JP2014017283A - Method of manufacturing nitride compound semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a nitride compound semiconductor light-emitting element that can be easily cleaved and divided without patterning to a reflection layer covering whole of a rear face.SOLUTION: A method of manufacturing a nitride compound semiconductor light-emitting element 1 provided with a p-side electrode 6 and an n-side electrode 7 on a surface side, comprises the steps of: forming an n-type nitride compound semiconductor layer 3, an active layer 4, and a p-type nitride compound semiconductor layer 5 on a surface of a substrate 2; polishing a rear face of the substrate 2 to make the substrate 2 thin; forming a division assistance part 2a assisting division of the substrate 2, inside the substrate 2; forming an optical multilayer film reflection layer 8 reflecting light emitted from the active layer 4, on the rear face of the substrate 2; forming a metal reflection layer 9 reflecting light transmitted through the optical multilayer film reflection layer 8, on a rear face of the optical multilayer film reflection layer 8; and dividing the substrate 2 into a plurality of nitride compound semiconductor light-emitting elements 1 at a division surface including the division assistance part 2a.

Description

  The present invention relates to a method for manufacturing a nitride compound semiconductor light emitting device.

  In general, functional elements formed by stacking compound semiconductor layers on hexagonal substrates such as sapphire substrates that function as various devices such as LEDs (Light Emitting Diodes) and HEMTs (Hetero-junction Field Effect Transistors) are known. It has been. For example, by applying a voltage to a semiconductor light emitting device in which an n-type compound semiconductor layer and a p-type compound semiconductor layer are joined via an active layer, electrons contained in the n-type compound semiconductor layer and a p-type compound semiconductor are applied. 2. Description of the Related Art Conventionally, a semiconductor light emitting device using light emission by recombining holes contained in a layer is known.

  As such a semiconductor light emitting element, for example, a blue light emitting diode element is commercially available. Since the blue light emitting diode element uses a direct transition semiconductor in which electrons and holes are efficiently recombined, the light emitting efficiency is very high. For this reason, blue light emitting diode elements are currently widely used for display applications of home appliances, display of traffic lights on roads, and illumination applications. For example, a white light-emitting diode device used for display and lighting applications is manufactured by combining a blue light-emitting diode element and a phosphor such as YAG (yttrium, aluminum, garnet) having a fluorescent wavelength in a yellow region.

  As the blue light emitting diode element, a functional element having a laminated structure of nitride semiconductor layers is used. A functional element having a laminated structure of a nitride semiconductor layer that is generally put into practical use as a blue light-emitting diode element has a structure in which an n-type GaN layer, an active layer, and a p-type GaN layer are sequentially laminated on a sapphire substrate. Yes. Since the sapphire substrate is an insulator, etching is performed from the p-type GaN layer to at least the n-type GaN layer, and an n-type electrode that is in ohmic contact with the n-type GaN layer is formed on the exposed surface of the n-type GaN layer. Provided.

  Here, a blue light emitting diode element is generally known in which a reflective layer is formed on the back surface of a substrate in view of a reflection effect and the like. Since the blue light emitting diode element has a high substrate hardness, the wafer is divided into individual elements by polishing and thinning the substrate when separating the wafer, and then scribing and cleaving from the back surface of the substrate. . Therefore, if a metal layer as a reflective layer is formed on the back surface of the substrate before scribing, there is a problem that alignment during scribing becomes difficult.

  Therefore, a conventional technique for solving this problem is disclosed in Patent Document 1. In the method for manufacturing a semiconductor light emitting device described in Patent Document 1, after forming a reflective layer, a part of the reflective layer is removed and patterned to enable alignment during scribing.

JP 2008-153362 A

  However, in the conventional method for manufacturing a semiconductor light emitting device described in Patent Document 1, a region that is not covered with a reflective layer is formed on a part of the back surface of the semiconductor light emitting device. Thereby, there existed a subject that reflective efficiency fell. Further, since a process for patterning the reflective layer is required, there is a problem that the manufacturing cost increases.

  The present invention has been made in view of the above points, and a nitride capable of easily cleaving and dividing a light-emitting element whose entire back surface is covered with a reflective layer without patterning the reflective layer. An object of the present invention is to provide a method for producing a compound semiconductor light emitting device.

  In order to solve the above problems, the present invention provides a nitride-based compound semiconductor light emitting device in which a plurality of nitride-based compound semiconductor layers are stacked on the surface of a substrate, and a p-side electrode and an n-side electrode are provided on the surface side. A method of forming at least an n-type nitride compound semiconductor layer, an active layer, and a p-type nitride compound semiconductor layer on a surface of the substrate, and polishing the back surface of the substrate to form the substrate A step of forming a dividing assisting portion for assisting the division of the substrate inside the substrate, and an optical multilayer film reflecting layer for reflecting the light emitted from the active layer on the back surface of the substrate Forming a metal reflective layer that reflects light transmitted through the optical multilayer reflective layer on the back surface of the optical multilayer reflective layer, and dividing the substrate into the division plane including the division assisting portion. Dividing into a plurality of elements; It is characterized in that it comprises.

  According to this method, since the division assisting portion is formed inside the substrate, it is not necessary to pattern the reflective layer. Then, the entire back surface of the nitride-based compound semiconductor light-emitting element is covered with the reflective layer.

  In the method for manufacturing a nitride-based compound semiconductor light-emitting device having the above-described configuration, the step of forming the division assisting portion is performed before the step of forming the optical multilayer reflective layer and the step of forming the metal reflective layer. It is characterized by doing. According to this method, there is no need to pattern the reflective layer. Therefore, the entire back surface of the nitride-based compound semiconductor light emitting device is covered with the reflective layer.

  In the method for manufacturing a nitride-based compound semiconductor light-emitting device having the above-described configuration, the division assisting portion is formed by laser processing. According to this method, the division assisting portion is formed inside the substrate.

  In the method for manufacturing a nitride-based compound semiconductor light-emitting device having the above-described configuration, the division assisting portion is formed by irradiating a laser from the back side of the substrate. According to this method, it is not necessary to form a groove for laser irradiation on the surface side of the substrate on which the nitride-based compound semiconductor layer is formed.

In the method for manufacturing a nitride-based compound semiconductor light-emitting device having the above structure, the optical multilayer film reflective layer is formed by alternately laminating a low refractive index film made of SiO ₂ and a high refractive index film made of TiO _2. It is characterized by being. According to this method, the absorption of light emission depending on the metal material can be reduced as compared with the case of using only the metal reflection layer, and the light extraction efficiency of the nitride-based compound semiconductor light-emitting element is improved.

  In the method for manufacturing a nitride-based compound semiconductor light-emitting device having the above-described configuration, the metal reflective layer is made of Ag or Al. According to this method, Ag and Al can reduce light absorption as compared with other metals, and the light extraction efficiency of the nitride-based compound semiconductor light-emitting element is improved.

  According to the configuration of the present invention, a nitride-based compound semiconductor light-emitting device capable of easily cleaving and dividing a light-emitting device whose entire back surface is covered with a reflective layer without patterning the reflective layer is manufactured. A method can be provided.

1 is a cross-sectional view of a nitride-based compound semiconductor light emitting device according to an embodiment of the present invention. 3 is a flowchart illustrating a method for manufacturing a nitride-based compound semiconductor light-emitting device according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  First, the structure of a nitride-based compound semiconductor light emitting device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a nitride compound semiconductor light emitting device.

  As shown in FIG. 1, the nitride-based compound semiconductor light emitting device 1 includes an n-type nitride-based compound semiconductor layer 3, an active layer 4, and a p-type nitride-based compound semiconductor layer 5 on the surface of a substrate 2. They are stacked in this order.

  Part of n-type nitride compound semiconductor layer 3, active layer 4, and p-type nitride compound semiconductor layer 5 are etched to form mesa portion 20. The mesa portion 20 protrudes upward with respect to the n-type nitride compound semiconductor layer 3 in FIG. A p-side electrode 6 is provided on the p-type nitride compound semiconductor layer 5.

  In the etched portion outside the mesa portion 20 (right side in FIG. 1), a part of the upper surface of the n-type nitride compound semiconductor layer 3 is not covered with the active layer 4 or the p-type nitride compound semiconductor layer 5. Is exposed. An n-side electrode 7 is provided on the exposed portion. That is, the p-side electrode 6 and the n-side electrode 7 are provided on the surface side where a plurality of nitride-based compound semiconductor layers are stacked on the surface of the substrate 3.

  Here, the substrate 2 may be an insulating substrate such as sapphire, or may be a conductive substrate such as GaN, SiC, or ZnO. The thickness of the substrate 3 during the growth of the nitride-based compound semiconductor layer is preferably 650 μm to 1200 μm, for example, and the thickness of the substrate 3 in the nitride-based compound semiconductor light emitting device 1 is, for example, 50 μm or more and 300 μm or less. preferable.

The n-type nitride semiconductor layer 3 is a layer in which, for example, Al _{s1 Gat1} In _u1 N (0 ≦ s1 ≦ 1, 0 ≦ t1 ≦ 1, 0 ≦ u1 ≦ 1, s1 + t1 + u1≈1) is doped with an n-type dopant More preferably, Al _s1 Ga _{1 -s1} N (0 ≦ s1 ≦ 1, preferably 0 ≦ s1 ≦ 0.5, more preferably 0 ≦ s1 ≦ 0.1) layer has an n-type dopant. It is a doped layer. The n-type dopant in the n-type nitride semiconductor layer 3 is not particularly limited, and may be Si, P, As, Sb, or the like, and is preferably Si. The thickness of the n-type nitride semiconductor layer 3 is preferably 1 μm or more and 10 μm or less, but is not particularly limited.

  The active layer 4 has a quantum well structure including, for example, a well layer, and may be either a single quantum well structure or a multiple quantum well structure. The quantum well structure is formed by sandwiching a well layer made of a thin film material having a small band cap with a barrier layer made of a material having a large band cap. The multiple quantum well structure is formed in multiple layers by alternately stacking well layers and barrier layers.

The p-type nitride semiconductor layer 5 is a layer in which, for example, Al _{s2 Gat2} In _u2 N (0 ≦ s2 ≦ 1, 0 ≦ t2 ≦ 1, 0 ≦ u2 ≦ 1, s2 + t2 + u2 ≠ 0) is doped with a p-type dopant. More preferably, it is a layer in which an Al _s2 Ga _{1 -s2} N (0 <s2 ≦ 0.4, preferably 0.1 ≦ s2 ≦ 0.3) layer is doped with a p-type dopant. The p-type dopant in the p-type nitride semiconductor layer 5 is not particularly limited, but is preferably, for example, Mg. The thickness of the p-type nitride semiconductor layer 5 is not particularly limited, but is preferably 50 nm or more and 300 nm or less.

  The p-side electrode 6 and the n-side electrode 7 are electrodes for supplying driving power to the nitride-based compound semiconductor light emitting device 1.

The p-side electrode 6 is preferably formed by, for example, a nickel layer, an aluminum layer, a titanium layer, and a gold layer laminated in this order, and may be made of the same material as the n-side electrode 7. Assuming the case where wire bonding is performed on the p-side electrode 6, the thickness of the p-side electrode 6 is preferably 1 μm or more. Further, an insulating layer (for example, made of SiO ₂ , ZrO _2, etc.) is provided under the p-side electrode 6 for current confinement, that is, for preventing current from being injected into the p-side electrode 6. Preferably it is. Thereby, the light emission amount shielded by the p-side electrode 6 is reduced.

  The n-side electrode 7 is preferably configured by, for example, a titanium layer, an aluminum layer, and a gold layer laminated in this order. Assuming the case where wire bonding is performed on the n-side electrode 7, the thickness of the n-side electrode 7 is preferably 1 μm or more.

On the other hand, an optical multilayer reflective layer 8 is provided on the back surface of the substrate 2, that is, on the lower surface of the substrate 2 in FIG. The optical multilayer film reflecting layer 8 is formed by alternately laminating a low refractive index film made of SiO ₂ and a high refractive index film made of TiO ₂ . The optical multilayer film reflecting layer 8 reflects the light emitted from the active layer 4.

  A metal reflective layer 9 is provided on the back surface of the optical multilayer reflective layer 8, that is, on the lower surface of the optical multilayer reflective layer 8 in FIG. The metal reflection layer 9 is made of Al or Ag, and reflects light emitted from the active layer 4 and transmitted through the optical multilayer film reflection layer 8.

  Next, a method for manufacturing the nitride-based compound semiconductor light-emitting element 1 having the above configuration will be described along a flow shown in FIG. 2 in addition to FIG. FIG. 2 is a flowchart showing a method for manufacturing the nitride-based compound semiconductor light-emitting element 1.

  When the manufacture of the nitride-based compound semiconductor light emitting device 1 is started (start of FIG. 2), first, a nitride-based compound semiconductor layer is formed on the surface of the substrate 2 (step # 101 of FIG. 2). The nitride-based compound semiconductor layer is epitaxially grown from the substrate 2 side in the order of the n-type nitride-based compound semiconductor layer 3, the active layer 4, and the p-type nitride-based compound semiconductor layer 5, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method. Grow using the method.

  Subsequently, the mesa portion 20 is formed by etching (step # 102). At this time, the p-type nitride compound semiconductor layer 5, the active layer 4, and a part of the n-type nitride compound semiconductor layer 3 are etched so that a part of the n-type nitride compound semiconductor layer 3 is exposed. .

  Subsequently, the p-side electrode 6 is formed on the upper surface of the p-type nitride-based compound semiconductor layer 5, and the n-side electrode 7 is formed on the upper surface of the n-type nitride-based compound semiconductor layer 3 exposed by the etching in Step # 102. (Step # 103).

  Subsequently, the substrate 2 is ground and polished from the back surface until the thickness of the substrate 2 becomes about 100 μm, thereby reducing the thickness (step # 104). The damaged layer formed on the back surface of the substrate 2 in this polishing process is removed by etching by vapor phase etching such as RIE (Reactive Ion Etching) or ICP (Inductive Coupled Plasma). .

  Then, the substrate 2 is irradiated with a laser from the back side to form the division assisting portion 2a inside the substrate 2 (step # 105). The division assisting portion 2a refers to an altered portion of the substrate 2 that assists so that the division of the substrate 2 described later can be easily realized. Specifically, it is as follows.

  When forming the division assisting portion 2a, the laser is focused by a lens or the like. When the condensed laser is irradiated onto a part of the inside of the substrate 2, the laser irradiation part inside the substrate 2 is melted to become an altered portion. This altered portion is the division assisting portion 2a.

  The division assisting portion 2a may be formed in the central portion of the substrate 2 in the thickness direction (vertical direction in FIG. 1), and on the surface side close to the nitride-based compound semiconductor layer (upper portion of the substrate 2 in FIG. 1). It may be formed or may be formed on the back surface side (lower part of the substrate 2 in FIG. 1). Moreover, although it may be formed in these several parts, if it forms in the back surface side, the division | segmentation of the board | substrate 2 may become easy. The portion of the substrate 2 to be cleaved as viewed from the back side is irradiated with laser, and the division assisting portion 2a may be formed in a straight line shape of the substrate 2, a dotted line shape, or a linear shape. You may form in one part.

  Thereafter, the optical multilayer film reflecting layer 8 is formed on the back surface of the substrate 2 (step # 106). For the formation of the optical multilayer reflective layer 8, a known method such as a sputtering method or an electron vapor deposition method can be used.

  Subsequently, the metal reflection layer 9 is formed on the back surface of the optical multilayer film reflection layer 8 (step # 107). The metal reflective layer 9 can be formed by using a known method such as a sputtering method or an electron vapor deposition method. In addition, you may affix the board | substrate 2 to an adhesive sheet or a support substrate (not shown) at the time of formation of the optical multilayer film reflective layer 8 and the metal reflective layer 9. FIG. However, the adhesive sheet and the support substrate are limited to those that can be removed in a later process.

  A nitride-based compound semiconductor wafer is completed through the above steps.

  Subsequently, the nitride-based compound semiconductor wafer is cleaved and divided along the dividing surface including the dividing assisting portion 2a formed in Step # 105 (Step # 108). Thereby, a plurality of nitride-based compound semiconductor light-emitting elements 1 are obtained, and the flow relating to the manufacture of the nitride-based compound semiconductor light-emitting elements 1 is completed (end of FIG. 2).

  As described above, the method for manufacturing the nitride-based compound semiconductor light-emitting element 1 includes forming the n-type nitride-based compound semiconductor layer 3, the active layer 4, and the p-type nitride-based compound semiconductor layer 5 on the surface of the substrate 2. Polishing the back surface of the substrate 2 to thin the substrate 2, forming the dividing assisting portion 2a inside the substrate 2, and forming the optical multilayer reflective layer 8 on the back surface of the substrate 2 A step of forming the metal reflection layer 9 on the back surface of the optical multilayer film reflection layer 8, and a step of dividing the substrate 2 into a plurality of nitride-based compound semiconductor light-emitting elements 1 at a division plane including the division assisting portion 2a, including. Thereby, since the division | segmentation assistance part 2a is formed in the inside of the board | substrate 2, it is not necessary to pattern with respect to the optical multilayer film reflective layer 8 and the metal reflective layer 9. FIG. The entire back surface of the nitride-based compound semiconductor light-emitting element 1 can be covered with the optical multilayer film reflective layer 8 and the metal reflective layer 9. Therefore, the nitride-based compound semiconductor light emitting device 1 can efficiently reflect the light emitted from the active layer 4 on the back surface thereof.

  Moreover, since the process of forming the division | segmentation assistance part 2a is performed before the process of forming the optical multilayer film reflective layer 8, and the process of forming the metal reflective layer 9, it is not necessary to pattern with respect to a reflective layer. Therefore, the entire back surface of the nitride-based compound semiconductor light-emitting element 1 can be covered with the reflective layer.

  The division assisting portion 2a is formed by laser processing. Thereby, it is possible to easily form the division assisting portion 2 a inside the substrate 2.

  The division assisting portion 2 a is formed by irradiating a laser from the back side of the substrate 2. Thereby, there is no need to form a groove for laser irradiation on the surface side of the substrate 2 on which the nitride-based compound semiconductor layer is formed.

Further, the optical multilayer film reflecting layer 8 is formed by alternately laminating a low refractive index film made of SiO ₂ and a high refractive index film made of TiO ₂ . Thereby, the absorption of light emission depending on the metal material can be reduced as compared with the case of only the metal reflection layer 9, and the light extraction efficiency of the nitride-based compound semiconductor light-emitting element 1 can be improved. .

  The metal reflection layer 9 is made of Ag or Al. Thereby, Ag and Al can reduce the absorption of light emission compared with other metals, and can improve the light extraction efficiency of the nitride-based compound semiconductor light-emitting element.

  Thus, according to the configuration of the above embodiment of the present invention, it is possible to easily cleave and divide the light emitting element whose entire back surface is covered with the reflective layer without patterning the reflective layer. The manufacturing method of the nitride type compound semiconductor light-emitting device 1 can be provided.

  Although the embodiments and examples of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

For example, instead of the low refractive index film (SiO ₂ ) and the high refractive index film (TiO ₂ ) constituting the optical multilayer film reflecting layer 8, a low refractive index dielectric made of Al ₂ O ₂ with a refractive index of 1.63 and A dielectric such as a high refractive index dielectric made of ZrO ₂ having a refractive index of 2.05 can be used. Thereby, it is possible to obtain the same effect as the above-described embodiment.

  The present invention can be used in a method for manufacturing a nitride compound semiconductor light emitting device.

DESCRIPTION OF SYMBOLS 1 Nitride-type compound semiconductor light-emitting device 2 Substrate 2a Division assistance part 3 N type nitride type compound semiconductor layer 4 Active layer 5 P type nitride type compound semiconductor layer 6 P side electrode 7 N side electrode 8 Optical multilayer film reflection layer 9 Metal reflective layer

Claims (6)

A method of manufacturing a nitride-based compound semiconductor light-emitting device in which a plurality of nitride-based compound semiconductor layers are stacked on a surface of a substrate, and a p-side electrode and an n-side electrode are provided on the surface side,
Forming at least an n-type nitride compound semiconductor layer, an active layer and a p-type nitride compound semiconductor layer on the surface of the substrate;
Polishing the back surface of the substrate to thin the substrate;
Forming a division assisting portion for assisting in the division of the substrate inside the substrate;
Forming an optical multilayer film reflecting layer that reflects light emitted from the active layer on the back surface of the substrate;
Forming a metal reflective layer that reflects light transmitted through the optical multilayer reflective layer on the back surface of the optical multilayer reflective layer;
Dividing the substrate into a plurality of elements at a dividing surface including the dividing assisting portion;
A method for producing a nitride-based compound semiconductor light-emitting device comprising:   2. The nitride-based compound semiconductor according to claim 1, wherein the step of forming the division assisting portion is performed before the step of forming the optical multilayer reflective layer and the step of forming the metal reflective layer. Manufacturing method of light emitting element.   The method for manufacturing a nitride-based compound semiconductor light-emitting element according to claim 1, wherein the division assisting portion is formed by laser processing.   The method of manufacturing a nitride-based compound semiconductor light-emitting element according to claim 3, wherein the division assisting portion is formed by irradiating a laser from the back side of the substrate. 3. The optical multilayer film reflective layer is formed by alternately laminating a low refractive index film made of SiO ₂ and a high refractive index film made of TiO ₂ . A method for manufacturing a nitride-based compound semiconductor light-emitting device.   The method for manufacturing a nitride-based compound semiconductor light-emitting element according to claim 1, wherein the metal reflective layer is made of Ag or Al.

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