JP7228120B2 - Light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device.

In recent years, the use of light irradiation devices using solid-state light source elements such as LEDs is expanding in place of discharge lamps. In such a light irradiation device, for example, a light source section is configured using a plurality of LED elements.

The discharge lamp has a high luminous intensity per light source area and achieves high brightness. On the other hand, a solid-state light source element such as an LED has a lower brightness than a discharge lamp, and since it is surface emitting, it is difficult in principle to increase the brightness.

For example, Patent Literature 1 below discloses a technique for increasing luminance when a discharge lamp is used. This discharge lamp has an ellipsoidal reflector on the back side of the light source, and the light source is arranged at the first focal point of the ellipsoidal reflector, and light is condensed on the second focal point. A spherical reflecting mirror is provided on the front side of the light source body, and the light emitted forward of the light source body is returned to the bright spot again via the spherical reflecting mirror. With such a configuration, all the light from the light source is collected at the second focal point via the ellipsoidal reflecting mirror, whereby all the emitted light can be collected within the same viewing angle, and high brightness can be achieved.

JP-A-6-250288

However, the method of Patent Document 1 cannot be used for surface emission when the light source is a solid-state light source element such as an LED element. An object of the present invention is to realize a light irradiation device including a semiconductor light emitting device and having higher luminance than conventional ones.

A light irradiation device according to the present invention includes a semiconductor light emitting device.
The semiconductor light emitting device is
a substrate;
a semiconductor layer formed on the substrate and including a first semiconductor layer of n-type or p-side, an active layer, and a second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light absorbing electrode made of a material that absorbs light having the same wavelength as the light emitted from the active layer, the light absorbing electrode being electrically connected to the first semiconductor layer;
Light extraction configured by either a surface of the substrate located on the opposite side to the semiconductor layer or a surface of the semiconductor layer located on the opposite side to the substrate. It is an upper layer of the surface and is formed of a material that reflects light of the same wavelength as light emitted from the active layer, which is formed at a position facing the light-absorbing electrode in a direction orthogonal to the surface of the substrate. and a reflective layer.
The light irradiation device is further arranged so as to surround an axis orthogonal to the light extraction surface of the semiconductor light emitting element, and is a mirror for returning part of the light emitted from the light extraction surface to the reflection layer. have a department.

A semiconductor light emitting device requires an electrode for supplying current to the semiconductor layer. A material for the electrode electrically connected to the first semiconductor layer is selected from the viewpoint of reduction in contact resistance, stability of the material, and the like. However, many of such materials absorb light of the same wavelength as the light emitted from the active layer. As an example, such an electrode is made of Au or an alloy containing Au. In this specification, an electrode that absorbs light having the same wavelength as light emitted from the active layer is referred to as a "light absorbing electrode".

In a semiconductor light-emitting device having a light-absorbing electrode, a non-light-emitting region is a region on the light-extracting surface where the light-absorbing electrode is formed at a position facing the surface in a direction orthogonal to the surface. Therefore, in the conventional light emitting device, the entire light extraction surface cannot emit light.

By the way, a semiconductor light emitting device is housed in a predetermined case or used in combination with various optical systems for guiding light to an application that uses the emitted light. Therefore, when the semiconductor light emitting device is used in a normal state, part of the light emitted from the active layer is reflected by the surfaces of the case and the optical system. This reflected light constitutes return light guided to the light extraction surface side of the semiconductor light emitting element.

In the semiconductor light emitting device having the above configuration, a reflective layer is formed on the light extraction surface and at a position facing the light absorbing electrode in a direction orthogonal to the surface of the substrate. Therefore, when part of the return light is incident on a portion where a non-light-emitting region is formed in a conventional light-emitting element, it is reflected by the reflective layer and emitted from the element again. In other words, in the conventional light-emitting element, the portion forming the non-light-emitting region constitutes the light-emitting region. As a result, a light-emitting element with higher luminance than conventional ones is realized.

By the way, in the field of semiconductor light emitting devices, there is known a configuration in which a reflective electrode is provided at a position closer to the active layer than the light extraction surface, that is, in the internal region of the light emitting device. Even when such a configuration is adopted, when the return light is generated, it can be reflected by the reflective electrode so that the light can be guided in the extraction direction. Seem. However, in the case of such a configuration, since a non-light-emitting area still exists on the light extraction surface side, the effect of improving the luminance on the light-emitting surface is low. In order to reflect light on the surface of the reflective electrode, the return light is led from the light extraction surface to the reflective electrode via the semiconductor layer, reflected by the surface of the reflective electrode, and then reversed. It must be taken out via the same optical path in the same direction, and light absorption can occur in this process.

According to the configuration of the present invention, since the reflective layer is provided on the light extraction surface, the non-light-emitting region can be changed to the light-emitting region, and the return light is absorbed before it is extracted again. The amount of light is lower than in the above configuration with the reflective electrode. As a result, a light-emitting element with higher luminance than conventional ones is realized.

Here, the reflective layer formed on the upper layer of the light extraction surface may be arranged so as to have a rotationally asymmetric shape with respect to the direction parallel to the light extraction surface. According to such a configuration, part of light emitted from a region of the light extraction surface that is not opposed to the light absorption electrode in a direction orthogonal to the surface of the substrate is directed to the light absorption electrode by the substrate. It becomes easy to return to the position facing the direction perpendicular to the surface of the reflective layer, that is, the position where the reflective layer is formed. As a result, the effect of increasing the luminance is improved.

It is preferable that the reflective layer is made of a material having a reflectance of 40% or more with respect to light having the same wavelength as the light emitted from the active layer. Further, the reflectance is more preferably 60% or higher, and even more preferably 90% or higher.

For example, when the wavelength of light emitted from the active layer is in the ultraviolet region of 410 nm or less, the reflective layer is made of at least one of Al, Ag, Cu, Ni, Pt, Rh, Cr, and Co. It can be made up of materials including: The material forming the reflective layer can be appropriately selected according to the wavelength band of light emitted from the active layer.

The semiconductor light emitting device may be configured to include a first protective layer formed on the reflective layer and made of a material that transmits light emitted from the active layer.

With such a configuration, the reflective surface of the reflective layer is prevented from being exposed to the atmosphere, so the material constituting the reflective layer is less likely to be oxidized or sulfurized, and the decrease in reflectance over time is suppressed. be done. In addition, according to this configuration, it becomes possible to use a material with relatively low stability (such as an alloy containing Ag) as the reflective layer, increasing the degree of freedom in material selection.

the light extraction surface is formed of a surface of the first semiconductor layer located on the side opposite to the substrate;
The light absorption electrode may be formed on the upper layer of the first semiconductor layer. In this case, the semiconductor light emitting device may be configured to include a reflective electrode formed in contact with a surface of the second semiconductor layer opposite to the active layer.

As a result, in a semiconductor light emitting device having a so-called vertical structure, luminance can be increased as compared with the conventional one.

A plurality of the light absorption electrodes may be formed on the upper layer of the first semiconductor layer by extending in a direction parallel to the surface of the substrate. In this case, it is preferable that the reflective layer formed on the light extraction surface has a rotationally asymmetric shape with respect to the direction parallel to the light extraction surface.

The semiconductor light emitting device can include a second protective layer made of a material that transmits light emitted from the active layer, between the first semiconductor layer and the light absorbing electrode.

If the light-absorbing electrode is made of a material with low stability, the electrode material may diffuse (eg, migrate) into the reflective layer and reduce the reflectance of the reflective layer. According to the above configuration, the diffusion of the electrode material toward the reflective layer is suppressed, so that the reflectance of the reflective layer can be prevented from decreasing with time.

the light extraction surface is formed of a surface of the substrate located on the opposite side of the semiconductor layer;
The semiconductor layer includes a first region formed by stacking the first semiconductor layer, the active layer, and the second semiconductor layer in a direction parallel to the surface of the substrate, and the active layer and the second semiconductor layer. and a second region in which the first semiconductor layer is formed without
The light absorbing electrode may be composed of a first electrode electrically connected to the first semiconductor layer in the second region.

As a result, in a so-called flip chip structure semiconductor light emitting device, the luminance can be increased compared to the conventional one.

When the light extraction surface is configured by a surface of the substrate located on the side opposite to the semiconductor layer,
a reflective electrode formed in contact with a surface of the second semiconductor layer opposite to the active layer;
a recess that penetrates at least the first semiconductor layer and the active layer and reaches the second semiconductor layer;
The light absorbing electrode is formed to be inserted into the recess and contact the first semiconductor layer while maintaining an insulating state between the active layer, the first semiconductor layer, and the reflective electrode. It does not matter if there is

Further, the light extraction surface may be configured by a surface of the first semiconductor layer located on the side opposite to the substrate. In this case:
The semiconductor light emitting device is
a reflective electrode formed in contact with a surface of the second semiconductor layer opposite to the active layer;
a recess that penetrates at least the first semiconductor layer and the active layer and reaches the second semiconductor layer;
The light absorbing electrode is formed to be inserted into the recess and contact the first semiconductor layer while maintaining an insulating state between the active layer, the first semiconductor layer, and the reflective electrode. It does not matter if there is

As a result, in a semiconductor light-emitting device having a so-called via-type structure, luminance can be increased compared to the conventional one.

According to the present invention, a semiconductor light emitting device with enhanced brightness is realized.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically the structure of the semiconductor light-emitting device of 1st embodiment. 2 is a plan view of the semiconductor light emitting device of the first embodiment when viewed from the light extraction surface side; FIG. 2 is a plan view of the semiconductor light emitting device of the first embodiment when viewed from the light extraction surface side; FIG. It is drawing which showed typically an example of the light source part containing a semiconductor light-emitting device. FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 2 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a cross-sectional view schematically showing another configuration of the semiconductor light emitting device of the first embodiment; FIG. 4 is a plan view of another configuration of the semiconductor light emitting device of the first embodiment when viewed from the light extraction surface side; FIG. 4 is a cross-sectional view schematically showing the configuration of a semiconductor light emitting device according to a second embodiment; FIG. 4 is a cross-sectional view schematically showing one step in the method for manufacturing a semiconductor light emitting device according to the second embodiment; FIG. 4 is a cross-sectional view schematically showing one step in the method for manufacturing a semiconductor light emitting device according to the second embodiment; It is drawing which shows typically the structure of the semiconductor light-emitting device of 3rd embodiment. FIG. 10 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the third embodiment; FIG. 10 is a cross-sectional view schematically showing one step in the method for manufacturing the semiconductor light emitting device of the third embodiment; It is drawing which shows typically another structure of the semiconductor light-emitting device of 3rd embodiment.

A semiconductor light emitting device of the present invention will be described with reference to the drawings. In each drawing, the dimensional ratio of the drawing and the actual dimensional ratio do not necessarily match. The manufacturing conditions, film thickness, and other dimensions described below are merely examples, and are not limited to these numerical values.

In this specification, the description “AlGaN” is synonymous with the description Al _m Ga _1-m N (0<m<1), and the description of the composition ratio of Al and Ga is simply omitted. However, the composition ratio of Al and Ga is not limited to 1:1. The same applies to descriptions such as "InGaN".

In this specification, "a certain layer X1 is formed on another layer X2" means that the layer X2 is formed in direct contact with the layer X1, and of course, the layer X2 is formed on another layer X3. It is intended to include the case where it is formed in contact with the layer X1 via the . Additionally, the above description is intended to include configurations in which layer X2 is positioned above layer X1 by rotating the element.

(First embodiment)
A first embodiment of a semiconductor light emitting device will be described.

[structure]
FIG. 1A is a cross-sectional view schematically showing the configuration of the first embodiment of the semiconductor light emitting device of the present invention. The semiconductor light emitting device 1 includes a substrate 3 , a semiconductor layer 5 formed on the substrate 3 , a first electrode 15 , a second electrode 13 , and a reflective layer 31 . Hereinafter, the semiconductor light emitting device 1 may be abbreviated simply as "light emitting device 1".

FIG. 1B is a plan view of the semiconductor light emitting device 1 as viewed from the light extraction surface side. However, illustration of the reflective layer 31 is omitted for convenience of explanation. FIG. 1A corresponds to a cross-sectional view taken along line X1-X1 in FIG. 1B. Hereinafter, the light extraction surface is defined as the XY plane, and the direction perpendicular to the XY plane is defined as the Z direction.

The structure of the light emitting device 1 will be described in detail below.

(Substrate 3)
The substrate 3 is composed of, for example, a conductive substrate such as CuW, W, Mo, or a semiconductor substrate such as Si.

(Semiconductor layer 5)
In this embodiment, the semiconductor layer 5 is formed by stacking a p-type semiconductor layer 11 , an active layer 9 and an n-type semiconductor layer 7 in this order from the side closer to the substrate 3 . In this embodiment, the n-type semiconductor layer 7 corresponds to the "first semiconductor layer", and the p-type semiconductor layer 11 corresponds to the "second semiconductor layer".

The p-type semiconductor layer 11 is composed of a nitride semiconductor layer doped with p-type impurities such as Mg, Be, Zn, or C, for example. For example, GaN, AlGaN, AlInGaN, or the like can be used as the nitride semiconductor layer.

The active layer 9 is composed of a semiconductor layer in which, for example, a light emitting layer composed of InGaN and a barrier layer composed of n-type AlGaN are periodically repeated. These layers may be undoped or doped p-type or n-type. The active layer 9 may be formed by laminating layers made of at least two kinds of materials having different energy bandgaps. The constituent material of the active layer 9 is appropriately selected according to the wavelength of light to be generated. In the light-emitting device 1 of this embodiment, the main emission wavelength in the active layer 9 can be 410 nm or less. For example, when the main emission wavelength is 365 nm, the active layer 9 is formed by laminating In _0.05 Ga _0.95 N and Al _0.09 Ga _0.91 N repeatedly.

The n-type semiconductor layer 7 is composed of a nitride semiconductor layer doped with an n-type impurity such as Si, Ge, S, Se, Sn, or Te. For example, GaN, AlGaN, AlInGaN, or the like can be used as the nitride semiconductor layer. The n-type impurity concentration of the n-type semiconductor layer 7 is set to, for example, approximately 3×10 ¹⁹ /cm ³ . The n-type impurity concentration of the n-type semiconductor layer 7 is preferably 1×10 ¹⁸ /cm ³ or more, more preferably 1×10 ¹⁹ /cm ³ or more, and more preferably 3×10 ¹⁹ /cm ³ or more. It is even more preferred to have

The n-type semiconductor layer 7 may be made of a material having a composition different from that of the p-type semiconductor layer 11 . In the light-emitting device 1 of this embodiment, the n-type semiconductor layer 7 constitutes the light extraction surface 28a.

(First electrode 15)
The first electrode 15 is formed in contact with the surface of the semiconductor layer 5 farther from the substrate 3 . More specifically, the first electrode 15 is formed in contact with the surface of the n-type semiconductor layer 7 .

In this embodiment, the first electrode 15 constitutes an n-side electrode. The first electrode 15 is composed of, for example, a multilayer structure of Ni/Al/Ni/Ti/Au, Cr/Au, Ti/Pt/Au, Ti/Pt/Cr/Au/Cr/Pt/Au, etc. be able to. As the first electrode 15, a material that can form an ohmic contact with the n-type semiconductor layer 7 and has a low contact resistance is preferable, and in addition, a chemically stable material is more preferable. As such a material, an alloy containing Au is suitable as described above.

However, when light with a wavelength of 410 nm or less is emitted from the active layer 9, such a metal material has extremely low reflectance for light in this wavelength band and absorbs most of the incident light. That is, the first electrode 15 constitutes a "light absorption electrode".

By the way, in the present embodiment, as shown in FIG. 1B, the first electrode 15 has a frame shape when viewed in the Z direction (direction perpendicular to the surface of the substrate 3). More specifically, the outer edge of the first electrode 15 is configured to have a frame shape along the outer edge of the semiconductor layer 5 . In the light-emitting element 1 shown in FIG. 1A, two first electrodes extending in the Y direction are provided at two positions inside the outer edge of the frame-shaped first electrode 15 and spaced apart from the outer edge in the X direction. It has an electrode 15 . However, inside the region showing the frame shape, the number of extending first electrodes 15 is not limited to two, and may be one or three or more. The shape of the first electrode 15 shown in FIG. 1B is merely an example, and can be arbitrarily changed according to the design.

The first electrode 15 includes a current supply portion 15a to which the current supply line 14 is connected at some locations. The current supply portion 15a exhibits a wide area compared to the other areas of the first electrode 15 . The current supply line 14 is made of Au, Cu, or the like, for example. The end of the current supply line 14 opposite to the end to which the current supply portion 15a is connected is connected to, for example, a power supply pattern of a package substrate.

(Second electrode 13)
The second electrode 13 is formed in contact with the p-type semiconductor layer 11 and forms an ohmic contact with the p-type semiconductor layer 11 . In this embodiment, the second electrode 13 constitutes a p-side electrode. By applying a voltage between the first electrode 15 and the second electrode 13, current flows in the active layer 9, and the active layer 9 emits light.

The second electrode 13 is preferably made of a conductive material that exhibits a high reflectance (for example, 80% or more, more preferably 90% or more) with respect to light emitted from the active layer 9 . More specifically, the second electrode 13 is made of a material containing Ag, Al, or Rh, for example. The light emitting device 1 shown in FIG. 1A is supposed to extract light emitted from the active layer 9 to the n-type semiconductor layer 7 side. Since the second electrode 13 is made of a material exhibiting a high reflectance, the light emitted from the active layer 9 toward the substrate 3 is reflected toward the n-type semiconductor layer 7, so that the light extraction efficiency is improved. Increased. At this time, the second electrode 13 constitutes a "reflective electrode".

For the first electrode 15, unlike the second electrode 13, it is difficult to select a conductive material that exhibits a high reflectance with respect to light emitted from the active layer 9 (and light of the same wavelength). This is because there is a narrower selection range of materials that can achieve ohmic contact with the n-type semiconductor layer 7 than materials that can achieve ohmic contact with the p-type semiconductor layer 11 .

(Conductive layer 20)
The conductive layer 20 is formed on the upper layer of the substrate 3 . In this embodiment, the conductive layer 20 has a multi-layer structure including a protective layer 23 , a bonding layer 21 , a bonding layer 19 and a protective layer 17 .

The bonding layers 19 and 21 are composed of, for example, Au--Sn, Au--In, Au--Cu--Sn, Cu--Sn, Pd--Sn, Sn or the like. As will be described later, these bonding layers 19 and 21 are arranged such that the bonding layer 21 formed on the substrate 3 and the bonding layer 19 formed on another substrate (growth substrate 25 described later) face each other. Later, it was formed by bonding the two together. These bonding layer 19 and bonding layer 21 may be integrated as a single layer.

The protective layer 17 has a multilayer structure such as Ni/Ti/Pt or TiW/Pt. It is provided for the purpose of suppressing the reflectance of 13 from decreasing. However, it is optional whether or not the light-emitting element 1 includes the protective layer 17 .

The protective layer 23 is made of, for example, the same material as the protective layer 17, and is provided for the purpose of suppressing diffusion of the material forming the bonding layers (19, 21) toward the substrate 3 side. However, it is optional whether or not the light-emitting device 1 includes the protective layer 23 .

(Current blocking layer 24)
The light-emitting device 1 of the present embodiment includes a current blocking layer 24 formed so as to be in contact with the second electrode 13 at a position facing the first electrode 15 in the Z direction. The current blocking layer 24 is composed of, for example _, SiO2 _, SiN, _Zr2O3 , AlN, _Al2O3 , or _the like. The current blocking layer 24 serves to spread the current flowing through the active layer 9 in the direction parallel to the XY plane. However, it is optional whether or not the light emitting device 1 includes the current blocking layer 24 .

(Reflection layer 31)
The light-emitting device 1 of this embodiment includes a reflective layer 31 on the first electrode 15 . The reflective layer 31 is made of a material that exhibits a high reflectance with respect to light having the same wavelength as the light emitted from the active layer 9 . As an example, when light having a wavelength of 410 nm or less is emitted from the active layer 9, the reflective layer 31 contains at least one of Al, Ag, Cu, Ni, Pt, Rh, Cr, and Co. It can be made of any material, and preferably made of material containing Al or Ag.

When the light-emitting element 1 does not have the reflective layer 31, that is, when it has a structure as shown in the plan view of FIG. Configure a region. However, as described above, the reflective layer 31 is formed on the first electrode 15 . FIG. 1C schematically shows a plan view of the configuration of the light-emitting element 1 when viewed from the light extraction surface, including the reflective layer 31 . According to such a configuration, part of the light emitted from the light extraction surface 28a of the light emitting element 1 is incident on the reflection layer 31, reflected again by the reflection layer 31, and guided in the extraction direction. .

FIG. 2 is a drawing schematically showing an example of a light source section including the light emitting element 1. As shown in FIG. The light source section 40 has a mirror section 41 so as to surround the axis which is perpendicular to the light extraction surface of the light emitting element 1 . Light emitted from the light emitting element 1 is emitted from the light emitting surface 42 of the light source section 40 .

Part of the light L1 emitted from the light extraction surface 28a of the light emitting element 1 is reflected by the mirror section 41, and part of the reflected light L1' is incident on the region 28b. Since the reflective layer 31 is formed in this region 28 b , the light is reflected by the reflective layer 31 and guided to the light exit surface 42 . When the reflective layer 31 is not formed, the region 28b constitutes a non-light-emitting region. However, according to the light-emitting device 1 of the present embodiment, the region 28b also constitutes a light-emitting region. be done.

Although the light source section 40 in FIG. 2 is configured to include the mirror section 41, the mirror section 41 may not necessarily be provided. In other words, a light source device including the light emitting element 1 is generally provided with various optical systems in order to use the light emitted from the light emitting element 1 . Some light is inevitably reflected when entering such an optical system. When part of the reflected light is guided toward the region 28b as return light, it is reflected by the reflective layer 31 formed in the region 28b. Therefore, the region 28b can be used as a light-emitting region, and a high-luminance light-emitting element is realized.

[Production method]
An example of a method for manufacturing the semiconductor light emitting device 1 will be described below with reference to FIGS. 3A to 3H and FIG. 1A.

(Step S1)
First, as shown in FIG. 3A, a growth substrate 25 is prepared. As the growth substrate 25, for example, a sapphire substrate having a C-plane can be used.

As a preparation step, the growth substrate 25 is cleaned. As a more specific example of this cleaning, the growth substrate 25 is placed in a processing furnace of an MOCVD (Metal Organic Chemical Vapor Deposition) apparatus, and a predetermined flow rate of hydrogen gas is placed in the processing furnace. This is carried out by raising the temperature in the furnace to, for example, 1150° C. while flowing the gas.

(Step S2)
As shown in FIG. 3B, an underlying layer 27, an n-type semiconductor layer 7, an active layer 9, and a p-type semiconductor layer 11 are sequentially formed on the growth substrate 25. As shown in FIG. This step S2 is performed, for example, by the following procedure.

First, the pressure inside the furnace of the MOVCVD apparatus is set to 100 kPa, and the temperature inside the furnace is set to 480.degree. Then, while nitrogen gas and hydrogen gas each having a flow rate of 5 slm are flowed into the processing furnace as carrier gases, trimethylgallium (TMG) having a flow rate of 50 μmol/min and ammonia having a flow rate of 250000 μmol/min as source gases are introduced into the processing furnace. for 68 seconds. Thereby, a low-temperature buffer layer made of GaN having a thickness of 20 nm is formed on the surface of the growth substrate 25 .

Next, the temperature inside the MOCVD apparatus is raised to 1150.degree. Then, in the processing furnace, nitrogen gas with a flow rate of 20 slm and hydrogen gas with a flow rate of 15 slm are flowed as carrier gases, and TMG with a flow rate of 100 μmol / min and ammonia with a flow rate of 250000 μmol / min are flowed as source gases. inside for 30 minutes. As a result, a buffer layer made of GaN having a thickness of 1.7 μm is formed on the surface of the low-temperature buffer layer. These buffer layers form the underlying layer 27 .

Next, the n-type semiconductor layer 7 is formed on the underlying layer 27 . A specific method of forming the n-type semiconductor layer 7 is, for example, as follows.

Subsequently, while the temperature inside the furnace is kept at 1150° C., the pressure inside the MOCVD apparatus is set at 30 kPa. Then, while flowing nitrogen gas with a flow rate of 20 slm and hydrogen gas with a flow rate of 15 slm as carrier gases in the processing furnace, TMG with a flow rate of 94 μmol / min and trimethylaluminum (TMA) with a flow rate of 6 μmol / min as source gases, Ammonia with a flow rate of 250000 μmol/min and tetraethylsilane with a flow rate of 0.013 μmol/min for doping n-type impurities are supplied into the processing furnace for 60 minutes. As a result, an n-type semiconductor layer 7 having a composition of, for example, Al _0.06 Ga _0.94 N, a thickness of 2 μm, and an n-type impurity concentration of 3×10 ¹⁹ /cm ³ is formed on the upper layer of the third semiconductor layer 28 . When the n-type semiconductor layer 7 is composed of GaN or AlGaN, the composition ratio of Al is preferably 0% or more and 15% or less, more preferably 2% or more and 11% or less, and 5% or more. Even more preferably, it is 9% or less.

After that, the supply of TMA was stopped and the other raw material gases were supplied for 6 seconds, so that a protective layer made of n-type GaN having a thickness of about 5 nm was formed on the n-type AlGaN layer. n-type semiconductor layer 7 may be realized.

In the above description, the case where Si is used as the n-type impurity contained in the n-type semiconductor layer 7 has been described, but Ge, S, Se, Sn, Te, or the like can be used as the n-type impurity other than Si. .

Next, an active layer 9 is formed on the n-type semiconductor layer 7 . A specific method of forming the active layer 9 is, for example, as follows.

First, the pressure inside the MOCVD apparatus is set to 100 kPa, and the temperature inside the furnace is set to 830.degree. Then, while flowing nitrogen gas with a flow rate of 15 slm and hydrogen gas with a flow rate of 1 slm as carrier gases in the processing furnace, TMG with a flow rate of 10 μmol / min, trimethylindium (TMI) with a flow rate of 12 μmol / min, and A step of supplying ammonia at a flow rate of 300000 μmol/min into the processing furnace for 48 seconds is performed. After that, a step of supplying TMG at a flow rate of 10 μmol/min, TMA at a flow rate of 1.6 μmol/min, tetraethylsilane at a flow rate of 0.002 μmol/min, and ammonia at a flow rate of 300000 μmol/min into the processing furnace for 120 seconds is performed. By repeating these two steps, the active layer 9 is formed by laminating 15 cycles of a light-emitting layer made of InGaN having a thickness of 2 nm and a barrier layer made of n-type AlGaN having a thickness of 7 nm, which is an n-type semiconductor layer. 7 is formed on the upper layer.

When the wavelength of light emitted from the active layer 9 is 410 nm or less, the In composition ratio of InGaN forming the light-emitting layer is preferably 10% or less. In this case, the Al composition ratio of GaN or AlGaN forming the barrier layer is preferably 0% or more and 15% or less, more preferably 2% or more and 13% or less, and 5% or more and 10% or less. is even more preferred.

Next, a p-type semiconductor layer 11 is formed on the active layer 9 . A specific method of forming the p-type semiconductor layer 11 is, for example, as follows.

Specifically, the furnace pressure of the MOCVD apparatus is maintained at 100 kPa, and the furnace temperature is raised to 1025° C. while flowing nitrogen gas with a flow rate of 15 slm and hydrogen gas with a flow rate of 25 slm as carrier gases in the processing furnace. do. After that, as source gases, TMG with a flow rate of 35 μmol/min, TMA with a flow rate of 20 μmol/min, ammonia with a flow rate of 250000 μmol/min, and biscyclopenta with a flow rate of 0.1 μmol/min for doping p-type impurities. Dienylmagnesium (Cp ₂ Mg) is fed into the furnace for 60 seconds. As a result, a hole supply layer having a composition of Al _0.3 Ga _0.7 N and having a thickness of 20 nm is formed on the surface of the active layer 33 . Thereafter, by changing the flow rate of TMA to 4 μmol/min and supplying the raw material gas for 360 seconds, a hole supply layer having a composition of Al _0.13 Ga _0.87 N with a thickness of 120 nm is formed. These hole supply layers form the p-type semiconductor layer 11 . The p-type impurity concentration of these hole supply layers is set to, for example, about 3×10 ¹⁹ /cm ³ /cm ³ .

After this step, the supply of TMA is stopped, and the flow rate of Cp ₂ Mg is changed to 0.2 μmol/min and the material gas is supplied for 20 seconds. may realize the p-type semiconductor layer 11 having a p-type GaN layer with a density of about 1×10 ²⁰ /cm ³ .

In the above description, the case of using Mg as the p-type impurity contained in the p-type semiconductor layer 11 has been described, but Be, Zn, C, or the like can also be used as the p-type impurity other than Mg.

(Step S3)
An activation process is performed on the wafer obtained in step S2. As a specific example, an RTA (Rapid Thermal Anneal) apparatus is used to perform activation treatment at 650° C. for 15 minutes in a nitrogen atmosphere.

(Step S4)
As shown in FIG. 3C, a current blocking layer 24 is formed on the top surface of a predetermined region of the p-type semiconductor layer 11 . The current blocking layer 24 is formed by depositing SiO ₂ , SiN, Zr ₂ O ₃ , AlN, Al ₂ O ₃ or the like by sputtering or the like. In addition, in this step S4, the current blocking layer 24 is formed at a position facing in the Z direction with respect to the region where the first electrode 15 is to be formed in the later step S12.

(Step S5)
Next, as shown in FIG. 3C, a second electrode 13 is formed on the upper surface of a predetermined region of the p-type semiconductor layer 11 . Here, the second electrode 13 is also formed on the upper surface of the current blocking layer 24, but the shape of the second electrode 13 is arbitrarily selected. The second electrode 13 is formed, for example, by forming a film of Ni/Ag with a sputtering device and then performing contact annealing in a dry air atmosphere using an RTA device. Here, as an example, the material of the second electrode 13 is an alloy of Ni and Ag, but Al, Rh, an alloy of Ag, Pd and Cu, etc. can also be used. As described above, it is preferable to use a material having a high reflectance with respect to the light emitted from the active layer 9 as the material of the second electrode 13 .

(Step S6)
Next, as shown in FIG. 3C , a protective layer 17 is formed on the upper surface of the second electrode 13 and a bonding layer 19 is formed on the upper surface of the protective layer 17 .

The protective layer 17 is formed, for example, by depositing Ni with a thickness of 80 nm, Ti with a thickness of 100 nm, and Pt with a thickness of 200 nm using an electron beam deposition apparatus (EB apparatus). As the material of the protective layer 17, TiW/Pt or the like can be used in addition to Ni/Ti/Pt.

After that, after vapor-depositing Ti with a thickness of 10 nm on the upper surface of the protective layer 17, a bonding layer 19 is formed by vapor-depositing Au—Sn solder composed of 80% Au and 20% Sn to a thickness of 3 μm. Besides Au--Sn solder, Au--In, Au--Cu--Sn, Cu--Sn, Pd--Sn, Sn, etc. can be used as the bonding layer 19 .

(Step S7)
As shown in FIG. 3D, the protective layer 23 and the bonding layer 21 are formed on the top surface of the substrate 3 prepared separately from the growth substrate 25 . As the substrate 3, a conductive substrate such as CuW, W, or Mo, or a semiconductor substrate such as Si can be used as described above. The protective layer 23 can be formed similarly to the protective layer 17 , and the bonding layer 21 can be formed similarly to the bonding layer 19 . Whether or not to provide the protective layer 23 is optional.

(Step S8)
As shown in FIG. 3E, the growth substrate 25 and the substrate 3 are bonded by bonding the bonding layer 19 formed on the growth substrate 25 and the bonding layer 21 formed on the substrate 3 together. As a specific example, the bonding process is performed at a temperature of 280° C. and a pressure of 0.2 MPa.

In this step, the bonding layer 19 and the bonding layer 21 are melted and bonded together, thereby forming a structure in which the substrate 3 and the growth substrate 25 are bonded to the front and back surfaces. That is, the bonding layer 19 and the bonding layer 21 may be integrated after this step. By forming the protective layer 23 and the protective layer 17 before executing step S8, diffusion of the constituent material of the bonding layers (19, 21) is suppressed.

(Step S9)
As shown in FIG. 3F, the growth substrate 25 is removed. More specifically, laser light is applied from the growth substrate 25 side. Here, the laser light to be irradiated is light having a wavelength that passes through the constituent material (sapphire in this embodiment) of the growth substrate 25 and is absorbed by the constituent material (GaN in this embodiment) of the underlying layer 27 . . As a result, the underlying layer 27 absorbs the laser light, so that the temperature of the interface between the growth substrate 25 and the underlying layer 27 rises, GaN is decomposed, and the growth substrate 25 is peeled off.

(Step S10)
After metal Ga remaining on the wafer is removed using hydrochloric acid or the like, GaN (underlying layer 27) is removed by dry etching using an ICP apparatus to expose the n-type semiconductor layer 7 (see FIG. 3G). .

(Step S11)
As shown in FIG. 3H, separate adjacent elements. Specifically, the semiconductor layer 5 is etched using an ICP apparatus in the boundary region between adjacent elements until the upper surface of the current blocking layer 24 formed in the element isolation region is exposed. At this time, the current blocking layer 24 functions as an etching stopper layer. In FIG. 3H, the side surface of the semiconductor layer 5 is illustrated as having an inclination with respect to the vertical direction, but this is an example and is not meant to limit the shape to such a shape.

(Step S12)
As shown in FIG. 1A, the first electrode 15 is formed on the upper surface of the n-type semiconductor layer 7 at a position facing the current blocking layer 24 in the Z direction. Specifically, the surface of the n-type semiconductor layer 7, for example, Ni/Al/Ni/Ti is deposited by, for example, an electron beam deposition apparatus while masking a region other than the target for forming the first electrode 15 with a resist or the like. /Au is vapor-deposited to a thickness of about 3 μm. After that, the mask is peeled off.

(Step S13)
As shown in FIG. 1A, a reflective layer 31 is formed on the top surface of the first electrode 15 . Specifically, while masking the upper surface of the n-type semiconductor layer 7 constituting the current supply portion 15a and the light extraction surface 28a with a resist or the like, for example, Al is deposited on the upper surface of the first electrode 15 to a thickness of about 10 nm to 1 μm. evaporate. After that, the mask is peeled off.

Note that the reflective layer 31 may be formed by applying a material layer by a sputtering method. According to this method, the reflective layer 31 is formed without using a mask. According to this method, the reflecting layer 31 having a diffuse reflecting surface is formed by adjusting the particle size of the material to be sprayed, so that the reflectance can be further increased.

(Later process)
A wafer is divided into chips. As a specific example, each element is separated from each other by, for example, a laser dicing device.

After that, the back surface of the substrate 3 is joined to the package with Ag paste, for example, and the current supply line 14 is connected to the current supply portion 15a. For example, wire bonding is performed by connecting the current supply line 14 made of Au with a diameter of Φ100 μm to the current supply portion 15a with a load of 50 g. Thus, the light emitting element 1 is formed.

[Another configuration]
Another configuration example of the light emitting device 1 of this embodiment will be described below.

<1> A protective layer 32 may be provided on the reflective layer 31 (see FIG. 4A). FIG. 4A is an enlarged view of the vicinity of the first electrode 15. FIG. The protective layer 32 is made of a material having a property of transmitting light having the same _wavelength as the light emitted from the active layer 9, such as SiO2 _, SiN, _Zr2O3 , _ZrO2 , _HfO2 , _Hf2. It is composed of O ₃ , AlN, Al ₂ O ₃ and the like. This protective layer 32 corresponds to the "first protective layer". According to this configuration, since the upper surface of the reflective layer 31 is protected, the material forming the reflective layer 31 is less likely to be oxidized or sulfurized, thereby suppressing a decrease in reflectance over time.

In addition, as shown in FIG. 4B, fine irregularities may be formed on the surface of the protective layer 32 . With such a configuration, the extraction efficiency of the return light L1' reflected by the surface of the reflective layer 31 is enhanced.

Furthermore, as shown in FIG. 4C, a protective layer 32 may be formed to cover the top surface and side surfaces of the reflective layer 31 . Such a configuration further enhances the effect of preventing the reflectance of the reflective layer 31 from deteriorating over time. In FIG. 4C, the protective layer 32 is configured to cover the outer surface of the first electrode 15 as well, but may be configured to cover only the upper surface and the outer surface of the reflective layer 31 .

<2> A protective layer 34 may be provided between the reflective layer 31 and the first electrode 15 (see FIG. 4D). Unlike the protective layer 32 , the protective layer 34 does not necessarily have the property of transmitting light having the same wavelength as the light emitted from the active layer 9 . The protective layer 34 _is composed of, for example, SiO2 _, SiN, _Zr2O3 , _ZrO2 , _HfO2 , _{Hf2O3 ,} AlN, _{Al2O3 ,} or the like. This protective layer 34 corresponds to the "second protective layer".

If the first electrode 15 is made of a material with low stability, the electrode material of the first electrode 15 may diffuse into the reflective layer and reduce the reflectance of the reflective layer 31 . According to the above configuration, it becomes difficult for the material of the first electrode 15 to diffuse toward the reflective layer 31 , and it is possible to prevent the reflectance of the reflective layer 31 from decreasing with time.

It should be noted that a configuration combined with another configuration example <1> may be employed (for example, see FIGS. 4E and 4F).

<3> As shown in FIG. 5, the reflective layer 31 formed on the light emitting element 1 may be arranged rotationally asymmetrically when viewed from the direction perpendicular to the light extraction surface (Z direction). When the light extraction surface 28a is arranged at a rotationally symmetrical position when viewed in the Z direction, the return light L1′ reflected at a predetermined location after being emitted from the light extraction surface 28a is returned to the light extraction surface 28a. The rate of being returned to is increasing. As shown in FIG. 5, by arranging the light extraction surface 28a rotationally asymmetrically when viewed from the Z direction, that is, by arranging the reflective layer 31 rotationally asymmetrically when viewed from the Z direction, the reflective layer The amount of light returned to 31 can be increased. Thereby, the luminance of the light emitting element 1 is further increased.

According to the embodiment, compared to the case where the reflective layer 31 is completely rotationally symmetrical when viewed from the Z direction, the reflective layer 31 is arranged in a predetermined shape to be rotationally asymmetrical when viewed from the Z direction. , it was confirmed that the amount of light from the light-emitting element 1 was improved by 3%.

<4> The upper surface of the n-type semiconductor layer 7 may be roughened. Thereby, the light extraction efficiency can be further improved. As an example, after step S11, the n-type semiconductor layer 7 is immersed in a predetermined alkaline solution such as KOH and wet-etched, so that uneven processing can be performed.

<5> In the above configuration, among the layers constituting the semiconductor layer 5, the side closer to the substrate 3 is defined as the p-type semiconductor layer 11, and the side farther from the substrate 3 is defined as the n-type semiconductor layer 7. can be reversed.

(Second embodiment)
A second embodiment of the semiconductor light emitting device will be described. Note that the same reference numerals are given to the same components as in the first embodiment, and the description thereof will be omitted as appropriate.

[structure]
FIG. 6 is a cross-sectional view schematically showing the configuration of the second embodiment of the semiconductor light emitting device of the present invention. The light emitting device 1 includes a substrate 25 , a semiconductor layer 5 formed on the substrate 25 , a first electrode 15 , a second electrode 13 , and a reflective layer 31 . The light emitting device 1 shown in FIG. 5 has a so-called "flip chip" type structure, and a light extraction surface 28a is formed on the surface of the substrate 25 opposite to the semiconductor layer 5. there is

In the light-emitting device 1 of the present embodiment, the semiconductor layer 5 includes a region (corresponding to a “first region”) formed by stacking an n-type semiconductor layer 7, an active layer 9, and a p-type semiconductor layer 11, and an active layer 9 and a region having the n-type semiconductor layer 7 without the p-type semiconductor layer 11 (corresponding to the “second region”). The first electrode 15 is formed in contact with the n-type semiconductor layer 7 located within the second region. The first electrode 15 is made of, for example, a metal material containing Au, and constitutes a "light absorbing electrode" as in the first embodiment. The second electrode 13 is formed in contact with the p-type semiconductor layer 11 located within the first region, and is made of a material that exhibits a high reflectance with respect to light emitted from the active layer 9 . preferable.

The first electrode 15 communicates with the bonding electrode 54 via the pad electrode 52 . The second electrode 13 communicates with the bonding electrode 53 via the pad electrode 51 . These bonding electrodes ( 53 , 54 ) are electrically connected to the mounting board 55 .

In the light emitting element 1 of the present embodiment, a reflective layer 31 is formed in a region 28b facing the first electrode 15 in a direction perpendicular to the substrate 25 on the light extraction surface side. If the reflective layer 31 were not present, the area 28b would constitute a non-light emitting area. However, in the light-emitting element 1 of the present embodiment, part of the light emitted from the light extraction surface 28a is reflected again by the reflective layer 31 and guided in the extraction direction. can be As a result, the brightness can be increased more than before.

[Production method]
An example of a method for manufacturing the light emitting device 1 of this embodiment will be described below with reference to FIGS. 7A to 7B and 6. FIG.

Steps S1 to S3 are executed in the same manner as in the first embodiment.

(Step S21)
As shown in FIG. 7A, the p-type semiconductor layer 11 and the active layer 9 formed in a part of the region are removed by dry etching using an ICP apparatus to expose the n-type semiconductor layer 7 .

(Step S22)
As shown in FIG. 7B, a first electrode 15 is formed on the exposed upper surface of the n-type semiconductor layer 7 and a second electrode 13 is formed on the upper surface of the p-type semiconductor layer 11 . The first electrode 15 can be formed, for example, by a method similar to step S12. The second electrode 13 can be formed, for example, by a method similar to step S5.

(Step S23)
A reflective layer 31 is formed in the above-described predetermined region 28 b of the surface of the substrate 25 opposite to the semiconductor layer 5 . The reflective layer 31 can be formed, for example, by a method similar to step S13.

(Later process)
A pad electrode 52 is formed on the upper surface of the first electrode 15, and a pad electrode 51 is formed on the upper surface of the second electrode 13, respectively. After that, the pad electrode 52 and the mounting board 55 are connected by the bonding electrode 54 , and the pad electrode 51 and the mounting board 55 are connected by the bonding electrode 53 . Thus, the light emitting element 1 shown in FIG. 6 is formed.

[Another configuration]
In the above configuration, among the layers constituting the semiconductor layer 5, the side closer to the substrate 25 is defined as the n-type semiconductor layer 7, and the side farther from the substrate 25 is defined as the p-type semiconductor layer 11. However, these conductivity types are reversed. I don't mind. Also in the present embodiment, as described with reference to FIGS. 4A to 4D, the protective layer 32 (first protective layer) may be provided so as to cover the surface of the reflective layer 31. FIG.

(Third embodiment)
A third embodiment of the semiconductor light emitting device will be described. Note that the same reference numerals are given to the same components as in the first embodiment, and the description thereof will be omitted as appropriate.

[structure]
FIG. 8 is a drawing schematically showing the configuration of the third embodiment of the semiconductor light emitting device of the present invention. In FIG. 8, (a) corresponds to the plan view, and (b) corresponds to the cross-sectional view. The light emitting device 1 includes a substrate 25 , a semiconductor layer 5 formed on the substrate 25 , a first electrode 15 , a second electrode 13 , and a reflective layer 31 . The light emitting device 1 shown in FIG. 8 has a so-called "via" structure, and a light extraction surface 28a is formed on the surface of the substrate 25 opposite to the semiconductor layer 5. .

In the light-emitting device 1 of the present embodiment, the semiconductor layer 5 includes a region (corresponding to a “first region”) formed by stacking an n-type semiconductor layer 7, an active layer 9, and a p-type semiconductor layer 11, and an active layer 9 and a region having the n-type semiconductor layer 7 without the p-type semiconductor layer 11 (corresponding to the “second region”). This second area is configured to be surrounded by the first area. More specifically, semiconductor layer 5 has a recess penetrating p-type semiconductor layer 11 and active layer 9 and reaching n-type semiconductor layer 7 . The first electrode 15 is arranged to be inserted into this recess. As in the first embodiment, the first electrode 15 is made of a metal material containing Au or the like, and constitutes a "light absorption electrode". The light-emitting element 1 has an insulating layer 58 to ensure insulation between the first electrode 15 and the p-type semiconductor layer 11, active layer 9, and second electrode 13. FIG.

The light emitting device 1 of this embodiment has a second electrode 13 arranged in contact with the upper surface of the p-type semiconductor layer 11 . As in the first embodiment, the second electrode 13 is preferably made of a material that exhibits a high reflectance with respect to light emitted from the active layer 9. In this case, the second electrode 13 is " reflective electrode”.

In the light emitting element 1 of the present embodiment, a reflective layer 31 is formed in a region 28b facing the first electrode 15 in a direction perpendicular to the substrate 25 on the light extraction surface side. As described above in the first embodiment, if the reflective layer 31 is not present, the area 28b constitutes a non-light emitting area. However, in the light-emitting element 1 of the present embodiment, part of the light emitted from the light extraction surface 28a is reflected again by the reflective layer 31 and guided in the extraction direction. can be As a result, the brightness can be increased more than before.

[Production method]
An example of a method for manufacturing the light emitting device 1 of this embodiment will be described below with reference to FIGS. 9A to 9B and 8. FIG.

Steps S1 to S3 are executed in the same manner as in the first embodiment.

(Step S31)
As shown in FIG. 9A, a second electrode 13 is formed at a predetermined location on the top surface of the p-type semiconductor layer 11 . Specifically, the second electrode 13 is selectively formed on the upper surface of the p-type semiconductor layer 11 except for one or more island-shaped regions. The wafer that has undergone step S31 has, on its upper surface, a region in which the p-type semiconductor layer 11 is exposed in an island shape and a region in which the second electrode 13 is exposed. The second electrode 13 can be formed, for example, by a method similar to step S5.

(Step S32)
As shown in FIG. 9B, the surface of the p-type semiconductor layer 11 exposed through step S31 is etched to expose the upper surface of the n-type semiconductor layer 7 . Thereby, a recess penetrating through the p-type semiconductor layer 11 and the active layer 9 and reaching the n-type semiconductor layer 7 is formed. After that, an insulating layer 58 is formed so as to cover the inner side surface of this recess. SiO _{2 ,} SiN, Zr ₂ O ₃ , AlN, Al ₂ O ₃ or the like can be used as the insulating layer 58 .

(Step S33)
A first electrode 15 is formed by depositing a conductive material so as to fill the recess. The first electrode 15 can be formed, for example, by a method similar to step S12.

(Step S34)
A reflective layer 31 is formed in a region of the surface of the substrate 25 opposite to the semiconductor layer 5 , which faces the first electrode 15 in a direction orthogonal to the substrate 25 . The reflective layer 31 can be formed, for example, by a method similar to step S13.

(Later process)
A protective layer 56 and a bonding layer 57 are formed on the exposed upper surfaces of the first electrode 15 and the second electrode 13, and a mounting substrate 55 is bonded via the bonding layer 57 (see FIG. 8). As a specific example, the protective layer 56 is formed by forming films of Ti and Pt three times in an electron beam deposition apparatus (EB apparatus), and then Ti is formed on the upper surface of the protective layer 56 (Pt surface). Then, a bonding layer 57 is formed by vapor-depositing Au—Sn solder. Then, a mounting substrate 55 for applying a voltage to each electrode (13, 15) is attached via the bonding layer 57. As shown in FIG. As the mounting substrate 55, a conductive substrate such as CuW, W, or Mo, a semiconductor substrate such as Si, or an insulating substrate such as AlN provided with a wiring pattern can be used.

[Another configuration]
Another configuration example of the light emitting device 1 of this embodiment will be described below.

<1> As shown in FIG. 10, it is also possible to employ a configuration in which the substrate 25 is peeled off. In this case, the n-type semiconductor layer 7 constitutes the light extraction surface, and the reflective layer 31 is arranged at a position corresponding to the direction perpendicular to the light extraction surface with respect to the first electrode 15 on the surface of the n-type semiconductor layer. be done. With this configuration as well, part of the light emitted from the light extraction surface 28a is reflected again by the reflective layer 31 and guided in the extraction direction, so that the region 28b can be used as a light emitting region. As a result, the brightness can be increased more than before.

When manufacturing the light emitting device 1 shown in FIG. 10, it can be manufactured, for example, by the following method. After step S33 is executed, the mounting board 55 is bonded via the protective layer 56 and the bonding layer 57 by the method described above. After that, the growth substrate 25 and the base layer 27 are removed by the same method as steps S9 to S10, for example. Then, the reflective layer 31 is formed on the exposed surface of the n-type semiconductor layer 7 at a position facing the first electrode 15 in the direction orthogonal to the light extraction surface.

<2> In the above configuration, among the layers constituting the semiconductor layer 5, the side closer to the mounting board 55 is defined as the p-type semiconductor layer 11, and the side farther from the mounting board 55 is defined as the n-type semiconductor layer 7. The conductivity type may be reversed. Also in the present embodiment, as described with reference to FIGS. 4A to 4D, the protective layer 32 (first protective layer) may be provided so as to cover the surface of the reflective layer 31. FIG.

Reference Signs List 1: semiconductor light emitting device 3: substrate 5: semiconductor layer 7: n-type semiconductor layer 9: active layer 11: p-type semiconductor layer 13: second electrode 14: current supply line 15: first electrode 15a: current supply section 17: Protective layer 19 : Bonding layer 20 : Conductive layer 21 : Bonding layer 23 : Protective layer 24 : Current blocking layer 25 : Growth substrate 27 : Base layer 28a : Light extraction surface 28b : Region 31 : Reflective layer 32 : Protective layer (first protective layer)
34: Protective layer (second protective layer)
40: Light source section 41: Mirror section 42: Light exit surface 51, 52: Pad electrodes 53, 54: Bonding electrodes 55: Mounting substrate 56: Protective layer 57: Bonding layer 58: Insulating layer

Claims (6)

A light irradiation device including a semiconductor light emitting device,
The semiconductor light emitting device is
a substrate;
An n-type or p -type first semiconductor layer, an active layer, and a second semiconductor layer having a conductivity type different from that of the first semiconductor layer, which are formed on the upper layer of the substrate, in order from the side closer to the substrate, a semiconductor layer formed by stacking the second semiconductor layer, the active layer, and the first semiconductor layer in this order;
a light-absorbing electrode in contact with the first semiconductor layer on the side opposite to the active layer and comprising Au or an Au alloy;
an upper layer of a light extraction surface formed of a surface of the semiconductor layer located on the opposite side of the substrate, the layer extending from the substrate relative to the direction perpendicular to the surface of the substrate relative to the light absorbing electrode; a reflective layer formed only at a distant position and made of a material exhibiting a reflectance of 40% or more with respect to light having the same wavelength as that of light emitted from the active layer;
A reflective electrode formed in contact with a surface of the second semiconductor layer opposite to the active layer,
The light irradiation device is further arranged so as to surround an axis orthogonal to the light extraction surface of the semiconductor light emitting element, and is a mirror for returning part of the light emitted from the light extraction surface to the reflection layer. having a department,
The light irradiation device, wherein the active layer is made of a nitride semiconductor material having a main emission wavelength of 410 nm or less. 2. The light irradiation device according to claim 1, wherein said reflective layer forms a diffuse reflection surface for the light returned from said mirror section. 3. The light according to claim 1, wherein the semiconductor light emitting device comprises a first protective layer formed on the reflective layer and made of a material that transmits light emitted from the active layer. Irradiation device. 4. The light absorbing electrode according to any one of claims 1 to 3, wherein a plurality of said light absorption electrodes are formed in an upper layer of said first semiconductor layer by extending in a direction parallel to the surface of said substrate. Light irradiation device. 5. The light irradiation device according to claim 4, wherein a plurality of the reflective layers are formed on the upper layer of the first semiconductor layer by extending in a direction parallel to the surface of the substrate. 6. The light irradiation device according to claim 5, wherein the reflective layer has a frame shape when viewed from a direction perpendicular to the surface of the substrate.

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