JP2005072527A - Light emitting element and its manufacturing method - Google Patents

Light emitting element and its manufacturing method Download PDF

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JP2005072527A
JP2005072527A JP2003304018A JP2003304018A JP2005072527A JP 2005072527 A JP2005072527 A JP 2005072527A JP 2003304018 A JP2003304018 A JP 2003304018A JP 2003304018 A JP2003304018 A JP 2003304018A JP 2005072527 A JP2005072527 A JP 2005072527A
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light
light emitting
emitting element
gan
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Tomio Inoue
Makoto Minamiguchi
井上登美男
南口誠
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Tomio Inoue
井上 登美男
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10Bump connectors; Manufacturing methods related thereto
    • H01L2224/12Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L2224/14Structure, shape, material or disposition of the bump connectors prior to the connecting process of a plurality of bump connectors
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/181Encapsulation

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet LED element with high emission efficiency which comprises a GaN based compound semiconductor thin film layer wherein a GaN layer which absorbs ultraviolet light is removed, and its manufacturing method for manufacturing with high yield. <P>SOLUTION: The ultraviolet LED element 1 has the epitaxial layer 8 wherein a GaN based compound semiconductor thin film layer which removes the two GaN layers and emits ultraviolet light is laminated under a silicate glass layer 9 which is a light transparent oxide layer, and an n-side electrode 12 and a p-side electrode 11 formed in an electrode surface 15 at the epitaxial layer side, and emits ultraviolet light emitted from the epitaxial layer 8 to an outside through the silicate glass layer 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultraviolet light emitting device that emits ultraviolet light, a white light emitting device using the same, and a method for manufacturing the same, and in particular, in a light emitting device (LED device) having a light emitting layer in which GaN-based compound semiconductor thin film layers are stacked. The present invention relates to an ultraviolet light emitting element having high luminous efficiency, a white light emitting element using the same, and a manufacturing method for producing the light emitting element with high yield.

GaN, GaAlN, InGaN, InAlGaN and other gallium nitride systems (GaN-based) combined with group III elements such as Ga (gallium), Al (aluminum), and In (indium)
In recent years, compound semiconductors have been widely used as semiconductor materials for visible light-emitting devices and the like, and are particularly being developed in the field of blue LEDs (light-emitting devices using this type of conventional LED).
As an example, for details of the basic structure, see, for example, Patent Document 1 below).

In this case, for example, as shown in FIG. 7 (details will be given to the following documents and the like), in this type of white light emitting element 100 having a hybrid structure, light from the light emitting element (blue LED element) 60 that emits blue light and its light Light is emitted to the outside as white light by mixing with light through the phosphor layer 63 that emits complementary color light. Further, in this case, an insulating sapphire substrate is generally used as the crystal substrate 59 for growing the semiconductor film, and Si ((conductable)) is used so that the electrode from the blue LED element 60 can be taken out. Mounting on a submount member (zener diode) 64 made of a silicon substrate by a flip chip method (flip chip mounting) (see, for example, the following Patent Document 2 for a manufacturing method (manufacturing flow)) For surface grinding, see Patent Document 3 below).
Japanese Patent No. 3257455 JP 2001-15817 A JP 2002-158377 A

  By the way, in the case of the conventional hybrid white light emitting element 100 using the blue LED element 60 shown in FIG. 7, for example, the blue LED element 60 flip-chip mounted on the submount element 64 of the zener diode is blue from the sapphire substrate 59 side. The light is extracted, and the YAG phosphor 63 applied around the blue LED element 60 is used to convert the blue light into a yellow-green light that is a complementary color thereof, and is extracted to the outside as white light by adding and mixing the light. . In this case, the light extraction efficiency from the blue LED element 60 was the highest in this hybrid structure and was a favorable structure. There are four reasons for this.

One is a type of light-emitting element that extracts light from the electrode forming surface side through a transparent electrode because there is no obstacle such as an electrode that prevents light extraction on the upper surface of the sapphire substrate 59 serving as a main light extraction surface. Compared to the above, the light extraction efficiency is higher by 30% or more.

  Second, since the electrode comes to the lower surface opposite to the upper surface of the sapphire substrate 59, which is the main light extraction surface, the material works as a light reflecting mirror by using a material with good reflectivity. Can be reflected upward by this reflecting mirror (reflecting electrode), whereby the light extraction efficiency is improved by 50% or more.

Third, the refractive index is gradually reduced to 2.1 of the GaN-based light emitting layer, 1.7 of the sapphire substrate, and 1.5 of the phosphor layer binder resin, and the loss of light at the interface can be suppressed. The effect is also added.

  Fourth, it becomes possible to process the top surface of the sapphire substrate 59, which is the main light extraction surface, into a shape that improves the light extraction efficiency, such as roughening it into a ground glass or grooving, thereby improving the light extraction efficiency. Is improved by 20% or more.

  In addition to the above effect, as a further great advantage, the Zener diode 64, which is a submount of the blue LED element 60 that is weak against static electricity, functions as an electrostatic protection element, and the blue LED element 60 against 1 kV surge in the forward direction and the reverse direction. Has been guaranteed to protect. As described above, the hybrid white light emitting device 100 mounted with the flip chip of FIG. 7 has a complicated structure as compared with the light emitting device having the structure of extracting light from the transparent electrode side, but has a number of advantages. Until the stage of using the LED element 60, the light emitting element had an excellent structure.

  However, when it becomes an ultraviolet LED element, a big problem has arisen in this structure. That is, when the wavelength is 370 nm or less, the epilayer GaN layer absorbs ultraviolet light due to the band gap, and the luminous efficiency is extremely deteriorated. For example, in the case of an ultraviolet LED element having a wavelength of 365 nm, in the case of an ultraviolet LED element having a structure in which light is extracted from the conventional transparent electrode side, a light output of 2 mW is obtained when the GaN buffer layer and the n-type GaN layer are left attached. However, it was found that the optical output of 10 mW was obtained by removing these two GaN layers. In addition to removing the GaN layer, this improvement in light output includes the effect of the reflective electrode and the effect of the electrode on the light extraction surface side. However, if these are subtracted, only the effect of removing the GaN layer is considered. The light output is at least 5 mW or more. That is, the effect is 2.5 times.

  In the case of the hybrid structure, since the two GaN layers are present at the interface between the epi layer and the sapphire substrate, the effect is greater than that of the structure in which light is extracted from the transparent electrode side. That is, both the light going upward from the light emitting layer and the light going downward (light reflected upward by the reflective electrode) are absorbed by the GaN layer, and the effect is fatal. Become. If these two GaN layers can be removed, the merit of the hybrid structure is exhibited again.

  In addition, in the manufacturing method shown in FIG. 8 (details will be left to the above-mentioned document (particularly Patent Document 2)), first, each blue LED element 60 having sapphire as the substrate 59 is prepared, and the submount element 64 and A bump electrode 61 for connecting the p-side electrode and the n-side electrode of each blue LED element 60 is formed on the Si wafer 62 (step (a)), and the p-side electrode and the n-side electrode of the blue LED element 60 are formed. Is aligned to the position of the bump electrode 61, and is joined by flip chip mounting via the bump (step (b)), and the upper surface (sapphire substrate 59 side) is ground by the grinding tool 65 to be flat (uniform) ( Step (c)), a phosphor material (phosphor paste) is screen-printed on the upper surface and side surfaces thereof to form a plurality of hybrid white light emitting elements having the phosphor layer 63 (step (d)).

Next, the upper surface of the plurality of hybrid white light emitting elements, that is, the phosphor layer 63 is attached to the grinding tool 66.
In step (e), the hybrid white light-emitting element is illuminated, and the light is input to the chromaticity measuring device 68 through the optical fiber 67 to inspect the chromaticity. If the target chromaticity is not obtained (step (f)), fine adjustment grinding of the phosphor layer 63 is performed again in step e. And the boundary of each hybrid white light emitting element is cut | disconnected (dicing) using the cutting tool (dicer) 69, and after obtaining an individual hybrid white light emitting element (process (g)), the last test | inspection is performed (step (g)). Step (h): not drawn in the figure). In the conventional manufacturing method described above, there are the following four problems that deteriorate the yield due to the construction method.

One is when the step (c) of grinding the sapphire substrate 59 of the blue LED element 60 is performed after the step (b) of flip-chip mounting the blue LED element 60 on the Si wafer 62 to be the submount element 64. Further, due to the deterioration of the sharpness of the grinding tool 65, a stress at the time of grinding is applied to the joint portion of the bump electrode, and a crack may occur in the joint portion. In this case, if it is removed due to abnormal static characteristics in the subsequent inspection process, the yield will be reduced, but if it is not detected,
It is a construction method that leads to market failure and includes extremely serious defect factors in terms of reliability.

Second, in the step (d) of forming the phosphor layer 63 by screen printing the phosphor paste, the phosphor layer 63 needs to be applied to the top and side surfaces of the blue LED element 60.
Since there is a wire bonding pad area right next to the submount element 64 on which the blue LED element 60 is flip-chip mounted, high-accuracy pattern recognition is necessary at the time of screen printing. A phosphor paste is applied to the position of the bonding pad. In this case, it is difficult to retry by removing the phosphor layer 63, and a large yield reduction occurs in which one Si wafer is lot out.

  Third, the phosphor layer 63 is ground to a uniform thickness by grinding with a grinder 66, and the thickness of the phosphor layer 63 is controlled to a thickness at which the target chromaticity is obtained in the step (e) of obtaining the target chromaticity. This depends on the phosphor concentration of the phosphor paste, but when the concentration is high, control of a thickness of 1 μm is necessary, and a fairly high-accuracy grinding machine is required, and excessive grinding may occur. In that case, it is difficult to retry by removing the phosphor layer 63 again, and the additional application of the phosphor paste is also difficult due to the wire bonding pad as described in the above 1. That is, in this case as well, a large yield reduction occurs in which one Si wafer becomes a lot-out.

  Fourth, even in the post-process only after each single unit of the blue LED element 60 is prepared, a complicated and time-consuming process as described above is necessary, and this complexity is one factor that hinders the yield improvement. It is also.

  The problem of this manufacturing method is not limited to the ultraviolet LED element, but is a manufacturing method with many problems even for blue LEDs. Therefore, the present invention solves the problems of the ultraviolet LED element including the problems of the manufacturing method, and provides an ultraviolet LED element with high luminous efficiency and a manufacturing method capable of manufacturing the LED element with a high yield. The purpose is to provide.

  The light-emitting device according to claim 1 of the present invention is a light-emitting device having a light-emitting layer made of a GaN-based compound semiconductor thin film layer, having an n-side electrode and a p-side electrode on one surface, and a GaN layer on the n-side electrode. And a light-emitting layer in which a GaN-based compound semiconductor thin film layer is laminated, and a light-transmitting oxide layer or an oxide layer containing a phosphor is formed on the GaN-based compound semiconductor thin film layer. It is a light emitting element.

  This light emitting element is different from the light emitting element 60 (blue LED element) used in the conventional hybrid structure 100 in the following points. In other words, in the conventional blue LED element 60, there is a light emitting layer in which a GaN-based compound semiconductor thin film layer is laminated on the p-side electrode, whereas the structure of the present invention has the light emission except for the GaN layer on the n-side electrode. There are layers, and a transparent oxide layer or an oxide layer containing a phosphor is formed instead of the crystalline sapphire substrate 59, and the manufacturing method thereof will be described later. Unlike the blue LED element 60 in which the epi layer is formed on the sapphire substrate 59, the sapphire substrate is removed, the GaN buffer layer and the n-type GaN layer are removed from the epi layer, and the exposed ultraviolet light is absorbed. An n-side electrode is formed on the lower surface of the n-type AlGaN layer that is not. The p-side electrode located on the side is formed on the exposed lower surface of the p-type AlGaN layer by further removing the n-type layer and the MQW layer by pattern etching (selective etching). Further, a light-transmitting oxide layer or an oxide layer containing a phosphor is formed on the epi layer, and the upper surface is used as a main light extraction surface.

  With this structure, neither upward light from the light emitting layer nor downward light reflected by the n-side electrode and going upwards passes through the GaN layer (the GaN layer has been removed), so absorption Does not happen. In this case, since the n-side electrode becomes a reflective electrode, Ag migration does not occur because the electric field is reversed, and if it can be formed by a method that can take ohmic resistance, the reflectance is still high at this wavelength (88% It is also possible to use an Ag electrode.

  Further, in this structure, in the step of forming the light-transmitting oxide layer, the phosphor is composed of three types of fluorescent light that convert ultraviolet light into R (red), G (green), and B (blue) light. If an oxide layer is formed by mixing these three kinds of phosphors, the layer becomes a white conversion layer, and a white light emitting element in which the ultraviolet LED element and the phosphor layer are integrated.

Further, in the light emitting device according to claim 2, the oxide layer is composed of a vitreous layer containing silicon oxide or aluminum oxide as a main component, and thereby the linear expansion of the epi layer in which the GaN-based compound semiconductor thin film layers are stacked. The coefficient is 5.2 × 10 −6 / ° C., and there is a glass having a linear expansion coefficient close to this and formed at 500 to 700 ° C. (for example, silicate glass or borosilicate low alkali glass), 100 μm. Since it can be formed with the above thickness, it can sufficiently substitute for a sapphire substrate. Also, aluminum oxide (alumina) is one method as long as it has the same linear expansion coefficient as that of the sapphire substrate and can be thickened by CVD or PVD. A formation method by a sol-gel method is also a good method.

  The light emitting device according to claim 3, wherein the phosphor includes three kinds of phosphors that convert ultraviolet light into R (red), G (green), and B (blue) light. If the three types of phosphors are included in the light-transmitting oxide layer, the layer becomes a white conversion layer that converts ultraviolet light into white light, and the ultraviolet LED element and the phosphor layer are integrated. A white light emitting device is obtained.

  According to a fourth aspect of the present invention, there is provided a light emitting device comprising: the light emitting device according to any one of the first to third embodiments as a single light emitting device, the single light emitting devices arranged in a matrix, and the light emitting device as a block unit. It is an element.

  Thereby, by setting it as a block light emitting element, it becomes easy to take the structure with respect to the use which requires large luminous intensity, such as an object for illumination. For example, if the area of the light emitting element is simply increased, there is a variation in VF in each part of the light emitting element, so that it is difficult for the current to flow uniformly in each part, but if the individual light emitting elements are connected in series, Since each single light emitting element has the same current, it is configured such that a current can be uniformly supplied to each part. Further, since it is not necessary to divide each single light emitting element, the number of man-hours can be reduced.

  The manufacturing method according to claim 5 of the present invention is a manufacturing method of a single light emitting device or a block light emitting device having a light emitting layer made of a GaN-based compound semiconductor thin film layer, and epitaxial vapor phase growth on a translucent crystal substrate. A GaN-based compound semiconductor thin film layer including a GaN buffer layer, an n-type GaN layer, and a light emitting layer that emits ultraviolet light is stacked by a method (this stacked structure is referred to as an epi layer, and its upper surface is referred to as an epi surface), and a light emitting diode LED) a preparatory step of preparing an epi-finished LED wafer, an oxide forming step of forming a translucent oxide layer on the epi-surface of the epi-finished LED wafer, and the translucent crystal substrate as GaN A substrate peeling step for peeling from the buffer layer, a GaN layer removing step for removing an GaN buffer layer and an n-type GaN layer that absorb ultraviolet light from the epi layer, and the epi layer Forming a p-side electrode and an n-side electrode on the surface opposite to the compound layer side to form an ultraviolet LED element, and a chip forming process for dividing along the boundary of the single light-emitting element or the block light-emitting element A method for manufacturing a light emitting device, comprising:

  In this manufacturing method, first, the epitaxial layer (GaN buffer layer, n-type GaN layer, and the like) is formed on a light-transmitting crystal substrate such as sapphire by an epitaxial vapor deposition method such as a metal organic chemical vapor deposition method (MOCVD method). An epi-finished LED wafer on which a GaN-based compound semiconductor thin film layer including a light emitting layer emitting ultraviolet light is formed is prepared (preparation step). A light-transmitting oxide layer, for example, silicate glass or borosilicate low alkali glass is formed on the epitaxial surface of the wafer (oxide forming step). The method can be formed by a sol-gel method using silicon alkoxide or a method in which silica fine powder (Aerosil) is mixed in water glass (sodium silicate solution) and heat-treated. This thickness is set to be 100 μm or more. Then, the formed light-transmitting oxide layer is ground (polished) flat with a surface grinder (polishing machine) so that the upper surface of the translucent oxide layer is parallel to the bottom surface of the sapphire substrate. Next, the translucent crystal substrate (sapphire substrate) is peeled from the GaN buffer layer by laser irradiation (substrate peeling step). The laser used for this uses a wavelength band that is absorbed by the GaN layer, where heat is generated and the sapphire substrate is peeled off due to the difference in thermal expansion.

  Next, the GaN buffer layer that absorbs ultraviolet light and the n-type GaN layer are removed from the epi layer (GaN layer removing step). The method is performed by a plasma etching method using a chlorine-based etching gas. The film thickness to be removed is about several μm, and with this method, the GaN layer can be accurately removed. Next, a p-side electrode and an n-side electrode are formed on the surface of the epi layer opposite to the oxide layer side (electrode formation step). In this case, the surface exposed by removing the GaN layer is an n-type AlGaN layer, an n-side electrode is formed on this surface, and the n-type layer and the MQW layer are further removed by pattern etching (selective etching). The AlGaN layer is exposed and a p-side electrode is formed on the surface. Since the n-side electrode also has a light reflecting mirror (reflecting electrode), it is important to use an electrode material having a high reflectivity and an ohmic property. An electrode material having a high reflectivity with respect to light having a wavelength of 365 nm is Al and Ag, and the reflectivities are 92.5% and 89%, respectively. Next, the LED element is divided into chips by dicing along the boundary of the single light emitting element or the block light emitting element (chip forming step). In this case, the outer shape of the chip can be processed into a shape with good light extraction efficiency. For example, the cross section may be a substantially trapezoidal shape.

  According to this manufacturing method, the two GaN layers that absorb ultraviolet light can be removed with high accuracy, and the reflective electrode can be an n-side electrode. Therefore, Al or Ag having high reflectivity is also used. be able to. In the case of Ag, migration does not occur because the electric field is reversed because it is an n-side electrode, and ohmic properties for n-type AlGaN are preferably formed by the following method.

  After forming a Ti thin film (transparent electrode) normally used for the n-side electrode of the GaN-based compound semiconductor light emitting device on the n-type AlGaN layer, an Ag electrode film is formed by depositing Ag on the thin film. Then, an electrode film having Ag reflectivity while maintaining ohmic properties is formed, and a structure in which Ni and Au are laminated thereon is formed. Instead of Ti, other electrode materials such as vanadium that can take ohmic contact may be used.

  The manufacturing method of claim 6 is the manufacturing method of the light emitting device according to claim 5, wherein the oxide forming step is performed by containing the phosphor in the light-transmitting oxide layer and oxidizing it. A phosphor layer forming step for forming a physical layer is used.

  According to this manufacturing method, when the light-transmitting oxide layer is formed, the three types of phosphors (phosphors that convert to R, G, and B light by ultraviolet light) are mixed and formed. The translucent oxide layer becomes a phosphor layer, and becomes a white light emitting element in which an ultraviolet LED element (epi layer) and a phosphor layer (translucent oxide layer) are integrated. In this case, the white chromaticity is adjusted by the content ratio of the three types of phosphors, and the thickness of the phosphor layer is a parameter for obtaining an optimum luminance.

  Thereby, the four problems described above can be easily solved.

  1 and 2 can form a white light-emitting element without flip-chip mounting the light-emitting element on the submount element, so there is no bump part and bonding pad area, and the pattern recognition accuracy during screen printing also contains a phosphor. No need to apply the glass paste and the problem disappears. Therefore, it is possible to improve the reliability related to the crack of the bump portion and the yield related to the lot-out of each wafer.

  No. 3 has no effect on chromaticity and does not become defective even when the thickness of the phosphor layer is excessively shaved. This eliminates the lot-out of wafer units and improves the yield.

  4 can form a white light-emitting element without flip-chip mounting the light-emitting element on the submount element, so that the process can be simplified, manufacturing can be performed with high yield, and cost can be reduced. Also, instead of processing sapphire wafers that are difficult to cut or cut, glass that is easy to process is used, so that full dicing can be easily performed, and the yield of chip forming processing is improved.

  The manufacturing method of claim 7 is the manufacturing method of the light emitting device according to claim 5 or 6, wherein a groove process is performed on an upper surface of the oxide layer containing the light-transmitting oxide layer and the phosphor. A groove processing step to be applied is further added.

  This groove processing is intended to shape the outer shape of the chip into a shape with good light extraction efficiency. For example, a material having a large refractive index by making it into a substantially trapezoidal cross section. Thus, the total reflection that occurs when light is emitted to a small substance can be reduced, and the light extraction efficiency can be increased.

  As described above, according to the light-emitting device of the present invention, the light-emitting element has an epi layer in which a GaN-based compound semiconductor thin film layer excluding the GaN layer is stacked below the light-transmitting oxide layer, and a p-side electrode and and an electrode surface having an n-side electrode. With this structure, the following three items are effective in improving luminous efficiency.

  First, since the two GaN layers that absorb ultraviolet light (GaN buffer layer and n-type GaN layer) have been removed, absorption of ultraviolet light, which has been a problem with ultraviolet LED elements, is eliminated, and light emission efficiency is at least Improve by more than 2.5 times.

  Second, if the electrode surface is used as a bonding surface and flip-chip mounted on a submount element, the hybrid structure is obtained, and there is no obstacle that obstructs light on the upper surface of the light-transmitting oxide film layer that becomes the main light extraction surface. In addition, since the n-side electrode located under the light emitting layer serves as a reflective electrode, if Al or Ag having high reflectivity is used as the electrode material, the light emission efficiency is further improved by a factor of two or more.

  The third is to improve the light extraction efficiency by roughening the upper surface of the translucent oxide layer, which is the main light extraction surface, into a frosted glass shape, or by grooving the chip shape into a substantially trapezoidal cross section. , Luminous efficiency can be improved.

  Furthermore, in the translucent oxide layer, by mixing and forming three types of phosphors that convert ultraviolet light into R, G, and B light, the layer becomes a white conversion layer, and the ultraviolet LED element and A white light emitting device in which the phosphor layer is integrated is obtained. Thereby, in the manufacturing method, there are the following three effects.

  One is that since a white light emitting element can be formed on a submount element without flip chip mounting, there is no risk of cracks in the bump joints compared to a manufacturing method in which a whitening process is performed after flip chip mounting. In addition, since the wire bonding pad region is not near the same surface, high-precision pattern recognition is not required when forming the phosphor layer, and lot-out of wafer units is eliminated, improving yield.

  Second, even if the thickness of the phosphor layer is excessively shaved, the chromaticity is not affected and does not become defective. This eliminates the lot-out of wafer units and improves the yield.

  Third, since the white light emitting element can be formed without flip chip mounting the light emitting element on the submount element, the process can be simplified, the manufacturing can be performed with high yield, and the cost can be reduced. Further, since the phosphor layer is a layer containing a phosphor in a light-transmitting oxide layer such as glass, it is not necessary to process a sapphire substrate that is difficult to process as in the conventional case, and the yield of the chip forming process is increased. improves.

  Furthermore, by using a white light-emitting element or a block white light-emitting element, it is possible to obtain a package frame that can constitute a white light-emitting device without depending on the shape of the package, and for applications that require a large light intensity such as an illumination light source. It becomes easy to take the structure.

  Hereinafter, embodiments of a light-emitting device and a method for manufacturing the same according to the present invention will be described in detail in the order of first to fourth embodiments with reference to the drawings.

  First, the light emitting device of the first embodiment is shown in FIG. Moreover, the manufacturing method consists of process (a)-(h) as shown in FIG. 3, and is a manufacturing method which manufactures several light emitting elements 1 collectively.

  The light emitting element 1 in this case is a large ultraviolet LED element used as a single light emitting element for an illumination light source, as shown in FIG. In the ultraviolet LED element 1, a GaN-based compound semiconductor thin film layer including a light emitting layer that emits ultraviolet light is laminated under the silicate glass layer 9, which is a translucent oxide layer, except for the two GaN layers. It has an epi layer 8 and an n-side electrode 12 and a p-side electrode 11 formed on the electrode surface 15 on the epi layer side, and transmits ultraviolet light emitted from the epi layer 8 through the silicate glass layer 9. This is an ultraviolet LED element of a type that emits light to the outside and a type (so-called face-down type) in which a top surface opposite to the electrode surface 15 that is a mounting surface is a main light extraction surface. The n-side electrode 12 is made of Al having a high reflectivity at the interface with the n-type AlGaN layer in order to efficiently reflect the ultraviolet light downward from the light emitting layer upward. Further, the upper surface of the silicate glass layer 9 of the main light extraction surface is processed with a groove 13 so that the extraction efficiency of ultraviolet light is good, and each of the sections of the n-side electrode 12 divided into four sections. The shape is substantially trapezoidal.

  Hereinafter, the manufacturing method of this light emitting element is demonstrated in order of process (a)-(h) of FIG. First, in step (a), a GaN buffer layer 6, an n-type GaN layer 7, and a GaN-based compound semiconductor (consisting of an n-type AlGaN layer, MQW layer, p-type AlGaN layer, p-type cap layer, etc.) on a sapphire substrate 5. One epi-finished LED wafer in which an epi layer composed of the thin film layer 8 is formed by a metal organic chemical vapor deposition method (MOCVD method) or the like is prepared (preparation step).

  Next, in step (b), the epi layer is protected by forming an aluminum oxide film of several μm on the upper surface of the epi layer by a CVD method, and silicate glass is formed thereon by a sol-gel method using silicon alkoxide. Form 100 μm or more. Here, in order to increase the thickness, silica fine powder (Aerosil) is mixed and heat treatment is performed at a temperature of 500 to 700 ° C. in a nitrogen atmosphere. Or after mixing silica fine powder with water glass (sodium silicate solution) and drying, it is set as the glass layer 9 by baking at the temperature of 500-700 degreeC in nitrogen atmosphere (oxide formation process). Then, in order to make the upper surface of the formed glass layer 9 parallel to the bottom surface of the sapphire substrate, it is ground (polished) with a surface grinder or lapping machine.

Next, in the step (c), the GaN buffer layer 6 can be obtained by irradiating light from the sapphire substrate side using a laser that oscillates ultraviolet light (for example, a gas laser of 325 nm He—Cd laser or 337 nm N 2 laser). The GaN buffer layer 6 is suddenly heated. And the distortion by thermal expansion arises in the interface with a sapphire substrate, peeling arises in the interface, and a sapphire substrate can be cut off (substrate peeling process). Thereafter, the glass layer 9 serves as a substrate.

  Next, in step (d), the GaN buffer layer 6 and the n-type GaN layer 7 appearing on the surface are removed by plasma etching (RIE) using a chlorine-based gas (GaN layer removing step), and the n-type AlGaN layer is removed. Expose. This process can be controlled on the order of μm.

  Next, in step (e), the region 10 for forming the p-side electrode 11 is further subjected to pattern etching (selective etching) and plasma etching (RIE) using a chlorine-based gas to form the n-type AlGaN layer and the MQW. The layer is removed to expose the p-type AlGaN layer.

  Next, in step (f), a p-side electrode made of Ni / Au is formed on the surface of the p-type AlGaN layer in the region 10 and an n-side electrode made of Al having a high reflectance is formed on the surface of the n-type AlGaN layer (electrode formation). Process).

  Next, in the step (g), on the upper surface of the glass layer 9 serving as the main light extraction surface, at the boundary and the center of the large ultraviolet LED element 1 (single light emitting element) so as to improve the light extraction efficiency. A groove 13 having a width of about 300 μm and a depth of about 70 μm is formed. This processing can be performed more easily than a sapphire substrate. Moreover, the cross-sectional shape of each one section of the n-side electrode 12 divided into four large ultraviolet LED elements is substantially trapezoidal, and the light extraction efficiency is improved.

  Next, at a process (h), it cut | disconnects along the boundary of an ultraviolet LED element by full dicing, and is chipped (chip formation process). When full dicing is difficult due to chipping or the like, a chip having a width of about 30 μm and a depth of about 10 μm is formed on the bottom surface of the groove 13, and a chip is formed by breaking along the line.

  As described above, according to the present embodiment (first embodiment), the sapphire substrate can be peeled from the epi layer, and the GaN layer that absorbs ultraviolet light can be accurately removed by plasma etching. This is possible because the glass layer 9 can be formed in place of the sapphire substrate.

  Next, a manufacturing method for manufacturing a plurality of block light emitting devices 2 shown in FIG. 2 in a batch by using the light emitting device and the manufacturing method thereof according to the second embodiment will be described.

  As shown in FIG. 2, the block light emitting element 2 in this case is an ultraviolet LED element having a side of 0.32 mm as a single light emitting element, and is a block light emitting element arranged in 2 rows and 2 columns. The structure of the single light emitting element is the same as that of FIG. 1 except that the element size and the electrode pattern are different.

Also, the manufacturing method is not shown because it includes substantially the same steps as in the first embodiment. The only difference is that the pattern of the ultraviolet LED element and the unit of chip formation are different.

  Thus, when making a light emitting device large, a method of increasing the area of the electrode simply by increasing the area as shown in FIG. 1 and a block of small light emitting devices as shown in FIG. There is no difference in the method of flowing the current uniformly in each part of the light emitting element when there is no VF (forward voltage) variation in the light emitting element. In the case of a light-emitting element, the variation is large. Therefore, when the light-emitting element is blocked as shown in FIG. 2, a current can flow more uniformly through each part of the light-emitting element, and the light emission efficiency can be improved. In consideration of an illumination light source or the like, the drive voltage is preferably set to 100 V. However, a series connection is easier to configure an illumination light source.

  Next, the white light emitting element of 3rd Embodiment is shown in FIG. Moreover, the manufacturing method consists of process (a)-(h) as shown in FIG. 6, and is a manufacturing method which manufactures several white light emitting elements 3 collectively.

As shown in FIG. 4, the white light emitting element 3 in this case is a large ultraviolet LED element used as a light source for illumination as a single light emitting element, in which a phosphor layer 19 is integrated. The phosphor layer 19 receives ultraviolet light in the light-transmitting oxide layer formed on the epi layer from which the GaN buffer layer 6 and the n-type GaN layer 7 are removed, and converts it into R, G, B light. It is a layer formed by mixing three types of phosphors to be converted. That is, the translucent oxide layer 9 of the light-emitting element 1 in FIG. 1 is replaced with a phosphor layer 19, for example, a layer in which the three kinds of phosphors are mixed in a silicate glass layer. The rest is the same as the first embodiment.

Further, a method for manufacturing this light emitting element will be described in the order of steps (a) to (h) in FIG. However, it is almost the same as the manufacturing method shown in FIG. 3, and the only difference is the oxide forming step of step (b), which will be described. In the step (b), an epi layer is protected by forming an aluminum oxide film of several μm on the upper surface of the epi layer by a CVD method, and a silicate glass is used as a binder by a sol-gel method using silicon alkoxide thereon. Three types of phosphor powders (for example, R is Y 2 O 2 S: Er, G is (Ba, Mg) Al 10 O 17 : Eu, Mn, B is (Ba, Mg) Al 10 O 17 : A phosphor layer 19 in which Eu) is hardened is formed with a thickness of 100 μm or more. Here, in order to adjust the chromaticity, an appropriate amount of fine silica powder (Aerosil) is mixed, and heat treatment is performed at a temperature of 500 to 700 ° C. in a nitrogen atmosphere. Alternatively, the phosphor layer 19 is prepared by mixing the three kinds of phosphor powder and silica fine powder in water glass (sodium silicate solution), drying the mixture, and firing the mixture in a nitrogen atmosphere at a temperature of 500 to 700 ° C. (Phosphor layer forming step). Then, in order to make the upper surface of the formed phosphor layer 19 parallel to the bottom surface of the sapphire substrate, it is ground (polished) with a surface grinder or lapping machine.

  In this manufacturing method, the phosphor layer 19 that converts ultraviolet light into R, G, and B light can be integrated without flip-chip mounting, so that a plurality of white light emitting elements 3 can be formed. In addition to improving the reliability and yield of the four problems in the method for manufacturing the hybrid white light emitting device 100, the process is simplified, and a plurality of white light emitting devices 3 having a uniform size and high light emission efficiency are bundled. Can be manufactured and the cost can be reduced.

  Next, a manufacturing method for manufacturing a plurality of block white light-emitting elements 4 shown in FIG.

  As shown in FIG. 5, the block white light emitting element 4 in this case is an ultraviolet LED element having a side of 0.32 mm as a single light emitting element, which is a block white light emitting element arranged in two rows and two columns. The structure of the single light emitting element is the same as that of FIG. 4 except for the element size and the electrode pattern. Further, the size is not limited to this, and the size of the single light emitting element and the number of blocks (block size) may be arbitrary.

  Also, the manufacturing method is not shown because it includes substantially the same steps as those of the third embodiment. The only difference is that the pattern of the ultraviolet LED element and the unit of chip formation are different.

  Since the block white light emitting element 4 can be a white light emitting element without being flip-chip mounted, there are advantages similar to those described in the third embodiment, and the block white light emitting element 4 is used for illumination. It has an optimal structure as a white light emitting element for large currents such as a light source. By making it a block light emitting element, it becomes easy to adopt the configuration for applications that require a large luminous intensity, such as for illumination. For example, if the area of the light emitting element is simply increased, there is a variation in VF in each part of the light emitting element, so that it is difficult for the current to flow uniformly in each part, but if the individual light emitting elements are connected in series, Since each single light emitting element has the same current, it is configured such that a current can be uniformly supplied to each part. Further, since it is not necessary to divide each single light emitting element, the number of man-hours can be reduced. Further, since it is already a white light emitting element, the package becomes free regardless of the type of package, which is limited when whitening is performed at the time of package sealing.

It is the detail of the light emitting element of 1st Embodiment which concerns on this invention, Comprising: (a) is a top view, (b) is a longitudinal cross-sectional view by the AA arrow of (c), (c) is a bottom plan view It is. It is the detail of the light emitting element of 2nd Embodiment which concerns on this invention, Comprising: (a) is a top view, (b) is a longitudinal cross-sectional view by the BB line arrow of (c), (c) is a bottom plan view It is. It is sectional drawing according to process which shows the manufacturing method of the light emitting element of 1st Embodiment which concerns on this invention. It is a detail of the light emitting element of 3rd Embodiment concerning this invention, Comprising: (a) is a top view, (b) is a longitudinal cross-sectional view by the AA arrow of (c), (c) is a bottom plan view It is. It is the detail of the light emitting element of 4th Embodiment which concerns on this invention, Comprising: (a) is a top view, (b) is a longitudinal cross-sectional view by the BB line arrow of (c), (c) is a bottom plan view It is. It is sectional drawing according to process which shows the manufacturing method of the light emitting element of 3rd Embodiment which concerns on this invention. It is front sectional drawing which shows the structure of the white light emitting element (hybrid white light emitting element) using the conventional general light emitting element. It is sectional drawing according to process which shows an example of the manufacturing method of the conventional light emitting element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Light emitting element 3, 4 White light emitting element 5 Sapphire substrate 6 GaN buffer layer 7 n-type GaN layer 8 Epi layer containing a light emitting layer 9 Translucent oxide layer 10 Etching part 11 P side electrode 12 N side electrode 13 Groove 15 Electrode surface 19 Phosphor layer 32 Laser 33 RIE (plasma etching)
34 Dicer

Claims (7)

  1. In a light emitting device having a light emitting layer composed of a GaN-based compound semiconductor thin film layer,
    A light emitting layer having an n-side electrode and a p-side electrode on one surface, and a GaN-based compound semiconductor thin film layer excluding the GaN layer stacked on the n-side electrode; A light-emitting element, wherein a light-transmitting oxide layer or an oxide layer containing a phosphor is formed.
  2.   The light emitting device according to claim 1, wherein the oxide layer is made of a vitreous layer containing silicon oxide or aluminum oxide as a main component.
  3.   3. The light emitting device according to claim 1, wherein the phosphor includes three types of phosphors that convert ultraviolet light into R (red), G (green), and B (blue) light. 4. .
  4.   A light-emitting element according to claim 1, wherein the light-emitting element is a single light-emitting element, the single light-emitting elements are arranged in a matrix, and the block light-emitting element is used as a block unit.
  5. A method for manufacturing a single light-emitting element or a block light-emitting element having a light-emitting layer composed of a GaN-based compound semiconductor thin film layer,
    A GaN-based compound semiconductor thin film layer including a GaN buffer layer, an n-type GaN layer, and a light emitting layer that emits ultraviolet light is laminated on a translucent crystal substrate by epitaxial vapor deposition (this laminated structure is an epi layer, its A preparation step of preparing an epi-finished LED wafer having a light emitting diode (LED) structure;
    An oxide forming step of forming a translucent oxide layer on the epi surface of the epi-LED wafer, a substrate peeling step of peeling the translucent crystal substrate from the GaN buffer layer, and ultraviolet light from the epi layer. A GaN layer removal step for removing the absorbing GaN buffer layer and the n-type GaN layer;
    On the surface of the epi layer opposite to the oxide layer side, a p-side electrode and an n-side electrode are formed to form an ultraviolet LED element along the boundary between the single light emitting element or the block light emitting element. Dividing into chips, and
    A process for producing a light emitting device comprising:
  6. It is a manufacturing method of the light emitting element according to claim 5,
    The method for manufacturing a light emitting element, wherein the oxide forming step is a phosphor layer forming step in which the phosphor is contained in the light-transmitting oxide layer to form an oxide layer.
  7. A method of manufacturing a light emitting device according to claim 5 or 6,
    A method for manufacturing a light emitting element, further comprising a groove processing step of performing groove processing on an upper surface of the light-transmitting oxide layer and the oxide layer containing a phosphor.
JP2003304018A 2003-08-28 2003-08-28 Light emitting element and its manufacturing method Pending JP2005072527A (en)

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Cited By (10)

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WO2006104063A1 (en) * 2005-03-28 2006-10-05 Tokyo Institute Of Technology Nitride-based deep ultraviolet luminescent element and process for producing the same
JP2007081088A (en) * 2005-09-14 2007-03-29 Showa Denko Kk Nitride-based semiconductor light-emitting element
JP2007081333A (en) * 2005-09-16 2007-03-29 Showa Denko Kk Nitride-based semiconductor light-emitting element and manufacturing method thereof
JP2007103690A (en) * 2005-10-05 2007-04-19 Matsushita Electric Ind Co Ltd Semiconductor light emitting device and its fabrication process
JP2007184615A (en) * 2006-01-09 2007-07-19 Mediana Electronic Co Ltd Light-emitting diode element which emits light of complex wavelengths
JP2007220972A (en) * 2006-02-17 2007-08-30 Showa Denko Kk Semiconductor light-emitting element, manufacturing method thereof, and lamp
JP2007220970A (en) * 2006-02-17 2007-08-30 Showa Denko Kk Light-emitting element, manufacturing method thereof, and lamp
JP2009231785A (en) * 2007-04-16 2009-10-08 Toyoda Gosei Co Ltd Light-emitting device and light emitter
US7982232B2 (en) 2008-08-27 2011-07-19 Showa Denko K.K. Semiconductor light-emitting device, manufacturing method thereof, and lamp
JP2013135139A (en) * 2011-12-27 2013-07-08 Disco Abrasive Syst Ltd Byte cutting method

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006104063A1 (en) * 2005-03-28 2006-10-05 Tokyo Institute Of Technology Nitride-based deep ultraviolet luminescent element and process for producing the same
JP2007081088A (en) * 2005-09-14 2007-03-29 Showa Denko Kk Nitride-based semiconductor light-emitting element
JP2007081333A (en) * 2005-09-16 2007-03-29 Showa Denko Kk Nitride-based semiconductor light-emitting element and manufacturing method thereof
JP2007103690A (en) * 2005-10-05 2007-04-19 Matsushita Electric Ind Co Ltd Semiconductor light emitting device and its fabrication process
JP2007184615A (en) * 2006-01-09 2007-07-19 Mediana Electronic Co Ltd Light-emitting diode element which emits light of complex wavelengths
US8748902B2 (en) 2006-01-09 2014-06-10 Samsung Electronics Co., Ltd. Light-emitting diode device generating light of multi-wavelengths
US7965036B2 (en) 2006-01-09 2011-06-21 Samsung Co., Ltd. Light-emitting diode device generating light of multi-wavelengths
JP2007220970A (en) * 2006-02-17 2007-08-30 Showa Denko Kk Light-emitting element, manufacturing method thereof, and lamp
JP2007220972A (en) * 2006-02-17 2007-08-30 Showa Denko Kk Semiconductor light-emitting element, manufacturing method thereof, and lamp
JP2009231785A (en) * 2007-04-16 2009-10-08 Toyoda Gosei Co Ltd Light-emitting device and light emitter
US7982232B2 (en) 2008-08-27 2011-07-19 Showa Denko K.K. Semiconductor light-emitting device, manufacturing method thereof, and lamp
JP2013135139A (en) * 2011-12-27 2013-07-08 Disco Abrasive Syst Ltd Byte cutting method

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