JP4481894B2 - Semiconductor light emitting device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor light emitting device such as a light emitting diode or a semiconductor laser, and more particularly to a semiconductor light emitting device with an improved light extraction portion and a method for manufacturing the same.

  A compound semiconductor constituting a semiconductor light emitting device has a very high refractive index, and a light emitting device using this type of semiconductor has a problem of light loss due to reflection at the surface and interface. For this reason, it is difficult to efficiently extract light generated inside the element to the outside. For example, a compound such as gallium phosphide (GaP) has a refractive index of about 3.2 to 3.5, and only about 19% of light can be extracted due to total reflection.

  As a countermeasure, a single layer film having a refractive index of about 1.5 is generally formed as an antireflection film on the surface of a semiconductor light emitting device. However, this type of light emitting device is not sufficient because the difference in refractive index between the light emitting surface and the single layer film is relatively large.

  In order to increase the light extraction efficiency, it has been studied to form a nanometer-sized regular structure (unevenness) on the surface of the light-emitting element and to transmit the light with high efficiency (see, for example, Non-Patent Document 1). Since the unevenness is nanometer size, light feels the uneven region as a layer whose refractive index smoothly changes from the semiconductor surface to the air. As a result, there is no reflection and the light is completely transmitted. However, in this situation, the light extraction efficiency greatly varies depending on the shape of the uneven region, and a sufficient effect is not obtained at present.

  In addition, the above-mentioned regular structure having an antireflection effect is close to the limit even in the optical lithography using the latest excimer laser because of the nanometer size, so it must be prepared by drawing / etching with an electron beam. Don't be. For this reason, manufacturing cost is high, productivity is poor, and it is not practical. Furthermore, since the regular structure must be fabricated in nanometer size, the margin for the process is low.

  In addition, in order to form a nanometer-sized structure on the surface of the light emitting element, at least one of the micro phase separation structures formed on the surface is formed using a resin composition that forms a micro phase separation structure in a self-organized manner. There is a method of selectively removing the phase and etching the surface using the remaining as an etching mask (see, for example, Patent Document 1). Furthermore, as a technique for roughening the light emitting surface, a technique for roughening the surface by performing surface treatment with hydrochloric acid, sulfuric acid, hydrogen peroxide, or a mixture thereof is known (for example, see Patent Document 2). . In this method, a large amount of light is extracted by using multiple scattering of light on the unevenness by forming micron-size unevenness.

However, these methods are affected by the crystallinity of the substrate, and a surface that can be roughened and a surface that cannot be roughened depending on the orientation of the exposed surface. For this reason, the light extraction surface cannot always be roughened, and the improvement of the light extraction efficiency is limited. In addition, the light extraction efficiency varies greatly depending on the shape of the unevenness, and it is currently unknown what shape is desirable.
JP 2003-258296 A JP 2000-299494 A Applied Physics Letters, 142, vol78,2001, Jpn.J.Appl.Phys., L735, vol39,2000

  As described above, in order to improve the light extraction efficiency, a method for forming a fine concavo-convex structure on the surface of a semiconductor light emitting element has been studied. However, the optimum shape of the concavo-convex structure is not known, and a sufficient effect has been obtained. There is no current situation. In addition, it is extremely difficult to form a fine uneven structure on the surface of the light emitting element with good reproducibility.

  The present invention has been made in consideration of the above circumstances, and the object of the present invention is to form an appropriate concavo-convex structure on the light extraction surface of the light-emitting element, so that the light generated inside the element can be efficiently externalized. It is an object of the present invention to provide a semiconductor light emitting device that can be taken out easily and can improve luminous efficiency.

  Another object of the present invention is to provide a method for manufacturing a semiconductor light emitting device that realizes the above semiconductor light emitting device with low manufacturing cost and high productivity.

  In order to solve the above problems, the present invention adopts the following configuration.

  That is, one embodiment of the present invention is a semiconductor light emitting device in which a plurality of convex structures are formed on a light extraction surface of a semiconductor light emitting element, and the convex structures form a refractive index gradient structure in order from the light extraction surface. It has three structures: a conical mesa part, a cylindrical part forming a diffraction grating structure, and a conical part forming a refractive index gradient structure, and the interval between the convex structures is 1 / (refractive index of external medium + substrate Greater than or equal to the refractive index of the cylindrical portion, and the circle equivalent average diameter of the cylindrical portion is in the range of 1/3 to 9/10 times the circle equivalent average diameter of the lower bottom portion of the mesa portion. The average height of the structure is in the range of 0.6 to 1.5 times the emission wavelength, and the circle-equivalent average diameter at the top of the mesa portion is equal to the circle-equivalent average diameter of the cylindrical portion, and the cylindrical portion The average height of the mesa is in the range of 3/10 to 1 times the emission wavelength. This average diameter is larger than 1 / (the refractive index of the external medium + the refractive index of the substrate) of the emission wavelength and is in the range of 1 time, and the average height of the mesa is in the range of 1/10 to 1/5 of the emission wavelength. The circle equivalent average diameter of the lower bottom portion of the cone portion is equal to the circle equivalent average diameter of the cylindrical portion, and the average height of the cone portion is in the range of 1/10 to 1 times the emission wavelength. It is characterized by.

  Here, the refractive index of the substrate is the refractive index of the semiconductor substrate constituting the light emitting element, and the refractive index of the external medium is the sealing material of the light emitting element existing outside the semiconductor element. Yes, it is the refractive index of air etc. when not sealed.

  According to another aspect of the present invention, there is provided a method for manufacturing the above semiconductor light emitting device, the step of forming a mask in which circular patterns are periodically arranged on the light extraction surface, and a reaction using the mask. A step of forming the cylindrical portion of the convex structure by selectively etching the light radiation side outermost layer or the inorganic light transmitting layer forming the light extraction surface by a reactive ion etching method.

  Further, if necessary, after removing the mask, the mesa portion is formed on the bottom of the cylindrical portion by etching the light emission side outermost layer or the inorganic light transmitting layer by a physical etching method using an inert gas. And forming the conical portion at the top of the cylindrical portion. Note that physical etching methods using an inert gas include sputtering using He, Ar, and Ne, ion milling, and the like.

  According to the present invention, the plurality of convex structures formed on the light extraction surface of the semiconductor light-emitting element are three refractive index gradient structures (mesa portions), diffraction grating structures (cylindrical portions), and refractive index gradient structures (conical portions). By having two structures and optimizing each structure, light generated inside the element can be extracted to the outside with high efficiency, and light emission efficiency can be improved. More specifically, the convex structure of the present invention not only suppresses reflection by the refractive index gradient effect, but also has a diffraction grating structure, so that light having a wider angle of incidence is externally transmitted. It becomes possible to take out.

  Further, in the present invention, by adopting a two-step etching method of reactive ion etching using a mask and physical etching using an inert gas, a semiconductor light emitting device having the above convex structure can be manufactured at low cost and high cost. It can be realized with productivity.

  Before describing embodiments of the invention, the principles of the present invention will be described.

  As a result of earnest research and various experiments to improve the light extraction efficiency in the semiconductor light emitting device, the present inventors formed a convex structure on the light extraction surface, and optimized the convex structure, thereby extracting the light. It has been found that the efficiency is greatly improved.

  FIG. 1 is a diagram showing a basic configuration of a semiconductor light emitting device according to the present invention. A convex structure 20 having a three-stage structure, which will be described later, is formed on the light extraction surface side of the surface-emitting type semiconductor light emitting element substrate 10 having the light emitting layer 13.

  The light extraction surface is generally a current diffusion layer on the light emission side outermost layer surface of the light emitting element substrate 10, and the convex structure 20 is formed in the current diffusion layer. An electrode is partially formed on the current diffusion layer, but the surface where the electrode is not formed is a light extraction surface, and the convex structure 20 is formed in this portion. Alternatively, an inorganic light transmissive layer having a refractive index equivalent to that of the layer may be formed on the current diffusion layer, and the convex structure 20 may be formed on the inorganic light transmissive layer. Due to the simplicity of the process and the high light extraction efficiency, it is better to form the convex structure portion 20 directly on the exposed surface where the electrode of the current diffusion layer is not formed.

  As shown in FIG. 2, the convex structure 20 includes, in order from the bottom to the apex, a mesa portion 21 forming a refractive index gradient structure, a cylindrical portion 22 forming a diffraction grating structure, and a conical portion 23 forming a refractive index gradient structure. It has three structures.

  The convex structure interval H constituting the convex structure 20 is larger than 1 / (refractive index of the external medium + refractive index of the substrate) and not more than one time of the emission wavelength. Here, the refractive index of the external medium <the refractive index of the substrate. The circle equivalent average diameter C of the cylindrical portion 22 of the convex structure 20 is in the range of 1/3 to 9/10 times the circle equivalent average diameter of the lower bottom portion of the mesa portion 21 of the convex structure 20. Furthermore, the average height B of the convex structure 20 is in the range of 0.6 to 1.5 times the emission wavelength.

  Further, the size and height of the three portions 21, 22, and 23 constituting the convex structure 20 are as follows.

(Cylinder part)
The average height E of the cylindrical portion 22 is in the range of 3/10 to 1 times the emission wavelength.

(Mesa)
The circle-equivalent average diameter A at the lower bottom portion of the mesa portion 21 is larger than 1 / (refractive index of the external medium + refractive index of the substrate) and is in a range of one time. The circle-equivalent average diameter C at the top of the mesa portion 21 is equal to the circle-equivalent average diameter C of the cylindrical portion. The average height D of the mesa portion 21 is in the range of 1/10 to 1/5 of the emission wavelength.

(Conical part)
The circle-equivalent average diameter F at the bottom side of the conical portion 23 is equal to the upper top portion of the cylindrical portion 22. The average height G of the conical portion 23 is in the range of 1/10 to 1 times the emission wavelength.

Here, the interval between the convex structures is defined as the distance between the apexes of the conical portion of the convex structure. The circle equivalent average diameter F of the bottom surface of the cylindrical portion 22 and the conical portion 23 is defined by 2 × (area / π) ^0.5 . As for the definition of the cylindrical portion 22 and the conical portion 23, the circularity coefficient of the bottom surface of the circular column and the cone is defined within a range of 0.6 or more and 1 or less. The circularity coefficient is defined by 4π × area / (peripheral length) ^{2. When} this coefficient is less than 0.6, the bottom surface of the cylinder or cone cannot be regarded as a circle. I can't say that. Here, in the present invention, a circularity coefficient of 0.6 or more is regarded as a substantial circle, and the equivalent circular average diameter of the cylindrical portion or the conical portion in this case is the true circle from the area of the substantial circle. It means the diameter when converted to a circle.

  In the present invention, not only visible light but also ultraviolet light can be applied as light. Therefore, it is appropriate that the above-mentioned emission wavelength is in the range of 300 nm to 800 nm, and the range of the circle equivalent average diameter of the lower bottom portion of the mesa portion 21 is 300 / (refractive index of external medium + refractive index of substrate. Rate) in the range of nm to 800 nm.

  In the present invention, the surface on which fine irregularities are provided is the surface of the light emitting side outermost layer of the semiconductor layer constituting the light emitting element, in order to efficiently extract the light radiation from the light emitting element to the outside. Since the optical transmission loss increases at the interface where the refractive indexes are greatly different (for example, 1.5 or more different) at the bonding interface of a plurality of substances constituting the path, fine irregularities are formed on the surface constituting the interface. Is provided. As this interface, the interface between the semiconductor layer and the air layer constituting the light emitting element, or the interface between the semiconductor layer and the protective film when a protective film such as plastic for protecting the light emitting element is formed. Etc.

  Next, the spacing between the convex structures in the convex structure 20 of the present invention, the stipulation of dimensions regarding the three portions 21, 22, 23, and the manufacturing method will be described.

[Convex structure spacing]
Regarding the spacing between the convex structures, when a diffraction grating as shown in FIG. 15 is considered, the equation of the diffraction grating based on the scalar theory is given as follows.

Here, n ₀ , n _sub , θ _i , θ _m , λ, and d are the refractive index of the external medium, the refractive index of the substrate (calculated in 3.2), the incident angle, the outgoing angle, the wavelength, and the diffraction grating, respectively. It is an interval. In order to cause diffraction of the first order or higher, n ₀ <n _sub (refractive index of external medium <substrate refractive index), m is the diffraction order, and m = −1 is related to the improvement of light extraction. . Here, for the sake of simplicity, calculation was performed with n ₀ = 1 (air) and λ = 600 nm. The calculation result of the incident angle at which -1st order light can be diffracted obtained from the equation (1) is shown in the following (Table 1).

  From this (Table 1), it can be seen that diffraction does not occur when the distance between the convex structures is 100 nm. Therefore, the improvement in light extraction is only for the refractive index gradient effect. It can be seen that diffraction occurs at a wide angle incidence when the grating interval is 150,200 nm, and diffraction occurs at a wide range of 39 ° or more at 200 nm. For this reason, light extraction is improved by a refractive index gradient effect at a shallow angle incidence, and light extraction is improved by a diffraction effect at a wide angle incidence. Therefore, it is considered that significant light extraction improvement is realized. From the equation (1), when the external medium is air, diffraction occurs if the lattice spacing is larger than 1 / (1 + refractive index) of the emission wavelength. When the grating interval is further increased, the -1st order diffraction angle becomes shallow, and the diffraction angle becomes narrow within 38 ° at 600 nm, which is the same as the wavelength. However, even at 600 nm, light extraction is improved because light having a wider angle than the total reflection angle (19 °) is diffracted. However, if the wavelength is larger than the wavelength, the -1st order diffraction angle becomes a shallower angle, so that the light extraction is not improved so much, and the effect of scattering appears and the light extraction is not improved so much. Therefore, the interval between the convex structures is desirably 1 time or less.

[Cylinder part]
The circle equivalent average diameter of the cylindrical portion 22 is in the range of 1/3 to 4/5 times the circle equivalent average diameter of the lower bottom portion of the mesa portion 21 and coincides with the circle equivalent average diameter C of the top top portion of the mesa portion 21. . By doing so, reflection at the interface between the mesa portion 21 and the cylindrical portion 22 does not occur.

Diffraction as to size and spacing of the irregularities, the scattering (diffraction) intensity I _s in the case where there is shading (n1, n0) of the refractive index in the space is given by the following equation.

In formula (3), n ₀ ² is related only to a small angle and may be handled as 0. Therefore, substituting equation (3) into equation (2) gives the following.

The contents of the integral are factors of the shape and size of the irregularities, and by solving this, you can see how much light is emitted at which angle. <Η ^2> _av is the density factor of unevenness, scattering when this value is maximum (diffraction) I _s is maximized. If the volume fraction of GaP is φ _A and the volume fraction of space is φ _B , <η ² > _av is given as follows.

Thus, I _s is the maximum φ _A = φ _B = 0.5.

From this, it can be seen that the diffraction efficiency is determined by the product of φ _A and φ _B. The circle-equivalent mean diameter has a maximum in the vicinity of 0.7 times the circle-equivalent mean diameter of the lower bottom portion of the mesa portion 21, and the effect of diffraction away from this becomes small.

  Further, when the circle-equivalent average diameter C of the upper top portion of the mesa portion 21 is larger than 9/10 times that of the lower bottom portion or smaller than 1/3 times, the effect of diffraction compared to the optimized interval. Becomes 1/5 or less. Therefore, the circle-equivalent average diameter C at the upper top is preferably in the range of 1/3 to 9/10 times that of the lower bottom. This is determined from the following theory.

  When the average height E of the cylindrical portion 22 is referred to a document (Journal of Optical Society Of America, 1385, vol72, No10, October, 1982), it is estimated that 3/10 or more of the wavelength of light is preferable. If it is smaller than this, the diffraction effect is almost lost. Further, the average height E is desirably about 1 time or less. This is because if it exceeds that, the diffraction efficiency will decrease.

[Mesa part]
In the surface structure that causes light scattering, the larger the size of the surface structure, the greater the influence on the light, and the effect is proportional to the square of the size. Therefore, it is preferable that the circle equivalent average diameter A of the lower bottom part of the mesa part 21 is 1/20 or more of the wavelength of the emitted light of a light emitting element. If the circle-equivalent average diameter A is smaller than this, the Rayleigh scattering region is deviated, and the unevenness effect is rapidly lost. A more preferable range is about 1/10 or more of the wavelength of light. The mesa portion is assumed to be larger than 1 / (external refractive index + substrate refractive index), but in the case of the external refractive index 1.5 and the substrate refractive index 3.5, 1 / (1.5 + 3.5) = 1/5. And is in an area where scattering occurs. On the other hand, when the circle-equivalent average diameter A is larger than the wavelength of light, the light recognizes the shape of the unevenness itself, so that the effect of the refractive index gradient is lost. Furthermore, the circle-equivalent average diameter A is desirably less than or equal to the wavelength of light that is large enough for the light not to recognize the uneven shape.

  The average height D of the mesa unit 21 is preferably 1/10 or more of the wavelength of light. If it is smaller than this, the refractive index changes at a very short distance, and the effect as a refractive index gradient is lost. On the other hand, when the average height D is high, light incident at a wide angle, in particular, does not reach the cylindrical portion 22 but is reflected and returned into the substrate, so that the diffraction effect cannot be generated in the cylindrical portion 22. For this reason, the average height D is preferably about 1/5 or less of the wavelength of light.

  If the circle-equivalent average diameter C at the top of the mesa portion 21 is larger than 9/10 times that of the bottom portion, the effect of the refractive index gradient is almost lost and reflection occurs. On the other hand, when it is smaller than 1/3 times, the distance between the cylindrical portions 22 becomes too large, so that the diffraction effect is not weakened. Therefore, the circle-equivalent average diameter C at the upper top is preferably in the range of 1/3 to 9/10 of the lower bottom.

[Cone]
The circle-equivalent average diameter F on the bottom surface of the conical part 23 matches the circle-equivalent average diameter of the cylindrical part 22. By doing so, reflection at the interface between the cylindrical portion 22 and the conical portion 23 does not occur.

  The average height G of the conical portion 23 is preferably 1/10 or more of the wavelength of light. If it is smaller than this, the refractive index changes at a very short distance, and the effect as a refractive index gradient is lost. On the other hand, if the average height G is too high, the effect of the refractive index gradient is lost. Therefore, the average height G is desirably about 1 time or less.

(Production method)
First, a normal photolithographic exposure apparatus or electron beam drawing apparatus can be used as a method for producing the required pattern size. Further, there is a method using a microphase separation structure using a block copolymer developed by the present inventors (Japanese Patent Laid-Open No. 2001-151834: hereinafter referred to as Patent Document 3). In addition, there is a method in which polymer beads or silica beads are used as a mask (Applied Physics Letters, 2174, vol 63, 1993).

Form the above-mentioned mask on the light emitting side outermost layer of the semiconductor layer constituting the light emitting element or the surface of the inorganic light transmitting layer formed on the layer, and form a cylindrical pattern by reactive ion etching (RIE) To do. Thereafter, the cylindrical pattern is formed using a gas that is chemically inert to the material, such as Ar, He, Ne, Xe, O ₂ , N ₂ , CF ₄ , CHF ₃ , and SF _4. Physically etch. When physical etching is performed on the cylindrical pattern, the upper surface of the cylinder and the lower surface without the cylinder are etched, and a mesa portion and a cone portion are formed by itself. By adopting such a two-step etching method, it is possible to produce the three structural portions.

  The details of the present invention will be described below with reference to the illustrated embodiments.

[Configuration of Light Emitting Element]
The light emitting device of the present invention is a semiconductor light emitting device such as a light emitting diode (LED) or a semiconductor laser (LD).

  FIG. 3 is a cross-sectional view showing an element structure of a light emitting diode according to an embodiment of the present invention.

  In the figure, reference numeral 11 denotes an n-type GaP substrate, on which a heterostructure part including an n-type InAlP cladding layer 12, an InGaP active layer 13, a p-type InAlP cladding layer 14 and the like is formed, and a p-type is formed thereon. The GaP current diffusion layer 15 is formed. A p-side electrode 16 is formed on a part of the current diffusion layer 15, and an n-side electrode 17 is formed on the back side of the substrate 11. The emitted light in the active layer 13 is extracted from the surface of the current diffusion layer 15 where the electrode 16 is not formed.

  Although the basic configuration so far is substantially the same as that of the conventional element, in addition to this, in this embodiment, minute irregularities are formed on the exposed surface of the current diffusion layer 15 where the electrode is not formed. And the unevenness | corrugation of this surface becomes the surface which has the above-mentioned convex structure 20. FIG. As shown in FIG. 4, an inorganic light-transmitting layer 18 having a refractive index equivalent to that of the layer 15 is formed on the exposed surface of the current diffusion layer 15 where the electrode is not formed. Fine irregularities may be formed on the surface. In view of the simplicity of the process and the high light extraction efficiency, it is better to form minute irregularities directly on the exposed surface of the current diffusion layer 15 where the electrode is not formed.

[Method for Manufacturing Light-Emitting Element]
Next, a method for manufacturing such a light emitting element will be described.

  First, a method using a microphase separation structure using a block copolymer developed by the present inventors will be described (see Patent Document 3).

  First, as shown in FIG. 5 (a), after forming a double hetero structure portion with an active layer 13 sandwiched between cladding layers 12 and 14 on an n-GaP substrate 11, a current diffusion layer 15 is epitaxially grown thereon. The p-side electrode 16 is formed on a part of the current diffusion layer 15, and the n-side electrode 17 is formed on the back surface side of the substrate 11. The process so far is the same as the conventional process.

  Next, as shown in FIG. 5B, a solution obtained by dissolving a block copolymer, which is a microphase separation structure composition, in a solvent was applied to the light emitting element substrate 10 having the structure shown in FIG. 5A by spin coating. Thereafter, the mask material layer 31 is formed by pre-baking to evaporate the solvent. Subsequently, annealing is performed in a nitrogen atmosphere, and phase separation of the block copolymer is performed.

  Next, the block copolymer of the phase-separated film is etched by performing RIE of the phase-separated substrate with the block copolymer under an etching gas flow. At this time, since the phase of one of the polymer fragments is selectively etched due to the difference in the etching rate of the plurality of polymer fragments constituting the block copolymer, a minute pattern 32 remains as shown in FIG. .

Next, as shown in FIG. 5 (d), fine concavo-convex patterns are formed on the surface of the current diffusion layer 15 by performing RIE with a required etching gas using the polymer fragment pattern 32 left without being etched away as a mask. Is done. The gas used can be etched not only by Cl ₂ but also by adding BCl ₃ and N ₂ . Thereafter, the polymer fragment remaining by the O ₂ asher is removed to form a cylindrical concavo-convex pattern.

  Next, when sputtering is performed with an inert gas, for example, Ar gas or He gas, as shown in FIG. 5E, the upper bottom portion and the lower bottom portion of the cylinder are sputter-etched, and the cone + cylinder + shown in FIG. 1 and FIG. A convex structure 20 having a mesa portion is obtained.

  A manufacturing method using PS fine particles as a polymer bead as a mask will also be described.

  As shown to Fig.6 (a), the light emitting element substrate 10 is the same as Fig.5 (a). The light emitting element substrate 10 having the structure shown in FIG. 6A is immersed in an aqueous solution in which PS particles having a diameter of 200 nm are monodispersed. Thereafter, the substrate 10 is gradually pulled up. When pulling up, there is a so-called meniscus line in which the substrate surface, the surface of the aqueous solution, and the air interface exist, so that PS particles are attracted to the substrate surface along that, and the PS particles are in a monolayer on the substrate surface. Arranged. As a result, a pattern 33 of PS fine particles is formed as shown in FIG.

Next, as shown in FIG. 6C, fine concavo-convex patterns are formed on the surface of the current diffusion layer 15 by performing RIE with a required etching gas using the PS fine particle pattern 33 as a mask. Thereafter, the PS fine particles remaining by the O ₂ asher are removed to form a cylindrical concavo-convex pattern. Subsequently, as shown in FIG. 6 (d), when the sputtering is performed with an inert gas, the upper bottom portion and the lower bottom portion of the cylinder are sputter-etched, and the convex structure having the cone + column + mesa portion shown in FIG. 1 and FIG. 20 is obtained.

  Further, a manufacturing method by electron beam drawing will be described.

As shown in FIG. 7A, the light emitting element substrate 10 is the same as FIG. In this method, first, as shown in FIG. 7B, an electron beam resist is formed on the light emitting element substrate 10, and an electron beam exposure apparatus having an acceleration voltage of 50 kV equipped with a pattern generator is used. A resist pattern 35 in which circular patterns are periodically arranged is generated. Next, as shown in FIG. 7C, by using this resist pattern 35 and performing RIE with a required etching gas, a fine uneven pattern is formed on the surface of the current diffusion layer 15. Thereafter, the remaining resist is removed by an O ₂ asher to form a cylindrical concavo-convex pattern. Subsequently, as shown in FIG. 7 (d), when the sputtering is performed with an inert gas, the upper bottom portion and the lower bottom portion of the cylinder are sputter-etched, and the convex structure having the cone + column + mesa portion shown in FIG. 1 and FIG. 20 is obtained.

In this method, the same result can be obtained even if an optical lithography method using an excimer laser beam such as F ₂ , ArF, KrF or the like and an emission line of a mercury lamp such as i-line or g-line as a light source instead of an electron beam. .

  In addition, although not necessarily limited to the following method, the etching method using the micro phase separation structure of the block copolymer will be described in more detail.

[Microphase-separated structure-forming resin composition]
After forming a thin film of a block copolymer or graft copolymer and microphase separation (intramolecular phase separation of the block copolymer), one polymer phase is selectively removed, whereby a porous having a nanometer size pattern Form a membrane. The obtained porous film can be used as a mask for transferring a pattern by etching a base. To selectively remove one polymer phase from a microphase-separated structure, use the difference in dry etching rate, difference in decomposability with respect to energy rays, or difference in thermal decomposability between the two polymer phases. . In any method, since it is not necessary to use a lithography technique, the throughput is high and the cost can be reduced.

[Formation of microphase-separated structure-forming composition thin film]
In order to form a thin film made of the microphase structure-forming resin composition, it is preferable to apply a uniform solution of the resin composition to the surface of the light emitting element. If a uniform solution is used, it is possible to prevent a history during film formation from remaining. If the coating solution is non-uniform due to the formation of micelles with a relatively large particle size in the solution, it is difficult to form a regular pattern because of an irregular phase separation structure. Since it takes time to do, it is not preferable.

  The solvent that dissolves the block copolymer that is the microphase structure-forming resin composition is desirably a good solvent for the two types of polymers constituting the block copolymer. The repulsive force between polymer chains is proportional to the square of the difference between the solubility parameters of the two polymer chains. Therefore, if a good solvent for the two kinds of polymers is used, the difference in solubility parameter between the two kinds of polymer chains becomes small, and the free energy of the system becomes small, which is advantageous for phase separation.

  When preparing a block copolymer thin film, a high boiling point such as ethyl cellosolve acetate (ECA), propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate (EL), etc. at 150 ° C. or higher so that a uniform solution can be prepared. It is preferable to use a solvent having

  The film thickness of the formed microphase-separated structure-forming composition thin film is preferably in the range of about the same or three times the circle equivalent average diameter of the target surface irregularities. When this film thickness deviates from this range, it is difficult to obtain a convex structure having a desired average diameter.

[Formation of micro phase separation structure]
The microphase-separated structure of the block copolymer or graft copolymer can be produced by the following method. For example, a coating solution is prepared by dissolving a block copolymer or a graft copolymer in a suitable solvent, and this coating solution is applied onto a substrate and dried to form a film. By annealing this film at a temperature equal to or higher than the glass transition temperature of the polymer, a good phase separation structure can be formed. After the copolymer is melted and annealed at a temperature not lower than the glass transition temperature and not higher than the phase transition temperature to cause microphase separation, the microphase separation structure may be fixed at room temperature. A microphase separation structure can also be formed by slowly casting a solution of the copolymer. The copolymer can be melted and molded into a desired shape by a method such as hot pressing, injection molding or transfer molding, and then annealed to form a microphase separation structure.

  The means for forming a nanometer-sized structure using the microphase separation structure thus formed is described in detail in Patent Document 3, and this means can also be adopted in the present invention. .

  The pattern transfer method is also an effective method. Details are described in Patent Document 3, and this means can also be adopted in the present invention. Specifically, a layer (pattern transfer layer) having different etching resistance is applied on the compound semiconductor substrate, and the block copolymer layer of the present invention is further applied. At this time, for the pattern transfer layer, materials such as SOG (spin on glass) as shown in Patent Document 3 can be used.

  The block copolymer layer is etched dry or wet, and only one phase of the block copolymer is selectively removed to form a concavo-convex pattern. Next, the pattern transfer layer is etched using the organic polymer pattern as a mask. For example, when a fluorine-based, chlorine-based, or bromine-based gas is used, a pattern transfer layer such as SOG can be etched using an organic substance as a mask.

  In this way, the microphase separation pattern of the block copolymer can be transferred to the pattern transfer layer. Next, the substrate is etched using the pattern transfer layer to which this pattern is transferred as a mask.

  Such a method is effective for etching a compound containing a metal that cannot have an etching selectivity with respect to the carbon-based polymer material. In addition, by using a plurality of pattern transfer layers, it is possible to stack materials having different etching resistances and obtain a pattern having a high aspect ratio.

(Example)
Next, the present invention will be described more specifically with reference to the following examples. Examples 1 to 17 are a method for producing irregularities using a microphase separation structure of a block copolymer, Examples 18 to 21 are methods for producing a response using PS or silica particles, and Example 22 is an electron beam drawing method. Describes the method for forming the unevenness.

Example 1
FIG. 3 is a sectional view showing the element structure of the light emitting diode according to the first embodiment of the present invention.

  A double heterostructure is formed on the n-GaP substrate 11 with the InGaAlP active layer 13 sandwiched between the n-InAlP clad layer 12 and the p-InAlP clad layer 14, and a p-GaP current diffusion layer 15 is formed thereon. ing. A p-side electrode 16 is formed on a part of the p-GaP current diffusion layer 15, and an n-side electrode 17 is formed on a part of the lower surface of the n-GaP substrate 11, thereby forming a light emitting diode having an emission wavelength of 650 nm. ing.

  Here, GaAs can be used as the substrate 11 instead of GaP, and InAlP or InGaAlP can be used as the current diffusion layer 15 instead of GaP. Of course, the substrate may be p-type and the overall conductivity type may be reversed.

  On the surface of the current diffusion layer 15 where the electrode 16 is not formed, a convex structure 20 that is characteristic of the present embodiment is formed. As shown in FIGS. 1 and 2, the convex structure 20 has three structures: a mesa portion 21 forming a refractive index gradient structure, a cylindrical portion 22 forming a diffraction grating structure, and a conical portion 23 forming a refractive index gradient structure. The circle-equivalent average diameter of the bottom part of the unevenness that becomes the lower bottom part of the mesa part 21 is 160 nm, the circle-equivalent average diameter of the upper top part is 100 nm, the average height is 80 nm, the lower bottom part and the upper top part of the cylindrical part 22 The circle-equivalent average diameter is the same as that of the lower bottom of the mesa portion 21 and is 80 nm, the average height is 250 nm. The interval between the convex structures is 180 nm.

  Next, the manufacturing method of the light emitting diode of a present Example is demonstrated.

  First, as shown in FIG. 5A, an n-InAlP clad layer 12, an InGaAlP active layer 13, a p-InAlP clad layer 14 and a p-GaP current diffusion layer 15 are formed on an n-GaP substrate 11 by metalorganic chemistry. Continuous growth is performed by vapor deposition (MOCVD). Subsequently, the p-side electrode 16 is formed on the current diffusion layer 15, the n-side electrode 17 is formed on the lower surface of the substrate 11, and each of the electrodes 16 and 17 is processed into a desired pattern. Thereby, the light emitting element substrate 10 is manufactured.

  Next, as shown in FIG. 5B, a solution obtained by dissolving a block copolymer in a solvent is applied onto the light emitting element substrate 10 by spin coating at a rotational speed of 2500 rpm, and then pre-baked at 110 ° C. for 90 seconds to remove the solvent. Vaporized. Thereby, the block copolymer film 31 is formed on the surface of the current diffusion layer 15 where the electrode 16 is not formed. Here, the block copolymer film 31 is made of polystyrene (PS) and polymethyl methacrylate (PMMA). The molecular weight of PS is 154800, the molecular weight of PMMA is 392300, and Mw / Mn is 1.08. Subsequently, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere, and phase separation of PS and PMMA of the block copolymer film 31 was performed.

Next, the phase-separated substrate with the block copolymer was etched by RIE at a CF ₄ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power of 100 W to etch PS and PMMA of the phase-separated film. At this time, due to the etching rate difference between PS and PMMA, the PMMA is selectively etched, and the PS pattern 32 remains as shown in FIG.

Next, as shown in FIG. 5D, RIE is performed for 60 seconds with a Cl ₂ flow rate of 50 sccm, a pressure of 0.266 Pa (2 mTorr), and a power of 300 W using the PS pattern 32 as a mask. A cylindrical pattern was formed. Etching can be performed by adding not only Cl ₂ but also BCl ₃ gas. Thereafter, the remaining PS was removed by an O ₂ asher.

  Next, as shown in FIG. 5 (e), by sputtering with Ar gas at an Ar flow rate of 50 sccm, a pressure of 0.65 Pa (5 mTorr), and a power of 300 W for 60 seconds, the bottom and top of the cylinder are sputtered. And a conical part were formed.

  As a result, the average diameter of the lower bottom portion of the mesa portion is 160 nm, the average diameter of the upper top portion of the mesa portion is 100 nm, and the average height of the mesa portion is 70 nm on the surface of the compound semiconductor substrate other than the electrode and wiring pattern. The average diameter of the part is 100 nm, the average height is 250 nm, the average diameter of the cone part is 100 nm, the average height is 80 nm, and the interval between the convex structures is 180 nm. It was.

  When this was subjected to element processing and compared with a light emitting diode not subjected to surface processing, a luminance improvement of 30% was observed.

(Example 2)
In addition, the phase-separated PS and PMMA are etched by RIE of the block copolymer-attached substrate prepared by the same method as in Example 1 at an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W. To do. The substrate etched with O ₂ cannot cut the substrate as compared with CF ₄ , but can selectively etch PMMA instead. Then, when the same process as Example 1 was performed, the minute unevenness | corrugation which has a cone + cylinder + mesa part was formed.

  The average diameter of the lower bottom part of the mesa part 21 is 160 nm, the average diameter of the top part is 100 nm, the average height is 70 nm, the average diameter of the cylindrical part 22 is 100 nm, the average height is 250 nm, and the average of the cone part 23 Fine irregularities having a cone, a cylinder, and a mesa portion were formed with a diameter of 100 nm, an average height of 80 nm, and a convex structure spacing of 180 nm.

  When this was subjected to element processing and compared with a light emitting diode not subjected to surface processing, a luminance improvement of 30% was observed.

(Example 3)
A solution obtained by dissolving a block copolymer having molecular weights of PS: 315000 and PMMA: 785000 in a solvent was applied to the current diffusion layer 15 which is the uppermost layer of the light emitting element formation substrate 10 used in Example 1 at 3000 rpm by a spin coating method. Thereafter, pre-baking was performed at 110 ° C. for 90 seconds to evaporate the solvent and obtain a film thickness of 150 nm. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere, phase separation between PS and PMMA was performed, and a PS dot pattern having a diameter of about 110 nm was formed.

The phase-separated PS and PMMA are etched by performing RIE on this phase-separated GaP substrate with a block copolymer under an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W. O ₂ obtained by etching can not be scraping the GaP substrate may be selectively etched instead PMMA. Since the etching rate ratio of PS and PMMA is 1: 4, the PMMA is selectively etched to leave a PS pattern, and its thickness is about 130 nm.

Next, using this PS pattern as a mask, using capacitively coupled plasma (ICP), BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr), incident power / bias power = 100 / When 150 seconds was performed at 100 W, a fine columnar pattern having a diameter of 100 nm and a height of 450 nm was formed. Thereafter, the remaining PS was removed by an O2 asher. Thereafter, similarly to Example 1, when Ar sputtering was performed, minute irregularities having a cone + cylinder + mesa portion were formed.

  As a result, the average diameter of the lower bottom portion of the mesa portion is 170 nm, the average diameter of the top portion is 110 nm, the average height is 80 nm, the average diameter of the cylindrical portion 22 is 110 nm, and the average height is on the GaP light emitting layer surface. Microscopic irregularities having a cone + cylinder + mesa portion with a diameter of 350 nm, an average diameter of the cone portion 23 of 110 nm, an average height of 120 nm, and a convex structure interval of 180 nm were formed.

  When this was subjected to element processing and compared with a light emitting diode that had not been subjected to surface processing, 60% improvement in luminance was observed.

Example 4
Further, a block copolymer-attached substrate prepared by the same method as in Example 3 and subjected to phase separation is subjected to RIE at BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr), and incident power / bias power = 100/100 W. Thus, PS and PMMA separated by phase were etched. Since the etching rate ratio of PS and PMMA is 1: 4, PMMA is selectively etched, and the PS pattern remains. Thereafter, the same process as in Example 3 was performed. Thereafter, when Ar sputtering was performed in the same manner as in Example 1, minute irregularities having a cone + column + mesa portion were formed.

As a result, the average diameter of the lower bottom portion of the mesa portion 21 is 160 nm, the average diameter of the upper top portion is 100 nm, the average height is 100 nm, the average diameter of the cylindrical portion 22 is 100 nm, and the average height on the compound semiconductor light emitting layer surface. Was 300 nm, the average diameter of the conical portion 23 was 100 nm, the average height was 120 nm, and the interval between the convex structures was 180 nm, and minute concavities and convexities having a cone + cylinder + mesa portion could be formed. In this process, PMMA was removed by RIE of BCl ₃ / Cl ₂ and irregularities were formed on the surface of the compound semiconductor light emitting layer.

  When this was subjected to element processing and compared with a light emitting diode not subjected to surface processing, a 55% improvement in luminance was observed.

(Example 5)
Further, polystyrene (PS) -polyisoprene (PI) was used as the block copolymer. The molecular weight of PS was 450,000, the molecular weight of PI was 1230000, and Mw / Mn was 1.07. A substrate with a block copolymer that was phase-separated by the same method as in Example 3 was prepared. Of the PS-PI block copolymer phase-separated with ozone, PI was selectively removed by ozone oxidation.

Using this PS pattern as a mask, using capacitively coupled plasma (ICP), BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W After 160 seconds, a cylindrical pattern was formed. Thereafter, the remaining PS was removed by an O ₂ asher. Thereafter, Ar sputtering was performed in the same manner as in Example 1 to form minute irregularities having a cone + cylinder + mesa portion.

  As a result, the average diameter of the lower bottom portion of the mesa portion 21 is 170 nm, the average diameter of the top top portion is 100 nm, the average height is 100 nm, the average diameter of the cylindrical portion 22 is 100 nm, and the average height on the GaP light emitting layer surface. Was 400 nm, the average diameter of the conical part 23 was 100 nm, the average height was 120 nm, and the interval between the convex structures was 180 nm, and minute concavities and convexities having a cone + cylinder + mesa part could be formed.

  When this was subjected to element processing and compared with a light emitting diode not subjected to surface processing, an improvement in luminance of 80% was observed.

  In the method of this example, since the PI monomer hardly absorbs water, a polymer having a high molecular weight is more easily polymerized than PMMA at the time of polymerization. For this reason, it is easy to enlarge the pattern. In this method, a film having a thickness as large as the pattern size of the block copolymer must be formed. For this reason, if it is a big pattern, the height of the pattern transcribe | transferred to a compound semiconductor can be made high. In addition, substantially the same structure was obtained even when polybutadiene (PB) was used instead of PI.

(Example 6)
FIG. 8 is a sectional view showing a manufacturing process of a light emitting diode according to the sixth embodiment of the present invention. The same parts as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8A, a light emitting element substrate 10 having the same structure as that of Example 1 was prepared. The uppermost current spreading layer 15 is InGaAlP.

  Next, as shown in FIG. 8B, a three-layer resist 36 (Nissan Chemical ARCXHRiC-11) was applied to form a film having a thickness of 500 nm. This was baked in an oven at 300 ° C. for 1 minute. Subsequently, spin-on-glass (SOG) 37 (Tokyo Ohka OCD T-7) was spin-coated at 110 nm thereon, and baked on a hot plate at 200 ° C. for 60 seconds, and further at 300 ° C. for 60 seconds. Further, a solution 38 in which the same block copolymer as in Example 3 was dissolved in a solvent was applied onto the substrate by spin coating at 2500 rpm, and then pre-baked at 110 ° C. for 90 seconds to evaporate the solvent. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere to separate the block copolymer PS and PMMA.

This phase-separated substrate with a block copolymer was subjected to RIE at an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power = 100 W, thereby etching the PS and PMMA of the phase-separated film. At this time, due to the etching rate difference between PS and PMMA, PMMA is selectively etched, and a PS pattern remains. Using this PS pattern as a mask, SOG was etched at a CF ₄ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power = 100 W. Further, when RIE was performed at an O ₂ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power = 100 W, the lower resist film was etched, and a columnar pattern having a height of 500 nm could be obtained. A mask pattern 39 as shown in FIG. 8C is formed.

Next, as shown in FIG. 8D, the current diffusion layer 15 was etched with BCl ₃ / N ₂ = 23: 7 sccm, pressure 0.200 Pa (1.5 mTorr), and power 500 W. Finally, ashing was performed with oxygen to remove the polymer. Note that the SOG was not removed by the previous BCl ₃ / N ₂ etching, which was not a problem.

  Thereafter, when Ar sputtering was performed in the same manner as in Example 1, as shown in FIG. 8E, minute irregularities having a cone + cylinder + mesa portion were formed.

  As a result, InGaAlP that was difficult to be etched by a normal etching method could be performed. As for the shape after etching, the average diameter of the lower bottom part of the mesa part 21 is 170 nm, the average diameter of the top part is 110 nm, the average height is 150 nm, the average diameter of the cylindrical part 22 is 110 nm, and the average height is 350 nm. The conical portion 23 had an average diameter of 110 nm, an average height of 100 nm, and a convex structure having a spacing of 200 nm.

(Example 7)
FIG. 9 is a cross-sectional view showing a manufacturing process of a light emitting diode according to the seventh embodiment of the present invention. The same parts as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9A, a light-emitting element substrate 10 similar to that in Example 1 was prepared. Next, as shown in FIG. 9B, block copolymers 41 and 41 ′ are formed on the surface of the p-GaP current diffusion layer 15 as the light extraction surface and the back surface of the n-GaP substrate 11 by the same method as in Example 3. Formed.

  Next, as shown in FIG. 9C, the block copolymer-attached substrate is annealed in a nitrogen atmosphere at 210 ° C. for 4 hours, phase separation of PS and PMMA is performed, and a PS dot pattern 42 having a diameter of about 110 nm is obtained. , 42 '.

Next, as shown in FIG. 9 (d), the phase separation is performed by performing RIE on both surfaces of the substrate with the block-separated block copolymer under the conditions of an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W. Etched PS and PMMA. The PMMA was selectively etched to leave a PS pattern, the thickness of which was about 130 nm on both sides.

Using this PS pattern as a mask, both surfaces of p-GaP and n-GaP are BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr) using capacitively coupled plasma (ICP), When incident power / bias power = 100/100 W was performed for 150 seconds, a fine columnar pattern having a diameter of 100 nm and a height of 450 nm was formed on the p-GaP and n-GaP surfaces. Thereafter, the remaining PS was removed by an O ₂ asher. Thereafter, similarly to Example 1, by performing Ar sputtering on both sides, minute irregularities having a cone + column + mesa portion were formed on both surfaces of p-GaP and n-GaP.

  As a result, on the light extraction surfaces of p-GaP and n-GaP, the average diameter of the lower bottom portion of the mesa portion 21 is 180 nm, the average diameter of the upper top portion is 100 nm, and the average height is 80 nm. The average diameter is 100 nm, the average height is 350 nm, the average diameter of the cone portion 23 is 100 nm, the average height is 120 nm, and the interval between the convex structures is 180 nm. did it.

  When this was subjected to element processing and compared with a light emitting diode that had not been subjected to surface processing, 100% improvement in luminance was observed. In addition, since the light emitting diode of the present embodiment emits light not only from the front surface but also from the back surface, it was confirmed that the luminance was significantly improved by providing unevenness on the back surface.

(Example 8)
Spin-on glass (SOG) (Tokyo Ohka OCD T-7) was spin-coated at 110 nm on the light-emitting element substrate 10 on which InGaAlP having the same structure as that of Example 6 was formed on the light extraction surface, and 200 ° C. on a hot plate. , 60 seconds, and further baked at 300 ° C. for 60 seconds. Further, a solution obtained by dissolving the same block copolymer as in Example 3 in a solvent was applied to the substrate by spin coating at a rotation speed of 2500 rpm, and then pre-baked at 110 ° C. for 90 seconds to vaporize the solvent. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere to separate the block copolymer PS and PMMA.

This phase-separated substrate with a block copolymer was subjected to RIE at an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W, thereby etching PS and PMMA of the phase-separated film. At this time, due to the etching rate difference between PS and PMMA, PMMA is selectively etched, and a PS pattern remains. Next, using this PS pattern as a mask, SOG was etched with a CF ₄ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power of 100 W. As a result, a mask pattern 39 was formed as shown in FIG.

Next, when ICP is used for 3 minutes at BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W, as shown in FIG. A cylindrical pattern was formed. Thereafter, Ar sputtering was performed in the same manner as in Example 1 to form minute irregularities having a cone + cylinder + mesa portion as shown in FIG.

  As a result, after etching, the average diameter of the lower bottom portion of the mesa 21 is 170 nm, the average diameter of the top top is 100 nm, the average height is 120 nm, the average diameter of the cylindrical portion 22 is 100 nm, and the average height is Minute concavities and convexities having a cone + cylinder + mesa portion having a diameter of 450 nm, an average diameter of the conical portion 23 of 100 nm, an average height of 150 nm, and a convex structure interval of 180 nm were formed.

  When the luminous efficiency of this sample was compared with that of the sample without the pattern, it was confirmed that the luminance was improved by 120%.

Example 9
SOG was formed to a thickness of 100 nm on the surface of the GaP current diffusion layer 15 which is the light emitting diode used in Example 1 in the same manner as in Example 7. Further, a solution in which the same block copolymer as in Example 3 was dissolved in a solvent was applied by spin coating at 2500 rpm, and then pre-baked at 110 ° C. for 90 seconds to evaporate the solvent. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere to separate the block copolymer PS and PMMA.

This phase-separated substrate with a block copolymer was subjected to RIE at an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W, thereby etching PS and PMMA of the phase-separated film to form a PS pattern. Using this PS pattern as a mask, SOG was etched with a CF ₄ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power of 100 W.

Next, when ICP is used for 3 minutes at BCl ₃ / Cl ₂ / CF ₄ = 5/20/5 sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W, a cylindrical pattern Formed. Thereafter, Ar sputtering was performed in the same manner as in Example 1 to form minute irregularities having a cone + cylinder + mesa portion.

As a result, after etching, the average diameter of the lower bottom portion of the mesa 21 is 180 nm, the average diameter of the top top is 110 nm, the average height is 150 nm, the average diameter of the cylindrical portion 22 is 110 nm, and the average height is 500 nm, the average diameter of the conical portion 23 is 110 nm, the average height is 180 nm, the interval between the convex structures is 190 nm, and a minute unevenness having a cone + cylinder + mesa portion can be formed. When the luminous efficiency of the samples was compared, it was confirmed that the luminance was improved by 150%.

(Example 10)
A block copolymer having a molecular weight of PS: 300,000 and PMMA: 420,000, and a PMMA homopolymer having a molecular weight of 15000 and Mw / Mn = 1.07 are mixed at a weight ratio of 6: 4, each of 3% by weight of PGMEA. The solution was adjusted to be a solution. This solution was applied by spin coating onto the surface of the GaP light emitting layer 15 which is the light emitting diode used in Example 1, at 2500 rpm, and then pre-baked at 110 ° C. for 90 seconds to evaporate the solvent. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere, and phase separation of the block copolymer PS and PMMA was performed.

The phase-separated PS and PMMA are etched by performing RIE on this phase-separated substrate with a block copolymer under conditions of an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power = 100 W. O ₂ obtained by etching can not cut the GaP but can be selectively etched instead PMMA. Since the etching rate ratio of PS and PMMA is 1: 4, the PMMA is selectively etched to leave a PS pattern, and its thickness is about 130 nm.

When this PS pattern is used as a mask and ICP is used for 150 seconds with BCl ₃ / Cl ₂ = 5/20 sccm, 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W, the diameter is 100 nm, A fine columnar pattern having a height of 450 nm was formed. Thereafter, the remaining PS was removed by an O ₂ asher. Thereafter, similarly to Example 1, by performing Ar sputtering, minute irregularities having a cone + cylinder + mesa portion were formed.

  As a result, the average diameter of the lower bottom portion of the mesa portion 21 is 160 nm, the average diameter of the top top portion is 90 nm, the average height is 100 nm, the average diameter of the cylindrical portion 22 is 90 nm, and the average height on the GaP light emitting layer surface. 350 nm, the average diameter of the conical portion 23 is 90 nm, the average height is 110 nm, and the interval between the convex structures is 180 nm, and minute concavities and convexities having a cone + cylinder + mesa portion can be formed. When this was subjected to element processing and compared with a light emitting diode not subjected to surface processing, a 70% improvement in luminance was observed.

  When the PMMA homopolymer was added to the block copolymer, the regularity of the phase separation structure was increased to some extent, so that the diffraction efficiency was improved and the luminance was considered to be improved as compared with Example 3.

(Example 11)
PS (polystyrene) -PI (polyisoprene) diblock copolymer (molecular weight (Mw) PS: 230,000, PI: 400,000 Mw / Mn = 1.06) was used as the phase separation polymer, and a low molecular weight homopolymer (molecular weight Mw). : 2000, Mw / Mn: 1.45), an example using a PI polymer is shown. That is, in the same manner as in Example 9, a low molecular weight homopolymer of PI was added to the PS-PI diblock polymer and dissolved in PGEMEA to form a solution.

  In the same manner as in Example 9, a mixture of PS-PI diblock copolymer and PI homopolymer was thinned on the GaP current diffusion layer 15 of the light-emitting element substrate 10, and a microphase separation structure was formed by thermal annealing, and then ozone oxidation. PI was removed by the method, and a PS etching mask was formed on the substrate. Thereafter, a light emitting device was produced in the same manner as in Example 9. As a result, the luminance was improved by about 100% compared to the sample in which no light emitting surface was processed.

(Example 12)
A sample in which PMMA with Mw = 15000 and PS homopolymer with a molecular weight of 9000 was added to a block copolymer with PS of 240,000, PMMA of 730,000, and Mw / Mn of 1.08 on the current spreading layer of the light emitting device substrate. Thinned. The mixing ratio of the PS-PMMA block copolymer, the PMMA homopolymer and the PS homopolymer, and the PS diameter of the resulting microphase separation pattern are as shown in Table 2 below.

As a result, it can be seen that the spherical pattern of PS increases with the addition of PS. In the pattern forming method used in the present invention, the film thickness needs to be set to the same degree as the diameter of the PS sphere. For this reason, the polymer thin film was applied on the GaP current diffusion layer 15 on which the electrode was prepared by adjusting the polymer concentration and the spin coating rotation speed so that the film thickness was almost the same as the obtained diameter. This was annealed in the same manner to generate a phase separation structure in the film. This phase-separated substrate with a block copolymer was subjected to RIE at O ₂ = 30 sccm, pressure 1.33 Pa (10 mTorr), and power = 100 W, thereby removing PMMA in the phase-separated polymer film. When the remaining PS pattern was used as a mask and RIE was performed with Cl ₂ = 50 sccm, 0.266 Pa (2 mTorr), and power = 300 W, a fine pattern was formed on the current diffusion layer. Thereafter, the remaining PS was removed by an O ₂ asher.

  Subsequently, sputtering was performed with Ar gas at Ar = 50 sccm, 0.65 Pa (5 mTorr), power = 300 W for 60 seconds, and the bottom and top of the cylinder were sputtered to form a mesa and a cone.

As a result, minute irregularities having a cone + cylinder + mesa portion could be formed on the surface other than the electrode and wiring pattern of the current diffusion layer forming the light extraction surface. The improvement of the brightness compared with the light emitting diode which processed the element and did not perform the surface processing was as follows (Table 3).

  Thus, by adding homopolymers to both the majority and minority phases of the block copolymer, it is possible to increase the phase separation pattern of the block copolymer, and as a result, the high PS of the mask that etches the compound semiconductor can be obtained. Since the thickness can be increased, the compound semiconductor can be etched deeply. This method is effective when it is difficult to increase the molecular weight or to reduce variation among lots.

(Example 13)
FIG. 10 is a sectional view showing an element structure of a light emitting diode according to the thirteenth embodiment of the present invention. The light emitting diode of this embodiment emits ultraviolet light (UV light).

First, a SiNx pattern is formed on the single crystal Al ₂ O ₃ substrate 51 as an etching mask as follows. A liquid obtained by forming a SiNx film with a thickness of 200 nm on a single-crystal Al ₂ O ₃ substrate 51 by plasma CVD, and dissolving a block copolymer of PS: 315000, PMMA: 785000 in molecular weight and Mw / Mn = 1.06 in PGMEA Was applied by spin coating at 3000 rpm and prebaked at 110 ° C. for 90 seconds to evaporate the solvent and obtain a film thickness of 150 nm.

Next, annealing was performed at 180 ° C. for 4 hours in a nitrogen atmosphere to separate phases of PS and PMMA to form a polystyrene dot pattern having a diameter of about 110 nm. This phase-separated single crystal Al ₂ O ₃ substrate with a block copolymer was subjected to RIE under the conditions of O ₂ = 30 sccm, pressure 13.3 Pa (100 mTorr), power = 100 W, and PMMA of phase-separated PS-PMMA. Was selectively etched. As a result, the aggregated polystyrene having a size of about 0.1 μm remains at an interval of about 0.1 μm, and becomes a mask for forming a SiNx pattern.

This sample was etched for 6.5 minutes under the conditions of Ar / CHF ₃ = 185/15 sccm, pressure 40 mTorr, and power 100 W to form a SiNx pattern as an etching mask. Next, using the SiNx pattern as an etching mask, the single crystal Al ₂ O ₃ substrate 51 was etched for 20 minutes under the conditions of BCl ₃ / Cl ₂ = 5/20 sccm, pressure 5 mTorr, and power 100 W. Subsequently, when sputtering was performed with Ar gas at Ar = 50 sccm, pressure 0.65 Pa (5 mTorr), and power 300 W for 5 minutes, the bottom and top of the cylinder were sputtered to form a mesa and a cone.

Thereby, on the surface of the single crystal Al ₂ O ₃ substrate 51, the average diameter of the lower bottom part of the mesa part is 120 nm, the average diameter of the top part is 80 nm, the average height is 90 nm, the average diameter of the cylindrical part is 80 nm, the average The height is 250 nm, the average diameter of the conical part is 80 nm, the average height is 100 nm, and the interval between the convex structures is 170 nm, and a minute unevenness (convex structure 60) having a cone + cylinder + mesa part can be formed. .

Next, n-Al _0.4 Ga _0.6 N (contact layer) 52, n-Al _0.35 Ga _0.65 N (cladding layer) 53, n-Al are formed on the uneven surface of the single crystal Al ₂ O ₃ substrate 51 by a CVD process. _0.28 Ga _0.72 N / n-Al _0.24 Ga _0.76 N (SL active layer) 54, p-Al _0.4 Ga _0.6 N / p-Al _0.3 Ga _0.7 N (SL clad layer) 55, p-GaN (contact layer) 56 Sequential growth formed. Subsequently, the contact layer 56 to the cladding layer 53 were selectively removed to expose a part of the contact layer 52. Then, a p-side electrode 57 and an n-side electrode 58 were formed on the contact layer 56 and the contact layer 52, respectively, and then cut into chips to obtain a light emitting element.

  The structure of the fabricated element is as shown in FIG. 10, and the emitted light in the active layer 54 is extracted from the back side of the substrate through the substrate 51. The light emission intensity of ultraviolet light (λ = 300 nm) was compared between the light emitting element of this example and the light emitting element in which the convex structure was not manufactured. As a result, the brightness of the convex structure was improved by about 40% compared to the brightness of the convex structure. Thus, it was confirmed that the structure obtained by this example was effective even with UV light.

(Example 14)
In contrast to the light-emitting diode (UV-LED) that emits ultraviolet light in which the convex structure 60 is formed on the surface of the single crystal Al ₂ O ₃ substrate 51 in Example 13, a phosphor is placed on the back surface of the substrate 51 to obtain white light. I was going to put out. The phosphors used are as follows (Table 4).

  The phosphor was thinned on the light emitting surface of the LED (the back surface of the substrate 51 in FIG. 10) and sealed with an epoxy resin. Using the same phosphor, the brightness of white light was compared with an LED having no convex structure on the LED surface. As a result, the brightness of the uneven LED was about 30% higher. As a result, it was confirmed that the structure obtained by this example was effective even with a white LED using a phosphor.

(Example 15)
FIG. 11 is a sectional view showing an element structure of a light emitting diode according to the fifteenth embodiment of the present invention. The same parts as those in FIG. 10 are denoted by the same reference numerals, and detailed description thereof is omitted. The light emitting diode of this example also emits ultraviolet light (UV light) as in Example 13.

On a single crystal Al ₂ O ₃ substrate 51, n-Al _0.4 Ga _0.6 N (contact layer) 52, n-Al _0.35 Ga _0.65 N (cladding layer) 53, n-Al _0.28 Ga _0.72 N / n- Al _0.24 Ga _0.76 N (SL active layer) 54, p-Al _0.4 Ga _0.6 N / p-Al _0.3 Ga _0.7 N (SL clad layer) 55, and p-GaN (contact layer) 56 were sequentially grown. Subsequently, the contact layer 56 to the cladding layer 53 were selectively removed to expose a part of the contact layer 52. Then, a p-side electrode was formed on the contact layer 56, and an n-side electrode 58 was formed on the contact layer 52 to produce a light emitting diode (UV-LED).

Next, a SiNx pattern is formed on the opposite side of the layer laminated by the CVD process. A SiNx film having a thickness of 200 nm was formed on the back surface of the single crystal Al ₂ O ₃ substrate 11 by plasma CVD, and a block copolymer of PS: 315000, PMMA: 785000, and a molecular weight of Mw / Mn = 1.06 was dissolved in PGMEA. The solution was applied by spin coating at 3000 rpm and then pre-baked at 110 ° C. for 90 seconds to evaporate the solvent and obtain a film thickness of 150 nm.

Next, annealing was performed at 180 ° C. for 4 hours in a nitrogen atmosphere to separate phases of PS and PMMA to form a polystyrene dot pattern having a diameter of about 110 nm. This phase-separated single crystal Al ₂ O ₃ substrate 51 with a block copolymer is subjected to RIE under the conditions of O ₂ = 30 sccm, pressure 13.3 Pa (100 mTorr), power = 100 W, and phase-separated PS-PMMA PMMA was selectively etched. As a result, the aggregated polystyrene having a size of about 0.1 μm remains at an interval of about 0.1 μm, and becomes a mask for forming a SiNx pattern.

This sample was etched for 6.5 minutes under the conditions of Ar / CHF ₃ = 185/15 sccm, 40 mTorr, 100 W to form a SiNx pattern as an etching mask. Next, the single crystal Al ₂ O ₃ substrate 51 was etched for 20 min under the conditions of BCl ₃ / Cl ₂ = 5/20 sccm, pressure 5 mTorr, and power 100 W using the SiNx pattern as an etching mask. Subsequently, when sputtering was performed with Ar gas at an Ar flow rate of 50 sccm, a pressure of 0.65 Pa (5 mTorr), and a power of 300 W for 5 minutes, the bottom and top of the cylinder were sputtered to form a mesa and a cone.

Thereby, on the back surface of the single crystal Al ₂ O ₃ substrate 51, the average diameter of the lower bottom part of the mesa part is 110 nm, the average diameter of the top part is 80 nm, the average height is 90 nm, the average diameter of the cylindrical part is 80 nm, the average The height is 250 nm, the average diameter of the conical part is 80 nm, the average height is 100 nm, and the interval between the convex structures is 170 nm, and a minute unevenness (convex structure 60) having a cone + cylinder + mesa part can be formed. .

  The structure of the manufactured element is as shown in FIG. The light emission intensity of ultraviolet light (λ = 300 nm) was compared between the light emitting element of this example and the light emitting element in which the convex structure was not manufactured. As a result, the brightness of the convex structure was improved by about 50% compared to the brightness of the convex structure. Thus, it was confirmed that the structure obtained by this example was effective even with UV light.

(Example 16)
In contrast to the UV-LED in which the convex structure 60 was produced on the back surface of the single crystal Al ₂ O ₃ substrate 51 in Example 15, a white light was emitted by placing a phosphor on the back surface of the substrate 51. The phosphor used is as shown in (Table 4) above.

  This phosphor was thinned on the light emitting surface of the LED (the back surface of the substrate 51 in FIG. 11) and sealed with an epoxy resin. The brightness of white light was compared with that of an LED having a convex structure on the LED surface using the same phosphor. As a result, the brightness of the uneven LED was about 35% higher.

(Example 17)
FIG. 12 is a sectional view showing an element structure of a light emitting diode according to the seventeenth embodiment of the present invention.

  An n-type GaN buffer layer 62, an n-type GaN cladding layer 63, an InGaN / GaN MQW active layer 64, a p-type AlGaN cap layer 65, and a p-type GaN contact layer 66 are grown on the n-type GaN substrate 61, A p-side electrode 67 is formed on a part of the contact layer 66, and an n-side electrode 68 is formed on the back surface of the substrate 61. The light emission wavelength of this light emitting diode was 400 nm. Further, a convex structure 70 which is a feature of the present embodiment is formed on the surface of the contact layer 66 where the electrode 67 is not formed.

  Next, the manufacturing method of the light emitting diode of a present Example is demonstrated.

  First, as shown in FIG. 13A, an n-GaN buffer layer 62 and an n-GaN cladding layer 63 are grown on an n-GaN substrate 61 by MOCVD, and an MQW made of InGaN / GaN is formed thereon. An active layer 64 is grown and formed. Furthermore, a p-AlGaN cap layer 65 and a p-GaN contact layer 66 are grown thereon by MOCVD. Then, a p-side electrode 67 is formed on the contact layer 66, an n-side electrode 68 is formed on the back surface of the substrate 61, and each of the electrodes 67 and 68 is processed into a desired pattern. Thereby, the light emitting element substrate 60 is manufactured.

  Next, as shown in FIG. 13B, an SOG film 71 having a thickness of 100 nm is formed on the light emitting element substrate 60 in the same manner as in Example 9, and a solution 72 in which a block copolymer is dissolved in a solvent is spin-coated. After coating at 2500 rpm, the solvent was vaporized by prebaking at 110 ° C. for 90 seconds. Next, annealing was performed at 210 ° C. for 4 hours in a nitrogen atmosphere to separate the block copolymer PS and PMMA.

Next, as shown in FIG. 13 (c), the phase-separated film PS and PMMA were obtained by RIE of the phase-separated substrate with the block copolymer at an O ₂ flow rate of 30 sccm, a pressure of 13.3 Pa (100 mTorr), and a power of 100 W. Was etched to form a PS pattern 73. Thereafter, the SOG was etched using the PS pattern 73 as a mask at a CF ₄ flow rate of 30 sccm, a pressure of 1.33 Pa (10 mTorr), and a power of 100 W.

Next, as shown in FIG. 13D, using ICP, BCl ₃ / Cl ₂ = 5/20 / sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W for 3 minutes. When done, a cylindrical pattern was formed.

  Next, as shown in FIG. 13E, when Ar gas is sputtered at Ar = 50 sccm, pressure 0.65 Pa (5 mTorr), power 300 W for 2 minutes, the bottom and top of the cylinder are sputtered, and the mesa and cone Part was formed. As a result, after etching, the average diameter of the lower bottom part of the mesa part is 140 nm, the average diameter of the top part is 100 nm, the average height is 100 nm, the average diameter of the cylindrical part is 100 nm, and the average height is 400 nm. The average diameter of the cone portion was 100 nm, the average height was 100 nm, and the interval between the convex structures was 180 nm, so that minute irregularities having a cone + cylinder + mesa portion could be formed.

  When the luminous efficiency of the sample with no pattern was compared with that of the example sample, it was confirmed that the luminance of the example sample was improved by 80%.

(Example 18)
The light emitting element substrate 10 provided with the light emitting layer surface of GaP which is the light emitting diode used in Example 1 is immersed in an aqueous solution in which PS particles (density 1.05) having a diameter of 200 nm are monodispersed. Thereafter, the substrate is pulled up at a speed of 10 μm / sec under conditions of a temperature of 25 ° C. and a humidity of 40%. During the pulling, there is an interface in the air between the substrate surface, the aqueous solution surface, and the air, so that PS particles are attracted to the substrate surface along a so-called meniscus line, and the PS particles are arranged in a monomolecular layer on the substrate surface (FIG. 6). (B)).

When this substrate with PS particles is subjected to BCl ₃ / Cl ₂ = 5/20 sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W for 2 minutes using ICP, a cylindrical pattern is formed. Formed (FIG. 6C). Thereafter, when Ar sputtering was performed in the same manner as in Example 1, fine irregularities having a cone + cylinder + mesa portion as shown in FIG. 6D were formed.

  As a result, after etching, the average diameter of the lower bottom part of the mesa part is 200 nm, the average diameter of the top part is 150 nm, the average height is 100 nm, the average diameter of the cylindrical part is 150 nm, and the average height is 300 nm. In addition, a minute concavity and convexity having a cone + cylinder + mesa portion with an average diameter of the cone portion of 150 nm, an average height of 120 nm, and a convex structure interval of 220 nm were formed.

  When the luminous efficiencies of this example sample and the sample without a pattern were compared, it was confirmed that the luminance of the example sample was improved by 60%.

(Example 19)
A light-emitting element substrate having a light extraction surface of GaP, which is the light-emitting diode used in Example 1, is immersed in an aqueous solution in which PS particles (density 1.05) having a diameter of 500 nm are monodispersed. Thereafter, PS particles were arranged in a monomolecular layer on the substrate surface by pulling up in the same manner as in Example 18.

  When this substrate with PS particles was subjected to BCl3 / Cl2 = 5/20 sccm, 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W for 3 minutes using ICP, a cylindrical pattern was formed. . Thereafter, when Ar sputtering was performed in the same manner as in Example 1, fine irregularities having a cone + column + mesa portion were formed as shown in the figure.

  As a result, after etching, the average diameter of the lower bottom part of the mesa part is 500 nm, the average diameter of the top part is 350 nm, the average height is 150 nm, the average diameter of the cylindrical part is 350 nm, and the average height is 450 nm. The average diameter of the cone portion was 350 nm, the average height was 150 nm, and the interval between the convex structures was 550 nm, and fine irregularities having a cone + column + mesa portion could be formed.

  When the luminous efficiencies of this example sample and the sample without a pattern were compared, it was confirmed that the luminance of the example sample was improved by 30%. When PS particles are used as in this example, it is possible to easily form a convex structure having a size that is difficult to achieve with a block copolymer.

(Example 20)
A light-emitting element substrate having a light extraction surface of GaP, which is the light-emitting diode used in Example 1, is immersed in an aqueous solution in which silica particles having a diameter of 200 nm (density 2.0) are monodispersed. Thereafter, silica particles were arranged in a monomolecular layer on the substrate surface by pulling up in the same manner as in Example 18 (FIG. 6B).

When this substrate with silica particles is subjected to BCl ₃ / Cl ₂ = 5/20 sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W for 3 minutes using ICP, a cylindrical pattern is formed. Formed (FIG. 6C). Thereafter, when Ar sputtering was performed in the same manner as in Example 1, fine irregularities having a cone + cylinder + mesa portion as shown in FIG. 6D were formed.

  As a result, after etching, the average diameter of the lower bottom part of the mesa part is 200 nm, the average diameter of the top part is 150 nm, the average height is 150 nm, the average diameter of the cylindrical part is 150 nm, and the average height is 450 nm. The cone had an average diameter of 150 nm, an average height of 150 nm, and a convex structure with an interval of 220 nm. Microscopic irregularities having a cone + cylinder + mesa portion could be formed.

  When the luminous efficiency of this example sample and a sample without a pattern were compared, it was confirmed that the luminance of the example sample was improved by 130%. Thus, since the silica particles are highly resistant to chlorine-based etching and have a higher selectivity than the PS particles, a higher uneven shape can be formed.

(Example 21)
FIG. 14 is a sectional view showing an element structure of a light emitting diode according to the twenty-first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to FIG. 13 and an identical part, and the detailed description is abbreviate | omitted.

  As shown in FIG. 14A, an element formation substrate 60 similar to that in Example 17 is prepared. Next, as shown in FIG. 14B, the surface (GaN contact layer) of the element formation substrate 60 is immersed in an aqueous solution in which silica particles having a diameter of 300 nm (density 2.0) are monodispersed. Thereafter, the silica particles 75 were arranged in a monomolecular layer on the substrate surface by pulling up in the same manner as in Example 18.

Next, as shown in FIG. 14 (c), the substrate with silica particles is made of ICP and BCl ₃ / Cl ₂ = 5/20 sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W. When etching was performed for 3 minutes under the conditions, a cylindrical pattern was formed. After that, by performing Ar sputtering in the same manner as in Example 1, as shown in FIG. 14D, minute irregularities having a cone + column + mesa portion were formed.

  As a result, the shape after etching is such that the average diameter of the lower bottom portion of the mesa portion is 300 nm, the average diameter of the top portion is 170 nm, the average height is 220 nm, the average diameter of the cylindrical portion is 170 nm, and the average height is 500 nm. In addition, minute concavities and convexities having a cone, a cylinder, and a mesa portion were formed in which the average diameter of the cone portion was 170 nm, the average height was 200 nm, and the interval between the convex structures was 250 nm.

  When the luminous efficiencies of this example sample and the sample without a pattern were compared, it was confirmed that the luminance of the example sample was improved by 90%. As described above, in this example, the brightness increased because GaN could be etched deeper.

(Example 22) (EB drawing)
An electron beam resist (manufactured by Fujifilm: FEP-301) was formed on the light-emitting element substrate 10 having the surface of the GaP light-emitting layer, which is the light-emitting diode used in Example 1. Then, a 150 nm circular pattern was generated by an electron beam exposure apparatus equipped with a pattern generator and having an acceleration voltage of 50 kV (FIG. 7B).

When this resist-patterned substrate is etched using ICP under the conditions of BCl ₃ / Cl ₂ = 5/20 / sccm, pressure 0.266 Pa (2 mTorr), incident power / bias power = 100/100 W, for 3 minutes. A cylindrical pattern was formed (FIG. 7C).

  Subsequently, when sputtering is performed with Ar gas at Ar = 50 sccm, pressure 0.65 Pa (5 mTorr), power 300 W for 2 minutes, the bottom and top of the cylinder are sputtered, and the mesa and cone as shown in FIG. Part was formed.

  As a result, after etching, the average diameter of the lower bottom part of the mesa part is 200 nm, the average diameter of the top part is 150 nm, the average height is 100 nm, the average diameter of the cylindrical part is 150 nm, and the average height is 400 nm. In addition, a minute concavity and convexity having a cone + cylinder + mesa portion with an average diameter of the cone portion of 150 nm, an average height of 100 nm, and a convex structure interval of 220 nm could be formed.

  When the luminous efficiencies of this example sample and the sample without a pattern were compared, it was confirmed that the luminance of the example sample was improved by 100%.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. Moreover, it is also possible to implement combining an Example suitably.

1 is a cross-sectional view showing a basic configuration of a semiconductor light emitting device according to the present invention. The figure which expands and shows the convex structure in FIG. Sectional drawing which shows the element structure of the light emitting diode concerning one Embodiment of this invention. Sectional drawing which shows the element structure of the light emitting diode concerning other embodiment of this invention. Sectional drawing which shows the manufacturing process (utilizing the micro phase-separation structure using a block copolymer) of the light emitting diode of FIG. Sectional drawing which shows the manufacturing process (PS fine particle utilization) of the light emitting diode of FIG. Sectional drawing which shows the manufacturing process (electron beam drawing utilization) of the light emitting diode of FIG. Sectional drawing which shows the manufacturing process of the light emitting diode concerning a 6th Example. Sectional drawing which shows the manufacturing process of the light emitting diode concerning a 7th Example. Sectional drawing which shows the element structure of the light emitting diode concerning a 13th Example. Sectional drawing which shows the element structure of the light emitting diode concerning a 15th Example. Sectional drawing which shows the element structure of the light emitting diode concerning a 17th Example. Sectional drawing which shows the manufacturing process of the light emitting diode concerning a 17th Example. Sectional drawing which shows the manufacturing process of the light emitting diode concerning a 21st Example. Sectional drawing which shows the structure of a convex diffraction grating for demonstrating the principle of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... n-GaP board | substrate 12 ... n-InAlP clad layer 13 ... InGaAlP active layer 14 ... p-InAlP clad layer 15 ... p-GaP current spreading layer 16, 57, 67 ... p side electrode 17, 58, 68 ... n side Electrodes 20, 60, 70 ... convex structure 21 ... mesa part 22 ... cylindrical part 23 ... conical part 31 ... mask material layer 32 ... polymer fragment pattern 33 ... PS particle pattern 35 ... resist pattern 36 ... three-layer resist 37, 71 ... SOG film 38,72 ... block copolymer solution 41 ... block copolymer 42 ... dot pattern 51 ... Al ₂ O ₃ substrate 52 ... n-AlGaN contact layer 63 ... n-AlGaN cladding layer 54 ... n-AlGaN / n- AlGaN active layer 55 ... p-AlGaN / p-AlGaN cladding layer 56 ... p-GaN contour Coat layer 61 ... n-GaN substrate 62 ... n-GaN buffer layer 63 ... n-GaN clad layer 64 ... MQW active layer 65 ... p-AlGaN cap layer 66 ... p-GaN contact layer 73 ... PS pattern 75 ... Silica particles pattern

Claims (12)

A semiconductor light emitting device in which a plurality of convex structures are formed on a light extraction surface of a semiconductor light emitting element,
The convex structure has, in order from the light extraction surface, a conical mesa portion that forms a refractive index gradient structure, a cylindrical portion that forms a diffraction grating structure, and a conical portion that forms a refractive index gradient structure,
The interval between the convex structures is greater than 1 / (refractive index of the external medium + refractive index of the substrate) and not more than 1 time, and the circle-equivalent mean diameter of the cylindrical portion is the lower bottom portion of the mesa portion. A semiconductor light emitting device characterized in that it is in the range of 1/3 to 9/10 times the circle equivalent average diameter.   The circle-equivalent average diameter of the top portion of the mesa portion is equal to the circle-equivalent average diameter of the cylindrical portion, and the circle-equivalent average diameter of the bottom portion of the mesa portion is 1 / (refractive index of external medium + substrate 2. The semiconductor light emitting device according to claim 1, wherein the average height of the mesa portion is in the range of 1/10 to 1/5 of the emission wavelength.   The circle-equivalent average diameter of the lower bottom part of the cone part is equal to the circle-equivalent average diameter of the cylindrical part, and the average height of the cone part is in the range of 1/10 to 1 times the emission wavelength. The semiconductor light emitting device according to claim 1 or 2.   4. The semiconductor light emitting device according to claim 1, wherein the average height of the convex structure is in the range of 0.6 to 1.5 times the emission wavelength.   5. The semiconductor light emitting device according to claim 1, wherein an average height of the cylindrical portion is in a range of 3/10 to 1 times the emission wavelength. A semiconductor light emitting device in which a plurality of convex structures are formed on a light extraction surface of a semiconductor light emitting element,
The convex structure has, in order from the light extraction surface, a conical mesa portion that forms a refractive index gradient structure, a cylindrical portion that forms a diffraction grating structure, and a conical portion that forms a refractive index gradient structure,
The interval between the convex structures is in a range greater than 1 / (refractive index of external medium + refractive index of substrate) and not more than one time, and the average height of the convex structures is 0.6 to 1 of the emission wavelength. .5 times the range,
The circle equivalent average diameter of the cylindrical portion is in the range of 1/3 to 9/10 times the circle equivalent average diameter of the lower bottom portion of the mesa portion, and the average height of the cylindrical portion is 3/10 to 1 of the emission wavelength. Double the range
The circle-equivalent average diameter of the top portion of the mesa portion is equal to the circle-equivalent average diameter of the cylindrical portion, and the circle-equivalent average diameter of the bottom portion of the mesa portion is 1 / (refractive index of external medium + substrate The average height of the mesa portion is in the range of 1/10 to 1/5 of the emission wavelength,
The circle-equivalent average diameter of the lower bottom part of the cone part is equal to the circle-equivalent average diameter of the cylindrical part, and the average height of the cone part is in the range of 1/10 to 1 times the emission wavelength. A semiconductor light emitting device.   The light-emitting element is a light-emitting diode, and an electrode is formed on a part of the light extraction surface, and the convex structure is formed on a portion of the light extraction surface where the electrode is not formed. Item 14. A semiconductor light emitting device according to Item 1. A method for manufacturing a semiconductor light-emitting device according to claim 1,
Forming a mask in which circular patterns are periodically arranged on the light extraction surface;
Forming the cylindrical portion of the convex structure by selectively etching the light emitting side outermost layer or the inorganic light transmitting layer forming the light extraction surface by a reactive ion etching method using the mask; and
A method for manufacturing a semiconductor device, comprising: A method for manufacturing a semiconductor light-emitting device according to claim 1,
Forming a mask in which circular patterns are periodically arranged on the light extraction surface;
Forming the cylindrical portion of the convex structure by selectively etching the light emitting side outermost layer or the inorganic light transmitting layer forming the light extraction surface by a reactive ion etching method using the mask; and
The mesa portion is formed at the bottom of the cylindrical portion by etching the outermost layer on the light emission side or the inorganic light transmitting layer by a physical etching method using an inert gas, and the conical portion is formed at the top of the cylindrical portion. Forming a step;
A method of manufacturing a semiconductor light emitting device, comprising:   10. The step of forming the mask, wherein a resist is formed on the light extraction surface, and then the circular pattern is drawn on the resist by a lithography method using an electron beam or light. Manufacturing method of the semiconductor light-emitting device.   As the step of forming the mask, after forming a thin film made of a resin composition containing a block copolymer or a graft copolymer on the light extraction surface and forming a micro phase separation structure in a self-organized manner, 10. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein at least one phase of the phase separation structure is selectively removed.   10. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein the step of forming the mask includes forming a polymer bead or silica bead in a single particle layer on the light extraction surface.

Images