JPS596527A - Manufacture of indium-antimony composite crystal thin film with high mobility - Google Patents

Abstract

PURPOSE:To form indium-antimony composite crystal thin film with high mobility by depositing indium and antimony on a substrate under the condition that the velosity ratio of In atom to Sb atom is less than 1.0 in the initial stage of evaporation and the temperature of the substrate is selected so as to be in a prescribed range. CONSTITUTION:''Initial stage of evaporation'' means nucleation process, which is the stage of nucleation until the thickness of film becomes about 500-3,000Angstrom from the beginning of evaporation. Formulas I and II are empirical formulas showing the relation between preset initial temperature and degree of vacuum when thin film with extreme high velocity. The formula I corresponds to the equilibrium evaporation temperature of Sb4 in the region of 10<-6>-10<-3>Torr in the degree of vacuum. The preset initial temperature of substrate is in the wide range because optimum preset temperature varies. It is during the time of nucleation process in the initial stage of evaporation that AIn/ASb should be less than 1.0 in relation to preset temperature, and during the time of grain growth process after that, a good result is obtained by depositing in the range of 1.1- 1.7 of AIn/ASb.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an indium-antimony (InSb) composite crystal thin film having excellent mobility.

In general, the mobility of ■nsb in a thin film of nnsb is 7 at room temperature.
Due to its large value of 8.000 cJ/VB, it is known to be an excellent material for Hall elements and magnetoresistive elements. Recently, there have been remarkable developments in Hall elements as position detection elements for direct drive motors, magnetoresistive elements as non-contact potentiometers, etc.

The present inventors have previously proposed a novel In5b-based composite crystal semiconductor that is excellent as a material for hall elements, magnetoresistive elements, etc., and a method for manufacturing the same.

The present invention further improves the method for manufacturing these InSb-based composite crystal semiconductor thin films, and provides an effective method for manufacturing thin films having significantly improved mobility.

In-8b is a well-known substance as a V-group compound semiconductor, and in order to be used as a Hall element or magnetoresistive element, it is necessary to combine the antimony element (S) of the indium element (In).
A crystal with an atomic ratio of 1.00 to b) has long been an essential condition, and it has been thought that the properties are highly exhibited in kamoai under such conditions, so many studies have been conducted based on this idea. It has been done.

However, the present inventors found that an excellent thin film could not be obtained only when the atomic ratio of In and sb was strictly controlled to 1:1, but also when there was an excess of stone, especially when the A new fact that cannot be predicted from the conventional technical concept is that if the ratio of Kenshi to 5bVc is in the range of 1.1 to 1.7, a composite crystal with excellent crystallinity and high mobility can be obtained. I found it.

Based on this new knowledge, an excellent InSb-based composite crystal thin film can be produced by increasing the arrival rate ratio (arrival rate ratio, hereinafter referred to as AIn/A) of In atoms to heavy atoms.
(abbreviated as sb) on a substrate under the conditions of 1.10-1.70, and furthermore, the substrate temperature at the initial stage of vapor deposition is determined by the formula 1 formula % [Here, T is the ultimate It was also found that the electrical characteristics can be improved by setting the temperature lower than the ultimate substrate temperature given by the substrate temperature (absolute temperature) P is the degree of vacuum (Torr) during deposition. .

The mobility of the thin film obtained by this method is 24.000C
If a higher mobility than that in the al direction is desired, it can be easily achieved by carrying out the vapor deposition in a nitrogen atmosphere.

However, the mobility of the thin film obtained even with this vapor deposition method under a nitrogen atmosphere is 30.000 when Fn/Feb (atomic ratio of total indium to antimony) is 1.4.
crl/', and the value was only about 40% of 1 nsb of the bulk.

The present inventors have conducted many experimental studies on how to obtain a high-mobility 1nSb thin film crystal, which is particularly useful as a material for magnetoresistive elements and Hall heads. I learned that the process can be roughly divided into a nucleation process and a grain growth process, and that the properties of InSb are greatly influenced by the previous crystal nucleation process.

Therefore, as a result of intensive research on the vapor deposition conditions, especially in the initial stage of vapor deposition, the present inventors found that AIn/
We have discovered that Asb and substrate temperature have an important correlation, and that when the specific range conditions of each are combined, an InSb composite crystal thin film with high mobility can be produced extremely effectively.Based on this knowledge, we have developed this book. This led to many inventions.

That is, the present invention provides an attainment velocity ratio of In atoms to sb atoms of 1.0 or less at the initial stage of vapor deposition, and a substrate temperature (
(Absolute temperature) T is expressed by the formula % Formula % [Here, TC is the boundary substrate temperature (absolute temperature), and P is the degree of vacuum (Torr) during vapor deposition. ], Tc≦T≦Tc +30
--- The present invention provides a method for producing a high-mobility InSb-based composite crystal thin film, characterized in that indium and antimony are deposited on a substrate under conditions selected to fall within the range of fll.

In the present invention, the initial stage of evaporation refers to the crystal nucleation process described above, and refers to the initial crystal nucleation stage from the start of evaporation until the film thickness reaches about 500 to 3000X. It is difficult to clearly define the thickness and time of the film formed at the initial stage of deposition, depending on the thickness, initial deposition conditions, overall deposition time, and the like.

The above formulas (11 and (ul) are experimental formulas that show the relationship between the initial setting temperature and the degree of vacuum when a thin film with extremely high mobility is obtained.Formula +1) is especially true when the degree of vacuum is 1O~10T.
This corresponds to the equilibrium evaporation temperature (Tv) of Sb4 at the head of orr. In fact, as long as the substrate temperature was set within this range, Sb could not be deposited on the substrate by vaporized NFC. This is confirmed by the thermal data of Stoll et al.
Elementso (Thermodynamic Prop
erties of the Filements
It is easy to understand 1c since it almost corresponds to the value obtained by A (S's6) ].

In addition, the initial set substrate temperature in the formula +Ill has a range because the optimum set temperature changes depending on factors such as the substrate temperature, the vacuum level monitor, the deposition rate, and the like.

In relation to this temperature setting, AI n/As at the initial stage of vapor deposition
It is important that b be 1.0 or less. The present inventors conducted numerous experiments and determined the control conditions for the boat of n and sb when obtaining a thin film with extremely high mobility.
In particular, repeated experiments in which the evaporation was stopped for several minutes at the beginning of the deposition and the atomic ratio AI n / As b up to that point were measured revealed that it is important that the artificial n / As b be less than 1.0. A conclusion has been reached.

In extreme cases, AIn/ASb was less than 0.5. However, the artificial n/ASb must be 1.0 or less only during the crystal nucleation process at the initial stage of vapor deposition, and also during the subsequent crystal grain growth process.
When vapor deposition was performed with AIn/ASb of 0 or less, only a thin film with poor crystallinity and low mobility or a ragged film was obtained. That is, during the time period corresponding to the grain growth process of the vapor deposition time, A/n/Asb is set to 1.
Good results were obtained when depositing in the range of 1 to 1.7. In particular, when AIn/ASb was evaporated at a ratio of 1.1 to 1.5, a thin film with extremely few pinholes was obtained.

Substrate temperature and AIn/ASb at the initial stage of vapor deposition
When the two conditions are met at the same time, the produced In5
The b-based composite crystal thin film grows so large that its crystals can be observed with the naked eye, and has high mobility characteristics. If the substrate temperature at the initial stage of deposition is lower than the substrate temperature at the boundary, large crystals will no longer grow or a pale film will be formed, and its mobility will be around 25,000 cdi/V, s, often 15,000 crl/v- It is less than or equal to θ.

If the initial substrate temperature is higher than the range of Equation [11], large crystals may be observed, but most of them are transparent films with many pinholes or white films, and their mobility is Wow, that's very low. Further, even when large crystals are observed, there are large variations in film thickness and mobility within a batch and within a film, making it difficult to adopt it industrially.

In the crystal nucleation process at the initial stage of vapor deposition in the method of the present invention, it is preferable to maintain the vapor deposition system in a vacuum system under a nitrogen atmosphere. This is because the presence of nitrogen is not only effective in forming better crystal nuclei, but also because the temperature of the substrate at the boundary of Equation 9 (1) cannot be adjusted by controlling the amount of nitrogen introduced.

Further, in the crystal grain growth process, it is preferable to perform vapor deposition while increasing the substrate temperature. The temperature at which crystals grow best is essentially unrelated to the substrate temperature at the boundary, and if the temperature is increased during deposition, a temperature gradient can be created within the substrate, which is extremely favorable for crystal growth. .

In the method of the present invention, the averaged AIn/As b and FIn/Fsb over the entire deposition period are A
Even if In /Asb is 1.0 or higher, they do not necessarily match at all points, and generally the relationship AIn /Asb <Fn/Fsb holds within experimental error. This is thought to be due to the fact that the plow alone does not adhere to the substrate above the boundary temperature.

However, even if it is made into a thin film with extremely high mobility,
The composite crystal is composed of an In, Sb compound crystal and a single In crystal, and the average atomic ratio F/F in the entire thin film is
It has been confirmed by X-rays and atomic absorption that Sb is in the range of 1.1 to 1.7, and there is no change as far as these requirements are concerned. The substrate used in the method of the present invention is Although there are no particular limitations on the material, it is preferably insulating and crystalline. Such materials include sapphire,
Examples include CaF2, Na11 and mica, which can be advantageously used as substrates in the method of the invention. However, mica is particularly preferable as a substrate, considering the need to have an open surface with minimal contamination and defects, and the complicated operations such as polishing and etching required to expose the surface. It's advantageous.

Moreover, it is extremely preferable to use In and sb of the rod body as the evaporation source for vapor deposition, but AIn and sb corresponding to the mounting ratio
/ As b, for example, ff1l for the boat.
By controlling J, you can use other items than just a single unit.

Therefore, for example, sb-containing compounds such as sb and garb can also be used as the sb source. Also In
, Ga has extremely low vapor pressure compared to sb,
These compounds can be fully utilized as sb sources.

1. Any method may be used to carry out the method of the present invention as long as it does not depart from the gist of the present invention.・Can also be used, for example, by conventional vapor deposition methods (heater heating, KB heating, etc.).

Flash evaporation, etc.), Ivy (Ivy, Ml), ion beam methods, etc. can be advantageously used.The thin film formation rate can be applied over a wide range, e.g. 11-1 When considering the industrial value, including the quality of the product and the overall quality of the product.
g A / sec is particularly preferable. The thin film produced in this way is usually 1000λ to 10μ, but considering the characteristics and workability, if it is rinsed too much, the sensitivity will decrease, and if it is too thin, it will move. This is not preferable because it lowers the degree of oxidation.

According to the method of the present invention, for example, 40.000 to 60,
InS with extremely high mobility of 000 cJ/V, s
A b-based composite crystal thin film can be easily obtained. Such a high-mobility thin film is particularly excellent as a material for magnetoelectric conversion elements, and can be widely used as a material for not only Hall elements but also magnetoresistive elements and Hall heads.

In the method of the present invention, it is only necessary to satisfy a specific combination of conditions particularly in the crystal nucleation stage at the initial stage of vapor deposition, and the operation is simple.
It is industrially advantageous and has excellent practicality.

The present invention will be explained in more detail with reference to Examples below.

The electrical properties of the thin films in each example were measured by the para method under conditions of an input pressure of 1 V and an applied magnetic field of 500 Gaus per day.

In addition, Fn/Feb of the thin film was determined by dissolving a predetermined amount of the thin film in dilute nitric acid according to the wet analysis method using atomic absorption, and using the atomic absorption spectrometer (AA-646 manufactured by Takasu Seisakusho) to analyze the In and It was determined by measuring the absorbance of sb.

Example 1 As an apparatus, a vacuum evaporation apparatus was used which could accommodate six wafers, had a substrate holder that rotated concentrically, and two ports. The substrate temperature was controlled by providing three Pt-Rd mocouples at positions 10+ nm above the wafer so that the difference between the maximum and minimum values of each display temperature was within 5°C. The degree of vacuum was measured using a BA gauge in the middle of the pipe leading from the Pelger to the exhaust system, immediately after the Honkawa valve.

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

First, the degree of vacuum is set to 1.5X 10 Torr (substrate temperature Tc at the boundary is 387.7°C), and the substrate temperature is set to 395
It was set at ℃. Next, the artificial n/ASb was set to 0.9 for the first 8 minutes and 1.40 for the remaining time.
By controlling the powers of the and sb ports, the film was deposited for 40 minutes at VC1 to a film thickness of 1.2 μm without raising the substrate temperature. The final substrate temperature in this case is 50
It was 0°C. After vapor deposition, the average AIn/Asb over the entire vapor deposition time period was calculated from the combination of In and sb, and was found to be 1.37.

When the characteristics of six wafers were measured, the electrical conductivity was 150-1600m and the Hall coefficient was 330-390.
ct/l/O, mobility 49,200-55.700
It was cJ/V,s.

This film had a whitish silver luster, and many island-like particles of several tens of microns were observed on the surface, and crystals were also observed with the naked eye due to the anisotropy of the luster.

Furthermore, when this film was analyzed by atomic absorption, it was found that FI
n/Fs b is 1.36 to 1.42, and X
According to line diffraction, the thin film was composed of In crystals and In crystals.

Comparative Example 1 AIn/Asb force 1.3 in the entire deposition time range
The procedure was the same as in Example 1 except that the power of the boat was controlled so that the power was 0. No large crystals were observed in the obtained thin film, and the mobility was 19,700 to 22,000 cJ.
/V,s. Further, when this film was subjected to atomic absorption analysis, the Fn/Fsb was 1.27 to 1.34.

Comparative Example 2 The substrate temperature at the initial stage of evaporation was set to 380° lower than the boundary substrate temperature.
The same procedure as in Example 1 was carried out except that C was used. Average A engineering n
/ASb is 1.31, and 1 (1
The engineering n/FSb was 1.25 to 1.34. This film has a slightly bluish tinge and a mobility of 14,800-16
．． 200crA2/v・Nippon ivy.

Example 2 The same substrate, raw materials, and equipment as in Example 1 were used. First, the true degree is 2 x 10 Torr (Tc is 38
9.7℃), then introduced p4-H nitrogen through a needle valve to 5X10 Torr and heated to 21 Dorno (
fixed loop. Next, set the substrate temperature to 420℃, and
Two boat power controls were carried out so that n/Asb was 1.0 or less for the first 6 minutes and 1.30 for the remaining time, and the substrate temperature was completely raised.
Vapor deposition was performed using 1, which resulted in a film thickness of 1.0 μm in 0 minutes. The final substrate temperature was 510°C. Also, the average artificial n/
Asb was 1.23.

The electrical characteristics of four parts of one wafer are measured,
When data from a total of 24 points were compiled, the Hall coefficient was 42.
0±40 ctl/C% mobility is 57,500±3
*000 cJ/v=Teatu fc.

This film consisted of a silver luster part and a silver luster part, and the crystals had grown to such an extent that they could be observed with the naked eye.

In addition, when X-ray diffraction was performed, ■nsb (111)
Strong diffraction lines of In(101) and In(101) were observed, and the Laue pattern was very simple and rare. Furthermore, when FIn/Fs b was determined by atomic absorption spectrometry, it was found to be 1.24 to 1.
．． It was 33.

Example 3 The same procedure as Example 2 was carried out except that A/Asb was controlled to be 0.5 for the first 6 minutes, 1.0 for the next 4 minutes, and 1.25 for the remaining 20 minutes. . When the average AI n/As b was calculated from the product of actual In and 8b, it was 0.85.

Crystals can be seen in these films, and their characteristics include a Hall coefficient of 3.
40-420 crl/O, mobility 38.500-
It was 44,700c, 1/2, V-8.

Furthermore, when F engineering n/FSb was measured, it was 1.24~
1.36, which was much larger than the average AIn/ASI).

Comparative Example 3 The same procedure as Example 3 was carried out except that the initial substrate temperature was 400°C. The average A/Asb was 0.88, and the resulting film had a bluish color.

When the FIn/Fsb and mobility of this film were measured, they were 1.00-1.02.4,500-7.2, respectively.
00CFI/v・8.

Comparative Example 4 Vapor deposition was carried out in the same manner as in Example 3, except that the initial substrate temperature was 445°C. The average AIH/Asb was 82, but the resulting film had crystalline and transparent parts. There were also many pinholes in the crystal part, and the film thickness varied by more than 10 inches.

When the FIn/Fsb and mobility of the crystalline part of this film were measured, they were 1.43-1.59 and 18.0, respectively.
00 to 33.600 crl/V-e, and there was a large variation.Example 4 The substrate, raw materials, and equipment were the same as in Example fl11, and the degree of vacuum was fi = 8 × 10 Torr (T
c was 412°C). Next, the substrate temperature was set to 425°C,
AI n / As b is less than 1.0 for the first 5 minutes,
For the remaining time, the power of the boat was controlled so that the thickness was 1.45, and the deposition was carried out in 30 minutes until the thickness was 0.9 μm while increasing the substrate temperature. The final board temperature is 51
At 0 °C, the average AIn/Asb was 1.38.

The six wafers had very uniform crystals, and the F-factor n/FSb was 1.36 to 1.46. Hall coefficient 350-430 CrI/C1 mobility 48,700
~56.600 crl/V'B.

Patent Applicant Asahi Kasei Industries Co., Ltd. Agent A Formation Amendment 1.4S (Indication of q, Patent Application No. 116542 116542 z, qB+1') Name m Manufacture of high mobility indium-antimony based composite crystal thin film Method 3 Relationship with the case of the person making the amendment Patent Applicant Address: 4th Representative, Dojimahama 1-2-6, Kita-ku, Osaka-shi, Osaka Address: 5th floor, 7th floor, Tsuchiya Building, 6-4-5, Ginza, Chuo-ku, Tokyo 104 Subject of amendment Column 8 of the detailed explanation of the invention in the specification, Contents of amendment (1) Change the ``atomic ratio'' in the 13th line of page 7 of the specification to ``
Corrected to ``Atomic Arrival Velocity Ratio.''

(2) “Also the crystal grain growth process” on page 7, line 19
Wow, I'll correct it to "the time for the grain growth process."

(3) On page 9, lines 4 and 5, "to maintain the evaporation system..." has been corrected to "to maintain the vacuum system in a nitrogen atmosphere."

(4) In the 8th line of page 9, ``Because I can't'' will be corrected to ``Because I can.''

(5) On page 9, lines 11 to 14, "Boundary substrate temperature... is very convenient." was changed to "Because it is higher than the boundary substrate temperature, it would be better to raise the substrate temperature for crystal growth." It is favorable for growth.''

(6) “(TC
is 389.7°C)" and delete all "Torr" on the 16th line.
After J, "(TC is 414 degrees Celsius)" will all be added.

(7) Change “412℃” in the 6th line of page 18 to “4
Corrected to 18℃.

Claims (1)

[Claims] 1. The arrival velocity ratio of indium atoms to antimony atoms at the initial stage of vapor deposition is 1.0 or less, and the substrate temperature (absolute temperature) T is expressed by the formula %. [Here, TC is the boundary substrate temperature ( Indium and antimony under conditions selected to be in the range Tc≦T≦Tc+30, where 1. A method for producing a high-mobility indium-antimony composite crystal thin film, characterized by e. depositing and on a substrate. 2. The method according to claim 1, wherein the average atomic ratio of indium atoms to antimony atoms in the entire crystal thin film is in the range of 1.1 to 1.7.