JP7120598B2 - Aluminum nitride single crystal film and method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to an aluminum nitride single crystal film with excellent crystal quality, a substrate with the single crystal film, and a semiconductor device comprising the single crystal film. The present invention also relates to a manufacturing method and a manufacturing apparatus capable of manufacturing an aluminum nitride single crystal film without ammonia.

In recent years, research and development of high-quality aluminum nitride (hereinafter also referred to as “AlN”) substrates and AlN films have been advanced. Since the AlN film has a large bandgap of 6.0 eV, it is being developed as an ultraviolet/deep ultraviolet light emitting device (LED or laser). Note that deep ultraviolet rays have a wavelength of about 200 nm to about 300 nm. The deep ultraviolet light source is promising in application fields such as the sterilization and medical field (wavelength 270 nm), the environmental field (wavelength 260-320 nm) by high-speed decomposition processing of pollutants, and the information field by high-density optical recording laser (wavelength 250 nm or less). be.

The AlN crystal substrate can keep the defect density of the nitride single crystal epitaxially grown thereon low. For example, in an electronic device having a high Al composition AlGaN channel, crystal growth of a high Al composition AlGaN thin film is performed on an AlN substrate in order to prevent cracks from occurring due to lattice constant mismatch. Thus, high-quality AlN substrates are required to realize high-performance devices. Further, AlN single crystal films are being researched and developed as substrate layers of substrate structures in electronic devices such as nitride crystal semiconductor devices.

Since AlN is a material with a high melting point, crystal growth at a high temperature is desired. Main AlN bulk growth methods include a sublimation method and a hydride vapor phase epitaxy (HVPE) method. In the sublimation method, growth is performed under extremely high temperature conditions (2000° C. or higher), and AlN powder is used as a raw material, so many impurities are mixed. The HVPE process requires an ammonia source gas and produces chlorine gas as a product. These noxious gases are toxic and corrosive and adversely affect the environment.

Metal Organic Vapor Phase Deposition (MOVPE) is well known as a technique for forming an AlN film by epitaxial growth. However, this growth method also uses a large amount of ammonia source gas.

As a result of the prior literature search, the following publicly known literature was found.

Patent Document 1 discloses a technique of growing an AlN single crystal film by a plasma enhanced metal organic chemical vapor deposition (REMOCVD) method without using ammonia gas. In Patent Document 1, an amorphous GaN layer is provided in advance in order to grow an AlN single crystal on a polycrystalline substrate. Further, on the amorphous GaN layer, a gas obtained by plasmatizing a mixed gas of nitrogen gas and hydrogen gas in a plasma generation region and an organometallic gas of group III metal (Al) are supplied to form an AlN single crystal film. growing up. Trimethylaluminum (TMA) is exemplified as an organometallic gas. Further, it is described that the substrate is grown at a low temperature of 100° C. or higher and 800° C. or lower.

Non-Patent Document 1 discloses a method that does not use ammonia gas. In Non-Patent Document 1, a plasma-enhanced atomic layer deposition (PE-ALD) method is performed using an organometallic gas (such as TMA) and a plasma-ized mixed gas of nitrogen gas and hydrogen gas. discloses a technique for forming an AlN layer at 150° C. or more and 300° C. or less.

Non-Patent Document 2 discloses a method that does not use ammonia gas. Non-Patent Document 2 discloses that an AlN film is formed on a sapphire substrate by metal-organic chemical vapor deposition using TMA gas and nitrogen gas. The substrate holder is disclosed to be heated to 1040°C-1115°C. Here, it is reported that the AlN single crystal film was formed only when the inside of the reaction vessel (substrate holder) was coated with the GaN layer. Moreover, it is described that when the temperature is raised to 1000° C. or higher in the presence of hydrogen, the GaN layer becomes unstable and an AlN single crystal film cannot be formed.

Non-Patent Documents 3 and 4 disclose the crystal quality of AlN single crystal films grown by MOCVD or HVPE.

JP 2016-132613 A

Sebastian Goerke, et al., Applied Surface Science, 338, 35-41. (2015) Lundin, et al., Technical Physics Letters, 34, 11, 908-911. (2008) Appl. Phys. Lett. 110, 232102 (2017) Appl. Phys. Express 9, 045501 (2016)

Conventionally, ammonia gas is used in the method of forming an AlN film. Therefore, since toxic gas is to be handled, the structure of the apparatus becomes complicated and there is a problem in terms of cost. Therefore, a method that does not use ammonia gas, that is, an ammonia-free method is desired.

Patent Document 1 and Non-Patent Document 1, which are methods that do not use ammonia gas, propose a method of plasmatizing nitrogen gas and hydrogen gas in order to obtain an AlN film. However, it requires a complicated device structure for plasma generation. In addition, Patent Document 1 requires an amorphous GaN intervening layer, and from the viewpoint of AlN film production, there are problems such as ensuring reproducibility due to the presence of impurities such as Ga and how to attach the intervening layer. There is also the problem of an increase in the number of processes. Also, in Non-Patent Document 1, the obtained AlN film is a polycrystalline film, and there is a problem that it cannot be used for practical use of semiconductor devices.

In Non-Patent Document 2, which is a method that does not use ammonia gas, it is necessary to provide a GaN layer coating in order to obtain an AlN single crystal film. Therefore, a pretreatment process for coating the GaN layer in advance is required, and there is a problem that the number of processes increases.

Sufficiently high-quality AlN single-crystal films are desired as substrate layers for ultraviolet/deep-ultraviolet light-emitting devices and electronic device elements. .

An object of the present invention is to solve these problems, and to provide a high-quality AlN single crystal film and a substrate with the AlN single crystal film. An object of the present invention is to provide a semiconductor device having a substrate with a high-quality AlN single crystal film. An object of the present invention is to provide a manufacturing method for manufacturing a high-quality AlN single crystal film, a substrate with the AlN single crystal film, and a semiconductor device without using ammonia gas. Another object of the present invention is to provide a manufacturing apparatus for manufacturing a high-quality AlN single crystal film without using ammonia gas.

The present invention has the following features in order to achieve the above objects.
(1) It is an aluminum nitride single crystal film, and the half-value width of the rocking curve diffraction peak by X-ray diffraction is 500 arcsec or less for the symmetric (002) peak and 600 arcsec or less for the asymmetric (102) diffraction peak. and a ratio of [half width of asymmetric (102) diffraction peak]/[half width of symmetric (002) diffraction peak] is 1.5 or less.
(2) A substrate with an aluminum nitride single crystal film, comprising a laminated structure of a substrate and the aluminum nitride single crystal film described in (1) above.
(3) A semiconductor device comprising at least a laminated structure of a substrate, the aluminum nitride single crystal film described in (1) above, and a semiconductor layer in that order.
(4) An aluminum nitride single crystal film is formed on a substrate by heating nitrogen gas, hydrogen gas, and an aluminum organometallic gas at a temperature of 1400° C. or higher. Production method.
(5) A method of manufacturing a semiconductor device, comprising forming a semiconductor layer on the aluminum nitride single crystal film formed by the manufacturing method described in (4) above.
(6) A manufacturing apparatus for manufacturing an aluminum nitride single crystal film, comprising: a heating reaction chamber; a gas supply mechanism for supplying nitrogen gas, hydrogen gas, and an aluminum organometallic gas to the heating reaction chamber; A substrate placement mechanism in the reaction chamber, a heating mechanism for heating the gas supplied via the gas supply mechanism and the substrate, a gas exhaust mechanism for exhausting the gas from the heating reaction chamber, and a heating temperature of the heating mechanism and a heating temperature control mechanism for controlling the temperature to 1400° C. or higher.

According to the present invention, a high-quality AlN single crystal film can be realized. In addition, according to the present invention, a high-quality AlN single crystal film can be formed, so that by using it as a substrate layer, the crystallinity of the group III nitride semiconductor layer formed thereon can be improved, and excellent A nitride semiconductor device can be realized.

The method of the present invention does not use ammonia gas, so it is an environmentally friendly method. In addition, according to the method of the present invention, there is no need to handle ammonia gas, which is a poisonous gas, so the manufacturing apparatus does not become complicated. Since the present invention is not a method of supplying nitrogen gas or the like in a plasma state, it does not require a plasma generating mechanism, and the manufacturing apparatus and method are simple.

In the manufacturing method of the present invention, the substrate material for growing the AlN single crystal film is not particularly limited. It is not necessary to deposit other films in advance before depositing the AlN single crystal film. An AlN single crystal film can be deposited directly on the substrate.

In the manufacturing method of the present invention, vapor phase epitaxy is performed at a high temperature of 1400° C. or higher, so an AlN single crystal film can be formed. In particular, when vapor phase growth is performed at a high temperature of 1500° C. or higher, a high-quality AlN single crystal film that could not be realized by other film forming methods can be realized.

1 is a schematic diagram of a substrate with an aluminum nitride single crystal film according to a first embodiment; FIG. 1 is a schematic diagram of an apparatus for manufacturing an aluminum nitride single crystal film according to a first embodiment; FIG. FIG. 4 is a diagram showing results of high-resolution X-ray diffraction ω-2θ measurement in the first embodiment; It is a figure which shows the result of the surface observation with a scanning electron microscope in 1st Embodiment. FIG. 4 is a diagram showing results of measurement by the energy dispersive X-ray spectrometer in the first embodiment; FIG. 4 is a diagram showing observation results of an AlN film surface with an optical microscope in the first embodiment; FIG. 4 is a diagram showing results of high-resolution X-ray diffraction ω-2θ measurement in the first embodiment; FIG. 10 is a diagram of observation results of the AlN film surface with an optical microscope in the second embodiment; 10 shows observation results of the AlN film surface of Comparative Example 1 with an optical microscope in the second embodiment. FIG. 10 is a diagram showing results of high-resolution X-ray diffraction ω-2θ measurement in the third embodiment; FIG. 10 is a diagram showing evaluation results of crystal quality by X-ray diffraction rocking curve measurement in the third embodiment; FIG. 10 is a diagram showing evaluation results of crystal quality by X-ray diffraction rocking curve measurement in the fourth embodiment; FIG. 10 is a diagram showing evaluation results of crystal quality by X-ray diffraction rocking curve measurement in the fourth embodiment; It is a schematic diagram of the basic structure of the ultraviolet/deep ultraviolet light emitting device in the fifth embodiment. It is a schematic diagram of the basic structure of the electronic power device element in 6th Embodiment.

An embodiment of the present invention will be described below.

In the process of researching AlN single crystal films, the present inventors focused on a manufacturing method that does not use an ammonia raw material gas, and conducted intensive research and development to obtain an AlN single crystal film having a high-quality single crystal structure. reached.

In the method for producing an AlN single crystal film according to the embodiment of the present invention, nitrogen gas, hydrogen gas, and an organometallic gas, which is a source gas for Al, which is a Group III metal, are used. AlN is deposited on the substrate by supplying nitrogen gas, hydrogen gas, and organometallic gas onto the substrate while the heating zone including the substrate and the reaction region around the substrate placed in the reaction chamber is heated to a high temperature. A single crystal film is deposited.

The manufacturing apparatus includes a heating reaction chamber, a gas supply mechanism for supplying raw material gas and other gases to the heating reaction chamber, a gas discharge mechanism for discharging gas after reaction from the heating reaction chamber, and a heating reaction chamber. It has at least a substrate setting mechanism for placing a substrate or the like in the chamber, a heating mechanism for heating the substrate and the reaction area in the heating reaction chamber, and a heating control mechanism. Since a plasma generation mechanism is unnecessary, it is not provided. The heating reaction chamber is constructed of a structure and materials suitable for high temperature heat treatment. As the heating reaction chamber, for example, a known heat-resistant heating reaction chamber such as a quartz tube can be used.

An AlN single crystal film can be formed by controlling the heating temperature of the substrate, that is, the high-temperature vapor phase epitaxy temperature to 1400° C. or higher. At a temperature of about 1600° C., an AlN single crystal film with very good crystallinity can be obtained. There is no particular upper limit for the heating temperature. Practically, the upper limit of the heating temperature is preferably about 1800°C. Therefore, the heating temperature is preferably 1400° C. or higher and 1800° C. or lower. When higher quality crystallinity is desired, 1500° C. or higher is preferred. Also, the temperature may be 1800° C. or lower.

Any gas known as an Al organometallic gas can be used as the Al source gas. Examples include trimethylaluminum (TMA), triethylaluminum (TEA), and the like. Nitrogen gas may have a purity of 99.9999% or higher. Hydrogen gas may have a purity of 99.9999% or higher. The amount and ratio of the organometallic gas are not limited. As for the ratio of each gas, it is important to flow at least about 1 slm or more of hydrogen. The pressure in the reaction chamber may be below atmospheric pressure.

The deposited AlN single crystal film is a direct bandgap semiconductor. The thickness of the AlN single crystal film of the present invention is not particularly limited. For example, it is about 0.5 μm or more and 300 μm or less.

The substrate is not particularly limited. Any substrate that has been used for forming an AlN film can be used. Examples thereof include AlN substrates of various plane orientations, AlN template substrates, sapphire substrates, SiC substrates, and various metal substrates.

According to the production method of the present invention, an aluminum nitride single crystal film with very good crystal quality could be produced. In the aluminum nitride single crystal film of the present invention, the half-value width of the diffraction rocking curve peak by X-ray diffraction is 500 arcsec or less for the symmetric (002) peak and 600 arcsec or less for the asymmetric (102) diffraction peak. and the ratio of [half width of asymmetric (102) diffraction peak]/[half width of symmetric (002) diffraction peak] is 1.5 or less. Although the lower limit of the half-value width is not particularly limited, it is, for example, 100 arcsec, and the lower limit of the ratio is about 0.9.

A semiconductor device of the present invention includes at least a laminated structure of a substrate, the aluminum nitride single crystal film of the present invention, and a semiconductor layer in that order. The semiconductor layer includes, for example, various nitride semiconductors, particularly Group III nitride semiconductors. In addition, a semiconductor layer having good crystallinity can be obtained, and a high-quality single crystal layer can be realized.

The semiconductor device of the present invention is produced by heating nitrogen gas, hydrogen gas, and aluminum organometallic gas at a temperature of 1400° C. or higher to form an aluminum nitride single crystal film on a substrate, and then depositing the aluminum nitride single crystal. It can be manufactured by forming a semiconductor layer on the film by another film forming method (MBE method, MOCVD method, etc.).

(First embodiment)
An aluminum nitride single crystal film and its manufacturing method will be described with reference to FIGS. FIG. 1 is a schematic diagram of a substrate 3 with an aluminum nitride single crystal film. A substrate 3 with an aluminum nitride single crystal film is obtained by depositing an aluminum nitride single crystal film 2 on a substrate 1 .

An aluminum nitride single crystal film is grown in an ammonia-free high-temperature gas phase atmosphere. Ammonia gas is not used as a source gas. In the present invention, nitrogen gas is used as source gas. In addition, high-temperature growth (1400° C. or higher) enables production of high-quality AlN single crystal films.

FIG. 2 is a schematic diagram of an example of a manufacturing apparatus used for manufacturing an aluminum nitride single crystal film. The manufacturing apparatus 10 includes a heating reaction chamber 11, gas supply mechanisms 14, 15, and 16 for supplying raw material gas and other gases to the heating reaction chamber 11, and gas exhaust for discharging gas after reaction from the heating reaction chamber 11. A mechanism 17, a substrate placing mechanism for placing a substrate 20 or the like in the heating reaction chamber 11, a heating mechanism 12 for heating a heating zone 13 including the substrate and the reaction region in the heating reaction chamber 11, a heating temperature, etc. It has at least a heating temperature control mechanism that controls the. Since a plasma generation mechanism is unnecessary, it is not provided. The reaction chamber is constructed with a structure and materials suitable for high temperature heat treatment of 1400° C. or higher. As a heating reaction chamber, for example, a quartz tube can be used.

A substrate is placed on the substrate placement mechanism of the reaction chamber. The substrate mounting mechanism is a functional component (also referred to as a “susceptor”) that supports the substrate, and is made of ceramic or the like having excellent strength, heat resistance, corrosion resistance, and the like. Nitrogen gas, hydrogen gas, and an aluminum organometallic gas are supplied to the heating reaction chamber by a gas supply mechanism. While flowing the supplied gas, it is heated to a high temperature by a heating mechanism in the heating zone. The substrate and the heating zone around the substrate are heated so that the raw material gas reacts to form an AlN film on the substrate. Nitrogen gas, hydrogen gas, and organometallic gas of aluminum react to form an AlN single crystal film on the substrate.

[Example 1-1] An AlN single crystal film was formed on a SiC substrate. The 4H—SiC substrate placed on the susceptor in the reaction chamber was heated to 1600° C., and trimethylaluminum (TMA) (20° C., hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing 20 slm of nitrogen gas and 1 slm of hydrogen gas. . The introduction time is 1 hour. The role of hydrogen bubbling is to push the organometallic raw material vapor out of the storage container. The flow rate unit slm is a unit indicating the flow rate per minute at standard liter (liter)/min, 1 atm, and 0° C. in liters. The unit sccm of the flow rate is ccm standardized at a constant temperature such as standard cc/min, 1 atm (atmospheric pressure), 0°C or 25°C.

The films formed were examined by X-ray diffraction measurements. FIG. 3 shows the results of high-resolution X-ray diffraction ω-2θ measurements. The horizontal axis is the angle (deg), and the vertical axis is the intensity of high-resolution X-ray diffraction (HRXRD). As shown in FIG. 3, the 4C-SiC (004) peak used for the substrate is clearly observed, and a very broad shoulder (Broad shoulder in the figure) is observed at the original AlN (002) peak position. rice field. This suggests that the thickness of the AlN film is very thin. The assumed AlN film thickness is several tens of nm or less.

The formed film was observed with a scanning electron microscope. FIG. 4 is a diagram showing the results of surface observation with a scanning electron microscope. As shown in FIG. 4, localized hexagonal islands were observed in addition to the overall uniform surface morphology. This hexagonal island is thicker than the surrounding area. FIG. 5 shows the results of measuring the hexagonal island and its peripheral portion (indicated as “Flat part” in the figure) by an energy dispersive X-ray microanalyzer (EDX). The horizontal axis is energy (unit: keV), and the vertical axis is the intensity obtained by normalizing the EDX spectrum intensity with the Si peak intensity. Al component and N component peaks are observed both in the hexagonal island (indicated by the dotted line) and in its peripheral portion (indicated by the solid line). That is, it was confirmed that a film having nitrogen and Al components was formed in the method using nitrogen gas and TMA as source gases, as in the present embodiment.

[Example 1-2] Next, an AlN film was grown on a c-Al ₂ O ₃ (0001) substrate called sapphire. A sapphire (0001) substrate placed on a susceptor in a reaction chamber was heated to 1600° C., and TMA (20° C., hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing 10 slm of nitrogen gas and 10 slm of hydrogen gas. The introduction time was 2 hours. The film thickness of AlN was about 1 μm. The formed film was observed with an optical microscope. FIG. 6 shows observation results of the AlN film surface with an optical microscope. AlN surface morphology with hexagonal symmetry was observed, as shown in FIG.

The films formed were examined by X-ray diffraction measurements. FIG. 7 shows the results of high-resolution X-ray diffraction ω-2θ measurement. As shown in FIG. 7, the Al ₂ O ₃ (004) diffraction peak used for the substrate was observed, and the AlN (002) diffraction peak was clearly observed. From this result, it can be confirmed that an AlN single crystal is grown.

(Second embodiment)
An aluminum nitride single crystal film and a method for manufacturing the same according to this embodiment will be described with reference to FIGS. In this embodiment mode, the effect of introducing hydrogen gas at the time of film formation will be described.

[Example 2] An AlN template substrate grown by MOCVD on sapphire (0001) was used, and an AlN single crystal film was grown on the AlN template substrate. The AlN template substrate was heated to 1600° C., and TMA (20° C., hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing 10 slm of nitrogen gas and 10 slm of hydrogen gas. The introduction time was 2 hours. The film thickness of AlN was about 1 μm. The formed film was observed with an optical microscope. FIG. 8 shows observation results of the AlN film surface with an optical microscope. As shown in FIG. 8, the growth of the AlN film was confirmed, and the AlN surface morphology with hexagonal symmetry was observed.

[Comparative Example 1] An experiment was conducted under the same conditions as in Example 2 except for the condition that hydrogen gas was not flowed. The AlN template substrate was heated to 1600° C., and TMA (20° C., hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing 20 slm of nitrogen gas and 0 slm of hydrogen gas. The introduction time was 1 hour. FIG. 9 shows the results of observation with an optical microscope. As shown in FIG. 9, it can be seen that the AlN film was hardly grown, and that desorption due to high temperature occurred on the originally flat AlN surface, resulting in the formation of numerous holes on the surface.

From the results of Comparative Example 1, it can be seen that introduction of hydrogen gas is effective in the method of forming an AlN single crystal film according to the present embodiment. This is because the introduction of the hydrogen gas serves to promote the decomposition reaction of the organometallic gas such as TMA.

(Third Embodiment)
An aluminum nitride single crystal film and a method for manufacturing the same according to this embodiment will be described with reference to FIGS. In this embodiment mode, the heating temperature during film formation will be described.

[Example 3] A sapphire (0001) substrate placed on a susceptor in a reaction chamber was heated to 1400°C, and TMA (20°C, hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing 10 slm of nitrogen gas and 10 slm of hydrogen gas. introduced. The introduction time was 2 hours. Since the growth was performed at a temperature of 1400° C., which is lower than in Examples 1 and 2, the film thickness of the deposited AlN was 0.1 μm or less.

The films formed were examined by X-ray diffraction measurements. FIG. 10 shows the results of high-resolution X-ray diffraction ω-2θ measurement. As shown in FIG. 10, a weak AlN (002) diffraction peak was observed along with another plane orientation peak. From this, it can be seen that a single crystal film of AlN is formed. The fact that another plane orientation peak is also observed indicates that nuclei having different plane orientations were simultaneously formed at the crystal nucleation stage in the early stage of growth.

Crystal quality (crystal defects, etc.) of the formed film was evaluated by X-ray diffraction measurement. FIG. 11 is a diagram showing comparison results of X-ray diffraction rocking curve evaluation of AlN films grown at 1400° C. and 1600° C. FIG. The AlN film grown at 1600° C. was the same as Example 3 grown at 1400° C. except for the heating temperature, and the film thickness of the AlN film was about 1 μm. The horizontal axis is the angle Δω (unit: arcsec), and the vertical axis is the normalized X-ray diffraction (XRD) intensity. In the figure, the half width of the (002) peak of the rocking curve is higher for the AlN film grown at 1400° C. (indicated by the solid line in the figure) than for the AlN film grown at 1600° C. (indicated by the dotted line in the figure). very wide. According to FIG. 11, the half width of the symmetrical (002) peak of the AlN film grown at 1400° C. was about 4000 arcsec. AlN films grown at 1400° C. are inferior to AlN films grown at 1600° C. in terms of dislocation density. In other words, it can be seen that the growth temperature greatly affects the film quality (dislocation density, etc.).

(Fourth embodiment)
The crystal quality of the aluminum nitride single crystal film of this embodiment will be described with reference to FIGS. Two AlN single crystal films grown under different manufacturing conditions were prepared to examine the crystal quality.

[Example 4-1] A sapphire (0001) substrate placed on a susceptor in a reaction chamber was heated to 1600°C, and TMA (20°C, hydrogen bubbling gas 100 sccm) was reacted while flowing 5 slm of nitrogen gas and 5 slm of hydrogen gas. introduced into the room. Growth time is 2 hours. The film thickness of AlN was about 1 μm.

[Example 4-2] A sapphire (0001) substrate placed on a susceptor in a reaction chamber was heated to 1600°C, and TMA (20°C, hydrogen bubbling gas 100sccm) was reacted while flowing 10slm of nitrogen gas and 10slm of hydrogen gas. introduced into the room. Growth time is 2 hours. The film thickness of AlN was about 1 μm.

AlN crystal quality was evaluated by X-ray diffraction measurement. In the case of X-ray diffraction measurement, a diffraction peak of the plane appears for a certain plane orientation. The growth direction of the AlN film is the c-plane, that is, the direction of the (002) plane, so it is called a plane of six-fold symmetry. An X-ray diffraction peak emerging from this (002) plane is called a "symmetrical (002) peak". On the other hand, planes other than the (002) plane of symmetry are called "asymmetric planes". Since the (102) plane was selected for the X-ray diffraction rocking curve measurements in FIGS. 12 and 13, the X-ray diffraction peaks emanating from this plane are called "asymmetric (102) peaks".

FIG. 12 is a diagram showing evaluation results of crystal quality of the AlN film formed in [Example 4-1] by X-ray diffraction rocking curve measurement. The horizontal axis is the angle Δω (unit: arcsec), and the vertical axis is the normalized X-ray diffraction (XRD) intensity. In the figure, symmetrical (002) diffraction is represented by a dotted line, and asymmetrical (102) diffraction is represented by a solid line. In the figure, the half width of the X-ray rocking curve diffraction peak (also referred to as “FWHM (full width at half maximum)”) is 480 arcsec for the symmetric (002) peak, and 480 arcsec for the asymmetric (102) diffraction. The half width of the peak is 560 arcsec. The half-width ratio of the asymmetric (102) diffraction peak to the symmetric (002) diffraction peak is 1.17.

FIG. 13 is a diagram showing evaluation results of the crystal quality of the AlN film formed in [Example 4-2] by X-ray diffraction rocking curve measurement. In the figure, symmetrical (002) diffraction is represented by a dotted line, and asymmetrical (102) diffraction is represented by a solid line. In the figure, the half-value width of the X-ray rocking curve diffraction peak is 358 arcsec for the symmetric (002) diffraction peak and 521 arcsec for the asymmetric (102) diffraction peak. The half-width ratio of the asymmetric (102) diffraction peak to the symmetric (002) diffraction peak is 1.46.

In general, the half width of the X-ray diffraction peak correlates with the dislocations present in the thin film and serves as an evaluation index of the dislocation density. The FWHM of the symmetric (002) diffraction peak corresponds to the screw dislocation, and the FWHM of the asymmetric (102) diffraction peak corresponds to the edge dislocation and the mixed dislocation. That is, the half-value width of the symmetric (002) diffraction peak and the half-value width of the asymmetric (102) diffraction peak represent the degree of tilt and twist of the lattice arrangement in the crystal, respectively. A wide half width indicates a high dislocation density. As in the AlN thin film of this embodiment, the fact that the difference between the half-width of the symmetrical (002) diffraction peak and the half-width of the asymmetrical (102) diffraction peak is small indicates that the crystal structure disorder is small. It is considered that the reason why crystals with a small difference between the two can be obtained like the AlN film of the present embodiment is that the AlN single crystal film can be grown by high temperature growth in the present manufacturing method.

From the above results, the aluminum nitride single crystal film of the present embodiment has a diffraction peak half width of 500 arcsec or less, a symmetric (002) diffraction peak half width of 500 arcsec or less, and an asymmetric (102) diffraction peak half width of 500 arcsec or less. is 600 arcsec or less, and the ratio of [half width of asymmetric (102) diffraction peak]/[half width of symmetric (002) diffraction peak] is 1.5 or less.

The properties of the aluminum nitride single crystal film of this embodiment are significantly different from those of AlN thin films obtained by other growth methods. Other growth methods have not yielded single crystal films with the above characteristics. For example, in the MOCVD growth method, an example of narrow X-ray half width (002): about 200 arcsec and (102): about 500 arcsec for an AlN thin film with a thickness of about 3 μm is disclosed. However, from these values, the ratio is quite large at 2.5 (see Non-Patent Document 3). Further, in the HVPE growth method, a wide example of X-ray half width (002): about 697 arcsec and (102): about 852 arcsec of a thick AlN thin film with a film thickness of about 5 μm is disclosed (see Non-Patent Document 4).

(Fifth embodiment)
In this embodiment mode, a semiconductor element using a substrate with an aluminum nitride single crystal film will be described with reference to FIGS. FIG. 14 shows a schematic diagram of the basic structure of an ultraviolet/deep ultraviolet light emitting device. As shown in FIG. 14, the ultraviolet/deep ultraviolet light emitting device 30 includes a laminate of a substrate 31, an AlN layer 32, an n-type AlGaN layer 33, a light emitting layer 34 containing (Ga, Al, In)N, and a p-type AlGaN layer 35. It has a sequential laminated structure. In the ultraviolet/deep-ultraviolet light-emitting device, the composition of each element in the light-emitting layer 34 differs depending on the emission wavelength. It is a condition. As the AlN layer 32, the high crystal quality AlN single crystal film shown in the embodiment of the present invention is used. This improves the crystal quality of a semiconductor layer such as a high Al composition AlGaN film grown on the AlN single crystal film. As a result, it is possible to realize an ultraviolet/deep ultraviolet light emitting device having excellent characteristics such as high internal quantum efficiency. A semiconductor device structure on the AlN single crystal film is produced by a known epitaxial growth method (molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), etc.).

(Sixth embodiment)
In this embodiment mode, a semiconductor element using a substrate with an aluminum nitride single crystal film will be described with reference to FIGS. FIG. 15 shows a schematic diagram of the basic structure of the electronic power device element. As shown in FIG. 15, the electronic power device element 40 has a laminated structure of a substrate 41, an AlN layer 42, an Al _x Ga _1-x N buffer layer 43, and an Al _y Ga _1-y N barrier layer 44 in the order of lamination. . In the case of an electronic power device element, the condition is that the Al composition of the AlGaN buffer layer 43 is smaller than the Al composition of the AlGaN barrier layer 44 (y>x). As the AlN layer 42, the high crystal quality AlN single crystal film shown in the embodiment of the present invention is used. This improves the crystal quality of a semiconductor layer such as an AlGaN film grown on the AlN single crystal film. As a result, an electronic power device element having excellent properties such as high-temperature durability can be realized. A semiconductor device structure on the AlN single crystal film is manufactured by a known epitaxial growth method.

It should be noted that the examples shown in the above embodiments and the like are described to facilitate understanding of the invention, and the invention is not limited to this form.

Since the method for producing an aluminum nitride single crystal film of the present invention does not use ammonia gas and does not require handling of toxic gas, the production method and production apparatus are industrially useful. Moreover, since the aluminum nitride single crystal film of the present invention has excellent crystal quality, it can be widely used for light-emitting devices, electronic power device devices, and the like, and is industrially useful.

Reference Signs List 1, 31, 41 substrate 2 aluminum nitride single crystal film 3 substrate with aluminum nitride single crystal film 10 manufacturing apparatus 11 heating reaction chamber 12 heating mechanism 13 heating zone 14, 15, 16 gas supply mechanism 17 gas discharge mechanism 30 ultraviolet/deep ultraviolet Light-emitting element 32, 42 AlN layer 33 n-type AlGaN layer 34 light-emitting layer containing (Ga, Al, In)N 35 p-type AlGaN layer 40 electronic power device element 43 Al _x Ga _1-x N buffer layer 44 Al _y Ga _{1 -y} N barrier layer

Claims (3)

What is claimed is: 1. A method for producing an aluminum nitride single crystal film, comprising heating nitrogen gas, hydrogen gas, and an aluminum organometallic gas at a temperature of 1400° C. or higher to form an aluminum nitride single crystal film on a substrate. The half-value width of the rocking curve diffraction peak by X-ray diffraction of the aluminum nitride single crystal film is such that the half-value width of the symmetric (002) peak is 500 arcsec or less, and the half-value width of the asymmetric (102) diffraction peak is 600 arcsec or less. 2. The method for producing an aluminum nitride single crystal film according to claim 1, wherein the ratio of (102) diffraction peak half width]/[symmetric (002) diffraction peak half width] is 1.5 or less. 3. A method of manufacturing a semiconductor device, comprising forming a semiconductor layer on the aluminum nitride single crystal film formed by the manufacturing method according to claim 1 or 2 .

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