Light-emitting element inspection method

Abstract

Disclosed is an inspection method comprising: forming a buffer layer on an amorphous substrate; forming an n-type clad layer, a luminescent layer, and a p-type clad layer each including an inorganic semiconductor, on the buffer layer to thereby form a plurality of semiconductor layers disposed in a matrix arrangement having a plurality of lines and a plurality of rows; forming an anode and a cathode on each of the plurality of semiconductor layers, thereby forming a plurality of luminescent elements; and using a first detector and a second detector to acquire the photoluminescent properties and / or the electroluminescent properties of the plurality of luminescent elements. The buffer layer has the function of accelerating the crystallization of the semiconductor layers. The photoluminescent properties and the electroluminescent properties are each acquired before and after the formation of the anodes and cathodes.

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a method for inspecting a light-emitting element, for example, a method for inspecting a plurality of inorganic light-emitting diodes provided on a large amorphous substrate. [Background technology]

[0002] In recent years, inorganic light-emitting diodes (LEDs) have been widely used as light-emitting elements, and LEDs are used not only in lighting devices but also in display devices. In the field of display devices, LEDs have traditionally been used as backlights for liquid crystal display devices, but recently, development of display devices in which LEDs are arranged within pixels arranged in a matrix has also been progressing. LEDs can be fabricated by forming a semiconductor layer by stacking multiple layers containing inorganic compounds such as Group 12, 13, and 15 elements, such as gallium, indium, arsenic, zinc, and selenium, on a wide-gap semiconductor substrate or an amorphous glass substrate, and then forming a pair of electrodes on top of that (see Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 121628 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-10834 [Patent Document 3] International Publication No. 2018 / 042792 [Patent Document 4] Patent No. 6723484 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide a new inspection method for inspecting a plurality of light-emitting elements provided on a substrate, or to provide an inspection method for quickly and efficiently inspecting a plurality of light-emitting elements provided on an amorphous substrate and having a semiconductor layer containing an inorganic compound. [Means for solving the problem]

[0005] One embodiment of the present invention is a method for inspecting light-emitting devices. The method includes forming a buffer layer on an amorphous substrate; forming a plurality of semiconductor layers arranged in a matrix having a plurality of rows and a plurality of columns by forming an n-type cladding layer, a light-emitting layer, and a p-type cladding layer, each containing an inorganic semiconductor, on the buffer layer; forming a plurality of light-emitting devices by forming an anode and a cathode on each of the plurality of semiconductor layers; and acquiring at least one of the photoluminescence characteristics and the electroluminescence characteristics of the plurality of light-emitting devices using a first detector and a second detector. The buffer layer has a function of promoting crystallization of the semiconductor layer. The photoluminescence characteristics are acquired before the formation of the anode and the cathode. The electroluminescence characteristics are acquired after the formation of the anode and the cathode. [Brief explanation of the drawings]

[0006] [Figure 1] 3 is a flowchart illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 2] 3 is a flowchart illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 3] 3 is a flowchart illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 4A] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 4B] 5A to 5C are schematic end views illustrating a method for inspecting a light emitting element according to an embodiment of the present invention. [Figure 5A]5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 5B] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 6A] 5A to 5C are schematic side views illustrating a method for inspecting a light emitting element according to an embodiment of the present invention. [Figure 6B] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 7A] 5A to 5C are schematic side views illustrating a method for inspecting a light emitting element according to an embodiment of the present invention. [Figure 7B] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 8A] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 8B] FIG. 2 is a schematic top view of a test substrate used in the method for testing a light-emitting element according to the embodiment of the present invention. [Figure 9A] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 9B] 5A to 5C are schematic end views illustrating a method for inspecting a light emitting element according to an embodiment of the present invention. [Figure 10A] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 10B] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 11A] 5A to 5C are schematic top views illustrating a method for inspecting a light-emitting element according to an embodiment of the present invention. [Figure 11B] 5A to 5C are schematic end views illustrating a method for inspecting a light emitting element according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0008] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described in the previous drawings may be given the same reference numerals, and duplicated explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and when these are individually represented, a hyphen and a natural number are added after the reference numeral. In addition, when representing a part of a single structure, a lowercase alphabet may be added after the reference numeral.

[0009] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case where another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case where another structure is placed above a certain structure via yet another structure.

[0010] In this specification and claims, the expression "a structure exposed from another structure" means a state in which a part of a structure is not covered by another structure, and includes a state in which the part not covered by another structure is covered by yet another structure. The state expressed by this expression also includes a state in which a structure is not in contact with another structure.

[0011] The following describes an embodiment of the present invention, which relates to a method for inspecting multiple light-emitting elements (hereinafter sometimes simply referred to as the present inspection method), and a method for manufacturing a light-emitting device that includes the present inspection method. The light-emitting elements that are the subject of the present inspection method are LEDs that have a semiconductor layer that is a laminate of multiple layers, each containing an inorganic semiconductor, and a pair of electrodes (anode and cathode) electrically connected to the semiconductor layer. In the present inspection method, multiple semiconductor layers or multiple light-emitting elements are formed on an amorphous substrate, and one or both of photoluminescence (PL) and electroluminescence (EL) from the semiconductor layer are utilized.

[0012] 1. Overview In an inspection method using photoluminescence, multiple semiconductor layers are formed on an amorphous substrate, as shown in the flowchart of FIG. 1. The multiple semiconductor layers are then irradiated with light, and the light-emitting characteristics, i.e., photoluminescence characteristics, obtained from the semiconductor layers are acquired. The photoluminescence characteristics can be acquired, for example, based on a photoluminescence spectrum. The characteristics of the obtained spectrum (e.g., spectral intensity, peak wavelength, shape, etc.) are evaluated, and if these characteristics are within specifications, the semiconductor layer is determined to be a non-defective product. If they are out of specifications, the semiconductor layer is determined to be a defective product. The photoluminescence characteristics do not necessarily have to be acquired from the photoluminescence spectrum; they may also be acquired, for example, from the intensity (brightness), chromaticity, or shape or area of ​​the light-emitting region of the light-emitting light obtained from the semiconductor layer.

[0013] In an inspection method using electroluminescence, as shown in the flowchart of Figure 2, multiple semiconductor layers are formed on an amorphous substrate, and then anodes and cathodes are formed on each of the multiple semiconductor layers to form multiple light-emitting elements. Power is then supplied to the multiple light-emitting elements, and the light-emitting characteristics obtained from the semiconductor layers, i.e., electroluminescence characteristics, are obtained. Similar to photoluminescence characteristics, electroluminescence characteristics can be obtained based on electroluminescence spectra. The characteristics of the obtained spectra are evaluated, and if they are within specifications, the light-emitting element is determined to be a good product; if they are out of specifications, the light-emitting element is determined to be defective. Alternatively, the intensity (brightness), chromaticity, or shape or area of ​​the light-emitting region of the electroluminescence obtained from the semiconductor layers may be used as the electroluminescence characteristics.

[0014] In an inspection method using both photoluminescence and electroluminescence, as shown in the flowchart of Figure 3, multiple semiconductor layers are formed on an amorphous substrate. Then, the photoluminescence characteristics are evaluated as described above. If the photoluminescence characteristics are out of specification, the semiconductor layer is determined to be defective. On the other hand, semiconductor layers whose photoluminescence characteristics are within specification are further subjected to an inspection using electroluminescence. That is, after forming anodes and cathodes on each of the multiple semiconductor layers to form multiple light-emitting elements, power is supplied to the multiple light-emitting elements as described above, and the electroluminescence characteristics obtained from the semiconductor layers are evaluated. If the electroluminescence characteristics are within specification, the light-emitting element is determined to be a good product; if they are out of specification, the light-emitting element is determined to be defective. Therefore, in an inspection method using both photoluminescence and electroluminescence, a light-emitting element is determined to be a good product only if both the photoluminescence characteristics and the electroluminescence characteristics are within specification. Conversely, if at least one of the photoluminescence characteristics and the electroluminescence characteristics is out of specification, the light-emitting element is determined to be defective. The details of this inspection method will be explained below.

[0015] 2. Light-emitting element (1) Circuit board As shown in the schematic top view of FIG. 4A, the light emitting element 110, which is the subject of this inspection method, is provided on an amorphous substrate 100. The substrate 100 is, for example, a glass substrate. The substrate 100 may have a thickness that allows it to be flexible. Preferably, the substrate 100 has a low thermal expansion coefficient, a high strain point, and a high surface flatness. For example, the substrate 100 has a thermal expansion coefficient of 50×10 -7 / °C and a strain point of 600°C or higher. Furthermore, the content of alkali metals such as sodium in the substrate 100 is preferably 0.1% or less. Therefore, when the substrate 100 is a glass substrate, a glass substrate made of, for example, aluminoborosilicate glass or aluminosilicate glass can be used. When the electroluminescence characteristics are obtained through the substrate 100 in an inspection method that utilizes electroluminescence, the substrate 100 is preferably configured to transmit visible light.

[0016] There are no restrictions on the shape of the substrate 100, but a quadrilateral shape such as a square or rectangle is preferable. There are also no restrictions on the size of the substrate 100, and the substrate 100 may be, for example, 600 mm x 720 mm, which is called 3.5 generation glass, 730 mm x 920 mm, which is called 4.5 generation glass, 1500 mm x 1850 mm, which is called 6 generation glass, or even larger sizes. Using a large substrate 100 enables testing of a large number of light-emitting elements, allowing for efficient testing at low cost.

[0017] (2) Structure of the light-emitting element The light-emitting elements 110 are arranged in a matrix having multiple rows and multiple columns (see FIG. 4A). A schematic diagram of an end surface along the chain line AA′ intersecting three consecutive light-emitting elements 110 is shown in FIG. 4B. As shown in FIG. 4B, a buffer layer 104 is provided on the substrate 100. The buffer layer 104 is provided either via the barrier layer 102 or in direct contact with the substrate 100. On the buffer layer 104, an n-type cladding layer 112, a light-emitting layer 114 on the n-type cladding layer 112, a p-type cladding layer 116 on the light-emitting layer 114, and an anode 118 and a cathode 120 electrically connected to the p-type cladding layer 116 and the n-type cladding layer 112, respectively, are provided. The stack of the n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 constitutes a semiconductor layer, and the light-emitting element 110 is composed of this semiconductor layer, the anode 118, and the cathode 120. The buffer layer 104 and the n-type cladding layer 112 can be formed so as to be continuous between adjacent light-emitting elements 110. In other words, the buffer layer 104 and the n-type cladding layer 112 can be provided on the substrate 100 so as to be shared by a plurality of light-emitting elements 110.

[0018] A. Barrier layer The barrier layer 102 is a film that prevents impurities such as sodium ions contained in the substrate 100 from diffusing toward the light emitting element 110. The barrier layer 102 is a laminate of one or more films containing a silicon-containing inorganic compound such as silicon oxide or silicon nitride, and may be formed by sputtering or chemical vapor deposition (CVD).

[0019] B. Buffer layer The buffer layer 104 is a film that promotes crystallization of the semiconductor layer stacked thereon and can include an insulating or conductive material having a hexagonal close-packed structure, a face-centered cubic structure, or a structure equivalent thereto. Here, a hexagonal close-packed structure or a structure equivalent thereto includes a crystal structure in which the c-axis is not perpendicular to the a-axis and the b-axis. Therefore, in this structure, the buffer layer 104 is oriented in the (0001) direction, i.e., the c-axis direction, relative to the substrate 100. Furthermore, a buffer layer 104 having a face-centered cubic structure or a structure equivalent thereto is oriented in the (111) direction relative to the substrate 100. Therefore, the c-axis of the buffer layer 104 is oriented perpendicular or approximately perpendicular to the surface on which the buffer layer 104 is provided. As will be described later, the semiconductor layer includes inorganic semiconductors such as gallium nitride-based materials. It is known that such inorganic semiconductors have a hexagonal close-packed structure and undergo crystal growth in the c-axis direction to minimize their surface energy. Therefore, by forming a semiconductor layer on the buffer layer 104, crystal growth in the c-axis direction of the semiconductor layer is promoted, resulting in improved crystallinity of the semiconductor layer.

[0020] Such a buffer layer 104 may include metal nitrides such as aluminum nitride, aluminum oxide, and titanium nitride, metal oxides such as zinc oxide, lithium niobate (LiNbO), BiLaTiO, SrFeO, BiFeO, BaFeO, ZnFeO, and PMnN-PZT, or basic calcium phosphate (biological apatite). By using such materials, an insulating buffer layer 104 can be formed. Alternatively, the buffer layer 104 may include metals such as titanium, aluminum, silver, nickel, copper, strontium, rhodium, palladium, iridium, platinum, and gold.

[0021] C. Semiconductor layer The n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 constituting the semiconductor layer are configured to emit visible light by recombination of holes and electrons injected from the anode 118 and the cathode 120, respectively. The n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 may each have a single-layer structure or a laminated structure in which multiple layers are stacked. In the example shown in FIG. 4B , the n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 are stacked in this order from the substrate 100 side, but the semiconductor layers may also be configured in the reverse order. In this case, the p-type cladding layer 116 can be formed so as to be shared by multiple light-emitting elements 110.

[0022] The n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 each contain an inorganic semiconductor. Examples of inorganic semiconductors include compounds containing Group 13 and Group 15 elements. More specifically, examples include semiconductors containing aluminum, gallium, and / or indium, as well as nitrogen, phosphorus, and / or arsenic, and typical examples include gallium-based materials. Examples of gallium-based materials include gallium nitride-based materials such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), and indium gallium nitride (InGaN), and gallium phosphide-based materials such as gallium phosphide (GaP) and aluminum indium gallium phosphide (AlGaInP). The n-type cladding layer 112 and the p-type cladding layer 116 may further contain a dopant. Examples of dopants include elements such as silicon, germanium, magnesium, zinc, cadmium, and beryllium. Adding these elements makes it possible to control the valence electrons of each layer, and not only maintain the intrinsic (i-type) conductivity but also control the band gap and impart p-type or n-type conductivity. The p-type cladding layer 116 is imparted with p-type conductivity, and the n-type cladding layer 112 is imparted with n-type conductivity. For example, the p-type cladding layer 116 may be made of p-type aluminum gallium nitride and / or p-type gallium nitride, and the n-type cladding layer 112 may be made of n-type gallium nitride and / or n-type aluminum gallium nitride.

[0023] The light-emitting layer 114 may have, for example, a single layer structure of indium gallium nitride, or a quantum well structure. A quantum well structure is a structure in which multiple thin films with different bandgaps and thicknesses of about 1 to 5 nm are alternately stacked, and examples of such structures include an alternating stack of indium gallium nitride and gallium nitride, an alternating stack of indium gallium arsenide phosphide (GaInAsP) and indium phosphide (InP), and an alternating stack of aluminum indium arsenide (AlInAs) and indium gallium arsenide (InGaAs).

[0024] D. Anode and cathode The anode 118 and the cathode 120 inject holes and electrons into the p-type cladding layer 116 and the n-type cladding layer 112, respectively. The anode 118 can be made of a metal such as palladium or gold, or a thin film of an alloy thereof. The cathode can be made of a metal such as silver or indium, or an alloy thereof. The light-emitting device 110 can be configured so that light emitted from the light-emitting layer 114 is extracted from the anode 118 side, or conversely, so that light is extracted from the substrate 100 side. In the former case, the anode 118 is provided so as not to cover the entire p-type cladding layer 116. In other words, at least a portion of the p-type cladding layer 116 that contacts the anode 118 is exposed from the anode 118.

[0025] 3. Light-emitting element inspection method (1) Formation of alignment marks As will be described later, this inspection method uses one or more detectors, and inspection is performed while the substrate 100 and the detectors are moved relative to one another. For this reason, alignment marks 106 for aligning the detectors are formed on the substrate 100. For example, as shown in FIG. 5A, multiple alignment marks 106 are formed outside an area (element manufacturing area) that surrounds all of the areas 100a in which the light-emitting elements 110 are formed. As shown in FIG. 5B, alignment marks 106 may also be formed within the element manufacturing area. In this case, alignment marks 106 are formed between adjacent areas 100a in the row direction, column direction, or diagonal directions relative to the row and column directions.

[0026] As will be described later, in this inspection method, multiple light-emitting elements 110 or multiple semiconductor layers are divided into multiple element groups, each including multiple light-emitting elements 110 or multiple semiconductor layers, and each element group is inspected using a detector. Therefore, the alignment marks 106 are arranged so that at least two alignment marks 106 are present within the field of view of each detector (i.e., the measurement range of each detector). Specifically, the multiple light-emitting elements 110 or multiple semiconductor elements are divided into multiple element groups so that each element group includes multiple light-emitting elements 110 or semiconductor layers arranged in a matrix of n rows and m columns. Therefore, the alignment marks 106 are arranged so that at least two alignment marks 106 are present in an area including the light-emitting elements 110 or semiconductor layers arranged in a matrix of n consecutive rows and m consecutive columns. Here, m and n are integers, and may be independently selected within the range of, for example, 3 to 20 or 5 to 10. The alignment marks 106 may also be used for etching the semiconductor layer.

[0027] The shape and size of the alignment mark 106 may be determined arbitrarily. The alignment mark 106 may be formed by sputtering using a material contained in the semiconductor layer, such as a gallium nitride-based material. This not only allows the alignment mark 106 to be formed using a semiconductor layer forming device, but also prevents the alignment mark 106 from being damaged by heat during semiconductor layer formation. Alternatively, the alignment mark 106 may be formed as a metal film. For example, the alignment mark 106 may be formed to include a material that can be used for the anode 118 or the cathode 120, or a metal with a melting point higher than the temperature during semiconductor layer formation. Specifically, the alignment mark 106 may be formed using metals such as gold, palladium, molybdenum, tungsten, tantalum, copper, and titanium. When a metal is used, the alignment mark 106 may be formed using CVD or sputtering.

[0028] Alternatively, a glass substrate may be used as the substrate 100, and the surface of the glass substrate may be processed to form the alignment marks 106. For example, the alignment marks 106 may be formed by sandblasting the substrate 100, treating it with hydrofluoric acid, or irradiating it with a laser such as a carbon dioxide laser.

[0029] (2) Formation of barrier and buffer layers The barrier layer 102 and the buffer layer 104 are formed on the substrate 100 so as to be shared by a plurality of light-emitting elements 110 or semiconductor layers (see FIG. 4B). The barrier layer 102 can be formed by a CVD method, a sputtering method, or the like.

[0030] The buffer layer 104 may also be formed by using a CVD method or a sputtering method. To more effectively grow the crystals of the semiconductor layer in the c-axis direction, the buffer layer 104 is preferably formed to have a high surface flatness. Specifically, the arithmetic mean roughness (Ra) of the surface of the buffer layer 104 is preferably smaller than 2.3 nm. Furthermore, the root-mean-square roughness (Rq) of the surface of the buffer layer 104 is preferably smaller than 2.9 nm. To achieve high surface flatness, the buffer layer 104 is preferably formed to have a thickness of 50 nm or less, for example, a thickness of 10 nm to 50 nm.

[0031] (3) Formation of semiconductor layer and electrodes Next, the n-type cladding layer 112, light-emitting layer 114, and p-type cladding layer 116, which constitute the semiconductor layers, are sequentially formed (see FIG. 4B). These layers can be formed using a sputtering method. For example, the substrate 100 and a gallium nitride target are placed in the chamber of a sputtering device. The gallium nitride target preferably has an atomic ratio of gallium to nitrogen of 0.7 or more and 2 or less. After the chamber is thoroughly evacuated, a sputtering gas is supplied. Examples of the sputtering gas include rare gases such as argon and krypton. The substrate 100 is heated to a temperature between room temperature and less than 600°C, preferably between 100°C and 400°C. Therefore, a substrate containing amorphous glass can be used as the substrate 100 supporting the light-emitting element 110. Furthermore, a voltage is applied between the substrate 100 and the gallium nitride target to generate plasma, which ionizes the sputtering gas. The ionized sputtering gas is accelerated and collides with the target, and the material scattered by this impact is deposited on the substrate 100, forming a functional layer containing gallium nitride. If a gallium nitride target containing silicon or germanium or a gallium nitride target containing magnesium is used instead of a gallium nitride target, it is possible to form an n-type cladding layer 112 or a p-type cladding layer 116 imparted with n-type or p-type conductivity. Furthermore, by using an indium gallium nitride target and a gallium nitride target, it is possible to form a light-emitting layer 114 in which indium gallium nitride films and gallium nitride films are alternately stacked.

[0032] As described above, the semiconductor layer is formed on the buffer layer 104. Therefore, even without applying vapor phase epitaxial growth, which has been conventionally used to form semiconductor layers, semiconductor particles ejected by sputtering a semiconductor target are deposited to form a semiconductor layer, and simultaneously c-axis oriented by the buffer layer 104. As a result, a highly crystalline semiconductor layer can be formed without requiring high temperatures during formation of the semiconductor layer. Note that patterning of the semiconductor layer can be performed by applying known photolithography, and therefore a detailed description thereof will be omitted.

[0033] The anode 118 and the cathode 120 may be formed by evaporation, CVD, or sputtering (see FIG. 4B).

[0034] (4) Inspection method using photoluminescence When photoluminescence is used in this inspection method, the semiconductor layer is inspected before the anode 118 and cathode 120 are formed. Schematic side and top views illustrating inspection using photoluminescence are shown in Figures 6A and 6B, respectively. These figures show a state in which the anode 118 and cathode 120 have not yet been formed, but only up to the p-type cladding layer 116 has been formed.

[0035] As described above, the light-emitting element 110, which is the subject of this inspection method, can be mounted on a large substrate 100. Therefore, if the inspection is performed so that all of the semiconductor layers fit within the measurement range of the detector, it would be difficult to evaluate the photoluminescence characteristics of each individual semiconductor layer in detail. Therefore, in this inspection method, as shown in FIG. 6B , the semiconductor layers, each including the n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116, are divided into multiple element groups 122, and inspection is performed for each element group 122. There is no restriction on the number of semiconductor layers included in one element group 122. However, as described above, each element group 122 is configured to include multiple semiconductor layers arranged in a matrix of multiple rows and multiple columns. The number of rows and columns may be selected from the range of 3 to 20 or 5 to 10. In the example shown in FIG. 6B , each element group 122 includes 16 semiconductor layers arranged in a 4-row, 4-column matrix.

[0036] This detection method uses a light source 132 for irradiating light onto the semiconductor layer and a detector 130 configured to acquire light emission characteristics from the semiconductor layer. The detector 130 can also be used in an inspection method using electroluminescence, which will be described later. For example, the detector 130 may be a spectrophotometer configured to generate a spectrum by dispersing light emitted from the semiconductor layer. Alternatively, the detector 130 may be a luminance meter configured to measure the luminance and / or chromaticity of light emitted from the semiconductor layer. Alternatively, the detector 130 may be an imaging device capable of capturing images of each semiconductor layer. Using the imaging device allows the shape and area of ​​the light-emitting region in each semiconductor layer to be measured. Alternatively, the detector 130 may have two or more functions of a spectrophotometer, a luminance meter, and an imaging device, or may be configured by combining two or more of a spectrophotometer, a luminance meter, and an imaging device. Detector 130 is positioned using alignment marks 106 so that it can detect light emitted from a plurality of semiconductor layers included in one element group 122, and its measurement range is adjusted (see dotted lines in FIG. 6A).

[0037] The light source 132 is configured to emit light that can be absorbed by the semiconductor layers, particularly the light-emitting layer 114 (see the dashed arrow in FIG. 6A ), and the light used is, for example, light in the wavelength range of 300 nm to 350 nm. The light may be incoherent light or may be laser light such as a He—Cd laser. The light source 132 may be configured to simultaneously irradiate all or a plurality of the semiconductor layers included in one element group 122 with light, or may be configured to sequentially irradiate each semiconductor layer with light.

[0038] In the example shown in FIG. 6A, the detector 130 and the light source 132 are connected to each other, but they may be separate and not connected to each other. Furthermore, since inspection is performed for each element group 122, a movement mechanism (not shown) is provided for relatively moving the detector 130 and the substrate 100 in a direction parallel to the upper surface of the substrate 100, as indicated by the white arrow in FIG. 6A. The movement mechanism may be, for example, a conveyor or robot for moving the substrate 100, or a rail or robot for moving the detector 130. The position of the detector 130 is adjusted using alignment marks 106 formed on the substrate 100. Furthermore, although not shown, a terminal for receiving the photoluminescence characteristics obtained by the detector 130 as data and for processing and storing the data is connected to the detector 130 wirelessly or via a wire.

[0039] As described above, the n-type cladding layer 112, the light-emitting layer 114, and the p-type cladding layer 116 that constitute the semiconductor layer are formed by sputtering, and the temperature during film formation can reach 500°C to 600°C. On the other hand, the strain point of a glass substrate, which is exemplified as the substrate 100, is 650°C to 720°C. Therefore, the semiconductor layer can be formed at a temperature lower than the strain point of the substrate 100. However, if the temperature during semiconductor layer formation approaches the strain point, deformation of the substrate 100, such as warping or bending, may occur. Such deformation may change the distance between the semiconductor layer and the detector 130 or the direction of light emission from the semiconductor layer. Therefore, to correct the influence of deformation of the substrate 100, a length measuring device 134 may be used to measure the distance of the detector 130 from the substrate 100 and / or the angle of the detector 130 relative to the substrate 100. An example of the length measuring device 134 is a laser length measuring device that can emit laser light to an object and measure distance and angle based on the reflected light. The length measuring device 134 is preferably fixed to the detector 130. The detector 130 may be configured so that its position and angle with respect to the substrate 100 can be adjusted according to the distance of the detector 130 from the substrate 100 and / or the angle with respect to the substrate 100 obtained by the length measuring device 134. This allows the photoluminescence characteristics to be accurately evaluated even if the substrate 100 is deformed.

[0040] In this inspection method, multiple detectors 130 may be used. This allows for more efficient inspection. For example, as shown in the schematic side and top views of FIGS. 7A and 7B, a first detector 130-1 and a second detector 130-2 may be used to acquire the photoluminescence characteristics of multiple semiconductor layers included in the element group 122. In this case, a first light source 132-1 and a second light source 132-2, and a first length measuring device 134-1 and a second length measuring device 134-2 may be used, which are linked to the first detector 130-1 and the second detector 130-2, respectively.

[0041] When multiple detectors 130 are used, the photoluminescence characteristics of the same semiconductor layer are acquired by the multiple detectors 130 to eliminate variations in detection sensitivity between the detectors 130. Specifically, as shown in FIG. 7B , the semiconductor layer is divided into multiple element groups 122 so that at least one light-emitting element is included in both of two adjacent element groups 122-1 and 122-2. The number of light-emitting elements 110 shared by the two element groups 122-1 and 122-2 is one or more. The photoluminescence characteristics of the shared light-emitting elements 110 are measured using the multiple detectors 130, and the obtained data is calibrated so that both results are identical, or the detectors 130 are calibrated. Such calibration eliminates the need to evaluate the same element group 122 using multiple detectors 130, enabling highly efficient inspection.

[0042] In this inspection method, the semiconductor layer of each element group 122 is irradiated with light using a light source 132, and the light emitted from the semiconductor layer is measured with a detector 130 to evaluate the photoluminescence characteristics. In the evaluation, characteristics such as the emission peak wavelength and its intensity, the shape of the spectrum, and the rising and falling wavelengths of the spectrum are used. Alternatively, characteristics such as the brightness and chromaticity of the light emitted from each semiconductor layer, or the shape and area of ​​the light-emitting region are evaluated. If these characteristics satisfy predetermined specifications, the semiconductor layer is determined to be non-defective; otherwise, the semiconductor layer is determined to be defective. Furthermore, each semiconductor layer may be classified (ranked) based on these characteristics.

[0043] (5) Inspection method using electroluminescence When electroluminescence is used in this inspection method, the light-emitting elements 110 obtained by forming the anode 118 and the cathode 120 are subjected to inspection. As with inspections using photoluminescence, in inspections using electroluminescence, the electroluminescence characteristics are acquired and evaluated for each element group 122. The element group 122 used in the inspection using electroluminescence may be the same as or different from the element group 122 used in the inspection using photoluminescence. Specifically, all of the light-emitting elements 110 included in one element group 122 used in the inspection using electroluminescence may be the light-emitting elements 110 included in one element group 122 used in the inspection using photoluminescence. Alternatively, only some of the light-emitting elements 110 included in one element group 122 used in the inspection using electroluminescence may be included in one element group 122 used in the inspection using photoluminescence. The inspection method using electroluminescence will be described in detail below, but descriptions of configurations and methods similar to those of the inspection method using photoluminescence may be omitted.

[0044] In an electroluminescence-based test, power is supplied to the light-emitting elements 110 included in each element group 122, and the light emitted from the light-emitting layer 114, i.e., electroluminescence, is measured by a detector 130 to evaluate the electroluminescence characteristics. For this purpose, a test substrate is used to supply power to each element group 122. Schematic top views of one element group 122 and a test substrate 140 are shown in FIGS. 8A and 8B, respectively. Here, an example is shown in which one element group 122 includes six light-emitting elements 110 arranged in two rows and three columns. As shown in FIG. 8B, the test substrate 140 includes a translucent substrate 142 that transmits visible light, and anode wiring 144 and cathode wiring 146 provided on the translucent substrate 142. Although not shown, the test substrate 140 may further include alignment marks for aligning the test substrate 140. By aligning the alignment marks of the test substrate 140 with the alignment marks 106 formed on the substrate 100, the test substrate 140 can be positioned on the element group 122 easily and accurately.

[0045] The light-transmitting substrate 142 is, for example, a glass substrate, and has a size and shape sufficient to cover the entirety of one element group 122 or all of the light-emitting elements 110 included in one element group 122. Since the light-emitting elements 110 included in one element group 122 are also arranged in a matrix, the light-transmitting substrate 142 is, for example, rectangular. The anode wiring 144 and the cathode wiring 146 are wiring containing a metal such as aluminum, molybdenum, tantalum, titanium, or tungsten, and are arranged to receive power from an external power source (not shown).

[0046] 9A shows a schematic top view of the state in which the light-transmitting substrate 142 is placed on the element group 122 so that the anode wiring 144 and the cathode wiring 146 are sandwiched between the light-transmitting substrate 142 and the substrate 100, and FIG. 9B shows a schematic view of the end surface along the chain line BB' in FIG. 9A. As can be seen from these figures, the cathode wiring 146 is provided so as to be in physical and electrical contact with the n-type cladding layer 112 when the test substrate 140 is placed on the light-emitting elements 110. Preferably, the cathode wiring 146 is provided so as to overlap in the column direction with all of the plurality of light-emitting elements 110 arranged in the row direction in the element group 122, or so as to overlap in the row direction with all of the plurality of light-emitting elements 110 arranged in the column direction in the element group 122. This enables reliable electrical connection between the cathode wiring 146 and the n-type cladding layer 112 and prevents the distance from the contact interface between the cathode wiring 146 and the n-type cladding layer 112 to the light-emitting element 110 from increasing or becoming uneven, thereby enabling the same or approximately the same potential to be supplied to the n-type cladding layer 112 of the multiple light-emitting elements 110. On the other hand, the anode wiring 144 is provided so as to be in physical and electrical contact with all or at least two of the multiple light-emitting elements 110 included in the element group 122 when the test substrate 140 is placed on the light-emitting element 110. Therefore, as shown in FIG. 9B , the thicknesses of the anode wiring 144 and the cathode wiring 146 may be different, the difference being the height difference between the top surface of the anode 118 and the top surface of the n-type cladding layer 112 between the light-emitting elements 110.

[0047] Test substrate 140 having the above structure is arranged so that anode wiring 144 and cathode wiring 146 are in contact with anode 118 and n-type cladding layer 112, respectively, and a potential difference is applied between them so that anode wiring 144 has a higher potential than cathode wiring 146. Then, because n-type cladding layer 112 is shared by multiple light-emitting elements 110, electrons are supplied to light-emitting elements 110 in element group 122. Meanwhile, holes are supplied to anode 118 of light-emitting element 110. As a result, electrons and holes recombine in light-emitting layer 114, resulting in electroluminescence.

[0048] As described above, the anode wiring 144 is provided so as to be electrically connected to the anodes 118 of all or at least two of the light-emitting elements 110 in the element group 122. Therefore, by applying a potential difference between the anode wiring 144 and the cathode wiring 146, light can be emitted simultaneously from all or at least two of the light-emitting elements 110 in the element group 122. In this state, electroluminescence characteristics can be obtained using the detector 130, similar to an inspection method using photoluminescence. Note that the detector 130 may be disposed on the inspection substrate 140 side and light emitted from the light-emitting layer 114 toward the anode 118 side may be utilized, or the detector 130 may be disposed on the substrate 100 side and light emitted from the light-emitting layer 114 toward the substrate 100 side may be utilized.

[0049] The configuration of the test board 140 is not limited to the above configuration. For example, as shown in Fig. 10A or 10B, the test board 140 may be configured so that multiple anode wires 144 are provided and power can be supplied to multiple light-emitting elements 110 on a row or column basis. In the example shown in Fig. 10A, multiple anode wires 144 are provided to simultaneously supply power to two or more light-emitting elements 110 arranged in a single row. On the other hand, in the example shown in Fig. 10B, multiple anode wires 144 are provided to simultaneously supply power to light-emitting elements 110 arranged in a single column.

[0050] Furthermore, as shown in the schematic top view of FIG. 11A and the schematic end view along the dashed line CC′ (FIG. 11B), a light-shielding film 148 for blocking light emitted from some of the light-emitting elements 110 may be provided on the test substrate 140. The light-shielding film 148 is provided in contact with the light-transmitting substrate 142 or on the light-transmitting substrate 142 via an undercoat 150. The undercoat 150 is an insulating film and may be composed of one or more films containing, for example, a silicon-containing inorganic compound. The light-shielding film 148 may include, for example, a metal film with low light transmittance such as chromium, or a resin in which a black or similar color pigment is dispersed. The light-shielding film 148 may be provided on either the upper or lower surface of the light-transmitting substrate 142.

[0051] The light-shielding film 148 has a plurality of openings that expose one or more light-emitting elements 110 when the test substrate 140 is placed on the light-emitting elements 110 of the element group 122. The light-shielding film 148 blocks light emitted from the light-emitting elements 110 that overlap with portions other than the openings (non-openings) and allows light emitted from the light-emitting elements 110 that overlap with the openings to pass through. The arrangement of the multiple openings is arbitrary, and they may be arranged, for example, to form a checkerboard pattern. That is, the openings may be provided so as to overlap every other light-emitting element 110 selected in the row and / or column directions. Alternatively, the light-shielding film 148 may be configured so as to have openings that overlap a pair of light-emitting elements 110 that sandwich one or more light-emitting elements 110 when the test substrate 140 is placed on the light-emitting elements 110 of the element group 122, and the non-openings overlap the one or more light-emitting elements 110.

[0052] Even when the light-shielding film 148 is provided, the anode wirings 144 are formed so that the anodes 118 of all the light-emitting elements 110 are in contact with one of the anode wirings 144. Therefore, when a potential difference is applied between the anode wirings 144 and the cathode wirings 146, all the light-emitting elements 110 in contact with the anode wirings 144 simultaneously emit light. Therefore, if the light-shielding film 148 is not provided, evaluation of the electroluminescence characteristics of one light-emitting element 110 may be affected by the electroluminescence of an adjacent light-emitting element 110. However, by providing the light-shielding film 148, it is possible to obtain the electroluminescence characteristics of the light-emitting elements 110 overlapping the opening while eliminating the influence of the light emission from the light-emitting elements 110 overlapping the non-opening. Therefore, for example, by forming the openings in a checkerboard pattern, it is possible to eliminate the influence of the electroluminescence of adjacent light-emitting elements 110, enabling more accurate evaluation of the electroluminescence characteristics.

[0053] Although a detailed description will be omitted, similar to inspections that utilize photoluminescence, in inspection methods that utilize electroluminescence, the distance from the substrate of the detector 130 and the angle relative to the substrate may be adjusted. Furthermore, multiple detectors 130 may be used, and calibration may be performed to eliminate detection variations between the detectors 130.

[0054] Similar to the inspection method using photoluminescence, the inspection method using electroluminescence also utilizes characteristics such as the emission peak wavelength and its intensity, the shape of the spectrum, and the rising and falling wavelengths of the spectrum. Alternatively, characteristics such as the luminance and chromaticity of the light emitted from each light-emitting element 110, or the shape and area of ​​the light-emitting region, are evaluated. If these characteristics satisfy predetermined specifications, the light-emitting element 110 is determined to be a non-defective product; otherwise, the light-emitting element 110 is determined to be a defective product. Furthermore, each light-emitting element 110 may be classified (ranked) based on these characteristics.

[0055] As described above, in this inspection method, multiple light-emitting elements 110 provided on an amorphous substrate 100 are inspected using photoluminescence and / or electroluminescence. The light-emitting elements 110 are LEDs, and the semiconductor layers included in the light-emitting elements 110 are formed using a sputtering method. Therefore, it is possible to use a large substrate 100, also known as mother glass. When using such a large substrate as the substrate 100, a large inspection device is required to inspect the light-emitting elements 110. However, in this inspection method, all of the light-emitting elements 110 are divided into multiple element groups 122, and each element group 122 is inspected separately. Therefore, a large detector is not required. Furthermore, since the light-emitting elements 110 on the large substrate 100 can be inspected using multiple detectors 130 while eliminating variations in detection sensitivity, inspection can be performed efficiently and quickly in a short time. This contributes to reducing the manufacturing cost of light-emitting devices including the light-emitting elements 110.

[0056] The light emitting element 110 on the substrate 100 that has undergone this inspection method can be mounted, using a so-called transfer method, on a device substrate provided with wiring and circuits for driving the light emitting element 110. This allows a light emitting device including the light emitting element 110 to be manufactured. At this time, only the light emitting element 110 that has been determined to be non-defective by this inspection method can be selectively used in the manufacture of the light emitting device, thereby preventing a decrease in the manufacturing yield of the light emitting device due to the semiconductor layer or the light emitting element 110. Therefore, by applying the embodiments of the present invention, it is also possible to reduce the manufacturing costs of light emitting devices such as display devices and lighting devices.

[0057] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, a display device in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits processes or modifies conditions, based on the display device of each embodiment, is also included in the scope of the present invention as long as it includes the gist of the present invention.

[0058] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0059] 100: substrate, 100a: region, 102: barrier layer, 104: buffer layer, 106: alignment mark, 110: light emitting element, 112: n-type cladding layer, 114: light emitting layer, 116: p-type cladding layer, 118: anode, 120: cathode, 122: element group, 122-1: element group, 122-2: element group, 130: detector, 130-1: first detector, 130-2: second detector, 132: light source, 132-1: first light source, 132-2: second light source, 134: length measuring device, 134-1: first length measuring device, 134-2: second length measuring device, 140: inspection substrate, 142: light-transmitting substrate, 144: anode wiring, 146: cathode wiring, 148: light-shielding film, 150: undercoat

Claims

1. forming a buffer layer on the amorphous substrate; forming an n-type cladding layer, a light-emitting layer, and a p-type cladding layer, each containing an inorganic semiconductor, on the buffer layer, thereby forming a plurality of semiconductor layers arranged in a matrix having a plurality of rows and a plurality of columns; forming a plurality of light-emitting elements by forming an anode and a cathode on each of the plurality of semiconductor layers; and acquiring at least one of photoluminescence characteristics and electroluminescence characteristics of the plurality of light-emitting elements using a first detector and a second detector; the buffer layer has a function of promoting crystallization of the semiconductor layer, the photoluminescence properties are obtained prior to forming the anode and the cathode; the electroluminescent properties are obtained after forming the anode and the cathode; The obtaining of the photoluminescence characteristics includes: simultaneously irradiating a first element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the first element group with the first detector; and irradiating a second element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the second element group with the second detector; The obtaining of the electroluminescent properties comprises: simultaneously supplying power to the light-emitting elements included in a third element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the third element group with the first detector; and supplying power to the light-emitting elements included in a fourth element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the fourth element group with the second detector; at least one light-emitting element among the plurality of light-emitting elements is included in both the first element group and the second element group, The method for testing a light-emitting element further comprising calibrating the first detector and the second detector using the photoluminescence of the at least one light-emitting element.

2. The method of claim 1 , wherein both the photoluminescence property and the electroluminescence property are obtained.

3. Forming a buffer layer on an amorphous substrate; forming an n-type cladding layer, a light-emitting layer, and a p-type cladding layer, each containing an inorganic semiconductor, on the buffer layer, thereby forming a plurality of semiconductor layers arranged in a matrix having a plurality of rows and a plurality of columns; forming a plurality of light-emitting elements by forming an anode and a cathode on each of the plurality of semiconductor layers; and acquiring at least one of photoluminescence characteristics and electroluminescence characteristics of the plurality of light-emitting elements using a first detector and a second detector; the buffer layer has a function of promoting crystallization of the semiconductor layer, the photoluminescence properties are obtained prior to forming the anode and the cathode; the electroluminescent properties are obtained after forming the anode and the cathode; The obtaining of the photoluminescence characteristics includes: simultaneously irradiating a first element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the first element group with the first detector; and irradiating a second element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the second element group with the second detector; The obtaining of the electroluminescent properties comprises: simultaneously supplying power to the light-emitting elements included in a third element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the third element group with the first detector; and supplying power to the light-emitting elements included in a fourth element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the fourth element group with the second detector; at least one light-emitting element among the plurality of light-emitting elements is included in both the third element group and the fourth element group, The method for testing light-emitting elements, further comprising calibrating the first detector and the second detector using the electroluminescence of the at least one light-emitting element.

4. the light-emitting element included in the first element group is the light-emitting element included in the third element group, The method of claim 1 , wherein the light emitting elements included in the second group of elements are the light emitting elements included in the fourth group of elements.

5. forming a plurality of alignment marks on the amorphous substrate for aligning the first detector and the second detector; The method of claim 1 , wherein the plurality of alignment marks comprise the inorganic semiconductor.

6. The method according to claim 5 , wherein the plurality of alignment marks are formed outside an area where the plurality of light emitting elements are disposed.

7. The method of claim 5 , wherein at least one of the plurality of alignment marks is formed between adjacent light emitting elements.

8. The method of claim 1 , wherein the first detector and the second detector are configured such that their distance from and / or angle with respect to the amorphous substrate is adjustable.

9. Forming a buffer layer on an amorphous substrate; forming an n-type cladding layer, a light-emitting layer, and a p-type cladding layer, each containing an inorganic semiconductor, on the buffer layer, thereby forming a plurality of semiconductor layers arranged in a matrix having a plurality of rows and a plurality of columns; forming a plurality of light-emitting elements by forming an anode and a cathode on each of the plurality of semiconductor layers; and acquiring at least one of photoluminescence characteristics and electroluminescence characteristics of the plurality of light-emitting elements using a first detector and a second detector; the buffer layer has a function of promoting crystallization of the semiconductor layer, the photoluminescence properties are obtained prior to forming the anode and the cathode; the electroluminescent properties are obtained after forming the anode and the cathode; The obtaining of the photoluminescence characteristics includes: simultaneously irradiating a first element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the first element group with the first detector; and irradiating a second element group including two or more light-emitting elements selected from the plurality of light-emitting elements with light, and measuring photoluminescence of the light-emitting elements included in the second element group with the second detector; The obtaining of the electroluminescent properties comprises: simultaneously supplying power to the light-emitting elements included in a third element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the third element group with the first detector; and supplying power to the light-emitting elements included in a fourth element group including two or more light-emitting elements selected from the plurality of light-emitting elements, and measuring electroluminescence of the light-emitting elements included in the fourth element group with the second detector; the obtaining of the electroluminescence characteristics includes supplying power to the plurality of light-emitting elements via a test substrate; The test board includes: a transparent substrate that transmits visible light; a first wiring on the light-transmitting substrate; and a second wiring on the light-transmitting substrate; the first wiring is configured to be electrically connected to the n-type clad layer when the test substrate is placed on the plurality of light-emitting elements; the second wiring is configured to be electrically connected to the anodes of at least two light-emitting elements when the test board is placed on the plurality of light-emitting elements; the at least two light emitting elements are arranged so as to sandwich another light emitting element therebetween, the test substrate further includes a light-shielding film; The method for inspecting light-emitting elements, wherein the light-shielding film is configured to overlap the other light-emitting elements when the inspection substrate is placed on the plurality of light-emitting elements.

10. The method of claim 1 , wherein the n-type cladding layer is continuous between adjacent light emitting elements.

11. The method of claim 9 , wherein the at least two light emitting elements are arranged in the row or column direction.

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