JPH01215014A - Growth of semiconductor crystal - Google Patents

Abstract

PURPOSE:To realize a high quality epitaxial growth layer at a low temperature by projecting light onto the raw gas or the substrate on which the layer grows in a compound semiconductor or a mixed crystal semiconductor of which composition element is (N). CONSTITUTION:After a substrate 6 is placed in a growth container 1, the interior of the growth container 1 is discharged to high vacuum through an exhaust system 4. Then hydrogen gas is introduced into the growth container 1 from a gas introduction port 3 and the exhaust rate of the exhaust system 4 is adjusted to set the pressure in the growth container 1 to a fixed value. Then the substrate 6 is heated and when a fixed temperature is attained, raw gas of trimethylgallium and carrier gas of hydrogen gas and hydrogen diluted NH gas are introduced into the growth container from the gas introduction port 2. Similar to this gas introduction, a laser beam 10 from an excimer laser 9 is projected vertically onto the substrate 6. Dissociation, surface reaction and surface migration of supplied material of (N) are promoted in this way, thus allowing a high quality semiconductor crystal layer to grow.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for vapor phase growth of a compound semiconductor or a mixed crystal semiconductor having nitrogen as a constituent element.

(Prior Art) Compound semiconductors and mixed crystal semiconductors having nitrogen as a constituent element are attracting attention as optical and electronic device materials.For example, GaN is a direct transition type and has a large band gap at room temperature, so it is used for green lasers, It is expected to be used as a material for short wavelength lasers in
It is also expected to be used as an insulating layer material that allows for the good surface control required for SF[T devices. ANN, which has even higher bandgap energy than GaN, can be used as an insulating layer material for MISFET devices as well as SAW.
It is also expected to be used as a device material.

As for the epitaxial growth method of compound semiconductors or mixed crystal semiconductors having these NttW constituent elements.

N113 (ammonia) was used as the NtM charge. Chloride vapor phase epitaxy and organometallic vapor phase epitaxy are used.

However, because the raw material decomposition temperature of Ni13 is high, the growth temperature is as high as 700°C or higher, and as a result, defects 1, such as atomic vacancies, occur due to component elements, making it difficult to obtain high-quality crystals. For example, in GaN, there is a problem that a p-type crystal cannot be obtained. Electron cyclotron resonance (EC) is a method to reduce the growth temperature.
R) There is a growth method using excitation, but defects are induced inside the growing crystal due to ion bombardment, and good crystals cannot be obtained.

(The problem that the invention tries to solve!fi) As mentioned above, conventional vapor phase growth methods with high growth temperatures.

Growth methods using ions have the problem that many crystal defects such as atomic vacancies exist, and it is difficult to obtain good epitaxial growth layers in compound semiconductors or mixed crystal semiconductors that contain N as one of the constituent elements. Ta.

The present invention aims to solve these problems and provide a vapor phase growth method that makes it possible to obtain a high-quality epitaxial growth layer at low temperatures in a compound semiconductor or a mixed crystal semiconductor containing N as a constituent element. purpose.

(Structure of the Invention) (Means for Solving the Problems) The present invention is characterized in that vapor phase growth is performed by irradiating a source gas or a substrate to be grown with light.

(Function) If such a vapor phase growth method (photoexcited vapor phase growth method) is used,
The dissociation of N113, N, I+, or an organic compound containing N, which is the N supply Jjπ material, is promoted by a photochemical reaction, and the growth reaction and surface migration of reactive species on the surface of the growth substrate are promoted by light irradiation. A high-quality semiconductor crystal layer can be obtained at a lower temperature than before.

(Example) Hereinafter, as an example of the present invention, a GaN crystal layer is formed from A0.
(Sapphire) An example grown on a six-sided substrate will be described with reference to the drawings.

FIG. 1 shows that a growth vessel 1, which is a growth apparatus for performing photoexcited vapor phase growth, has AQ, 0. A (sapphire) zero-plane substrate 6 is installed and housed on the susceptor 5.

The substrate 6 on the susceptor 5 is heated by a heater (not shown), and the substrate 6 is set to a predetermined temperature. The growth container 1 is provided with gas inlets 2 and 3. The Group 1 raw material and the Group 2 bar material are introduced into the growth container 1 through the gas inlet 2 together with a carrier gas (mainly hydrogen gas). Board 6
A laser beam lO from an excimer laser 9 is applied via a reflection mirror 8 and a light introduction window 7 made of synthetic quartz. Hydrogen gas or inert gas is introduced into the growth container 1 from the gas inlet 3 in order to suppress film formation on the light introduction window. By adjusting the exhaust speed of the exhaust system 4 that exhausts the gas introduced into the container 1 from the gas introduction ports 2 and 3, the pressure inside the growth container 1 is set to a predetermined value.

Evital growth of a GaN crystal layer using such a growth apparatus will be specifically described below. Trimethylgallium (Ga(CI+, )
3) and hydrogen was used as the carrier gas. Ammonia (Ni13) was used as the Group (2) raw material gas. After the substrate 6 was placed in the growth container 1, the inside of the growth container 1 was evacuated to a high vacuum of I.times.10-' Torr or less by the exhaust system 4. After that, 4008 CCM of hydrogen gas is introduced into the growth container 1 from the gas inlet 3, and the exhaust speed of the exhaust system 4 is adjusted to grow, and the pressure inside the growth container 1 is raised to 10.0T.
It was set to orr. After that, the substrate 6 was heated, and after the temperature of the substrate 6 which was set at 400°C reached 400°C, 0.453 CCM of trimethyl gallium was added from the gas inlet 2, IO3 ccM of hydrogen gas as a carrier gas, and 10% hydrogen diluted N.
H, gas 4505CCM (NH3 flow rate 45SCCM
) was introduced into the growth vessel. In the same way as the source gas and hydrogen gas were introduced into the growth container through the gas inlet 2, the substrate 6 was irradiated with laser light 10 from an excimer laser 9 perpendicularly. The laser beam 10 used was A with a wavelength of 193n-
An rF excimer laser was used to irradiate the surface of the substrate 6 with irradiation energy of 5+aj/J per pulse. The number of repetitions of pulse irradiation was 80 pps. In addition,
The growth pressure and growth temperature were 1OTorr and 400°C, respectively.

The GaN crystal layer grown in this manner was evaluated by electron beam diffraction and X-ray two-crystal method.

The electron beam diffraction pattern was streak-like, indicating that a flat, high-quality crystal layer had grown.

Further, the half-width obtained from the diffraction pattern of the X-ray two-crystal method was narrower than that of the conventional high temperature (700° C. or higher) vapor phase growth method without light irradiation.

In the above example, the laser irradiation intensity was set to 5 mj/c+J per pulse on the substrate surface, but this may be sufficient as long as the energy does not cause welding of the substrate.The irradiating light may be an excimer laser beam of other wavelengths, such as KrF. Light (wavelength 248nm
), XeF (wavelength 350 nm), low pressure, high pressure or ultra-high pressure 11g lamp, X5-11g lamp.

It is also possible to use bright lines produced by rare gas microwave discharge, which may be light from a deuterium lamp or the like. Although the growth temperature is not limited to 400°C, a growth temperature of 700°C or less is preferable. The semiconductor crystal to be grown is not limited to GaN,
AQN, InN, GaAQN, InAj! N.

InGaN or FaInAQN may be used, but when epitaxial growth is performed, the substrate and the mixed crystal composition ratio must be selected so that the lattice mismatch between the crystal layer and the substrate is small.

Although the GaN crystal layer obtained in the above example exhibited n-type electrical characteristics, in order to obtain a p-type layer, a gas containing a group Ⅰ or group Ⅰ element may be used as a doping material.

Furthermore, in the above embodiment, a single light beam is irradiated.

Light having a plurality of wavelengths may be irradiated, and the present invention can be implemented with various modifications without departing from the spirit thereof.

(Effects of the Invention) As described above, according to the present invention, irradiation with light promotes the disintegration, surface reaction, and surface migration of N as a feedstock, thereby producing a compound semiconductor or mixed crystal containing N as a constituent element. A semiconductor can be grown at a low temperature, and therefore a high quality semiconductor crystal layer can be grown, and therefore a high quality semiconductor crystal layer can be formed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a crystal growth apparatus for explaining one embodiment of the present invention. 1...Growth container 2.3...Gas inlet 4
... Exhaust system 5 ... Susceptor 6 ... Substrate 7 ... Light introduction window 8 ... Reflection mirror 9 ... Excimer laser lO ... Laser light agent Patent attorney Nori Chika Ken Yudo Matsuyama Mitsuyuki

Claims (2)

[Claims] (1) A method for growing a semiconductor crystal, which comprises irradiating a source gas or a substrate to be grown with light in a vapor phase growth method for a compound semiconductor or a mixed crystal semiconductor having nitrogen (N) as a constituent element. (2) The compound semiconductor is GaN, AlN, InN, and the mixed crystal semiconductor is InGaAlN, AlGaN, InG.
2. The method for vapor phase growth of a semiconductor crystal according to claim 1, wherein the semiconductor crystal is aN.