JPH0774102A - Method of manufacturing compound semiconductor - Google Patents

Abstract

PURPOSE:To clean and flatten a substrate surface by adjusting the substrate temperature, processing time and group V molecular beam pressure on the substrate surface to specific conditions. CONSTITUTION:In the substrate cleaning process. When the group V molecular beam pressure is P1 and the molecular beam pressure at the growth of a crystal is P2, the group V molecular beam of which the pressure P1 is kept as P1<=(P2X1/2) is applied to the substrate surface. For example, the pressure of an As molecular beam that is emitted from a molecular beam source cell is set to be 10<-6>Torr and the beam is applied to the substrate surface to raise the temperature of the substrate at a rate of 30 deg.C/min. When the temperature of an InP substrate surface reaches 440 deg.C, the rise of the temperature is stopped and the temperature is held for 2 minutes. In the crystal growth process, the As molecular beam pressure is increased to 2X10<-5>Torr and when the pressure reaches a predetermined As molecular beam pressure, the shutters of other two molecular beam source are opened to irradiate the substrate surface with the As molecular beam, an In molecular beam and an Al molecular beam, and InAlAs crystal is deposited on the substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a compound semiconductor through a molecular beam epitaxy method (MBE method).

[0002]

2. Description of the Related Art Molecular beam epitaxy (MBE) is one of the methods for producing compound semiconductors.
The pitaxy method is widely used. As is well known, MB
The E method is a method in which the constituent atoms of the semiconductor crystal to be grown reach the substrate as molecular beams. When using the MBE method, it is possible to control the composition of an extremely thin single crystal thin film and grow it in situ. In particular, when multiple molecular beams are simultaneously supplied onto the substrate and their intensities are independently controlled, crystal growth can be performed in atomic layer units, and semiconductor crystals with uniform and precise composition can be obtained. It is advantageous in forming a conversion device. By the way, InAlAs, InGaAs, I
Quantization devices in which semiconductor crystals such as nGaAlAs are formed on a Group 3-5 substrate are expected to be used for semiconductor laser devices, photodetectors, high-speed transistors, and the like.

In the MBE method, when a high-quality semiconductor crystal is stably grown on a Group III-V substrate, transients of molecular beam intensity are reduced and As pressure is stabilized by controlling back pressure. Cleaning the substrate surface in a vacuum atmosphere is also important. Therefore, in the MBE method, a substrate cleaning process for removing impurities adhering to the substrate surface in advance is taken.

In the above-mentioned substrate cleaning step, the substrate is generally heated in order to remove impurities on the surface of the substrate. In such heat treatment, the Group V component having a high vapor pressure is released from the substrate. Therefore, a good substrate surface suitable for crystal growth may not be obtained.

As a measure for preventing the separation of the Group V component, MB
Among the molecular beams used in the crystal growth step of the E method, the surface temperature of the substrate is raised while irradiating the surface of the substrate with a group 5 molecular beam that does not cause substantial deposition by itself. For example, in the case of MBE method using InP substrate,
In order to prevent the release of P, the surface temperature of the substrate is raised while irradiating the As molecular beam.

[0006]

The parameters for cleaning the substrate in the MBE method are the substrate temperature, the processing time, and the pressure of the Group 5 molecular beam on the substrate surface. If these parameters are not set properly, it will not be possible to form a flat and well-cleaned substrate surface, which impairs reproducibility in producing high quality crystals. However, in the measures for preventing the group V component separation described above, no technical study has been made on the pressure of the group 5 molecular beam irradiating the substrate surface. Since the pressure is set to be equal to the pressure of the group 5 molecular beam in the growth step, a substrate surface suitable for crystal growth cannot be obtained.

Japanese Patent Laid-Open Publication No. 4-274315 can be seen as a technical document for examining the pressure of the group 5 molecular beam in the substrate cleaning step. The invention described in this document is InP
A used to prevent the separation of P in the substrate cleaning process
s molecular beam is applied at a pressure (2 × 10 ⁻⁵ Tor) suitable for crystal growth.
r) to maintain a higher pressure (4 × 10 ⁻⁵ Torr) to enhance the P separation prevention effect, and to raise the temperature of the substrate (540 to 595
C) to clean the substrate surface. Further, in the subsequent crystal growth step, the As molecular beam pressure is lowered to a pressure suitable for crystal growth (2 × 10 ⁻⁵ Torr) to start crystal growth. However, according to this known technique, as pointed out in the following documents, the substrate is exposed to a high temperature, so that the damage of the substrate becomes large, and in addition to this, crystal components are present at the interface between the substrate and the crystal. Since a buffer layer having a different ratio is generated, a steep potential barrier is not formed, and the electrical characteristics of the crystal deteriorate. Reference: C. Giannini et. Al, Appl. Phys. Lett. 62, pp
149, 1993

In addition, Japanese Patent Laid-Open No. 60-58613,
Japanese Unexamined Patent Publication No. 4-122731 discloses irradiating a small amount of a Group III atom on the oxide film as a method for changing the oxide composition forming the oxide film to an oxide composition that is easily released at low temperature. There is. These methods are effective as low-temperature desorption methods for oxide films. However, when an oxide deposited in a polycrystalline state is irradiated with Group 3 atoms, for example, In atoms are irregularly deposited. In addition, if the surface of the substrate upon irradiation with the Group III atoms is the Group III surface, the flatness of the surface of the substrate is impaired.

[Object of the Invention] In view of these technical problems existing in the existing molecular beam epitaxy method (MBE method), the present invention can clean and flatten the substrate surface to a higher degree, An object of the present invention is to provide a method for producing a compound semiconductor in which impurities are not present at the interface between a crystal growth layer and a crystal growth layer, that is, a method capable of producing a high quality compound semiconductor with good reproducibility.

[0010]

In order to achieve the intended purpose, the method of manufacturing a compound semiconductor according to claim 1 of the present invention provides a surface of a substrate made of a compound of Group 3-5 in a high vacuum atmosphere. Substrate cleaning process for cleaning the substrate surface by molecular beam irradiation while heat-treating, and irradiating the cleaned substrate surface with multiple molecular beams consisting of the constituent atoms of semiconductor crystals in a high vacuum atmosphere And a crystal growth step for depositing and growing a semiconductor crystal on the substrate surface, and when the substrate surface is heat-treated in the substrate cleaning step, a Group III stabilizing surface appears on the substrate surface. Until the surface temperature of the substrate is increased, and when the substrate surface is subjected to molecular beam irradiation treatment in the substrate cleaning step,
Of the molecular beams used in the crystal growth process, a group 5 molecular beam that does not cause substantial deposition on the substrate surface by itself is used.
Further, when the pressure of the group 5 molecular beam is P ₁ and the molecular beam pressure during crystal growth is P ₂ , the group 5 molecular beam held at a pressure of P ₁ ≦ (P ₂ × 1/2) Is irradiated onto the substrate surface. Irradiation of the Group 5 molecular beam onto the substrate surface in the above may be started when the substrate is at room temperature,
It suffices to start when the Group V component leaves the substrate. By the way, in the case of the InP substrate, since P does not dissociate up to a substrate temperature of about 200 ° C. under high vacuum, irradiation of the Group 5 molecular beam may be performed when the substrate temperature reaches about 200 ° C. Irradiation with this Group 5 molecular beam is described below.
The same applies to the substrate cleaning steps according to 4 above.

In the method for producing a compound semiconductor according to a second aspect of the present invention, in the substrate cleaning step, the surface temperature of the substrate is T ₁ , and the transition temperature T _{2 between the} Group 5 stabilization surface and the Group III stabilization surface is T _2. In the case of, after the Group III stabilizing surface appears on the substrate surface,
The substrate surface temperature is maintained at T ₂ ≦ T ₁ ≦ (T ₂ + 50 ° C.) while irradiating the substrate surface with the Group 5 molecular beam.

According to a third aspect of the present invention, there is provided a method of manufacturing a compound semiconductor, wherein in the substrate cleaning step using an InP substrate, As atoms kept at a pressure of 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ Torr. While irradiating the substrate surface with a molecular beam containing, the surface temperature of the substrate is raised until a Group III stabilizing surface appears on the substrate surface. In this case, the molecular beam containing the As atom is
More preferably, the pressure is maintained at 1 × 10 ⁻⁶ to 1 × 10 ⁻⁷ Torr.

In the method for producing a compound semiconductor according to a fourth aspect of the present invention, after the Group III stabilizing surface appears on the substrate surface in the substrate cleaning step, 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ To is obtained.
While irradiating the substrate surface with a molecular beam containing As atoms held at a pressure of rr, the surface temperature of the substrate is T ₂ ≦ T ₁ ≦ (T ₂
Hold at + 50 ° C).

In order to achieve the intended purpose, the method for producing a compound semiconductor according to claim 5 of the present invention comprises heating the surface of a substrate made of a compound of Group 3-5 in a high-vacuum atmosphere while heating the molecule. Substrate cleaning process to clean the substrate surface by beam irradiation, and to irradiate the cleaned substrate surface with a plurality of molecular beams composed of the constituent atoms of the semiconductor crystal in a high vacuum atmosphere so that the substrate surface A crystal growth step for depositing and growing a semiconductor crystal; and, in the substrate cleaning step, a Group V stabilization surface appears on the substrate surface and then a Group III stabilization surface appears. Before, the surface of the substrate is irradiated with the molecular beam of the group III atoms constituting the substrate. The irradiation time of the Group III molecular beam in this case is, for example, about 1 to several seconds.

In a method of manufacturing a compound semiconductor according to a sixth aspect of the present invention, in a substrate cleaning process using an InP substrate, while increasing the surface temperature of the substrate until a Group 5 stabilizing surface appears on the substrate surface, 1 × 10 ^-5 to 1 × 10 ^-7 Tor
Irradiating the substrate surface with a molecular beam containing As atoms held at the pressure of r, and after the appearance of the Group 5 stabilizing surface on the substrate surface and before the appearance of the Group 3 stabilizing surface, I
The surface of the substrate is irradiated with a molecular beam containing n atoms.

[0016]

The present inventors have conducted a molecular beam epitaxy method (MBE
Method) to produce a compound semiconductor, the present invention has been achieved through repeated studies and repeated experiments. That is, in the present invention, out of the following technical matters obtained from research and experiments relating to the MBE method, harmful matters and undesirable matters are excluded, only effective matters are extracted, and these effective matters are technically summarized. It is a thing. (1) In the substrate cleaning process, it is effective to irradiate the surface of the substrate with a group 5 molecular beam of the same type as or different from the group 5 atoms in the substrate in order to prevent the group 5 components from separating from the substrate. However, if the group 5 molecular beam pressure P ₁ is increased at this time,
A transition layer is easily formed at the interface between the substrate and the crystal. (2) In the substrate cleaning process, when the Group III stabilizing surface appears on the substrate surface, impurities are quickly removed from the substrate surface, but the Group V stabilizing surface appears on the substrate surface. In this state, the removal rate of impurities on the substrate surface is significantly reduced. (3) When the group 5 molecular beam pressure P ₁ is increased during the substrate cleaning process, the substrate temperature T ₁ for causing the group III stabilizing surface to appear on the substrate surface becomes higher, and the substrate is significantly damaged by heat. Become. (4) When the substrate temperature T ₁ exceeds the 5-3 transition temperature (transition temperature from the Group 5 stabilization surface to the Group 3 stabilization surface) T ₂ + 50 ° C., it is due to the release of the Group 5 component from the substrate. The substrate damage becomes remarkable and the substrate surface is roughened. However, when the substrate temperature T ₁ is (T ₂ + 50 ° C.) or less, such group V component separation is significantly reduced. (5) The oxide is deposited on the substrate in polycrystalline form, and
When an image of a polycrystal obtained through a reflection type high-energy electron diffraction device (RHEED) shows a halo pattern or a 1 × 1 pattern, when the polycrystal is irradiated with a Group 3 atom, In atoms are Deposit in order. (6) When the substrate surface is exposed to Group III atoms while it is a Group V stabilized surface, a chemical reaction occurs on the substrate surface, and the oxide forming the oxide film is released at low temperature. The oxide composition changes easily. As a result, the oxide film is rapidly separated from the substrate surface, and a Group III surface that is flat at the atomic level appears on the substrate surface. (7) When the substrate surface is irradiated with Group III atoms while the substrate is a Group III surface, extra Group III atoms are deposited on the substrate surface, resulting in poor flatness of the substrate surface. (8) When a Group III-V compound semiconductor is deposited and grown on the surface of the substrate in the crystal growth step after the treatment of the above item (6), impurities or transitions occur at the interface between the substrate and the crystal. Good quality semiconductor crystals grow on the substrate without the formation of layers. (9) By performing the treatment of the above item (6), the Group III stabilizing surface appears on the substrate surface at a lower temperature. (10) The Group III-stabilized surface, which appears on the substrate surface by the treatment of the above item (6), has extremely few impurities such as oxygen and carbon.

[0017]

EXAMPLE A molecular beam epitaxy apparatus used in the method of the present invention will be described with reference to FIG. In FIG. 1, a growth chamber 1 composed of an airtight pressure-resistant container includes a container body 1a and a lid body 1b which are combined with each other, and a liquid nitrogen shroud 2 is provided on each wall surface of the container body 1a and the lid body 1b. ing. In FIG. 1, the substrate holder 3 is rotatably disposed in the center of the growth chamber 1 including a transmission system 4 for rotation, and penetrates the rotation transmission system 4 and the wall surface on the container body 1a side. The manipulator 5 is connected to each other. Further, the substrate holder 3 is equipped with an electric heater (not shown) for heating the substrate holder 3, and the heater can be controlled from the manipulator 5 side. On the lid 1b side of the growth chamber 1, a plurality of molecular beam source cells 6a to 6d are attached, which pass through the lid wall from the outside toward the inside and face the substrate holder 3 side. Inside the growth chamber 1, shutters 7a to 7d for individually blocking the beams from these molecular beam source cells 6a to 6d are provided on the tip side, and
Between each of the shutters 7a to 7d and the substrate holder 3, a main shutter 8 for collectively blocking the beams from these cells is arranged. Container body 1a of growth chamber 1
The gate valve 9 provided in the above connects the growth chamber 1 and a substrate preparation chamber (not shown), and further, a substrate introduction chamber (not shown) is connected to the substrate preparation chamber side. In FIG. 1, a reflection type high speed electron diffraction device (RHEED) 10 and an RH mounted on wall surfaces of a container body 1a facing each other.
The fluorescent screen 11 for EED has its tips intervening in the growth chamber 1 so as to correspond to the substrate holder 3 side. The quadrupole mass spectrometer (QMS) 12 is also mounted on the wall surface portion of the container body 1 a, and the tip of this is interposed in the growth chamber 1. Ion gauge 13 for molecular beam monitor
It is arranged in the growth chamber 1 on the container body 1a side. In FIG. 1, reference numeral 14 denotes a viewing window provided in the growth chamber 1, and 15
Indicates a substrate held on the substrate holder 3.

An example of using the molecular beam epitaxy apparatus illustrated in FIG. 1 in the method of the present invention and growing an InAlAs crystal on the (100) plane of the InP substrate 15 will be described below. The respective source materials for producing the In molecular beam, Al molecular beam, and As molecular beam are the respective molecular beam source cells 6a to 6d.
Among them, they are housed in a predetermined number of cells and heated to a temperature at which the molecular beam sublimes or evaporates. For example, the In radiation source material is stored in the molecular radiation source cell 6a, the Al radiation source material is stored in the molecular radiation source cell 6b, and the As radiation source material is stored in the molecular radiation source cell 6C. ing. The InP substrate 15 is carried into the substrate preparation chamber from the substrate introduction chamber, and after moisture and other substances are removed by heat treatment in the substrate preparation chamber, it is carried into the growth chamber 1 from the substrate preparation chamber and set on the substrate holder 3. It In this way, the inside of the growth chamber 1 into which the InP substrate 15 is loaded is maintained in an ultrahigh vacuum atmosphere containing no impurities. In the cleaning process of the InP substrate 15, the InP substrate 15 is used as a molecular beam for cleaning the substrate.
The As molecular beam is used to prevent the detachment of the P atom from the. The pressure of the As molecular beam emitted from the molecular beam source cell 6c is controlled by the heating temperature of the cell 6c and the mechanical opening / closing of the shutter 7c at the tip of the cell 6c. At the time of this cleaning, whether the surface of the substrate is a Group III stabilizing surface or a Group V stabilizing surface is determined by electron diffraction through the reflection type high speed electron diffraction device 10 and the fluorescent screen 11. The surface condition of the cleaned substrate 15 is observed through electron beam diffraction and a scanning electron microscope.

FIG. 2 (vertical axis: As molecular beam pressure, horizontal axis: substrate 5-3 transition temperature) shows As molecules irradiated to the surface of the InP substrate 15 in the molecular beam irradiation process of the substrate cleaning step described above. 7 shows the results of experiments performed to determine the line pressure. In Fig. 2, each plot (x
The points) are the measured values of the 5-3 transition temperature at various As molecular beam pressures, and these measured value points are connected by a solid line. As is clear with reference to FIG. 2, the surface of the InP substrate 15 serves as a Group 5 stabilizing surface on the lower temperature side than the solid line in the figure and as a Group 3 stabilizing surface on the higher temperature side than the solid line in the figure. . When the As molecular beam pressure is in the range of 10 ⁻⁵ to 10 ⁻⁷ Torr, the 5-3 transition temperature decreases almost linearly with the decrease of the As molecular beam pressure. In such a case, the surface of the substrate obtained after cleaning is not roughened,
The electrical characteristics of the grown crystal do not deteriorate. In particular, when the As molecular beam pressure is high, the formation of InAs on the surface of the InP substrate is promoted, which causes a situation where the lattice constant of InAs is greatly different from that of InP, but the As molecular beam pressure is 10 ⁻⁶ to 10 ⁻⁷ Torr.
When it is within the range, it is more desirable because such a situation is suppressed. When the As molecular beam pressure is less than 10 ⁻⁷ Torr, the 5-3 transition temperature deviates from the straight line and shifts to the high temperature side. This is As molecular beam pressure 10 ^-7 Torr
This is because P is significantly separated from the InP substrate 15 at a temperature lower than the above and the transition condition of the surface layer of the substrate changes. In such a case, the surface of the substrate obtained after cleaning is roughened. When the As molecular beam pressure exceeds 10 ⁻⁵ Torr, the substitution of P atoms and As atoms inside the substrate is promoted, so that a buffer layer is formed at the interface between the substrate and the grown crystal, and the electrical characteristics of the crystal are increased. Is reduced. Therefore, the As molecular beam pressure P ₁ in the substrate cleaning step is 10 ⁻⁵ to 10 ⁻⁷ Tor.
It is necessary to be set within the range of r, and this value is 10 ^-6 ~
It is more desirable to set it within the range of 10 ⁻⁷ Torr.

In order to completely remove the impurities on the substrate surface, it is necessary to form a Group III stabilizing surface on the substrate surface. As a condition therefor, the As molecular beam pressure P ₁ is 1
When it is 0 ⁻⁵ Torr, the surface temperature T ₁ of the InP substrate 15 is set to 500 ° C. or higher, and the As molecular beam pressure P ₁ is 10 ⁻⁷ Torr.
When r, the surface temperature T ₁ of the InP substrate 15 is set to 350 ° C. or higher. However, when the surface temperature T ₁ exceeds the critical temperature (five-three transition temperature T ₂ + 50 ° C.), P as described above.
Since good substrate surface due to the release of can not be obtained, it is necessary to control to hold the T ₁ below the critical temperature. Therefore, for the surface temperature T ₁ , T ₂ ≦ T
This is controlled so as to satisfy ₁ ≦ (T ₂ + 50 ° C.), and in such a case, impurities on the substrate surface can be removed without causing surface roughness.

Next, specific examples of the method of the present invention based on the above will be described. [Specific Example 1] In the specific example 1, InA is formed on the InP substrate.
Grow lAs crystals. The pressure P ₁ of As molecular beam emitted from the molecular beam source cell during the substrate cleaning step of cleaning the substrate surface by performing molecular beam irradiation treatment while heating the substrate surface in an ultrahigh vacuum atmosphere. The temperature of the substrate was raised at 30 ° C./min while setting the pressure to 1 × 10 ⁻⁶ Torr and irradiating the surface of the substrate with As molecular beam having the pressure. By doing so, it was confirmed that a Group III stabilizing surface appeared on the substrate surface when the surface temperature T ₁ of the InP substrate reached 420 ° C. After that, only the substrate heat treatment is continued under the above conditions,
When the surface temperature T ₁ of the InP substrate reached 440 ° C., the temperature rise was stopped and this state was maintained for 2 minutes. After the temperature rise was stopped, two minutes later, the surface of the substrate was observed through an electron diffractometer and an electron microscope. As a result, the InP substrate had a smooth surface with no unevenness, and P did not separate from the substrate surface. It was confirmed that there was no surface roughness due to it. In the crystal growth process subsequent to the above substrate cleaning process,
The pressure of the As molecular beam emitted from the molecular beam source cell is increased to 2 × 10 ⁻⁵ Torr by shutter operation, and when the predetermined As molecular beam pressure is obtained, the other two molecular beam source cells are Opened by shutter, As molecular beam, In
The InAlAs crystal was deposited and grown on the InP substrate by irradiating the substrate surface with the molecular beam and the Al molecular beam, respectively. In order to evaluate the InAlAs crystal obtained in Example 1, this was subjected to SIMS (secondary ion mass spectrometer) and X-ray diffractometer. Referring to the analysis result by SIMS, almost no impurities are present in the InAlAs crystal of Example 1. That is, InAlAs of Specific Example 1
Compared with the InAlAs crystal produced by the conventional MBE method, the crystal content of the crystal is reduced to 1/200 or less. Further, referring to the measurement results by the X-ray diffractometer, the compound semiconductor of Example 1 had a good potential barrier because no buffer layer was formed at the interface between the InP substrate and the crystal.

[Specific Example 2] Also in the specific example 2, InAlAs crystals are grown on the InP substrate. The pressure P ₁ of As molecular beam emitted from the molecular beam source cell during the substrate cleaning step of cleaning the substrate surface by performing molecular beam irradiation treatment while heating the substrate surface in an ultrahigh vacuum atmosphere. 1 x 10 ^-7
Torr was set, and the temperature of the substrate was raised at 35 ° C./min while irradiating the surface of the substrate with the As molecular beam having the pressure. As a result, the surface temperature T ₁ of the InP substrate was 350 ° C.
It was confirmed that a Group III stabilizing surface appeared on the substrate surface when the temperature reached the temperature. Then, only the substrate heat treatment was continued under the above conditions, and when the surface temperature T ₁ of the InP substrate reached 400 ° C., the temperature rise was stopped and this state was maintained for 5 minutes. After the temperature rise was stopped, after 5 minutes, the substrate surface was observed through an electron diffraction device and an electron microscope.
The InP substrate had a smooth surface without irregularities, and it was confirmed that the surface of the InP substrate was not roughened due to the release of P. The crystal growth step subsequent to the above-mentioned substrate cleaning step was carried out in the same manner as in Example 1 to deposit and grow InAlAs crystals on the InP substrate. In the InAlAs crystal obtained in Example 2, the impurities were completely removed in the evaluation test similar to Example 1, and the potential barrier of the compound semiconductor was also good as in Example 1.

[Specific Example 3] Also in the specific example 3, InAlAs crystals are grown on the InP substrate. The pressure P ₁ of As molecular beam emitted from the molecular beam source cell during the substrate cleaning step of cleaning the substrate surface by performing molecular beam irradiation treatment while heating the substrate surface in an ultrahigh vacuum atmosphere. The shutter operation sets the pressure to 5 × 10 ^-7 Torr,
The temperature of the substrate was raised at 30 ° C./minute while irradiating the substrate surface with the molecular beam. By doing so, it was confirmed that a Group V stabilizing surface appeared on the substrate surface when the surface temperature T ₁ of the InP substrate reached 300 ° C. Then, while continuing the above treatment, when the surface temperature T ₁ of the InP substrate reached 360 ° C., the group 3 In molecular beam was irradiated with 2 × 10 ⁻⁷ Torr.
It was confirmed that when the substrate surface was irradiated for 2 seconds, the oxide film on the substrate surface was rapidly released, and a Group III stabilizing surface appeared on the substrate surface. This confirmation is performed by a quadrupole mass spectrometer (QMS) and a reflection high-speed electron diffraction instrument (RHEED)
According to In the case where the irradiation of the In molecular beam on the substrate surface was omitted as the above comparative example, a Group III stabilizing surface appeared on the substrate surface when the surface temperature T ₁ of the InP substrate reached 395 ° C. When the Group III stabilized surface appeared on the substrate surface, the temperature rise of the substrate was stopped, and the substrate surface was observed through an electron diffractometer and an electron microscope. As a result, the InP substrate had a smooth surface with no unevenness. It was In the crystal growth step subsequent to the above-mentioned substrate cleaning step, this step is used as a specific example 1.
InAlAs crystals were deposited and grown on the InP substrate in the same manner as in. In the InAlAs crystal obtained in Specific Example 3, impurities were completely removed in the same evaluation test as in Specific Example 1, and the potential barrier of the compound semiconductor was also good as in Specific Example 1.

According to the method of the present invention, when a compound semiconductor other than those shown in the above-mentioned examples and specific examples is deposited and grown on a Group 3-5 substrate other than those shown in the above-mentioned examples and specific examples, for example, InAs is used. , InSb, GaP, GaAs, GaS
When InGaAlAs, InGaAlSb, etc. are deposited and grown on a substrate of b, AlAs, AlSb, InGaAs, etc., the same or similar to the above contents can be applied.

[0025]

The present invention is based on the molecular beam epitaxy method (MBE).
Method, a clean and flat substrate surface is obtained, no harmful impurities are present at the interface between the substrate and the crystal, and a buffer layer is formed at the initial stage of crystal growth. It is also possible to prevent this, so that a high quality compound semiconductor can be manufactured with good reproducibility.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a molecular beam epitaxy apparatus used in a method for producing a compound semiconductor according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between As molecular beam pressure of an InP substrate and a 5-3 transition temperature in a method for producing a compound semiconductor according to the present invention.

[Explanation of symbols]

 1 Growth Chamber 1a Container Body 1b Lid 2 Liquid Nitrogen Shroud 3 Substrate Holder 5 Manipulator 6a Molecular Beam Source Cell 6b Molecular Beam Source Cell 6c Molecular Beam Source Cell 6d Molecular Beam Source Cell 7a Shutter 7b Shutter 7c Shutter 7d Shutter 8 Main Shutter 9 Gate valve 10 Reflective high-speed electron diffraction device (RHEED) 11 Fluorescent screen 12 Quadrupole mass spectrometer (QMS) 15 Substrate

Claims (6)

[Claims] 1. A substrate cleaning step for cleaning a substrate surface by performing molecular beam irradiation treatment while heating the surface of a substrate composed of a Group III-V compound in a high vacuum atmosphere, and in a high vacuum atmosphere. In a crystal growth step for irradiating a cleaned substrate surface with a plurality of molecular beams composed of constituent atoms of the semiconductor crystal to deposit and grow semiconductor crystals on the substrate surface, and the substrate cleaning When the substrate surface is heat-treated in the oxidization step, the surface temperature of the substrate is increased until a Group III stabilizing surface appears on the substrate surface, and when the substrate surface is subjected to molecular beam irradiation treatment in the substrate cleaning step. In addition, among the molecular beams used in the crystal growth step, a group 5 molecular beam that does not cause substantial deposition on the substrate surface by itself is used, and the pressure of the group 5 molecular beam is P
₁ , P ₁ when the molecular beam pressure during crystal growth is P _2.
A method for producing a compound semiconductor, which comprises irradiating the surface of a substrate with the Group 5 molecular beam held under a pressure of ≦ (P ₂ × 1/2). 2. In the substrate cleaning step, the surface temperature of the substrate is T ₁ , and the transition temperature T _{2 between the} Group 5 stabilization surface and the Group III stabilization surface is T _2.
In the case of, after the Group III stabilizing surface appears on the substrate surface,
The method for producing a compound semiconductor according to claim 1, wherein the substrate surface temperature is maintained at T ₂ ≦ T ₁ ≦ (T ₂ + 50 ° C.) while irradiating the substrate surface with the Group 5 molecular beam. 3. In a substrate cleaning process using an InP substrate, while irradiating the substrate surface with a molecular beam containing As atoms held at a pressure of 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ Torr, the substrate surface is subjected to three The method for producing a compound semiconductor according to claim 1, wherein the surface temperature of the substrate is raised until the group stabilizing surface appears. 4. In the substrate cleaning step, after the Group III stabilizing surface appears on the substrate surface, 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ To is obtained.
While irradiating the substrate surface with a molecular beam containing As atoms held at a pressure of rr, the surface temperature of the substrate is T ₂ ≦ T ₁ ≦ (T ₂ +
The method for producing a compound semiconductor according to claim 3, wherein the method is maintained at 50 ° C. 5. A substrate cleaning step for cleaning the substrate surface by molecular beam irradiation while heating the surface of the substrate made of a Group III-V compound in a high vacuum atmosphere, and in a high vacuum atmosphere. In a crystal growth step for irradiating a cleaned substrate surface with a plurality of molecular beams composed of constituent atoms of the semiconductor crystal to deposit and grow semiconductor crystals on the substrate surface, and the substrate cleaning In the oxidization step, irradiation of the molecular beam of Group 3 atoms constituting the substrate to the substrate surface before the Group 5 stabilizing surface appears on the substrate surface and before the Group 3 stabilizing surface appears. A method of manufacturing a compound semiconductor having the characteristics. 6. In a substrate cleaning process using an InP substrate, 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ To while increasing the surface temperature of the substrate until a Group V stabilizing surface appears on the substrate surface.
Irradiating the substrate surface with a molecular beam containing As atoms held at a pressure of rr, and after the appearance of the Group 5 stabilizing surface on the substrate surface and before the appearance of the Group 3 stabilizing surface,
The method for producing a compound semiconductor according to claim 5, wherein the surface of the substrate is irradiated with a molecular beam containing In atoms.