JP2008166487A - Semiconductor light-emitting device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that hue adjustment needed for use of semiconductor light-emitting device as lighting application requires thickness adjustment by grinding a phosphor layer, that lessening unnecessary light emitted from a side face of the phosphor layer requires use of a reflecting unit having a reflective surface, and that grinding work may damage the semiconductor light-emitting device. <P>SOLUTION: The semiconductor light-emitting device is designed so that a top face is higher than the surface of the reflecting unit, and the top face is ground while a hue of light is checked to manufacture the semiconductor light-emitting device offering a desired hue. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor light-emitting device in which a phosphor layer is disposed around a semiconductor light-emitting element surrounded by a reflecting portion, and a semiconductor light-emitting device in which a phosphor layer is ground and adjusted in order to adjust the color, and a method for manufacturing the same. Is.

  Semiconductor light-emitting devices are not only used for semiconductor light-emitting elements that emit light of a specific color, but are often used by changing the emission color by arranging a phosphor layer around the semiconductor light-emitting elements. After the development of a semiconductor light emitting device capable of emitting blue light, it has become possible to emit white light using a phosphor that emits yellow light with blue light. In such a case, the mixing ratio of blue and yellow varies depending on the concentration and thickness of the phosphor layer containing the phosphor, and even if the white color is the same, the hue slightly changes.

  Conventionally, semiconductor light-emitting devices have been demanded only for light emission, but there are many demands for using semiconductor light-emitting devices having long life and low power consumption for illumination. In order to use the semiconductor light emitting device for illumination, it is necessary to prepare light of a specific range of shades, even if it is white light, in order to make the illuminated object appear as natural as possible.

  In order to adjust the emission color, a technique of grinding after forming a phosphor layer on a semiconductor light emitting element has been proposed (see Patent Document 1).

  By the way, there are many inventions that try to use the light emission color of the semiconductor light emitting element as efficiently as possible, and the semiconductor light emitting element is mounted on a package (or also called a cup) composed of a reflecting portion having a reflecting surface whose inner surface is mirror finished. The structure to fix is known (refer patent document 2).

  However, it is difficult to use light emitted from the semiconductor light emitting device in the lateral direction even if it is reflected by a reflecting surface or the like. Therefore, it is desirable from the aspect of efficient use that the light emitted from the side surface of the semiconductor light emitting device is made as small as possible.

In a semiconductor light emitting device having a phosphor layer fixed to a package composed of a reflective portion, when the phosphor layer is ground to adjust the hue of the luminescent color, the phosphor is positioned higher than the upper surface of the reflective portion. There must be a layer surface. Such a configuration is disclosed in Patent Document 3, for example.
JP 2001-15817 A JP 2005-93896 A Japanese Patent Laid-Open No. 2000-223752

  In order to efficiently use the light emitted from the semiconductor light emitting device, a means for limiting the light emitted from the semiconductor light emitting element in the lateral direction, such as a reflection portion, is necessary. On the other hand, when the color tone is adjusted, it is necessary to grind the top surface of the phosphor layer. However, for this purpose, if the top surface is not above the reflecting portion, the reflecting portion must be ground together, which may cause damage to the semiconductor light emitting device itself. Then, light leaks from the phosphor layer between the top surface and the reflecting portion surface, and this becomes light that cannot be used effectively.

  The present invention has been conceived in view of the requirement to use a reflecting portion in order to improve the light utilization efficiency as described above and to enable adjustment of the hue.

  In order to solve the above-mentioned problems, the present invention fixes a semiconductor light emitting device in a package surrounded by a reflective portion so that not only the light emitting surface but also a connection line with an extraction electrode does not come out above the reflective portion surface. To do. The phosphor layer filled up to the surface of the reflecting portion is ground to adjust the hue, and the semiconductor light emitting device and the manufacturing method thereof.

  In the semiconductor light emitting device of the present invention, since the connecting line with the lead electrode as well as the light emitting surface of the semiconductor light emitting element is not above the reflecting portion surface, the phosphor layer can be ground up to the reflecting portion surface. That is, it is possible to provide a semiconductor light emitting device in which the color tone is adjusted with the semiconductor light emitting element having the reflective portion.

  FIG. 1 shows a semiconductor light emitting device 1 of the present invention. In the semiconductor light emitting device 1, the semiconductor light emitting element 10 is fixed on the submount 21, the reflecting portion 40 is disposed around the semiconductor light emitting element, and the phosphor layer 50 is formed in a portion surrounded by the reflecting portion and the submount. It is a filled structure.

  Lead electrodes 22 and 23 are formed on the submount 21. The extraction electrode is an electrode for applying a current to the semiconductor light emitting element 10. There are an n-side extraction electrode 22 connected to the n-type layer side of the semiconductor light emitting device and a p-side extraction electrode 23 connected to the p-type layer side. Further, in FIG. 1, the extraction electrode is connected to the terminal electrodes 28 and 29 through the through holes 26 and 27. As a result, current can flow from the terminal electrodes 28 and 29 to the semiconductor light emitting device. Bumps 24 and 25 are formed on the extraction electrode. Similar to the lead electrode, the bump includes an n-side bump 24 connected to the n-type layer and a p-side bump 25 connected to the p-type layer. Although there are a plurality of p-side bumps in FIG. Of course, there may be a plurality of n-side bumps. The lead electrode and the semiconductor light emitting element are directly connected by this bump. Therefore, this bump can be said to be a connection line. The submount 21, the extraction electrodes 22 and 23, the bumps 24 and 25, the through holes 26 and 27, and the terminal electrodes 28 and 29 are collectively referred to as the support body 20. In some embodiments, the terminal electrodes 28 and 29, the bumps 24 and 25, and the through holes 26 and 27 may be omitted from the support 20. Further, the support 20 and the reflecting portion 40 are collectively referred to as a package.

  For the submount 21, a silicon Zener diode, a silicon diode, silicon, aluminum nitride, alumina, other ceramics, or the like can be used.

  The through hole is a through hole formed in the submount and includes a conductive material such as copper, aluminum, and gold inside. The terminal electrode 29 is electrically joined to the through hole and is made of a conductive material such as copper, silver, or gold. For the extraction electrode, a conductive material such as copper, aluminum, gold, or silver is used.

  The bumps serve to fix the semiconductor light emitting element 10 on the submount 21 and to electrically couple the lead electrodes 22 and 23 to each other.

  As the material for the bump, gold, gold-tin, solder, indium alloy, conductive polymer, or the like can be used, but a material mainly containing gold or gold is particularly preferable. Using these materials, it can be formed using a plating method, a vacuum deposition method, a screen printing method, a droplet injection method, a wire bump method, or the like.

  For example, a gold wire is produced by the wire bump method, and one end of the gold wire is bonded to the extraction electrode on the submount with a bonder, and then the wire is cut to form a gold bump. In addition, a liquid in which fine nanoparticles of highly conductive material such as gold are dispersed in a volatile solvent is printed by a method similar to inkjet printing, and the solvent is removed by volatilization to form bumps as an aggregate of nanoparticles. A drop ejection method can also be used.

  The semiconductor light emitting device 10 includes a substrate 11, an n-type layer 12, an active layer 13, a p-type layer 14, an n-side electrode 16, and a p-side electrode 17.

  The substrate 11 has a role of holding a portion that emits light. As a material, insulating sapphire can be used. However, since the luminous efficiency and the light emitting part are based on gallium nitride (GaN), in order to reduce the reflection of light at the light emitting layer, more specifically, at the interface between the n-type layer 12 and the substrate 11. It is preferable to use GaN, SiC, AlGaN, or AlN having a refractive index equivalent to that of the light emitting layer.

  The n-type layer 12, the active layer 13, and the p-type layer 14 that are light emitting layers are sequentially stacked on the substrate 11. The material is not particularly limited but is preferably a gallium nitride compound. Specifically, the n-type layer 12 of GaN, the active layer 13 of InGaN, and the p-type layer 14 of GaN, respectively. As the n-type layer 12 and the p-type layer 14, AlGaN or InGaN may be used, or a buffer layer made of GaN or InGaN may be used between the n-type layer 12 and the substrate 11. It is. For example, the active layer 13 may have a multilayer structure (quantum well structure) in which InGaN and GaN are alternately stacked.

  Thus, the active layer 13 and the p-type layer 14 are removed from a part of the n-type layer 12, the active layer 13 and the p-type layer 14 laminated on the substrate 11, and the n-type layer 12 is exposed. An n-side electrode 16 is formed on the exposed n-type layer 12. Similarly, a p-side electrode 17 is formed on the p-type layer 14. That is, by removing the active layer 13 and the p-type layer 14 and exposing the n-type layer 12, the light emitting layer, the p-side electrode, and the n-side electrode can be formed on the same side of the substrate.

  The p-side electrode 17 uses a first electrode made of Ag, Al, Rh or the like having high reflectivity in order to reflect the light emitted from the light emitting layer to the substrate 11 side. That is, in the case of FIG. 1, the substrate 11 is a light emitting surface. In order to reduce the ohmic contact resistance between the p-type layer 14 and the p-side electrode 17, it is desirable to use a second electrode such as Pt, Ni, Co, or ITO between the p-type layer 14 and the first electrode. The n-side electrode 16 can use Al, Ti, or the like. It is desirable to use Au or Al on the surface of the p-side electrode 17 and the n-side electrode 16 in order to increase the adhesive strength with the bump. These electrodes can be formed by vacuum deposition, sputtering, or the like.

  The size of the semiconductor light emitting element 10 is not particularly limited, but in order to obtain a light source with a large amount of light and near surface emission, it is preferable that the entire area is wide, and it is desirable that one side is 600 μm or more.

  The reflecting portion is disposed around the semiconductor light emitting element and reflects light emitted in the lateral direction to the top surface 55 side. As the material, resin, metal, ceramic or a composite thereof is used. In particular, the surface 42 facing the semiconductor light emitting element side preferably has an inclined or concave surface to reflect light to the top surface side, and is preferably mirror-finished. Specifically, any treatment in which the reflecting portion is formed of aluminum and polished to a mirror surface, or aluminum or silver is deposited or plated on the reflecting portion formed of resin can be used.

  Since the reflecting portion is provided to reflect light emitted from the semiconductor light emitting element obliquely with respect to the top surface direction, the reflecting surface 45 is set higher than the light emitting surface of the semiconductor light emitting device. Here, “high” means that the distance from the submount is long.

  The phosphor layer 50 is obtained by dispersing particles of an inorganic or organic phosphor material in a transparent medium such as a resin or glass.

For example, when the semiconductor light emitting element 10 emits blue light and the emission color of the semiconductor light emitting device 1 itself is white, the phosphor that receives blue light from the semiconductor light emitting element 10 and converts the wavelength to yellow and emits it. It is. As such a phosphor material, a rare earth-doped nitride-based or rare earth-doped oxide-based phosphor is preferable. More specifically, (Y · Sm) ₃ (Al · Ga) ₅ O ₁₂ : Ce or (Y _0.39 Gd _0.57 Ce _0.03 Sm _0.01 ) ₃ Al ₅ O ₁₂ of the rare earth doped alkaline earth metal sulfide rare earth doped garnet. Rare earth doped alkaline earth metal orthosilicate, rare earth doped thiogallate, rare earth doped aluminate and the like can be suitably used. Further, silicate phosphor _{(Sr 1-a1-b2-} x Ba a1 Ca b2 Eu x) 2SiO 4 or alpha sialon (α-sialon: Eu) Mx (Si, Al) 12 (O, N) 16 yellow emission It may be used as a phosphor material.

  Throughout this specification, Al is aluminum, N is nitrogen, O is oxygen, Ag is silver, Rh is rhodium, Pt is platinum, Ni is nickel, Co is cobalt, Ti is titanium, Au is gold, Y is yttrium, Sm represents samarium, Ce represents cerium, Sr represents strontium, Ba represents barium, Ca represents calcium, Eu represents europium, and Mg represents magnesium.

  As the medium, a resin mainly composed of a silicone resin, an epoxy resin, and a fluororesin can be used. In particular, as the non-silicone resin, a siloxane-based resin, a polyolefin, a silicone / epoxy hybrid resin, or the like is preferable.

Note that a glass material manufactured by a sol-gel method can be used instead of the resin. Specifically, it is a compound represented by the general formula Si (X) _n (R) _4-n (n = 1 to 3). Here, R is an alkyl group, and X is selected from halogen (Cl, F, Br, I), a hydroxy group (—OH), and an alkoxy group (—OR). A phosphor or an alkoxide represented by the general formula M (OR) _n can also be added to this glass material. The refractive index of the concavo-convex structure can be changed by adding an alkoxide.

  Some of these glass materials have a curing reaction temperature of about 200 degrees Celsius, and can be said to be suitable materials considering the heat resistance of materials used for bumps and electrode portions. A state in which the phosphor material and the medium are mixed is called a phosphor paint.

  The top surface 55 of the phosphor layer 50 serves as a light emission exit surface of the semiconductor light emitting device 1. The color of the semiconductor light emitting device 1 is determined by the phosphor h1 between the substrate 11 and the top surface 55 of the semiconductor light emitting element 10. Therefore, the final color of the semiconductor light emitting device 1 is determined by grinding the top surface as will be described later. That is, the top surface of the semiconductor light emitting device 1 of the present invention is finished by grinding.

  On the other hand, since the hue is determined by grinding the top surface, the semiconductor light-emitting device 1 itself may be damaged if the reflective portion is ground during grinding. Therefore, a certain margin h <b> 2 is provided on the top surface 55 of the phosphor layer 50 and the surface 45 of the reflecting portion 40.

  If the margin h2 is too high, the emitted light from this becomes unnecessary light, so it is desirable that the margin h2 be as low as possible.

  The color of the semiconductor light emitting device 1 is considered to be determined by the distance h1 between the top surface and the substrate, the concentration of the phosphor material of the phosphor layer 50, and the emission color of the semiconductor light emitting element 10. The concentration of the phosphor material in the phosphor layer is not particularly limited, but if the concentration is high, h1 can be lowered, but the hue changes greatly by slight grinding. If the concentration is too low, it is easy to adjust the hue by grinding, but the phosphor layer must be thickened to obtain the desired hue, and h2 may increase. As already described, unnecessary radiation increases as h2 increases. The concentration of the phosphor material is preferably about 10 to 60% by mass with respect to the medium.

  h1 and h2 cannot be defined in particular, and are designed as needed according to the specifications of the required semiconductor light emitting device. However, if the light emission angle of the semiconductor light emitting device is reduced, the light emitted in the oblique direction becomes unnecessary light, and therefore it is preferable that the light emission angle be as small as possible with respect to the aperture length L. Accordingly, h2 is desirably 1/10 or less of the opening length L surrounded by the reflection portion.

  FIG. 2 is a view of the semiconductor light emitting device of FIG. 1 as viewed from the top side.

  FIG. 3 is a diagram showing a method for manufacturing a semiconductor light emitting device of the present invention. A through hole is provided in the submount, a terminal electrode is formed on the back side, an extraction electrode is formed on the front side, and then a bump is formed on the extraction electrode. Thereafter, a semiconductor light emitting element is welded to the bump. Welding is performed by ultrasonic vibration. Specifically, the support 20 or the semiconductor light emitting element 10 side is fixed, the other is fixed by a chuck of an ultrasonic welding apparatus, and ultrasonic vibration is applied. At this time, by heating from the support 20 or the semiconductor light-emitting element 10 side, the bumps and the n-side electrode 16 and the p-side electrode 17 of the semiconductor light-emitting element can be welded with a lower ultrasonic output than when not heated. it can. The heating temperature is preferably 100 to 400 ° C. FIG. 3A shows a state where the semiconductor light emitting element is welded.

  In order to improve mass productivity, a plurality of semiconductor light emitting devices are manufactured on the submount at a time.

  Next, the package material is bonded (FIG. 3B). Since the reflecting portion material is cut into individual semiconductor light emitting devices in a later step, the reflecting portion material is a member having inclined surfaces on both sides. The adhesive is not particularly limited, but it is considered that the semiconductor light emitting device itself is subjected to a solder flow treatment or the like when it is bonded to a printed circuit board, etc. Therefore, a resin adhesive having a glass transition temperature of 250 ° C. or higher or a sol-gel method. A formed glass bond or the like is preferable.

  After the reflecting portion material is adhered, a phosphor layer is formed (FIG. 3C). In this case, the phosphor coating described above is formed by dipping or printing. At this time, the distance h1 between the top surface and the substrate is formed sufficiently thick.

  After the phosphor layer is cured, the phosphor layer is ground. For grinding, a lap master or a surface grinder is used. Further, a plurality of stages of grinding may be used, such as grinding at a stroke to near the design thickness h1, and then performing fine grinding while watching the hue.

  Specifically, in the grinding process, the top surface is ground by grinding and the distance h1 between the top surface and the substrate is shortened. Then, the light is actually emitted to check the color, and if it does not reach the predetermined color, further grinding is performed. The process of performing is repeated (FIG. 3D).

  After adjusting the distance h1 between the top surface and the substrate so as to obtain a predetermined color, the space between the reflective portions is cut and divided into individual chips (FIG. 3E). Thus, the semiconductor light emitting device of the present invention can be obtained.

  In the present embodiment, the case where the extraction electrode and the semiconductor light emitting device are connected using bumps has been described. However, the present invention may be implemented in other forms without departing from the spirit of the present invention.

  FIG. 4 shows a case where the shape of the extraction electrode is different. The submount 21 has no through hole. On the other hand, the extraction electrodes 22 and 23 pass under the reflecting portion, and are routed around the side surface of the submount to the lower side of the submount. That is, the extraction electrode and the terminal electrode are common.

  FIG. 5 further shows the case where the semiconductor light emitting device is fixed upward. In this example, the emission surface is on the p-type layer side, and the n-side electrode and the p-side electrode are formed upward. Therefore, the connection lines 18 and 19 are connected to the extraction electrodes 22 and 23. This connection line is formed by wire bonding. The p-side electrode is composed of a translucent electrode that covers almost the entire surface of the p-type layer and a pad electrode provided on a part thereof. As a manufacturing method, it is the same as the method shown in FIG. 3, and it is necessary to finish wire bonding before bonding the reflective portion. In the present invention, the top surface 55 is ground for color adjustment. Therefore, the apex 31 of the connection line must be lower than the surface 45 of the reflection part. In other words, it is difficult to wire-bond the electrode of the semiconductor light emitting element and the extraction electrode after bonding the reflection portion. “Low” means that the distance from the submount is short.

  FIG. 6 shows an example where the n-side electrode is formed on the back side of the substrate 11. Also in this case, the manufacturing method of the connection line 18 is the same as in the case of FIG. In addition, the extraction electrode and the terminal electrode are formed in common.

  FIG. 7 shows an example in which the extraction electrode is formed only on the surface of the submount. The connection between the extraction electrode and the power supply line 33 may be normal soldering. As a manufacturing method in the case of FIG. 7, in FIG. 3B, instead of adhering a reflection part common to the adjacent semiconductor light emitting device, individual reflection parts are adhered. Therefore, in the step of FIG. 3E, the reflecting portion is not cut, but only the submount is cut.

  FIG. 8 illustrates another embodiment of the semiconductor light emitting device of the present invention described in FIGS. Compared with FIG. 2, FIG. 8 does not have the hatched portion 43 of the reflecting portion. This is because, when the phosphor layer is applied, FIG. 2 is prepared by applying a phosphor paint to each semiconductor light emitting device, whereas in the case of FIG. The semiconductor light-emitting devices lined up in (1) were collectively applied with a phosphor coating material, and the individual phosphor layers were cut together with the submount and the reflective portion when cutting them individually.

  FIG. 9 shows the case where the inclined surface of the reflecting portion is circular 44 and the phosphor layer is also circular. Thus, in the semiconductor light emitting device of the present invention, the shape of the phosphor layer is not limited to a square, and may be a circle or a triangle.

  The present invention can be used for a semiconductor light-emitting device that adjusts the hue.

The figure showing the structure of the semiconductor light-emitting device of this invention The figure which looked at the semiconductor light-emitting device of this invention from the top | upper surface side The figure which shows the manufacturing method of the semiconductor light-emitting device of this invention The figure which shows the other structure of the semiconductor light-emitting device of this invention. The figure which shows the other structure of the semiconductor light-emitting device of this invention. The figure which shows the other structure of the semiconductor light-emitting device of this invention. The figure which shows the other structure of the semiconductor light-emitting device of this invention. The figure which looked at other composition of the semiconductor light-emitting device of the present invention from the top side The figure which looked at other composition of the semiconductor light-emitting device of the present invention from the top side

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor light-emitting device 10 Semiconductor light-emitting device 11 Substrate 12 N-type layer 13 Active layer 14 P-type layer 16 n-side electrode 17 p-side electrode 20 Support 21 Submount 22 n-side extraction electrode 23 p-side extraction electrode 24 n-pole bump 25 P-pole bumps 26, 27 Through-hole 31 Top of connection line 40 Reflecting portion 45 Reflecting portion surface 50 Phosphor layer 55 Top surface

Claims (3)

An extraction electrode provided on the substrate;
A reflective portion provided on the substrate with a reflective surface;
A semiconductor light emitting element coupled with the extraction electrode by a connection line, and fixed at a position where the light emitting surface is lower than the surface of the reflecting portion;
A semiconductor light emitting device comprising a phosphor layer filled with a portion of a flat surface with a top surface ground and higher than the surface of the reflecting portion and surrounded by the substrate and the reflecting portion. Providing an extraction electrode on the base substrate;
Providing a connection line on the extraction electrode;
Connecting a light emitting element to the connection line;
Adhering a reflective portion on the base substrate;
Filling a phosphor on a substrate surrounded by the reflective portion;
Grinding the phosphor;
And a step of cutting the reflecting portion together with the base substrate. Providing an extraction electrode on the base substrate;
Fixing the light emitting element on the base substrate;
Connecting the semiconductor light emitting element and the extraction electrode with a connection line;
Adhering a reflective portion on the base substrate;
Filling a phosphor on a substrate surrounded by the reflective portion;
Grinding the phosphor;
And a step of cutting the reflecting portion together with the base substrate.

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