KR101341662B1 - Method for error minimum of between led chip inspection equipment and equipment - Google Patents

Abstract

The present invention relates to a method for minimizing an error between LED chip visual inspection equipment. The present invention: measures the image focus position error, image pixel size error, image uniformity error, and image color error of the multiple pieces of inspection equipment which inspect the fault of LED chip appearance by using a standard specimen; improves reliability between the multiple pieces of inspection equipment because error can be minimized between the multiple pieces of inspection equipment by compensating an obtained image by applying the measured inspection errors; and enables the efficiency improvement of an inspection work and the convenient management of the inspection equipment because unnecessary works which are caused by error are unnecessary to be done. [Reference numerals] (31) Prepare a standard specimen;(32) Measure the inspection error of multiple pieces of inspection equipment by using the standard specimen;(33) Apply a measured image focus position error to the multiple pieces of inspection equipment;(34) Obtain an LED chip image by using the applied focus position error;(35) Inspect all pixels of the obtained image by correcting an image uniformity error and an image color error;(36) Correct a pixel size by applying an image pixel size inspection error to the inspected image;(AA) Start;(BB) End

Description

Minimizing error between LED chip inspection equipment {METHOD FOR ERROR MINIMUM OF BETWEEN LED CHIP INSPECTION EQUIPMENT AND EQUIPMENT}

The present invention relates to a method for minimizing the error between the LED chip inspection equipment, and in particular, to minimize the inspection error between a plurality of the same inspection equipment for inspecting the defect of the LED chip LED to check the defect more accurately The present invention relates to a method for minimizing errors between chip appearance inspection equipment.

In general, the LED chip inspection equipment detects defects such as contamination, foreign matter, scratches, etc. occurring on the exterior of the LED chip as an image, and determines the amount and fire of the LED chip based on the size and color of the detected image defect. When the defects of the exterior of the LED chip are inspected by the above equipment, the exterior of the LED chip is inspected using at least a plurality of equipment to inspect a large amount of chips in a mass production line.

As shown in FIG. 1, inspection apparatuses for performing appearance inspection with at least two or more equipments may include a glass inspection table 1, a lower light 2 for irradiating a lower portion of the glass inspection table 1, and the glass inspection table. The image obtained by the optical system is inspected by a recipe consisting of an optical system consisting of side lighting (3), upper lighting (4), a lens (5), and a camera (6) irradiated from the top and the side of (1).

As such, when inspecting the appearance of the LED chip with the inspection equipments, there is a slight error between the optical systems mounted between the equipments, and these errors cause a difference in the test results between the respective equipments. Let's do it.

Here, the error of the optical system has an error such as sensitivity, color, uniformity in the case of the camera 6 used in the respective equipment, the lens 5 is the error of magnification, distortion, color, uniformity The illumination (2) (3) (4) will have errors of brightness, color, uniformity, and other errors of focal position, these errors of which are mounted on the equipment as well as the optical system itself. It exists in the process.

These error-prone devices perform the LED chip visual inspection by a reference recipe.

However, even if the equipment is inspected with the reference recipe due to the error of the optical system existing in each equipment, an error that is inspected with different sizes, colors, and brightness of one image is generated. Since different test results are displayed on the same sample, the test reliability is deteriorated, and the problem of deteriorating the work efficiency and the work of re-inspection due to a bad judgment due to an error is caused.

So, conventionally, the inspection equipment has been inspected by the operator to modify the recipe for each inspection equipment that has errors. Therefore, even the same inspection equipment has a complicated problem of performing the inspection with each different recipe. Due to this, there is a problem in the management of the inspection equipment due to the presence of different recipes for each equipment.

In addition, according to Patent Publication No. 10-589850 (name: error correction method of the overlay inspection apparatus), by forming a separate measurement pattern on the stage rather than the actual wafer, by measuring the initial measurement value at the time of device setup (setup) Record and periodically, the inspection device automatically compares the difference with the initial measurement value for the measurement pattern, and if the difference occurs, recognizes the difference as the state change amount of the inspection equipment and corrects all errors of the inspection device by correcting the error. It was.

Therefore, the error correction method is to calibrate all the recipes of the inspection apparatus with the measured error by periodically measuring the error according to the state variation of the inspection apparatus, so that every recipe is different for each inspection apparatus, so that it is difficult to manage the inspection apparatus. I still have the problem.

An object of the present invention to solve the above problems is to measure the optical system errors of a plurality of inspection equipment for inspecting the appearance of the LED chip as a reference recipe, and apply the error measured for each equipment when the LED chip inspection with a plurality of inspection equipment By inspecting and calibrating, it is possible to inspect with a minimum number of inspection errors.

Another object of the present invention for solving the above problems is to simplify the management of a plurality of inspection equipment.

Another object of the present invention for solving the above problems is to minimize the inspection error between a plurality of inspection equipment, to improve the work efficiency by reducing the unnecessary inspection work as well as the reliability of the inspection equipment.

Means for solving the above problems are the steps of preparing a reference specimen for measuring the image error of the inspection equipment; Measuring inspection errors of the image focal position, image pixel size, image uniformity, and image color of the plurality of inspection apparatuses with the reference specimen prepared in the step; Applying the image focal position error measured in the step to a plurality of inspection equipment; Acquiring an image of the LED chip to be inspected by the inspection error applied in the step; Inspecting the image by applying the measured image uniformity error and the image color inspection error to all pixels of the image acquired in the step; Correcting the pixel size by applying the image pixel size check error to the image checked in the step;
Image uniformity test error measurement of the plurality of inspection equipment is to check the average brightness of the image obtained by the camera through the lens by irradiating the upper illumination of the inspection equipment to the square plate shape of the reference specimen and the average of the confirmed image brightness It is characterized by measuring the color uniformity error by generating an image.

In the means of the present invention, the reference specimen is formed of a quadrilateral quadrilateral cross vertically horizontally and vertically with a flat plate of glass material, and forms a square shape by plating chromium in the diagonal direction of the quadrilateral quadrangle, The diagonal shape in which the chromium is not plated has a diagonal shape in which a chrome is plated alternately in a horizontal and vertical direction by a square having a predetermined size.

The image focus position inspection error measurement of a plurality of inspection equipment in the means of the present invention is irradiated to the chrome-plated checkerboard shape of a square of a predetermined size of the reference specimen to the image obtained by the camera through the lens The focus position is measured at an illumination level where the brightness contrast is maximum and the sharpness is maximum.

In the means of the present invention, the image pixel size inspection error measurement of a plurality of inspection equipment is a pixel in the image obtained by the camera through the lens by irradiating the lower illumination of the inspection equipment to the chrome plated checkerboard shape into a square of a predetermined size of the reference specimen The image pixel size error is measured by calculating the size of.

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In the means of the present invention, the image color inspection error measurement of a plurality of inspection equipment is obtained by the camera through a lens by illuminating the upper illumination of the inspection equipment to the chrome plated square plate shape of the reference specimen and the average of the obtained image The method generates an image and calculates a color correction value for each of R, G, and B planes of the generated average image to measure color errors.

The effect of the present invention according to the problem is that the image focus position error, image pixel size error, image uniformity error, image uniformity of the plurality of inspection equipment by using a plurality of inspection equipment for inspecting defects of the LED chip appearance By measuring the color error and correcting the obtained image by applying the measured inspection error, it is possible to minimize the error between the plurality of inspection equipment to improve the reliability between the inspection equipment and unnecessary work due to the error Since there is no need to improve the efficiency of the inspection work and further simplify the management of the inspection equipment will be provided.

1 is a schematic diagram of a conventional LED chip inspection equipment
2 is an installation state diagram of the present invention LED chip inspection equipment
Figure 3 is a flow chart of the error minimization method between the present invention LED chip inspection equipment.
Figure 4 is an illustration of the reference specimen used in the present invention LED chip inspection equipment
5 is a flowchart illustrating an image focal position error and an image pixel size error measurement between the LED chip visual inspection equipment of the present invention;
6 is an image uniformity error and image color error measurement flowchart between the present invention LED chip inspection equipment

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is an installation state diagram of the LED chip appearance inspection equipment to which the present invention is applied.

As shown in FIG. 2, the LED chip inspection equipment includes a reference inspection equipment 10 and a number of relative inspection equipments 11n for inspecting the LED chip appearance with the same recipe as the reference inspection equipment 10. .

Therefore, the reference inspection equipment 10 and the plurality of relative inspection equipment (11n), respectively, the inspection of the LED chip appearance, while the image obtained during the reference inspection equipment 10 and a plurality of relative inspection equipment to be described later Inspection is performed by correcting with the image error measured in (11n).

Figure 3 is a flow chart of the method of minimizing the error between the LED chip inspection equipment of the present invention, Figure 4 is an illustration of the reference specimen used in the LED chip inspection equipment of the present invention, Figure 5 is an image between the LED chip inspection equipment of the present invention Focus position error and image pixel size error measurement flowchart, Figure 6 is an image uniformity error and image color error measurement flowchart between the LED chip appearance inspection equipment of the present invention.

As shown in Figure 3, the step (31) of preparing a reference specimen 20 for measuring the image error of the inspection equipment; Measuring the inspection error for the image focus position, image pixel size, image uniformity, image color of the plurality of inspection equipment (10) (11n) with the reference specimen 20 prepared in step 31, respectively (32) ; Applying the image focal position error measured in the step 32 to the plurality of inspection equipment 10 (11n) (33), to obtain an image of the LED chip to be inspected by the inspection error applied in the step 33 Step 34; Inspecting (35) the image by applying the measured image uniformity error and the image color inspection error to all pixels of the image obtained in the step (34); And correcting the pixel size by applying the image pixel size test error to the image examined in the step 35.

The reference specimen 20 is a lower illumination (2), side illumination (3), upper illumination by using a recipe for the reference inspection equipment (1) and a plurality of relative inspection equipment (2n) for inspecting defects of the LED chip appearance (4) The inspection error of the optical system consisting of the lens 5 and the camera 6 is measured.

As shown in FIG. 4, the reference specimen 20 is formed of a rectangular flat plate made of glass, and forms a quadrangular quadrangular cross between the center and the horizontal of the flat plate. Direction to form a rectangular shape by plating chromium (Cr), and in the diagonal direction in which the chromium (Cr) is not plated, form a checkered plate by alternately plating chromium (Cr) horizontally and vertically in a square of a predetermined size. To prepare (step 31).

Thus prepared reference specimen 20 has a large square shape and grid shape, respectively, the lower illumination (2), side illumination (3), upper illumination (4) of the reference inspection device 10 and the plurality of relative inspection equipment (11n) ), Respectively, to obtain images of the light source formed in the square shape and the checkerboard shape of the reference specimen 20 with the lens 5 and the color camera 6, and the reference inspection equipment 10 and a plurality of images. The inspection error is measured for the relative inspection equipment 11n.

At this time, the inspection error is to check the error of the image focusing position, image pixel size, image uniformity, image color with respect to the reference inspection equipment 10 and a plurality of relative inspection equipment (11n), the image in the inspection of the error The inspection error for the uniformity of the image and the color of the image is measured by the image of the light source irradiated to the square shape of the reference specimen 20, the inspection error for the pixel size of the image and the focal position of the image is An inspection error is measured by an image of a light source irradiated to the checkerboard shape of the reference specimen 20 (step 32).

That is, as shown in FIG. 5, the image focus position error measurement of the reference inspection device 10 and the plurality of relative inspection devices 11n is performed by lower illumination of the reference inspection device 10 and the plurality of relative inspection devices 11n. (2) is measured by an image obtained by the camera 6 through the lens 5 by irradiating a checkered plate chrome plated into a square of a predetermined size of the reference specimen 20, wherein the reference specimen 20 In operation 51, the brightness level of the lower illumination 2 is maximized by comparing the brightness between the irradiated portion and the non-irradiated portion through the image.

Here, the illumination level is adjusted from 0 to a maximum of 1000 levels, searching for an illumination level at which the brightness contrast of the lower light 2 is maximized, and searching for an illumination level at which the sharpness of the illumination is maximized to a focus position (step 52). The detected focus position error is compared with the previous focus position to identify the current focus position (step 53).

At this time, the illumination level and the focal position are to determine the maximum illumination level and the focal position by the light and dark of the light formed in the chrome plated portion and the non-plated square with a square of a predetermined size of the reference specimen 20.

When the search and confirmation of the maximum illumination level and the focus position is completed, the size of the pixel in the image obtained by the camera through the lens is irradiated to the chrome plated checkerboard shape with a square of a predetermined size of the reference specimen 20 for the image In this case, the pixel size is calculated by finding the size of each quadrangle of a predetermined size on the reference specimen 20.

That is, the pixel size is calculated by dividing the size of the pixel corresponding to the rectangle by dividing the image formed on the predetermined rectangle of the reference specimen 20 (step 54). The error of the calculated reference focal position and the pixel size error are measured (step 55).

As shown in FIG. 6, the image uniformity error and the image color error of the reference inspection device 10 and the plurality of relative inspection devices 11n are measured by the reference inspection device 10 and the plurality of relative inspection devices. 11n) is irradiated to the chrome-plated square shape of the reference specimen 20 of the upper light 4 of the reference specimen 20 to obtain an image obtained by the camera through the lens (step 61), and confirms the average brightness of the obtained image. (Step 62).

Here, the brightness of the image is adjusted in 0 to 255 steps, where the brightness level is set to 80% as the reference brightness and the brightness is checked while adjusting the upper light (3) to match the reference brightness, but the brightness is 64 The average image is generated by accumulating the times and using the average value of the accumulated brightness (step 63).

Subsequently, a color correction value is calculated for the color (R, G, B) plane of the generated average image, where color (R, G, B) correction is a value obtained by dividing the brightness reference value by the current brightness value for all pixels. Calculate the color correction value (step 64),

As described above, in the state of calculating, measuring, and storing an inspection error value of an optical system with respect to the reference inspection device 10 and the plurality of relative inspection devices 11n, the reference inspection device 10 and the plurality of relative inspection devices ( 11n) put the LED chip to be tested, and as shown in FIG. 3, the reference inspection equipment 10 and the plurality of relative inspection equipment 11n are already calculated and measured, respectively, and shown in FIG. As described above, by applying the measured image focal position error (step 33), an image of the LED chip is obtained using the applied focal position error (step 34).

 The obtained image is calculated and measured at each of the reference inspection equipment 10 and the plurality of relative inspection equipments 11n for all pixels, and as shown in FIG. 6, the measured image uniformity error and image color. The LED chip image is inspected by applying an inspection error of each (step 35), and the tested LED chip image is the reference inspection equipment 10 and the plurality of relative inspection equipment 11n as shown in FIG. The calculated image pixel size check error is applied to the LED chip to correct the image pixel size of the LED chip (step 36).

Therefore, the reference inspection equipment 10 and the plurality of relative inspection equipments 11n having respective inspection errors inspect the LED chip by applying the previously calculated and measured inspection error values, so that the inspection errors between the inspection equipments. The inspection is performed while minimizing the number, which gives reliability of the inspection equipment and makes it easier to manage the inspection equipment by using the same standard recipe among the inspection equipment without changing the recipe of each inspection equipment due to the inspection error. Will be.

In addition, the present invention has been described by applying to the equipment for inspecting the appearance of the LED chip, but is not limited to this is applicable to all inspection equipment for inspecting the appearance of the semiconductor wafer or fluorescent film using the optical system consisting of illumination, lens, camera. Let's find out.

10; Standard inspection equipment 11n; Relative inspection equipment

Claims (6)

Preparing a reference specimen for measuring an image error of an inspection device;
Measuring inspection errors of the image focal position, image pixel size, image uniformity, and image color of the plurality of inspection apparatuses with the reference specimen prepared in the step;
Applying the image focal position error measured in the step to a plurality of inspection equipment;
Acquiring an image of the LED chip to be inspected by the inspection error applied in the step;
Inspecting the image by applying the measured image uniformity error and the image color inspection error to all pixels of the image acquired in the step; And
Correcting the pixel size by applying the image pixel size check error to the image checked in the step;
Image uniformity test error measurement of the plurality of inspection equipment is to check the average brightness of the image obtained by the camera through the lens by irradiating the upper illumination of the inspection equipment to the square plate shape of the reference specimen and the average of the confirmed image brightness Method for minimizing the error between the LED chip inspection equipment, characterized in that it comprises generating an image to measure the color uniformity error. The method of claim 1,
The reference specimen is made of glass and forms a quadrilateral quadrilateral cross vertically and horizontally with a rectangular flat plate, and forms a square shape by plating chromium in a diagonal direction of the quadrilateral quadrangle, and the chromium is not plated. The method of minimizing the error between the LED chip inspection equipment, characterized in that by forming a checkerboard shape by alternately plating chrome in a horizontal and vertical direction with a square of a predetermined size in the diagonal direction. The method of claim 1,
Image focus position inspection error measurement of the plurality of inspection equipment,
Irradiating the lower lights of the inspection equipments to a chrome plated checkerboard with a square of a predetermined size of the reference specimen to search for a focus position with an illumination level that maximizes brightness contrast and maximizes clarity for an image obtained by a camera through a lens. Method of minimizing the error between the LED chip external inspection equipment, characterized in that for measuring the image focus position error. The method of claim 1,
Image pixel size error measurement of the plurality of inspection equipment,
LED is characterized by measuring the pixel size error by calculating the size of the pixel in the image acquired by the camera through the lens by irradiating the lower illumination of the inspection equipment into the square of 200㎛ size of the reference specimen Minimizing error between chip appearance inspection equipment. delete The method of claim 1,
Image color inspection error measurement of the plurality of inspection equipment
The upper illumination of the inspection equipment is irradiated to the chrome plated square plate shape of the reference specimen to acquire an image through a lens, generate an average image of the acquired image, and apply it to each plane of the average image generated The method for minimizing the error between LED chip inspection equipment, characterized in that for calculating the color correction value for the image and measuring the image color error with this correction value.

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