JP2011138820A - Light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-output, reliable light-emitting element that has a relatively simple configuration and suppresses a decrease in electromigration of a metal atom included in a metal reflection film of a light reflection structure and a decrease in a reflection factor of the light reflection structure caused by the electromigration. <P>SOLUTION: The light-emitting element includes a semiconductor element structure, the light reflection structure that is provided at one portion on the semiconductor element structure and includes a light-transmitting and insulating first reflection film, a second reflection film made of metal, and an insulation film in this order, and an electrode film including a coating unit for sandwiching the light reflection structure with the semiconductor element structure for coating on the light reflection structure and a conduction unit on the semiconductor element structure exposed from the light reflection structure. The second reflection film includes an extension unit extending from at least one of the first reflection film and the insulation film to the conduction unit and abutting on the electrode film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting element, and more particularly to a light emitting element in which a light reflecting structure is provided on a semiconductor element structure.

  Light emitting diodes (Light Emitting Diodes: LEDs), laser diodes (Laser Diodes: LDs), and other light emitting elements, and wavelengths that can be excited by primary light emitted from the light emitting elements to emit secondary light with a different hue from the primary light A light emitting device capable of emitting light of various colors has been developed by combining the conversion member and the principle of color mixing of light. Particularly in recent years, such light-emitting devices have attracted attention as low-power consumption and long-life lighting alternatives to incandescent bulbs and fluorescent lamps, and there is a demand for light-emitting elements and devices with high output and high reliability. .

  For example, Patent Document 1 includes a semiconductor layer stacked on a light-transmitting substrate, and an n-electrode and a p-electrode are formed on the semiconductor layer side with respect to the light-transmitting substrate. A transparent conductive film that is transparent to light, formed on a certain contact layer, and a multi-reflective film that is formed on the transparent conductive film and that is formed by periodically laminating layers made of dielectric materials having different refractive indexes; And a reflective film made of a metal having a high reflectance with respect to light and an electrode layer formed on the transparent conductive film so as to be bonded to a part of the transparent conductive film. There has been proposed a flip-chip type semiconductor light emitting element that emits emitted light from the side of a light transmitting substrate.

  According to such a semiconductor light emitting device, the interfacial reaction between the reflective film made of silver or aluminum and the transparent conductive film such as ITO is suppressed by the interposition of the multiple reflective film, and the transparent conductive film is transmitted by the alteration or discoloration of the film. It is described that it is possible to prevent a decrease in the reflectance and the reflectance of the reflective film. Further, it is described that the electromigration of metal atoms in the reflective film can be prevented by covering the side surface and the upper surface of the reflective film or only the upper surface with an insulating protective film.

JP 2006-120913 A JP 2006-108161 A JP 2009-088299 A JP 2009-164423 A JP 2005-197289 A JP 11-340514 A

  However, in the semiconductor light emitting device described and illustrated in Patent Document 1, the metal reflection film has a uniform thickness and is formed so as to cover the side surface of the multiple reflection film interposed thereunder. Absent. In such a semiconductor light emitting device, when only the upper surface of the metal reflective film is covered with an insulating protective film, current flows in a direction parallel to the surface of the reflective film, and thus electromigration of metal atoms in the reflective film occurs. Therefore, there is a problem that the reliability of the element is lowered. In addition, when the metal reflective film is completely covered with the insulating protective film and the multiple reflective film, the path of the current flowing from the electrode layer to the semiconductor layer is more restricted even if the occurrence of electromigration can be prevented. May increase, and the film formation process of the metal reflective film and the insulating protective film may become complicated, resulting in an increase in production cost.

  The present invention has been made in view of the above problems, and its object is to provide a relatively simple configuration, electromigration of metal atoms contained in the metal reflective film of the light reflecting structure, and the reflectance of the light reflecting structure thereby. Is to provide a light-emitting element with high output and high reliability.

The light emitting device according to the present invention can solve the above problems by the following means (1) to (13).
(1) Light including a semiconductor element structure, a light-transmitting and insulating first reflective film, a metal second reflective film, and an insulating film provided in this order on a part of the semiconductor element structure. An electrode film having a reflection structure, a covering portion that covers the light reflection structure with the semiconductor element structure sandwiched on the light reflection structure, and a conductive portion on the semiconductor element structure that is exposed from the light reflection structure And the second reflective film has an extended portion that extends from at least one of the first reflective film and the insulating film to the conductive portion and contacts the electrode film.
(2) The first reflective film includes an inclined portion that is continuous from the first reflective film on the covering portion side and is inclined toward the semiconductor element structure side in the extending direction in the extending portion ( The light emitting element as described in 1).
(3) The light emitting element according to (1), wherein the extending portion is provided on a side surface of the first reflective film on the conductive portion side.
(4) The light emitting device according to (2) or (3), wherein the first reflective film includes a dielectric multilayer film in which two or more kinds of dielectric films having different refractive indexes are periodically stacked.
(5) The light-emitting element according to any one of (1) to (4), wherein the film thickness of the extension portion decreases in the extension direction.
(6) The light emitting element according to any one of (1) to (5), wherein a gap is provided between the second reflective film and the electrode film in the extending portion.
(7) Any one of the above (1) to (6), wherein the semiconductor element structure includes a plurality of the conductive portions, and at least one of the conductive portions is surrounded by the covering portion. The light emitting element as described in.
(8) The semiconductor element structure includes first and second conductive semiconductor layers, and the electrode film and the light reflecting structure are provided on the same surface side of the first and second conductive semiconductor layers, respectively. The light emitting element according to (7), wherein all the conductive portions on the two-conductivity type semiconductor layer are conductive portions surrounded by the covering portion.
(9) The light-emitting element according to any one of (1) to (7), wherein the light-emitting element includes an extending side portion in which the electrode film and the light reflecting structure extend side by side.
(10) The conducting portion on the first conductive type semiconductor layer is provided on an outer peripheral portion of the electrode film, and the light reflecting structure on the first conductive type semiconductor layer is provided only on the inner side of the outer peripheral portion. The light emitting element as described in said (8) or (9).
(11) The light-emitting element according to any one of (1) to (10), wherein a light-transmitting conductive film is provided between the semiconductor element structure, the electrode film of the conductive portion, and the light reflecting structure. .
(12) The light-emitting element according to (11), further including a second light reflection structure including the first reflection film between the light-transmitting conductive film and the semiconductor element structure.
(13) The light-emitting element according to (12), wherein the conductive portion is disposed in the second light reflecting structure within the surface of the translucent conductive film.

  According to the present invention, in the light reflecting structure provided on a part of the semiconductor element structure and covered with the electrode film, first, the metal second reflecting film is formed of a translucent and insulating first reflecting film; By forming the laminated structure sandwiched between the insulating films, the current flowing in the vertical direction from the covering portion of the electrode film covering the light reflecting structure to the second reflecting film can be suppressed. Further, the second reflective film extends from the first reflective film and / or the insulating film to the conductive part of the electrode film provided on the semiconductor element structure exposed from the light reflecting structure, and extends to be in contact with the electrode film Even if a current flows laterally through the second reflective film, the metal atoms of the second reflective film in the extension part in the vicinity of the conductive part having a relatively high current density can be preferentially electromigrated. it can. This suppresses the electromigration of the metal atoms of the second reflective film on the side of the covering portion that functions as the main light reflective film even if the current flows while suppressing the current flowing in the second reflective film. Therefore, it is possible to provide a light emitting element with high output and high reliability by preventing a decrease in reflectance of the light reflecting structure.

It is a light emitting element concerning one embodiment of the present invention, and is a schematic sectional view in an AA section of Drawing 1B. 1 is a schematic top view of a light emitting device according to an embodiment of the present invention. It is the schematic sectional drawing which expanded the circumference of the light reflection structure of the light emitting element concerning one embodiment of the present invention partially. It is the schematic sectional drawing which expanded the circumference of the light reflection structure of the light emitting element concerning one embodiment of the present invention partially. It is the schematic sectional drawing which expanded the circumference of the light reflection structure of the light emitting element concerning one embodiment of the present invention partially. It is the schematic sectional drawing which expanded the circumference of the light reflection structure of the light emitting element concerning one embodiment of the present invention partially.

  Hereinafter, embodiments of the invention will be described with reference to the drawings as appropriate. However, the light emitting element described below is for embodying the technical idea of the present invention, and the present invention is not limited to the following. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the components described below are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. In addition, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. Furthermore, each embodiment described below can also be applied by appropriately combining the components and the like unless otherwise specified. In the present specification, the term “upper” as used on the layer or the like is not necessarily limited to the case where the upper surface is formed in contact with the upper surface, but includes the case where the upper surface is formed apart from the upper surface. It is used to include the case where there is an intervening layer between them.

<Embodiment 1>
1 is a schematic diagram of a light-emitting element according to Embodiment 1 of the present invention, FIG. 1A is a schematic cross-sectional view taken along line A-A in FIG. 1B of a schematic top view, and FIG. It is the schematic sectional drawing which expanded the circumference of a reflective structure partially. In each drawing, the protective film 50 and the external connection portions 34 and 44 of the first and second electrodes 30 and 40 at the openings are partially omitted, such as other light reflecting structures and electrode structures. The same applies to the other figures. The light emitting element of the example shown in FIGS. 1 and 2 mainly includes a semiconductor element structure 20, light reflecting structures 17 and 18, and electrode films 32 and 42. The semiconductor element structure 20 has semiconductor layers 21 to 23 constituting the light emitting element structure on the substrate 10, and the semiconductor layers are a first conductivity type semiconductor layer 21, an active layer 22, and a second conductivity type semiconductor layer from the lower layer side. 23 in this order. In the following description, the first conductivity type is mainly n-type and the second conductivity type is p-type. The light reflecting structures 17 and 18 include a light-transmitting and insulating first reflecting film 1, a metal second reflecting film 2, and an insulating film 3 in this order from the lower layer side. The light reflecting structure is provided on a part of the semiconductor element structure, more specifically on each conductive type semiconductor layer, on a part of the non-light emitting structure part 26 and the light emitting structure part 25 in the exposed part. On each conductive type semiconductor layer, electrode films 32 and 42 are provided so as to cover the light reflecting structures 17 and 18. The electrode films cover the light reflecting structure and light is transmitted between the semiconductor element structures. Covering portions 36 and 46 sandwiching the reflection structure and conductive portions 35 and 45 on the semiconductor element structure (semiconductor layer) exposed from the light reflection structure and electrically connected to the semiconductor layer are continuously provided. When such a light emitting element is energized, current is injected into the semiconductor element structure 20 from the conductive portions 35 and 45 of the electrode film, carriers in the element structure are injected, and light is emitted from the active layer 22. A part of the light emitted to the film forming surface side is reflected by the light reflecting structures 17 and 18 and extracted from the substrate 10 side.

  The light reflecting structures 17 and 18 in the light emitting element of the present invention have the second reflective film 2 made of metal provided on the first reflective film 1 that is translucent and insulative. A part of the light is reflected by the reflective film 1 and part of the light is transmitted. The transmitted light can be reflected by the second reflective film 2. The second reflective film 2 is electrically insulated from the translucent conductive films 31 and 41 by the first reflective film 1 interposed thereunder, and is also translucent mainly composed of an oxide. Oxide generation due to a chemical reaction with the conductive film is also suppressed. Further, the second reflective film 2 is electrically insulated from the electrode film covering portions 36 and 46 by the insulating film 3 interposed thereon. In this way, the second reflective film 2 on the covering portion side that functions as a main light reflective film in the light reflective structures 17 and 18 is sandwiched between the first reflective film 1 and the insulating film 3 and sandwiched outside thereof. The electrode films 32 and 42 are insulated from the semiconductor element structure 20, specifically, the semiconductor element structure and the electrode film sandwiched through the light-transmitting conductive film, and thus the current flowing in the vertical direction in the second reflective film 2 is suppressed. Has been. Furthermore, the upper surfaces of the light reflecting structures 17 and 18 covered by the covering portions 36 and 46 have high resistance due to the electrical barrier by the insulating film 3, and the current flowing through the electrode films 32 and 42 is covered by the covering on the light reflecting structure. It flows in the horizontal direction at the part. On the other hand, in the conductive portions 35 and 45, the current flowing in the lateral direction in the second reflective film 2 is promoted because the flow in the semiconductor layer 20 side exposed in the light reflecting structures 17 and 18 and the relatively low resistance side, that is, the vertical direction is promoted. Can be reduced. As described above, the first reflective film 1 and the insulating film 3 having the light reflecting structure serve to control the flow of current to the second reflective film 2.

  The second reflective film 2 has extended portions 17a and 18a that extend from at least one of the first reflective film 1 and the insulating film 3 to the conductive portions 35 and 45 and are in contact with the electrode film. As described above, the electrical connection region between the electrode films 32 and 42 and the semiconductor layer 20 is limited to the conductive portions 35 and 45 by the first reflective film 1 and the insulating film 3 having the light reflecting structure. The current is concentrated in the portion, and the current density is relatively high. And in the region where the current density is relatively high, the extension portions 17a and 18a of the second reflective film 2 that are in contact with the electrode film are more likely to cause electromigration of contained metal atoms from the covering portion side. Thereby, even if an electric current flows into the 2nd reflective film 2 to the horizontal direction, the metal atom of the 2nd reflective film 2 in the extension parts 17a and 18a can be electromigration preferentially. In this way, by causing the extending portions 17a and 18a of the second reflective film 2 to function as a sacrificial region due to electromigration, electromigration of metal atoms of the second reflective film on the covering portion side is suppressed, and the light reflecting structure 17 , 18 can be prevented from decreasing in reflectance. Eventually, the metal atoms of the extending portions 17a and 18a of the second reflective film 2 may migrate to form voids in the extending portions, but these voids act as an electrical barrier. Further, it is possible to further suppress the electric current flowing in the lateral direction to the second reflective film on the covering portion side, and to further suppress the electromigration of the metal atoms of the second reflective film on the covering portion side. In addition, the metal atoms of the second reflective film 2 migrate in the extended portions 17a and 18a, and a gap is formed between the second reflective film 2 and the electrode films 32 and 42. 2 The cross-sectional area and volume of the reflection film are reduced, the current path to the second reflection film 2 is further restricted, the current density of the second reflection film 2 around the gap is further increased, and electromigration is further promoted to increase the gap. Is encouraged to grow.

  In the light emitting device of the present embodiment, as shown in FIG. 2, the first reflective film 1 is continuous from the first reflective film 1 on the covering portion side, and the extended portions 17a and 18a extend the extended portion. A form having an inclined part that inclines toward the semiconductor element structure in the outgoing direction, that is, an extended part 17 a, 18 a of the second reflective film 2 is preferably provided in the inclined part of the first reflective film 1. Thereby, the current density change from the covering portions 36 and 46 to the conducting portions 35 and 45 and from the upper surface side to the lower surface side of the conducting portion can be made smooth, and the extending portions 17a and 18a of the second reflective film 2 can be Since the cross-sectional area can be reduced and the semiconductor layer can be disposed in a region where the current density is particularly high, the above-described effects can be easily achieved. Further, the extending portions 17a and 18a of the second reflecting film 2 are formed so as to extend along the path of the current flowing through the conducting portions 35 and 45, so that they flow to the second reflecting film 2 on the covering portion side. Even if the current flows through the second reflective film 2 while suppressing the current, the electromigration of the metal atoms in the extending portions 17a and 18a of the second reflective film 2 can be preferentially generated. In FIG. 2, for the sake of simplicity, arrows indicating the flow from the electrode films 32 and 42 to the semiconductor are shown. However, the negative electrode of the positive and negative electrodes flows in the direction of the arrow, and that the electrons flow in the reverse direction of the positive electrode. Needless to say, the same applies to FIGS.

  Specifically, in the light reflecting structures 17 and 18 according to the first embodiment, the first reflecting film 1 is formed on the substantially flat surfaces of the translucent conductive films 31 and 41, and extends in the extending direction, that is, conductive. The closer to the contact side with the semiconductor layer in the portions 35 and 45, the smaller the film thickness. From the central portion of the light reflecting structure, that is, from the substantially flat surface on the covering portions 36 and 46 side, the surface To the semiconductor element structure 20 side. The second reflective film 2 is formed so as to cover the substantially flat surface of the first reflective film 1 and a part of the inclined surface. Here, in the present invention, each film on the covering portion side of the light reflecting structures 17 and 18 may be various forms such as a gently curved surface and an uneven surface, even if it is not substantially flat. It is only necessary to provide the extended portions 17a and 18a which are greatly inclined as compared with the above. Further, the second reflective film 2 has a surface with an inclined surface that becomes thinner as it extends, and that inclines continuously from the surface of the central portion toward the semiconductor element structure side. Further, the insulating film 3 is formed so as to cover the surface of the covering portion of the second reflecting film 2 and a part of the surface of the inclined surface, and similarly the film thickness is reduced in the extending direction. The surface of the inclined surface is continuously inclined from the surface to the semiconductor element structure side. Therefore, the surfaces of the end portions of the light reflecting structures 17 and 18 are partly covered with a film laminated on the surface of each film, and a part of the surface is exposed. The inclined surface is inclined from the surface to the semiconductor element structure side. As described above, the extending portions 17a and 18a of the second reflecting film 2 in the first embodiment are provided on the surface of the inclined surface of the first reflecting film 1, and extend from the insulating film 3 to the conducting portion side. I'm out. Therefore, since the insulating film 3 that covers a part of the surface of the inclined surface of the second reflective film 2 covers the second reflective film 2 on the coating part side from the side, the conductive parts 35 and 45 of the electrode film. Current flowing directly from the first to the center of the second reflective film 2 in the lateral direction can be suppressed, and the contact area between the extended portions 17a and 18a of the second reflective film 2 and the electrode films 32 and 42 can be further increased. When the current flows through the second reflective film 2, the current density at the extended portion of the second reflective film can be increased, and electromigration of metal atoms in the extended portion can be preferentially generated.

  Moreover, in such light reflection structures 17 and 18, it is preferable that the 1st reflection film 1 has a dielectric multilayer film which is mentioned later. Since the first reflective film 1 has a dielectric multilayer film, the reflectivity of the light reflecting structure as a whole can be increased. However, the dielectric multilayer film has a reflectivity that depends on the wavelength and incident angle of light. In particular, the reflectance of light having an intended wavelength is likely to decrease with respect to incident light at a high angle. For this reason, the metal second reflective film 2 is the first reflective film 1 in the extended portions 17a and 18a where the film thickness is changed, the surface is inclined, and the reflective function is reduced as compared with the covering portion side. By covering at least a part of the inclined portion, light leaking to the outside and incident light at a high angle are reflected by the second reflecting film 2 to suppress a decrease in reflectance in the vicinity of the end portions of the light reflecting structures 17 and 18. can do. More preferably, the metal second reflective film 2 covers at least a part of the surface of the dielectric multilayer film in the inclined portion of the first reflective film 1 and completely covers the surface of the dielectric multilayer film in the inclined portion. It is more preferable.

  The film thickness of the second reflective film 2 is preferably smaller in the extending portions 17a and 18a than in the covering portion side. As a result, when a current flows through the second reflective film 2 in the lateral direction, the current density in the extended portions 17a and 18a of the second reflective film 2 is higher than that on the covering portion side, so that the metal in the extended portion Electromigration of atoms can be preferentially generated. Further, the migration of metal atoms generated in the light emitting element may cause problems such as short-circuiting or disconnection between electrodes and a decrease in light emission efficiency, but the film thicknesses of the extending portions 17a and 18a of the second reflective film 2 are not limited. Is small, the influence on the element due to migration of metal atoms in the second reflective film 2 can be suppressed. The “film thickness” here is considered to be the average film thickness of the part. Furthermore, it is preferable that the film thickness of the extension parts 17a and 18a becomes smaller as it extends as shown in the figure. Thereby, in the extension parts 17a and 18a, the current density on the conduction part side can be increased stepwise in the extension direction from the covering part side, and the metal atoms on the conduction part side can be electromigrationd more preferentially. Therefore, the occurrence of electromigration of metal atoms in the second reflective film 2 on the covering portion side can be further suppressed, the decrease in the reflectance of the light reflecting structure can be further suppressed, and the influence on the element can be further reduced.

  Further, in the example of the light emitting element shown in FIGS. 1 and 2, both conductive type electrode films 32 and 42 are provided on the same surface side of the semiconductor element structure 20, respectively, and the first conductive type electrode film 32 is formed. As a region 26, a part of the first conductivity type semiconductor layer 21 is exposed. And the 1st electrode 40 of the structure which has the external connection part 33 and the extending | stretching part 34 extended | stretched from there is provided on the exposed surface 26 of a 1st conductivity type semiconductor layer, On the other hand, the light reflection structure of each electrode 40 17 is provided in a single island shape, and a conductive portion 35 of an electrode film is formed around the light reflecting structure 17. On the other hand, the light reflecting structure 18 on the second conductive type semiconductor layer 23 is provided in a lattice shape, and a conducting portion 45 of the electrode film 42 is formed in the opening of the light reflecting structure 18.

  As described above, the light-emitting element of the present embodiment has a plurality of conducting portions 35 and 45 within the surface of the semiconductor element structure 20, and at least one conducting portion is surrounded by the covering portions 36 and 46. It is preferable. Since the conducting portions 35 and 45 are surrounded by the covering portions 36 and 46, a current can be concentrated on the conducting portion from the covering portion around the conducting portion, and a region having a high current density can be locally formed. . Thereby, in the light reflecting structures 17 and 18, the region where the electromigration of the metal atoms of the second reflecting film 2 due to the current is likely to occur is limited, the end length and the area are reduced, and the first portion on the covering portion side is reduced. 2 Electromigration of metal atoms in the reflective film 2 can be suppressed, and the amount thereof can be reduced. A light reflecting structure in which all the conducting portions 35 and 45 are surrounded by the covering portions 36 and 46 may be used. In this case, the surface of the semiconductor element structure 20 can be covered widely with the light reflecting structures 17 and 18. A light reflecting structure having excellent light reflectivity can be formed. Further, in the formation of a large-area electrode film like the second electrode 40 on the second conductivity type layer 23, it is configured by only the conductive portion 45 of the opening without providing an extension side portion to be described later. The occurrence of electromigration in the stretching direction can be prevented. Therefore, in the structure having the electrode films 32 and 42 and the light reflecting structures 17 and 18 on the same surface side of the first and second conductive semiconductor layers 21 and 23, the covering portion 46 is formed on the second conductive semiconductor layer 23. It is preferable to have a plurality of conducting portions 45 surrounded by the. In this way, by disposing a plurality of conductive portions 45 in the opening on the second conductive type semiconductor layer 23, the current diffusivity in the surface of the electrode film 42 is improved, and the reflection function by the light reflecting structure 18 is improved. Can be increased. The shape of the opening 45 is not particularly limited, but there are other shapes such as a quadrilateral shape, an island shape such as a polygonal shape and a circular shape, a stripe shape, and a lattice shape as shown in the figure. In addition to placement, regular placement and irregular placement are possible. Preferably, as shown in the figure, the islands are arranged in a grid pattern.

  As shown in the second embodiment and FIG. 2, the light reflecting structure 18 has an outer peripheral portion on the surface of the semiconductor element structure 20 and a plurality of openings 45 inside the light reflecting structure. The conducting portion is formed on the surface of the second conductivity type semiconductor layer 23 by the first conducting portion surrounded by the covering portion 46 provided in the opening portion, and the outer peripheral portion or one side or a second portion thereof. You may have a conduction | electrical_connection part. As a result, the second conducting portion on the outer peripheral portion is provided relatively widely and continuously, and the end portion length becomes long. Therefore, the current density is lower than that of the first conducting portion, and the metal atoms of the extending portion 18a It can be formed as a region where electromigration is unlikely to occur, and the presence of the second conductive portion reduces the current density of each first conductive portion, and the metal in the extended portion also in the first conductive portion Generation of atomic electromigration can be suppressed. In addition, light emission is promoted also at the outer edge portion of the element by the second conductive portion, and the light is directly taken out from the side surface of the element, and the light emitted inside the element is surrounded by the covering portion 46 (first). By having the conduction part 45, the light reflection structure 18 formed extensively in the surface of the surface of the second conductivity type semiconductor layer 23 can be efficiently reflected and taken out. On the other hand, in the outer peripheral part, the electrode part and the light reflecting structure are arranged side by side to become an extended extension part, and the extension side part is formed in a region having a long outer peripheral length, that is, a long extension length. A current flowing in the stretching direction is generated, and electromigration is thereby generated, which is preferable because it can be improved by the structure of the present invention. Each of the above embodiments has been described for the second electrode 40 on the second conductivity type semiconductor layer, but may be applied to the first electrode.

  On the other hand, the conductive part 35 on the first conductive type semiconductor layer 21 diffuses a current widely with respect to the second conductive type semiconductor layer 23 and reduces the electrode formation region as seen in the present embodiment. The form is preferred. In the present embodiment, the conducting part 35 is provided with a conducting part only at the end of the light reflecting structure 17 in the cross section, and further, the conducting part is formed at both ends in the cross section, and surrounds the periphery of the light reflecting structure 17. In addition, the conductive portion is provided so as to face the end surface of the second conductivity type semiconductor layer 23. As a result, the electrode portion 30 can be made small and thin, the function of the light reflecting structure 17 is enhanced, the potential at each part of the electrode 30 is made more uniform, and the light emitting structure portion 25 adjacent to the conducting portion 35 is made. This is preferable because the current can be diffused efficiently. On the other hand, the electrode portion 30 that is formed to be thin and long and stretched as shown by the arrow in FIG. The occurrence of electromigration in the direction becomes a problem, but the structure of the present invention can suppress the occurrence and reduce the problem.

  In addition, translucent conductive films 31 and 41 are provided in substantially the entire region on the electrode film formation surface of each semiconductor layer, and the light reflecting structures 17 and 18 are provided in contact with the translucent conductive film. Thus, by providing the translucent conductive films 31 and 41 between the semiconductor element structure 20 and the electrode film and the light reflecting structure of the conductive portions 35 and 45, the conductive portions 35 and 45 are changed from the covering portions 36 and 46, respectively. The vertical current flowing to the semiconductor layer 20 via 45 can be promoted, and the current flowing to the second reflective film 2 can be suppressed. In addition, the current density of the conductive portions 35 and 45 can be increased, and electromigration of the metal atoms of the extending portions 17a and 18a can be preferentially generated. Translucent conductive films 31 and 41 are provided between the light reflecting structures 17 and 18 and the semiconductor element structure 20 to diffuse current from the conducting portions 35 and 45 to the light reflecting structure of the semiconductor layer, thereby reflecting the light. The light is emitted below, and a part of the light can be efficiently extracted by being transmitted through the light-transmitting conductive film and reflected by the light reflecting structure.

  As another embodiment of the present invention different from the present embodiment, as shown in FIG. 3, the second light reflecting structure 18A is formed on the lower side of the light reflecting structure 18, the translucent conductive film 41 and the semiconductor. Further, it is possible to have a structure in which it is interposed between the element structure 20 and corresponding to the conductive portion 45, that is, through the translucent conductive film so as to face the conductive portion 45. Thereby, the light passing through the opening of the light reflecting structure 18 is reflected by the second light reflecting structure 18A, and the light extraction efficiency of the element can be increased. The first nitride semiconductor layer 21 may be provided on either the exposed portion 26 side or the light emitting structure portion 25 side, and particularly preferably provided on the large area light emitting structure portion 25 side. The second light reflecting structure 18 </ b> A may have each reflecting film similarly to the light reflecting structure 18, and preferably has at least the first reflecting film 1. Thus, by forming the light reflecting structure 18 in a thin film, it is possible to suppress an appropriate reflecting function, a shape change to the light reflecting structure 18 on the upper layer side due to a step, and an influence on the reflecting function. Here, as shown in the drawing, the second reflection structure 18A is preferably arranged so as to be wider than the conduction portion 45 and include the second reflection structure 18A, and within the plane of the translucent conductive film 41. It is more preferable to provide the conductive portion 45 so as to have a larger area than the portion 45 and to be disposed inside. On the other hand, by forming it smaller than the conductive portion 45, and further separating the light reflecting structure 18 and the second light reflecting structure 18A from each other, the mutual influence can be reduced and a structure in which the light reflecting structures are laminated can be obtained. Also, as shown in the figure, when a step is provided inside the light reflecting structure 18 and its covering portion 46 by overlapping each other, a top surface side 18c, a step portion 18d, and a bottom surface side 18e are provided. As a result, the path of the second reflective film 2 in the light reflecting structure 18 is narrowed, the current flowing through the inside can be reduced, and the influence of electromigration from the extending portion 18a to the upper surface side 18c is suppressed. It is possible to reduce the influence, and to maintain the reflection function of the bottom surface side 18e serving as a main light reflecting portion. Similarly to the light reflecting structure 18, the second light reflecting structure 18 </ b> A can be provided with a conducting portion 49 adjacent thereto, and current can be injected into the semiconductor element structure therefrom. On the other hand, as shown in the drawing, the formation region of the second light reflecting structure 18A becomes a non-injection path and becomes a non-light emitting region on the light emitting structure 25, but suppresses light emission just below the conducting portion 45, and reduces the light. A second light reflecting structure having a lower reflectance than the reflecting structure 18 can be used to reflect the light passing therethrough. At that time, there is light that obliquely passes through the region between the light reflecting structures and the region of the light transmitting conductive film 41. However, the light transmitting conductive film 41 is thinner than the light reflecting structure, and as illustrated, in the stacking direction. By letting them overlap each other, the passing light can be reduced. Further, in accordance with the non-light-emitting structure, the reflection function different from that of the light reflection structure 18, for example, the set wavelength of the first reflection film 1 may be longer than that of the light reflection structure 18 so as to correspond to incident light at a high angle. it can. Similarly to the light reflecting structure 18, the second light reflecting structure 18 </ b> A may be provided with a light-transmitting conductive film interposed thereunder to serve as a current injection region.

  The structure of the electrode film 32 and the light reflecting structure 17 shown in FIG. 4 relates to another embodiment of the present invention that is different from the present embodiment, and is opposite to the case of the first electrode 30 of the present embodiment described above. In addition, the light reflecting structure 17 is provided on the end side of the electrode, and the conducting part 35 is provided on the inner side. Further, the outer peripheral portion is constituted by the light reflecting structure 17, the light reflecting structure opening and the conducting portion 35 are provided inside thereof, and the light reflecting structure extends to the outside of the translucent conductive film 31, and further the semiconductor. It is provided directly on the layer 20. By having such a structure, the function of the light reflecting structure is enhanced, and the conductive section 35 is surrounded by the light reflecting structure 17 as in the present embodiment, and thus the above-described effects are achieved.

  It should be noted that the film thickness and surface inclination of each film constituting the light reflecting structures 17 and 18 can be determined by etching, lift-off, etc. after forming one film by sputtering, CVD, vapor deposition or the like. This can be realized by partially removing and shaping the film. However, in the light reflecting structures 17 and 18 having the structure as shown in FIG. 2, as a protective film (resist, mask) for forming the pattern of the light reflecting structure, an inclined surface inclined inward from the upper surface thereof is used. By using a film having a side surface and sequentially forming each film constituting the light reflecting structure, it can be formed relatively easily. Specifically, after patterning the protective film having the above shape on the translucent conductive film, the first reflective film is formed, and the first reflective film having a substantially trapezoidal cross section is formed in the opening of the protective film. It is formed. Subsequently, if a second reflective film is formed thereon, the second reflective film is formed not only on the substantially flat surface at the center of the first reflective film but also on the inclined surface at the end of the first reflective film. Be filmed. At this time, since the second reflective film on the inclined surface of the end portion is formed so as to go around the gap between the inclined surface of the first reflective film and the side surface of the protective film, the film thickness is smaller than the central portion. It will be a thing. In addition, since the gap between the first reflective film and the protective film decreases toward the end portion, the thickness of the second reflective film also decreases accordingly, and the second reflective film is not partially formed and the first reflective film is formed. The surface of the reflective film is exposed. Further, the insulating film formed thereon and the intervening layer interposed therebetween are similarly formed on the substantially flat surface at the center of the lower layer and the inclined surface at the end. With this method, the light reflection structure of the example shown in FIG. 2 can be formed only by sequentially forming each film using the protective film as described above without involving the patterning process of each film by etching or the like. And productivity is good.

    Next, each structure of the light emitting element of this invention is explained in full detail below.

(Light emitting element)
As the light-emitting element, a known semiconductor light-emitting element can be used. In particular, a nitride semiconductor is preferable because it can emit visible light and ultraviolet light having a short wavelength that can excite a fluorescent substance efficiently. A specific emission peak wavelength is 240 nm or more and 560 nm or less, preferably 380 nm or more and 470 nm or less. In addition, a light emitting element of ZnSe, InGaAs, or AlInGaP semiconductor may be used.

(Semiconductor element structure)
The semiconductor element structure 20 by the semiconductor layer is composed of at least a first conductivity type (n-type) layer 21 and a second conductivity type (p-type) layer 23, and further has a structure having an active layer 22 between them in terms of output and efficiency. preferable. In addition, the electrode structure is preferably the same surface side electrode structure in which both the first conductivity type electrode and the second conductivity type electrode are provided on one main surface side, but the electrode structure is not limited thereto and faces each main surface of the semiconductor layer. A counter electrode structure in which electrodes are provided, for example, a structure in which electrodes are provided on the substrate removal side in a growth substrate removal structure may be employed. As for the mounting form of the light-emitting element, for example, in the above-mentioned same-surface electrode structure, flip-chip mounting in which the electrode film forming surface is the mounting surface and the substrate side facing it is the main light extraction surface is formed between the semiconductor layer and the electrode film. It is preferable in terms of a structure having a light reflecting structure between them. In addition, face-up mounting may be used in which the electrode film forming surface side is the main light extraction surface.

(Nitride semiconductor light emitting device)
As an example of the light emitting device, for example, in the nitride semiconductor light emitting device shown in FIG. 1, the n-type semiconductor layer 21 that is the first nitride semiconductor layer and the light emission that is the active layer are formed on the sapphire substrate that is the growth substrate 10. The layer 22 and the p-type semiconductor layer 23 which is the second nitride semiconductor layer are epitaxially grown in this order. As the crystal growth method, for example, a metal-organic chemical vapor deposition (MOCVD) method, a hydride vapor deposition (HVPE) method, or the like can be used. Then, a part of the light emitting layer 22 and the p-type semiconductor layer 23 is selectively removed by etching, a part of the n-type semiconductor layer 21 is exposed, and an n-type pad electrode is formed as a first electrode 30 in the exposed region. 32 is formed. In addition, a translucent conductive film 41 is formed as the second electrode 40 on the same surface side as the first electrode 30 and on almost the entire surface of the p-type semiconductor layer, and a p-type pad electrode 42 is formed thereon. Further, a protective film 50 is provided to expose the surfaces of the n-type and p-type pad electrodes 32 and 42 and cover each semiconductor layer. Note that the first electrode 30 may be formed on the exposed region of the n-type semiconductor layer via the translucent conductive film 31.

(Nitride semiconductor layer)
As the nitride semiconductor, the general formula _{In x Al y Ga 1-xy} N (0 ≦ x, 0 ≦ y, x + y ≦ 1) A, B and P, may be mixed with As. Further, the n-type semiconductor layer 21 and the p-type semiconductor layer 23 are not particularly limited to a single layer or a multilayer. The active layer 22 preferably has a single quantum well structure (SQW) or a multiple quantum well structure (MQW). As an example of a blue light emitting device structure, an n-type nitride is formed on a C surface of a sapphire substrate via a nitride semiconductor underlayer such as a buffer layer, for example, a low-temperature growth thin film layer of GaN and a high-temperature growth layer of GaN. As the semiconductor layer, for example, an Si-doped GaN n-type contact layer and a GaN / InGaN n-type multilayer film layer are stacked, followed by an InGaN / GaN MQW active layer, and further as a p-type nitride semiconductor layer, for example, Mg-doped InGaN / AlGaN p-type multilayer film and Mg-doped GaN p-type contact layer are stacked.

(Growth substrate)
The growth substrate 10 is a substrate on which a semiconductor layer can be epitaxially grown, and the size and thickness of the substrate are not particularly limited. As a substrate in a nitride semiconductor, an insulating substrate such as sapphire or spinel (MgAl ₂ O ₄ ) whose main surface is any of C-plane, R-plane, and A-plane, and silicon carbide (6H, 4H, 3C). ), Silicon, ZnS, ZnO, Si, GaAs, diamond, and nitride semiconductors, and oxide semiconductor substrates such as lithium niobate and neodymium gallate, and nitride semiconductor substrates such as GaN and AlN. A substrate (for example, 0.01 ° to 3.0 ° on the sapphire C surface) can also be used. The growth substrate 10 may serve as a part of one conductivity type semiconductor layer. The growth substrate 10 may be removed when the semiconductor element structure is not formed, and a support substrate such as a conductive substrate or another light-transmitting member / substrate is formed on the semiconductor layer from which the growth substrate 10 has been removed. It can also be set as the structure which adhered. In addition, an element having a structure in which a semiconductor layer is bonded and covered with a light-transmitting member such as glass or resin (or a wavelength conversion member containing a fluorescent substance) may be used. The removal of the growth substrate 10 can be carried out by polishing or LLO (Laser Lift Off) while being held on the chip mounting portion of the apparatus or submount, for example. Moreover, even if it is a translucent dissimilar board | substrate, light extraction efficiency and an output can be improved by removing a board | substrate.

(Translucent conductive film)
Since the conductive films 31 and 41 are formed on almost the entire surface of the semiconductor layer, the current can be spread uniformly over the entire semiconductor layer, and the conductive film has translucency so that light is reflected thereon. Structures 17 and 18 can be provided. The translucent conductive films 31 and 41 include various types such as a transparent electrode, but are preferably oxides containing at least one element selected from the group consisting of Zn, In, and Sn. Specifically, those containing oxides of Zn, In, Sn such as ITO, ZnO, In ₂ O ₃ , SnO ₂ are preferable, and ITO is more preferably used. Alternatively, a metal such as Ni may be a thin metal film such as 30 mm, other metal oxides, nitrides, compounds thereof, a light transmission structure such as a metal film having a window opening, or a composite of the above. . Further, the thickness of the translucent conductive films 31 and 41 is set in consideration of the light absorption and electric resistance / sheet resistance of the layer, and the light reflection structures 17 and 18 and the spread of current, for example, 1 μm or less. Specifically, the thickness is 10 nm to 500 nm. In addition, the light extraction efficiency can be increased by setting the wavelength λ of light emitted from the active layer 22 to be approximately an integral multiple of λ / 4. The translucent conductive films 31 and 41 can be omitted. In that case, the light reflecting structures 17 and 18 may be provided in contact with the semiconductor layers of the respective conductivity types.

(Light reflection structure)
In the light emitting device of the present invention, when one of the two main surfaces facing each other of the semiconductor device structure 20 is a light extraction side and the other is a light reflection side, light reflection structures 17 and 18 are provided on the light reflection side. The active layer 22 is provided in a region 25 having a light emitting structure. The light reflecting structures 17 and 18 are provided as a part of the electrode structure, an overlapping structure with the electrode structure, an in-plane separation structure with the electrode structure, and the like, and preferably the light emitting area increases corresponding to the light emitting structure. In addition, a superposition structure is employed so that the charge injection efficiency is increased. Specifically, a light reflecting structure is provided between a semiconductor layer or a light-transmitting conductive film thereover and a pad electrode connected to the outside of the element. As a result, the electrical conduction path and the light reflection region are separated from each other in the plane. This in-plane separation light reflecting structure has a conduction structure in the separation region, and thus can be configured to be insulative.

  Hereinafter, each film of the first reflecting film 1, the second reflecting film 2, and the insulating film 3 constituting the light reflecting structures 17 and 18 of the present invention will be described.

(First reflective film)
The first reflective film 1 is made of an insulator. Although a single layer of an insulating film may be used, the light reflectivity of the light reflecting structure can be further enhanced by being configured in combination with a dielectric multilayer film. Specifically, light with a high incident angle is favorably reflected by the insulating film, and light with a low incident angle is favorably reflected by the DBR of the dielectric multilayer film. Therefore, a composite in which both are combined rather than either one It is preferable to use a reflective structure. The arrangement of the insulating film and the dielectric multilayer film is not particularly limited. However, when an insulating film and a dielectric multilayer film are preferably provided in this order from the semiconductor layer side, reflection of the refractive index difference by the insulating film and the dielectric Each function can be enhanced by separating the wavelength and direction-dependent reflection by the multilayer film, which is preferable. Note that the first reflective film 1 may include only a dielectric multilayer film without including an insulating film.

(Insulating film)
The insulating film has a light-transmitting property so that light from the light emitting element is efficiently reflected and a part of the light is transmitted through the dielectric multilayer film. Therefore, the insulating film is preferably an oxide, more preferably an oxide of at least one element selected from the group consisting of Si and Al. Specifically, SiO ₂ , Al ₂ O ₃ or the like is used, and preferably SiO ₂ is used. The insulating film can be formed to a thickness of about 10 nm to 2 μm, and is preferably 200 nm to 500 nm.

(Dielectric multilayer film)
The dielectric multilayer film has a multilayer structure in which two or more kinds of dielectric films having different refractive indexes are periodically stacked. More specifically, the dielectric multilayer film constitutes a distributed Bragg reflector (DBR) in which films having different refractive indexes are alternately laminated with a thickness of ¼ wavelength, and a predetermined wavelength is highly efficient. Can be reflected. An example of the dielectric multilayer film is preferably a laminate in which at least two selected from at least one oxide or nitride selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al are repeatedly stacked. More preferably, it is made of a material composed of a non-metallic element or a laminated structure of oxides, for example, (Nb ₂ O ₅ / SiO ₂ ) n (where n is a natural number).

(Second reflection film)
The second reflective film 2 includes at least Al, Ag, W, Pt, Zn, Ni, Pd, Rh, Ru, Os, Ir, Ti, Zr, Hf, V, Nb, Ta, Co, Fe, Mn, Mo, A single layer or a multilayer structure having a layer containing a metal or an alloy containing at least one element selected from the group consisting of Cr, La, Cu, and Y or an oxide thereof is provided. The second reflective film 2 provided between the semiconductor layer and the electrode film is made of a metal having a higher reflectance and a smaller absorption coefficient than the metal constituting the electrode film with respect to the wavelength of light emitted from the active layer. It is preferable to use Al or Ag. As a result, the light emitted from the active layer can be reflected by the second reflective film 2, and light loss due to light absorption of the electrode film can be reduced to increase the light extraction efficiency.

  Among these, Al tends to cause electromigration due to electric current, but has the second highest reflectance after Ag. For this reason, in the present invention, the second reflective film 2 is particularly preferably Al or an alloy thereof, and has a structure capable of suppressing the current from flowing from the electrode film to the central portion of the Al-containing film serving as a main light reflecting region. With the light reflection structure, it is possible to suppress the occurrence of electromigration of Al atoms and suppress the decrease in the reflectance of the light reflection structure, so that a highly reliable light-emitting element can be obtained. Furthermore, since the second reflective film 2 is bonded to the insulating film through Ti, the adhesion between the two films can be enhanced, and thereby the above-described effects of the present invention can be enhanced. This Ti film can also function as a barrier layer for protecting the second reflective film 2 in the photolithography development process. As the adhesion layer and the barrier layer, Ti—W alloy, W, Ta, Hf, and nitrides thereof can be used in addition to Ti. As the Al alloy, Cu (Al—Cu) in Al or an alloy containing Si and Cu (Al—Si—Cu) can be used. The Cu content is, for example, 2 wt% or more, and further 3 wt%. Preferably, the upper limit of the Cu and Si content is, for example, about 10 wt% or less, and further 5 wt% or less. The Ag alloy is selected from the group consisting of Pt, Co, Au, Pd, Ti, Mn, V, Cr, Zr, Rh, Cu, Al, Mg, Bi, Sn, Ir, Ga, Nd, and Re. A seed | species or 2 or more types of alloy is mentioned. In this case, the ratio of silver is preferably about 90% by mass or more, preferably about 94% by mass or more, about 95% by mass or more, and more preferably about 96% by mass or more.

(Insulating film)
The insulating film 3 has a function of electrically insulating the electrode film and the second reflective film 2. The insulating film 3 is preferably an oxide, more preferably an oxide of at least one element selected from the group consisting of Si and Al, like the insulating film of the first reflective film 1. Specifically, SiO ₂ , Al ₂ O ₃ or the like is used, and preferably SiO ₂ is used. The thickness of the insulating film 3 is not particularly limited, and the insulating film 3 can be formed with a thickness of about 10 nm to 2 μm, preferably 100 nm to 500 nm.

(Light reflection structure formation pattern)
Any pattern can be used as the pattern (planar shape) of the light reflecting structures 17 and 18. A preferable shape of the opening is a line, stripe, lattice, or island. In the example of FIG. 1, the opening 45 of the light reflecting structure 18 is patterned in an island shape. Since the light reflecting structure includes the opening, an exposed region of the semiconductor element structure 20 (or the translucent conductive film) is formed. In this way, by partially exposing the semiconductor element structure 20 and being electrically connected to the electrode film, this region becomes a conduction path, and the contact resistance is substantially reduced and the forward voltage is reduced. Can be reduced. The formation pattern of the light reflecting structures 17 and 18 is not limited to the above example. For example, the shape of the opening is circular, elliptical, rectangular, polygonal, or the like, and the light reflecting structures 17 and 18 are island-shaped, For example, it is formed in a rectangular pattern, the vertical and horizontal widths of the rectangular pattern are changed as appropriate, the island shape is triangular, circular, semicircular, polygonal, or the arrangement is staggered The shapes and arrangements of various forming portions and openings may be used. Moreover, it is not restricted to the example arrange | positioned uniformly to the whole, A magnitude | size and density can be changed suitably for every area | region, or said pattern can also be combined.

  Further, the light reflecting structure may be provided on one of the conductive semiconductor layers, such as provided only on the p-type semiconductor layer, or may be provided on both conductive semiconductor layers. . For example, in a nitride semiconductor light emitting device, an n-type semiconductor layer and a p-type semiconductor layer are often stacked in this order on a substrate, and in addition, when each conductivity type electrode is formed on the same surface side, a light emitting region In order to increase the area of the n-side electrode, the n-side electrode and the exposed portion of the n-type semiconductor layer are formed small or narrow, and the current density is higher in the n-side electrode than in the p-side electrode. In particular, it is more effective when provided on such an n-type semiconductor layer.

  Further, if the light reflecting structures 17 and 18 are formed on both the first electrode 30 and the second electrode 40, the light that has traveled to both regions can be selectively reflected to effectively reduce the light loss. . Further, in the light emitting element of Embodiment 1, since both electrodes 30 and 40 are arranged on the same surface side, if a light reflecting structure is formed on both electrodes, light is reflected on almost the entire main surface of the light emitting element. A region is provided, and the light extraction efficiency can be increased. In the light emitting element of FIG. 1, the optical characteristics of the light reflecting structures 17 and 18 formed on both electrodes 30 and 40 are substantially the same. If the light reflecting structures provided on both electrodes are substantially the same, unevenness in the emission color of the light emitting element can be reduced, and the manufacturing process can be simplified by forming both light reflecting structures simultaneously. On the other hand, the light reflecting structures 17 and 18 provided on the electrodes 30 and 40 may have a difference in optical characteristics. For example, the thickness of each layer constituting the first and second reflective films 1 and 2 is determined in consideration of the incident angle of light by the electrode part, the distance from the wavelength conversion member provided on the light emitting element, and the like. Can be determined.

(Electrode film)
After the light reflecting structures 17 and 18 are formed on the semiconductor element structure 20, electrode films 32 and 42 that are electrically connected to the semiconductor element structure 20 are formed. The electrode films 32 and 42 are formed as the first electrode 30 and the second electrode 40 in contact with the n-type semiconductor layer and the p-type semiconductor layer, the appropriately provided translucent conductive film, and the light reflecting structures 17 and 18, respectively. Is done. The electrode films 32 and 42 electrically connect the light emitting element and the external electrode and function as a pad electrode. For example, a conductive member such as an Au bump is disposed on the surface of the electrode film, and the electrode of the light emitting element is electrically connected to the external electrode disposed opposite to the conductive member via the conductive member. For the electrode films 32 and 42, an existing configuration can be adopted as appropriate, and for example, the electrode films 32 and 42 are made of any metal of Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, alloys thereof, or combinations thereof. As an example of the electrode films 32 and 42, a laminated structure of Ti / Pt / Au or Ti / Rh / Au can be adopted from the lower layer side. In the present embodiment, the electrode films 32 and 42 are formed in contact with at least a part of the translucent conductive films 31 and 41, but a part of the electrode film is a through hole provided in the translucent conductive film. It may be provided as a contact portion that extends inward or directly contacts the semiconductor layer outside the translucent conductive film. By providing such a contact portion in part of the electrode film, the adhesion between the electrode film and the semiconductor element structure can be improved. In addition, the electrode film formed on the semiconductor layer of each conductivity type has the same configuration and the same type of metal to be used, and is formed at the same time. Can be simplified. The n-side electrode when separately provided is, for example, a W / Pt / Au electrode laminated in order from the semiconductor layer side (the film thickness is, for example, 20 nm / 200 nm / 500 nm, respectively) or a W / P laminated with Ni. Pt / Au / Ni or Ti / Rh / Pt / Au electrodes can be used.

(Protective film)
After forming the electrode film, the insulating protective film 50 can be formed on almost the entire surface of the semiconductor light emitting element except for the connection region with external electrodes and terminals. Therefore, the openings 33 and 43 are formed in the protective film 50 covering the n-side electrode portion and the p-side electrode portion, respectively. The protective film 50 is _{SiO 2, TiO 2, Al 2} O 3, available polyimide and the like. Note that the insulating film 3 and the protective film 50 may be used together in the same member, that is, it is preferable that the protective film and the insulating film are formed as the same process and the same film because the process can be simplified.

  In the above example, the example in which the light-emitting element having the p-side electrode and the n-side electrode on the same surface is flip-chip mounted has been described. However, the present invention can also be applied to a light-emitting element having a counter electrode structure. In a light emitting element with a counter electrode structure, a light reflecting structure is provided at least on the electrode on the wiring board side on which the light emitting element is placed, so that light traveling to the light reflecting structure is reflected to the opposite light extraction surface side. can do. Also, a light reflecting structure may be formed on the electrode formed on the light extraction surface side to suppress light absorption to the electrode, thereby increasing the external quantum efficiency, and providing a light reflecting structure on both main surfaces. You can also. In the light-emitting element mounted face-up, the light reflecting structure of the present invention may be provided on the light extraction side electrode. Further, a light reflecting structure can be provided on the side surface of the semiconductor layer, the side surface of the light emitting structure, or the region of the element surface, for example, in a superimposed manner corresponding to the protective film.

<Embodiment 2>
FIG. 5 is a schematic cross-sectional view in which the periphery of the light reflecting structure of the light emitting element according to Embodiment 2 is partially enlarged. In the light emitting element of the example shown in FIG. 5, the same reference numerals are given to substantially the same configurations as those in the first embodiment, and description thereof will be omitted as appropriate.

  In the light reflecting structures 17 and 18 of the second embodiment, the first reflecting film 1 is formed on a substantially flat surface of the translucent conductive films 31 and 41, and is substantially below the covering portions 36 and 46 that are upper surfaces thereof. Continuing from the flat surface, it has a side surface of an inclined surface inclined inward from the surface, that is, an inclined surface facing the semiconductor layer 20 side, and the film thickness becomes closer to the conductive portions 35 and 45 side. Is getting smaller. The second reflective film 2 is formed on the first reflective film, and the insulating film 3 is formed on the second reflective film, and similarly inclines inward from the upper surface on the coating portion side of each film. It has a side surface, and the film thickness decreases as it approaches the conduction portion side. As described above, the side surfaces of the light reflecting structures 17 and 18 are inclined surfaces that are inclined from the substantially flat surface, which is the upper surface thereof, toward the central portion. Therefore, the light reflecting structures 17 and 18 in the second embodiment have an inclined portion inclined in the opposite direction to the light reflecting structure in the first embodiment at the end thereof, and the second reflecting film 2 extends. The projecting portions 17 a and 18 a extend from the first reflective film 1 to the conducting portions 35 and 45. As described above, the first reflective film 1 may have side surfaces facing the conductive portions 35 and 45, and the extending portions 17 a and 18 a may be provided on the side surfaces of the first reflective film 1.

  In the light reflection structures 17 and 18 having such a form, electrons flowing in the vertical direction flow to the semiconductor layer while diffusing in the horizontal direction in the conductive portions 35 and 45, but the second reflection film extending portions 17a and 18 By providing 18a closer to the center side than the insulating film 3, the protruding portion in which the insulating film 3 protrudes toward the conducting portion from the second reflective film 2 has the effect of constricting the flow of electrons in the conducting portion. 2 It is considered that the collision probability of electrons from the electrode films 32 and 42 to the reflective film 2 is reduced, and the occurrence of electromigration of metal atoms in the second reflective film can be suppressed.

  The light reflecting structures 17 and 18 having such a form are formed by sequentially forming each film constituting the light reflecting structure using a protective film having a side surface of an inclined surface inclined outward from the upper surface thereof. Thus, it can be formed with high productivity as in the first embodiment. Specifically, after the protective film having the above shape is formed on the translucent conductive film and then the first reflective film is formed, the first reflective film having a substantially inverted trapezoidal cross section is formed in the opening of the protective film. Is formed. Subsequently, when the second reflective film is formed thereon, the cross section having a substantially inverted trapezoidal shape with an upper surface wider than the upper surface of the first reflective film on the substantially flat surface of the upper surface of the first reflective film. A second reflective film is formed. Furthermore, if the insulating film formed thereon and the intervening layer interposed therebetween are sequentially formed, a film having a substantially inverted trapezoidal cross section having an upper surface wider than the upper surface of the lower layer is formed. . At this time, as in the first embodiment, the second reflective film and the layer formed on the second reflective film are formed around the gap between the inclined side surface of the lower layer and the side surface of the protective film, It may be formed on the side surface of the lower layer so as to cover a part of the side surface of the lower layer, and the extended portion of the second reflective film may be formed here.

  Further, in the light reflecting structures 17 and 18 of the second embodiment, in the electrode film forming process, between the light reflecting structures 17 and 18 and the electrode films 32 and 42, particularly on the side surfaces of the light reflecting structure. There is a possibility that the air gap 19 is provided in the lower part (near the side surface of the first reflective film 1). However, the light reflection structure and the electrode film are partially separated by the gap 19, and the gap 19 preferably acts as an electrical barrier so that a current flows laterally from the electrode film to the second reflection film 2. This can be suppressed.

(Light emitting device)
The light-emitting element of the present invention may be mounted on a mounting substrate such as a wiring board, a package substrate, or a lead frame to form a light-emitting device, and a light-transmitting member such as a resin or a lens for sealing the light-emitting element is added thereto. Also good. In addition, a wavelength conversion member containing a phosphor excited by light of the light emitting element can be added to the light emitting element by bonding, bonding, or mixing in the light transmissive member. Since the light emitting device of the present invention has a light reflecting structure including the second metal reflection film, the light emitting device has a high reflectivity with respect to light of a wide range of wavelengths, and from a phosphor disposed around the light emitting device. The emitted wavelength converted light can also be efficiently reflected. In addition, since the light reflecting structure has high reliability, it is possible to provide a light-emitting element and a light-emitting device that can suppress generation of luminance and color unevenness and can stably emit light even when driven for a long time and at a high current.

  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.

<Example 1>
As the light emitting element of Example 1, an LED chip having the configuration shown in FIG. 1 is manufactured. First, using a MOVPE reactor, on a 2 inch φ sapphire substrate 1, a buffer layer made of GaN is 20 nm, an n-type contact layer 21 made of Si-doped n-type GaN is 4 μm, and a single layer made of non-doped In _0.2 Ga _0.8 N. The active layer 22 having a single quantum well structure is 3 nm, the p-type cladding layer (23) made of Mg-doped p-type Al _0.1 Ga _0.9 N is 0.2 μm, and the p-type contact layer (23) made of Mg-doped p-type GaN is 0 Growing sequentially with a film thickness of 5 μm.

  Further, the wafer is annealed in a reaction vessel under a nitrogen atmosphere at a temperature of 600 ° C. to further reduce the resistance of the p-type nitride semiconductor layer 23. After annealing, the wafer is taken out of the reaction vessel, a mask having a predetermined shape is formed on the surface of the uppermost p-type GaN, and etching is performed from above the mask with an etching apparatus. As shown in FIG. To expose a part of

  Next, the mask on the p-type nitride semiconductor layer is removed, and ITO is formed as the translucent conductive layers 41 and 31 on the almost entire surface of the uppermost p-type GaN (23) and the exposed n-type contact layer 21. Is sputtered with a film thickness of 800 nm.

  Next, masks having inclined side surfaces inclined inward from the upper surface are formed on the ITO formed on the p-type and n-type contact layers, respectively. At this time, a pattern is formed on the p-type contact layer so that a square mask having a side of 10 μm is arranged at a lattice point (interval is 30 μm). On the other hand, a mask having one semicircular opening with a diameter of 100 μm is formed on the n-type contact layer.

Then, a SiO ₂ film having a thickness of 500 nm is formed as a light-transmitting insulating film of the first reflective film 1 by sputtering, and Nb ₂ O ₅ / SiO is formed as a dielectric multilayer film of the first reflective film 1. ₂ Three pairs (film thickness 55 nm / 90 nm) are stacked. Subsequently, Al (Cu-containing) is formed to a thickness of 200 nm as the second reflective film 2, and subsequently, Ti is formed to a thickness of 100 nm as the adhesion layer. Further, a 200 nm-thick SiO ₂ film is formed thereon as the insulating film 3, and then the mask is removed to obtain the light reflecting structures 17 and 18.

  Ti / Pt / Au (thickness: 1.5 nm / 200 nm / 500 nm) is formed on almost the entire surface of the p-type contact layer and the exposed n-type contact layer through the light reflecting structures 17 and 18 by sputtering. The pad electrodes 42 and 32 having a laminated structure are formed. Thus, the electrode film covers the surface of the light reflecting structure and the exposed surface of the semiconductor layer, and has the covering portions 36 and 46 and the conducting portions 35 and 45. The second reflecting film of the light reflecting structure includes the first reflecting film. Extending portions 17a and 18a extending from the insulating film and in contact with the electrode film are formed on the inclined portion of one reflective film.

  As described above, the wafer in which the electrode film is formed on the n-type contact layer and the p-type contact layer is cut into 1 mm square chips to obtain LED chips.

<Comparative Examples 1 and 2>
The light emitting device of Comparative Example 1 is manufactured in the same manner as in Example 1 except that the light reflection structures 17 and 18 are formed except for the insulating film 3 in Example 1. The light emitting device of Comparative Example 2 is manufactured in the same manner as in Example 1 except that the light reflecting structures 17 and 18 are formed except for the second reflective film 2 and the insulating film 3 in Example 1.

  When the light emitting elements of Example 1 and Comparative Example 1 were driven at a temperature of 85 ° C. and a current value of 1600 mA for 1000 hours, the light emitting element of Comparative Example 1 was discolored to a part of the n-side pad electrode due to the occurrence of Al electromigration. However, no abnormality is observed in the appearance of the light-emitting element of Example 1. When the light-emitting elements of Example 1 and Comparative Example 2 are driven at room temperature and a current value of 350 mA, the light-emitting element of Comparative Example 2 emits light with a forward voltage of 3.14 V and an optical output of 568 mW. Emits light at a forward voltage of 3.14 V and an optical output of 598 mW, and the optical output is 5% or more higher than that of the light emitting device of Comparative Example 2.

  The light-emitting element of the present invention and the light-emitting device equipped with the light-emitting element are suitably used for illumination light sources, backlight sources such as LED displays and liquid crystal display devices, traffic lights, illumination switches, various sensors, and various indicators. be able to.

17, 18 ... Light reflection structure (first electrode side 17, second electrode side 18) (1 ... first reflection film, 2 ... second reflection film, 3 ... insulating film), 17a, 18a ... extension part, 19 ... Gap 10 ... Substrate (11 ... Uneven structure),
DESCRIPTION OF SYMBOLS 20 ... Semiconductor element structure (21 ... 1st conductivity type layer (n-type layer), 22 ... Active layer (light emitting layer), 23 ... 2nd conductivity type layer (p-type layer), 25 ... Light emission structure part, 26 ... Non Light emitting structure (electrode forming part),
DESCRIPTION OF SYMBOLS 30 ... 1st electrode (31 ... 1st layer [translucent conductive film], 32 ... 2nd layer [electrode film], 33 ... External connection part [opening part of protective film], 34 ... Extension | extension part, 35 ... Conduction Part [opening part of light reflection structure], 36 ... covering part 40 ... second electrode (41 ... first layer, 42 ... second layer, 43 ... external connection part [opening part of protective film], 45 ... conduction part [Opening part of light reflecting structure]), 46 ... covering part 50 ... protective film

Claims (13)

A semiconductor device structure;
A light reflecting structure provided in a part on the semiconductor element structure and including a light-transmitting and insulating first reflecting film, a metal second reflecting film, and an insulating film in this order;
An electrode film having a covering portion for covering the light reflecting structure with the semiconductor element structure sandwiched on the light reflecting structure; and a conductive portion on the semiconductor element structure exposed from the light reflecting structure. ,
The second reflective film is a light emitting device having an extended portion that extends from at least one of the first reflective film and the insulating film to the conductive portion and contacts the electrode film.   2. The first reflective film has an inclined portion that is continuous from the first reflective film on the covering portion side and has an inclined portion that inclines toward the semiconductor element structure side in the extending direction in the extending portion. Light emitting element.   The light emitting element according to claim 1, wherein the extending portion is provided on a side surface of the first reflective film on the conductive portion side.   4. The light emitting device according to claim 2, wherein the first reflective film has a dielectric multilayer film in which two or more kinds of dielectric films having different refractive indexes are periodically stacked. 5.   5. The light-emitting element according to claim 1, wherein a film thickness of the extending portion decreases in the extending direction.   6. The light emitting device according to claim 1, wherein a gap is provided between the second reflective film and the electrode film in the extending portion.   7. The light emitting device according to claim 1, wherein a plurality of the conductive portions are provided within a surface of the surface of the semiconductor element structure, and at least one of the conductive portions is surrounded by the covering portion. The semiconductor element structure has first and second conductivity type semiconductor layers, and has the electrode film and the light reflection structure on the same surface side of the first and second conductivity type semiconductor layers,
The light emitting device according to claim 7, wherein all conductive portions on the second conductive type semiconductor layer are conductive portions surrounded by the covering portion.   The light emitting device according to any one of claims 1 to 7, wherein the light emitting device has an extending side portion in which the electrode film and the light reflecting structure extend side by side.   9. The conductive portion on the first conductive type semiconductor layer is provided on an outer peripheral portion of the electrode film, and the light reflecting structure on the first conductive type semiconductor layer is provided only on the inner side of the outer peripheral portion. Or 9.   The light emitting element of any one of Claims 1 thru | or 10 which has a translucent electrically conductive film between the said semiconductor element structure, the electrode film of the said conduction | electrical_connection part, and the said light reflection structure.   The light emitting device according to claim 11, further comprising a second light reflecting structure having the first reflecting film between the light transmitting conductive film and the semiconductor element structure.   The light emitting element according to claim 12, wherein the conductive portion is disposed in the second light reflecting structure within the surface of the light transmissive conductive film.

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