JP2024059753A - Method and apparatus for inspecting semiconductor layer structure - Google Patents

Abstract

[Problem] To provide a method and an apparatus for inspecting a semiconductor layer structure by irradiating light, which allows efficient inspection and high inspection quality. [Solution] An inspection method for judging the quality of a semiconductor layer structure having a plurality of light-emitting sections including a light-emitting layer, comprising: a primary judgment 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 judgment of the quality of the light-emitting sections based on a fluorescent image of the semiconductor layer structure acquired by 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 second judgment of the quality of the light-emitting sections based on a fluorescent image of the semiconductor layer structure acquired by 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 a tertiary judgment step of judging the quality of each light-emitting section based on the primary and secondary judgments. [Selected Figure] Figure 1

Description

This disclosure relates to a method for inspecting a semiconductor layer structure and an apparatus for inspecting a semiconductor layer structure.

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 inspecting their light-emitting characteristics. In general, inspection of the 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, causing a current to flow through the semiconductor layers and cause them to emit light.

However, light emission inspections performed by passing a current require the needles (probes) of a prober to contact the electrodes of each semiconductor light-emitting element, which takes a lot of time. Therefore, as a method for inspecting the light-emitting performance of a semiconductor light-emitting element without passing a current through it, an inspection method has been proposed and considered in which the active layer of the semiconductor light-emitting element is excited by irradiating it with light and the fluorescence emitted from the excited active layer is observed (Patent Documents 1 and 2).

JP 2009-128366 A JP 2013-038313 A

However, while the inspection method of irradiating light to determine the quality of semiconductor light-emitting elements can perform inspections efficiently, there is a demand for improved inspection quality.

The present disclosure therefore aims to provide a method for inspecting a semiconductor layer structure by irradiating light and an inspection device for the semiconductor layer structure, which allows for efficient inspection and high inspection quality.

In order to achieve the above object, a semiconductor layer structure inspection method according to one embodiment of the present disclosure is an inspection method for determining the quality of a semiconductor layer structure having a plurality of light-emitting portions 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 performing a primary determination of the quality of the light-emitting portion based on a first fluorescent image of the semiconductor layer structure obtained by irradiating 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 performing a secondary determination of the quality of the light-emitting portion based on a second fluorescent image of the semiconductor layer structure obtained by irradiating the second inspection light, and a tertiary determination step of determining the quality of each light-emitting portion based on the primary determination and the secondary determination.

A semiconductor layer structure inspection device according to one embodiment of the present disclosure is an inspection device that irradiates inspection light onto a semiconductor layer structure having a plurality of light-emitting units including a light-emitting layer to determine the quality of the light-emitting units, and includes an irradiation unit that irradiates the semiconductor layer structure with inspection light having an adjustable irradiation intensity and wavelength, 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 control unit that controls the irradiation unit so that 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 fluorescent image of the semiconductor layer structure obtained by irradiation with the first inspection light, and acquires a second fluorescent 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 unit based on the first fluorescent image and the second fluorescent image.

Another embodiment of the semiconductor layer structure inspection method according to the present disclosure is an inspection method for determining the quality of a semiconductor layer structure having a plurality of light-emitting sections including a light-emitting layer, and includes the steps of: preparing a database that stores a correlation between a current value when determining the quality of the light-emitting sections by applying a current and an irradiation intensity when determining the quality of the light-emitting sections by irradiating inspection light having a shorter wavelength than the light emitted by the light-emitting sections; an irradiation intensity acquisition step of acquiring a first irradiation intensity corresponding to the applied current value for which the quality is to be determined by referring to the database; an irradiation step of irradiating the inspection light to the semiconductor layer structure at the first irradiation intensity; and a determination step of determining the quality of the light-emitting sections based on a fluorescent image of the semiconductor layer structure obtained by the irradiation step.

Another embodiment of the semiconductor layer structure inspection device according to the present disclosure is an inspection device for determining the quality of a semiconductor layer structure having a plurality of light-emitting units including a light-emitting layer, and includes a database storing a correlation between a current value when determining the quality of the light-emitting units by applying a current and an irradiation intensity when determining the quality of the light-emitting units by irradiating inspection light having a shorter wavelength than the light emitted by the light-emitting layer, an irradiation unit that irradiates the inspection light to the semiconductor layer structure, a control unit that refers to the database to obtain an irradiation intensity corresponding to the applied current value for which the quality is to be determined, controls the emission intensity of the inspection light so that the semiconductor layer structure is irradiated with the inspection light of the obtained irradiation intensity, and causes the irradiation unit to irradiate the inspection light to the semiconductor layer structure, an image acquisition unit that acquires a fluorescent image of the semiconductor layer structure by irradiation with the inspection light, and a judgment unit that judges the quality of the semiconductor layer structure based on the acquired fluorescent image and outputs the judgment result as a judgment result of the semiconductor layer structure at the applied current value.

The semiconductor layer structure inspection method and inspection device disclosed herein, configured as described above, can provide a semiconductor layer structure inspection method and inspection device that uses light irradiation to perform efficient inspection and have high inspection quality.

1 is a flowchart of an inspection method according to a first embodiment of the present disclosure. 1 is a configuration diagram illustrating an inspection device according to a first embodiment. 11 is a flowchart of another inspection method according to the first embodiment of the present disclosure. 11 is a flowchart of an inspection method according to a second embodiment of the present disclosure. 13 is a flowchart of a database preparation step in the inspection method of the second embodiment. FIG. 11 is a configuration diagram illustrating an inspection device according to a second embodiment.

Hereinafter, an inspection method and an inspection device 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 light of different irradiation intensities is irradiated, the pass/fail of the light-emitting part is judged in the fluorescence image obtained by each irradiation, and the light-emitting part judged to be a pass/fail part in both pass/fail judgments is judged to be a pass/fail part, and is based on the following findings.

That is, in pass/fail judgment based on a fluorescent image, if the brightness of the fluorescent light is low, the light-emitting part is judged to be defective. However, there are cases where a light-emitting part that is judged to be a pass when irradiated with inspection light at a weak irradiation intensity is judged to be defective when irradiated with inspection light at a strong irradiation intensity. Therefore, when the irradiation intensity of the inspection light was increased, it was found that, conversely, a light-emitting part that was judged to be a defective part when irradiated with inspection light at a weak irradiation intensity was sometimes judged to be a pass when irradiated with inspection light at a strong irradiation intensity.
The above-mentioned findings are findings that the present inventors have independently discovered, and the inspection method of embodiment 1 according to the present disclosure has been made based on the above-mentioned findings that the present inventors have independently discovered.
The inspection method and inspection device of the first embodiment will be described in detail below.

FIG. 1 is a flowchart of an inspection method according to a first embodiment of the present disclosure.
The inspection method of the first embodiment is an inspection method for determining the quality of a semiconductor layer structure having a plurality of light-emitting portions including a light-emitting layer, and includes a primary judgment step S510, a secondary judgment step S520, and a tertiary judgment step S530, as shown in Fig. 1. Here, in particular, the primary judgment step S510 irradiates a first inspection light having a shorter wavelength than the light emitted by the light-emitting layer at a first irradiation intensity, and determines the quality of the light-emitting portion based on a first fluorescent image obtained by the irradiation, and the secondary judgment step S520 irradiates 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 determines the quality of the light-emitting portion based on a second fluorescent image obtained by the irradiation.
Then, in the tertiary judgment step S530, the light-emitting portion judged as non-defective in both the primary judgment step S510 and the secondary judgment step S520 is judged as non-defective.
This makes it possible to provide a method for inspecting a semiconductor layer structure by irradiating light, which allows efficient inspection and high inspection quality.

More specifically, in the inspection method of the first embodiment, the primary judgment step S510 includes a first irradiation step S511 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, a first fluorescence image acquisition step S512 of acquiring an image (first fluorescence image) formed by the fluorescence emitted by the light-emitting portion excited by the irradiation of the first inspection light, and a first judgment step S513 of judging the quality of the light-emitting portion based on the acquired first fluorescence image, as shown in FIG. 1. The secondary judgment step S520 also includes a second irradiation step S521 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, a second fluorescence image acquisition step S522 of acquiring an image (second fluorescence image) formed by the fluorescence emitted by the light-emitting portion excited by the irradiation of the second inspection light, and a second judgment step S523 of judging the quality of the light-emitting portion based on the acquired second fluorescence image. Then, in the tertiary judgment step S530, the light-emitting section that was judged to be good in both the primary judgment step S510 and the secondary judgment step S520 is judged to be good.

<First Irradiation Step S511, Second Irradiation Step S521>
The first inspection light in the first irradiation step S511 of the primary judgment step S510 and the second inspection light in the second irradiation step S521 of the secondary judgment step S520 are light having a shorter wavelength than the light emitted by the light-emitting layer. For example, when the light emitted by the light-emitting layer is visible light, light having an emission peak wavelength of 405 nm, which is close to visible light, is used for the first inspection light and the second inspection light. The wavelengths of the first inspection light and the second inspection light may be the same or different. If the wavelengths of the first inspection light and the second inspection light are the same, the configuration of the irradiation unit in the inspection device described below can be simplified.
A semiconductor layer structure is a layer of multiple semiconductors, for example, a part of a light emitting element. A light emitting layer is a layer of the semiconductor layer structure that emits light. A specific example of the semiconductor layer structure is a nitride semiconductor, such as In _x Al _y Ga _1-x-y N (0≦X≦1, 0≦Y≦1). The same is true for the light emitting layer.

In addition, the first irradiation intensity of the first inspection light in the first irradiation step S511 is preferably set to a range of the same intensity that reproduces the luminescence phenomenon caused by the first current application, more preferably to a range of irradiation intensity equivalent to the first applied current value. A preferred 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. The second irradiation intensity of the second inspection light in the second irradiation step S521 is preferably set to a range of the same intensity that reproduces the luminescence phenomenon caused by the second current application, more preferably to a range of irradiation intensity equivalent to the second applied current value. A preferred 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 . By setting the first irradiation intensity and the second irradiation intensity within the above range, defects that were not detected in the primary judgment step S510 can be detected in the secondary judgment step S520, and defects that cannot be detected in the secondary judgment step S520 can be detected in the primary judgment step S510.

<First Image Acquiring Step S512, Second Image Acquiring 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 portion is excited by irradiation with the first inspection light to emit fluorescence and the light is emitted from the semiconductor layer structure. For example, the first fluorescence image includes information on contrast, which is an index of brightness that changes depending on the brightness and position, corresponding to the intensity of the fluorescent emission. 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 portion is excited by irradiation with the second inspection light to emit fluorescence and the light is emitted from the semiconductor layer structure. For example, the second fluorescence image includes information on contrast, which is an index of brightness that changes depending on the brightness and position, corresponding to the intensity of the fluorescent emission.

<First Determination Step S513, Second Determination Step S523>
The first judgment step S513 of the primary judgment step S510 includes judging a light-emitting portion whose emission in the first fluorescent image is smaller than a first reference intensity to be defective. The first reference intensity is set based on an image obtained by fluorescent emission when a reference semiconductor layer structure having the same configuration as the semiconductor layer structure to be judged and recognized as a good product by a pass/fail judgment by applying a current is irradiated with a first inspection light at a first irradiation intensity. Here, the first reference intensity is, for example, a peak value of emission intensity calculated based on the highest brightness in the image, an average value of emission intensity calculated based on an average value of brightness in the image, or the like. The first reference intensity may include both the peak value of emission intensity and the average value of emission intensity calculated based on the average value of brightness in the image.

The second judgment step S523 of the secondary judgment step S520 includes judging a light-emitting portion whose light emission in the second fluorescent image is smaller than a second reference intensity different from the first reference intensity as a defective product. The second reference intensity, like the first reference intensity, is set based on an image formed by fluorescent light emission when a reference semiconductor layer structure that has the same configuration as the semiconductor layer structure to be judged and is recognized as a good product by a pass/fail judgment by applying a current is irradiated with a second inspection light at a second irradiation intensity. Here, the second reference intensity is, for example, a peak value of the light emission intensity calculated based on the highest brightness in the image, an average value of the light emission intensity calculated based on the average value of the brightness in the image, or the like. The second reference intensity may include both the peak value of the light emission intensity and the average value of the light 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 a non-defective product by applying a current in a conventional semiconductor layer structure inspection. As will be described later, this reference semiconductor layer structure is inspected by applying a current and determined to be a non-defective product, but a reference semiconductor layer structure may be prepared in advance, and specifically, a purchased reference semiconductor layer structure that has been determined to be a non-defective product may be prepared.
Moreover, the second judgment step S523 of the secondary judgment step S520 preferably includes judging a light-emitting portion in which light emission of a third reference intensity or more, which is greater than the second reference intensity, is confirmed in the second fluorescent image as being defective. This makes it possible to judge a semiconductor layer structure including a strong light-emitting portion that emits abnormally strong light as being defective, in addition to judging a light-emitting portion with a weak light-emitting intensity as being defective. The strong light-emitting portion refers to a light-emitting portion that can be observed by irradiating a defective portion of a semiconductor, such as a so-called pit structure, with excitation light.

In the first judgment step S513 of the primary judgment step S510, the pass/fail judgment may be made by comparing a first fluorescence image of the semiconductor layer structure to be inspected with a first reference fluorescence image obtained when a reference semiconductor layer structure judged to be a pass/fail product is irradiated with the same light as the first inspection light at a first irradiation intensity. Also, in the second judgment step S523 of the secondary judgment step S520, the pass/fail judgment may be made by comparing a second fluorescence image of the semiconductor layer structure to be inspected with a second reference fluorescence image obtained when a reference semiconductor layer structure judged to be a pass/fail product is irradiated with the same light as the second inspection light at a second irradiation intensity. This allows for efficient inspection of the semiconductor layer structure with high inspection quality.

The first reference fluorescence image may be an image obtained when multiple reference semiconductor layer structures that have been determined to be good products are irradiated with the same light as the first inspection light all at once. When the first reference fluorescence image including images of the multiple reference semiconductor layer structures is used, it is possible to efficiently determine the pass/fail status of the multiple reference semiconductor layer structures all at once by comparing it with, for example, a fluorescence image including images of the multiple semiconductor layer structures to be inspected.
In addition, the second reference fluorescence image may be an image obtained when multiple reference semiconductor layer structures that have been determined to be good are irradiated with the same light as the second inspection light all at once. By using the second reference fluorescence image including images of the multiple reference semiconductor layer structures, it is possible to efficiently determine the pass/fail status of the multiple reference semiconductor layer structures all at once by comparing it with, for example, a fluorescence image including images of the multiple semiconductor layer structures that are the subject of inspection.

Here, the first reference fluorescence image and the second reference fluorescence image including images obtained when multiple reference semiconductor layer structures are irradiated at once, and the first fluorescence image and the second fluorescence image including images obtained when multiple reference semiconductor layer structures to be inspected are irradiated at once, are images obtained, for example, by irradiating inspection light onto an entire wafer on which multiple reference semiconductor layer structures are formed.
In addition, in the tertiary judgment step, an item that is judged as a good item in the primary judgment step and also judged as a good item in the secondary judgment step is judged as a good item. An item that is judged as a defective item in either the primary judgment step or the secondary judgment step is judged as a defective item in the tertiary judgment step.

The inspection method of embodiment 1 according to the present disclosure described above irradiates inspection light with different irradiation intensities in the primary judgment step S510 and the secondary judgment step S520, and judges the quality of the light-emitting part based on the fluorescent image obtained by each irradiation, so that it is possible to provide an inspection method for semiconductor layer structures that can perform inspection efficiently and has high inspection quality.

Also, FIG. 3 is a flowchart of another inspection method according to embodiment 1 of the present disclosure. The primary judgment step and the secondary judgment step may be performed first, as shown in FIG. 1, and then the secondary judgment step, or may be performed first, as shown in FIG. 3, and then the primary judgment step.

In the inspection method of the first embodiment of the present disclosure described above, the first and second fluorescent images obtained when the multiple reference semiconductor layer structures to be inspected are irradiated at once are compared with the first and second reference fluorescent images obtained when the multiple reference semiconductor layer structures are irradiated at once to determine pass/fail, so that, for example, multiple semiconductor layer structures formed on a single wafer can be determined as pass/fail in a batch, enabling more efficient pass/fail determination.

Next, an inspection apparatus according to the first embodiment for carrying out the inspection method according to the first embodiment will be described.
The inspection device of embodiment 1 is an inspection device 100 that irradiates inspection light onto a semiconductor layer structure including a plurality of light-emitting units including a light-emitting layer, and judges the quality of the light-emitting units, and includes: an irradiation unit 112 that irradiates the semiconductor layer structure with inspection light having an adjustable irradiation intensity; an irradiation control unit 124 that controls the irradiation unit 112 so that the semiconductor layer structure is irradiated with first inspection light having a shorter wavelength than the light emitted by the light-emitting layer at a first irradiation intensity, and controls the irradiation unit 112 so that the semiconductor layer structure is irradiated with 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; 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 irradiating with the second inspection light; and a judgment unit 121 that judges the quality of each light-emitting unit based on the first fluorescence image and the second fluorescence image.
Here, the irradiating unit 112 may be capable of adjusting the wavelength of the inspection light in addition to the irradiation intensity.

FIG. 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.
This will be explained in more detail below.

The inspection unit 110 includes, in addition to an irradiation unit 112 and an image acquisition unit 111, a support unit 113 on which an inspection sample is placed, for example.
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 source may be, for example, a light emitting diode, a laser diode, an excimer light source, or the like that irradiates the entire semiconductor layer structure placed on the support unit 113 with light having a certain degree of spread. For example, when the light emitted by the light emitting layer is visible light, the light source may be light having an emission peak wavelength at 405 nm, which is close to the wavelength of visible light.
When the illumination unit 112 includes two or more illumination units 112, the illumination units 112 may be provided at different positions. The illumination unit 112 may include a plurality of light sources that switch between emitting the first inspection light and the second inspection light, and irradiate the semiconductor layer structure that is the illumination target with the first inspection light or the second inspection light from different directions.
Furthermore, the first inspection light and the second inspection light may be light of the same wavelength.

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

Note that FIG. 2 illustrates a wafer 115 having multiple semiconductor layer structures as the inspection object. When the inspection object is the wafer 115, for example, the light source of the irradiation unit 112 is positioned to irradiate the entire wafer 115 with light, and irradiates the multiple semiconductor layer structures with inspection light all at once. This allows the image acquisition unit 111 to acquire a first fluorescent image or a second fluorescent image from the multiple semiconductor layer structures.

The control unit 120 includes, in addition to an irradiation control unit 124 and a 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 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, the emission angle with respect to the surface of the semiconductor layer structure, etc., to emit the inspection light from the irradiation unit 112 so that the inspection light (first or second inspection light) is irradiated to the semiconductor layer structure with a predetermined irradiation intensity (first or second irradiation intensity). Also, when the inspection object is a wafer 115, for example, the irradiation unit 112 is controlled so that the inspection light (first or second inspection light) is irradiated to the entire surface of the wafer 115 with a predetermined irradiation intensity (first or second irradiation intensity) and with reduced irradiation unevenness.
Needless to say, the irradiation control of the first inspection light and the second inspection light by the irradiation control unit 124 is not performed simultaneously but is performed at different times. It is preferable to control the irradiation of the first inspection light or the second inspection light so that the first inspection light or the second inspection light is irradiated at a predetermined interval taking into consideration the fluorescent characteristics of the light emitting portion of the semiconductor layer structure. For example, when the first inspection light is irradiated first, it is preferable to irradiate the second inspection light after the fluorescence due to the irradiation of the first inspection light has weakened to a certain extent, which enables high-quality inspection.

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 causes the irradiation unit 112 to emit inspection light. Normally, the image acquisition unit 111 acquires an image several milliseconds (ms), that is, almost immediately after the inspection light is emitted. However, for example, if there is a time difference between when the inspection light is irradiated onto the semiconductor layer structure and when the light emitting unit emits light, and when a stable, optimal image is formed on the surface of the semiconductor layer structure after the light emitting unit emits light, the image acquisition control unit 122 controls the timing at which the image acquisition unit 111 acquires an image, taking these time differences into consideration.

The judgment unit 121 makes a primary judgment as to whether the semiconductor layer structure is good or bad based on the first fluorescent image, a secondary judgment as to whether the semiconductor layer structure is good or bad based on the second fluorescent image, and a tertiary judgment as to whether the semiconductor layer structure is good or bad based on the primary and secondary judgments.
For example, the determination unit 121 determines, as a defective product, a light-emitting portion whose emission is less than a first reference intensity in the first fluorescent image (primary determination), and determines, as a defective product, a light-emitting portion whose emission is less than a second reference intensity in the second fluorescent image (secondary determination). The determination unit 121 preferably includes, in the secondary determination, determining, as a defective product, a light-emitting portion in which emission of light of a third reference intensity or more that is greater than the second reference intensity is confirmed in the second fluorescent image, thereby making it possible to determine, as a defective product, a light-emitting portion that emits abnormal light. The determination unit 121 then performs a tertiary determination of the quality of the semiconductor layer structure based on the primary determination and the secondary determination, i.e., by determining, as a good product, a semiconductor layer structure that has been determined to be good in both the primary determination and the secondary determination.

The first, second, and third reference intensities are stored, for example, in the memory unit 123, and the judgment unit 121 judges pass/fail by comparing the emission intensity based on the first and second fluorescent images with the first, second, and third reference intensities, etc., stored in the memory unit 123. In addition, for example, the result of the primary judgment can be temporarily stored in the memory unit 123, and after the secondary judgment is completed, a tertiary judgment can be made based on the result of the primary judgment and the result of the secondary judgment.

The comparison of the luminescence intensity based on the first and second fluorescent images with the first reference intensity, the second reference intensity, the third reference intensity, etc. can be performed in various ways, for example, based on the brightness, contrast, etc. of the images.
For example, the determination unit 121 determines the pass/fail status by comparing a first fluorescent image of the semiconductor layer structure with a first reference fluorescent image obtained when a reference semiconductor layer structure determined to be a pass/fail product is irradiated with the same light as the first inspection light at a first irradiation intensity, in terms of image brightness, contrast, etc. Also, the determination unit 121 determines the pass/fail status by comparing a second fluorescent image of the semiconductor layer structure with a second reference fluorescent image obtained when a reference semiconductor layer structure determined to be a pass/fail product is irradiated with the same light as the second inspection light at the second irradiation intensity, in terms of image brightness, contrast, etc.

The first and second fluorescent images may be images obtained, for example, when multiple semiconductor layer structures provided on a single wafer are irradiated at the same time. In this case, the first reference fluorescent image may be an image obtained when a single reference semiconductor layer structure is irradiated, but it is preferable that the first reference fluorescent image is an image obtained when multiple reference semiconductor layer structures determined to be good products are irradiated at the same time with the same light as the first inspection light. This makes it possible to configure, for example, multiple semiconductor layer structures formed on a single wafer to be determined to be good products at the same time, allowing for more efficient pass/fail determination.

The output unit 130 outputs the result of the determination made by the determination unit 221. The output unit 130 is, for example, a display.

The inspection device of embodiment 1 of the present disclosure described above can provide an inspection device for semiconductor layer structures that can perform inspections efficiently and with high inspection quality.

[Embodiment 2]
An inspection method of a second embodiment according to the present disclosure is an inspection method for determining whether a semiconductor layer structure has a plurality of light-emitting sections including a light-emitting layer, and includes the steps of: preparing a database storing a correlation between a current value when determining whether the light-emitting sections are good or bad by applying a current, and an irradiation intensity when determining whether the light-emitting sections are good or bad by irradiating inspection light having a shorter wavelength than the light emitted by the light-emitting sections; an irradiation intensity acquisition step of acquiring a first irradiation intensity corresponding to the applied current value for which the pass/fail judgment is to be made by referring to the database; an irradiation step of irradiating the semiconductor layer structure with inspection light at the first irradiation intensity; and a judgment step of judging whether the light-emitting sections are good or bad based on a fluorescent image of the semiconductor layer structure obtained by the irradiation step.
Here, the correlation between the current value when determining whether the light-emitting unit is good or bad and the irradiation intensity when determining whether the light-emitting unit is good or bad by irradiating it with inspection light refers to the current value and irradiation intensity at which the result of judging whether the light-emitting unit is good or bad by applying current matches the result of judging whether the light-emitting unit is good or bad by irradiating it with inspection light.

The inspection method of the above-described embodiment 2 judges the pass/fail of the light-emitting portion based on a fluorescent image of the semiconductor layer structure. Therefore, it is possible to judge the pass/fail of the light-emitting portion without applying a current, in other words, without using a probe for applying a current, and therefore it is possible to efficiently judge the pass/fail of the light-emitting portion.
Furthermore, the inspection method of embodiment 2 judges the pass/fail of the light-emitting unit based on the correlation between the current value when judging the pass/fail of the light-emitting unit by applying a current, and the irradiation intensity when judging the pass/fail of the light-emitting unit by irradiating it with inspection light having a shorter wavelength than the light emitted by the light-emitting unit, so it is possible to judge the pass/fail of the light-emitting unit with the same detection accuracy as with current application.
Hereinafter, each step of the inspection method according to the second embodiment will be specifically described with reference to the drawings.
Here, as described above, the inspection method of the second embodiment includes the database preparation step S610, the irradiation intensity acquisition step S620, the irradiation step S630, and the determination step S640 shown in the flowchart of Fig. 4. Fig. 5 is a flowchart of the database preparation step S610.

<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 when determining whether the light-emitting unit is good or bad by applying a current, and the irradiation intensity when determining whether the light is good or bad by irradiating inspection light having a shorter wavelength than the light emitted by the light-emitting unit.
The database preparation step S610 includes a type selection step S611, a current application measurement step S612, a light excitation measurement step S613, and a data storage step S614, all of which are shown in FIG.

First, in a type selection step S611, the semiconductor layer structure of the light emitting element to be inspected is selected.
Next, in a current application measurement step S612, for example, a pass/fail judgment is performed for the selected semiconductor layer structure when a current is applied. Also, a pass/fail judgment is performed for a plurality of semiconductor layer structures provided on a wafer when a current is applied. When a pass/fail judgment is performed for each of a plurality of semiconductor layer structures, a probe is moved to apply a current. For example, a constant current of 1 mA or less or 1/100 of the rated current set for each type is applied to the semiconductor layer structure, and the voltage of each semiconductor layer structure is measured. Then, for example, a semiconductor layer structure that satisfies a threshold voltage (which may have a certain allowable range) provided for the selected semiconductor layer structure is judged to be a pass/fail product, and a semiconductor layer structure that is below the threshold voltage is judged to be a failing product.

Next, in the photoexcitation measurement step S613, the semiconductor layer structures determined to be good in the current application measurement step S612 and the semiconductor layer structures determined to be defective are irradiated with inspection light having a shorter wavelength than the light emitted by the light-emitting unit while changing the irradiation intensity. Then, the fluorescent light emission at each irradiation intensity is confirmed, and (i) the irradiation intensity of the inspection light at which the semiconductor layer structures determined to be good by the current application measurement can be determined to be good and the semiconductor layer structures determined to be defective, and (ii) the fluorescent images of the good products and the defective products at the irradiation intensity are obtained.

For example, when a pass/fail judgment is performed by applying a current to each of a plurality of semiconductor layer structures provided on a wafer, the optimum irradiation intensity of the inspection light for pass/fail judgment by light irradiation can be determined as follows. Specifically, the inspection light is irradiated collectively to the plurality of semiconductor layer structures provided on the wafer for which a pass/fail judgment by current application has been performed, and fluorescent images of the plurality of semiconductor layer structures are acquired collectively. Then, the fluorescent images of each semiconductor layer structure in the collectively acquired images are matched to the pass/fail judgment for each semiconductor layer structure by applying a current based on the position information of each semiconductor layer structure, and the irradiation intensity of the inspection light at which the pass/fail judgment by irradiation of the inspection light and the pass/fail judgment by current application match can be determined as the irradiation intensity suitable for pass/fail judgment.

Then, in a data storage step S614, the irradiation intensity when determining pass/fail by irradiating inspection light with a shorter wavelength than the light emitted by the light-emitting portion, which is correlated with the pass/fail determination of the light-emitting portion by current application, and the fluorescence image at that irradiation intensity, i.e., (i) the irradiation intensity of the inspection light at which a semiconductor layer structure determined to be pass/fail by current application measurement can be determined to be pass/fail and a semiconductor layer structure determined to be fail/fail, and (ii) the fluorescence image of a pass/fail product and the fluorescence image of a fail/fail product at that irradiation intensity are stored in the database. Here, the fluorescence image of a pass/fail product and the fluorescence image of a fail/fail product in (ii) are reference fluorescence images that are used as the standard for pass/fail determination. The reference fluorescence image may also be an image obtained when multiple reference semiconductor layer structures determined to be pass/fail by current application are collectively irradiated with the same light as the inspection light irradiated in the irradiation step.

Furthermore, in step S615, it is checked whether there are any other varieties to be put into the database, and if there are other varieties, steps S611 to S614 are repeated to put the other varieties into the database, and if there are no other varieties to be put into the database, preparation of the database is terminated.

<Irradiation Intensity Acquisition Step S620>
In the irradiation intensity acquisition step S620, the database is referenced to acquire the irradiation intensity corresponding to the applied current value when determining whether the type of the semiconductor layer structure to be inspected is good or bad.

<Irradiation step S630>
In an irradiating step S630, the inspection light is irradiated onto the semiconductor layer structure at an illumination intensity.

<Determination Step S640>
In the determination step S640, a fluorescent image of the semiconductor layer structure obtained by irradiating it with the inspection light is obtained, and the quality of the light emitting portion is determined based on the fluorescent image of the semiconductor layer structure while referring to the database.
For example, in the determination step S640,
(i) a fluorescence image of the semiconductor layer structure;
(ii) a reference fluorescent image obtained by irradiating a reference semiconductor layer structure determined to be a non-defective product by applying a current with the same light as the inspection light irradiated in the irradiation step; and
The quality of the light emitting portion is judged by comparing the above.
The database stores a correlation between a plurality of current values when determining whether the semiconductor layer structure is good or bad by applying a current and a plurality of irradiation intensities corresponding to the respective current values. The irradiation intensity acquisition step, the irradiation step, and the determination step may be performed with a plurality of irradiation intensities. For example, an irradiation step of irradiating the semiconductor layer structure with inspection light at the second irradiation intensity using a second irradiation intensity smaller than the first irradiation intensity, and a determination step of determining whether the light-emitting portion is good or bad based on a fluorescent image of the semiconductor layer structure obtained by the irradiation step may be performed. Also, an irradiation step of irradiating the semiconductor layer structure with inspection light at the second irradiation intensity using a second irradiation intensity larger than the first irradiation intensity, and a determination step of determining whether the light-emitting portion is good or bad based on a fluorescent image of the semiconductor layer structure obtained by the irradiation step may be performed.

According to the inspection method of embodiment 2 described above, the pass/fail of the light-emitting portion is judged based on a fluorescent image of the semiconductor layer structure. Therefore, the pass/fail judgment can be made without applying a current, in other words, without using a probe for applying a current, and the pass/fail judgment can be made efficiently.
Furthermore, according to the inspection method of embodiment 2, the pass/fail of the light-emitting unit is determined based on the correlation between the current value when determining the pass/fail of the light-emitting unit by applying a current, and the irradiation intensity when determining the pass/fail of the light-emitting unit by irradiating it with inspection light having a shorter wavelength than the light emitted by the light-emitting unit, so that it is possible to determine the pass/fail of the light-emitting unit with the same detection accuracy as with current application.

Next, we will explain the inspection device that performs the inspection method of embodiment 2.

The inspection device of the second embodiment is
An inspection apparatus 200 for determining whether a semiconductor layer structure having a plurality of light emitting portions including a light emitting layer is acceptable or not,
a database 240 storing a correlation between a current value when determining the quality of a light-emitting portion by applying a current and an irradiation intensity when determining the quality of a light-emitting portion by irradiating the light with an inspection light having 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 that refers to the database to obtain an irradiation intensity corresponding to an applied current value to be judged as pass/fail, controls the emission intensity of the inspection light so that the semiconductor layer structure is irradiated with the inspection light of the obtained irradiation intensity, and causes the irradiation unit to irradiate the semiconductor layer structure with the inspection light;
an image acquisition unit 111 for acquiring a fluorescent image of a semiconductor layer structure by irradiating the semiconductor layer structure with inspection light;
a determination unit that determines whether the semiconductor layer structure is good or bad based on the acquired fluorescent image and outputs the determination result as a determination result of the semiconductor layer structure at the applied current value;
including.

The inspection device of the second embodiment will be described in detail below.
FIG. 6 is a block diagram showing the configuration of inspection device 200 , which includes inspection section 110 , control section 220 , database 240 , and output section 130 .
Here, the inspection unit and the output unit are configured similarly to the inspection unit 110 and the output unit 130 of the inspection device 100 of the first embodiment, and are indicated in Fig. 6 by the same reference numerals as in Fig. 2. Also in Fig. 6, a wafer 115 provided with a plurality of semiconductor layer structures is illustrated as an inspection target.

The database 240 stores a reference fluorescent light image obtained when a reference semiconductor layer structure that has been determined to be non-defective by applying a current is irradiated with the same light as the inspection light irradiated by the irradiating unit 112 .
In the database 240, for each type of product, the current value used to determine the pass/fail of the light-emitting part by applying a current, and the irradiation intensity used to determine the pass/fail of the light-emitting part by irradiating it with inspection light having a shorter wavelength than the light emitted by the light-emitting part, which results in agreement with the pass/fail determination based on that current value, are stored together with a reference fluorescent image.
Furthermore, in the case where the reference fluorescence image is an image including fluorescence images of a plurality of semiconductor layer structures provided on a wafer, database 240 stores, for each product type, the current value used to judge the pass/fail of the light-emitting portion by applying a current, the irradiation intensity used to judge the pass/fail of the light-emitting portion by irradiating it with inspection light having a shorter wavelength than the light emitted by the light-emitting portion and whose result coincides with the pass/fail judgment based on that current value, as well as the reference fluorescence image and positional information of each semiconductor layer structure on the wafer.

As described above, the inspection unit 110 is configured in the same manner as in embodiment 1, and a detailed description will be omitted.

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 acquires the irradiation intensity of the inspection light to be irradiated on the type of 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 on the semiconductor layer structure with the acquired irradiation intensity. For example, the irradiation control unit 224 controls one or more of 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 of the light emitted from the light source, the emission angle with respect to the surface of the semiconductor layer structure, etc., to cause the irradiation unit 112 to emit the inspection light so that the semiconductor layer structure is irradiated with the inspection light at a predetermined irradiation intensity. In addition, when the inspection object is a wafer 115, for example, the irradiation unit 112 is controlled so that the inspection light is irradiated on the entire surface of the wafer 115 with a predetermined irradiation intensity and with reduced irradiation unevenness.

The image acquisition control unit 222 controls the image acquisition timing of the image acquisition unit 111, for example, the timing of releasing the camera shutter, based on the timing at which the irradiation control unit 224 causes the irradiation unit 112 to emit the inspection light. Normally, the image acquisition unit 111 acquires an image several milliseconds (ms), that is, almost immediately after the inspection light is emitted. However, for example, if there is a time difference between when the inspection light is irradiated onto the semiconductor laminate structure and when the light emitting unit emits light, and when a stable, optimal image is formed on the surface of the semiconductor laminate structure, the image acquisition timing of the image acquisition unit 111 is controlled taking these time differences into consideration.

The determination unit 221 determines whether the semiconductor layer structure is good or bad based on the fluorescent image acquired by the image acquisition control unit 222. For example, the determination unit 221 determines whether the semiconductor layer structure is good or bad by comparing the fluorescent image of the semiconductor layer structure obtained by irradiating inspection light by the irradiation unit 112 with a reference fluorescent image stored in the database 240.

The comparison of the fluorescent image and the reference fluorescent image in the pass/fail judgment can be performed in various ways. For example, the brightness and contrast of the image in the fluorescent image of the semiconductor layer structure are compared with the brightness and contrast of the image in the reference fluorescent image, and if the difference in brightness and contrast is within a predetermined range, the product is judged to be good, and if the brightness, etc. in the fluorescent image of the semiconductor layer structure is lower than the predetermined range, the product is judged to be defective. In addition, the judgment unit 221 may be configured to judge the product to be good if the emission intensity calculated based on the brightness, etc. of the fluorescent image is greater than a first reference intensity calculated based on the brightness, etc. of the reference fluorescent image, and to judge the product to be defective if it is smaller.

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

In the inspection device 200 of the second embodiment configured as described above, the database stores correlations between a plurality of current values when determining the quality of the semiconductor layer structure by applying a current and a plurality of irradiation intensities corresponding to the respective current values. Then, the determination unit 221 can determine the quality of the semiconductor layer structure at the plurality of current values.
In the inspection device 200, for example, the irradiation control unit 224 controls the irradiation unit 112 to irradiate the inspection light to multiple semiconductor layer structures simultaneously at the acquired irradiation intensity, and the irradiation unit 112 irradiates the inspection light to multiple semiconductor layer structures simultaneously at the acquired irradiation intensity.
The image acquisition unit 111 acquires a fluorescent image including a plurality of fluorescent lights emitted by a plurality of semiconductor layer structures by simultaneous irradiation with the inspection light.
The determining unit 221 then determines whether the multiple semiconductor layer structures are good or bad based on the fluorescent light image containing the multiple fluorescent lights.

In the inspection device 200, when inspection light is irradiated simultaneously to multiple semiconductor layer structures to obtain a fluorescence image containing multiple fluorescent light, it is preferable that the judgment unit 221 judges 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 simultaneously to multiple reference semiconductor layer structures that have been judged to be good products by applying a current.

REFERENCE SIGNS LIST 100, 200 Inspection device 110 Inspection unit 111 Image acquisition unit 112 Irradiation unit 113 Support unit 115 Wafer 120, 220 Control unit 121, 221 Determination unit 122, 222 Image acquisition control unit 123 Storage unit 124, 224 Irradiation control unit 130 Output unit 240 Database

Claims (9)

1. An inspection method for determining whether a semiconductor layer structure having a plurality of light emitting portions including a light emitting layer is acceptable or not, comprising the steps of:
preparing a database storing a correlation between a current value when determining whether the light-emitting unit is good or bad by applying a current and an irradiation intensity when determining whether the light-emitting unit is good or bad by irradiating the light with an inspection light having a shorter wavelength than the light emitted by the light-emitting unit;
an irradiation intensity acquisition step of acquiring a first irradiation intensity corresponding to an applied current value for which a pass/fail judgment is to be made by referring to the database;
an irradiation step of irradiating the semiconductor layer structure with the inspection light at the first irradiation intensity;
a determining step of determining whether the light emitting portion is good or bad based on a fluorescent image of the semiconductor layer structure obtained by the irradiating step;
including,
A method for inspecting a semiconductor layer structure. In the determining step,
(i) the fluorescence image of the semiconductor layer structure; and
(ii) a reference fluorescent image obtained by irradiating a reference semiconductor layer structure determined to be a non-defective product by applying a current with the same light as the inspection light irradiated in the irradiation step; and
and determining whether the light emitting unit is good or bad by comparing the results.
2. A method for inspecting a semiconductor layer structure according to claim 1. The irradiation intensity acquisition step, the irradiation step, and the determination step are performed at a plurality of irradiation intensities.
3. A method for inspecting a semiconductor layer structure according to claim 1. The reference fluorescent image is an image obtained when a plurality of reference semiconductor layer structures determined to be non-defective by current application are collectively irradiated with the same light as the inspection light irradiated in the irradiation step.
3. A method for inspecting a semiconductor layer structure according to claim 2. An inspection apparatus for determining whether a semiconductor layer structure having a plurality of light emitting portions including a light emitting layer is acceptable or not,
a database storing a correlation between a current value when determining the quality of a light-emitting portion by applying a current and an irradiation intensity when determining the quality of a light-emitting portion by irradiating the light with an 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;
an irradiation control unit that refers to the database to obtain an irradiation intensity corresponding to an applied current value to be determined as pass/fail, controls an emission intensity of an inspection light so that the semiconductor layer structure is irradiated with an inspection light of the obtained irradiation intensity, and causes the irradiation unit to irradiate the inspection light onto the semiconductor layer structure;
an image acquisition unit for acquiring a fluorescent image of the semiconductor layer structure by irradiating the inspection light;
a determination unit that determines whether the semiconductor layer structure is good or bad based on the acquired fluorescent image and outputs a determination result of the semiconductor layer structure at the applied current value;
including,
Semiconductor layer structure inspection equipment. The database stores a reference fluorescent light image obtained when a reference semiconductor layer structure determined to be a non-defective product is irradiated with the same light as the inspection light irradiated by the irradiating unit by applying a current,
6. The semiconductor layer structure inspection device according to claim 5, wherein the determining section determines whether the semiconductor layer structure is good or bad by comparing the fluorescent image of the semiconductor layer structure with the reference fluorescent image. the determination unit outputs a determination result of the semiconductor layer structure at the plurality of current values.
7. An inspection device for a semiconductor layer structure according to claim 5 or 6. The irradiation unit irradiates the inspection light at the acquired irradiation intensity onto the plurality of semiconductor layer structures at once,
the image acquisition unit acquires a fluorescent image including a plurality of fluorescent lights emitted by the plurality of semiconductor layer structures by simultaneous irradiation with the inspection light,
the determining unit determines whether the plurality of semiconductor layer structures are good or bad based on a fluorescent light image including the plurality of fluorescent lights.
An inspection device for a semiconductor layer structure according to any one of claims 5 to 7. In the determination unit,
A fluorescence image including the plurality of fluorescences;
a reference fluorescent image including fluorescent light emitted from a plurality of reference semiconductor layer structures determined to be non-defective by current application when the plurality of reference semiconductor layer structures are collectively irradiated with the same light as the inspection light irradiated from the irradiation unit;
and determining whether the plurality of semiconductor layer structures are good or bad by comparing the above.
9. An apparatus for inspecting a semiconductor layer structure according to claim 8.

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