KR20110067843A - Apparatus and method for inspecting led epiwafer using photoluminescence imaging - Google Patents

Abstract

PURPOSE: An apparatus and method for inspecting LED epiwafer using photoluminescence imaging are provided to reduce a time for monitoring an epiwafer by detecting PL(photoluminescence) with CCD camera or CMOS camera and analyzing an image signal. CONSTITUTION: In an apparatus and method for inspecting LED epiwafer using photoluminescence imaging, a lighting unit outputs light having wavelength shorter than that of an LED epiwafer to a target. A pickup unit(130) obtains the image of light emitted from the LED epitaxial wafer. A filter unit(140) is comprised of a plurality of bandpass filter passing an emitted light within a certain wavelength An image processing unit(150) calculates the strength of the light at sub-area corresponding to the LED epitaxial wafer.

Description

LED epiwafer inspection apparatus using photoluminescence imaging and its method {Apparatus and method for inspecting LED epiwafer using photoluminescence imaging}

The present invention relates to an LED epiwafer inspection apparatus and a method thereof, and in particular, an inspection time of an epiwafer through image processing of photoluminescence imaging which photographs light emitted by irradiating light onto the LED epiwafer. The present invention relates to an LED epiwafer inspection apparatus using photoluminescence imaging and a method thereof, which can reduce the number of pixels.

The LED epiwafer is a wafer on which a necessary crystal layer is grown on a substrate by using metal organic chemical vapor deposition (MOCVD).

9 is a cross-sectional view of the LED epiwafer.

In the case of the blue LED and the green LED, as shown in FIG. 9, the nitride-based semiconductor is grown on the sapphire substrate, but in the case of the red LED and the yellow LED, the phosphide-based semiconductor is grown on the gallium arsenide substrate.

In general, LED epiwafers that have grown the necessary crystal layers are inspected before being introduced into the chip (device) manufacturing process, and photoluminescence (hereinafter referred to as PL) is mainly used.

The PL measurement is to examine the characteristics of the active layer of the LED epiwafer. The light having a higher energy than the bandgap energy of the active layer that determines the wavelength of the LED, that is, the light having a wavelength shorter than the wavelength of the LED is used as the excitation light. This excites electrons in the valence band of the active layer to the conduction band and detects the light when these excited electrons fall back to the valence band while emitting energy as light.

The PL measurement to check if the active layer crystal of the LED epiwafer is a good enough crystal to act as a chip is the PL wavelength, PL intensity and half width of the PL spectrum.

The method of inspecting the LED epi wafer is to examine the characteristics of the epi wafer on which the p-n junction structure layer is grown for each position, and a method mainly used is PL mapping. The PL mapping method detects a PL signal for each inspection target element (inspection point) formed on the epiwafer and maps the result to confirm distribution of PL characteristics according to positions on the epiwafer.

However, since the conventional method of inspecting the LED epiwafer using PL mapping detects the PL signal for several points for each subregion on the epiwafer, the inspection time is about a few minutes per epiwafer. In the case of inch wafer takes about 2-3 minutes there is a problem that the inspection time takes a relatively long time.

Moreover, considering the size of epi wafers and the trend of mass production in LED production in the future, it is required to develop the PL characteristics of epi wafers as an analysis and inspection method that can obtain more information faster.

In order to solve the above problems of the prior art, the present invention detects a PL signal with a CCD camera using a band pass filter corresponding to a target wavelength and analyzes the image through an image processing, and analyzes the PL of the epi wafer in a short time within several tens of seconds. An apparatus and method for inspecting an LED epiwafer using photoluminescence imaging capable of inspecting characteristics are provided.

The present invention for solving the above problems is an illumination unit for outputting light having a wavelength shorter than the emission wavelength of the inspection target LED epi-wafer; A photographing unit which acquires an image of light emitted from the LED epi wafer by the irradiated light; A filter unit formed at a front end of the photographing unit, the filter unit comprising a plurality of band pass filters passing light of a predetermined wavelength band among the emitted light; The intensity of each subregion corresponding to the LED epiwafer is calculated from the acquired image, and the intensity of the subregion is based on the plurality of images acquired by the photographing unit for each of the plurality of bandpass filters. And an image processor configured to generate an image in which the wavelength and the intensity are displayed by using the large wavelength band as the emission light wavelength of the corresponding detail region.

Preferably, the control unit for adjusting the wavelength of the output light of the illumination unit, and sequentially selects the pass band of the filter unit; And a display unit configured to display an image processed by the image processor.

According to another aspect of the present invention, an LED epiwafer inspection apparatus using photoluminescence imaging may include: an illumination unit configured to output an intensity of light having a wavelength shorter than a light emission wavelength of an LED epiwafer to be inspected; A photographing unit which acquires an image of light emitted from the LED epi wafer by the irradiated light; A filter unit installed at a front end of the photographing unit and configured to pass light having a predetermined wavelength band among the emitted light; The intensity is calculated for each subregion corresponding to the LED epi wafer from the acquired image, and the intensity is changed according to the intensity change rate of the subregion based on a plurality of images acquired by the photographing unit with respect to the intensity of the output light. And an image processor for generating an image displayed at the emission efficiency of the corresponding detail region.

Preferably, the controller for controlling the intensity and wavelength of the output light of the lighting unit; And a display unit configured to display an image processed by the image processor.

Preferably, the image processor may calculate the displayed image to be displayed in gray scale or color.

Preferably, the light emitting unit may further include a diffusion unit that uniformly irradiates the LED epi wafer.

Preferably, the lens unit may further include a lens unit installed at the front end of the photographing unit so as to photograph the maximum area of the LED epiwafer.

Preferably, the lens unit may determine the magnification according to the size of the LED epi-wafer.

Preferably it may further comprise a spectrum analyzer for measuring the intensity and wavelength of light emitted from the LED epiwafer.

Preferably, the image processor may correct the intensity displayed on the plurality of images or images of different LED epiwafers based on the intensity of light measured by the spectrum analyzer.

According to another aspect of the present invention, there is provided a method of inspecting an LED epiwafer using photoluminescence imaging, comprising: irradiating a light having a wavelength shorter than a light emission wavelength of an inspection target LED epiwafer to the LED epiwafer; A photographing step of acquiring an image of light emitted from the LED epiwafer through a plurality of band pass filters; The intensity of each subregion corresponding to the LED epiwafer is calculated from the acquired image, and the intensity of the subregion is based on the plurality of images acquired by the photographing unit for each of the plurality of bandpass filters. And an image processing step of generating an image in which the wavelength and the intensity are displayed by using the large wavelength band as the emission light wavelength of the corresponding detail region.

Preferably, in the photographing step, the plurality of band pass filters may be sequentially selected for photographing.

LED epiwafer inspection method using photoluminescence imaging according to another aspect of the present invention is irradiating step of uniformly irradiating the LED epiwafer while changing the intensity of light having a wavelength shorter than the emission wavelength of the inspection target LED epiwafer Wow; A photographing step of acquiring an image of light emitted from the LED epiwafer through a plurality of band pass filters; The intensity is calculated for each subregion corresponding to the LED epi wafer from the acquired image, and the intensity is changed according to the intensity change rate of the subregion based on a plurality of images acquired by the photographing unit with respect to the intensity of the output light. And an image processing step of generating an image displayed at the emission efficiency of the corresponding detail area.

Preferably, the method may further include displaying an image processed by the image processor.

Preferably, the image processing step may be calculated so that the obtained image is displayed in gray scale or color.

Preferably, in the photographing step, the photographing magnification may be determined according to the size of the LED epiwafer to photograph the maximum area of the LED epiwafer.

Preferably, the method further includes a measuring step of measuring the intensity and wavelength of light emitted from the LED epiwafer using a spectrum analyzer, wherein the image processing step is based on the intensity of light measured by the spectrum analyzer. Alternatively, the intensity displayed on the images of different LED epiwafers may be corrected.

LED epiwafer inspection apparatus and method using photoluminescence imaging according to the present invention by detecting the PL of the LED epiwafer with a CCD camera or a CMOS camera and analyzing through the image signal processing, PL wavelength according to the position on the epiwafer And the intensity distribution can be easily confirmed, there is an effect that can be inspected in a short time within several tens of seconds.

In addition, the present invention obtains PL imaging while changing inspection conditions such as the wavelength and intensity of the excitation light, thereby obtaining unknown crystal characteristics by an inspection method according to PL mapping such as PL efficiency distribution.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

First, referring to FIG. 1, an LED epiwafer inspection apparatus using photoluminescence imaging according to a first embodiment of the present invention will be described.

1 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a first embodiment of the present invention.

LED epi-wafer inspection apparatus 10 is a light source 110 for outputting light, a diffusion plate 120 for diffusing the output light, the image of the light emitted from the LED epi-wafer 300 by the irradiated light Acquiring the photographing unit 130, the filter unit 140 for passing the light of a predetermined wavelength band, the image processing unit 150 for processing the obtained image to generate a PL imaging, and a display unit for displaying the PL characteristics 160, a control unit 170 for controlling the wavelength and intensity of the light source 110 and the filter unit 140, and a stage 200 for fixing the LED epiwafer 300.

The light source 110 outputs light having a wavelength shorter than the emission wavelength of the LED epiwafer 300 to be inspected.

Here, in order to examine the LED epiwafer 300 having grown the required LED structure layer on the substrate, the excitation light having a higher energy than the bandgap energy of the active layer of the LED epiwafer 300, that is, than the light emitting wavelength of the LED Short excitation light is required. For example, when inspecting the 450 nm area blue LED epiwafer, the light source 110 is preferably a 325 nm He-Cd laser or a GaN-based blue violet or ultraviolet laser diode.

The diffuser 120 is an optical component such as a homogenizer or diffuser, and has a size necessary to uniformly irradiate the excitation light output from the light source 110 on the entire surface of the LED epi wafer 300. To spread.

The photographing unit 130 maximizes the area of the camera 132 and the LED epiwafer 300 that acquire an image of the light emitted from the LED epiwafer 300 by the light emitted from the diffuser plate 120. It consists of a lens 134 to be photographed.

The camera 132 may be a CCD camera or a CMOS camera, and the area on the LED epiwafer 300 per pixel is determined according to the size of the image sensor, for example, a 2-inch epiwafer with a size of 1024x1024. In the case of inspecting the X, corresponds to an area of 50 μm per pixel.

Here, the macroblock may be set to 5x5 or 10x10 or wider area according to the actual resolution of the image to be photographed, and the video signal of each pixel may be averaged and used as the video signal of the corresponding macroblock. Corresponds to an area of 0.25 to 1 mm 2 or more on the LED epiwafer 300.

The lens 134 is installed at the front of the camera 132, and the magnification is determined according to the size of the inspection target LED epiwafer 300 so that the entire area for the LED epiwafer 300 is detected in one frame. Here, the magnification of the lens 134 may be adjusted to enlarge the detail region of the LED epiwafer 300.

The filter unit 140 is installed at the front end of the photographing unit 130, that is, between the photographing unit 130 and the stage 200, and may include a plurality of band pass filters 142a to e.

The reason why the filter unit 140 is composed of a plurality of band pass filters 142a to e is a pass corresponding to a target wavelength of the LED epiwafer 300 to be inspected in order to inspect the crystal characteristics of the LED epiwafer 300. It is required to measure the primary intensity distribution by band, where a plurality of bandpasses having different passbands may exist because wavelengths of emitted light may not be uniform depending on the positional characteristic distribution of the LED epiwafer 300. It is for measuring using a filter.

Each bandpass filter 142a through e passes light of a predetermined wavelength band among the emission light emitted from the LED epiwafer 300, and each passband is determined from the PL spectrum, and in the case of a blue LED, a range of 440 nm to 460 nm. This is preferred.

The image processor 150 calculates the intensity of each sub-region corresponding to the LED epi-wafer 300 in the image obtained from the photographing unit 130, and the intensity distribution of each part of the acquired image is gray scale. Or compute to display in color. In this case, the bright part of the image represents a strong intensity region, and the PL image may be configured in a continuous form. The macro block may be defined by neighboring pixels and the average value thereof may be displayed on the overall LED epiwafer 300. It may also be characteristic.

In addition, the image processor 150 is configured based on the PL image obtained from the photographing unit 130 with respect to light having a wavelength region near each pass band of each of the plurality of band pass filters 142a to e, and is applied to the wavelength band of the emitted light. Therefore, the image is reconstructed for each region of high intensity. That is, the image processor 150 generates an image in which the wavelength band having the greatest intensity of the corresponding detail region is displayed as the emission light wavelength of the detail region.

The display 160 displays an image processed by the image processor 150 so that an inspector can check the measured PL characteristics of the LED epiwafer 300.

The control unit 170 adjusts the wavelength of the output light of the light source 110 according to the setting, and sequentially selects a plurality of band pass filters 142a to e so as to measure the PL of the wavelength band according to each pass band.

The stage 200 fixes the LED epiwafer 300 grown by the organometallic chemical vapor deposition method through the wafer holder and moves the LED epiwafer 300 in the process sequence.

The LED epi-wafer inspection apparatus 10 according to the first embodiment of the present invention configured as described above detects the distribution of the PL appearing in the LED epi-wafer 300 with the camera 132 at room temperature and the brightness of the signal, that is, the PL intensity. The image is processed and displayed accordingly.

Here, the PL of the LED epiwafer 300 is observed using a spectrum analyzer as shown in FIG. 2.

2 is a graph showing the relationship between PL intensity and wavelength.

As shown in FIG. 2, the intensity of the PL varies according to the wavelength. In the case of the LED, since the required layer is laminated by crystal growth on the substrate, the characteristic may vary for each part. That is, there may be a difference in PL wavelength or a difference in intensity for each position on the LED epi-wafer 300, and the band pass filters 142a to e passing only the light of a specific band wavelength may pass the wavelength band. When only the light is photographed by the camera 132, the area where the wavelength of each pass band is the center wavelength on the LED epiwafer 300 has the largest intensity of PL and appears brightest in the image, and the low portion of PL intensity appears dark.

As described above, there is a part where the PL wavelength is slightly different for each part on the LED epiwafer 300. Images are obtained for each filter by using a plurality of band pass filters 142a to e by a method such as rotation. Then, the respective intensities are compared for each location of the image, that is, for each location on the LED epiwafer 300, and then displayed as one image. In this case, by displaying and displaying the wavelength having the strongest intensity for each position, that is, the center wavelength of the band pass filters 142a to e, the information on the intensity and the wavelength can be represented on the entire wafer.

This will be described in more detail with reference to FIGS. 3 and 4.

FIG. 3 is an example of an image photographed by a plurality of bandpass filters, and FIG. 4 is an example of an image representing PL wavelength characteristics using the image of FIG. 3.

Here, assuming that the target wavelength of the LED epi-wafer 300 is λ and that the difference between the allowable wavelengths but deviating from the target wavelength is Δλ, the center wavelengths of the band pass filters 142a to e are λ in FIG. 3. Δλ (a), λ-Δλ / 2 (b), λ (c), λ + Δλ / 2 (d), and λ + Δλ (e). In this case, the center wavelength of the band pass filter may be selected by other criteria.

When the LED epi-wafer 300 is irradiated with excitation light having a uniform intensity and excites PL, a PL image passing through each band pass filter 142a to e is obtained as shown in FIG. 3.

The brighter each image is, the greater the intensity is, and the greater intensity is shown in the corresponding wavelength band. As shown in FIG. 4, the wavelength band in which the intensity among the five images is greatest is shown on the LED epiwafer 300. Create a PL image to appear in the area.

For example, since the brightest image for the left region of the LED epiwafer 300 is b of FIG. 3 and the corresponding center wavelength is λ-Δ / 2, it is simply indicated by −Δλ / 2 in FIG. 4. Here, the display of the image may be represented by color, gray scale, or another method.

5 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a second embodiment of the present invention.

In the present embodiment, since the output light intensity of the light source 510, the configuration of the filter unit 540, and the configuration except for the image processor 550 are the same as those of Embodiment 1, the description thereof is omitted here.

The light source 510 outputs light while changing the intensity of the output light under the control of the controller 570.

As described above, the LED epiwafer 300 has a difference in characteristics of each subregion according to the lamination process, wherein PL efficiency is related to the quantum efficiency inside the LED epiwafer 300. It can be used as a basis for determining how much the crystallinity of the active layer is in each subregion of.

On the other hand, the present inventors are in the process of formulating the relationship between the PL efficiency and the internal quantum efficiency, and when the formulation is completed, it may directly indicate the internal quantum efficiency through the PL image.

The filter unit 540 is configured as one bandpass filter that passes light of a predetermined wavelength band among the light emitted from the LED epiwafer 300. In this embodiment, since only the same wavelength band is measured in order to measure the intensity variation of the PL according to the intensity of the light source 510, only one bandpass filter is used. It can also consist of multiple bandpass filters.

The image processor 550 calculates the intensity of each subregion corresponding to the LED epiwafer 300 in the image acquired from the photographing unit 530 as in the first exemplary embodiment.

In addition, the image processing unit 550 based on the PL image obtained from the photographing unit 530 with respect to the output light of different intensities of the light source 510, the image for each region having a high rate of change of PL intensity according to the change in the intensity of the excitation light Reconstruct That is, the image processor 550 generates an image displayed by the emission efficiency of the corresponding subregion according to the PL intensity change rate with respect to the subregion.

The LED epi-wafer inspection apparatus 50 according to the second embodiment of the present invention configured as described above acquires a plurality of images on the LED epi-wafer 300 while varying the intensity of the excitation light output from the light source 510, and each image. Comparing the subregions of the measured by the change of the PL intensity, and based on this to generate a single image representing the PL efficiency. Here, the degree of change in each subregion is quantified by color or gray scale to display the PL efficiency on the LED epiwafer 300 as one image.

In general, the PL intensity increases with the intensity of the excitation light, but as described above, the increase is different depending on the position on the LED epiwafer 300. This is because the PL efficiency is different from each other and is closely related to the internal efficiency of the LED epiwafer 300. Therefore, by analyzing the PL image for each intensity of the excitation light, it is possible to display the change of the PL image according to the intensity of the excitation light as the PL efficiency for each region of the LED epiwafer 300.

This will be described in more detail with reference to FIG. 6.

FIG. 6 is a diagram for describing a method of generating an image representing a PL efficiency characteristic according to light intensity.

The LED epiwafer inspection apparatus 10 changes the intensity of the excitation light with respect to the same LED epiwafer 300, for example, 10 Hz, 20 Hz, 30 Hz,... , 80 kHz, while obtaining the respective LED epi-wafer 300 image is displayed PL intensity distribution.

For example, the change rate of the PL intensity is calculated by comparing images for each subregion of 5x5 or 10x10 pixels. In FIG. 6, the PL intensity increases more rapidly as the intensity of the excitation light increases as compared to the right region, which means that the left region has a higher PL efficiency than the right region.

When the result of the PL intensity change with respect to the change in the excitation light intensity is displayed as one image, the PL efficiency may be indicated for each subregion on the LED epiwafer 300.

As described above, the present invention uses the PL imaging to change the inspection conditions by using the advantages of inspecting the characteristics such as the PL wavelength and intensity distribution according to the position of the LED epiwafer 300 in a short time within several tens of seconds. It is more closely related to the characteristics of the epiwafer 300, and it is possible to obtain more effective characteristics in predicting the information of the epitaxial wafer 300, which is unknown by the conventional PL mapping method, such as the PL efficiency distribution. Therefore, it is possible to provide more effective information for determining whether the LED chip production input.

7 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a third embodiment of the present invention.

In the present embodiment, since the configuration except for the image processor 750 and the spectrum analyzer 780 is the same as that of Embodiment 1, the description thereof is omitted here.

When the security light flasher 70 relatively compares the PL characteristics of the plurality of LED epiwafers 300, the highest intensity or total LED epiwafer just before converting the PL imaging result of each LED epiwafer to gray scale. After measuring the average intensity of the phases, it is possible to make a relative comparison between the PL intensities of each LED epiwafer based on this. In this case, it is possible to have a value deviating by the influence of noise or a local difference. The spectrum is measured by the spectrum analyzer 780 to perform relative comparison.

The image processor 750 corrects the intensity displayed on the plurality of images or images of the different LED epiwafers 300 based on the intensity of the light measured by the spectrum analyzer 780.

The spectrum analyzer 780 measures the intensity and the wavelength of the light emitted from the LED epiwafer 300 through the optical fiber 782.

Here, when displaying a PL image, the maximum light intensity and the lowest light intensity are detected in one image and displayed as brightness, so that the brightness is the same when compared with images having different inspection conditions, especially when the LED epiwafer 300 is different. Since the intensity of the position is not the same, the spectrum analyzer 780 is always fixed to a certain position when acquiring each PL image, and then the PL spectrum is photographed, and then the intensity of the PL image is corrected using the PL intensity value. .

In the present embodiment, when comparing the LED epi-wafer 300 with a plurality of images or comparing images for different intensity and wavelength conditions, the actual PL spectrum is measured through the spectrum analyzer 780, and each center is used by using the same. Relative comparison is possible by correcting the PL image representing the wavelength intensity.

Hereinafter, an LED epiwafer inspection method using photoluminescence imaging of the present invention will be described with reference to FIG. 8.

8 is a flowchart of a method for inspecting an LED epiwafer using photoluminescence imaging according to an embodiment of the present invention.

LED epi-wafer inspection method using photo luminescence imaging is a step of uniformly irradiating light to the inspection target LED epi-wafer 300 (step S801), and photographing the light emitted from the LED epi-wafer 300 ( Step S802, and generating one image representing the PL characteristic based on the plurality of photographed images (step S803).

In more detail, first, light having a wavelength shorter than the light emission wavelength of the LED epi wafer 300 is uniformly irradiated to the LED epi wafer 300 through the diffusion plate 120 (step S801).

In this case, the intensity of the light source 110 is changed according to the inspection condition according to the PL characteristic. When the PL distribution and the PL wavelength are inspected, the light source 110 outputs excitation light having the same intensity and inspects the PL efficiency. In this case, excitation light of different intensities is output.

Next, an image of light having a wavelength of a specific band is obtained through the filter unit 140 having a predetermined pass band from the light emitted from the LED epiwafer 300 by the excitation light (step S802).

Here, the photographing magnification is determined according to the size of the LED epiwafer 300 so as to capture the maximum area of the LED epiwafer 300, for example, the lens 134 installed in front of the CCD camera 132. Adjust the magnification.

In this case, the image acquisition method is changed according to the inspection condition according to the PL characteristic. When the PL distribution and the PL wavelength are inspected, the filter unit 140 has a plurality of band pass filters 142a to e having different passbands. An image is obtained through the photographing. In this case, a plurality of band pass filters 142a to e are sequentially selected and photographed.

In addition, in the case of examining the PL efficiency, only one bandpass filter may be used to perform the same condition for different inspection conditions, for example, the PL wavelength, and a plurality of bandpass filters 142a for examining various characteristics at once. ~ e) can also be used.

In addition, when comparing the PL characteristics of different images or different LED epiwafer 300, it is necessary to correct the PL intensity for each image based on the same criteria. PL spectra such as intensity and wavelength of light emitted from the wafer 300 are measured.

Next, one image representing PL wavelength and intensity distribution, PL efficiency, etc. is generated based on the images acquired under different inspection conditions (step S803).

More specifically, first, the intensity of each subregion corresponding to the LED epi-wafer 300 is calculated in each of the acquired images, and the obtained image is calculated to be displayed in gray scale or color.

In this case, an image capable of displaying the PL characteristic to be inspected is generated. When inspecting the PL intensity and distribution characteristic, as illustrated in FIGS. 3 and 4 based on images of emission light having different wavelength bands. Similarly, an image in which the wavelength band having the greatest intensity of the corresponding detail region is displayed as the emission light wavelength of the detail region is generated.

In addition, in the case of inspecting the PL efficiency characteristic, as shown in FIG. 6, the rate of change of the intensity of the emitted light according to the intensity of the excitation light is displayed as the emission efficiency of the corresponding detailed area based on the image acquired according to the intensity of the different excitation light. Create the video

In addition, when comparing the PL characteristics of different images or different LED epiwafer 300, each image, that is, a plurality of images or different LED epiwafer 300 based on the intensity of light measured by the spectrum analyzer 780 Correct the intensity displayed on the image.

The processed image is displayed for inspection by the inspector.

In this manner, not only the PL characteristic can be inspected in a short time but also the characteristic information that can be applied to efficiently analyze various PL characteristics or substantial characteristics of the LED epiwafer 300 can be inspected using a short time.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the technical idea of the present invention, and it is obvious that the present invention belongs to the appended claims. Do.

1 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a first embodiment of the present invention,

2 is a graph showing the relationship between PL intensity and wavelength,

3 is an example of an image photographed by a plurality of band pass filters,

FIG. 4 is an example of an image showing PL wavelength characteristics using the image of FIG. 3.

5 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a second embodiment of the present invention;

FIG. 6 is a diagram for describing a method of generating an image representing a PL efficiency characteristic according to light intensity.

7 is a schematic configuration diagram of an LED epiwafer inspection apparatus using photoluminescence imaging according to a third embodiment of the present invention;

8 is a flowchart of a method for inspecting an LED epiwafer using photoluminescence imaging according to an embodiment of the present invention.

9 is a cross-sectional view of the LED epiwafer.

Explanation of symbols on the main parts of the drawings

10: wafer inspection device 110: light source

120: diffusion unit 130: the photographing unit

140: filter unit 150: image processing unit

160: display unit 170: control unit

Claims (17)

An illumination unit for outputting light having a wavelength shorter than the emission wavelength of the inspection target LED epi-wafer; A photographing unit which acquires an image of light emitted from the LED epi wafer by the irradiated light; A filter unit formed at a front end of the photographing unit, the filter unit comprising a plurality of band pass filters passing light of a predetermined wavelength band among the emitted light; The intensity of each subregion corresponding to the LED epiwafer is calculated from the acquired image, and the intensity of the subregion is based on the plurality of images acquired by the photographing unit for each of the plurality of bandpass filters. And an image processor configured to generate an image in which a wavelength and an intensity are displayed by using a large wavelength band as the emission light wavelength of a corresponding subregion. The method of claim 1, A controller for adjusting a wavelength of the output light of the lighting unit and sequentially selecting a pass band of the filter unit; LED epi-wafer inspection apparatus using a photo luminescence imaging further comprises a; display unit for displaying the image processed by the image processing unit. An illumination unit for outputting the light intensity having a wavelength shorter than the emission wavelength of the inspection target LED epiwafer; A photographing unit which acquires an image of light emitted from the LED epi wafer by the irradiated light; A filter unit installed at a front end of the photographing unit and configured to pass light having a predetermined wavelength band among the emitted light; The intensity is calculated for each subregion corresponding to the LED epi wafer from the acquired image, and the intensity is changed according to the intensity change rate of the subregion based on a plurality of images acquired by the photographing unit with respect to the intensity of the output light. LED epiwafer inspection apparatus using photoluminescence imaging comprising a; image processing unit for generating an image displayed by the emission efficiency of the sub-region. The method of claim 3, wherein A control unit for controlling the intensity and the wavelength of the output light of the lighting unit; LED epi-wafer inspection apparatus using a photo luminescence imaging further comprises a; display unit for displaying the image processed by the image processing unit. The method according to claim 1 or 3, And the image processing unit calculates the obtained image to be displayed in gray scale or color. The method according to claim 1 or 3, LED epiwafer inspection apparatus using photoluminescence imaging, characterized in that it further comprises a diffuser for uniformly irradiating the output light to the LED epiwafer. The method according to claim 1 or 3, LED epiwafer inspection apparatus using a photo luminescence imaging, characterized in that further comprising a lens unit is installed in front of the photographing unit to shoot to maximize the area of the LED epiwafer. The method of claim 7, wherein The lens unit LED epiwafer inspection apparatus using photoluminescence imaging, characterized in that the magnification is determined according to the size of the LED epiwafer. The method according to claim 1 or 3, And a spectrum analyzer for measuring the intensity and the wavelength of light emitted from the LED epiwafer. The method of claim 9, The image processor checks the LED epiwafer using photoluminescence imaging, characterized in that for correcting the intensity displayed on the plurality of images or images for different LED epiwafers based on the intensity of light measured by the spectrum analyzer. Device. An irradiation step of irradiating the LED epiwafer uniformly with light having a wavelength shorter than a light emission wavelength of the inspection target LED epiwafer; A photographing step of acquiring an image of light emitted from the LED epiwafer through a plurality of band pass filters; The intensity of each subregion corresponding to the LED epiwafer is calculated from the acquired image, and the intensity of the subregion is based on the plurality of images acquired by the photographing unit for each of the plurality of bandpass filters. And an image processing step of generating an image in which a wavelength and an intensity are displayed by using a large wavelength band as an emission light wavelength of a corresponding subregion. 2. 11. The method of claim 10, In the photographing step, LED epiwafer inspection method using photo luminescence imaging, characterized in that the photographing by sequentially selecting the plurality of band pass filter. An irradiation step of irradiating the LED epiwafer uniformly while changing the intensity of light having a wavelength shorter than the emission wavelength of the inspection target LED epiwafer; A photographing step of acquiring an image of light emitted from the LED epiwafer through a plurality of band pass filters; The intensity is calculated for each subregion corresponding to the LED epi wafer from the acquired image, and the intensity is changed according to the intensity change rate of the subregion based on a plurality of images acquired by the photographing unit with respect to the intensity of the output light. And an image processing step of generating an image displayed at the emission efficiency of the corresponding detail region. The method of claim 13, LED epi-wafer inspection method using a photo luminescence imaging, characterized in that it further comprises the step of displaying the image processed by the image processing unit. The method according to claim 11 or 13, The image processing step of the LED epi-wafer inspection method using a photo luminescence imaging, characterized in that for calculating so that the obtained image is displayed in gray scale (grey scale) or color. The method according to claim 11 or 13, The photographing step of the LED epi-wafer inspection method using a photo luminescence imaging, characterized in that for determining the shooting magnification in accordance with the size of the LED epi-wafer to shoot the maximum area of the LED epi-wafer. The method according to claim 11 or 13, A measurement step of measuring the intensity and wavelength of the light emitted from the LED epiwafer using a spectrum analyzer, In the image processing step, the LED epiwafer using photoluminescence imaging is characterized in that it corrects the intensity displayed on the plurality of images or images of different LED epiwafers based on the intensity of light measured by the spectrum analyzer. method of inspection.

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