A method for inspecting a gallium nitride-based semiconductor film, a method for manufacturing a gallium nitride-based semiconductor device equipped therewith, and a multilayer structure used therein.

Abstract

One of the objectives of this invention is to easily determine the cause when the crystallinity of a gallium nitride-based semiconductor film formed on a crystal orientation layer is not high. [Solution] A method for inspecting a gallium nitride semiconductor film, comprising: preparing a laminated structure including a substrate and a crystal orientation region and a crystalline region disposed on the substrate; forming a gallium nitride semiconductor film in the crystal orientation region and the crystalline region, respectively; and evaluating the crystallinity of the gallium nitride semiconductor film formed in the crystal orientation region and the crystalline region, respectively.

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting a gallium nitride-based semiconductor film, a method for manufacturing a gallium nitride-based semiconductor device equipped therewith, and a laminated structure used therein. [Background technology]

[0002] Gallium nitride (GaN) semiconductors are characterized by being direct transition semiconductors with a large bandgap. Taking advantage of these characteristics, light-emitting diodes (LEDs) using gallium nitride semiconductors have already been put into practical use. Furthermore, gallium nitride semiconductors also possess high electron saturation mobility and breakdown voltage. In recent years, these characteristics have been utilized in the development of transistors for high-frequency power device applications. Generally, gallium nitride semiconductor films for light-emitting diodes or transistors are deposited on sapphire substrates at high temperatures of 800°C to 1000°C using MOCVD (Metal Organic Chemical Vapor Deposition) or HVPE (Hydride Vapor Phase Epitaxy).

[0003] Another method for depositing gallium nitride-based semiconductor films at low temperatures is sputtering. In sputtering, for example, a laminated structure is prepared in which a crystal orientation layer that improves the crystal growth of the gallium nitride-based semiconductor is placed on the substrate, and the gallium nitride-based semiconductor is deposited on this crystal orientation layer to obtain a gallium nitride-based semiconductor film with good crystallinity. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 8791474 [Patent Document 2] U.S. Patent Application Publication No. 2020 / 0075664 [Patent Document 3] International Publication No. 2022 / 210401 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, when the crystallinity of a gallium nitride-based semiconductor film formed on this crystal orientation layer was not high, it was difficult to determine whether this was due to sputtering of the gallium nitride-based semiconductor or to the crystal orientation layer.

[0006] Therefore, one of the objectives of the present invention is to easily determine the cause when the crystallinity of a gallium nitride-based semiconductor film formed on a crystal orientation layer is not high. [Means for solving the problem]

[0007] A method for inspecting a gallium nitride-based semiconductor film according to one embodiment of the present invention comprises: preparing a laminated structure including a substrate and a crystal orientation region and a crystalline region disposed on the substrate; forming a gallium nitride-based semiconductor film in the crystal orientation region and the crystalline region, respectively; and evaluating the crystallinity of the gallium nitride-based semiconductor film formed in the crystal orientation region and the crystalline region, respectively. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of a stacked structure used in a method for inspecting gallium nitride-based semiconductor films according to one embodiment of the present invention. [Figure 2] This is a schematic plan view of a stacked structure used in a method for inspecting gallium nitride-based semiconductor films according to one embodiment of the present invention. [Figure 3] This is a flowchart illustrating a method for inspecting a gallium nitride-based semiconductor film according to one embodiment of the present invention. [Figure 4] This is a flowchart showing the steps for preparing a laminated structure according to one embodiment of the present invention. [Figure 5]This is a plan view showing a gallium nitride-based semiconductor film formed on a laminated structure according to one embodiment of the present invention. [Figure 6] This is a flowchart showing the steps for evaluating the crystallinity of a gallium nitride-based semiconductor film according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. While the drawings may schematically represent the width, thickness, shape, etc., of parts in order to clarify the explanation, they are merely examples and do not limit the interpretation of the present invention. In this specification and in the drawings, elements similar to those described above in previous drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0010] <Laminated structure> A laminated structure used in a method for inspecting a gallium nitride-based semiconductor film according to one embodiment of the present invention will be described. Figure 1 is a schematic perspective view of the laminated structure 1. Figure 2 is a schematic plan view of the laminated structure 1. As shown in Figures 1 and 2, the laminated structure 1 includes a substrate 11 and a crystal orientation region 111 and a crystalline region 112 disposed on the substrate 11.

[0011] As shown in Figure 2, the substrate 11 has, for example, a square shape in plan view. The shape of the substrate 11 is not limited to this. The size of the substrate 11 can be set, for example, between 400 mm and 3440 mm in height and between 320 mm and 3100 mm in width in plan view.

[0012] The substrate 11 is preferably one that can withstand the sputtering temperature of gallium nitride-based semiconductors (for example, about 600°C). Examples of materials for the substrate 11 include amorphous glass and polymer resins. Examples of polymer resins include polyimide resins, acrylic resins, siloxane resins, and fluororesins.

[0013] As shown in FIG. 2, the crystal orientation region 111 has, for example, a square shape in plan view. The shape of the crystal orientation region 111 is not limited thereto. The shape and size of the crystal orientation region 111 are appropriately set according to, for example, the use (active area, drive circuit area) of the crystal orientation region 111. The size of the crystal orientation region 111 can be made larger than that of the crystalline region 112 described later in plan view. In FIG. 2, four crystal orientation regions 111 are arranged on the substrate 11 at a predetermined interval, but the number and arrangement of the crystalline orientation regions 111 are not limited thereto. By forming a gallium nitride-based semiconductor film 113 on the crystal orientation region 111, the crystallinity of the gallium nitride-based semiconductor film 113, that is, the c-axis orientation can be improved.

[0014] The crystal orientation region 111 can be arranged on the substrate 11 by forming a crystal orientation film on the substrate 11. Examples of forming the crystal orientation film on the substrate 11 include sputtering and CVD. Depending on the method of forming the crystal orientation film on the substrate 11, the crystallinity of the formed crystal orientation film may not be high. If the crystallinity of the crystal orientation film is not high, the crystallinity of the gallium nitride-based semiconductor film 113 formed thereon will not be high either.

[0015] Examples of the crystal orientation film include those having a hexagonal close-packed structure, a face-centered cubic structure, or a structure similar thereto. The structure similar to the hexagonal close-packed structure or the face-centered cubic structure means one including a crystal structure in which the c-axis is not 90° with respect to the a-axis and the b-axis. Examples of the material of the crystal orientation film include titanium (Ti), titanium nitride (TiN x ), titanium oxide (TiO x) graphene, zinc oxide (ZnO), magnesium diboride (MgB2), aluminum (Al), aluminum nitride (AlN), aluminum oxide (Al2O3), silver (Ag), calcium (Ca), nickel (Ni), copper (Cu), strontium (Sr), rhodium (Rh), palladium (Pd), cerium (Ce), ytterbium (Yb), iridium (Ir), platinum (Pt), gold (Au), lead (Pb), actinium (Ac), thorium (Th), lithium niobate (LiNbO), BiLaTiO, SrFeO, BiFeO, BaFeO, ZnFeO, PMnN-PZT, or biological apatite (BAp). As the crystalline orientation film, titanium, graphene, zinc oxide, aluminum nitride, or aluminum oxide is preferable.

[0016] As shown in FIG. 2, the crystalline region 112 has, for example, a square shape in plan view. The shape of the crystalline region 112 is not limited thereto. The size of the crystalline region 112 is set, for example, to be 1 mm or more and 20 mm or less in length and 1 mm or more and 20 mm or less in width in plan view. As shown in FIG. 2, the crystalline region 112 is arranged on the substrate 11 so as not to overlap with the crystalline orientation region 111. In FIG. 2, nine crystalline regions 112 are arranged at positions corresponding to the corners of the crystalline orientation region 111 on the substrate 11 with a predetermined interval therebetween, but the number and arrangement of the crystalline regions 112 are not limited thereto. By forming the gallium nitride-based semiconductor film 113 on the crystalline region 112, the crystallinity of the gallium nitride-based semiconductor film 113, that is, the c-axis orientation can be improved.

[0017] The crystalline region 112 can be placed on the substrate 11 by bonding a crystalline substrate to the substrate 11. A crystalline substrate refers to a single-crystal substrate or a highly crystalline polycrystalline substrate. High crystallinity means that the full width at half maximum of the diffraction peaks in the X-ray diffraction pattern obtained by X-ray diffraction is sufficiently small. The crystallinity of the crystalline region 112 is greater than or equal to the crystallinity of the crystal orientation region 111. Bonding the crystalline substrate to the substrate 11 can be done by, for example, melt bonding, solid-phase bonding by electrostatic attraction, surface activation bonding, bonding with adhesive or adhesive material, or fitting to the substrate 11. In melt bonding, an intermediate layer can be provided between the substrate 11 and the crystalline substrate to perform TLP bonding (Transient Liquid Phase Diffusion Bonding). Bonding the crystalline substrate to the substrate 11 can be done by combining these methods. Bonding the crystalline substrate to the substrate 11 may be done individually or in multiples simultaneously using known equipment.

[0018] Examples of single-crystal substrates include silicon substrates, sapphire substrates, gallium nitride substrates, gallium nitride templates (gallium nitride deposited on a sapphire substrate by MOCVD), SAM substrates, aluminum nitride substrates, silicon carbide substrates, germanium substrates, boron nitride, and graphene. In the X-ray diffraction pattern obtained by X-ray diffraction, the degree of crystallinity (c-axis orientation) is determined by the peak at (111) for silicon substrates, the peak at (006) for sapphire substrates, and the peak at (002) for gallium nitride substrates. Examples of highly crystallinity polycrystalline substrates include titanium substrates, zirconium substrates, scandium substrates, and hafnium substrates. The materials of the crystalline region 112 and the crystal orientation region 111 may be the same. Since single-crystal substrates or highly crystallinity polycrystalline substrates have high crystallinity, the crystallinity of the gallium nitride-based semiconductor film 113 formed on them will be high, provided that the sputtering is not poor.

[0019] <Inspection method for gallium nitride-based semiconductor films> A method for inspecting a gallium nitride-based semiconductor film according to an embodiment of the present invention will be described. FIG. 3 is a flowchart showing an inspection method 2 of a gallium nitride-based semiconductor film. As shown in FIG. 3, the inspection method 2 of the gallium nitride-based semiconductor film includes preparing a laminate structure 1 (S21), forming a gallium nitride-based semiconductor film 113 on the laminate structure 1 (S22), and evaluating the crystallinity of the formed gallium nitride film 13 (S23).

[0020] Step S21 is to prepare a laminate structure 1 including a substrate 11 and a crystal orientation region 111 and a crystallinity region 112 disposed on the substrate 11. FIG. 4 is a flowchart for preparing the laminate structure 1. As shown in FIG. 4, preparing the laminate structure 1 (S21) includes forming a crystal orientation film on the substrate 11 to dispose a crystal orientation region 111 on the substrate 11 (S211), and bonding a crystalline substrate whose high crystallinity has been previously determined to the substrate 11 to dispose a crystallinity region 112 on the substrate 11 (S212). Step S212 may be performed prior to step S211, and the order of steps S211 and S212 is not limited.

[0021] Step S22 is to form a gallium nitride-based semiconductor film 113 in each of the crystal orientation region 111 and the crystallinity region 112 in the laminate structure 1. FIG. 5 is a plan view when the gallium nitride-based semiconductor film 113 is formed on the laminate structure 1. As shown in FIG. 5, the gallium nitride-based semiconductor film 113 is formed on the substrate 11 in a region where the crystal orientation region 111, the crystallinity region 112, and a region where the crystal orientation region 111 and the crystallinity region 112 are not disposed. The formation of the gallium nitride-based semiconductor film 113 includes, for example, sputtering. Examples of the material of the sputtering target include Al x Ga 1-x N, In x Ga 1-x N. In the case of Al x Ga 1-x N, x is preferably 0.5 or less, and more preferably 0.2 or less. In x Ga 1-xIn the case of N, x is preferably 0.9 or less, and more preferably 0.7 or less. x may also be 0.

[0022] Step S23 is to evaluate the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystal orientation region 111 and the crystalline region 112. Examples of methods for evaluating the crystallinity of the gallium nitride-based semiconductor film 113 include X-ray diffraction, ellipsometry, electron backscatter diffraction (EBSD), Raman spectroscopy, and electron diffraction.

[0023] In X-ray diffraction, for example, crystallinity is evaluated by examining the relationship between the diffraction angle and diffraction intensity of the obtained X-ray diffraction pattern, specifically whether the full width at half maximum (FWHM) of the peak at a given diffraction angle exceeds a certain value (e.g., 1000 arcsec). If the FWHM of the peak exceeds a certain value, it is judged to be low crystallinity; if it does not, it is judged to be high crystallinity.

[0024] In ellipsometry, for example, crystallinity is evaluated from the obtained spectrum by determining whether the angle of rise of the absorption edge of the absorption coefficient exceeds a certain value. If the angle of rise of the absorption edge of the absorption coefficient exceeds a certain value, it can be judged that the crystallinity is high; if it does not exceed this value, it can be judged that the crystallinity is low. In addition, if the obtained values ​​of refractive index n and extinction coefficient k are close to values ​​previously known to indicate high crystallinity, it can be judged that the crystallinity is high; if they are not close, it can be judged that the crystallinity is low.

[0025] In backscatter electron diffraction, for example, crystallinity can be evaluated by checking whether the average particle size exceeds a certain value from the obtained particle size distribution. If the average particle size exceeds a certain value, it can be judged as having high crystallinity; if it does not, it can be judged as having low crystallinity.

[0026] In Raman spectroscopy, for example, crystallinity is evaluated by looking at the relationship between the difference in frequency between the incident and scattered light (Raman shift) and the intensity of the scattered light, and determining whether the full width at half maximum (FWHM) of the peak at a given Raman shift exceeds a certain value. If the FWHM of the peak exceeds a certain value, it is judged that the crystallinity is low; if it does not exceed a certain value, it is judged that the crystallinity is high.

[0027] In electron diffraction, for example, crystallinity is evaluated by whether a predetermined electron diffraction pattern is obtained from the resulting electron diffraction pattern. If the predetermined diffraction pattern is obtained, it can be judged that the crystallinity is high; if it is not obtained, it can be judged that the crystallinity is low.

[0028] Figure 6 is a flowchart showing the evaluation of the crystallinity of each formed gallium nitride-based semiconductor film 113 (S23). As shown in Figure 6, the evaluation of the crystallinity of each formed gallium nitride-based semiconductor film 113 (S23) involves, in order, evaluating the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystal orientation region 111 (S231) and evaluating the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystalline region 112 (S232). Before performing the crystallinity evaluation, the stacked structure 1 may be cut and each gallium nitride-based semiconductor film 113 may be individually separated, or the crystallinity evaluation may be performed and only the gallium nitride-based semiconductor film 113 with good crystallinity may be individually separated.

[0029] As shown in Figure 6, first the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystal orientation region 111 is evaluated (S231). If the crystallinity of this gallium nitride-based semiconductor film 113 is high (Yes in S231), the gallium nitride-based semiconductor film 113 formed on the stacked structure 1 is used in the manufacture of a gallium nitride-based semiconductor device (S24). In other words, the method 2 for inspecting a gallium nitride-based semiconductor film according to one embodiment of the present invention can be incorporated as part of a method for manufacturing a gallium nitride-based semiconductor device.

[0030] In step S231, if the crystallinity of the gallium nitride-based semiconductor film 113 is not high (No in S231), the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystalline region 112 is evaluated (S232). In step S232, if the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystalline region 112 is high (Yes in S232), it can be determined that the low crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystal orientation region 111 is due to the crystal orientation film, since the gallium nitride-based semiconductor film 113 is well formed in the crystalline region 112.

[0031] On the other hand, in step S232, if the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystalline region 112 is not high (No. in S232), unless the sputtering is poor due to the material of the sputtering target or the film deposition conditions, the crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystalline region 112 will be high. Therefore, it can be determined that the low crystallinity of the gallium nitride-based semiconductor film 113 formed in the crystal orientation region 111 is due to sputtering, such as the material of the sputtering target or the film deposition conditions. If it is due to sputtering, possible causes include, for example, the material of the sputtering target (composition, density, purity, etc.), the sputtering film deposition conditions (chamber leak, incorporation of impurities due to residual gas in the chamber, abnormal discharge, insufficient pre-spat, fluctuations in film deposition temperature, etc.), and the effects of pre-treatment (effects of residual impurities due to poor cleaning, etc.).

[0032] Any other effects and advantages brought about by the embodiments described herein that are obvious from this specification or that can be appropriately conceived by those skilled in the art are naturally considered to be brought about by the present invention. [Explanation of symbols]

[0033] 1. Laminated structure 11 circuit boards 111 Crystal orientation region 112 Crystalline region 113 Gallium nitride-based semiconductor film 2. Inspection method for gallium nitride-based semiconductor films

Claims

1. A laminated structure is prepared, which includes a substrate and a crystal orientation region and a crystalline region disposed on the substrate. A gallium nitride-based semiconductor film is formed in the crystal orientation region and the crystalline region, A method for inspecting a gallium nitride semiconductor film, comprising evaluating the crystallinity of the gallium nitride semiconductor film formed in the crystal orientation region and the crystalline region.

2. Evaluating the crystallinity of each of the gallium nitride-based semiconductor films is To evaluate the crystallinity of the gallium nitride-based semiconductor film formed in the crystal orientation region, A method for inspecting a gallium nitride-based semiconductor film according to claim 1, comprising: evaluating the crystallinity of the gallium nitride-based semiconductor film formed in the crystalline region; and

3. Evaluating the crystallinity of each of the gallium nitride-based semiconductor films is A method for inspecting a gallium nitride-based semiconductor film according to claim 2, wherein the inspection is performed by any one of X-ray diffraction, ellipsometry, backscattered electron diffraction, Raman spectroscopy, or electron diffraction.

4. Preparing the aforementioned laminated structure is A method for inspecting a gallium nitride-based semiconductor film according to claim 1, comprising forming a crystal orientation film on the substrate and arranging the crystal orientation region on the substrate.

5. Preparing the aforementioned laminated structure is A method for inspecting a gallium nitride-based semiconductor film according to claim 4, comprising bonding a crystalline substrate to the substrate and arranging the crystalline region on the substrate.

6. A method for manufacturing a gallium nitride semiconductor device, comprising a method for inspecting a gallium nitride semiconductor film according to any one of claims 1 to 5.

7. circuit board and The substrate includes a crystal orientation region and a crystalline region, A stacked structure in which a gallium nitride-based semiconductor film is formed in each of the crystal orientation regions and the crystalline regions.

8. The laminated structure according to claim 7, wherein the material of the crystal orientation region and the crystalline region are the same.

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