CN116046800A - Wafer inspection apparatus, wafer inspection method, computer-readable storage medium, and electronic device - Google Patents

Abstract

Embodiments of the present invention provide a wafer inspection device, method, computer-readable storage medium, and electronic equipment, which belong to the technical field of optical inspection. The wafer detection device includes a measurement component, a detection circuit and a scanning table. The measurement component includes an illumination unit and a reflection measurement unit. light, and the reflected light is divided into the first detection light and the second detection light; the detection circuit is used to detect wafer surface defects and film thickness according to the reflected light of the measurement component, the detection circuit includes an adder and a divider, and the adder is used to The analog signal of the first detection light is added to the analog signal of the second detection light, and the divider is used for dividing the analog signal of the first detection light and the analog signal of the second detection light; the scanning table is used for placing the wafer. The wafer inspection device can quickly and simultaneously complete wafer surface defect inspection and film thickness inspection.

Description

Wafer inspection device, method, computer-readable storage medium, and electronic equipment

technical field

The present invention relates to the technical field of optical detection, in particular to a wafer detection device, a wafer detection method, a computer-readable storage medium and an electronic device.

Background technique

With the development of semiconductor device technology, the integration of chips is getting higher and higher, and defect detection has become an indispensable means to improve semiconductor yield. Wafer surface defects and uneven film thickness will cause a drop in yield. Prior art spot-scan based defect detection systems specifically direct a beam of radiation onto the surface of a semiconductor material, then collect and analyze the reflected or scattered light from the surface, quantify surface features for absence detection, It is sensitive to surface defects such as scratches, but it cannot detect the film thickness on the wafer surface, and its detection sensitivity to contamination defects is also low. On the other hand, the inspection speed of the traditional photometric ellipsometer with high-precision film thickness measurement performance cannot meet the wafer inspection productivity requirements.

The invention provides a wafer detection device and a wafer detection method. The wafer detection device can detect wafer surface defects and film thickness simultaneously, quickly and with high precision through multiplexing of optical paths, and at the same time through an adder and a divider The device analog signal processing circuit improves the synchronization of dual-channel signal detection and improves the detection accuracy of defects and film thickness.

Contents of the invention

The purpose of the embodiment of the present invention is to provide a wafer inspection device and a wafer inspection method, the wafer inspection device can quickly and simultaneously complete the wafer surface defect detection and film thickness detection.

In order to achieve the above purpose, in the first aspect, an embodiment of the present invention provides a wafer inspection device, including a measurement component, a detection circuit, and a scanning table;

The measurement assembly includes an illumination unit and a reflection measurement unit, the illumination unit is used to provide illumination focused light for the wafer detection area, and the reflection measurement unit is used to receive the reflected light from the wafer surface and divide the reflected light into second a detection light and a second detection light;

The detection circuit is used to detect wafer surface defects and film thickness according to the reflected light of the measurement component;

The scanning table is used for placing wafers.

Preferably, the detection circuit includes a microprocessor, an adder and a divider;

The adder is used to add the analog signal of the first detection light to the analog signal of the second detection light to obtain the reflectivity of the detection position;

The divider is used to divide the analog signal of the first detection light by the analog signal of the second detection light to obtain the ellipsometric parameter relational expression of the detection position;

The microprocessor is used to obtain the result of the defect on the wafer surface according to the reflectivity, and obtain the result of the film thickness of the wafer according to the relational formula of the ellipsometric parameter.

Preferably, the detection circuit further includes a first photodetector, a second photodetector, a first analog-to-digital converter and a second analog-to-digital converter;

The output terminals of the first photodetector are respectively connected to the adder and the divider, and the output terminals of the second photodetector are respectively connected to the adder and the divider; the input terminals of the first analog-to-digital converter are connected to the Adder, the output end of the first analog-to-digital converter is connected to the input end of the microprocessor, the input end of the second analog-to-digital converter is connected to the divider, and the input end of the second analog-to-digital converter is connected to the The output terminal is connected to the input terminal of the microprocessor.

Preferably, the illumination unit includes a laser, a laser beam expander, a half-wave plate and a first focusing mirror, the laser beam expander is arranged below the laser, and two laser beam expanders are arranged below the laser beam expander. a one-half-wave plate, and the first focusing mirror is arranged under the half-wave plate.

Preferably, the reflection measurement unit includes a collimating mirror, a quarter wave plate, a polarizing beam splitter, a second focusing mirror and a third focusing mirror, and the quarter wave plate is arranged above the collimating mirror. wave plate, the polarizing beam splitter is arranged above the quarter wave plate, the second focusing mirror is arranged above the first output end of the polarizing beam splitter, and the second focusing mirror of the polarizing beam splitter A third focusing mirror is arranged above the output end, the optical signals of the two focusing mirrors are input to the first photodetector, and the optical signals of the third focusing mirror are input to the second photodetector; wherein, the quarter wave The fast axis angle of the sheet was 22.5°.

Preferably, the incident polarization angle of the laser is 0°, and the fast axis angle of the half-wave plate is 22.5°.

Preferably, the scanning table includes an XY translation table, a rotary table and a wafer suction device, the wafer suction device is connected to the rotary table, and the rotary table is connected to the upper end of the XY translation table.

In the second aspect, an embodiment of the present invention provides a wafer detection method, which uses the above-mentioned wafer detection device to detect a wafer, and specifically includes the following steps:

Rotate and translate the wafer, scan the wafer during the rotation and translation process, and obtain the first detection light and the second detection light optical signal reflected on the wafer;

Adding the analog signal of the first detection light and the analog signal of the second detection light to obtain the reflectivity of the detection position, and obtain the wafer surface defect result according to the reflectivity;

The analog signal of the first detection light and the analog signal of the second detection light are divided to obtain the ellipsometric relational expression of the detection position, and the film thickness result of the wafer is obtained according to the ellipsometric parametric relational expression.

In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions, and when the computer instructions are run on a computer, the computer is made to execute the wafer detection method as described above.

In a fourth aspect, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and operable on the processor. When the processor executes the computer program, the computer program is implemented. Wafer inspection method as described above.

The present invention adopts the adder and the divider to process the reflected light analog signal, can realize the wafer surface defect detection and the wafer film thickness detection, and the adder and the divider can improve the wafer surface defect detection accuracy and the film thickness detection accuracy.

Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description.

Description of drawings

The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the present invention, but do not constitute limitations to the embodiments of the present invention. In the attached picture:

FIG. 1 is a schematic structural view of a wafer detection device provided in Embodiment 1 of the present invention;

FIG. 2 is a flow chart of the wafer detection method provided in Embodiment 1 of the present invention;

FIG. 3 is a graph showing the relationship between the ratio of the first detection light to the second detection light and the film thickness of the wafer according to Embodiment 1 of the present invention.

Explanation of reference signs

1-laser, 2-laser beam expander, 3-half wave plate, 4-first focusing mirror, 5-collimating mirror, 6-quarter wave plate, 7-polarization beam splitter, 8 -The second focusing mirror, 9-the third focusing mirror, 10-the first photodetector, 11-the second photodetector, 12-adder, 13-divider, 14-the first analog-to-digital converter, 15- The second analog-to-digital converter, 16-microprocessor, 17-scanning platform.

Detailed ways

The specific implementation manners of the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation manners described here are only used to illustrate and explain the embodiments of the present invention, and are not intended to limit the embodiments of the present invention.

In the embodiments of the present invention, unless otherwise specified, the used orientation words such as "up, down, left, right" usually refer to the orientation or positional relationship shown in the drawings, or the use of the inventive product The usual orientation or positional relationship. The terms "first", "second", "third", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

The terms "parallel", "perpendicular", etc. do not mean that the components are absolutely parallel or perpendicular, but may be slightly inclined. For example, "parallel" only means that its direction is more parallel than "vertical", and does not mean that the structure must be completely parallel, but can be slightly inclined.

The terms "horizontal", "vertical", "overhanging" and the like do not imply that the part is absolutely horizontal, vertical or overhanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In addition, terms such as "approximately" and "basically" are intended to indicate that the relevant content does not require absolute precision, but may have certain deviations. For example: "approximately equal" does not only mean absolute equality, because it is difficult to achieve absolute "equal" in the actual production and operation process, generally there is a certain deviation. Therefore, in addition to being absolutely equal, "approximately equal to" also includes the above-mentioned situation where there is a certain deviation. Take this as an example, and in other cases, unless otherwise specified, terms such as "approximately" and "basically" have similar meanings to the above.

In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation", "installation", "connection" and "connection" should be understood in a broad sense, for example, it may be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediary, and it can be internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

The "connection" mentioned in this article is used to describe the electrical power connection or signal connection between two components; An indirect connection made by a third element.

The "signal connection" described herein is used to describe the signal connection between two components, such as control signals and feedback signals; the "electrical connection" described is used to describe the electrical power connection between two components; "connection" can It is a direct connection between two parts or an indirect connection through a third part.

Example 1

Please refer to FIGS. 1-2. In a first aspect, an embodiment of the present invention provides a wafer inspection device, including a measurement component, a detection circuit, and a scanning table 17.

The measurement assembly includes an illumination unit and a reflection measurement unit, the illumination unit is used to provide illumination focused light for the wafer detection area, and the reflection measurement unit is used to receive the reflected light from the wafer surface and divide the reflected light into second a detection light and a second detection light;

The detection circuit is used to detect wafer surface defects and film thickness according to the reflected light of the measurement component;

The scanning table 17 is used for placing wafers.

Specifically, the illumination focused light provided by the lighting component is irradiated on the point to be measured on the wafer, and the reflected light of the focused light on the wafer is received by the reflective measurement unit, which inputs the reflected light into the detection circuit, and the detection circuit passes the reflection Light power measurement to obtain wafer surface defect results and film thickness results.

In this embodiment, the microprocessor 16, the adder 12 and the divider 13;

The adder 12 is used to add the analog signal of the first detection light to the analog signal of the second detection light to obtain the reflectivity of the detection position;

The divider 13 is used to divide the analog signal of the first detection light by the analog signal of the second detection light to obtain the ellipsometric parameter relational expression of the detection position;

The microprocessor 16 is used to obtain the wafer surface defect result according to the reflectivity, and obtain the wafer film thickness result according to the ellipsometric parameter relational expression.

In this embodiment, the detection circuit further includes a first photodetector 10, a second photodetector 11, a first analog-to-digital converter 14, and a second analog-to-digital converter 15;

The output terminals of the first photodetector 10 are respectively connected to the adder 12 and the divider 13, and the output terminals of the second photodetector 11 are respectively connected to the adder 12 and the divider 13; the first analog-to-digital converter The input terminal of 14 is connected with the adder 12, the output terminal of the first analog-to-digital converter 14 is connected with the input terminal of the microprocessor 16, and the input terminal of the second analog-to-digital converter 15 is connected with the division device 13, the output end of the second analog-to-digital converter 15 is connected to the input end of the microprocessor 16.

Specifically, the first photodetector 10 receives the first detected light analog signal, and the power of the first detected light analog signal is obtained as:

The second photodetector 11 receives the second detection light analog signal, and obtains the power of the second detection light analog signal as:

Among them, I ₁ is the optical signal power of the first detection light, I ₂ is the optical signal power of the second detection light, I ₀ is the incident light power, and the ellipsometric parameter ψ is the amplitude of the first detection light and the second detection light The ellipsometric parameter Δ is the phase difference between the first detection light and the second detection light.

The adder 12 is used to add the analog signal of the first detection light and the analog signal of the second detection light to obtain the power sum of the first detection light and the second detection light. The power sum has nothing to do with the ellipsometric parameters, but only with the surface It is related to the reflectivity, and the surface defects of the wafer are reflected by the change of the reflectivity.

The divider 13 is used to divide the analog signal of the first detection light and the analog signal of the second detection light to obtain the ratio of the first detection light to the second detection light:

The ratio result divides the incident light power I ₀ approximately, so that the ratio result has nothing to do with the incident light power I ₀ , but only with the ellipsometric parameters ψ and ellipsometric parameters Δ, and in this field, the ellipsometric parameters ψ and ellipsometric parameters There is a functional relationship between the parameter Δ and the film thickness, and the film thickness can be obtained by calculating the relationship between the ellipsometric parameter ψ and the ellipsometric parameter Δ.

Specifically, both the first analog-to-digital converter 14 and the second analog-to-digital converter 15 are used to convert analog signals into digital signals. The first analog-to-digital converter 14 converts the analog signal output by the adder 12 , and the second analog-to-digital converter 15 converts the analog signal output by the divider 13 .

The microprocessor 16 performs defect signal analysis and film thickness signal analysis on the added analog signal and the divided analog signal.

Further, the adder 12 directly adds the strengths of the analog signals, and then collects them through the first analog-to-digital converter 14, which can effectively improve the synchronization of the two reflection signal measurements and improve the detection accuracy of surface defects.

The divider 13 directly divides the analog signal, which can effectively improve the synchronization of the measurement of the two reflection signals, further reduce the random error introduced by the energy fluctuation of the light source, and improve the detection accuracy of the film thickness.

In this embodiment, the illumination unit includes a laser 1, a laser beam expander 2, a half-wave plate 3 and a first focusing mirror 4, and the laser beam expander 2 is arranged below the laser 1, so that A half-wave plate 3 is arranged below the laser beam expander 2 , and the first focusing mirror 4 is arranged under the half-wave plate 3 . The laser 1 emits a laser beam, and the laser beam expander 2 expands the beam diameter and reduces the divergence angle, so that a smaller focused light is obtained after passing through the first focusing lens 4, and the resolution of wafer surface defect detection and film thickness detection is improved. At the same time, the laser energy density after beam expansion is reduced, which can reduce the energy damage threshold requirement for wave plate selection. The half-wave plate 3 is used to adjust the laser polarization direction.

In this embodiment, the incident polarization angle of the laser 1 is 0°, and the fast axis angle of the half-wave plate 3 is set to 22.5° to ensure that the laser light source is incident at 45°, so that the wafer thickness measurement has the best effect .

In this embodiment, the reflection measurement unit includes a collimating mirror 5, a quarter wave plate 6, a polarizing beam splitter 7, a second focusing mirror 8 and a third focusing mirror 9, and the collimating mirror 5 The quarter wave plate 6 is arranged above, the polarization beam splitter 7 is arranged above the quarter wave plate 6, and the first output end of the polarization beam splitter 7 is provided with the first Two focusing mirrors 8, a third focusing mirror 9 is arranged above the second output end of the polarizing beam splitter 7, the optical signal of the second focusing mirror 8 is input to the first photodetector 10, and the third focusing mirror The optical signal of 9 is input to the second photodetector 11; wherein, the fast axis angle of the quarter wave plate 6 is 22.5°.

The collimating mirror 5 receives the reflected light passing through the wafer surface and collimates it into parallel light. The collimated beam is polarized and modulated by a quarter-wave plate 6, and then separated by a polarizing beam splitter 7 to separate P-polarized light and S-polarized light, transmit P-light, and focus to the first photodetector through a second focusing lens 8 10 ; the S light is reflected and focused onto the second photodetector 11 by the third focusing mirror 9 .

In other embodiments of the present invention, the polarizing beam splitter 7 is a polarizing beam splitting cube or a Wollaston prism.

The fast axis angle of the quarter-wave plate 6 is set to 22.5° to ensure that the ellipsometric parameter can be eliminated when the polarized first detection light is added to the second detection light.

In this embodiment, the incident polarization angle of the laser 1 is 0°, and the fast axis angle of the half-wave plate 3 is 22.5°.

In this embodiment, the scanning table 17 includes an XY translation table, a rotary table, and a wafer suction device, the wafer suction device is connected to the rotary table, and the rotary table is connected to the upper end of the XY translation table . Under the action of the XY translation stage, rotary stage and wafer adsorption device, the measurement point moves in a spiral trajectory relative to the wafer to complete the scanning of the entire wafer.

In the second aspect, an embodiment of the present invention provides a wafer detection method, which uses the above-mentioned wafer detection device to detect a wafer, and specifically includes the following steps:

S1. Rotate and translate the wafer, scan the wafer during the rotation and translation process, and obtain the first detection light and the second detection light optical signal reflected on the wafer;

S2. Adding the analog signal of the first detection light and the analog signal of the second detection light to obtain the reflectivity of the detection position, and obtain the wafer surface defect result according to the reflectivity;

The sum of the power detected by the surface of the first photodetector 10 and the second photodetector 11 is measured by the adder 12, and its value has nothing to do with the ellipsometric parameter, but only with the surface reflectivity, and the wafer surface defect is reflected by the reflectivity change . The adder 12 directly adds the strengths of the analog signals, and then collects them through the first analog-to-digital converter 14, which can effectively improve the measurement synchronization of the two reflection signals and improve the accuracy of defect detection.

S3. Divide the analog signal of the first detection light and the analog signal of the second detection light to obtain an ellipsometric parameter relational expression of the detection position, and obtain a film thickness result of the wafer according to the ellipsometric parameter relational expression.

Specifically, the ratio result can divide the incident light power I ₀ approximately, so that the ratio result has nothing to do with the incident light power I ₀ , but is only related to the ellipsometric parameter ψ and ellipsometric parameter Δ, and in this field, the ellipsometric parameter There is a functional relationship between ψ, the ellipsometric parameter Δ and the film thickness, and the film thickness can be obtained by calculating the relational expressions of the ellipsometric parameter ψ and the ellipsometric parameter Δ.

This embodiment provides a Si wafer model with a SiO ₂ single-layer film structure, a simulation of the relationship between the ratio of the first detection light to the second detection light and the film thickness. The simulation conditions are set as follows, the wafer is made of Si, the incident angle of the light source is 70°, the wavelength is 405nm, the refractive index of the air layer is 1, the refractive index of the SiO ₂ film is 1.47, and the refractive index of the Si wafer is 5.44-0.34i. According to the above simulation conditions, a graph showing the relationship between the ratio of the first detection light to the second detection light and the film thickness of the wafer obtained through simulation is shown in FIG. 3 . The film thickness of the wafer to be measured can be obtained according to the graph of the relationship between the ratio of the first detection light to the second detection light and the film thickness of the wafer, and the ratio of the first detection light to the second detection light output by the divider.

In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions, and when the computer instructions are run on a computer, the computer is made to execute the wafer detection method as described above.

In a fourth aspect, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and operable on the processor. When the processor executes the computer program, the computer program is implemented. Wafer inspection method as described above.

The optional implementations of the embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above-mentioned embodiments. Within the scope of the technical concept of the embodiments of the present invention, the embodiments of the present invention can be Various simple modifications are made to the technical solution, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

Those skilled in the art can understand that all or part of the steps in the method of the above-mentioned embodiments can be completed by instructing the relevant hardware through a program. (processor) executes all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disc, etc., which can store program codes. .

In addition, various implementations of the embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the embodiments of the present invention, they should also be regarded as the content disclosed in the embodiments of the present invention.

Claims (10)

1. A wafer inspection apparatus is characterized by comprising a measuring assembly, an inspection circuit, and a scanning stage (17),

the measuring assembly comprises an illumination unit and a reflection measuring unit, wherein the illumination unit is used for providing illumination focusing light for a wafer detection area, and the reflection measuring unit is used for receiving reflected light of the surface of the wafer and dividing the reflected light into first detection light and second detection light;

the detection circuit is used for detecting the surface defect and the film thickness of the wafer according to the reflected light of the measurement assembly;

the scanning table (17) is used for placing a wafer.

2. The wafer inspection apparatus according to claim 1, wherein the inspection circuit comprises a microprocessor (16), an adder (12) and a divider (13);

the adder (12) is used for adding the analog signal of the first detection light and the analog signal of the second detection light to obtain the reflectivity of the detection position;

the divider (13) is used for dividing the analog signal of the first detection light and the analog signal of the second detection light to obtain an ellipsometric parameter relation of the detection position;

the microprocessor (16) is used for obtaining a wafer surface defect result according to the reflectivity and obtaining a wafer film thickness result according to the ellipsometric parameter relation.

3. The wafer inspection apparatus according to claim 2, wherein the inspection circuit further comprises a first photodetector (10), a second photodetector (11), a first analog-to-digital converter (14), and a second analog-to-digital converter (15);

the output end of the first photoelectric detector (10) is respectively connected with an adder (12) and a divider (13), and the output end of the second photoelectric detector (11) is respectively connected with the adder (12) and the divider (13); the input end of the first analog-to-digital converter (14) is connected with the adder (12), the output end of the first analog-to-digital converter (14) is connected with the input end of the microprocessor (16), the input end of the second analog-to-digital converter (15) is connected with the divider (13), and the output end of the second analog-to-digital converter (15) is connected with the input end of the microprocessor (16).

4. The wafer inspection apparatus according to claim 1, wherein the illumination unit comprises a laser (1), a laser beam expander (2), a half wave plate (3) and a first focusing mirror (4), the laser beam expander (2) is disposed below the laser beam expander (1), the half wave plate (3) is disposed below the laser beam expander (2), and the first focusing mirror (4) is disposed below the half wave plate (3).

5. The wafer detection device according to claim 4, wherein the reflection measurement unit comprises a collimating mirror (5), a quarter wave plate (6), a polarization beam splitter (7), a second focusing mirror (8) and a third focusing mirror (9), the quarter wave plate (6) is arranged above the collimating mirror (5), the polarization beam splitter (7) is arranged above the quarter wave plate (6), the second focusing mirror (8) is arranged above a first output end of the polarization beam splitter (7), the third focusing mirror (9) is arranged above a second output end of the polarization beam splitter (7), an optical signal of the second focusing mirror (8) is input to a first photoelectric detector (10), and an optical signal of the third focusing mirror (9) is input to a second photoelectric detector (11); wherein the fast axis angle of the quarter wave plate (6) is 22.5 degrees.

6. Wafer inspection device according to claim 5, characterized in that the incident polarization angle of the laser (1) is 0 ° and the fast axis angle of the half wave plate (3) is 22.5 °.

7. The wafer inspection apparatus according to claim 1, wherein the scanning stage (17) includes an XY shift stage, a rotary stage, and a wafer suction device, the wafer suction device being connected to the rotary stage, the rotary stage being connected to an upper end of the XY shift stage.

8. A wafer inspection method, characterized in that the wafer inspection apparatus according to any one of claims 1 to 7 is applied to inspect a wafer, comprising the steps of:

rotating and translating the wafer, and scanning the wafer in the rotating and translating processes to obtain a first detection light and a second detection light signal reflected on the wafer;

adding the analog signals of the first detection light and the analog signals of the second detection light to obtain the reflectivity of the detection position, and obtaining the wafer surface defect result according to the reflectivity;

dividing the analog signal of the first detection light and the analog signal of the second detection light to obtain an ellipsometric parameter relation of the detection position, and obtaining the film thickness result of the wafer according to the ellipsometric parameter relation.

9. A computer readable storage medium storing computer instructions which, when run on a computer, cause the computer to perform the wafer inspection method of claim 8.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the wafer inspection method of claim 8 when the computer program is executed by the processor.

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