JP2005354020A - Semiconductor light emitting device manufacturing method and semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device manufacturing method and a semiconductor light emitting device with extremely high light extraction efficiency.
In the present invention, a refractive index on a light extraction surface is formed by forming a periodic structure A1 formed on a light extraction surface of a semiconductor light-emitting element 10 with a period equal to or less than twice the average optical wavelength of light. The difference can be eased. Therefore, reflection on the light extraction surface can be prevented, and high light extraction efficiency can be realized. Furthermore, since the fine periodic mask can be formed by heating the Au thin film, the periodic structure A1 can be formed easily and inexpensively.
[Selection] Figure 7

Description

  The present invention relates to a semiconductor light emitting device manufacturing method and a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device manufacturing method and a semiconductor light emitting device in which a light emitting portion composed of at least an n-type semiconductor layer and a p-type semiconductor layer is stacked on a substrate.

  Conventionally, a low-temperature deposition buffer layer (1986 H. Amano, N. Sawaki, I. Akasaki and Y. Toyoda: Appl. Phys. Lett., 48 (1986) 353) was formed as this type of semiconductor light emitting device. Has been proposed. In addition, p-type conductivity control (1989 H. Amano, M. Kito, K. Hiramatsu and I. Akasaki: Jpn. J. Appl. Phys. 28 (1989) L2112) and n-type conductivity control (1991 H Amano and I. Akasaki: Mat. Res. Soc. Ext, Abst., EA-21 (1991) 165) has also been proposed. Furthermore, a semiconductor light emitting device created by applying a method for producing a highly efficient light emitting layer (1991 N. Yoshimoto, T. Matsuoka, T. Sasaki and A. Katsui, Appl. Phys. Lett., 59 (1991) 2251). Devices have also been proposed.

  FIG. 13 shows a configuration of a group III nitride semiconductor light emitting device as an example of a semiconductor light emitting device to which the above technique is applied. In FIG. 1, a group 3 nitride semiconductor light emitting device 1 includes a sapphire substrate 2, and a low temperature deposition buffer layer 3 is laminated on the sapphire substrate 2. An n-GaN cladding layer 4, a GaInN light emitting layer 5, a p-AlGaN barrier layer 6, and a p-GaN contact layer 7 are sequentially stacked on the low temperature deposition buffer layer 3. Further, the p-electrode 8 is laminated on the uppermost p-GaN contact layer 7 and the n-electrode 9 is laminated on the n-GaN layer, whereby the group 3 nitride semiconductor light emitting device 1 is formed. .

  In the group III nitride semiconductor light emitting device represented by the semiconductor light emitting device having the above structure, it is possible to realize blue, green and white light emission with high luminance. In addition, for other types of semiconductor light-emitting devices such as AlGaInP and AlGaAs, it is possible to construct almost the same layer structure by using a substrate having a suitable lattice constant, realizing high luminous efficiency. Is possible.

  Even in such a semiconductor light emitting device having high light emission efficiency, if the light extraction efficiency to the outside of the semiconductor light emitting device is low, the energy conversion efficiency of the semiconductor light emitting device as a whole is low. Therefore, improvement of light extraction efficiency has been an important issue. One factor of low light extraction efficiency is that the refractive index of the semiconductor is larger than the refractive index of air. This is because when the refractive index of the semiconductor is larger than the refractive index of air, the majority of the light emitted from the light emitting layer is totally reflected and confined inside the semiconductor light emitting element.

On the other hand, a technique of molding a semiconductor light emitting element with an epoxy resin or the like having an intermediate refractive index between the refractive index of the semiconductor light emitting element and the refractive index of air is generally known (for example, Non-Patent Document 1 ,reference.). In addition, it is known that light extraction efficiency is improved by forming a large number of protrusions having a peak period of 500 nm or more on the surface layer of a semiconductor light emitting element (see, for example, Patent Document 1). According to the former configuration, an extreme difference in refractive index between the semiconductor light emitting element and air can be alleviated, so that total reflection can be reduced and light extraction efficiency can be improved. On the other hand, in the latter configuration, since the emitted light can be diffused and reflected by the unevenness and extracted, it is possible to improve the light extraction efficiency.
JP 2003-174191 A Tetsuro Ishida, Higashi Shimizu: Revised Semiconductor Device, Corona, 1980

However, in the former configuration, since the difference in refractive index at the interface is not completely eliminated, total reflection at the interface cannot be completely prevented. Further, in the latter semiconductor light emitting device, light cannot be diffused to the outside depending on the incident angle of light, or energy is attenuated by diffuse reflection, so that a drastic improvement in extraction efficiency is realized. It was not reached. Further, in the latter, it is difficult to accurately control the formation period of a large number of protrusions, and there is a problem that the cost increases.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a semiconductor light emitting device and a semiconductor light emitting device with extremely high light extraction efficiency.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a semiconductor light emitting device manufacturing method for producing a semiconductor light emitting device in which a light emitting portion composed of at least an n type semiconductor layer and a p type semiconductor layer is laminated on a substrate. ,

  A mask forming step of forming a periodic mask having a periodic pattern in which an average period is equal to or less than twice an average optical wavelength of light emitted from the light-emitting unit; And a periodic structure forming step for forming a periodic structure having a periodicity that is twice or less the wavelength.

  In the invention of claim 1 configured as described above, a semiconductor light emitting element capable of emitting light can be manufactured by laminating a light emitting portion including at least an n-type semiconductor layer and a p-type semiconductor layer on a substrate. In the mask formation step, a periodic mask having a periodic pattern having an average period that is equal to or less than twice the average optical wavelength of the light emitted from the light emitting unit is formed. In the periodic structure forming step, a periodic structure having an average period twice as long as the average optical wavelength is formed using the periodic mask. Here, in the periodic structure forming step, the periodic structure may be formed using the periodic mask, and a method of selectively laminating a portion other than the periodic mask or a portion other than the periodic mask may be selectively used. A removal method or the like can be applied.

As a specific example of the periodic structure forming step, in the invention according to claim 2, the periodic structure forming step includes an etching step of performing etching using the periodic mask as an etching resist.
In the invention of claim 2 configured as described above, the periodic structure forming step performs etching using the periodic mask as an etching resist. That is, in the periodic structure forming step, the periodic structure may be formed by etching using the periodic mask as an etching resist. As a specific method of etching, either a wet method or a dry method may be employed.

Furthermore, as another specific example of the periodic structure forming step, in the invention according to claim 3, the periodic structure forming step includes a highly reflective metal layer forming step of depositing a highly reflective metal on the periodic mask. It is as composition to do.
In the invention of claim 3 configured as described above, the periodic structure forming step forms a highly reflective metal layer by depositing a highly reflective metal on the periodic mask. That is, according to the periodic mask, since the highly reflective metal can be selectively laminated, the highly reflective metal layer can be formed into a periodic shape.

On the other hand, as a specific example of the mask forming step, in the invention according to claim 4, the mask forming step includes a deposition step of forming a coating layer by depositing a coating material, and imparts kinetic energy to the coating layer. And a kinetic energy application step.
In the invention of claim 4 configured as described above, the mask forming step includes a vapor deposition step and a kinetic energy applying step. In the said vapor deposition process, a coating layer is formed by vapor-depositing a coating material. On the other hand, in the kinetic energy application step, kinetic energy is applied to the coating layer formed in the vapor deposition step. Since the coating layer to which kinetic energy is applied can be aggregated into a large number of grains, the aggregated grains can be periodically arranged to form the periodic mask.

Furthermore, as a suitable example of the kinetic energy application step, in the invention according to claim 5, the kinetic energy application step is configured to apply kinetic energy to the coating layer by heating the coating layer.
In the invention of claim 5 configured as described above, kinetic energy can be imparted to the coating layer by heating the coating layer. In heating the coating layer, it is only necessary to apply kinetic energy uniformly to some extent, and various heating devices can be used.

As a specific example of the covering material, in the invention according to claim 6, the covering material is a metal.
In the invention of claim 6 configured as described above, a metal material can be applied as the covering material.

Furthermore, as a specific example of the covering material, in the invention according to claim 7, the covering material is configured to be Au.
In the invention of claim 7 configured as described above, Au can be applied as the covering material.

By the way, in the invention according to claim 8, in the semiconductor light emitting device in which the light emitting portion composed of at least the n-type semiconductor layer and the p-type semiconductor layer is laminated on the substrate,
A periodic mask having a periodic pattern having an average period that is equal to or less than twice the average optical wavelength of the light emitted from the light emitting section is formed, and the average period is twice the average optical wavelength by using the same period mask. The following periodic structure is formed.

  In the invention of claim 8 configured as described above, in the semiconductor light emitting device produced by the method of manufacturing a semiconductor light emitting device according to claim 1, the average optical wavelength of light emitted from the light emitting portion is not more than twice. A periodic structure having an average period is formed. By forming the periodic structure at the interface where a plurality of layers having different refractive indices are in contact, the behavior of light in the layer having the average refractive index of the plurality of layers can be realized at the same interface. That is, in the semiconductor light emitting device, it is possible to prevent an abrupt difference in refractive index at the interface from adversely affecting extraction of light emitted from the light emitting portion. Needless to say, the semiconductor manufacturing method according to any one of claims 2 to 7 may be applied in the manufacture of the semiconductor light emitting device according to claim 8.

Furthermore, in the invention according to claim 9, in the semiconductor light emitting device in which the light emitting portion composed of at least the n-type semiconductor layer and the p-type semiconductor layer is stacked on the substrate.
It is formed at an interface where a plurality of layers having different refractive indexes are in contact with each other, and has a periodic structure composed of a number of convex portions formed with an average period equal to or less than the average optical wavelength of light emitted from the light emitting unit As a configuration.

  In the invention of claim 9 configured as described above, at the interface where a plurality of layers having different refractive indexes are in contact, a large number of convex portions formed with an average period equal to or less than the average optical wavelength of light emitted from the light emitting portion. Is formed. By forming the periodic structure at the interface where a plurality of layers having different refractive indexes are in contact, the behavior of light in the layer having the average refractive index of the plurality of layers can be realized at the same interface. That is, in the semiconductor light emitting device, it is possible to prevent an abrupt difference in refractive index at the interface from adversely affecting extraction of light emitted from the light emitting portion.

As an example of a preferred configuration of the periodic structure, the invention according to claim 10 is configured such that an average height of a large number of the convex portions constituting the periodic structure is equal to or greater than the average optical wavelength.
In the invention of claim 10 configured as described above, by setting the average height of the plurality of convex portions constituting the periodic structure to be equal to or greater than the average optical wavelength, at least the same convexity than the formation period of the convex portions. The height of the part can be increased. Thus, by forming the convex part high, even in the light incident so as to be substantially orthogonal to the height direction of the convex part, the layer having an average refractive index of the plural layers is used. Light behavior can be realized.

Furthermore, as a preferred example of the periodic structure, in the invention according to claim 11, the standard deviation of the period in which the plurality of convex portions are formed is 20% or less of the average period.
In the invention of claim 11 configured as described above, by setting the standard deviation of the period in which the plurality of convex portions are formed to 20% or less of the average period, the period may exceed the average optical wavelength. And the light extraction efficiency can be stably improved.

Similarly, as a preferred example of the periodic structure, in the invention according to claim 12, the height standard deviation of the plurality of convex portions is 20% or less of the average height.
In the invention of claim 12 configured as described above, by setting the height standard deviation of the plurality of convex portions to 20% or less of the average height, there is a possibility that the height is lower than the average optical wavelength. The light extraction efficiency can be stably improved.

Furthermore, as an example of the location where the periodic structure is formed, in the invention described in claim 13, the periodic structure is configured to be formed on a surface of the substrate opposite to the side where the light emitting portion is laminated. .
In the invention of claim 13 configured as described above, the periodic structure is formed on the surface of the substrate opposite to the side where the light emitting section is laminated. Thereby, it is possible to alleviate a rapid change in the refractive index at the interface between the surface of the substrate opposite to the side where the light emitting part is laminated and the other layer. For example, when the surface of the substrate opposite to the side where the light emitting unit is laminated is formed so as to be in contact with an external air layer, adverse effects due to the difference in refractive index between the air layer and the substrate are suppressed. And good light extraction efficiency can be realized.

Further, as an example of a place where the periodic structure is formed, in the invention described in claim 14, a Group 3 nitride semiconductor layer is stacked between the substrate and the light emitting unit,
The periodic structure is configured to be formed at the interface between the substrate and the group 3 nitride semiconductor layer.
In the invention of claim 14 configured as described above, the periodic structure may be formed at an interface between the group III nitride semiconductor layer formed between the substrate and the light emitting portion and the substrate. Good. Since the group III nitride semiconductor layer and the substrate have different refractive indexes, the effects of the present invention can be exhibited.

Furthermore, as an example of a location where the periodic structure is formed, in the invention described in claim 15, the periodic structure is formed in the p-type semiconductor layer.
In the invention of claim 15 configured as described above, the periodic structure may be formed in the p-type semiconductor layer. Since the p-type semiconductor layer is in contact with any layer having a different refractive index, the light extraction efficiency can be improved by forming the periodic structure.

Furthermore, as an example of the location where the periodic structure is formed, in the invention described in claim 16, a sealing portion that covers a part or the whole of the semiconductor light emitting element is formed,
The periodic structure is configured to be formed on the surface of the sealing portion.
In the invention of claim 16 configured as described above, the periodic structure may be formed on the surface of the sealing portion covering a part or the whole of the semiconductor light emitting element. By doing in this way, the bad influence by the difference in refractive index of the said sealing part and the layer which contact | connects the said sealing part and an interface can be relieved.

Furthermore, as an example of the specific shape of the convex portion constituting the periodic structure, in the invention described in claim 17, the convex portion is configured to be formed in a cone shape.
In the invention of claim 17 configured as described above, the shape of the convex portion may be formed in a cone shape. By forming the convex portion in a cone shape, the effective refractive index in the periodic structure can be gradually changed.

Furthermore, as an example of a specific aspect of the periodic structure, the invention described in claim 18 is configured such that a highly reflective metal layer is formed in contact with the periodic structure and an interface.
That is, a highly reflective metal layer is formed so as to contact the periodic structure and the interface. According to the highly reflective metal layer, a high reflectance can be realized. Even in this case, the above-described periodic structure can alleviate a rapid change in reflectance, and a high reflectance can be realized.

Furthermore, as a specific example of the highly reflective metal layer, in the invention described in claim 19, the highly reflective metal layer constitutes an electrode.
In the invention of claim 19 configured as described above, an electrode can be used as the highly reflective metal layer.

As described above, according to the first aspect of the present invention, it is possible to provide a method for manufacturing a semiconductor light emitting device with extremely high light extraction efficiency.
According to the second aspect of the present invention, a semiconductor light emitting device with extremely high light extraction efficiency can be manufactured at low cost.
According to the third aspect of the invention, a semiconductor light emitting device having a high reflectance can be manufactured by the highly reflective metal layer having a periodic structure.
According to the invention of claim 4, the periodic mask can be manufactured at low cost.
According to the invention of claim 5, the periodic mask can be easily manufactured.

According to the invention of claim 6, the covering material can be formed of metal.
According to the invention of claim 7, the covering material can be formed of Au.
According to the eighth aspect of the present invention, it is possible to provide a semiconductor light emitting device with extremely high light extraction efficiency.
According to the invention of claim 9, it is possible to provide a semiconductor light emitting device with extremely high light extraction efficiency.
According to the invention of claim 10, the light extraction efficiency can be further improved.

According to the invention of claim 11, the light extraction efficiency can be stabilized.
According to the twelfth aspect of the present invention, the light extraction efficiency can be stabilized.
According to the invention of claim 13, light can be efficiently extracted from the substrate.
According to the fourteenth aspect of the present invention, it is possible to prevent light from being lost at the interface between the substrate and the group 3 nitride semiconductor layer.
According to the fifteenth aspect of the present invention, it is possible to prevent light from being lost at the interface of the p-type semiconductor layer.

According to the sixteenth aspect of the present invention, it is possible to prevent light from being lost at the interface between the sealing portion and the outside.
According to the seventeenth aspect of the present invention, a rapid change in refractive index can be suppressed.
According to the eighteenth aspect of the present invention, a high reflectance can be realized with a periodic structure.
According to the nineteenth aspect of the present invention, the manufacturing cost can be reduced.

Here, embodiments of the present invention will be described in the following order.
(1) First embodiment:
(2) Second embodiment:
(3) Third embodiment:
(4) Fourth embodiment:
(5) Fifth embodiment:
(6) Sixth embodiment:
(7) Summary:

(1) First embodiment:
FIG. 1 conceptually shows the structure of a group III nitride semiconductor light-emitting device according to the first embodiment of the present invention. In the figure, a semiconductor light emitting device 10 includes a substrate 11, a low temperature deposition buffer layer 12, a cladding layer 13, a light emitting layer 14, a barrier layer 15, a contact layer 16, a p-electrode 17, and an n− each formed in a substantially plate shape. The electrode 18 is constituted. In the figure, a plate-like substrate 11 constituting the lowermost layer is made of SiC, and a low-temperature deposition buffer layer 12 made of AlGaN (Group III nitride semiconductor) on the front side surface and n-GaN. The clad layer 13, the light emitting layer 14 made of GaInN, the barrier layer 15 made of p-AlGaN, and the contact layer 16 made of p-GaN are sequentially stacked. . Further, a plate-like p-electrode 17 is laminated on the uppermost contact layer 16, and an n-electrode 18 is laminated on the cladding layer 13. Periodic irregularities are formed on the back side of the substrate 11. Note that the light emitting section referred to in the present invention is formed from the clad layer 13 made of n-GaN to the contact layer 16 made of p-GaN.

  FIG. 2 shows the back side of the substrate 11 (the surface opposite to the surface on which the light emitting portions are stacked) as viewed obliquely. In the figure, a large number of substantially conical convex portions 11a, 11a, 11a,... Protrude downward from the back side of the substrate 11, so that the back surface of the substrate 11 has an undulating shape. The convex portions 11a, 11a, 11a,... Are periodically distributed in the two-dimensional direction on the back surface of the substrate 11, and the convex portions 11a, 11a, 11a,. The average height of the convex portions 11a, 11a, 11a,... Is about 300 nm, and the standard deviation is about 20 nm. It is assumed that the height of the convex portions 11a, 11a, 11a,... Is the difference between the apex, the height, and the skirt height of the convex portions 11a, 11a, 11a,. The average of the formation period of the convex portions 11a, 11a, 11a... Is about 200 nm, and the standard deviation of the formation period is about 15 nm. In addition, let the space | interval of the vertex of adjacent convex part 11a, 11a, 11a ... be a formation period of convex part 11a, 11a, 11a ..., or the average period of periodic structure A1.

  In this configuration, the light emitting layer 14 can emit light by applying a voltage in the forward bias direction between the p-electrode 17 and the n-electrode 18 of the semiconductor light emitting device 10. In the light emitting layer 14, light having a wavelength corresponding to the band gap is emitted. In the light emitting unit of this embodiment, the average optical wavelength is about 220 nm. The optical wavelength means a value obtained by dividing the actual wavelength by the refractive index. The wavelength of the light emitted from the light emitting layer 14 is distributed in a wavelength band with a width of several tens of nm, and the average value is about 220 nm. The substrate 11, the low temperature deposition buffer layer 12, the cladding layer 13, the barrier layer 15, and the contact layer 16 each have a light transmitting property, and light emitted from the light emitting layer 14 can be extracted from the back side of the substrate 11. It is possible. That is, the back surface of the substrate 11 constitutes a light extraction surface of the semiconductor light emitting element 10, and the light extracted from the extraction surface can be used for illumination or the like.

  The light emitted from the light emitting layer 14 passes through the periodic structure A1 formed on the back surface of the substrate 11 and is emitted into the air outside the semiconductor light emitting element 10. Since the refractive index of light is different between the air outside the semiconductor light emitting element 10 and the SiC constituting the substrate 11, the interface between the periodic structure A1 and the air forms a reflecting surface. Therefore, the light incident on the interface between the periodic structure A1 and air at an incident angle exceeding the critical angle may be reflected at the interface and confined within the semiconductor light emitting device 10. However, in the present invention, since the average period (about 200 nm) of the periodic structure A1 is smaller than the optical wavelength of the emitted light (about 220 nm), most of the light reaching the periodic structure A1 is between the air and the substrate 11. You will feel the refractive index.

  It can be considered that the refractive index in the periodic structure A1 changes according to the area ratio of the air layer distributed on the slice surface when the periodic structure A1 is sliced in a direction parallel to the back surface of the substrate 11. Actually, the air and the SiC of the substrate 11 are unevenly distributed on the slice plane, but since this bias exists with a period shorter than the average optical wavelength, most of the light is an average depending on the area ratio. A refraction index is felt. Since the occupied area ratio of the air layer is small on the slice surface near the skirt of the periodic structure A1, the refractive index of the substrate 11 contributes greatly at the height near the skirt of the periodic structure A1. On the other hand, since the occupied area ratio of the air layer is large in the slice surface near the apex of the periodic structure A1, the contribution of the refractive index of air becomes large at the apex height of the periodic structure A1. That is, as the light travels deeper in the height direction of the periodic structure A1, the periodic structure A1 has a refractive index (effective refractive index) that gradually converges from the refractive index of the substrate 11 to the refractive index of air. Can be considered.

  The transition of the refractive index according to the height of the periodic structure A1 depends on the shape of the convex portions 11a, 11a, 11a..., For example, the slope of the convex portions 11a, 11a, 11a. Is linear, it can be considered that the refractive index fluctuates in a continuous parabolic shape. Therefore, a sudden change in refractive index in the periodic structure A1 that constitutes the interface between the substrate 11 and air can be prevented, and light can be prevented from being reflected in the periodic structure A1. However, the shape of the convex portions 11a, 11a, 11a,... Is not limited to a conical shape, and the effects of the present invention can be exhibited even with other shapes. That is, the shape may be a shape whose cross-sectional area gradually changes according to the height. For example, a triangular pyramid shape, a quadrangular pyramid shape, a hemispherical shape, or a trapezoidal shape protrusion may be provided.

  In the present embodiment, the height (about 400 nm) of the periodic structure A1 is larger than the average optical wavelength (about 220 nm) of light and the average period (about 200 nm), so that the convex portions 11a, 11a, 11a,. The angle at which the inclined surface intersects the substrate 11 can be a relatively high angle (close to 90 degrees). Therefore, by forming the periodic structure A1 high, it is possible to prevent a sudden change in refractive index from being sensed even for light incident at a shallow angle with respect to the surface on which the periodic structure A1 is formed. . In addition, by forming the periodic structure A1 high, the variation of the area ratio according to the height of the periodic structure A1 becomes gradual, and the gradient in which the refractive index varies linearly can be reduced. That is, a rapid change in refractive index can be further suppressed, and high antireflection properties can be realized.

  FIG. 3 shows the effect of the present invention with a histogram. In the figure, the horizontal axis indicates the ratio of the light output of the product of the present invention formed as shown in FIG. 1 to the light output of the conventional product formed as shown in FIG. 13, and the number of samples corresponding to the ratio of each light output is shown vertically. Shown on the axis. The light output of 30 products of the present invention was investigated. As a result, it was found that the sample to which the present invention is applied can obtain a light output of 3.4 to 4.6 times (mode value 3.8 times) compared to the conventional product. It was also found that most of the electric energy input to the semiconductor light emitting element 10 was extracted as light energy without losing it.

  As described above, the effect of the present invention is exhibited when the average period of the periodic structure A1 is smaller than the average optical wavelength of light. However, the standard deviation of the formation period of the convex portions 11a, 11a, 11a,. By making it within 20% (more preferably within 10%) of the average period of the periodic structure A1, the effect of the present invention can be surely exhibited. Further, it is desirable that the standard deviation of the formation period of the convex portions 11a, 11a, 11a,... Is small, but the convex portions 11a, 11a, 11a,. There is no. However, it is desirable that the convex portions 11a, 11a, 11a,... Be distributed in a two-dimensional direction on the back surface of the substrate 11 so as not to cause anisotropy. Of course, anisotropy occurs in the effect, but the periodic structure A1 may be formed in a stripe shape. Further, it is desirable that the convex portions 11a, 11a, 11a,... Height variations are within 20% (more preferably within 10%) of the average.

  FIG. 4 is a graph showing the transmittance at the interface between the substrate 11 and air. In the figure, the vertical axis indicates the light transmittance, and the horizontal axis indicates the average period of the periodic structure A1. Note that the average period of the periodic structure A1 on the horizontal axis is expressed as a multiple of the average optical wavelength (about 220 nm) of the emitted light. In the figure, it can be seen that the transmittance is improved in a region where the average period of the periodic structure A1 is about 500 nm or less, which is three times the average optical wavelength (about 220 nm). In particular, in the region where the average period of the periodic structure A1 is not more than twice the average optical wavelength, good light extraction efficiency can be realized as the semiconductor light emitting device 10. Moreover, if the average period of the periodic structure A1 is equal to or less than the average optical wavelength as in this embodiment, a light transmittance close to 100% can be realized. That is, the smaller the average period of the periodic structure A1, the better.

  The light emitted from the light emitting layer 14 has an average optical wavelength of about 220 nm, but has a wavelength bandwidth of several tens of nm. Therefore, the smaller the average period of the periodic structure A1, the shorter the period of the emitted light. The ratio of those having an optical wavelength smaller than the period of the structure A1 is increased. Accordingly, the light transmittance is gradually improved from a region where the average period of the periodic structure A1 is 2 to 3 times the average optical wavelength of the emitted light, and the average period of the light having the average period of the periodic structure A1 is emitted. In the region below the optical wavelength, it can reach nearly 100%.

  Next, a method for manufacturing the semiconductor light emitting element 10 will be described. First, a substantially plate-like substrate 11 is prepared. At this time, the periodic structure A1 is not formed on the back side of the substrate 11. A low temperature deposition buffer layer 12 having a predetermined thickness is formed by uniformly growing AlGaN on the front side of the substrate 11 using a metal organic chemical vapor deposition method. Similarly, a clad layer 13 is formed on the low temperature deposition buffer layer 12, and a light emitting layer 14 is further formed on the clad layer 13. Further, the barrier layer 15 is formed on the light emitting layer 14, and p-GaN is grown on the barrier layer 15, thereby forming the contact layer 16.

  After the layers are laminated as described above, the coating layer 20 is formed by uniformly depositing Au as a coating material on the back side of the substrate 11 as shown in FIG. 5 (deposition step). In depositing Au, various deposition techniques can be applied. For example, you may utilize the EB vapor deposition apparatus etc. which vapor-deposit by heat-evaporating Au by evacuation. Furthermore, it is sufficient that Au can be uniformly distributed on the back side of the substrate 11 to some extent. For example, Au may be attached by a wet method. In the present embodiment, vapor deposition is performed so that the film thickness of the coating layer 20 is about 50 mm.

  After forming the coating layer 20, the semiconductor light emitting element 10 is heated by an oven or the like (kinetic energy application step). At that time, the coating layer 20 formed on the back side of the substrate 11 is uniformly heated to, for example, about 180 ° C. over the entire surface. By doing in this way, kinetic energy can be given to each Au atom which comprises the coating layer 20, and Au atom can be aggregated on the back side surface of the board | substrate 11 by it. Then, by cooling the semiconductor light emitting element 10, a large number of Au particles 30, 30, 30... Can be distributed on the back side surface of the substrate 11 as shown in FIG. As described above, the coating layer 20 is formed to have a uniform film thickness, and the kinetic energy is uniformly applied over the entire surface. Therefore, the aggregation energy of Au atoms can be considered to be uniform over the entire back side of the substrate 11. it can. Therefore, as shown in FIG. 6, the Au particles 30, 30, 30... Can be distributed uniformly on the back side surface of the substrate 11.

  The distribution period of the Au particles 30, 30, 30,... Can be controlled by the heating temperature, the film thickness of the coating layer 20, and the like. In this embodiment, by heating the coating layer 20 having a film thickness of about 50 mm at about 180 ° C., the Au particles 30, 30, 30... Can be distributed so that the average period is about 200 nm. . For example, when it is desired to increase the distribution period of the Au particles 30, 30, 30..., The heating temperature may be increased or the film thickness of the coating layer 20 may be increased. Conversely, when it is desired to reduce the distribution period of the Au particles 30, 30, 30..., The heating temperature may be lowered or the film thickness of the coating layer 20 may be reduced. Moreover, the kinetic energy should just be provided to the extent that the coating layer 20 can be aggregated, and the periodic Au particles 30, 30, 30... May be formed by a method other than heating. For example, kinetic energy can be imparted to the coating layer by ion irradiation or electron beam irradiation. Since the Au grains 30, 30, 30... Have a periodic pattern in which the average period is equal to or less than the average optical wavelength, the Au grains 30, 30, 30. Configure (mask forming step).

After forming the Au particles 30, 30, 30,... Periodically distributed on the back side surface of the substrate 11 as described above, the back side of the substrate 11 is etched by a reactive ion etching apparatus (etching process). In the present embodiment, CF ₄ gas is used as the etching medium. Of course, other etching gases may be used, or etching may be performed using an etching solution. Since etching resistance of Au to CF ₄ gas is higher than etching resistance of SiC to CF ₄ gas, SiC can be selectively etched. The etching direction is perpendicular to the back surface of the substrate 11, and only the portion where the Au particles 30, 30, 30.

  That is, etching can be performed using a periodic mask composed of a large number of Au particles 30, 30, 30,... As an etching resist. Thereby, periodic structure A1 as shown in FIG. 8 can be formed (periodic structure formation process). In general, when the etching rate is increased, the etching proceeds perpendicularly to the back surface of the substrate 11, so that the inclination angles of the slopes of the convex portions 11a, 11a, 11a,. Get closer. On the other hand, under the condition that the etching rate is slow, side etching proceeds, and the inclination angle of the slopes of the convex portions 11a, 11a, 11a... With respect to the back surface of the substrate 11 becomes an acute angle.

  By performing etching using the periodic mask in this way, the shape of the periodic structure A1 can be controlled to a desired shape. Moreover, as long as it does not etch excessively, the height of the vertex of convex part 11a, 11a, 11a ... can be arrange | equalized. Therefore, the height variation of the convex portions 11a, 11a, 11a,. However, the amount of side etching may be increased intentionally, and the Au particles 30 may be removed like the third convex portion 11a from the left in FIG. Further, etching conditions may be set so that the Au particles 30 disappear by etching. In the present embodiment, even if the Au particles 30, 30, 30... Remain inside the semiconductor light emitting element 10, the performance of the semiconductor light emitting element 10 is not greatly deteriorated. However, depending on the material of the covering material, the performance may be deteriorated. In this case, it is desirable to remove the periodic mask.

The material of the periodic mask is not limited to Au as long as the etching resistance to the etching medium is higher than that of the substrate. Specifically, the etching selectivity between the periodic mask and the substrate may be 0.1 or more, and more preferably 1 or more. For example, as a material of the periodic mask effective for CF ₄ gas, Ga, In, Al, Cu, Ag, Ni, Pt, Pd, SiN, SiO _{2, an} insulator, or the like can be given. Of course, since an appropriate periodic mask material is selected according to the etching medium, it goes without saying that a periodic mask material other than the above can be applied. However, in the process of forming the periodic mask as in the present embodiment, when using atomic or molecular aggregation, it is necessary to select an aggregating coating material such as Au.

  In this embodiment, the periodic mask is formed by utilizing the aggregation of the coating layer. However, the periodic mask may be formed by another method. For example, a periodic mask pattern may be formed by using a stepper using an excimer laser, or a periodic mask pattern may be formed by performing electron beam exposure or the like or two-speed interference exposure on a photosensitive mask material. A mask pattern may be formed.

  After forming the periodic structure A1 as described above, the n-electrode 17 and the n-electrode 18 are formed, and the semiconductor light emitting device 10 is packaged. Note that the clad layer 13 on which the n-electrode 18 is formed may be exposed by selectively etching the light emitting layer 14, the barrier layer 15, and the contact layer 16 that are uniformly stacked, or the light emitting layer may be selectively formed in advance. 14, the barrier layer 15, and the contact layer 16 may be grown to expose the cladding layer 13 on which the n− electrode 18 is formed. Alternatively, the periodic structure A1 may be formed after the n-electrode 17 and the n-electrode 18 are formed in advance.

Further, the periodic structure A1 may be formed in advance on the back side of the substrate 11 and then each layer may be formed on the front side of the substrate 11. Moreover, the board | substrate 11 should just have translucency, and you may make it form a board | substrate with materials other than SiC. For example, a sapphire substrate, a GaN substrate, a Ga ₂ O ₃ substrate, a GaN substrate, or the like can be applied. Needless to say, the present invention is applicable to other types of semiconductor light emitting devices such as AlGaInP and AlGaAs. In addition, although the average optical wavelength of the light emitted changes with kinds of light emitting layer, forming periodic structure A1 which has a period of 2 times or less of each average optical wavelength (an average optical wavelength or less is preferable). Therefore, a high light extraction efficiency can be realized.

(2) Second embodiment:
FIG. 8 conceptually shows the structure of the group III nitride semiconductor light emitting device according to the second embodiment of the present invention. In the figure, a semiconductor light emitting device 110 includes a substrate 111, a low temperature deposition buffer layer 112, a cladding layer 113, a light emitting layer 114, a barrier layer 115, a contact layer 116, a p-electrode 117, and an n−, each formed in a substantially plate shape. And electrode 118. A plate-like substrate 111 constituting the lowermost layer is made of SiC, and a low temperature deposition buffer layer 112 made of AlGaN, a clad layer 113 made of n-GaN, and GaInN on the surface on the front side. The light emitting layer 114 is configured, a barrier layer 115 composed of p-AlGaN, and a contact layer 116 composed of p-GaN are sequentially stacked. Further, a periodic structure A2 composed of Au grains 130, 130, 130... Periodically arranged on the uppermost contact layer 116 is provided, and on the contact layer 116 on which the periodic structure A2 is formed. A p-electrode 117 is stacked as a highly reflective metal layer made of Cu. The back side of the substrate 111 is a flat surface, and an n-electrode 118 is laminated.

  According to this configuration, the light emitting layer 114 can emit light by applying a voltage to the semiconductor light emitting element 110 in the forward bias direction. In the light emitting layer 114, light corresponding to the band gap is emitted, and the average optical wavelength is about 220 nm. The substrate 111, the low-temperature deposition buffer layer 112, the cladding layer 113, the barrier layer 115, and the contact layer 116 each have a light-transmitting property, and light emitted from the light-emitting layer 114 can be extracted from the back side of the substrate 111. It is possible. That is, the back side of the substrate 111 constitutes a light extraction surface of the semiconductor light emitting device 110, and the light extracted from the extraction surface can be used for illumination or the like.

  On the other hand, since the upper surface of the contact layer 116 is covered with the p-electrode 117 made of Cu having a high reflectance, the emitted light is reflected to prevent leakage from the p-electrode 117 side. Yes. The reflected light is extracted from the light extraction surface and can be used for illumination or the like. Since the diffuse reflection can be promoted by forming the periodic structure A2, the reflectance at the interface between the contact layer 116 and the p-electrode 117 can be further improved. Therefore, the amount of light extracted from the light extraction surface in the semiconductor light emitting device 110 can be increased, and the light extraction efficiency can be improved to about 1.3 times the normal efficiency.

  Next, a method for manufacturing the semiconductor light emitting device 110 will be described. First, a substantially plate-like substrate 111 is prepared. A low temperature deposition buffer layer 112 having a predetermined thickness is formed by uniformly growing AlGaN on the front side of the substrate 111 using a metal organic compound vapor deposition method. Similarly, a cladding layer 113 is formed on the low temperature deposition buffer layer 112, a light emitting layer 114 is further formed on the cladding layer 113, and a barrier layer 115 is further formed on the light emitting layer 114. Then, the contact layer 116 is formed by growing p-GaN on the barrier layer 115.

  After the layers are stacked as described above, Au as a coating material is uniformly deposited on the surface of the contact layer 116 to form a coating layer similar to that shown in FIG. In depositing Au, various deposition techniques can be applied. For example, you may utilize the EB vapor deposition apparatus etc. which vapor-deposit by heat-evaporating Au by evacuation. Further, it is only necessary that Au can be uniformly distributed on the back side of the substrate 111. For example, Au may be attached by a wet method. In this embodiment, vapor deposition is performed so that the coating layer has a thickness of about 50 mm.

  After forming the coating layer, the semiconductor light emitting device 110 is heated by an oven or the like. At that time, the coating layer formed on the surface of the contact layer 116 is heated to about 180 ° C., for example. In this way, kinetic energy can be imparted to each Au atom constituting the coating layer, and the Au atoms can be aggregated on the surface of the contact layer 116. Then, by cooling the semiconductor light emitting device 110, a large number of Au particles 130, 130, 130... Can be distributed on the surface of the contact layer 116. As described above, the coating layer is formed to have a uniform film thickness, and the aggregation energy of Au atoms that aggregate when heated can be considered to be uniform on the surface of the contact layer 116. Therefore, as in FIG. .. Can be distributed on the surface of the contact layer 116 in a uniform period.

  After the Au particles 130, 130, 130... That are periodically distributed on the surface of the contact layer 116 are formed as described above, on the contact layer 116 and the Au particles 130, 130, 130. Cu is vapor-deposited (highly reflective metal layer forming step). Here, an EB vapor deposition apparatus or the like can be used for vapor deposition of Cu, or Cu may be adhered to the surface of the contact layer 116 by a method other than vapor deposition. In the initial stage of vapor deposition, the surface of the contact layer 116 is uneven by the Au particles 130, 130, 130..., But the gap between the Au particles 130, 130, 130. Is filled with Cu, finally a flat surface is formed, and a p-electrode 117 is formed. That is, a highly reflective metal layer in contact with the periodic structure composed of Au grains 130, 130, 130... Is formed as the p-electrode 117.

The substrate in the present embodiment only needs to have translucency, and the substrate may be formed of a material other than SiC. For example, a sapphire substrate, a GaN substrate, a Ga ₂ O ₃ substrate, a GaN substrate, or the like can be applied. Needless to say, the present invention is applicable to other types of semiconductor light emitting devices such as AlGaInP and AlGaAs. In addition, although the average optical wavelength of the emitted light differs depending on the type of the light emitting layer, a high light extraction efficiency can be realized by forming the periodic structure A2 having a period equal to or less than the respective average optical wavelength. No difference. Moreover, in this embodiment, although what used Cu as a raw material was illustrated as an example of a highly reflective metal layer, Rh, Ag, Al, Ni, Pt, Cu, an alloy containing these, etc. are used as a highly reflective metal layer. It may be formed. In addition, although the number of processes can be reduced by using the highly reflective metal layer as an electrode, the highly reflective metal layer and the electrode may be formed separately.

(3) Third embodiment:
FIG. 9 conceptually shows the structure of the group III nitride semiconductor light emitting device according to the third embodiment. In the figure, a semiconductor light emitting device 210 includes a substrate 211, a low temperature deposition buffer layer 212, a cladding layer 213, a light emitting layer 214, a barrier layer 215, a contact layer 216, a p-electrode 217, and an n−, each formed in a substantially plate shape. And an electrode 218. A plate-like substrate 211 constituting the lowermost layer is made of SiC, and a low temperature deposition buffer layer 212 made of AlGaN, a clad layer 213 made of n-GaN, and GaInN on the surface on the front side. The light emitting layer 214 is configured, a barrier layer 215 composed of p-AlGaN, and a contact layer 216 composed of p-GaN are sequentially stacked. Further, by projecting a number of convex portions upward from the uppermost contact layer 216, a periodic structure A3 (average period of about 200 nm, average height of 400 nm) is formed. A p-electrode 217 made of Cu is stacked on the periodic structure A3, and an n-electrode 218 is stacked on the back side of the substrate 211.

  With this configuration, the light emitting layer 214 can emit light by applying a voltage to the semiconductor light emitting element 210 in the forward bias direction. In the light emitting layer 214, light corresponding to the band gap is emitted, and the average optical wavelength is about 220 nm. The substrate 211, the low temperature deposition buffer layer 212, the cladding layer 213, the barrier layer 215, and the contact layer 216 each have a light-transmitting property, and light emitted from the light emitting layer 214 can be extracted from the back side of the substrate 211. It is possible. That is, the back side of the substrate 211 constitutes a light extraction surface of the semiconductor light emitting device 210, and the light extracted from the extraction surface can be used for illumination or the like.

  On the other hand, since the upper surface of the contact layer 216 is covered with the p-electrode 217 formed of Cu having high reflectivity, the light is prevented from leaking from the p-electrode 217 side by reflecting the emitted light. ing. The reflected light is extracted from the light extraction surface and can be used for illumination or the like. By forming the periodic structure A3, diffuse reflection can be promoted, so that the reflectance at the interface between the contact layer 216 and the p-electrode 217 can be further improved. Therefore, the amount of light finally extracted from the light extraction surface of the semiconductor light emitting device 210 can be increased, and the light extraction efficiency can be improved.

  Next, a method for manufacturing the semiconductor light emitting device 210 will be described. First, a substantially plate-like substrate 211 is prepared. A low temperature deposition buffer layer 212 having a predetermined thickness is formed by uniformly growing AlGaN on the front side of the substrate 211 using a metal organic chemical vapor deposition method. Similarly, a cladding layer 213 is formed on the low temperature deposition buffer layer 212, and a light emitting layer 214 and a barrier layer 215 are formed on the cladding layer 213. Then, the contact layer 216 is formed by growing p-GaN on the barrier layer 215.

  After laminating the layers as described above, the periodic structure A3 is formed on the surface of the contact layer 216. In forming the periodic structure A3, since the same technique as that of the first embodiment can be applied, the description thereof is omitted here. When the periodic structure A3 can be formed, Cu is further deposited on the surface of the contact layer 216. In the initial stage of vapor deposition, the surface of the contact layer 216 is uneven due to the periodic structure A3, but as the vapor deposition proceeds, the gaps in the periodic structure A3 are filled with Cu, and finally a flat surface is formed. Then, the p-electrode 217 is formed. As in the previous embodiment, the number of steps can be reduced by using Au grains as the periodic structure A2. On the other hand, the shape of the periodic structure A3 can be controlled by forming the periodic structure A3 using Au grains as a periodic mask as in the present embodiment.

(4) Fourth embodiment:
FIG. 10 conceptually shows the structure of the group III nitride semiconductor light emitting device according to the fourth embodiment. In the figure, a semiconductor light emitting device 310 includes a substrate 311, a low temperature deposition buffer layer 312, a cladding layer 313, a light emitting layer 314, a barrier layer 315, a contact layer 316, a p-electrode 317, and an n−, each formed in a substantially plate shape. And an electrode 318. A plate-like substrate 311 constituting the lowermost layer is made of SiC, and a low temperature deposition buffer layer 312 made of AlGaN, a clad layer 313 made of n-GaN, and GaInN on the front side surface thereof. The light emitting layer 314 is formed, a barrier layer 315 made of p-AlGaN, and a contact layer 316 made of p-GaN are sequentially stacked. Further, a p-electrode 317 is stacked on the uppermost contact layer 316, and an n-electrode 318 is stacked on the back side of the substrate 311.

  A periodic structure A4 that undulates periodically is formed on the front side of the substrate 311. A low temperature deposition buffer layer 312 and a cladding layer 313 are formed so as to follow the periodic structures 311a, 311a, 311a. On the other hand, the front side of the cladding layer 313 is flattened, and all layers above the cladding layer 313 are formed flat.

  Thus, by forming the periodic structure A4 that periodically undulates on the front side of the substrate 311, the reflectance at the interface between the substrate 311 and the low temperature deposition buffer layer 312 can be reduced. This is because the refractive index of the substrate 311 and the refractive index of the low-temperature deposition buffer layer 312 are different, but a rapid change in the refractive index can be suppressed by the periodic structure A4. Further, if a thin layer such as the low temperature deposition buffer layer 312 is formed, the irregular shape of the periodic structure A4 is maintained. Therefore, the interface between the low temperature deposition buffer layer 312 and the cladding layer 313 laminated thereon Can be undulated periodically. Therefore, the reflectance at the interface between the low temperature deposition buffer layer 312 and the cladding layer 313 can also be reduced.

  In this way, the light extraction efficiency can be further improved by forming the periodic structure at the plurality of sets of interfaces. Further, by forming a thin film layer (low-temperature deposition buffer layer 312) having a thickness that does not flatten the periodic structure A4 on the periodic structure A4, the surface of the thin film layer (low-temperature deposition buffer layer 312) is maintained in an uneven shape. be able to. Therefore, by laminating the upper layer (cladding layer 313) on the surface of the thin film layer (low temperature deposition buffer layer 312), a periodic structure is formed at the interface between the thin film layer (low temperature deposition buffer layer 312) and the upper layer (cladding layer 313). Can be formed. That is, since it is not necessary to perform the step of forming the periodic structure individually at each interface, a semiconductor light emitting device having high light extraction efficiency can be manufactured at a low manufacturing cost.

  Next, a method for manufacturing the semiconductor light emitting device 310 will be described. First, a substantially plate-like substrate 311 is prepared. Then, the periodic structure A4 is formed on the front side of the substrate 311. In forming the periodic structure A4, since the same method as the method of forming the periodic structure A1 on the back side of the substrate 11 in the first embodiment can be applied, the description is omitted here. After forming the periodic structure A4, the low temperature deposition buffer layer 312 having a shape following the periodic structure A4 is formed by uniformly growing AlGaN on the front side of the substrate 311 using an organic metal compound vapor phase growth method.

  Then, the clad layer 313 is formed by growing n-GaN on the front side of the low temperature deposition buffer layer 312 by using an organic metal compound vapor phase growth method. When the cladding layer 313 is formed to some extent, the concave portion of the periodic structure A4 is filled with n-GaN, and finally a flat surface is formed. When the flat surface of the cladding layer 313 is formed, the light emitting layer 314 is formed on the cladding layer 313, and the barrier layer 315 is grown on the light emitting layer 314. Then, the contact layer 316 is formed by growing p-GaN on the barrier layer 315. Further, a p-electrode 317 is stacked on the uppermost contact layer 316, and an n-electrode 318 is stacked on the back side of the substrate 311.

(5) Fifth embodiment:
FIG. 11 conceptually shows the structure of the group III nitride semiconductor light-emitting device according to the fifth embodiment. In the figure, a semiconductor light emitting device 410 includes a substrate 411, a low temperature deposition buffer layer 412, a cladding layer 413, a light emitting layer 414, a barrier layer 415, a contact layer 416, a p-electrode 417, and an n−, each formed in a substantially plate shape. And an electrode 418. A plate-like substrate 411 constituting the lowermost layer is made of SiC, and a low temperature deposition buffer layer 412 made of AlGaN, a clad layer 413 made of n-GaN, and GaInN on the surface on the front side. The light emitting layer 414 is formed, a barrier layer 415 made of p-AlGaN, and a contact layer 416 made of p-GaN are sequentially stacked. Further, a p-electrode 417 is stacked on the contact layer 416, and an n-electrode 318 is stacked on the back side of the substrate 411. Note that the p-electrode 417 is semitransparently formed of mesh Ni / Au or the like, and can transmit light. Further, the p-electrode 417 only needs to transmit light to some extent, and a transparent electrode such as Ga ₂ O ₃ , ZnO, or ITO may be used.

  The substrate 411, the low temperature deposition buffer layer 412, the cladding layer 413, the light emitting layer 414, the barrier layer 415, the contact layer 416, and the n-electrode 418 are laminated in a flat plate shape. A periodic structure A5 that undulates periodically is formed on the surface of the contact layer 416, and a p-electrode 417 follows and is stacked on the periodic structure A5. The surface of the p-electrode 417 has a shape in which the unevenness of the periodic structure A5 is maintained.

  Thus, by forming the periodic structure A5 that periodically undulates on the front side of the contact layer 416, the reflectance at the interface between the contact layer 416 and the p-electrode 417 can be reduced. This is because the refractive index of the contact layer 416 and the refractive index of the p-electrode 417 are different, but a rapid change in the refractive index can be suppressed by the periodic structure A5. Further, if a thin layer such as the p-electrode 417 is formed, the uneven shape of the periodic structure A5 is maintained, so that the interface between the p-electrode 417 and air can be undulated periodically. Therefore, the reflectance at the interface between the p-electrode 417 and air can also be reduced.

  Next, a method for manufacturing the semiconductor light emitting element 410 will be described. First, a substantially plate-like substrate 411 is prepared. Then, AlGaN is uniformly grown on the front side of the substrate 411 by using an organic metal compound vapor phase growth method to form a low temperature deposition buffer layer 412. A clad layer 413 is formed by growing n-GaN on the front side of the low temperature deposition buffer layer 412 using an organic metal compound vapor phase growth method. Further, a light emitting layer 414 is formed on the cladding layer 413, and a barrier layer 415 is grown on the light emitting layer 414. Then, the contact layer 416 is formed by growing p-GaN on the barrier layer 415.

  A periodic structure A5 that periodically undulates is formed on the contact layer 416. In forming the periodic structure A5, since the same method as the method of forming the periodic structure A1 on the back side of the substrate 11 in the first embodiment can be applied, the description is omitted here. After forming the periodic structure A5, the p-electrode 417 is laminated on the periodic structure A5 by coating or vapor deposition. On the other hand, an n-electrode 418 is stacked on the back side of the substrate 411.

(6) Sixth embodiment:
FIG. 12 conceptually shows the structure of the group III nitride semiconductor light-emitting device according to the sixth embodiment. In the figure, a substantially hemispherical dome-shaped sealing portion 60 is formed, and the semiconductor light emitting device 10 of the first embodiment is embedded in the sealing portion 60 with the light extraction surface oriented above the paper surface. ing. The sealing portion 60 is made of a synthetic resin such as a transparent epoxy resin, and can transmit light extracted from the semiconductor light emitting element 10 to the outside. A periodic structure A6 that periodically undulates the surface of the sealing portion 60 is formed. In forming the periodic structure A6, a method similar to the method of forming the periodic structure A1 on the back side of the substrate 11 in the first embodiment can be applied, and thus the description thereof is omitted here.

  Thus, by forming the periodic structure A6 that periodically undulates on the surface of the sealing portion 60, the reflectance at the interface between the sealing portion 60 and the outside air can be reduced. This is because, although the refractive index of the air of the sealing portion 60 is different, a sudden change in the refractive index can be suppressed by the periodic structure A6. There are various modes of sealing the semiconductor light emitting element 10 with the sealing portion 60, and only the light extraction surface may be sealed with the sealing portion 60. Also in this case, by forming the periodic structure A6 on the surface of the sealing portion 60, the light extraction efficiency to the outside of the sealing portion 60 can be improved.

(7) Summary:
As described above, according to the present invention, the periodic structure A1 formed on the light extraction surface of the semiconductor light emitting element 10 is formed on the light extraction surface of the semiconductor light emitting device 10 by forming the periodic structure A1 formed with a period of twice or less the average optical wavelength of light. The difference in refractive index can be reduced. Therefore, reflection on the light extraction surface can be prevented, and high light extraction efficiency can be realized. Furthermore, since the fine periodic mask can be formed by heating the Au thin film, the periodic structure A1 can be formed easily and inexpensively.

  Moreover, it is also possible to form a semiconductor light emitting element by appropriately combining the embodiments. For example, the semiconductor light emitting devices of the first to fifth embodiments may be sealed in the sealing portion 60 of the sixth embodiment. In addition, for example, it is possible to form a semiconductor light emitting element in which the configuration of the first embodiment and the configuration of the second or third embodiment are combined. According to such a configuration, it is possible to achieve a high reflectance on the light extraction surface and the opposite surface across the light emitting unit while realizing a high transmittance on the light extraction surface, so that the light extraction can be achieved. Efficiency can be improved synergistically.

1 is a conceptual diagram of a semiconductor light emitting device according to a first embodiment. It is a perspective view of the periodic structure concerning a first embodiment. It is a histogram which shows the output of the light of the semiconductor light-emitting device to which this invention is applied. It is a graph which shows the relationship between the transmittance | permeability of light, and an average period. It is process explanatory drawing of the periodic structure concerning 1st embodiment. It is process explanatory drawing of the periodic structure concerning 1st embodiment. It is process explanatory drawing of the periodic structure concerning 1st embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning 2nd embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning 3rd embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning 4th embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning 5th embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning 6th embodiment. It is a conceptual diagram of the semiconductor light-emitting device concerning a prior art example.

Explanation of symbols

1, 10, 110, 210, 310, 410 ... Semiconductor light emitting devices 2, 11, 111, 211, 311, 411 ... Substrate 3, 12, 112, 212, 312, 412 ... Low temperature deposition buffer layers 4, 13, 113, 213, 313, 413 ... cladding layers 5, 14, 114, 214, 314, 414 ... light emitting layers 6, 15, 115, 215, 315, 415 ... barrier layers 7, 16, 116, 216, 316, 416 ... contact layers 8, 17, 117, 217, 317, 417 ... p-electrodes 9, 18, 118, 218, 318, 418 ... n-electrode 11a ... convex portion 20 ... coating layer 30 ... Au particles (periodic mask)
60 ... Sealing portions A1 to A6 ... Periodic structure

Claims (19)

In a method for manufacturing a semiconductor light-emitting device, a semiconductor light-emitting device is formed by laminating a light-emitting portion composed of at least an n-type semiconductor layer and a p-type semiconductor layer on a substrate.
A mask forming step of forming a periodic mask having a periodic pattern in which the average period is equal to or less than twice the average optical wavelength of the light emitted from the light emitting unit;
And a periodic structure forming step of forming a periodic structure in which the average period is equal to or less than twice the average optical wavelength by using the same period mask. The periodic structure forming step includes
The method of manufacturing a semiconductor light emitting element according to claim 1, further comprising an etching step of performing etching using the periodic mask as an etching resist. The periodic structure forming step includes
2. The method of manufacturing a semiconductor light emitting device according to claim 1, further comprising a highly reflective metal layer forming step of depositing a highly reflective metal on the periodic mask. The mask forming step includes
A deposition step of forming a coating layer by depositing a coating material;
The method for manufacturing a semiconductor light emitting element according to claim 1, further comprising a kinetic energy applying step of applying kinetic energy to the coating layer. The kinetic energy application step
The method for manufacturing a semiconductor light-emitting element according to claim 4, wherein kinetic energy is imparted to the coating layer by heating the coating layer.   6. The method of manufacturing a semiconductor light-emitting element according to claim 4, wherein the covering material is a metal.   The method of manufacturing a semiconductor light emitting element according to claim 6, wherein the covering material is Au. In a semiconductor light emitting device in which a light emitting part composed of at least an n type semiconductor layer and a p type semiconductor layer is laminated on a substrate,
Forming a periodic mask having a periodic pattern in which the average period is equal to or less than twice the average optical wavelength of the light emitted from the light emitting unit;
A semiconductor light-emitting element, wherein a periodic structure having an average period of not more than twice the average optical wavelength is formed using the same period mask. In a semiconductor light emitting device in which a light emitting part composed of at least an n type semiconductor layer and a p type semiconductor layer is laminated on a substrate,
A periodic structure formed of a plurality of convex portions formed at an interface where a plurality of layers having different refractive indexes are in contact with each other, and formed with an average period not more than twice the average optical wavelength of light emitted from the light emitting portion. A semiconductor light emitting element comprising:   The semiconductor light emitting element according to claim 9, wherein an average height of the plurality of convex portions constituting the periodic structure is equal to or greater than the average optical wavelength.   11. The semiconductor light emitting element according to claim 9, wherein a standard deviation of a period in which the plurality of convex portions are formed is 20% or less of the average period.   The semiconductor light emitting element according to claim 9, wherein a height standard deviation of the plurality of convex portions is 20% or less of the average height.   13. The semiconductor light emitting element according to claim 9, wherein the periodic structure is formed on a surface of the substrate opposite to the side on which the light emitting part is laminated. A group 3 nitride semiconductor layer is laminated between the substrate and the light emitting unit,
The semiconductor light emitting element according to claim 9, wherein the periodic structure is formed at an interface between the substrate and the group 3 nitride semiconductor layer.   The semiconductor light-emitting element according to claim 9, wherein the periodic structure is formed in the p-type semiconductor layer. A sealing portion that covers a part or the whole of the semiconductor light emitting element is formed,
The semiconductor light-emitting element according to claim 9, wherein the periodic structure is formed on a surface of the sealing portion.   The semiconductor light emitting element according to claim 9, wherein the convex portion is formed in a cone shape.   The semiconductor light emitting device according to claim 9, wherein a highly reflective metal layer is formed in contact with the periodic structure and an interface.   19. The semiconductor light emitting element according to claim 18, wherein the highly reflective metal layer constitutes an electrode.

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