WO2011126094A1 - Semiconductor light emitting device - Google Patents

Abstract

Disclosed is a semiconductor light emitting device wherein light extraction from a chip which outputs light mainly in the horizontal direction can be utilized to a maximum extent. The semiconductor light emitting device has the semiconductor light emitting element, a case section, and a sealing material. The semiconductor light emitting element has a substrate, a semiconductor layer section, and an electrode section, and the element has a maximum physical thickness of t_emax as a whole. The case section has a recessed section for housing the semiconductor light emitting element, and the depth (D_p) to the element mounting surface of the recessed section satisfies the inequality of t_emax<D_p. The semiconductor light emitting element is mounted such that the opening direction of the recessed section and the direction of the substrate main surface substantially match, and the sealing material is formed to have a protruding portion in the direction which the substrate main surface faces. When the semiconductor light emitting device is viewed in air from the direction perpendicular to the direction which the substrate main surface faces, at least a part of the side wall of the semiconductor light emitting element can be viewed through the protruding portion.

Description

Semiconductor light emitting device

The present invention relates to a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device that can make maximum use of light extraction of a chip that mainly emits light in a lateral direction.

Blue light-emitting elements and ultraviolet light-emitting elements can be used as white light sources in combination with appropriate wavelength conversion materials. Such white light sources have been extensively studied for application as backlights for liquid crystal displays, light-emitting diode illumination, automotive lighting, or general lighting instead of fluorescent lamps, and some of them have already been put into practical use. ing.

At present, such a light emitting element is mainly realized by a semiconductor light emitting element (LED). A semiconductor light emitting device (hereinafter sometimes simply referred to as “light emitting device”) is usually realized by a GaN-based material formed on a sapphire substrate. Among them, the mainstream is that the planar shape projected from the main surface direction of the substrate is substantially square. Moreover, since the light emitting element which has the AlGaInN type | system | group semiconductor layer part formed on the sapphire substrate is a sapphire board | substrate very hard material, since element isolation | separation is not easy, the thickness of the sapphire substrate inherent in a light emitting element The mainstream is about 100 μm.

On the other hand, attempts have been made to increase the output and efficiency of light-emitting elements by epitaxially growing an AlGaInN-based semiconductor layer on a nitride substrate such as GaN or AlN to reduce the dislocation density in the semiconductor layer. Attempts have also been made to improve the light extraction efficiency by devising the light emitting element structure.

Conventionally disclosed methods for improving light extraction efficiency in semiconductor light-emitting devices mainly formed on GaN substrates include the following. For example, a device of a light emitting element structure for efficiently extracting light from a light emitting layer in a normal direction (vertical direction) is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2006-1000078). Here, in order to efficiently extract light in the normal direction from the light emitting layer, the surface of the LED element, that is, the back surface of the substrate or the semiconductor layer exposed by peeling off the substrate is subjected to a predetermined optical shape to be refracted. The predetermined optical shape is formed on a substrate having a refractive index substantially equal to that of the light emitting layer of the LED element or a semiconductor layer peeled and exposed. A light emitting device is disclosed. Further, here, the substrate is made transparent so that light can be extracted in the normal direction of the light emitting layer, where n1 is the refractive index of the light emitting layer of the LED element, n2 is the refractive index of the sealing material, and w is the element width. As the material layer (thickness t), the t is w / (2 tan (sin ⁻¹ (n1 / n2))) ≦ t
A light emitting element satisfying the above requirements is disclosed.

Japanese Laid-Open Patent Publication No. 2006-100787

However, in the means of Patent Document 1, the intrinsic high output and high efficiency of a light emitting device having an AlGaInN-based semiconductor layer on a nitride substrate such as GaN or AlN have not been sufficient. That is, in Patent Document 1, the back surface of the substrate or the semiconductor layer exposed by peeling the substrate is sealed with a sealing material having a refractive index of 1.6 or more, and the light extraction efficiency in the vertical direction of the active layer is improved. Attempts are essentially not sufficient for the following reasons. That is, as will be described later, the present inventors have found that a light emitting element having an AlGaInN-based semiconductor layer portion on a substrate has a direction in which the internal emission intensity is strong in a direction close to the parallel direction of the active layer structure. It was. For example, in the case where the substrate is formed of nitride and the difference in refractive index between the semiconductor layer portion such as the active layer and the substrate is not large, there is a method for taking out light from the side wall surface of the active layer light emitting element and improving the efficiency. And found it to be an essentially superior method. For this reason, the attempt of Patent Document 1 to improve the light extraction efficiency in the vertical direction of the active layer is essentially compared to a method of efficiently extracting internal light emitted in a direction close to the parallel direction of the active layer. It was not enough.

As described above, the inventors have found that the method of taking out light from the side wall surface of the light emitting element and improving the efficiency is an essentially excellent method (details will be described later). In order to extract light from such a new semiconductor light emitting device more efficiently and in a state where the characteristic light distribution characteristics are utilized, or to apply these to a light source for illumination with a higher degree of processing, conventionally The general mold shape is not sufficient, and a specific mold shape is required.

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a semiconductor light emitting device that can make maximum use of light extraction and light distribution characteristics of a chip that mainly emits light in a lateral direction. There is.

As a result of intensive studies, the present inventors have found that in a light emitting device having an AlGaInN-based semiconductor layer portion on a substrate, there is a direction in which the internal emission intensity density is strong in a direction close to the parallel direction of the active layer structure. For example, when the substrate is a nitride substrate, further a GaN substrate, an AlN substrate, an AlGaN substrate, etc., the semiconductor layer portion is made of an AlGaInN system, and the refractive index difference between the active layer and the substrate is not large, light emission It has been found that the method of taking out light from the side wall surface of the device and improving the efficiency is an essentially excellent method. Furthermore, it has been found that a physical thickness of the substrate that greatly exceeds the technical common sense of those skilled in the art is required to improve the light extraction efficiency from the wall surface. The semiconductor light emitting device of the present invention capable of efficiently extracting light from such a semiconductor light emitting element and making use of characteristic light distribution characteristics is as follows.

That is, the gist of the present invention is as follows.
1. A semiconductor light emitting device having a semiconductor light emitting element, a case portion for mounting the semiconductor light emitting element, and a sealing material,
The semiconductor light emitting device has a substrate, a semiconductor layer portion including an active layer structure that emits light, and an electrode portion, and the maximum physical thickness of the entire semiconductor light emitting device is _temax ,
The case portion has a recess for enclosing the semiconductor light emitting element, and a depth D _{p of the} recess to the semiconductor light emitting element mounting surface satisfies t _emax <D _p ,
The sealing material is disposed in contact with at least a part of the semiconductor light emitting element and a part of the case part,
The semiconductor light emitting element is mounted such that the opening direction of the concave portion of the case portion and the direction in which the substrate main surface faces are substantially the same direction,
The sealing material is formed so as to have a convex portion with respect to the direction in which the main surface of the substrate faces.
When the semiconductor light emitting device is viewed in the air in a direction perpendicular to the direction in which the main surface of the substrate faces, at least a part of the side wall of the semiconductor light emitting element through the convex portion of the sealing material A semiconductor light emitting device that can be visually recognized.

1 above. “Visible” means that the semiconductor light-emitting element in the semiconductor light-emitting device can be visually recognized by the light refraction effect brought about by the sealing material. In other words, this “visible” includes (i) a state in which the sealing material is transparent and the semiconductor light-emitting element inside can actually be seen, and (ii) a phosphor or the like is contained in the sealing material. Actually, the internal semiconductor light emitting device cannot be seen, but if the phosphor or the like is not contained, both the state where the internal semiconductor light emitting device can be seen are included. In addition, in order to define the visibility, it is also important in what surrounding refractive index environment the semiconductor light emitting device is installed, but here, it is a common-sense environment at room temperature and atmospheric pressure. It is assumed that visibility is easily confirmed, and the refractive index at this time is approximately 1, which is the same refractive index environment as that in vacuum.

The semiconductor light emitting device of the present invention may be as follows.
-The semiconductor light-emitting device in which the said case part is comprised from the single package component.
The semiconductor light-emitting device in which the case portion includes at least a submount that is positioned directly below the semiconductor light-emitting element and a package component that is positioned directly below the submount.
A semiconductor light emitting device having one or more of a reflector and a phosphor in the recess of the case portion.

-The semiconductor light-emitting device which has one recessed part of the said case part, Comprising: The said semiconductor light-emitting element mounted in the said recessed part is one.
A semiconductor light emitting device in which the case portion has two or more recesses, and each of the semiconductor light emitting elements mounted in each recess is one.
-The semiconductor light-emitting device which has one recessed part of the said case part, Comprising: The said semiconductor light-emitting element mounted in the said recessed part is 2 or more.
A semiconductor light emitting device having two or more concave portions of the case portion and two or more semiconductor light emitting elements mounted in at least one of the concave portions.

2. The semiconductor maximum physical thickness t _t of the substrate and the semiconductor layer portion light emitting element is 150μm or more, the semiconductor light-emitting device according to claim 1.

3. 3. The semiconductor light emitting device according to 1 or 2, wherein the substrate satisfies the following formula 1.
Formula 1
L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}
(However,
λ represents the peak wavelength (nm) of light emitted from the semiconductor light emitting device,
t _s represents the maximum physical thickness of the substrate;
L _sc represents the longest line segment length formed by any two points on the main surface of the substrate;
n _s (λ) represents the refractive index of the substrate at the wavelength λ. )

4). The semiconductor light emitting element is
The light emitting element is in an arbitrary plane perpendicular to the main surface of the substrate in which the light emitting element is present, and the direction to be the light extraction direction is 0 degree, and one direction parallel to the main surface is 90 degrees, opposite to the 90 degree direction. When the light distribution characteristics are measured in a state where the direction is set to −90 degrees, the light emitting element is installed in the air, and there is effectively no disturbance,
From the direction φ _{em max} indicating the maximum value of the external light emission intensity density, the direction θ _{em max} indicating the maximum value of the internal light emission intensity density inside the semiconductor light emitting element obtained using Snell's law is at least one of the following expressions: 4. The semiconductor light-emitting device according to any one of 1 to 3, wherein a plane that satisfies one of the planes exists.
−90.0 degrees <θ _{em max} ≦ −67.5 degrees 67.5 degrees ≦ θ _{em max} <90.0 degrees

5. The semiconductor light emitting element is
The light emitting element is in an arbitrary plane perpendicular to the main surface of the substrate in which the light emitting element is present, and the direction to be the light extraction direction is 0 degree, and one direction parallel to the main surface is 90 degrees, opposite to the 90 degree direction. When the light distribution characteristics are measured in a state where the direction is set to -90 degrees, the element is installed in the air, and there is effectively no disturbance,
There is a plane having a light distribution characteristic in which the direction φ _{em max} indicating the maximum value of the external emission intensity density emitted from the light emitting element satisfies at least one of the following formulas: The semiconductor light-emitting device of any one of Claims.

−90.0 degrees <φ _{em max} ≦ −32.5 degrees 32.5 degrees ≦ φ _{em max} <90.0 degrees

6). 6. The semiconductor light emitting device according to any one of 1 to 5, wherein the substrate is made of nitride.

7). The depth D _p of the concave portion of the case portion to the semiconductor light emitting element mounting surface is
500 μm ≦ D _p ≦ 5 mm
7. The semiconductor light-emitting device according to any one of 1 to 6 above.

8). The physical height of the convex portion formed by the sealing material with respect to the opening direction of the concave portion of the case portion is formed in a convex shape from the case portion and from a direction perpendicular to the direction in which the substrate main surface faces. It is defined as the physical height X _{ph of the} encapsulant part that can be expected,
Let X _{op be the} optical height corresponding to this,
The peak wavelength of light emitted from the semiconductor light emitting element is λ (nm),
When the refractive index at the wavelength λ of the sealing material is n _m (λ),
8. The semiconductor light emitting device according to any one of 1 to 7, which satisfies any of the following formulas.
800 (μm) ≦ X _ph ≦ 1900 (μm) Equation 2
1040 (μm) ≦ X _op ≦ 3420 (μm) Equation 3
1.3 ≦ n _m (λ) ≦ 1.8 Equation 4

A semiconductor light emitting device that satisfies all of the equations 2 to 4.

9. When the semiconductor light emitting device is observed from the opening direction of the recess of the case portion in the air in the semiconductor light emitting device,
9. The physical length a of an arbitrary portion of the projected shape of the semiconductor light emitting element, and the visually recognized length b of the corresponding portion satisfies the following relationship: Semiconductor light emitting device.
1 ≦ b / a <1.25

10. 10. A light emitting module comprising the semiconductor light emitting device according to any one of 1 to 9 above and a phosphor layer including a phosphor that emits fluorescence when excited by light emitted from the semiconductor light emitting element. The light emitting module which a layer is arrange | positioned so that it may space apart from the said convex part and may cover the said convex part.

According to the present invention, it is possible to provide a semiconductor light emitting device capable of making maximum use of the light extraction and light distribution characteristics of a chip that mainly emits light in the lateral direction.

FIG. 1A is a cross-sectional view showing an example of a semiconductor light emitting device of the present invention. FIG. 1B is a simplified view of the semiconductor light emitting element portion of the apparatus of FIG. 1A. FIGS. 2A and 2B are side views showing a state in which the semiconductor light emitting device installed in the air is viewed from the horizontal direction. 3A and 3B show the physical length of an arbitrary portion of the semiconductor light emitting element and the length when the semiconductor light emitting device installed in the air is viewed through the encapsulant when viewed from the vertical direction. It is an example which shows the relationship with the visually recognized length of the part corresponding to thickness, FIG.3 (a) is the length of the arbitrary parts of a semiconductor light-emitting device, FIG.3 (b) is when it sees through a sealing material. Length. FIG. 4A is a cross-sectional view schematically showing the structure of the semiconductor light emitting device of one embodiment of the present invention. FIG. 4B is a diagram illustrating a quantum well layer and a barrier layer. FIG. 5A is a model for obtaining an internal light emission profile. FIG. 5B is a diagram for explaining the internal light emission profile. FIG. 5C is a diagram for explaining the internal light emission profile. FIG. 6A is a perspective view schematically showing a geometric shape of the semiconductor light emitting device. 6B is a side view of FIG. 6A. FIG. 6C is a diagram illustrating the behavior of light. FIG. 6D is a diagram illustrating the behavior of light. FIG. 6E is a diagram illustrating the behavior of light. FIG. 7A is a diagram schematically illustrating a geometric shape of a semiconductor light emitting device having a square planar shape. FIG. 7B is a diagram schematically showing a geometric shape of a hexagonal semiconductor light emitting device. FIG. 8A is a diagram for explaining an external light emission profile and the like. FIG. 8B is a diagram for explaining the farthest side wall portion inclined at an angle β. FIG. 9A is a simulation graph showing an internal light emission profile when the thickness of the second conductivity type semiconductor layer is changed in the range of 0 to 150 nm. FIG. 9B is a simulation graph showing an internal light emission profile when the thickness of the second conductivity type semiconductor layer is changed in the range of 150 to 500 nm. FIG. 10A is a graph showing characteristics of the semiconductor light-emitting device manufactured in Example 1. FIG. 10B is a graph showing characteristics of the semiconductor light emitting device manufactured in Example 2. FIG. 10C (a) is a table showing the mold rising rate in Example 1, and FIG. 10C (b) is a table showing the mold rising rate in Example 2. FIG. 11 shows the experimental results showing the light distribution characteristics of the single semiconductor light emitting device used in Example 1. FIG. 12 shows the experimental results showing the light distribution characteristics of the light-emitting devices prototyped in Example 1 and Comparative Example 1. FIG. 13 is a simulation result showing the light distribution characteristics of a white light-emitting module including the light-emitting device prototyped in Example 1 and Comparative Example 1 and a phosphor molded body. FIG. 14 is a simulation result showing the light distribution characteristics of a white light-emitting module including the light-emitting device prototyped in Example 1 and Comparative Example 1 and a phosphor molded body.

[Semiconductor light-emitting device]
FIG. 1A is a cross-sectional view showing an example of a semiconductor light emitting device of the present invention. First, a basic configuration of a semiconductor light emitting device which is an example of the present invention will be described.

As shown in FIG. 1A, the semiconductor light emitting device 1 includes a side emission type semiconductor light emitting element 10 (details will be described later) in which main light extraction is performed from the side wall of the light emitting element when the semiconductor light emitting element itself is installed in the air. is doing. The semiconductor light emitting device 1 includes, for example, a semiconductor light emitting element 10 that is flip-chip mounted, a package component 103 in which a recess for mounting the semiconductor light emitting element 10 is formed, and a sealing material 106 that covers the light emitting element 10. ing.

The package component 103 is formed with a recess 104 formed to a depth enough to accommodate the entire semiconductor light emitting element 10. In the recess 104, the semiconductor light emitting element 10 is electrically connected to the submount 101 via solder or bumps 102a and 102b in a face-down state. In the example of FIG. 1A, the submount 101 is connected to a package component 103 having printed wiring.

Each part of the semiconductor light emitting device 10 will be described in detail again. The semiconductor light emitting device 10 includes a substrate 12, a semiconductor layer portion 15, and an electrode portion. As an example, the maximum physical thickness t _t excluding the electrode portion (details will be described later with reference to FIG. 6A) is preferably 150 μm or more, more preferably 250 μm or more, and 350 μm or more. More preferably, it is more preferably 450 μm or more, particularly preferably 650 μm or more, and most preferably 800 μm or more. In addition, the generic name of the first conductivity type side electrode 27a and the second conductivity type side electrode 27b is an electrode part, and the maximum physical thickness of the entire semiconductor light emitting element including the substrate 12, the semiconductor layer part 15, and the electrode part is t _emax ( (See FIGS. 1A, 1B, and 4A).

The depth D _p (see FIG. 1A) of the recess 104 to the semiconductor light emitting element mounting surface is preferably in the range of 500 μm ≦ D _p ≦ 5 mm. When the depth D _p of the recessed portion 104 is shallower than 500 [mu] m, depending on the thickness of the semiconductor light emitting element 10 becomes the top of the light-emitting element protrudes upwardly from the recess, it may become difficult to achieve a proper sealing material shape . On the other hand, if the depth D _p of the recessed portion 104 is more than 5 mm, the size of the packaging component (thickness) in size, is not preferable from the viewpoint of production cost.

The “semiconductor light-emitting element mounting surface” refers to the surface on which the semiconductor light-emitting element is mounted, and refers to the contact surface between the bump and the electrode unit when the semiconductor light-emitting element is connected to the submount via the bump. . In addition, when the semiconductor light emitting element is directly connected to the bottom of the package component via solder or the like, the contact surface between the solder material and the electrode portion is indicated. That is, the semiconductor light emitting element mounting surface can be understood as a contact surface with the electrode portion.

In the present invention, between the maximum physical thickness t _{emax of the} entire semiconductor light emitting element, that is, the substrate, the semiconductor layer part, and the entire electrode part, and the depth D _p to the semiconductor light emitting element mounting surface, t _emax <D _p holds true. This has the following important implications.

In the present invention, when the mold is formed with a sealing material or the like, that is, when the semiconductor light emitting element and the package member are integrated, when viewed from a direction perpendicular to the direction in which the main surface of the substrate faces. The semiconductor light emitting element is not visible at all. In such a situation, any viscous sealing material can be easily dropped / applied to appropriate portions of the semiconductor light emitting device and the package member. In other words, if the semiconductor light emitting device is visible from the direction perpendicular to the direction in which the main surface of the substrate faces before molding, the semiconductor is particularly used when a low-viscosity sealing material or the like is used. A part or all of the light emitting element is exposed, and an appropriate mold cannot be formed. For this, it is important that t _emax <D _p .

On the other hand, when t _emax <D _p , the light emitted from the semiconductor light emitting element mainly at an angle close to the horizontal direction tends to be shielded by the side wall portion of the package member or the like. Thus, it is important to control the mold shape. That is, when the semiconductor light-emitting device after molding is viewed from the direction perpendicular to the direction in which the main surface of the substrate faces in the air, the semiconductor light-emitting element of the semiconductor light-emitting element passes through the convex portion of the sealing material. It is important that at least a part of the side wall is visible.

The recess 104 has a planar (one example) package component bottom surface 105b and a package component side wall 105a (in this case, an inclined wall inclined) rising from the outer periphery of the package component bottom surface 105b. The shape of the package component side wall 105a is designed so that the internal light emission profile of the semiconductor light emitting device 10 having the maximum value of the internal light emission intensity density in the direction parallel to the active layer structure 16 (details below) can be used effectively. Yes. As an example, a reflective material may be used for the package component side wall 105a.

The detailed structure of the semiconductor light emitting device 10 will be described again with reference to another drawing. As shown in FIG. 1A, the semiconductor light emitting device 10 includes the first conductivity type side electrode 27a and the second conductivity type side. Each of the electrodes 27b is mounted on the submount 101 via solder or bumps 102a and 102b made of a conductive material.

The recess 104 is filled with a sealing material 106 and covers the semiconductor light emitting element 10. As an example, the sealing material 106 is provided from the viewpoint of improving the light extraction efficiency of the semiconductor light emitting device 10. As the material, as will be described in detail later, it is preferable to use one or more of a silicone-based sealing material, a high refractive index silicone composition sealing material, and a glass sealing material. The encapsulant may contain one or more phosphors for the purpose of converting the wavelength of the semiconductor light emitting device.

In the present specification, as shown in FIG. 1A, the package component 103 in which the submount 101 or solder material, bumps or the like are provided as necessary is referred to as a “case part”. The “case part” may be configured by a single package component 103 without the submount 101 or the like.

In FIG. 1A, an example in which a semiconductor light emitting element is mounted in a flip chip type structure is depicted, but for example, the semiconductor light emitting element may be mounted in a face-up type or a vertical conduction type structure.

In the semiconductor light emitting device 1 of the present embodiment, as shown in FIGS. 1A and 1B, the sealing material 106 is formed so as to rise from the upper surface of the package component 103, and the upper surface of the sealing material 106 is a curved surface. ing. That is, the sealing material 106 is formed to have a convex portion with respect to the opening direction of the concave portion 104.

Specifically, when the semiconductor light emitting device 1 is viewed from a direction perpendicular to the direction in which the main surface of the substrate faces, for example, in the air, as shown in FIG. By the action of refracting light, at least a part of the side wall of the internal semiconductor light emitting element 10 is formed to be visually recognized.

If the height of the sealing material 106 is too low or too high, the internal semiconductor light emitting element 10 cannot be visually recognized. For example, when the sealing material 106 is simply formed in a hemispherical shape (example) as shown in FIG. 2B, the semiconductor light emitting element 10 is not visually recognized from the horizontal direction. This is because the height of the sealing material is too high when the refractive index sealing material (described later in detail) used in the present invention is formed as shown in FIG. 2B. As described above, when the height of the sealing material is too high, the light from the semiconductor light emitting element 10 can be extracted very efficiently, but the light emitting device can be obtained by the lens effect due to the shape of the sealing material. The light distribution characteristics of the semiconductor light emitting device are greatly different from those of the semiconductor light emitting device. For example, when a light-emitting device having a hemispherical sealing material is configured using a semiconductor light-emitting element having a relatively wide light distribution characteristic with a light emission intensity from the side wall being stronger than the substrate main surface as described later, Most of the light emitted from the side wall of the semiconductor light emitting element is bent in the direction in which the main surface of the substrate faces when emitted from the sealing material, resulting in a light emitting device having a relatively narrow light distribution characteristic (this) Will be described later with reference to FIG. 12 as an example). As described above, if the side wall of the semiconductor light emitting element 10 is not visible, even if a semiconductor light emitting element having a characteristic light distribution characteristic is used, a light emitting device utilizing the light distribution characteristic is obtained. It is not possible.

On the other hand, by adopting a configuration in which at least a part of the side wall of the semiconductor light emitting element 10 can be visually recognized as in this embodiment, light from the side emission type semiconductor light emitting element 10 to be described later is very efficiently obtained. And it becomes possible to take out in the state which utilized the characteristic light distribution characteristic. Specifically, when the light-emitting device of the present invention is configured using a semiconductor light-emitting element whose emission intensity from the side wall is stronger than the main surface of the substrate, which will be described later, the light distribution characteristic derived from the semiconductor light-emitting element is utilized. Thus, a light emitting device having a relatively wide light distribution characteristic can be obtained.

As an example, the physical height X _ph of the convex portion of the sealing material 106 is preferably in the range as follows. This result is a result of repeating various experiments using a side emission type semiconductor light emitting device.

800 (μm) ≦ X _ph ≦ 1900 (μm)
Here, “physical height X _ph ” refers to the height from the upper surface of the package component 103 to the top of the convex portion of the sealing material 106 as shown in FIG. 1A.

The optical height X _op of the sealing material 106 is preferably in the following range.

1040 (μm) ≦ X _op ≦ 3420 (μm)
Here, “optical height X _op ” refers to a value obtained by multiplying the physical height X _ph by the refractive index _nm (λ) of the sealing material 106. Note that λ is a peak wavelength (nm) of light emitted from the semiconductor light emitting element.

The specific material, refractive index, etc. of the sealing material 106 will be described later again.

FIGS. 3A and 3B show the physical length a of an arbitrary portion of the semiconductor light emitting element 10 (in this example, one side of the outer periphery of the element) and the semiconductor light emitting device in the air, for example, in a sealing material. FIG. 10 is a plan view showing a relationship with a visually recognized length b of a portion corresponding to a length a when viewed through 106. FIG. 3A shows only the semiconductor light emitting element 10, and FIG. 3B shows a state where the semiconductor light emitting element 10 is viewed through the sealing material 106. These lengths a and b preferably satisfy the following relationship.

Preferably, 1 ≦ b / a <1.25
More preferably, 1 ≦ b / a <1.15
More preferably, 1 ≦ b / a <1.10
Particularly preferably, 1 ≦ b / a <1.08
Most preferably, 1 ≦ b / a <1.05

In FIGS. 3A and 3B, the vertical direction is the direction perpendicular to the paper surface. 3A and 3B, the horizontal direction is indicated by the up and down arrows, but any direction in the plane of the paper is the horizontal direction. Note that “vertical direction” is synonymous with “direction in which the main surface of the substrate is facing”, and “horizontal direction” is synonymous with “direction perpendicular to the direction in which the main surface of the substrate is facing”.

In the case where the above relationship is satisfied, the light emitted from the side wall of the semiconductor light emitting element can be relatively less internally reflected by the elements constituting the semiconductor light emitting device such as the encapsulant, the package component, and the submount. Since internal reflection basically loses radiant energy whenever reflection is repeated, it is basically not preferable. In the case of satisfying the aforementioned b / a relationship, the light emitted from the side wall of the semiconductor light emitting element is relatively easy and does not depend only on the vertical direction of the sealing material of the semiconductor light emitting device, and the horizontal direction of the sealing material. Direct emission is possible from a direction close to the direction, which is very preferable.

In the semiconductor light emitting device 1, as described above, the light emitted from the side wall of the semiconductor light emitting element is preferable because it can be emitted directly from the direction close to the horizontal direction of the sealing material relatively easily. In addition to this, it is further preferable that a package component or the like is configured to improve the light extraction efficiency while effectively using an external light emission profile (described later in detail) in the sealing material of the semiconductor light emitting element 10. . For example, the inclination angle of the package component side wall 105a of the recess 104 is set so as to effectively extract light of a component that cannot be directly emitted from a direction close to the horizontal direction in light extraction in a direction nearly parallel to the active layer structure. It is preferable that the semiconductor light emitting device is designed so that light in the direction of high external light emission intensity density can be extracted to the outside.

Further, for example, for the purpose of effective excitation of the phosphor by light emission of the semiconductor light emitting device 10, it is preferable that the phosphor is arranged in a direction in which the external light emission intensity density of the semiconductor light emitting device is relatively high. . Specifically, a step of intentionally precipitating the phosphor in the step of curing the sealing material is provided so that the phosphor is distributed in a region near the bottom of the recess 104 of the package component. It is done.

Further, a phosphor layer including a phosphor that emits fluorescence when excited by light emitted from the semiconductor light emitting element may be provided on the convex portion of the semiconductor light emitting device to constitute a light emitting module. In order to take advantage of the relatively wide light distribution characteristics of the semiconductor light emitting device, it is preferable to configure the light emitting module by providing the phosphor layer so as to be spaced apart from and cover the convex portion of the semiconductor light emitting device. .

Further, among the light emitted from the side wall of the semiconductor light emitting element, the light from the semiconductor light emitting element 10 is applied to, for example, the package component bottom surface 105b of the recess 104 with respect to a component that cannot be emitted directly from the direction close to the horizontal direction. One or more reflectors and phosphors may be provided that reflect the light toward the concave opening side (upward in the figure). According to such a configuration, the light from the semiconductor light emitting element 10 can be emitted more favorably to the concave opening side.

Next, each part will be described in detail.
[1] Semiconductor Light Emitting Element The semiconductor light emitting element used in the semiconductor light emitting device of the present invention is a semiconductor light emitting element having a semiconductor layer portion on the main surface of a substrate. The substrate is preferably a nitride, and more preferably a single crystal such as GaN, AlN, or AlGaN. Specifically, the semiconductor light-emitting device mainly has the following requirements (1) to (3) having a specific relationship.
(1) Peak emission wavelength λ of a semiconductor light emitting device
(2) maximum physical thickness t _s or a sum t _t of the maximum physical thickness t _L of the maximum physical thickness t _s and a semiconductor layer portion of the _substrate, the substrate
(3) The longest line segment length L _{sc formed by} any two points on the substrate main surface

This semiconductor light emitting device is a side emission type device with improved lateral light extraction efficiency. As a result of satisfying the specific relationship regarding the above (1) to (3), the substrate thickness with respect to the length of L _sc becomes a shape having a substrate having a physical thickness that greatly exceeds the technical common knowledge of those skilled in the art. As a result, it is possible to improve the efficiency of extracting light from the side wall surface of the light emitting element and to realize a large total radiant flux or a total luminous flux as an absolute value, and as a result, it is possible to achieve high output and high efficiency. it can.

The planar shape of the semiconductor light emitting element may be a triangle, a quadrangle, or an m-gon (m is an integer of 5 or more). As for the square, a different part will be supplementarily described.

As described later, the main structural requirements of such a semiconductor light emitting element are supported by a technical idea that utilizes the natural law clarified by the present inventors. Hereinafter, the natural law used in the semiconductor light emitting device and the technical idea (constituent requirement of the present invention) using the same will be described in detail, and a preferred embodiment of the present invention will be described in detail as an example.

[1-1] Overview of Semiconductor Light Emitting Element FIG. 4A shows an example of a semiconductor light emitting element. The semiconductor light emitting device 10 includes a nitride substrate 12, a semiconductor layer portion 15 formed on the surface, and an electrode portion including a first conductivity type side electrode 27a and a second conductivity type side electrode 27b. Nitride substrate 12, when a peak emission wavelength of the light emitting element and a lambda, a refractive index of n _{s (lambda)} at the wavelength lambda, the maximum physical thickness of t _s.

The semiconductor layer portion 15 has an active layer structure 16 that can constitute a light emitting element. The semiconductor layer portion 15 preferably has one or both of the first conductivity type semiconductor layer 17 and the second conductivity type semiconductor layer 18. Any one or both of the first conductivity type semiconductor layer and the second conductivity type semiconductor layer can arbitrarily include layers having various functions such as a contact layer and a carrier overflow suppression layer.

Hereinafter, the refractive index at a wavelength λ of an arbitrary layer X constituting the semiconductor layer portion is described as n _LX (λ), and the maximum physical thickness of the semiconductor layer portion is described as t _L. A substrate surface on which the semiconductor layer portion 15 is formed is expressed as a main surface 21. The Z axis is taken in a direction perpendicular to the main surface 21, and this direction is set to 0 degrees in the directions of internal light emission and external light emission described later (see FIG. 4A). The maximum physical thickness from the main surface 21 to the substrate side interface of the active layer structure 16 and t _a.

The “side wall portion (side wall surface)” of the semiconductor light emitting device is used when referring to both the substrate side wall portion (side wall surface) and the semiconductor layer side wall portion (side wall surface).
The “exposed surface” also indicates a main surface, a surface (12a) facing the main surface, a wall surface, for example, a surface exposed when the substrate is processed, a processed sidewall surface of the semiconductor layer portion 15, and the like. The surface which becomes a boundary with the surrounding medium of a semiconductor light-emitting device. Usually, a plurality of semiconductor light emitting elements 10 are formed on one substrate during the manufacturing process, and a surface formed by separation from adjacent elements at this time is sometimes referred to as a “separation surface”. As a result, the separation surface may become an exposed surface. “Exposed surface formation” means to form an exposed surface by an arbitrary method and an arbitrary form. In particular, the nuance for increasing the amount of light entering the critical angle at the interface and increasing the light extraction efficiency is indicated. Sometimes it is used.
“Concavity and convexity processing” refers to forming concavities and convexities by an arbitrary method and an arbitrary form, and in particular, it may be used with a nuance for increasing the light scattering effect.

As shown in FIG. 4B, the active layer structure 16 that the semiconductor light emitting element 10 can optionally have is preferably a quantum well active layer structure having a quantum well layer 31 and a barrier layer 33.

[1-2] Natural laws used in semiconductor light emitting devices and technical ideas using them [How to derive natural laws related to internal light emission profiles of semiconductor light emitting devices]
As shown in FIG. 4A, the semiconductor light emitting device 10 is provided with an electrode portion having a first conductivity type side electrode 27a and a second conductivity type side electrode 27b. Electrons and holes injected from these electrodes 27 a and 27 b are recombined in the active layer structure 16, for example, in the quantum well active layer if the structure is a quantum well active layer, and light is emitted into the semiconductor light emitting device 10. To do.

Since the electrodes 27a and 27b have a certain degree of reflection, the angular distribution of the emission intensity density in the semiconductor light emitting device 10 is strongly dependent on the optical interference effect. This angular distribution of the light emission intensity density is called an internal light emission profile in the present invention, and is obtained as follows.

Assume an infinitely wide XY plane and a Z axis perpendicular to it. It is assumed that each quantum well layer portion in the multiple quantum well layer extending in the XY plane direction and substantially parallel to the substrate main surface 21 is a planar set of electric dipoles (dipole plane). In the dipole plane, the dipole orientation is uniform in all directions. The light emitted from the dipole is multiplexed in each layer of the semiconductor layer portion (multiple quantum well layer portion, second conductivity type side semiconductor layer, second conductivity type side electrode, etc.) and electrode portion in the semiconductor light emitting device 10. Subjected to reflection and multiple interference. As a result, the emission intensity density J _in inside the light emitting device 10 is dependent on the radiation direction (the Z axis direction is 0 degree and the angle between the radiation direction and the Z axis direction is expressed as θ _em ). Become.

The internal light emission profile refers to the dependence of the light emission intensity density (J _in ) inside the semiconductor light emitting element on the radiation direction (θ _em ).

The angle that defines the internal light emitting direction includes an angle (azimuth angle) that the projection of the light emitting direction onto the XY plane makes with the X axis direction, in addition to the angle θ _{em made} with the Z axis direction. However, since the direction of the dipole is isotropic, it may be considered that the emission intensity density J _in does not depend on the azimuth angle.

By the way, in the studies made in the design of the semiconductor light emitting device, the light emitted from the active layer portion of the semiconductor light emitting device is “isotropic internal light emission profile”, that is, J _in is constant _in any θ _em . Assuming that there is, inventions and the like have been made on the shape and layer configuration of the semiconductor light emitting device.

However, as a result of studies by the present inventors, it has been found that these inventions and the like are based on an erroneous internal light emission profile. And in the conventional examination, it discovered that there was not sufficient effect in high output and high efficiency of a semiconductor light emitting element. That is, it is the dipole orientation that should be isotropic, and the resulting internal emission profile in the radial direction is not isotropic and is anisotropic.

Considering light emission from a dipole surface (dipole orientation isotropic) existing at a distance d from the electrode in a half space consisting of a flat plate electrode and one uniform medium, the internal light emission profile is Can be described as follows.

here,
I ₀ : Radiation intensity from dipole r _s : Amplitude reflection coefficient in reflection of electrode surface of s-polarized light r _p : Amplitude reflection coefficient in reflection of electrode surface of p-polarization δ: 2πnd / λ
n: Refractive index at wavelength λ in a region where a dipole surface exists d: Physical distance λ between dipole surface and electrode: Peak wavelength of semiconductor light emitting device.

Further, when considering multiple reflection and multiple interference in the multiple quantum well layer, multiple reflection and multiple interference between various phases constituting the semiconductor layer portion 15, J _in can be calculated using the characteristic matrix method. preferable.

FIG. 5A shows an example of a model used for obtaining the internal light emission profile of this semiconductor light emitting element. Here, it is assumed that the active layer structure in the semiconductor light emitting device 10 is a quantum well active layer structure. As shown in FIG. 5A, the quantum well layer 31, that is, the dipole surface, is present at a distance d from the barrier layer 33 and the second conductivity type semiconductor layer 18 to the second conductivity type electrode 27b. .

The light emitted from a certain dipole becomes anisotropic due to the interference effect with itself, but the lights emitted from different dipoles do not interfere with each other, and the overall internal emission intensity density Is the sum of the internal emission intensity densities of each anisotropic light. When the light emitting layers are present at different distances d, the direction in which the internal emission intensity from the dipole in each light emitting layer increases and the direction in which they weaken may cancel each other, but according to the study of the present invention, For example, by having a quantum well active layer structure that satisfies (Formula A), which will be described later, as a result of always strengthening in a specific direction, that is, a direction close to a direction parallel to the active layer structure, It was found that an internal emission intensity density distribution having a maximum value in a specific direction was obtained.

[It has an isotropic orientation assuming that there is an appropriate refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer and the light emitting layer has an appropriate thickness. (Anisotropic internal light emission profile by dipole radiation)
It is assumed that an appropriate refractive index difference exists between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer, and has, for example, a quantum well active layer structure that satisfies (Formula A) described later. Such a structure is a structure that can be actually realized. When the internal emission profile from the dipole radiation having an isotropic orientation is calculated, typically, as shown in FIG. 5B (the angle θ _em where the horizontal axis is the Z-axis direction and the vertical axis is the internal emission intensity density J _in ). Such a characteristic, that is, an anisotropic internal light emission profile is obtained.

As shown in FIG. 4A, although there are variations depending on conditions such as the thickness of the second conductivity type semiconductor layer 18 and the reflectance of the second conductivity type side electrode 27b, the direction showing the maximum value of the internal emission intensity density is the active layer. The direction is close to the direction parallel to the structure (the direction in which θ _em is close to 90 °). Such a tendency that the internal emission intensity density increases in a direction nearly parallel to the active layer structure becomes more conspicuous in, for example, a light-emitting element having a quantum well active layer structure that satisfies (Formula A) described later.

FIG. 5B shows that the internal emission profile from dipole radiation with an isotropic orientation becomes essentially anisotropic. That is, assuming that there is an appropriate refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer and the light emitting layer has an appropriate thickness, the following natural law is can get.
“There is an appropriate refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer. For example, when the quantum well active layer structure satisfies the following (formula A), isotropic Dipolar radiation with a different orientation results in an anisotropic internal emission profile, and the internal emission intensity density increases in a direction close to parallel to the active layer structure. "

[Isotropic orientation when assuming that there is an excessive refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer or the light emitting layer has an excessive thickness, etc. Isotropic internal emission profile due to dipole radiation
As mentioned above, the internal emission profile from dipole radiation with an isotropic orientation is essentially anisotropic, but the refraction between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer. When the rate difference becomes larger than an appropriate range, or when the light emitting layer is thicker than an appropriate range, the degree is as shown in FIG. As illustrated in the order of (b) and line (c), the intensity of the light emitted internally in a direction close to the direction parallel to the active layer structure is weakened. It looks like the middle line (d).

When the refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer increases, the light emitted in the direction near the parallel to the active layer structure is reflected more strongly, and as a result of multiple reflection, Absorbed by electrodes with finite reflectivity. Further, when the thickness of the light emitting layer is increased, light emitted in a direction nearly parallel to the active layer structure is canceled out in the sum of light emission from the respective dipoles. As a result, when the refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer increases beyond an appropriate range, or when the light emitting layer has an excessive thickness, etc. The following natural law is obtained.

Isotropic when the difference in refractive index between the quantum well layer, barrier layer, and second conductivity type semiconductor layer increases beyond an appropriate range or when the light emitting layer has an excessive thickness. A dipole radiation with a different orientation results in an isotropic internal emission profile.

[1-3] Preferred Embodiment of Semiconductor Light-Emitting Element As described above, this semiconductor light-emitting element has an appropriate refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer, or the light-emitting layer. Is preferable when it has an appropriate thickness. The active layer structure preferably has a quantum well active layer structure, whereby an internal light emission profile can be realized that is anisotropic with a maximum value of internal light emission intensity density in a direction parallel to the active layer structure.

According to detailed examinations by the present inventors, such an active layer structure can be realized, for example, by appropriately selecting a difference in refractive index between the quantum well layer and the barrier layer. In addition, it can be realized by appropriately selecting the number of repetitions of the quantum well layer and the barrier layer, or appropriately selecting the thicknesses of the quantum well layer and the barrier layer.

Although these numerical values are related to each other, the following can be mentioned as preferable realization means. First, in relation to the quantum well active layer structure and the second conductivity type semiconductor layer, it is preferable to satisfy the following formula A.

here,
NUM _QW represents the number of quantum well layers included in the active layer structure,
T _QW (nm) represents the average physical thickness of the layers constituting the quantum well layer,
NUM _BR represents the number of barrier layers included in the active layer structure,
T _BR (nm) represents the average physical thickness of the layers constituting the barrier layer,
T _P (nm) represents the physical thickness of the second conductivity type semiconductor layer,
n _QW (λ) represents the average refractive index at the wavelength λ of the layers constituting the quantum well layer,
n _BR (λ) represents an average refractive index at a wavelength λ of a layer constituting the barrier layer,
n _P (λ) represents the average refractive index of the second conductivity type semiconductor layer at the wavelength λ,
n _s (λ) represents the refractive index at the wavelength λ of the substrate as described above.

Second, the number of quantum well layers is preferably 4 or more and 30 or less.

Third, it is preferable that the thickness of the quantum well layer included in the active layer structure is 40 nm or less.

These were obtained as a result of various studies, and a quantum well layer having a relatively large refractive index strongly reflects light emitted in a direction nearly parallel to the active layer structure, and causes absorption by the electrodes. It is considered that this is not a condition. By satisfying these conditions, it is feasible in practice and has an emission direction of high-density light in a direction parallel to the active layer structure in consideration of confinement of electron-hole pairs in the quantum well layer. A layer structure can be realized.

[It has an isotropic orientation assuming that there is an appropriate refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer and the light emitting layer has an appropriate thickness. Details of having an anisotropic internal emission profile due to dipole radiation)
As shown in FIG. 5B, the semiconductor light emitting device is anisotropic in the internal light emission profile, and has a characteristic that the maximum value of the internal light emission intensity density is close to the direction parallel to the active layer structure. That is, it is preferable that the emission intensity density distribution with respect to the internal emission direction (θ _em ) of the semiconductor light emitting device is not isotropic.

Here, in the internal light emitting direction (θ _em ) of the semiconductor light emitting element 10, the direction (θ _{em max} ) having the maximum value is a direction close to the parallel direction of the active layer structure. The direction (θ _{em max} ) giving the maximum value of internal light emission varies depending on the material constituting the semiconductor layer portion, the structure of each layer, the electrode material, and the structure thereof.

Specifically, the direction (θ _{em max} ) giving the maximum value of internal light emission includes the first conductivity type semiconductor layer constituting the semiconductor layer portion, the active layer structure including the quantum well active layer and the barrier layer, and the second conductivity type. It varies depending on the semiconductor layer, the contact layer, various structures that can be arbitrarily introduced, the constituent material of the first conductivity type side electrode, the constituent material of the second conductivity type side electrode, the structure thereof, and the like.

Furthermore, θ _{em max} can be most strongly changed by the reflection effect due to the refractive index difference between the quantum well layer, the barrier layer, and the second conductivity type semiconductor layer, and different dipoles from the light emitting layer having a certain thickness. This is the effect of canceling the anisotropy as a result of the addition of the light emission due to.

Therefore, as a result of examining these conditions in the semiconductor layer on the nitride substrate 12, the following was found. That is, in the case of having an anisotropic internal light emission profile, the direction (θ _{em max} ) for giving the maximum value of internal light emission is
It can be changed in the range of 67.5 degrees ≦ θ _{em max} <90 degrees. This is simultaneously −90 degrees <θ _{em max} ≦ −67.5 degrees.

As a result, the present inventors have found the following. That is, in order to efficiently extract light emitted from the active layer structure 16 of the semiconductor layer portion 15 of FIG. 4A into the semiconductor light emitting element, the extraction efficiency of high-density light toward the vicinity of the θ _{em max} direction is improved. It is essential and effective. Such a method is more essential and effective than the conventional method, that is, the method of improving the extraction efficiency of light emitted internally in the direction of θ _em = 0 degrees.

Furthermore, the present inventors have found the following. That is, it is more effective to extract the light emitted in such a direction from the side wall surface than to extract from the “upper surface (surface 12 a facing the substrate main surface in FIG. 4A)” of the semiconductor light emitting element 10.

Furthermore, as a result of various studies, the present inventors have found the following. That is, the angle (θ _{em max} ) indicating the maximum value of the internal light emission intensity density emitted from the active layer structure 16 of the semiconductor light emitting device 10 to the inside of the semiconductor light emitting device has a lower limit of the absolute value of 67.5 degrees or more. It is preferably 70.0 degrees or more, more preferably 72.5 degrees or more, and particularly preferably 75.0 degrees or more.

Furthermore, the upper limit of the absolute value of θ _{em max} is preferably smaller than 90 degrees, more preferably 87.5 degrees or less, further preferably 85.0 degrees or less, and 82.5 degrees or less. It is particularly preferred. This is because the internal light emission direction is advantageous for extracting light from the side wall of the semiconductor light emitting device.

That is, in order to improve the light extraction efficiency of the semiconductor light emitting device 10, light mainly extracted from the side surface of the light emitting device is mainly light in the direction in which the light is emitted at a high density internally. It is an essential and effective method for improving efficiency. This is a conclusion that cannot be reached from the isotropic internal light emission profile disclosed heretofore.

Here, when the active layer structure has a quantum well structure and the refractive index difference between the quantum well layer and the barrier layer is small within an appropriate range, the light emitted internally from the active layer structure 16 is 67.5 degrees ≦ Since θ _{em max} <90 degrees, the side wall of the semiconductor light emitting element 10 can be reached. Further, when the refractive index difference at the interface of the semiconductor layer constituting the active layer structure 16 and the other semiconductor layer portion is small in an appropriate range, the refractive index difference at the interface between the semiconductor layer portion and the nitride substrate is also in an appropriate range. The same is true for small cases. Therefore, it is most effective to extract the light emitted internally from the active layer structure 16 from here.

[External light emission profile]
As a comprehensive result of light reflection, transmission, refraction, and the like at the interface between the internal light emission profile and the peripheral medium of the semiconductor light emitting element, an external light emission profile, that is, a light distribution characteristic is determined according to Snell's law.

The “external light emission profile” is a distribution of the emission intensity density (J _out ) outside the semiconductor light emitting element in the radiation direction (φ _em ). That is, θ _{em max} cannot be observed directly, but by observing the (φ _{em max} ) direction indicating the maximum value of the emission intensity density (J _out ) outside the semiconductor light emitting element, It is possible to obtain by calculating backward from the law of.

For this purpose, in order to measure the light distribution characteristics of semiconductor light emitting elements with high accuracy, the light distribution characteristics are measured in the air by mounting the light emitting elements on a stem or the like that eliminates the portion that can be a reflecting mirror as much as possible. It is preferable to do. In other words, when discussing the light distribution characteristics as the characteristics of a single element, measure by mounting the light-emitting element on a stem or the like where the element is placed in the air and the portion that can be a reflecting mirror as described above is eliminated as much as possible. Is preferred.

On the other hand, the external light emission profile of the semiconductor light emitting device is, for example, a semiconductor light emitting device sealed with a sealing material having a refractive index of 1.42, and the direction of light emitted into the sealing material is the refraction around the device. It is possible to calculate by using Snell's law with a rate of 1.42. Specifically, when the external light emission profile is measured by installing the device in the air, the internal light emission profile of the semiconductor light emitting device can be known. By using this internal light emission profile, a peripheral medium having an arbitrary refractive index is obtained. The external light emission profile of the semiconductor light emitting element in the medium emitted into the medium can be known.

[Derivation of required substrate thickness by critical angle at farthest side wall]
As an example, the semiconductor light emitting device will be described by taking a case where a nitride substrate is projected in a direction perpendicular to the main surface of the substrate in a substantially triangular shape. In addition, one of the features is that a specific relationship is satisfied between the longest line segment length formed by any two points on the substrate main surface and the maximum physical thickness of the nitride substrate.

FIG. 6A is a perspective view schematically showing the geometric shape of the semiconductor light emitting device.

As shown in FIG. 6A, the semiconductor light emitting device 10 has a semiconductor layer portion 15 including an active layer structure 16 that emits light having a peak emission wavelength λ on the main surface (lower side of the drawing) of the nitride substrate 12. is doing. In the example of FIG. 6A, when the nitride substrate 12 is projected in a direction perpendicular to the substrate main surface 21, the shape is substantially triangular. Further, since all of the side wall surfaces are perpendicular to the substrate main surface 21, the projection shape of the nitride substrate 12 matches the planar shape of the substrate main surface 21, and the main surface also has a substantially triangular shape. . In this case, the shape projected in the vertical direction on the main surface of the substrate generally matches the shape of the adjacent element isolation end. Further, as will be described later, when the main surface is processed in the example in which the wall surface is processed, the planar shape of the substrate main surface 21 is smaller than the shape of the substrate projected perpendicularly to the substrate main surface. There is a case. In this case, the main surface shape of the substrate may be substantially triangular (however, smaller than the shape in which the substrate is projected in the vertical direction on the main surface of the substrate). 4 or a natural number of 100 or less), a circular shape, an elliptical shape, an indefinite shape surrounded by a curve, an indefinite shape surrounded by a straight line and a curve, or the like.

Here, the longest line segment length formed by any two points on the main surface of the substrate is L _sc, and the refractive index at the wavelength λ of the substrate is n _s (λ). The semiconductor light emitting element 10, a maximum physical thickness t _s of the substrate satisfies the following formula 1.
Formula 1
L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}
(However,
λ represents the peak wavelength (nm) of light emitted from the semiconductor light emitting device,
t _s represents the maximum physical thickness of the substrate;
L _sc represents the longest line segment length formed by any two points on the main surface of the substrate;
n _s (λ) represents the refractive index of the substrate at the wavelength λ. )

The configuration satisfying the formula 1 can effectively improve the light extraction efficiency from the side wall of the semiconductor light emitting device in which the direction of the maximum value of the internal light emission intensity density is close to the parallel direction to the active layer structure. At the same time, such a structure can be realized by a simple manufacturing method. Further, such a structure is advantageous in that the light distribution characteristic can be controlled.

In a triangular planar structure, the proportion of vertices whose angles are acute among all vertices can be easily increased compared to other figures. For example, in the case of a regular triangle, all corners are acute angles, but there are no acute angles in squares, regular pentagons, and regular hexagons. In a triangle, at least the two angles are acute angles, so the ratio of the acute angles is 2/3 or more. However, if there is no concave portion in plan in other figures, it will not exceed this ratio. . The acute angle portion forms a planar shape that is advantageous in extracting light emitted in the vicinity of the acute angle portion as compared with the obtuse angle portion. Therefore, particularly in this semiconductor light emitting device mainly for extracting light from the side wall surface, It is particularly preferable that the shape projected in the direction perpendicular to the main surface of the substrate is a substantially triangular shape.

Further, when the projection shape of the semiconductor light emitting element is selected to be a triangle, a shape having low symmetry is preferable because it is advantageous for light extraction. For example, an isosceles triangle is more preferable than an equilateral triangle, and an unequal triangle having different lengths and angles of all sides is advantageous for light extraction. This is because in the case of a highly symmetric figure, planar stay light is generated due to the symmetry. On the other hand, when the symmetry is low, such staying light is unlikely to occur.

For the above reasons, it is preferable that the shape of the substrate projected from the direction perpendicular to the main surface is substantially triangular. In addition, the “substantially triangular” means a figure (triangle) surrounded by three sides such as a regular triangle, an isosceles triangle, and an unequal triangle, and generally has a triangular shape, but the three sides are not strictly straight lines. It is intended that a part or all of any one or more of the sides may have a fine corrugated shape or irregular shape regularly or irregularly.

Here, in the shape of fine irregularities, for example, as will be described later in the section <Substrate surface orientation and irregularity formation on substrate>, the irregularity size (level difference from the line) is the peak wavelength of the semiconductor light emitting element. Can have dimensions of about λ / 50 to 50λ. Preferably, it has a dimension of about λ / 10 to 10λ, more preferably a dimension of about λ / 7 to 7λ, and further preferably a dimension of about λ / 5 to 5λ. The distance between the concave portions adjacent to the concave portion (distance between the convex portions adjacent to the convex portion) can have a dimension of about λ / 50 to 50λ, where λ is the peak wavelength of the semiconductor light emitting element. Preferably, it has a dimension of about λ / 10 to 10λ, more preferably a dimension of about λ / 7 to 7λ, and further preferably a dimension of about λ / 5 to 5λ.

In the configuration of FIG. 6A (see also FIG. 6B), the refractive index at the wavelength λ of the surrounding medium is expressed as n _out (λ),
The refractive index at wavelength λ of the nitride substrate is expressed as n _s (λ),
Let t _{s be} the physical thickness of the thickest part of the substrate,
The refractive index at the wavelength λ of the layer X constituting the semiconductor layer portion is represented by n _LX (λ) (that is, the layer X represents an arbitrary layer constituting the semiconductor layer portion, and n _LX (λ) is the wavelength of the layer X. represents the refractive index at λ).
The maximum physical thickness from the substrate main surface to the active layer structure is t _a ,
Let t _L be the maximum physical thickness of the semiconductor layer portion.

The longest line segment length (straight line length) formed by any two points on the main surface of the substrate (substantially triangular in this figure) is defined as L _sc .

In this figure, since the planar shape of the main surface is a substantially triangular shape, the length of the shortest side of the substantially triangular shape of the main surface of the substrate is L _sa .

6A, points A and B are points at the end of the semiconductor layer portion 15 (the lower side of the figure). Points C and D are end points of the active layer structure 16. Points E and F are points at the end of the boundary between the substrate main surface 21 and the semiconductor layer portion 15. Point G and point H are points at which the element is separated from other light emitting elements 10 that were adjacent to each other in manufacturing (in this shape, the other points are also the ends at which element separation was performed). . Point I and point J are points at the end of the substrate on the surface opposite to the substrate main surface 21 (upper side in the figure).

The maximum value of the internal emission intensity density of light emitted from the active layer structure 16 (the maximum value of the internal profile) is relatively close to the parallel direction of the active layer structure. Therefore, in order to improve the light extraction efficiency, the light emitted from the point C in FIG. 6A is assumed, and this includes the direction of the maximum value of the internal emission intensity density and includes the point C as much as possible. Assuming internal light emission radiated in the other direction from the semiconductor light emitting device shape in which these lights can be effectively extracted from the wall portion (the farthest side wall portion) of the light emitting device farthest from the point C You can do it.

That is, considering the critical angle on the straight line including point B, point D, point F, point H, and point J of the light emitted from point C in FIG. 6A, any light emitting portion of the entire element was considered. Even in this case, the light extraction requirement from the side wall is sufficient. FIG. 6B is a view of a surface surrounded by the points I, A, B, and J of the light emitting element of FIG. 6A as viewed from the vertical direction. In FIG. 6B, a straight line including point A to point I, a straight line including point B to point J (the farthest side wall portion), and a plane surrounded by point A to point B and point I to point J are illustrated. Yes.

Here, the distance between the points A and B is the longest line segment length L _{sc formed} by any two points on the main surface of the substrate, and in this case, corresponds to the longest side (see FIG. 6A). Here, an approximation with good visibility is given below. Since n _s (λ) and n _LX (λ) do not differ greatly, light generated from the active layer structure sufficiently reaches the side surface of the nitride substrate. The maximum physical thickness t _a of the substrate main surface 21 to the active layer structure is sufficiently thin compared to the thickness t _s of the nitride substrate. Therefore, assuming that the light emission from point C is the light emission from point E, the critical angle in the farthest side wall including point B, point D, point F, point H and point J may be considered.

FIG. 6C is a diagram showing the behavior of light. Assuming that light is emitted from the point E, the farthest side wall (the right wall in the figure) is divided into the following three regions 131, 132, and 133 corresponding to the behavior of light.

The first region 131 is the lowermost region of the farthest side wall portion. In this first region 131, the incident angle α (= 90−θ _em ) of the light incident on the farthest side wall portion is the critical angle α _c = sin ⁻¹ (n _out (λ) / n _s (λ)). Where α <α _c
(The farthest side wall first region with respect to the point E). Here, n _out (λ) is the refractive index of the peripheral medium at the emission wavelength λ of the semiconductor light emitting element.

The second area 132 is an area existing on the first area 131 described above. In the second region 132, α _c ≦ α in the relation that the incident angle α of the light incident on the farthest side wall portion is the critical angle α _c = sin ⁻¹ (n _out (λ) / n _s (λ)). ≦ 90-α _c
(The farthest side wall second region with respect to the point E or the intrinsic confinement light generation region).

The third region 133 is a region further above the second region 132 described above. In the third region 133, the incident angle α of the light incident on the farthest side wall portion is 90−α _{c in} relation to the critical angle α _c = sin ⁻¹ (n _out (λ) / n _s (λ)). <Α
(The farthest side wall third region with respect to the point E).

The light incident on the first region 131 is not totally reflected. Therefore, light can be effectively extracted from this region 131 in the farthest side wall portion. On the other hand, the light incident on the second region 132 and the light incident on the third region 133 undergo total reflection.

The second region 132 is a region where even if the light that has undergone total reflection is reflected and reaches the other light emitting element side wall surface, it is further subjected to total reflection on that surface. In other words, the semiconductor light emitting element It is an area that creates “intrinsic confinement light”.

The light incident on the third region 133 is totally reflected at the farthest side wall, but has an incident angle smaller than the critical angle at the other part (for example, the substrate surface 21a), so that it can be taken out by repeating the reflection. .

Here, when the thickness t _s (FIG. 6B) of the nitride substrate 12 is thin so as to be within the farthest side wall first region 131, the nitride substrate thickness that is essentially sufficient as shown in FIG. 6D. The light that can be extracted from the farthest side wall portion (see the broken line in the figure) is totally reflected by the substrate surface 12a facing the main surface, and is absorbed when the light again enters the active layer structure, or Since it may be absorbed by the second conductivity type side electrode, the first conductivity type side electrode, etc., it is not preferable.

If the reflectivity of the electrode or the like is 100% and the loss of the nitride substrate and the semiconductor layer portion is 0, the light can be emitted from the side wall by repeating multiple reflection. Environment is not realized. That is, the thickness t _s of the nitride substrate may such that the first region 131 is not preferable from the viewpoint of efficient extraction of light.

On the other hand, if such a thick thickness t _s of the nitride substrate 12 is in the third region 133 (Fig. 6C) in the as shown in FIG. 6E, the major surface be thick thickness of the original nitride substrate 12 Light that can be extracted from the opposing substrate surface 12a is reflected by the third region 133 and is extracted from the substrate surface 12a in a different direction. In this case, light can be extracted from the side wall of the light emitting element, which is preferable.

However, in this case, since the optical path length becomes long, there is a concern that the light emission efficiency is reduced due to optical loss in the nitride substrate 12, and that a light emitting element using an excessively thick substrate is disadvantageous in terms of cost. However, in principle, it is possible to extract light from the side wall of the light emitting element, which is preferable.

In particular, when emphasizing the light extraction from the side wall of the semiconductor light emitting device 10, it is a form that can be preferably used, and in particular, by providing the side wall with uneven processing, further exposed surface forming processing, etc. Is preferable as its basic structure.

On the other hand, the thickness t _s of the preferred nitride substrate in the present invention is given as follows.

Considering that the intensity of light emitted internally from the active layer structure has its maximum value in a direction relatively close to the direction parallel to the active layer structure 16, light in a direction with a high internal emission intensity density is converted into a semiconductor. while effectively removed from the light emitting element side wall, even light emitted in other directions as well effectively removed from the side wall as possible, further also consider enough in cost, the thickness t _s of the nitride substrate 12 The thickness is within the second region 132 (intrinsic confinement light generation region).
That is, the nitride substrate thickness t _s of the present invention is preferably more than the thickness (t ₁ in FIG. _6C) The lower limit of the thickness of the intrinsic confinement light generation region 132. The upper limit of the thickness _{t s} is preferably less 5500μm in terms of isolation.

Further preferred thickness t _s of the nitride substrate is preferably to a thickness of at least the thickness of the lower limit of the intrinsic confinement light generation region 132 (t ₁ in the _figure), the upper limit of the intrinsic confinement light generation region thickness (in FIG. t ₂ ) More preferably, the thickness is less than or equal to. That is, the nitride substrate thickness t _s is the thickness of the intrinsic confining light generation region, i.e.,
t ₁ ≦ t _s ≦ t ₂
More preferably.

From this result, the thickness t _s of the nitride substrate of the present invention, the aspect ratio of the longest line segment lengths to make the two arbitrary points overlaying the substrate main surface and _{L sc (t s / L sc} ) When captured, tan α = t _s / L _sc
tan {sin ⁻¹ (n _out (λ) / n _s (λ))} ≦ t _s / L _sc
≦ tan {90−sin ⁻¹ (n _out (λ) / n _s (λ))}
It is.

Therefore, more preferred thickness _{t s} of the nitride substrate 12 of the semiconductor light emitting element 10,
L _sc × tan {sin ⁻¹ (n _out (λ) / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (n _out (λ) / n _s (λ))}
... (Formula 1a)
It becomes.

By setting the thickness within this range, internal light emission can be effectively extracted from the semiconductor light emitting element.

[Specific example 1 regarding substrate thickness]
Additionally, Formula _1a, if _{n out (λ)} is small _{n s} (lambda) is large, giving a thickness _{t s} of the nitride substrate of the broadest range.

Therefore, n _out (λ) can be set to 1 assuming vacuum or effectively air. Therefore, the preferred substrate thickness of the semiconductor light emitting device in the present invention is:
L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}
... (Formula 1)
It becomes.

The thickness t _s of the nitride substrate in the present invention, as described below, the maximum thickness length extended from the main surface vertically thickest.

It is preferable that the substrate thickness satisfy the formula 1 and the light emitted in the direction giving the maximum value of the internal emission intensity density is directly incident on the farthest side wall portion within the specified thickness. Further, from the viewpoint of manufacturing cost and the like, it is advantageous that the thickness of the substrate is set to the minimum necessary thickness while satisfying these.

Therefore, the index that can be the lower limit of the thickness t _s of the semiconductor light emitting element,
(A) L _sc × tan {sin ⁻¹ (1 / n _s (λ))}
(B) L _sc × tan {1 × (90−θ _{em max} )}
(C) L _sc × tan {1.5 × (90−θ _{em max} )}
(D) L _sc × tan {2.0 × (90−θ _{em max} )}
It is.

(A) is an index defined by the critical angle of light emitted from the point E in the farthest side wall, and is a necessary requirement to be satisfied by the present invention.
In (b) to (d), since the direction showing the maximum value of the internal emission intensity density is close to the direction substantially parallel to the active layer structure, the preferable range in the present invention is 67.5 degrees ≦ θ _{Although em max} <90.0 degrees, here, if considered as 45 degrees <θ _{em max} <90 degrees, it is sufficient as a mathematical range, and after satisfying the requirement of (a), the semiconductor light emitting device which may give preferable lower limit of the thickness t _s should satisfy it is.

Note that the requirements (a) and (b) to (d) have different magnitude relationships depending on each parameter. Therefore, when the requirements (b) to (d) are larger than the requirements (a), There is a case where a preferable lower limit value of the thickness to be satisfied by the semiconductor light emitting element is given. In particular, when (c) and (d) are satisfied, not only the light emitted in the direction indicating the maximum value of the internal light emission intensity density but also the strong light in the vicinity thereof can be extracted from the side wall. preferable.

Meanwhile, the index that can be the preferred upper limit of the thickness t _s of the semiconductor light emitting element,
(E) L _sc × tan {90-sin ⁻¹ (1 / n _s (λ))}
(F) 2.5 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))}
(G) 2.0 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))}
(H) 1.5 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))}
It is.

(E) is an index defined by the critical angle of light emitted from the point E in the farthest side wall, and is a requirement that the present invention preferably satisfies.
(F) to (h) are more preferable indicators of the substrate thickness that can be provided so that the substrate thickness is the minimum necessary thickness. The substrate in which the semiconductor light emitting element is embedded when the indices (f) to (h) are smaller than the indices (e) and larger than any one of the indices (a) to (d) which may give a preferred upper limit of the thickness t _s should satisfy it is. In this case, (f) means that the thickness of the substrate is preferably within 2.5 times the minimum necessary thickness, (g) is within 2 times, and (h) is preferably within 1.5 times. .

[Specific example 2 regarding substrate thickness]
A specific example of Equation 1 will be described. As will be described later, n _s (λ) increases as the wavelength becomes shorter, but it is necessary to select n _s (λ) within a range where absorption is not large. Further, in the nitride substrate 12, for example, even if an AlN substrate, a BN substrate, or the like is assumed, the refractive index at the same wavelength is smaller than that of the GaN substrate.

Therefore, _{n s} (λ) would give a thickness _{t s} of the widest range of the nitride substrate may have a 2.596 from the measured value at 370nm of the GaN substrate.

Thus, when calculating Equation 1,
L _sc × 0.418 ≦ t _s ≦ L _sc × 2.395 Equation 8
It becomes.

Therefore, if installing a semiconductor light-emitting element around the medium _{n out (λ) = 1,} θ em when the _max = 75 degrees, more preferably _{t s} range the that may have the lower limit of the (a) To (d) are as follows: (a) L _sc × tan {sin ⁻¹ (1 / n _s (λ))} = L _sc × 0.418
(B) L _sc × tan {1.0 × (90−θ _{em max} )} = L _sc × 0.268
(C) L _sc × tan {1.5 × (90−θ _{em max} )} = L _sc × 0.414
(D) L _sc × tan {2.0 × (90−θ _{em max} )} = L _sc × 0.577
It is.

Therefore, the lower limit of the thickness of the semiconductor light emitting element L _sc × 0.418 ≦ _{t s}
And more preferably,
L _sc × 0.577 ≦ t _s
It is.

On the other hand, the indicators (e) to (h) that may give the upper limit are
(E) L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))} = L _sc × 2.395
(F) 2.5 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))} = L _sc × 1.045
(Q) 2.0 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))} = L _sc × 0.836
(H) 1.5 × L _sc × tan {sin ⁻¹ (1 / n _s (λ))} = L _sc × 0.627
It is.

Preferably the upper limit of the thickness _{t s} of the semiconductor light emitting element is t _s ≦ _{L sc} × 2.395,
More preferably, t _s ≦ L _sc × 1.045
More preferably, t _s ≦ L _sc × 0.836,
Most preferably, t _s ≦ L _sc × 0.627.

Therefore, in summary, when listing preferable indicators in the case of such an example,
L _sc × 0.418 ≦ L _sc × 0.577 ≦ t _s ≦ L _sc × 0.627
≦ L _sc × 0.836 ≦ L _sc × 1.045 ≦ L _sc × 2.395
It becomes.

In addition, when calculating using 2.4367 from the actual measurement value at 460 nm of the GaN substrate, Equation 1 is
L _sc × 0.450 ≦ t _s ≦ L _sc × 2.221
Thus, the range is narrower than that of Equation 8.

Table 1 shows a GaN substrate (“C-GaN” in the table) whose main surface is the (0001) plane and a GaN substrate (“m-GaN” in the table) whose main surface is (1-100). ) Shows the result of actual measurement of the refractive index.

[Additional Note in Equation 1a: 45 degrees <sin ⁻¹ (n _out (λ) / n _s (λ)) ≦ 90 degrees (general theory)]
In the case of 45 degrees <sin ⁻¹ (n _out (λ) / n _s (λ)) ≦ 90 degrees, Expression 1a interchanges the magnitude relationship between the upper limit and the lower limit. That is, in this case, the critical angle of the light emitted from the point E at the far side wall is larger than 45 degrees.

In this case, further in other words, the second region 132 farthest side wall portion of the E points defining a nitride substrate thickness t _s (intrinsic confinement light generation region) will not be present.

Even in such a case, in the present invention, the internal light emission profile is anisotropic and θ _{em max,} which is the direction giving the maximum value of the light emission intensity density, is 67.5 degrees ≦ θ _{em max} <90 degrees. Therefore, it is preferable that light extraction from the farthest side wall portion is easily realized.

Equation 1a is a peripheral medium of the semiconductor light emitting element.
n _out (λ) << n _s (λ)
In fact, it is an element placed in a peripheral medium where 45 degrees <sin ⁻¹ (n _out (λ) / n _s (λ)) ≦ 90 degrees. even, if n _{out (λ)} is assumed small n _{s (lambda)} is large, it is possible to obtain the thickness t _s of the broadest scope of the preferred nitride substrate. This is because even if the refractive index of the GaN substrate is a value of about 2.43 at about 460 nm, the refractive index of the peripheral medium is a practical limit of about 2.20 or less.

Therefore, even in such a case, n _{out (lambda)} is the vacuum or effectively assume air, giving a thickness t _s widest range of the nitride substrate obtained by this with 1 .

Therefore, even in the case of 45 degrees <sin ⁻¹ (n _out (λ) / n _s (λ)) ≦ 90 degrees, the semiconductor light emitting element can be expressed by Formula 1 or Formula 8 if the light emitting element is on a GaN substrate. If satisfied, sufficient light extraction from the side wall is possible. In addition, indices for giving a preferable substrate thickness are as shown in (a) to (h).

[About Additional Matters t _s and _{t a} in formula 1a]
Now, _{t s} in the description up to now, were those approximating _t s + _{t a} from a consideration of FIG. 6B. That is, the end of the active layer structure 16 was approximated to the end of the nitride substrate 12. Here, in general, the thickness of the second conductivity type semiconductor layer that can be a main component between the point C and the point A is sufficiently smaller than the thickness of the entire layer constituting the other semiconductor layer portion. it is also possible to approximate the _s + _{t a} as _t s + _{t L.} That is, the end of the active layer structure can be approximated to the end of the semiconductor layer portion.

In this case, Equation 1 and Equation 8 are expressed as _{t t} = t _s + t _L ,
L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _t
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))} Equation 5
L _sc × 0.418 ≦ t _t ≦ L _sc × 2.395 Equation 7
It is.

On the other hand, it is possible to consider the point C as a light emitting point without making such approximations, but the structure of the semiconductor layer, particularly the light emitting part when using the quantum well active layer structure is not necessarily specified. Since it is not easy, it is a realistic guideline and preferable to satisfy the approximate expressions of Expressions 1, 5, 7, and 8.

[Plane size of the chip of the element of the present invention]
Next, the inventors examined a method for easily manufacturing the semiconductor light emitting device 10 having the structure of FIG. 6A, for example. As described above, it is preferable that the maximum physical thickness t _s of the substrate satisfies the equation 1, when the addition meets formula 2-1, to be able to easily form a semiconductor light-emitting device of substantially triangular substrate main surface I found it.
Formula 1
L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}
Formula 2-1
250 (μm) ≦ L _sa ≦ L _sc ≦ 5000 (μm)
Here, L _sa is the length of the shortest side of the substantially triangular shape of the substrate main surface.

This is derived from the following study.

The length of a normal GaN-based semiconductor light-emitting element _{L sa} and _{L sc} is about 250 [mu] m, _{t s} is about 100 [mu] m. _{Furthermore, L sa} and _{L t s} even large chip that is longer than about 1mm of _sc is approximately 100 [mu] m. This is because the substrate that has been mainly used is an excessively hard material such as sapphire, and its thickness is mainly determined by the convenience of the element separation process of element separation and dicing.

On the other hand, a GaN-based semiconductor light emitting device on a different substrate such as sapphire has a problem of thermal distortion when a semiconductor layer portion is formed on the substrate, and crystal growth is difficult on a substrate having a thickness of about 100 μm. Therefore, it is necessary to form a semiconductor layer 15 with a substrate thickness exceeding 400 μm, and then polish the substrate to a thickness of about 100 μm at the final stage of the device fabrication process to prepare for the device isolation step. The process was complicated.

On the other hand, when a GaN substrate, for example, is used as the nitride substrate, its hardness is lower than that of a sapphire substrate, and element separation processes such as scribing, breaking, and dicing are relatively easy even with a relatively thick substrate. Can be. On the other hand, its hardness is harder than GaAs, GaP, InP, ZnO, etc., and it is not as easy as these materials in element isolation processes such as scribe, braking, dicing and the like. That is, when using a nitride substrate, it is necessary to overcome special circumstances due to its hardness. In addition, when a GaN-based semiconductor light-emitting element is formed on a GaN substrate, it is expected that problems such as thermal distortion will be reduced.
Therefore, as a result of various studies, the handling of the process is easy, and the preferable lower limit of the thickness t _s of the GaN substrate of the semiconductor light emitting element capable of forming a high-quality semiconductor layer portion was at 250μm thick.

Next, a semiconductor light emitting device having a substrate having a thickness of 250 μm was easily isolated by various methods such as scribing, breaking, and dicing, and L _sa that can be converted into a device was experimentally determined. As a result, element separation was easy when L _sa was 250 μm or more. Further, when the thickness is 400 μm or more, the occurrence of damage to the element itself and the yield reduction due to this are reduced. Further, when L _sa is 550 μm or more, the occurrence of chipping or the like due to the braking process is particularly reduced. In the present invention, since light is extracted from the side wall of the semiconductor light emitting device and the shape projected in the direction perpendicular to the main surface of the substrate is a substantially triangular shape, chipping in the chip outer shape is described as follows. Suppressing the occurrence has great technical significance.

In the present semiconductor light emitting device in which the shape projected in the direction perpendicular to the main surface of the substrate is substantially triangular, the angle of two vertices is an acute angle at least among the vertices, so the ratio of the acute angle is 2/3 or more. The acute angle portion forms a planar shape that is advantageous for light extraction as compared to the obtuse angle portion, and in this semiconductor light emitting device mainly for light extraction from the side wall surface, it is projected in a direction perpendicular to the main surface of the substrate. It is particularly preferable that the formed shape is a substantially triangular shape. However, since the acute angle portion is easily chipped, it is technically significant to suppress this chipping. That is, the lower limit of L _sa when _ts is relatively thin is preferably 250 μm or more, more preferably 400 μm or more, and further preferably 550 μm or more.

On the other hand, scribing, breaking, the upper limit of the thickness t _s of the GaN substrate capable of carrying out isolation process by a simple method such as dicing was 5500Myuemu. In this case, an element isolation method such as dicing is effective. Thus, it was found that when _ts is thick, good element isolation can be _achieved when L _sa is large.

However, if L _sc is excessively large, it was found that the peeling from the dicing sheet becomes difficult. Especially when t _s is diced thick GaN substrate of 5500μm and film thickness is necessary to fix the GaN substrate to withstand a load applied to the spindle to the dicing sheet with a sufficient adhesive force is generated, the L _sc When dicing was performed so as to have a thickness of 5000 μm or less, when the device was peeled from the sheet after dicing, excessive damage was not induced in the device, and the yield reduction was reduced.

Furthermore, when L _sc was 2500 μm or less, partial damage of the element during sheet peeling was reduced, and a good shape could be maintained after element separation. When L _sc was 2000 μm or less, the degree of breakage of the element was further reduced, and many elements having a favorable shape were preferred. When L _sc was 1550 μm or less, extremely good element isolation was possible.

That is, the upper limit of _{L sc} where _{t s} is relatively thick, there generally below 5000 .mu.m, preferably not more than 2500 [mu] m, more preferably equal to or less than 2000 .mu.m, more preferably was less than 1550. These facts were not found in GaAs, GaP, InP, ZnO or the like.

Here, first, the semiconductor light emitting element 10 having a planar shape satisfying 550 μm ≦ L _sa ≦ L _sc is a semiconductor light emitting element in a category called a so-called large chip. In general, a large chip has a problem that its light emission efficiency is low, but according to the light emitting element of the present invention, light can be efficiently extracted from the side wall of the semiconductor light emitting element. For example, in the case of a semiconductor light emitting device having a GaN-based semiconductor layer on a right isosceles triangular GaN substrate with L _sa of 550 μm, the L _sc is about 778 μm, and the substrate thickness required from Equation 8 is about the lower limit. 325 μm.

Therefore, when such a relatively large planar device is produced with a thickness of about 100 μm like a semiconductor light emitting device having a conventional sapphire substrate, as shown in FIG. 6D, an essentially sufficient nitride substrate is obtained. The light that can be extracted from the farthest side wall portion is totally reflected by the substrate surface 12a facing the main surface and is absorbed when the light enters the active layer structure again, or the second conductivity type. It may be absorbed by the side electrode, the first conductivity type side electrode, or the like.

As described above, such a semiconductor light emitting device is a very effective method for a large chip, which has a problem of low luminous efficiency. In particular, since the planar shape is a triangle, it is advantageous to extract light from an acute angle portion. Therefore, light extraction efficiency superior to other shapes is expected.

Among these, the case where 550 μm ≦ L _sa ≦ L _sc ≦ 5000 μm is satisfied is more preferable, and a process such as polishing the substrate after forming a high-quality semiconductor layer portion on the prepared nitride substrate of the semiconductor light emitting element is performed. Even if it is not implemented, the shape can be produced by a simple method. Further, since the light distribution characteristic can be controlled, a large-sized semiconductor light-emitting element having favorable characteristics can be manufactured at low cost.

Furthermore, the semiconductor light emitting device 10 on a nitride substrate having a planar shape satisfying 550 μm ≦ L _sa ≦ L _sc ≦ 1550 μm is preferable, and it is possible to perform remarkably easy and good device isolation. In particular, the lower limit of the above formula is more preferable when satisfying 650 μm or more, further preferable when satisfying 800 μm or more, particularly preferable when satisfying 850 μm or more, and most preferable when satisfying 900 μm or more.

The upper limit of the above formula is more preferably 1450 μm or less, more preferably 1300 μm or less, particularly preferably 1250 μm or less, and most preferably 1200 μm or less. In the present invention, a semiconductor light-emitting device having a planar shape satisfying L _sa ≦ L _sc <550 μm, that is, a so-called small chip, can be produced from a single nitride substrate in a larger number than a large chip. . Since these elements mainly extract light from the side wall, they are highly efficient and can control light distribution characteristics. Therefore, the present invention is very effective even when L _sa ≦ L _sc <550 μm, and it is also preferable to have such a planar size.

In particular, when 250 μm ≦ L _sa ≦ L _sc <550 μm, that is, when L _sa is 250 μm or more, element isolation is easy as described above, which is more preferable.

The above-described technology is a technology that can be suitably used for semiconductor light emitting devices in the purple, near-ultraviolet, and ultraviolet regions, which generally do not have high reflectivity at electrodes.

The lower limit of the peak emission wavelength λ is preferably 370 nm or more, more preferably 380 nm or more, further preferably 390 nm or more, and particularly preferably 400 nm or more. Furthermore, the upper limit of the peak emission wavelength λ is preferably 430 nm or less, more preferably 420 nm or less, and further preferably 410 nm or less.

Further, the nitride semiconductor for setting the light emitted from the active layer structure 16 in the above range includes a quantum well layer made of In _x Ga _1-x N and a barrier layer made of Al _y Ga _1-y N. A quantum well active layer structure can be exemplified, but in this, when realizing the above wavelength range, it is possible to easily realize a configuration for reducing the refractive index difference between the quantum well layer and the barrier layer, and There are configurations that can also confine sufficient electron-hole pairs. The In _x Ga _1-x N-based quantum well layer capable of realizing such a wavelength can have an In composition x of about 0.10 or less when a GaN substrate is used, for example. The barrier layer can be made of GaN, which is preferable because the difference in refractive index is reasonably small.

Further, by doping the barrier layer 33 (see FIG. 4B) with Si or the like, it becomes possible to further reduce the refractive index difference between the quantum well layer and the barrier layer, so that the barrier layer is doped with Si or the like. It is particularly preferred. Therefore, in this invention, it is suitable to adapt to the semiconductor light-emitting device which has a wavelength of the said range.

Further, when the semiconductor layer portion 15 on one substrate has a so-called large chip configuration in which a relatively large single light emitting unit is configured, a plurality of light emitting units are configured on the semiconductor layer portion 15 on one substrate, Although the single light emitting unit has a relatively small planar shape, the integrated light emitting element has a large planar shape as a whole, and moreover, a plurality of relatively large sizes are formed on a semiconductor layer portion on one substrate. An integrated semiconductor light-emitting element having a light-emitting unit and having a large planar shape can be obtained. A light-emitting element having a large planar size can input a large amount of power, and the present invention can improve the light extraction efficiency of such a light-emitting element. Therefore, a light-emitting element that achieves both high output characteristics and high efficiency. Is preferable.

Here, a supplementary explanation will be given for the case where the planar shape of the semiconductor light emitting element is a square or a polygon.
[Rectangle]
FIG. 7A is a diagram schematically illustrating a geometric shape of a semiconductor light emitting device having a square planar shape. In this example, when the nitride substrate 12 is projected on the substrate main surface 21 in the vertical direction, it has a substantially rectangular shape. Further, since all of the side wall surfaces are perpendicular to the substrate main surface 21, the projection shape of the nitride substrate 12 coincides with the planar shape of the substrate main surface 21 and is congruent within the range of manufacturing errors (“substantially congruent”). ) And the main surface has a substantially rectangular shape. In this case, the shape projected in the vertical direction on the main surface of the substrate generally matches the shape of the adjacent element isolation end.

Here, the longest line segment length formed by any two points on the main surface of the substrate is L _sc, and the refractive index at the wavelength λ of the substrate is n _s (λ). The semiconductor light emitting element 10, a maximum physical thickness t _s of the substrate satisfies the following formula 1.
Formula 1
L _sc × tan {sin ₋₁ (1 / n _s (λ))} ≦ t _s
≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}

Further, main surface, wherein in the case is substantially congruent with the projected shape in a direction perpendicular to the substrate main surface, the longest substantially rectangular length L _sa and the substrate main surface of the shortest side of the substantially rectangular the substrate main surface The side length L _sb satisfies the following expression 2-2.
Formula 2-2
550 (μm) ≦ L _sa ≦ L _sb ≦ 1550 (μm)

The configuration satisfying these equations can effectively improve the light extraction efficiency from the side wall of the semiconductor light emitting device in which the direction of the maximum value of the internal light emission intensity density is close to the parallel direction to the active layer structure. At the same time, such a structure can be realized by a simple manufacturing method. Further, such a structure is advantageous in that the light distribution characteristic can be controlled.

This is derived from the following study.

The length of _{L sa} and _{L sb} on conventional GaN-based semiconductor light-emitting device is about 250 [mu] m, _{t s} is about 100 [mu] m. _{Furthermore, L sa} and _{L t s} even large chip that is longer than approximately 1mm in _sb is about 100 [mu] m. This is because the substrate that has been mainly used is an excessively hard material such as sapphire, and its thickness is mainly determined by the convenience of the element separation process of element separation and dicing.

On the other hand, a GaN-based semiconductor light emitting device on a different substrate such as sapphire has a problem of thermal distortion when a semiconductor layer portion is formed on the substrate, and crystal growth is difficult on a substrate having a thickness of about 100 μm. Therefore, it is necessary to form a semiconductor layer 15 with a substrate thickness exceeding 400 μm, and then polish the substrate to a thickness of about 100 μm at the final stage of the device fabrication process to prepare for the device isolation step. The process was complicated.

On the other hand, when a GaN substrate, for example, is used as a nitride substrate, its hardness is lower than that of a sapphire substrate, and element separation processes such as scribing, breaking, and dicing are relatively easy even with a relatively thick substrate. Can be. On the other hand, its hardness is harder than GaAs, GaP, InP, ZnO, etc., and it is not as easy as these materials in element isolation processes such as scribe, braking, dicing and the like. That is, when using a nitride substrate, it is necessary to overcome special circumstances due to its hardness. In addition, when a GaN-based semiconductor light emitting element is formed on a GaN substrate, it is expected that problems such as thermal distortion will be reduced.

Therefore, as a result of various investigations, it is easy to handle a wafer including a semiconductor light emitting element whose shape projected in the vertical direction on the main surface of the substrate is a substantially rectangular shape, and a high-quality semiconductor layer portion. the lower limit of the thickness _{t s} of the GaN substrate of a semiconductor light emitting element may be formed, it was at 250μm thick.

Next, a semiconductor light emitting device having a substrate having a thickness of 250 μm was easily isolated by various methods such as scribing, breaking, and dicing, and L _sa that can be converted into a device was experimentally determined. As a result, when L _sa is shorter than 250 μm, element isolation is difficult. When L _sa is shorter than 250 μm and shorter than 400 μm, although element isolation is possible, the element itself may be damaged, resulting in a decrease in yield. In the case of 400 μm or more and shorter than 550 μm, defects such as chipping occurred particularly in the braking process. In the present invention, since light is extracted from the side wall of the semiconductor light emitting device, it is not preferable that excessive chipping occurs in the outer shape of the chip.

On the other hand, it was found that good element isolation can be achieved when L _sa is 550 μm or more. That is, the lower limit of L _sa when _ts is relatively thin is 250 μm or more, preferably 400 μm or more, and more preferably 550 μm or more.

On the other hand, scribing, breaking, the upper limit of the thickness t _s of the GaN substrate capable of carrying out isolation process by a simple method such as dicing was 5500Myuemu. In this case, an element isolation method such as dicing is effective. Thus, even if t _s is thick, L _sa is the case of the above 550μm was found to be good isolation.

However, it was found that when L _sb is excessively large, peeling from the dicing sheet becomes difficult. Especially when t _s is diced thick GaN substrate of 5500μm and film thickness is necessary to fix the GaN substrate to withstand a load applied to the spindle to the dicing sheet with a sufficient adhesive force is generated, more than 5000μm When dicing so as to be L _sb , even when a UV curable sheet was used when the element was peeled from the sheet after dicing, excessive damage was induced to the element, and no yield was obtained. When it was longer than 2500 μm and less than or equal to 5000 μm, partial damage was induced in the element, and although it could be peeled from the sheet, it did not have a good shape after element separation.

On the other hand, when L _sb is longer than 1550 μm and equal to or less than 2500 μm, the degree of damage to the elements is reduced, and many elements have good shapes, which is preferable. This degree was even better when it was longer than 1550 μm and less than 2000 μm. When L _sb was 1550 μm or less, extremely good element isolation was possible.

That is, the upper limit of _{L sb} where _{t s} is relatively thick, a less 2500 [mu] m, preferably not more than 2000 .mu.m, more preferably was less than 1550. These facts were not found in GaAs, GaP, InP, ZnO or the like.

On the other hand, in the semiconductor light emitting device 10 on a nitride substrate having a planar shape satisfying 550 μm ≦ L _sa ≦ L _sb ≦ 1550 μm, a high quality semiconductor layer portion is formed on the prepared nitride substrate, and then the substrate is polished. Even without performing such processes as described above, it was possible to easily perform good element isolation.

In particular, the lower limit of the above formula is more preferable when satisfying 650 μm or more, more preferable when satisfying 800 μm or more, particularly preferable when satisfying 850 μm or more, and most preferable when satisfying 900 μm or more. The upper limit of the above formula is more preferably 1450 μm or less, more preferably 1300 μm or less, particularly preferably 1250 μm or less, and most preferably 1200 μm or less.

A semiconductor light emitting device that satisfies such requirements is a semiconductor light emitting device in a category called a so-called large chip because of its planar shape. In general, a large chip has a problem that its light emission efficiency is low, but according to this light emitting element, it is possible to efficiently extract light from the side wall of the semiconductor light emitting element. Moreover, it has a shape that can be produced by a simple method. Further, since the light distribution characteristic can be controlled, a large-sized semiconductor light-emitting element having favorable characteristics can be manufactured at low cost.

[For polygons]
FIG. 7B is a diagram schematically showing a geometric shape of a hexagonal semiconductor light emitting element as an example of a planar shape. In this example, when the nitride substrate 12 is projected on the substrate main surface 21 in the vertical direction, it has a substantially hexagonal shape. That is, it is an m-gon with m = 6.

Here, the longest line segment length formed by any two points on the main surface of the substrate is L _sc, and the refractive index at the wavelength λ of the substrate is n _s (λ). The semiconductor light emitting device 10 of the present invention, the maximum physical thickness t _s of the substrate, said same, satisfies equation 1. Further, when the main surface of the substrate is substantially the same as the shape projected in the direction perpendicular to the main surface of the substrate, the L _sc satisfies the following formula 2-3.
Formula 2-3
500 (μm) ≦ L _sc

As a result of various investigations, wafers containing a polygonal semiconductor light emitting element whose shape projected in the direction perpendicular to the main surface of the substrate is approximately pentagonal to octagonal are easy to handle in the process, and high a preferred lower limit of the thickness t _s of the GaN substrate of the semiconductor light emitting element capable of forming a quality semiconductor layer portion, was at 250μm thick.

Next, a semiconductor light emitting device having a shape projected in a direction perpendicular to the main surface of the substrate and having a substantially regular pentagonal shape, a substantially regular hexagonal shape, a substantially regular octagonal shape, and a substantially regular dodecagonal shape is formed on a substrate having a thickness of 250 μm. Element dimensions that can be easily separated into elements by various methods such as dicing were obtained experimentally. Here, it has been found that the ease of element isolation depends not on L _sa but on L _sc which can define the approximate size of the element. Specifically, when the L _{sc of} the regular pentagonal, regular hexagonal, regular octagonal, and regular dodecagonal semiconductor light emitting elements is 500 μm or more, any element separation was easy. Further, when the thickness is 550 μm or more, the occurrence of damage to the element itself and the yield reduction due to this are reduced. Further, when L _sc is 600 μm or more, the occurrence of chipping or the like due to the braking process is reduced. In the present invention, since light is extracted from the side wall of the semiconductor light emitting element, it is technically significant to suppress the occurrence of chipping in the outer shape of the chip.

That is, it is preferable that the lower limit of the _{L sc} where _{t s} is relatively thin is 500μm or more, more preferably at least 550 .mu.m, it has been further Konomashika' is 600μm or more.

On the other hand, scribing, breaking, the upper limit of the thickness t _s of the GaN substrate capable of carrying out isolation process by a simple method such as dicing was 5500Myuemu. In this case, an element isolation method such as dicing is effective. Thus, even if t _s is thick, was found to be good isolation is large L _sc.

However, if L _sc is excessively large, it was found that the peeling from the dicing sheet becomes difficult. Especially when t _s is diced thick GaN substrate of 5500μm and film thickness is necessary to fix the GaN substrate to withstand a load applied to the spindle to the dicing sheet with a sufficient adhesive force is generated, the L _sc When dicing to 7000 μm or less, when the device was peeled from the sheet after dicing, excessive damage was not induced in the device, and the yield reduction was reduced.

Further, when L _sc was 3500 μm or less, partial damage of the element during sheet peeling was reduced, and a good shape could be maintained after element separation. When L _sc was 2800 μm or less, the degree of breakage of the element was further reduced, and many elements having a favorable shape were preferred. When L _sc was 2200 μm or less, extremely good element isolation was possible.

That is, the upper limit of _{L sc} where _{t s} is relatively thick, there generally below 7000Myuemu, preferably equal to or less than 3500, more preferably equal to or less than 2800Myuemu, more preferably was less than 2200Myuemu. These facts were not found in GaAs, GaP, InP, ZnO or the like.

In particular, in the semiconductor light emitting device 10 on the nitride substrate having a planar shape satisfying 500 μm ≦ L _sa ≦ L _sc ≦ 2200 μm, the high-quality semiconductor layer portion is formed on the prepared nitride substrate, and then the substrate is polished. Even without performing such processes as described above, it was possible to easily perform good element isolation.

In particular, the lower limit of the above formula is more preferable when 550 μm or more is satisfied, and is most preferable when 600 μm or more is satisfied. The upper limit of the above formula is more preferably 2100 μm or less, and most preferably 2000 μm or less.

[Light distribution characteristics of the element of the present invention]
Next, the light distribution characteristics of the semiconductor light emitting device in the present invention will be described in detail.

The semiconductor light emitting device preferably has an anisotropic internal light emission profile as described above.

That is, the emission intensity density distribution with respect to the internal emission direction (θ _em ) of this semiconductor light emitting device is not isotropic. The direction of the dipoles arranged in the quantum well layer portion inherent in the active layer structure is isotropic, and as a result, the direction of internal light emission is anisotropic.

Further, since the light emitted in the direction close to the direction showing the maximum internal light emission intensity density is not suppressed by the effect of excessive multiple interference or the like, it becomes anisotropic.

The direction (θ _{em max} ) having the maximum value of internal light emission is a direction close to the parallel direction of the active layer structure, as shown in FIG. 8A. The direction (θ _{em max} ) giving the maximum value of internal light emission varies depending on the material constituting the semiconductor layer portion, the structure of each layer, the electrode material, and the structure thereof.

Specifically, the first conductive semiconductor layer constituting the semiconductor layer portion, the active layer structure including the quantum well active layer and the barrier layer, the second conductive semiconductor layer, the contact layer, various structures that can be arbitrarily introduced, It varies depending on the constituent material of the first conductivity type side electrode, the constituent material of the second conductivity type side electrode, the structure thereof, and the like. Furthermore, θ _{em max} can be changed most strongly when the active layer structure is a quantum well active layer structure, such as the refractive index difference between the quantum well layer and the barrier layer, the number of quantum wells, the thickness of the quantum well layer, etc. These are the elements that govern the thin film interference effect in the layer structure and the thin film interference effect of the second conductivity type semiconductor layer that can define the optical path length of the internal emission reflected by the second conductivity type side electrode.

Therefore, when these conditions are studied as variables in the semiconductor layer on the nitride substrate, the present inventors have found that θ _{em max} can be changed in a range of 67.5 degrees ≦ θ _{em max} <90 degrees. It was. This is simultaneously −90 degrees <θ _{em max} ≦ −67.5 degrees. This range is a preferred range of the present invention.

As a result, the following can be understood regarding the external light emission profile that can be actually measured.

Assume that the peripheral medium of the semiconductor light emitting element is vacuum or air. That is, it is assumed that the semiconductor light emitting device of the present invention is installed in a peripheral medium with n _out (λ) = 1. At this time, it is preferable to eliminate factors that hinder accurate measurement, such as a state in which there is no effective disturbance, that is, the presence of an object that reflects the emitted light.

As shown in FIG. 8A, the external light emission direction is φ _em, and also regarding φ _em , the direction perpendicular to the main surface and the light extraction direction is 0 degree, similarly to the internal light emission direction. One direction parallel to the direction is 90 degrees, and the direction opposite to the 90 degree direction is -90 degrees.

As shown in FIG. 8A, the light emitted in the direction with the highest internal emission intensity density and transmitted through the sidewall of the semiconductor light emitting element defines the direction with the highest external emission intensity density (φ _{em max} ) in accordance with Snell's law. It will be.

Note that in external light emission, the dipole orientation is different from isotropic internal light emission, and there is anisotropy of the shape of the semiconductor light emitting element, and therefore, the angle formed by the projection of the reference direction on the main surface and the light emission direction. Although dependence also occurs on the azimuth angle, it is not as significant as the dependence on _φem . However, in the present invention, the anisotropy of the shape of the semiconductor light emitting element is, for example, that the projected shape of the element is a substantially triangular shape, and therefore includes any one vertex and is external within a plane perpendicular to the main surface of the substrate. The value differs depending on whether the light emission intensity density is measured or the external light emission intensity density is measured in a plane perpendicular to the main surface of the substrate without including the apex. In the present invention, regarding the azimuth angle reflecting the anisotropy of the shape of the semiconductor light emitting device, the following characteristics can be confirmed in a plane perpendicular to the main surface of the substrate at at least one azimuth angle. In some cases, it is preferable that observation is possible at a plurality of azimuth angles. Furthermore, it is most preferable that observation is possible at all azimuth angles.

In the present invention, in the side wall portion of the semiconductor light emitting element, the side wall portion through which light emitted in the direction having the maximum value of the internal light emission intensity density is transmitted is substantially perpendicular to the substrate main surface or the active layer direction ( (Including β≈0 degrees, which will be described later) includes errors that can be actually measured, side wall roughness, fluctuations due to chipping, etc.
It was found that 32.5 degrees ≦ φ _{em max} <90.0 degrees. This is simultaneously −90.0 degrees <φ _{em max} ≦ −32.5 degrees.

Therefore, the semiconductor light emitting device according to the present invention can extract light traveling in the direction of high internal light emission intensity density from the side wall portion of the semiconductor light emitting device. Therefore, when arranged in a medium of n _out (λ) = 1, as described above The light distribution characteristic having the maximum value of the external light emission intensity density in the range is exhibited. For example, when θ _{em max} is 80 degrees, the refractive index of the GaN substrate is 2.52 using the value of the wavelength of 400 nm from Table 1, and from Snell's law, φ _{em max} is about 64 degrees. Is equivalent to

Therefore, in the present invention, θ _{em max} indicating the maximum value of the internal light emission intensity density can be preferably changed within the range of 67.5 degrees ≦ θ _{em max} <90 degrees. The direction of the maximum value is 32.5 degrees ≦ φ _{em max} <90.0 degrees. This is also −90.0 degrees <φ _{em max} ≦ −32.5 degrees. This range is a preferred range of the present invention. A semiconductor light emitting device having such an external light emission profile has a higher intensity of light emitted from the side wall than light emitted from the main surface of the substrate, and is defined by an angle having, for example, half the maximum value of light distribution intensity. It can be suitably used for a light emitting device or a lighting device having a wide light distribution angle. In other words, when the structure does not sufficiently pass through the substrate side wall surface, the light distribution characteristic having such an external light emission profile cannot be obtained, and the characteristic has a maximum value in the vicinity of φ _em = 0 degrees.

[About mold with sealing material]
Referring to FIGS. 1A and 1B again.

In the present invention, the encapsulant 106 may be made of the following materials: silicone encapsulant (1.25 ≦ n _out (λ) ≦ 1.53), high refractive index silicone composition encapsulant (1.45 ≦ n _out (λ) ≦ 1.8) or glass sealant (1.55 ≦ n _out (λ) ≦ 2.10). Such a material is preferable for further improving the light extraction efficiency.

In addition, it is also preferable that wavelength converting particles such as a phosphor are placed in the sealing material, and at least a part of the wavelength of light emitted from the semiconductor light emitting element is converted to another wavelength. Even in such a case, it is preferable that the light-emitting element of the present invention satisfies Expression 1 and Expression 8 (in Expression 1 (a), n _out (λ) = 1).

Among such encapsulants, preferred silicone encapsulants (1.25 ≦ n _out (λ) ≦ 1.53), high refractive index silicone composition encapsulants (1.45 ≦ n _out (λ) ≦ 1). .80) and a glass sealing material (1.55 ≦ n _out (λ) ≦ 2.10).

“Silicone-based encapsulant” refers to an encapsulant made of silicone material. This silicone material usually refers to an organic polymer having a siloxane bond as the main chain, and for example, a silicone material such as a condensation type, an addition type, an improved sol-gel type, and a photo-curing type can be used.

Examples of the condensation type silicone material include a compound having a Si—O—Si bond obtained by hydrolysis and polycondensation of an alkylalkoxysilane at a crosslinking point. Condensation-type silicone materials have excellent adhesion to components such as packages, electrodes, and light-emitting elements used in semiconductor light-emitting devices, so the addition of adhesion-improving components can be minimized, and crosslinking is mainly due to siloxane bonds. There is an advantage of excellent heat resistance and light resistance. Since the condensed silicone material essentially contains the polar group described later, in the semiconductor light emitting device having a structure that expects the light extraction effect from the side surface of the substrate as in the present invention, the side surface of the thick film substrate Since the adhesiveness is also good, it is preferable in that it produces a synergistic effect on the light extraction effect as a whole. In the case of a large chip where the present invention is relatively large, it is particularly preferable from the above viewpoint.

Examples of such condensation-type silicone materials include Japanese Patent Application Publication No. 2007-112973, Japanese Patent Application Publication No. 2007-112974, Japanese Patent Application Publication No. 2007-112975, and Japanese Patent Application Publication No. 2007-19459. The members for semiconductor light emitting devices described in Japanese Patent Laid-Open No. 2008-34833 and the like can be used.

The addition type silicone material refers to a material in which a polyorganosiloxane chain is crosslinked by an organic addition bond. A typical example is a compound having a Si—C—C—Si bond at a crosslinking point obtained by reacting vinylsilane and hydrosilane in the presence of an addition catalyst such as a Pt catalyst. The addition-type silicone material has advantages such as a high degree of freedom in selection such as the curing speed and hardness of the cured product, no component that is detached during curing, hardly shrinking by curing, and excellent deep-part curability. Addition-type silicone materials are essentially free of the polar groups described below, but the polar groups are introduced into the skeleton, adhesion improving components having polar groups are added, or primers are interposed. Thus, the adhesion with the chip can be enhanced.

With such a technique, in the semiconductor light emitting device having a structure that expects the light extraction effect from the side surface of the substrate as in the present invention, the adhesion on the side surface of the thick film substrate is also good, and thus synergistically with the light extraction effect. It is preferable at the point which produces an effect. In the case of a large chip where the present invention is relatively large, it is particularly preferable from the above viewpoint.

Examples of such addition-type silicone materials include potting silicone materials described in Japanese Patent Application Laid-Open No. 2004-186168, Japanese Patent Application Laid-Open No. 2004-221308, Japanese Patent Application Laid-Open No. 2005-327777, and the like. Organically modified silicone material for potting described in Japanese Patent Application Laid-Open No. 2003-183881, Japanese Patent Application Laid-Open No. 2006-206919, etc., Silicone material for injection molding described in Japanese Patent Application Laid-Open No. 2006-324596, Japan A silicone material for transfer molding described in JP-A-2007-231173 can be suitably used.

Further, as an improved sol-gel type silicone material which is one of the condensation types, for example, Japanese Unexamined Patent Publication No. 2006-077234, Japanese Unexamined Patent Publication No. 2006-291018, Japanese Unexamined Patent Publication No. 2007-119509, etc. Can be suitably used. The improved sol-gel type silicone-based material has a high degree of crosslinking, heat resistance, light resistance and excellent durability. In the case where the present invention is a large chip having a relatively large size, it is preferable from the viewpoints of heat resistance, light resistance and durability.

As the photocurable silicone material, for example, silicone materials described in Japanese Patent Application Laid-Open No. 2007-131812, Japanese Patent Application Laid-Open No. 2007-214543 and the like can be suitably used. The photo-curing type silicone material has advantages such as excellent productivity because it is cured in a short time, and it is not necessary to apply a high temperature for curing, and the light-emitting element is hardly deteriorated. In the case where the present invention is a large chip having a relatively large size, in addition to the above-mentioned advantages, a high temperature is not required at the time of curing. To preferred.

These silicone materials may be used alone, or a plurality of silicone materials may be mixed and used as long as they do not inhibit curing by mixing.

Moreover, in order to make the said silicone type sealing material high refractive index, it mixes with nanoparticles, such as a zirconia and a titania, and high refractive index silicone composition sealing material (1.45 <= _nout ((lambda)) <= 1). .8). In this case, for the purpose of improving adhesion and dispersibility between the nanoparticle and the silicone-based material, the nanoparticle is an organic acid or silane cup having a ligand that easily reacts with a metal on the nanoparticle surface such as a carboxyl group. It is preferable to use after surface treatment with a ring agent, a hydrolyzate / partial hydrolyzate thereof, a silicone oil / silicone resin such as polysiloxane having a hydrolyzable group or a silanol group. In addition, when the nanoparticles such as titania have a photocatalytic action, a coating layer containing silicon oxide may be provided on the nanoparticle surface in order to prevent deterioration of surrounding organic substances.

Here, coating with these coating layers means both a form in which the nanoparticle surface is completely covered or a form in which a gap is left.

As the high refractive index silicone composition sealing material, for example, a semiconductor light emitting device sealing composition described in Japanese Patent Application Laid-Open No. 2007-27099 can be used.

The silicone-based encapsulant preferably has the following characteristics in order to improve the adhesion to the semiconductor light emitting element.
1) containing polar groups at the interface with other layers;
2) Hardness is 5 or more and 100 or less at Shore A, or 0 or more and 85 or less at Shore D.

Hereinafter, these characteristics will be described.
Characteristic 1): Polar group When the sealing material is peeled off between the semiconductor light emitting elements due to light, heat, physical action, etc., the light maintenance rate of the semiconductor light emitting device is lowered. This is a very important factor in a semiconductor light emitting device having a structure that expects a light extraction effect from the side surface of the substrate as in the present invention. Therefore, it is important that they are in close contact with each other.

Therefore, the sealing material used in the present invention preferably contains a polar group at the interface with the adjacent layer. That is, the encapsulant contains a compound having a polar group so as to have a polar group at the interface with the adjacent semiconductor light emitting element. There is no limitation on the type of such a polar group. For example, silanol groups, amino groups and derivatives thereof, hydrolyzable silyl groups such as alkoxysilyl groups, carbonyl groups, epoxy groups, carboxy groups, carbinol groups (- COH), methacryl group, cyano group, sulfone group and the like. In addition, the sealing material may contain only any 1 type of polar group, and may contain 2 or more types of polar groups by arbitrary combinations and ratios. These polar groups may be contained in the sealing material from the beginning, or may be added later by primer application or surface treatment.

Characteristic 2): Hardness measurement value The hardness measurement value is an index for evaluating the hardness of the sealing material used in the present invention, and is measured by the following hardness measurement method.
The sealing material used in the present invention is preferably a member having a relatively low hardness, preferably an elastomeric member. That is, in the present invention, a plurality of types of members having different thermal expansion coefficients, ie, a semiconductor light emitting element and a sealing material are adjacent to each other, but the sealing material has a relatively low hardness, and preferably exhibits an elastomeric shape. The stress due to expansion and contraction of each member can be relaxed. Therefore, it is possible to obtain a semiconductor light emitting device that is less likely to be peeled, cracked, disconnected, etc. during use and that has excellent reflow resistance and temperature cycle resistance. Specifically, the translucent coating layer has a durometer type A hardness measurement value (Shore A) of 5 or more, preferably 7 or more, more preferably 10 or more, and usually 100 or less, preferably 80 or less. More preferably, it is 70 or less. Or the hardness measurement value (Shore D) by durometer type D is 0 or more, and usually 85 or less, preferably 80 or less, more preferably 75 or less.

The glass sealing material refers to a sealing material made of an inorganic material such as silicon oxide, silicon nitride, or silicon oxynitride, and a glass material such as borosilicate, phosphosilicate, or alkali silicate. When the glass material in the present invention is used, it can be produced, for example, by melting and curing crushed glass. As the glass material, the yield point is usually 700 ° C. or lower, preferably 600 ° C. or lower, more preferably 500 ° C. or lower, still more preferably 400 ° C. or lower, and usually 200 ° C. or higher, preferably 250 ° C. or higher. If the yield point is too large, the temperature becomes too high during sintering, which may cause deterioration of the semiconductor light emitting device. In addition, when phosphors are mixed and used, the phosphors may be deteriorated or the emission characteristics of the phosphors may be lowered due to the reaction between the phosphors and the glass composition. If the yield point is too small, the stability of the coating is lowered, and there may be a problem that the product is softened during use.

The carbon component of the glass used in the present invention is usually 100 ppm or less, preferably 60 ppm or less, more preferably 30 ppm or less, and particularly preferably 10 ppm or less. Since there is a possibility that colorless transparency cannot be sufficiently secured if there are too many carbon components, the smaller the carbon components, the better. As a method for reducing the carbon component, a method using a glass obtained in advance through melting, curing, and pulverizing steps is preferable.

Glass encapsulant is easy to increase the refractive index, has high light extraction efficiency from the chip, does not contain organic components, has excellent heat resistance and light resistance, has a dense structure and low gas permeability, so it can be used for chip and fluorescent. There is an advantage that the body can be protected from deterioration due to water vapor or oxygen. In the case where the present invention is a large chip having a relatively large size, it is particularly preferable from the above viewpoint.

Other materials used for the sealing material include organic materials. Examples of organic materials include thermoplastic resins, thermosetting resins, and photocurable resins. Specifically, for example, methacrylic resin such as polymethylmethacrylate; styrene resin such as polystyrene and styrene-acrylonitrile copolymer; polycarbonate resin; polyester resin; phenoxy resin; butyral resin; polyvinyl alcohol; And cellulose resins such as cellulose acetate butyrate; epoxy resins; phenol resins and the like.

Example 1
[The planar shape of the semiconductor light emitting device is triangular]
EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention should not be construed as being limited by the specific examples shown below.
10A is a graph showing characteristics of the semiconductor light emitting device according to the present invention manufactured as Example 1. FIG. In this example, a planar shape triangular, nitride substrate, a semiconductor layer, a semiconductor light emitting device where the maximum thickness t _emax of the electrode portion is mounted a semiconductor light-emitting device (no mold) is about 822μm (D _p is about 1280μm And a semiconductor light emitting device molded with a sealing material. The refractive index of the sealing material was 1.42, and the height (X _ph ) of the sealing material was 1.5 mm.

In the semiconductor light-emitting device after molding, although t _emax <D _p , when viewed in the air from the direction perpendicular to the direction in which the substrate main surface faces, A part of the side wall of the semiconductor light emitting device was visible. Further, as shown in FIG. 10C (a), improvement in characteristics was observed at any current value.

On the other hand, FIG. 11 shows the light distribution characteristic measurement results of another semiconductor light emitting element having the same design as the semiconductor light emitting element used when the semiconductor light emitting device was produced. In this measurement, a semiconductor light-emitting element was mounted on a flat surface to enable current introduction. In other words, this is a result obtained for measuring the characteristics of the semiconductor light emitting device itself. In FIG. 11, line (a) is a case where the measurement direction includes the center of gravity of the equilateral triangle and is parallel to one side of the equilateral triangle, and in FIG. 11, line (b) shows the measurement direction of the equilateral triangle. This is a case where one vertex of the triangle is included and the direction is perpendicular to one side of the regular triangle. In any direction, it can be seen that the absolute value of the light distribution angle has two peaks in the direction from 45 degrees to 50 degrees instead of 0 degrees. That is, it can be seen that the emission from the semiconductor light emitting device of the present invention is mainly in the lateral direction.

Further, the characteristic indicated by a solid line in FIG. 12 is a light distribution characteristic after completion of the semiconductor light emitting device in which the semiconductor light emitting element is incorporated (after molding). Here, when the “light distribution angle” indicating the characteristic in the light distribution characteristics is defined as 50% of the maximum intensity, the light distribution angle in the first embodiment is about 160 degrees, and a very wide light distribution angle is realized. I understand that.

Next, the phosphor molded body and the convex portion of the semiconductor light emitting device are separated from each other in the spherical shell-shaped phosphor molded body having a diameter of 5 cm and a thickness of 1 mm. FIG. 13 and FIG. 14 show the results of simulation of the light distribution characteristics of the phosphor-converted light when the phosphor molded body is arranged so as to cover the convex portion. 13 is a simulation result when the correlated color temperature of the phosphor converted light is 2900K, and FIG. 14 is a simulation result when the correlated color temperature of the phosphor converted light is 4300K. Here, the simulation uses the Monte Carlo ray tracing method by LightTools Ver 7.1 (manufactured by ORA), and the phosphor in the phosphor molding is modeled as a point where constant scattering, absorption, and light emission occur. ing. As is apparent from FIGS. 13 and 14, it was found that by using the semiconductor light emitting device of Example 1, it is possible to realize a white light emitting module capable of emitting light at a wide angle and backward.

(Example 2)
[The planar shape of the semiconductor light-emitting element is hexagonal]
FIG. 10B is a graph showing characteristics of the semiconductor light emitting device according to the present invention manufactured as Example 2. In this example, the planar shape is a hexagon, and the nitride substrate, the semiconductor layer, and the maximum thickness of the electrode portion A semiconductor light-emitting device (Dp is about 1280 μm) on which a semiconductor light-emitting element (no mold) having a t _emax of about 822 μm and a semiconductor light-emitting device molded with a sealing material were manufactured. As above, the refractive index of the sealing material was 1.42, and the height (X _ph ) of the sealing material was 1.5 mm.

In the semiconductor light-emitting device after molding, although t _emax <D _p , when viewed in the air from the direction perpendicular to the direction in which the substrate main surface faces, A part of the side wall of the semiconductor light emitting device was visible. Further, as shown in FIG. 10C (b), improvement in characteristics was observed at any current value.

(Comparative Example 1)
A semiconductor light emitting device in which a triangular semiconductor light emitting element having a planar shape similar to that of Example 1 was mounted and molded with a sealing material was produced. A semiconductor light emitting device was produced in the same manner as in Example 1 except that the height (X _ph ) of the sealing material was changed to a hemispherical shape of 4.0 mm.

When the semiconductor light emitting device according to Comparative Example 1 is viewed in air from a direction perpendicular to the direction in which the main surface of the substrate faces, a part of the side wall of the semiconductor light emitting element is formed through the convex portion of the sealing material. It was not possible to see. The light distribution characteristics of Comparative Example 1 are indicated by dotted lines in FIG. The semiconductor light emitting device according to the comparative example 1 cannot take advantage of the wide light distribution characteristics derived from the semiconductor light emitting element due to the shape of the sealing material, and has a light distribution angle as compared with the first example. It was narrow at about 120 degrees.

Next, as in Example 1, the semiconductor light-emitting device having the light distribution characteristics of Comparative Example 1 was placed in a spherical shell-shaped phosphor molded body having a diameter of 5 cm and a thickness of 1 mm. FIGS. 13 and 14 show the results of simulation of the light distribution characteristics of the phosphor-converted light when the convex portion of the apparatus is spaced apart and the phosphor molding is disposed so as to cover the convex portion. Similar to the previous Example 1, the simulation was performed using the Monte Carlo ray tracing method by LightTools Ver 7.1 (manufactured by ORA), and the phosphor in the phosphor molded body had a certain amount of scattering, absorption, It is modeled as what causes luminescence. As is apparent from FIGS. 13 and 14, when the semiconductor light emitting device of this comparative example 1 is used, the light emission distribution in the wide angle / rear direction is weaker than when the semiconductor light emitting device of example 1 is used. I found out.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on April 9, 2010 (Japanese Patent Application No. 2010-090422) and a Japanese patent application filed on March 30, 2011 (Japanese Patent Application No. 2011-076199). Incorporated herein by reference.

According to the present invention, the light extraction and light distribution characteristics of the chip that mainly emits light in the lateral direction can be utilized to the maximum, and therefore, it can be suitably used in the field of illumination devices and image display devices.

DESCRIPTION OF SYMBOLS 1 Semiconductor light-emitting device 10 Semiconductor light emitting element 12 Substrate 12a Substrate surface 15 Semiconductor layer part 16 Active layer structure 17 1st conductivity type semiconductor layer 18 2nd conductivity type semiconductor layer 21 Substrate main surface 31 Quantum well layer 33 Barrier layers 27a and 27b Electrode 101 Submount 102a, 102b Bump 103 Package part 104 Recessed part 105a Package part side wall 105b Package part bottom face 106 Sealant 131-133 area

Claims (10)

1. A semiconductor light emitting device having a semiconductor light emitting element, a case portion for mounting the semiconductor light emitting element, and a sealing material,
   The semiconductor light emitting device has a substrate, a semiconductor layer portion including an active layer structure that emits light, and an electrode portion, and the maximum physical thickness of the entire semiconductor light emitting device is _temax ,
   The case portion has a recess for enclosing the semiconductor light emitting element, and a depth D _{p of the} recess to the semiconductor light emitting element mounting surface satisfies t _emax <D _p ,
   The sealing material is disposed in contact with at least a part of the semiconductor light emitting element and a part of the case part,
   The semiconductor light emitting element is mounted such that the opening direction of the concave portion of the case portion and the direction in which the substrate main surface faces are substantially the same direction,
   The sealing material is formed so as to have a convex portion with respect to the direction in which the main surface of the substrate faces.
   When the semiconductor light emitting device is viewed in the air in a direction perpendicular to the direction in which the main surface of the substrate faces, at least a part of the side wall of the semiconductor light emitting element through the convex portion of the sealing material Is visible,
   Semiconductor light emitting device.
2. The semiconductor light emitting device according to claim 1, wherein a maximum physical thickness t _t of the substrate and the semiconductor layer portion of the semiconductor light emitting element is 150 μm or more.
3. The semiconductor light-emitting device according to claim 1, wherein the substrate satisfies Formula 1 below.
   Formula 1
   L _sc × tan {sin ⁻¹ (1 / n _s (λ))} ≦ t _s
   ≦ L _sc × tan {90−sin ⁻¹ (1 / n _s (λ))}
   (However,
   λ represents the peak wavelength (nm) of light emitted from the semiconductor light emitting device,
   t _s represents the maximum physical thickness of the substrate;
   L _sc represents the longest line segment length formed by any two points on the main surface of the substrate;
   n _s (λ) represents the refractive index of the substrate at the wavelength λ. )
4. The semiconductor light emitting element is
   The light emitting element is in an arbitrary plane perpendicular to the main surface of the substrate in which the light emitting element is present, and the direction to be the light extraction direction is 0 degree, and one direction parallel to the main surface is 90 degrees, opposite to the 90 degree direction. When the light distribution characteristics are measured in a state where the direction is set to −90 degrees, the light emitting element is installed in the air, and there is effectively no disturbance,
   From the direction φ _{em max} indicating the maximum value of the external light emission intensity density, the direction θ _{em max} indicating the maximum value of the internal light emission intensity density inside the semiconductor light emitting element obtained using Snell's law is at least one of the following expressions: The semiconductor light-emitting device according to any one of claims 1 to 3, wherein a plane that satisfies one of the planes exists.
   −90.0 degrees <θ _{em max} ≦ −67.5 degrees 67.5 degrees ≦ θ _{em max} <90.0 degrees
5. The semiconductor light emitting element is
   The light emitting element is in an arbitrary plane perpendicular to the main surface of the substrate in which the light emitting element is present, and the direction to be the light extraction direction is 0 degree, and one direction parallel to the main surface is 90 degrees, opposite to the 90 degree direction. When the light distribution characteristics are measured in a state where the direction is set to -90 degrees, the element is installed in the air, and there is effectively no disturbance,
   The plane having light distribution characteristics in which the direction φ _{em max} indicating the maximum value of the external light emission intensity density emitted from the light emitting element satisfies at least one of the following formulas exists: The semiconductor light-emitting device of any one of these.
   −90.0 degrees <φ _{em max} ≦ −32.5 degrees 32.5 degrees ≦ φ _{em max} <90.0 degrees
6. 6. The semiconductor light emitting device according to claim 1, wherein the substrate is made of nitride.
7. The depth D _p of the concave portion of the case portion to the semiconductor light emitting element mounting surface is
   500 μm ≦ D _p ≦ 5 mm
   The semiconductor light-emitting device according to any one of claims 1 to 6, wherein:
8. The physical height of the convex portion formed by the sealing material with respect to the opening direction of the concave portion of the case portion is formed in a convex shape from the case portion and from a direction perpendicular to the direction in which the substrate main surface faces. It is defined as the physical height X _{ph of the} encapsulant part that can be expected,
   Let X _{op be the} optical height corresponding to this,
   The peak wavelength of light emitted from the semiconductor light emitting element is λ (nm),
   When the refractive index at the wavelength λ of the sealing material is n _m (λ),
   The semiconductor light-emitting device according to claim 1, wherein any one of the following formulas is satisfied.
   800 (μm) ≦ X _ph ≦ 1900 (μm) Equation 2
   1040 (μm) ≦ X _op ≦ 3420 (μm) Equation 3
   1.3 ≦ n _m (λ) ≦ 1.8 Equation 4
9. When the semiconductor light emitting device is observed in the air from the opening direction of the recess of the case portion in the air,
   9. The physical length a of an arbitrary portion of the projected shape of the semiconductor light emitting element, and the visually recognized length b of the corresponding portion satisfy the following relationship: Semiconductor light emitting device.
   1 ≦ b / a <1.25
10. A light emitting module comprising: the semiconductor light emitting device according to any one of claims 1 to 9; and a phosphor layer including a phosphor that emits fluorescence when excited by light emitted from the semiconductor light emitting element. The light emitting module, wherein the body layer is disposed so as to be separated from the convex portion and cover the convex portion.

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