TW201605070A - Epitaxial growth substrate production method, epitaxial growth substrate obtained therefrom, and light-emitting element using said substrate - Google Patents

Abstract

The epitaxial growth substrate production method comprises: a coating step of coating an inorganic material (66) over a relief pattern surface of a mold (140); a transfer step (P3) of bringing the inorganic material (66)-coated mold (140) into tight contact with a base material (40) to transfer the inorganic material onto the base material by following the relief pattern; and a curing step of curing the inorganic material (60) transferred onto the base material. The epitaxial growth substrate can be produced efficiently.

Description

Method for producing epitaxial growth substrate, epitaxial growth substrate obtained thereby, and light-emitting element using the same

The present invention relates to a method for producing a substrate for epitaxial growth of a semiconductor layer or the like, a substrate for epitaxial growth obtained thereby, and a light-emitting device having a semiconductor layer formed on the substrate.

A semiconductor light-emitting device usually has a light-emitting diode (LED) or a laser diode (LD), and is widely used for various light sources, illuminations, signals, and large displays used in backlight devices and the like. Wait.

A light-emitting element having a semiconductor layer such as a nitride semiconductor is generally configured by sequentially epitaxially growing a buffer layer, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on a light-transmitting substrate to form an electrical connection. The n-side electrode and the p-side electrode of each of the n-type and p-type semiconductor layers. In the light-emitting element, light generated in the active layer is emitted from the outside of the element from the exposed surface (upper surface, side surface) of the semiconductor layer, and the exposed surface (back surface, side surface) of the substrate. In such a light-emitting element, when light generated in the active layer is incident at an angle equal to or greater than a critical angle of the interface between the semiconductor layer and the electrode or the interface between the semiconductor layer and the substrate, the total reflection is repeated on the semiconductor layer. Inward and lateral propagation, during which part of the light is absorbed, and light extraction Reduced efficiency.

Therefore, in Patent Documents 1 and 2, it is disclosed that the growth surface of the semiconductor layer of the substrate is etched to form a concave-convex pattern, thereby improving the light extraction efficiency of the light-emitting element. Further, Patent Document 2 discloses that such a concavo-convex pattern is provided on the growth surface of the semiconductor layer of the substrate, whereby the dislocation density of the semiconductor layer is reduced, and the characteristics of the light-emitting element can be suppressed from deteriorating.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-206230

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2001-210598

Regarding the semiconductor light-emitting element as described above, it is required to manufacture it with higher production efficiency. Therefore, an object of the present invention is to provide a method for producing an epitaxial growth substrate for use in efficiently producing a light-emitting device such as a semiconductor light-emitting device, an epitaxial growth substrate produced by the production method, and the use of the substrate A light-emitting element of a substrate for epitaxial growth.

According to a first aspect of the present invention, a method for producing an epitaxial growth substrate for producing an epitaxial growth substrate, comprising: a coating step of a concave-convex pattern of a mold having a concave-convex pattern on a surface thereof is provided Surface coating of inorganic materials; a transfer step of adhering the mold coated with the inorganic material to a substrate, transferring the inorganic material to the substrate according to the uneven pattern, and a curing step of transferring the substrate to the substrate The above inorganic material of the material is hardened.

In the method for producing a substrate for epitaxial growth, after the transfer step, the surface of the substrate on which the inorganic material is transferred may be exposed.

In the coating step, the inorganic material may be applied to the concave portion of the concave-convex pattern surface of the mold, or the inorganic material may be applied to the convex portion of the concave-convex pattern surface of the mold.

After the transfer step, the step of etching the substrate to form a recess may be included.

According to a second aspect of the present invention, a method for producing an epitaxial growth substrate for producing an epitaxial growth substrate, comprising: a coating step of coating a solution of an inorganic material on a substrate And forming a film; the transfer step of transferring the uneven pattern to the film by pressing the film to the film having the uneven pattern, thereby forming an uneven structure on the substrate; and etching step etching The concave portion of the concave-convex structure exposes a surface of the base material, and a hardening step of curing the concave-convex structure.

In the manufacturing method of the second aspect, the step of etching the substrate to form a concave portion may be included in a region where the surface of the substrate is exposed. Further, after the etching step, a buffer layer may be formed on the surface of the substrate having the uneven structure.

In the manufacturing method of the first and second aspects, the inorganic material may be a sol. Gel material. A buffer layer may be formed on the substrate before the coating step, or a buffer layer may be formed on the surface of the substrate having the inorganic material after the transfer step.

In the above-described transfer step of the manufacturing method of the first and second aspects, the transfer may be performed while heating the inorganic material.

In the manufacturing method of the first and second aspects, the buffer layer may be formed on the substrate before the coating step, or after the transfer step, on the substrate having the inorganic material. The surface forms a buffer layer.

In the manufacturing method of the first and second aspects, i) the convex portion or the concave portion of the concave-convex pattern surface of the mold has an elongated shape of each of the ridges in plan view, and ii) the convex portion of the concave-convex pattern surface of the mold The portion or the convex portion may also have a non-uniform direction, a bending direction, and a length.

In the manufacturing method of the first and second aspects, the mold having the uneven pattern may be a mold produced by self-organization of the block copolymer. The structure formed by the self-organization of the above block copolymer may be a horizontal cylindrical structure or a vertical layered structure.

In the method for producing an epitaxial growth substrate according to the first and second aspects, the substrate may be a sapphire substrate.

The manufacturing method of the first and second aspects may further include a step of etching the substrate to form a concave portion after the transfer step.

According to a third aspect of the present invention, there is provided a substrate for epitaxial growth obtained by the method of producing the first or second aspect.

In the epitaxial growth substrate according to the third aspect, i) the convex portion or the concave portion of the concave-convex pattern surface of the epitaxial growth substrate has an elongated shape in a plan view, and ii) the epitaxial growth substrate The convex portion or the convex portion of the concave-convex pattern surface may have a non-uniform direction, a bending direction, and a length. In the epitaxial growth substrate, the extending direction of the convex portion is irregularly distributed in a plan view, and the outline of the convex portion included in the region per unit area of the concave-convex pattern has a more curved section in a plan view. Straight line interval. Further, the width of the convex portion may be constant in a direction substantially perpendicular to the extending direction of the convex portion in a plan view. The outline of the convex portion included in the region per unit area of the concave-convex pattern may include a curved section and a straight section in a plan view, and the curved section is a section in which the average value of the width of the convex portion is π The length of the (pi) ratio is divided into the outline of the convex portion in a plan view, thereby forming a plurality of sections, and the linear distance between the ends of the section is relative to the length of the contour line between the end points. The ratio is 0.75 or less, and the straight line section is a section that is not the curve section among the plurality of sections. The outline of the convex portion included in the region per unit area of the concave-convex pattern may include a curved section and a straight section in a plan view, and the curved section is a section in which the average value of the width of the convex portion is π The length of the (pi) ratio is divided into a contour in which the convex portion is viewed in a plan view, thereby forming a plurality of sections, a line segment connecting one end of the section and the middle point of the section, and the other end connecting the section and the section The angle of the two angles formed by the line segment of the midpoint is 180° or less, and the straight section is a section in which the plurality of sections are not the curve section, and the curve section in the plurality of sections The ratio is 70% or more. In addition, the Fourier transform image obtained by performing two-dimensional fast Fourier transform processing on the concavity and convexity analysis image obtained by analyzing the concavo-convex pattern by the scanning probe microscope exhibits an absolute value of the wave number of 0 μm ^-1 . The point is a substantially circular or circular pattern, and the circular or circular pattern may exist in a region where the absolute value of the wave number is within a range of 10 μm ^-1 or less.

According to a fourth aspect of the present invention, a light-emitting device comprising a semiconductor layer containing at least a first conductive type layer, an active layer, and a second conductive type layer is provided on the epitaxial growth substrate of the third aspect.

In the method for producing an epitaxial growth substrate of the present invention, the uneven pattern can be formed on the substrate by the imprint method using the roll process, so that the epitaxial growth substrate can be continuously produced at high speed. Further, the photolithography method which requires a high-priced optical precision machine and generates a large amount of waste liquid is used, and the uneven pattern is transferred by the nanoimprint method, so that the load on the environment is small. Further, since the epitaxial growth substrate of the present invention has a function of a diffraction grating substrate which improves light extraction efficiency, the light-emitting element produced by using the substrate has high luminous efficiency. Therefore, the epitaxial growth substrate of the present invention is extremely effective for the production of a light-emitting element having excellent luminous efficiency.

20‧‧‧buffer layer

22, 122‧‧‧pressure roller

23, 123‧‧‧ peeling roller

30‧‧‧Mold coating machine

40‧‧‧Substrate

60‧‧‧Inorganic materials

61‧‧‧ convex

62, 62a‧‧‧ concave and convex structures

64‧‧·coating film

66‧‧‧Inorganic materials

68‧‧·coating film

70, 70a, 70b, 71, 71a, 71b‧‧‧ recess

80, 80a, 80b, 81, 81a, 81b‧‧‧ concave pattern

100, 100a, 100b, 100c, 100d, 101, 101a, 101b, 101c, 101d‧‧‧ epitaxial growth substrate

140, 141‧‧‧ mould

140a‧‧‧The concave part of the mold

140b‧‧‧ convex part of the mold

200‧‧‧Lighting elements

220‧‧‧Semiconductor layer

222‧‧‧1st conductive layer

224‧‧‧Active layer

226‧‧‧2nd conductive layer

240‧‧‧1st electrode

260‧‧‧2nd electrode

A1, A2‧‧‧ an area protruding in the middle of the convex part

d1‧‧‧Width of area A1

d2‧‧‧Extension length of area A1

D3‧‧‧ Length through the area A1 and orthogonal to the extension axis

L1, L2‧‧‧ extension axis

d4‧‧‧Width of area A2

d5‧‧‧Extension length of area A2

D6‧‧‧ Length through the direction of the area A2 and orthogonal to the extension axis

La‧‧‧The length of the outline of the convex part of point A and point C

Lb‧‧‧ Straight line distance between point A and point C

S1‧‧‧ convex area

S2‧‧‧ recessed area

Outline of the X‧‧‧ convex

Fig. 1 is a flow chart showing a method of manufacturing the epitaxial growth substrate of the first embodiment.

2(a) to 2(e) are diagrams conceptually showing respective steps of a method of manufacturing an epitaxial growth substrate according to an embodiment.

Fig. 3 is a view showing an example of a case of an adhesion step and a peeling step in the method for producing an epitaxial growth substrate according to the first embodiment.

4(a) to 4(c) are schematic cross-sectional views showing a substrate for epitaxial growth in which a buffer layer is formed.

Fig. 5 (a) shows an example of an AFM image of the surface of the substrate obtained by the method for producing an epitaxial growth substrate according to the first embodiment, and Fig. 5 (b) shows an AFM image of Fig. 5 (a). A cross-sectional image of the substrate for epitaxial growth on the cut line.

(a) to (e) are diagrams conceptually showing respective steps of a method of manufacturing an epitaxial growth substrate according to the second embodiment.

Fig. 7 is a flow chart showing a method of manufacturing the epitaxial growth substrate of the third embodiment.

(a) to (e) are diagrams conceptually showing respective steps of a method of manufacturing an epitaxial growth substrate according to the third embodiment.

FIG. 9 is a conceptual diagram showing an example of a pressing step and a peeling step in the method for producing an epitaxial growth substrate according to the third embodiment.

10(a) to 10(c) are schematic cross-sectional views showing a substrate for epitaxial growth according to a third embodiment in which a buffer layer is formed.

Fig. 11 (a) is an AFM image example of the surface of the substrate obtained by the method for producing an epitaxial growth substrate according to the third embodiment, and Fig. 11 (b) is an AFM image of Fig. 11 (a). A cross-sectional image of the substrate for epitaxial growth on the cut line.

Fig. 12 is a schematic cross-sectional view showing an optical element of the embodiment.

Fig. 13 is an example of a plan analysis image (black and white image) of a substrate such as epitaxial growth in the embodiment.

14(a) and 14(b) are diagrams for explaining an example of a method of determining a branch of a convex portion in a plan view image.

Fig. 15(a) is a diagram for explaining the first definition method of the curve section, and Fig. 15(b) is a diagram for explaining the second definition method of the curve section.

In the following, the method for producing the epitaxial growth substrate of the present invention, the epitaxial growth substrate obtained by the substrate, and the embodiment of the light-emitting device using the substrate will be described with reference to the drawings. The first embodiment relates to a method in which an inorganic material is adhered to a convex portion of a mold, and an inorganic material is transferred to the substrate, whereby a concave-convex pattern of the inorganic material is formed on the substrate, and the second embodiment relates to an inorganic material. A method of attaching an inorganic material to a concave portion of a mold and transferring an inorganic material to the substrate to form a concave-convex pattern of the inorganic material on the substrate. In the third embodiment, the inorganic material is adhered to the substrate, and the mold is pressed against A method of forming an uneven pattern of an inorganic material on a substrate by using an inorganic material.

[First Embodiment]

A method of producing the epitaxial growth substrate of the first embodiment will be described. The manufacturing method of the epitaxial growth substrate is mainly as shown in FIG. 1 : a solution preparation step P1 for preparing a sol-gel material; and a coating step P2 for applying the prepared sol-gel material to a mold. The adhesion step P3 is to adhere the coated sol-gel material to the substrate; the peeling step P4 is to peel the mold from the coating film; and the curing step P5 is to cure the coating film. Further, the adhesion step P3 and the peeling step P4 are collectively referred to as a transfer step. Hereinafter, the mold for transferring the uneven pattern and the method for producing the same will be described first, and the above respective steps will be sequentially described with reference to FIGS. 2(a) to 2(e).

<Concave pattern transfer printing mold>

The mold for transfer of the uneven pattern used for the production of the substrate for epitaxial growth includes, for example, a metal mold or a film-shaped resin mold produced by the following method. Resin mold The resin also includes rubber such as natural rubber or synthetic rubber. The mold has a concave-convex pattern on the surface. The shape of the concave-convex pattern of the mold is not particularly limited, and the cross-sectional shape of the concave-convex pattern may be formed by a relatively gentle inclined surface to form a corrugated structure. The planar shape of the concave-convex pattern of the mold may extend continuously in the shape of a convex ridge, or may be formed by a concave or convex portion of the elongated shape of the crucible. Since the mold is less likely to cause mold clogging, the frequency of cleaning or replacement of the mold can be reduced, and the production can be continuously performed at a high speed for a long time, and the manufacturing cost can be suppressed. The ridge-like extension or the elongated concave or convex portion of the ridge may also branch on the way.

An example of a method of manufacturing a mold for transferring a concave-convex pattern will be described. First, a master pattern for forming a concave-convex pattern of a mold is produced. In the case where the concave-convex pattern of the mother die is, for example, the above-mentioned convex portion (or concave portion) ridge-likely extending concave-convex pattern, it is preferably formed by the following method: as described in WO2012/096368, the applicant et al. The method of self-organizing (microphase separation) of the block copolymer by heating (hereinafter, referred to as "BCP (Block Copolymer) thermal annealing method" as appropriate) or the use described in WO2013/161454 The method of self-organizing a block copolymer in a solvent environment (hereinafter, referred to as "BCP solvent annealing method" as appropriate) or WO2011/007878A1 by heating and cooling a vapor deposited film on a polymer film by polymerization A method of forming irregularities on the wrinkles of the surface of the object (hereinafter, referred to as "BKL (Buckling) method" as appropriate). In the case of patterning by BCP thermal annealing or BCP solvent annealing, the material for patterning may be any material, but is preferably selected from a styrenic polymer such as polystyrene selected from polystyrene. a block composed of a combination of two of a group consisting of a polymethyl methacrylate of a methyl ester, polyethylene oxide, polybutadiene, polyisoprene, polyvinyl pyridine, and polylactic acid Copolymer. The pattern formed by the self-organization of the materials is preferably a horizontal cylindrical structure as described in WO 2013/161454 (a structure in which a cylinder is horizontally aligned with respect to a substrate) or as described in Macromolecules 2014, 47, 2. The vertical layered structure (the structure in which the layer is vertically aligned with respect to the substrate) is more preferably a vertical layered structure in order to form deeper unevenness. Further, the concave-convex pattern obtained by the solvent annealing treatment may be etched by irradiation with an energy ray represented by ultraviolet rays such as excimer UV light, or dry by RIE (Reactive Ion Etching) and ICP etching. Etching is performed by etching. Further, heat treatment may be performed on the uneven pattern that has been etched as described above. Further, the concave-convex depth formed by the BCP thermal annealing method or the BCP solvent annealing method can be formed by a method as described in Adv. Mater. 2012, 24, 5688-5694, Science 322, 429 (2008) or the like. Larger concave and convex pattern. That is, the block copolymer is coated on the underlayer composed of SiO ₂ , Si or the like, and the self-organized structure of the block copolymer is formed by BCP thermal annealing or BCP solvent annealing. A segment of the block copolymer is then selectively etched and removed. The remaining segment is masked and the underlayer is etched to form a trench (recess) of the desired depth at the bottom layer. The average value of the depth distribution of the concavities and convexities of the concavo-convex pattern is preferably in the range of 20 nm to 10 μm, more preferably in the range of 50 nm to 5 μm. If the average value of the depth distribution of the concavities and convexities does not reach the above lower limit, there is a tendency that the depth is too small with respect to the emission wavelength, and the desired diffraction is not generated. On the other hand, if the average value of the depth distribution of the concavities and convexities exceeds the upper limit, When a semiconductor layer is laminated on a substrate to produce a light-emitting element, the thickness of the semiconductor layer necessary for planarization of the surface of the semiconductor layer is increased, and the time required for the production of the light-emitting element becomes long. The average value of the depth distribution of the concavities and convexities is more preferably in the range of 100 nm to 2 μm.

A photolithography method may be used instead of the BCP thermal annealing method, the BKL method, and the BCP solvent annealing method described above to form a concavo-convex pattern. In addition, for example, a master mold can be produced by a micromachining method such as a cutting method, an electron beam direct drawing method, a particle beam processing method, or an operation probe processing method, or a microfabrication method using self-organization of fine particles. Concave pattern.

After the master mold of the concavo-convex pattern is formed by a BCP thermal annealing method, a BKL method, a BCP solvent annealing method, or the like, a mold to which a pattern is transferred can be formed by electroforming or the like. First, a seed layer which is a conductive layer for electroforming can be formed on a mother mold having a pattern by electroless plating, sputtering, vapor deposition, or the like. As for the seed layer, in order to make the current density in the subsequent electroforming step uniform, and to make the thickness of the metal layer deposited by the subsequent electroforming step constant, it is preferably 10 nm or more. As the material of the seed layer, for example, nickel, copper, gold, silver, platinum, titanium, cobalt, tin, zinc, chromium, gold-cobalt alloy, gold-nickel alloy, boron-nickel alloy, solder, copper-nickel can be used. - chromium alloy, tin-nickel alloy, nickel-palladium alloy, nickel-cobalt-phosphorus alloy, or alloys thereof. Then, a metal layer is deposited on the seed layer by electroforming (electroplating). The thickness of the metal layer can be set to a thickness of, for example, 10 to 30000 μm as a whole including the thickness of the seed layer. As the material of the metal layer deposited by electroforming, any of the above-mentioned metal materials which can be used as the seed layer can be used. Regarding the metal layer to be formed, it is preferable to have appropriate hardness and thickness in terms of ease of treatment such as pressing, peeling, and washing of the resin layer for forming the subsequent mold.

The metal layer containing the seed layer obtained in the above manner was peeled off from the master mold having the uneven structure to obtain a metal substrate. The peeling method may be physically stripped, or may be dissolved and removed using an organic solvent which dissolves the pattern-forming material, for example, toluene, tetrahydrofuran (THF), chloroform or the like. When the metal substrate is peeled off from the master mold, the remaining material components can be removed by washing. As the washing method, wet cleaning using a surfactant or the like or dry cleaning using ultraviolet rays or plasma can be used. Further, for example, an adhesive or an adhesive may be used to adhere and remove the remaining material components. The metal substrate (metal mold) from which the pattern is transferred from the master mold obtained in the above manner can be used as the mold for transfer of the uneven pattern of the present embodiment.

Further, by using the obtained metal substrate, the uneven structure (pattern) of the metal substrate is transferred to the film-shaped support substrate, whereby a mold which is flexible like a film mold can be produced. For example, after applying a curable resin to a support substrate, the uneven structure of the metal substrate is pressed against the resin layer and the resin layer is cured. Examples of the support substrate include a substrate made of an inorganic material such as glass, quartz or ruthenium; and a polysiloxane resin, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The basis of organic materials such as polycarbonate (PC), cycloolefin polymer (COP), polymethyl methacrylate (PMMA), polystyrene (PS), polyimine (PI), polyarylate, etc. Metal materials such as nickel, copper and aluminum. Further, the thickness of the support substrate can be set in the range of 1 to 500 μm.

Examples of the curable resin include epoxy, acrylic, methacrylic, vinyl ether, oxetane, amine ester, melamine, urea, polyester, and polyolefin. Various resins such as a phenol-based, cross-linked liquid crystal system, a fluorine-based, polyfluorene-based or polyamid-based monomer, an oligomer, and a polymer. The thickness of the curable resin is preferably in the range of 0.5 to 500 μm. When the thickness is less than the lower limit, the height of the unevenness formed on the surface of the cured resin layer tends to be insufficient. When the thickness exceeds the above upper limit, there is a possibility that the influence of the volume change of the resin generated during curing becomes large. However, it becomes impossible to form the uneven shape well.

As a method of applying the curable resin, for example, a spin coating method, a spray coating method, a dip coating method, a dropping method, a gravure printing method, a screen printing method, a letterpress printing method, a die coating method, or a curtain coating method can be employed. Various coating methods such as a cloth method, an inkjet method, and a sputtering method. Further, the conditions for curing the curable resin vary depending on the type of the resin to be used. For example, the curing temperature is preferably in the range of room temperature to 250 ° C, and the curing time is in the range of 0.5 minute to 3 hours. Further, the method may also be irradiated by ultraviolet or electron beam energy ray curable resin is cured the sum of, in the case when the irradiation amount is preferably in the range of ^{20mJ / cm 2 ~ 5J / cm} 2 of.

Then, the hardened resin layer after hardening is removed from the metal substrate. The method of removing the metal substrate is not limited to the mechanical peeling method, and a known method can be employed. A resin mold having a film shape having a cured resin layer having irregularities formed on the support substrate as described above can be used as the mold for transfer of the uneven pattern of the present embodiment.

Moreover, a rubber-based resin material is applied to the uneven structure (pattern) of the metal substrate obtained by the above method, and the applied resin material is cured and peeled off from the metal substrate, whereby a metal substrate can be transferred and transferred. The rubber mold of the concave and convex pattern. The obtained rubber mold can be used as a mold for transfer of concave-convex patterns of the present embodiment. The rubber-based resin material is preferably a polyoxyethylene rubber, or a mixture or copolymer of a polyoxyxene rubber and other materials. As the polyoxyxene rubber, for example, polyorganosiloxane, crosslinked polyorganosiloxane, polyorganosiloxane/polycarbonate copolymer, polyorganosiloxane/polyphenylene copolymer, polyorganofluorene can be used. Oxylkane/polystyrene copolymer, polytrimethyldecylpropyne, polytetramethylpentene, and the like. Compared with other resin materials, polyoxymethylene rubber is inexpensive, has excellent heat resistance, has high thermal conductivity, is elastic, and is difficult to be deformed even under high temperature conditions. Therefore, when a concave-convex pattern transfer process is performed under high temperature conditions, good. Further, since the material of the polyoxymethylene rubber has high gas permeability or water vapor permeability, the solvent or water vapor of the material to be transferred can be easily penetrated. Therefore, in the case where a rubber mold is used to transfer the uneven pattern to the sol-gel material as described below, the material of the polyoxymethylene rubber is preferable. Further, the surface free energy of the rubber-based material is preferably 25 mN/m or less. Thereby, the mold release property at the time of transferring the uneven pattern of the rubber mold to the coating film on the substrate becomes good, and the transfer failure can be prevented. The rubber mold can be, for example, a length of 50 to 1000 mm, a width of 50 to 3000 mm, and a thickness of 1 to 50 mm. If the thickness of the rubber mold is less than the above lower limit, the strength of the rubber mold becomes smaller, so that the rubber mold is Damage during operation. When the thickness is larger than the above upper limit, it becomes difficult to peel off the mold at the time of rubber mold production. Further, the mold release treatment may be performed on the concave-convex pattern surface of the rubber mold as needed. The description of the concave-convex pattern transfer mold described herein is suitable for the molds used in the second and third embodiments described below.

<Sol-gel material solution preparation step>

The sol-gel material solution used in the first to third embodiments and a method for producing the same will be described. First, a solution of a sol-gel material (inorganic material) is prepared. As the sol-gel material, in particular, cerium oxide, a Ti-based material, or an ITO (indium-tin oxide)-based material, a sol-gel material such as ZnO, ZrO ₂ or Al ₂ O ₃ can be used. For example, when a convex portion (or a concavo-convex portion) composed of cerium oxide is formed on a substrate by a sol-gel method, a metal alkoxide (cerium oxide precursor) is prepared as a sol-gel material. As the precursor of cerium oxide, tetramethoxy decane (TMOS), tetraethoxy decane (TEOS), tetraisopropoxy decane, tetra-n-propoxy decane, tetraisobutoxy decane, and tetra can be used. a tetraalkoxide monomer represented by a tetraalkoxy decane such as n-butoxydecane, tetra-butoxy decane or tetra-butoxy decane, or methyltrimethoxydecane or ethyltrimethoxy Decane, propyltrimethoxydecane, isopropyltrimethoxydecane, phenyltrimethoxydecane, methyltriethoxydecane (MTES), ethyltriethoxydecane, propyltriethoxydecane , isopropyl triethoxy decane, phenyl triethoxy decane, methyl tripropoxy decane, ethyl tripropoxy decane, propyl tripropoxy decane, isopropyl tripropoxy decane , phenyl tripropoxy decane, methyl triisopropoxy decane, ethyl triisopropoxy decane, propyl triisopropoxy decane, isopropyl triisopropoxy decane, phenyl triiso a trialkoxide monomer represented by a trialkoxy decane such as propoxy decane or tolyl triethoxy decane, dimethyldimethoxydecane, dimethyl Ethoxy decane, dimethyl dipropoxy decane, dimethyl diisopropoxy decane, dimethyl di-n-butoxy decane, dimethyl di-isobutoxy decane, dimethyl di - a second butoxy decane, dimethyl di-t-butoxy decane, diethyl dimethoxy decane, diethyl diethoxy decane, diethyl dipropoxy decane, diethyl Diisopropoxydecane, diethyldi-n-butoxydecane, diethyldi-isobutoxydecane, diethyldi-second butoxydecane, diethyldi-t-butoxide Base decane, dipropyl dimethoxy decane, dipropyl diethoxy decane, dipropyl dipropoxy decane, dipropyl diisopropoxy decane, dipropyl di-n-butoxy decane , dipropyl di-isobutoxydecane, dipropyl di-second butoxydecane, dipropyl di-t-butoxydecane, diisopropyldimethoxydecane, diisopropyl Diethoxydecane, diisopropyldipropoxydecane, diisopropyldiisopropoxydecane, diisopropyldi-n-butoxydecane, diisopropyldi-isobutoxydecane Diisopropyldi-second butoxy oxime , diisopropyldi-t-butoxydecane, diphenyldimethoxydecane, diphenyldiethoxydecane, diphenyldipropoxydecane, diphenyldiisopropoxydecane Dialkyloxy such as diphenyldi-n-butoxydecane, diphenylbis-isobutoxydecane, diphenyldi-secondbutoxydecane, diphenyldi-t-butoxydecane a dioxane monomer represented by a decane. Further, an alkyltrialkoxide or a dialkyldialkoxydecane having an alkyl group having a C4 to C18 carbon number may also be used. A vinyl monomer such as vinyl trimethoxy decane or vinyl triethoxy decane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxynonane or 3-glycidyloxy can also be used. Propylmethyldimethoxydecane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, 3-glycidoxypropyltriethyl a monomer having an epoxy group such as oxydecane, a monomer having a styryl group such as p-styryltrimethoxydecane, 3-methylpropenyloxypropylmethyldimethoxydecane, 3-methyl Methyl propylene such as propylene methoxy propyl trimethoxy decane, 3-methyl propylene methoxy propyl methyl diethoxy decane, 3-methyl propylene methoxy propyl triethoxy decane a monomer having a fluorenyl group such as a monomer of a mercapto group, a 3-propenylmethoxypropyltrimethoxydecane, or an N-2-(aminoethyl)-3-aminopropylmethyldimethoxy group Decane, N-2-(aminoethyl)-3-aminopropyltrimethoxydecane, 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-tri Ethoxy decyl-N-(1,3-dimethyl-arylene) a monomer having an amine group such as propylamine or N-phenyl-3-aminopropyltrimethoxydecane, a monomer having a urea group such as 3-ureidopropyltriethoxydecane, or a 3-mercapto group a monomer having a mercapto group such as a monomer having a mercapto group such as propylmethyldimethoxydecane or 3-mercaptopropyltrimethoxydecane, or a monomer having a sulfur group such as bis(triethoxydecylpropyl)tetrasulfide; a monomer having an isocyanate group such as isocyanatopropyltriethoxysilane or a polymer obtained by polymerizing the monomers in a small amount, and is characterized by a metal alkane such as a composite material having a functional group or a polymer introduced into one of the above materials. Oxide. Further, one or both of the alkyl group or the phenyl group of the compounds may be substituted with fluorine. Further, examples thereof include an ethyl acetonide metal salt, a metal carboxylate, an oxychloride, a chloride, or a mixture thereof, but are not limited thereto. Examples of the metal material include, but are not limited to, Si, Ti, Sn, Al, Zn, Zr, In, etc., or the like, but are not limited thereto. It is also possible to use a precursor that is appropriately mixed with the above-mentioned oxidized metal. Further, it is also possible to perform mesoporation by adding a surfactant to the materials. Further, the surfaces may be hydrophobized. The method of hydrophobization treatment may be a known method. For example, if it is a surface of cerium oxide, it may be hydrophobized by dimethyldichlorosilane or trimethyl alkoxy decane, or may be used. A method of hydrophobizing a trimethylsulfonating agent such as methyldiazepine or a polyoxyxanic acid may also be carried out by a surface treatment method using a metal oxide powder of supercritical carbon dioxide. Further, as the precursor of cerium oxide, a decane coupling agent having a hydrophilic group having reactivity with cerium oxide and reactivity and a water-repellent organic functional group in the molecule can be used. For example, a decane monomer such as n-octyltriethoxydecane, methyltriethoxydecane or methyltrimethoxydecane, vinyltriethoxydecane, vinyltrimethoxydecane or vinyltrile may be mentioned. Vinyl decane such as (2-methoxyethoxy)decane, vinylmethyldimethoxydecane, 3-methylpropenyloxypropyltriethoxydecane, 3-methylpropenyloxyl Methyl propylene decyl decane such as propyl trimethoxy decane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxy decane, 3-glycidoxypropyltrimethoxy decane, 3-shrinkage Ethylene decane such as glyceryloxypropyl triethoxy decane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltriethoxydecane, etc., decyl decane, 3-octyl thiol-1-propyltriethyl Thionine such as oxoxane, 3-aminopropyltriethoxydecane, 3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropyltrimethoxy An amine decane such as decane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane or 3-(N-phenyl)aminopropyltrimethoxydecane, A polymer obtained by polymerizing a monomer or the like.

In the case where a mixture of TEOS and MTES is used as a solution of the sol-gel material, the mixing ratio can be set to 1:1, for example, in a molar ratio. The amorphous cerium oxide is produced by subjecting the sol-gel material to hydrolysis and polycondensation reaction. In order to adjust the pH of the solution to a synthesis condition, an acid such as hydrochloric acid or a base such as ammonia is added. The pH is preferably 4 or less or 10 or more. Further, water may be added for the purpose of hydrolysis. The amount of water to be added can be 1.5 times or more in terms of the molar ratio with respect to the metal alkoxide species.

Examples of the solvent of the sol-gel material solution include alcohols such as methanol, ethanol, isopropyl alcohol (IPA), and butanol, and aliphatic hydrocarbons such as hexane, heptane, octane, decane, and cyclohexane. Aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene, diethyl ether, tetrahydrofuran, and Ethers such as alkane, ketones such as acetone, methyl ethyl ketone, isophorone, cyclohexanone, butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol, benzyloxyethanol Ether ethers, alcohols such as ethylene glycol and propylene glycol, glycol ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate, Esters such as γ-butyrolactone, phenols such as phenol and chlorophenol, amides such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone A halogen-based solvent such as chloroform, dichloromethane, tetrachloroethane, monochlorobenzene or dichlorobenzene, a hetero atom-containing compound such as carbon disulfide, water, or a mixed solvent thereof. In particular, ethanol and isopropyl alcohol are preferred, and those in which water is mixed are also preferred.

As an additive of the sol-gel material solution, an alkanolamine such as polyethylene glycol, polyethylene oxide, hydroxypropyl cellulose, polyvinyl alcohol, or triethanolamine as a solution stabilizer may be used for adjusting the viscosity. , β-diketone such as acetamidine, β-ketoester, formamide, dimethylformamide, two Alkane, etc. Further, as an additive to the sol-gel material solution, a material which generates an acid or an alkali by irradiation with light such as an energy ray represented by ultraviolet rays such as excimer UV light can be used. By adding the above materials, it becomes possible to harden the sol-gel material solution by irradiating light.

<Coating step>

As shown in Fig. 2(a), a solution of the sol-gel material (inorganic material) prepared in the above manner is applied onto the concave-convex pattern of the mold 140, and a coating film 66 is formed in the concave portion 140a of the mold 140. At this time, it is preferable to fill only the solution of the sol-gel material into the concave portion 140a of the mold 140, and the solution of the sol-gel material is not adhered to the convex portion 140b of the mold 140. Therefore, the coating amount of the sol-gel material solution is preferably set to be equal to the volume of the concave portion of the mold. As the mold 140, the above-described concave-convex pattern transfer mold can be used, but it is preferable to use a film mold having flexibility or flexibility. For example, as shown in FIG. 3, the film-shaped mold 140 may be fed to the vicinity of the front end of the die coater 30, and the sol-gel material may be ejected from the die coater 30 to form a coating on the concave portion 140a of the film-shaped mold 140. Membrane 66. From the viewpoint of mass productivity, it is preferred to continuously transport the film mold on one side. The sol gel material is continuously applied to the film mold 140 by a die coater 30 provided at a specific position. As the coating method, any coating method such as a bar coating method, a spray coating method, a die coating method, or an inkjet method can be used, but the sol-gel material can be uniformly applied to the width relative to each other. A larger mold, which can be quickly applied before gelation of the sol-gel material, is preferably a die coating method.

<Close step>

As shown in FIG. 2(b), the mold 140 on which the coating film 66 of the sol-gel material is formed is pressed against the substrate 40, whereby the coating film 66 is adhered to the substrate 40. Thereby, the coating film 66 is adhered to a portion of the substrate 40 that faces the concave portion 140a of the mold 140. At this time, the mold 140 may be pressed against the substrate 40 using a pressing roller (adhesive roller). As the substrate 40, various substrates having light transmissivity can be used. For example, glass, sapphire single crystal (Al ₂ O ₃ : A surface, C surface, M surface, R surface), spinel single crystal (MgAl ₂ O ₄ ), ZnO single crystal, LiAlO ₂ single crystal, LiGaO ₂ single crystal, oxide single crystal such as MgO single crystal, Si single crystal, SiC single crystal, SiN single crystal, GaAs single crystal, AlN single crystal, GaN single crystal, and boride single crystal such as ZrB ₂ Substrate. Among these, a sapphire single crystal substrate and a SiC single crystal substrate are preferable. Further, the surface orientation of the substrate is not particularly limited. Further, the substrate may be a just substrate having an off angle of 0 degrees, or may be a substrate provided with an off angle. The substrate 40 may also be subjected to a hydrophilic treatment of the surface by treatment with O ₃ or the like. By subjecting the surface of the substrate 40 to a hydrophilic treatment, the adhesion between the substrate 40 and the coating film 66 of the sol-gel material can be increased. In the example in which the mold is pressed against the base material by using the pressure roller, for example, as shown in FIG. 3, a coating film 66 is fed between the pressure roller 22 and the substrate 40 that is conveyed directly below the roller. The film mold 140 can thereby adhere the coating film 66 formed on the concave portion 140a of the film mold 140 to the substrate 40. In other words, when the film-shaped mold 140 in which the coating film 66 is formed in the concave portion 140a is pressed against the base material 40 by the pressing roller 22, the film-shaped mold 140 and the base material 40 are simultaneously conveyed, and the film-shaped mold 140 is coated. The surface of the material 40. At this time, the pressing roller 22 is pressed against the back surface of the film-shaped mold 140 (the surface opposite to the surface on which the uneven pattern is formed), thereby forming the coating film 66 and the substrate 40 in the concave portion 140a of the film-shaped mold 140. Adjacent to one side. Further, when the long film-shaped mold 140 is fed toward the pressing roller 22, it is advantageous to use the film winding roller that winds up the long film-shaped mold 140 to directly wind up the film-shaped mold 140.

In the adhesion step, the coating film can also be heated when the coating film is pressed against the substrate. For example, the coating film may be heated by pressing against the roller, or the coating film may be heated directly or from the substrate side. In the case where the coating film is heated by the pressing roller, a heating means may be provided inside the pressing roller (adhesive roller), and any heating means may be used. It is preferable that the inside of the pressure roller is provided with a heater, but a heater separate from the pressure roller may be provided. In any case, any pressure roller can be used as long as it can be pressed while heating the coating film. The pressure roller is preferably a roll of a resin material such as an ethylene-propylene-diene rubber (EPDM) or a polyoxyxene rubber, a nitrile rubber, a fluororubber, an acrylic rubber or a chloroprene rubber having heat resistance on the surface. Further, in order to counteract the pressure applied by the pressing roller, the supporting roller may be provided in such a manner as to oppose the pressing roller and sandwich the substrate, or a support table for supporting the substrate may be provided.

When the film is heated (pressed), the heating temperature of the coating film can be set to room temperature to 300 ° C. When heating with a pressure roller, the heating temperature of the pressure roller can be similarly set to room temperature to 200 ° C. . By heating the pressing roller in the above manner, the mold can be peeled off immediately from the coating film which is pressed by the mold, and the productivity can be improved. If the heating temperature of the coating film or the pressing roller exceeds 200 ° C, there is a higher temperature than the heat resistance temperature of the mold composed of the resin material. Further, by heating the coating film while pressing it, the same effect as the pre-baking of the sol-gel material layer described below can be expected.

After the coating film is adhered to the substrate, the coating film may be pre-fired. In the case where the coating film is not heated and pressed, it is preferred to perform calcination. The gelation of the coating film is carried out by pre-baking, and the pattern is cured, and the pattern is not easily deformed when the mold is peeled off. In the case of pre-baking, it is preferred to heat at room temperature to 300 ° C in the atmosphere. Furthermore, pre-firing does not necessarily have to be carried out. Further, when a material which generates an acid or an alkali by irradiation with light such as ultraviolet rays is added to the sol-gel material solution, an energy line represented by ultraviolet rays such as excimer UV light may be irradiated instead of pre-coating the coating film. Burnt.

<Peeling step>

The coating film and the substrate after the self-adhesive step are peeled off from the mold. After the mold is peeled off, as shown in FIG. 2(c), the coating film of the sol-gel material is adhered to the portion of the base material 40 corresponding to the concave portion 140a of the mold 140 to form the convex portion 60. The surface of the substrate 40 is exposed in a region other than the region corresponding to the concave portion 140a of the mold 140 (the region of the base material 40 where the convex portion 60 is formed). In this way, a region (concave portion 70) where the surface of the substrate is exposed is defined between the convex portions 60 composed of the sol-gel material. As the peeling method of the mold, a known peeling method can be employed. It is also possible to peel off the mold while heating, whereby the generated gas escapes from the coating film to prevent generation of bubbles in the film. When the roll process is used, the peeling force can be made smaller than that of the plate-shaped mold used in a pressurized manner, so that the film can be easily peeled off from the coating film without remaining in the mold. In particular, since the coating is pressed while heating the coating film, the reaction proceeds easily, and the mold is easily peeled off from the coating film immediately after the pressing. Further, in order to improve the peelability of the mold, a peeling roll can also be used. As shown in FIG. 3, the peeling roller 23 is provided on the downstream side of the pressing roller 22, and the film-shaped mold 140 and the coating film 66 are pressed by the peeling roller 23 to the base material 40, and rolling support is performed. The state in which the film-like mold 140 and the coating film 66 are adhered to the base material 40 is maintained only by the distance between the roller 22 and the peeling roller 23 (for a certain period of time) between). Then, on the downstream side of the peeling roller 23, the path of the film-shaped mold 140 is changed so that the film-shaped mold 140 is pulled up to the peeling roller 23, whereby the film-shaped mold 140 is formed of a coating film of a free sol-gel material. The convex portion 60 and the base material 40 are peeled off. Further, the above-mentioned coating film may be pre-fired or heated while the film-shaped mold 140 is attached to the substrate 40. Further, when the peeling roller 23 is used, for example, peeling can be performed by heating to room temperature to 300 ° C to facilitate peeling of the coating film. Further, the heating temperature of the peeling roller 23 may be set to be higher than the heating temperature of the pressing roller or the pre-baking temperature. In this case, peeling is performed while heating to a high temperature, whereby the generated gas escapes from the coating film 66, and generation of bubbles can be prevented. Further, in FIG. 3, the coating film 66 which is not adhered to the substrate 40, that is, the coating film formed in the region between the substrate 40 and the continuously conveyed substrate 40 of the film-like mold 140 is formed. 66 is conveyed together with the film mold 140 in a state of being directly attached to the concave portion 140a of the film mold 140.

<hardening step>

After the mold is peeled off, the convex portion 60 composed of the sol-gel material is cured. The convex portion 60 can be hardened by performing main firing. By the main baking, the hydroxyl group contained in the cerium oxide (amorphous cerium oxide) constituting the convex portion 60 is detached, and the coating film becomes stronger. The main firing can be carried out at a temperature of 600 to 1200 ° C for about 5 minutes to 6 hours. Thus, the convex portion 60 is cured, and the convex portion 60 formed on the substrate 40 and the epitaxial growth substrate 100 in which the concave-convex pattern 80 is formed in the concave portion 70 can be formed. In this case, when the convex portion 60 is composed of cerium oxide, it is amorphous or crystalline depending on the firing temperature and firing time, or a mixed state of amorphous and crystalline. Further, when a material which generates an acid or an alkali by irradiation with light such as ultraviolet rays is added to the sol-gel material solution, instead of firing the convex portion 60, for example, an energy represented by ultraviolet rays such as excimer UV light may be irradiated. The wire, whereby the convex portion 60 can be hardened.

As shown in Fig. 2(e), the exposed substrate surface of the epitaxial growth substrate 100 manufactured by the method of the above embodiment can be etched to form the concave portion 70a in the substrate 40. Thereby, the epitaxial growth substrate 100a is formed, and the epitaxial growth substrate 100a is formed with the concave-convex pattern 80a composed of the convex portion 60 and the concave portion 70a. Since the epitaxial growth substrate 100a is formed with the concave portion 70a in the base material 40, the unevenness of the concave-convex pattern can be made larger than that of the substrate 100 in which the substrate 40 is not etched. In the case where a sapphire substrate is used as the substrate, etching of the substrate can be performed, for example, by using RIE using a gas containing BCl ₃ or the like.

In the above manner, the buffer layer may be formed on the surface of the substrate on which the uneven patterns 80 and 80a are formed (the surface on which the uneven pattern is formed). Thereby, the epitaxial growth substrates 100b and 100c having the buffer layer 20 on the surface of the uneven patterns 80 and 80a as shown in FIGS. 4(a) and 4(b) can be obtained. When the cross-sectional shape of the concave-convex pattern is composed of a relatively gentle inclined surface and a corrugated structure is formed, a uniform buffer layer having less defects can be formed.

Further, a buffer layer may be formed on the substrate before the coating step. Thereby, as shown in FIG. 4(c), the convex portion 60 is formed on the buffer layer 20, and the region where the surface of the buffer layer is exposed (the concave portion 70b) is defined between the convex portions 60. Thereby, the epitaxial growth substrate 100d on which the uneven pattern 80b is formed can be obtained.

The buffer layer 20 can be formed by a known method such as a low temperature MOCVD method or a sputtering method. The layer thickness of the buffer layer 20 is preferably in the range of 1 nm to 100 nm. When the semiconductor layer is epitaxially grown on the surface of the epitaxial growth substrates 100b, 100c, and 100d having the buffer layer, the difference in lattice constant between the substrate and the semiconductor layer can be relaxed by the buffer layer to form crystallinity. Higher semiconductor layer. When the GaN-based semiconductor layer is epitaxially grown on the epitaxial growth substrate of the embodiment, the buffer layer may be made of Al _x Ga _{1 x} N (0≦×≦1), and is not limited to a single-layer structure. It is also possible to have a multilayer structure in which two or more layers having two or more different compositions are laminated.

In the method for producing an epitaxial growth substrate in which the surface of the substrate is embossed and the surface of the substrate is embossed, as in the prior art described in Patent Documents 1 and 2, only the concave-convex pattern is formed. The bump depth etches the substrate. On the other hand, in the method for producing an epitaxial growth substrate of the present embodiment, the coating film of the sol-gel material is adhered only to the region where the convex portion is finally formed by the adhesion step, so that the mold is applied to the mold. At the time after the peeling, a part of the surface of the substrate other than the region where the convex portion is formed is exposed. Therefore, in the method for producing an epitaxial growth substrate of the present embodiment, it is not necessary to perform etching for exposing the surface of the substrate, and the manufacturing time can be shortened. Further, when the surface of the substrate is etched, the surface of the substrate exposed by the etching may be broken (damaged), and the chemical solution treatment may be performed after the etching. However, in the present embodiment, In the method for producing an epitaxial growth substrate, etching is not required, so that the above-described damage is not caused, and chemical solution treatment is not required. Therefore, the manufacturing time of the substrate can be shortened by the method of manufacturing the epitaxial growth substrate of the present embodiment.

Further, since the method for producing an epitaxial growth substrate of the present embodiment can be applied to the above-described roll process as described above, the epitaxial growth substrate can be continuously produced at a high speed. Further, since the embossing pattern can be transferred by the nanoimprint method without using the photolithography method as described above, the production cost of the epitaxial growth substrate can be reduced, and the load on the environment can be reduced.

In the epitaxial growth substrate 100 formed by the above-described manufacturing method, since the convex portion 60 is formed of an inorganic material, the epitaxial growth substrate 100 has excellent heat resistance.

Further, in the epitaxial growth substrates 100 and 100a to 100d shown in FIG. 2(d)(e) and FIGS. 4(a) to 4(c) manufactured by the manufacturing method of the present embodiment, The convex portion 60 and the concave portions 70, 70a, and 70b on the base material 40 constitute the concave-convex patterns 80, 80a, and 80b. Figure 5 (a) shows an example of an AFM image of the epitaxial growth substrate manufactured by the manufacturing method of the present embodiment, and FIG. 5(b) shows an epitaxial crystal in a straight line in the AFM image of FIG. 5(a). A cross-sectional image of the substrate for growth.

The cross-sectional shape of the concave-convex pattern of the epitaxial growth substrate is not particularly limited, and can be as shown in FIGS. 2(d), (e), 4(a), (b), (c), and 5(b). A waveform formed by a relatively gentle inclined surface and formed upward from the base material 40 (referred to as "waveform structure" as appropriate in the present application). That is, the convex portion may have a cross-sectional shape that is narrowed from the bottom to the top of the substrate side.

The planar shape of the concave-convex pattern of the epitaxial growth substrate obtained in the present application is not particularly limited, and may be a regular alignment pattern such as a stripe, a wavy stripe, a zigzag regular alignment pattern, or a dot pattern. As shown in Fig. 5(a), an example of an AFM image of a concave-convex pattern on a surface of a substrate, the convex portion (white portion) is continuously extended in a ridge shape, and the extending direction, the bending direction, and the extending length are irregular in plan view. That is, it may have the following features: i) the convex portion (or the concave portion) has an elongated shape in which each of the convex portions and extends, and ii) the convex portion (or the concave portion) has a non-uniform direction, a bending direction, and a length in the concave-convex pattern. When the concave-convex pattern of the epitaxial growth substrate has the above-described characteristics, even if the concave-convex pattern 80 is cut in any direction orthogonal to the surface of the substrate 40, the unevenness profile is repeated. Further, the convex portion (or the concave portion) may be branched in part or all in the plan view (see FIG. 5(a)). Further, in Fig. 5(a), the distance between the convex portions (or the concave portions) is uniform as a whole.

When the epitaxial growth substrate obtained in the present application is used as a substrate of a light-emitting element formed of, for example, a GaN-based semiconductor material, in order to improve the light extraction efficiency of the light-emitting element, the unevenness is preferably a Fourier transform image. If there is a width in the frequency distribution of the ring shape, it is preferably an irregular pattern such as irregularities with no directivity. case. In order to cause the epitaxial growth substrate 100 to function as a diffraction grating for improving the light extraction efficiency of the light-emitting element, the average pitch of the concavities and convexities is preferably in the range of 100 nm to 10 μm, more preferably in the range of 100 nm to 1,500 nm. When the average pitch of the concavities and convexities is less than the lower limit, the pitch of the light-emitting elements is too small, so that the pitch of the light caused by the unevenness does not occur. On the other hand, if the average pitch of the irregularities exceeds At the upper limit, there is a tendency that the diffraction angle becomes small and the function as a diffraction grating is lost. The average pitch of the concavities and convexities is further preferably in the range of 200 nm to 1200 nm.

The average value of the depth distribution of the concavities and convexities is preferably in the range of 20 nm to 10 μm. The average value of the depth distribution of the concavities and convexities is preferably in the range of 50 nm to 5 μm. If the average value of the depth distribution of the concavities and convexities does not reach the above lower limit, there is a tendency that the depth is too small with respect to the emission wavelength, so that the desired On the other hand, when the average value of the depth distribution of the unevenness exceeds the upper limit, when a semiconductor layer is laminated on the substrate to produce a light-emitting element, the thickness of the semiconductor layer necessary for planarization of the surface of the semiconductor layer becomes large. The time required for the manufacture of the light-emitting element becomes longer. The average value of the depth distribution of the concavities and convexities is more preferably in the range of 100 nm to 2 μm. The standard deviation of the depth of the concavities and convexities is preferably in the range of 10 nm to 5 μm. If the standard deviation of the depth of the concavities and convexities does not reach the above lower limit, the depth is too small with respect to the wavelength of visible light, so that the desired diffraction tendency is not generated. On the other hand, if the standard deviation of the depth of the concavities exceeds the upper limit, The intensity of the diffracted light tends to be uneven. The standard deviation of the depth of the concavities and convexities is preferably in the range of 25 nm to 2.5 μm.

When the layer is subjected to epitaxial growth on the epitaxial growth substrate 100 having the concave-convex pattern having the ridge-like curvature and the convex portion extending in the irregular direction as described above, the following advantages are obtained. First, since the inclined surface of the uneven shape is relatively gentle, the epitaxial growth layer can be uniformly laminated on the uneven pattern 80 to form an epitaxial layer having less defects. Further, the concave and convex pattern Since the direction of the unevenness is an irregular shape having no directivity, even if it is assumed that a defect caused by the pattern is generated, an epitaxial growth layer having no anisotropy and homogeneity can be formed.

Further, when the semiconductor layer is epitaxially grown on the epitaxial growth substrate 100 having such a concavo-convex pattern to produce a light-emitting element, the following advantages are obtained. First, since the light extraction efficiency of the epitaxial growth substrate having such a concavo-convex pattern is high, the light-emitting element produced by using the substrate has high luminous efficiency. Secondly, since the light diffracted by the epitaxial growth substrate having such a concavo-convex pattern has no directivity, the light extracted from the light-emitting element produced by using the substrate has no directivity and faces all directions. Third, the manufacturing time of the light-emitting element can be shortened for the following reasons. In the case of manufacturing a light-emitting element using a substrate having a concavo-convex pattern, it is necessary to laminate the semiconductor layer as described below until the uneven shape is covered with the semiconductor layer and the surface is flattened. The epitaxial growth substrate having the concave-convex pattern having the ridge-like curvature and extending in the irregular direction has sufficient light extraction efficiency because of the unevenness of the depth of 10 nm, and thus is described in Patent Document 1. The layer thickness of the laminated semiconductor layer can be made smaller than that of the substrate having the concavo-convex pattern of the submicron to micron order. Therefore, the growth time of the semiconductor layer can be shortened, and the manufacturing time of the light-emitting element can be shortened.

In the present application, the average pitch of the concavities and convexities refers to a case where the distance between the concavities and convexities in the surface on which the concavities and convexities are formed is measured (the distance between the adjacent convex portions or the adjacent concave portions), and the distance between the concavities and convexities The average value. The average value of the distance between the concavities and convexities is a scanning probe microscope (for example, product name "E-sweep" manufactured by Hitachi High-Tech Science Co., Ltd.), and the following conditions are used: measurement method: intermittent contact method of the cantilever

Cantilever material: 矽

Cantilever rod width: 40μm

Diameter of the tip end of the cantilever: 10nm

After analyzing the unevenness on the surface and measuring the unevenness analysis image, the interval between any adjacent convex portions or adjacent concave portions in the unevenness analysis image is measured at 100 or more points, thereby obtaining It is calculated by arithmetic mean.

Further, in the present application, the average value of the depth distribution of the unevenness and the standard deviation of the unevenness depth can be calculated as follows. The concave-convex analysis image was measured using a scanning probe microscope (for example, product name "E-sweep" manufactured by Hitachi High-Tech Science Co., Ltd.) for the shape of the surface unevenness. In the analysis of the concavities and convexities, an arbitrary area of 3 μm square (3 μm in length, 3 μm in width) or 10 μm square (10 μm in length and 10 μm in width) was measured under the above-described conditions to obtain a concavity and convexity analysis image. At this time, data of the height of the concavities and convexities in the measurement points of 16384 points (128 points in length × 128 points in width) in the measurement area were obtained at a nanometer scale. In addition, the number of such measurement points differs depending on the type or setting of the measuring device to be used, for example, when the product name "E-sweep" manufactured by Hitachi High-Tech Science Co., Ltd. described above is used as the measuring device. At the time of measurement, 65,536 points (256 points in length × 256 points in width) can be measured in the measurement area of 10 μm square (measured by resolution of 256 × 256 pixels). Here, in the unevenness analysis image, in order to improve the measurement accuracy, a flat process including one tilt correction may be performed. In addition, in the various analysis of the uneven shape described below, in order to ensure sufficient measurement accuracy, the measurement region may be set to have a length of 15 or more times the average value of the width of the convex portion included in the measurement region. A square-shaped area of the side length. Then, regarding the height of the concavities and convexities (unit: nm) measured as described above, first, the measurement point P having the highest height from the bottom surface of the substrate (the surface on the side opposite to the surface on which the concavo-convex pattern is formed) is obtained among all the measurement points. . Then, using the surface including the measurement point P and parallel to the bottom surface of the substrate as a reference surface (horizontal plane), the value of the depth from the reference surface is obtained (the height value from the measurement point P is subtracted from the height of the bottom surface of the substrate) The difference between the height of the point of the substrate and the height of the bottom surface of the substrate is measured as the data of the depth of the concave and convex. Further, such uneven depth data can be obtained by automatically calculating the software in the measuring device by a measuring device (for example, product name "E-sweep" manufactured by Hitachi High-Tech Science Co., Ltd.), and The value obtained by the automatic calculation is used as the data of the depth of the concave and convex.

After obtaining the data of the unevenness depth of each measurement point in the above manner, the values calculated by calculating the arithmetic mean and the standard deviation are used as the average value of the depth distribution of the unevenness and the standard deviation of the unevenness depth. In the present specification, the average pitch of the unevenness and the average value of the depth distribution of the unevenness are determined irrespective of the material on which the uneven surface is formed, and can be obtained by the above-described measuring method.

In addition, the "irregular concave-convex pattern" in the present application includes an approximate periodic structure, that is, a Fourier transform image obtained by performing two-dimensional fast Fourier transform processing on the concave-convex analysis image obtained by analyzing the uneven shape of the surface, and appears A circular or circular pattern, that is, although the direction of the above-mentioned unevenness has no directivity, but has a distribution of the distance between the concave and convex. The light scattered and/or diffracted from such a concavo-convex pattern is not a single or narrow band of wavelength light, but has a relatively wide wavelength band, and the scattered light and/or the diffracted light has no directivity, facing all direction. Therefore, such a substrate having an approximately periodic structure can be preferably used for a substrate used for a light-emitting element such as an LED as long as the distribution of the uneven pitch thereof scatters visible light.

Further, in the Fourier transform image obtained by performing the two-dimensional fast Fourier transform processing on the concavity and convexity analysis image, the pattern is observed by the bright point set. Therefore, the "Fourier transform image appears as a circular pattern" means that the pattern of the bright points in the Fourier transform image appears as the approximate center with the absolute value of the wave number of 0 μm ^-1 a circular or circular pattern, and the circular or annular pattern is present in an absolute value of the wave number of 10 μm ^-1 or less (may also be in the range of 0.1 to 10 μm ^-1 , and further may be set In the region of 0.667 to 10 μm ^-1 , preferably in the range of 0.833 to 5 μm ^-1 , it is also included that one of the apparent shapes is convex or concave. In addition, the "Fourier transform image appears as an annular pattern" means that the pattern formed by the bright points in the Fourier transform image appears to be substantially annular, and also includes a circle on the outer side or a circle on the inner side. The shape of the circle appears to be substantially round, and also includes a portion of the outer shape of the circle or the inner circle that looks like the outer side of the ring, which is convex or concave. In addition, so-called "circular or annular pattern present in the absolute value of the wave becomes 10μm ^-1 or less (the range may be 0.1 to 10μm ^-1, the addition can be within the range of 0.667 ~ 10μm ^-1 In the region within the range of 0.833 to 5 μm ^-1 , it is preferable that 30% or more of the bright points constituting the Fourier transform image exist in the absolute value of the wave number. It is in the range of 10 μm ^-1 or less (may be in the range of 0.1 to 10 μm ^-1 , and may be in the range of 0.667 to 10 μm ^-1 , preferably in the range of 0.833 to 5 μm ^-1 ). Within the area. When the epitaxial growth substrate of the embodiment is used as the substrate of the light-emitting element, the wavelength dependence and directivity of the light emission from the light-emitting element can be obtained in a certain direction. The nature of the luminescence) becomes small enough.

Further, regarding the relationship between the concavo-convex pattern and the Fourier transform image, the following may be known. When the pitch pattern itself has no distribution or no directivity, the Fourier transform image also appears in an irregular pattern (no pattern), but when the concave and convex pattern is uniformly equidistant in the XY direction but spaced apart, the circle appears or A circular Fourier transform image. Moreover, when the concave-convex pattern has a single distance, the ring formed by the Fourier transform image becomes a sharp outline. to. The average of the planar shape of the concave-convex pattern of the epitaxial growth substrate and the average pitch and depth distribution of the unevenness, and the advantages of the measurement method and the concave-convex pattern obtained in the embodiment, and the unevenness analysis chart The description and the like are also suitable for the concavo-convex pattern obtained in the other embodiments.

The two-dimensional fast Fourier transform processing of the concavity and convexity analysis image can be easily performed by electronic image processing using a computer having a two-dimensional fast Fourier transform processing software.

Further, the convex portion is displayed in white, and the concave and convex analysis image is processed so that the concave portion is displayed in black, whereby a plan view image (black and white image) as shown in FIG. 13 can be obtained. FIG. 13 is a view showing an example of a plan analysis image of a measurement region in the epitaxial growth substrate 100 of the present embodiment.

The width of the convex portion (white display portion) in a plan view image is referred to as "the width of the convex portion". The average value of the widths of the convex portions is selected from any one of the convex portions of the plan view image, and is set to be substantially perpendicular to the direction in which the convex portions extend in a plan view. The boundary of the convex portion is measured up to the length of the boundary on the opposite side, and can be calculated by calculating the arithmetic mean.

Further, when calculating the average value of the width of the convex portion, the value of the position at which the convex portion of the image is randomly selected from the plan view is used as described above, but the value of the position of the convex portion may not be used. In the convex portion, whether or not a certain region is a branched region can be determined, for example, by whether or not the region extends a certain amount or more. More specifically, the determination can be made by whether or not the ratio of the extension length of the region to the width of the region is constant (for example, 1.5) or more.

Referring to Fig. 14, it is determined whether or not the region is branched in an area protruding in a direction substantially perpendicular to the extending axis of the convex portion in the middle position of the convex portion extending in a certain direction. An example of the law is explained. Here, in the case where the determination target region of the convex portion is excluded from the convex portion, the extension axis of the convex portion is along the virtual axis extending in the direction in which the convex portion extends depending on the shape of the outer edge of the convex portion. More specifically, the extending axis of the convex portion is a line drawn by a substantially central point of the width of the convex portion orthogonal to the extending direction of the convex portion. FIGS. 14( a ) and 14 ( b ) are each a schematic view in which only one of the convex portions in the plan analysis image is selected, and the region S shows the convex portion. In FIGS. 14(a) and 14(b), the areas A1 and A2 that protrude in the middle of the convex portion are set as the determination target areas selected for branching. In this case, when the regions A1 and A2 are excluded from the convex portion, the extension axes L1 and L2 are defined as a line passing through a substantially central point of the width of the convex portion orthogonal to the extending direction of the convex portion. Such an extension axis can be defined by image processing using a computer, can be defined by an operator who performs the analysis operation, or can be defined by using image processing of a computer and manual operation of an operator. . In Fig. 14(a), the region A1 protrudes in a direction orthogonal to the extension axis L1 at a position intermediate the convex portion extending along the extension axis L1. In FIG. 14(b), the region A2 protrudes in a direction orthogonal to the extension axis L2 at a position intermediate the convex portion extending along the extension axis L2. Further, regarding the region which is inclined and protruded with respect to the direction orthogonal to the extension axes L1 and L2, it is only necessary to use the same viewpoint as the following description about the regions A1 and A2 to determine whether or not to branch.

According to the above determination method, the ratio of the extension length d2 of the region A1 to the width d1 of the region A1 is about 0.5 (less than 1.5), so that the determination region A1 is not a branch region. In this case, the length d3 passing through the region A1 and orthogonal to the extension axis L1 is one of the measured values for calculating the average value of the widths of the convex portions. On the other hand, the ratio of the extension length d5 of the region A2 to the width d4 of the region A2 is about 2 (1.5 or more), so the determination region A2 is The area of the branch. In this case, the length d6 in the direction orthogonal to the extension axis L2 passing through the region A2 is not set to one of the measured values for calculating the average value of the width of the convex portion.

In the epitaxial growth substrate 100 of the present embodiment, the width of the convex portion in the direction substantially perpendicular to the direction in which the convex portion extends in plan view of the concave-convex pattern 80 can be constant. Whether or not the width of the convex portion is constant can be determined based on the width of the convex portion of 100 points or more obtained by the above measurement. Specifically, the average value of the width of the convex portion and the standard deviation of the width of the convex portion are calculated from the width of the convex portion of 100 points or more. Then, the value calculated by dividing the standard deviation of the width of the convex portion by the average value of the width of the convex portion (the standard deviation of the width of the convex portion / the average value of the width of the convex portion) is defined as the width of the convex portion. Coefficient of variation. Regarding the coefficient of variation, the more the width of the convex portion is constant (the variation in the width is small), the smaller the coefficient of variation is. Therefore, whether or not the width of the convex portion is constant can be determined by whether or not the coefficient of variation is equal to or less than a specific value. For example, when the coefficient of variation is 0.25 or less, it can be defined that the width of the convex portion is constant.

Further, as shown in FIG. 13, in the epitaxial growth substrate 100 of the present embodiment, the extending direction of the convex portion (white portion) included in the concave-convex pattern is irregularly distributed in plan view. That is, the convex portion is not a regularly arranged stripe shape or a regularly arranged dot shape or the like, but has a shape that extends in an irregular direction. Further, in the measurement region, that is, in the specific region of the concave-convex pattern, the convex portion included in the region per unit area has a linear section having a larger number of curved sections in a plan view.

In the present embodiment, the "straight line section including a plurality of curved sections" means that the concave and convex pattern is not formed as follows: in all the sections on the outline of the convex portion, the curved section accounts for the majority. Whether or not the outline of the convex portion in the plan view has a linear section having a larger curved section, for example, by using the definition method of the two curved sections shown below The judgment is made in one case.

<The first definition method of the curve section>

In the first definition method of the curve section, the curve section is defined as a section in which the contour of the convex portion in a plan view is divided by the length of the average value of the width of the convex portion by π (pi), thereby forming a plurality of contours. In the case of the interval, the ratio of the linear distance between the ends of the interval to the length of the contour between the ends is 0.75 or less. Further, the straight line interval is defined as a section other than the curve section in the plurality of sections, that is, the section in which the ratio is larger than 0.75. In the following, an example of a procedure for determining whether or not the contour of the convex portion in the plan view includes a linear section having a larger curved section using the first definition method will be described with reference to FIG. 15( a ). Fig. 15 (a) is a view showing a part of a plan view image of a concave-convex pattern, and the concave portion is whitened for convenience. The region S1 indicates a convex portion, and the region S2 indicates a concave portion.

Program 1-1

A convex portion is selected from a plurality of convex portions in the measurement region. It is determined that any position on the outline X of the convex portion is a starting point. In FIG. 15(a), as an example, the point A is set as the starting point. On the outline X of the convex portion, the reference point is set at a specific interval from the starting point. Here, the specific interval is a length of π (pi) of the average value of the width of the convex portion/2 times. In FIG. 15(a), as an example, point B, point C, and point D are sequentially set.

Procedure 1-2

When the points A to D which are the reference points are set on the outline X of the convex portion, the section to be determined is set. Here, the start point and the end point are reference points, and the section including the reference point which becomes the intermediate point is set as the determination target. In the example of Fig. 15(a), when the point A is selected as the starting point of the section, the second set point C from the point A is the end point of the section. About the distance between points A The interval is set to a length of π/2 times the average value of the width of the convex portion. Therefore, the point C is a length π times the average value of the width of the convex portion along the contour line X from the point A. Similarly, when the point B is selected as the starting point of the section, the second set point D from the point B is the end point of the section. Here, the target section is set in the order set, and the point A is set as the point set first. In other words, first, the section (section AC) of the point A and the point C is set as the section to be processed. Then, the length La of the outline X of the convex portion of the joint A and the point C shown in Fig. 15 (a) and the linear distance Lb between the point A and the point C are measured.

Procedure 1-3

The ratio (Lb/La) of the linear distance Lb to the length La is calculated using the length La and the linear distance Lb measured in the procedure 1-2. When the ratio is 0.75 or less, it is determined that the point B at which the contour line X of the convex portion becomes a point in the section AC is a point existing in the curve section. On the other hand, when the above ratio is larger than 0.75, the determination point B is a point existing in the straight line section. Further, in the example shown in Fig. 15 (a), since the ratio (Lb/La) is 0.75 or less, the determination point B is a point existing in the curve section.

Procedure 1-4

When each point set in the program 1-1 is selected as a starting point, the program 1-2 and the program 1-3 are performed.

Procedure 1-5

Procedure 1-1 to 1-4 are performed for all the convex portions in the measurement area.

Program 1-6

When it is determined that the ratio of the point existing at the point of the straight line section is 50% or more of all the points set for all the convex portions in the measurement region, the convex portion is determined to be under the plan view. The profile contains a linear interval that is more than the curve interval. On the other hand, when it is determined that the ratio of the point existing at the point of the straight line section is less than 50% of the whole point among all the points set for all the convex portions in the measurement region, the contour of the convex portion in a plan view is determined. The line contains more curved intervals than the straight line interval.

The processing of the above-described procedures 1-1 to 1-6 may be performed by the measurement function of the measurement device, or may be performed by a software for analysis different from the above-described measurement device, or may be performed manually.

In addition, in the above-described procedure 1-1, the process of setting a point on the contour line of the convex portion ends as long as "the point where the ring convex portion is one week or the measurement region cannot be set and the point is more than the above point cannot be set" Just handle it. Further, since the ratio (Lb/La) cannot be calculated in the section other than the point set first and the point which is set last, it is sufficient to be the object of the above determination. Further, the convex portion in which the length of the contour line is less than π times the average value of the width of the convex portion may be the object of the above-described determination.

<The second definition method of the curve section>

In the second definition method of the curve section, the curve section is defined as a section in which the contour of the convex portion in a plan view is divided by a length π (pi) of the average value of the width of the convex portion, thereby forming a complex number In the case of a section, the line segment (point A) of the link interval (point A) and the middle point (point B) of the interval (the line segment AB), and the other end of the interval (point C) and the point of the interval (point) The angle of the smaller of the two angles formed by the line segment (line segment CB) of B) (which is 180 or less) is 120 or less. Further, the straight line section is defined as a section other than the curve section in the plurality of sections, that is, the section in which the angle is greater than 120 degrees. Hereinafter, referring to FIG. 5(b), it is determined whether or not the outline of the convex portion in the plan view has a relatively large curved section by using the second definition method. An example of the program of the line interval will be described. Fig. 15 (b) is a view showing a part of a plan analysis image of the concave-convex pattern similar to Fig. 15 (a).

Program 2-1

A convex portion is selected from a plurality of convex portions in the measurement region. It is determined that any position on the outline X of the convex portion is a starting point. In FIG. 15(b), as an example, the point A is set as the starting point. On the outline X of the convex portion, the reference point is set at a specific interval from the starting point. Here, the specific interval is a length of π (pi) of the average value of the width of the convex portion/2 times. In FIG. 15(b), as an example, point B, point C, and point D are sequentially set.

Procedure 2-2

When the points A to D which are the reference points are set on the outline X of the convex portion, the section to be determined is set. Here, the start point and the end point are reference points, and the section including the reference point which becomes the intermediate point is set as the determination target. In the example of FIG. 15(b), when the point A is selected as the starting point of the section, the second set point C from the point A is the end point of the section. Regarding the interval from the point A, the length is set to be π/2 times the average value of the width of the convex portion, and therefore the point C is π times the average value of the width of the convex portion along the contour line X from the point A. Length. Similarly, when the point B is selected as the starting point of the section, the second set point D from the point B is the end point of the section. Here, the target section is set in the order set, and the point A is set as the point set first. In other words, first, the section (section AC) of the point A and the point C is set as the section to be processed. Then, the angle θ of the smaller of the two angles formed by the line segment AB and the line segment CB (which is 180 or less) is measured.

Procedure 2-3

When the angle θ is 120° or less, the determination point B is a point existing in the curve section. On the other hand, when the angle θ is larger than 120°, the determination point B is a point existing in the straight line section. Further, in the example shown in FIG. 15(b), since the angle θ is 120° or less, the determination point B is a point existing in the curve section.

Program 2-4

Regarding the case where each point set in the program 2-1 is selected as a starting point, the program 2-2 and the program 2-3 are performed.

Procedure 2-5

Procedure 2-1 to 2-4 are performed for all the convex portions in the measurement area.

Procedure 2-6

When it is determined that the ratio of the point existing at the point of the straight line section is 70% or more of all the points set for all the convex portions in the measurement region, it is determined that the contour of the convex portion in the plan view has a relatively curved curve. A straight interval with multiple intervals. On the other hand, when it is determined that the ratio of the point existing at the point of the straight line section is less than 70% of the total of all the points set in all the convex portions in the measurement region, the contour of the convex portion in plan view is determined. The line contains more curved intervals than the straight line interval.

The processing of the above-described procedures 2-1 to 2-6 may be performed by the measurement function of the measuring device, or may be performed by a software for analysis different from the above-described measuring device, or may be performed manually.

In addition, in the above-described program 2-1, the process of setting a point on the contour line of the convex portion ends as long as "the point where the ring convex portion is one week or the measurement region cannot be set and the point is more than the above point cannot be set" Just handle it. Further, since the angle θ cannot be calculated in the section outside the point set by the first point and the point which is set last, the object of the above determination is required. Just outside. Further, the convex portion in which the length of the contour line is less than π times the average value of the width of the convex portion may be the object of the above-described determination.

As described above, by using any of the first and second definition methods of the curve section, it is possible to determine, for the measurement region, whether or not the contour line X of the convex portion in the plan view includes a linear section having a larger number of curved sections. Further, in the concave-convex pattern 80 of the epitaxial growth substrate 100, the determination as to whether or not the convex portion included in the region per unit area has a linear section having a larger curved section in a plan view can be determined by It is determined based on one measurement region randomly selected and measured from the region of the concave-convex pattern 80 of the epitaxial growth substrate 100, and may be plural in the concave-convex pattern 80 for the same epitaxial growth substrate 100. The determination result of the measurement area is performed by comprehensive determination. In this case, for example, it is also possible to use a determination result of a larger number of determination results for a plurality of different measurement areas as "whether the contour line included in the area per unit area has a more curved section in a plan view. The result of the determination of the straight line interval.

[Second Embodiment]

A method of manufacturing the epitaxial growth substrate of the second embodiment will be described with reference to FIGS. 6(a) to 6(e). In the same manner as in the first embodiment, the method for producing an epitaxial growth substrate according to the second embodiment mainly includes a solution preparation step of preparing a sol-gel material, and a coating step of condensing the prepared sol. Applying a glue material to the mold; a sealing step of adhering the coated sol-gel material to the substrate; a peeling step of peeling the mold from the coating film; and a hardening step of coating the film hardening. In the above embodiment, the convex portion 60 formed on the base material 40 is formed in a portion opposed to the concave portion 140a of the mold 140. However, in the present modification, the convex portion 60 is formed on the base 40 and the mold. The convex portion 140b of 140 is opposite to the portion.

<Sol-gel material solution preparation step>

The preparation of the sol-gel material solution was carried out in the same manner as the method described in the above embodiment.

<Coating step>

In the present embodiment, as shown in Fig. 6(a), a solution of the prepared sol-gel material (inorganic material) is applied to the convex portion 140b of the mold 140 to form a coating film 68. The sol-gel material is more rationally applied only to the surface of the convex portion 140b of the mold 140 (opposite to the substrate 40), but depending on the coating method, the sol-gel material may be folded into the side of the convex portion 140b. That is, the recess 140a. In this case, if the convex portion 60 composed of the sol-gel material reflecting the pattern of the convex portion 140b of the mold is formed on the substrate 40 after the peeling step, the sol-gel material may also adhere to the concave portion 140a of the mold. . As the coating method, the sol-gel material can be uniformly used by any coating method such as a bar coating method, a spin coating method, a spray coating method, a dip coating method, a die coating method, or an inkjet method. The bar coating method, the die coating method, and the spin coating are preferably applied to a relatively large-area mold and can be quickly finished before the sol-gel material is cured (gelled). law. Alternatively, the mold may be formed into a roll shape, and the roll-shaped mold may be immersed in a sol-gel material which is shallowly filled in the container and rotated, whereby the sol-gel material may be applied to the convex portion of the mold. The roll-shaped mold can be produced, for example, by winding a flexible mold on a hard roll such as metal. The film thickness of the coating film 68 of the sol-gel material applied to the convex portion 140b of the mold is preferably from 1 to 3,000 nm. The film thickness of the coating film of the sol-gel material can be prepared, for example, according to the viscosity of the sol-gel material or the like.

The mold used in the embodiment is preferably a mold that is elastically deformable like the rubber mold described above. Moreover, it is preferred to apply the sol-gel material to the substrate after the stripping step. Since the coating film is transferred only to the portion corresponding to the convex portion of the mold to form the convex portion, the average value of the depth distribution of the unevenness of the mold is preferably about 1 to 10 times the pitch with respect to the formed concave-convex pattern. When the unevenness of the mold is less than the above lower limit, the coating film of the sol-gel material may be transferred to the outside of the desired portion of the substrate. On the other hand, if the unevenness depth of the mold is larger than the upper limit, there is a possibility that the shape of the mold is deformed in the adhesion step, and the pattern of the convex portion transferred onto the substrate is deformed, and the desired shape cannot be obtained. pattern.

<Close step>

As shown in FIG. 6(b), the mold 140 on which the coating film 68 of the sol-gel material is formed is pressed against the substrate 40, whereby the coating film 68 is adhered to the substrate 40. Thereby, the coating film 68 is adhered to the portion of the substrate 40 that faces the convex portion 140b of the mold 140. Further, the substrate 40 may be subjected to a hydrophilic treatment of the surface by treatment with O ₃ or the like. By subjecting the surface of the substrate 40 to a hydrophilic treatment, the adhesion between the substrate 40 and the sol-gel material can be further increased.

In the adhesion step, when the coating film of the sol-gel material is brought into contact with the substrate, the coating film may be heated. By heating, the chemical reaction of the sol-gel material and the evaporation of the water and the solvent generated thereby are promoted, whereby the coating film is cured (gelled). Therefore, it is possible to prevent the unhardened coating film from being wetted and diffused to the size of the convex portion of the mold to be transferred to the substrate. Further, it is possible to prevent the unhardened coating film from remaining in the convex portion of the mold after the peeling step. When the coating film remains in the convex portion of the mold, there is a case where the film thickness of the coating film formed on the mold is changed or the residual coating film is hardened when the mold is repeatedly used to produce the substrate for epitaxial growth. And the reason for becoming a particle. As a method of heating the coating film, for example, heating may be performed by a mold, or the coating film may be directly heated or the coating film may be heated from the substrate side. In the heating, any heating means can be used. For example, when heating from the substrate side, a heating plate can be provided on the back side of the substrate to add heat. Although the heating temperature of the coating film depends on the speed at which the substrate is processed, the higher the temperature, the more preferable, and it is preferable to be close to the heat-resistant temperature of the mold. For example, when the mold is formed of polydimethyl siloxane (PDMS), the heating temperature of the coating film of the sol-gel material is preferably 150 to 200 °C. When a material which generates an acid or an alkali by irradiation with light such as ultraviolet rays is added to the sol-gel material solution, instead of heating the coating film, for example, by irradiating an energy ray represented by ultraviolet rays such as excimer UV light, Gelation proceeds.

<Peeling step>

The mold was peeled off from the coating film and the substrate. After the mold is peeled off, as shown in FIG. 6(c), the coating film of the sol-gel material is adhered to the portion of the base material 40 corresponding to the convex portion 140b of the mold 140 to form the convex portion 60. The surface of the substrate 40 is exposed in a region other than the region (the region where the convex portion 60 is formed) corresponding to the convex portion 140b of the mold 140. In this way, a region (concave portion 70) where the surface of the substrate is exposed is defined between the convex portions 60 composed of the sol-gel material. As the peeling method of the mold, a known peeling method can be employed. When the above-described roll-shaped mold is used, the coating film 68 of the sol-gel material can be transferred to the substrate 40 by rolling only the roll-shaped mold coated with the sol-gel material onto the substrate 40. The convex portion 60 is formed up, and the mold can be peeled off from the substrate 40.

<hardening step>

After the mold is peeled off, the convex portion 60 composed of the sol-gel material is cured. The curing can be carried out by the same method as the method described in the curing step of the above embodiment. Thus, the coating film is hardened, and the projection growth substrate 100 in which the convex portion 60 and the concave portion 70 formed on the substrate 40 are formed as shown in FIG. 6(d) can be formed.

Further, in the same manner as in the first embodiment, as shown in FIG. 6(e), the substrate surface exposed by the epitaxial growth substrate 100 manufactured by the present modification may be etched. On the substrate 40, a recess 70a is formed. Thereby, the epitaxial growth substrate 100a is formed, and the epitaxial growth substrate 100a is formed with the concave-convex pattern 80a composed of the convex portion 60 and the concave portion 70a.

In the present embodiment, the coating film of the sol-gel material is formed only in the convex portion of the mold, and since the coating film is not formed in the concave portion of the mold, the mold is not clogged, and the frequency of cleaning or exchange of the mold can be reduced. Therefore, this embodiment can be continuously produced at a high speed for a long period of time, and the manufacturing cost can be suppressed.

[Third embodiment]

A method of producing the epitaxial growth substrate of the third embodiment will be described. The manufacturing method of the epitaxial growth substrate mainly includes a solution preparation step S1 for preparing a sol-gel material, and a coating step S2 for applying the prepared sol-gel material to the substrate. a drying step S3 of drying the coating film of the sol-gel material applied to the substrate; pressing the step S4 to press the mold having the transfer pattern pressed against the coating film dried at a specific time The pre-baking step S5 is to pre-fire the coating film pressed by the mold; the stripping step S6 is to peel the mold from the coating film; and the etching step S7 is to remove the concave portion of the coating film; The hardening step S8 is to harden the coating film. Further, the pressing step S4, the pre-baking step S5, and the peeling step S6 are collectively referred to as a transfer step. Hereinafter, the mold for transferring the uneven pattern and the method for producing the same will be described first, and the above respective steps will be described with reference to FIGS. 8(a) to 8(e).

<Coating step>

As shown in Fig. 8 (a), a solution of a sol-gel material (inorganic material) prepared in the above manner is applied onto a substrate 40 to form a coating film 64 of a sol-gel material. As the substrate 40, various light-transmitting substrates similar to those of the user in the first embodiment can be used.

As a coating method of the sol-gel material, a bar coating method or a spin coating method can be used. A coating method such as a cloth method, a spray coating method, a dip coating method, a die coating method, or an inkjet method can uniformly apply a sol-gel material to a relatively large-area substrate, and can be sol-geled. The bar coating method, the die coating method, and the spin coating method are preferred in terms of quickly ending the coating before the gel material is gelated. The film thickness of the coating film 64 is preferably 500 nm or more. Further, in order to improve the adhesion on the substrate 40, a surface treatment layer or an easy-adhesion layer may be provided.

<drying step>

After the application of the sol-gel material, the substrate is held in the air or under reduced pressure in order to evaporate the solvent in the coating film 64. If the holding time is short, the viscosity of the coating film 64 becomes too low, and the uneven pattern is not transferred to the coating film 64. If the holding time is too long, the polymerization reaction of the precursor proceeds, and the viscosity of the coating film 64 proceeds. It becomes too high, and it becomes impossible to transfer the uneven pattern to the coating film 64. Further, after the sol-gel material is applied, the polymerization of the precursor proceeds as the evaporation of the solvent progresses, and the physical properties such as the viscosity of the sol-gel material also change in a short time. From the viewpoint of forming the stability of the concavo-convex pattern, it is preferable that the pattern transfer can be performed well in a wide range of drying time depending on the drying temperature (holding temperature), the drying pressure, the type of the sol-gel material, and the sol-gel material. The mixing ratio of the types, the amount of the solvent used in the preparation of the sol-gel material (the concentration of the sol-gel material), and the like are adjusted. Further, in the drying step, as long as the substrate is directly held, the solvent in the sol-gel material solution evaporates, so that it is not necessary to perform an active drying operation such as heating or blowing, as long as the substrate on which the coating film is formed is directly Place it for a specific time, or for a specific time to carry out the subsequent steps. That is, in the method for producing an epitaxial growth substrate of the embodiment, the drying step is not necessarily required.

<Pressure step>

Then, as shown in FIG. 8(b), the mold 141 is overlaid on the coating film 64 and pressed, and The concave-convex pattern of the mold 141 is transferred to the coating film 64 of the sol-gel material. As the mold 141, the above-described concave-convex pattern transfer mold can be used, and a film mold having flexibility or flexibility is preferably used. At this time, the mold 141 may be pressed against the coating film 64 of the sol-gel material by using a pressing roller. In the roll process using the press roll, compared with the press type, there is an advantage that the contact time between the mold and the coating film is short, so that thermal expansion of the mold or the substrate and the platform on which the substrate is disposed can be prevented. Pattern distortion caused by the difference of the coefficients; it can prevent bubbles from being generated in the pattern due to the boiling of the solvent in the sol-gel material solution, or the gas marks remain; due to the line contact with the substrate (coating film), The transfer pressure and the peeling force are small, and it is easy to cope with a large area; there is no case of entraining bubbles when pressed. Further, the substrate may be heated while pressing against the mold. As an example of using a pressure roller to press a mold against a coating film of a sol-gel material, as shown in FIG. 9, a film is fed between the pressing roller 122 and the substrate 40 directly conveyed thereto. The mold 141 can thereby transfer the uneven pattern of the film mold 141 to the coating film 64 on the substrate 40. In other words, when the film mold 141 is pressed against the coating film 64 by the pressing roller 122, the film mold 141 and the substrate 40 are simultaneously conveyed, and the coating film 64 on the substrate 40 is coated with the film mold 141. surface. At this time, the pressing roller 122 is pressed against the back surface of the film mold 141 (the surface opposite to the surface on which the uneven pattern is formed) and rolled, whereby the film mold 141 advances and adheres to the substrate 40. Further, in the case where the long film-shaped mold 141 is fed toward the pressing roller 122, it is convenient in that the film roll 141 is directly fed out from the film roll from which the long film-shaped mold 141 is wound. And use.

<Pre-burning step>

The coating film may be pre-fired after the mold 141 is pressed against the coating film 64 of the sol-gel material. By performing the calcination, the coating film 64 is gelated and the pattern is solidified, and the pattern becomes difficult to be deformed when the mold 141 is peeled off. In the case of pre-firing, it is preferred to use a chamber in the atmosphere. Heating at a temperature of ~300 °C. Furthermore, pre-firing does not necessarily have to be carried out. Further, when a material which generates an acid or an alkali by irradiation with light such as ultraviolet rays is added to the sol-gel material solution, instead of pre-baking the coating film 64, for example, ultraviolet rays such as excimer UV light may be irradiated. Energy line.

<Peeling step>

After the mold 141 is pressed or the coating film 64 of the sol-gel material is pre-fired, as shown in FIG. 8(c), the mold 141 is peeled off from the coating film (concave-convex structure) 62 in which the irregularities are formed. As the peeling method of the mold 141, a known peeling method can be employed. The mold 141 can be peeled off while being heated, whereby the generated gas escapes from the uneven structure body 62, and generation of air bubbles in the uneven structure body 62 can be prevented. When the roll process is used, the peeling force can be made smaller than that of the plate-shaped mold used in a pressurized manner, so that the sol-gel material does not remain in the mold 141, and the mold 141 can be easily self-concave the concave-convex structure. 62 peeling. In particular, since the concave-convex structure 62 is pressed while being heated, the reaction is easily performed, and the mold 141 is easily peeled off from the uneven structure 62 immediately after the pressing. Further, in order to improve the peelability of the mold 141, a peeling roll may be used. As shown in Fig. 9, the peeling roller 123 is disposed on the downstream side of the pressing roller 122, and the film-shaped mold 141 is pressed against the coating film 64 by the peeling roller 123, and rolling support is performed, whereby the film shape can be obtained. The state in which the mold 141 adheres to the coating film 64 is maintained at a distance (fixed time) between only the pressing roller 122 and the peeling roller 123. Then, on the downstream side of the peeling roll 123, the film-shaped mold 141 is changed to the upper side of the peeling roll 123, and the film-shaped mold 141 is changed, and the film-shaped mold 141 is formed from the uneven film. Body) 62 peeled off. Further, during the period in which the film mold 141 is adhered to the coating film 64, the above-described coating film 64 may be pre-fired or heated. Further, when the peeling roller 123 is used, for example, the peeling of the mold 141 can be further performed by peeling while heating to room temperature to 300 ° C. easily.

<etching step>

After the peeling of the mold, as shown in FIG. 8(c), a film of the sol-gel material is present in the concave portion of the concave-convex structure 62 (the region where the thickness of the uneven structure is thin), and the concave portion of the concave-convex structure 62 is The sol-gel material is removed by etching, whereby the surface of the substrate 40 is exposed as shown in FIG. 8(d), whereby a large number of convex portions 61 are formed on the substrate 40. The etching can be performed by using RIE of a fluorine-based gas such as CHF ₃ or SF ₆ . Etching can also be performed by wet etching using BHF or the like. In the etching step, not only the concave portion of the concave-convex structure 62 but also the entire concave-convex structure including the convex portion is etched. Therefore, the concave portion of the concave-convex structure 62 is etched and the surface of the substrate is exposed, and the convex portion 61 of a specific size is formed on the base. At the time of the material 40, the etching is stopped. In this way, a region (concave portion 71) where the surface of the substrate is exposed is defined between the convex portions 61 composed of the sol-gel material. The embossed concavo-convex structure 62a is formed by a plurality of convex portions 61 composed of a free sol-gel material. Further, when etching is performed by dry etching such as RIE, the surface of the exposed substrate is broken (damage), and therefore, it can be post-treated by a chemical solution such as a phosphoric acid.

<hardening step>

After the etching step, the uneven structure 62a (the convex portion 61) composed of the sol-gel material is cured. The convex portion 61 can be hardened by main firing. By the main baking, the hydroxyl group contained in the cerium oxide (amorphous cerium oxide) constituting the convex portion 61 is detached, and the coating film becomes stronger. The main firing can be carried out at a temperature of 600 to 1200 ° C for about 5 minutes to 6 hours. When the convex portion 61 is cured, the concave-convex structure 62a (the convex portion 61) formed on the base material 40 and the epitaxial growth substrate 100 having the concave-convex pattern 81 formed in the concave portion 71 can be formed. In this case, when the convex portion 61 is composed of cerium oxide, it becomes amorphous or crystalline, or amorphous or crystalline depending on the firing temperature and the firing time. Mixed state. Further, when a material which generates an acid or an alkali by irradiation with light such as ultraviolet rays is added to the sol-gel material solution, instead of firing the convex portion 61, for example, an energy represented by ultraviolet rays such as excimer UV light may be irradiated. The wire, whereby the convex portion 61 can be hardened.

Furthermore, the hardening step and the etching step can also be performed in any step. When the etching step is performed after the hardening step, the concave-convex structure composed of the sol-gel material is hardened in the hardening step, and the concave portion of the cured concave-convex structure is etched away in the etching step to make the surface of the substrate Exposed.

Further, as shown in FIG. 8(e), the exposed substrate surface may be etched in the etching step to form the concave portion 71a in the substrate 40. Thereby, the epitaxial growth substrate 101a is formed, and the epitaxial growth substrate 101a is formed with the concavo-convex pattern 81a composed of the concavo-convex structure 62a (the convex portion 61) and the concave portion 71a. Since the epitaxial growth substrate 101a is formed with the concave portion 71a in the base material 40, the unevenness of the concave-convex pattern can be made larger than that of the substrate 101 in which the substrate 40 is not etched. In the case where a sapphire substrate is used as the substrate 40, the etching of the substrate 40 can be performed, for example, by using RIE using a gas containing BCl ₃ or the like.

The surface of the substrate on which the uneven patterns 81 and 81a are formed as described above (the surface on which the uneven pattern is formed) may be formed to form a buffer layer. Thereby, the epitaxial growth substrates 101b and 101c having the buffer layer 20 on the surface of the uneven patterns 81 and 81a as shown in FIGS. 10(a) and 10(b) can be obtained. When the cross-sectional shape of the concave-convex pattern is composed of a relatively gentle inclined surface and a corrugated structure is formed, a uniform buffer layer having less defects can be formed.

Further, a buffer layer may be formed on the substrate before the coating step. As a result, as shown in FIG. 10( c ), the uneven structure 62 a is formed on the buffer layer 20 , and a region (concave portion 71 b ) in which the surface of the buffer layer is exposed is defined between the convex portions 61 . Thereby, the Lei formed with the concave-convex pattern 81b can be obtained. The crystal growth substrate 101d.

The method or material for forming the buffer layer 20 is the same as that described in the first embodiment.

In the method for producing an epitaxial growth substrate in which the surface of the substrate is embossed and the surface of the substrate is embossed, as in the prior art described in Patent Documents 1 and 2, only the concave-convex pattern is formed. In the method for producing an epitaxial growth substrate of the present embodiment, the sol-gel material remaining in the concave portion of the uneven structure may be etched after the mold is peeled off. Therefore, the manufacturing method of the epitaxial growth substrate of the present embodiment can shorten the manufacturing time of the substrate.

Further, in the epitaxial growth substrates 101 and 101a to 101d shown in Figs. 8(d) and 8(e) and Figs. 10(a) to 10(c) formed by the manufacturing method of the present embodiment, the epitaxial growth substrates 101 and 101a to 101d are formed. The concavo-convex structure 62a (a plurality of convex portions 61) and the concave portions 71, 71a, and 71b on the base material 40 constitute concave-convex patterns 81, 81a, and 81b. Fig. 11(a) shows an example of an AFM image of an epitaxial growth substrate manufactured by the manufacturing method of the embodiment, and Fig. 11(b) shows a cutting line in the AFM image of Fig. 11(a). A cross-sectional image of the substrate for epitaxial growth.

The cross-sectional shape of the uneven pattern of the epitaxial growth substrate is not particularly limited, and can be formed as shown in FIGS. 8( d ), ( e ), 10 (a), (b), (c), and 11 (b). The waveform formed by the relatively gentle inclined surface and facing upward from the substrate 40 (referred to as "waveform structure" as appropriate in the present application). That is, the convex portion 61 may have a cross-sectional shape that is narrowed from the bottom to the top of the substrate side.

The planar shape of the concave-convex pattern of the epitaxial growth substrate is not particularly limited, and may be a regular alignment pattern such as a stripe, a wavy stripe, a zigzag regular alignment pattern, or a dot pattern, or as shown in FIG. 11 ( a) one of the AFM images of the concave-convex pattern of the substrate surface shown For example, the convex portion (white portion) and the concave portion are curved and extended, and the extending direction, the bending direction, and the extending length are irregular in plan view. That is, it may be characterized in that i) the convex portion and the concave portion have an elongated shape of each of the ridges, and i) the convex portion and the concave portion are not uniform in the direction in which the concave-convex pattern extends, the bending direction, and the length. When the concave-convex pattern of the epitaxial growth substrate has the above-described characteristics, even if the concave-convex pattern 81 is cut in any direction orthogonal to the surface of the substrate 40, the unevenness profile is repeated. Further, when the convex portion and the concave portion are in a plan view, some or all of them may be branched on the way (see FIG. 11( a )). Further, in Fig. 11 (a), the distance between the convex portion and the concave portion is uniform as a whole.

Further, in the first to third embodiments, as the solution of the inorganic material applied in the coating step, a sol-gel material such as TiO ₂ , ZnO, ZnS, ZrO, BaTiO ₃ or SrTiO ₂ may be used. Solution or microparticle dispersion. Among them, in terms of film formability or refractive index, TiO _{2 is} preferred. Among them, in terms of film formability or refractive index, TiO _{2 is} preferred. A coating film of an inorganic material can also be formed by a liquid phase deposition method (LPD) or the like.

Further, as the inorganic material applied in the coating step, a polyazane solution may also be used. In this case, the convex portion formed by applying and transferring the embossed portion may be ceramized (cerium oxide modified) in the curing step to form a convex portion composed of cerium oxide. Further, the "polyazide" is a polymer having a ruthenium-nitrogen bond, and is composed of Si-N, Si-H, NH, or the like, SiO ₂ , Si ₃ N _{4 ,} and the intermediate of the two. Solvent SiO _X N _Y and other ceramic precursor inorganic polymers. More preferably, it is a compound which is represented by the following general formula (1) described in the following general formula (1), and is ceramized at a relatively low temperature to be converted into cerium oxide, as described in JP-A-H08-112879.

General formula (1): -Si(R1)(R2)-N(R3)-

In the formula, R1, R2 and R3 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylalkylene group, an alkylamino group or an alkoxy group.

In the compound represented by the above formula (1), it is particularly preferred that all of the hydrogen polyazide (also known as PHPS) in which R1, R2 and R3 are hydrogen atoms or a part of hydrogen bonded to Si An organopolyazane substituted with an alkyl group or the like.

As another example of the polyazane which is ceramized at a low temperature, an alkoxide oxime addition polyazide obtained by reacting a polyazide with an alkoxide may also be used (for example, Japanese Patent Laid-Open No. 5- Japanese Patent No. 238827), a dehydroglycerin-added polyazide obtained by reacting polyazane with dehydrin (for example, JP-A-6-122852), and reacting polyazane with an alcohol Further, the obtained alcohol is added to a polyazane (for example, Japanese Laid-Open Patent Publication No. Hei 6-240208), and a metal carboxylate addition polyazide obtained by reacting polyazane with a metal carboxylate (for example, Japanese Patent Application Laid-Open No. Hei 6-299118, the acetamylpyruvate complex obtained by reacting polyazane with a metal-containing acetoacetate complex to form polyazane (for example, Japanese Patent) Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

As the solvent of the polyazirane solution, a hydrocarbon solvent such as an aliphatic hydrocarbon, an alicyclic hydrocarbon or an aromatic hydrocarbon, a halogenated hydrocarbon solvent, an ether such as an aliphatic ether or an alicyclic ether can be used. In order to promote the modification of the cerium oxide compound, an amine or metal catalyst may also be added.

[Light-emitting element]

A light-emitting device can be produced by using the epitaxial growth substrate obtained by the method for producing an epitaxial growth substrate according to the first to third embodiments. As shown in FIG. 12, the light-emitting element 200 of the embodiment includes a first conductive type layer 222 and an active layer 224 which are sequentially laminated on the epitaxial growth substrate 100. The semiconductor layer 220 formed by the second conductive type layer 226. Further, the light-emitting element 200 of the embodiment includes a first electrode 240 electrically connected to the first conductive type layer 222 and a second electrode 260 electrically connected to the second conductive type layer 226.

As the material of the semiconductor layer 220, a known material used for the light-emitting element can be used. As a material used for the light-emitting element, for example, a GaN-based semiconductor material represented by the general formula In _x Al _y Ga _1-xy N (0≦x≦1, 0≦y≦1, 0≦x+y≦1) is known. In the light-emitting device of the present embodiment, a GaN-based semiconductor including the well-known GaN-based semiconductor and represented by the general formula Al _X Ga _Y In _Z N _{1 A} M _A may be used without any limitation. The GaN-based semiconductor may contain other Group III elements in addition to Al, Ga, and In, and may contain elements such as Ge, Si, Mg, Ca, Zn, Be, P, As, and B as needed. Further, the present invention is not limited to the intentionally added elements, and may include impurities which are inevitably contained depending on the growth conditions of the semiconductor layer, and trace impurities contained in the raw material and the reaction tube material. Other semiconductor materials such as GaAs, GaP-based compound semiconductor, AlGaAs, and InAlGaP-based compound semiconductor may be used in addition to the above-described nitride semiconductor.

The n-type semiconductor layer 222 as the first conductivity type layer is laminated on the substrate 100. The n-type semiconductor layer 222 is formed of materials and structures known in the art, and may be formed, for example, of n-GaN. The active layer 224 is laminated on the n-type semiconductor layer 222. The active layer 224 is formed of a material and structure known in the art, and may have, for example, a multiple quantum well (MQW) structure in which a plurality of layers of GaInN and GaN are laminated. The active layer 224 emits light by injection of electrons and holes. The p-type semiconductor layer 226 as the second conductivity type layer is laminated on the active layer 224. The p-type semiconductor layer 226 may have a well-known configuration in the above technique, and may be formed, for example, of p-AlGaN and p-GaN. Product of a semiconductor layer (n-type semiconductor layer, active layer, and p-type semiconductor layer) The layer method is not particularly limited, and a known method of growing a GaN-based semiconductor such as MOCVD (Organic Metal Chemical Vapor Deposition), HVPE (Hydride Vapor Deposition), or MBE (Molecular Beam Epitaxy) can be applied. From the viewpoint of layer thickness controllability and mass productivity, the MOCVD method is preferred.

The uneven pattern 80 is formed on the surface of the epitaxial growth substrate 100. However, in the epitaxial growth of the n-type semiconductor layer, the growth of the semiconductor layer described in Japanese Laid-Open Patent Publication No. 2001-210598 causes the surface to be flat. Governing. Since the active layer must be formed on a flat surface, it is necessary to laminate an n-type semiconductor layer before the surface is flattened. In the epitaxial growth substrate of the embodiment, since the cross-sectional shape of the concave-convex pattern is formed by a relatively gentle inclined surface and a corrugated structure is formed, the planarization of the surface is rapidly performed, and the layer thickness of the n-type semiconductor layer can be reduced. The growth time of the semiconductor layer can be shortened.

The n-electrode 240 as the first electrode is formed on the n-type semiconductor layer 222 which is exposed by etching one of the p-type semiconductor layer 226 and the active layer 224. The n-electrode 222 is formed of a material and a structure which are known in the art, and is formed of, for example, Ti/Al/Ti/Au or the like, and is formed by a vacuum deposition method, a sputtering method, a CVD method, or the like. A p-electrode 260 as a second electrode is formed on the p-type semiconductor layer 226. The p-electrode 226 is formed of a material and a structure which are known in the art, and is, for example, a translucent conductive film made of ITO or the like and an electrode pad made of a Ti/Au laminate or the like. The p electrode 260 may also be formed of a highly reflective material such as Ag or Al. The n electrode 240 and the p electrode 260 can be formed by any film forming method such as a vacuum deposition method, a sputtering method, or a CVD method.

In addition, as long as at least the first conductive type layer, the active layer, and the second conductive type layer are provided, and voltage is applied to the first conductive type layer and the second conductive type layer, recombination of electrons and holes is performed. When the active layer is made to emit light, the layer of the semiconductor layer is configured to be arbitrary.

The optical element 200 of the embodiment configured as described above may be an upward-facing optical element that extracts light from the p-type semiconductor 226 side. In this case, it is preferable that the p-electrode 260 uses a light-transmitting conductive material. The optical element 200 of the embodiment may be a flip chip type optical element that extracts light from the substrate 100 side. In this case, it is preferable that the p electrode 260 uses a highly reflective material. Either way, the light generated by the active layer 224 can be efficiently extracted to the outside of the element by the diffraction effect of the concave-convex pattern 80 of the substrate.

Further, in the optical element 200, since the uneven pattern 80 is formed on the substrate 100, the semiconductor layer 220 having a small dislocation density is formed, and the characteristics of the light-emitting element 200 are suppressed from being deteriorated.

The present invention has been described above with reference to the embodiments. However, the method for producing an epitaxial growth substrate and the optical element of the present invention are not limited to the above-described embodiments, and can be appropriately within the scope of the technical idea described in the claims. change.

[Industrial availability]

According to the method for producing an epitaxial growth substrate of the present invention, the epitaxial growth substrate can be continuously produced at high speed. Further, since the photolithography method which generates a large amount of waste liquid during the formation of the concavo-convex pattern is not used, the load on the environment is small. Further, since the epitaxial growth substrate of the present invention has a function as a diffraction grating substrate for improving light extraction efficiency, the light-emitting element produced by using the substrate has high luminous efficiency. Therefore, the epitaxial growth substrate of the present invention is extremely effective for the production of a light-emitting element having excellent luminous efficiency, and contributes to energy saving.

Claims (23)

A method for producing an epitaxial growth substrate, comprising: a coating step of applying an inorganic material to a concave-convex pattern surface of a mold having a concave-convex pattern on a surface; and a transfer step of coating the inorganic material The mold is adhered to the substrate, the inorganic material is transferred to the substrate in accordance with the uneven pattern, and a curing step is performed to cure the inorganic material transferred to the substrate. The method for producing an epitaxial growth substrate according to the first aspect of the invention, wherein a surface of the substrate on which the inorganic material is transferred is partially exposed. The method for producing an epitaxial growth substrate according to the first aspect of the invention, wherein in the coating step, the inorganic material is applied to a concave portion of the concave-convex pattern surface of the mold. The method for producing an epitaxial growth substrate according to the first aspect of the invention, wherein in the coating step, the inorganic material is applied to a convex portion of the concave-convex pattern surface of the mold. The method for producing an epitaxial growth substrate according to the first aspect of the invention, comprising the step of etching the substrate after the transfer step to form a concave portion. A method for producing an epitaxial growth substrate, comprising: a coating step of applying a solution of an inorganic material on a substrate to form a film; and a transferring step of pressing the film to have a concave-convex pattern Transferring the uneven pattern to the film to form an uneven structure on the substrate, and an etching step of etching the concave portion of the uneven structure to expose the surface of the substrate; and hardening step This hardens the above-mentioned uneven structure. The method for producing an epitaxial growth substrate according to claim 6, comprising the step of etching the substrate to form a concave portion in a region where the surface of the substrate is exposed. The method for producing an epitaxial growth substrate according to the sixth aspect of the invention, wherein after the etching step, a buffer layer is formed on a surface of the substrate having the uneven structure. The method for producing an epitaxial growth substrate according to claim 1 or 6, wherein a buffer layer is formed on the substrate before the coating step. The method for producing an epitaxial growth substrate according to the first or sixth aspect of the invention, wherein the inorganic material is a sol-gel material. The method for producing an epitaxial growth substrate according to claim 1 or 6, wherein in the transferring step, the inorganic material is heated while being transferred. The method for producing an epitaxial growth substrate according to the first or sixth aspect of the invention, wherein the mold having the concavo-convex pattern is manufactured by self-organization of a block copolymer. The method for producing an epitaxial growth substrate according to claim 12, wherein the structure formed by self-organization of the block copolymer is a horizontal columnar structure or a vertical layered structure. The method for producing an epitaxial growth substrate according to the first or sixth aspect of the invention, wherein the substrate is a sapphire substrate. The method for producing an epitaxial growth substrate according to the first aspect of the invention, wherein i) the convex portion or the concave portion of the concave-convex pattern surface of the mold has an elongated shape in which each of the concave-convex pattern faces is extended in a plan view, and ii) the mold The convex portion or the concave portion of the concave-convex pattern surface has a non-uniform extending direction, a bending direction, and a length. A substrate for epitaxial growth, which is obtained by the method for producing an epitaxial growth substrate according to any one of claims 1 to 8. The substrate for epitaxial growth according to claim 16, wherein i) the convex portion or the concave portion of the concave-convex pattern surface of the epitaxial growth substrate has an elongated shape in which each of the concave-convex pattern surfaces is extended in plan view, and ii) the above-mentioned Lei The convex portion or the concave portion of the concave-convex pattern surface of the crystal growth substrate has a non-uniform extending direction, a bending direction, and a length. The substrate for epitaxial growth according to claim 17, wherein the extending direction of the convex portion is irregularly distributed in a plan view, and the convex portion included in a region per unit area of the concave-convex pattern is in a plan view. The contour line contains a linear interval that is more than the curve interval. The epitaxial growth substrate according to claim 17, wherein a width of the convex portion in a direction substantially perpendicular to a direction in which the convex portion extends in a plan view is constant. The substrate for epitaxial growth according to claim 17, wherein the contour of the convex portion included in the region per unit area of the concave-convex pattern includes a curved section and a straight section, and the curved section is as follows Interval: a linear distance between the ends of the interval when the plurality of sections are formed by dividing the contour of the convex portion in a plan view by a length of π (pi) which is an average value of the width of the convex portion The ratio of the length of the contour line between the two end points is 0.75 or less; and the straight line section is a section which is not the curve section among the plurality of sections. The substrate for epitaxial growth according to claim 17, wherein the outline of the convex portion included in the region per unit area of the concave-convex pattern in a plan view includes a curved section and In the straight line section, the curve section is a section in which a plurality of sections are formed by dividing the contour of the convex portion in a plan view by a length of π (pi) which is an average value of the width of the convex portion. The angle between the one end of the section and the midpoint of the section and the line connecting the other end of the section and the midpoint of the section is 180° or less at an angle of 120° or less; The plurality of sections are not the sections of the curve section, and the ratio of the curve sections in the plurality of sections is 70% or more. The epitaxial growth substrate according to claim 18, wherein the Fourier transform obtained by performing two-dimensional fast Fourier transform processing on the concavity and convexity analysis image obtained by analyzing the concavo-convex pattern by a scanning probe microscope For example, a pattern in which the absolute value of the wave number is 0 μm ^-1 is a substantially circular or circular shape, and the circular or circular pattern is present in the absolute value of the wave number to be 10 μm ^{-1 .} Within the range below. A light-emitting element comprising a semiconductor layer containing at least a first conductive type layer, an active layer, and a second conductive type layer on the epitaxial growth substrate according to any one of claims 17 to 22.