JP2002274997A - METHOD FOR MANUFACTURING GaN SEMICONDUCTOR CRYSTAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a GaN semiconductor single crystal having few crystal defects with a high yield by using a rare earth 13 (3B) group perovskite substrate showing relatively good lattice matching with the GaN semiconductor crystal. SOLUTION: In the method of growing the GaN semiconductor crystal by using a rare earth 13 (3B) group perovskite crystal containing one or more kinds of rare earth elements as the substrate, a plane in an off-angle state by 1 deg. to 4 deg. from the (011) plane of the rare earth 13 (3B) perovskite crystal substrate is used as the growing plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device such as a light emitting device or an electronic device.
The present invention relates to a method for producing an aN-based compound semiconductor crystal.

[0002]

2. Description of the Related Art GaN, InGaN, AlGaN, InGaN
GaN-based compound such as GaAlN semiconductor _(In x _Ga y A
l _1-xy N where 0 ≦ x, y; x + y ≦ 1) is expected not only as a light emitting device but also as a material for semiconductor devices such as electronic devices such as devices having excellent environmental resistance and power devices, In addition, it is attracting attention as a material applicable in various other fields.

Conventionally, it has been difficult to grow a bulk crystal of a GaN-based compound semiconductor. For this reason, the above-mentioned electronic device has a substrate on which a thin-film single crystal such as GaN is formed by heteroepitaxy on a heterogeneous crystal such as sapphire. Was used.

However, since the lattice mismatch between the sapphire crystal and the GaN-based compound semiconductor crystal is large, the dislocation density of the GaN-based compound semiconductor crystal grown on the sapphire crystal becomes large and crystal defects occur. was there. Furthermore, since sapphire has a low thermal conductivity and is difficult to dissipate heat, there is a problem in that when a substrate in which a GaN-based compound semiconductor crystal is grown on a sapphire crystal is used for an electronic device or the like which consumes a large amount of power, the temperature tends to rise.

Accordingly, the need for a substrate having a large thermal conductivity and lattice-matching with a GaN-based compound semiconductor crystal has been further increased.
Research such as ELO (Epitaxial Lateral Overgrowth) using hydride vapor phase epitaxy (hereinafter abbreviated as HVPE) has been rapidly advanced. Here, the ELO method means that, for example, an insulator mask is formed on a sapphire substrate, an opening is provided in a part of the mask, and the exposed sapphire substrate surface is used as a seed for epitaxial growth to form a highly crystalline GaN-based compound semiconductor crystal. It is a method of growing. According to this method, the growth of the GaN-based compound semiconductor crystal starts from the opening provided in the mask, and the growth layer spreads on the mask. Therefore, the dislocation density in the crystal can be suppressed to be small, and the number of crystal defects is small. A GaN-based compound semiconductor crystal can be obtained.

However, since the GaN-based compound semiconductor crystal wafer obtained by the ELO method has a large thermal distortion, it is difficult to separate the sapphire substrate by polishing in the wafer manufacturing process to obtain a GaN-based compound semiconductor crystal wafer alone. There is a problem that the system compound semiconductor crystal wafer is distorted.

Therefore, the present inventors have used a rare earth 13 (3B) group perovskite crystal as one of the materials for the heterocrystalline substrate, and have grown a GaN-based compound semiconductor using the {011} plane or the {101} plane as a growth plane. A method of growing by heteroepitaxy was proposed (WO 95/278).
No. 15). The {011} plane or {10}
The 1｝ plane represents a set of planes equivalent to the (011) plane and the (101) plane, respectively.

According to the growth technology of the prior application, for example, NdGa which is one of the rare earth 13 (3B) group perovskites is used.
Using O ₃ as a substrate, its {011} plane or {101}
When GaN is grown on a surface, the lattice mismatch is about 1.2%, which is much smaller than that of a substrate made of sapphire or SiC used as a substitute thereof. Therefore, the dislocation density in the crystal is reduced, so that a GaN-based compound semiconductor crystal with few crystal defects can be grown.

[0009]

However, in the growth method of the prior application, the generation of crystal defects due to lattice mismatch with the substrate during the growth of the GaN-based compound semiconductor crystal could be suppressed. In some cases, the crystal state of the GaN-based compound semiconductor crystal becomes polycrystalline. That is, the prior-art growth method has a problem that a GaN compound semiconductor single crystal suitable for a semiconductor device may not be able to grow with high yield.

The present invention provides a method for producing a GaN-based compound semiconductor single crystal having few crystal defects with good yield by using a rare-earth 13 (3B) group perovskite which has a relatively good lattice matching with a GaN-based compound semiconductor crystal as a substrate. The purpose is to provide.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and a GaN-based compound using a rare earth 13 (3B) group perovskite crystal containing one or more rare earth elements as a substrate. In the method for growing a semiconductor crystal, a plane which is off-angled by 1 ° to 4 ° from the (011) plane of the rare-earth 13 (3B) group perovskite crystal substrate is defined as a growth plane.
This is a method for producing an aN-based compound semiconductor crystal.

Thus, a GaN-based compound semiconductor crystal having few crystal defects can be grown, and
Since the single crystallization rate of the aN-based compound semiconductor crystal is improved,
A GaN-based compound semiconductor single crystal suitable for a semiconductor device can be manufactured with high yield.

Preferably, the off-angle direction is set to the <100> direction. As a result, the single crystallization ratio of the GaN-based compound semiconductor crystal becomes particularly high.
An aN-based compound semiconductor single crystal can be manufactured with high yield.

The rare earth element 1 used as a substrate
The 3 (3B) group perovskite crystal is preferably a compound of N and at least one of Al, Ga, and In among rare earth elements. For example, an NdGaO ₃ crystal can be used as the rare earth 13 (3B) group perovskite crystal. Also, hydride VPE is desirable as a crystal growth method.

Hereinafter, a process of completing the present invention will be described.

First, the present inventors have proposed the G method proposed in the prior application.
Ga obtained by a method of growing an aN-based compound semiconductor crystal
It has been noticed that some of the N-based compound semiconductor crystals have a polycrystalline crystal state. That is, in the above-mentioned growth method, the generation of crystal defects due to lattice mismatch with the substrate when growing the GaN-based compound semiconductor crystal could be suppressed. It has been found that it is difficult to put it into practical use as a method for producing a GaN compound semiconductor crystal suitable for a material of a semiconductor device.

Therefore, the present inventors consider that there is room for further improvement in the above-mentioned growth method, and in order to improve the crystal state of the GaN-based compound semiconductor crystal obtained by the above-mentioned growth method, a rare-earth 13 (3B) group perovskite is used. N which is one
Focusing on the growth surface of the dGaO ₃ substrate, intensive research was conducted.
Specifically, the (011) just surface of the NdGaO ₃ substrate was used as the growth surface in the growth method of the prior application, but instead of (0)
11) An experiment was conducted in which a GaN compound semiconductor crystal was grown with an off-angle plane inclined by a predetermined angle from the plane as a growth plane.

First, an ingot of NdGaO ₃ crystal is sliced, and a substrate having an off-angle surface inclined by 1 ° to 6 ° in the <100> direction from the (011) just surface and the (011) surface is used as a growth surface. Multiple pieces were prepared for each. After cleaning and etching these NdGaO ₃ substrates, GaN compound semiconductor crystals were grown by the hydride VPE method.

As a result, when the (011) just face was used as the growth face, the single crystallization ratio was 50%, and the single crystallization rate was 1
The single crystallization ratio when the off-angle surface inclined at an angle of 0 ° is the growth surface is 80%, and the single crystallization ratio when the off-angle surface inclined at 2 ° from the (011) plane is the growth surface is 90%.
The single crystallization ratio when the off-angle surface inclined at 3 ° from the (11) plane is the growth surface is 80%, and the single crystallization ratio when the off-angle surface at 4 ° from the (011) plane is the growth surface is: When the off-angle plane inclined by 5 ° from the (011) plane was used as the growth plane, the single crystallization ratio was 50%.
1) When the off-angle plane inclined 6 ° from the plane was used as the growth plane, the single crystallization ratio was 30% (Table 1).

[0020]

[Table 1]

From this experiment, (01) of the NdGaO ₃ substrate
1) It was found that the single crystallization ratio was improved when the off-angle surface inclined by 1 ° to 4 ° in the <100> direction from the (011) plane was used as the growth surface, rather than when the just surface was used as the growth surface. .

The present invention has been made based on the above findings, and this method can grow a GaN compound semiconductor single crystal suitable for a semiconductor device with high yield.

In the present invention, the NdGaO ₃ substrate is
Although it was found by an experiment for growing an N compound semiconductor crystal, in addition to the GaN compound semiconductor crystal, In
Similar effects can be obtained when a GaN-based compound semiconductor crystal such as GaN or AlGaN is grown.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below in which a GaN compound semiconductor crystal is grown using an NdGaO ₃ crystal as a substrate.

First, an ingot of NdGaO ₃ was placed at (01
1) A substrate was sliced on an off-angle plane inclined at 2 ° in the <100> direction from the plane. At this time, NdGaO ₃
The size of the substrate was 50 mm in diameter, and the thickness was 0.5 mm.

Next, the mirror-polished NdGaO ₃ substrate was subjected to ultrasonic cleaning in acetone for 5 minutes, followed by ultrasonic cleaning in methanol for 5 minutes. Thereafter, the liquid droplets were blown off by blowing with N ₂ gas, and then air-dried. next,
The washed NdGaO ₃ substrate was etched with a sulfuric acid-based etchant (phosphoric acid: sulfuric acid = 1: 3, 80 ° C.) for 5 minutes.

Next, after placing this NdGaO ₃ substrate at a predetermined position in a hydride VPE device, the substrate temperature was increased to 620 ° C. while introducing N ₂ gas, and the NdGaO ₃ substrate was formed from Ga metal and HCl gas. GaCl and NH ₃ gas were supplied onto the NdGaO ₃ substrate using an N ₂ carrier gas to form a GaN protective layer of about 100 nm. NdG
Since aO ₃ reacts with NH ₃ or H ₂ at a high temperature of 800 ° C. or more to generate a neodymium compound, in this embodiment, N ₂ is used as a carrier gas and the growth temperature is 620 ° C.
By forming the protective layer at a low temperature, the neodymium compound is prevented from being generated.

Next, the substrate temperature is raised to 1000 ° C.
a GaCl generated from metal and HCl gas, NH
_{The three} gases were supplied onto a NdGaO ₃ substrate using a N ₂ carrier gas. At this time, the GaCl partial pressure was 4.0 × 10
⁻⁴⁰ atm while controlling the gas introduction amounts so that the partial pressure of NH ₃ becomes 2.4 × 10 ⁻¹ atm.
A GaN compound semiconductor crystal was grown at a growth rate of m / h for 300 minutes.

Thereafter, the cooling rate is 5.3 ° C./min at 90 ° C.
After cooling for one minute, a GaN compound semiconductor crystal having a thickness of about 200 μm was obtained.

The obtained GaN compound semiconductor crystal was a single crystal having few crystal defects and excellent crystallinity. Further, when a GaN compound semiconductor crystal is manufactured by the above-described method, the single crystallinity of the GaN compound semiconductor crystal is 90% or more, so that a GaN compound semiconductor single crystal suitable as a material for a semiconductor device can be grown with high yield. did it.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments. For example, the angle of inclination in the <100> direction is not limited to 2 °, and the single crystallization ratio can be improved by setting the angle in the range of 1 ° to 4 ° as in the present embodiment.

Further, as the growth conditions, GaCl partial pressure of ^{1.0 × 10 -3 ~1.0 × 10 -} 2 atm, NH 3 partial pressure 1.0 × ¹⁰ -1 ~4.0 × ^{10 - 1} atm, growth rate 30-100 μm / h, growth temperature 930-1
It is desirable that the cooling rate is 050 ° C and the cooling rate is 4 to 10 ° C / min.

The present invention is not limited to the case where a GaN compound semiconductor crystal is grown. For example, InGaN, AlGaN
The same effect can be obtained by applying the present invention to a method for growing a GaN-based compound semiconductor crystal. The rare-earth 13 (3B) group perovskite crystal used as the substrate is Nd.
The crystal is not limited to the GaO ₃ crystal, but may be a rare-earth 13 (3B) group perovskite crystal containing at least one of Al, Ga, and In.

[0034]

According to the present invention, there is provided a method of growing a GaN-based compound semiconductor crystal using a rare earth 13 (3B) group perovskite crystal containing one or more kinds of rare earth elements as a substrate. Since the plane that is off-angled by 1 ° to 4 ° from the (011) plane of the perovskite crystal substrate is used as the growth plane, a GaN-based compound semiconductor crystal with few crystal defects can be grown, and the GaN-based compound semiconductor crystal Since the single crystallization rate is improved, there is an effect that a GaN-based compound semiconductor single crystal suitable for a semiconductor device can be manufactured with high yield.

Claims (3)

[Claims] 1. A method for growing a GaN-based compound semiconductor crystal using a rare earth 13 (3B) group perovskite crystal containing one or more kinds of rare earth elements as a substrate, wherein the (011) A method for producing a GaN-based compound semiconductor crystal, characterized in that a plane off-angled by 1 ° to 4 ° from the plane is a growth plane. 2. The off-angle direction is <100>.
The method according to claim 1, wherein the direction is a direction. 3. The rare earth element 13 used as a substrate.
The group (3B) perovskite crystal is one of the rare earth elements A
The G according to claim 1 or 2, wherein the compound is a compound of at least one of l, Ga, and In and N.
A method for producing an aN-based compound semiconductor crystal.