JP2010056457A - Method of manufacturing light emitting element array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a light emitting element array in which a fabricating process is shortened. <P>SOLUTION: The method of manufacturing the light emitting element array includes the processes of: (1) forming a group III nitride semiconductor layer, including an optical semiconductor layer 2 comprising a semiconductor layer 2b of a first conductivity type, a light emitting layer 2c, and a semiconductor layer 2d of a second conductivity type, on a substrate 1 for growth; (2) exposing the group III nitride semiconductor layer differing in type from one principal surface of the group III nitride semiconductor layer by removing a portion of the one principal surface, and forming electrodes on the semiconductor layers of the first conductivity type and second conductivity type respectively; and (3) removing the substrate for growth after bonding the electrodes formed on one-side principal surfaces of the semiconductor layers to electrodes formed on a principal surface of a support substrate at positions opposed to the electrodes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a light-emitting element array including a plurality of light-emitting elements.

  In recent years, light emitting elements composed of optical semiconductors have been developed and used for lighting devices and the like. Examples of such a light emitting element include a group III-V group compound semiconductor such as a blue light emitting element and an ultraviolet light emitting element.

Along with the development of light-emitting elements, various methods for manufacturing light-emitting elements have been developed. For example, after a light-emitting element is grown on a growth substrate, the light-emitting element is peeled off from the growth substrate to produce a light-emitting element. A manufacturing method is disclosed (see Patent Document 1).
JP 2007-19511 A

  When a light emitting element is used in a lighting device or the like, it needs to be arrayed in order to obtain high luminance, and in recent years, simplification of the arraying process of the light emitting element is required.

  Note that the technique described in Patent Document 1 is not an array of light emitting elements. For this reason, in order to form an array, it is necessary to separately arrange the produced light-emitting elements one by one on the circuit board. Therefore, the production process has not been sufficiently shortened.

  The objective of this invention is providing the manufacturing method of the light emitting element array which performs arraying of a light emitting element by a simple process.

  The present invention includes (1) a step of forming a plurality of optical semiconductor layers composed of a first conductivity type semiconductor layer, a light emitting layer, and a second conductivity type semiconductor layer on a growth substrate; 2) A part of each of the plurality of optical semiconductor layers is removed to expose the first conductive type semiconductor layer and the second conductive type semiconductor layer, thereby forming first and second electrodes, respectively. And (3) bonding the first and second electrodes formed on the plurality of optical semiconductor layers to electrodes on a support substrate provided at positions opposed to these electrodes, The present invention relates to a method for manufacturing a light emitting element array, comprising: mounting a growth substrate on the support substrate; and (4) removing the growth substrate.

  In the step (1), (1-1) a growth suppressing mask pattern is formed on the growth substrate by a material made of a material that is inactive with respect to the epitaxial growth of the optical semiconductor layer and separated from each other. Forming a plurality of exposed portions on the growth substrate; (1-2) forming the optical semiconductor layer by epitaxial growth on the plurality of exposed portions on the growth substrate; And removing the growth suppression mask pattern.

  When the growth substrate and the optical semiconductor layer are made of different materials, it is preferable that the growth substrate is removed by laser lift-off in the step (4).

  The method for manufacturing a light-emitting element array according to the present invention includes (1) a step of forming a plurality of optical semiconductor layers on a growth substrate, and (2) first and second electrodes in each of the plurality of optical semiconductor layers. And (3) bonding the first and second electrodes formed on a plurality of optical semiconductor layers to electrodes on a support substrate provided at positions facing these electrodes, respectively. And (4) removing the growth substrate, and mounting the growth substrate on the support substrate. Thereby, a plurality of light emitting elements can be arrayed at a time without arranging the light emitting elements one by one on the support substrate. In this manufacturing method, since a plurality of optical semiconductor layers are used for one growth substrate and one support substrate, the difference in thermal expansion coefficient between the growth substrate and the support substrate is large. However, the contact area between the optical semiconductor layer, the growth substrate and the support substrate can be reduced, and the strain generated due to the difference in coefficient of thermal expansion can be reduced. Therefore, a growth substrate and a support substrate having different thermal expansion coefficients can be used.

  In the method for manufacturing a light-emitting element array according to the present invention, the step (1) includes (1-1) a growth suppression mask pattern formed on the growth substrate by a substance made of a material inactive with respect to the epitaxial growth of the optical semiconductor layer. Forming a plurality of exposed portions on the growth substrate separated from each other; and (1-2) forming the optical semiconductor layer on the plurality of exposed portions on the growth substrate by epitaxial growth. And (1-3) a step of removing the growth suppression mask pattern. Thereby, a some optical semiconductor layer can be formed collectively. Furthermore, the growth suppression mask pattern can be finely processed by a photolithography process, and a plurality of optical semiconductor layers patterned by the growth suppression mask pattern can be transferred onto the support substrate in the same arrangement, so that the element spacing can be precisely controlled. These optical semiconductor layers can be formed together.

  In the method for manufacturing a light emitting element array according to the present invention, preferably, when the growth substrate and the optical semiconductor layer are made of different materials, in the step (4), the growth substrate is preferably removed by laser lift-off. As a result, only the optical semiconductor layer bonded on the support substrate can be selectively removed from the growth substrate easily.

  Hereinafter, the manufacturing method of the light emitting element array of this invention is demonstrated in detail, referring drawings.

  FIG. 1 is a cross-sectional view showing a first embodiment of a light emitting element array of the present invention. In FIG. 1, 1 is a growth substrate, 2 is a semiconductor layer, 2a is a buffer layer, 2b is a first conductivity type (n-type) semiconductor layer, 2c is a light emitting layer, and 2d is a second conductivity type (p-type). Semiconductor layer, 3 is a conductive layer on the second conductive side, 4 is a pad electrode (second electrode) on the second conductive side (p side), 5 is a conductive layer on the first conductive side (n side), and 6 is a first conductive layer The pad electrode (first electrode) on the first conductive side (n side), 7 the pattern electrode on the second conductive side (p side), 8 the pattern electrode on the first conductive side (n side), and 9 the support substrate Each is shown.

  The method for manufacturing a light-emitting element array according to the present invention includes (1) a step of forming a plurality of optical semiconductor layers 2 on a growth substrate 1, (2) a step of forming electrodes on the plurality of optical semiconductor layers 2, and (3 And a step of removing the growth substrate after bonding the electrode formed on one main surface of the optical semiconductor layer 2 to the electrode on the main surface of the support substrate.

  Each process will be described below.

(Process 1)
In step 1, a plurality of optical semiconductor layers 2 are formed on a growth substrate 1 as shown in FIG.

The growth substrate 1 may be any substrate on which the optical semiconductor layer 2 can be grown. Specifically, examples of the substrate 1 include sapphire (Al ₂ O ₃ ), gallium nitride (GaN), aluminum nitride (AlN), zinc oxide (ZnO), and silicon carbide (SiC). The thickness of the growth substrate 1 is about 100 μm to 1000 μm.

  Examples of the optical semiconductor layer 2 include III-V group compound semiconductors such as gallium nitride (GaN), aluminum nitride (AlN), aluminum gallium nitride (AlGaN), and indium nitride (InN), and II-VI group compounds such as ZnO. A semiconductor etc. are mentioned. Here, Group III means Group III (Group 13) in the Periodic Table of Elements.

  In the case of FIG. 1A, the optical semiconductor layer 2 includes a buffer layer 2a, a first conductivity type semiconductor layer 2b, a light emitting layer 2c, and a second conductivity type semiconductor layer 2d.

  The buffer layer 2 a is preferably formed in order to relieve stress between the growth substrate 1 and the optical semiconductor layer 2. The nitride buffer layer 2a is made of a material such as gallium nitride or aluminum nitride, for example. The thickness of the nitride buffer layer 2a is about 0.01 to 0.2 μm.

  Examples of the first conductivity type semiconductor layer 2b include an n-type semiconductor layer. For example, to make the group III nitride semiconductor layer n-type, Si or the like, which is a group IV element in the periodic table, may be mixed into the nitride semiconductor layer as a dopant. The thickness of the first conductivity type semiconductor layer 2b is about 2 to 3 μm.

  Examples of the second conductivity type semiconductor layer 2d include a p-type nitride semiconductor. For example, in order to make the group III nitride semiconductor layer p-type, Mg or the like, which is a group II element in the periodic table, may be mixed into the nitride semiconductor layer as a dopant. The thickness of the second conductivity type semiconductor layer 2d is about 200 to 500 nm.

The light emitting layer 2c is provided between the first conductive type semiconductor layer 2b and the second conductive type semiconductor layer 2d. The light emitting layer 2c has a multilayer quantum well structure (MQW) in which a quantum well structure composed of a barrier layer having a wide forbidden band and a well layer having a narrow forbidden band is regularly stacked a plurality of times (for example, about 3 times). Also good. Note that examples of the barrier layer include an In _0.01 Ga _0.99 N layer. Examples of the well layer include an In _0.11 Ga _0.89 N layer. The thickness of the barrier layer is about 5 to 15 nm, and the thickness of the well layer is about 2 to 10 nm. The thickness of the light emitting layer 2c is about 25 to 150 nm.

  As a growth method of the optical semiconductor layer 2 on the growth substrate 1, a molecular beam epitaxy (MBE) method, a metal organic epitaxy (MOVPE), a hydride vapor phase epitaxy (HVPE; Vapor Phase Epitaxy), pulsed laser deposition (PLD) method, or the like is used.

  In step 1, a plurality of optical semiconductors 2 are formed by dividing the optical semiconductor layer 2 grown on one surface of the growth substrate, or a substance made of a material that is inactive with respect to the epitaxial growth of a group III nitride semiconductor. And a method of dividing the region of the growth substrate 1 first and then growing the optical semiconductor layer 2. Examples of the method for dividing the grown optical semiconductor layer 2 include a dicing method and a method of performing dry etching after forming an etching mask in a region other than the region to be divided.

  A specific example of a method of first dividing the region of the growth substrate 1 on which the optical semiconductor layer 2 is grown and then growing the optical semiconductor layer 2 is shown in FIG.

  First, a growth suppression mask pattern is formed on the growth substrate 1 (FIG. 2A). At this time, after the template layer 2e is grown on the buffer layer 2a, the buffer layer 2a and the template layer 2e are removed by etching or the like only in the region where the mask is to be formed. Here, the template layer 2 e is used for selectively growing the semiconductor layer 2 b so as not to grow on the growth suppression mask 10. The template layer 2e is made of the same material as the first conductivity type semiconductor layer 2b and has a thickness of about 1 to 5 μm.

The growth suppression mask 10 is formed of a material made of a material that is inactive with respect to the epitaxial growth of a group III nitride semiconductor. Here, specific examples of the material used for the growth suppression mask 10 include SiO ₂ and polycrystalline silicon. These are inert to the epitaxial growth of group III nitride semiconductors.

  Specifically, the growth suppression mask 10 is formed by depositing a mask material on one surface by vapor deposition, CVD, or the like, and then performing photolithography and etching.

  After forming the growth suppression mask 10, the first conductivity type semiconductor layer 2b, the light emitting layer 2c, and the second conductivity type semiconductor layer 2d separated by the growth suppression mask 10 on the template layer 2e, It is formed by epitaxial growth (see FIG. 2B).

Then, after forming them, the growth suppression mask 10 is removed (FIG. 2C). Specifically, if the mask material is SiO ₂ in the case of hydrofluoric acid, polycrystalline silicon removing the growth suppression mask 10 by the wet etching using a mixed acid with nitric acid and hydrofluoric acid.

(Process 2)
In step 2, as shown in FIG. 1B, a part of one main surface of the group III nitride semiconductor layer 2 is removed to expose the group III nitride semiconductor layer 2 having a different type from the main surface. Electrodes are formed on the semiconductor layer 2 of the first conductivity type and the second conductivity type, respectively.

  Step 2 removes a part of each of the plurality of optical semiconductor layers 2 to expose the first conductive type semiconductor layer 2b and the second conductive type semiconductor layer 2d, and the first conductive side (n side) respectively. The pad electrode (first electrode) 6 and the second conductive side (p side) pad electrode (second electrode) 4 are formed.

In order to remove a part of one main surface of the optical semiconductor layer 2 and expose the first conductivity type semiconductor layer 2b of the optical semiconductor layer 2, specifically, an RIE apparatus or the like is used to form Cl ₂ gas and BCl ₃ . Dry etching is performed for a predetermined time using a mixed gas. Thus, the first conductivity type semiconductor layer 2b having a different type from the second conductivity type semiconductor layer 2d can be exposed.

  In the case of FIG. 2C, the first conductive side conductive layer 5 is formed on the first conductive type semiconductor layer 2b, and the first conductive side conductive layer 5 is formed on the first conductive side conductive layer 5 as the first electrode. A pad electrode 6 was formed. Similarly, the second conductive side conductive layer 3 is formed on the second conductive type semiconductor layer 2d, and the second conductive side pad electrode 4 is formed on the second conductive side conductive layer 3 as the second electrode. Formed.

  The conductive layer 5 on the first conductive side and the conductive layer 3 on the second conductive side are formed by a method such as vacuum deposition or sputtering.

The material of the conductive layer 5 on the first conductive side and the conductive layer 3 on the second conductive side reflects the light generated from the light emitting layer 2c without loss, and the first conductive type semiconductor layer 2b and the second conductive type semiconductor. It is preferably provided in order to make a good ohmic connection with the layer 2d. For example, aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), indium (In), tin (Sn), molybdenum (Mo), silver (Ag), gold (Au), niobium (Nb) ), Tantalum (Ta), vanadium (V), platinum (Pt), lead (Pb), beryllium (Be), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), A thin film such as a gold-silicon (Au-Si) alloy, a gold-germanium (Au-Ge) alloy, a gold-zinc (Au-Zn) alloy, or a gold-beryllium (Au-Be) alloy can be preferably used.

  The pad electrode 6 on the first conductive side and the pad electrode 4 on the second conductive side are respectively joined to the first electrode 6 and the second electrode 4 of the support substrate 9 in an after process, and are electrically connected to them. Is provided. The first conductive side pad electrode 6 and the second conductive side pad electrode 4 are made of, for example, titanium or titanium so that the first conductive side pattern electrode 8 and the second conductive side pattern electrode 7 can be joined. A layer in which a gold layer is laminated is used as the ground layer.

The pad electrode 6 on the first conductive side and the pad electrode 4 on the second conductive side are formed by a method such as vacuum deposition or sputtering (step 3).
In step 3, the first conductive side pad electrode 6 and the second conductive side pad electrode 4 formed on the plurality of optical semiconductor layers 2 are placed on a support substrate 9 provided at a position facing these electrodes. In this step, the growth substrate 1 is mounted on the support substrate 9 by bonding to the electrodes 7 and 8 (p-side pattern electrode 7 and n-side pattern electrode 8), respectively (see FIG. 1C).

  After the step 3, the pattern electrode 8 on the first conductive side and the pattern electrode 7 on the second conductive side and the pattern electrode 7 on the second conductive side are formed on the support substrate 9 so that it can function as a light emitting element array only by the step of removing the growth substrate 1. A wiring pattern is provided in advance.

  The pattern electrode 8 on the first conductive side and the pattern electrode 7 on the second conductive side can be bonded to the pad electrode 6 on the first conductive side and the pad electrode 4 on the second conductive side and are electrically connected. Things are used. Specifically, materials such as An—Sn alloy and Pb—Sn alloy are used.

  The pattern electrode 8 on the first conductive side and the pattern electrode 7 on the second conductive side are produced by a method such as plating, sputtering, or vacuum deposition. Moreover, the thickness of those layers is about 1-100 micrometers.

  The circuit pattern is produced by a method of forming a resist pattern on a metal film such as a copper foil formed on one surface by a photolithography process, performing etching, and removing the resist pattern.

The support substrate 9 is made of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or the like. The thickness of the support substrate 9 is about 0.5 to 3 mm. If the thickness is within this range, the support substrate 9 has sufficient strength against heat generated by the light emitting element and stress during handling, and has high heat dissipation characteristics.

  In step 3, the first conductive side pad electrode 6 and the second conductive side pad electrode 4 are joined to the first conductive side pattern electrode 8 and the second conductive side pattern electrode 7, respectively. Specifically, the bonding is performed by heating the support substrate 9, the growth substrate 1 and the like to 150 to 400 ° C.

  By the step 3, the plurality of light emitting elements 2 can be mounted on the support substrate 9 at the same time, and further, the alignment is not necessary, so that the step can be greatly simplified.

  In step 3, a plurality of optical semiconductor layers are used for one growth substrate and one support substrate. Therefore, even when the difference in thermal expansion coefficient between the growth substrate and the support substrate is large, the contact area between the optical semiconductor layer, the growth substrate and the support substrate is reduced, and distortion caused by the difference in thermal expansion coefficient is reduced. It can be reduced by dispersion. Therefore, a growth substrate and a support substrate having different thermal expansion coefficients can be used.

(Process 4)
In step 4, the growth substrate 1 is removed. Examples of the removal method include laser lift-off (when the growth substrate 1 and the optical semiconductor layer 2 are made of different materials), polishing of the substrate, and the like. Among these, the growth substrate 1 can be easily removed by laser irradiation, and therefore, laser lift-off is preferable as the removal method. In Step 3, when heated, laser lift-off may be performed in the cycle. In this case, since the support substrate 9 is cooled in a state where the growth substrate 1 is removed first, accumulation of thermal stress can be prevented.

  The light emitting element array 11 can be manufactured by performing the above processes 1-4.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

It is sectional drawing which shows one embodiment of the manufacturing method of the light emitting element array of this invention. It is sectional drawing which shows one of the process 1 of the manufacturing method of the light emitting element array of this invention.

Explanation of symbols

1: growth substrate 2: optical semiconductor layer 2a: buffer layer 2b: first conductivity type (n-type) semiconductor layer 2c: light emitting layer 2d: second conductivity type (p-type) semiconductor layer 2e: template layer 3: Second conductive side conductive layer 4: Second conductive side pad electrode 5: First conductive side conductive layer 6: First conductive side pad electrode 7: First conductive side pattern electrode 8: Second conductive side pattern electrode 9: Support substrate 10: Growth suppression mask 11: Light emitting element array

Claims (3)

(1) forming a plurality of optical semiconductor layers composed of a first conductivity type semiconductor layer, a light emitting layer, and a second conductivity type semiconductor layer on a growth substrate;
(2) A part of each of the plurality of optical semiconductor layers is removed to expose the first conductive type semiconductor layer and the second conductive type semiconductor layer, thereby forming first and second electrodes, respectively. And a process of
(3) The growth substrate is formed by bonding the first and second electrodes formed on a plurality of the optical semiconductor layers to electrodes on a support substrate provided at positions facing the electrodes. Mounting on the support substrate;
(4) removing the growth substrate;
A method for manufacturing a light-emitting element array comprising: The step (1)
(1-1) A growth suppression mask pattern is formed on the growth substrate with a material made of a material inactive with respect to the epitaxial growth of the optical semiconductor layer, and exposed on the growth substrate separated from each other. Forming a plurality of parts,
(1-2) forming the optical semiconductor layer by epitaxial growth on a plurality of exposed portions on the growth substrate;
(1-3) removing the growth suppression mask pattern;
The manufacturing method of the light emitting element array of Claim 1 containing this.   3. The method for manufacturing a light-emitting element array according to claim 1, wherein when the growth substrate and the optical semiconductor layer are made of different materials, the growth substrate is removed by laser lift-off in the step (4).

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