JPH0567576A - Manufacture of compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To enhance the reproducibility of the title manufacture by a method wherein ethyldimethylindium is used as an In raw material and to enhance the safety of an apparatus by a method wherein monotertiary butylarsine and monotertiary butylphosphine are used as P raw materials in the manufacture of a III-V compound semiconductor crystal. CONSTITUTION:A group III raw material and a Group V raw material are introduced respectively into a reaction container together with a carrier gas; they are pyrolyzed; a III-V compound semiconductor crystal is vapor-grown on a substrate 4. In the manufacturing method of the compound semiconductor crystal, monotertiary butylarsine (C4H9AsH2) and monotertiary butylphosphine (C4H9PH2) are used as group V raw materials, and ethyldimethylindium [C2 H5(CH3)2In] is used as one of group III raw materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a compound semiconductor device containing arsenic (As), phosphorus (P) and indium (In) as constituent elements, and is particularly safe and has reproducibility of film thickness and composition. It is about how to provide good growth technology.

[0002]

2. Description of the Related Art Semiconductor lasers currently in practical use,
The light receiving element is In _1-x Ga _x As _y P _1-y , In _1-x Ga
is made of group III-V compound semiconductor crystal such as _x As. These crystals are industrially used in liquid phase epitaxy and chloride vapor phase epitaxy, respectively, but in recent years, metal organic vapor phase epitaxy (hereinafter MOVP) using organic metal as a raw material has been used.
The E method is abbreviated). The reason is MO
Since the composition control is easy in the VPE method and a crystal having excellent film thickness and composition uniformity can be obtained even in a large-area substrate, it is considered to have a great industrial advantage as compared with the conventional method. Is.

Taking a case where an active layer (In _1-x Ga _x As _y P _1-y ) of a laser having a light wavelength of 1.3 to 1.5 μm is formed by the MOVPE method as an example, a normal MOV will be described.
In the PE method, trimethylcindium (hereinafter abbreviated as TMI), triethylgallium (hereinafter abbreviated as TEG) as a group III raw material, and arsine (hereinafter A as a group V raw material).
sH ₃ ) and phosphine (hereinafter referred to as PH ₃ ) are used to thermally decompose the raw material under atmospheric pressure or a reduced pressure of about several tens of torr to epitaxially grow it on the InP substrate.

In FIG. 5, the compound semiconductor In _1-x Ga _x As _y P _1-y is converted into In by a MOVPE apparatus having a vertical reaction tube.
An apparatus configuration for growing on a P substrate is shown. In the figure, 1 is a reaction tube, 2 is a high frequency induction coil, 3 is a susceptor, 4 is a substrate, 5 is a rotary shaft, 6 is a rotary pump, and 7 is a rotary pump.
Is a pressure gauge, 8 is a pressure control valve, 9 is a nozzle, 10 is piping,
11, 12 are pressure regulating valves, 15 and 16 are pressure gauges, 19,
Reference numeral 20 is a raw material container, 23, 24, 27 and 28 are mass flow controllers, 29 and 30 are pressure reducing valves, 31 and 32 are high pressure cylinders, and 33 and 34 are constant temperature baths. Then III
The group materials TMI and TEG are contained in stainless steel material containers 19 and 20, respectively. TEG is a liquid,
Since TMI is solid, it adheres to the inner wall of the container in the form of needle crystals. The raw material container is kept at a certain temperature by a constant temperature bath. For example, TMI is 20 ℃, TEG is 1
The temperature is 0 ° C., and the saturated vapor pressures at this time are 1.1 Torr and 2.3 Torr, respectively. Mass flow controller 2
The carrier gas whose flow rate is controlled by 3, 24 is introduced into the raw material container, and the raw material vapor is saturated. After that, it is supplied to the reaction tube 1 through the pipe 10. Pressure gauge 15, 16
Detects the pressure in the raw material container and transmits a feedback signal to the pressure adjusting valves 11 and 12 to keep the pressure in the raw material container at a constant value. This value is typically set near 760 torr. The concentration of the raw material in the carrier gas is precisely controlled by the saturated vapor pressure of the raw material and the pressure inside the container.
Further, the supply amount of the raw material is (flow rate of the mass flow controller) × (concentration). On the other hand, the group V raw materials arsine and phosphine are usually diluted with hydrogen gas to several tens of percent and then filled in the high-pressure cylinders 31 and 32. Filling pressure is 80
To 100 Kg / cm ² . After reducing the pressure of arsine and phosphine to several Kg / cm ² by the pressure reducing valves 29 and 30, the flow rates are controlled by the mass flow controllers 27 and 28 and are supplied to the reaction tube 1 through the pipe 10. The reaction tube 1 is made of quartz. There is a susceptor 3 made of carbon on which an InP substrate 4 is placed, and it rotates around a rotating shaft 5. The substrate is heated by the high frequency induction coil 2. The raw material gas supplied through the pipe 10 is sprayed onto the InP substrate 4 through the nozzle 9 to grow a compound semiconductor crystal. The inside of the reaction tube is evacuated by the rotary pump 6 to grow under reduced pressure. The pressure in the reaction tube is detected by the pressure gauge 7 and controlled to a constant value by the pressure adjusting valve 8. This value is usually set around 100 torr. The composition x and y of In _1-x Ga _x As _y P _1-y are the feed ratios TEG / TMI and As of the raw materials, respectively.
Uniquely determined by H ₃ / PH ₃ . Also, the growth rate is
Determined by the sum of TMI and TEG supply.

The first problem with this method is that III
Since TMI, which is one of the group raw materials, is solid around room temperature, it is difficult to keep the raw material concentration in the carrier gas constant compared to liquid raw materials. The reason is that the surface of the solid is apt to change due to the influence of oxygen and water in the carrier gas, and an altered layer is formed on the outermost surface. Therefore, the saturated vapor pressure changes and the raw material concentration in the carrier gas changes. Also,
Since TMI is recrystallized during a long use period, the surface area is reduced and the raw material concentration in the carrier gas is gradually reduced.
Therefore, there is a problem in the stable supply of raw materials over a long period of time,
There was a problem that reproducibility of composition and growth rate could not be obtained. On the other hand, conventionally, triethylindium (hereinafter abbreviated as TEI), which is a liquid In raw material near room temperature, has also been used, but since the vapor pressure near room temperature is low, it is necessary to use a raw material container in order to obtain a practical growth rate. It is necessary to heat the pipe 10 to room temperature or higher, which complicates the configuration of the apparatus and makes it difficult to purify the raw material, resulting in poor purity as compared with TMI.

The second problem is that arsine and phosphine used as V group raw materials are highly toxic gases and are usually supplied in a high pressure gas cylinder diluted with hydrogen gas to about 20%. For this reason, it is necessary to take measures against possible leakage and safety measures on the device. The main measures to be taken are a system that detects leaks of arsine and phosphine and issues an alarm.
A barrier system that completely shuts off the supply of phosphine, arsine and phosphine cylinders, and a partition that completely covers the growth equipment are installed, and the air conditioning is independent of the working space in which workers exist. It is an air-conditioning system that removes harmful substances and discharges them into the atmosphere. Therefore, enormous capital investment is required to introduce the MOVPE device into the factory.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to remedy the above drawbacks, and its purpose is to
Reproducibility deterioration due to raw material and As toxicity
The problem of great danger caused by using H ₃ and PH ₃ is solved, and high quality In
It is an object of the present invention to provide a method for producing a compound semiconductor crystal capable of producing _1-x Ga _x As _y P _1-y .

[0008]

In order to achieve the above object, the present invention introduces a group III source and a group V source together with a carrier gas into a reaction vessel and thermally decomposes them to form a group III-V group on a substrate. In the method of vapor-depositing a compound semiconductor crystal, monotertiary butyl arsine (C ₄ H ₉ AsH ₂ ) and monotertiary butyl phosphine (C ₄ H ₉ PH ₂ ) are used as Group V raw materials, Ethyl dimethyl indium (C ₂ H ₅ (C
The gist of the invention is a method for producing a compound semiconductor crystal, which is characterized by using H ₃ ) ₂ In). In other words, in order to improve the composition controllability of In _1-x Ga _x As _y P _1-y and the reproducibility of the growth rate, the present invention replaces TMI and TEI that have been used conventionally with liquids at room temperature as an In raw material. Ethyl dimethyl indium (hereinafter abbreviated as EDMIn) is used, and in order to enhance the safety of the manufacturing equipment, a less toxic mono-tertiary material is used as a raw material for As and P, which replaces the highly toxic AsH ₃ and PH ₃ used conventionally. Butyl arsine (hereinafter abbreviated as TBA) and mono-tertiary butyl phosphine (hereinafter abbreviated as TBP) are used.

[0009]

In the present invention, EDMIn is used as the In raw material.
Reproducibility is improved by using
The safety of the device can be improved by using TBA and TBP as the s and P raw materials.

[0010]

EXAMPLES Next, examples of the present invention will be described. It is needless to say that the embodiment is merely an example, and various modifications and improvements can be made without departing from the spirit of the present invention.

FIG. 1 shows the MO used in the method of the present invention.
The outline of a VPE device is shown. In the figure, 1 is a reaction tube, 2
Is a high frequency induction coil, 3 is a susceptor, 4 is a substrate, 5 is a rotary shaft, 6 is a rotary pump, 7 is a pressure gauge, 8 is a pressure adjusting valve, 9 is a nozzle, 10 is piping, 11 to 14 are pressure adjusting valves, 15 to 17 are pressure gauges, 19 to 22 are raw material containers, 23
26 show mass flow controllers. EDMIn was used as an In raw material, triethylgallium (hereinafter abbreviated as TEG) as a Ga raw material, TBA as an As raw material, and TBP as a P raw material. These raw materials are contained in raw material containers 19, 20, 21, and 22, respectively. In the apparatus configuration of the conventional method shown in FIG. 5, the TMI container 19 is replaced with an EDMIn container, and arsine and phosphine cylinders 31, 32 are used.
Was replaced with TBA and TBP containers 21 and 22. Other functions are the same as the conventional method.

Since EDMIn is a liquid near room temperature, there is no problem concerning the supply stability associated with the solid raw material. FIG. 2 shows the relationship between the growth rate of InP and the usage rate of the raw material (ratio of the usage amount to the initial amount) when the carrier gas flow rate flowing in the bubbler containing EDMIn and TMI is constant. In the case of EDMIn, the growth rate is constant until it is used up, whereas in the case of TMI, the growth rate changes. Further, since the vapor pressure and the purity of EDMIn are equivalent to those of TMI, they are more advantageous than the TEI of the liquid In raw material that has been used conventionally. According to the literature (American Cyanamid Co. of ApplicationNote No.2), LC of TBA ₅₀
Values AsH ₃ than 14 minutes for one low toxicity at 70 ppm, the value of the LC ₅₀ of TBP is not less than 1100 ppm P
1/100 less toxic than H ₃ . By the way, the LC ₅₀ values of AsH ₃ and PH ₃ are 5 ppm and 11 ppm, respectively. LC ₅₀ indicates the degree of gas toxicity, and is the gas concentration at which half of the rats (a mouse) inhaled the gas for 4 hours die within 14 days.

FIG. 3 shows In _1-x Ga _{x in} each composition.
Lattice mismatch with respect to As _y P _1-y InP of (△ a / a)
And the feed molar ratio of EDMIn and TEG (EDMIn / T
EG). EDMIn / T for each y composition
EG and Δa / a show a linear relationship, indicating that the composition controllability is good.

FIG. 4 shows In _0.56 G lattice-matched with InP.
The characteristics of a distributed feedback laser manufactured from a wafer having a double hetero structure having a _0.44 As _0.93 P _0.07 as an active layer are shown. The solid line in the figure shows the optical output, and the dotted line shows the external differential quantum efficiency. At the same time, the oscillation spectrum is also shown. When the injection current is 200 mA, the light output is about 20 mW, and the characteristics are the same as when using the conventional raw material. From the oscillation spectrum, it can be seen that there is a single longitudinal mode.

[0015]

As described above, according to the present invention, I
In a method of introducing a Group II raw material and a Group V raw material into a reaction vessel together with a carrier gas and thermally decomposing them, a III-V group compound semiconductor crystal is vapor-deposited on a substrate. (C ₄ H ₉ A
sH ₂ ) and mono-tertiary butyl phosphine (C ₄
H ₉ PH ₂ ) and ethyl dimethylindium (C ₂ H ₅ (CH ₃ ) ₂ In) as one of the group III raw materials to improve reproducibility by using EDMIn as an In raw material. The safety of the device can be improved by using TBA and TBP as the P and P raw materials, respectively. Furthermore, since the distributed feedback laser manufactured by using the present invention exhibits good characteristics, the present invention is based on In _1-x Ga _x As for semiconductor lasers and light receiving elements.
It has been shown to be effective as a method for growing _y P _1-y and In _1-x Ga _x As.

[Brief description of drawings]

FIG. 1 shows a manufacturing apparatus used in the present invention.

FIG. 2 is a diagram showing the supply stability of EDMIn.

FIG. 3 is a diagram showing composition controllability of an In _1-x Ga _x As _y P _1-y mixed crystal in the present invention.

FIG. 4 In _0.56 Ga _0.44 As grown according to the present invention
The _0.93 P _0.07 layers is a graph showing characteristics of a distributed feedback laser to the active layer.

FIG. 5 shows a MOVPE apparatus using a conventional raw material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tube 2 High frequency induction coil 3 Susceptor 4 Substrate 5 Rotating shaft 6 Rotary pump 7 Pressure gauge 8 Pressure adjusting valve 9 Nozzle 10 Piping 11 to 14 Pressure adjusting valve 15 to 17 Pressure gauge 19 to 22 Raw material container 23 to 26 Mass flow controller 27 , 28 Mass flow controller 29, 30 Pressure reducing valve 31, 32 High pressure cylinder 33, 34 Constant temperature bath

Claims (1)

[Claims] 1. A method for introducing a group III source material and a group V source material into a reaction vessel together with a carrier gas and thermally decomposing them to vapor-deposit a group III-V compound semiconductor crystal on a substrate. Using mono-tert-butylarsine (C ₄ H ₉ AsH ₂ ) and mono-tert-butyl phosphine (C ₄ H ₉ PH ₂ ), ethyl dimethyl indium (C ₂ H ₅ (CH
₃ ) A method for producing a compound semiconductor crystal, which comprises using ₂ In).