JP2019151523A - Aluminium nitride single crystal film, substrate having the same, semiconductor element, manufacturing method and manufacturing apparatus - Google Patents

Abstract

To provide: a method and apparatus for forming an aluminium nitride single crystal film without using ammonia gas; a high quality aluminium nitride single crystal film; a substrate having the single crystal film; and a semiconductor element including the single crystal film.SOLUTION: The manufacturing method capable of depositing an aluminium nitride single crystal film on a substrate is achieved by heating nitrogen gas, hydrogen gas and aluminium organic metal gas at a temperature of 1400°C or more. The aluminium nitride single crystal film obtained by the manufacturing method has: the half value width of a rocking curve diffraction peak by X-ray diffraction having 500 arcsec or less of the half value width of a symmetric (002) peak and 600 arcsec or less of the half value width of an asymmetric (102) diffraction peak; and 1.5 or less of the ratio of [the half value width of the asymmetric (102) diffraction peak]/[the half value width of the symmetry (002) diffraction peak].SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aluminum nitride single crystal film having excellent crystal quality, the substrate with the single crystal film, and a semiconductor element including 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 free of ammonia.

  In recent years, research and development of high-quality aluminum nitride (hereinafter also referred to as “AlN”) substrates and AlN films have been promoted. Since the AlN film has a large band gap of 6.0 eV, it has been developed as an ultraviolet / deep ultraviolet light emitting element (LED or laser). In addition, deep ultraviolet means a wavelength of about 200 nm to about 300 nm. Deep ultraviolet light source is promising in application fields such as sterilization / medical field (wavelength 270 nm), environment field (wavelength 260-320 nm) by high-speed decomposition treatment of pollutants, and information field (wavelength 250 nm or less) by high-density optical recording laser. is there.

  The substrate of the AlN crystal 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, a high Al composition AlGaN thin film is grown on an AlN substrate in order to prevent the occurrence of cracks due to lattice constant mismatch. Thus, a high quality AlN substrate is required to realize a high performance device. In addition, an AlN single crystal film has been researched and developed as a substrate layer of a substrate structure in an electronic device such as a nitride crystal semiconductor element.

  Since AlN is a high melting point material, crystal growth at a high temperature is desired. As main AlN bulk growth methods, there are a sublimation method and a hydride vapor phase epitaxy (HVPE) method. In the sublimation method, growth is performed under extremely high temperature (2000 ° C. or higher) conditions, and AlN powder is used as a raw material. In the HVPE method, ammonia source gas is required, and chlorine gas is generated in the product. These toxic gases are toxic and corrosive and have a negative impact on the environment.

  As a technique for forming an AlN film by epitaxial growth, metal organic vapor phase deposition (MOVPE) is well known. However, this growth method also uses a large amount of ammonia source gas.

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

  Patent Document 1 discloses a technique for 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, a gas obtained by converting a mixed gas of nitrogen gas and hydrogen gas into a plasma and an organometallic gas of a group III metal (Al) are supplied on the amorphous GaN layer to form an AlN single crystal film. Growing up. Trimethylaluminum (TMA) is exemplified as the 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 using an organic metal gas (TMA or the like) and a mixed gas in which nitrogen gas and hydrogen gas are converted into plasma. 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 vapor phase epitaxy using TMA gas and nitrogen gas. It is disclosed that the substrate holder is heated to 1040 ° C-1115 ° C. Here, it is reported that an AlN single crystal film is formed only when a GaN layer coating is performed in the reaction vessel (substrate holder). Further, it is described that when the temperature is increased to 1000 ° C. or more 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 an AlN single crystal film grown by MOCVD or HVPE.

Japanese Patent Laid-Open No. 2006-132613

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

  Conventionally, ammonia gas is used in a method of forming an AlN film. Therefore, since toxic gas is handled, the structure of the apparatus is 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 converting nitrogen gas and hydrogen gas into plasma in order to obtain an AlN film. However, it requires a complicated device structure for plasma generation. Moreover, in Patent Document 1, an amorphous GaN intervening layer is required, and there is a problem of ensuring reproducibility due to a mixture of impurities such as Ga and the method of attaching the intervening layer from the viewpoint of manufacturing an AlN film. There is also a drawback that the number of processes increases. Further, in Non-Patent Document 1, the obtained AlN film is a polycrystalline film and has a drawback that it cannot be used for practical use of a semiconductor device.

  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. For this reason, a pretreatment process for coating the GaN layer in advance is required, which increases the number of processes.

  A sufficiently high quality AlN single crystal film is desired as a substrate layer for ultraviolet / deep ultraviolet light-emitting elements and electronic device elements, but the prior art document cannot realize a high quality single crystal film as in the present invention. .

  The present invention is intended to solve these problems, and an object thereof is to provide a high-quality AlN single crystal film and a substrate with the AlN single crystal film. An object of this invention is to provide a semiconductor element provided with a high quality substrate with an 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 element 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 object.
(1) An aluminum nitride single crystal film having a half-width of a rocking curve diffraction peak by X-ray diffraction, a half-width of a symmetric (002) peak of 500 arcsec or less, and a half-width of an asymmetric (102) diffraction peak of 600 arcsec or less 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 the substrate and the aluminum nitride single crystal film according to (1).
(3) A semiconductor device comprising at least a laminated structure in the order of a substrate, the aluminum nitride single crystal film according to (1), and a semiconductor layer.
(4) An aluminum nitride single crystal film is formed on a substrate by heating nitrogen gas, hydrogen gas, and an organometallic gas of aluminum at a temperature of 1400 ° C. or higher. Production method.
(5) A method for manufacturing a semiconductor device, comprising forming a semiconductor layer on the aluminum nitride single crystal film formed by the manufacturing method according to (4).
(6) A manufacturing apparatus for manufacturing an aluminum nitride single crystal film, a heating reaction chamber, a gas supply mechanism for supplying nitrogen gas, hydrogen gas, and an organometallic gas of aluminum to the heating reaction chamber, and the heating A substrate mounting mechanism in the reaction chamber, a gas supplied via the gas supply mechanism and a heating mechanism for heating the substrate, a gas discharge mechanism for exhausting 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, since a high-quality AlN single crystal film can be formed, by using it as a substrate layer, the crystallinity of a group III nitride semiconductor layer or the like to be formed thereon can be improved. A nitride semiconductor device can be realized.

  Since the method of the present invention does not use ammonia gas, it is an environmentally friendly method. Further, according to the method of the present invention, it is not necessary to handle ammonia gas which is a toxic gas, so that the manufacturing apparatus is not complicated. Since the present invention is not a method of supplying nitrogen gas or the like in a plasma state, a plasma generating mechanism is not required, and the manufacturing apparatus and method are simple.

  In the manufacturing method of the present invention, the substrate material on which the AlN single crystal film is grown is not particularly limited. There is no need to form another film in advance before forming the AlN single crystal film. An AlN single crystal film can be directly formed on a substrate.

  In the manufacturing method of the present invention, since vapor phase growth is performed at a high temperature of 1400 ° C. or higher, 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 cannot be realized by other conventional film forming methods can be realized.

It is a schematic diagram of the board | substrate with an aluminum nitride single crystal film in 1st Embodiment. It is a schematic diagram of the manufacturing apparatus of the aluminum nitride single crystal film in 1st Embodiment. It is a figure which shows the result of the high-resolution X-ray-diffraction omega-2theta measurement in 1st Embodiment. It is a figure which shows the result of the surface observation by a scanning electron microscope in 1st Embodiment. It is a figure which shows the result measured with the energy dispersive X-ray analyzer in 1st Embodiment. It is a figure which shows the observation result of the AlN film | membrane surface by an optical microscope in 1st Embodiment. It is a figure which shows the result of the high-resolution X-ray-diffraction omega-2theta measurement in 1st Embodiment. It is a figure of the observation result of the AlN film | membrane surface by the optical microscope in 2nd Embodiment. It is an observation result of the AlN film | membrane surface of the comparative example 1 by the optical microscope in 2nd Embodiment. It is a figure which shows the result of the high-resolution X-ray-diffraction omega-2theta measurement in 3rd Embodiment. It is a figure which shows the evaluation result of the crystal quality by X-ray diffraction rocking curve measurement in 3rd Embodiment. It is a figure which shows the evaluation result of the crystal quality by X-ray diffraction rocking curve measurement in 4th Embodiment. It is a figure which shows the evaluation result of the crystal quality by X-ray diffraction rocking curve measurement in 4th Embodiment. It is a schematic diagram of the basic structure of the ultraviolet / deep ultraviolet light emitting element in the fifth embodiment. It is a schematic diagram of the basic structure of the electronic power device element in 6th Embodiment.

  Embodiments of the present invention will be described below.

  In the process of studying the AlN single crystal film, the present inventors have conducted intensive research and development focusing on a manufacturing method that does not use ammonia source gas, and obtain an AlN single crystal film having a high-quality single crystal structure. It reached.

  In the method of manufacturing an AlN single crystal film according to the embodiment of the present invention, nitrogen gas that is a source gas, hydrogen gas, and an organometallic gas that is a source gas of Al that is a group III metal are used. A heating zone including a substrate disposed in the reaction chamber and a reaction region around the substrate is heated to a high temperature, and nitrogen gas, hydrogen gas, and organometallic gas are supplied onto the substrate to thereby generate AlN on the substrate. A single crystal film is formed.

  The manufacturing apparatus includes a heating reaction chamber, a gas supply mechanism for supplying a source gas and other gases to the heating reaction chamber, a gas discharge mechanism for discharging the reacted gas from the heating reaction chamber, and a heating reaction. It has at least a substrate installation mechanism for placing a substrate or the like in the room, a heating mechanism for heating the substrate and the reaction region 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 composed of a structure and material suitable for high-temperature heat treatment. Examples of the heating reaction chamber include a known heat-resistant heating reaction chamber such as a quartz tube.

  An AlN single crystal film can be formed by controlling the heating temperature of the substrate, that is, the high temperature vapor phase growth temperature to 1400 ° C. or higher. At a temperature of about 1600 ° C., an AlN single crystal film having excellent crystallinity can be obtained. There is no particular upper limit on the heating temperature. Actually, 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 preferable. Moreover, 1800 degrees C or less may be sufficient.

  The organometallic gas that is the source gas of Al can be used as long as it is a gas known as the organometallic gas of Al. Examples thereof include trimethylaluminum (TMA) and triethylaluminum (TEA). Examples of the nitrogen gas include those having a purity of 99.9999% or more. Examples of the hydrogen gas include those having a purity of 99.9999% or more. The amount and ratio of the organometallic gas is not limited. As for the ratio of each gas, it is important to flow hydrogen at least about 1 slm. The pressure in the reaction chamber may be not more than atmospheric pressure.

  The formed AlN single crystal film is a direct transition 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 to form an AlN film is possible. For example, AlN substrates of various plane orientations, AlN template substrates, sapphire substrates, SiC substrates, various metal substrates, and the like can be given.

  According to the production method of the present invention, an aluminum nitride single crystal film having a very good crystal quality could be produced. The aluminum nitride single crystal film of the present invention has a half-width of a diffraction rocking curve peak by X-ray diffraction, a half-width of a symmetric (002) peak of 500 arcsec or less, and a half-width of an asymmetric (102) diffraction peak of 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 lower limit of the full width at half maximum is not particularly limited, but is, for example, 100 arcsec, and the lower limit of the ratio is about 0.9.

  The semiconductor element of the present invention includes at least a laminated structure of a substrate, an aluminum nitride single crystal film of the present invention, and a semiconductor layer in this order. Examples of the semiconductor layer include various nitride semiconductors, particularly group III nitride semiconductors. Further, as the semiconductor layer, a layer with good crystallinity can be obtained, and a high-quality single crystal layer can be realized.

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

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

  An aluminum nitride single crystal film is grown in a high temperature gas phase atmosphere free from ammonia. As source gas, ammonia gas is not used. In the present invention, nitrogen gas is used as a raw material gas. Further, since high temperature growth (1400 ° C. or higher) is possible, a high quality AlN single crystal film can be manufactured.

  FIG. 2 is a schematic view 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 that supply raw material gas and other gases to the heating reaction chamber 11, and gas discharge that discharges the reacted gas from the heating reaction chamber 11. A mechanism 17; a substrate placement mechanism for placing the substrate 20 or the like in the heating reaction chamber 11; a heating mechanism 12 for heating the heating zone 13 including the substrate and the reaction region in the heating reaction chamber 11; At least a heating temperature control mechanism for controlling the temperature. Since a plasma generation mechanism is unnecessary, it is not provided. The reaction chamber is composed of a structure and material suitable for high-temperature heat treatment at 1400 ° C. or higher. An example of the heating reaction chamber is a quartz tube.

  A substrate is placed on the substrate mounting mechanism in the reaction chamber. The substrate mounting mechanism is a functional component (also referred to as “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 organometallic gas of aluminum are supplied to the heating reaction chamber by a gas supply mechanism. While flowing the supplied gas, it is heated at a high temperature by a heating mechanism in a heating zone. The substrate and the heating zone around the substrate are heated so that the source 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 nitrogen gas 20 slm and hydrogen gas 1 slm. . The introduction time is 1 hour. The role of hydrogen bubbling is to push the organometallic source vapor out of the storage vessel. The unit slm of the flow rate is a unit in which the flow rate per minute at standard liter (liter) / min, 1 atm, 0 ° C. is expressed in liters. The unit sccm of the flow rate is ccm normalized at a constant temperature such as standard cc / min, 1 atm (atmospheric pressure), 0 ° C. or 25 ° C.

  The formed film was examined by X-ray diffraction measurement. FIG. 3 is a diagram showing the results of high-resolution X-ray diffraction ω-2θ measurement. The horizontal axis represents the angle (deg), and the vertical axis represents 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 originally observed at the AlN (002) peak position. It was. 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 by a scanning electron microscope. As shown in FIG. 4, in addition to the uniform surface morphology, a hexagonal island was locally observed. This hexagonal island is thicker than the surrounding area. FIG. 5 shows the results of measuring the hexagonal island and its peripheral part (indicated as “Flat part” in the figure) with an energy dispersive X-ray analyzer (EDX). The horizontal axis represents energy (unit: keV), and the vertical axis represents EDX spectrum intensity normalized by Si peak intensity. Al component and N component peaks are observed on both the hexagonal island (indicated by a dotted line) and its peripheral part (indicated by a solid line). That is, formation of a film having a nitrogen component and an Al component was confirmed in the method using nitrogen gas, which is a raw material gas, and TMA 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. The sapphire (0001) substrate placed on the susceptor in the reaction chamber was heated to 1600 ° C., and TMA (20 ° C., hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber while flowing nitrogen gas 10 slm and hydrogen gas 10 slm. 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 the results of observation of the AlN film surface with an optical microscope. As shown in FIG. 6, a hexagonal symmetrical AlN surface morphology was observed.

The formed film was examined by X-ray diffraction measurement. FIG. 7 is a diagram showing 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 the AlN single crystal is grown.

(Second Embodiment)
An aluminum nitride single crystal film and a manufacturing method thereof according to the present embodiment will be described with reference to FIGS. In this embodiment mode, an 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 nitrogen gas 10 slm and hydrogen gas 10 slm. 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 the results of observation of the AlN film surface with an optical microscope. As shown in FIG. 8, the growth of the AlN film was confirmed, and a hexagonal symmetrical AlN surface morphology was observed.

  [Comparative Example 1] An experiment was performed under the same conditions as in Example 2 except that hydrogen gas was not supplied. 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 nitrogen gas 20 slm and hydrogen gas 0 slm. 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 AlN film is hardly grown, and desorption due to high temperature occurs on the originally flat AlN surface, and a large number of holes are formed 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 in the present embodiment. This is because the introduction of hydrogen gas serves to promote the decomposition reaction of organometallic gases such as TMA.

(Third embodiment)
An aluminum nitride single crystal film and a manufacturing method thereof according to the present embodiment will be described with reference to FIGS. In this embodiment mode, a heating temperature at the time of 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 while flowing nitrogen gas 10 slm and hydrogen gas 10 slm, TMA (20 ° C, hydrogen bubbling gas 100 sccm) was introduced into the reaction chamber. Introduced. The introduction time was 2 hours. Since the growth was at a low temperature of 1400 ° C. compared to Examples 1 and 2, the film thickness of the deposited AlN was 0.1 μm or less.

  The formed film was examined by X-ray diffraction measurement. FIG. 10 is a diagram showing the results of high-resolution X-ray diffraction ω-2θ measurement. As shown in FIG. 10, a weak AlN (002) diffraction peak was observed, and another plane orientation peak was also observed. This shows 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 stage of crystal nucleation in the early stage of growth.

  The crystal quality (crystal defects, etc.) of the formed film by X-ray diffraction measurement was evaluated. FIG. 11 is a diagram showing a comparison result 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. had the same conditions as Example 3 grown at 1400 ° C. except for the heating temperature, and the film thickness of the deposited AlN was about 1 μm. The horizontal axis is the angle Δω (unit: arcsec), and the vertical axis is the intensity of normalized X-ray diffraction (XRD). In the figure, the AlN film (shown by a solid line in the figure) having a half-width of the (002) peak of the rocking curve grown at 1400 ° C. is better than the AlN film (shown by a dotted line in the figure) grown at 1600 ° C. Very wide. According to FIG. 11, the FWHM of the symmetrical (002) peak of the AlN film grown at 1400 ° C. was about 4000 arcsec. The AlN film grown at 1400 ° C. is inferior to the AlN film grown at 1600 ° C. in terms of dislocation density. That is, 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 the present embodiment will be described with reference to FIGS. Two AlN single crystal films grown under different production conditions were prepared, and the crystal quality was examined.

  [Example 4-1] A sapphire (0001) substrate placed on a susceptor in a reaction chamber is heated to 1600 ° C., and TMA (20 ° C., hydrogen bubbling gas 100 sccm) is reacted while flowing 5 slm of nitrogen gas and 5 slm of hydrogen gas. Introduced into the room. The 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 100 sccm) was reacted while flowing 10 slm of nitrogen gas and 10 slm of hydrogen gas. Introduced into the room. The growth time is 2 hours. The film thickness of AlN was about 1 μm.

  The AlN crystal quality was evaluated by X-ray diffraction measurement. In the case of X-ray diffraction measurement, a diffraction peak of the surface appears for a specific surface orientation. Since the direction of the c-plane, that is, the (002) plane of the AlN film is the growth direction, it is called a six-fold symmetry plane. This X-ray diffraction peak emerging from the (002) plane is called a “symmetric (002) peak”. On the other hand, planes other than the (002) plane of symmetry are called “asymmetric planes”. In the X-ray diffraction rocking curve measurement of FIGS. 12 and 13, since the (102) plane is selected, the X-ray diffraction peak emitted from this plane is called an “asymmetric (102) peak”.

  FIG. 12 is a diagram showing the evaluation results of the 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 intensity of normalized X-ray diffraction (XRD). In the figure, symmetric (002) diffraction is represented by a dotted line, and asymmetric (102) diffraction is represented by a solid line. In the figure, the full width at half maximum of the X-ray rocking curve diffraction peak (also referred to as “FWHM (full width at half maximum)”) is a symmetric (002) peak at 480 arcsec and asymmetric (102) diffraction. The half width of the peak is 560 arcsec. The ratio of the half width of the asymmetric (102) diffraction peak to the symmetric (002) diffraction peak is 1.17.

  FIG. 13 is a diagram showing the 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, symmetric (002) diffraction is represented by a dotted line, and asymmetric (102) diffraction is represented by a solid line. In the figure, the half width of the X-ray rocking curve diffraction peak is 358 arcsec for the symmetric (002) peak and 521 arcsec for the asymmetric (102) diffraction peak. The ratio of the half width of the asymmetric (102) diffraction peak to the symmetric (002) diffraction peak is 1.46.

  In general, the full width at half maximum of the X-ray diffraction peak correlates with dislocations existing in the thin film, and becomes an evaluation index of dislocation density. The half width of the symmetric (002) diffraction peak corresponds to the screw dislocation, and the half width of the asymmetric (102) diffraction peak corresponds to the edge dislocation and mixed dislocation. That is, the half width of the symmetric (002) diffraction peak and the half 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-value width indicates a high dislocation density. A small difference between the FWHM of the symmetric (002) diffraction peak and the FWHM of the asymmetric (102) diffraction peak as in the AlN thin film of the present embodiment indicates that the structural disorder of the crystal is small. The reason why a crystal having a small difference between the two can be obtained as in the AlN film of the present embodiment is considered to be that AlN single crystal film growth by high-temperature growth can be realized in this manufacturing method.

  From the above results, the aluminum nitride single crystal film of the present embodiment has a half-value width of the diffraction peak by X-ray diffraction, a half-value width of the symmetric (002) peak of 500 arcsec or less, and a half-value width of the asymmetric (102) diffraction peak. Is less than or equal to 600 arcsec, and the ratio of [half-width of asymmetric (102) diffraction peak] / [half-width of symmetric (002) diffraction peak] is 1.5 or less.

  The aluminum nitride single crystal film of the present embodiment is greatly different from the characteristics of an AlN thin film obtained by other growth methods. In other growth methods, a single crystal film having the above-described characteristics has not been obtained. For example, in the MOCVD growth method, a narrow example of an AlN thin film with a film thickness of about 3 μm, such as a narrow X-ray half width (002): about 200 arcsec and (102): about 500 arcsec, is disclosed. However, from these values, the ratio is considerably large at 2.5 (see Non-Patent Document 3). Further, in the HVPE growth method, a wide example is disclosed in which the X-ray half width (002): about 697 arcsec and (102): 852 arcsec of a thick AlN thin film having a thickness of about 5 μm (see Non-Patent Document 4).

(Fifth embodiment)
In this embodiment, a semiconductor element using a substrate with an aluminum nitride single crystal film is described with reference to FIGS. FIG. 14 shows a schematic diagram of the basic structure of an ultraviolet / deep ultraviolet light emitting element. As shown in FIG. 14, the ultraviolet / deep ultraviolet light emitting element 30 includes 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 element, the composition of each element of the light emitting layer 34 varies depending on the light emission wavelength, but the Al composition of the upper and lower AlGaN layers (33, 35) may not be smaller than the Al composition in the light emitting layer 34. 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 high characteristics such as high internal quantum efficiency. The semiconductor element 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, a semiconductor element using a substrate with an aluminum nitride single crystal film is 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 stacked structure in the stacking order 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 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. Thereby, the crystal quality of a semiconductor layer such as an AlGaN film grown on the AlN single crystal film is improved. As a result, an electronic power device element having excellent characteristics such as high-temperature durability can be realized. The semiconductor element structure on the AlN single crystal film is produced by a known epitaxial growth method.

  In addition, the example shown by the said embodiment etc. was described in order to make invention easy to understand, and is not limited to this form.

  Since the manufacturing method of the aluminum nitride single crystal film of the present invention is a method that does not use ammonia gas and does not need to handle toxic gas, the manufacturing method and manufacturing 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 elements, electronic power device elements, and the like, and is industrially useful.

DESCRIPTION OF SYMBOLS 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 Light emitting layer containing n-type AlGaN layer 34 (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 (6)

An aluminum nitride single crystal film,
The half-value width of the rocking curve diffraction peak by X-ray diffraction 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. A ratio of [value width] / [half-value width of symmetric (002) diffraction peak] is 1.5 or less.   A substrate with an aluminum nitride single crystal film, comprising a laminated structure of the substrate and the aluminum nitride single crystal film according to claim 1.   A semiconductor element comprising at least a laminated structure of a substrate, the aluminum nitride single crystal film according to claim 1, and a semiconductor layer in this order.   A method for producing an aluminum nitride single crystal film, comprising forming an aluminum nitride single crystal film on a substrate by heating nitrogen gas, hydrogen gas, and an organometallic gas of aluminum at a temperature of 1400 ° C. or higher.   A semiconductor element manufacturing method, comprising: forming a semiconductor layer on the aluminum nitride single crystal film formed by the manufacturing method according to claim 4. A manufacturing apparatus for manufacturing an aluminum nitride single crystal film,
A heated reaction chamber;
A gas supply mechanism for supplying nitrogen gas, hydrogen gas, and organometallic gas of aluminum to the heating reaction chamber;
A substrate mounting mechanism in the heating reaction chamber;
A heating mechanism for heating the gas and the substrate supplied via the gas supply mechanism;
A gas discharge mechanism for exhausting gas from the heating reaction chamber;
A heating temperature control mechanism for controlling the heating temperature of the heating mechanism to 1400 ° C. or higher;
A manufacturing apparatus comprising at least

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