JP3063378B2 - Method for producing InSb thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 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, magneto-electric conversion elements have been required
2. Description of the Related Art As a sensor for detecting a position displacement or the like, it is widely used in consumer equipment such as a video tape recorder and industrial equipment such as a machine tool. Particularly in recent years, the demand for automobile sensors has been increasing with the advance of computerization of automobiles, and in particular, the use of gear sensors for detecting the number of revolutions in combination with iron gears has been increasing.

As a semiconductor material used for the magnetoelectric conversion element, there are compounds such as InSb, InAs, and GaAs. In general, inexpensive InSb which has a high electron mobility, provides a high signal output, and is inexpensive is often used. I have. Such a magnetoelectric conversion element using InSb includes a bulk type in which a thin plate cut out of a single crystal and polished is used by attaching it to an insulating substrate, and an I / O element directly on an insulating substrate by vapor deposition or the like.
There are two types: a thin film type in which an nSb thin film is formed or an InSb thin film formed on another substrate by vapor deposition or the like is transferred and adhered to an insulating substrate.

[0004]

However, the conventional I
The nSb magnetoelectric conversion element is similar to an automotive gear sensor.
In applications used in a wide temperature range of 50 to + 150 ° C. or in high temperatures, it has been difficult to use them for the following reasons.

The reason will be described with reference to an example of an InSb magnetoresistive element. First, a bulk type element has an electron mobility of:
It is dominated by impurity scattering in the low-temperature region and polar optical scattering in the high-temperature region, and has a peak value of electron mobility at the boundary between the regions where these are present. On the high temperature side from the peak value, the electron mobility changes substantially along the -1.7th power of the temperature, and has a sharp peak at an extremely low temperature of usually around 70K. Therefore, in the normal temperature range, the electron mobility shows a tendency to greatly decrease the gradient, and the signal output correlated therewith also greatly decreases with the temperature rise.

Further, in the bulk type, since an InSb thin plate is adhered to an insulating substrate with an adhesive resin or the like, when the temperature becomes high, the difference in the thermal expansion coefficient between the adhesive and the InSb thin plate causes In Inb.
Cracks occur in the Sb thin plate, making it unusable.

On the other hand, in the case of the thin film type, the scattering factor due to defects such as dislocations and other scattering factors such as grain boundary scattering and surface scattering are added, so that the electron mobility peaks at a high temperature. Side, and has a relatively broad peak near room temperature. Therefore, considering a temperature range of −50 to + 150 ° C., a change in signal output with respect to temperature is small, which is preferable in terms of temperature dependency. In addition, the thin-film type magnetoresistive element can easily increase the resistance, increase the driving voltage of the magnetoresistive element (the signal output is proportional to the electron mobility and the driving voltage), reduce power consumption, and reduce the size. There is an advantage that can be made.

However, an InSb thin film formed by directly depositing an InSb thin film on an insulative substrate is used, for example, as a growth substrate for epitaxial growth of the InSb thin film.
If dTe and PbTe single crystal substrates are used, a thin film having sufficiently large electron mobility can be obtained, but 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 at random and becomes a so-called polycrystalline type film, and as a result, a thin film having a large electron mobility is obtained. Is difficult, and a large signal output cannot be obtained.

[0009] In contrast, it has been clarified that the use of a cleaved mica substrate provides electron mobility comparable to that of a single crystal. However, with this method, it is difficult to obtain an InSb thin film that can be used for high-temperature applications. It is I
Because of the poor adhesion between the nSb thin film and the mica substrate, this In
This is because the Sb thin film must be transferred onto another insulating substrate via an adhesive layer such as epoxy and used. Therefore, in the completed magnetoresistive element, when the temperature is high, or when the temperature cycle from low to high temperature is repeated, the difference in thermal expansion coefficient between the adhesive layer and the InSb thin film is large,
In particular, the above-described -50 to +
In the temperature range of 150 ° C., it did not have the reliability that could withstand 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 method of forming a preliminary film made of In and Sb on a substrate made of an insulator or a surface-insulated substrate. Forming a film while increasing the ratio of the number of particles of Sb to In with the passage of 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 the same.

[0012]

According to this structure, in the preliminary film composed of In and Sb preformed at a low temperature (for example, room temperature), the ratio of the number of particles of Sb to In increases from the substrate side toward the upper layer. It becomes a nucleus for crystal growth of the InSb thin film formed by heating and raising, and the obtained InSb thin film is extremely sharp and preferentially oriented (C-axis oriented) in the (111) plane direction, and has excellent crystallinity. This InSb thin film having excellent crystallinity simply forms a thin film composed of In and Sb at a low temperature,
This is unique to the present invention, which cannot be obtained by simply applying a heat treatment thereto, nor can be obtained by heating and raising the temperature of the substrate without providing a preliminary film to form an InSb thin film.

Thus, In has good surface properties, high electron mobility, and good adhesion to an insulating substrate.
An Sb thin film can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an InSb thin film according to an 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 an InSb thin film according to the present embodiment. In this example, a glass substrate 1 (CGW # 7059 (manufactured by Corning)) was used as an insulating substrate. After the glass substrate 1 was organically washed, it was immediately introduced into a vacuum evaporation apparatus, and the degree of vacuum was 1 × 1.
After evacuation to 0 ^-5 Torr or less, first, as shown in the heating temperature profile of the glass substrate 1 in FIG.
b at room temperature, while maintaining the Sb / In particle number ratio reaching the glass substrate 1 at 2 or more, and setting the Sb / In particle number ratio to In at room temperature.
The Sb preliminary film 2 is formed by vapor deposition until the cumulative In film thickness becomes 10 nm on the glass substrate 1 while increasing as the upper layer of the Sb preliminary film 2 is reached.

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

FIGS. 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, respectively. In the case of the conventional method, the diffraction intensity of each crystal plane is random, and no result indicating the orientation of a specific plane has been obtained. That is, it is in a non-oriented state.

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

Further, InS fabricated by these two methods is used.
Observing the surface state of the b thin film 4 with a metallographic microscope, the InSb thin film 4 manufactured by the conventional method has extremely large irregularities on the surface of the film. 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 in performing microfabrication when forming a magnetoresistive element.
It may cause poor formation (related to reliability) or InSb
The problems of the conventional method, such as difficulty in uniformity of the thin film 4 (influencing the fluctuation of the midpoint potential of the magnetoresistive element) are solved. Further, the InSb thin film 4 manufactured by the method of the present embodiment is used.
Has extremely good adhesion to the base 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. Also, as shown in FIG.
After forming a short-circuit electrode 5 on the Sb thin film 4 and forming a pattern (L / W of a unit element = about 10) so as to form a magnetoresistive element structure having a large number of short-circuit electrodes 5, a protective film 6 is formed. After the actual semiconductor thin film magnetoresistive element, 3 kG
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 μm
m, the electron mobility is 1-1.5 m ² / V ·
sec. This is the maximum value that can be obtained, and the resistance change is 1.3 to
The electron mobility is 2.5 to 3.5 m ² / V · sec., Even at a film thickness of 1.5 μm, by using the manufacturing method of the present embodiment, while it is about 1.5 times. In addition, the resistance change is 2.5 to 3.0 times, which is very large and has excellent characteristics.

The important points in the manufacturing method of the present embodiment are the film thickness when forming the InSb preliminary film 2 at room temperature in FIG. 1 and the particle number ratio between Sb and In.
Therefore, focusing on this point, the crystal orientation of the InSb thin film 4 when these were changed was determined, and the results are shown in FIG. In the figure, the In cumulative film thickness on the glass substrate 1 is variable by 5 nm and 10 nm, and the horizontal axis represents the ratio of the number of Sb / In particles, and the vertical axis represents (220), (311), (422) The ratio of the diffraction line intensity at each crystal plane is taken. In addition, Table 2 shows the diffraction line intensity ratio of the InSb thin film 4 manufactured according to the conventional method and the present embodiment.

[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 the present embodiment, it can be seen that the (111) plane is sharply oriented. . Based on this, FIG. 4 shows a case where the cumulative In film thickness on the glass substrate 1 is 5 nm, which is indicated by a dotted line. As the Sb / In particle number ratio increases, the orientation of the InSb thin film 4 increases. It turns out that it becomes favorable. That is, Sb /
It turns out that the In particle number ratio is required to be 8 or more.

On the other hand, the accumulated In film thickness 10 on the glass substrate 1
In the case of nm, the particles are sharply oriented at a Sb / In particle number ratio of 2 or more. In other words, as the cumulative In film thickness on the glass substrate 1 increases (the film thickness increases), the Sb / In particles are well oriented even when the Sb / In particle number ratio is reduced, and the Sb / In particles grow under a certain In cumulative film thickness. If you set the number above a certain limit,
Good orientation. This is because, above a certain limit, the substrate heating process after the formation of the InSb preliminary film 2 is no longer possible.
This is because b evaporates and the amount of Sb remaining in the InSb preliminary film 2 during the main formation becomes substantially constant. Here, the glass substrate 1
If the upper In cumulative film thickness is smaller than 5 nm, the InSb thin film 4 will no longer be preferentially oriented in the (111) plane direction. This is because if the film thickness is too small, the influence of the underlying glass substrate 1 is large. Therefore, in order to orient the film with good reproducibility, it is preferable that the cumulative In film thickness on the glass substrate 1 be 10 nm or more.

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

In addition, when the InSb preliminary film 2 is formed, by increasing the number ratio of Sb / In particles as it goes to the upper layer, the crystal orientation of the InSb thin film 4 can be improved with good reproducibility. This is because in the process of heating and raising the temperature of the glass substrate 1 after forming the InSb preliminary film 2, InSb
This is because Sb is more likely to re-evaporate in the upper layer of the preliminary film 2 and thus Sb is more deficient (In excess) in the upper layer.
It is necessary to deposit relatively more Sb as it goes to the upper layer.

Further, after forming the InSb preliminary film 2,
The glass substrate 1 is heated and heated to irradiate only Sb to the glass substrate 1 immediately before the formation of the InSb main formation film 3, and then the InSb main formation film 3 is quickly formed. Crystallinity can be improved.
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 process of heating and raising the temperature of the InSb preliminary film 2.
At this time, by irradiating Sb alone, Sb deprives the surface of oxygen, and the oxide of this Sb has a high vapor pressure and is easily re-evaporated. As a result, the surface of the InSb preliminary film 2 is cleaned. By making it. When only In is irradiated alone, the melting point of In is low, and In does not easily re-evaporate, so that the film aggregates, impairs the surface properties of the film, and obtains a film having good crystallinity. Can not. Therefore, after irradiating Sb alone, it goes without saying that the InSb main formation film 3 may be formed by gradually increasing the number of evaporated In particles while continuously evaporating Sb.

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

In addition, in the manufacturing method of this embodiment, for example, before forming the InSb preliminary film 2, the glass substrate 1 is cooled at a high temperature after a process of maintaining the glass substrate 1 at a high temperature.
It goes without saying that a step of forming the InSb preliminary film 2 may be performed thereafter. Further, in the present embodiment, an example of the glass substrate 1 is shown as the substrate, but the present invention is not limited to this, and other insulating substrates or substrates whose surfaces are coated with an insulator such as glass may be used. You may. Further, in this embodiment, an example of an InSb thin film is shown. However, the InSb thin film of the present invention does not reject impurities inevitable in production and contains an additive in a range that does not form a ternary compound with In and Sb. It does not matter.

The magnetoresistive element using the InSb thin film 4 manufactured according to the manufacturing method of this embodiment is -50 to +15.
A characteristic deterioration test was repeatedly performed under a temperature cycle of 0 ° C., and it was confirmed that the element had no characteristic deterioration unlike the conventional case and had extremely high reliability.

[0033]

As described above, according to the method of manufacturing an InSb thin film of the present invention in which a preliminary film is formed and then a main film is formed, the crystallinity of the InSb thin film is improved, the electron mobility is high, 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 prepared 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 a temperature range of 0 ° C.
The industrial utility value is extremely large.

[Brief description of the drawings]

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

FIG. 2 is a relationship diagram showing the relationship between substrate temperature and time when the 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 a manufacturing method according to the present embodiment.

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

[Explanation of symbols]

 DESCRIPTION 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-54568 (JP, A) JP-A-3-106085 (JP, A) JP-A-58-78418 (JP, A) JP-A-5-784 299358 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/205 H01L 43/08

Claims (5)

(57) [Claims] 1. The method according to claim 1, wherein the number of Sb particles arriving at the substrate or the substrate made of an insulating material or a substrate whose surface is insulated is determined by the number of Inb
Forming a preliminary film by depositing In and Sb while increasing the ratio with respect to the number of particles over time,
Heating the substrate temperature on the preliminary film to a higher temperature than the substrate temperature in the step of forming the preliminary film to form a main film composed of an InSb compound. 2. A step of depositing Sb on the preliminary film between the step of forming the preliminary film and the step of forming the main film by heating the substrate to a temperature higher than the substrate temperature in the step of forming the preliminary film. The method for producing an InSb thin film according to claim 1, further comprising a step. 3. The In film 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.
A method for producing an Sb thin film. 4. The method according to claim 1, wherein the preliminary film is formed while maintaining the substrate temperature at 150 ° C. or lower. 5. A preliminary film is formed by depositing In so that the thickness of In is in the range of 10 nm to 1 μm.
The method for producing an InSb thin film according to the above.