invention will be described with reference to an example in which a Hall element made of GaAs is obtained by using an ion implantation method. In order to obtain a GaAs Hall element as in the prior art, a so-called semi-insulating so-called high-resistance GaAs single crystal is used as a substrate. First, areas other than the element forming area on the surface of the high-resistance GaAs substrate, that is, the areas other than the areas serving as the input / output electrode section and the magnetic sensing section, are exposed to a general resist material, oxidation method, or the like according to a known photolithography method, etching method, or the like. It is covered with a film such as silicon (SiO ₂ ) or silicon nitride (SiN). Thereafter, S, which becomes an n-type impurity for GaAs,
An appropriate amount of i-ion is injected. Next, the film material covering the region other than the region that becomes the functional portion of the element is removed by etching. Thereafter, a suitable heat treatment is applied to the GaAs crystal substrate into which the Si ions have been implanted, and the implanted Si ions are electrically activated to make the magneto-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 a pair of input electrode portions,
A p-type impurity such as, for example, Zn ions is implanted to form a / n junction. Thereafter, an appropriate heat treatment is performed again to electrically activate the implanted Zn ions to form ap / n junction. Eventually, an electrode is formed by forming a pair of input / output electrode portions by applying an electrode material that provides ohmic contact to n-type GaAs, such as a gold-germanium alloy, by a vacuum deposition method or the like. A Hall element according to the invention is obtained.

In the above example, the process procedure is such that the n-type impurity Si is first implanted, heat treatment for activation is performed, and then the p-type impurity Zn ion is implanted and heat-treated. The Hall element according to the present invention is not particularly limited to this procedure. Conversely to the above example, a p-type impurity is implanted and heat treatment is performed, and then an n-type impurity is implanted and heat treatment is performed. Is also good. In addition, 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 treatment is performed simultaneously, instead of performing heat treatment each time each ion is implanted. .

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

[0014]

The p / n junction according to the present invention is provided by providing a p / n junction to one of the pair of input electrodes.
The input of the operation / control voltage for operating the Hall element does not interfere at all, and the action of protecting the element from functional destruction is obtained with respect to the input of the operating voltage exceeding the allowable level.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a Hall element according to the present invention will be described.
This will be described in detail based on an embodiment. (Example 1) Here, G which is a group III-V binary compound is used.
A description will be given by taking a Hall element using aAs as a base material as an example. First, FIG. 2 shows a schematic plan view of a Hall element according to the present invention, and FIG. 3 shows a cross-sectional view thereof. As described above, in a Hall element made of GaAs, chromium (C
A high resistance GaAs crystal having a semi-insulating property, to which a transition metal such as r) or oxygen (O ₂ ) is added or not added (undoped) is used. In this embodiment, undoped semi-insulating GaAs having a specific resistance of about 10 ⁷ Ω · cm
An s single crystal was used as the substrate 204. Also, the substrate
The plane orientation of 204 was in the range of (100) ± 0.5 degrees. However, neither the specific resistance value nor the plane orientation of the substrate to be used is limited to the above values.
It may be about ⁶ Ω · cm, and the plane direction may be a direction inclined about 2 degrees from the (100) plane.

Next, the above-mentioned GaAs single crystal substrate 204
GaAs having n-type conduction type on the surface to be the magnetic sensing part 203, the input electrode part 201, and the output electrode part 202
In order to form an s layer, the surface of the GaAs crystal 204 is covered with a general photoresist material over the entire surface, and thereafter, by using a well-known photolithography method and an etching method, portions (201 to 201) corresponding to the element formation region portion are formed. 203) The photoresist is selectively removed, and GaAs is formed in the same region.
The surface of the s crystal 204 was exposed.

Thereafter, 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 charged at an accelerating voltage of 200K.
V and a dose of 2 × 10 ¹² cm ⁻² were selectively implanted into the element formation regions (202 to 204) to form an n-type GaAs implanted layer. Next, after the photoresist material used as the masking material is removed, the ion-implanted GaAs crystal 204 is removed at a temperature of 850 ° C. for 15 minutes in an atmosphere containing a prescribed partial pressure of arsine (AsH ₃ ) gas. Heat treated.

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

Further, the entire surface of the GaAs crystal 204 into which the Si and Zn ions have been implanted is covered with a general photoresist material, and the region of the n-type GaAs layer which becomes the input electrode portion 201 and the output electrode portion 202 is formed. Only the photoresist material covering the area is peeled off and the same area (2
01 and 202), processing was performed such that the n-type GaAs layer was exposed. Thereafter, a gold-germanium (Au-Ge) alloy providing ohmic contact with the n-type GaAs is vacuum-deposited, and a pair of the four input electrodes 206 is formed.
And the 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. However, the Ge content in the Au-Ge alloy is not fixed thereto, and the Au content is not fixed.
-A substance other than the Ge alloy may be used.

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

Comparative Example In order to better compare the effects of the present invention, a conventional Hall element according to the present invention, which does not include a p / n junction, was prepared. The procedure is p-type GaAs
The injection of the s injection layer was not performed, and all others were the same.

Table 1 shows the characteristics of the Hall element according to the present invention,
In particular, the surge resistance is summarized in comparison with that of the conventional Hall element.

[0023]

[Table 1]

Regardless of the presence or absence of the p / n junction according to the present invention, no remarkable difference was observed in the characteristics of the input and output resistance values, the product sensitivity, the temperature dependency of the Hall voltage, and the unbalance rate of the Hall voltage. . On the other hand, as a result of investigating surge resistance against an input voltage by a method of instantaneously applying a predetermined voltage to an input electrode, a Hall element having a p / n junction according to the present invention has a conventional hole element having no p / n junction. The surge resistance was much better than that of the device. As an example, p
In a conventional Hall element that does not include the / n junction, a total of 8200 specimens of 52
% Of samples caused instability of the Hall output voltage, deterioration of the uniformity of the input resistance value, and the like, which are considered to be due to the destruction of the electrode portion. In addition, when a pulse voltage of 35 V was input, as many as 83% of the subjects had abnormalities in some electrical characteristics. Contrary to this, in the Hall element having the p / n junction on the input electrode side according to the present invention, even if an instantaneous input of a pulse voltage of 35 V is performed, some of the characteristics of the element out of the total number of subjects are 7,500. None of them had any abnormalities.

In the embodiment according to the present invention, GaAs is used.
Although the Hall element using a semiconductor as a material has been described as an example, the effect of the present invention can be exerted even when a binary compound semiconductor such as InP, InAs, and InSb, and a single semiconductor such as Si and Ge are used. Is clear.

[0026]

As described above, in the Hall element incorporating the p / n junction according to the present invention, it is clear that the surge resistance is improved as described above. It has the effect of giving. in addition,
By incorporating a function having surge resistance into the element, it is not necessary to provide an external electric circuit having a surge absorbing function as in the conventional case, so that the element itself can be downsized. It is applied to the industrial field as a magnetic field sensor, a rotation sensor, and the like in the field, and greatly contributes to the development of control engineering fields and the like that require high reliability and high accuracy.

[Brief description of the drawings]

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

FIG. 2 is a plan view schematically showing a Hall element having a built-in p / n junction according to the present invention.

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

[Explanation of symbols]

 101, an input electrode 102, an output electrode 103, a magnetic sensing part 104, a crystal substrate 201, an input electrode formation area 202, an output electrode formation area 203 ... Magnetic sensing part 204... Crystal substrate 205... P-type layer formation region 206... N-type input electrode 207... N-type output electrode 208. 209 ··· p-type input electrode

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-27075 (JP, A) JP-A-63-151090 (JP, A) JP-A-56-96886 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 43/06 G01R 33/07 G11B 5/37

Claims (1)

(57) [Claims] 1. A magnetic sensing part comprising an n-type GaAs layer formed on a surface of a semi-insulating GaAs substrate, and a pair of input and output electrode parts, and surfaces of the input and output electrode parts. A Hall element having a pair of input electrodes and a pair of output electrodes formed so as to make ohmic contact with each other.
A p-type GaAs layer is formed by forming a pn junction with the p-type GaAs layer; a p-type ohmic electrode is formed on the surface of the p-type GaAs layer; and a p-type ohmic electrode is formed on the other of the input electrode portion and the other side. Characterized in that the input element is electrically connected to the input electrode by a wiring.