JPH0113212B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an indium antimony-based composite crystal semiconductor, and more specifically, to a method for manufacturing an indium antimony-based composite crystal semiconductor having improved electrical properties, which is composed of an indium antimony compound crystal and an indium single crystal. Indium antimony (hereinafter abbreviated as InSb)
Compound crystalline thin films have extremely high mobility and far superior magnetoelectric conversion efficiency compared to other compound semiconductors, such as indium arsenide and potassium arsenide, so they are suitable as materials for Hall elements and magnetoresistive elements. It is known that there is. Recently, it has also gained attention in the electronics industry, especially as a position detection device for direct drive motors, and as a component for VTRs and audio equipment. InSb is a well-known substance as a - group compound semiconductor, and in order to be used as a Hall element or magnetoresistive element, the atomic ratio of indium element (In) to antimony element (Sb) is required.
1.00 crystal is an essential condition, and it has been thought that the properties are highly exhibited under such conditions, and many studies have been conducted based on this idea. For example, when considering the Hall effect, the Hall coefficient R _H and the Hall mobility μ _H are important parameters. Here, as shown in the pattern in Figure 1,
The InSb thin film was patterned and electrodes were attached as a measurement sample, and gold-plated electrodes a,
A′ is provided as an input electrode, electrodes b and b′ are provided as output electrodes, the voltage generated between the output electrodes when the input electrode is connected to a constant current power source I is V _Hi , and the input electrode is connected to a constant voltage power source V. If the voltage generated between the output electrodes at this time is V _Hv , V _Hi and V _Hv are given by the following equations. However, in Fig. 1, l is the length of the pattern, W is the width of the pattern, and t in the formula
is the film thickness of the sample. V _Hi = R _H BI/t・f (1) V _Hv = μ _H BV・W/l・f (2) In the above equations (1) and (2), B is the magnetic flux density of the applied external magnetic field, I is the current applied to the sample, V is the voltage applied to the sample, and f is the shape factor of the sample.
Further, R _H is the Hall coefficient of the sample, and μ _H is the Hall mobility of the sample. As can be seen from equation (1), the output voltage is inversely proportional to the thickness of the material through which the current flows, and it is better to use thin films when creating highly sensitive Hall elements and magnetoresistive elements. it is obvious. However, the present inventors have discovered that excellent devices are not obtained only when the atomic ratio of In and Sb is strictly controlled to 1:1, but also when In is in excess, especially when the Sb of In We found and proposed a new fact that could not have been predicted from conventional technical concepts: a composite crystal with excellent crystallinity and high mobility can be obtained if the atomic ratio is in the range of 1.1 to 1.7. The superior InSb-based composite crystal thin film based on this new knowledge is
In and Sb are the arrival speed ratio of Sb to In (arrival rate ratio, abbreviated as AIn/ASb)
can be produced by vapor deposition on a substrate under conditions of 1:1.1 to 1:1.7, and substantially
Obtained as a composite crystal consisting of InSb compound crystal and In single crystal. This manufacturing is similar to conventional AIn/ASb
It is industrially much easier to produce than InSb compound crystals with a value of 1.00, and is superior in that thin films with very little variation in composition and properties can be easily controlled and produced. Conventionally, it has been thought that the essential condition for compound semiconductors such as InSb is that the atomic ratio of group B elements and group Vb elements in the periodic table be 1:1 as described above. A method for producing InSb compound crystals was proposed based on this basic concept. For example, as a relatively simple method, Mr. KGGunther (KGGunther)
There is a so-called three-temperature method proposed by (U.S. Pat. No. 3,172,778). This three temperature method
By adjusting AIn/ASb to 1.0 or less and raising the substrate temperature higher than the decomposition temperature of InSb,
This is convenient for forming a compound crystal thin film with an atomic ratio of In and Sb of 1:1. However, AIn/ASb, which was proposed earlier by the present inventors,
In the method of manufacturing an InSb compound composite crystal semiconductor by keeping the temperature within the range of 1.1 to 1.7, the method of setting the substrate temperature higher than the decomposition temperature in the three-temperature method described above is essentially inapplicable due to excess In. I learned. If the substrate temperature is set higher than the decomposition temperature of the InSb compound semiconductor and the deposition is forced under the condition of AIn/ASb of 1.1 to 1.7, only a matte, non-uniform, and porous film will be obtained, which is especially important. Only films with a mobility of 10,000 cm ² /Vsec or less can be obtained. Based on the above findings, the present inventors conducted further research on an improved manufacturing method for the previously proposed InSb composite crystal semiconductor that exhibits particularly improved mobility. Relatedly, we have found that an excellent composite crystal semiconductor with higher mobility can be obtained when the temperature of the substrate is set under certain conditions. That is, in the present invention, when depositing In and Sb under conditions where the attained velocity ratio of Sb to In (AIn/ASb) is 1:1.1 to 1:1.7, the substrate temperature at the initial stage of deposition is determined by the following formula; 1/T=9.98×10 ^-4 −5.66×10 ^-5 IogP (3) [Here, T is the ultimate substrate temperature (absolute temperature),
P is the degree of vacuum during deposition (Torr)] Provides a method for manufacturing an InSb composite crystal semiconductor consisting of an InSb compound crystal and an In single crystal, characterized in that the temperature is set lower than the ultimate substrate temperature given by do. The ultimate substrate temperature T given by the above formula (3) corresponds to the decomposition temperature of the InSb compound crystal, as described later, and in reality, the set temperature at the initial stage of vapor deposition is
It has also been found that it is desirable to set the temperature at least 20°C lower than this decomposition temperature. However, the substrate temperature set at the initial stage of vapor deposition must be controlled to a temperature lower than the upper limit of about 530° C., which is the MP of InSb, although the temperature rises during thin film formation. In consideration of the strain and brittleness of the resulting thin film, it is preferable for such control to be a continuous and uniform rate increase. In the method of the present invention, the ultimate substrate temperature is a temperature that depends on the degree of vacuum, as given by the above equation (3), and is a temperature that depends on the degree of vacuum (In
This is the temperature at which the amount of Sb attached to the substrate per unit area rapidly decreases. Therefore, it can be defined as the substrate temperature at which the value of adhesion amount/flying amount suddenly decreases at a certain degree of vacuum. The present inventors investigated the relationship between the extreme substrate temperature and the degree of vacuum and obtained the results shown in FIG. 2. In Figure 2, the vertical axis shows the pressure (10gP) and the horizontal axis shows the reciprocal of the substrate temperature, and 1 in the figure is based on equation (3).
The theoretical decomposition lines 2, 2', and 2'' given by are the points obtained in experiments with varying degrees of vacuum, and it is clear at first glance that each of these experimental points is almost on the theoretical decomposition line. .This experimental point is the InSb of Richter et al.
Thermal data [Trans.Metallurgical SOC.AIAE 24 5,
99'69)] and the thermal data of the elements by Stoll et al. [Thermodynamic Properties of the Elements]
It was found that the curve matches well with the theoretical curve of the decomposition pressure of InSb (approximated to Equation (3)) calculated using Elements ACS'56)]. That is, when the degree of vacuum during vapor deposition is fixed, the ultimate substrate temperature approximately corresponds to the decomposition temperature. In the method of the present invention, In and Sb are deposited under conditions such that the attained speed ratio of In to Sb is 1.1 to 1.7, and the preferable speed ratio is 1.2 to 1.5. In addition, as the evaporation source for vapor deposition, single In and
Although it is extremely preferable to use Sb, the power to the boat may be controlled so that AIn/ASb, which corresponds to the ratio of flight distance, is 1.1 to 1.7. Therefore, for example, Sb-containing compounds such as InSb and GaSb can also be used as the Sb source. Furthermore, since In and Ga have extremely low vapor pressures compared to Sb, these compounds can be fully utilized as Sb sources. Further, the substrate used in the method of the present invention is not particularly limited in terms of material, but it is preferably insulating and crystalline. Such materials include sapphire, CaF ₂ , NaCl, mica and semi-insulating GaAs doped with Cr or Cr--O, which can be advantageously used as substrates in the method of the invention. However, considering the need to produce cleavage planes with less contamination and defects and the complicated operations such as polishing and etching required to produce such planes, mica is particularly preferable as a substrate, and is extremely advantageous from an industrial perspective. It is. Any method can 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, such as ordinary vapor deposition methods (heater heating, EB heating, flash vapor deposition, etc.), sputtering, MBE, and ion beam methods. etc. can be used to advantage. In addition, a wide range of thin film formation speeds, for example 0.1 to 1000 Å/sec, can be applied, but when considering the industrial value including ease of control of AIn/ASb and product quality,
~10 Å/sec is particularly preferred. The present invention will be explained in more detail below using specific examples. Example 1 Mica was used as a substrate, and a vacuum evaporation apparatus was used, which had a concentrically rotating substrate holder on which six wafers could be placed. The substrate temperature was sensed by a Pt--Rd thermocouple placed 10 m/m above the wafer, and another thermocouple was placed on the control. Since the detected substrate temperature differs from the actual substrate temperature, it was corrected for the case of no rotation. The substrate temperature referred to in the present invention is such a corrected substrate temperature. Both In and Sb used as raw materials were 6-N manufactured by Furuuchi Chemical Co., Ltd. The degree of vacuum is 1×10 ^-6 Torr, and the substrate temperature is 380℃.
and set In and Sb so that AIn/ASb is 1.45.
was removed, and a deposited film with a thickness of 1.1μ was obtained in 30 minutes. During the deposition, the substrate temperature was raised to 460°C. When we patterned six wafers as shown in Figure 1 and measured their characteristics, we found that the mobility was 22,500 ~
24000cm ² /Vsec, and the Hall coefficient is 380-400
It was as high as cm ³ /C. All films were also very shiny. Example 2 Example 1 except that the substrate temperature was kept constant at 420°C.
When deposited in the same manner as above, the mobility was 16,000 to 18,000
cm ² /Vsec, and the Hall coefficient is 270 to 280 cm ³ /C.
It was hot. Comparative Example 1 The substrate temperature was set at 480° C., which exceeds the ultimate substrate temperature, and the other operations were the same as in Example 1. The resulting film had an average mobility of 3000 cm ² /Vsec and a Hall coefficient of 230 to 250 cm ³ /C. Further, in this case, the film was matte and the unbalanced voltage was large. Examples 3 to 5 In Example 1, the attained speed ratio AIn/ASb is
Mobility was measured for those obtained when the values were set to 1.15, 1.3, and 1.6. The results are shown in the table below.

[Table] Comparative Example 2 In Example 1, when AIn/ASb is 0.9 and 1.8, the mobility is smaller than 10000cm ² /Vsec, and the average is 6000cm ² /V・sec and 3000cm ² /Vsec, respectively.
It was hot at Vsec. Moreover, when AIn/ASb is 0.9, the unbalanced voltage of the obtained film is large, and AIn/ASb
When the film was 1.8, the resulting film was non-uniform and had many holes. Example 6 Start with a substrate temperature of 380°C and increase the final temperature to 500°C.
℃, and vapor deposition was carried out in the same manner as in Example 1 except for the following.
The mobility varies up and down by about 1000cm ² /V・sec,
AIn/ almost similar to Examples 1 and 3-5.
A trend toward ASb was obtained. Examples 7 to 10 For the case of AIn/ASb=1.45, the initial substrate temperature was set to 400℃, 420℃, 440℃ or 470℃, respectively.
, set the final temperature to 480℃, and set the vacuum level to 8.
Vapor deposition was carried out at ×10 ⁻⁷ Torr in accordance with Example 1 except that the results shown in the table below were obtained.

[Table] Examples 11 to 14 The average substrate temperature of Examples 7 to 10, that is, the results obtained when the experiments were carried out while being kept constant at 440°C, 450°C, 460°C, or 475°C, are shown in the table below.

[Table] Example 15 AIn/ASb is 1.5, the initial substrate temperature is set to 380℃, the deposition is continued for 10 minutes, and the next minute is 380℃.
Raise the temperature to 420℃ and keep it at this temperature for 10 minutes, then increase the temperature to 460℃ for 1 minute and keep it for 10 minutes.
A stepwise substrate temperature increase method was used in which the substrate was held at this temperature for minutes. The degree of vacuum was 1×10 ^-6 Torr.
The mobility of the six membranes obtained is 18,000 to 22,000 cm ² /
The Hall coefficient was 330 to 380 cm ³ /C at V.S.
This film had somewhat lower gloss than the film obtained in Example 1.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a pattern for measuring electrical characteristics, and FIG. 2 is a graph showing the relationship between the vacuum degree of the system during vapor deposition and the ultimate substrate temperature. In the figure, a and a' are input electrodes, b and b' are output electrodes, 1 is a theoretical decomposition line, and 2, 2', and 2'' are actual measurement points.

Claims (1)

[Claims] 1. When depositing indium and antimony under conditions such that the arrival speed ratio of antimony to indium on the substrate is 1:1.1 to 1:1.7,
The substrate temperature at the initial stage of vapor deposition is expressed by the formula 1/T=9.98×10 ^-4 −5.66×10 ^-5 logP [Here, T is the ultimate substrate temperature (absolute temperature),
P is the degree of vacuum during vapor deposition (Torr)] A method for manufacturing an indium-antimony composite crystal semiconductor consisting of an indium-antimony compound crystal and an indium elemental crystal, characterized by setting the temperature to be lower than the ultimate substrate temperature given by .