JPS5927519A - Fabrication of indium-antimony-arsenic system compound semiconductor thin film - Google Patents

Abstract

PURPOSE:To fabricate a semiconductor thin film by vacuum-depositing In and Sb on a substrate in such condition that the transport speed rate of Sb to In is kept at 1.0 or more and a substrate temperature is kept within the particular range in the initial stage of vacuum-deposition, and by vacuum-depositing arsenic etc. after forming a thin film in the particular composition ratio with the speed ratio of 1.0 or less. CONSTITUTION:Both In and Sb are vacuum-deposited on a substrate. In this case, these are deposited in the initial condition in such a condition that the transport speed ratio ASb/AIn of both atoms is set to 1.0 or more and a substrate temperature is kept within the range from the substrate temperature Tc of interface given as a function of a degree of vacuum P to 30 deg.C. After nuclei of InSb is formed in the initial stage of vacuum-deposition, deposition is controlled so that the transport speed ratio ASbAIn is kept to 1.0 or less and an InSb system thin film having the composition ratio (FSb/FIn) in the range of 0.65-0.95 is formed. As is individually vacuum-deposited or both As and In are simultaneously vacuum-deposited on the InSb system thin film having a high mobility. Thereby, an InSb1-xAsx thin film is effectively formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an indium-antimony-arsenic (In5bAs)-based compound semiconductor thin film that is useful for various purposes as a semiconductor, and more specifically, to a method for manufacturing an In5bAs-based compound semiconductor thin film having extremely high mobility. The present invention relates to a method for manufacturing a thin film.

The In5bAs-based compound represented by the formula n5b1-xAsx (where X is a number less than 1 indicating the atomic ratio of arsenic) is
Compared to indium-antimony (InSb)-based compounds, the temperature dependence of resistance is smaller, so the atoms in InSb
This has the advantage that the temperature compensation required for the b-element is unnecessary or can be made extremely easy. Therefore InSb, -x
Although AsX can be said to be an extremely useful substance as a semiconductor element material, it has the disadvantage that it is difficult to manufacture even when obtained as a bulk crystal.

On the other hand, when using this semiconductor material to make semiconductor devices such as magnetoelectric transducers and thin film field effect transistors, it is necessary to form it into a thin film, and conventional methods for forming such thin films include , a method of cutting out and polishing a bulk crystal is known. 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.

By the way, as a simple method for manufacturing a thin film of InSb1-xASX, a method has been proposed in which InSb and InSb are used as deposition materials and both are simultaneously deposited on a substrate to obtain a thin film element (West German Publication). Patent No. 225219
Publication No. 7). However, according to this method, it is difficult to control X, so the inventors first determined the atomic arrival rate ratio (arrival rate ratio) of sb and In.
I by depositing sb/AXn on a deposition substrate at 1 or less
After forming an nSb composite crystal thin film, As
Alternatively, a method of vapor depositing As and In was proposed.

This method certainly makes it easier to control the arsenic atomic ratio (x), but in terms of characteristics, the value obtained is only about half of that obtained from bulk crystals.

As a result of further repeated experimental studies, the inventors found that I
The present inventors have discovered that the properties of ■n5bAs-based compound semiconductor thin films can be made extremely excellent by placing detailed restrictions on the vapor deposition conditions at the nSb-based composite crystal thin film stage, and have completed the present invention.

That is, the present invention aims at increasing the arrival velocity ratio (AI, b/A□n) of antimony atoms to indium atoms at the initial stage of vapor deposition.
) is i, o or more, and the substrate temperature (absolute temperature) T is the formula % formula % [Here, Tc is the boundary substrate temperature (absolute temperature), P is the vacuum [(Torr)] during the deposition. When the substrate temperature at the given boundary is Tc, indium and antimony are deposited on the substrate under conditions selected to be within the range of Tc≦T≦Tc + 30, and then the above-mentioned attained velocity ratio (A8b/Aln ) is smaller than 1.0 to form an indium-antimony thin film with a composition ratio of antimony to indium (Fsb/p'+n) of 0.65 to 0.95, and then arsenic alone or arsenic is added on top of it. An indium-antimony-arsenic compound semiconductor represented by the general formula % (X in the formula is a number less than 1 indicating the atomic ratio of arsenic) characterized by the simultaneous vapor deposition of arsenic and indium. A method for manufacturing a thin film is provided.

In the method of the present invention, indium (In) and antimony (sb) are first vapor-deposited onto a substrate.1 In the initial stage of vapor deposition, the arrival velocity ratio of both atoms is A B b/A□. is 1.0 or more, and the degree of vacuum P (T
It is important to perform deposition while maintaining the substrate temperature (absolute temperature) within a range of not less than the boundary substrate temperature (absolute temperature) Tc given as a function of Tc and not more than 30° C. higher than Tc. After the formation of InSb nuclei at the initial stage of vapor deposition in this InSb-based thin film formation stage, vapor deposition is performed by controlling the arrival speed ratio Asb/AXn of both atoms to the substrate to be smaller than 1.0, and the composition PC of antimony with respect to indium is controlled. (Feb/FIn) is 0.65 to 0.
It is necessary to form an InSb-based thin film within the range of 95, and furthermore, the high mobility I formed in this way
Arsenic (As) alone or As and In is deposited on the nSb-based thin film.
and the total number of atoms (F, n) in the In film or AS and the material to be deposited
By depositing As such that the sum of the number of atoms in the film (Feb) and the number of atoms reached by AS is greater than 1.0, it is possible to effectively produce a ■n5bl-xAsx thin film. .

The method of the present invention will be described in further technical detail below.

In the first half of the InSb-based thin film formation stage of the present invention, the substrate temperature T at the initial stage of vapor deposition is, for example, 5 x 10'-6To
When vapor deposition is performed under a vacuum of rr, the range is set to 670≦T<700 (0K), and at the same time Asb/Ar. Vapor deposition is started with the value of 1.0 or more. Then, when InSb nuclei of about 500 to 300 OA are formed, Asb/Arn is gradually lowered and vapor deposition is performed so that the final FSb/Fln becomes 0.65 to 0.95. InSb thus formed
The system composite crystal thin film consists of a large InSb crystal and a large In crystal, and has a power of 40,000-60,0OOcJ/V,
Indicates a high-mobility special order called S.

The substrate temperature Tc at the boundary that increases the substrate temperature at the initial stage of vapor deposition is closely related to the equilibrium vapor pressure of sb especially in the region of vacuum degree of 10' to 10-8 Torr. In fact, as long as the substrate temperature was set at a temperature higher than Tc, it was not possible to deposit sb on the substrate by vapor deposition. In this way, in the method of the present invention, sb that does not adhere to the substrate initially
exists, which means integration over time. The equality holds within experimental error when the initial Asb/At□ is close to 1.0. Therefore, since the intention of the present inventors in forming the InElb thin film type film is to form a thin film with F8b/Fln of 0.65-0.95, it is not necessarily the Asb/A process. It is not necessary to keep the integral value within this range. However, FBb/F engineering.

When considering the control including the above, it is preferable to operate so that the equal sign of the above equation (1) is satisfied.

Furthermore, in the present invention, the early stage of vapor deposition is the time period required for the growth of nSb crystals to form, and this corresponds to the time period from the start of vapor deposition until the film thickness reaches approximately 500 to 3000 A. However, it is difficult to clearly define the film thickness and time to be formed at this initial stage, depending on the final desired film thickness, initial vapor deposition conditions, overall vapor deposition time, and the like.

It is only during this initial stage of deposition that it is safe to deposit ASb/Al'n at a concentration of 1.0 or more. If the remaining time in the InSb-based thin film formation stage is 1.0 or more, Asb
When vapor deposition is performed using /Arn, only a thin film with poor crystallinity and low mobility or a crumbly film can be obtained. That is, in this time period, ARb/AIn is a ratio smaller than 1,
In particular, it is necessary to perform vapor deposition at an ultimate velocity ratio of 0.95 or less.

In the latter stage of In5b1-xARx formation in the present invention, As alone or As and In are simultaneously deposited.
is 0.39 or less, As alone is evaporated and X is 0.
．． When it exceeds 35, it is preferable to deposit As and In at the same time. Most of the crystals generated at this time are In5
bl, As, and the others are trace amounts of InAs and In. In this case,
[Determined almost automatically from lb/Fin.

Here, X is still equal to FAI/FX, and since excess As does not adhere to the substrate, FAs < Aa &, considering equation (B), Feb + AAI /Ftn > 1
, 0. It is necessary to deposit As so that , 0. As
Even in the case where In and In are simultaneously deposited, when the total number of In atoms in the film deposited in the InSb thin film formation stage, process n5bl, and As process stage is expressed by ΣFin, AAa > FAa = ΣFXn Fsb
It is necessary to evaporate As to an extent that it is outside of (III).

As is clear from this formula (IID), if As is deposited in sufficient excess, by controlling In and sb,
The composition of In5bl-XAsx can be easily controlled. However, formula II) holds true when F 8 b/F I n of the InSb thin film formed in the first half is 0.65-0.95, and this Feb/FX
When n is larger than 0.95, it becomes two-phase or InAs
This is not preferable as it may cause a lot of. Further, when it is smaller than 0.65, the film becomes uniform with many Hahin holes, which is not preferable.

The properties of the In5J and AsX thin films produced in this way are extremely excellent. For example, when X is 0.30, the hole mobility is 37,000 crl/V, s, and the resistance at 50°C is Temperature dependence is 0.9
5%/d, cracks on the order of og, trace amounts of InAS and In
There are virtually no significant effects on characteristics.

On the other hand, A11b/AIn is 1.0 at the initial stage of vapor deposition.
If it is set smaller than , there will be no problem with the state of the formed film, but it will no longer be possible to use In5b1°AsX with high mobility.
It is not possible to obtain thin films. Furthermore, if the evaporation starts at a temperature where the substrate temperature at the initial stage of evaporation is lower than the boundary substrate temperature Tc,
Not only will it result in a dull blue-colored film, but the properties will also deteriorate significantly, and if the temperature is too high above (i', c -1-30°C), the dispersion will become sharp, pinholes will increase, and the yield will decrease. This is not preferable because it lowers the temperature and is very disadvantageous industrially.

In the method of the present invention, there is no particular restriction on the substrate temperature during the deposition time period other than the initial stage, but it is preferable to perform the deposition while increasing the substrate temperature.

However, in the first half of the InSb-based thin film formation stage, InSb
It is lower than the melting point of 530℃, and the latter half is In5
Needless to say, it is necessary to set the melting point lower than the melting point of bl-XAsx (approximately 800° C., although it varies depending on X).

The degree of vacuum during vapor deposition was 1O-8 Tor, which is commonly used.
A degree of vacuum greater than or equal to r is used, but an appropriate degree of vacuum is selected in relation to the desired temperature of the substrate and in light of the relational expression with Tc. In that case, the temperature of the substrate at the boundary can be changed by introducing various gases into the evaporation system or by controlling the pumping speed and changing the degree of vacuum. In such a case, it is preferable to use, for example, nitrogen gas to set the desired degree of vacuum.

Furthermore, in the present invention, the first half of the InSb-based thin film formation stage and the second half of the In5bl-2Asz formation stage may be deposited continuously, or may be performed completely separately, for example, using separate vacuum evaporation equipment. good.

In the method of the present invention, the vapor deposition source is a single process n,
Although it is preferable to use Sb and As, compounds such as Sb, Garb, etc. may be used as the Sb source,
However, it is also possible to use compounds such as As, GaAl, and the like as the As source.

When using a compound as a vapor deposition raw material, whether it is sb or As, the single vapor pressure of the other metals forming the compound should be as small as possible than the vapor pressure of sb or As, considering the control of the atomic arrival velocity. Preference is given to using compounds with metals.

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.

As such a substrate, for example, Zaphire% Ca
F2. Na04s mica, glass, Cr-doped Ga
Examples include As. Particularly preferred are crystalline substrates.

The vapor-deposited thin film obtained by the method of the present invention can be formed to any thickness within a range that maintains the characteristics, depending on the use as a semiconductor device and its desired characteristics.
A range from 00 A to 10 μm is advantageously adopted industrially.

The means and devices for implementing the method of the present invention are not subject to any limitations as long as they do not depart from the technical concept of the present invention described above. For example, heating means such as heater heating or KB heating, or extremely conventional means such as flash vapor deposition may be used for vapor deposition, or MBE, ion beam method, etc. may also be applied.

Furthermore, the deposition rate of the thin film according to the method of the present invention can be in a wide range of, for example, 0.1 to 1000 A/sec, but from the viewpoint of ease of control of the attained rate ratio,
A film thickness formation rate of about 100 A/sec is preferable.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 As an apparatus, a vacuum evaporation apparatus was used, which could accommodate six sea urchins, had a substrate holder that rotated concentrically, and two boats. To control the substrate temperature, pt-Rd thermocouples were installed at three locations 10 mm above the wafer.
The temperature was controlled so that the difference between the maximum and minimum values of each displayed temperature was within 5°C.

The degree of vacuum was measured using a B-A gauge in the middle of the pipe from the Pelger to the exhaust system, immediately after the Mizuhiki pulp.

Mica was used as the substrate, and 6-H In and sb for semiconductors manufactured by Furuuchi Chemical Co., Ltd. were used as the raw materials.

The vacuum level was set to 5 x 10-' Torr (substrate temperature Tc at the boundary was 390°C), and the substrate temperature was set to 420°C.
It was set to Next, Asb/Ax. is 1 for the first 5 minutes only.
゜1, the remaining time is 0.63, In and sb
The power of each boat was controlled, and the deposition was carried out for 25 minutes without raising the substrate temperature until the film thickness reached 0.8 μm. The substrate temperature at this time was 500°C.

Next, while increasing the substrate temperature to 550°C, AAg/
AB was deposited for 5 minutes so that AAs+A8b was 0.35.

When the obtained thin film was examined by X-ray diffraction, the atomic ratio X of AB was 0.34, and only a trace amount of In and 1 nA could be detected.

When the characteristics of six wafers were measured using the rosette method, the mobility was 30,000 to 32,000 crl/V・S
Met. However, when we investigated the temperature dependence of the resistance of three of the films, we found that -0.95%/4eg at 50°C.
This was much smaller than -1.5%/deg for the In5b-based thin film.

Comparative Example 1 In the InSb thin film formation stage, A
Vapor deposition was carried out in the same manner as in Example 1, except that the power of the boat was controlled so that B b /A 1 was 0.66.

The obtained thin film had an As atomic ratio X of 0.34. The Hall mobility was 20,000-=21,500 d/V-8, and the temperature dependence of resistance was -0.94 coefficients/deg.

Example 2 The same substrate, raw materials, and equipment as in Example 1 were used. First, the degree of vacuum was set to 2 X-10-' Torr, and then 4-H nitrogen was introduced with a needle valve to 5 X
The needle pulp was fixed at 1 O"" Torr (TC: 414° C.). Next, set the substrate temperature to 430°C, and control the power of the two Bonitos so that A s b /A I 11 is 1.0 or more for the first 6 minutes and 0.84 for the remaining time. The film was deposited to a film thickness of 1.0 μm in 30 minutes while increasing the substrate temperature. The substrate temperature at that point was 510°C.

Next, while depositing a large amount of AB, the substrate temperature was increased to 550°C.
The total thickness of the SbAθ-based thin film was increased to 1.1 μm.

When the obtained thin film was examined by X# diffraction, it was found that x =
0.14, and some 1nAs and In were detected.

When we investigated the Hall mobility and ]loo (band gap at O' divided by the temperature dependence of the Hall coefficient) of this film, we found that they were 45,000 CJ/v-8, 0, and 45,000 CJ/v-8, respectively.
It was 21 eV.

Comparative Example 2 The same procedure as Example 2 was carried out except that the initial substrate temperature was 410°C.

The obtained thin film has x = 0.08 and nAs
were also detected slightly more frequently. Also, the color is dull in appearance, and the hole mobility is also poor. , 000CJ/V・S.

Comparative Example 3 In the InSb thin film formation stage, A was maintained during the entire vapor deposition period.
Vapor deposition was carried out in the same manner as in Example 2, except that the power of the boat was controlled so that s b /A I n was equal to or greater than i, o.

The X of the obtained thin film was so small that it could not be detected by X-ray diffraction, and AB was hardly contained in the crystal.

Comparative Example 4 Vapor deposition was performed under the same conditions as in Example 2 except that the initial substrate temperature was 450°C.

There were many transparent parts in the obtained thin film, and X = 0.2
1, the six films had a variation in adhesion charge of 80. When we measured the hole mobility of these six sheets, it was 16.300 ~
It was 32,500 c4/V'S.

Example 3 The substrate, raw materials, and equipment were the same as in Example 1, and the degree of vacuum was set to 8×1O−5 Torr (TO: 418° C.) using 4-N nitrogen. Next, the substrate temperature was set to 435°C, and A
e b /A I・ is 1.0 for the first 5 minutes and 0.0 for the remaining time.・Control the power of the boat so as to press 7, raise the board temperature to 515℃, and press 3.
It was deposited for 0 minutes. Then, the substrate temperature was increased to 570°C for 10 minutes.
A was vapor-deposited so that AAs/AAs''A8b was 0.5.

The obtained thin film had x = 0.30, had a blueish silver luster, and was recognized to be large crystals based on the way it reflected light.

When we investigated the temperature dependence of the hole mobility and resistance of this film at 50°C, we found that they were 37,000c4/V', respectively.
S, -0.95%/deg, and was an excellent material for magnetoelectric conversion elements.

Patent applicant: Asahi Kasei Industries, Ltd. Agent Akira Agata

Claims (1)

[Claims] 1. The arrival velocity ratio of antimony atoms to indium atoms at the initial stage of vapor deposition is 1.0 or more, and the substrate temperature (absolute temperature) T is expressed by the formula %. [Here, TC is the boundary substrate temperature ( (absolute temperature), P is the degree of vacuum during deposition (Torr)], and P is the degree of vacuum (Torr) during deposition. and antimony on the substrate, and then reduce the above-mentioned attained velocity ratio to less than 1.0 to form an indium-antimony based thin film with a composition ratio of antimony to indium (F8b/FIn) of 0.65 to 0.95. After that, arsenic alone or arsenic and indium are simultaneously vapor-deposited thereon, with the general formula % formula % (X in the formula is a number less than 1 indicating the atomic ratio of arsenic). A method for manufacturing the indium-antimony-arsenic compound semiconductor thin film described above.