JPH0359570B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an indium-gallium-antimony compound thin film useful for various applications as a semiconductor, and more specifically, to an excellent practical method that allows the composition ratio of indium and gallium to be adjusted to any desired ratio over a wide range. Indium-Gallium-
The present invention relates to a method for producing an antimony compound thin film. The indium-gallium-antimony compound represented by the formula In _1-y GaySb (where y is a number less than 1 indicating the atomic ratio) has a larger Hall coefficient than InSb, so when used as a magnetoelectric conversion element, It has the advantage of high sensitivity and maximum magnetic flux density sensitivity. Therefore, In _1-y GaySb can be said to be an extremely useful material as a semiconductor element material, but when obtaining this material as a single phase,
Bulk crystals also have the disadvantage of being difficult to manufacture. On the other hand, when this semiconductor material is used to produce a semiconductor device such as a magnetoelectric conversion element or a thin film field effect transistor, it is necessary to make it into a thin film. Conventionally, as a method of forming such a thin film, a method of cutting out and polishing a bulk crystal is known. However, although the thin film obtained by this method has excellent properties, cutting out and polishing such a single crystal causes a large amount of loss, and is not necessarily suitable as an industrial method. In addition, an extremely simple thin film formation method is a one-step formation method in which the compositional elements In, Ga, and Sb are vapor-deposited, but in this method, single-phase In _1-y
GaySb is difficult to form, and even if it is formed, its properties are extremely poor, and the deposition product
It is extremely difficult to coat the composition ratio of In, Ga, and Sb, and there is a drawback that it is difficult to obtain a crystalline vapor deposited film having a desired composition ratio. As a result of extensive research in order to improve these drawbacks, the inventors of the present invention have developed a method of vapor depositing antimony and indium on a heated substrate so that the composition ratio in the antimony and indium film is within a certain range. Then, we discovered that an In _1-y GaySb thin film with any Ga atomic ratio (y) could be obtained very easily by depositing gallium alone or gallium and antimony thereon, and based on this knowledge, we The present invention has now been completed. That is, in the present invention, antimony and indium are vapor-deposited on a heated substrate so that the composition ratio (F _Sb /F _Io ) in the film is 0.65 to 0.95, and then gallium alone or together with gallium is deposited on the heated substrate. Production of an indium-gallium-antimony based compound thin film represented by the general formula In _1-y GaySb (in the formula, y is a number less than 1 indicating the atomic ratio of gallium), characterized by simultaneously vapor depositing indium and antimony. The present invention provides a method. In the method of the present invention, first, antimony (Sb)
and indium (In) are evaporated onto a heated substrate to form a thin film such that the composition ratio (F _Sb /F _Io in the film is in the range of 0.65 to 0.95.
F _Sb /F _Io can be approximately determined by the ratio of the arrival rate of atoms to the substrate surface (arrival rate ratio) A _Sb /A _Io and the degree of substrate heating. i.e.
Between F _Sb /F _Io and A _Sb /A _Io , generally F _Sb /F _Io
The relational expression ≦A _Sb /A _Io holds true, and A _Sb /A _Io is 0.85.
In the following cases, A _Sb /A _Io and F _Sb /F _Io are equal, so F _Sb /F _Io is uniquely determined. Furthermore, when the substrate temperature at the initial stage of vapor deposition is as high as 420°C or higher under a vacuum of 10 ^-5 torr, and A _Sb /A _Io is greater than 0.85, F _Sb /F _Io <A _Sb /A _Io becomes the desired value. A slightly larger amount of Sb is deposited according to the composition ratio of . In this way, a thin film is first formed on the heated substrate so that the composition ratio of antimony and indium (F _Sb /F _Io ) is in the range of 0.65 to 0.95, and then gallium (Ga) alone or a combination of gallium and antimony is formed. are simultaneously deposited. At this time, the atomic ratio y of the Ga composition in the In _1-y GaySb thin film is determined by the following formula: y=A _Ga /ΣA _Sb (In the formula, A _Ga /ΣA _Sb is the rate at which Ga and Sb atoms reach the substrate surface. ΣA _Sb is the sum of the speed at which Sb reaches the substrate surface when it is first evaporated with In and the speed at which Sb reaches the substrate surface when it is evaporated simultaneously with Ga). . That is, in the method of the present invention, y can be primarily controlled by the atomic arrival velocity ratio. Incidentally, this amount can be controlled in advance when forming a thin film. The possibility of controlling y in this way depends on the conditions during the initial formation of the InSb thin film. For example, if F _Sb /F _Io is greater than 0.95,
When forming an InSb thin film, y is not determined,
Two-phase or three-layer thin films can be obtained, but these have extremely poor properties. Furthermore, when an InSb thin film is formed under conditions where F _Sb /F _Io is smaller than 0.65, the resulting film becomes transparent and has extremely poor properties. That is, according to the present invention, F _Sb /F _Io is from 0.65 to
InSb with an appropriate amount of In excess to be in the range of 0.95
Forming a thin film is unreliable in order to obtain single-phase In _1-y GaySb, and only in this case y is uniquely determined by the deposition conditions. The initial InSb deposition in the method of the present invention is
Although InSb may be used as an evaporation source, in order to easily control A _Sb /A _Io , it is preferable to use In and Sb as separate evaporation sources. In this case as well, it is of course possible to use Sb alone as the Sb source, but
Compounds such as GaSb and InSb can be used. It is generally preferable to use a highly purified evaporation source, but in the method of the present invention,
The characteristics of the semiconductor device obtained do not substantially change even if a number of about three nines is used. Therefore, the method of the present invention has the advantage that such relatively low purity materials can be used as a deposition source. In the next deposition in the method of the invention,
Whether to evaporate only Ga or to evaporate Ga and Sb at the same time is appropriately selected depending on the desired y value. For example, if y is 0.3 or less, either method may be used, but if y exceeds 0.3, the latter method may be used. The method is preferred. If the former method is used, Sb
This is because the ratio of the sum of In and Ga to the total amount of In and Ga becomes too large, making it difficult to form a high-quality film. In this case, the Ga supply source is not only Ga alone but also GaSb.
can also be used. There are no particular limitations on the deposition substrate used in the method of the present invention, and commonly used substrates can be advantageously used. Such substrates include, for example, sapphire, CaF ₂ , NaCl, mica, glass, Cr-
Examples include dove GaAs. Particularly preferred are crystalline substrates. In the method of the present invention, during the deposition process, the substrate is heated to about 530°C, which is the melting point of InSb, for the first InSb deposition.
There is no particular restriction as long as the temperature is maintained at ℃ or below. The substrate is usually set at a suitable temperature of 530° C. or less, but the temperature can also be raised or lowered during deposition, and it can also be varied slowly or rapidly. In addition, in the next vapor deposition process, the temperature of the substrate is usually maintained at the temperature at the end point of InSb vapor deposition, but it may be changed to a higher or lower temperature, or it may be set to a higher or lower temperature gradually or suddenly during the vapor deposition. The temperature can also be raised or lowered. Furthermore, in the method of the present invention, the degree of vacuum when depositing metal is the same as that commonly used.
10 ^-3 Torr or higher is advantageously employed. The lowest limit is determined from the mean free path of In, Sb, and As, and an appropriate degree of vacuum higher than that is used. It is also possible to replace the inside of the vapor deposition apparatus (belgear) with N ₂ , Ar, etc. and then reduce the pressure to a desired degree of vacuum. The vapor-deposited product obtained by the method of the present invention can be formed to have any thickness within a range that maintains the characteristics, depending on the intended use as a semiconductor device and its desired characteristics. Usually from several 100Å to several
A range of up to 10 μm is advantageously employed industrially. Means or devices for carrying out the method of the present invention include:
There are no limitations as long as they do not deviate from the technical concept of the present invention described above. For example, heating means such as heater heating or EB heating, or extremely ordinary means such as flash deposition may be used for vapor deposition, or
MBE, ion beam method, etc. can also be applied. Further, the thin film deposition rate by the method of the present invention can be in a wide range of, for example, 0.1 to 1000 Å/sec, but the film thickness formation rate of about 1 to 100 Å/sec is preferable due to the ease of controlling the attained rate ratio. preferable. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Mica was used as a substrate, and a vapor deposition apparatus having a concentrically rotating substrate holder on which six wafers could be placed was used. As raw materials In, Sb, and Ga, 6-N manufactured by Furuuchi Chemical Co., Ltd. was used. The degree of vacuum is 5×10 ^-6 Torr, and the substrate temperature is 400℃.
It was set to Next, while raising the substrate temperature to 500°C, adjust Sb and In to 30°C so that A _Sb /A _Io becomes 0.94.
It was deposited for a minute. Next, while raising the substrate temperature to 540° C., Ga was deposited for 4 minutes so that A _Ga /A _Sb was 0.20. When the obtained thin film was examined by X-ray diffraction, y was found to be
It was found that a single-phase ternary crystal In _0.8 Ga _0.2 Sb of 0.2 was obtained. When the characteristics of six wafers were measured using the Pau method, the mobility was 25,000 to 26,500 cm ² /V sec,
The Hall coefficient was 850-900 cm ³ /c. By the way, the mobility of the film obtained by another evaporation process that stops before the InSb formation stage is 22,000 to 23,000.
cm ² /V·sec, and the Hall coefficient was 300 to 320 cm ³ /c. Comparative Example 1 A _Sb / during initial InSb formation in Example 1
The operation was exactly the same as in Example 1 except that A _Io was changed to 1.2, and ^Ga was later deposited. It was ~130cm ³ /c. Comparative Example 2 When In, Sb, and Ga were simultaneously deposited under the same conditions as Example 1, the mobility of the obtained film was 3000~
4000cm ² /V・sec, Hall coefficient is 150-200cm ³ /c
It was hot. Example 2 In _0.8 Ga _0.2 was deposited as follows under the same conditions as Example 1 except that Ga and Sb were evaporated instead of Ga alone.
A thin Sb film was formed. First, evaporation is performed with A _Sb /A _Io of 0.83, and then Sb is deposited again so that ΣA _Sb /A _Io is 0.94.
Ga was simultaneously deposited so that A _Ga /ΣA _Sb was 0.2. y calculated from the X-ray diffraction pattern of the obtained thin film was 0.20, and its characteristics were the same as in Example 1 within experimental errors. Examples 3 to 5 Various thin films were formed under the same vapor deposition conditions as in Example 1 using various attained velocity ratios as shown in Table 1, and y and characteristics were determined for each. The results are shown in Table 1.

[Table] Note that the InSb-only thin films formed under the conditions of A _Sb /A _Io in Examples 3 to 5 had the best characteristics among them, with a mobility of 25000 cm ² /V·sec and a Hall coefficient of 320 cm ³ / C. Therefore, as can be seen from Table 1, the method of the present invention resulted in a thin film that was greatly improved, especially in terms of the Hall coefficient. Comparative Examples 3 to 5 Various thin films were formed under the same vapor deposition conditions as in Example 1, with A _Sb /A _Io being set to 1 or more, with almost no change in A _Sb /A _Io in Examples 3 to 5, and the characteristics of each were determined. The results are shown in Table 2.

[Table] In this case, y is not determined in any case, and 2
It became phase or three phase. Example 6 Using the same equipment, substrate, and raw materials as in Example 1, vapor deposition was first performed with A _Sb /A _Io of 0.79, and then Sb and A were deposited so that ΣA _Sb /A _Io was 0.91. Ga was simultaneously deposited so that _Ga /ΣA _Sb was 0.4. The obtained thin film had a y of 0.38, a Hall coefficient of 1450 cm ³ /C, and a mobility of 12000 cm ² /V.
S, and had a particularly large Hall coefficient. Example 7 The initial substrate temperature was set to 430°C, and the degree of vacuum was set to 7x.
At 10 ^-5 Torr, a large amount of Sb is initially deposited, and the average
Set A _Sb /A _Io to 0.94 and set the board temperature to 500.
In and Sb were deposited for 30 minutes while increasing the temperature to ℃. Next, while increasing the substrate temperature to 540℃, A _Ga /A _Sb
Ga was deposited for 4 minutes so that the value was 0.2. When the obtained thin film was examined by X-ray diffraction, it was found that y was
0.23, and when the composition ratio of In and Sb was examined by atomic absorption, F _Sb /F _Io was 0.85. In addition, the mobility is 46,000 to 49,000 cm ² /V・sec, and the Hall coefficient is 950.
It was ~970cm ³ /C. Example 8 In _0.8 Ga _0.2 Sb was produced in the same manner as in Example 1, using a slide substrate instead of the mica substrate in Example 1. The mobility was 6500 cm ² /V·sec, and the Hall coefficient was 300 cm ³ /C. In addition, in the case of InSb only, the mobility is 6000cm ² /
V·sec and Hall coefficient were 150 cm ³ /C.

Claims (1)

[Claims] 1. The composition ratio (F _Sb /F _Io ) of antimony and indium in the film is 0.65 to 0.95.
In _1-y GaySb (In the formula, y indicates the atomic ratio of gallium.) A method for producing an indium-gallium-antimony compound thin film represented by: