JP2012156272A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of preventing unevenness of light emission and capable of emitting light more uniformly.SOLUTION: A light-emitting device comprises: a semiconductor part having a first primary surface and a second primary surface; a first electrode provided on the first primary surface side; and a second electrode provided on the second primary surface side. The first electrode includes more than three external connection parts arranged so as to surround the center of the first primary surface and first extending parts extending toward the center of the first primary surface from the external connection parts.

Description

  The present invention provides a light emitting device comprising: a semiconductor portion having a first main surface and a second main surface; a first electrode provided on the first main surface side; and a second electrode provided on the second main surface side. It relates to an element.

  As a conventional light emitting element, there is one in which a “pad” is arranged at the center of the light emitting element, and a “thin wire electrode” is extended from the “pad” in a cross shape (see Patent Document 1).

JP 2008-282851

  However, the conventional structure has a problem that the current density is not uniform, and accordingly, the light emission is uneven. Generally, a current density is high in a region close to a pad to which a wire for supplying a current from the outside is connected, and even if there is a thin wire electrode, the current density is lowered. Therefore, in the conventional structure, only the vicinity of the pad emits light strongly, and weak light emission occurs at the tip of the thin wire electrode. As a result, there is a problem that uneven light emission occurs as a whole element.

  This invention is made | formed in view of this situation, and makes it a subject to provide the light emitting element which suppresses light emission nonuniformity and can light-emit more uniformly.

  A light emitting device according to an embodiment includes a semiconductor portion having a first main surface and a second main surface, a first electrode provided on the first main surface side, and a second electrode provided on the second main surface side. And comprising. The first electrode includes three or more external connection portions arranged so as to surround the center portion of the first main surface, and a first extension portion extending from the external connection portion toward the center portion of the first main surface. Prepare.

FIG. 2 is a plan view of the light emitting element according to Embodiment 1 as viewed from the first electrode side. It is sectional drawing in the XX part of FIG. 4 is a diagram for explaining a light emission state of the light emitting element according to Embodiment 1. FIG. It is the top view which looked at the light emitting element concerning Embodiment 2 from the 1st electrode side. 6 is a diagram for explaining a light emitting state of a light emitting element according to Embodiment 2. FIG. It is the top view which looked at the light emitting element concerning Embodiment 3 from the 1st electrode side. It is a figure for demonstrating the light emission state of the light emitting element which concerns on Embodiment 3. FIG.

  Hereinafter, embodiments for implementing a light-emitting device according to the present invention will be described with reference to the drawings. However, the form shown below is an illustration for embodying the technical idea of the present invention, and the present invention is not limited to the following unless otherwise specified. Further, in principle, the same names and symbols indicate the same or the same members, and detailed description thereof will be omitted as appropriate.

<Embodiment 1>
FIG. 1 is a plan view of the light emitting device 100 according to the present embodiment as viewed from the first electrode 20 side, and FIG. 2 is a cross-sectional view taken along a line XX in FIG. FIG. 3 shows simulation results for showing the current density of the light emitting element 100. Note that light emission is strong when the current density is high, and light emission is weak when the current density is low. Therefore, the intensity of light emission can be grasped from FIG.

  As shown in FIGS. 1 to 3, the light emitting device 100 according to this embodiment includes a semiconductor unit 10 having a first main surface 11 and a second main surface 12, and a first electrode provided on the first main surface 11 side. 20 and a second electrode 30 provided on the second main surface 12 side. The first electrode 20 extends from the external connection portion 21 toward the central portion C of the first main surface 11 by three or more external connection portions 21 disposed so as to surround the central portion C of the first main surface 11. A first extending portion 22. Here, the “center C” refers to an intersection when the first main surface 11 is equally or substantially equally divided into four by two straight lines intersecting each other. For example, as shown in FIG. 1, when the first major surface 11 is a square, the intersection of two diagonal lines is “center C”.

  Thereby, the current density unevenness on the first main surface can be further reduced, and more uniform light emission can be obtained. Hereinafter, the mechanism will be described.

  Generally, a conductive member such as a wire is directly connected to the external connection portion in order to pass a current to the light emitting element. As a result, the current density is high in a region near the external connection portion, and the current density is low in a region far from the external connection portion. In order to compensate for this, an attempt has been made to provide an extension part extending from the external connection part and diffuse the current over a wider area. However, even if the extension portion is provided, the current density decreases as the distance from the external connection portion increases, and it is difficult to obtain uniform light emission as the entire device.

  Therefore, by arranging three or more external connection portions 21 so as to surround the central portion C of the first main surface 11, the external connection portions 21 that can expect strong light emission are arranged in a wide area away from the central portion C. ), Strong light emission can be obtained even in a region away from the central portion C (see FIG. 3). Furthermore, as a result of providing the 1st extending | stretching part 22 extended | stretched toward the center part C from each external connection part 21, the distance of the two adjacent 1st extending | stretching parts 22 can be shortened, so that it becomes close to a center part. That is, the first extending portion 22 emits less light as the distance from the external connecting portion 21 increases, but the distance from the other adjacent first extending portion 22 decreases as the distance from the external connecting portion 21 increases. Even in the extending direction of 22, it is possible to ensure sufficient intensity of light emission (see FIG. 3). As a result, as shown in FIG. 3, more uniform light emission is possible while obtaining light emission with sufficient intensity on the first main surface. Hereinafter, main components constituting the light emitting element 100 will be described.

(Semiconductor part 10)
The material constituting the semiconductor unit 10 and the structure thereof are not limited, and various materials can be adopted. In the present embodiment, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked (not shown), and a nitride semiconductor (In _X Al _Y Ga _1-XY N N is used as a material for each layer. (0 ≦ X <1, 0 ≦ Y <1, 0 ≦ X + Y <1)). Nitride semiconductors have a higher resistance inside the semiconductor than other materials such as GaAs, and it is difficult to effectively spread the current. Therefore, this embodiment is particularly effective when the semiconductor portion is made of a nitride semiconductor.

  In the present embodiment, the n-type semiconductor layer side is the first main surface 11, and the p-type semiconductor layer side is the second main surface 12. The first main surface 11 and the second main surface 2 are located on opposite sides of the semiconductor unit 10. In the light emitting element 100, the first main surface 11 is a light extraction surface, and the second main surface 12 is mounted on a support portion 40 or the like described later.

  In the present embodiment, the first main surface 11 has a square shape. However, the shape of the first main surface 11 can be variously selected. In general, since the light emitting element is obtained by being separated from one wafer, the shape of the first main surface 11 is preferably square (or substantially square) in consideration of the yield. As will be described later, it is preferable that the external connection portion 21 is arranged on the circumference of the circle and the first main surface 11 is effectively used, and the shape thereof is a square (or a substantially square).

  In the present embodiment, the shape of the first main surface 11 is a square and one side thereof is about 3 mm. However, the size of the first main surface 11 can be variously selected. When the shape of the 1st main surface 11 is a square (or substantially square), the one side can be 1.5 mm or more, Preferably it is 2.0 mm or more, More preferably, it can be 2.5 mm or more. This is because if the area of the first main surface 11 is small, the current density becomes excessively high when three or more external connection portions 21 are provided, which is not preferable. Although there is no particular upper limit on one side, in order to obtain the semiconductor part 10 with a certain crystallinity and good mass productivity, it can be 4.5 mm or less, preferably 4.0 mm or less, more preferably 3.5 mm or less.

(First electrode 20)
The first electrode 20 is an electrode provided on the first main surface 11 side, and includes an external connection portion 21 and a first extending portion 22. Specifically, three or more external connection portions 21 are provided around the central portion C so as to surround the central portion C in a plan view when the light emitting element 100 is viewed from the first main surface 11 side. The external connection portion 21 is a portion to which current is supplied from the outside through a conductive member such as a wire, and is a so-called pad portion.

  Each of the external connection portions 21 includes a first extending portion 22 that extends toward the central portion C. That is, the 1st extending | stretching part 22 is comprised so that the distance with the other adjacent 1st extending | stretching part 22 may become near as it leaves | separates from the external connection part 21 (as it approaches the center part C).

  The structure and material of the first electrode 22 are not limited, and various types can be used. In the present embodiment, the first electrode 22 has a structure in which Ti / Pt / Au (which means that Ti, Pt, and Au are sequentially stacked from the semiconductor portion 20) are sequentially stacked.

  Each of the external connection portions 21 is preferably arranged at equal intervals on the circumference of a circle centered on the center portion C of the first main surface 11 (see FIG. 1). Thereby, not only the distance from the center part C to each external connection part 21 can be made the same, but also the distance between the adjacent external connection parts 21 can be made the same. Light can be emitted more uniformly. Furthermore, if a lens is arranged on the first main surface 11 side, the optical design can be easily performed by making the light emitting region of the first main surface 11 circular. Here, the fact that the external connection portions 21 are arranged at “equal intervals” is not limited to the case where the external connection portions 21 are completely arranged at equal intervals. For example, the distance between the external connection portion arranged at a predetermined position and the external connection portion on one side adjacent to the external connection portion, and the external connection portion on the other side adjacent to the external connection portion arranged at the predetermined position. Even when the difference from the distance is within ± 10%, preferably within ± 5%, more preferably within ± 2%, it is assumed that the external connection portions are arranged at substantially equal intervals. Say it.

  In particular, each of the external connection portions 21 is preferably arranged on the circumference of a circle that passes through the vicinity of the edge of the first main surface 11 with the center portion C of the first main surface 11 as the center (see FIG. 1). . Thereby, in the 1st main surface 11, since the area | region enclosed by the external connection part 21 can be made into the maximum, more uniform light emission is attained in a wider area | region.

  The first electrode 20 is preferably arranged so as to be point-symmetric with respect to the central portion C of the first main surface 11 (see FIG. 1). That is, even if the first electrode 20 (including the external connection portion 21 and the first extending portion 22) is rotated 180 degrees around the center portion C, it is preferable that the same shape is obtained before and after the rotation. Thereby, the inside of the area | region enclosed by the external connection part 21 can be light-emitted more uniformly. Here, the fact that the first electrode 20 is “point-symmetric” is not limited to the case where the first electrode 20 is completely point-symmetric. For example, even if the first electrode is slightly deviated before and after the rotation, it is substantially point-symmetric and is referred to as “point symmetry”.

  In the light emitting element 100, the external connection portion 21 has a circular shape, a diameter of about 170 μm, and the number thereof is twelve. However, the size and number of the external connection portions 21 can be variously selected in consideration of the size of the current flowing through the light emitting element 100, the size of the first main surface 11, and the like. If the external connection portion 21 is large, light is blocked, which is not preferable. Conversely, if the external connection portion 21 is small, it is not preferable because connection of a wire or the like becomes difficult. Moreover, when there are many external connection parts 21, not only the area | region where light emission is excessively strong between adjacent external connection parts arises, but it interrupts | blocks light unnecessarily, and is unpreferable. On the contrary, if the number of external connection portions 21 is small, a region where light emission is weak occurs between two adjacent external connection portions 21, which is not preferable. Considering these, the number of external connection portions can be 3 or more, preferably 6 or more, more preferably 8 or more, and still more preferably 12 or more.

  In the light emitting element 100, the width | variety of the 1st extending | stretching part 22 shall be about 30 micrometers, and the length is about 0.9 mm. However, the width | variety and length of the 1st extending | stretching part 22 can be variously selected. For example, when the light emission at the center portion C is strong, all or a part of the first extending portions 22 can be shortened so that the end portions thereof are separated from the center portion C. On the contrary, when the light emission of the center part C is weak, all or a part of the first extending part 22 can be lengthened so that the end part approaches the center part C.

  In the present embodiment, the first extending portion 22 is configured to extend from the external connecting portion 21 to the central portion C in the entire area, but the first extending portion 22 is partially directed from the external connecting portion 21 to the central portion C. It can also be stretched in different directions. Furthermore, the 1st electrode 20 should just have the 3rd or more external connection part 21 and the 1st extending | stretching part 22 extended | stretched from them, and it may have the external connection part which does not have a 1st extending | stretching part other than that. Good.

(Second electrode 30)
The second electrode 30 is an electrode provided on the second main surface 12 side. The structure and material of the second electrode 30 are not limited, and various types can be used. In the present embodiment, the second electrode 30 has a structure in which Ti / Pt / AuSn / Au (which means that the layers are sequentially stacked from the semiconductor portion 10 side) are sequentially stacked. Note that the second electrode 30 does not need to be provided directly on the second main surface 12, and can be provided on the support portion 40 described later as in the present embodiment.

(Supporting part 40)
In the present embodiment, the light emitting element 100 includes a support portion 40 for supporting the semiconductor portion 10. The structure and material of the support portion 40 are not limited, and various types can be used. In this embodiment, CuW is used as the support portion 40.

  The support portion 40 is electrically connected to the second main surface 12 via a conductive member (not shown), and includes the second electrode 30 on the opposite side to which the second main surface 12 is connected. The conductive member provided between the support portion 40 and the semiconductor portion 10 may be disposed so as not to overlap the first electrode 20 when the semiconductor portion 10 is seen from the first main surface 11 side. preferable. This is because a current can flow through a wide region of the semiconductor unit 20 by shifting the positions of the first electrode 20 and the conductive member. In the present embodiment, Ag / Ni / Ti / Pt (meaning that the layers are sequentially laminated from the semiconductor portion 10 side) is used as the conductive member.

  In the present embodiment, the light emitting element 100 has a structure including the support portion 40, but the support portion 40 is not an essential configuration. When the support part 40 is not provided, the second electrode 30 can be directly provided on the second main surface 12 of the semiconductor part.

<Embodiment 2>
FIG. 4 is a plan view of the light emitting element 200 according to the present embodiment as viewed from the first electrode 20 side, and FIG. 5 is a simulation result for showing the current density level of the light emitting element 200 (light emission intensity). Hereinafter, a configuration different from that of the first embodiment will be described.

  The light emitting element 100 according to the first embodiment is provided with twelve external connection portions 21, but the light emitting element 200 according to the present embodiment is provided with sixteen external connection portions 21. Similarly, twelve first extending portions 22 are provided in the light emitting device 100 according to the first embodiment, whereas the sixteen first extending portions 22 are provided in the light emitting device 200 according to the present embodiment. Yes. Since the number of the external connection parts 21 and the 1st extending | stretching part 22 is increasing compared with Embodiment 1, as a result, the space | interval of the external connection parts 21 narrows, and the space | interval of the 1st extending | stretching parts 22 extended | stretched from there also is also obtained. It is narrowing.

  As a result, the light emitting element 200 reduces the area of weak light emission between the two adjacent external connection portions 21 and the two adjacent first extending portions 22 as compared with the light emitting device 100, and the vicinity of the central portion C is reduced. Light emission can be increased (see FIG. 5).

<Embodiment 3>
6 is a plan view of the light emitting device 200 according to the present embodiment as viewed from the first electrode 20 side, and FIG. 7 is a simulation result for showing the current density of the light emitting device 300 (the intensity of light emission). Hereinafter, a configuration different from that of the first embodiment will be described.

  As shown in FIG. 6, in the present embodiment, the first electrode 20 includes a second extending portion 23 that extends from both the external connection portion 21 and the first extending portion 22 in a direction different from the first extending portion 22. Yes. Thereby, since the 2nd extending | stretching part 23 can be arrange | positioned in the area | region where the light emission produced between the two adjacent 1st extending | stretching parts 22 between the two adjacent external connection parts 21 in Embodiment 1 is concerned, More uniform light emission is possible in the region (see FIG. 7).

  The light emitting element 300 will be described more specifically. In the two adjacent first extending portions 22a and 22b, one first extending portion 22a extends toward the other first extending portion 22b. A portion 23a is provided. Further, the other first extending portion 22b includes a second extending portion 23b extending toward a region sandwiched between the two second extending portions 23a. Thereby, compared with the case where three 2nd extending | stretching parts are provided in the fixed area | region of one 1st extending | stretching part, more uniform light emission can be obtained. That is, firstly, the second extending portion is not provided densely in a predetermined region and is more uniformly arranged, so that more uniform light emission is possible in a wide region. Second, although the region sandwiched between the two second extending portions 23a may be weak in light emission, by arranging the second extending portion 23b there, two adjacent first extending portions 22a, Even in a narrow region sandwiched between 22b, more uniform light emission is possible.

  In one of the two first extending portions 22a and 22b adjacent to each other, the two second extending portions 23a are separated from the external connection portion 21a (the distance between the first extending portions 22a and 22b). It is provided to be shorter as the value becomes smaller. Thereby, since it can suppress that light emission becomes strong too much, more uniform light emission can be obtained in the narrow area | region pinched by two adjacent 1st extending | stretching parts 22a and 22b.

  Each of the first extending portions 22 is configured to be connected to each other in the vicinity of the center portion C. That is, the tip of the first extending portion 22 is provided with a circular second extending portion 23 surrounding the central portion C in the vicinity of the central portion C, and the plurality of first extending portions 22 are circular second extending portions. 23 are electrically connected. Thereby, it can be made more uniform light emission in the central part C vicinity.

  Further, the first electrodes 22 extending from the two external connection portions 21 located on the opposite sides across the center portion C are connected to each other at the center portion C. Here, the two external connection parts 21 located on each diagonal line of the 1st main surface 12 which is a square are connected by the common 1st extending | stretching part 22. FIG. Thereby, since the 1st extending | stretching part 22 passes the center part C, as a result of being able to carry out strong light emission also in the center part C, the light emission nonuniformity can be reduced more as a whole.

  Here, the second extending portion 23 is configured to extend from both the external connecting portion 21 and the first extending portion 22. However, the second extending portion 23 may be extended from one of the external connecting portion 21 and the first extending portion 22 in consideration of light emission unevenness. It is not necessary for all the first extending portions 22 to include the second extending portions 23, and a part of the first extending portions 22 may be configured to include the second extending portions 23. The first extending portion 22a can include three or more second extending portions, and the first extending portion 22b can include two or more second extending portions. All or a part of the external connection parts 21 can be connected by the second extension part 23, or a part of the first extension part 22 can be connected.

DESCRIPTION OF SYMBOLS 100, 200, 300 ... Light emitting element 10 ... Semiconductor part 20 ... 1st electrode 21 ... External connection part 22 ... 1st extending | stretching part 23 ... 2nd extending | stretching part 30 ... 2nd electrode 40 ... support part

Claims (7)

In a light emitting device comprising: a semiconductor portion having a first main surface and a second main surface; a first electrode provided on the first main surface side; and a second electrode provided on the second main surface side. ,
The first electrode includes three or more external connection portions arranged so as to surround a central portion of the first main surface, and a first extension extending from the external connection portion toward the central portion of the first main surface. And a light emitting element.   The said 1st electrode is provided with the 2nd extending | stretching part extended | stretched in a direction different from the said 1st extending | stretching part from at least one among the said external connection part and the said 1st extending | stretching part. Light emitting element. In the two adjacent first extending portions,
One first extending portion includes two second extending portions extending toward the other first extending portion,
2. The light emitting device according to claim 1, wherein the other first extending portion includes a second extending portion extending toward a region sandwiched between the two second extending portions.   4. The light emitting device according to claim 1, wherein the external connection portions are arranged at equal intervals on a circumference of a circle centering on a central portion of the first main surface.   The said external connection part is arrange | positioned on the circumference | surroundings of the circle | round | yen which passes along the edge vicinity arrangement | positioning of the said 1st main surface centering on the center part of the said 1st main surface. The light emitting element in any one. In the one first extending portion,
4. The light emitting device according to claim 3, wherein the two second extending portions are provided so as to become shorter as the distance from the external connection portion increases. 5.   The light emitting device according to claim 1, wherein the first electrode is disposed so as to be point-symmetric with respect to a center portion of the first main surface.