CN116457642A - Wavelength measurement device and wavelength measurement method - Google Patents
Wavelength measurement device and wavelength measurement method Download PDFInfo
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- CN116457642A CN116457642A CN202180075003.XA CN202180075003A CN116457642A CN 116457642 A CN116457642 A CN 116457642A CN 202180075003 A CN202180075003 A CN 202180075003A CN 116457642 A CN116457642 A CN 116457642A
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- 238000005259 measurement Methods 0.000 title claims abstract description 156
- 238000000691 measurement method Methods 0.000 title claims description 9
- 238000004364 calculation method Methods 0.000 claims abstract description 15
- 238000000926 separation method Methods 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 19
- 238000012935 Averaging Methods 0.000 claims description 8
- 238000013461 design Methods 0.000 claims description 6
- 230000005484 gravity Effects 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 12
- 230000005284 excitation Effects 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 238000000295 emission spectrum Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/443—Emission spectrometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0275—Details making use of sensor-related data, e.g. for identification of sensor parts or optical elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J2003/2853—Averaging successive scans or readings
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J2003/2859—Peak detecting in spectrum
- G01J2003/2863—Peak detecting in spectrum and calculating peak area
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- Microelectronics & Electronic Packaging (AREA)
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- Investigating Or Analysing Materials By Optical Means (AREA)
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Abstract
The wavelength measurement device is provided with: a spectroscopic unit (3) that splits light emitted by exciting a plurality of light emitting element chips (101) included in a measurement object (100); a light receiving unit (5) having a plurality of pixels (51) which receive the light emitted from the light emitting surfaces of the light emitting element chips and split into a plurality of areas; a separation unit (6) that separates measurement data obtained based on the light receiving result for each light emitting element chip (101); and a calculation unit (6) for calculating a representative wavelength from measurement data for each wavelength of the plurality of regions in the light emitting surface for each of the separated light emitting element chips (101).
Description
Technical Field
The present invention relates to a wavelength measurement device and a wavelength measurement method for measuring representative wavelengths of light emitting element chips such as a plurality of LED chips included in an object to be measured.
Background
For example, in a backlight LED used for a display such as a television, the variation in color tone causes degradation of image quality such as color unevenness of the display, and thus the emission color is strictly controlled. Therefore, conventionally, a so-called merging process has been performed in which the wavelengths of the LED chips are measured and classified for each color.
As a method of measuring the wavelength of the LED chips by combining the above, non-patent document 1 discloses measuring the LED chips individually by using a spot spectrometer.
Non-patent document 1: otsuka electronic company homepage application example "color Classification (LE series) of LED manufacturing Process" URL https:// www.otsukael.jp/appcase/detail/case/116
However, the method of individually measuring the representative wavelength of the LED chips one by one using a point spectrometer as in the technique described in non-patent document 1 has the following problems.
That is, for example, as for a micro LED chip having a size of 100 μm or less, the smaller the size of the LED chip, the larger the number of LED chips to be measured, which takes time to perform the measurement on a chip-by-chip basis, and the efficiency is not high.
In addition, in the case of measurement on a wafer, if the size of the LED chip is small, there is a problem that a plurality of LED chips are included in a measurement region of the spot spectrometer, and measurement with high accuracy cannot be performed.
Disclosure of Invention
The present invention has been made in view of such a technical background, and an object thereof is to provide a wavelength measurement device and a wavelength measurement method that can efficiently and accurately measure representative wavelengths of a plurality of LED chips.
The above object is achieved in the following manner.
(1) A wavelength measurement device is provided with:
a spectroscopic unit that splits light emitted by a plurality of light emitting element chips included in a measurement object when excited;
a light receiving unit having a plurality of pixels for receiving light emitted from the light emitting surfaces of the light emitting element chips and split by the light splitting unit in a plurality of areas;
a separation unit configured to separate measurement data obtained based on a light receiving result of the light receiving unit for each of the light emitting element chips; and
and a calculation unit configured to calculate a representative wavelength from measurement data for each wavelength of the plurality of regions in the light emitting surface for each light emitting element chip separated by the separation unit.
(2) According to the wavelength measurement device described in the foregoing item (1), the calculation means averages measurement data of a region in which a maximum value is obtained for a predetermined wavelength and one or more regions adjacent to the region among the measurement data in the light emitting surface, and calculates a representative wavelength from the measurement data for each wavelength after the averaging.
(3) The wavelength measurement device according to the above item (2), wherein the predetermined wavelength is any one of a wavelength having a maximum brightness among data of a pixel group including an appropriate region of measurement data of a plurality of light emitting element chips, a wavelength having a maximum brightness among measurement data of a data region of one light emitting element chip, and a design wavelength of a light emitting element chip.
(4) The wavelength measurement device according to any one of the preceding items (1) to (3), wherein the light receiving means is a region sensor,
each pixel of one pixel row of the area sensor corresponds to a plurality of areas in the one-dimensional direction of the object to be measured, and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from the plurality of areas in the one-dimensional direction and split into light beams.
(5) The wavelength measurement device according to item (4), wherein the wavelength measurement device includes a moving unit that relatively moves at least one of the object to be measured and the wavelength measurement device in a direction orthogonal to both the one pixel row and the other pixel row,
the area sensor receives the split light from each area of the object to be measured in the two-dimensional direction by measuring while moving at least one of the object to be measured and the wavelength measuring device by the moving means.
(6) The wavelength measurement device according to any one of the preceding items (1) to (5), wherein the representative wavelength is a light emission peak wavelength.
(7) The wavelength measurement device according to any one of the preceding items (1) to (5), wherein the representative wavelength is a center of gravity wavelength.
(8) The wavelength measurement device according to any one of the preceding items (1) to (5), wherein the representative wavelength is a center wavelength.
(9) The wavelength measurement device according to any one of the above (1) to (8), wherein the light emitting element chip is an LED chip.
(10) The wavelength measurement device according to any one of the preceding items (1) to (9), wherein the wavelength measurement device includes a light source unit that excites the plurality of light emitting element chips and causes the plurality of light emitting element chips to emit light.
(11) A wavelength measurement method is provided with:
a spectroscopic step of spectroscopic light emitted by exciting a plurality of light emitting element chips included in the object to be measured by a spectroscopic unit;
a light receiving step of receiving light emitted from the light emitting surfaces of the light emitting element chips and split by the light splitting step by a plurality of pixels of a light receiving unit in a plurality of areas;
a separation step of separating measurement data obtained based on a light receiving result of the light receiving step for each of the light emitting element chips; and
and a calculation step of calculating a representative wavelength from measurement data for a plurality of regions in the light emitting surface for each of the light emitting element chips separated by the separation step.
(12) According to the wavelength measurement method described in the foregoing item (11), in the calculation step, the measurement data of the region in which the maximum value is obtained for the predetermined wavelength and one or more regions adjacent to the region among the measurement data in the light emitting surface are averaged, and the representative wavelength is calculated from the measurement data for each wavelength after the averaging.
(13) The wavelength measurement device according to the item (1), wherein the predetermined wavelength is any one of a wavelength having a maximum brightness among data of a pixel group including an appropriate region of measurement data of a plurality of light-emitting element chips, a wavelength having a maximum brightness among measurement data of a data region of one light-emitting element chip, and a design wavelength of a light-emitting element chip.
(14) The method for measuring a wavelength according to any one of the preceding items (11) to (13), wherein the light receiving unit is a region sensor,
one pixel row of the area sensor receives light from each area in the one-dimensional direction of the object to be measured, and the other pixel row orthogonal to the one pixel row receives light after light splitting corresponding to each area in the one-dimensional direction.
(15) The method for measuring a wavelength according to item (14) above, wherein the method for measuring a wavelength includes a moving step of relatively moving at least one of the area sensor and the object to be measured in the direction of the other pixel row,
the area sensor receives light from each area in the two-dimensional direction of the object to be measured by movement of at least one of the area sensor and the object to be measured based on the movement step.
(16) The method for measuring a wavelength according to any one of the preceding items (11) to (15), wherein the representative wavelength is a light emission peak wavelength.
(17) The method for measuring a wavelength according to any one of the preceding items (11) to (15), wherein the representative wavelength is a center of gravity wavelength.
(18) The method for measuring a wavelength according to any one of the preceding items (11) to (15), wherein the representative wavelength is a center wavelength.
(19) The method for measuring a wavelength according to any one of the preceding items (11) to (18), wherein the light-emitting element chip is an LED chip.
According to the inventions described in the foregoing items (1) and (11), the plurality of light emitting element chips included in the object to be measured are excited to emit light, and the light emitted from the light emitting surface of each light emitting element chip and split by the light splitting means is received by the plurality of pixels of the light receiving means in a plurality of areas. The measurement data obtained based on the light receiving result is separated for each light emitting element chip, and the representative wavelength is calculated from the measurement data for each wavelength of the plurality of regions in the light emitting surface for each separated light emitting element chip.
In this way, since the representative wavelength is calculated for each light emitting element chip using measurement data when a plurality of light emitting element chips are excited at one time to emit light, the measurement time can be shortened and the measurement efficiency can be improved as compared with the case where the representative wavelengths of the light emitting element chips are individually measured one by one using a point spectrometer. Further, since the representative wavelength is calculated from the measurement data for a plurality of regions in the light emitting surface of the light emitting element chip, a measurement result with high accuracy can be obtained without variation.
According to the inventions described in the foregoing items (2) and (12), the measurement data of the region in which the maximum value is obtained for the predetermined wavelength and the one or more regions adjacent to the region among the measurement data in the light emitting surface are averaged, and the representative wavelength is calculated from the measurement data for each wavelength after the averaging, so that the representative wavelength with high accuracy can be easily obtained.
According to the inventions described in the foregoing items (3) and (13), the wavelength having the maximum brightness among the data of the pixel group of the appropriate region including the measurement data of the plurality of light emitting element chips, the wavelength having the maximum brightness among the measurement data of the data region of one light emitting element chip, and the measurement data of the region in which the maximum value is obtained among the design wavelengths of the light emitting element chips and one or more regions adjacent to the region are averaged.
According to the inventions described in the foregoing items (4) and (14), the light from each region in the one-dimensional direction of the object to be measured can be received by one pixel row of the area sensor, and the light after the light splitting corresponding to each region in the one-dimensional direction can be received by the other pixel row orthogonal to the one pixel row.
According to the inventions described in the foregoing items (5) and (15), by moving at least one of the object to be measured and the wavelength measuring device, the area sensor can receive the split light from each area of the object to be measured in the two-dimensional direction.
According to the inventions described in the foregoing items (6) and (16), the emission peak wavelength can be measured as the representative wavelength.
According to the inventions described in the foregoing items (7) and (17), the barycentric wavelength can be measured as the representative wavelength.
According to the inventions described in the foregoing items (8) and (18), the center wavelength can be measured as the representative wavelength.
According to the inventions described in the foregoing items (9) and (19), the representative wavelength of each LED chip can be calculated using measurement data when a plurality of LED chips are excited at one time and emit light.
According to the invention described in the aforementioned item (10), the plurality of light-emitting element chips can be excited by the light source section and can emit light.
Drawings
Fig. 1 is a block diagram showing the configuration of a wavelength measurement device according to an embodiment of the present invention.
Fig. 2 is a perspective view showing a specific configuration of a part of the wavelength measurement device of fig. 1.
Fig. 3 is a diagram for explaining a relationship between the sizes of the pixels of the light receiving unit and the plurality of LED chips on the measurement object.
Fig. 4 schematically shows a light receiving state in each pixel when light of an arbitrary wavelength among light received from the surface of the measurement object is received by the light receiving means.
Fig. 5 (a) is a diagram showing a state in which measurement data in each pixel is separated for each light emitting element chip, fig. 5 (B) is a diagram for explaining a calculation method of a representative wavelength, and fig. 5 (C) is an enlarged diagram of fig. 5 (B).
Fig. 6 is a spectrum diagram depicting the average value of 9 pixels for each wavelength for the data regions of the plurality of light emitting element chips.
Fig. 7 is a spectrum diagram depicting values of 1 pixel for each wavelength for data regions of a plurality of light emitting element chips.
Fig. 8 is a graph depicting an average value of 9 pixels calculated for each wavelength for a data region of one light emitting element chip, and a fitted curve based on the average value.
Fig. 9 is a diagram for explaining a measurement method for a measurement object having a wide measurement range.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Fig. 1 is a block diagram showing the configuration of a wavelength measurement device according to an embodiment of the present invention. In this embodiment, a case will be described in which the light emitting element chip is an LED chip, and the object to be measured 100 is a wafer on which a plurality of LED chips are formed.
The wavelength measurement device shown in fig. 1 includes: the light source 1 for excitation, the objective lens 2 capable of changing magnification, the spectroscopic unit 3, the imaging lens 4, the area sensor 5 which is a two-dimensional imaging element constituted by a CCD sensor or the like, the calculation unit 6, and the measurement result display unit 7 constituted by a liquid crystal display device or the like.
The excitation light source 1 irradiates a plurality of LED chips on the object to be measured 100 with excitation light, and excites the plurality of LED chips to emit light.
The spectroscopic unit 3 splits the light from each LED chip passing through the objective lens 2 for each wavelength, and the imaging lens 4 images the light of each wavelength split by the spectroscopic unit 3 on the area sensor 5. In this embodiment, each wavelength is split at a wavelength interval of 5nm.
The area sensor 5 corresponds to a light receiving section, and includes a plurality of pixels 51 arranged vertically and horizontally as shown in fig. 2. The lateral direction (Y direction in fig. 2) of the area sensor 5 means the lateral direction of the physical space, and each pixel 51 in the lateral direction corresponds to the lateral area of the object to be measured. On the other hand, the longitudinal direction (Z direction in fig. 2) of the area sensor 5 corresponds to the brightness (luminance) of each wavelength of light. That is, each pixel 51 of the horizontal pixel row corresponds to a plurality of regions in the one-dimensional direction of the object 100 to be measured, and light which is emitted from each region and subjected to wavelength decomposition is received by each pixel 51 of the vertical pixel row. Therefore, in order to perform the spectroscopic measurement of each region in the two-dimensional direction (plane) of the object 100, it is necessary to perform the spectroscopic measurement while moving the object 100 in the Z direction of fig. 2. Alternatively, the wavelength measurement device may be moved in the Z direction of fig. 2 without moving the object 100, or both the object 100 and the wavelength measurement device may be moved with a speed difference, or in other words, at least one of the object 100 and the wavelength measurement device may be moved relative to the other in the Z direction of fig. 2. In this embodiment, the object 100 is moved, and as shown in fig. 1, a moving device 300 is provided that can move the table 200 on which the object 100 is placed in the Z direction.
The technique of dividing the plane of the object 100 into regions having a size corresponding to the pixels 51 of the area sensor 5, and splitting light from the regions to be received by the pixels 51 of the area sensor 5 is known as, for example, a hyperspectral camera.
As necessary, measurement data of the electric signals output from the pixels 51 of the area sensor 5 are converted into digital signals by a current/voltage (IV) conversion circuit and an analog/digital (AD) conversion circuit, which are not shown, and sent to the arithmetic unit 6. The calculation unit 6 calculates the representative wavelength for each of the plurality of LED chips on the measurement object by using the transmitted measurement data, by a CPU or the like. Details of the calculation method of the representative wavelength will be described later.
The measurement result display unit 7 displays the calculation result by the calculation unit 6. The conversion of the measurement data output from the area sensor 5 into a digital signal may be performed by the arithmetic unit 6.
The arithmetic unit 6 may be a dedicated device or may be a personal computer. The measurement data outputted from the area sensor 5 and processed into a digital signal may be transmitted to the arithmetic unit 6 via a network. In this case, even if the computing unit 6 is located at a place distant from the measurement place, the representative wavelength of the LED chip can be measured.
Next, a method of measuring the representative wavelength of each LED chip on the wafer as the measurement object 100 by the wavelength measuring apparatus shown in fig. 1 will be described.
Fig. 3 is a diagram for explaining a relationship between the plurality of LED chips 101 on the measurement object 100 and the size of the pixel 51 of the area sensor 5. The horizontal axis of the fine grid of fig. 3 is the space Y direction of fig. 2, and the vertical axis is the space X direction generated by scanning the LED chip 101 in the wavelength Z direction. The size of one cell is a measurement area, and corresponds to the size of the pixel 51.
The LED chips 101 are shown as rectangles, and are arranged vertically and horizontally on the object 100 to be measured. The rectangular region directly serves as a light emitting surface of each LED chip 101.
The arrangement pitch of the LED chips 101, the pitch of the pixels 51 of the area sensor 5, the magnification of the objective lens 2, and the like are set so that data can be acquired by using the plurality of pixels 51 for the light emitting surface of one LED chip 101, that is, light emitted from a plurality of areas of the light emitting surface of one LED chip 101, the areas corresponding to the pixels 51, can be received by using the plurality of pixels 51 corresponding to each other. In this embodiment, the light from the light emitting surface of one LED chip 101 is set to be received so as to be divided into pixels of 3×3=9 pixels or more.
Next, excitation light is irradiated from the excitation light source 1 onto the measurement object 100 mounted on the stage 200, and the stage 200 is moved in the Z direction of fig. 2 by the moving device 300, and light emitted from the plurality of LED chips 101 on the measurement object 100 is received by the pixels 51 of the area sensor 5. The light emitted from the LED chip 101 is split by the splitter 3 at a predetermined wavelength, and the split light of each wavelength is received by each pixel 51. The value (luminance value) of each pixel 51 after receiving the light is transmitted as measurement data to the operation unit 6, and stored in a memory (not shown) in the operation unit 6. Further, since the object 100 on the stage 200 is moved in the Z direction of fig. 2 by the moving device 300 and is measured, measurement data for each wavelength after the light is split is obtained for each region corresponding to the pixels in the two-dimensional direction, in other words, the plane, of the object 100.
Based on the measurement data thus obtained, the calculation unit 6 calculates the representative wavelength of each LED chip 101.
Fig. 4 schematically shows the light receiving state in each pixel 51 when light of an arbitrary wavelength among the light received from the surface of the measurement object 100, for example, light of a wavelength λ having the maximum brightness among data of a pixel group of an appropriate area including measurement data of the plurality of LED chips 101 is received by the area sensor 5. The lateral direction of fig. 4 is the spatial Y direction of fig. 2, and the longitudinal direction is data of the spatial X direction obtained by scanning the LED chip 101 in the Z direction. The black frame 8 shown in fig. 4 indicates a region corresponding to the light emitting surface of one LED chip 101. The region 9 shown in a thicker state has a stronger brightness, and the brightness is shown to be weaker as it goes to the periphery.
Next, the measurement data received by each pixel 51 of the area sensor 5 is separated for each LED chip 10. This separation can be performed, for example, as follows. That is, the wavelength λ having the maximum brightness is obtained from the data of the pixel group in the appropriate region including the measurement data of the plurality of LED chips 101. Next, at the wavelength λ, each pixel 51 may be classified into a class according to brightness, and image processing may be performed using a certain brightness class as a threshold value, thereby separating the LED chips 101. Fig. 5 (a) shows a state in which measurement data in each pixel 51 is separated for each LED chip 101. In fig. 5 (a), 9 data areas 10a to 10i indicated by black boxes are separated.
Next, a pixel of interest that obtains the maximum value of brightness (luminance value) is specified for the measurement data of each LED chip 101 after separation. For example, as shown in fig. 5B, in measurement data for a data area (for example, the data area 10B) of one LED chip 101, if the maximum value is obtained by the pixel 51a at a certain wavelength, the pixel 51a is determined as the pixel of interest.
Here, a certain wavelength is only a wavelength used for finding a separation brightness level or a pixel of interest, and for example, as described above, a wavelength having the maximum brightness among data of a pixel group of an appropriate area including measurement data of a plurality of LED chips 101, a wavelength having the maximum brightness among measurement data of a data area of one LED chip, a design wavelength of a light emitting element chip, and the like can be cited.
After the pixel of interest 51a is determined, the value of the pixel of interest 51a and the value of one or more pixels around the pixel of interest 51a are averaged to become spectral data of the wavelength (brightness data at the wavelength). In the example of fig. 5 (B), as shown in fig. 5 (C), the values of 8 pixels 51B to 51i around the pixel of interest 51a and 9 pixels 51 in total are averaged.
By averaging the data of the plurality of pixels including the target pixel 51a in this manner, the effect of reducing the measurement noise can be obtained. The explanation about this is as follows.
That is, the emission wavelength of a self-light emitting element is an important factor determining the characteristics of the element. The self-luminous elements mainly include LEDs and OLEDs (Organic Light Emitting Diode: organic light emitting diodes). Compared with an OLED, the LED has a relatively uniform light-emitting wavelength at any position in a light-emitting surface in principle. Therefore, in the case of an LED, the representative wavelength of the LED can be measured at any position within the light emitting surface, and the effect of reducing the measured noise can be obtained by averaging the data obtained by dividing the area. However, the light emitting element chip is not limited to the LED chip 101, and may be an OLED.
The average pixel is set as a pixel around the target pixel 51a so that the measurement region of the wavelength of the LED chip 101 is converged in the light emitting surface, and a value having little influence of the variation can be obtained with a relatively small amount of data. Specifically, if a value including the surrounding 9 pixels of the target pixel 51a indicating the maximum brightness is used, a value having sufficiently little influence of the deviation can be obtained.
The reason why the LED has a relatively uniform emission wavelength at any position in the light emitting surface as compared with the OLED is as follows.
That is, the emission wavelength of the LED is determined by the energy band gap (Eg) of the compound semiconductor material, and is represented by the following formula.
λ(nm)＝1240/Eg(eV)
For example, gaAs (gallium arsenide) is eg=1.4 (eV) (at a temperature of 300K), and therefore the emission wavelength λ is 885nm. Eg is determined by the composition of the compound semiconductor material constituting the LED, and thus it can be said that the variation in the material composition becomes a factor of the variation in the emission wavelength. On the other hand, the basic principle of the OLED is also the same as that of the LED, and therefore, it can be said that the variation in the material composition becomes a factor of the variation in the emission wavelength. Also, in the case of the OLED, since it has a relatively wide light emission spectrum, the spectrum is steeped by using a microcavity structure to improve color purity. Since the microcavity structure utilizes the resonance effect of light between the upper and lower electrodes of the organic light-emitting layer, it can be said that the variation in the film thickness of the organic light-emitting layer is a factor of the variation in the emission wavelength.
That is, since the LED has less deviation factor than the OLED, the deviation of the emission wavelength in the light emitting surface of the chip is small.
Fig. 6 is a spectrum diagram showing the average value of 9 pixels at each wavelength for four data areas 10b, 10d, 10f, and 10h among the data areas 10a to 10i of the plurality of LED chips 101 shown in fig. 5 (a). On the other hand, fig. 7 is a spectrum diagram depicting the values of the only-focused pixel 51a obtained for each wavelength for the four data regions 10b, 10d, 10f, and 10h, which are the same data regions. In each graph, the horizontal axis represents wavelength, and the vertical axis represents brightness. When the two graphs are compared, it is found that the spectral shape of only the value of the pixel of interest 51a shown in fig. 7 is destroyed.
The luminance values of the target pixel 51a and the surrounding pixels 51b to 51i are averaged for each wavelength, and a representative wavelength is obtained from the average value of each wavelength obtained. Specifically, as shown in fig. 8, a fitting curve is obtained by gaussian fitting or the like based on the average value of the respective wavelengths, and the wavelength of the peak of the fitting curve is taken as a representative wavelength. In addition, in the case where the wavelength interval is small, the wavelength of the largest average value among the average values of the respective wavelengths may be used as the representative wavelength without fitting.
In this way, the representative wavelength is calculated from the measurement data for all the LED chips 101 of the measurement object 100. The representative wavelength calculated in this embodiment is the emission peak wavelength, but may be the center of gravity wavelength, the center wavelength, or the like. The barycentric wavelength is a weighted average of wavelengths having the emission spectrum as a weight. In other words, the center of gravity wavelength is a value obtained by dividing a value obtained by integrating the product of each wavelength and the intensity of light of that wavelength over the entire region of the emission wavelength by a value obtained by integrating the intensity of light over the entire region of the emission wavelength. The center wavelength is the average value of the two half-value wavelengths obtained by reducing the maximum amplitude of the peak wavelength by 3 dB.
Next, the measurement repetition accuracy of the representative wavelength calculated as described above is compared with that obtained from the value of the pixel of interest 51a alone when the measurement repetition accuracy is calculated from the average value of 9 pixels including the pixel of interest 51a for each wavelength. The measurement of the LED chip 101 was repeated 10 times, and the average value of 9 pixels was calculated for each wavelength for one data area of the LED chip 101, and the representative wavelength of 10 times calculated from the peak position of each obtained fitting curve was shown in (a) of table 1. Further, a process of calculating only the value of the pixel of interest 51a for each wavelength is performed, and the representative wavelength calculated 10 times from the peak positions of the fitting curves obtained individually is shown in (B) of table 1.
TABLE 1
(A) 9 pixel averaging
| No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | max | min | △ | STDEV | ve |
| Maximum value | 226.94 | 234.56 | 235.64 | 228.35 | 232.78 | 235.86 | 238.17 | 238.17 | 227.7 | 220.52 | 238.17 | 220.52 | 17.65 | 5.78 | 231.87 |
| Peak position | 626.7 | 626.6 | 626.6 | 626.82 | 626.43 | 626.52 | 626.81 | 626.81 | 626.62 | 626.79 | 626.82 | 626.43 | 0.39 | 0.14 | 626.67 |
(B) 1 pixel
| No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | max | min | △ | STDEV | ave |
| Maximum value | 269.27 | 226.12 | 208.94 | 243.7 | 205.14 | 255.96 | 226.66 | 230.73 | 212.58 | 227.14 | 269.27 | 205.14 | 64.13 | 20.55 | 230.62 |
| Peak position | 626.61 | 626.94 | 626.18 | 626.78 | 626.19 | 627.29 | 626.74 | 627.33 | 627.16 | 627.12 | 627.33 | 626.18 | 1.15 | 0.42 | 626.83 |
In table 1, "maximum value" refers to the maximum value of the fitted curve, and "peak position" refers to the peak wavelength, i.e., the representative wavelength, at which the maximum value of the curve is fitted. In the method of calculating the representative wavelength by focusing on only 1 pixel in (B) of table 1, the difference (Δ) between the maximum value (max) and the minimum value (min) of the representative wavelength is 1.15, the standard deviation based on the STDEV function is 0.42, and the average value (ave) is 626.83. In contrast, in the method of calculating the representative wavelength from the average value of 9 pixels in (a) of table 1, the difference (Δ) between the maximum value (max) and the minimum value (min) of the representative wavelength is 0.39, the standard deviation based on the STDEV function is 0.14, the average value (ave) is 626.67, the deviation is small, and the convergence in 3σ is less than about 0.5nm.
When the measurement range of the object to be measured 100 is wider than the one-time measurement area 11 shown by a rectangle in fig. 9 and the measurement of the entire measurement range cannot be completed by 1-time measurement, at least one of the measurement symmetry 100 and the measurement device is moved after measuring the representative wavelength for each LED chip 101 in the measurement area 11, and the measurement area 11 is moved to the next measurement site to perform the measurement, and the measurement may be repeated sequentially. In fig. 9, the moving direction of the measurement region 11 is indicated by solid arrows and broken arrows, and the measurement region 11 is sequentially moved from left to right and from top to bottom.
As described above, in the present embodiment, the plurality of LED chips 101 included in the object to be measured 100 are excited at a time to emit light, and the light emitted from the light emitting surface of each LED chip 101 and split by the splitting unit 3 is received by the plurality of pixels 51 of the area sensor 5 in a plurality of areas. The measurement data obtained based on the light receiving result is separated for each LED chip 101, and the representative wavelength is calculated from the measurement data for each wavelength of the plurality of regions in the light emitting surface for each separated LED chip 101.
In this way, since the representative wavelength is calculated for each LED chip 101 using measurement data when the plurality of LED chips 101 are excited at one time to emit light, the measurement time can be shortened and the measurement efficiency can be improved as compared with the case where the representative wavelengths of the LED chips 101 are individually measured one by one using a point spectrometer. Further, since the representative wavelength is calculated from the averaged measurement data for each wavelength by averaging the measurement data of the region where the maximum value is obtained and the measurement data of one or more regions adjacent to the region in the light emitting surface of the LED chip 101, the variation can be eliminated and the representative wavelength with high accuracy can be easily obtained.
The present application is accompanied by the claims of priority from japanese patent application publication No. 2020-186652, filed 11/9 in 2020, the disclosure of which forms a part of the present application directly.
Industrial applicability
The present invention can be used as a wavelength measuring device for measuring representative wavelengths of light emitting element chips such as a plurality of LED chips included in an object to be measured.
Reference numerals illustrate: 1 … light source for excitation; 2 … objective; 3 … spectroscopic part; 4 … imaging lens; 5 … area sensor; 51 … pixels; 51a … focus on pixels; 51b to 51i …; a 6 … arithmetic unit; 7 … measurement result display unit; 10 a-10 i … data areas; 100 … object to be measured; 101 … light emitting element chip (LED chip); 200 … workbench; 300 ….
Claims (19)
1. A wavelength measurement device is provided with:
a spectroscopic unit that splits light emitted by a plurality of light emitting element chips included in a measurement object when excited;
a light receiving unit having a plurality of pixels for receiving light emitted from the light emitting surfaces of the light emitting element chips and split by the light splitting unit in a plurality of areas;
a separation unit that separates measurement data obtained based on a light receiving result of the light receiving unit for each of the light emitting element chips; and
and a calculation unit configured to calculate a representative wavelength from measurement data for each wavelength of the plurality of regions in the light emitting surface for each light emitting element chip separated by the separation unit.
2. The wavelength measurement device according to claim 1, wherein,
the calculation unit averages measurement data of a region in which a maximum value is obtained for a predetermined wavelength and one or more regions adjacent to the region among the measurement data in the light emitting surface, and calculates a representative wavelength from the measurement data for each wavelength after the averaging.
3. The wavelength measurement device according to claim 2, wherein,
the predetermined wavelength is any one of a wavelength having the maximum brightness among data of a pixel group of an appropriate region including measurement data of a plurality of light emitting element chips, a wavelength having the maximum brightness among measurement data of a data region of one light emitting element chip, and a design wavelength of the light emitting element chip.
4. The wavelength measurement device according to claim 1 to 3, wherein,
the light receiving unit is an area sensor,
each pixel of one pixel row of the area sensor corresponds to a plurality of areas in a one-dimensional direction of the object to be measured, and each pixel of another pixel row orthogonal to the one pixel row receives light emitted from the plurality of areas in the one-dimensional direction and split.
5. The wavelength measurement device according to claim 4, wherein,
the wavelength measuring device includes a moving unit that relatively moves at least one of the object to be measured and the wavelength measuring device in a direction orthogonal to both the one pixel row and the other pixel row,
the area sensor receives the split light from each area of the object to be measured in the two-dimensional direction by measuring while at least one of the object to be measured and the wavelength measuring device is moved by the moving means.
6. The wavelength measurement device according to any one of claims 1 to 5, wherein,
the representative wavelength is a light emission peak wavelength.
7. The wavelength measurement device according to any one of claims 1 to 5, wherein,
the representative wavelength is the center of gravity wavelength.
8. The wavelength measurement device according to any one of claims 1 to 5, wherein,
the representative wavelength is a center wavelength.
9. The wavelength measurement device according to any one of claims 1 to 8, wherein,
the light emitting element chip is an LED chip.
10. The wavelength measurement device according to any one of claims 1 to 9, wherein,
the wavelength measurement device includes a light source unit that excites the plurality of light emitting element chips and causes the plurality of light emitting element chips to emit light.
11. A wavelength measurement method is provided with:
a spectroscopic step of spectroscopic light emitted by exciting a plurality of light emitting element chips included in the object to be measured by a spectroscopic unit;
a light receiving step of receiving light emitted from each light emitting surface of the plurality of light emitting element chips and split by the light splitting step by a plurality of pixels of a light receiving unit in a plurality of areas;
a separation step of separating measurement data obtained based on a light receiving result of the light receiving step for each of the light emitting element chips; and
and a calculation step of calculating a representative wavelength from measurement data for a plurality of regions in the light emitting surface for each of the light emitting element chips separated by the separation step.
12. The method for measuring a wavelength according to claim 11, wherein,
in the calculating step, measurement data of a region in which a maximum value is obtained for a predetermined wavelength and one or more regions adjacent to the region among the measurement data in the light emitting surface is averaged, and a representative wavelength is calculated from the averaged measurement data for each wavelength.
13. The method for measuring a wavelength according to claim 12, wherein,
the predetermined wavelength is any one of a wavelength having the maximum brightness among data of a pixel group of an appropriate region including measurement data of a plurality of light emitting element chips, a wavelength having the maximum brightness among measurement data of a data region of one light emitting element chip, and a design wavelength of the light emitting element chip.
14. The wavelength measurement device according to any one of claims 11 to 13, wherein,
the light receiving unit is an area sensor,
one pixel row of the area sensor receives light from each area in the one-dimensional direction of the object to be measured, and the other pixel row orthogonal to the one pixel row receives light after light splitting corresponding to each area in the one-dimensional direction.
15. The method for measuring a wavelength according to claim 14, wherein,
the wavelength measurement method includes a moving step of relatively moving at least one of the area sensor and the measurement object in the direction of the other pixel row,
the area sensor is configured to receive light from each area in the two-dimensional direction of the object to be measured by movement of at least one of the area sensor and the object to be measured in the moving step.
16. The wavelength measurement device according to any one of claims 11 to 15, wherein,
the representative wavelength is a light emission peak wavelength.
17. The wavelength measurement device according to any one of claims 11 to 15, wherein,
the representative wavelength is the center of gravity wavelength.
18. The wavelength measurement device according to any one of claims 11 to 15, wherein,
the representative wavelength is a center wavelength.
19. The wavelength measurement device according to any one of claims 11 to 18, wherein,
the light emitting element chip is an LED chip.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020-186652 | 2020-11-09 | ||
| JP2020186652 | 2020-11-09 | ||
| PCT/JP2021/040846 WO2022097726A1 (en) | 2020-11-09 | 2021-11-05 | Wavelength measuring device, and wavelength measuring method |
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| KR (1) | KR20230079215A (en) |
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| EP3644045A1 (en) * | 2018-10-26 | 2020-04-29 | Julius-Maximilians-Universität Würzburg | Hyperspectral imaging for spectral and spatial characterization of quantum dots |
| US10801953B2 (en) * | 2019-01-11 | 2020-10-13 | Kla-Tencor Corporation | Semiconductor metrology based on hyperspectral imaging |
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