JP2003124510A - Semiconductor light emitting device and method of manufacturing semiconductor light emitting device - Google Patents

Abstract

(57) Abstract: In a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device in which an active layer is formed in a plane parallel to an inclined crystal plane by selective growth, an active layer formed on the inclined crystal plane is sandwiched. An object of the present invention is to provide a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device, which can prevent diffusion of impurities from a conductive type layer, prevent deterioration of an active layer, and have high luminous efficiency. In the active layer and the conductive type layer formed in the plane parallel to the inclined crystal plane by the growth, the impurity diffused from the conductive type layer to the active layer can be blocked by the undoped crystal layer formed close to the active layer. As a result, the conductivity type layer can be doped with a large number of impurities, so that the luminous efficiency can be increased. Further, it is possible to prevent a leak current generated at the interface between the active layer and the conductive type layer, and to avoid deterioration of the active layer.

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 a method for manufacturing the semiconductor light emitting device, and more particularly, to a semiconductor light emitting device using a nitride compound semiconductor and a method for manufacturing the semiconductor light emitting device with respect to a main surface of a substrate. A semiconductor light emitting device and a semiconductor light emitting device in which a first conductivity type layer, an active layer, and a second conductivity type layer extend in a plane parallel to a tilted crystal plane in a crystal layer having a tilted tilted crystal plane. The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor light emitting device using a nitride compound semiconductor, a low temperature buffer layer is formed on a sapphire substrate, and an n-side contact layer made of, for example, silicon-doped GaN is formed thereon. Ga of silicon dope
N-side cladding layer made of N, silicon-doped InGa
It is formed by laminating an active layer made of N, a p-side cladding layer made of magnesium-doped AlGaN, a p-side contact layer made of magnesium-doped GaN, and the like.

The semiconductor light emitting device having such a structure is commercialized and mass-produced as a blue and green light emitting diode including 450 nm to 530 nm, and is used in various applied devices such as a large display. In order to increase the light emission output of each semiconductor light emitting device and improve the brightness of the applied device, the concentration of impurities doped in the cladding layer of the semiconductor light emitting device is increased to improve the brightness of the applied device.

When crystal-growing a nitride semiconductor on a sapphire substrate, a sapphire substrate having a C-plane as a main surface is usually used. Since the nitride-based semiconductor layer is formed so as to extend in a plane parallel to the main surface of the substrate, the surface of the nitride-based semiconductor layer such as the active layer formed on the main surface of the substrate and the cladding layers that sandwich the active layer are also formed. It has a C surface.

When selectively grown on the C plane of a sapphire substrate, a crystal layer having a pointed shape surrounded by the (1-101) plane, that is, the S plane is formed (for example, Japanese Patent Publication No. 2830814). (See paragraph 0009 of the description of the issue),
It is assumed that the flat surface required for electrode formation has not been obtained,
There is no example in which it is positively used as an electronic device or a light emitting device, and it is merely used as an underlayer having a crystal structure from further selective growth.

[0006]

However, if the amount of impurities doped into the clad layer is increased too much in order to improve the light emission output of the semiconductor light emitting device, the impurities are likely to diffuse into the active layer, and the crystals of the active layer are apt to be diffused. It deteriorates the quality and deteriorates the active layer.

Further, in the case of a semiconductor light emitting device in which a crystal layer is formed by using selective growth to extend in a plane parallel to a tilted crystal plane, the cladding layer is formed in a crystal layer having a tilted crystal plane. As compared with the planar semiconductor light emitting device, the impurities are more likely to diffuse into the active layer.

Therefore, the present invention provides a semiconductor light emitting device in which an active layer is formed in a crystal layer having a tilted crystal plane by using selective growth so as to extend in a plane parallel to the tilted crystal face, and a method for manufacturing the semiconductor light emitting device. In the above, it is an object of the present invention to provide a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device, which can prevent impurities from diffusing from the cladding layer to the active layer and prevent deterioration of the active layer.

[0009]

In a semiconductor light emitting device according to the present invention, a crystal layer having a tilted crystal plane tilted with respect to a main surface of the substrate is formed on a substrate, and an in-plane surface parallel to the tilted crystal plane is formed. A first conductivity type layer, an active layer, and a second conductivity type layer extending in the crystal layer, and an undoped crystal layer extending in a plane parallel to the tilted crystal plane in proximity to the active layer. And is formed in the crystal layer.

By forming an undoped crystal layer in the vicinity of an active layer formed extending in a plane parallel to the tilted crystal plane in the crystal layer having a tilted crystal plane tilted with respect to the principal surface of the substrate, The undoped crystal layer can prevent impurities from diffusing from the conductivity type layer to the active layer due to the inclination of the crystal plane. In particular, impurities can be prevented from diffusing from the second conductivity type layer, which is the outermost layer of the crystal layer, into the active layer. Furthermore, since impurities that diffuse from the conductivity type layer to the active layer can be prevented by the undoped crystal layer, it is possible to form a semiconductor light emitting device in which the crystal quality of the active layer is not deteriorated and the active layer is not deteriorated by the impurities. .

In a semiconductor light emitting device in which an active layer is formed by extending in a plane parallel to a tilted crystal plane in a crystal layer having a tilted crystal plane tilted with respect to a main surface of a substrate, a conductive type layer is changed to an active layer. Since the diffusion of the impurities can be prevented, the impurity concentration of the conductive type layer can be increased, and a semiconductor light emitting element having high luminous efficiency can be formed.

A method of manufacturing a semiconductor light emitting device according to the present invention comprises a step of forming a mask layer or a crystal seed layer having an opening on a substrate, and a step of forming the mask layer or the crystal seed layer from the opening of the mask layer or the crystal seed layer. A step of selectively forming a crystal layer having a tilted crystal plane inclined with respect to the first conductivity type layer extending in a plane parallel to the tilted crystal plane, an active layer,
And a step of forming a second conductivity type layer in the crystal layer, and a step of forming an undoped crystal layer extending in a plane parallel to the tilted crystal plane in the crystal layer close to the active layer. It is characterized by

By forming an undoped crystal layer in the vicinity of an active layer formed in a crystal layer having a tilted crystal plane tilted with respect to the main surface of the substrate and extending in a plane parallel to the tilted crystal plane, The undoped crystal layer can prevent impurities from diffusing from the conductivity type layer to the active layer due to the inclination of the crystal layer. In particular, impurities can be prevented from diffusing from the second conductivity type layer, which is the outermost layer of the crystal layer, into the active layer. Furthermore, since impurities that diffuse from the conductivity type layer to the active layer can be prevented by the undoped crystal layer, the active layer can be prevented from being deteriorated by impurities without lowering the crystal quality of the active layer.

In a semiconductor light emitting device in which an active layer is formed by extending in a plane parallel to a tilted crystal plane in a crystal layer having a tilted crystal plane tilted with respect to a main surface of a substrate, from a conductivity type layer to an active layer Since the diffusion of the impurities can be prevented, the impurity concentration of the conductive type layer of the semiconductor light emitting element can be increased and the luminous efficiency can be improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In a semiconductor light emitting device according to the present invention, a crystal layer having a tilted crystal plane tilted with respect to a principal surface of the substrate is formed on a substrate and extends in a plane parallel to the tilted crystal plane. A first conductivity type layer, an active layer, and a second conductivity type layer are formed in a crystal layer, and an undoped crystal layer extending in a plane parallel to a tilted crystal plane is formed in the crystal layer close to the active layer. It is characterized by

The substrate used in the present invention is not particularly limited as long as it can form a wurtzite type compound semiconductor layer, and various substrates can be used. For example, sapphire (including Al ₂ O ₃ , A plane, R plane, and C plane), S
iC (including 6H, 4H, 3C), GaN, Si, Z
nS, ZnO, AlN, LiMgO, LiGaO ₂ , G
A substrate made of aAs, MgAl ₂ O ₄ , InAlGaN, or the like, preferably a hexagonal substrate or a cubic substrate made of these materials, more preferably a hexagonal substrate. For example, when a sapphire substrate is used, it is possible to use a sapphire substrate having a C-plane as a main surface, which is often used when growing a gallium nitride (GaN) -based compound semiconductor material. In this case, the C-plane as the main surface of the substrate is substantially equivalent to the S-plane including the plane orientation inclined in the range of 5 to 6 degrees. It is also possible to use a silicon substrate or the like that is widely used for manufacturing semiconductor devices.

The crystal layer formed on the substrate has a tilted crystal plane tilted with respect to the principal surface of the substrate, and extends in a plane parallel to the tilted crystal plane tilted with respect to the principal surface of the substrate described later. There is no particular limitation as long as it is a material layer capable of forming the first conductivity type layer, the active layer, and the second conductivity type layer. As such a material layer, a wurtzite type compound semiconductor layer is preferably selected because a facet structure is formed in a step described later. As the compound semiconductor layer, a nitride-based compound semiconductor having a wurtzite crystal structure, Be
MgZnCdS compound semiconductor and BeMgZnC
A dO compound semiconductor or the like is preferable. As the crystal layer made of a nitride-based compound semiconductor, for example, a group III-based compound semiconductor can be used, and gallium nitride (Ga
N) -based compound semiconductors, aluminum nitride (AlN) -based compound semiconductors, indium nitride (InN) -based compound semiconductors, indium gallium nitride (InGaN) -based compound semiconductors, and aluminum gallium nitride (AlGaN) -based compound semiconductors are preferable, and gallium nitride-based compound semiconductors are particularly preferable. Compound semiconductors are preferred. As an example, an undoped GaN layer is formed on a sapphire substrate, and then Si-doped GaN is formed.
You may form a layer. In the present invention, InGa
N, AlGaN, GaN, etc. do not necessarily mean a ternary compound crystal-only nitride compound compound semiconductor. For InGaN, for example, a trace amount of Al within a range that does not change the action of InGaN, other Needless to say, the inclusion of the above impurities is within the scope of the present invention. In addition, in the present specification, a nitride refers to a compound in which B, Al, Ga, In, and Ta are group III and N is included in group V, and 1
% Or less than 1 × 10 ²⁰ cm ³ may be mixed in.

As a method for growing the crystal layer, various vapor phase epitaxy methods can be mentioned, for example, vapor phase epitaxy method (MOCVD (MOVPE) method) and molecular beam epitaxy method (MBE method). There are a phase growth method and a hydride vapor phase growth method (HVPE method). MO among them
According to the CVD method, a material with good crystallinity can be obtained quickly. In the MOCVD method, as a Ga source, TMG (trimethylgallium), TEG (triethylgallium), A
As the l source, TMA (trimethylaluminum),
Alkali metal compounds such as TMI (trimethylindium) and TEI (triethylindium) are often used as TEA (triethylaluminum) and In sources, and gases such as ammonia and hydrazine are used as nitrogen sources. As the impurity source, silane gas is used for Si, germane gas is used for Ge, Cp2Mg (cyclopentadienyl magnesium) is used for Mg, and DEZ (diethyl zinc) is used for Zn. Generally, in the MOVPE method, an InAlGaN-based compound semiconductor can be epitaxially grown by supplying these gases to the surface of a heated substrate and decomposing them.

It is preferable to form an undergrowth layer on the substrate before forming the crystal layer, and this undergrowth layer is composed of a gallium nitride layer, an aluminum nitride layer, or the like. The base growth layer may be formed by combining the low temperature buffer layer and the high temperature buffer layer, or may be formed by combining the buffer layer and the crystal seed layer that functions as a crystal seed. Like the crystal layer, this undergrowth layer can be formed by various vapor phase growth methods,
For example, a vapor phase growth method such as a metal organic compound vapor phase growth method (MOVPE method), a molecular beam epitaxy method (MBE method), or a halide vapor phase growth method (HVPE method) can be used.

When the growth of the crystal layer is started from the low temperature buffer layer, polycrystals are likely to be deposited on the mask. Therefore, by including a crystal seed layer and then growing a different surface from the substrate, the crystallinity is further improved. Crystals can grow. In addition, in order to perform crystal growth using selective growth, a crystal seed layer is formed from a buffer layer, but when selective growth is performed from the buffer layer, growth is hindered in the part where growth does not have to occur. Is more likely to occur. Therefore, by using the crystal seed layer, it is possible to grow the crystal with good selectivity in the region where the growth is required.

The formation of the buffer layer can alleviate the lattice mismatch between the substrate and the nitride-based compound semiconductor, but when using a substrate having a lattice constant close to that of the nitride-based compound semiconductor or a substrate having a matching lattice constant. In some cases, a nitride-based compound semiconductor may be grown without forming a buffer layer. For example, a buffer layer of AlN not at low temperature may be formed on SiC, and AlN or GaN may be formed on a Si substrate.
May grow as a buffer layer without lowering the temperature.
Even if a buffer layer that is not low in temperature is formed in this way, a good quality G
aN can be formed. In addition, as in the case of using the GaN substrate, the buffer layer may not be provided in particular.

In the present invention, the selective growth method can be used to form a tilted crystal plane tilted with respect to the main surface of the substrate. The tilted crystal plane tilted with respect to the principal plane of the substrate depends on the selection of the principal plane of the substrate, but when the wurtzite (0001) plane (C plane) is used as the principal plane of the substrate, (1
-100) plane (M plane), (1-101) plane (S plane),
(11-20) plane (A plane), (1-102) plane (R
Surface), (1-123) surface (N surface), (11-22) surface,
And a tilted crystal plane selected from crystal planes equivalent to these. In particular, S-plane, (11-22) plane, and 5
It is preferable to use crystal planes equivalent to those including plane orientations inclined in the range of 6 degrees. When the selective crystal growth layer is formed by selective growth, it is possible to easily form the S-plane or a plane substantially equivalent to the S-plane. S surface is C + surface (C
The plane index of the + plane is (0001), which is a stable plane observed when selectively grown on, and is a surface that is relatively easy to obtain, and the hexagonal plane index is (1-101). Also,
Similar to the C + and C− planes on the C plane, there are S + and S− planes on the S plane, but in the present specification, unless otherwise specified, S on the C + plane GaN. Regarding the plane, the S + plane, which is a stable plane, is growing, and this is designated as the S plane.

Regarding the S-plane, when the crystal layer is made of a gallium nitride-based compound semiconductor as described above,
The number of bonds from Ga to N is 2 or 3, which is the second largest after the C-plane. Here, since the C-plane cannot be practically obtained on the C + plane, the number of bonds on the S-plane becomes the largest. For example, when a nitride is grown on a sapphire substrate having a C + plane as the main surface, the surface of the wurtzite type nitride generally becomes the C + plane, but the S plane is stably formed by utilizing selective growth. The bond of N, which has a tendency to be easily desorbed on the plane parallel to the C + plane, is bonded by one bond from Ga, while it is bonded by at least one bond or more on the inclined S surface. It will be. Therefore, the V / III ratio is effectively increased, which is advantageous for improving the crystallinity of the laminated structure. Further, when grown in a direction different from that of the substrate, dislocations extending upward from the substrate may be bent, which is also advantageous in reducing defects.

In the semiconductor light emitting device of the present invention, the crystal layer has a structure having an inclined crystal plane inclined with respect to the main surface of the substrate. In particular, the crystal layer is substantially S-plane or substantially equivalent to S-plane. The surface may be a structure forming a substantially hexagonal pyramid-shaped slope, or a surface substantially equivalent to the S-plane or the S-plane may be a substantially hexagonal-pyramidal-shaped slope, respectively, and a C-plane or a C-plane. The surface that is substantially equivalent to the surface may be a structure forming the upper flat surface portion of the substantially hexagonal truncated pyramid shape, that is, a substantially hexagonal truncated pyramid shape. The substantially hexagonal pyramid shape and the substantially hexagonal pyramid shape do not need to be exactly hexagonal pyramids, and include those in which some of the faces disappear. In a preferred example, the tilted crystal planes are arranged in six planes and are substantially symmetrical. The term “substantially symmetrical” includes not only the case where the shape is completely symmetrical but also the case where the shape is slightly deviated from the symmetrical shape. Further, the ridgeline between the crystal planes of the crystal layer does not necessarily have to be a straight line, and the substantially hexagonal pyramid shape or the approximately hexagonal pyramid shape may be a linearly extended shape.

As a specific selective growth method, the selective growth is performed selectively by utilizing an opening portion of a mask layer formed on the underlayer growth layer or before forming the underlayer growth layer, or by underlayer growth. It is performed by selectively removing part of the layer. When the mask layer formed on the underlying growth layer is selectively opened to form a window region and selectively grown, the mask layer can be formed of, for example, a silicon oxide layer or a silicon nitride layer, and the thickness is It is in the range of 100 to 500 nm. An opening for growing the selective crystal growth layer is formed in the mask layer on the underlying crystal layer by using a photolithography technique and a required etchant. The size of the opening is set according to the characteristics of the semiconductor light emitting device to be created, but as an example, the size is about 10 μm, and its shape is rectangular, square, circular, hexagonal. Shape, triangular,
Various shapes such as a rhombus shape and an elliptical shape can be used. When the above-described substantially hexagonal truncated pyramid shape or substantially hexagonal pyramid shape is a linearly extended shape, a pyramidal frustum or pyramid shape in which one direction is the longitudinal direction makes the window region of the mask layer band-shaped. Alternatively, the crystal seed layer may be formed into a band shape. When the underlying growth layer is composed of a buffer layer and a crystal seed layer, for example, 10 μs interspersed with the crystal seed layer on the buffer layer.
It is possible to form a crystal layer having an S-plane or the like by subdividing into small regions of about m diameter and crystal growth from each portion. For example, the subdivided crystal seed layers can be arranged so as to be separated with a margin for separation as a semiconductor light emitting element, and the individual small regions can be circular, square, hexagonal, triangular. Shape, rectangular,
The shape may be a rhombus or a modified shape thereof. Crystal growth from the crystal seed portion is performed by making a selective mask, leaving a portion with the mask, and etching the other portion to obtain a seed crystal portion, and selectively growing from the seed crystal portion. Less affected by mask contamination.

The window region of the mask layer is made 10 μm thick by selective growth.
A circle of about m (or a hexagon with 1-100 sides)
Alternatively, a selective growth region having a size about twice that of the hexagonal shape with sides of 11-20 directions can be easily manufactured.
Further, if the S-plane is in a direction different from that of the substrate, it has an effect of bending dislocations and an effect of shielding dislocations, which is also useful for reducing dislocation density. Further, in the case where the substantially hexagonal pyramid shape or the substantially hexagonal pyramid shape is a linearly extended shape, the pyramidal frustum or the pyramid shape having one direction as the longitudinal direction makes the window region of the max layer into a band shape, or This is possible by forming the crystal seed layer into a band shape.

In the experiment conducted by the present inventors, observation of the hexagonal truncated pyramid shape grown by using cathodoluminescence shows that the crystals on the S-plane are of good quality and the luminous efficiency is higher than that on the C + plane. Has been shown. Especially I
Since the growth temperature of the nGaN active layer is 700 to 800 ° C, the decomposition efficiency of ammonia is low and more N species are required. Also, when the surface was observed with an AFM, the steps were aligned and a surface suitable for incorporation of InGaN was observed. Furthermore, it is known that the growth surface of the Mg-doped layer generally has a poor surface condition at the AFM level, but the growth of the S-plane also causes the Mg-doped layer to grow in a good surface condition and the doping conditions are considerably different. . In addition, when microphotoluminescence mapping is performed, it can be measured with a resolution of about 0.5 to 1 μm, but in the usual method of growing on the C + plane, unevenness of about 1 μm pitch exists, and S by selective growth Uniform results were obtained for the surface-obtained samples. Further, the flatness of the slope viewed by SEM is smoother than that of the C + surface.

Further, in the case of selective growth using a selective growth mask, since there is no lateral growth when growing only on the opening of the selective mask, the lateral growth is performed using microchannel epitaxy. It is possible to make the shape larger than the window region. It is known that the lateral growth using such microchannel epitaxy makes it easier to avoid threading dislocations and reduces dislocations. In addition, such lateral growth also increases the light emitting region, which makes it possible to make the current uniform, avoid current concentration, and reduce the current density.

In the semiconductor light emitting device of the present invention, the first conductivity type layer, the active layer, and the second conductivity type layer extending in the plane parallel to the tilted crystal plane tilted with respect to the main surface of the substrate are crystal layers. And an undoped crystal layer is formed adjacent to the active layer.
At this time, the undoped crystal layer is formed close to the active layer, but it may be formed so as to sandwich the active layer, or may be formed only on either the first conductivity type layer side or the second conductivity type layer side. You may. When forming only one of them,
In particular, since the diffusion of impurities from the second conductivity type layer side to the active layer is severe, it is preferably formed on the second conductivity type layer side. The film thickness of the undoped crystal layer formed near the active layer is
When it is less than 10Å, the carrier injection efficiency is increased, but the crystallinity of the crystal layer formed on the undoped crystal layer is lowered to lower the light emission efficiency. When it is more than 100 nm, it is formed on the undoped crystal layer. The crystallinity of the crystalline layer increases, but the carrier injection efficiency decreases and the light emission efficiency decreases, so 10 Å or more and 100 nm or less is preferable. The first conductivity type is a p-type or n-type cladding layer, and the second conductivity type is the opposite conductivity type. For example, when the crystal layer forming the S-plane is composed of a silicon-doped gallium nitride compound semiconductor layer, the n-type cladding layer is composed of a silicon-doped gallium nitride compound semiconductor layer,
A double hetero structure in which an InGaN layer is formed thereon as an active layer and a p-type cladding layer is formed thereon using a magnesium-doped gallium nitride-based compound semiconductor layer can be adopted. The active layer, In,
An undoped GaN layer, which is an undoped crystal layer, is formed adjacent to the GaN layer. In addition, Ga is formed on both sides of the active layer.
It is also possible to form a multi-structure by forming a guide layer such as N or InGaN layer, and a magnesium-doped AlGaN layer formed between the guide layer such as a magnesium-doped GaN layer formed on the p-side and the active layer. Are preferably formed. In this way, when the active layer is sandwiched by the guide layers or the magnesium-doped AlGaN layer is formed,
The undoped crystal layer formed between the active layer and the guide layer is formed close to the active layer to prevent impurities from diffusing from the conductivity type layer to the active layer. The active layer may be composed of a single bulk active layer, but a quantum well having a single quantum well (SQW) structure, a double quantum well (DQW) structure, a multiple quantum well (MQW) structure, or the like. The structure may be formed. A barrier layer is additionally used in the quantum well structure for the purpose of separating the quantum well. Similarly, when forming such a quantum well structure, the undoped crystal layer is formed close to the active layer to prevent impurities from diffusing from the conductivity type layer to the active layer.

For example, when the active layer is an InGaN layer, the structure is particularly easy to manufacture in the manufacturing process, and the light emitting characteristics of the device can be improved. Furthermore, the InGaN layer is particularly easy to crystallize and has good crystallinity when grown on the S-plane, which has a structure in which nitrogen atoms are hard to be desorbed, and the luminous efficiency can be improved. In the semiconductor light emitting device of the present invention,
An undoped crystal layer such as an undoped GaN layer is formed close to the active layer, and the undoped crystal layer can prevent impurities of the conductivity type layer from diffusing into the active layer. Therefore, the concentration of impurities doped into the conductivity type layer can be increased, and the luminous efficiency can be further improved. It should be noted that the nitride-based compound semiconductor has a property of becoming an n-type due to nitrogen vacancies formed in the crystal even if it is undoped.
By doping donor impurities such as during crystal growth,
The n-type carrier having a preferable carrier concentration can be used. The undoped crystal layer has similar properties, but may be doped as long as the carrier concentration of the undoped crystal layer is such that impurities do not diffuse and deteriorate in the active layer. Further, in order to make the nitride-based compound semiconductor p-type, Mg, Z
It is obtained by doping with acceptor impurities such as n, C, Be, Ca and Ba. High carrier concentration p
In order to form the mold layer, after the acceptor impurities are doped, the mold layer is formed in an atmosphere of an inert gas such as nitrogen or argon.
Annealing is preferably performed at 0 ° C. or higher, and there is also a method of activation by electron beam irradiation, microwave irradiation, light irradiation, or the like.

The first-conductivity-type layer, the active layer, the second-conductivity-type layer, and the undoped crystal layer are formed so as to extend in a plane parallel to the inclined crystal plane that is inclined with respect to the main surface of the substrate. The extension into the tilted crystal plane can be easily performed by continuing the crystal growth where the tilted crystal plane is formed. For example, when the crystal layer has a substantially hexagonal pyramid shape or a substantially triangular prism shape, and each inclined crystal plane is an S plane, etc., all of the first conductivity type layer, the active layer, the second conductivity type layer, and the undoped crystal layer are included. Alternatively, it can be formed on a part of the S surface. Light is attenuated by multiple reflection on a parallel plate by utilizing the inclined S surface to emit light, but if there is an inclined surface, light can escape the effect of multiple reflection and go out of the semiconductor. There is an advantage. In addition, light extraction can be improved if the surface is not perpendicular to the substrate. The first-conductivity-type layer, that is, the clad layer, can be made of the same material and have the same conductivity type as the crystal layer forming the S-plane, and is formed by continuously adjusting the concentration after forming the crystal layer forming the S-plane. can do. As another example, a structure in which a part of the crystal layer of the S-plane functions as the first conductivity type layer may be used. Similarly, when forming the active layer, the sources can be switched to form the layers by continuously adjusting the concentration, but it is necessary to switch the sources sharply. However, when the undoped crystal layer is formed in the vicinity of the active layer, the undoped crystal layer may contain impurities to the extent that the impurities do not diffuse into the active layer. Therefore, while continuously adjusting the concentration from the first conductivity type layer, There is no need to sharply adjust the density.

In the semiconductor light emitting device of the present invention, the first conductivity type layer, the active layer, and the second conductivity type layer are parallel to the tilted crystal plane on the crystal layer having the tilted crystal plane tilted with respect to the main surface of the substrate. The semiconductor light emitting device is formed so as to extend inward, and an undoped crystal layer is formed adjacent to the active layer. Therefore, the impurities diffused from the conductivity type layer to the active layer can be blocked by the undoped crystal layer, and the deterioration of the active layer can be prevented without lowering the crystal quality of the active layer. Since the impurities that diffuse from the conductivity type layer to the active layer can be blocked by the undoped crystal layer, it is possible to dope more impurities into the conductivity type layer and improve the luminous efficiency of the semiconductor light emitting device. Further, as impurities diffuse from the conductivity type layer to the active layer, a diffusion current outside the design occurs and a leak current occurs, but by forming an undoped crystal layer close to the active layer, the conductivity type layer Impurities can be prevented from diffusing into the active layer, and a diffusion current that is a leak current can be prevented.

Further, in the semiconductor light emitting device of the present invention, the light emitting efficiency can be enhanced by utilizing the good crystallinity of the inclined crystal planes. In particular, when a current is injected only into the S-plane, which has good crystallinity, the S-plane can take in In well and have good crystallinity, so that the light emission efficiency can be increased. Further, the area extending in the plane substantially parallel to the S-plane of the active layer may be larger than the area when the active layer is projected on the main surface of the substrate or the underlying growth layer. By increasing the area of the active layer, the light emitting area of the device is increased, the current density can be reduced, and it is possible to reduce the brightness saturation, which can increase the light emission efficiency. Therefore, when the undoped crystal layer is formed close to the active layer, the luminous efficiency can be further improved.

When forming the first-conductivity-type layer, the active layer, and the second-conductivity-type layer in a plane parallel to the inclined crystal plane, it is not possible to uniformly form the impurity concentration in the conductivity-type layer. Since it is difficult, the concentration of impurities to be doped is precisely controlled to uniformly dope the conductivity type layer. However, even if the impurity concentration is precisely controlled, there is a limit due to its three-dimensional structure, and since the impurity concentration is generally non-uniform, a concentration gradient occurs and the concentration gradient causes a difference between the conductivity type layer and the active layer. Leak current is generated at the interface. Therefore, by forming an undoped crystal layer close to the active layer,
Leakage current can be prevented from occurring at the interface on the active layer side, and the controllability of the impurity concentration can be reduced. Further, since it is difficult to form a crystal layer while making the film thickness uniform within the tilted crystal plane, it is difficult to form the active layer and the conductivity type layer with a uniform film thickness. Brightness unevenness is likely to occur without exhibiting the normal light emission characteristics. When the undoped crystal layer is formed close to the active layer,
Such nonuniformity of the film thickness can be alleviated, and unevenness in brightness can be reduced.

As described above, in the semiconductor light emitting device of the present invention, the first conductivity type layer, the active layer, and the second conductivity type layer are formed in the plane parallel to the tilted crystal plane tilted with respect to the main surface of the substrate. By forming an undoped crystal layer in the vicinity of the active layer of the semiconductor light emitting device, it is possible to prevent diffusion of impurities from the conductivity type layer to the active layer and prevent deterioration of the active layer. It is possible to avoid the occurrence of leakage current due to the non-uniformity of the film thickness, and to reduce the unevenness of the brightness due to the non-uniformity of the film thickness. Furthermore, since the active layer formed in the plane parallel to the tilted crystal plane due to the structure of the semiconductor light emitting element has good crystallinity and a large effective area, impurities are diffused from the conductivity type layer to the active layer by the undoped crystal layer. Instead, the conductive type layer can be doped with a large amount of impurities to form a semiconductor light emitting device having higher luminous efficiency.

[First Embodiment] A semiconductor light-emitting device formed of a hexagonal pyramidal crystal layer having a substantially triangular cross section, which is formed by selective growth and has an S-plane as an inclined crystal plane inclined with respect to the main surface of a substrate. The element will be described together with its manufacturing process with reference to FIGS.

First, the underlayer growth layer 11 is formed on the substrate 10, and the mask layer 12 is formed on the underlayer growth layer 11. As an example, an undoped GaN layer and a silicon-doped GaN layer are formed on a sapphire substrate having a C plane as a main surface, and a mask layer 12 made of a silicon oxide film is formed by a sputtering method or the like.

After the base growth layer 11 and the mask layer 12 are formed on the substrate 10 in this way, a part of the mask layer 12 is removed to form the opening 13 (FIG. 1). Opening 13
Can be formed using, for example, photolithography and a hydrofluoric acid-based etchant. In FIG. 1, the shape of the opening 13 is hexagonal, but any shape that can form a hexagonal pyramidal crystal layer such as a circular shape may be used. The size of the opening 13 can be changed according to the characteristics of the semiconductor light emitting device.

As shown in FIG. 2, the first conductivity type layer 14 is grown through the hexagonal opening 13 by selective growth. First, the underlayer growth layer 11 is grown through the opening 13 and is grown for a while. If you continue the
The hexagonal pyramid-shaped underlying growth layer 11 of 1}) is exposed. If the growth conditions such as insufficient growth time are different, the shape becomes a hexagonal truncated pyramid shape, but by controlling the growth time, the hexagonal pyramid covered with the S surface is formed almost in the frame of the opening 13 and has a substantially triangular cross section. The hexagonal pyramid-shaped first conductivity type layer 14 is formed.

As shown in FIG. 3, a lower undoped crystal layer 15 is formed on the first conductivity type layer 14, and an active layer 16, an upper undoped crystal layer 17 and a second conductivity type layer 18 are sequentially formed thereon. It is formed. The crystal layer formed on the first-conductivity-type layer 14 is a hexagonal pyramid-shaped crystal layer having a substantially triangular cross section, and an inclined surface which is a side surface of the hexagonal pyramid-shaped crystal layer is an S plane ({1-1
(01} plane) or {11-22} plane and is stably formed during selective growth.

The first-conductivity-type layer 14 and the second-conductivity-type layer 18 function as clad layers, and the active layer 16 functions as a layer for generating light of the semiconductor light emitting device. The lower undoped crystal layer 15 prevents impurities doped in the first conductivity type layer 14 from diffusing into the active layer 16, and the upper undoped crystal layer 1
7 prevents impurities doped in the second conductivity type layer 18 from diffusing into the active layer 16. In particular, in an element having a three-dimensional structure of hexagonal pyramids, the diffusion of impurities from the second-conductivity-type layer 18 to the active layer 16 is severe.
It is possible to prevent the diffusion. Thus, the lower undoped crystal layer 15 and the upper undoped crystal layer 17
By forming the above, it is possible to prevent deterioration of the active layer 16 without diffusing impurities into the active layer 16 and without lowering the crystal quality of the active layer 16.

Both the lower undoped crystal layer 15 and the upper undoped crystal layer 17 may be formed adjacent to the active layer 16, or one of them may be formed. When one is formed, it is preferable to form the upper undoped crystal layer 17 because the diffusion of impurities from the second conductivity type layer 18 is severe. As an example, the first conductivity type layer 14 is a silicon-doped GaN layer, the second conductivity type layer 18 is a magnesium-doped GaN layer, the active layer 16 is an InGaN layer, and the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are undoped. Can be a GaN layer. The upper undoped crystal layer 15 and the lower undoped crystal layer 17 formed in the vicinity of the active layer preferably have a film thickness of 10 Å or more and 100 nm or less. This is because when the film thickness is smaller than 10Å, the carrier injection efficiency is increased, but the crystallinity of the active layer 16 and the second conductivity type layer 18 formed on the undoped crystal layer is reduced and the emission efficiency is reduced. , The active layer 1 formed on the undoped crystal layer when the film thickness is larger than 100 nm
This is because although the crystallinity of No. 6 or the second conductivity type layer 18 is increased, the injection efficiency of carriers is reduced and the emission efficiency is reduced. The lower undoped crystal layer 15 and the upper undoped crystal layer 17 may be doped with impurities to the extent that they do not diffuse into the active layer 16 and deteriorate. Impurities to be doped into the second conductivity type layer 18 include zinc and beryllium.

Although the active layer 16 may be formed of a single bulk active layer, a single quantum well (SQW) structure,
Double quantum well (DQW) structure, multiple quantum well (MQW)
A quantum well structure such as a structure may be formed. A barrier layer is additionally used in the quantum well structure for the purpose of separating the quantum well. In addition, G is provided on both sides of the active layer 16.
It is possible to form a multiple layer structure by forming a guide layer such as aN, but magnesium-doped G formed on the p-side.
It is preferable to form a magnesium-doped AlGaN layer between the active layer 16 and a guide layer such as an aN layer or an InGaN layer. When the active layer 16 is sandwiched between the guide layers or the magnesium-doped AlGaN layer is formed as described above, the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed so as to be close to the active layer 16, Are prevented from diffusing into the active layer 16 and degrading the active layer 16.

The first conductivity type layer 1 is formed on the substrate 10 so as to extend in a plane parallel to the tilted crystal plane tilted with respect to the main surface of the substrate 10.
4, when the active layer 16 and the second-conductivity-type layer 18 are formed, it is necessary to rapidly and continuously adjust the concentration of the growth gas for impurities due to its three-dimensional structure.
When the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed in the vicinity of 6, the lower undoped crystal layer 1
5 and the upper undoped crystal layer 17 may be doped with impurities to the extent that the active layer 16 is not deteriorated, it is not necessary to switch the growth gas sharply.

As shown in FIG. 4, a p-side electrode 19 is formed on the second conductivity type layer 18 which is the outermost layer. p-side electrode 19
Is, for example, a Ni / Pt / Au electrode structure or Ni (P
d) An electrode layer having an electrode structure of / Pt / Au, which is accurately formed by a vapor deposition method or the like.

As shown in FIG. 5, after the p-electrode 19 is formed, the main surface of the substrate 10 is separated by reactive ion etching or dicer to form an element isolation groove 20, and each element is formed on the substrate 10. To separate. For example, when the element isolation trench is formed by reactive ion etching, a silicon oxide film or the like serving as a protective film for preventing erosion due to dry etching is formed over the entire surface of the crystal layer by a plasma CVD method or the like, and then reactive ion etching is performed. The element isolation groove 20 is formed by etching and removing the protective film with acid or the like.
Is formed.

Next, using an excimer laser, a YAG laser, or the like, a region to be an element portion is peeled from the substrate 10. When laser is irradiated from the back surface of the substrate 10, the interface between the underlying growth layer 11 and the substrate 10 is irradiated. As a result, ablation occurs and the crystal layer can be separated from the substrate 10.
For example, when the substrate 10 is a sapphire substrate and the underlying growth layer 11 is GaN, and an excimer laser is irradiated from the back surface,
GaN is decomposed into metallic gallium and nitrogen at the interface between the sapphire substrate and the GaN layer, and the GaN layer can be easily separated from the sapphire substrate.

Ti / Al / Pt / A is formed on the back surface of the device.
Accurately deposit the u electrode (FIG. 6). This electrode functions as the n-side electrode 21 arranged on the back surface of the element. It is preferable that the n-side electrode 21 provided on the back surface of the element is provided at a corner portion so as not to block the light emitted from the back surface.
When the underlying growth layer 11 is composed of an undoped underlying growth layer and a doped underlying growth layer, the undoped underlying growth layer is removed by wet etching to form the n-side electrode 21, and then the electrode is deposited. .

In the semiconductor light emitting device in which the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed close to the active layer 16 as described above, the first conductive type layer 14 and the second conductive type layer 18 to the active layer are formed. Impurities do not diffuse into the active layer 16, and deterioration of the active layer 16 can be prevented without lowering the crystal quality of the active layer 16. Furthermore, since diffusion of impurities into the active layer 16 can be prevented, the luminous efficiency of the semiconductor light emitting device can be improved by doping more impurities into the first conductivity type layer 14 and the second conductivity type layer 18. You can

[Second Embodiment] A semiconductor light emitting device which is formed by selective growth and has a triangular columnar crystal layer having a substantially triangular cross section and having an S-plane as an inclined crystal plane inclined with respect to the main surface of the substrate. The element will be described together with the manufacturing process thereof with reference to FIGS.

First, the underlayer growth layer 31 is formed on the substrate 30, and the mask layer 32 is formed on the underlayer growth layer 31. As an example, an undoped GaN layer and a silicon-doped GaN layer are formed on a sapphire substrate having a C-plane as a main surface, and a mask layer made of a silicon oxide film is formed by a sputtering method or the like.

After the base growth layer 31 and the mask layer 32 are formed on the substrate 30 in this way, a part of the mask layer 32 is removed to form an opening 33 (FIG. 7). Opening 33
Can be formed using, for example, photolithography and a hydrofluoric acid-based etchant. The opening 33 has a stripe shape, and its longitudinal direction is [1-10
0] direction or [11-20] direction. Opening 3
By extending the shape of 3 as a stripe shape in the [1-100] direction or the [11-20] direction, an S-plane is formed as an inclined crystal plane inclined with respect to the main surface of the substrate 30, and the ridge line 35 is an opening. It is possible to form a triangular prism-shaped crystal layer having a direction of 33. The size of the opening 33 can be changed according to the characteristics of the semiconductor light emitting device.

As shown in FIG. 8, the first-conductivity-type layer 34 is grown from the stripe-shaped opening 33 by selective growth. First, the underlying growth layer 31 is opened from the opening 33.
However, when the growth continues for a while, the tilted crystal plane is the S plane and the ridge line 3
Trigonal prism whose 5 directions are [1-100] direction or [11-20] direction, and the inclined surfaces formed on both sides of the ridgeline 35 are S-plane ({1-101} plane) or {11-22} plane The underlying growth layer 31 having a shape is exposed, and the first conductivity type layer 34 is formed.
Is formed.

As shown in FIG. 8, a lower undoped crystal layer 36 is formed on the first conductivity type layer 34, and an active layer 37, an upper undoped crystal layer 38, and a second conductivity type layer 39 are formed thereon. It is formed. These layers are crystal layers each having a triangular prism shape with a substantially triangular cross section, and the ridge line 35 has the above-mentioned [1-10].
The inclined planes formed on both sides of the ridgeline 35 in the [0] direction or the [11-20] direction are S planes ({1-101} planes) or {11-22} planes, and are stably formed during selective growth. To be done.

The first-conductivity-type layer 34 and the second-conductivity-type layer 39 function as a clad layer, and the active layer 37 functions as a layer for generating light of the semiconductor light emitting device. The lower undoped crystal layer 36 prevents impurities doped in the first conductivity type layer 34 from diffusing into the active layer 37, and the upper undoped crystal layer 3
8 prevents the impurities doped in the second conductivity type layer 39 from diffusing into the active layer 37. In particular, in an element having a three-dimensional structure of a triangular prism, the diffusion of impurities from the second conductivity type layer 39 to the active layer 37 is severe, so that the upper undoped crystal layer 38 is formed to cause impurities to diffuse into the active layer 37.
It is possible to prevent the diffusion. Thus, the lower undoped crystal layer 36 and the upper undoped crystal layer 38
By forming the, it is possible to prevent deterioration of the active layer 37 without diffusing impurities into the active layer 37 and without lowering the crystal quality of the active layer 37.

Both the lower undoped crystal layer 36 and the upper undoped crystal layer 38 may be formed adjacent to the active layer 37, or one of them may be formed. When one is formed, it is preferable to form the upper undoped crystal layer 38 because the diffusion of impurities from the second conductivity type layer 39 is severe. As an example, the first conductivity type layer 34 is a silicon-doped GaN layer, the second conductivity type layer 39 is a magnesium-doped GaN layer, the active layer 37 is an InGaN layer, and the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are undoped. Can be a GaN layer. The thickness of the upper undoped crystal layer 36 and the lower undoped crystal layer 38 is preferably 10 Å or more and 100 nm or less. This is because when the film thickness is smaller than 10Å, the carrier injection efficiency is increased, but the crystallinity of the active layer 37 and the second conductivity type layer 39 formed on the undoped crystal layer is reduced and the emission efficiency is reduced. When the film thickness is larger than 100 nm, the crystallinity of the active layer 37 and the second conductivity type layer 39 formed on the undoped crystal layer increases, but the carrier injection efficiency decreases and the light emission efficiency decreases. is there. Further, the lower undoped crystal layer 36 and the upper undoped crystal layer 38 may be doped with impurities to the extent that they do not diffuse into the active layer 37 and deteriorate. Impurities with which the second conductivity type layer 39 is doped include zinc and beryllium.

Although the active layer 37 can be formed of a single bulk active layer, a single quantum well (SQW) structure,
Double quantum well (DQW) structure, multiple quantum well (MQW)
A quantum well structure such as a structure may be formed. A barrier layer is additionally used in the quantum well structure for the purpose of separating the quantum well. Further, G is provided on both sides of the active layer 37.
It is possible to form a multiple layer structure by forming a guide layer such as aN, but magnesium-doped G formed on the p-side.
It is preferable to form a magnesium-doped AlGaN layer between the active layer 37 and a guide layer such as an aN layer or an InGaN layer. When the active layer 37 is sandwiched by the guide layers or the magnesium-doped AlGaN layer is formed as described above, the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed close to the active layer 37, and impurities are Are prevented from diffusing into the active layer 37 and degrading the active layer 37.

The first conductivity type layer 3 is formed on the substrate 30 and extends in a plane parallel to the tilted crystal plane tilted with respect to the main surface of the substrate 30.
4, when the active layer 37 and the second-conductivity-type layer 39 are formed, it is necessary to rapidly and continuously adjust the concentration of the growth gas for impurities due to its three-dimensional structure.
When the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed in the vicinity of 7, the lower undoped crystal layer 3
6 and the upper undoped crystal layer 38 may be doped with impurities to such an extent that the active layer is not deteriorated, so that it is not necessary to switch the growth gas sharply.

As shown in FIG. 10, the p-side electrode 40 is formed on the second conductivity type layer 39 which is the outermost layer. p-side electrode 40
Is, for example, Ni / Pt / Au or laser / Pt / Au
Is an electrode layer having a laminated structure of, and is formed by a vapor deposition method or the like.

As shown in FIG. 5, after the p-side electrode 40 is formed, the main surface of the substrate 30 is separated by reactive ion etching or dicer to form an element separation groove 41.
The elements are separated on the substrate 30. For example, when the element isolation trench is formed by reactive ion etching, a silicon oxide film or the like serving as a protective film for preventing erosion due to dry etching is formed over the entire surface of the crystal layer by a plasma CVD method or the like, and then reactive ion etching is performed. The element isolation groove 4 is formed by etching and removing the protective film with acid.
1 is formed.

Next, using an excimer laser or a YAG laser, a region to be an element portion is peeled off from the substrate 30. When laser is irradiated from the back surface of the substrate 30, the interface between the underlying growth layer 31 and the substrate 30 is separated. Then, ablation occurs and the crystal layer can be separated from the substrate 30.
For example, when the substrate 30 is a sapphire substrate and the underlying growth layer 31 is GaN, and an excimer laser is irradiated from the back surface,
GaN is decomposed into metallic gallium and nitrogen at the interface between the sapphire substrate and the GaN layer, and the GaN layer can be easily separated from the sapphire substrate.

Ti / Al / Pt / A on the back surface of the device side
Accurately deposit the u electrode (FIG. 6). This electrode functions as the n-side electrode 42 arranged on the back surface of the element. It is preferable that the n-side electrode 42 provided on the back surface of the element is provided at a corner portion so as not to block the light emitted from the back surface.
When the underlying growth layer 31 is composed of an undoped underlying growth layer and a doped underlying growth layer, the undoped underlying growth layer is removed by wet etching to form the n-side electrode 42, and then the electrode is deposited. .

Further, the semiconductor light emitting element separated for each element by the element isolation groove 41 is cleaved substantially perpendicularly to the direction of the ridgeline 35 of the stripe shape to form a cleaved surface which is a resonance surface of the semiconductor laser element. can do.

In the semiconductor light emitting device in which the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed in the vicinity of the active layer 37 as described above, the first conductivity type layer 34 is formed as in the first embodiment. Also, the impurities do not diffuse from the second conductivity type layer 39 to the active layer 37, and the deterioration of the active layer 37 can be prevented without lowering the crystal quality of the active layer 37. Furthermore, since it is possible to prevent the diffusion of impurities into the active layer 37, it is possible to improve the luminous efficiency of the semiconductor light emitting device by doping more impurities into the first conductivity type layer 34 and the second conductivity type layer 39. You can

[0065]

In the semiconductor light emitting device of the present invention, the active layer is formed in a plane parallel to the tilted crystal plane and has good crystallinity and a large effective area, so that the luminous efficiency is high, but it is formed close to the active layer. Since the impurity is prevented from diffusing from the conductivity type layer to the active layer by the undoped crystal layer, it is possible to dope the conductivity type layer with more impurities and further improve the light emission efficiency. Furthermore, when the undoped crystal layer is formed in the vicinity of the active layer, the unevenness of brightness due to the unevenness of the leak current or the unevenness of the film thickness caused by the diffusion of impurities at the interface between the active layer and the conductivity type layer and the unevenness of the impurity concentration is caused. It is possible to avoid this, and it is possible to form a semiconductor light emitting device having a long life and excellent light emitting characteristics. Further, since it is possible to avoid the leakage current and the unevenness of brightness in this way, it is possible to efficiently form a semiconductor light emitting element having a low design allowance, a long life, and good reproducibility.

[Brief description of drawings]

FIG. 1 is a process perspective view showing formation of a mask layer and an opening in a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a process perspective view showing formation of a first conductivity type layer in a process of manufacturing a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 3 is a process perspective view showing formation of an undoped crystal layer, an active layer, and a second conductivity type layer in the manufacturing process of the semiconductor light emitting device of the embodiment of the present invention.

FIG. 4 is a process perspective view showing the formation of the p-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 5 is a process perspective view showing the formation of device isolation trenches in the process of manufacturing the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 6 is a process perspective view showing the formation of an n-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 7 is a process perspective view showing formation of a mask layer and an opening in a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 8 is a process perspective view showing formation of a first conductivity type layer in a manufacturing process of the semiconductor light emitting device of the embodiment of the present invention.

FIG. 9 is a process perspective view showing formation of an undoped crystal layer, an active layer, and a second conductivity type layer in a manufacturing process of the semiconductor light emitting device of the embodiment of the present invention.

FIG. 10 is a process perspective view showing the formation of the p-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 11 is a process perspective view showing formation of an element isolation groove in a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 12 is a process perspective view showing the formation of an n-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

[Explanation of symbols]

10,30 substrate 11,31 Undergrowth layer 12,32 Mask layer 13,33 opening 14, 34 First conductivity type layer 15,36 Lower undoped crystal layer 16,37 Active layer 17.38 Upper undoped crystal layer 18,39 Second conductivity type layer 19,40 p-side electrode 20,41 Element isolation groove 21, 42 n-side electrode 35 ridge

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masato Doi             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Toyoji Ohata             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 5F041 AA03 AA44 CA05 CA40 CA46                       CA65 CA74 CA75 CA76                 5F045 AA04 AB09 AB14 AB17 AF02                       AF04 AF09 CA09 DA52 DA57                       DA61 DB02

Claims (25)

[Claims] 1. A first-conductivity-type layer and an active layer, wherein a crystal layer having a tilted crystal plane tilted with respect to a main surface of the substrate is formed on a substrate and extending in a plane parallel to the tilted crystal plane. And a second conductivity type layer is formed on the crystal layer, and an undoped crystal layer extending in a plane parallel to the inclined crystal plane is formed on the crystal layer close to the active layer. Semiconductor light emitting device. 2. The semiconductor light emitting device according to claim 1, wherein the crystal layer is a wurtzite type compound semiconductor layer. 3. The semiconductor light emitting device according to claim 2, wherein the wurtzite compound semiconductor layer is a nitride compound semiconductor layer. 4. The semiconductor light emitting device according to claim 1, wherein the crystal layer is formed by selective growth on the substrate via an underlayer growth layer. 5. The semiconductor light emitting device according to claim 4, wherein the selective growth is performed using an opening of a mask layer that is selectively formed. 6. The semiconductor light emitting device according to claim 4, wherein the selective growth is performed with the crystal layer spreading laterally beyond the opening. 7. The semiconductor light emitting device according to claim 1, wherein the main surface of the substrate is a C surface. 8. The tilted crystal planes are S-plane and (11-2
2. The semiconductor light emitting device according to claim 1, comprising at least one of the 2) planes. 9. The semiconductor light emitting device according to claim 1, wherein the crystal layer has a hexagonal pyramid shape or a triangular stripe shape. 10. The ridgeline of the triangular stripe shape is [1
The semiconductor light emitting device according to claim 9, wherein the semiconductor light emitting device has a −100] direction or a [11-20] direction. 11. The semiconductor light emitting device according to claim 1, wherein the second conductivity type layer is doped with magnesium, zinc, or beryllium. 12. The undoped crystal layer is 10 Å or more 1
The semiconductor light emitting device according to claim 1, having a thickness of 00 nm or less. 13. A step of forming a mask layer or a crystal seed layer having an opening on a substrate, and a crystal layer having a tilted crystal plane inclined from the opening or the crystal seed layer with respect to the main surface of the substrate. And a step of forming a first conductivity type layer extending in a plane parallel to the tilted crystal plane, an active layer, and a second conductivity type layer in the crystal layer,
And a step of forming an undoped crystal layer extending in a plane parallel to the tilted crystal plane in the crystal layer in the vicinity of the active layer. 14. The method for manufacturing a semiconductor light emitting device according to claim 13, wherein the crystal layer is a wurtzite type compound semiconductor layer. 15. The wurtzite compound semiconductor layer is a nitride-based compound semiconductor layer.
A method for manufacturing a semiconductor light emitting device as described above. 16. The method of manufacturing a semiconductor light emitting device according to claim 13, wherein the crystal layer is formed on the substrate via an underlayer growth layer. 17. The method for manufacturing a semiconductor light emitting device according to claim 13, wherein the crystal layer is grown so as to spread laterally beyond the opening. 18. The method of manufacturing a semiconductor light emitting device according to claim 13, wherein the main surface of the substrate is a C surface. 19. The tilted crystal planes are S-plane and (11-2
14. The method for manufacturing a semiconductor light emitting device according to claim 13, further comprising at least one of 2) planes. 20. The method of manufacturing a semiconductor light emitting device according to claim 13, wherein the crystal layer has a hexagonal pyramid shape or a triangular stripe shape. 21. The ridgeline of the triangular stripe shape is [1
21. The method for manufacturing a semiconductor light emitting device according to claim 20, wherein the direction is [-100] direction or [11-20] direction. 22. The method of claim 13, wherein the second conductivity type layer is doped with magnesium, zinc, or beryllium. 23. The undoped crystal layer is 10 Å or more 1
14. The thickness is 00 nm or less.
A method for manufacturing a semiconductor light emitting device as described above. 24. The method of manufacturing a semiconductor light emitting device according to claim 13, wherein a plurality of semiconductor light emitting devices are formed on the substrate and then separated for each semiconductor light emitting device. 25. The method for manufacturing a semiconductor light emitting device according to claim 24, wherein one electrode is formed on the back surface of the separated semiconductor light emitting device.