JPH05304097A - Manufacture of insb thin film - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing an InSb thin film through which a magnetoelectric conversion element excellent in temperature characteristics and reliability and hardly deteriorated in characteristics at a high temperature is realized. CONSTITUTION:An InSb pre-film 2 is evaporated on a glass substrate 1 increasing the ratio of the number of Sb particles to the number of In particles with a deposition time, an InSb proper film 3 is evaporated thereon at a higher substrate temperature, and an InSb film 4 is formed thereon. An InSb thin film formed by this method is excellent in crystal orientation property, large in electron mobility, and excellent in temperature characteristics. Therefore, a short-circuit electrode 5 and a protective film 6 are formed on the InSb film 4 for the formation of a magnetoresistive element, where the glass substrate 1 is hardly separated off from the InSb thin film 4 at a high temperature of 150 deg.C, so that the magnetoresistive element excellent in temperature characteristics and reliability at a high temperature can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an InSb thin film used for a magnetoelectric conversion element such as a semiconductor magnetoresistive element or a Hall element.

[0002]

2. Description of the Related Art In recent years, magnetoelectric conversion elements have been
As a sensor for detecting positional displacement, it is widely used in consumer equipment such as video tape recorders and industrial equipment such as machine tools. In particular, recently, the demand for sensor for automobiles has increased along with the computerization of automobiles, and in particular, the use for gear sensor for detecting the number of revolutions in combination with an iron gear has been increasing.

Compounds such as InSb, InAs, and GaAs are available as semiconductor materials used for the magnetoelectric conversion element. In general, InSb is used because it has a large electron mobility and a high signal output is obtained. There is. As the magnetoelectric conversion element using such InSb, a bulk type in which a thin plate prepared by cutting out and polishing a single crystal is attached to an insulating substrate, and a bulk type in which the thin plate is used directly on the insulating substrate by vapor deposition or the like.
There are two types, namely, a thin film type in which an nSb thin film is formed, or an InSb thin film formed by vapor deposition or the like on another substrate is transferred and adhered to an insulating substrate.

[0004]

However, the conventional I
The nSb magnetoelectric conversion element is like a gear sensor for automobiles.
In a wide temperature range of 50 to + 150 ° C. or in an application used in a high temperature, it is difficult to use due to the following reasons.

The reason will be explained using an example of an InSb magnetoresistive element. First, the bulk type has an electron mobility
It is dominated by impurity scattering in the low temperature region and polar optical scattering in the high temperature region, and electron mobility peaks at the boundaries of the regions in which they exist. On the high temperature side from the peak value, the electron mobility changes substantially along the -1.7th power of the temperature, and usually has a sharp peak at an extremely low temperature around 70K. Therefore, in the normal temperature region, the electron mobility shows a large decreasing tendency of the gradient, and the signal output correlated therewith also greatly decreases with increasing temperature.

Further, in the bulk type, since an InSb thin plate is attached to an insulating substrate with an adhesive resin or the like, due to a difference in thermal expansion coefficient between the adhesive and the InSb thin plate at high temperature, In
The Sb thin plate is cracked and becomes unusable.

On the other hand, in the case of the thin film type, since a scattering factor caused by defects such as dislocations and another scattering factor such as grain boundary scattering and surface scattering are added, the peak of electron mobility is high. Since it shifts to the side and has a relatively broad peak near room temperature, when considering the temperature range of −50 to + 150 ° C., the change in signal output with respect to temperature is small, which is preferable in terms of temperature dependence. In addition to this, the thin-film type magnetoresistive element can easily be made high in resistance, the driving voltage of the magnetoresistive element can be increased (the signal output is proportional to the electron mobility and the driving voltage), low power consumption, and small size. It has the advantage that it can be realized.

However, an InSb thin film formed by vapor deposition directly on an insulating substrate is used as a growth substrate for epitaxial growth of the InSb thin film.
Although it is possible to obtain a thin film having a sufficiently high electron mobility by using a dTe or PbTe single crystal substrate, these substrates are extremely expensive. In addition, if an inexpensive substrate such as a glass substrate is used, the cost can be reduced, but at this time, the thin film grows randomly and becomes a so-called polycrystalline type film, and as a result, a thin film with high electron mobility can be obtained. Is difficult and you can't get a big signal output.

On the other hand, it has been clarified that an electron mobility equivalent to that of a single crystal can be obtained by using a cleaved mica substrate. However, with this method, it is difficult to obtain an InSb thin film that can be used in high temperature applications. That is I
Since the adhesion between the nSb thin film and the mica substrate is poor, this In
This is because the Sb thin film must be transferred and used on another insulating substrate via an adhesive layer such as epoxy. Therefore, in the completed magnetoresistive element, the difference in the thermal expansion coefficient between the adhesive layer and the InSb thin film is large when the temperature is high or when the temperature cycle of low temperature to high temperature is repeated,
In particular, the Sb thin film is cracked.
In the temperature range of 150 ° C, it was not reliable enough for practical use.

An object of the present invention is to provide a method for producing an InSb thin film having good temperature characteristics and sufficient reliability even in high temperature applications such as gear sensors for automobiles.

[0011]

In order to achieve the above object, a method of manufacturing an InSb thin film according to the present invention comprises a substrate made of an insulating material or a surface-insulated substrate, and a preliminary film made of In and Sb formed on the substrate. Which is reached while increasing the ratio of the number of particles of Sb and In while increasing the deposition time, and heating the substrate to a temperature higher than the substrate temperature in the step of forming the preliminary film to further deposit the InSb thin film on the preliminary film. And a step of forming.

[0012]

According to this structure, the preliminary film made of In and Sb preformed at a low temperature (for example, room temperature) has a particle number ratio of Sb and In that increases from the substrate side to the upper layer. It becomes a nucleus of crystal growth of the InSb thin film formed by heating and raising the temperature, and the obtained InSb thin film is extremely sharply preferentially oriented in the (111) plane direction (C-axis orientation) and has excellent crystallinity. This InSb thin film having excellent crystallinity forms a thin film composed of In and Sb at a low temperature,
This is peculiar to the present invention, which cannot be obtained only by applying heat treatment thereto, and cannot be obtained even when an InSb thin film is formed by heating and heating the substrate without providing a preliminary film.

As a result, In having a good surface property, a high electron mobility, and a good adhesion to an insulating substrate can be obtained.
An Sb thin film can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an InSb thin film in one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a thin film magnetoresistive element using the InSb thin film of this embodiment. In this example, the glass substrate 1 (CGW # 7059 (made by Corning)) was used as the insulating substrate. After the glass substrate 1 is organically washed, it is immediately introduced into a vacuum vapor deposition apparatus, and the degree of vacuum is 1 × 1.
After evacuation to 0 ^-5 Torr or less, as shown in the heating temperature profile of the glass substrate 1 in FIG.
The preliminary film 2 (hereinafter referred to as an InSb preliminary film) made of b is kept at room temperature while maintaining the Sb / In particle number ratio reaching the glass substrate 1 at 2 or more, and the Sb / In particle number ratio is In.
The Sb preliminary film 2 is formed by vapor deposition while increasing as it goes to the upper layer of the Sb preliminary film 2 until the cumulative In film thickness becomes 10 nm on the glass substrate 1.

Thereafter, the glass substrate 1 is heated and heated to maintain the substrate temperature at 450 ° C., and the InSb main forming film 3 is subjected to Sb / Sb /
The InSb thin film 4 was formed with an In particle number ratio of 2 or more.
For comparison, without forming the InSb preliminary film 2,
An InSb thin film 4 was formed by directly forming only the InSb main formation film (hereinafter referred to as a conventional method).

3 (a) and 3 (b) show the results of thin film X-ray diffraction measurement of the crystallinity of the InSb thin film 4 manufactured by the conventional method and the manufacturing method of this embodiment. In the case of the conventional method, the diffraction intensity of each crystal plane is random, and the result showing the orientation of the specific plane has not been obtained. That is, it is in a non-oriented state.

On the other hand, In produced by the production method of this embodiment
In the Sb thin film 4, it can be seen that the diffraction intensity of the (111) plane is extremely strong and preferentially oriented in this plane direction. That is, the crystallinity is improved.

InS produced by these two methods
When observing the surface state of the b thin film 4 with a metallographic microscope, the InSb thin film 4 produced by the conventional method has extremely large unevenness on the surface of the film, whereas the InSb thin film 4 produced by the present example has a relatively large unevenness. It can be seen that the surface of the film is smooth. The smoothness of the surface of the InSb thin film 4 is extremely advantageous when performing microfabrication when forming a magnetoresistive element,
It may cause formation failure (related to reliability) or InSb
The problems of the conventional method such as difficulty in the uniformity of the thin film 4 (which affects the fluctuation of the midpoint potential of the magnetoresistive element) are solved. Furthermore, the InSb thin film 4 manufactured by the method of this embodiment.
Has extremely good adhesion to the substrate such as the glass substrate 1.

Next, the electron mobility of the InSb thin film 4 manufactured by the conventional method and the manufacturing method of this embodiment was measured by the Van der Pauw method. In addition, as shown in FIG.
After forming the short-circuit electrode 5 on the Sb thin film 4 and performing pattern formation (L / W = about 10 for unit element) so as to form a magnetoresistive element structure having a large number of short-circuit electrodes 5, a protective film 6 is formed. 3kG after making the actual semiconductor thin film magnetoresistive element
The resistance change in the magnetic field was measured. The results are shown in (Table 1).

[0021]

[Table 1]

As shown in (Table 1), in the conventional method, 3 μ
Even with a film thickness of m, the electron mobility is 1 to 1.5 m ² / V ·
sec. The maximum value that can obtain the degree, the resistance change is also 1.3 ~
Although it is about 1.5 times, by using the manufacturing method of this embodiment, the electron mobility is 2.5 to 3.5 m ² / V · sec even when the film thickness is 1.5 μm. It can be said that the resistance change is 2.5 to 3.0 times, which is extremely large and has good characteristics.

By the way, what is important in the fabrication method of this embodiment is the film thickness and the particle number ratio of Sb and In when the InSb preliminary film 2 is formed at room temperature in FIG.
Therefore, paying attention to this point, the crystal orientation of the InSb thin film 4 when these were changed was obtained, and the results are shown in FIG. In this figure, the cumulative In film thickness on the glass substrate 1 is variable between 5 nm and 10 nm, the horizontal axis represents the Sb / In particle number ratio, and the vertical axis represents the diffraction line intensity of the InSb (111) plane (220), The ratio of the diffraction line intensities at the crystal planes of (311) and (422) is taken. Further, (Table 2) shows the diffraction line intensity ratio of the InSb thin film 4 produced by the conventional method and this example.

[0024]

[Table 2]

As shown in (Table 2), in the conventional method, the diffraction line intensity is random as described above, but in the manufacturing method of this embodiment, the (111) plane is sharply oriented. .. Based on this, when FIG. 4 is viewed, the case where the cumulative In film thickness on the glass substrate 1 is 5 nm is shown by a dotted line. As the Sb / In particle number ratio increases, the orientation of the InSb thin film 4 becomes It turns out that it becomes good. That is, Sb /
It is understood that the In particle number ratio needs to be 8 or more.

On the other hand, the cumulative In film thickness on the glass substrate 1 is 10
In the case of nm, it is sharply oriented at a Sb / In particle number ratio of 2 or more. That is, as the In cumulative film thickness on the glass substrate 1 increases (the film thickness becomes thicker), the Sb / In particle number ratio is favorably oriented even if the Sb / In particle number ratio is small. If you set the number above a certain limit,
Orients well. This is because, above a certain limit value, S is no longer present in the substrate heating process after the InSb preliminary film 2 is formed.
This is because b is evaporated and the amount of Sb remaining in the InSb preliminary film 2 during the main formation becomes almost constant. Here, the glass substrate 1
When the above In cumulative film thickness is made smaller than 5 nm, the InSb thin film 4 is no longer preferentially oriented in the (111) plane direction. This is because when the film thickness is too thin, it is greatly affected by the underlying glass substrate 1. Therefore, in order to orient with good reproducibility, the In cumulative film thickness on the glass substrate 1 is preferably 10 nm or more.

On the other hand, when the In cumulative film thickness is 1 μm or more, InS is increased in the heating and heating process after the InSb preliminary film 2 is formed.
b When the preliminary film 2 is cracked, the InS
b The preliminary film 2 becomes a factor that hinders the characteristics. Considering these points, the In cumulative film thickness is preferably in the range of about 10 nm to 1 μm.

Further, when the InSb preliminary film 2 is formed, the crystal orientation of the InSb thin film 4 can be improved with good reproducibility by increasing the Sb / In particle number ratio as it goes to the upper layer. This is a process in which the glass substrate 1 is heated and heated after the InSb preliminary film 2 is formed.
This is because Sb is more likely to be re-evaporated in the upper layer of the preliminary film 2, and thus Sb is more likely to be deficient in the upper layer (In is excessive).
It is necessary to apply a relatively large amount of Sb to the upper layer.

Further, after the InSb preliminary film 2 is formed,
The glass substrate 1 is heated and heated, and immediately before the InSb main forming film 3 is formed, the glass substrate 1 is irradiated with Sb only, and then the InSb main forming film 3 is rapidly formed. It becomes possible to improve the crystallinity.
This is because the surface of the InSb preliminary film 2 is covered with oxygen or the like depending on the degree of vacuum in the heating and heating process of the InSb preliminary film 2.
At this time, by irradiating Sb alone, Sb deprives the surface of oxygen, and since the oxide of this Sb has a high vapor pressure and easily re-evaporates, the surface of the InSb preliminary film 2 is consequently cleaned. It depends on. In addition, when only In is irradiated alone, the melting point of In is low, and In does not easily re-evaporate, so that it aggregates, impairs the surface property of the film, and obtains a film having good crystallinity. I can't. Therefore, it is needless to say that the main InSb forming film 3 may be formed by irradiating Sb alone and then gradually evaporating Sb while gradually increasing the number of evaporated particles of In.

Further, in this embodiment, the substrate temperature at the time of forming the InSb preliminary film 2 is room temperature, but of course, even if the substrate temperature is raised, if it is lower than the substrate temperature at the time of main formation,
Similar results can be obtained by selecting an appropriate Sb / In particle number ratio. However, in order to preferentially orientate with good reproducibility and to keep the surface property of the InSb thin film 4 smooth,
It is preferable to keep the substrate temperature low at the time of forming the InSb preliminary film 2, and it is desirable to keep it at 150 ° C. or lower.

In addition, in the manufacturing method of this embodiment, for example, before the InSb preliminary film 2 is formed, after the glass substrate 1 is kept at a high temperature, the glass substrate 1 is cooled,
Needless to say, the step of forming the InSb preliminary film 2 may be performed thereafter. Further, although the example of the glass substrate 1 is shown as the substrate in the present embodiment, the present invention is not limited to this, and other insulating substrate or a substrate whose surface is coated with an insulator such as glass is used. May be. Further, although an example of the InSb thin film is shown in the present embodiment, the InSb thin film of the present invention does not reject impurities inevitable in manufacturing, and contains an additive within a range not forming a ternary compound with In and Sb. It doesn't matter.

Incidentally, a magnetoresistive element using the InSb thin film 4 manufactured by the manufacturing method of this embodiment is -50 to +15.
A characteristic deterioration test was performed repeatedly under a temperature cycle of 0 ° C., and it was confirmed that the characteristic deterioration of the element which occurred conventionally does not occur and that the element has extremely high reliability.

[0033]

As described above, according to the method of manufacturing an InSb thin film of the present invention in which the preliminary film is formed and then the main film is formed, the crystallinity of the InSb thin film is improved, the electron mobility is large, and The surface property of the InSb thin film is also improved, and the fine workability is also improved. Therefore, using the manufacturing method of the present invention,
By using the manufactured InSb thin film, -50 to +15
It is possible to provide a semiconductor thin film magnetoresistive element having good temperature characteristics and sufficiently high reliability even in the temperature range of 0 ° C.
The industrial utility value is extremely high.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetoresistive element using an InSb thin film according to an embodiment of the present invention.

FIG. 2 is a relationship diagram showing a relationship between a substrate temperature and a time when the same InSb thin film is manufactured.

3A is an X-ray diffraction diagram of an InSb thin film according to a conventional method. FIG. 3B is an X-ray diffraction diagram of an InSb thin film according to the manufacturing method of this example.

FIG. 4 is a diagram showing the relationship between the Sb / In particle number ratio in the preliminary film forming step and the crystal orientation of the obtained InSb thin film in the manufacturing method of this example.

[Explanation of symbols]

 1 glass substrate 2 InSb preliminary film 3 InSb main formation film 4 InSb thin film 5 short-circuit electrode 6 protective film

Claims (5)

[Claims] 1. A substrate made of an insulator or a substrate whose surface is insulated, and the number of Sb particles reaching the substrate and In.
Forming a preliminary film by depositing In and Sb while increasing the ratio with the number of particles of the above with the passage of deposition time;
A method of manufacturing an InSb thin film, comprising the step of forming a main forming film made of an InSb compound by heating the substrate temperature on the preliminary film to be higher than the substrate temperature in the forming process of the preliminary film. 2. Between the step of forming the preliminary film and the step of forming the main film, the substrate temperature is heated above the substrate temperature in the step of forming the preliminary film to deposit Sb on the preliminary film. The method for producing an InSb thin film according to claim 1, wherein a step is added. 3. The In according to claim 1, wherein the preliminary film is formed by setting the ratio of the number of Sb particles to the number of In particles to 2 or more.
Manufacturing method of Sb thin film. 4. The method for producing an InSb thin film according to claim 1, wherein the preliminary film is formed while maintaining the substrate temperature at 150 ° C. or lower. 5. The preliminary film is formed by depositing In so as to have a thickness of 10 nm to 1 μm.
A method for producing the InSb thin film described.