JP2006041479A - Light emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element and its manufacturing method which promotes the outside radiation, without holding the light in a layer having a high optical absorption coefficient. <P>SOLUTION: A sapphire substrate is lifted off from an n-GaN layer 13 of an LED element 1, and a glass member 11, having a higher refractive index than that of the sapphire substrate, is bonded to the n-GaN layer 13. This reduces layer-confined lights confined in the GaN layer to increase blue lights to be radiated to the outside, resulting in an improved light extraction properties. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device and a method for manufacturing the same, and more particularly to a light emitting device capable of promoting external radiation without stopping light in a layer having a large light absorption coefficient and a method for manufacturing the same.

  Conventionally, a method of manufacturing a light emitting device by growing a semiconductor crystal made of a group III nitride compound semiconductor on a base substrate such as sapphire is known. In such a light-emitting element, there is a problem that light generated in the light-emitting layer is confined in a layer having a high light absorption coefficient and is absorbed in the layer, thereby reducing external radiation efficiency.

  As a solution to such a problem, there is a light emitting element in which an uneven surface is formed on the surface of a sapphire substrate and a group III nitride compound semiconductor layer is provided thereon (see, for example, Patent Document 1).

  The light emitting device described in Patent Document 1 is formed of a group III nitride compound semiconductor on a substrate surface, and a surface of the buffer layer having a texture structure, a trapezoidal shape, or a pit shape is formed. A group III nitride compound semiconductor layer is formed on the layer.

According to the light-emitting element described in Patent Document 1, the light incident on the interface between the sapphire substrate and the group III nitride compound semiconductor layer with a large angle (light having a small angle between the interface and the light traveling direction). Even in such a case, the light can be emitted from the step surface (side surface) to the outside, and the light extraction efficiency is improved.
JP 2003-197961 A ([0011], FIG. 1)

  However, according to the light-emitting element described in Patent Document 1, the extraction of light confined in the layer (in-layer confinement light) other than the light extracted directly from the group III nitride compound semiconductor layer is uneven. Even if the processing is performed, the reflectivity of the light confined in the layer is not sufficient, and the light extraction efficiency is limited because it depends on the refractive index difference between the group III nitride compound semiconductor layer and the sapphire substrate. In addition, since the group III nitride compound semiconductor layer has a large light absorption coefficient, it is attenuated and cannot be used effectively when it becomes confined light in the layer.

  Accordingly, an object of the present invention is to provide a light emitting device capable of promoting external radiation without stopping light in a layer having a large light absorption coefficient, and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides a flip-chip type light emitting device having a semiconductor layer including a light emitting layer and provided with first and second electrodes on the mounting surface side. A light-emitting element having a light-transmitting high refractive index material layer having a refractive index n = 1.6 or more provided on a surface side is provided.

  In order to achieve the above object, the present invention includes a semiconductor layer including a light-emitting layer, and a light-transmitting high-refractive index material layer having a refractive index n = 1.6 or more attached to the semiconductor layer. The light-transmitting high-refractive-index material layer provides a light-emitting element made of glass.

  In order to achieve the above object, the present invention provides a substrate preparation step for preparing a base substrate, a semiconductor layer forming step for forming a semiconductor layer on the base substrate, and a lift-off for lifting off the base substrate from the semiconductor layer. A translucent high refractive index material layer forming step for providing a translucent high refractive index material layer on the base substrate mounting side of the semiconductor layer lifted off the base substrate, and the translucent high refractive index material An electrode forming step of forming an electrode on the semiconductor layer provided with the layer is provided.

  According to the present invention, in-layer confinement light that remains in the semiconductor layer is extracted through the translucent high-refractive-index material layer that is attached to the semiconductor layer, so that interface reflection is suppressed and light extraction performance is improved. As a result, external radiation can be promoted without stopping light in the layer having a large light absorption coefficient.

(First embodiment)
(Configuration of LED element 1)
1A and 1B are LED elements according to the first embodiment, FIG. 1A is a longitudinal sectional view, and FIG. 1B is an explanatory view showing a critical angle. As shown in FIG. 1A, the flip-chip type LED element 1 includes a glass member 11 which is a light-transmitting high refractive index material having a higher refractive index than a GaN-based semiconductor layer 100 having a light emitting layer 14, and a GaN semiconductor. An n-GaN layer 13 formed of a compound, a light emitting layer 14 stacked on the n-GaN layer 13, a p-GaN layer 15 stacked on the light emitting layer 14, and the p-GaN layer 15 to n − The n-electrode 16 provided on the n-GaN layer 13 removed by etching over the GaN layer 13 and the p-electrode 18 provided on the p-GaN layer 15 are included.

  The formation method of the group III nitride compound semiconductor layer is not particularly limited, but the well-known metal organic chemical vapor deposition method (MOCVD method), molecular beam crystal growth method (MBE method), halide vapor phase epitaxy method (HVPE method). ), A sputtering method, an ion plating method, an electron shower method, or the like. Note that a light-emitting element having a homo structure, a hetero structure, or a double hetero structure can be used. Furthermore, a quantum well structure (single quantum well structure or multiple quantum well structure) can also be adopted.

Glass member 11 has refractive index n = 2.0, coefficient of thermal expansion: 7.0 × 10 ⁻⁶ / ° C., yield point: 6
A GaN-based semiconductor compound grown on a sapphire substrate (not shown) with a Bi ₂ O ₃ -based material at 50 ° C. is separated from the sapphire substrate by being peeled off by irradiation with a laser beam, and exposed to the exposed n-GaN layer 13. It is heat-sealed.

  FIG.1 (b) is a figure which shows the difference in the critical angle at the time of using a glass member. In the case of a sapphire substrate, the critical angle with respect to the interface 1A is in a range indicated by an arrow of n = 1.7 (45 degrees with respect to the interface direction), and is externally radiated without being totally reflected as compared with the case of the glass member 11. Less light. Light that is not emitted externally becomes confined light within the layer, and becomes light loss due to light absorption in the GaN-based semiconductor layer 100 and light absorption by the electrode member. On the other hand, when the glass member 11 is attached to the surface of the n-GaN layer 13, the critical angle with respect to the interface 1A of the glass member 11 is a range indicated by an arrow n = 2.0 (56 degrees with respect to the interface direction). It becomes. Thereby, light absorption in the GaN-based semiconductor layer 100 can be reduced, and light emission efficiency can be improved.

(Manufacturing process of LED element 1)
FIG. 2 is a diagram showing a manufacturing process of the LED element. Below, the manufacturing process of the LED element 1 is demonstrated.

(Board preparation process)
FIG. 2A is a diagram illustrating a substrate preparation process. First, a wafer-like sapphire substrate 10 serving as a base substrate is prepared.

(Buffer layer forming process)
FIG. 2B is a diagram showing a buffer layer forming process on the sapphire substrate. An AlN buffer layer 12 is formed on the surface of the sapphire substrate 10.

(Semiconductor layer formation process)
FIG. 2C is a diagram showing a process for forming a GaN-based semiconductor layer. An n-GaN layer 13, a light emitting layer 14, and a p-GaN layer 15 are sequentially provided on the AlN buffer layer 12, and then removed from the p-GaN layer 15 to the n-GaN layer 13 by etching. -The GaN layer 13 is exposed.

(Lift-off process)
FIG. 2D is a diagram showing a lift-off process between the sapphire substrate and the GaN-based semiconductor layer. A sapphire substrate 10 on which the GaN-based semiconductor layer 100 shown in FIG. 2C is laminated is irradiated with a laser beam from the sapphire substrate 10 side over the entire surface of the wafer. The laser beam irradiated here has a wavelength that passes through the sapphire substrate and does not pass through the GaN-based semiconductor layer 100. Based on such irradiation of the laser beam, the interface between the sapphire substrate 10 and the n-GaN layer 13 is locally heated, and as a result, the sapphire substrate 10 that is the formation substrate is peeled off from the n-GaN layer 13. Here, the AlN buffer layer 12 remaining on the n-GaN layer 13 side is removed based on acid cleaning.

(Glass preparation process)
FIG.2 (e) is a figure which shows the glass preparation process which prepares the glass member heat-sealed to the GaN-type semiconductor layer from which the sapphire substrate was peeled. With respect to the GaN-based semiconductor layer 100 in which the sapphire substrate 10 is lifted off in FIG. 2E, a glass member 11 with n = 2.0 is disposed on the n-GaN layer 13 side.

(Glass crimping process)
FIG. 2 (f) is a diagram showing a glass crimping process for thermally fusing a glass member to the n-GaN layer 13. The glass member 11 is heat-sealed by being hot pressed onto the n-GaN layer 13.

(Electrode formation process)
FIG. 2G is a diagram showing an electrode forming process for forming an electrode. An n-electrode 16 is formed as a first electrode on the n-GaN layer 13 exposed by etching, and a p-electrode 18 is formed as a second electrode on the p-GaN layer 15. After the electrodes are formed, each LED element 1 is cut with a dicer, and an insulating film (not shown) is formed on the surface excluding the electrodes. In addition, cutting | disconnection of the LED element 1 can also be performed by methods other than the cutting | disconnection by a dicer, for example, scribe.

  In order to form an LED lamp using the LED element 1 formed as described above, first, the LED element 1 is mounted on a ceramic substrate provided with a wiring pattern via Au bumps. Next, the LED element 1 is integrally sealed with a sealing resin to be packaged.

(Operation of LED element 1)
When the wiring pattern of the LED lamp is connected to a power supply unit (not shown) and energized, a forward voltage is applied to the n-electrode 16 and the p-electrode 18 through the wiring pattern, and holes and electrons are generated in the light emitting layer 14. Carrier recombination occurs to emit light. Of the blue light generated based on this light emission, the blue light emitted from the light emitting layer 14 toward the glass member 11 enters the sealing resin through the glass member 11 and is radiated from the sealing resin to the outside.

  Further, the blue light emitted from the light emitting layer 14 toward the p-GaN layer 15 is reflected by the p-electrode 18 and guided toward the glass member 11. Here, the light within the critical angle range of the glass member 11 is transmitted through the glass member 11 and is emitted to the outside of the LED element 1.

  The light that reaches the glass member 11 is radiated to the outside with high efficiency. That is, in FIG. 1, the glass member 11 and each GaN layer are drawn to have the same thickness for the sake of explanation, but in reality, the glass member 11 is about 100 microns, whereas the GaN layer 13 + light emitting layer. The 14 + p-GaN layer 15 has a thickness of several microns, and the light confined in the GaN is significantly attenuated by intra-layer absorption and electrode member absorption. On the other hand, the light reaching the glass member can be ignored by the glass member 11, and the critical angle between the sealing resin (n = 1.5) and the glass member 11 is about 50 degrees. Light that is not emitted externally is emitted externally from the side. Similarly, in the case of other interface reflections, external radiation is emitted within two interface reflections. And since the glass member 11 has sufficient thickness, the probability of such 2 degree interface reflection is high.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(1) Since the sapphire substrate is lifted off from the n-GaN layer 13 of the LED element 1 and the glass member 11 having a refractive index higher than that of the sapphire substrate is bonded to the n-GaN layer 13, the inside of the layer confined in the GaN layer The blue light emitted outside can be increased by reducing the confinement light, and as a result, the light extraction performance can be improved. When the sapphire substrate 10 is used, the critical angle θc based on the refractive index ratio with the n-GaN layer 13 is 1.7 (sapphire) /2.4 (GaN): θc = 45 degrees. When the glass member 11 with a rate n = 2.0 is used, θc is 56 degrees, so the solid angle of the opening angle is increased by 52%, and the blue light that can be transmitted to the glass member 11 is increased by about 50%. . For this reason, external radiation can be promoted without keeping blue light in a layer having a large light absorption coefficient.

(2) Since the sapphire substrate 10 is lifted off from the n-GaN layer 13 with a laser beam and the glass member 11 which is a transmissive material is integrated, an LED corresponding to the emission wavelength and desired light extraction performance The element 1 can be easily formed.

(3) Since a heat-deformable glass material as a permeable material is heat-sealed by hot pressing, it has excellent adhesion to the n-GaN layer 13 and can be easily joined. In addition, since the thermal expansion coefficients are made equal, it is possible to prevent cracks and large warpage from occurring after heat fusion.

(Second Embodiment)
(Configuration of LED element 1)
FIG. 3 is a longitudinal sectional view of an LED element according to the second embodiment. The flip-chip type LED element 1 is different from the first embodiment in a configuration in which a phosphor-containing glass member 11B containing a phosphor is provided instead of the glass member 11 described in the first embodiment. ing.

  In the phosphor-containing glass member 11B, for example, YAG: Ce phosphor particles that are excited by blue light and emit yellow light can be used as the phosphor. Moreover, a fluorescent complex can be used as another fluorescent substance.

(Effect of the second embodiment)
According to the second embodiment, by using the phosphor-containing glass member 11B containing a phosphor in a glass member having a high refractive index, the phosphor reaches a phosphor as compared with a material having a phosphor outside the high refractive index material. The amount of light can be increased, and the amount of light that can be wavelength-converted can be increased. In addition, the wavelength-converted light (yellow light) by the phosphor is much smaller than the blue light in both GaN layer absorption and electrode absorption. For this reason, the wavelength conversion type LED element 1 which is excellent in light extraction property and radiates white light having no color unevenness based on good excitation of the phosphor is obtained.

(Third embodiment)
(Configuration of LED element 1)
FIG. 4 is a longitudinal sectional view of an LED element according to the third embodiment. In this flip-chip type LED element 1, a flat glass member 11 is thermally fused to the n-GaN layer 13 described in the first embodiment, and a fine uneven portion 11C is provided on the light extraction surface. This configuration is different from the first embodiment.

  The concavo-convex shape portion 11 </ b> C is transferred by the concavo-convex provided in a mold for hot pressing the glass member 11 onto the n-GaN layer 13. The uneven shape can be formed by a method other than transfer, and the glass member 11 on which the uneven shape has been formed in advance may be integrated with the n-GaN layer 13 by hot pressing.

(Effect of the third embodiment)
According to the third embodiment, the glass member 11 bonded to the n-GaN layer 13 is provided with the fine uneven portion 11C on the light extraction surface. The light extraction property of blue light on the surface can be improved.

(Fourth embodiment)
(Configuration of LED element 1)
FIGS. 5A to 5C are diagrams showing an LED element according to the fourth embodiment, and FIG.
(B) is a top view which shows the external shape and cutting part of (a), (c) is a figure which shows the light which injects into a cut part. This flip-chip type LED element 1 is provided with a cut portion 110 in which the corner of the glass member 11 of the LED element 1 described in the first embodiment is cut at 45 degrees to enhance the light extraction property of blue light. This configuration is different from the first embodiment.

  The cut part 110 is formed by cutting a corner of the glass member 11 after the LED element 1 is cut out. Further, when the LED element 1 is cut out, a V-shaped cut may be formed based on cutting with a dicer or the like, and an inclined surface may be formed by dividing the cut at the bottom of the cut. The shape of the corner cut portion is not limited to a 45 degree cut by a flat surface, but may be a cut other than 45 degrees or a cut shape by a convex surface.

  FIG. 5B is a plan view of the LED element 1. The LED element 1 emits light in the light emitting layer 14 in the region where the p-electrode 18 is provided, and emits blue light to the outside via the glass member 11.

5 (c) is a diagram showing the transmission in the glass member 11 of the blue light L _B generated in the light emitting layer. Of the blue light L _B generated in the light emitting layer 14, by the approach the normal incidence at a cut portion 110 also light Not radiated in the 45-degree direction by the blue light L _B emitted to the upper surface direction, Prevents optical loss due to interface reflection.

(Effect of the fourth embodiment)
According to the fourth embodiment, by providing the cut portion 110 in which the corner portion of the glass member 11 is cut at 45 degrees, the blue light incident on the glass member 11 can be taken out more efficiently and light emission. Efficiency can be improved. Moreover, since the edge is not an acute angle, such as when the LED element 1 is sealed with a hard member, there is an advantage that cracks hardly occur.

(Fifth embodiment)
(Configuration of LED element 1)
FIG. 6 is a longitudinal sectional view of an LED element according to the fifth embodiment. This flip-chip type LED element 1 has the p-electrode 18 of the LED element 1 described in the fourth embodiment disposed at the center of the element, and an upper surface of a glass member 11 having an optical shape formed by a curved surface. The fourth embodiment is different from the fourth embodiment in the configuration in which the blue light is perpendicularly incident to the first embodiment.

(Effect of 5th Embodiment)
According to the fifth embodiment, in addition to the preferable effects of the fourth embodiment, the light distribution of the blue light emitted from the light emitting layer 14 is based on the arrangement of the p-electrode 18 and the shape of the glass member 11. It is possible to control by setting. However, in order to obtain the lens effect by refraction, it is necessary to set the refractive index of the glass member 11 having a significant difference from the refractive index of the sealing material of the LED element. For this reason, a refractive index of n = 1.7 or more is desirable.

In the fifth embodiment, the structure in which the glass having an optical shape is provided on the n-GaN layer 13 has been described. However, for example, the refractive index is equivalent to that of the light emitting layer 14 such as TiO ₂ , SiC, or GaN. A substrate may be attached. As a result, the light propagating in the GaN layer direction can be brought to the side surface without being affected by a layer having a high absorption rate such as the light emitting layer 14, and high external radiation efficiency can be obtained.

  In particular, if there is a substrate thickness of 1/5 or more of the LED element size, it will be sufficiently significant for externally radiating GaN layer propagation light having an angle of about 90 ° with respect to the central axis of the LED element 1. be able to.

  In addition, since the LED element 1 is a flip chip type, the surface on which the sapphire substrate is lifted off selects a substrate for improving the light extraction efficiency without restrictions such as electrical restrictions and lattice constant matching for epitaxial growth. It becomes possible.

(Sixth embodiment)
(Configuration of LED element 1)
FIG. 7 is a longitudinal sectional view of an LED element according to the sixth embodiment. The flip-chip type LED element 1 is different from the first embodiment in the configuration in which the fine uneven portion 1B is provided at the interface between the glass member 11 and the n-GaN layer 13 described in the first embodiment. is doing.

  The uneven portion 1B is formed by roughening the n-GaN layer 13 obtained by lifting off the sapphire substrate, and the glass member 11 is integrated by hot pressing the glass member 11 on the uneven portion 1B.

(Effect of 6th Embodiment)
According to the sixth embodiment, the glass member 11 can be made to correspond to the shape of the GaN layer, which is an epitaxially grown semiconductor layer provided with fine irregularities at the interface, by reducing the viscosity by hot pressing. . In the first embodiment, as shown in FIG. 1B, the light incident on the interface at an angle direction of 56 degrees or more with respect to the interface direction causes total reflection and does not enter the glass member 11, but the glass member. By providing the concavo-convex portion 1B at the interface between the n-GaN layer 13 and the n-GaN layer 13, in-layer confinement light in the n-GaN layer 13 is also incident on the interface within a critical angle within the critical angle. The amount of light reaching the glass member 11 can be increased. Thereby, external radiation efficiency can be improved.

(Seventh embodiment)
(Configuration of LED element 1)
FIGS. 8A to 8C are diagrams showing LED elements according to the seventh embodiment. The flip-chip type LED element 1 is different from the first embodiment in the configuration in which the concave portion 13A is provided at the interface between the glass member 11 and the n-GaN layer 13 described in the first embodiment. . The recess 13A formed in the n-GaN layer 13 has a substantially columnar shape, and the inclined surface of the recess 13A is formed at an angle substantially parallel to the center axis A in the figure.

(Effect of 7th Embodiment)
According to the seventh embodiment, by providing the substantially columnar recess 13A at the interface between the glass member 11 and the n-GaN layer 13, the confinement light in the layer in the n-GaN layer 13 is applied to the glass member 11. The extractability is further improved, and the external radiation efficiency of blue light can be increased. That is, when the interface between the n-GaN layer 13 and the glass member 11 is a random rough surface from the flat surface without particular consideration, the direction in which the n-GaN layer 13 can be incident on the glass member 11 is a flat surface. Thus, part of the light reaching the interface cannot enter the glass member 11 because the angle of the interface changes. However, the light emitted from the n-GaN layer 13 of the LED element 1 shown in FIG. 1A to the glass member 11 is emitted with the same efficiency as a, b, and c in FIG. 8C. Further, when the interface with the glass member 11 is flat as shown in FIG. 1A, the light that has not been emitted to the glass member 11 due to total reflection due to the refractive index difference between the glass member 11 and the n-GaN layer 13 is also obtained. , D. The light emitted to the glass member 11 as shown in c is effective light to the glass member 11 if the critical angle is 45 degrees or 50 degrees or more in two dimensions as shown in FIG. It becomes radiation. If the critical angle is 45 degrees or more, light can be emitted to the glass member 11 within 2 degrees of incidence on the interface, and if it is 50 degrees or more, the Fresnel reflection can be set to an angle that is not large, so that further efficiency can be obtained. Can do. In three dimensions, depending on the column shape, if the rectangular shape is as shown in FIG. 8, if the critical angle is 55 degrees or 60 degrees or more, light emission to the glass member 11 is performed within 3 degrees of interface incidence. it can. By using the glass member 11 having a high refractive index, the glass member 11 satisfying this can be approached or close to this.

  In addition, although the recessed part 13A was demonstrated as what formed the groove | channel which continued to the side surface on the GaN side, it is good also as what formed the dot-shaped groove | channel on the GaN side. However, in order to bond the GaN layer 13 and the glass member 11 satisfactorily without residual bubbles, it is preferable to perform continuous groove formation. Moreover, as shown in FIG. 5, the glass member 11 may be subjected to a corner cut or a phosphor-containing glass may be used.

(Eighth embodiment)
(Configuration of LED element 1)
FIG. 9 is a longitudinal sectional view of an LED element according to the eighth embodiment. In the following description, parts having the same configuration and function as those of the first embodiment are denoted by common reference numerals. This LED element 1 is a face-up type LED element in which a milky white glass member 11A having a refractive index n = 2.0 is provided instead of the glass member 11 described in the first embodiment. This is different from the first embodiment.

(Effect of 8th Embodiment)
According to the eighth embodiment, the in-layer confinement light propagating in the n-GaN layer 13 is diffused by the milky white glass member 11A, so that the light extraction property is improved. In addition, there is an effect that the member that mounts the LED element 1 is not affected by light absorption. The Ag paste, the organic adhesive, or the like has a problem that the LED element 1 is deteriorated by light or heat emitted from the LED element 1, and the light absorption degree is increased. However, this can be avoided. In this way, not only the flip type but also a face up type may be used.

In the first to eighth embodiments, the LED element having the semiconductor layer made of GaN has been described. However, other materials such as GaAs and AlInGaP may be used. Moreover, although it demonstrated as what lifted off the sapphire substrate 10, if a semiconductor layer and a board | substrate are the same refractive index, it is not necessary to remove a board | substrate. Further, _Bi 2 _{O 3} based material has been described as a glass member having a refractive index 2.0, _SiO 2 _-Nb 2 _{O 5} system is not limited to _Bi 2 _{O 3 system,} other materials such as SiO 2 _-B 2 _{O 3} It may be. Further, if the refractive index is higher than that of the LED element sealing material or the semiconductor growth substrate, the effect of improving the light extraction efficiency can be obtained. For example, an epoxy resin having a refractive index n = 1.5 is generally used as an LED element sealing material. However, if a glass member 11 having a refractive index n = 1.6 or more is attached to GaAs or AlInGaP, an effect is obtained. be able to. In the case of GaN grown on a sapphire substrate (refractive index n = 1.7) 10, an effect can be obtained by adhering a refractive index material higher than the substrate to the semiconductor layer. When the light transmittance of the substrate itself is high, it is necessary to use a refractive index material higher than that of the substrate. Of course, even with GaAs or AlInGaP, the glass member 11 having a refractive index n = 1.7 or more can provide a greater effect.

  Further, the high refractive index material layer provided on the light extraction side may be made of a material other than the glass described above, and may be a high refractive index material layer made of resin, for example. Moreover, it is also possible to comprise other inorganic materials that enhance light extraction from the GaN-based semiconductor layer 100.

(Ninth embodiment)
FIG. 10 is a cross-sectional view showing an LED element according to the ninth embodiment. As described in the first embodiment, the flip-chip type LED element 1 has a thin high refractive index made of an inorganic material on the surface of the n-GaN layer 13 exposed by lifting off the sapphire substrate. The material layer 19 is provided.

The high refractive index material layer 19 is formed to have a film thickness of 1 μm on the surface of the n-GaN layer 13 by heating and vaporizing tantalum oxide (Ta ₂ O ₅ ) as a raw material by electron beam evaporation. Ta ₂ O ₅ has a refractive index n = 2.2, and the critical angle θc based on the refractive index ratio with the n-GaN layer 13 is 66 °. A rough surface portion 19A based on an electron beam evaporation method is formed on the surface of the high refractive index material layer 19 on the light extraction side.

(Effect of 9th Embodiment)
According to the ninth embodiment, by providing the high refractive index material layer 19 made of Ta ₂ O ₅ with n = 2.2 on the surface of the n-GaN layer 13, the solid angle can be expanded. . Further, since the rough surface portion 19A is formed when Ta ₂ O ₅ is recrystallized on the surface of the n-GaN layer 13 during the Ta ₂ O ₅ film formation, random incidence at the interface between the LED element 1 and the outside is performed. An angle can be given, and the light extraction efficiency is improved.

The high refractive index material layer 19 may be formed of a material other than Ta ₂ O ₅ , for example, ZnS (n = 2.4), SiC (n = 2.4), HfO ₂ (N = 2.0), ITO (n = 2.0), or GaN may be used. These film-forming materials may not be conductive materials, and may be any material that has excellent adhesion and optical characteristics.

(Tenth embodiment)
FIG. 11 is a cross-sectional view showing an LED element according to the tenth embodiment. This flip-chip type LED element 1 has a configuration in which a glass member 11 of n = 1.75 is bonded to the surface of the high refractive index material layer 19 of the LED element 1 described in the ninth embodiment. .

(Effect of 10th Embodiment)
According to the tenth embodiment, the light incident on the high refractive index material layer 19 from the n-GaN layer 13 is diffused at the interface with the glass member 11, and the external radiation is further enhanced. This is in addition to the rough surface portion 19A of the high refractive index material layer 19 made of _Ta 2 _{O 5,} the critical angle θc when emitted from the _Ta 2 _{O 5} becomes large by through the glass member 11, n- This is because the emission efficiency from the GaN layer 13 to the high refractive index material layer 19 can be increased.

(Eleventh embodiment)
FIG. 12 is a sectional view showing an LED element according to the eleventh embodiment. The flip-chip type LED element 1 includes an ITO contact electrode 20 having a thermal expansion coefficient of 7.7 × 10 ⁻⁶ / ° C. instead of the p-electrode 18 of the LED element 1 described in the ninth embodiment. The bonding pad 21 including the Al layer 21A and the Au layer 21B is provided.

(Effect of 11th Embodiment)
According to the eleventh embodiment, since the ITO contact electrode 20 having a thermal expansion coefficient substantially equal to that of the GaN-based semiconductor layer 100 is provided in addition to the preferable effects of the ninth embodiment, the adhesion of the p-side electrode is increased. As a result, the LED element 1 with high reliability that does not cause the p-side electrode to peel off due to heat generated by the sealing process of the LED element 1 or heat generated due to light emission can be obtained. In addition, unevenness in light emission can be reduced based on the current diffusivity of ITO.

(Twelfth embodiment)
FIGS. 13A and 13B show an LED element according to a twelfth embodiment, where FIG. 13A is a plan view of the LED element, and FIG. 13B is a cross-sectional view taken along the line AA in FIG. is there. The flip-chip type LED element 1 has a predetermined width and depth as shown in FIG. 13A with respect to the n-GaN layer 13 of the LED element 1 described in the eleventh embodiment. The groove-like recesses 13A are provided in a lattice shape, and a high refractive index material layer 19 is provided on the surface thereof as shown in FIG.

(Effect of 12th Embodiment)
According to the twelfth embodiment, in addition to the preferable effects of the eleventh embodiment, the light-extracting surface is enlarged by providing the groove-like recesses 13A in a lattice shape, and light having a plane and a vertical plane is provided. The light extraction property is enhanced by providing the extraction surface. Further, since the high refractive index material layer 19 having the rough surface portion 19A is provided on the surface of the n-GaN layer 13, the propagation light confined in the n-GaN layer 13 is externally emitted from the groove-shaped recess 13A before reaching the side surface. In this case, the critical angle is widened by the high refractive index material layer 19. For this reason, the LED element 1 excellent in external radiation is obtained.

(Thirteenth embodiment)
FIG. 14 is a sectional view showing an LED element according to the thirteenth embodiment. This flip-chip type LED element 1 has a configuration in which a glass member 11 of n = 1.75 is attached to the surface of the high refractive index material layer 19 of the LED element 1 described in the twelfth embodiment.

(Effect of 13th Embodiment)
According to the thirteenth embodiment, in addition to the preferable effects of the twelfth embodiment, the light incident on the high refractive index material layer 19 from the n-GaN layer 13 is randomly incident at the interface with the glass member 11. However, since the critical angle at that time can be increased, the external radiation can be further increased.

(Fourteenth embodiment)
FIG. 15 is a sectional view showing an LED element according to the fourteenth embodiment. This flip-chip type LED element 1 has a configuration in which a cut portion 110 having an inclination of 45 ° is provided at the end of the glass member 11 of the LED element 1 described in the thirteenth embodiment.

(Effect of 14th Embodiment)
According to the fourteenth embodiment, in addition to the preferable effects of the thirteenth embodiment, light that propagates laterally through the glass member 11 is emitted from the cut portion 110 to the outside, thereby further improving the light extraction performance. be able to.

(A) And (b) is the LED element which concerns on 1st Embodiment, (a) is a longitudinal cross-sectional view, (b) is explanatory drawing which shows a critical angle. It is a figure which shows the manufacturing process of an LED element, (a) is a figure which shows a board | substrate preparation process, (b) is a figure which shows the buffer layer formation process to a sapphire substrate, (c) is a figure of a GaN-type semiconductor layer. The figure which shows a formation process, (d) is a figure which shows the lift-off process of a sapphire substrate and a GaN-type semiconductor layer, (e) is a glass member heat-sealed to the GaN-type semiconductor layer from which the sapphire substrate was peeled off. The figure which shows the glass preparatory process to prepare, (f) is a figure which shows the glass crimping | compression-bonding process which heat-seal | fuses a glass member to an n-GaN layer, (g) is a figure which shows the electrode formation process which forms an electrode. . It is a longitudinal cross-sectional view of the LED element which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view of the LED element which concerns on 3rd Embodiment. (A)-(c) is a figure which shows the LED element which concerns on 4th Embodiment, (a) is a longitudinal cross-sectional view, (b) is a top view which shows the external shape and cutting part of (a), (C) is a figure which shows the light which injects into a cut part. It is a longitudinal cross-sectional view of the LED element which concerns on 5th Embodiment. It is a longitudinal cross-sectional view of the LED element which concerns on 6th Embodiment. It is a figure which shows the LED element which concerns on 7th Embodiment. It is a longitudinal cross-sectional view of the LED element which concerns on 8th Embodiment. It is sectional drawing which shows the LED element which concerns on 9th Embodiment. It is sectional drawing which shows the LED element which concerns on 10th Embodiment. It is sectional drawing which shows the LED element which concerns on 11th Embodiment. (A) And (b) shows the LED element which concerns on 12th Embodiment, (a) is a top view of an LED element, (b) is sectional drawing in the AA part of (a). It is sectional drawing which shows the LED element which concerns on 13th Embodiment. It is sectional drawing which shows the LED element which concerns on 14th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LED element, 1A ... Interface, 1B ... Uneven part, 10 ... Sapphire substrate, 11 ... Glass member, 11A ... Milky white glass member, 11B ... Phosphor containing glass member, 11C ... Uneven shape part, 12 ... Buffer layer, 13 ... n-GaN layer, 13A ... recess, 14 ... light emitting layer, 15 ... p-GaN layer, 16 ... n-electrode, 18 ... p-electrode, 19 ... high refractive index material layer, 19A ... rough surface part, 20 ... ITO Contact electrode, 21 ... bonding pad, 21A ... Al layer, 21B ... Au layer, 100 ... GaN-based semiconductor layer, 110 ... cut portion

Claims (15)

In a flip chip type light emitting element having a semiconductor layer including a light emitting layer and provided with first and second electrodes on the mounting surface side,
A light-emitting element comprising: a light-transmitting high-refractive-index material layer having a refractive index n = 1.6 or more provided on the light emitting surface side of the semiconductor layer.   The light-emitting element according to claim 1, wherein the translucent high-refractive-index material layer has an uneven rough surface portion on a surface.   2. The light emitting device according to claim 1, wherein the semiconductor layer is obtained by removing a formation substrate, and the light transmissive high refractive index material layer has a thickness of 1/5 or more of the width of the light emitting device.   2. The light-emitting element according to claim 1, wherein the translucent high refractive index material layer includes a first layer in contact with the semiconductor layer and a second layer stacked on the first layer. A semiconductor layer including a light emitting layer;
A light-transmitting high-refractive-index material layer having a refractive index of n = 1.6 or more attached to the semiconductor layer, and the light-transmitting high-refractive index material layer is made of glass.   6. The light emitting element according to claim 1, wherein the semiconductor layer is formed by removing a formation substrate.   The light emitting device according to claim 4, wherein the light transmissive high refractive index material layer includes a phosphor.   The light-emitting element according to claim 5, wherein the translucent high-refractive-index material layer has a concavo-convex shape portion on a surface thereof.   6. The light emitting device according to claim 5, wherein the translucent high refractive index material layer has a corner cut shape.   10. The light-emitting element according to claim 5, further comprising an uneven portion at an interface between the semiconductor layer and the translucent high refractive index material layer.   The light emitting device according to claim 10, wherein the uneven portion has a columnar shape.   The semiconductor layer is a GaN-based semiconductor layer formed on a sapphire substrate based on crystal growth, and the translucent high refractive index material layer has a refractive index n = 1.7 or more. The light emitting device according to claim 3.   The light emitting device according to claim 7, wherein the phosphor is a fluorescent complex or a particulate phosphor. A substrate preparation step of preparing a base substrate;
A semiconductor layer forming step of forming a semiconductor layer on the base substrate;
A lift-off step of lifting off the base substrate from the semiconductor layer;
A translucent high refractive index material layer forming step of providing a translucent high refractive index material layer on the base substrate mounting side of the semiconductor layer lifted off the base substrate;
An electrode formation step of forming an electrode on the semiconductor layer provided with the light-transmitting high refractive index material layer.   The method of manufacturing a light emitting element according to claim 14, wherein the semiconductor layer forming step forms a GaN-based semiconductor layer as the semiconductor layer on a sapphire substrate as the base substrate.

Images