TWI628810B - Light emitting element and method of manufacturing light emitting element - Google Patents

Abstract

The invention provides a light-emitting element and a method for manufacturing the light-emitting element, having a window layer and supporting substrate and a light-emitting portion provided on the window layer and supporting substrate, the light-emitting portion includes a second semiconductor layer, an active layer and a first semiconductor layer in sequence Wherein the light-emitting element has a removed portion that removes the light-emitting portion, a non-removed portion other than the removed portion, a first ohmic electrode provided on the first semiconductor layer of the non-removed portion, and a window layer provided on the removed portion and a supporting substrate The second ohmic electrode, at least a part of the surface of the first semiconductor layer and the side surface of the light-emitting portion is covered with an insulating protective film, and the surface except the outer peripheral portion of the first semiconductor layer and the surface of the window layer and supporting substrate are roughened , And the Rz on the side of the light-emitting part is less than 2 μm. This suppresses the occurrence of poor leakage or ESD.

Description

Light emitting element and method of manufacturing light emitting element

The invention relates to a light-emitting element and a method for manufacturing the light-emitting element, in particular to forming a first semiconductor layer, an active layer, a second semiconductor layer, and a window layer as well as a supporting substrate by epitaxial growth After removing the substrate, the structure and manufacturing method when the rough surface treatment is applied to the light-emitting element substrate on which the electrode is formed.

In recent years, light-emitting diodes (LEDs) have advanced toward higher efficiency, and are gradually applied to lighting equipment. The conventional lighting equipment is almost a combination of InGaN blue LED and phosphor. However, when using a phosphor, it is impossible to avoid the occurrence of Stokes loss in principle, so there is a problem that it is impossible to convert all the light received by the phosphor to other wavelengths. This problem is particularly noticeable in the range of yellow and red, which are relatively long blue and relatively blue.

In order to solve this problem, the technology adopted in recent years is a combination of yellow or red LEDs and blue LEDs. At this time, instead of taking out light on one side like a COB (chip on board) type, it is gradually becoming a light bulb type lighting device in which LEDs are arranged side by side on a board and emit light in a wire type. The LED element used in this type of equipment needs to be expanded and the entire wire to extract light, so it is not suitable for the type of light extraction from one side of the element. The ideal element is a light distribution with light extracted from the global surface of the chip .

InGaN-based LEDs, which are generally blue LEDs, use a sapphire substrate. Since the sapphire substrate is transparent with respect to the emission wavelength, it exhibits an ideal shape for the aforementioned lighting device. However, in yellow or red LEDs, GaAs or Ge, which will become the light absorbing substrate for the light emission wavelength, as the starting substrate, are not suitable for the aforementioned uses.

In order to solve this problem, there is disclosed a method of bonding a transparent substrate to a light-emitting portion as in Patent Document 1, and disclosed as in Patent Document 2 that a window layer is grown to a thickness for supporting a substrate, and a starting substrate which is a light-absorbing substrate is removed And become LED technology.

In the method disclosed in Patent Document 1, a transparent substrate having a required thickness or more must be joined, and the substrate needs to be thinned to a predetermined thickness after joining, which causes a cost increase. In addition, a substrate generally used for bonding has a thickness of 200 μm or more. The required film thickness of the LED element, considering the light distribution characteristics and the assembly with other elements, is at most about 100 μm, so it must be thinned to such a thickness. In thin-film processing, the number of working hours increases due to processing, and the risk of wafer breakage also increases, which becomes a major cause of increased costs and decreased productivity.

On the other hand, the method disclosed in Patent Document 2 that grows through crystal growth to a window layer that can be used as a support substrate as a support substrate only needs to grow the window layer to a desired thickness, and There is no need to perform the steps of thinning, substrate bonding, and adhesion, so it can be formed at low cost, which is an excellent method.

In addition, in the light-emitting element having the above-mentioned transparent support substrate, a general approach is to prevent multiple reflections inside the light-emitting element and improve the light-emitting efficiency by suppressing light absorption. Patent Document 3 proposes that in a structure in which a thick window layer and current diffusion layer and a thick window layer and support substrate sandwich the light emitting portion, the window layer and current diffusion layer and the window layer and support substrate are roughened No roughening method is applied to the light emitting part. However, this method must form a deep trench penetrating the window layer and the current diffusion layer. This method not only increases the cost, but also makes it difficult to perform wire bonding because the difference in height between the upper and lower electrodes is too large. Even when applied to the flip-chip type, it is necessary to form a thick insulating film and a very long metal via, which causes a rise in cost. Therefore, it is desirable that the window layer and current diffusion layer of the upper electrode portion be thin.

Patent Documents 4 and 5 can be cited as disclosed technologies in which the thickness of the window layer and current diffusion layer is thin, the height difference between the upper electrode portion and the lower electrode portion is small, and the light extraction portion or the light reflection portion has a rough surface. In Patent Document 4, although a rough surface is formed on the surface of the n-type semiconductor layer on the light extraction surface side and the opposite side, it is a disclosure of the flip-chip technology, and the efficient reflection of light from the electrode side to the window layer side is purpose. In addition, it is also disclosed that it is difficult to roughen both the window layer and the supporting substrate and the light emitting section.

Patent Document 5 discloses a technique of roughening the surface of the light-emitting portion and having a platform shape with a different angle or a simple platform shape on the side surface of the light-emitting portion. In this case, the substrate adopts a reflective structure that does not require a rough surface. In addition, there is disclosed a technique of forming irregularities such as a 2 μm period on the surface of the light-emitting portion by the lithography method.

On the other hand, in the case where the window layer and the supporting substrate are formed by epitaxial growth, the substrate has a large warpage due to the lattice mismatch, even if the contact exposure method is used to form a pitch of 2 μm or less on the surface of the light emitting portion by the lithography Uniform patterns are also extremely difficult. Therefore, in the case where the window layer and the support substrate are formed by epitaxial growth, the roughening of the surface of the light-emitting part is performed by the roughening liquid.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5427585.

[Patent Document 2] Japanese Patent No. 4569858

[Patent Document 3] Japanese Patent No. 4715370

[Patent Document 4] Japanese Patent Application Publication No. 2007-059518

[Patent Document 5] Japanese Patent Laid-Open No. 2011-198992

However, in the case where the surface of the light-emitting portion is roughened with the roughening liquid and the device is separated, the shape of the side surface of the light-emitting portion where the element has been separated is a shape reflecting the unevenness of the surface of the roughened light-emitting portion. This is because in the element separation, the etching of the light emitting portion ends earlier due to the thinner concave portion and reaches the window layer and support substrate portion, and the convex portion reaches the window layer and support substrate portion later due to the thickness. Therefore, during the etching of the convex portion, the concave portion over-etches the light emitting portion, resulting in the formation of irregularities in the projection view of the etching direction of the side surface of the light emitting portion. In this way, after roughening the surface of the light-emitting portion with the roughening liquid, under the condition of element separation, the electric field in the shape of the side surface of the light-emitting portion separated by the element tends to be concentrated on the convex portion, so that leakage leakage or ESD may occur. Electrostatic discharge) bad problem.

In view of the above problems, an object of the present invention is to provide a light-emitting element and a method for manufacturing the light-emitting element, which has a window layer and a supporting substrate and a light-emitting portion, after roughening the light-emitting portion with a roughening liquid, and then performing light emission after element separation The device can suppress the occurrence of poor leakage or ESD.

In order to achieve the above object, the present invention provides a light-emitting device having a window layer and supporting substrate and a light-emitting portion disposed on the window layer and supporting substrate, the light-emitting portion sequentially includes a first type of second conductivity type Two semiconductor layers, an active layer, and a first semiconductor layer of the first conductivity type, wherein the light emitting element has a removed portion from which the light emitting portion is removed, a non-removed portion other than the removed portion, and is provided on the non-removed portion A first ohmic electrode on the first semiconductor layer of the portion, and a second ohmic electrode on the support layer and the window layer provided in the removed portion, and the surface of the first semiconductor layer and the side surface of the light emitting portion At least a part of it is covered with an insulating protective film, the surface except the outer peripheral portion of the first semiconductor layer and the surface of the window layer and supporting substrate are roughened, and the R _{Z on the} side of the light emitting portion is not Full 2μm.

With such a light-emitting element, it is possible to improve the light-emitting efficiency by roughening, and at the same time, it is possible to realize a light-emitting element that suppresses the occurrence of leakage defects and ESD defects depending on the uneven shape of the side surface of the light-emitting portion.

At this time, preferably, the window layer and supporting substrate are made of any one of GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), and SiC. The first semiconductor layer, The active layer and the second semiconductor layer are composed of AlGaInP or AlGaAs.

In this way, as the window layer and supporting substrate, the first semiconductor layer, the active layer, and the second semiconductor layer, the above-mentioned materials can be suitably used.

In addition, a method for manufacturing a light-emitting device provided by the present invention includes: a step of forming a light-emitting part on a substrate, and a material that is a lattice matching system with the substrate is sequentially grown by epitaxial growth to a first The semiconductor layer, an active layer, and a second semiconductor layer form a light-emitting portion; the window layer also supports the substrate forming step, which is formed on the light-emitting portion to make the substrate an amorphous matching system by epitaxial growth Forming a window layer and supporting substrate; the removal step is to remove the substrate; the first ohmic electrode forming step is to form a first ohmic electrode on the surface of the first semiconductor layer; the first rough surface treatment step is to The surface of the first semiconductor layer is roughened; the element separation step is to form a removed part and a non-removed part other than a part of the light emitting part; the second ohmic electrode forming step is to remove the light emitting part Forming a second ohmic electrode on the window layer and supporting substrate; the covering step is to cover at least a part of the surface of the first semiconductor layer and the side surface of the light emitting part with an insulating protective film; and the second roughening surface treatment step is to roughen The window layer also supports the surface and the side surface of the substrate, wherein in the first rough surface processing step, the first semiconductor that does not roughen the periphery of the first ohmic electrode and becomes the non-removed portion in the element separation step thereafter The area of the outer periphery of the layer surface.

According to this manufacturing method, the light emitting efficiency can be improved by roughening, and at the same time, a light-emitting element in which the occurrence of poor leakage or ESD defects depending on the uneven shape of the side surface of the light-emitting part can be manufactured.

At this time, preferably, the substrate is GaAs or Ge, and the window layer and supporting substrate is any one of GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), SiC, and The first semiconductor layer, the active layer, and the second semiconductor layer are AlGaInP or AlGaAs.

In this way, as the substrate, the window layer and supporting substrate, the first semiconductor layer, the active layer, and the second semiconductor layer, the above-mentioned materials can be suitably used.

At this time, preferably, the first rough surface processing step, It is carried out using a mixture of organic acids and inorganic acids, the organic acids include: any one or more of citric acid, malonic acid, formic acid, acetic acid, and tartaric acid, the inorganic acids include: hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid Any one or more of; and in the second rough surface treatment step, any one or more of organic acids including citric acid, malonic acid, formic acid, acetic acid, and tartaric acid are used, and include: hydrochloric acid, sulfuric acid, nitric acid, and Hydrofluoric acid is carried out in any one or more of inorganic acids and a solution containing iodine.

In this way, the surface can be reliably roughened.

At this time, the element separation step can be performed by a wet etching method including a wet etching solution of hydrochloric acid, and in the first rough surface treatment step, the non-Al-containing layer is left in the unroughened area as Etching mask used.

In this way, a clear platform shape can be obtained on the side surface of the light-emitting part subjected to element separation.

At this time, preferably, the non-Al-containing layer includes any one or more of GaAs, InGaP, InGaAs, and Ge, and the step of removing the non-Al-containing layer is performed after the wet etching.

In this way, a clear platform shape can be more surely obtained on the side surface of the light-emitting portion where the elements are separated.

In addition, this element separation step can be performed by a dry etching method including a gas containing hydrogen chloride.

In this way, a non-shrinking shape can be obtained on the side surface of the light-emitting part subjected to element separation.

The light-emitting element and the method of manufacturing the light-emitting element of the present invention can improve the luminous efficiency by roughening, and at the same time, a light-emitting element that suppresses the occurrence of poor leakage or ESD failure depending on the uneven shape of the side surface of the light-emitting portion.

1‧‧‧Lighting element

103‧‧‧First semiconductor layer

104‧‧‧active layer

105‧‧‧Second semiconductor layer

106‧‧‧buffer layer

107‧‧‧Window layer and supporting substrate

108‧‧‧Lighting Department

109‧‧‧ epitaxial substrate

110‧‧‧Light-emitting element substrate

121‧‧‧The first ohmic electrode

122‧‧‧The second ohmic electrode

130‧‧‧ third area

131‧‧‧ Second area

150‧‧‧Insulation protective film

160‧‧‧Part separation line

170‧‧‧Removed

180‧‧‧non-removed department

[Figure 1] is a schematic view showing an example of the light-emitting element of the present invention.

[FIG. 2] A step diagram showing an example of a method of manufacturing a light-emitting element of the present invention.

[FIG. 3] A schematic diagram showing that the light-emitting portion and the window layer and supporting substrate on the substrate have grown into an epitaxial substrate during the manufacturing process of the method for manufacturing a light-emitting element of the present invention.

[FIG. 4] is a schematic view showing a light-emitting element substrate from the epitaxial substrate through the removal of the substrate in the manufacturing process of the method of manufacturing the light-emitting element of the present invention.

[FIG. 5] This is a schematic view of the light-emitting element substrate in which the first ohmic electrode is formed during the manufacturing process of the light-emitting element manufacturing method of the present invention.

[FIG. 6] is a schematic view of a light-emitting element substrate subjected to a first rough surface treatment in the manufacturing process of the method of manufacturing a light-emitting element of the present invention.

[Figure 7] This is a schematic view of a light-emitting element substrate that has undergone an element separation step in the manufacturing process of the method of manufacturing a light-emitting element of the present invention.

[FIG. 8] A schematic diagram showing a light-emitting element substrate in which a second ohmic electrode is formed and an insulating protective film is formed in the manufacturing process of the light-emitting element manufacturing method of the present invention.

[FIG. 9] is a schematic diagram of a light-emitting element of Example 1.

[Figure 10] is a schematic diagram of a light-emitting element of Example 2.

[Figure 11] is a photograph of the element separation end in Example 1.

[Figure 12] is a photograph of the element separation end in the comparative example.

[FIG. 13] A schematic diagram showing the frequency of the reverse voltage (VR) of the light-emitting elements in Examples and Comparative Examples.

[Fig. 14] is a schematic diagram showing the relationship between the ESD voltage and the ESD defect rate of the light-emitting elements in Examples and Comparative Examples.

[FIG. 15] A schematic diagram showing the relationship between R _z on the side surface of the light-emitting part and the VR defect rate in the experiment.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

As described above, after roughening the surface of the light-emitting portion with the roughening liquid and then performing element separation, there may be a problem of poor electric leakage or defective ESD.

Therefore, the inventors of the present application conducted in-depth research in order to solve such problems. As a result, it was found that when roughening the surface of the light emitting portion, by not roughening the area that becomes the outer peripheral portion of the surface of the first semiconductor layer in the subsequent element separation, the R _z of the side surface of the light emitting portion can be less than 2 μm. In this way, it is possible to suppress poor leakage or poor ESD. In addition, a detailed investigation was conducted on the best type for implementing these contents, thereby completing the present invention.

First, the light-emitting element of the present invention will be described with reference to FIG.

As shown in FIG. 1, the light-emitting element 1 of the present invention has a window layer and support substrate 107 and a light-emitting portion 108 provided on the window layer and support substrate 107. The light-emitting portion 108 includes A second semiconductor layer 105 of two conductivity types and an active layer 104 are a first semiconductor layer 103 of the first conductivity type.

The window layer and support substrate 107 can be composed of GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), SiC, etc., and can make the first semiconductor layer 103, the active layer 104, the second semiconductor layer 105 is composed of AlGaInP or AlGaAs.

The light-emitting element 1 has at least a first semiconductor layer 103 and a removed portion 170 of the active layer 104 from which the light-emitting portion 108 is removed, a non-removed portion 180 other than the removed portion 170, and is provided on the non-removed portion A first ohmic electrode 121 on the first semiconductor layer 103 of 180, and a second ohmic electrode 122 on the supporting layer 107 of the window layer provided in the removed portion 170.

At least a part of the surface of the first semiconductor layer 103 and the side surface of the light emitting portion 108 is covered with an insulating protective film 150, except for the surface except the outer peripheral portion (second area 131) of the first semiconductor layer 103 and the The surface of the window layer and support substrate 107 is roughened, and the R _z of the side surface of the light emitting portion 108 is less than 2 μm.

In addition, R _{z in} this application is defined by the average height of 10 points (JIS B0601-1994) which shows the surface.

According to the light-emitting element 1 of the present invention, while the luminous efficiency is improved by roughening, and the R _z of the side surface of the light-emitting portion 108 is less than 2 μm, it is possible to cause the occurrence of electrical leakage defects and ESD defects depending on the uneven shape A suppressed light-emitting element is obtained.

Next, the method of manufacturing the light-emitting element of the present invention will be described with reference to FIGS. 2 to 8.

First, as the starting substrate shown in FIG. 3, a substrate 101 (SP1 in FIG. 2) is prepared.

As the substrate 101, GaAs or Ge can be suitably used.

In this way, since the material of the active layer 104 described later can be epitaxially grown in a lattice matching system, the quality of the active layer 104 can be easily improved, and the brightness or life characteristics can be improved.

Next, on the substrate 101, the first semiconductor layer 103 of the first conductivity type, the active layer 104, and the second conductivity type that have different lattice constants from the substrate 101 are sequentially grown by epitaxial growth The second semiconductor layer 105 to form a light emitting portion 108 (SP2 in FIG. 2).

In addition, although not shown, it is preferable to insert a substrate to remove the selective etching layer between the substrate 101 and the first semiconductor layer 103 for the step of removing the substrate 101 described later.

Next, an epitaxial substrate 109 (SP3 in FIG. 2) is produced by forming a window layer and supporting substrate 107 by epitaxial growth on the light-emitting portion 108 using an epitaxial growth material for the substrate 101.

In SP2 and 3 above, specifically, as shown in FIG. 3, for example, MOVPE (organometal vapor phase epitaxy), MBE (molecular beam epitaxy), CBE (chemical beam) Epitaxial method) and a buffer layer is formed on the light-emitting portion 108 composed of the first semiconductor layer 103 of the first conductivity type, the active layer 104, and the second semiconductor layer 105 of the second conductivity type 106. An epitaxial substrate 109 in which the window layer also supports the epitaxial growth of the substrate 107 in sequence.

In addition, the window layer and support substrate 107 may also be formed by the HVPE method (hydride vapor phase growth method).

The active layer 104 is based on (Al _x Ga _1-x ) _y In _1-y P (0 <x ≦ 1, 0.4 ≦ y ≦ 0.6) or Al _z Ga _1-z As (0 ≦ z ≦ 0.45) ) To be formed. It is suitable for the selection of AlGaInP in the case of visible light illumination and AlGaAs in the case of infrared illumination. However, the design of the active layer 104 can be adjusted beyond the wavelength due to the material composition by using a superlattice or the like, so it is not limited to the above-mentioned materials.

The first semiconductor layer 103 and the second semiconductor layer 105 can be selected from AlGaInP or AlGaAs, and this selection does not necessarily need to be the same material as the active layer 104.

In this embodiment, the case where the first semiconductor layer 103, the active layer 104, and the second semiconductor layer 105 of the simplest structure are all made of the same material AlGaInP is taken as an example. In order to enhance the first semiconductor layer 103 or For the characteristics of the second semiconductor layer 105, each layer generally includes a plurality of layers. The first semiconductor layer 103 or the second semiconductor layer 105 is not limited to a single layer.

As the window layer and support substrate 107, GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), SiC, or the like can be suitably used. In the case where the window layer and support substrate 107 are formed with GaAsP or GaP, it is most suitable to form the buffer layer 106 with InGaP.

In addition, the window layer and support substrate 107 can also be formed of AlGaAs which is a lattice-matching material. In addition, as the window layer and support substrate 107, if GaAsP is selected, the weather resistance is good.

However, due to the large lattice mismatch between GaAsP and AlGaInP-based materials or AlGaAs-based materials, GaAsP will infiltrate high-density strain or penetrating differentials. As a result, the epitaxial substrate 109 has large warpage.

Here, preferably, in order to prevent the wavelength drift caused by the formation of the natural superlattice, the light emitting portion 108 is grown with a crystallographic tilt of 12 degrees or more relative to the growth surface. Although any direction can be selected for this oblique direction, in the case where the separation element step is adopted as the scribe line splitting step, if one side of the scribe line selects the direction where the crystal axis intersects perpendicularly without being inclined, and the other side of the scribe line Choosing the direction in which the crystal axis is inclined can reduce the inclination of the side surface of the device relative to the surface and inner surface of the device. Therefore, although the side of the scribe line generally chooses a direction that does not incline, the inclination of the side surface of the component around 20 degrees will not cause too much problem in assembly. Therefore, the above vertical intersection direction does not need to be closely aligned, and an angle range of about ± 20 degrees from the vertical intersection direction is included in the conceptual vertical intersection direction.

Next, the substrate 101 is removed from the epitaxial substrate 109 to fabricate the light-emitting element substrate 110 shown in FIG. 4 (SP4 in FIG. 2).

Specifically, the substrate 101 can be removed from the epitaxial substrate 109 by a wet etching method to become a light-emitting element substrate 110.

Next, as shown in FIG. 5, on the substrate-removed surface 120 of the first semiconductor layer 103 of the light-emitting element substrate 110, a first ohmic electrode 121 (SP5 in FIG. 2) that supplies a potential to the light-emitting element is formed.

Next, the first rough surface treatment step (SP6 in FIG. 2) of performing rough surface treatment on the surface of the first semiconductor layer 103 as shown in FIG. 6 is performed. In the first rough surface processing step, the third region 130 around the first ohmic electrode 121 and the second region 131 which is a part of the surface of the first semiconductor layer 103 are not roughened.

The first rough surface treatment step is carried out using a mixture of organic and inorganic acids. The organic acid can contain carboxylic acids, especially citric acid, malonic acid, formic acid, acetic acid and tartaric acid. Any one or more of these inorganic acids can be used including any one or more of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid.

In this way, the surface can be reliably roughened.

The third region 130 has the effects of suppressing over-etching and electrode peeling of the first ohmic electrode 121 in the first rough surface processing step. On the other hand, in order not to reduce the reflection prevention effect due to the roughening effect, the width of the third region 130 must be set to an appropriate width that is not too wide. As the width of the anti-reflection effect that is less reduced and the effect of suppressing the peeling of the electrode can be obtained, a width of about 0.5 to 15 times the depth roughened by the first rough surface treatment is more suitable. Preferably, the roughness of the rough surface is an integral multiple of 1/2 of the emission wavelength.

The width of the second region 131 is preferably about 0.5 to 15 times the depth roughened by the first rough surface treatment.

Here, in a state where the aforementioned substrate removal selective etching layer is provided on the first semiconductor layer 103, a first rough surface treatment selective etching layer is provided between the substrate removal selective etching layer and the first semiconductor layer 103 ( (Not shown) is preferred. In this way, after the substrate is removed, the first rough surface treatment selective etching layer remains in the second region 131 to perform the first rough surface treatment. In this way, overetching under the photoresist pattern can be reduced in the first rough surface processing step.

Since the first roughening liquid has selective etching properties for a layer composed of a non-Al-containing material, it is preferable that the first rough surface treatment selective etching layer is composed of GaAs, InGaP, InGaAs, and Ge. In this way, using the first rough surface treatment selective etching layer end as a starting point to form a facet can suppress over-etching under the pattern. However, in the case where the etching layer is selected using the first rough surface treatment, since the non-Al-containing material absorbs light at the emission wavelength, it is best to add a liquid containing hydrogen peroxide solution such as SPM after the first rough surface treatment The step of selectively removing the first rough surface and processing the selective etching layer.

The width of the second region 131 is not only limited by the depth of roughening performed by the first rough surface processing, but also by the positioning accuracy of lithography. Use locator or stepper with high alignment accuracy It is sufficient to make the additional width predicted for the alignment accuracy a little. On the other hand, in the case of using a locator with a low alignment accuracy, it is better to predict the accuracy and prepare more additional width.

By performing the above steps, an unroughened flat second region 131 can be obtained on the surface of the first semiconductor layer 103. In this way, it is possible to suppress the occurrence of unevenness on the side surface of the light-emitting portion 108 separated by the element in the element separation step described later.

Next, as shown in FIG. 7, an element separation step (SP7 in FIG. 2) of forming the removed portion 170 that removes a part of the light-emitting portion 108 and the other non-removed portion 180 is performed.

In the device isolation step, a predetermined area (the second ohmic electrode formation area 140 and the scribe line area 141 in FIG. 6) of the first semiconductor layer 103 can be patterned by photolithography, for example, by a photolithography method , This photoresist can be used as an etching mask for etching.

The above etching can be formed by a wet etching method including a wet etching solution of hydrochloric acid: the second semiconductor layer 105, the removal portion 170 that exposes the buffer layer 106 or the window layer and support substrate 107, and the non-removable portion 170 Apart from the 180.

At this time, in the first rough surface treatment step described above, a non-Al-containing layer (not shown) can be left in the unroughened second region 131 to be used as an etching mask.

The non-Al-containing layer may include any one or more of GaAs, InGaP, InGaAs, and Ge. Since the non-Al-containing layer cannot be etched with an etchant containing hydrochloric acid, a facet is formed using the end of the non-Al-containing layer as a starting point, so that a clear platform shape can be obtained on the side surface of the light-emitting portion 108 subjected to element separation. However, in the case where a non-Al-containing layer is used, after the element separation step, it is preferable to perform a step of selectively removing the non-Al-containing layer with a liquid containing hydrogen peroxide solution such as SPM (sulfuric acid / hydrogen peroxide water).

In addition, in the element isolation step, in addition to the above-mentioned wet etching method, a dry etching method can also be performed by a method using a gas containing halogen gas or preferably containing hydrogen chloride.

In this way, a shape without shrinkage (over-etching) can be obtained on the side surface of the light-emitting portion where the elements are separated.

Next, as shown in FIG. 8, a second ohmic electrode 122 (SP8 in FIG. 2) is formed on the removed portion 170 on the window layer and support substrate 107 from which the light emitting portion 108 has been removed.

Next, as shown in FIG. 8, at least a part of the surface of the first semiconductor layer 103 and the side surface of the light emitting portion 108 is covered with the insulating protective film 150 (SP9 in FIG. 2).

The insulating protective film 150 may be any material as long as it is a transparent and insulating material. As the insulating protective film 150, for example, quartz or silicon nitride can be suitably used. With such a material, the upper portions of the first ohmic electrode 121 and the second ohmic electrode 122 can be easily processed by the lithography method and the etching solution containing hydrofluoric acid.

Next, as shown in FIG. 1, a second rough surface treatment step is performed to roughen the surface and side surfaces of the window layer and support substrate 107 (SP10 in FIG. 2).

Before performing the second rough surface treatment, it is preferable to first scribe a scribe line along the removal portion 170, and separate the light emitting element by splitting to form a light emitting element crystal grain. After the light-emitting element die is formed, preferably, the light-emitting element die is transferred to a carrier tape and is located on the upper surface of the window layer and support substrate 107, and then subjected to the second rough surface treatment described below.

In the second rough surface treatment step, any one or more of organic acids including citric acid, malonic acid, formic acid, acetic acid, and tartaric acid, and any of inorganic acids including hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid can be used This is done with a solution containing iodine.

The first roughening liquid applied to the first semiconductor layer 103 used in the first rough surface processing step mentioned above, and the second roughening liquid applied to the window layer and support substrate 107 in the second rough surface processing step The chemical composition of the two liquids is different. Accordingly, since the etching characteristics different reasons, necessarily causes the first semiconductor layer 103 and the window layer and the support substrate has a shape and a rough surface 107 R _a (arithmetic mean roughness) of different things.

According to the method for manufacturing a light-emitting element of the present invention described above, by providing an unroughened second region 131 on the surface of the first semiconductor layer 103, the over-etching generated in the light-emitting portion 108 can be suppressed during the element separation step Therefore, the shape of the side surface of the light-emitting part 108 separated by the element is substantially the same as the shape of the second region 131. Therefore, since the R _z of the side surface of the light-emitting portion 108 separated by the element can be less than 2 μm, the shape of the side surface of the light-emitting portion 108 separated by the element can be prevented from being concentrated in the convex portion. In this way, it is possible to improve the luminous efficiency through roughening, and at the same time, it is possible to manufacture a light-emitting element in which the occurrence of poor leakage or ESD defects depending on the uneven shape of the side surface of the light-emitting portion is suppressed.

[Examples]

Hereinafter, Examples and Comparative Examples of the present invention will be shown to explain the present invention more specifically, but the present invention is not limited thereto.

<Example 1>

The n-type GaAs buffer layer (not shown) is grown by 0.5 μm on the n-type GaAs substrate 101 with a thickness of 280 μm and the crystal axis is inclined by 15 ° from the [001] direction to the [110] direction, and the selective etching layer is removed from the n-type AlInP substrate (Not shown) After growing 1 μm, an n-type cladding layer (first semiconductor layer 103) composed of AlGaInp, an active layer 104, and a p-type cladding layer (second semiconductor layer 105) are formed by the MOVPE method The light-emitting portion 108 of 6.5 μm is further formed with a buffer layer 106 of 0.3 μm composed of p-type InGaP and a layer of 1 μm composed of p-type GaP as a part of the GaP window layer and support substrate 107. Next, it moved to an HVPE furnace to grow a window layer and support substrate 107 composed of p-type GaP by 120 μm to obtain an epitaxial substrate 109 (refer to FIG. 3).

Next, the GaAs substrate 101, the GaAs buffer layer, and the n-type AlInP substrate are removed, and the selective etching layer is removed to produce a light-emitting element substrate 110 (refer to FIG. 4).

Next, the first ohmic electrode 121 is formed on the substrate-removed surface 120 of the first semiconductor layer 103 of the light-emitting element substrate 110 (refer to FIG. 5), and is formed by photolithography to cover the third region 130 with a photoresist And the pattern of the second area 131. As shown in FIG. 9, the third region 130 is along the first ohm For the electrode, the second region 131 is provided along the line 160 for separating the elements. The width of the third region 130 is set to 2 μm which is four times the etching depth. In addition, the width of the second region 131 is set to 6 μm.

Next, a first rough surface treatment step is performed on the surface of the first semiconductor layer 103 (refer to FIG. 6). The first roughening solution is made of a mixed solution of acetic acid and hydrochloric acid, and is etched at room temperature for 1 minute to achieve rough surface treatment.

Next, the area other than the second ohmic electrode formation region 140 and the split region 141 (refer to FIG. 6) is covered with a photoresist by a photolithography method, and implemented by a wet etching method including a wet etching solution containing hydrochloric acid In the element isolation step, the removed portion 170 that removes the light-emitting portion 108 to expose the window layer and support substrate 107 and the other non-removed portion 180 (see FIG. 7) are formed.

As a result of performing the above steps, the R _z of the side surface of the light-emitting part subjected to element separation is displayed at about 0.5 μm according to the accuracy of the photoresist pattern.

Next, the second ohmic electrode 122 is formed in the removed portion 170 (refer to FIG. 8). Next, an insulating protective film 150 made of quartz is laminated, and the surface of the first semiconductor layer 103 and the side surface of the light emitting portion 108 are covered with the insulating protective film 150. In addition, the first ohmic electrode 121 and the second ohmic electrode 122 are formed with an opening in the insulating protective film 150 by lithography and hydrofluoric acid etching.

Next, a scribe line is scribed along the exposed removal portion 170, a crack line is extended along the scribe line, and then the device is separated by dicing to form a light-emitting element crystal grain.

After the light-emitting element die is formed, the element die is transferred to the carrier tape so that the surface on which the first ohmic electrode is provided is located on the side close to the tape surface, and then the second rough surface treatment step is performed. The roughening liquid used for roughening the window layer and supporting substrate in the second rough surface treatment step is prepared from a mixed liquid of acetic acid, hydrofluoric acid, and iodine. Then, the second rough surface treatment is performed by etching at room temperature for 1 minute.

The light-emitting element shown in FIG. 9 was produced by the method described above.

FIG. 11 is a photograph showing the end of the element separation portion in Example 1. FIG. It can be seen from FIG. 11 that it shows a state where the end of the second region 131 is formed in a straight line.

A light bulb was produced using the light-emitting element prepared above, and the measurement and evaluation were performed.

The light bulb fabricated with the light-emitting element manufactured in Example 1 shows the reverse voltage (VR) result when the current value is 10 μA in the reverse direction, as shown in FIG. 13. In addition, FIG. 13 also shows the results of Example 2 and Comparative Examples described later.

As a result, as shown in FIG. 13, in the case of the bulb manufactured in Example 1 and Example 2 described later, under the condition that the reverse applied current value is 10 μA, VR must be at least 30 V, and the VR value is displayed in A bulb full of 30V did not happen. On the other hand, about half of the VR values of the bulbs produced in the comparative examples described below are shown to be less than 30V. In this way, it is known that the light-emitting device of the present invention has excellent reverse voltage characteristics due to the presence of the second region.

Next, the light bulb manufactured using the light-emitting element manufactured in Example 1 was used, and the result of ESD inspection is shown in FIG. 14. ESD implementation conditions are based on HBM (Human Body Model). In addition, the results of Example 2 and Comparative Examples described later are collectively shown in FIG. 14.

As a result, as shown in FIG. 14, the bulbs produced in Example 1 and Example 2 described below did not undergo ESD damage during ESD inspection up to 2000V. On the other hand, in the comparative example described later, ESD destruction occurs at an ESD voltage of about 100V, and all components put into inspection before 600V have been destroyed by ESD.

<Example 2>

First, as in Example 1, proceed to the first rough surface treatment step.

Next, in order to perform a dry etching method, the first semiconductor layer and the first ohmic electrode are covered with a quartz film to 300 nm, and a photoresist pattern with a predetermined shape for device separation is formed by a lithography method. Next, the opening of the pattern is etched by hydrofluoric acid.

In addition, a dry etching method is performed using a quartz film having an opening pattern as an etching mask. During dry etching, element separation is performed by the RIE method or the ICP method in which a gas containing chlorine is introduced, and the light-emitting portion is removed to form a removal portion that exposes the window layer and supports the substrate.

As a result of performing the above steps, the R _z system on the side surface of the light-emitting part that has undergone element separation is displayed at about 0.5 μm in accordance with the pattern accuracy of the quartz cover.

Thereafter, in the same way as in Example 1, the steps from the formation of the second ohmic electrode to the second rough surface were performed to manufacture the light-emitting element shown in FIG. 10.

The light-emitting element produced in the above steps was used to produce a light bulb, and measurement and evaluation were performed.

The result of the reverse voltage (VR) of the light bulb fabricated with the light-emitting element manufactured in Example 2 when the current value is 10 μA in the reverse direction is shown in FIG. 13.

As a result, as shown in FIG. 13, in the case of the bulb manufactured in Example 2, when the reverse applied current value is 10 μA, VR must be 30 V or more, and a bulb with a VR value less than 30 V does not occur. From this, it is known that the light-emitting device of the present invention has excellent reverse voltage characteristics due to the presence of the second region.

Next, using the light-emitting device manufactured in Example 2, the light bulb produced and the results of ESD inspection are shown in FIG. 14. ESD implementation conditions are based on HBM (Human Body Model).

As a result, as shown in FIG. 14, the bulb manufactured in Example 2 did not undergo ESD damage in the ESD inspection up to 2000V.

<Comparative example>

In the first rough surface treatment step, except that the second region was not provided, the same light-emitting element as in Example 1 was manufactured.

As a result, the unevenness (before and after R _z = 0.6 μm on the surface of the first semiconductor layer) generated by the first rough surface treatment in the comparative example is increased by the element separation step, so that the light-emitting portion subjected to element separation The R _z on the side reaches 3 ~ 4μm.

FIG. 12 is a photograph showing the end of the element separation portion in the comparative example.

The light-emitting element produced above was used to produce a light bulb, and measurement and evaluation were performed.

The results of the reverse voltage (VR) when the current value of the light bulb produced by the light-emitting element manufactured in the comparative example was 10 μA in the reverse direction were shown in FIG. 13.

As a result, as shown in FIG. 13, it was shown that about half of the VR values of the bulbs produced in the comparative example were less than 30V.

Next, using the light-emitting element manufactured in the comparative example, the bulb was produced, and the results of ESD inspection are shown in FIG. 14. ESD implementation conditions are based on HBM (Human Body Model).

As a result, as shown in FIG. 14, the bulb manufactured in the comparative example caused ESD destruction at an ESD voltage of about 100V, and all the devices under inspection before 600V were destroyed by ESD.

<Experiment>

A plurality of light bulbs were produced in the light-emitting element manufactured by the method of Example 1, except for the mask pattern during the formation of the variable element separation step and the variation of R _z on the side surface of the light-emitting portion (Experiment 1).

A plurality of light bulbs were produced by the light-emitting element manufactured by the method of Example 2 except for the mask pattern during the formation of the variable element separation step and the variation of R _z on the side surface of the light-emitting portion (Experiment 2).

In addition, the results of the measurement of the VR defect rate when the current value of the lamp of Experiments 1 and 2 was reversely applied at 10 μA are shown in FIG. 15. In addition, when the VR value when the current is applied in the reverse direction of 10 μA is less than 30V, it is measured as a VR defect.

As a result, as shown in Fig. 15, experiments 1 and 2 together had almost no VR defects before less than 2 μm. Under the condition that R _z was 2 μm or more, it was learned that VR defects started increasing at the same time in experiments 1 and 2 .

The shape of the side surface of the light-emitting portion after element separation is almost the shape of the outer periphery of the first semiconductor layer in the element separation step, so FIG. 15 shows the unevenness of the outer periphery of the first semiconductor layer during the element separation step The larger it is, the more likely VR defects will occur.

Therefore, the R _{z on the} side of the light-emitting part must be less than 2 μm. Although Fig. 15 shows only the VR failure, the IR characteristics showing the leakage current value when the reverse bias voltage is applied also have the same tendency.

In addition, although the unevenness on the side surface of the light-emitting portion is not uniform on the side surface of the light-emitting portion, but a part of the side surface of the light-emitting element is measured with a pattern of half the amount of unevenness, the tendency of VR defects to occur is the same as the pattern composed of the same amount of unevenness The situation is the same. Therefore, it is known that the relationship between the unevenness on the side surface of the light emitting portion and the occurrence rate of the VR defect is that as long as the R _z on the side surface of the light emitting portion is 2 μm or more, the VR defect rate increases. Therefore, in order to suppress defective leakage or defective ESD, the R _{z on the} side of the light-emitting part must be less than 2 μm.

In addition, the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are examples, and those who have substantially the same structure as the technical idea described in the patent application scope of the present invention and can obtain the same effect are included. Within the technical scope of the present invention.

Claims (8)

A light-emitting element has a window layer and supporting substrate and a light-emitting portion provided on the window layer and supporting substrate, the light-emitting portion includes a second semiconductor layer, an active layer and a second conductive type in sequence It is a first semiconductor layer of the first conductivity type, wherein the light-emitting element has a removed portion from which the light-emitting portion is removed, a non-removed portion other than the removed portion, and is disposed on the first semiconductor layer of the non-removed portion A first ohmic electrode, and a second ohmic electrode on the support layer and the window layer provided in the removed portion, and at least a part of the surface of the first semiconductor layer and the side surface of the light emitting portion are Covered by an insulating protective film, the surface except the outer peripheral portion of the first semiconductor layer and the surface of the window layer and supporting substrate are roughened, and the outer peripheral portion of the first semiconductor layer is a flat surface without roughening , And R _{z on the} side surface of the light-emitting part is less than 2 μm. The light-emitting element according to claim 1, wherein the window layer and supporting substrate is composed of any one of GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), and SiC. A semiconductor layer, the active layer, and the second semiconductor layer are composed of AlGaInP or AlGaAs. A method for manufacturing a light-emitting device, comprising: a step of forming a light-emitting part on a substrate, a material of lattice matching system with the substrate is sequentially grown by epitaxial growth, a first semiconductor layer, an active layer, a The second semiconductor layer forms a light-emitting portion; the window layer and supporting substrate forming step is formed on the light-emitting portion to form an amorphous-matching material for the substrate by epitaxial growth to form a window layer and supporting substrate ; The removal step is to remove the substrate; The first ohmic electrode forming step is to form a first ohmic electrode on the surface of the first semiconductor layer; The first rough surface treatment step is to roughen the surface of the first semiconductor layer Surface treatment; the element separation step is to form a removed portion and a non-removed portion other than a part of the light-emitting portion; the second ohmic electrode forming step is formed on the window layer and supporting substrate after removing the light-emitting portion A second ohmic electrode; a covering step to cover the surface of the first semiconductor layer and at least a part of the side surface of the light-emitting portion with an insulating protective film; and a second roughness processing step to roughen the surface of the window layer and supporting substrate And a side surface, in which the periphery of the first ohmic electrode is not roughened in the first rough surface processing step and the area of the outer peripheral portion of the surface of the first semiconductor layer that becomes the non-removed portion in the element separation step thereafter. The method for manufacturing a light-emitting element according to claim 3, wherein the substrate is GaAs or Ge, and the window layer and supporting substrate are GaP, GaAsP, AlGaAs, sapphire (Al ₂ O ₃ ), quartz (SiO ₂ ), SiC Any one of them, and the first semiconductor layer, the active layer, and the second semiconductor layer are AlGaInP or AlGaAs. The method for manufacturing a light-emitting element according to claim 4, wherein the first rough surface treatment step is performed using a mixture of an organic acid and an inorganic acid, the organic acid including: citric acid, malonic acid, formic acid , Acetic acid and tartaric acid, the inorganic acid contains: any one of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid; and in the second rough surface treatment step, the system contains citric acid, malonic acid , Formic acid, acetic acid, and tartaric acid, any one or more of organic acids, and includes hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid, any one or more of inorganic acids, and iodine solution. The method for manufacturing a light-emitting element according to any one of claims 3 to 5, wherein the element separation step is performed by a wet etching method including a wet etching solution containing hydrochloric acid, and In the rough surface treatment step, the non-Al-containing layer is left in the non-roughened area and used as an etching mask. The method for manufacturing a light-emitting element according to claim 6, wherein the non-Al-containing layer includes any one or more of GaAs, InGaP, InGaAs, and Ge, and a step of removing the non-Al-containing layer is performed after the wet etching. The method of manufacturing a light-emitting element according to any one of claims 3 to 5, wherein the element separation step is performed by a dry etching method of a gas containing hydrogen chloride.