JP2003063899A - Method for producing iii-v group compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a III-V group compound semiconductor having good crystallinity. SOLUTION: The method for producing the III-V group compound semiconductor includes sequentially a first process for placing a substrate 2 composed of an n-type or a p-type III-V group compound semiconductor on a support 1 in a reactor 101, a second process for increasing the temperature of the support to a crystal-growing temperature, and a third process for growing the n-type or the p-type III-V group compound semiconductor on the substrate through an organic metal vapor phase growth method. In the second process, the raw material gas 11 for the V group element of the III-V group compound semiconductor which constitutes the substrate, and the raw material gas for dopant which has same conductivity as the substrate are simultaneously introduced into the reactor 101.

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, and more particularly to a compound semiconductor including a group 3 element and a group 5 element.
The present invention relates to a method for manufacturing a compound semiconductor.

[0002]

2. Description of the Related Art GaAs, Al are used for manufacturing light emitting devices such as light emitting diodes and laser diodes and electronic devices.
3-5 such as GaAs, AlGaInP, GaInAsP, etc.
Group compound semiconductors are widely used. The compound semiconductors used in these devices are grown by using a liquid phase epitaxial method, a metal organic chemical vapor deposition method (hereinafter referred to as MOCVD method), a molecular beam epitaxy method, or the like. Recently, the MOCVD method has been widely used.

In the MOCVD method, an organometallic gas and a hydride gas are supplied to a reactor as raw materials, and a support placed inside the reactor is heated while a substrate crystal placed on the support is heated. Is a method of growing a compound semiconductor.

In order to obtain a light emitting device, an electronic device or the like, it is necessary to continuously grow a plurality of compound semiconductors of the same kind or different kinds on a substrate. For example, in the case of a light emitting diode using AlGaInP, a buffer layer made of n-type GaAs on an n-type GaAs substrate, a lower cladding layer made of n-type AlGaInP, an active layer made of n-type AlGaInP, and an upper cladding layer made of p-type AlGaInP. , A p-type AlGaAs or p-type GaP current diffusion layer is continuously grown.

Here, control of n-type or p-type conductivity is
It is generally performed by flowing a source gas for an n-type or p-type dopant together with a source gas such as an organometallic gas. For example, when n-type GaAs is grown, Si, S, Se or the like is used as a dopant, and SiH ₄ , H ₂ S, H ₂ Se or the like is used as each source gas. When p-type AlGaAs is grown, Zn, Mg or the like is used as a dopant, and dimethylzinc (DMZn), biscyclopentadienyl magnesium (Cp ₂ Mg) or the like is used as each source gas.

[0006]

When manufacturing a device having such a laminated structure, there may occur a problem that the morphology of the surface of the wafer having the laminated structure grown on the substrate deteriorates. That is, a crystal defect may occur inside the laminated structure, and the defect may reach the surface of the wafer starting from this and form a pit or a hillock (growth hill). These crystal defects cause a reduction in device efficiency and a deterioration in electrical characteristics, which causes a reduction in yield in device fabrication.

Therefore, the present invention has been made in order to solve such a problem, and provides a method for producing a compound semiconductor having good crystallinity.

[0008]

According to the present invention, there is provided a first step of mounting a substrate made of an n-type or p-type group 3-5 compound semiconductor on a support in a reactor, and a step of forming the support. A second step of raising the temperature to the crystal growth temperature and a third step of growing an n-type or p-type group III-V compound semiconductor on the substrate by a metal organic chemical vapor deposition method are included in this order. Three
-5 Group 5 compound semiconductor manufacturing method, wherein in the second step, 5 of group 3-5 compound semiconductor constituting the substrate is used.
A source gas containing a dopant of the same conductivity type as the substrate is introduced into the reactor together with the source gas of the group element.

According to the present invention, a compound semiconductor having good crystallinity can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 comprises a first step of mounting a substrate made of an n-type or p-type group 3-5 compound semiconductor on a support in a reactor, The second step of raising the temperature of the support to the crystal growth temperature, and the n-type or p-type 3-on the substrate by the metal organic chemical vapor deposition method.
A method for manufacturing a 3-5 group compound semiconductor, comprising a third step of growing a 5 group compound semiconductor in this order, wherein in the second step, the 5 group element of the 3-5 group compound semiconductor constituting the substrate And a source gas containing a dopant having the same conductivity type as that of the substrate together with the source gas of (3) are introduced into the reactor.
With this configuration, in the process of raising the temperature of the support, re-evaporation of the Group 5 element of the Group 3-5 compound semiconductor forming the substrate is prevented, and re-evaporation of the dopant contained in the substrate and the impurities generated thereby are prevented. It has the effect of being prevented from being taken in.

The invention according to claim 2 is characterized in that the source gas of the group 5 element and the source gas of the dopant are introduced before the temperature of the support exceeds 500 ° C. A method for manufacturing a 3-5 group compound semiconductor. This configuration has an effect that the re-evaporation of the Group 5 element and the dopant contained in the substrate can be prevented more effectively.

The invention according to claim 3 is characterized in that the flow rates of the source gas for the group 5 element and the source gas for the dopant are increased as the temperature of the support increases. No. 3-5 group compound semiconductor manufacturing method. With this configuration, it is possible to start crystal growth of the 3-5 group compound semiconductor while keeping the content rates of the group 5 element and the dopant on the substrate surface substantially constant.

FIG. 1 shows an embodiment of the present invention.
2 and FIG.

FIG. 1 is a schematic view of a crystal growth apparatus for carrying out a compound semiconductor manufacturing method according to an embodiment of the present invention. The crystal growth apparatus 100 has a reactor 101, a source gas supply system 102, and an exhaust system 103.
A support 1 for mounting a wafer inside the reactor 101.
And a substrate 2 made of GaAs or the like is placed on the support 1. The support 1 is formed of a material having a high thermal conductivity such as graphite, and when the crystal grows, the heater 3 provided below the support 1 causes the support 1 to have a temperature of about 40 μm.
It is heated to a high temperature of about 0 ° C to about 1000 ° C. The reactor 101 is composed of parts made of a material such as quartz, stainless steel, molybdenum, or the like, which is selected to withstand such a high temperature.

During crystal growth, the source gas 11 for obtaining a desired compound semiconductor is supplied from the supply system 102 to the reactor 10.
Supply to 1. Inside the reactor 101, the heater 3
The raw material gas is decomposed by the support 1 heated by the substrate 1 and held at a high temperature and the substrate 2 placed thereon, and the support 1
A desired compound semiconductor is grown on the substrate 2 while being deposited on the substrate 2. Excess source gas 12 not used for deposition on the support 1 or growth on the substrate 2 is exhausted from the exhaust system 1.
It is sent to 03.

Here, the first feature of the present invention is that the substrate is formed in the step of raising the temperature of the support to the crystal growth temperature in growing the desired compound semiconductor 3-5
That is, the source gas containing the dopant of the same conductivity type as that of the substrate is introduced into the reactor together with the source gas of the group 5 element of the group compound semiconductor.

FIG. 2 is a schematic sectional view showing a part of the inside of the reactor of the crystal growth apparatus for carrying out the method according to the embodiment of the present invention shown in FIG. Usually, the compound semiconductor deposit 31 deposited in the previous crystal growth remains inside the reactor 101 and on the support 1.

Here, when the substrate 2 is placed on the support 1 to grow the compound semiconductor 21, the temperature of the support is raised from room temperature to a crystal growth temperature of about 400 ° C. to 1000 ° C. It is considered that a part of the deposit 31 on the inner wall of the reactor and the support is decomposed again by heat to become a gas and pollutes the surface of the substrate 2. In particular, when the previous crystal growth ends with a compound semiconductor having a conductivity type different from that of the substrate, the deposit 31 contains a dopant having a conductivity type different from that of the substrate, which causes the surface of the substrate 2. The crystallinity of the substrate surface may be deteriorated due to the re-evaporation or compensation of the dopant that occurs in the above step, or a high resistance region may be formed at the interface between the substrate and the compound semiconductor grown on the substrate. Such a problem causes deterioration of the characteristics of a device having a laminated structure.

In the step of raising the temperature of the support to the crystal growth temperature during the growth of a desired compound semiconductor as in the present invention, together with the source gas of the group 5 element of the group 3-5 compound semiconductor constituting the substrate. When a source gas containing a dopant of the same conductivity type as the substrate is introduced into the reactor, it prevents re-evaporation or compensation of the dopant on the substrate surface,
Crystal growth can be started without contaminating the surface of the substrate and maintaining a good substrate surface.

Further, when the temperature of the support, that is, the temperature of the substrate is around 500 ° C., re-evaporation of the Group 5 element and the dopant contained in the substrate occurs, so that the third characteristic of the present invention is 5 By introducing the raw material gas of the group element and the raw material gas of the dopant before the temperature of the support exceeds 500 ° C., re-evaporation of these can be prevented more effectively.

Furthermore, according to the findings of the present inventors,
In the step of raising the temperature of the support, re-evaporation of the Group 5 element and the dopant contained in the substrate on the surface of the substrate occurs depending on the temperature of the support. By increasing the flow rates of the source gas of the element and the source gas of the dopant as the temperature of the support rises, the group 3-5 compound semiconductor is maintained while keeping the content of the group 5 element and the dopant on the substrate surface substantially constant. Crystal growth can be started.

[0022]

EXAMPLES Examples of the present invention will be described below by taking a method of manufacturing a light emitting diode using AlGaInP as an example. First, after growing a laminated structure such as a light emitting diode using a compound semiconductor, a substrate made of n-type GaAs is introduced into a reactor and placed on a support.

Next, the support and the substrate placed thereon are heated using a heater, and the temperature is raised to the crystal growth temperature (for example, 650 ° C.) while flowing AsH ₃ and SiH ₄ gas. Here, the flow rate of the SiH ₄ gas was set to ½ of the flow rate at which the carrier concentration of n-type GaAs grown at the crystal growth temperature was equivalent to that of the substrate, and thereafter the flow rate was increased as the temperature increased.

Next, at the same time as starting to flow TMG as a source gas, the flow rate of SiH ₄ gas is changed to a desired flow rate,
About 1 μm of n-type buffer layer made of Si-doped GaAs
Grow to a thickness of.

After stopping the growth of the n-type buffer layer by stopping the supply of the source gas, the source gas T
MG, trimethyl aluminum (TMA), trimethyl indium (TMI), PH ₃ gas and SiH ₄ begins to conduct gas, Si-doped Al _{0. 35} Ga _0.15 In _0.5 grow the n-type cladding layer made of P to a thickness of about 1μm Let

After the growth of the n-type cladding layer is stopped by stopping the supply of the source gas, the undoped Al is similarly formed.
_0.1 Ga _0.4 In _0.5 in the active layer consisting of P and Zn-doped Al _{0 .35} Ga _0.15 In _0.5 p-type cladding layer consisting of P and continuously to a thickness of respectively about 0.5μm and about 1μm grow. Here, dimethyl zinc (DMZ) is used as a source gas of Zn.

After stopping the growth of the p-type clad layer by stopping the supply of the raw material gas, TMG, TMA, DMZ and AsH ₃ gas are subsequently started to flow as the raw material gas, and the p-type layer made of Zn-doped Al _0.7 Ga _0.3 As is formed. The current spreading layer is grown to a thickness of about 7 μm.

After stopping the growth of the p-type current diffusion layer by stopping the supply of the source gases other than the AsH ₃ gas, the AsH
₃ Decrease the temperature while flowing gas. When the temperature reaches about room temperature, the supply of AsH ₃ gas is stopped and exhausted sufficiently, and then the substrate is taken out from the reactor.

The defect density on the surface of the wafer having the laminated structure of the light emitting diode thus obtained was measured and found to be 4
It was 00 / cm ² . On the other hand, the defect density of the wafer in which the laminated structure of the light emitting diode is continuously grown without using the method of the present invention is 11000 / cm ^2, which is about 28 times higher than that in the case of using the method of the present invention. It was

Further, when the wafer of the light emitting diode was chipped by a usual method and the output was evaluated, the output was about 8 times higher when the method of the present invention was used than when the method of the present invention was not used. was gotten.

Here, an embodiment has been shown in which an n-type compound semiconductor is grown on an n-type GaAs substrate and a laminated structure is formed on the n-type compound semiconductor. When growing a compound semiconductor, a source gas of a p-type dopant may be supplied in the process of raising the temperature, which is within the scope of the present invention. Other various modifications may be made without departing from the spirit of the present invention.

[0032]

According to the present invention, it is possible to suppress the generation of crystal defects at the interface between the substrate and the compound semiconductor which is grown on the substrate in contact therewith. Therefore, the laminated structure of these compound semiconductors is used. An excellent effect that the manufacturing yield of the light emitting device or the electronic device can be improved is obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a crystal growth apparatus for carrying out a compound semiconductor manufacturing method according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a part of the inside of the reactor of the crystal growth apparatus for carrying out the method according to the embodiment of the present invention shown in FIG.

[Explanation of symbols]

1 support 2 substrates 3 heater 11 Raw material gas 12 Excess material gas 21 Compound semiconductor 31 sediment 100 crystal growth equipment 101 reactor 102 source gas supply system 103 Exhaust system

Continued front page    F-term (reference) 4G077 AA03 BE46 DB08 EE09 TB05                       TC02 TC16                 5F045 AB18 AC01 AC08 AD10 AF04                       BB12 CA10 DQ06 EE18

Claims (3)

[Claims] 1. An n-type or p-type on a support in a reactor.
Type step of placing a substrate made of a group III-V compound semiconductor, a second step of raising the temperature of the support to the crystal growth temperature, and a metal organic chemical vapor deposition method on the substrate. A method for manufacturing a Group 3-5 compound semiconductor, comprising a third step of growing an n-type or p-type Group 3-5 compound semiconductor in this order, and forming a substrate in the second step. 3. A method for producing a Group 3-5 compound semiconductor, which comprises introducing a source gas of a Group 5 element of a Group 5 compound semiconductor into a reactor together with a source gas of a dopant having the same conductivity type as the substrate. 2. The group 3-5 compound semiconductor according to claim 1, wherein the group 5 element source gas and the dopant source gas are introduced before the temperature of the support exceeds 500 ° C. Production method. 3. The method according to claim 1 or 2, wherein the flow rates of the source gas of the Group 5 element and the source gas of the dopant are increased as the temperature of the support increases.
Method for manufacturing Group 5 compound semiconductor.