JPH11204855A - Method of forming indium antimony type crystal film, indium antimony type semiconductor element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise an input/output impedance and enhance magnetic collection effect by growing an InSb-contg. III-V compd. semiconductor crystal film on a semiconductor substrate, adhering other substrate to the opposite side of the semiconductor substrate to the semiconductor crystal film, and removing the semiconductor substrate. SOLUTION: An InSb-contg. III-V compd. semiconductor crystal film 2 is formed on a GaAs semiconductor substrate 1, an epoxy adhesive 3 is coated on the opposite side of the semiconductor substrate 1 to the semiconductor crystal film 2, a magnetic ferrite substrate 4 is adhered to the epoxy adhesive 3, the GaAs semiconductor substrate 1 is mechanically polished down to specified thickness, and a nitric acid-hydrogen peroxide-based etching liq. for etching GaAs is applied to act on the semiconductor substrate 1 to perfectly remove the GaAs semiconductor substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an InSb-based crystal film, an InSb-based semiconductor device and a method for manufacturing the same, and more particularly to a method for forming an InSb-based crystal film having high mobility and high sheet resistance characteristics. And an InSb-based semiconductor device and a method for manufacturing the same.

[0002]

2. Description of the Related Art The mobility of single crystal InSb is the mobility of another compound semiconductor, for example, the mobility of GaAs of 700,000.
0 cm ² / Vs or InAs mobility 28,000 cm ²
Since it is at a much higher level of 78,000 cm ² / Vs than / Vs, it is frequently used as a Hall element for a magnetic detection sensor. In recent years, it has begun to be put to practical use as a magnetoresistive (MR) element for a rotation sensor.

Here, it is important for the InSb-based Hall element to have a high input / output impedance from the viewpoint of power consumption and the like. It must be formed very thin.

As a conventional method for forming a thin-film InSb crystal, for example, a method is known in which a single crystal of InSb is thinned to a predetermined thickness by performing machining such as cutting and grinding. Is technically difficult,
It is not used much because it is wasteful and time-consuming.

As another conventional method for forming a thin film of InSb, for example, an InSb crystal film is grown on a substrate such as single crystal mica or glass-coated ferrite by vapor deposition or the like, and then the substrate is peeled off. Is known, but in this case, the resulting In
Since the mobility of the Sb film is low, and the surface from which the substrate is peeled is roughened to deteriorate the characteristics, the Sb film is not sufficiently utilized.

In particular, the low mobility is remarkable because the lattice constant between the above-mentioned substrate material and the InSb crystal is largely different, so that the grown crystal is polycrystallized. The mobility obtained by this method is at most about 20,000 cm ² / Vs.

It is known that the mobility of the InSb crystal is gradually improved by growing the crystal film thickly. However, increasing the crystal film thickness also means increasing the sheet carrier concentration. Is not preferred.

[0008] Therefore, in making this into an element,
It is necessary to consider the trade-off relationship between sheet resistance and mobility. For this reason, for example, when the sheet resistance is set high, only a low level of mobility can be obtained, and a Hall element with sufficient characteristics can be obtained. Cannot be obtained.

As still another method of forming a conventional InSb crystal film, for example, a semiconductor substrate of a III-V compound not containing Sb containing GaAs as a typical example is used, and a III-V compound containing InSb is formed on this semiconductor substrate. There is known a method for growing a semiconductor crystal film of a -V compound.

According to this method, crystal film of InSb is oriented to grow strongly on the surface orientation of the semiconductor substrate, thus, also the mobility, 45,000Cm ² at the time of a thickness of 2 microns Growth
/ Vs, 70,000 cm ² / Vs at 8 micron growth
And a feature that a higher level can be obtained with the same film thickness as compared with those using other substrate materials described above. Therefore, this method is promising as a new method for forming an InSb-based crystal film. .

[0011]

SUMMARY OF THE INVENTION However, this GaAs
According to the conventional method for forming an InSb crystal film using a semiconductor substrate of No. 1, in order to secure a high sheet resistance value required for a Hall element, the thickness of the InSb crystal film is set to 0.1.
It is necessary to make it about 1 to 0.3 microns, but GaAs
The closer the substrate is to the substrate, the more crystal defects are present in the InSb crystal film.
Actually, it remains at a low level of about 23,100 cm ² / Vs.

Since the Hall voltage, which is the output of the Hall element, is proportional to the product of the mobility of the Hall element and the magnetic flux density, it is generally common to increase the magnetic flux density by using a magnetic material to collect the magnetic flux. Is being done. For example, In
When the Sb crystal film is sandwiched between two ferrite plates, the magnetic flux collection rate is improved. However, when a GaAs substrate is present, the distance between the ferrite plates is increased by the thickness of the GaAs substrate, and a significant improvement in the magnetic flux collection cannot be expected.

Accordingly, an object of the present invention is to provide a method for growing an InSb-based semiconductor crystal film on a semiconductor substrate of a III-V compound such as GaAs, which has a high sheet resistance and a high mobility with respect to the InSb-based crystal film. It is an object of the present invention to provide a method for forming an InSb-based crystal film that can simultaneously add the degree of temperature, a high-performance InSb-based semiconductor device utilizing the same, and a method for manufacturing the same.

[0014]

According to the present invention, a semiconductor crystal film of a group III-V compound containing InSb is grown on a semiconductor substrate of a group III-V compound containing no Sb. Another method is to provide a method for forming an InSb-based crystal film, characterized in that another substrate is bonded to the surface of the semiconductor crystal film opposite to the semiconductor substrate and the semiconductor substrate is removed.

In order to achieve the above object, the present invention provides a magnetic substrate and an InS bonded to the magnetic substrate.
an operating layer of a predetermined shape composed of a semiconductor crystal film of a III-V compound containing b, and an electrode provided on the operation layer, wherein the semiconductor crystal film is a III-V compound containing no Sb. The present invention provides an InSb-based Hall element characterized by being formed by growing a semiconductor crystal film of a group III-V compound containing InSb on a semiconductor substrate and removing the semiconductor substrate. is there.

Further, according to the present invention, in order to achieve the above object, a semiconductor crystal film of a III-V compound containing InSb is grown on a semiconductor substrate of a III-V compound containing no Sb. Another substrate is bonded to the surface of the crystal film opposite to the semiconductor substrate, the semiconductor substrate is removed, and the semiconductor crystal film is processed into a predetermined shape to form an operation layer as a Hall element. An object of the present invention is to provide a method for manufacturing an InSb-based Hall element, wherein an electrode is formed on an operation layer.

As the group III-V compound semiconductor not containing Sb, GaAs is typically used. Other specific materials include, for example, InAs, InP, and Ga.
P and the like.

As an apparatus used for growing an InSb-based crystal film on a semiconductor substrate, a molecular beam epitaxial growth apparatus, a metal organic chemical vapor deposition epitaxial growth apparatus,
A vacuum evaporation device or the like is conceivable.

As the bonding means for bonding the InSb-based crystal film to another substrate, a curable adhesive such as an epoxy-based adhesive or a polyester-based adhesive, or
The use of various organic adhesives such as anaerobic adhesives is appropriate.

As another substrate to be adhered to the InSb-based crystal film so as to be a base member, for example, ferrite which is a magnetic material is used for this. Further, a non-magnetic material such as glass or ceramics may be used in order to obtain linearity of output characteristics with respect to an external magnetic field.

It is preferable in the present invention to add a high sheet resistance to the InSb-based crystal film by removing the semiconductor substrate by etching, etching the InSb-based crystal film, and thereby thinning the crystal film. It is an embodiment.

As a method for removing the semiconductor substrate, a method for removing the semiconductor substrate by selective liquid phase etching is preferable. For example, when the substrate is made of GaAs, a known sulfuric acid / hydrogen peroxide system or the like is used. Anything should do. Note that it is possible to increase the efficiency of the semiconductor substrate removing operation by mechanically grinding the semiconductor substrate to a predetermined thickness before the etching process and performing the etching process thereafter.

Examples of the etchant for the InSb crystal film include hydrofluoric acid / hydrogen peroxide / water system, ferric chloride / hydrochloric acid system, ferric chloride aqueous solution, lactic acid / nitric acid system, nitric acid / hydrochloric acid / water system and the like. Known etching solutions can be used.

The growth thickness of the InSb-based crystal film on the semiconductor substrate is at least 100 nm because the larger the growth thickness, the more the mobility of the growth layer surface tends to recover and become higher.
It is desirable to set above. But if it ’s too thick,
It is desirable to set the thickness to 10 μm or less because the productivity is deteriorated, for example, the crystal growth time becomes longer, the thinning by etching takes time, and the like.

It is preferable to use Ti or Al, which has high adhesion to the InSb-based operation layer, as an electrode formed on the operation layer of the Hall element, and the surface of this electrode has a wire bonding property. From the viewpoint of improving the quality, it is desirable that the multilayer structure has Au as the outermost surface layer.

The electrodes may be made of a conductive organic material as long as they can withstand the operating conditions and operating environment of the Hall element.

[0027]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a procedure for forming an InSb crystal film. First, as shown in FIG. 1A, a 1.2 μm thick InSb film is formed on a semiconductor substrate 1 made of GaAs by a molecular beam epitaxial growth apparatus. A crystal film 2 is formed.

At this point, the mobility of the InSb crystal film 2 is 45,000 cm ² / Vs, the sheet carrier concentration is 2.8 × 10 ¹² cm ² , and the sheet resistance value is 50 ohm. Was.

Next, as shown in (b), the InSb crystal film 2
After applying an epoxy-based adhesive 3 to the surface on the opposite side of the semiconductor substrate 1 and bonding a magnetic ferrite substrate 4 thereto,
The GaAs semiconductor substrate 1 was mechanically ground.

Then, a known sulfuric acid / hydrogen peroxide-based etchant is applied to the semiconductor substrate 1 ground to a predetermined thickness as a GaAs etchant, thereby forming a GaAs etchant as shown in FIG. The semiconductor substrate 1 was completely removed.

After the semiconductor substrate 1 was removed, various characteristics of the InSb crystal film 2 were measured.
m ² / Vs, sheet carrier concentration 2.3 × 10 ¹² c
Both the m ² and the sheet resistance were 56 ohms, which were better than before the semiconductor substrate 1 was removed, and the effect of the present invention was confirmed.

This is because the disappearance of the interface layer with the GaAs semiconductor substrate 1 prevents generation of unnecessary carriers.

In the present embodiment, the thickness of the InSb crystal film 2 was further reduced by etching. The etching solution may be any of the above-mentioned known etching solutions, but in this embodiment, 49%
Hydrofluoric acid: 30% hydrogen peroxide: water = 1: 1: 12 was further diluted 100 times with water.

FIGS. 2A and 2B show FIGS.
9 summarizes the relationship between the thickness of the InSb crystal film 2 formed in (c) and mobility and sheet resistance, and the relationship between the thickness of the crystal film 2 and sheet carrier concentration.

According to these graphs, the sheet carrier concentration decreases linearly as the crystal film 2 becomes thinner due to the progress of etching, and the sheet resistance increases because it is proportional to the reciprocal of the product of the sheet carrier concentration and the mobility. I do. The mobility is about 50,0 to a thickness of about several tens nm where surface scattering (the phenomenon that electrons run on the crystal surface instead of in the crystal) becomes dominant.
Although the value should be maintained at 00 cm ² / Vs, in the present example, the mobility was sharply reduced at a thickness of 200 nm or less. This is considered to be because the variation in etching (irregularities on the surface) of the InSb crystal film cannot be ignored with respect to the film thickness, and the surface scattering becomes dominant in extremely thin portions.

Therefore, if an etching technique with a small variation in etching is developed, it is expected that this rapid decrease in mobility will be improved. In actual use, it is necessary to set the thickness of the InSb crystal film from the sheet resistance value required for the element. According to the present invention, the mobility is 50,000 cm ² / Vs and the sheet resistance is Can be realized as a Hall element of 500 Ω / sq, and further, 1,000 Ω / sq. As the sheet resistance increases, the power consumption can be reduced, and the width or length of the cross-shaped magnetic sensing surface of the Hall element can be increased or shortened. Sensitivity), and it is possible to form a Hall element having excellent characteristics which has not been achieved in the past. This thinning of the InSb crystal film by the etching process after removing the GaAs semiconductor substrate is adopted in most embodiments of the present invention.

The conventional example shown in FIG.
It shows the relationship between the InSb crystal film thickness and the sheet carrier concentration in a conventional type in which an InSb crystal film is formed on a semiconductor substrate of As. Compared with the embodiment of the present invention,
The carrier concentration of the conventional example is high, and a clear difference is observed between the two.

FIG. 3 shows an embodiment of the InSb-based Hall element according to the present invention, which is a continuation of the above-described step of FIG.

The thickness is 150 nm by the etching process.
The InSb crystal film 2 which has been thinned to the above shape is processed into a cross-shaped operation layer 2 ′ by a photolithography process, and then, at each end of the cross arm of the operation layer 2 ′, an ohmic electrode formation process is performed. Lowermost layer Ti, outermost layer Au
Is formed.

Thereafter, through a normal process (not shown) such as an insulating film, dicing, die bonding, wire bonding, and resin molding, a predetermined InSb-based Hall element was manufactured.

According to the characteristics of the InSb-based Hall element manufactured as described above, the mobility of the thinned InSb crystal film is 42,000 cm ² / Vs, and the sheet carrier concentration is 0.5 × 10 ¹² cm. ² and the sheet resistance is 29
The resistance could be significantly increased with the high mobility of 7 ohms, and a high-performance Hall element could be constructed as a whole.

The thickness variation in the InSb crystal film is maintained at a high level of ± 10% or less, the yield is high,
A Hall element could be manufactured under advantageous conditions.

A ferrite plate (not shown) is further provided on the InSb-based Hall element, and the InSb crystal film 2 is sandwiched between the ferrite plate and the ferrite substrate 4 to improve the magnetic flux collection. In that case, Ga
Compared with a Hall element in which an As substrate (having a thickness of 150 μm to 600 μm) remains, the magnetic flux collection (magnetic flux density) reaches three times or more, and as a result, a higher Hall voltage than ever before can be obtained.

In the above-described embodiment, the description has been given of the Hall element.
The b crystal film can be applied to a semiconductor element such as a magnetoresistive element. In the case of a magnetoresistive element, the magnetic sensitivity is proportional to the mobility of the InSb crystal film. Therefore, by using the high mobility InSb crystal film obtained according to the present invention, an unprecedented high sensitivity magnetoresistive element is obtained. be able to.

[0046]

As described above, in accordance with the present invention, In
According to the method of forming an Sb-based crystal film, and the method of manufacturing an InSb-based Hall element and a method of manufacturing the same, a semiconductor crystal film of a III-V compound containing InSb is formed on a semiconductor substrate of a III-V compound containing no Sb. After growing and bonding another substrate to this crystal film, the semiconductor substrate of the III-V compound not containing Sb is removed, so that a high mobility InSb crystal film can be left.

Accordingly, unlike the conventional GaAs semiconductor substrate, a layer having a low mobility does not exist at the interface. Therefore, when the thickness of the InSb-based crystal film is reduced, a high mobility is obtained. Can be maintained,
Further, since the InSb crystal film can be made thin, a high sheet resistance is guaranteed.

As a result, it is possible to provide a high-performance InSb-based Hall element which has a large input / output impedance, a large magnetizing effect, and can output a high Hall voltage.

When applied to a magnetoresistive element,
An extremely sensitive InSb-based magnetoresistive element can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of one embodiment of a method for forming an InSb crystal film according to the present invention, and (a) to (c) show the procedure.

FIGS. 2A and 2B are graphs showing the relationship between the thickness of an InSb crystal film and various characteristics in an example of the present invention, wherein FIG. 2A shows the relationship between the crystal film thickness and mobility and sheet resistance, and FIG. The relationship between the film thickness and the sheet carrier concentration is shown.

3A and 3B are explanatory views of one embodiment showing an InSb-based Hall element and a method of manufacturing the same according to the present invention, wherein FIG.
(B) is a front view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 GaAs semiconductor substrate 2 InSb crystal film 3 Adhesive 4 Ferrite substrate 5 Electrode

Claims (6)

[Claims] 1. A semiconductor crystal film of a III-V compound containing InSb is grown on a semiconductor substrate of a III-V compound containing no Sb. A method for forming an InSb-based crystal film, comprising bonding another substrate and removing the semiconductor substrate. 2. The semiconductor film according to claim 1, wherein said semiconductor crystal film is thinned by being etched after said semiconductor substrate is removed, thereby forming a crystal film having a predetermined sheet resistance characteristic. The method for forming an InSb-based crystal film according to the above. 3. An operating layer having a predetermined shape formed of a semiconductor crystal film of a group III-V compound containing InSb adhered to the substrate, and an electrode provided on the operating layer. The semiconductor crystal film is formed by growing a semiconductor crystal film of a III-V compound containing InSb on a semiconductor substrate of a III-V compound not containing Sb, and removing the semiconductor substrate. Characterized in that:
Sb-based semiconductor element. 4. The InSb semiconductor device according to claim 3, wherein said semiconductor crystal film is thinned by being etched after said semiconductor substrate is removed, whereby a predetermined sheet resistance characteristic is added. Series semiconductor element. 5. A semiconductor crystal film of a group III-V compound containing InSb is grown on a semiconductor substrate of a group III-V compound not containing Sb. Adhering another substrate, removing the semiconductor substrate, processing the semiconductor crystal film into a predetermined shape to form an operation layer as a semiconductor element, and forming an electrode on the operation layer. I
A method for manufacturing an nSb-based semiconductor device. 6. The semiconductor crystal film according to claim 5, wherein said semiconductor crystal film is thinned by being etched after said semiconductor substrate is removed, thereby forming a thin film having a predetermined sheet resistance characteristic. A method for manufacturing an InSb-based semiconductor device.