JP2002217450A - Semiconductor light-emitting device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting device which has a low parasitic series resistance, improved reflection coefficient, and high light emission efficiency. SOLUTION: The semiconductor light-emitting device comprises a semiconductor light-emitting function layer 4, alloy layer 5 for contact which is formed cyclically on the principal plane of the semiconductor light-emitting function layer 4, and reflection film 3 having a high conductivity bonded via the alloy layer 5 for making contact. The semiconductor light-emitting function layer 4 comprises a first clad layer 6, active layer 7, and second clad layer 8. In the upper part of the second clad layer 8, a p-type current diffusion layer 9 is provided. A conductive flat plate 2 is bonded to the principal plane of the reflection film 3 having a high conductivity. The conductive flat plate 2 functions as a cathode electrode, while mechanically reinforming the reflection film 3 which has high conductivity. On the current diffusion layer 9, an anode electrode 10 is formed. A high optical reflection region, having a proper interfacial morphology and a high optical reflection coefficient and an ohmic contact region having a low electrical contact resistance, are formed alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device that emits light perpendicular to a main surface of a semiconductor light emitting functional layer.

[0002]

2. Description of the Related Art As a semiconductor light emitting device which emits light in a direction perpendicular to the main surface of a semiconductor light emitting function layer, that is, a so-called "surface light emission", for example, an Al _x Ga _{2. Description of the} Related Art A semiconductor light emitting element in which a semiconductor light emitting functional layer including an active layer made of _1-x In or the like is laminated is known. In such a semiconductor light emitting device,
Light emitted from the active layer is emitted in all directions. For this reason,
In order to increase the brightness of a semiconductor light emitting device, it is extremely important how to efficiently extract light emitted from the active layer to the outside of the device. For example, when the semiconductor light-emitting functional layer and the substrate such as to form, respectively _{(Al x Ga 1 -x) y} In 1-y P and GaAs, the light is emitted from the one main surface of the semiconductor light-emitting functional layer, When the light is reflected by a reflector arranged on the GaAs substrate side, the GaAs substrate absorbs light emitted from the active layer, and therefore, it is necessary to suppress this light absorption by some means.

For example, when light emitted from the active layer is extracted to the other main surface of the semiconductor light emitting device, light emitted from the active layer to one main surface of the semiconductor light emitting device is efficiently transferred to the other main surface. As a well-known means, it is known to form a Bragg reflection (DBR) structure between the substrate and the semiconductor light-emitting functional layer (hereinafter, referred to as "first means"). This DBR structure is formed by laminating two compound semiconductor layers having a desired thickness different from each other in refractive index, for example, a pair of AlAs / GaAs laminated films and a plurality of pairs of these layers. The DBR structure uses the DBR structure determined by the optical refractive index and the thickness of the compound semiconductor layer to transmit light emitted from the active layer to the substrate (one main surface). The light is reflected to the other main surface to increase the light extraction efficiency. Since such a DBR structure can be formed in a series of epitaxial growth processes for forming a semiconductor light emitting functional layer and the like, it can be said that it is a means excellent in simplicity and productivity.

As another means for improving the light extraction efficiency of a semiconductor light emitting device (hereinafter referred to as "second means"), a semiconductor light emitting functional layer and the like are formed on a substrate by a method such as epitaxial growth. Later, the substrate functioning as a light-absorbing substrate is removed, and the surface from which the substrate has been removed is provided with a material having an absorption edge energy larger than the energy of the light emitted from the active layer, that is, a transparent material for the light emitted from the active layer. A hetero-junction or a structure similar to a hetero-junction in which an insulating substrate such as another high bandgap semiconductor or sapphire having a low light absorption property is attached. By further providing a light reflecting surface on the outer surface of the substrate constituting such a structure such as a heterojunction, the active layer emits light toward the substrate having light transmission characteristics, and after transmitting this light through the substrate, Light can be taken out to the other main surface side of the semiconductor light emitting device by being reflected in the opposite direction by the reflecting surface.

[0005]

However, the improvement of the light extraction efficiency by the first and second means has the following problems, respectively.

That is, in the first means employing the DBR structure, if the light reflectance with respect to the peak wavelength of the light emitted from the active layer is to be increased, the spectral band of the wavelength for reflection is narrowed. On the other hand, if the spectral band of the wavelength for the reflection is to be widened, there is a problem that the reflectance for the peak wavelength must be lowered. That is, it is difficult to obtain a high reflectivity for light having a wide band of emission wavelengths using the DBR structure. In such a semiconductor light emitting device, the light reflectance also depends on the angle of incidence of light on the DBR structure, so that the light extraction efficiency does not improve as expected.

In the second means, such as a heterojunction in which a high bandgap semiconductor having a low light absorption property or a substrate of an insulator is attached, the emission wavelength and the incident angle are different from the first means (DBR structure). There is no problem based on. However, basically, there is a voltage drop and a series resistance (parasitic series resistance) at a heterojunction interface or a semiconductor / insulator interface. Furthermore, obtaining a low ohmic contact with such a high bandgap semiconductor or insulator substrate is difficult in principle, considering the band structure. In other words, when a high forbidden band semiconductor or insulator substrate is attached, the forward voltage drop (ON voltage) as a whole
Has to be large.

Further, as a practical process problem, a sufficient heat treatment (alloying treatment) is required to obtain a low ohmic contact with such a high bandgap semiconductor or insulator substrate. . However, if the heat treatment (alloying treatment) is performed, the morphology of the interface between the high forbidden band semiconductor or the insulator and the light reflecting surface is reduced. In other words, regarding the characteristics of the interface between the substrate and the light reflecting surface, optical characteristics such as light transmission characteristics and reflection characteristics and electrical characteristics (low-resistance ohmic contact at the interface)
Is in a trade-off relationship. To improve the electrical characteristics, the optical characteristics decrease, and to improve the optical characteristics, the electrical characteristics decrease. As described above, if an attempt is made to reduce the electrical resistance (parasitic series resistance), there is a trade-off that light cannot be efficiently reflected by the reflection surface on the outer surface of the substrate. There was a problem that it could not be achieved sufficiently.

The present invention has been made to solve the above problems. Therefore, an object of the present invention is to improve the electrical characteristics of one main electrode of the semiconductor light emitting function layer, improve the reflectance on the main surface on which the one main electrode is arranged, and improve the light extraction efficiency. An object of the present invention is to provide a high-brightness semiconductor light emitting device.

Another object of the present invention is to provide a semiconductor light emitting device having both good electrical characteristics and good optical characteristics, high luminous efficiency, and good production yield.

[0011]

SUMMARY OF THE INVENTION In view of the above object, a first feature of the present invention is that a semiconductor light emitting functional layer and optical elements arranged alternately and periodically on one main surface of the semiconductor light emitting functional layer. The gist of the present invention is that the semiconductor light emitting device includes a “high optical reflection region” having a high reflectance and an “ohmic contact region” having a low electrical contact resistance. Here, the “semiconductor light-emitting functional layer” has a laminated structure for emitting light having a wavelength specific to the semiconductor by current injection through a pn junction. For example, the semiconductor light-emitting functional layer may be constituted by a simple pn junction, and includes a double layer comprising a first cladding layer, an active layer above the first cladding layer, and a second cladding layer above the active layer. Hetero (D
H) It may be constituted by a structure. Alternatively, of the DH structure, a single hetero (SH) structure in which one of the first clad layer and the second clad layer is omitted may be employed. The “semiconductor light emitting device” corresponds to a light emitting diode (LED) or a surface emitting semiconductor laser.

If the semiconductor light emitting function layer has a DH structure, the first cladding layer is a first conductivity type semiconductor having a common main surface with one main surface of the semiconductor light emitting function layer to which the highly conductive reflection film is bonded. Layer. The second cladding layer is a semiconductor layer of the second conductivity type and is located on the light emitting surface (emission surface) side. The first conductivity type and the second conductivity type are opposite conductivity types. That is,
If the first conductivity type is n-type, the second conductivity type is p-type,
If the first conductivity type is p-type, the second conductivity type is n-type.
Here, the “main surface” means a surface having the largest or second largest area in a flat plate shape, and is intended to be distinguished from an end surface. The “one main surface” is one of the main surfaces of the semiconductor light-emitting functional layer having a substantially flat plate shape, and faces the “one main surface” and serves as a light-emitting surface (an emission surface). Exists. That is, one of “one main surface” and “the other main surface” is “front” and the other is “back”
In the present invention, the “main surface that is not the light-emitting surface (output surface) side” is the “one main surface” of the semiconductor light-emitting functional layer.

The "ohmic contact region" includes, for example, a contact alloy layer periodically provided on a part of the semiconductor light emitting functional layer on one main surface of the semiconductor light emitting functional layer and one of the semiconductor light emitting functional layers. And a highly conductive reflective film joined via a contact alloy layer to the main surface. On the other hand, the “high optical reflection region” can be formed at the interface between the one main surface of the semiconductor light emitting functional layer and the high conductive reflection film in the region where the contact alloy layer is not arranged.

For example, a contact alloy layer periodically provided on a part of the semiconductor light emitting functional layer on one main surface of the semiconductor light emitting functional layer and a contact alloy layer on one main surface of the semiconductor light emitting functional layer are provided. If the semiconductor light emitting device is configured with the highly conductive reflective film joined through the intermediary, a region directly joined to the highly conductive reflective film and a contact alloy layer are formed on one main surface of the semiconductor light emitting functional layer. Regions that are indirectly bonded to the highly conductive reflective film through the intervening layers are formed alternately and periodically. The region directly joined to the highly conductive reflective film is a “highly optically reflective region” which has a high electrical contact resistance, has good interface morphology, and has a high optical reflectance. On the other hand, in the region that is indirectly joined to the highly conductive reflective film via the contact alloy layer, the interface morphology is reduced and the optical reflectivity is sacrificed, but the ohmic contact with low electrical contact resistance is good. This is an “ohmic contact region” showing characteristics.

In the semiconductor light emitting device according to the first aspect of the present invention, light emitted from the semiconductor light emitting functional layer is reflected at the interface between the highly conductive reflective film and the semiconductor light emitting functional layer in the high optical reflection region. Through the semiconductor light emitting functional layer again,
The light exits from the other main surface. Although the reflectivity is lower than that of the high optical reflection area, the light is also reflected in the ohmic contact area. Since the reflectance in the high optical reflection region is high, the light extraction efficiency of the semiconductor light emitting device can be improved as a whole. On the other hand, since there is an ohmic contact region where a low ohmic contact can be obtained, a parasitic resistance component connected in series is small, light can be emitted at a low operating voltage, and luminous efficiency can be increased. That is, according to the semiconductor light emitting device of the first aspect of the present invention, the trade-off relationship between the optical reflection characteristics and the electric characteristics (low-resistance ohmic contact at the electrode portion) can be relaxed. I can do it.

In the case of the DH structure, of the light emitted from the active layer, the light emitted to the first cladding layer side is
In the high optical reflection region, the light is reflected at the interface between the first cladding layer and the highly conductive reflection film, passes through the first cladding layer and the active layer again, and finally exits from the second cladding layer side. The light extraction efficiency of the light emitting element can be improved. At the same time, in the ohmic contact region, a contact alloy layer exists at the interface between the first cladding layer and the highly conductive reflective film, and the reflectivity is lower than that of the high optical reflection region, but the electric contact resistance is low. Good ohmic properties are obtained. Therefore, the presence of the ohmic contact region reduces the parasitic resistance component connected in series inside the semiconductor light emitting element, and makes it possible for the semiconductor light emitting element to emit light at a low operating voltage as a whole. That is, according to the semiconductor light emitting device of the first aspect of the present invention, the trade-off relationship between the optical characteristics and the electric characteristics is relaxed, and high luminous efficiency can be exhibited. The “alloy layer for contact” means that, for example, the first cladding layer is (Al _x Ga _1-x ) _y In
If the semiconductor layer is a _1-y P-based semiconductor layer, a solid solution or eutectic composed of each element of Al, Ga, In, and P constituting the semiconductor layer and a well-known metal element such as Au or Ge as an ohmic electrode material A mixture, a compound, or a state in which these coexist.

In the semiconductor light-emitting device according to the first aspect of the present invention, the contact alloy layer is periodically formed at intervals substantially equal to the carrier diffusion length near one main surface of the semiconductor light-emitting functional layer. Preferably, they are arranged in a shape. This is because if the contact alloy layer is arranged at a distance within the diffusion length of the carrier, an ohmic contact resistance substantially similar to the case where the contact alloy layer is formed on the entire surface can be obtained. Similarly, the contact alloy layer may be periodically provided in a lattice at intervals substantially equal to the carrier diffusion length near one main surface of the semiconductor light emitting functional layer.

In the semiconductor light emitting device according to the first aspect of the present invention, a conductive flat plate may be further bonded to the main surface of the highly conductive reflective film on the side opposite to the side bonded to the semiconductor light emitting functional layer. preferable. The “conductive flat plate” functions as one main electrode of the semiconductor light emitting element, and at the same time, mechanically (physically) reinforces the highly conductive reflective film.

A second feature of the present invention is that (a) a step of forming a semiconductor light emitting functional layer including at least a pn junction on a starting substrate, and (b) a step of selectively removing the starting substrate to form a semiconductor light emitting layer. Exposing one main surface of the functional layer, (c)
A step of forming a metal film having a periodic pattern on one main surface of the semiconductor light emitting functional layer; (d) an alloy layer of a metal film and a semiconductor layer located on one main surface of the semiconductor light emitting functional layer by performing a heat treatment Forming a contact alloy layer made of the following in a semiconductor layer located on one main surface of the semiconductor light-emitting functional layer: (e) removing a residual metal film that does not become a contact alloy layer; Forming a highly conductive reflective film on one main surface of the semiconductor light emitting functional layer.

For example, the semiconductor light emitting function layer can be constituted by a DH structure including a first clad layer, an active layer, and a second clad layer. The first cladding layer is a semiconductor layer of the first conductivity type,
The second cladding layer is a semiconductor layer of the second conductivity type. First
The conductivity type and the second conductivity type are opposite to each other, and pn
By the current injection through the junction, light having a wavelength specific to the semiconductor is emitted to form a semiconductor light emitting functional layer. In this case, first, at least a first cladding layer, an active layer, and a second cladding layer are sequentially epitaxially grown on the starting substrate, and then the starting substrate is selectively removed, and the main surface of the first cladding layer is removed. If it is exposed, one main surface of the semiconductor light emitting functional layer is exposed. When the main surface of the first cladding layer is exposed, a metal film having a periodic pattern is formed on the main surface of the first cladding layer, and heat treatment is performed to alloy the metal film with the semiconductor layer forming the first cladding layer. A contact alloy layer comprising a layer is formed inside the first cladding layer. Then, by removing the remaining metal film that does not become the contact alloy layer and laminating a highly conductive reflective film on the main surface of the first cladding layer, a semiconductor light emitting device can be manufactured.

As a result, on one main surface of the semiconductor light emitting function layer of the semiconductor light emitting element, a region directly joined to the highly conductive reflective film and an indirectly connected to the highly conductive reflective film via the contact alloy layer. The regions to be joined are formed alternately and periodically. The region directly joined to the highly conductive reflective film is a “highly optically reflective region” which has a high electrical contact resistance, has good interface morphology, and has a high optical reflectance. on the other hand,
In the region that is indirectly bonded to the highly conductive reflective film via the contact alloy layer, the interface morphology is reduced and the optical reflectivity is sacrificed, but good ohmic characteristics with low electrical contact resistance are achieved. "Ohmic contact area" shown in FIG.

According to the method for manufacturing a semiconductor light emitting device according to the second aspect of the present invention, light emitted from the semiconductor light emitting functional layer is transmitted to the highly conductive reflective film and the semiconductor light emitting functional layer in the high optical reflection region. A semiconductor light emitting element having a structure in which light is reflected at the interface of the above, transmits through the semiconductor light emitting functional layer again, and is emitted from the other main surface can be easily manufactured. In this semiconductor light emitting device, although the reflectance is lower than that of the high optical reflection region, the light emitted from the semiconductor light emitting functional layer is reflected also in the ohmic contact region. Since the reflectance in the high optical reflection region is high, the light extraction efficiency of the semiconductor light emitting device can be improved as a whole. On the other hand, since there is an ohmic contact region where a low ohmic contact can be obtained, a parasitic resistance component connected in series is small, light can be emitted at a low operating voltage, and luminous efficiency can be increased. In other words, according to the method for manufacturing a semiconductor light emitting device according to the second aspect of the present invention, a semiconductor light emitting device having a structure capable of relaxing the trade-off relationship between optical reflection characteristics and electrical characteristics can be easily manufactured.

In the method for manufacturing a semiconductor light emitting device according to the second aspect of the present invention, a conductive flat plate is formed on the main surface of the highly conductive reflective film opposite to the side joined to one main surface of the semiconductor light emitting functional layer. It is preferable that the method further includes a step of further joining By further joining the conductive flat plate, the conductive flat plate functions as one main electrode of the semiconductor light emitting element and mechanically (physically) reinforces the highly conductive reflective film.
At this time, if the highly conductive reflective film and the conductive flat plate are bonded by thermocompression bonding, stable mechanical bonding can be easily obtained.

[0024]

Next, a semiconductor light emitting device according to an embodiment of the present invention and a method for manufacturing the same will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thickness of each layer, the ratio of the thickness, and the like are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. In addition, it is needless to say that dimensional relationships and ratios are different between drawings.

(Semiconductor Light Emitting Element) As shown in FIG. 1, a semiconductor light emitting element 1 according to the embodiment of the present invention has a semiconductor light emitting function layer 4 and a semiconductor light emitting function on one main surface of the semiconductor light emitting function layer 4. It is composed of a contact alloy layer 5 periodically provided on a part of the layer 4 and a highly conductive reflective film 3 joined to one main surface of the semiconductor light emitting functional layer 4 via the contact alloy layer 5. ing. Here, the semiconductor light-emitting functional layer 4 has a laminated structure for emitting light having a wavelength unique to the semiconductor by current injection through a pn junction. In FIG. 1, the n-type first clad layer 6 and the first It comprises an active layer 7 above the cladding layer 6 and a p-type second cladding layer 8 above this active layer 7. Further, a p-type current diffusion layer 9 is provided above the second cladding layer 8. Further, the conductive flat plate 2 is bonded to the main surface of the highly conductive reflective film 3 on the side opposite to the side bonded to the semiconductor light emitting functional layer 4. The conductive flat plate 2 functions as one main electrode (cathode electrode) of the semiconductor light emitting device 1 and mechanically (physically) reinforces the highly conductive reflective film 3. On the other hand, on the other main surface (outer surface) side of the semiconductor light emitting function layer 4, another main electrode (anode electrode) 10 electrically connected to the current diffusion layer 9 is formed. In an actual semiconductor light emitting device, a configuration may be adopted in which an n-type current block layer or the like is provided in a part of the p-type current diffusion layer 9. Further, a p-type contact layer having a higher impurity density than the p-type current diffusion layer 9 may be provided between the p-type current diffusion layer 9 and the other main electrode (anode electrode) 10. Similarly, an n-type contact layer having a higher impurity density than the n-type first cladding layer 6 is further provided at a position near the interface between the n-type first cladding layer 6 and the contact alloy layer 5. Is also good.

As shown in FIG. 1, one main surface of the semiconductor light emitting function layer 4 of the semiconductor light emitting device 1 according to the embodiment of the present invention has a region directly joined to the highly conductive reflective film 3 and a contact. Regions indirectly bonded to the highly conductive reflective film 3 via the alloy layer 5 are alternately and periodically formed. The region directly joined to the highly conductive reflection film 3 is a high optical reflection region having a high electrical contact resistance, good interface morphology, and high optical reflectivity. On the other hand, in a region which is indirectly joined to the highly conductive reflective film 3 via the contact alloy layer 5, the interface morphology is reduced and the optical reflectivity is sacrificed, but the low electrical contact resistance is good. This is an ohmic contact region exhibiting excellent ohmic characteristics.

In the semiconductor light emitting device 1 according to the embodiment of the present invention, the light emitted from the semiconductor light emitting function layer 4 is transmitted to the high conductive reflection film 3 and the semiconductor light emitting function layer 4 in the high optical reflection region. Reflected at the interface, the semiconductor light emitting functional layer 4
And exits from the window on the other main surface side where the other main electrode (anode electrode) 10 is not formed. Also,
Although the reflectivity is lower than the high optical reflection area, it also reflects in the ohmic contact area. Since the reflectance in the high optical reflection region is high, the light extraction efficiency of the semiconductor light emitting device 1 can be improved as a whole. On the other hand, since there is an ohmic contact region where a low ohmic contact can be obtained, a parasitic resistance component connected in series is small, light can be emitted at a low operating voltage, and luminous efficiency can be increased. That is, according to the semiconductor light emitting device 1 according to the embodiment of the present invention, the trade-off relationship between optical reflection characteristics and electric characteristics (low-resistance ohmic contact on the cathode electrode side) can be relaxed. If the interval between the contact alloy layers 5 is selected to the extent of the carrier diffusion length, it is inevitable that the resistance becomes slightly higher than when the contact alloy layers 5 are formed over almost the entire surface. Layer 5
Is formed on almost the entire surface, a considerably close contact resistance can be obtained.

The conductive flat plate (metal substrate) 2 is preferably formed of a metal plate such as aluminum (Al). The conductive flat plate (metal substrate) 2 has a thickness (about 70 μm to 500 μm in the embodiment of the present invention) that functions as a support member for the highly conductive reflective film 3 and the semiconductor light emitting function layer 4. Is preferred. For example, a metal plate that forms a package or a stem can be used as the conductive flat plate 2.

Although the conductive flat plate is not limited to a substrate made of a metal material as in the embodiment of the present invention, a material having good thermal conductivity and low resistivity is used. It is desirable that As a material satisfying these conditions, if it is a metal material, aluminum (Al), gold (Au), copper (Cu), molybdenum (Mo), rhodium (Rh) or the like as in the metal substrate 2 is used. It can be used. If a semiconductor material is used for the conductive flat plate, for example, silicon (S) doped with impurities at a relatively high impurity density and having a small resistivity (S
i), a semiconductor material such as diamond can be used. Since this conductive flat plate functions as a cathode electrode as one main electrode of the semiconductor light emitting function layer 4, the conductive flat plate is provided within a range that satisfies the relationship with the work function of the joining member on the semiconductor light emitting function layer 4 side. Of course, it may be composed of a material other than those exemplified above.

The highly conductive reflective film 3 laminated on the upper surface of the metal substrate 2 is formed of the same aluminum (Al) as the metal substrate 2 in the embodiment of the present invention. The highly conductive reflective film 3 converts the light emitted from the active layer 7 toward one main surface side (lower side) of the semiconductor light emitting functional layer 4 into the n-type clad layer 6 and the highly conductive reflective film 3. It has the function of reflecting light at the interface with. That is, the highly conductive reflective film 3 forms a reflective surface having good surface morphology at the interface with the n-type clad layer 6 formed on the upper surface thereof, and emits light from the active layer 7 to the lower side of the semiconductor light emitting functional layer 4. The light traveling toward the semiconductor light emitting functional layer 4
Has the effect of reflecting at a high reflectance toward the upper side (the other main surface side).

The highly conductive reflective film 3 is in ohmic contact with the contact alloy layer 5 with low contact resistance. Therefore, as a material constituting the highly conductive reflective film 3, a wavelength in a specific band in which light is emitted from the active layer 7 (for example, 5 in the embodiment of the present invention).
(55 nm to 650 nm) is desired to be a metal material capable of favorably reflecting light and capable of favorably forming a low resistance contact surface with the contact alloy layer 5. That is, metal materials satisfying such conditions include aluminum (Al), gold (Au), and silver (A
g) and the like can be used. For example, if Al is used, the reflectance for light in a specific band wavelength (555 nm to 650 nm in the embodiment of the present invention) emitted from the active layer 7 can be made about 90%.

The n-type cladding layer 6 is made of (Al_xG
a_1-x)_yIn_1-yMade of P compound semiconductor
You. Also for contacts that make up the ohmic contact area
The alloy layer 5 becomes the n-type clad layer 6 (Al_xGa
_1-x)_yIn_1-yEach element constituting P compound semiconductor
And an alloy of a metal such as Au and Ge. others
Therefore, the contact alloy layer 5 is in contact with the highly conductive reflective film 3.
Low resistance ohmic material on both the surface and the interface with the n-type cladding layer 6.
Forming a contact surface. As a result, the anode electrode 1
Current from 0 to metal substrate 2 as cathode electrode
Are two low resistances exhibited by the contact alloy layer 5.
Flow through the ohmic contact surface. Note that (Al_xGa
_1-x)_yIn_1-yEach element constituting P compound semiconductor
And contact alloy layer 5 composed of elements such as Au and Ge
, Such as GaAs, because the alloy is formed in fine particles
It does not become a perfect light absorber, and does not respond to light emitted from the active layer 7.
About 30 to 50%. Accordingly
Then, light is emitted from the active layer 7 and one of the semiconductor light emitting functional layers 4
Light traveling toward the main surface side (lower side) passes through the n-type cladding layer 6
Interface having good surface morphology with conductive reflective film 3
Reflected by the high optical reflection area,
Is connected to the n-type cladding layer 6 in the ohmic contact region.
The light is also reflected at the interface of the tact alloy layer 5.

The n-type cladding layer 6 is made of, for example, silicon (S
i) doped (Al_xGa_1-x)_yIn
_1-yP (0.3 ≦ x ≦ 1), n-type
The lower surface of the cladding layer 6 is in contact with the highly conductive reflective film 3.
And alternately and periodically contact the alloy layer 5. Note that FIG.
Is a plan view of the contact alloy layer 5 and the n-type clad layer 6.
FIG. As shown in FIG.
The alloy layer 5 is connected to the n-type cladding layer 6 in an island shape.
It is arranged periodically. This alloy layer for contact 5
Lower surface of n-type cladding layer 6 (one side of semiconductor light emitting functional layer 4)
Thermal diffusion of Au-Ge / Au from the main surface of
To form the n-type cladding layer 6 (Al _xG
a_1-x)_yIn_1-yP-based compound semiconductors and Au-G
It is configured by alloying e / Au. In this way,
Since the tact alloy layer 5 is periodically formed in an island shape,
From the n-type cladding layer 6 via the contact alloy layer 5
The current path leading to the highly conductive reflective film 3 is periodically formed in an island shape.
Is done. On the other hand, the n-type cladding layer 6 and the highly conductive reflection film 3
With good surface morphology composed of
High optical reflection area consisting of launch surface is formed in a periodic lattice
Is done.

The n-type clad layer 6 is laminated on the upper surface.
The active layer 7 is, for example, (Al_xGa _1-x)_yIn
_1-yP (0.2 ≦ x ≦ 1). Active layer
7 have a narrower forbidden band width than the n-type cladding layer 6 (Al_x
Ga_1-x)_yIn_1-yFormed with P (0.2 ≦ x ≦ 1)
In this case, the active layer 7 has a wavelength of 555 nm to 650 nm.
It can emit long light. Further, the upper surface of the active layer 7
The p-type cladding layer 8 laminated on the
Wide p-type semiconductor layer, for example Zn doped
(Al_xGa_1-x)_yIn_1-yP (0.3 ≦ x ≦
If formed in 1), the DH structure effectively forms the active layer 7.
Since the carriers are confined, the luminous efficiency increases.
The active layer 7 has a single quantum well (SQW) structure or a multiple quantum well (SQW) structure.
A quantum well (MQW) structure may be used.

The current spreading layer 9 laminated on the upper surface of the p-type cladding layer 8 is made of, for example, GaP, Ga _x In _1-x
P, or and a p-type semiconductor layer, such as _Al x _{Ga 1-x} As. The current diffusion layer 9 spreads the current from the anode electrode 10 in the plane direction so that holes can be injected into the entire surface of the p-type cladding layer 8. For this reason, the light emitting region is expanded in the outer peripheral direction of the other main electrode (anode electrode) 10 serving as a light shielding portion, and has a function of extracting light more effectively. The current diffusion layer 9, the p-type cladding layer 8, the active layer 7, and the n-type cladding layer 6 are formed by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE).
It is formed by continuous epitaxial growth by a chemical beam epitaxy (CBE) method, a molecular layer epitaxy (MLE) method, or the like.

In the semiconductor light emitting device 1 having such a configuration,
Of the light emitted from the active layer 7, the lower side (the semiconductor light emitting functional layer 4)
(The one main surface side) can be satisfactorily reflected by the high optical reflection region located at the interface between the n-type cladding layer 6 and the highly conductive reflection film 3. In addition, light can be reflected at the interface between the n-type cladding layer 6 and the contact alloy layer 5 located in the ohmic contact region. Therefore, of the light emitted from the active layer 7, light traveling downward can be guided with high efficiency toward the upper side of the semiconductor light emitting element 1 (the other main surface side of the semiconductor light emitting functional layer 4),
The light extraction efficiency of the entire semiconductor light emitting device 1 can be increased. Therefore, high brightness of the semiconductor light emitting device 1 can be achieved.

Since a low-resistance current path is formed between the anode electrode 10 and the metal substrate 2 functioning as a cathode electrode by the contact alloy layer 5 located in the ohmic contact region, the forward voltage Descent is reduced,
The electrical characteristics are also good.

In the semiconductor light emitting device 1 according to the embodiment of the present invention, it is not necessary to add a semiconductor substrate having a light transmission characteristic in order to increase the light extraction efficiency in the conventional semiconductor light emitting device. Can be easier. Of course, since it is not necessary to add a semiconductor substrate having light transmission characteristics, light transmission characteristics and electrical characteristics (low-resistance ohmic contact on the cathode electrode side) do not have a trade-off relationship. In addition, as in the case of the DBR structure, if the spectral band of the wavelength for the reflection is widened, the problem that the reflectance for the peak wavelength must be lowered does not occur, and the high reflectance in the spectral band of the wide wavelength band does not occur. Can be obtained.

As described above, in the semiconductor light emitting device 1 according to the embodiment of the present invention, the electrical characteristics are good, and the light extraction efficiency can be increased, so that a higher luminance can be achieved. Further, in the semiconductor light emitting device 1, the manufacturing process is facilitated, so that the manufacturing yield can be improved.

(Method of Manufacturing Semiconductor Light-Emitting Element) Next, a method of manufacturing a semiconductor light-emitting element according to the embodiment of the present invention will be described with reference to FIGS.

(A) First, a GaAs substrate having a thickness of about 250 μm to 450 μm is mounted on a susceptor of a low-pressure MOCVD apparatus (not shown), and the MOCVD method is used.
On this GaAs substrate, an n-type clad layer 6, an active layer 7, a p-type clad layer 8, and a current diffusion layer 9 are sequentially vapor-phase epitaxially grown. For example, when growing by the reduced pressure MOVPE method, the substrate temperature 55
At 0 ° C. to 700 ° C., TMA (trimethylaluminum), TEG (triethylgallium), TMIn (trimethylindium), and PH ₃ (phosphine) are introduced, and n-type (Al _x Ga _1-x ) _y In _{1 1− y} P (0.
3 ≦ x ≦ 1) first cladding layer 6, not doped with impurities intentionally _{(Al x Ga 1-x)} y In 1-y P (0.2
≦ x ≦ 1) active layer 7, p-type _{(Al x Ga 1-x)} y I
n _{1 -yP} (0.3 ≦ x ≦ 1) The second cladding layer 8 is continuously grown. Further, the supply of TMA is stopped, and TEG,
TMIn, and the p-type by introducing _{PH 3 Ga x In 1-x} P
A current spreading layer 9 is continuously grown on the second cladding layer 8. TBP (tertiary butyl) instead of PH ₃
(Phosphine) may be used. For the first cladding layer 6, SiH ₄ (monosilane), Si ₂ H ₆ (disilane), DESe (diethyl selenium), DETe (diethyl tellurium), or the like may be used as an n-type dopant gas. In the second cladding layer 8, as a p-type dopant gas, for example, DEZn (diethyl zinc), CP ₂ M
A dopant gas such as g (biscyclopentadienyl magnesium) or a solid Be source may be used.
Before the n-type cladding layer 6 is formed by vapor phase epitaxial growth, the buffer layer may be grown by vapor phase epitaxial growth. After the continuous vapor phase epitaxial growth is completed, the laminated structure (epitaxial substrate) is
After taking out from the CVD apparatus, the surface of the current diffusion layer 9 and the side surfaces of the laminated structure are covered with a protective film such as a photoresist. Thereafter, the epitaxial substrate is fixed to a polishing jig,
Grind and polish the s substrate. The thickness of the GaAs substrate is
At the stage of 10 to 30 μm, the epitaxial substrate is removed from the polishing jig and wet-etched until the n-type cladding layer 6 is exposed. As a result, light emitted from the active layer 7 (555 nm to 65 nm in the embodiment of the present invention).
0 nm), the GaAs substrate having the light absorption property is removed, and as shown in FIG. 4, the current diffusion layer 9, the p-type cladding layer 8,
A semiconductor light emitting functional layer 4 having a structure in which an active layer 7 and an n-type clad layer 6 are sequentially laminated is prepared.

(B) Next, as shown in FIG. 5, gold (Au) and germanium (Ge) are sequentially formed on one main surface of the semiconductor light emitting function layer 4, that is, on the surface of the n-type cladding layer 6. )
The Au—Ge alloy film 11 and the Au film 12 made of the alloys described above are deposited by a vacuum evaporation method.

(C) Thereafter, photolithography is performed so that a resist as an etching mask remains on the Au—Ge alloy film 11 / Au film 12 in the region where the contact alloy layer 5 is to be formed in the n-type cladding layer 6. The resist is patterned using the fee technology. Then, using the resist as an etching mask, the Au—Ge alloy film 11 / Au film 12 is transformed into iodine (I ₂ ) / potassium iodide (K).
I) Etching is performed with an etching solution such as a solution. As a result, as shown in FIG. 6, the Au-Ge alloy film 11 / Au film 12 has a structure in which islands are left on the surface of the n-type cladding layer 6. Alternatively, before depositing the Au—Ge alloy film 11 /, Au film 12 by a vacuum deposition method, the resist is patterned using a photolithography technique, and the resist is peeled off after the vacuum deposition. An island pattern of the Au—Ge alloy film 11 / Au film 12 shown in FIG. 6 may be formed.

(D) Next, as shown in FIG. 7, the semiconductor light-emitting functional layer 4 processed as described above is subjected to a predetermined heat treatment. By the heat treatment for forming the alloy layer 6, Au-G
From the e alloy film 11 / Au film 12, each constituent element is n
The alloy is diffused into the mold cladding layer 6 to a predetermined depth and alloyed. As a result, the contact alloy layer 5 is formed inside the n-type cladding layer 6 near the interface between the Au—Ge alloy film 11 and the n-type cladding layer 6. At the same time, some of the constituent elements of the n-type cladding layer 6 diffuse outward to the Au—Ge alloy film 11 / Au film 12. If it is necessary to prevent outward diffusion, a barrier metal such as nickel (Ni) / titanium (Ti) may be formed. Further, the Au—Ge alloy film 11 and the Au film 1
7, the constituent elements of the interface also diffuse into each other and alloy with each other. Therefore, as shown in FIG.
On top of this, an integrated alloy film 1 fused by heat treatment
3 (however, in detail, it has a profile of each component element in the depth direction).

(E) Thereafter, the alloy film 13 formed on the upper surface of the n-type cladding layer 6 is selectively removed with an etching solution such as an I ₂ -KI solution. Thereby, as shown in FIG. 8, the surface of the n-type cladding layer 6 is flattened, and the contact alloy layer 5 is exposed on the surface of the n-type cladding layer 6 in an island shape. At this time, chemical mechanical polishing (CMP)
By such a method, the surface of the n-type cladding layer 6 may be polished to a mirror surface and flattened.

(F) Next, as shown in FIG. 9, aluminum (A) is formed on the exposed surfaces of the n-type cladding layer 6 and the contact alloy layer 5 (one main surface of the semiconductor light emitting function layer 4).
1) is vacuum-deposited to a predetermined thickness (for example, 1 μm to 10 μm).
A highly conductive reflective film 3 (about μm) is formed. After vacuum deposition of aluminum (Al), at 380 ° C. to 420 ° C., 15
The sintering is performed for 30 seconds to 30 seconds, and the highly conductive reflective film 3 is densely contacted and joined to the surfaces of the n-type cladding layer 6 and the contact alloy layer 5. The sintering is performed in a short time using infrared lamp heating or the like so that the alloy reaction at the interface does not progress. This is to prevent the morphology of the interface between the n-type cladding layer 6 and the highly conductive reflective film 3 from being degraded. Therefore, this sintering step can be omitted.

(G) Then, as shown in FIG. 10, a metal substrate 2 made of aluminum (Al) and having a predetermined thickness of, for example, about 70 μm to 500 μm and having a mirror-finished surface, as shown in FIG. Prepare The separately prepared metal substrate 2 and the highly conductive reflective film 3 formed in the above process
Are adhered to each other and bonded together by a thermocompression bonding method. FIG. 11 shows a state where the metal substrate 2 and the reflective substrate film 3 are adhered.

(H) Finally, on the surface of the current diffusion layer 9 (the other main surface of the semiconductor light emitting function layer 4), for example, a chromium (Cr) film and an Au film are sequentially laminated by a vacuum deposition method. A / Au structure anode electrode film 10A is formed on the entire surface. After that, the anode electrode film 10A is processed by using the photolithography technique and the etching technique to form the anode electrode 10 as shown in FIG. Alternatively, before depositing the anode electrode film 10A having a Cr / Au structure by a vacuum evaporation method, the resist is patterned using a photolithography technique, and the resist is peeled off after the vacuum evaporation. The pattern of the Cr / Au structure anode electrode film 10A shown in FIG. As a result, the manufacture of the semiconductor light emitting device 1 as shown in FIG. 13 is completed.

In the method for manufacturing a semiconductor light emitting device according to the embodiment of the present invention, the low-resistance contact alloy layer 5 is formed in the n-type clad layer 6 according to the processed shape of the alloy film 13. I can do it. Therefore, at the interface between the n-type cladding layer 6 and the highly conductive reflective film 3, an ohmic contact region where a low-resistance ohmic contact can be made and a high optical reflectivity having a good interface morphology are provided. It is possible to easily form a structure in which the optical reflection region is periodically and alternately repeated.

(Modification of Manufacturing Method of Semiconductor Light Emitting Element) Next, a modification of the manufacturing method of the semiconductor light emitting element according to the embodiment of the present invention will be described.

(A) The steps up to FIG. 5 are the same as those described above. That is, as shown in FIG. 5, on one main surface of the semiconductor light emitting function layer 4, that is, on the surface of the n-type cladding layer 6, an alloy of gold (Au) and germanium (Ge) is sequentially formed. The Au—Ge alloy film 11 and the Au film 12 are deposited by a vacuum evaporation method. In this modification, FIG.
Unlike the first embodiment, the island pattern of the Au—Ge alloy film 11 / Au film 12 is not formed. Then, the Au—Ge alloy film 11
A predetermined heat treatment is applied to the semiconductor light emitting functional layer 4 on which the / Au film 12 is deposited on the entire surface. By the heat treatment for forming the alloy layer 6, the contact alloy layer 5 is formed on the entire surface inside the n-type cladding layer 6 near the interface between the Au—Ge alloy film 11 and the n-type cladding layer 6.

(B) Thereafter, the alloy film 13 remaining on the entire upper surface of the n-type cladding layer 6 is selectively removed with an etching solution such as an I ₂ -KI solution. Then, the resist is patterned using a photolithography technique so that the resist serving as an etching mask remains on the region where the contact alloy layer 5 is to be formed. And
Using the resist as an etching mask, a part of the contact alloy layer 5 formed on the entire surface is selectively etched by reactive ion etching (RIE) until the n-type cladding layer 6 is exposed. For example, if the depth of the contact alloy layer 5 is 0.5 μm to 0.7 μm, a U groove having a depth of about 1 μm is formed. As a result, a U-shaped groove is formed in a planar shape as shown in FIG. That is, the convex portion surrounded by the U groove is formed as an island as the contact alloy layer 5.

(C) Next, the surface of the contact alloy layer 5 and the entire surface of the n-type cladding layer 6 exposed at the bottom of the U groove are sufficiently thicker than the depth of the U groove, for example, Aluminum (Al) of about 2 μm to 10 μm is vacuum-deposited to form a highly conductive reflective film 3. After vacuum deposition, sintering is performed at 380 ° C. to 420 ° C. for 15 to 30 seconds. Thereafter, the surface of the highly conductive reflective film 3 is polished and flattened by a technique such as CMP until the surface of the highly conductive reflective film 3 becomes a mirror surface. At this time, the highly conductive reflective film 3 may be polished until the contact alloy layer 5 is exposed.

(D) Then, as in FIG.
A metal substrate (conductive flat plate) 2 having a thickness of about 0 μm to 500 μm and a mirror-finished surface is prepared. The separately prepared metal substrate 2 and the highly conductive reflective film 3 are brought into close contact with each other and bonded together by a thermocompression bonding method (the highly conductive reflective film 3 is polished until the contact alloy layer 5 is exposed). In this case, the contact alloy layer 5 and the metal substrate 2 are directly joined via Al embedded in the U groove.) The steps after FIG. 11 are the same as those described above, and thus are omitted.

(Other Embodiments) As described above, it should not be understood that the description and drawings constituting a part of the disclosure of the embodiments of the present invention limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art. For example, in the above-described embodiment of the present invention, the metal substrate 2 is used as the conductive flat plate. However, a semiconductor substrate made of silicon or the like doped with a high impurity density of about 10 ¹⁹ cm ⁻³ to 10 ²¹ cm ⁻³ or Alternatively, a laminate of a semiconductor substrate and a metal layer can be used.

In the above description of the embodiment, the contact alloy layer 5 as the ohmic contact region is arranged in an island shape with respect to the n-type clad layer 6 as the high optical reflection region. As shown, the contact alloy layer 5 serving as an ohmic contact region may be formed in a lattice shape, and the n-type clad layer 6 serving as a high optical reflection region may be formed in an island shape. Further, the present invention is not limited to the square islands shown in FIGS. 2 and 3, but may be a rectangle or a polygon such as a hexagon. Therefore, various topologies such as a honeycomb shape can be adopted as the shape of the lattice.

In the method of manufacturing a semiconductor light emitting device described with reference to FIGS. 4 to 13, the highly conductive reflective film 3 is formed on the semiconductor light emitting functional layer 4, and this is formed on a metal substrate (conductive flat plate).
2, the highly conductive reflective film 3 may be formed on the metal substrate 2 in advance, and the semiconductor light emitting functional layer 4 may be adhered to this.

In the method of manufacturing a semiconductor light emitting device described with reference to FIGS. 4 to 13, the highly conductive reflective film 3 and the metal substrate 2 are formed of the same material (Al). There may be.

When the conductive flat plate 2 has light reflectivity, the high conductive reflective film 3 is omitted, and the conductive flat plate 2 is directly bonded to the semiconductor light emitting function layer 4 by a direct bonding method. Is also good. That is, one main surface of the semiconductor light-emitting functional layer 4 is polished to a mirror surface, and the conductive flat plate 2 whose surface is further finished to a mirror surface is prepared. May be closely adhered to each other, and both may be bonded to each other by a thermocompression bonding method. At this time, a metal film functioning as a highly conductive reflective film 3 and an alloy layer functioning as a contact alloy layer 5 are periodically arranged on the conductive flat plate 2 side as shown in FIG. 2 or FIG. The surface may be mirror-finished and joined to one main surface of the semiconductor light emitting functional layer 4 (in this case, the contact alloy layer 5 can be omitted on one main surface side of the semiconductor light emitting functional layer 4). .

Further, in the above description of the embodiment, the wavelength band of light emitted from the active layer 7 is 555 nm to 650 nm.
Although it is set to about m, the emission wavelength is appropriately changed according to the emission characteristics of the active layer 7.

Further, a highly conductive reflection film is formed of vacuum-deposited gold (Au), and a plating film having a thickness of 10 μm to 50 μm is formed thereon.
The conductive flat plate 2 may be formed by performing Au plating of μm.

As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the claims that are appropriate from the above description.

[0063]

According to the present invention, on one main surface of the semiconductor light emitting functional layer, a high optical reflection region having good interface morphology and high optical reflectance and a low electrical contact resistance are provided. Ohmic contact regions exhibiting good ohmic characteristics are alternately and periodically arranged. Therefore, it is possible to provide a semiconductor light emitting device with low operating voltage, high light extraction efficiency, high luminance, and high efficiency.

Further, according to the present invention, a semiconductor light emitting device having high light extraction efficiency can be manufactured with a high manufacturing yield.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is an explanatory plan view showing an arrangement topology of an alloy layer forming an ohmic contact region and an n-type cladding layer forming a high optical reflection region in the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 3 is an explanatory plan view showing an arrangement topology of an ohmic contact region and a high optical reflection region of a semiconductor light emitting device according to another embodiment.

FIG. 4 is a process cross-sectional view (part 1) illustrating a process for manufacturing the semiconductor light-emitting device according to the embodiment of the present invention.

FIG. 5 is a process cross-sectional view (No. 2) illustrating the process of manufacturing the semiconductor light-emitting device according to the embodiment of the present invention.

FIG. 6 is a process sectional view (3) showing a step for manufacturing the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 7 is a process cross-sectional view (No. 4) showing the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 8 is a process cross-sectional view (No. 5) showing the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 9 is a process cross-sectional view (part 6) illustrating the process for manufacturing the semiconductor light-emitting device according to the embodiment of the present invention.

FIG. 10 is a process cross-sectional view (No. 7) showing the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 11 is a process sectional view (8) showing a step for manufacturing the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 12 is a process cross-sectional view (No. 9) showing the manufacturing process of the semiconductor light-emitting device according to the embodiment of the present invention.

FIG. 13 is a process sectional view (10) showing a step for manufacturing a semiconductor light-emitting device according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor light emitting element 2 conductive flat plate (one main electrode: cathode electrode) 3 highly conductive reflective film 4 semiconductor light emitting functional layer 5 alloy layer for contact 6 first clad layer (n-type clad layer) 7 active layer 8 second Cladding layer (p-type cladding layer) 9 Current diffusion layer 10 The other main electrode (anode electrode) 11 Au-Ge alloy film 12 Au film 13 Alloy film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Takeda 3-6-3 Kitano, Niiza City, Saitama Prefecture Within Sanken Electric Co., Ltd. (72) Inventor Hidekazu Aoyagi 3-6-3 Kitano, Niiza City, Saitama Prefecture F-term (reference) in Nippon Electric Co., Ltd. 5F041 AA03 AA04 AA41 CA04 CA05 CA12 CA34 CA36 CA73 CA74 CA77 CB15

Claims (12)

[Claims] 1. A semiconductor light emitting functional layer having a laminated structure for emitting light having a wavelength unique to a semiconductor by current injection through a pn junction, and an alternating and periodic structure on one main surface of the semiconductor light emitting functional layer. 1. A semiconductor light emitting device comprising: a high optical reflection region having a high optical reflectivity; and an ohmic contact region having a low electrical contact resistance. 2. The semiconductor light emitting functional layer, wherein the ohmic contact region is a contact alloy layer periodically provided on a part of the semiconductor light emitting functional layer on the one main surface of the semiconductor light emitting functional layer. 2. The semiconductor light emitting device according to claim 1, further comprising: a highly conductive reflective film bonded to said one main surface via said contact alloy layer. 3. The high optical reflection region is formed at an interface between the one main surface of the semiconductor light emitting function layer and the high conductive reflection film in a region where the contact alloy layer is not disposed. 3. The semiconductor light emitting device according to claim 2, wherein: 4. The semiconductor light-emitting functional layer includes: a first conductive type first cladding layer having the one main surface in common; an active layer above the first cladding layer; A second conductive type opposite to the first conductive type;
The semiconductor light emitting device according to any one of claims 1 to 3, further comprising at least a conductive second clad layer. 5. The semiconductor device according to claim 1, wherein the contact alloy layer is periodically arranged in an island shape at an interval substantially equal to a carrier diffusion length near one main surface of the semiconductor light emitting function layer. The semiconductor light emitting device according to claim 2 or 3, wherein: 6. The contact alloy layer is periodically provided in a lattice at intervals substantially equal to a carrier diffusion length near one main surface of the semiconductor light emitting function layer. The semiconductor light emitting device according to claim 2 or 3, wherein: 7. A conductive flat plate is further bonded to a main surface of the highly conductive reflective film on a side opposite to a side bonded to the semiconductor light emitting functional layer. 2. The semiconductor light emitting device according to claim 1. 8. The semiconductor light emitting functional layer, wherein the ohmic contact region is a contact alloy layer periodically provided on a part of the semiconductor light emitting functional layer on the one main surface of the semiconductor light emitting functional layer. 2. The semiconductor light emitting device according to claim 1, further comprising: a conductive flat plate joined to said one main surface via said contact alloy layer. 9. The high optical reflection region is formed at an interface between the one main surface of the semiconductor light emitting function layer and the conductive flat plate in a region where the contact alloy layer is not disposed. The semiconductor light emitting device according to claim 8, wherein: 10. A step of forming a semiconductor light emitting functional layer including at least a pn junction on a starting substrate, and selectively removing the starting substrate to expose one main surface of the semiconductor light emitting functional layer. Forming a metal film having a periodic pattern on the one main surface of the semiconductor light emitting function layer; and performing a heat treatment to position the metal film and the semiconductor light emitting function layer on the one main surface. Forming a contact alloy layer composed of an alloy layer with a semiconductor layer inside the semiconductor layer located on the one main surface of the semiconductor light-emitting functional layer; and the remaining metal that does not become the contact alloy layer A method for manufacturing a semiconductor light emitting device, comprising: removing a film; and laminating a highly conductive reflective film on the one main surface of the semiconductor light emitting functional layer. 11. The method according to claim 11, further comprising a step of further bonding a conductive flat plate to a main surface of the highly conductive reflection film on a side opposite to a side bonded to the one main surface of the semiconductor light emitting functional layer. A method for manufacturing a semiconductor light emitting device according to claim 10. 12. The method according to claim 11, wherein the highly conductive reflective film and the conductive flat plate are bonded by thermocompression bonding.