Aluminum nitride laminated structure and aluminum nitride layer

Abstract

The present invention relates to an aluminum nitride stacked component and an aluminum nitride layer. A technology for growing an AlN layer having protrusions periodically formed on the surface using a sapphire substrate having protrusions periodically arranged thereon is provided. The aluminum nitride stacked component comprises: a sapphire substrate having a base surface having protrusions periodically arranged thereon with a height of 500 nm or less; and an aluminum nitride layer provided on the base surface and having a surface having protrusions formed above the tops of the protrusions.

Description

Technical Field

[0001] The present invention relates to an aluminum nitride laminated structure and an aluminum nitride layer. Background Art

[0002] As a method for producing a light emitting diode (LED), for example, a technique for growing an aluminum nitride (AlN) layer on a sapphire substrate having a periodic concave-convex shape is proposed (see, for example, non-patent document 1). As the concave-convex shape of the sapphire substrate, there are known shapes in which concave portions are periodically (and discretely) arranged and shapes in which convex portions are periodically (and discretely) arranged.

[0003] Prior art literature

[0004] Non-patent literature

[0005] Non-patent document 1: H. Miyake et al., "HVPE growth of thick AlN on trench-patterned substrate", Phys Status Solidi C 8, No. 5, 1483-1486 (2011) Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the conventional technology, when a sapphire substrate having periodically arranged protrusions is used, irregular and disorderly AlN crystals are grown, and therefore it is impossible to grow the AlN layer in a controlled form.

[0008] An object of the present invention is to provide a technology for growing an AlN layer having a controlled morphology, specifically, a morphology in which protrusions are periodically formed on the surface, using a sapphire substrate having protrusions periodically arranged thereon.

[0009] Solutions for solving problems

[0010] According to one embodiment of the present invention, there is provided an aluminum nitride laminated structure comprising:

[0011] A sapphire substrate having a base surface on which projections having a height of 500 nm or less are periodically arranged; and

[0012] The aluminum nitride layer is provided on the base surface and has a surface with a protrusion formed above the top of each of the protrusions.

[0013] According to another embodiment of the present invention, there is provided an aluminum nitride layer having a surface on which protrusions are periodically formed.

[0014] Each of the protrusions has a hexagonal shape when viewed from above.

[0015] In each of the protrusions, the height of the protrusion is equal to or greater than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0016] In each of the protrusions, the size of the protrusion is less than 1 / 2 of the distance between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0017] A recess is formed on the outer surface of the protrusion at the base of the protrusion.

[0018] According to another embodiment of the present invention, there is provided an aluminum nitride layer having a surface on which protrusions are periodically formed.

[0019] Each of the protrusions has a hexagonal shape when viewed from above.

[0020] In each of the protrusions, the height of the protrusion is smaller than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0021] In each of the protrusions, the size of the protrusion is larger than 1 / 2 of the distance between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0022] A raised portion is formed at the center of the protruding portion.

[0023] Effects of the Invention

[0024] A technique for growing an AlN layer having protrusions periodically formed on the surface thereof using a sapphire substrate having protrusions periodically arranged thereon can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is an exemplary cross-sectional schematic diagram of the stacked structure 100 according to the first embodiment of the present invention.

[0026] Figure 2 It is an exemplary schematic plan view of the substrate 10 according to the first embodiment.

[0027] Figure 3 This is an exemplary schematic plan view of the layer 20 according to the first embodiment.

[0028] Figure 4 (a) and Figure 4 (b) are SEM stereoscopic images and SEM top view images showing the results of Experimental Example 1, respectively. Figure 4(c) is an AFM image and an AFM line profile showing the results of Experimental Example 1.

[0029] Figure 5 (a) and Figure 5 (b) are SEM stereoscopic images and SEM top view images showing the results of Experimental Example 2, respectively. Figure 5 (c) is an AFM image and an AFM line profile showing the results of Experimental Example 2.

[0030] Figure 6 (a) and Figure 6 (b) are SEM stereoscopic images and SEM top view images showing the results of Experimental Example 3, respectively. Figure 6 (c) is an AFM image and an AFM line profile showing the results of Experimental Example 3.

[0031] Figure 7 It is an exemplary cross-sectional schematic diagram of the stacked structure 100 according to the second embodiment.

[0032] Figure 8 (a) and Figure 8 (b) are a SEM stereoscopic image and a SEM top view image showing the results of Experimental Example 4, respectively.

[0033] Fig. 9 2 is a schematic plan view of the layer 20 , illustrating another embodiment in which the axis direction of the regular triangle lattice in which the protrusions 12 are arranged is parallel to the a-axis direction of the sapphire constituting the substrate 10 .

[0034] Fig.10 FIG. 1 is a schematic plan view of the substrate 10 , illustrating another embodiment in which the protrusions 12 are arranged in a quadrangular lattice.

[0035] Fig.11 FIG. 1 is a schematic plan view of the substrate 10 , illustrating another embodiment in which the protrusions 12 are arranged in a hexagonal lattice.

[0036] Fig.12 FIG. 1 is a schematic plan view of a substrate 10 , illustrating another embodiment in which ridge-shaped protrusions 12 are arranged.

[0037] Description of Reference Numerals

[0038] 10 ... sapphire substrate, 11 ... base surface, 12 ... convex portion, 13 ... valley portion, 14 ... flat surface, 20 ... AlN layer, 21 ... surface, 22 ... protrusion, 100 ... AlN laminated member DETAILED DESCRIPTION

[0039] <First Embodiment>

[0040] An aluminum nitride (AlN) laminated structure 100 (hereinafter also referred to as the laminated structure 100 ) according to a first embodiment of the present invention will be described. Figure 1 1 is an exemplary cross-sectional schematic diagram of a stacked component 100 according to the first embodiment. The stacked component 100 includes a sapphire substrate 10 (hereinafter also referred to as substrate 10) and an AlN layer 20 (hereinafter also referred to as layer 20) grown on the substrate 10. The layer 20 of this embodiment is characterized in that a protrusion 22 is formed on its surface 21 by growth.

[0041] The substrate 10 is made of single crystal sapphire and has a base surface 11 as a base for growing the layer 20. The base surface 11 has a plurality of protrusions 12 arranged periodically (and discretely). The shape of the protrusion 12 is, for example, conical. In the present embodiment, the conical shape includes a cone and a pyramid, and includes not only a shape with a sharp top but also a shape with a flat top (a frustum).

[0042] Here, an embodiment in which the convex portion 12 is conical is exemplified.

[0043] The outer portion 13 of the basal surface 11 (hereinafter also referred to as the valley 13) of the convex portion 12 is arranged on a (virtual) plane 14. The convex portion 12 can be considered to be arranged on the plane 14, and the normal direction N14 of the plane 14 is the height direction of the convex portion 12. The height H12 of the convex portion 12 is specified by the distance from the plane 14 to the upper end of the convex portion 12. The convex portion 12 is formed in a manner that the height direction of the convex portion 12 is parallel to the c-axis direction of the sapphire constituting the substrate 10. The top of each convex portion 12 exposes the c-plane of the sapphire. It should be noted that in this specification, "a certain direction D1 is parallel to another direction D2" means that the angle formed by a certain direction D1 and another direction D2 is less than 3°.

[0044] Figure 2 1 is an illustrative top view of the substrate 10. In the present embodiment, the protrusions 12 are periodically arranged in a two-dimensional manner by being arranged, for example, on the grid points of a triangular grid, a quadrangular grid or a hexagonal grid. Here, an embodiment in which the protrusions 12 are arranged on the grid points of an equilateral triangular grid is illustrated. The axial direction of the equilateral triangular grid is indicated by a single dotted line. The axial direction of the lattice such as the triangular grid in which the protrusions 12 are arranged is not particularly limited, and is, for example, parallel to the m-axis direction or the a-axis direction of the sapphire constituting the substrate 10.

[0045] The layer 20 is composed of AlN grown on the base surface 11 of the substrate 10. The surface (upper surface) 21 of the layer 20 has a plurality of protrusions 22 formed when the layer 20 grows. Each protrusion 22 is formed above the top of each protrusion 12 of the substrate 10. The protrusions 22 are isolated from each other. The AlN constituting the protrusions 22 controls the crystal orientation by utilizing the c-plane exposed at the top of the protrusion 12, so that the c-axis direction is parallel to the height direction of the protrusion 12. As a result, the c-axis direction of the AlN constituting the protrusions 22 is parallel to each other between the protrusions 22.

[0046] Figure 3 is an exemplary top view of layer 20. Figure 2 Correspondingly, an embodiment in which the protrusions 22 are arranged on the grid points of the equilateral triangle lattice is illustrated. Each protrusion 22 has a hexagonal shape when viewed from above. The direction connecting the center and the vertex of the hexagon (the diagonal direction connecting the vertices opposite to each other with the center sandwiched therebetween) is the a-axis direction of the AlN constituting the protrusion 22. Here, the case where the axial direction of the equilateral triangle lattice in which the convex portion 12 is arranged (i.e., the protrusion 22 is arranged) is parallel to the m-axis direction of the sapphire constituting the substrate 10 is illustrated. Thus, the a-axis direction of the AlN constituting the layer 20 is parallel to the axial direction of the equilateral triangle lattice. That is, the a-axis direction of the AlN constituting the protrusion 22 is parallel to each other between the protrusions 22. It should be noted that in the heteroepitaxial growth of AlN above the c-plane of sapphire, AlN grows in a manner parallel to the m-axis direction of the sapphire and the a-axis direction of the AlN. In other words, it grows in a manner parallel to the a-axis direction of the sapphire and the m-axis direction of the AlN.

[0047] The inventors of the present application have obtained the following insights: As shown in Experimental Examples 1 to 3 described later, in order to grow the protrusion 22 with high selectivity above the top of the convex portion 12, it is preferable to make the height H12 of the convex portion 12 low. Specifically, the height H12 of the convex portion 12 is preferably 500 nm or less, and more preferably 300 nm or less. It should be noted that the lower limit of the height H12 of the convex portion 12 is not particularly limited, but from the perspective of clearly defining the convex portion 12, the height H12 of the convex portion 12 is, for example, set to be 50 nm or more, preferably 100 nm or more.

[0048] The reason why the height H12 of the protrusion 12 is preferably low is, for example, presumably as follows. As described later, the layer 20 is preferably grown by vapor phase epitaxy, such as hydride vapor phase epitaxy (HVPE), and the base surface 11 is subjected to ultraviolet irradiation treatment before the growth of the layer 20. It is believed that the base surface 11 treated with ultraviolet irradiation changes the terminal state due to ultraviolet irradiation, thereby increasing the smoothness, that is, the ease of movement of Al atoms on the base surface 11.

[0049] In order to selectively grow the protrusion 22 above the top of the convex portion 12, it is considered preferable that Al atoms attached to various parts of the base surface 11 can easily move to the vicinity of the top of the convex portion 12. In the present embodiment, it is considered that by making the height H12 of the convex portion 12 sufficiently low and then subjecting the base surface 11 to ultraviolet irradiation treatment, the Al atoms attached to various parts of the base surface 11 can easily move to the vicinity of the top of the convex portion 12, whereby the protrusion 22 can be grown with high selectivity above the top of the convex portion 12. It should be noted that the suitable growth conditions (growth temperature, V / III ratio, etc.) for growing the protrusion 22 will be described later.

[0050] In order to make it easier for Al atoms to move to the vicinity of the top of the convex portion 12 (to shorten the movement distance), it is more preferable that the width W12 of the inclined surface of the convex portion 12 in a plan view is narrow. Alternatively, it is more preferable that the pitch P12 between the nearest convex portions 12 is narrow. Specifically, the width W12 is preferably set to 500 nm or less, and the pitch P12 is preferably set to 1000 nm or less.

[0051] The (planar) dimension D22 of the protrusion 22 is defined by the distance of the diagonal line passing through the center of the hexagon of the outer shape of the protrusion 22 in a plan view. The height H22 of the protrusion 22 is defined by the distance from the root (lower end) of the protrusion 22 protruding from the surface 21 of the layer 20 to the upper end of the protrusion 22. The pitch P22 of the protrusion 22 is defined by the distance between the centers of the nearest protrusions 22 in a plan view. It can be considered that the pitch P22 of the protrusion 22 is equal to the pitch P12 of the convex portion 12.

[0052] The inventors of the present application have obtained the following insights: It is also possible to form elongated rod-shaped protrusions 22 as described in Experimental Example 2 (refer to Figure 5 of (a) to Figure 5 of (c)) and Experimental Example 3 (refer to Figure 6 of (a) to Figure 6 of (c)), and it is also possible to form flat and large plate-shaped protrusions 22 as described in Experimental Example 4 (refer to Figure 8 of (a) and Figure 8 of (b)).

[0053] Here, the case where the height H22 is greater than or equal to the dimension D22 (H22≥D22) is referred to as the protrusion 22 being rod-shaped, and the case where the height H22 is less than the dimension D22 (H22<D22) is referred to as the protrusion 22 being plate-shaped. In addition, the case where the dimension D22 is 1 / 2 or less of the pitch P22 (D22≤(1 / 2)×P22) is referred to as the protrusion 22 being small-diameter, and the case where the dimension D22 is greater than 1 / 2 of the pitch P22 (D22>(1 / 2)×P22) is referred to as the protrusion 22 being large-diameter.

[0054] The first embodiment and Experimental Examples 2 and 3 of the first embodiment illustrate rod-shaped protrusions 22 and small-diameter protrusions 22. The second embodiment described later and Experimental Example 4 of the second embodiment illustrate plate-shaped protrusions 22 and large-diameter protrusions 22.

[0055] Next, a method for manufacturing the stacked component 100 is described. Prepare a substrate 10. The height H12 of the protrusion 12 of the substrate 10 is set to be less than 500nm. The width W12 of the inclined surface of the protrusion 12 is preferably set to be less than 500nm, and the pitch P12 of the protrusion 12 is preferably set to be less than 1000nm. Such a substrate 10 can be produced by a formation technology of a patterned sapphire substrate (PSS). The base surface 11 of the substrate 10 is subjected to ultraviolet irradiation treatment. For example, ultraviolet treatment preferably uses a light source containing a bright line of less than 300nm, such as a low-pressure mercury lamp or a high-pressure mercury lamp, at a power of 10mW / cm 2 Perform the above intensity for more than 10 minutes.

[0056] On the ultraviolet irradiated substrate 11, AlN is grown by vapor phase epitaxy, preferably HVPE, to form the layer 20. As the aluminum (Al) raw material gas, for example, aluminum chloride (AlCl) gas or aluminum chloride (AlCl3) gas can be used, and as the nitrogen (N) raw material gas, ammonia (NH3) gas can be used. These raw material gases can be mixed with a carrier gas using hydrogen (H2 gas), nitrogen (N2 gas) or a mixed gas thereof and supplied.

[0057] The growth conditions of the first embodiment can be exemplified as follows. As the growth temperature, 900 to 1050°C can be exemplified. As the supply amount ratio of the N raw material gas to the Al raw material gas, that is, the V / III ratio, 20 to 200 can be exemplified. As the growth rate, 200 to 500 nm / minute can be exemplified. It should be noted that in order to prevent AlN from adhering to the nozzle of the gas supply pipe used to introduce various gases into the growth chamber of the HVPE device, hydrogen chloride (HCl) gas can also be circulated, and the supply amount of HCl gas can be exemplified as an amount with a ratio of 0.1 to 100 relative to AlCl gas or AlCl3 gas.

[0058] That is, as the growth conditions of the first embodiment, the layer 20 is grown under conditions of a lower temperature, a high V / III ratio and a high speed (compared to the growth conditions of the second embodiment described later), so that the protrusion 22 is formed with high selectivity above the top of the convex portion 12 in a manner that forms a rod-shaped and small-diameter protrusion 22.

[0059] Next, experimental examples 1 to 3 of the first embodiment are described. In these experimental examples, how the growth state of the layer 20 changes due to changes in the height H12 of the protrusions 12 is studied. As the substrate 10, a substrate in which the conical protrusions 12 are arranged in an equilateral triangular lattice is used. The axial direction of the equilateral triangular lattice is set to be parallel to the m-axis direction of the sapphire constituting the substrate 10.

[0060] The height H12 of the convex portion 12 is set to 1600nm, 440nm and 220nm in Experimental Examples 1, 2 and 3, respectively. The width W12 of the inclined surface of the convex portion 12 is set to 1200nm, 350nm and 250nm in Experimental Examples 1, 2 and 3, respectively. The pitch P12 of the convex portion 12 is set to 3000nm, 1000nm and 600nm in Experimental Examples 1, 2 and 3, respectively. The growth conditions of the layer 20 are the growth conditions of the first embodiment illustrated above. The layer 20 is grown at a thickness level of 700nm when grown on a flat base surface.

[0061] Figure 4 (a) Figure 4 (b) and Figure 4 (c) shows the results of Experimental Example 1, Figure 5 (a) Figure 5 (b) and Figure 5 (c) shows the results of Experimental Example 2, Figure 6 (a) Figure 6 (b) and Figure 6 (c) shows the results of Experimental Example 3. Figure 4 (a) Figure 5 (a) and Figure 6 (a) is a stereoscopic image (SEM stereoscopic image) of the surface 21 of the layer 20 based on a scanning electron microscope (SEM), Figure 4 (b) Figure 5 (b) and Figure 6 (b) is a top-view image of the surface 21 of the layer 20 by SEM (SEM top-view image). Figure 4 (c) Figure 5 (c) and Figure 6 (c) is an atomic force microscope (AFM) image of the surface 21 of the layer 20 and an AFM line profile.

[0062] In Experimental Example 2 (protrusion height 440nm) and Experimental Example 3 (protrusion height 220nm), it can be seen from the SEM stereoscopic image and the SEM top view image that the protrusions 22 are selectively formed on the lattice points of the regular triangle lattice corresponding to the top of the protrusion 12 on the surface 21 of the layer 20. In contrast, in Experimental Example 1 (protrusion height 1600nm), no clear protrusions 22 are formed on the lattice points of the regular triangle lattice on the surface 21 of the layer 20. Therefore, it can be said that in order to grow the protrusions 22 with high selectivity above the top of the protrusions 12, the height H12 of the protrusions 12 is preferably, for example, 500nm or less.

[0063] In Experimental Examples 2 and 3, a rod-shaped and small-diameter protrusion 22 was formed. The protrusion 22 has a substantially regular hexagonal shape when viewed from above. The axial direction of the regular triangular lattice in which the protrusions 12 are arranged is parallel to the m-axis direction of the sapphire constituting the substrate 10, and correspondingly, the a-axis direction of the AlN constituting the protrusion 22, that is, the direction connecting the center and the vertex of the hexagon of the protrusion 22, is parallel to the axial direction of the regular triangular lattice.

[0064] In Experimental Examples 2 and 3, it can be seen from the AFM line profile that protrusions 22 having a height H22 of at least 100 nm are formed. It should be noted that since the measurement direction of the line profile deviates from the axial direction of the regular triangle lattice in which the protrusions 22 are arranged, the intervals between the protrusions 22 presented in the line profile are inconsistent with the pitch P22 of the protrusions 22.

[0065] In Experimental Examples 2 and 3, the valleys 13 between the protrusions 12 are substantially filled with AlN. Thus, the surface 21 between the protrusions 22 is substantially close to being flat compared to the concavo-convex shape of the base surface 11. It should be noted that the layer 20 may not completely fill the valleys 13 between the protrusions 12, and there may be pores inside the layer 20.

[0066] If Experimental Example 2 is compared with Experimental Example 3, the surface 21 between the protrusions 22 in Experimental Example 2 has a large degree of concavity, and an incidental protrusion protruding in the oblique direction can also be observed. In contrast, the surface 21 between the protrusions 22 in Experimental Example 3 has a small degree of concavity and is flatter, and no incidental protrusion protruding in the oblique direction can be observed. It can be considered that when the height H12 of the protrusion 12 is lower, the protrusion 22 protruding in the height direction of the protrusion 12 can be grown with higher selectivity. According to various additional experiments on changing the height H12 of the protrusion 12, it can also be considered that as the height H12 of the protrusion 12, for example, if it is less than 500nm, a higher selectivity can be obtained as shown in Experimental Example 2, and if it is less than 300nm, a very high selectivity can be obtained as shown in Experimental Example 3.

[0067] In Experimental Examples 2 and 3, the surface 21 between the protrusions 22 is not completely flattened. In particular, from the SEM top view image, it can be seen that the surface 21 outside the protrusion 22 tends to be easily depressed (depressions tend to remain) around the base of the protrusion 22. Such depressions can be considered to be traces formed by the growth of the protrusion 22 (the surface 21 is a feature of direct growth (as-grown)).

[0068] Thus, as described with reference to Experimental Examples 2 and 3, the inventors of the present application have obtained a new insight that a layer 20 having periodically formed protrusions 22 can be obtained by growth. It should be noted that, in Experimental Example 1, although such protrusions 22 are not formed, as described below, a layer 20 having a characteristic concavo-convex shape is formed on the surface 21. This insight of Experimental Example 1 is also a new insight obtained by the inventors of the present application.

[0069] In Experimental Example 1, compared with Experimental Examples 2 and 3, it can be seen that the valleys 13 between the protrusions 12 tend to be less likely to be buried with AlN. A convex shape roughly along the convex shape of the protrusion 12 was observed on the surface 21 of the layer 20. The following microstructures were observed in each of the convex shapes on the surface 21. Fins arranged along the circumferential direction of the protrusion 12 are formed above the inclined surface of the protrusion 12. A plurality of fine rods growing in a direction intersecting the inclined surface of the protrusion 12 are formed between the fins arranged along the circumferential direction of the protrusion 12. According to various additional experiments on changing the height H12 of the protrusion 12, it can be determined that when the height H12 of the protrusion 12 is as high as 1000nm or more, a concave-convex shape with obvious fins can be formed.

[0070] <Second Embodiment>

[0071] Next, a laminated structure 100 according to a second embodiment will be described. Figure 7 This is an exemplary schematic cross-sectional view of the stacked component 100 of the second embodiment. The form of the protrusion 22 of the layer 20 of the stacked component 100 of the second embodiment is different from that of the first embodiment. In the second embodiment and Experimental Example 4 of the second embodiment, specifically, as described above, a plate-shaped protrusion 22 is exemplified, and a protrusion 22 with a large diameter is exemplified.

[0072] The substrate 10 is the same as that in the first embodiment. In addition, the height H12 of the convex portion 12 is set to 500 nm or less, and the layer 20 is grown on the ultraviolet irradiated base surface 11, for example, by HVPE to form the protrusion 22, which is also the same as the first embodiment. However, the growth conditions of the layer 20 are different from those in the first embodiment, so that the morphology of the protrusion 22 is different from that in the first embodiment.

[0073] The growth conditions of the second embodiment can be exemplified as follows. As the growth temperature, 1050 to 1300°C can be exemplified. As the supply ratio of the N raw material gas to the Al raw material gas, that is, the V / III ratio, 0.2 to 20 can be exemplified. As the growth rate, 0.5 to 200 nm / minute can be exemplified. It should be noted that in order to prevent AlN from adhering to the nozzle of the gas supply pipe used to introduce various gases into the growth chamber of the HVPE device, hydrogen chloride (HCl) gas can also be circulated, and the supply amount of HCl gas can be exemplified as an amount with a ratio of 0.1 to 100 relative to AlCl gas or AlCl3 gas.

[0074] That is, as the growth conditions of the second embodiment, the layer 20 is grown under conditions of higher temperature, lower V / III ratio and lower speed (compared to the growth conditions of the above-mentioned first embodiment), so that the protrusion 22 is formed with high selectivity above the top of the convex portion 12 in such a way that a plate-shaped and large-diameter protrusion 22 is formed.

[0075] Next, Experimental Example 4 of the second embodiment is described. As the substrate 10, the same substrate as that of Experimental Example 3 was used. That is, as the substrate 10, a substrate having a height H12 of 220 nm of the convex portion 12 was used. The growth conditions of the layer 20 were the growth conditions of the second embodiment exemplified above. The layer 20 was grown at a thickness level of 700 nm when grown on a flat base surface.

[0076] Figure 8 (a) and Figure 8 (b) shows the results of Experimental Example 4. Figure 8 (a) is a SEM stereoscopic image of the surface 21 of the layer 20, Figure 8 (b) is a SEM top view image of the surface 21 of the layer 20. It can be seen from the SEM stereo image and the SEM top view image that, in Experimental Example 4 of the second embodiment, similarly to Experimental Examples 2 and 3 of the first embodiment, protrusions 22 are selectively formed on the surface 21 of the layer 20 at the grid points of the regular triangle grid corresponding to the top of the protrusion 12.

[0077] In Experimental Examples 2 and 3, a rod-shaped protrusion 22 with a small diameter was formed, whereas in Experimental Example 4, a plate-shaped protrusion 22 with a large diameter was formed. In Experimental Example 4, as in Experimental Examples 2 and 3, the protrusion 22 had a substantially regular hexagonal shape in a plan view. In addition, the a-axis direction of AlN constituting the protrusion 22, that is, the direction connecting the center and the vertex of the hexagon of the protrusion 22, was parallel to the axial direction of the regular triangle lattice.

[0078] In Experimental Example 4, as in Experimental Examples 2 and 3, the valleys 13 between the protrusions 12 are substantially filled with AlN. As a result, the surface 21 between the protrusions 22 is substantially close to being flat compared to the concavo-convex shape of the base surface 11. It should be noted that the layer 20 may not completely fill the valleys 13 between the protrusions 12, and there may be pores inside the layer 20.

[0079] In the protrusion 22 formed in Experimental Example 4, it was observed that a protrusion with an irregular shape tended to be formed in the center of the protrusion 22. Such a protrusion can be considered as a trace formed by the growth of the protrusion 22 (the surface 21 is a feature of direct growth (as-grown)). Thus, Experimental Example 4 also confirmed the view that the protrusion 22 can be obtained by growth.

[0080] As described above, according to the first and second embodiments, the layer 20 having the surface 21 on which the protrusions 22 are periodically formed can be obtained by growth. That is, the surface 21 on which the protrusions 22 are periodically formed can be obtained as a directly grown surface. Therefore, there is no need for complicated processing for forming the protrusions 22. In addition, since such processing is not required, damage to the AlN crystal caused by the processing can be prevented.

[0081] The layer 20 newly discovered by the inventors of the present application, in which the protrusions 22 are periodically formed, can be used in any application. Since the size D22 or the height H22 of the protrusions 22 can be made nanometer-sized below 1 μm, it is foreseeable that it can be used as a material for a device using a nanometer-sized structure. For example, it is expected to use an optical resonator using a whispering gallery mode (WGM) of each protrusion 22, more specifically, an optical resonator that receives incident visible light and emits ultraviolet light through wavelength conversion based on the nonlinear optical effect of AlN. The layer 20 can be used in the form of a stacked member 100 stacked on a substrate 10, or can be used in a form separated from the substrate 10.

[0082] <Other Implementation Methods>

[0083] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. In addition, various embodiments can be appropriately combined.

[0084] In the first and second embodiments described above, the substrate 10 is exemplified in which the protrusions 12 are arranged at the lattice points of the equilateral triangle lattice, and the axis direction of the equilateral triangle lattice is parallel to the m-axis direction of the sapphire constituting the substrate 10. That is, correspondingly, the layer 20 is exemplified in which the a-axis direction of AlN constituting the protrusion 22 is parallel to the axis direction of the equilateral triangle lattice. However, as described above, the axis direction of the equilateral triangle lattice is not limited to the m-axis direction of the sapphire, and may be set to other directions.

[0085] Fig. 9 A schematic plan view of the layer 20 is provided as an example of an embodiment in which the protrusions 12 are arranged on the grid points of an equilateral triangle lattice, and the axial direction of the equilateral triangle lattice is parallel to the a-axis direction of the sapphire constituting the substrate 10. In this embodiment, the m-axis direction of the AlN constituting the layer 20 is parallel to the axial direction of the equilateral triangle lattice, so that the m-axis directions of the AlN constituting the protrusions 22 are parallel to each other between the protrusions 22.

[0086] In the first and second embodiments, a triangular lattice (e.g., an equilateral triangular lattice) is exemplified as the two-dimensional periodic arrangement of the protrusions 12. However, as described above, the two-dimensional periodic arrangement of the protrusions 12 is not limited to a triangular lattice, and may be, for example, a quadrangular lattice or a hexagonal lattice. Fig.10 and Fig.11 The schematic plan views of the substrate 10 illustrate a tetragonal lattice (eg, a square lattice) and a hexagonal lattice (eg, a regular hexagonal lattice) as examples of the two-dimensional periodic arrangement of the protrusions 12 .

[0087] In the first and second embodiments, the convex portions 12 are cone-shaped, but the convex portions 12 are not limited to cones. In the first and second embodiments, the convex portions 12 are arranged two-dimensionally periodically, but the periodic arrangement of the convex portions 12 is not limited to two dimensions. Fig.12 The schematic plan view of the substrate 10 is shown as an example in which ridge-shaped protrusions 12 are arranged one-dimensionally periodically so that the extending directions of the ridges are parallel to each other. The solid lines and dotted lines extending in the vertical direction of the paper represent the ridge lines and valley lines of the protrusions 12, respectively.

[0088] <Preferred Mode of the Invention>

[0089] Preferred embodiments of the present invention are described below.

[0090] (Note 1)

[0091] An aluminum nitride laminated component comprising:

[0092] A sapphire substrate having a base surface on which projections having a height of 500 nm or less are periodically arranged; and

[0093] The aluminum nitride layer is provided (grown) on the base surface and has a surface having a protrusion formed above the top of each of the protrusions.

[0094] (Note 2)

[0095] The aluminum nitride laminated structure according to Supplementary Note 1, wherein each of the protrusions has a hexagonal outer shape in a plan view.

[0096] (Note 3)

[0097] The aluminum nitride laminated structure according to Supplement 1 or 2, wherein in each of the protrusions, the height of the protrusion is equal to or greater than the size of the protrusion, and the size of the protrusion is defined by the distance of a diagonal line passing through the center of the hexagon.

[0098] (Note 4)

[0099] The aluminum nitride laminated structure according to Supplementary Note 1 or 2, wherein in each of the protrusions, the height of the protrusion is smaller than the size of the protrusion, and the size of the protrusion is defined by the distance of a diagonal line passing through the center of the hexagon.

[0100] (Note 5)

[0101] The aluminum nitride laminated structure according to Appendix 1 or 2, wherein, in each of the protrusions, the size of the protrusion is less than 1 / 2 of the interval between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0102] (Note 6)

[0103] The aluminum nitride laminated structure according to Appendix 1 or 2, wherein, in each of the protrusions, the size of the protrusion is larger than 1 / 2 of the interval between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0104] (Note 7)

[0105] The aluminum nitride laminated structure according to Appendix 1 or 2, wherein in each of the protrusions, the height of the protrusion is greater than or equal to the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0106] In each of the protrusions, a size of the protrusion is less than 1 / 2 of a pitch between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by a distance between a diagonal line passing through the center of the hexagon.

[0107] (Note 8)

[0108] The aluminum nitride laminated structure according to Supplementary Note 7, wherein a recess is formed at a base of the protrusion on the surface outside the protrusion.

[0109] (Note 9)

[0110] The aluminum nitride laminate structure according to Supplementary Note 7 or 8, wherein the height of the protrusion is 100 nm or more.

[0111] (Note 10)

[0112] The aluminum nitride laminated structure according to Supplement 1 or 2, wherein in each of the protrusions, the height of the protrusion is smaller than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0113] In each of the protrusions, a size of the protrusion is larger than 1 / 2 of a distance between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by a distance of a diagonal line passing through the center of the hexagon.

[0114] (Note 11)

[0115] The aluminum nitride laminated structure according to Supplementary Note 10, wherein a bulge is formed at the center of the protrusion.

[0116] (Note 12)

[0117] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 11, wherein the c-axis directions of the aluminum nitride constituting the protrusions are parallel to each other between the protrusions.

[0118] (Note 13)

[0119] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 12, wherein the c-axis direction of the aluminum nitride constituting the protrusion is parallel to the height direction of the convex portion.

[0120] (Note 14)

[0121] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 13, wherein the a-axis directions of the aluminum nitride constituting the protrusions are parallel to each other between the protrusions.

[0122] (Note 15)

[0123] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 14, wherein the m-axis directions of the aluminum nitride constituting the protrusions are parallel to each other between the protrusions.

[0124] (Note 16)

[0125] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 15, wherein a height direction of the protrusion is parallel to a c-axis direction of sapphire constituting the sapphire substrate.

[0126] (Note 17)

[0127] The aluminum nitride laminated structure according to any one of Supplementary Notes 1 to 16, wherein each of the convex portions has a tapered shape.

[0128] (Note 18)

[0129] The aluminum nitride laminate structure according to Supplementary Note 17, wherein the protrusions are arranged at lattice points of a triangular lattice, a quadrangular lattice, or a hexagonal lattice.

[0130] (Note 19)

[0131] The aluminum nitride laminate structure according to Supplementary Note 18, wherein the directions of the axes of the triangular lattice, the quadrangular lattice or the hexagonal lattice are parallel to the m-axis direction or the a-axis direction of sapphire constituting the sapphire substrate.

[0132] (Note 20)

[0133] The aluminum nitride laminated structure according to Supplementary Note 1, wherein each of the protrusions is ridge-shaped and is arranged such that the ridges extend in parallel to each other.

[0134] (Note 21)

[0135] The aluminum nitride laminated structure according to any one of appendixes 1 to 20, wherein each of the convex portions is cone-shaped or ridge-shaped, and a width of a slope of each of the convex portions in a plan view is 500 nm or less.

[0136] (Note 22)

[0137] The aluminum nitride laminate structure according to any one of Supplementary Notes 1 to 21, wherein a pitch between the most adjacent protrusions is 1000 nm or less.

[0138] (Note 23)

[0139] An aluminum nitride layer having a surface on which protrusions are periodically formed,

[0140] Each of the protrusions has a hexagonal shape when viewed from above.

[0141] In each of the protrusions, the height of the protrusion is equal to or greater than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0142] In each of the protrusions, the size of the protrusion is less than 1 / 2 of the distance between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0143] A recess is formed on the outer surface of the protrusion at the base of the protrusion.

[0144] (Note 24)

[0145] An aluminum nitride layer having a surface on which protrusions are periodically formed,

[0146] Each of the protrusions has a hexagonal shape when viewed from above.

[0147] In each of the protrusions, the height of the protrusion is smaller than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon,

[0148] In each of the protrusions, the size of the protrusion is larger than 1 / 2 of the distance between the most adjacent protrusions, and the size of the protrusion is determined by the distance of the diagonal line passing through the center of the hexagon.

[0149] A raised portion is formed at the center of the protruding portion.

[0150] (Note 25)

[0151] An aluminum nitride laminated component comprising:

[0152] A sapphire substrate having a base surface on which convex portions are periodically arranged, wherein the height of the convex portions is greater than 1000 nm and the convex portions have an inclined surface; and

[0153] An aluminum nitride layer is grown on the aforementioned base surface and has a surface in which fins arranged along the circumferential direction of the aforementioned protrusions are formed above the aforementioned inclined surfaces of each aforementioned protrusion, and a plurality of rods grown along a direction intersecting the aforementioned inclined surfaces are formed between the fins arranged along the circumferential direction of the aforementioned protrusions.

Claims

1. An aluminum nitride laminated component comprising: A sapphire substrate having a base surface on which projections having a height of 500 nm or less are periodically arranged; and an aluminum nitride layer disposed on the base surface and having a surface having a protrusion formed above the top of each of the protrusions, Each of the convex portions is cone-shaped.

2. The aluminum nitride laminate structure according to claim 1, wherein: Each of the protrusions has a hexagonal outer shape in a plan view.

3. The aluminum nitride laminate structure according to claim 2, wherein: In each of the protrusions, a height of the protrusion is equal to or greater than a size of the protrusion, and the size of the protrusion is defined by a distance of a diagonal line passing through the center of the hexagon.

4. The aluminum nitride laminate structure according to claim 2, wherein: In each of the protrusions, a height of the protrusion is smaller than a size of the protrusion, and the size of the protrusion is defined by a distance of a diagonal line passing through the center of the hexagon.

5. The aluminum nitride laminate structure according to claim 2, wherein: In each of the protrusions, a size of the protrusion is equal to or smaller than 1 / 2 of a pitch between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by a distance between a diagonal line passing through the center of the hexagon.

6. The aluminum nitride laminate structure according to claim 2, wherein: In each of the protrusions, a size of the protrusion is larger than 1 / 2 of a pitch between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by a distance of a diagonal line passing through the center of the hexagon.

7. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The c-axis directions of the aluminum nitride constituting the protrusions are parallel to each other.

8. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The a-axis directions of the aluminum nitride constituting the protrusions are parallel to each other.

9. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The m-axis directions of the aluminum nitride constituting the protrusions are parallel to each other.

10. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The protrusions are arranged at grid points of a triangular grid, a quadrangular grid or a hexagonal grid.

11. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The width of the slope of each of the protrusions in a plan view is 500 nm or less.

12. The aluminum nitride laminate structure according to any one of claims 1 to 6, wherein The distance between the most adjacent protrusions is 1000 nm or less.

13. An aluminum nitride layer having a surface on which protrusions are periodically formed, Each of the protrusions has a hexagonal shape when viewed from above. In each of the protrusions, the height of the protrusion is equal to or greater than the size of the protrusion, and the size of the protrusion is defined by the distance of a diagonal line passing through the center of the hexagon, In each of the protrusions, the size of the protrusion is less than 1 / 2 of the interval between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon. A recess is formed on the outer surface of the protrusion at the base of the protrusion.

14. An aluminum nitride layer having a surface on which protrusions are periodically formed, Each of the protrusions has a hexagonal shape when viewed from above. In each of the protrusions, the height of the protrusion is smaller than the size of the protrusion, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon, In each of the protrusions, the size of the protrusion is larger than 1 / 2 of the interval between the protrusions that are most adjacent to each other, and the size of the protrusion is defined by the distance of the diagonal line passing through the center of the hexagon. A raised portion is formed at the center of the protruding portion.

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