JP2006073618A - Optical element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element along with its manufacturing method in which an illumination area that occupies the entire element is larger, with excellent mounting characteristics, reliability in electrical connection, and heat radiation characteristics, while using an existing facility and known manufacturing method, with no advanced processing technology required. <P>SOLUTION: Based on a manufacturing process for a semiconductor light emitting element with a wafer-like sapphire substrate 10, an LED element 1 is formed where an n external electrode 17 and p external electrode 18 are provided around a light emitting layer 13. Thus, using an existing facility and a known manufacturing method, an LED element 1 is easily mass-produced in a lump. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element, and in particular, without requiring advanced processing technology, the light emitting area occupying the entire element can be increased while using existing equipment and a known manufacturing method, and is excellent in mountability and electrical connection. The present invention relates to an optical element having high reliability and good heat dissipation and a method for manufacturing the same.

  As a conventional optical element, an LED element (Light Emitting Diode: hereinafter referred to as an LED element) in which a semiconductor crystal such as a group III nitride compound semiconductor is grown on a light-transmitting base substrate such as sapphire is known. Yes. The LED element emits light in the light emitting layer by energizing n-type and p-type nitride compound semiconductor layers (hereinafter referred to as semiconductor layers), and emits light based on the light emission to the outside.

  When energizing the n-type and p-type semiconductor layers of the LED element, a first electrode for energizing the p-type semiconductor layer, which is the uppermost layer of the LED element, is provided and further exposed by etching from the p-type semiconductor layer. It is known that a second electrode is provided on an n-type semiconductor layer and is electrically connected to an external circuit by wire bonding. In such an LED element, since the first electrode is provided on the light extraction surface, extraction of light emitted from the LED element is hindered.

  On the other hand, an LED element has been proposed in which electrical connection with an external circuit is flip-chip bonded via a pump such as Au without using a wire, and light based on light emission in the light emitting layer is extracted from the sapphire substrate side. Yes. In such an LED element, it is necessary to provide the first and second electrodes having an area necessary for bump bonding without causing a short circuit, and thus it is difficult to increase the light emitting area in the entire element. There is an inconvenience.

  In order to solve such a problem, an LED element in which an electrode for applying a voltage to the n-type semiconductor layer and the p-type semiconductor layer of the LED element is provided on the side surface has been proposed (for example, see Patent Document 1). .

As shown in FIG. 1 of Patent Document 1, the LED element described in Patent Document 1 includes insulating layers made of, for example, silicon oxide (SiO ₂ ) on both side surfaces of the laminated portion and both side surfaces of the sapphire substrate. Is formed. One insulating layer is etched at a location in contact with the end face portion of the p-type GaN layer located on the outermost surface of the stacked portion. In addition, the other insulating film is etched at a location where it comes into contact with the end face portion of the n-type GaN layer, and an electrode made of a conductive film that conducts to the p-type GaN layer and the n-type GaN layer via the etched portion. Is provided on the outer surface of the insulating layer.

According to the LED element described in Patent Document 1, since the electrode is not formed on the surface portion of the laminated portion of the semiconductor light emitting element, the light emitted from the light emitting layer is efficiently emitted upward. Moreover, the area of the light emitting layer is not reduced by etching, and the light emitting area of the light emitting layer can be formed in the same large area as the sapphire substrate. Therefore, the amount of light emitted upward from the outermost surface portion of the laminated portion can be increased, and the light emission intensity can be increased.
JP-A-8-102552 ([0024] to [0032], FIG. 1)

  However, according to the LED element described in Patent Document 1, a laminated portion is formed on a sapphire substrate, and this is diced and divided into chips, and then the insulating layer is etched, and p-type GaN is passed through the etched portion. Since the electrode which conducts to the layer and the n-type GaN layer is provided, there is a problem that it is difficult to perform mass mass production because it requires fine and advanced processing technology for each chip. Also, even if the electrical connectivity is improved, if sufficient heat dissipation is not obtained for the heat generated by light emission, the light emission efficiency will not improve, and high brightness and high output will be realized. I can't.

  Therefore, the object of the present invention is to increase the light emitting area in the entire device using existing equipment and a known manufacturing method without requiring advanced processing technology, and is excellent in mountability and reliability of electrical connection. It is an object of the present invention to provide an optical element having a high performance and a good heat dissipation property and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides a semiconductor layer including a light emitting layer and n-side and p-side electrodes provided on the periphery of the semiconductor layer having a width smaller than the entire width of the element and supplying power to the light emitting layer. The optical element characterized by having these.

  In order to achieve the above object, the present invention provides a semiconductor layer forming step of forming a semiconductor layer including a light emitting layer by laminating a semiconductor material on a wafer-like base substrate, and a predetermined width from the surface of the semiconductor layer. And a semiconductor layer removing step of removing the semiconductor layer so as to have a depth to form an exposed portion, and an electrode forming step of forming electrodes for supplying power to the n layer and the p layer of the semiconductor layer in the exposed portion, There is provided an optical element manufacturing method including an element forming step of cutting the base substrate and the semiconductor layer into an element so that the electrode is exposed at the periphery of the element.

  According to the present invention, the light emitting area occupying the entire element can be increased, and it is excellent in mountability without requiring sophisticated and expensive equipment, the reliability of electrical connection is large, and even if the size is large, it is good. Heat dissipation can be imparted.

(First embodiment)
(Configuration of LED element 1)
1A and 1B show an LED element according to a first embodiment, in which FIG. 1A is a longitudinal sectional view cut in a diagonal direction of the element, and FIG. 1B is a plan view seen from the light extraction surface side of the LED element.

  As shown in FIG. 1A, the LED element 1 is obtained by growing a group III nitride compound semiconductor on a sapphire substrate 10 and includes an AlN buffer layer 11 and a group III on the sapphire substrate 10. An n-GaN layer 12 composed of a nitride compound semiconductor layer, a light emitting layer 13, a p-GaN layer 14, and a p-contact electrode 15 for diffusing current in the p-GaN layer 14 are sequentially stacked, and GaN An insulating layer 16 having optical transparency on the side surface of the semiconductor layer 100, an n external electrode 17 provided on the n-GaN layer 12 exposed by etching from the p-GaN layer 14 to the n-GaN layer 12, and The p external electrode 18 provided on the side surface of the GaN-based semiconductor layer 100 from the AlN buffer layer 11 to the p contact electrode 15 on the sapphire substrate 10, and the n external electrode 1 And an insulating layer 19 having light transmittance that covers the element surface of the over the p external electrodes 18 from.

  In the following description, the portion from the AlN buffer layer 11 to the insulating layer 19 on the sapphire substrate 10 is a GaN-based semiconductor layer 100. The emission wavelength of light emitted from the light emitting layer 13 of the LED element 1 is 460 nm.

  The formation method of the group III nitride compound semiconductor layer is not particularly limited, but the well-known metal organic chemical vapor deposition method (MOCVD method), molecular beam crystal growth method (MBE method), halide vapor phase epitaxy method (HVPE method). ), A sputtering method, an ion plating method, an electron shower method, or the like. In addition, as a structure of a LED element, the thing of a homo structure, a hetero structure, or a double hetero structure can be used. Furthermore, a quantum well structure (single quantum well structure or multiple quantum well structure) can also be adopted.

  The p-contact electrode 15 is for diffusing current to the p-GaN layer 14 and providing good electrical connectivity with the outside. In this embodiment, the p-contact electrode 15 is formed of Rh having light reflectivity. ing. Note that the p-contact electrode 15 is made of a light-transmitting material such as ITO (Indium Tin Oxide), ZnO, Au / Co, or Ni / Ti that has optical transparency as long as the material can make ohmic contact with the p-GaN layer 14. It may be formed.

The insulating layer 16 is made of SiO ₂ and is provided so as to cover the side surface of the GaN-based semiconductor layer, thereby preventing the n external electrode 17 and the p external electrode 18 from being short-circuited with the GaN-based semiconductor layer 100. It should be noted that other insulating materials such as SiN can be used instead of SiO ₂ .

  The n external electrode 17 is made of V / Al, and the p external electrode 18 is made of Ti. These external electrodes are formed so as to be exposed at the periphery of the element from the element side surface to the p contact electrode 15 formation surface in order to enable electrical bonding on the element side surface and surface mounting on the p contact electrode 15 side. Yes. The element periphery here is, for example, the side surface of the LED element 1 shown in FIG. 1 and the edge of the surface of the GaN-based semiconductor layer 100 on which the insulating layer 19 is provided. The formation length is provided on the entire side surface of two sides adjacent to the n external electrode 17, and the p external electrode 18 is provided on a part of the two sides opposite to the two sides on which the n external electrode 17 is formed. The region where 18 is formed is provided to be smaller than the n external electrode 17. The surface may be solder plated.

(Manufacturing process of LED element 1)
FIGS. 2A to 2D are diagrams showing the LED element manufacturing process (up to the process of providing the insulating layer 16 on the side surface of the LED element) according to the first embodiment. In the following description, a semiconductor layer is formed on the wafer-like sapphire substrate 10 and a manufacturing process for separating the element into an element is illustrated, with the focus on the portion that becomes the LED element 1. ing.

(GaN-based semiconductor layer formation process)
First, as shown in FIG. 2A, an AlN buffer layer 11, a GaN-based semiconductor layer 100, and a p-contact electrode 15 are formed on a wafer-like sapphire substrate 10 serving as a base substrate for crystal growth by MOCVD.

(First etching process)
Next, as shown in FIG. 2B, dry etching is performed on the GaN-based semiconductor layer 100, and the n-GaN layer 12 is formed from the surface of the GaN-based semiconductor layer 100 in a region where the n external electrode and the p external electrode are provided. Then, the exposed portion 12A is provided on the side surface of the GaN-based semiconductor layer 100 by removing the semiconductor layer in the stacking direction. The p contact electrode 15 may be formed by forming a photoresist on the exposed portion 12A to form the p contact electrode 15 and then removing the photoresist.

(Formation process of insulating layer 16)
Next, as shown in FIG. 2C, an insulating layer 16 made of a SiO ₂ -based material is provided on the etched GaN-based semiconductor layer 100 by an evaporation method.

(Second etching process)
Next, as shown in FIG. 2D, a photoresist is applied to the GaN-based semiconductor layer 100 on which the insulating layer 16 is formed, etching is performed, and then the photoresist is removed, whereby the GaN-based semiconductor layer 100 is removed. By removing the insulating layer 16 provided on the portion other than the side surface, a part of the exposed portion 12A and the p-contact electrode 15 are exposed.

  FIGS. 3A to 3C are views showing the LED element manufacturing process (from the electrode forming process to completion) according to the first embodiment.

(Process for forming p-contact electrode 15)
In the electrode formation step, first, as shown in FIG. 3A, an n external electrode 17 made of V / Al is formed on the exposed portion 12A on the n external electrode side by vapor deposition. Next, the p external electrode 18 made of Ti is formed by vapor deposition on the exposed portion 12A on the p external electrode side. The material constituting the n external electrode 17 may be any material that can be in ohmic contact with the n-GaN layer 12 and may be formed of a material other than the above-described V / Al, for example, Ti. Moreover, the material which comprises the p external electrode 18 should just have the characteristic which can be electrically connected with the p contact electrode 15, and can also be formed with materials other than above-mentioned Ti, for example, Al.

  Further, both the n external electrode 17 and the p external electrode 18 can be formed of Ti. In this case, the n external electrode 17 and the p external electrode 18 can be collectively provided in the same process, and the manufacturing process can be simplified.

(Electrode formation process)
Next, as shown in FIG. 3B, an insulating layer 16 made of a SiO ₂ -based material is formed over the upper surface of the GaN-based semiconductor layer 100 including the electrode portion, the formation region of the n external electrode 17 and the p external electrode 18. Provided by vapor deposition.

(Formation process of the insulating layer 19)
Next, a photoresist is applied to the GaN-based semiconductor layer 100 on which the insulating layer 16 is formed, etching is performed, and then the photoresist is removed to prevent a short circuit between the n external electrode 17 and the p external electrode 18 and as a protective layer. An insulating layer 19 is provided. The insulating layer 19 is removed from the n outer electrode 17 and the p outer electrode 18 at the periphery of the element.

(Element fabrication process)
Next, the GaN-based semiconductor layer 100 having the n external electrode 17 and the p external electrode 18 and the sapphire substrate 10 are cut to an element size by a dicer (not shown) to form the LED element 1 as shown in FIG. Is done. In addition, the cutting | disconnection in elementization can also process by a scribe etc. other than the thing by a dicer, for example.

  4A and 4B show a mounting state of the LED element according to the first embodiment, in which FIG. 4A shows an example of flip chip mounting on a substrate, and FIG. 4B shows a flip chip mounting state on a substrate provided with a recess. It is. As shown in FIG. 4A, the LED element 1 is bonded and fixed to the surface of a ceramic substrate 23 having a wiring pattern 22 on the surface by an epoxy insulating adhesive 41. The n external electrode 17 and the p external electrode 18 are reflow bonded to the wiring pattern 22 with solder 20A. The insulating adhesive 41 may be other as long as it has good thermal conductivity. The adhesive between the LED element 2 and the substrate 23 may be a paste having no adhesiveness or a sheet-like form. Any material can be used as long as it has the properties. Moreover, it is more desirable if heat resistance is high and adhesiveness is favorable.

  If the substrate 23 can secure the insulation with the wiring pattern 22, the substrate 23 is replaced with an insulating substrate such as a flexible substrate made of a laminate of ceramics, glass epoxy, polyimide and conductive foil, and heat conductivity such as Cu and Al. It is also possible to use a conductive substrate obtained by subjecting a metal material excellent in insulation to an insulation treatment.

  If the short circuit between the n external electrode 17 and the p external electrode 18 does not occur, the LED element 1 may be supported and fixed to the substrate 23 with a conductive material instead of the insulating adhesive 41. good. As such a material, for example, a conductive paste made of a silicone resin containing filler of Au, Cu, or Al can be used.

  Further, the electrical connection to the wiring pattern 22 by the n external electrode 17 and the p external electrode 18 is not limited to that by the solder 20A. For example, a conductive adhesive (for example, Ag paste, Au, Cu, An epoxy resin containing a conductive filler such as Al) may be used.

  Also, as shown in FIG. 4B, it is possible to prepare a substrate 23 having a recess 23A for positioning an element and fix it so that the p contact electrode 15 formation side of the LED element 1 is inserted into the recess 23A. . An insulating adhesive 41 is applied to the inside of the recess 23A to bond and fix the p contact electrode 15 forming side of the LED element 1. Further, the n external electrode 17 and the p external electrode 18 are reflow bonded to the wiring pattern 22 by the solder 20A as in FIG.

(Operation of LED element 1)
Below, operation | movement of the LED element 1 of 1st Embodiment shown to Fig.4 (a) is demonstrated.

  When the wiring pattern 22 is connected to a power source (not shown) and energized, the light emitting layer 13 is energized via the n external electrode 17 and the p external electrode 18 of the LED element 1. The light emitting layer 13 emits blue light based on energization. Of the blue light, the light emitted toward the sapphire substrate 10 is transmitted through the sapphire substrate 10 and emitted to the outside. Further, the heat generated based on the light emission of the LED element 1 is conducted to the substrate 23 through the insulating adhesive 41.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(1) Since the LED element 1 in which the n external electrode 17 and the p external electrode 18 are provided around the light emitting layer 13 is formed based on the manufacturing process of the semiconductor light emitting element for the wafer-like sapphire substrate 10, the existing equipment is used. In addition, the LED elements 1 can be easily manufactured in large quantities using a known manufacturing method.

(2) Since the n external electrode 17 and the p external electrode 18 are provided on the periphery of the LED element 1 by removing the side surface of the GaN-based semiconductor layer 100 instead of the light extraction surface, the light generated in the light emitting layer 13 is n The external electrode 17 and the p external electrode 18 are hardly obstructed. Further, the light emitting area of the light emitting layer 13 can be increased with the same element size based on the arrangement of the external electrodes, and the high luminance LED element 1 with improved light emission intensity and good light extraction can be obtained.

(3) Either flip-chip type mounting or face-up type mounting can be electrically connected to the wiring pattern 22 and the like, and a mounting mode can be selected according to the application, and does not correspond to any mounting mode. For example, mounting such that one side surface of the LED element 1 is electrically and mechanically joined is possible, and various mounting forms can be provided.

(4) Since the wire bonding space and the n-electrode bump space serving as a non-light emitting portion can be eliminated or made extremely small, a sufficient light emitting area / light emitting element even with a small size LED element 1 The area ratio can be obtained. Therefore, the LED element 1 which has the electrode space | interval close | similar to element width | variety as a smaller-sized LED element is realizable. For example, it is possible to manufacture the LED element 1 having a practical light emitting area of 0.1 mm square. If both the n-side and p-side electrodes for mounting Au stud bumps on the lower surface of the LED element 1 are provided, an electrode having a diameter of about 0.1 mm is required for each, and 0.1 × 0.2 mm ² It is difficult to make the LED element 1 of less than.

(5) Since the n external electrode 17 and the p external electrode 18 of the LED element 1 are provided so as to be continuous with the two sides of the element side surface, the bonding area by reflow bonding of the solder 20A can be increased, and stable mounting property And good heat dissipation is obtained. In addition, reliable mounting is possible without requiring high positioning accuracy like bump bonding. The n external electrode 17 and the p external electrode 18 do not necessarily have to be continuous on two sides as shown in FIG. 1B, and may be discontinuous.

(6) Since the GaN-based semiconductor layer 100 side is in surface contact with the substrate 23 and the n external electrode 17 and the p external electrode 18 are electrically bonded by the solder 20A when the LED element 1 is flip-chip bonded, the bonding strength is high. become. Further, heat conduction from the GaN-based semiconductor layer 100 to the substrate 23 can be performed without using a sapphire substrate, and heat dissipation is excellent. Moreover, since sealing resin does not intervene in the joining interface of LED element 1, joining peeling by thermal expansion does not arise and it is excellent in reliability.

  In the first embodiment, a blue LED element using a group III nitride compound semiconductor has been described. However, the LED element 1 is not limited to a blue LED element and generates other emission colors. Also good. The semiconductor material may also be a semiconductor material other than the group III nitride compound semiconductor.

  Further, for example, a GaN substrate can be used instead of the sapphire substrate 10 as a base substrate on which the group III nitride compound semiconductor is grown.

  Further, as described with reference to FIG. 4A, when the LED element 1 is used in a flip chip type mounting form with the p contact electrode 15 side of the LED element 1 as a mounting surface, the LED element 1 in which the p contact electrode 15 is formed of ITO is used. By using this and surface-mounting the substrate 23 made of a light-transmitting material such as glass so that the p-contact electrode 15 side becomes the mounting surface, light can be extracted to the substrate 23 side. Become.

(Second Embodiment)
(Configuration of LED element 1)
5A and 5B show an LED element according to the second embodiment, where FIG. 5A is a plan view, FIG. 5B is a cross-sectional view taken along the line AA in FIG. 5A, and FIG. It is the top view seen from the sapphire substrate side to show. This LED element 1 is formed in a long shape so as to have five light emitting regions, and has a plurality of n external electrodes 17 and p external electrodes 18, and the p external electrode 18 is an electrode as shown in FIG. It is connected to the p-contact electrode 15 made of Rh via the connecting portion 18A. This long LED element 1 is also configured so that the n external electrode 17 and the p external electrode 18 have a bonding width that can be taken out to the side surface to obtain sufficient bonding properties. 17 and the p external electrode 18 are disposed on the opposing long sides of the LED element 1. In addition, n external electrodes 17 are exposed at the opposing short sides of the LED element 1.

  The n external electrode 17 and the p external electrode 18 are flip-chip bonded to a wiring pattern provided on a substrate (not shown) by solder 20A as shown in FIG.

(Effect of the second embodiment)
According to the second embodiment, in addition to the preferable effect of the first embodiment, the LED element 1 can be easily wired even if the LED element 1 has a long structure. Can be provided. In addition, uniform and good electrical bondability can be obtained by the n external electrode 17 and the p external electrode 18 provided on the side surface of the LED element 1 with a predetermined bonding width.

  Further, as shown in FIG. 5A, also in the element structure provided with a plurality of light emitting regions, the mounting surface (not shown) from the GaN-based semiconductor layer 100 side as described in the effect of the first embodiment. ) Is quickly conducted, so that it is possible to realize a structure with sufficient heat dissipation when the output is increased.

  In addition, in 2nd Embodiment, although the elongate LED element 1 provided with five light emission area | regions was demonstrated, it sets arbitrarily about the number, size, and shape of a light emission area | region according to a use etc. be able to.

  Further, the LED element 1 described above is not limited to the application by flip chip bonding shown in FIG. 5C, and the p contact electrode 15 is formed of a light-transmitting material such as ITO, ZnO, Au / Co, Ni / Ti, or the like. And it can also be used as the face-up type LED element 1 which mounts the sapphire substrate 10 side on a mounting surface.

(Third embodiment)
(Configuration of LED element 1)
6A and 6B show an LED element according to the third embodiment, wherein FIG. 6A is a plan view and FIG. 6B is a cross-sectional view taken along the line BB in FIG. This LED element 1 is a large-size (1 mm square) LED element 1 having an n external electrode 17 extending in a comb shape from the side surface of the element into a light emitting region, and a p contact electrode 15 and a p external electrode 18. A plurality of electrode connection portions 18A to be connected are provided. Also in the LED element 1 of the third embodiment, the n external electrode 17 and the p external electrode 18 are exposed to face the element side surface and are formed over the entire side surface.

  The p-contact electrode 15 can be made of a light-transmitting material such as ITO when used as the LED element 1 that extracts light from the GaN-based semiconductor layer 100 side. Moreover, when using as LED element 1 which takes out light from the sapphire substrate 10 side, in addition to the above translucent material, the electroconductive material which has light reflectivity, such as Rh, can also be used.

(Effect of the third embodiment)
According to the third embodiment, since the n external electrode 17 and the p external electrode 18 are not provided on the light extraction surface and are arranged on the side surface, the large LED element 1 has a light extraction area from the inside of the element. The LED element 1 with good light extraction property can be obtained. Further, since the n external electrode 17 and the p external electrode 18 are formed so as to face the side surfaces of the element, the junction area with the outside can be increased, and the junction strength, heat dissipation, and current dispersibility can be improved. Further, the mounting can be reliably performed without the need for troublesome adjustments such as positioning at the time of mounting compared to mounting using Au bumps.

  In addition, the large-size LED element 1 generates a larger amount of heat than the standard-size LED element 1, but the n external electrode 17 and the p external electrode 18 are arranged on the side surface, so that the entire surface is mounted on the mounting substrate or the like. It is possible to make it adhere | attach, and it can ensure sufficient heat dissipation by it.

  In the third embodiment, the n external electrode 17 and the p external electrode 18 are arranged so as to face the side surface of the LED element 1 and are exposed over the entire width. If the external electrode 18 is configured to be exposed on the side surface of the LED element 1 without being short-circuited, it is possible to form these electrodes at arbitrary locations and sizes.

  Further, in the third embodiment, the LED element 1 provided with nine electrode connection portions 18A has been described. However, the number, size, and shape of the electrode connection portions 18A are arbitrarily set according to applications and the like. be able to.

(Fourth embodiment)
(Configuration of LED element 1)
FIG. 7 is a plan view showing an LED element according to the fourth embodiment. The LED element 1 has a configuration in which an n external electrode 17 and a p external electrode 18 are provided along the side surface of the large-size LED element 1. Even with such a configuration, as described in the third embodiment, it is possible to improve the bonding strength, the heat dissipation, and the current dispersibility.

(Fifth embodiment)
(Configuration of LED element 1)
FIG. 8 is a plan view showing an LED element according to the fifth embodiment. In this LED element 1, an n external electrode 17 and a p external electrode 18 are arranged on the side surface of the large-sized LED element 1, and the n electrode 17B and the p electrode 18B are further extended in a direction from the side surface toward the center of the LED element 1. It has a structure formed in a comb shape. Even with such a configuration, as described in the third embodiment, it is possible to improve the bonding strength and heat dissipation. Further, by providing the n electrode 17B and the p electrode 18B extending in a comb shape from the n external electrode 17 and the p external electrode 18, it is possible to further improve the uniform dispersibility of the current in the light emitting region.

(Sixth embodiment)
(Wiring structure of LED element 1)
FIG. 9 is a diagram showing a mounted state in which LED elements are connected to copper leads as the sixth embodiment. The copper lead 21 is formed by previously processing a copper alloy into a predetermined lead shape by pressing or the like. The n external electrode 17 and the p external electrode 18 are formed on the side surface of the LED element 1 based on solder bonding by the solder plating 20. It is connected to the. The LED element 1 has a p-contact electrode 15 made of Rh, and thereby has a configuration for extracting light from the sapphire substrate 10 side to the outside. The n-GaN layer 12 is in surface contact with the copper leads 21 and 21 that feed power to the cathode side and the anode side on the side surface, but no short circuit occurs because the contact surface is not in ohmic contact.

  In FIG. 9, the pair of copper leads 21 is configured to serve both as an electrical connection and a mechanical support, and the LED element 1 is supported by the copper leads 21 and suspended. In addition, it is preferable to set it as the structure which seals LED element 1 and the copper lead 21 integrally with sealing materials, such as an epoxy resin, from the point of protection of the LED element 1 and the copper lead 21, and an improvement in light extraction. Further, as a material for electrically bonding the copper lead 21 and the LED element 1, a conductive bonding material other than the above-described solder plating 20 can also be used. As such a conductive bonding material, for example, an Ag adhesive or an epoxy adhesive containing a conductive filler can be used.

(Operation of LED element 1)
Below, operation | movement of the LED element 1 shown in FIG. 9 is demonstrated.

  When the copper lead 21 is connected to a power source (not shown) and energized, the light emitting layer 13 is energized via the n external electrode 17 and the p external electrode 18 of the LED element 1. The light emitting layer 13 emits blue light based on energization. Of the blue light, the light emitted to the sapphire substrate 10 side is emitted from the sapphire substrate 10 to the outside. In addition, light emitted from the blue light toward the p contact electrode 15 is reflected by the p contact electrode 15 and emitted from the sapphire substrate 10 to the outside.

(Effect of 6th Embodiment)
According to the sixth embodiment, the following effects can be obtained.
(1) Since the n external electrode 17 and the p external electrode 18 are not provided on the light extraction surface, but are provided on the side surface of the LED element 1, both face-up type and flip chip type mounting forms as shown in FIG. Implementation that does not fall under is also possible. As a result, thin and compact mounting is possible, and the sealing performance can be improved by the sealing material and the package can be downsized. Further, if the copper lead 21 is thinner than the LED element 1, it is more desirable because light extraction from the side surface can be further improved.

(2) Since the copper lead 21 having a good thermal conductivity is disposed on the side surface of the element, the heat based on the heat is generated without inhibiting the external emission of the light generated based on the light emission of the LED element 1. Heat is quickly radiated through 100 and solder plating 20.

  In the sixth embodiment, the LED element 1 has the p contact electrode 15 made of Rh. However, by providing the p contact electrode 15 made of a translucent material such as ITO, the sapphire substrate 10 side and Light can be extracted from both the GaN-based semiconductor layer 100 side.

(Other connection configuration of LED element 1)
FIG. 10 shows another mounting state of the LED element according to the seventh embodiment, (a) is a longitudinal sectional view showing the first mounting state, and (b) is a longitudinal section showing the second mounting state. FIG.

In the first mounting state shown in FIG. 10A, the LED element 1 has a p-contact electrode 15 made of a light-transmitting material such as ITO, and the insulating substrate 23 made of Al ₂ O _{3 on the} sapphire substrate 10 side. The n external electrode 17 and the p external electrode 18 are electrically connected to a wiring pattern 22 provided on the surface of the substrate 23 by solder 20A.

  As the solder 20A, for example, a conductive adhesive such as an Ag paste can be used instead. Further, as another conductive adhesive, an epoxy adhesive containing a conductive filler or the like may be used.

  Further, the conductive adhesive may be light transmissive. For example, when a conductive adhesive in which a conductive filler is contained in a transparent epoxy resin is used, light can be extracted from the side surface of the LED element 1.

  The substrate 23 may be light transmissive. In this case, light can be extracted from the sapphire substrate 10 side to the substrate 23 in addition to light extraction from the GaN-based semiconductor layer 100 side.

  The substrate 23 may be formed of a conductive material such as Cu or Al. In this case, although it is necessary to provide an insulating layer on the surface so as not to cause a short circuit through the substrate 23, it is effective to select a conductive material such as metal in order to ensure heat dissipation.

  The second mounting state shown in FIG. 10B is different from the first mounting state in the configuration in which the LED element 1 is accommodated in the recess 23 </ b> A formed on the substrate 23. The recessed portion 23A has an inclined surface 23B, and a space is formed around the accommodated LED element 1. The LED element 1 is accommodated in the recess 23 </ b> A so that the amount of protrusion from the surface of the substrate 23 is suppressed, and a pair of wiring patterns is formed by the solder 20 </ b> A filled in the space between the inclined surface 23 </ b> B and the LED element 1. 22 is electrically connected.

  Note that the substrate 23 illustrated in FIG. 10B may be formed using a metal material having light reflectivity. In this case, although it is necessary to provide an insulating layer on the surface, it is possible to extract light emitted in the direction of the side surface of the LED element 1 using the inclined surface 23B as a reflection surface based on the reflection. The solder 20A may be a light-transmitting conductive adhesive. In this case, light can be extracted at the electrical joint portion.

(Effect of 7th Embodiment)
(1) In the first mounting state, the n external electrode 17 and the p external electrode 18 provided on the side surface of the LED element 1 are electrically joined by the solder 20A, so that the light from the GaN-based semiconductor layer 100 The extraction area can be increased. In addition to the solder 20 </ b> A, electrical bonding on the side surface of the element can be performed by using a conductive adhesive or the like, and an appropriate bonding method can be selected according to the application. Further, when the substrate 23 is formed of a light transmissive material, light extraction from the substrate 23 side can be realized.

(2) In the second mounting state, by embedding the LED element 1 in the substrate 23 having the recess 23A, in addition to the preferable effects of the first mounting state, the LED element 1 can be easily positioned and the substrate A compact package can be realized by suppressing the amount of protrusion of the element from the surface 23. Further, since the inclined surface 23B is provided in the recess 23A, the light radiated to the side surface of the element can be reflected by the inclined surface 23B and emitted externally.

(Eighth embodiment)
(Configuration of LED element 1)
FIG. 11 is a longitudinal sectional view showing a mounted state of the LED element according to the eighth embodiment. This LED element 1 is different from the LED element 1 of FIG. 4A in the configuration in which the sapphire substrate 10 of the LED element 1 described in FIG.

  The LED element 1 is obtained by lifting off the sapphire substrate 10 and the AlN buffer layer 11 by irradiating laser light from the sapphire substrate 10 side. Note that the AlN buffer layer 11 may remain on the surface of the n-GaN layer 12 with the lift-off, and in this case, it is preferable to remove the AlN buffer layer 11 by acid cleaning.

  The LED element 1 emits light in the light emitting layer 13 by applying a voltage to the light emitting layer 13 through a n external electrode 17 and a p external electrode from a power source (not shown) connected to the wiring pattern 22. Of the light based on light emission, the light emitted to the n-GaN layer 12 side is emitted from the n-GaN layer 12 to the outside. Further, the light emitted to the p contact electrode 15 side is reflected by the p contact electrode 15 formed of Rh and is emitted from the n-GaN layer 12 to the outside.

  The p-contact electrode 15 is formed of a light-transmitting material such as ITO, and the substrate 23 is formed of a light-transmitting material, whereby light extraction and heat dissipation from the GaN-based semiconductor layer 100 side that is the mounting side. It is good also as a structure which can perform.

(Effect of 8th Embodiment)
According to the eighth embodiment, light can be extracted from the n-GaN layer 12 of the LED element 1 that is flip-chip bonded, thereby reducing the confinement light in the layer that is not emitted from the GaN-based semiconductor layer 100 to the outside. It becomes possible to form a light emitting device having excellent external radiation efficiency.

  In addition, since the n external electrode 17 and the p external electrode 18 are disposed on the side surface of the LED element 1, the LED element 1 can be formed thin, and it is possible to avoid the restrictions associated with downsizing and shape of the mounting target. Further, the heat dissipation to the substrate 23 through the insulating layer 19 is also excellent.

  From the viewpoint of protecting the LED element 1, it is preferable to cover the surface of the n-GaN layer 12 with a light-transmitting material or seal the wiring pattern 22 and the substrate 23 together with a sealing member such as an epoxy resin.

  Moreover, it is good also as a structure which reduces the confinement light in a layer and improves external radiation efficiency by giving shape processing, such as an unevenness | corrugation, to the surface of the n-GaN layer 12. FIG.

(Ninth embodiment)
(Configuration of LED element 1)
FIG. 12 is a longitudinal sectional view showing a mounted state of the LED element according to the ninth embodiment. This LED element 1 is formed by bonding and fixing a glass member 30 that is a high refractive index material having a wiring pattern 22 on the n-GaN layer 12 side of the LED element 1 described in FIG. It is configured. The p contact electrode 15 of the LED element 1 is formed of Rh.

  As the light-transmitting adhesive 42, an epoxy-based adhesive that does not interfere with the transmission of light emitted from the LED element 1 is used.

  The n external electrode 17 and the p external electrode 18 are electrically connected to the wiring pattern 22 by an adhesive 24 having optical transparency and conductivity. As described above, an epoxy resin containing a conductive filler can be used for the adhesive 24.

  The LED element 1 emits light in the light emitting layer 13 by applying a voltage to the light emitting layer 13 through a n external electrode 17 and a p external electrode from a power source (not shown) connected to the wiring pattern 22. Of the light based on light emission, the light emitted to the n-GaN layer 12 side enters the glass member 30 through the light-transmitting adhesive 42 from the n-GaN layer 12 and is emitted from the glass member 30 to the outside. Further, the light emitted to the p contact electrode 15 side is reflected by the p contact electrode 15 formed of Rh, enters the glass member 30 from the n-GaN layer 12, and is emitted from the glass member 30 to the outside.

  Further, a part of the light that is totally reflected at the interface with the glass member 30 and propagates laterally through the GaN-based semiconductor layer 100 is radiated to the outside by entering the adhesive 20 </ b> B from the side surface of the LED element 1.

(Effect of 9th Embodiment)
According to the ninth embodiment, by adhering the LED element 1 to the glass member 30 through the light transmissive adhesive 42, it is possible to provide a light source suitable for the use of transmissive illumination such as a backlight.

  In the ninth embodiment, the p-contact electrode 15 is made of Rh having light reflectivity. However, the p-contact electrode 15 is made of a light-transmitting material such as ITO, so that light can be extracted also from the GaN-based semiconductor layer 100 side. Also good.

(Configuration of LED element 1)
FIG. 13 shows a large-size (1 mm square) LED element according to the tenth embodiment, wherein (a) is a longitudinal sectional view, and (b) is a plan view as viewed from the insulating layer forming surface side of (a). It is.

  This LED element 1 has a hole 1A formed from the GaN-based semiconductor layer 100 to the n-GaN layer 12 at the center of the element as shown in FIG. 5B, and is exposed inside the hole 1A by etching. An n external electrode 17 provided so as to cover the n-GaN layer 12 and a p external electrode 18 provided so as to cover the outer portion of the GaN-based semiconductor layer 100 and electrically connected to the p contact electrode 15. I have. The p contact electrode 15 of the LED element 1 is formed of Rh.

  The LED element 1 can be flip-chip bonded to a substrate having a wiring pattern corresponding to the pattern of the solder plating 20 corresponding to the n external electrode 17 and the p external electrode 18.

(Effect of 10th Embodiment)
According to the tenth embodiment, the n external electrode 17 is provided in the center of the element and the p external electrode 18 is provided on the outer periphery of the element. Therefore, even in the large-size LED element 1, the light emitting layer 13 is spread over the entire surface. Light can be emitted uniformly.

  Further, by flip chip bonding the LED element 1 of the tenth embodiment, good light emission characteristics can be obtained while ensuring excellent heat dissipation to the mounting substrate and the like.

  Also in the tenth embodiment, when used as the face-up LED element 1, the p-contact electrode 15 can be formed of a light-transmitting material such as ITO. Excellent wire bondability can be obtained while minimizing the decrease in light extraction performance. .

  In each of the above-described embodiments, the LED element is described as the optical element. However, the present invention is not limited to the LED element, and can be applied to other optical elements such as a solar cell and a light receiving element, and a manufacturing method thereof.

The LED element which concerns on 1st Embodiment is shown, (a) is the longitudinal cross-sectional view cut | disconnected in the element diagonal direction, (b) is the top view seen from the light extraction surface side of the LED element. (A) to (d) is a figure which shows the manufacturing process (until the process of providing the insulating layer 16 on the side surface of an LED element) of the LED element which concerns on 1st Embodiment. (A) to (c) is a figure which shows the manufacturing process (from an electrode formation process to completion) of the LED element which concerns on 1st Embodiment. The LED element mounting state which concerns on 1st Embodiment is shown, (a) is the example of the flip chip mounting to a board | substrate, (b) is a figure which shows the flip chip mounting state to the board | substrate which provided the recessed part. The LED element which concerns on 2nd Embodiment is shown, (a) is a top view, (b) is sectional drawing in the AA part of (a), (c) is the sapphire substrate side which shows the state at the time of solder connection It is the top view seen from. The LED element which concerns on 3rd Embodiment is shown, (a) is a top view, (b) is sectional drawing in the BB part of (a). It is a top view which shows the LED element which concerns on 4th Embodiment. It is a top view which shows the LED element which concerns on 5th Embodiment. It is a figure which shows the mounting state which connected the LED element to the copper lead as 6th Embodiment. The other mounting state of the LED element which concerns on 7th Embodiment is shown, (a) is a longitudinal cross-sectional view which shows a 1st mounting state, (b) is a longitudinal cross-sectional view which shows a 2nd mounting state. It is a longitudinal cross-sectional view which shows the mounting state of the LED element which concerns on 8th Embodiment. It is a longitudinal cross-sectional view which shows the mounting state of the LED element which concerns on 9th Embodiment. The large size (1 mm square) LED element which concerns on 10th Embodiment is shown, (a) is a longitudinal cross-sectional view, (b) is the top view seen from the insulating layer formation surface side of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LED element, 1A ... Hole part, 10 ... Sapphire substrate, 11 ... AlN buffer layer, 12 ... n-GaN layer, 12A ... Exposed part, 13 ... Light emitting layer, 14 ... p-GaN layer, 15 ... p contact electrode , 16 ... insulating layer, 17 ... n external electrode, 18 ... p external electrode, 18A ... electrode connection part, 19 ... insulating layer, 20 ... solder plating, 21 ... copper lid, 22 ... wiring pattern, 23 ... substrate, 24 ... Wire, 25 ... Insulating adhesive, 26 ... Metal thin film, 30 ... Glass member, 40 ... Rh electrode, 100 ... GaN-based semiconductor layer

Claims (13)

  An optical element comprising: a semiconductor layer including a light emitting layer; and an n-side electrode and a p-side electrode provided on a periphery of the semiconductor layer having a width smaller than the entire width of the element and supplying power to the light emitting layer.   The optical element according to claim 1, wherein the peripheral edge is formed by removing the semiconductor layer in the same direction as the stacking direction of the semiconductor layers.   2. The electrode according to claim 1, wherein the electrode is electrically connected to the n layer or the p layer through an insulating layer made of a light transmissive material having a refractive index different from that of the semiconductor layer. Optical element.   The electrode is mounted by electrically bonding a portion exposed to the peripheral edge of the semiconductor layer in a state where a sapphire substrate that is a base substrate of the semiconductor layer is in close contact with a mounting surface. The optical element according to claim 1.   2. The optical element according to claim 1, wherein the electrode is electrically connected to an external circuit at a portion exposed to the periphery of the semiconductor layer in a state where the semiconductor layer is in close contact with a mounting surface.   The optical element according to claim 1, wherein the electrode includes an n-electrode provided in a hole provided in the semiconductor layer and a p-electrode provided on an outer portion of the semiconductor layer.   The optical element according to claim 1, wherein the semiconductor layer is made of a group III nitride compound semiconductor. A semiconductor layer forming step of forming a semiconductor layer including a light emitting layer by laminating a semiconductor material on a wafer-like base substrate;
Removing the semiconductor layer so as to have a predetermined width and depth from the surface of the semiconductor layer to form an exposed portion; and
Forming an electrode for supplying power to the n layer and the p layer of the semiconductor layer in the exposed portion;
A method of manufacturing an optical element, comprising: an element forming step of cutting the base substrate and the semiconductor layer into an element so that the electrode is exposed at the periphery of the element. The electrode forming step includes an insulating layer forming step of forming an insulating layer that covers surfaces of the semiconductor layer and the exposed portion;
An insulating layer removing step of removing the insulating layer so as to ensure insulation between the n layer and the p layer to form an electrode formation region corresponding to the n layer and the p layer;
The method for manufacturing an optical element according to claim 8, further comprising an external electrode forming step of forming external electrodes connected to the n layer and the p layer, respectively, in the electrode forming region.   10. The external electrode forming step includes a first external electrode forming step connected to the n layer and a second external electrode forming step connected to the p layer. Of manufacturing the optical element.   10. The external electrode forming step includes simultaneously performing a first external electrode forming step connected to the n layer and a second external electrode forming step connected to the p layer. The manufacturing method of the optical element of description.   9. The method of manufacturing an optical element according to claim 8, wherein in the semiconductor layer forming step, the contact electrode laminated on the p layer is formed of a light reflective material.   9. The method of manufacturing an optical element according to claim 8, wherein in the semiconductor layer forming step, the contact electrode laminated on the p layer is formed of a light transmissive material.

Images