Method for inspecting semiconductor layer structure and apparatus for inspecting semiconductor layer structure

Abstract

To provide a semiconductor layer structure inspection method and a semiconductor layer structure inspection device based on irradiation of light, with which inspection can be efficiently carried out, and inspection quality is high.SOLUTION: Provided is an inspection method for determining the acceptability of a semiconductor layer structure which has a plurality of light emission parts including a light emission layer. The inspection method includes: a primary determination step for irradiating, at a first intensity of irradiation, the semiconductor layer structure with first inspection light of a shorter wavelength than the light emitted by the light emission layer and primarily determining the acceptability of the light emission parts on the basis of a fluorescent image of the semiconductor layer structure acquired by irradiation of the first inspection light; a secondary determination step for irradiating, at a second intensity of irradiation lower than the first intensity of irradiation, the semiconductor layer structure with second inspection light of a shorter wavelength than the light emitted by the light emission layer and secondarily determining the acceptability of the light emission parts on the basis of a fluorescent image of the semiconductor layer structure acquired by irradiation of the second inspection light; and a tertiary determination step for determining the acceptability of each of the light emission parts on the basis of the primary and secondary determinations.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for inspecting semiconductor layer structures and an apparatus for inspecting semiconductor layer structures. [Background technology]

[0002] For example, semiconductor light-emitting elements such as light-emitting diodes (LEDs) are manufactured by stacking multiple semiconductor layers, including a light-emitting layer, on a substrate to form electrodes, and are shipped after their light-emitting characteristics are inspected. Generally, this inspection of light-emitting characteristics is performed by applying a voltage between the positive and negative pad electrodes of multiple semiconductor light-emitting elements in the wafer state, thereby causing current to flow through the semiconductor layers and making them emit light.

[0003] However, luminescence testing using an electric current requires contacting the probe of a probe to the electrodes of each individual semiconductor light-emitting element, which is time-consuming. Therefore, as a method for testing the luminescence performance of semiconductor light-emitting elements without passing an electric current through them, testing methods have been proposed and investigated that involve irradiating the active layer of the semiconductor light-emitting element with light to excite it and observing the fluorescence emitted from the excited active layer (Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2009-128366 [Patent Document 2] Japanese Patent Publication No. 2013-038313 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, while inspection methods that use light irradiation to determine the quality of semiconductor light-emitting elements are efficient, there is a need to improve the quality of the inspections.

[0006] Therefore, the purpose of this disclosure is to provide a method and apparatus for inspecting semiconductor layer structures by light irradiation, which enables efficient and high-quality inspection. [Means for solving the problem]

[0007] To achieve the above objectives, a method for inspecting a semiconductor layer structure according to the present disclosure is a method for determining the quality of a semiconductor layer structure having a plurality of light-emitting parts including a light-emitting layer, and includes: a primary determination step of irradiating the semiconductor layer structure with a first inspection light having a shorter wavelength than the light emitted by the light-emitting layer at a first irradiation intensity and making a primary determination of the quality of the light-emitting parts based on a first fluorescence image of the semiconductor layer structure obtained by irradiation with the first inspection light; a secondary determination step of irradiating the semiconductor layer structure with a second inspection light having a shorter wavelength than the light emitted by the light-emitting layer at a second irradiation intensity lower than the first irradiation intensity and making a secondary determination of the quality of the light-emitting parts based on a second fluorescence image of the semiconductor layer structure obtained by irradiation with the second inspection light; and a tertiary determination step of determining the quality of each light-emitting part based on the primary determination and the secondary determination.

[0008] An inspection apparatus for a semiconductor layer structure according to this disclosure is an inspection apparatus for determining the quality of a plurality of light-emitting parts, including a light-emitting layer, by irradiating the semiconductor layer structure with inspection light, the apparatus comprising: an irradiation unit that irradiates the semiconductor layer structure with inspection light whose irradiation intensity and wavelength can be adjusted; a control unit that controls the irradiation unit so that a first inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a first irradiation intensity, and a second inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a second irradiation intensity lower than the first irradiation intensity; an image acquisition unit that acquires a first fluorescence image of the semiconductor layer structure obtained by irradiation with the first inspection light and acquires a second fluorescence image of the semiconductor layer structure obtained by irradiation with the second inspection light; and a determination unit that determines the quality of each light-emitting part based on the first fluorescence image and the second fluorescence image.

[0009] Another form of inspection method for semiconductor layer structures according to this disclosure is an inspection method for determining the quality of a semiconductor layer structure having a plurality of light-emitting parts including a light-emitting layer, and includes the steps of: preparing a database that stores the correlation between the current value used when determining the quality of the light-emitting parts by applying an electric current and the irradiation intensity used when determining the quality by irradiating with inspection light having a shorter wavelength than the light emitted by the light-emitting parts; an irradiation intensity acquisition step of obtaining a first irradiation intensity corresponding to the applied current value to be determined by referring to the database; an irradiation step of irradiating the semiconductor layer structure with the inspection light at the first irradiation intensity; and a determination step of determining the quality of the light-emitting parts based on a fluorescence image of the semiconductor layer structure obtained by the irradiation step.

[0010] Another form of semiconductor layer structure inspection apparatus according to the present disclosure is an inspection apparatus for determining the quality of a semiconductor layer structure comprising a plurality of light-emitting parts including a light-emitting layer, and includes: a database storing a correlation between a current value used to determine the quality of a light-emitting part by applying a current and an irradiation intensity used to determine the quality by irradiating the semiconductor layer structure with inspection light having a shorter wavelength than the light emitted by the light-emitting layer; an irradiation unit that irradiates the semiconductor layer structure with the inspection light; a control unit that, by referring to the database, obtains an irradiation intensity corresponding to the applied current value to be determined as quality, controls the emission intensity of the inspection light so that the inspection light of the acquired irradiation intensity is irradiated onto the semiconductor layer structure, and causes the irradiation unit to irradiate the semiconductor layer structure with the inspection light; an image acquisition unit that acquires a fluorescence image of the semiconductor layer structure due to irradiation with the inspection light; and a determination unit that determines the quality of the semiconductor layer structure based on the acquired fluorescence image and outputs the determination result as the determination result of the semiconductor layer structure at the applied current value. [Effects of the Invention]

[0011] As described above, the semiconductor layer structure inspection method and inspection apparatus according to this disclosure can provide an inspection method and inspection apparatus for semiconductor layer structures using light irradiation that allows for efficient inspection and high inspection quality. [Brief explanation of the drawing]

[0012] [Figure 1]It is a flowchart of the inspection method of Embodiment 1 according to the present disclosure. [Figure 2] It is a configuration diagram schematically showing the inspection apparatus of Embodiment 1. [Figure 3] It is a flowchart of another inspection method of Embodiment 1 according to the present disclosure. [Figure 4] It is a flowchart of the inspection method of Embodiment 2 according to the present disclosure. [Figure 5] It is a flowchart of the database preparation step in the inspection method of Embodiment 2. [Figure 6] It is a configuration diagram schematically showing the inspection apparatus of Embodiment 2.

Mode for Carrying Out the Invention

[0013] Hereinafter, the inspection method and inspection apparatus according to the present disclosure will be described with reference to the drawings. [Embodiment 1] The inspection method of Embodiment 1 according to the present disclosure is an inspection method in which inspection lights with different irradiation intensities are irradiated, the quality of the light emitting part is determined in each fluorescence image obtained by each irradiation, and the light emitting part determined to be a non-defective product in any of the quality determinations is determined to be a non-defective product, and it is based on the following findings.

[0014] That is, in the quality determination by the fluorescence image, when the luminance of the fluorescence emission is small, the light emitting part is determined to be a defective product. However, there are cases where the light emitting part determined to be a non-defective product when the inspection light is irradiated with a weak irradiation intensity is determined to be a defective product when the inspection light is irradiated with a strong irradiation intensity. Therefore, when the irradiation intensity of the inspection light was increased, conversely, it was found that there are cases where the light emitting part determined to be a defective product when the inspection light is irradiated with a weak irradiation intensity is determined to be a non-defective product when the inspection light is irradiated with a strong irradiation intensity. The above-described findings are findings independently discovered by the present inventors, and the inspection method of Embodiment 1 according to the present disclosure is based on the above findings independently discovered by the present inventors. Hereinafter, the inspection method and inspection apparatus of Embodiment 1 will be described in detail.

[0015] FIG. 1 is a flowchart of the inspection method according to Embodiment 1 of the present disclosure. The inspection method according to Embodiment 1 is an inspection method for determining the quality of a semiconductor layer structure including a plurality of light-emitting portions each including a light-emitting layer. As shown in FIG. 1, it includes a primary determination step S510, a secondary determination step S520, and a tertiary determination step S530. Here, in particular, in the primary determination step S510, a first inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated with a first irradiation intensity, and the quality of the light-emitting portion is determined based on a first fluorescence image obtained by the irradiation. In the secondary determination step S520, a second inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated with a second irradiation intensity lower than the first irradiation intensity, and the quality of the light-emitting portion is determined based on a second fluorescence image obtained by the irradiation. Then, in the tertiary determination step S530, a light-emitting portion determined to be a non-defective product in any of the determinations in the primary determination step S510 and the secondary determination step S520 is determined to be a non-defective product. Thereby, it is possible to provide an inspection method for a semiconductor layer structure by light irradiation that enables efficient inspection and has high inspection quality.

[0016] More specifically, in the inspection method of Embodiment 1, the primary determination step S510 includes, as shown in Figure 1, a first irradiation step S511 in which a first inspection light with a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a first irradiation intensity; a first fluorescence image acquisition step S512 in which an image (first fluorescence image) formed by fluorescence emission emitted when the light-emitting part is excited by the irradiation of the first inspection light is acquired; and a first determination step S513 in which the quality of the light-emitting part is determined based on the acquired first fluorescence image. The secondary determination step S520 includes a second irradiation step S521 in which a second inspection light with a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a second irradiation intensity lower than the first irradiation intensity; a second fluorescence image acquisition step S522 in which an image (second fluorescence image) formed by fluorescence emission emitted when the light-emitting part is excited by the irradiation of the second inspection light is acquired; and a second determination step S523 in which the quality of the light-emitting part is determined based on the acquired second fluorescence image. Then, in the third determination step S530, the light-emitting part that was determined to be good in both the first determination step S510 and the second determination step S520 is determined to be good.

[0017] <First irradiation step S511, second irradiation step S521> In the first irradiation step S511 of the primary determination step S510, the first inspection light is used, and in the second irradiation step S521 of the secondary determination step S520, the second inspection light is used, and light with a shorter wavelength than the light emitted by the light-emitting layer is used. For example, if the light emitted by the light-emitting layer is visible light, then the first and second inspection lights are used, and the light has an emission peak wavelength of 405 nm, which is close to the wavelength of visible light. The wavelengths of the first and second inspection lights may be the same or different. If the wavelengths of the first and second inspection lights are the same, the configuration of the irradiation unit in the inspection apparatus described later can be simplified. A semiconductor layer structure is a structure in which multiple semiconductors are arranged in layers, for example, as part of a light-emitting element. The light-emitting layer is the layer within the semiconductor layer structure that emits light. Specifically, a semiconductor layer structure is made of nitride semiconductors, and In x Al y Ga 1-x-yN satisfies 0≦X≦1 and 0≦Y≦1. The light-emitting layer is the same.

[0018] Also, the first irradiation intensity of the first inspection light in the first irradiation step S511 is preferably set within a range of intensity similar to reproducing the light emission phenomenon caused by the first current application, more preferably within a range of irradiation intensity corresponding to the first applied current value. The preferable range of the first irradiation intensity is 0.75 mW / cm 2 or more and 2.0 mW / cm 2 or less. For example, 1.0 mW / cm 2 is included. The second irradiation intensity of the second inspection light in the second irradiation step S521 is preferably set within a range of intensity similar to reproducing the light emission phenomenon caused by the second current application, more preferably within a range of irradiation intensity corresponding to the second applied current value. The preferable range of the second irradiation intensity is 0.05 mW / cm 2 or more and 0.50 mW / cm 2 or less. For example, 0.15 mW / cm 2 is included. By setting the first irradiation intensity and the second irradiation intensity within the above ranges, defects not detected in the primary determination step S510 can be detected in the secondary determination step S520, and defects not detectable in the secondary determination step S520 can be detected in the primary determination step S510.

[0019] <First Image Acquisition Step S512, Second Image Acquisition Step S522> The first fluorescence image acquired in the first fluorescence image acquisition step S512 is an image obtained from the semiconductor layer structure when the light-emitting part is excited by irradiation with the first inspection light and emits fluorescence, and the light is emitted from the semiconductor layer structure. For example, the first fluorescence image includes brightness corresponding to the intensity of fluorescence emission and contrast information, which is an index of brightness that changes with position. Similarly, the second fluorescence image acquired in the second fluorescence image acquisition step S52 is an image obtained from the semiconductor layer structure when the light-emitting part is excited by irradiation with the second inspection light and emits fluorescence, and the light is emitted from the semiconductor layer structure. For example, the second fluorescence image includes brightness corresponding to the intensity of fluorescence emission and contrast information, which is an index of brightness that changes with position.

[0020] <First judgment step S513, second judgment step S523> The first determination step S513 of the primary determination step S510 includes determining that any light-emitting portion in the first fluorescence image whose emission is less than the first reference intensity is a defective product. The first reference intensity is set based on an image obtained from fluorescence emission when a first inspection light is irradiated at a first irradiation intensity onto a reference semiconductor layer structure that has the same configuration as the semiconductor layer structure to be determined and has been certified as a good product by a good / bad judgment by applying current. Here, the first reference intensity is, for example, the peak value of the emission intensity calculated based on the highest brightness in the image, or the average value of the emission intensity calculated based on the average value of the brightness in the image. The first reference intensity may include both the peak value of the emission intensity and the average value of the emission intensity calculated based on the average value of the brightness in the image.

[0021] The second determination step S523 of the secondary determination step S520 includes determining that any light-emitting portion in the second fluorescence image that is different from the first reference intensity and is less than the second reference intensity is a defective product. The second reference intensity, like the first reference intensity, is set based on an image formed by fluorescence emission when a second inspection light is irradiated at a second irradiation intensity onto a reference semiconductor layer structure that has the same configuration as the semiconductor layer structure to be determined and has been certified as a good product by a good / bad judgment by applying current. Here, the second reference intensity is, for example, the peak value of the emission intensity calculated based on the highest brightness in the image, or the average value of the emission intensity calculated based on the average value of the brightness in the image. The second reference intensity may include both the peak value of the emission intensity and the average value of the emission intensity calculated based on the average value of the brightness in the image. Here, the reference semiconductor layer structure refers to a semiconductor layer structure that has been determined to be good by applying an electric current during a conventional semiconductor layer structure inspection. As will be explained later, this reference semiconductor layer structure is determined to be good by performing an inspection by applying an electric current, but it is also possible to prepare a reference semiconductor layer structure in advance, or more specifically, to prepare purchased reference semiconductor layer structures that have been determined to be good. Furthermore, it is preferable that the second determination step S523 of the secondary determination step S520 includes determining that any light-emitting portion that exhibits emission at a third reference intensity or higher, greater than the second reference intensity, in the second fluorescence image is a defective product. This allows for the determination of not only light-emitting portions with weak emission intensity as defective products, but also semiconductor layer structures that include abnormally strong light-emitting portions as defective products. A strong light-emitting portion refers to a light-emitting portion that can be observed by irradiating a defect in the semiconductor, such as a so-called pit structure, with excitation light.

[0022] In the first determination step S513 of the primary determination step S510, the pass / fail status may be determined by comparing the first fluorescence image of the semiconductor layer structure to be inspected with the first reference fluorescence image obtained when the same light as the first inspection light is irradiated on a reference semiconductor layer structure that has been determined to be good at a first irradiation intensity. Alternatively, in the second determination step S523 of the secondary determination step S520, the pass / fail status may be determined by comparing the second fluorescence image of the semiconductor layer structure to be inspected with the second reference fluorescence image obtained when the same light as the second inspection light is irradiated on a reference semiconductor layer structure that has been determined to be good at a second irradiation intensity. This allows for efficient inspection and enables inspection of semiconductor layer structures with high inspection quality.

[0023] The first reference fluorescence image may be an image obtained when the same light as the first inspection light is simultaneously irradiated onto multiple reference semiconductor layer structures that have been determined to be good. By using a first reference fluorescence image that includes images of multiple reference semiconductor layer structures, for example, it is possible to efficiently determine whether a product is good or bad by comparing it with a fluorescence image that includes images of multiple semiconductor layer structures that are the subject of inspection. Furthermore, the second reference fluorescence image may be an image obtained when the same light as the second inspection light is simultaneously irradiated onto multiple reference semiconductor layer structures that have been determined to be good. By using a second reference fluorescence image that includes images of multiple reference semiconductor layer structures, for example, it is possible to efficiently determine whether a product is good or bad by comparing it with a fluorescence image that includes images of multiple semiconductor layer structures that are being inspected.

[0024] Here, the first and second reference fluorescence images, which include images obtained when multiple reference semiconductor layer structures are irradiated simultaneously, and the first and second fluorescence images, which include images obtained when multiple reference semiconductor layer structures to be inspected are, for example, images obtained by irradiating an entire wafer on which multiple reference semiconductor layer structures are formed with inspection light. Furthermore, the third judgment step determines that items that were determined to be good in the first judgment step and also determined to be good in the second judgment step are considered good. Items that were determined to be defective in either the first or second judgment step are determined to be defective in the third judgment step.

[0025] The inspection method of Embodiment 1 described above provides an efficient and high-quality inspection method for semiconductor layer structures, as it irradiates the light source with inspection light of different irradiation in the primary determination step S510 and the secondary determination step S520, and determines the quality of the light-emitting portion based on the fluorescence image obtained from each irradiation.

[0026] Figure 3 is a flowchart of another inspection method of Embodiment 1 according to this disclosure. The primary and secondary determination steps may be performed either by first performing the primary determination step and then the secondary determination step, as shown in Figure 1, or by first performing the secondary determination step and then the primary determination step, as shown in Figure 3.

[0027] In the inspection method of Embodiment 1 described above, by comparing the first and second fluorescence images obtained when multiple reference semiconductor layer structures to be inspected are irradiated simultaneously with the first and second reference fluorescence images obtained when multiple reference semiconductor layer structures

[0028] Next, we will describe the inspection apparatus of Embodiment 1 for implementing the inspection method according to Embodiment 1. The inspection apparatus of Embodiment 1 is an inspection apparatus 100 that irradiates a semiconductor layer structure having a plurality of light-emitting parts including a light-emitting layer with inspection light to determine the quality of the light-emitting parts, and includes an irradiation unit 112 that irradiates the semiconductor layer structure with inspection light whose irradiation intensity can be adjusted; an irradiation control unit 124 that controls the irradiation unit 112 so that a first inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a first irradiation intensity, and a second inspection light having a shorter wavelength than the light emitted by the light-emitting layer is irradiated onto the semiconductor layer structure at a second irradiation intensity lower than the first irradiation intensity; an image acquisition unit 111 that acquires a first fluorescence image of the semiconductor layer structure obtained by irradiation with the first inspection light and acquires a second fluorescence image of the semiconductor layer structure obtained by irradiation with the second inspection light; and a determination unit 121 that determines the quality of each light-emitting part based on the first fluorescence image and the second fluorescence image. Here, the irradiation unit 112 may be capable of adjusting not only the irradiation intensity but also the wavelength of the inspection light.

[0029] Figure 2 is a block diagram showing the configuration of the inspection device 100, which includes an inspection unit 110 including an irradiation unit 112 and an image acquisition unit 111, a control unit 120 including an irradiation control unit 124 and a determination unit 121, and an output unit 130. The following provides a more detailed explanation.

[0030] The inspection unit 110 includes, in addition to the irradiation unit 112 and the image acquisition unit 111, a support unit 113 for which an inspection sample is placed. The irradiation unit 112 includes, for example, one or more light sources that irradiate the semiconductor layer structure to be inspected with inspection light. The light sources can be, for example, light-emitting diodes, laser diodes, excimer light sources, etc., that irradiate the entire semiconductor layer structure placed on the support unit 113 with light having a certain spread. If the light emitted by the light-emitting layer is visible light, for example, the light from the light source can be light having an emission peak wavelength of 405 nm, which is close to the wavelength of visible light. If there are two or more irradiation units 112, they may be located in different positions. Each irradiation unit 112 includes multiple light sources that switch between emitting a first inspection light and a second inspection light, and the semiconductor layer structure to be irradiated may be irradiated with the first inspection light or the second inspection light from different directions. Furthermore, the first and second inspection lights may be light of the same wavelength.

[0031] The image acquisition unit 111 is, for example, a camera provided opposite the support unit 113. The image acquisition unit 111 can acquire (photograph) a first fluorescence image formed on the surface of the semiconductor layer structure by the emission of light from a light-emitting unit excited by irradiation with a first inspection light, and a second fluorescence image formed on the surface of the semiconductor layer structure by the emission of light from a light-emitting unit excited by irradiation with a second inspection light.

[0032] Figure 2 illustrates a wafer 115 having multiple semiconductor layer structures as the object of inspection. When the object of inspection is a wafer 115, for example, the light source of the irradiation unit 112 is positioned to irradiate the entire wafer 115 with light, and the inspection light is irradiated onto the multiple semiconductor layer structures simultaneously. As a result, the image acquisition unit 111 can acquire a first fluorescence image or a second fluorescence image from the multiple semiconductor layer structures.

[0033] The control unit 120 includes, in addition to the irradiation control unit 124 and the determination unit 121, for example, an image acquisition control unit 122 and a storage unit 123. The irradiation control unit 124 controls one or more of the following: the light emission intensity of the light source, the distance between the light source and the semiconductor layer structure to be irradiated, the light distribution characteristics emitted from the light source, and the emission angle relative to the surface of the semiconductor layer structure, thereby causing the irradiation unit 112 to emit inspection light (first or second inspection light) so that the inspection light is irradiated onto the semiconductor layer structure at a predetermined irradiation intensity (first or second irradiation intensity). Furthermore, if the object to be inspected is a wafer 115, for example, the irradiation unit 112 is controlled so that the inspection light (first or second inspection light) is irradiated onto the entire surface of the wafer 115 at a predetermined irradiation intensity (first or second irradiation intensity) while reducing irradiation unevenness. It goes without saying that the irradiation control of the first and second inspection lights by the irradiation control unit 124 is performed with a delay, not simultaneously. When controlling the irradiation of the first or second inspection light, it is preferable to irradiate at predetermined intervals, taking into account the fluorescence characteristics of the light-emitting part of the semiconductor layer structure. For example, when irradiating with the first inspection light first, it is preferable to irradiate with the second inspection light after the fluorescence caused by the irradiation of the first inspection light has weakened to a certain extent, which enables high-quality inspection.

[0034] The image acquisition control unit 122 controls the timing at which the image acquisition unit 111 acquires an image, for example, the timing at which the camera shutter is released, based on the timing at which the irradiation control unit 124 emits inspection light from the irradiation unit 112. Normally, the image is acquired by the image acquisition unit 111 a few milliseconds (ms) later, that is, almost simultaneously with the emission of the inspection light. However, if there is a time difference, for example, between the time the inspection light is irradiated onto the semiconductor layer structure and the time the light-emitting unit emits light, and between the time the light-emitting unit emits light and the time it takes for a stable and optimal image to be formed on the surface of the semiconductor layer structure, the image acquisition control unit 122 controls the timing at which the image acquisition unit 111 acquires the image, taking these time differences into consideration.

[0035] The determination unit 121 performs a primary determination of the quality of the semiconductor layer structure based on the first fluorescence image, a secondary determination of the quality of the semiconductor layer structure based on the second fluorescence image, and a tertiary determination of the quality of the semiconductor layer structure based on the primary and secondary determinations. For example, the determination unit 121 determines, for instance, that any light-emitting portion in the first fluorescence image that emits less than a first reference intensity is a defective product (primary determination), and that any light-emitting portion in the second fluorescence image that emits less than a second reference intensity is a defective product (secondary determination). Preferably, the determination unit 121 includes in the secondary determination that any light-emitting portion in the second fluorescence image that emits light at a third reference intensity or higher, which is greater than the second reference intensity, is a defective product, thereby enabling the determination of defects in light-emitting portions that emit abnormal light. Then, based on the primary and secondary determinations, the determination unit 121 performs a tertiary determination of the quality of the semiconductor layer structure by determining that any semiconductor layer structure that has been determined to be good in both the primary and secondary determinations is a good product.

[0036] The first reference intensity, second reference intensity, and third reference intensity are stored, for example, in the memory unit 123, and the determination unit 121 determines whether the image is good or bad by comparing the emission intensity based on the first and second fluorescence images with the first reference intensity, second reference intensity, third reference intensity, etc., stored in the memory unit 123. Alternatively, for example, the result of the first determination can be temporarily stored in the memory unit 123, and after the second determination is completed, a third determination can be made based on the results of the first and second determinations.

[0037] The emission intensity based on the first and second fluorescence images can be compared with the first, second, and third reference intensities, etc., using various methods, such as based on the brightness and contrast of the images. For example, the determination unit 121 determines whether the semiconductor layer structure is good or bad by comparing the brightness, contrast, etc., of the first fluorescence image of the semiconductor layer structure with the first reference fluorescence image obtained when the same light as the first inspection light is irradiated onto a reference semiconductor layer structure that has been determined to be good at a first irradiation intensity. Furthermore, the determination unit 121 determines whether the semiconductor layer structure is good or bad by comparing the brightness, contrast, etc., of the second fluorescence image of the semiconductor layer structure with the second reference fluorescence image obtained when the same light as the second inspection light is irradiated onto a reference semiconductor layer structure that has been determined to be good at the second irradiation intensity.

[0038] The first and second fluorescence images may be images obtained when multiple semiconductor layer structures provided on a single wafer are irradiated simultaneously, for example. In this case, the first reference fluorescence image may be an image obtained when one reference semiconductor layer structure is irradiated, but it is preferable that the same light as the first inspection light is irradiated simultaneously to multiple reference semiconductor layer structures that have been determined to be good products. This makes it possible to configure the system to determine whether multiple semiconductor layer structures formed on a single wafer are good products simultaneously, allowing for more efficient quality determination.

[0039] The output unit 130 outputs the result determined by the determination unit 221. The output unit 130 is, for example, a display.

[0040] According to the inspection apparatus of Embodiment 1 of this disclosure described above, it is possible to provide an inspection apparatus for semiconductor layer structures that can perform inspections efficiently and with high inspection quality.

[0041] [Embodiment 2] The inspection method of Embodiment 2 of the present disclosure is an inspection method for determining the quality of a semiconductor layer structure having a plurality of light-emitting parts including a light-emitting layer, and includes the steps of: preparing a database that stores the correlation between the current value used when determining the quality of a light-emitting part by applying an electric current and the irradiation intensity used when determining the quality by irradiating with inspection light having a shorter wavelength than the light emitted by the light-emitting part; an irradiation intensity acquisition step of obtaining a first irradiation intensity corresponding to the applied current value to be determined by referring to the database; an irradiation step of irradiating the semiconductor layer structure with inspection light at the first irradiation intensity; and a determination step of determining the quality of a light-emitting part based on a fluorescence image of the semiconductor layer structure obtained by the irradiation step. Here, the correlation between the current value used to determine the quality of the light-emitting part and the irradiation intensity used to determine its quality by irradiating it with inspection light refers to the current value and irradiation intensity at which the result of determining the quality of the light-emitting part by applying current matches the result of determining its quality by irradiating it with inspection light.

[0042] The inspection method of Embodiment 2 described above determines the quality of the light-emitting part based on a fluorescence image of the semiconductor layer structure. Therefore, quality can be determined without applying current, or in other words, without using a probe for applying current, and quality can be determined efficiently. Furthermore, the inspection method of Embodiment 2 determines the quality of the light-emitting part based on the correlation between the current value used when determining the quality of the light-emitting part by applying current and the irradiation intensity used when determining the quality by irradiating it with inspection light of a shorter wavelength than the light emitted by the light-emitting part. Therefore, it is possible to determine the quality of the light-emitting part with the same detection accuracy as when applying current. The following describes each step of the inspection method according to Embodiment 2 in detail with reference to the drawings. Here, the inspection method of Embodiment 2, as described above, includes a database preparation step S610, an irradiation intensity acquisition step S620, an irradiation step S630, and a determination step S640, as shown in the flowchart of Figure 4. Figure 5 is a flowchart of the database preparation step S610.

[0043] <Database preparation step S610> In the database preparation step S610, as described above, a database is prepared that stores the correlation between the current value used to determine the quality of the light-emitting part by applying current and the irradiation intensity used to determine the quality of the part by irradiating it with inspection light of a shorter wavelength than the light emitted by the light-emitting part. The database preparation step S610 includes the variety selection step S611, the current application measurement step S612, the photoexcitation measurement step S613, and the data storage step S614, as shown in Figure 5.

[0044] First, in the variety selection step S611, the semiconductor layer structure of the light-emitting element to be inspected is selected. Next, in the current application measurement step S612, for example, a quality determination is made when current is applied to the selected semiconductor layer structure. In addition, a quality determination is made when current is applied to multiple semiconductor layer structures provided on the wafer. When determining the quality of multiple semiconductor layer structures, the probe is moved and current is applied. For example, a constant current of 1 mA or less, or 1 / 100th or less of the rated current set for each product type, is applied to the semiconductor layer structure, and the voltage of each semiconductor layer structure is measured. Then, for example, those that meet the threshold voltage (which may have a certain allowable range) set for the selected semiconductor layer structure are determined to be good products, and those below the threshold voltage are determined to be defective products.

[0045] Next, in the photoexcitation measurement step S613, the semiconductor layer structures determined to be good and those determined to be defective in the current application measurement step S612 are irradiated with inspection light of a shorter wavelength than the light emitted by the light-emitting part, while varying the irradiation intensity. Then, fluorescence emission at each irradiation intensity is confirmed, and (i) the irradiation intensity of the inspection light that allows the semiconductor layer structures determined to be good in the current application measurement to be determined to be defective, and (ii) fluorescence images of the good and defective products at the said irradiation intensity are obtained.

[0046] Furthermore, for example, if a pass / fail judgment is performed by applying current to each of the multiple semiconductor layer structures provided on a wafer, the optimal irradiation intensity of the inspection light for pass / fail judgment by light irradiation can be determined as follows. Specifically, the multiple semiconductor layer structures provided on the wafer, which have been judged for pass / fail judgment by current application, are all irradiated with inspection light at once, and fluorescence images of the multiple semiconductor layer structures are acquired at once. Then, the fluorescence images of each semiconductor layer structure in the acquired image are matched with the pass / fail judgment for each semiconductor layer structure based on the positional information of each semiconductor layer structure, and the irradiation intensity of the inspection light that matches the pass / fail judgment by current application can be set as the irradiation intensity suitable for pass / fail judgment.

[0047] Then, in the data storage step S614, the irradiation intensity and fluorescence image at the irradiation intensity, which are correlated with the quality determination of the light-emitting part by current application and are used to determine quality by irradiation with inspection light of a shorter wavelength than the light emitted by the light-emitting part, are stored in the database. Specifically, (i) the irradiation intensity of the inspection light that can determine semiconductor layer structures that have been determined to be good by current application measurement as good products and semiconductor layer structures that have been determined to be defective products, and (ii) the fluorescence image of good products and fluorescence image of defective products at the said irradiation intensity are stored in the database. Here, the fluorescence image of good products and fluorescence image of defective products in (ii) are reference fluorescence images used as the basis for quality determination. The reference fluorescence image may also be an image obtained when the same light used in the irradiation step is irradiated simultaneously onto multiple reference semiconductor layer structures that have been determined to be good products by current application.

[0048] Furthermore, in step S615, the system checks for any other varieties that should be added to the database. If there are other varieties, steps S611 to S614 are repeated to add them to the database. If there are no other varieties that should be added to the database, the database preparation is completed.

[0049] <Irradiation intensity acquisition step S620> In the irradiation intensity acquisition step S620, the irradiation intensity corresponding to the applied current value used to determine the quality of the semiconductor layer structure being inspected is acquired by referring to the database.

[0050] <Irradiation step S630> In irradiation step S630, the inspection light is irradiated onto the semiconductor layer structure at the specified irradiation intensity.

[0051] <Decision step S640> In the determination step S640, a fluorescence image of the semiconductor layer structure obtained by irradiation with inspection light is acquired, and the quality of the light-emitting part is determined based on the acquired fluorescence image of the semiconductor layer structure while referring to the database. For example, in the determination step S640, (i) Fluorescence image of semiconductor layer structure, (ii) The reference fluorescence image obtained when the same light used for the inspection in the irradiation step is irradiated onto a reference semiconductor layer structure that has been determined to be good by applying an electric current, The quality of the light-emitting part is determined by comparing the two. The database stores the correlation between multiple current values ​​used to determine the quality of a semiconductor layer structure by applying current, and multiple irradiation intensities corresponding to each current value. The irradiation intensity acquisition step, irradiation step, and determination step may be performed with multiple irradiation intensities. For example, an irradiation step may be performed in which an inspection light is irradiated onto the semiconductor layer structure at the second irradiation intensity, using a second irradiation intensity smaller than the first irradiation intensity, and a determination step may be performed in which the quality of the light-emitting part is determined based on the fluorescence image of the semiconductor layer structure obtained in the irradiation step. Alternatively, an irradiation step may be performed in which an inspection light is irradiated onto the semiconductor layer structure at the second irradiation intensity, using a second irradiation intensity larger than the first irradiation intensity, and a determination step may be performed in which the quality of the light-emitting part is determined based on the fluorescence image of the semiconductor layer structure obtained in the irradiation step.

[0052] According to the inspection method of Embodiment 2 described above, since the quality of the light-emitting part is determined based on the fluorescence image of the semiconductor layer structure, quality can be determined without applying current, in other words, without using a probe for applying current, and quality can be determined efficiently. Furthermore, according to the inspection method of Embodiment 2, the quality of the light-emitting part is determined based on the correlation between the current value used when determining the quality of the light-emitting part by applying current and the irradiation intensity used when determining the quality by irradiating it with inspection light of a shorter wavelength than the light emitted by the light-emitting part. Therefore, the quality of the light-emitting part can be determined with the same detection accuracy as when applying current.

[0053] Next, we will describe an inspection apparatus for carrying out the inspection method of Embodiment 2.

[0054] The inspection apparatus of this second embodiment, An inspection device 200 for determining the quality of a semiconductor layer structure having multiple light-emitting parts including a light-emitting layer, A database 240 that stores the correlation between the current value used to determine the quality of the light-emitting part by applying an electric current and the irradiation intensity used to determine the quality by irradiating with inspection light of a shorter wavelength than the light emitted by the light-emitting layer, An irradiation unit 112 that irradiates the semiconductor layer structure with inspection light, An irradiation control unit 224 obtains an irradiation intensity corresponding to the applied current value to be judged as good or bad by referring to a database, controls the emission intensity of the inspection light so that the inspection light of the obtained irradiation intensity is irradiated onto the semiconductor layer structure, and irradiates the semiconductor layer structure with inspection light from the irradiation unit. An image acquisition unit 111 acquires a fluorescence image of the semiconductor layer structure by irradiation with inspection light, A determination unit 221 determines the quality of the semiconductor layer structure based on the acquired fluorescence image and outputs the determination result as the determination result of the semiconductor layer structure at the applied current value. Includes.

[0055] The inspection apparatus of Embodiment 2 will be described in detail below. Figure 6 is a block diagram showing the configuration of the inspection device 200, which includes an inspection unit 110, a control unit 220, a database 240, and an output unit 130. Here, the inspection unit and output unit are configured similarly to the inspection unit 110 and output unit 130 of the inspection apparatus 100 of Embodiment 1, and are indicated in Figure 6 with the same reference numerals as in Figure 2. Also in Figure 6, a wafer 115 having multiple semiconductor layer structures is shown as the object to be inspected.

[0056] Database 240 stores reference fluorescence images obtained when the same light emitted by the irradiation unit 112 is irradiated onto a reference semiconductor layer structure that has been determined to be a good product by applying an electric current. Database 240 stores, for each variety, the current value used to determine the quality of the light-emitting part by applying an electric current, and the irradiation intensity used to determine the quality by irradiating with inspection light of a shorter wavelength than the light emitted by the light-emitting part, which matches the quality determination result based on the current value, along with a reference fluorescence image. Furthermore, if the reference fluorescence image is an image that includes fluorescence images of multiple semiconductor layer structures provided on the wafer, the database 240 stores, for each product type, the current value used when determining the quality of the light-emitting part by applying current, the irradiation intensity used when determining the quality by irradiating with inspection light of a shorter wavelength than the light emitted by the light-emitting part, which matches the quality determination result based on the current value, the reference fluorescence image, and the positional information of each semiconductor layer structure on the wafer.

[0057] The inspection unit 110 is configured in the same manner as in Embodiment 1, as described above, and therefore its explanation will be omitted.

[0058] The control unit 220 includes an irradiation control unit 224, a determination unit 221, and an image acquisition control unit 222. The irradiation control unit 224 obtains the irradiation intensity of the inspection light to be irradiated onto the semiconductor layer structure (light-emitting element) to be inspected from the database 240, and controls the irradiation unit 112 so that the inspection light is irradiated onto the semiconductor layer structure with the obtained irradiation intensity. For example, the irradiation control unit 224 controls one or more of the following: the emission intensity of the light source, the distance between the light source and the semiconductor layer structure to be irradiated, the light distribution characteristics emitted from the light source, the emission angle relative to the surface of the semiconductor layer structure, etc., to cause the irradiation unit 112 to emit inspection light so that the inspection light is irradiated onto the semiconductor layer structure with a predetermined irradiation intensity. Also, if the object to be inspected is a wafer 115, for example, the irradiation unit 112 is controlled so that the inspection light is irradiated onto the entire surface of the wafer 115 with a predetermined irradiation intensity and with reduced irradiation unevenness.

[0059] The image acquisition control unit 222 controls the image acquisition timing of the image acquisition unit 111, for example, the timing of the camera shutter release, based on the timing at which the irradiation control unit 224 emits inspection light from the irradiation unit 112. Normally, the image is acquired by the image acquisition unit 111 a few milliseconds (ms) later, that is, almost simultaneously with the emission of the inspection light. However, if there is a time difference, for example, between the time the inspection light is irradiated onto the semiconductor stacked structure and the time difference between the time the light-emitting unit emits light and the time difference between the time the light-emitting unit emits light and the time difference until a stable and optimal image is formed on the surface of the semiconductor stacked structure, the image acquisition timing of the image acquisition unit 111 is controlled taking these time differences into consideration.

[0060] The determination unit 221 determines the quality of the semiconductor layer structure based on the fluorescence image acquired by the image acquisition control unit 222. For example, the determination unit 221 determines the quality of the semiconductor layer structure by comparing the fluorescence image of the semiconductor layer structure obtained by irradiating it with inspection light by the irradiation unit 112 with a reference fluorescence image stored in the database 240.

[0061] The comparison between the fluorescence image and the reference fluorescence image for determining whether a product is good or bad can be performed in various ways. For example, the brightness and contrast of the fluorescence image of the semiconductor layer structure can be compared with the brightness and contrast of the reference fluorescence image. If the difference in brightness and contrast is within a predetermined range, the product is determined to be good. If the brightness, etc., of the fluorescence image of the semiconductor layer structure is lower than the predetermined range, the product is determined to be defective. Alternatively, the determination unit 221 may determine that a product is good if the emission intensity calculated based on the brightness, etc., of the fluorescence image is greater than a first reference intensity calculated based on the brightness, etc., of the reference fluorescence image, and that a product is defective if it is smaller.

[0062] The fluorescence image may be, for example, an image obtained when multiple semiconductor layer structures provided on a single wafer are irradiated simultaneously. In this case, the reference fluorescence image may be an image obtained when one reference semiconductor layer structure is irradiated simultaneously, but it is preferable that the same light as the inspection light is irradiated simultaneously to multiple reference semiconductor layer structures that have been determined to be good products.

[0063] In the inspection apparatus 200 of Embodiment 2 configured as described above, the database stores the correlation between multiple current values ​​used to determine the quality of the semiconductor layer structure by applying current, and multiple irradiation intensities corresponding to each current value. The determination unit 221 can then determine the quality of the semiconductor layer structure at multiple current values. In the inspection device 200, for example, the irradiation control unit 224 controls the irradiation unit 112 to irradiate multiple semiconductor layer structures simultaneously with the acquired irradiation intensity of the inspection light, and the irradiation unit 112 irradiates multiple semiconductor layer structures simultaneously with the acquired irradiation intensity of the inspection light. The image acquisition unit 111 acquires a fluorescence image containing multiple fluorescence emissions from multiple semiconductor layer structures by simultaneously irradiating them with inspection light. The determination unit 221 then determines the quality of multiple semiconductor layer structures based on a fluorescence image containing multiple fluorescence particles.

[0064] In the inspection device 200, when inspection light is irradiated onto multiple semiconductor layer structures simultaneously to acquire a fluorescence image containing multiple fluorescence, it is preferable that the determination unit 221 determines the quality of the multiple semiconductor layer structures by comparing the fluorescence image with a reference fluorescence image containing fluorescence emitted by multiple reference semiconductor layer structures obtained when the same light as the inspection light is irradiated onto multiple reference semiconductor layer structures that have been determined to be good by applying an electric current. [Explanation of symbols]

[0065] 100, 200 inspection devices 110 Inspection Department 111 Image acquisition unit 112 Irradiation area 113 Support part 115 wafers 120, 220 Control Unit 121, 221 Judgment section 122, 222 Image acquisition control unit 123 Storage section 124, 224 Irradiation control unit 130 Output section 240 databases

Claims

1. A method for determining the quality of a semiconductor layer structure comprising multiple light-emitting parts including a light-emitting layer, The steps include: preparing a database that stores the correlation between the current value used to determine the quality of the light-emitting part by applying an electric current and the irradiation intensity used to determine the quality of the part by irradiating it with inspection light of a shorter wavelength than the light emitted by the light-emitting part, and the results of determining quality. An irradiation intensity acquisition step involves obtaining a first irradiation intensity corresponding to the applied current value to be judged as good or bad by referring to the aforementioned database, An irradiation step of irradiating the semiconductor layer structure with the inspection light at the first irradiation intensity, A determination step in which the quality of the light-emitting portion is determined based on the fluorescence image of the semiconductor layer structure obtained by the irradiation step, including, A method for inspecting the structure of semiconductor layers.

2. In the determination step, (i) The fluorescence image of the semiconductor layer structure, (ii) The reference fluorescence image obtained when the same light used for the inspection in the irradiation step is irradiated onto a reference semiconductor layer structure that has been determined to be good by applying an electric current, The quality of the light-emitting part is determined by comparing the following: A method for inspecting a semiconductor layer structure according to claim 1.

3. In the step of preparing the database, a plurality of irradiation intensities having a correlation relationship in which a plurality of current values ​​and a pass / fail judgment result match are stored in the database, In the irradiation intensity acquisition step, two or more first irradiation intensities corresponding to the applied current values ​​to be judged as good or bad are acquired. In the irradiation step, the semiconductor layer structure is irradiated with a first irradiation intensity corresponding to each of the two or more first irradiation intensities obtained in the irradiation intensity acquisition step. In the determination step, the quality of the light-emitting part is determined based on the fluorescence images acquired in the irradiation step corresponding to the two or more first irradiation intensities. A method for inspecting a semiconductor layer structure according to claim 1 or 2.

4. The aforementioned reference fluorescence image is an image obtained when the same light used for the inspection light irradiated in the irradiation step is simultaneously irradiated onto multiple reference semiconductor layer structures that have been determined to be good products by applying an electric current. A method for inspecting a semiconductor layer structure according to claim 2.

5. An inspection device for determining the quality of a semiconductor layer structure having multiple light-emitting parts including a light-emitting layer, A database that stores the correlation between the current value used to determine the quality of the light-emitting part by applying an electric current and the irradiation intensity used to determine the quality by irradiating it with inspection light of a shorter wavelength than the light emitted by the light-emitting layer, and the quality determination result matching the current value used to determine the quality of the light-emitting part. An irradiation unit that irradiates the semiconductor layer structure with the aforementioned inspection light, An irradiation control unit that, by referring to the database, obtains an irradiation intensity corresponding to the applied current value to be judged as good or bad, controls the emission intensity of the inspection light so that the inspection light of the obtained irradiation intensity is irradiated onto the semiconductor layer structure, and irradiates the semiconductor layer structure with the inspection light from the irradiation unit, An image acquisition unit that acquires a fluorescence image of the semiconductor layer structure by irradiation with the aforementioned inspection light, A determination unit that determines the quality of the semiconductor layer structure based on the acquired fluorescence image and outputs the determination result of the semiconductor layer structure at the applied current value, including, A device for inspecting semiconductor layer structures.

6. The aforementioned database stores reference fluorescence images obtained when the same light as the inspection light emitted by the irradiation unit is irradiated onto a reference semiconductor layer structure that has been determined to be a good product by applying an electric current. The semiconductor layer structure inspection apparatus according to claim 5, wherein the determination unit determines whether the semiconductor layer structure is good or bad by comparing the fluorescence image of the semiconductor layer structure with the reference fluorescence image.

7. The determination unit outputs the determination result of the semiconductor layer structure at the plurality of current values. An inspection apparatus for semiconductor layer structures according to claim 5 or 6.

8. The irradiation unit irradiates the plurality of semiconductor layer structures simultaneously with the inspection light at the acquired irradiation intensity. The image acquisition unit acquires a fluorescence image including multiple fluorescence emitted by each of the multiple semiconductor layer structures by simultaneous irradiation with the inspection light. The determination unit determines the quality of the plurality of semiconductor layer structures based on the fluorescence image containing the plurality of fluorescence. An inspection apparatus for semiconductor layer structures according to any one of claims 5 to 7.

9. In the determination unit, A fluorescence image containing the aforementioned plurality of fluorescence, When the same light as the inspection light emitted from the aforementioned irradiation unit is simultaneously irradiated onto multiple reference semiconductor layer structures that have been determined to be good products by applying an electric current, a reference fluorescence image including the fluorescence emitted by the multiple reference semiconductor layer structures is obtained, The quality of the multiple semiconductor layer structures is determined by comparing them. The apparatus for inspecting semiconductor layer structures according to claim 8.

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