JP2013120945A - Light-emitting element and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element and a light-emitting device, which greatly improve a current density in a PN junction; maximize a heat sink effect (heat radiation effect); and achieve an increased light emission amount and improved light emission efficiency.SOLUTION: A light-emitting device comprises: an overlapping part where a PN semiconductor lamination structure 1, a P-type semiconductor layer 11 and an N-type semiconductor layer 13 overlap each other; and a non-overlapping part 14 where the PN semiconductor lamination structure 1, the P-type semiconductor layer 11 and the N-type semiconductor layer 13 do not overlap each other. The non-overlapping part 14 is arranged lateral to the overlapping part and has a width W1 viewed in arrangement direction narrower than a width W2 of the overlapping part, and the N-type semiconductor layer 13 appears. A P-side electrode 5 and an N-side electrode 7 are provided on a surface on the side opposite to a light emission surface 30. The N-side electrode 7 is provided on the N-type semiconductor layer 13 in the non-overlapping part 14 and electrically insulated from the P-type semiconductor layer 11 and the P-side electrode 5 by an insulation gap G1. The P-side electrode 5 covers almost an entire surface of the P-type semiconductor layer 11 except the insulation gap G1.

Description

  The present invention relates to a light emitting element and a light emitting device using a light emitting diode.

  A light-emitting element using a light-emitting diode has advantages of energy saving and long life, and has attracted attention as a light source such as a lighting device, a color image display device, a liquid crystal panel backlight, or a traffic light.

  For example, when a light-emitting element using a light-emitting diode is a blue light-emitting element, as disclosed in Patent Document 1, a buffer layer, an N-type GaN layer, an active layer, A P-type GaN layer and a transparent electrode layer are sequentially stacked.

  A P-side electrode is formed on a part of the surface of the transparent electrode layer, and the transparent electrode layer, the P-type GaN layer and a part of the active layer are dry-etched to expose a part of the N-type GaN layer, An N-side electrode is formed on the exposed N-type GaN layer. The part where the part of the N-type GaN layer is exposed is a part where the P-type GaN layer and the active layer do not overlap with the N-type GaN layer, and the other part overlaps. The overlapping portion becomes a light emitting region, and the non-overlapping portion becomes a non-light emitting region. Patent Documents 2 and 3 also disclose similar laminated structures and electrode structures.

  In mounting on a packaging substrate, conventionally, an LED chip type light emitting element configured as a flip chip (FC) is mounted on a submount substrate, and this assembly is further mounted on the packaging substrate, and the submount is mounted. The electrodes formed on the substrate and the electrodes formed on the packaging substrate are connected by wire bonding.

  However, this assembly structure increases the cost because a submount substrate made of an expensive material such as AlN must be used. Moreover, since it is necessary to connect the electrode formed on the submount substrate and the electrode formed on the packaging substrate by wire bonding, a wire bonding apparatus is necessary, and the production equipment cost increases. This was passed on to the product cost, leading to high costs for light emitting devices.

  As means for solving the above-mentioned problems, Patent Document 4 discloses that a groove is formed on one surface of a silicon submount, two vias (penetrating electrodes) are formed at the bottom of the groove, and an LED die is placed in the groove. A method of manufacturing an LED package that is flip chip mounted and filled with grooves with a protective adhesive is disclosed.

  When such an LED package structure is employed, conventionally, an electrode (usually a P-side electrode) provided in a portion where the P-type semiconductor layer, the active layer, and the N-type semiconductor layer overlap is provided as a through electrode provided on the package side. In general, it was adjusted to the area of the end face. For this reason, the current supply area from the P-side electrode to the P-type semiconductor layer is limited to a flat area that is considerably smaller than the overlapping area, and the current viewed at the junction of the P-type semiconductor layer, the active layer, and the N-type semiconductor layer. There is a problem that the density is lowered, and the light emission amount and the light emission efficiency are lowered.

  Further, since the cross-sectional area of the through electrode provided on the packaging substrate side is small, the heat dissipation when packaged is poor, the temperature of the light emitting element is increased, and the characteristics are deteriorated. In order to avoid this deterioration of characteristics, the supply current value must be suppressed to a small value, which inevitably results in limitations on the improvement of the light emission amount and the light emission efficiency.

  The electrode (usually the N-side electrode) provided in the non-overlapping portion also employs a structure in which the N-side electrode is joined to the end surface of the through electrode in accordance with the shape of the end surface of the through electrode. The contact area is small. For this reason, even if not as much as in the case of the P-side electrode, the light emission amount and the light emission efficiency are adversely affected. In addition, it becomes difficult to align the N-side electrode and the through electrode, and a slight misalignment is likely to cause poor connection between the two. In order to solve the above-described problems, when the area of the N-side electrode or the through electrode is increased, the width of the non-overlapping portion must be increased, and the area of the overlapping portion that becomes the light emitting region is reduced reflectively, The light emission amount and the light emission efficiency are reduced.

JP 2001-210867 A JP 2009-71337 A JP 2008-153634 A JP 2009-111006 A

  An object of the present invention is to provide a light emitting element and a light emitting device that greatly improve the current density seen at the PN junction, maximize the heat sink effect (heat dissipation effect), increase the amount of light emission, and improve the light emission efficiency. That is.

  In order to solve the above-described problems, a light-emitting element according to the present invention includes a PN semiconductor stacked structure in which a P-type semiconductor layer and an N-type semiconductor layer are stacked, a P-side electrode of the P-type semiconductor layer, and the N-type semiconductor layer. N-side electrode. The PN semiconductor multilayer structure has a portion where the P-type semiconductor layer and the N-type semiconductor layer overlap and a portion where they do not overlap. The non-overlapping portion is disposed on the side of the overlapping portion, and the width viewed in the arrangement direction is narrower than the overlapping portion.

  The P-side electrode and the N-side electrode are on a surface opposite to the light emitting surface, and one of the P-side electrode and the N-side electrode (for example, the P-side electrode) is the P-type semiconductor. One of the layers and the N-type semiconductor layer (for example, a P-type semiconductor layer) is provided on the overlapping portion. The other electrode (for example, N-side electrode) is provided on the other semiconductor layer (for example, N-type semiconductor layer) in the non-overlapping portion, and the one semiconductor layer (for example, P-type semiconductor layer) and The one electrode (for example, P-side electrode) is electrically insulated by an insulation gap. In the above structure, the one electrode (for example, the P-side electrode) covers substantially the entire surface of the one semiconductor layer (for example, the P-type semiconductor layer) except for the insulating gap.

  As described above, since the P-side electrode and the N-side electrode are on the surface opposite to the light emission surface, the light emission area is not reduced by the P-side electrode and the N-side electrode. Therefore, it is possible to realize a light-emitting element having a large light emission amount and high light emission efficiency, and can be connected to a through electrode or the like by a flip-chip method, and there is no need to adopt a wire bonding structure.

  The semiconductor stacked structure has a portion where the P-type semiconductor layer and the previous N-type semiconductor layer overlap and a portion that does not overlap, and the portion that does not overlap is arranged on the side of the overlapping portion, and the width seen in the arrangement direction is Since the width is narrower than the overlapping portion, the light emitting area viewed at the overlapping portion is maximized, the light emission amount is large, and a light emitting element with high light emission efficiency can be realized.

  One of the P-side electrode and the N-side electrode (for example, the P-side electrode) is provided on the surface of the other of the P-type semiconductor layer and the N-type semiconductor layer (for example, the P-type semiconductor layer). The other electrode (for example, the N-side electrode) is electrically insulated from the other semiconductor layer (for example, the P-type semiconductor layer) by an insulating gap and is provided in one semiconductor layer (for example, the N-type semiconductor layer). . Therefore, the N-side electrode and the P-side electrode can supply a current to the semiconductor multilayer structure to perform a light emitting operation.

  More importantly, as one of the most important structures and operational effects, one electrode (for example, the P-side electrode) covers almost the entire surface of one semiconductor layer (for example, the P-type semiconductor layer) except for the insulating gap. The current supply area from the P-side electrode to the P-type semiconductor layer is expanded to the same area as the overlapping area. For this reason, the current density seen at the junction of the P-type semiconductor layer, the active layer, and the N-type semiconductor layer is greatly improved, and the light emission amount and the light emission efficiency are also improved. The area of one electrode (eg, the P-side electrode) can be maximized by minimizing the width of the insulating gap to the dimensions required for electrical insulation.

  Moreover, the cross-sectional area of the through electrode provided on the package side is expanded to the area of one maximized electrode (for example, the P-side electrode), and the heat sink effect by the one electrode (for example, the P-side electrode) and the through electrode (Heat dissipation characteristics) can be maximized.

  Since the other electrode (for example, the N-side electrode) is provided in a non-overlapping portion, the non-overlapping portion can be narrowed to increase the electrode area while avoiding a decrease in the light emitting area in the overlapping portion. it can. That is, the electrode area can be expanded by extending the other electrode (for example, the N-side electrode) in the length direction orthogonal to the width. For this reason, it is possible to increase the light emission amount and improve the light emission efficiency, and to avoid poor connection due to misalignment.

  The light emitting device according to the present invention is configured by combining the above light emitting element with a substrate. The substrate has a light emitting element mounting region on one surface, and end faces of the first electrode and the second electrode provided in a thickness direction are exposed in the surface of the light emitting element mounting region, and the first electrode Is matched to the electrode area of the one electrode (for example, the P-side electrode).

  The light emitting element is mounted in the light emitting element mounting region, the one electrode (for example, a P-side electrode) is joined to the first electrode, and the other electrode (for example, the N-side electrode) is connected to the second electrode. It is joined to. Thereby, since the current supply path having substantially the same cross-sectional area is formed by the first electrode and one electrode (for example, the P-side electrode) for the light emitting element, the current density of the light emitting element is improved, the light emission amount, Luminous efficiency can be improved.

  As described above, according to the present invention, the current density seen at the PN junction is greatly improved, the heat sink effect (heat dissipation effect) is maximized, the light emission amount is increased, and the light emission efficiency is improved. And a light-emitting device can be provided.

  Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. The accompanying drawings are merely examples.

It is sectional drawing which shows one form of the light emitting element which concerns on this invention. It is a bottom view of the light emitting element shown in FIG. It is sectional drawing which shows the light-emitting device incorporating the light emitting element which concerns on this invention. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG.

  Referring to FIGS. 1 and 2, the light emitting device according to the present invention is a PN in which a P-type semiconductor layer 11 and an N-type semiconductor layer 13 are stacked on the other surface of the transparent crystal layer 3 opposite to the light emitting surface 30. A semiconductor multilayer structure 1 is included. An active layer 12 is provided between the P-type semiconductor layer 11 and the N-type semiconductor layer 13. The transparent crystal layer 3 is typically sapphire, and one surface thereof becomes the light emitting surface 30. The transparent crystal layer 3 made of sapphire preferably has a layer thickness in the range of 3 μm to 200 μm. A buffer layer (not shown) is provided on one surface of the transparent crystal layer 3 made of sapphire, and the PN semiconductor multilayer structure 1 is grown on the transparent crystal layer 3 through the buffer layer.

  The PN semiconductor multilayer structure 1 is well known in a light emitting device. A PN junction is typically used and a III-V compound semiconductor is typically used. However, it is possible to include not only known techniques but also compound semiconductors that may be proposed in the future. In the present invention, the light emitting element may be any of a red light emitting element, a green light emitting element, a blue light emitting element, and an orange light emitting element, or a white light emitting element. In these light emitting devices, the semiconductor material constituting the PN semiconductor multilayer structure 1 and the manufacturing method thereof are already known.

  The light emitting device according to the present invention includes a PN semiconductor multilayer structure 1 in which a P-type semiconductor layer 11 and an N-type semiconductor layer 13 are laminated, a P-side electrode 5 of the P-type semiconductor layer 11, and an N-side electrode of the N-type semiconductor layer 13. 7 and so on. For example, the P-side electrode 5 and the N-side electrode 7 are flip-chip connected to an external electrode such as a through electrode provided in the package, and are on the surface opposite to the light emitting surface 30. Is provided.

  Of the P-side electrode 5 and the N-side electrode 7, the P-side electrode 5 is an electrode provided on the surface of the P-type semiconductor layer 11 located on the side opposite to the light emitting surface 30. The P-side electrode 5 covers almost the entire surface of the P-type semiconductor layer 11 except for the insulating gap G1. On the other hand, the N-side electrode 7 fills a non-overlapping portion 14 formed by cutting out the P-type semiconductor layer 11 and the active layer 12 and is provided in the N-type semiconductor layer 13. The non-overlapping portion 14 is filled with an electrical insulating layer 9 that electrically insulates the N-side electrode 7 from the P-type semiconductor layer 11 and the active layer 12. The electrical insulating layer 9 also covers the surface of the P-type semiconductor layer 11 exposed between the N-side electrode 7 and the P-side electrode 5, and the N-side electrode 7 is located in the portion 14 where it does not overlap with the P-type semiconductor layer 11. The P-side electrode 7 is electrically insulated by an insulation gap G1.

  The P-type semiconductor layer 11 and the N-type semiconductor layer 13 are overlapped with each other through the active layer 12 except for a portion 14 that does not overlap, and the overlapping portion becomes a light emitting region. The width W1 of the N-side electrode 7 viewed in the arrangement direction of the N-side electrode 7 and the P-side electrode 5 is significantly smaller than the width W2 of the P-side electrode 5. For example, the ratio of the width W1 to the width W2 can be selected in the range of 1 to 40%. In the embodiment, the length L1 orthogonal to the width direction is substantially equal for both the N-side electrode 7 and the P-side electrode 5.

  The electrical insulating layer 9 may be either an organic insulating layer or an inorganic insulating layer. The N-side electrode 7 can be formed by a plating method, a molten metal filling method, a fluid conductive material embedding method, or the like. In this embodiment, the non-overlapping portion 14 is formed over the entire length of the PN semiconductor multilayer structure 1, but it may be provided in an intermediate portion in the length direction. Further, the shape is not limited to the belt shape, but may be other shapes.

  As described above, since the P-side electrode 5 and the N-side electrode 7 are on the side opposite to the light emitting surface 30, the light emitting area is not reduced by the P-side electrode 5 and the N-side electrode 7. Therefore, it is possible to realize a light-emitting element having a large light emission amount and high light emission efficiency, and can be connected to a through electrode or the like by a flip-chip method. There is no need to adopt a wire bonding structure with poor reliability and workability.

  The PN semiconductor multilayer structure 1 has a portion where the P-type semiconductor layer 11 and the N-type semiconductor layer 13 overlap and a portion 14 that does not overlap, and the portion 14 that does not overlap is disposed on the side of the overlapping portion. Although the periphery of the N-side electrode 7 is filled with the electrical insulating layer 9, the thickness of the non-overlapping portion 14 can be regarded as the width W1 of the N-side electrode 7 because the thickness of the electrical insulating layer 9 is thin. Further, the width of the overlapping portion can be regarded as the width W2 of the P-side electrode 5. In this state, the non-overlapping portion 14 has a ratio of the width W1 to the width W2 in the range of 1 to 40%. Accordingly, it is possible to realize a light-emitting element having a maximum light emission area, a large light emission amount, and high light emission efficiency.

  Of the P-side electrode 5 and the N-side electrode 7, the P-side electrode 5 is provided on the surface of the P-type semiconductor layer 11, and the N-side electrode 7 is electrically connected to the P-type semiconductor layer 11 by the electrical insulating layer 9. Insulating is provided in the N-type semiconductor layer 13. Therefore, the N-side electrode 7 and the P-side electrode 5 can supply a current to the PN semiconductor multilayer structure 1 to perform a light emitting operation.

  Moreover, since the P-side electrode 5 covers almost the entire surface of the P-type semiconductor layer 11 except for the insulating gap G1 and the inevitable insulating portion, current supply from the P-side electrode 5 to the P-type semiconductor layer 11 is achieved. The area is enlarged to the same area as the overlapping area. For this reason, the current density seen at the junction of the P-type semiconductor layer 11, the active layer 12, and the N-type semiconductor layer 13 is greatly improved, and the light emission amount and the light emission efficiency are also improved. Under the above structure, the area of the P-side electrode 5 is maximized by minimizing the insulating gap G1 to the size required for electrical insulation and minimizing the width W1 of the N-side electrode 7. can do.

  Since the N-side electrode 7 is provided in the non-overlapping portion 14, the non-overlapping portion 14 can be narrowed to increase the electrode area while avoiding a decrease in the light emitting area in the overlapping portion. That is, the electrode area can be expanded by extending the N-side electrode 7 in the length direction L1 perpendicular to the width W1. For this reason, it is possible to avoid poor connection due to misalignment while increasing the light emission amount and improving the light emission efficiency.

  3 to 5, a light emitting device in which a light emitting element according to the present invention is mounted on a substrate is illustrated. The substrate 2 has a light emitting element mounting region S1 on one surface, and end faces of the first electrode 21 and the second electrode 22 provided in the thickness direction in the surface of the light emitting element mounting region S1 are exposed. The area of the end surface of the first electrode 21 is substantially the same as the electrode area of the P-side electrode 5. The second electrode 22 is the same, and the area of the end face is substantially the same as the electrode area of the N-side electrode 7. The first electrode 21 and the second electrode 22 are generally through electrodes provided so as to penetrate the substrate 1 made of a package substrate or the like in the thickness direction. The first and second electrodes 21 and 22 and the N-side electrode 7 and the P-side electrode 5 can be joined by an Au—Sn bonding material, a solder paste, an Ag paste, a Cu diffusion paste, or the like.

  The light emitting element 100 is mounted in the light emitting element mounting region S <b> 1, the P-side electrode 5 is bonded to the first electrode 21, and the N-side electrode 7 is bonded to the second electrode 22. As a result, a current supply path having substantially the same cross-sectional area is formed by the first electrode 21 and the P-side electrode 5 with respect to the light emitting element 100, so that the current density of the light emitting element 100 is improved, and the light emission amount and the light emission efficiency are increased. Can be improved.

  In addition, the cross-sectional area of the first electrode 21 provided as a through electrode in the substrate 2 made of a packaging substrate or the like is expanded to the area of the maximized P side electrode 5, and the P side electrode 5 and the first electrode as the through electrode The heat sink effect (heat radiation effect) by 21 can be maximized.

  In the embodiment, since the end surface area of the second electrode 22 is substantially the same as the electrode area of the N-side electrode 7, the heat sink effect (heat dissipation effect) by the N-side electrode 7 and the second electrode 22 that is a through electrode is also provided. ) Can also be improved. Further, there is no connection failure due to the displacement of the N-side electrode 7 with respect to the second electrode 22.

  The light-emitting element and the light-emitting device according to the present invention have a wide range of uses such as a single light-emitting element, a surface light-emitting device in which a plurality of light-emitting elements are arranged in a matrix, a lighting device, a backlight for a liquid crystal display, a signal lamp, and the like. Yes.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

DESCRIPTION OF SYMBOLS 1 PN semiconductor laminated structure 3 Transparent crystal layer 5 N side electrode 7 P side electrode

Claims (4)

A light-emitting device including a PN semiconductor stacked structure in which a P-type semiconductor layer and an N-type semiconductor layer are stacked, a P-side electrode of the P-type semiconductor layer, and an N-side electrode of the N-type semiconductor layer,
The PN semiconductor multilayer structure has a portion where the P-type semiconductor layer and the N-type semiconductor layer overlap, and a portion where they do not overlap,
The non-overlapping part is disposed on the side of the overlapping part, and the width seen in the arrangement direction is narrower than the overlapping part,
The P-side electrode and the N-side electrode are on the surface opposite to the light emitting surface,
One of the P-side electrode and the N-side electrode is provided on the overlapping portion on one surface of the P-type semiconductor layer and the N-type semiconductor layer,
The other electrode is provided on the other semiconductor layer in the non-overlapping portion, and is electrically insulated from the one semiconductor layer and the one electrode by an insulating gap,
The one electrode covers almost the entire surface of the one semiconductor layer except the insulating gap,
Light emitting element.   2. The light emitting device according to claim 1, wherein a width of the non-overlapping portion is in a range of 1 to 40% of a width of the overlapping portion when viewed in the arrangement direction.   It is a light emitting element described in Claim 1 or 2, Comprising: The said light-projection surface is comprised with the sapphire which has a layer thickness of 3 micrometers-200 micrometers. A light emitting device including a light emitting element and a substrate,
The light emitting element is described in any one of claims 1 to 3,
The substrate has a light emitting element mounting region on one surface, and end surfaces of the first electrode and the second electrode provided in the thickness direction in the surface of the light emitting element mounting region are exposed, and the first electrode is The area of the end face is matched to the electrode area of the one electrode,
The light emitting element is mounted on the light emitting element mounting region, the one electrode is bonded to the first electrode, and the other electrode is bonded to the second electrode.
Light emitting device.

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