JP2024140964A - Surface inspection method and surface inspection device - Google Patents

Abstract

To improve performance of a surface inspection method.SOLUTION: A surface inspection device 1 comprising a storage part and a control part is used, for a method for inspecting, foreign objects on an inspected surface SF on an inspected object W1. The method comprises the steps of: (a) radiating light of multiple wavelengths to the inspected surface SF of the inspected object W1; (b) detecting reflection intensity for multiple wavelengths, by detecting the reflection light 3 from the foreign objects for each of the multiple wavelengths; and (c) comparing, by the control part, a value which is stored in the storage part in advance and is a value of a second change ratio between reflection intensities between light of two wavelengths on a reference material, with a value of a first change ratio between reflection intensities of the light of the two wavelengths out of the multiple wavelengths, for determining whether the reference material and a material of the foreign objects match.SELECTED DRAWING: Figure 1

Description

The present invention relates to technology that is effective when applied to a surface inspection method and a surface inspection device.

Technology has been developed to inspect the surface of a hard disk substrate or other object by irradiating it with laser light.

Patent Document 1 (JP Patent Publication No. 2020-204579) discloses a surface inspection method in which a laser beam is irradiated onto the surface of a semiconductor wafer, and the presence or absence of foreign matter is determined based on the light reflected from the surface, and whether the foreign matter is metallic or non-metallic.

Patent Document 2 (JP Patent Publication No. 2022-39137) discloses a method for detecting irregular defects in which a laser beam is irradiated onto the surface of a semiconductor wafer, and the presence or absence of irregular defects is detected based on the light scattered from the surface.

JP 2020-204579 A JP 2022-39137 A

When defects such as foreign matter adhering to the surface of a hard disk substrate occur, identifying the material of the foreign matter can help clarify the cause of the foreign matter and review the manufacturing process, leading to improved manufacturing yields and improved product reliability. For this reason, there is a demand for technology that can determine the material in more detail, rather than simply determining whether the foreign matter is metallic or non-metallic, as in Patent Document 1.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

A brief overview of the representative embodiments disclosed in this application is as follows:

A surface inspection method according to one embodiment is a surface inspection method for inspecting a surface of an object to be inspected for foreign bodies using a surface inspection device having a control unit and a memory unit, and includes the steps of: (a) irradiating the surface of the object to be inspected with light of multiple wavelengths; (b) detecting the reflection intensity for each of the multiple wavelengths of light by detecting the reflected light from the foreign body; and (c) determining whether the reference material and the material of the foreign body match by the control unit comparing a value of a first rate of change between the reflection intensities of light of two wavelengths among the multiple wavelengths with a value of a second rate of change between the reflection intensities of light of the two wavelengths of a reference material, the value being stored in advance in the memory unit.

According to one embodiment, the performance of the surface inspection method can be improved.

1 is a schematic diagram showing a surface inspection device according to a first embodiment. 1 is a block diagram showing a signal processing system according to a first embodiment; 3 is a flow diagram showing a surface inspection method according to the first embodiment. 4 is a graph showing the relationship between wavelength and reflectance of a reference material in the first embodiment. 4 is a table showing wavelengths and reflection intensities of reference materials in the first embodiment. 1 is a table showing the rate of change in reflection intensity in the waveband of a reference material in the first embodiment. 4 is a graph showing the relationship between wavelength and reflectance of comparative materials in the first embodiment. 1 is a table showing the wavelength and reflection intensity of comparative materials in the first embodiment. 1 is a table showing the change rate of reflection intensity in the waveband of comparison materials in the first embodiment. 13 is a table showing the results of comparing and judging a reference value (c) and a comparative value (d) of the rate of change when the threshold value is set to ±3 in the first embodiment. 13 is a table showing the results of comparing and judging the reference value (c) and the comparative value (d) of the rate of change when the threshold value is set to ±4 in the first embodiment. 1 is a graph showing the relationship between wavelength and reflectance in nickel. 1 is a graph showing the relationship between wavelength and reflectance in aluminum. 1 is a graph showing the relationship between wavelength and reflectance for iron. 1 is a graph showing the relationship between wavelength and reflectance in magnesium oxide. 1 is a graph showing the relationship between wavelength and reflectance in carbon graphite. 1 is a graph showing the relationship between wavelength and reflectance in iron oxide. 1 is a graph showing the relationship between wavelength and reflectance in silicon. 1 is a graph showing the relationship between wavelength and reflectance in PET. 1 is a graph showing the relationship between wavelength and reflectance in PMMA. FIG. 1 is a schematic diagram showing a surface inspection device according to a first modified example of the first embodiment. 13 is a schematic diagram showing a light scanning method of a surface inspection device according to a second modification of the first embodiment. FIG. 13 is an equation for calculating the slope coefficient of the regression line of the inter-wavelength output in the second embodiment. 1 is a graph showing the relationship between wavelength and reflectance in silicon oxide. 1 is a graph showing the relationship between wavelength and reflectance in nickel. 1 is a graph showing the relationship between wavelength and reflectance in copper. 1 is a table showing the reflectance of silicon oxide, nickel, and copper at each wavelength. 1 is a table showing the slope coefficients at each wavelength for silicon oxide, nickel, and copper. 13 is a table showing the matching rate of the slope coefficient between each material and the result of the match/mismatch determination in the second embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings. In all drawings used to explain the embodiment, the same reference numerals are used for components having the same functions, and repeated explanations will be omitted. In addition, in the embodiment, explanations of the same or similar parts will not be repeated as a general rule, unless particularly necessary.

Here, we explain how to determine the material of the substance present on the surface of the object by irradiating the object with two or more beams of light with different wavelengths, receiving the reflected light, detecting the reflection intensity (scattering intensity), and comparing it with the reflection intensity of a specific material pre-stored in the device. Note that the term "material" here refers to either a specific type or composition of substance, or both.

(Embodiment 1)
<Structure of Surface Inspection Device>
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a surface inspection device 1 for detecting foreign matter according to one embodiment is used to detect, for example, a nickel (Ni) substrate, i.e., a nickel board, as an object W1 to be inspected, for example, peeling of plating or defects of uneven shape on the metallic surface, i.e., the surface SF to be inspected, or adhesions on the surface SF to be inspected. The surface inspection device 1 is also used to determine the material of the foreign matter. The material in this application also includes the composition of the substance. The object W1 to be inspected is, for example, a hard disk, a semiconductor wafer, a glass substrate, etc., and in this embodiment, it is possible to inspect not only the surface of the object W1 to be inspected and adhesions on the surface, but also foreign matters in the film that constitutes the surface. Furthermore, foreign matters on the surface or inside of glass can also be inspected. In other words, it is possible to inspect foreign matters inside the transparent or semi-transparent object W1 to be inspected. Furthermore, it is possible to inspect the portion of the surface of the object W1 to be inspected that has been altered, i.e., the composition of the locally heterogeneous composition. In this application, peeling plating and uneven shape defects on the inspected surface SF, adhesions on the inspected surface SF, objects embedded under the inspected surface SF, and partially altered areas of the inspected surface SF are collectively referred to as foreign matter.

The surface inspection device 1 has a moving stage 12 arranged on a support table 11, and the moving stage 12 is arranged on the support table 11 so as to be movable in the left-right direction (X-axis direction) in FIG. 1. The moving stage 12 is movable in the X-axis direction along a horizontal plane. The Y-axis direction and the X-axis direction are directions that perpendicularly intersect each other in a plan view. A rotary motor 13 is attached to the moving stage 12, and a chuck 15 that holds the inspection object W1 is provided on a rotary shaft 14 that is rotated by the rotary motor 13. A through hole is provided in the center of the inspection object W1, a disc-shaped nickel substrate, and the chuck 15 has a collet (not shown) that engages with the inner surface of the through hole.

The surface inspection device 1 has a light source 16, which is disposed diagonally above the surface SF to be inspected and irradiates light toward the surface SF to be inspected. The light source 16 can be a laser oscillator capable of irradiating multiple short-wavelength laser beams, an LED (Light Emitting Diode) capable of irradiating multiple short-wavelength LED beams, or a high-brightness white light source. In any case, these light sources can irradiate multiple wavelengths of light simultaneously in the same direction. Here, the light irradiated from the light source 16 is described as a laser beam irradiating light of at least three wavelengths. A focus lens (condensing lens) 17 is disposed on the optical path of the laser beam, and the laser beam irradiated from the light source 16 is condensed by the focus lens 17 on the surface SF to be inspected to form a beam spot. Here, the laser beam is condensed by the focus lens 17 to target a single lump of material as much as possible. This is because if multiple materials are targeted at the same time with light having a large irradiation range, reflected light from foreign objects of various compositions will be mixed, making it difficult to distinguish the material of the foreign object, and there is a risk of reducing the inspection accuracy. In addition, if the irradiation range is large, the reflection intensity or detection sensitivity decreases, and it becomes difficult to accurately determine the location of the foreign object. The laser light includes laser light of three wavelengths, for example, 400 nm, 480 nm, and 560 nm.

In order to collect the reflected light 3 from the surface SF to be inspected, the condensing lenses 18a and 18b are arranged as condensing members facing the surface SF to be inspected. Instead of the condensing lenses 18a and 18b, a condensing mirror or the like can also be used as the condensing member. The reflected light 3 collected by passing through the condensing lenses 18a and 18b in order is split into two optical paths by the half mirror 19C arranged on the optical axis of the light receiving system. The reflected light 3 on one optical path is incident on the photodetector (light receiving section) 2C, and the reflected light 3 on the other optical path is incident on the half mirror 19B. The reflected light 3 incident on the half mirror 19B is split into two optical paths by the half mirror 19B arranged on the optical axis. The reflected light 3 on one optical path is incident on the photodetector (light receiving section) 2B, and the reflected light 3 on the other optical path is incident on the photodetector (light receiving section) 2A.

For example, a prism that reflects only light of a single wavelength C at 45 degrees is used for the half mirror 19C. For example, a prism that reflects only light of a single wavelength B at 45 degrees is used for the half mirror 19B. Between the half mirror 19C and the photodetector 2C, a plate 4C that blocks specularly reflected light is placed. Between the half mirror 19B and the photodetector 2B, a plate 4B that blocks specularly reflected light is placed. Between the half mirror 19B and the photodetector 2A, a plate 4A that blocks specularly reflected light is placed. By performing detection simultaneously with the three photodetectors 2A, 2B, and 2C, a more accurate comparison can be made.

Between the half mirror 19B and the photodetector 2A, an optical filter 23 is arranged to block light of wavelengths other than the desired wavelength from entering the photodetector 2A. The optical filter 23 transmits only light of a single wavelength A. A similar optical filter may be arranged between the half mirror 19B and the photodetector 2B, or between the half mirror 19C and the photodetector 2C. For example, the photodetector 2A receives light of a wavelength of 400 nm from the reflected light 3, the photodetector 2B receives light of a wavelength of 480 nm from the reflected light 3, and the photodetector 2C receives light of a wavelength of 560 nm from the reflected light 3. Each of these three wavelengths of light may be detected by any of the photodetectors 2A, 2B, and 2C.

For the photodetectors 2A, 2B, and 2C, devices that can convert light into a signal voltage according to its intensity can be used. For example, the photodetectors 2A, 2B, and 2C can be a PMT (Photomultiplier Tube) system, an APD (Avalanche Photodiode) system, or a PD (Photodiode) system. Here, camera elements such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) are not used for the photodetectors 2A, 2B, and 2C.

The laser light is irradiated toward a predetermined irradiation position on the surface SF to be inspected. Meanwhile, the object W1 to be inspected is rotated at high speed by the rotary motor 13, and is moved by the moving stage 12 along the normal direction (radial direction; here, the X-axis direction) of the outer circumferential surface of the object W1 to be inspected. In this way, by scanning and moving the object W1 to be inspected, the laser light performs a spiral scan of the surface SF to be inspected. However, the object to be inspected may be fixed and supported, and the laser light may be scanned and moved relative to the surface to be inspected. In other words, the scanning movement of the irradiation position of the laser light on the surface SF to be inspected need only be relative. The moving stage 12 and the rotary motor 13 constitute a scanner that relatively scans and moves the irradiation position of the laser light (light of multiple wavelengths irradiated from the light source 16) on the surface to be inspected.

Figure 2 is a block diagram showing a signal processing system including a comparison and judgment processing unit 39 according to this embodiment. The signal processing system has the photodetectors 2A, 2B, and 2C described with reference to Figure 1, and a signal processing circuit (signal processing unit) 31. The output signal of the photodetector 2A is converted into a voltage signal by the I/V converter 32, amplified by the amplifier 33, and then converted into a digital signal by the A/D converter 34 and sent to the signal processing circuit 31. Similarly, the output signals of the photodetectors 2B and 2C are sent to the signal processing circuit 31 via the I/V converter 32, the amplifier 33, and the A/D converter 34 in that order.

The surface inspection device 1 has a scanning encoder 35, which is a rotary encoder for detecting the rotation angle of the rotary motor 13 or the rotary shaft 14 during scanning, and each encoder signal is sent to a signal processing circuit 31. The signal processing circuit 31 calculates whether or not a foreign object is present based on the detection signals output by the photodetectors 2A, 2B, and 2C upon receiving the reflected light 3 from the foreign object.

Reflected light in this application includes either specular reflected light or scattered light (diffuse reflected light), or both. When inspecting the surface of a normal inspection object W1 without any foreign matter, almost no scattered light is generated, and only specular reflected light reaches the photodetector. As shown in FIG. 1, if the specular reflected light is blocked by plates 4A, 4B, and 4C before it reaches the detector, a spectrum cannot be obtained from the specular reflected light. In other words, if no spectrum can be obtained from the reflected light, it can be determined that there is no abnormality. If a foreign matter is present, the reflected light includes scattered light. However, even with specular reflected light, differences in wavelength spectrum occur if light is absorbed by the reflector, so if there are no obstructions such as plates 4A, 4B, and 4C, a spectrum can be obtained from the specular reflected light. When a diffraction grating is used as in Modification 1 described later with reference to FIG. 21, the specular reflected light is also reflected by the diffraction grating, so the spectrum of the specular reflected light can be obtained.

The signal processing system has a comparison and judgment processing unit 39 consisting of, for example, a PC (Personal Computer). The comparison and judgment processing unit 39 has a storage unit (memory) 30 in which the reference reflection intensity, a control program, an arithmetic expression, map data, etc. are stored, and a control unit (processor) that calculates a control signal. The control unit has a comparison and judgment unit 29, a mapping unit 37, and a defect number judgment unit 38. In other words, the comparison and judgment processing unit 39 is composed of the comparison and judgment unit 29, the storage unit 30, the mapping unit 37, and the defect number judgment unit 38. The comparison and judgment unit 29 is connected to the signal processing circuit 31, the storage unit 30, and the mapping unit 37, and the mapping unit 37 is connected to the defect number judgment unit 38.

The comparison and judgment unit 29 compares the reflection intensity, which is the detection signal detected by the photodetectors 2A to 2C from the reflected light 3, with a reference reflection intensity previously stored in the memory unit 30, and judges the presence or absence of a foreign object on the inspection surface SF and the material of the foreign object. If the comparison and judgment unit 29 judges that a foreign object is present, the comparison and judgment unit 29 calculates the position signal data of the foreign object on the inspection surface SF based on the foreign object detection signal and the encoder signal obtained from the scanning encoder 35, which is a rotary encoder, via the signal processing circuit 31. The position signal data and the detection signal data are sent to the mapping unit 37, and a map of the foreign object on the inspection surface SF is created. The position of the foreign object is displayed on a display provided in the mapping unit 37. For foreign objects that are finally judged to be defects based on the position signal data (position information) and the detection signal data, the position on the inspection surface SF is displayed on a comprehensive map display provided in the defect number judgment unit 38. The mapping unit 37 and the defect number judgment unit 38 are configured by the software of the comparison and judgment processing unit 39.

<Surface inspection method using a surface inspection device>
Next, a surface inspection method using the above-mentioned surface inspection device 1 will be described with reference to the flow of Fig. 3 and with reference to Fig. 4 to Fig. 11. Fig. 3 is a flow chart showing an algorithm of a judgment procedure.

Here, before starting the surface inspection, pre-inspection preparation is performed. That is, reflection intensity data of a reference material (substance or composition) is registered in the memory unit 30 shown in FIG. 2 as a reference value for comparison (step S21 in FIG. 3). The reference material may be the material of the surface of the inspection object W1 to be inspected in a later inspection process (step S1 onward in FIG. 3) when no foreign matter is present, or it may be the material of a foreign matter such as an attachment whose presence is suspected on the inspection surface SF.

In step S21, the reflection intensity is calculated from the reflectance at three different wavelengths as shown in FIG. 4, the change rate is calculated from the reflection intensity value, and the change rate is stored. FIG. 4 is a graph of the reflectance of a reference material (e.g., nickel (Ni)), where the horizontal axis indicates the wavelength of light irradiated onto the reference material, and the vertical axis indicates the reflectance.

However, the graph in FIG. 4 was not obtained by actual measurement, and the graph in FIG. 4 can be obtained without irradiating the reference material with light in step S21. In other words, when light waves hit a material, light of a certain wavelength is easily absorbed, and light of other certain wavelengths is easily reflected. In other words, the color (spectrum) of the reflected light differs depending on the material. If the reflected light is divided by wavelength, a graph like that shown in FIG. 4, that is, a spectral pattern, is obtained. The reflectance (R) of a material is explained by the dielectric constant specific to the material, and is calculated from the refractive index (n) and extinction coefficient (k). The extinction coefficient k represents the loss of light energy in the material, and is related to the light absorption rate by the material. In this way, the graph shown in FIG. 4 was obtained by calculation, not by actual measurement.

Here, the three reflectances obtained by irradiating the object made of the reference material with light of wavelengths of 400 nm, 480 nm, and 560 nm at the three points circled in FIG. 4, that is, the values obtained by multiplying the three reflectances by 10 are stored as the reflection intensity. That is, as shown in FIG. 5, the three reflectances x 10 values (reflection intensity) of the reflected light when irradiating the object made of the reference material with light of wavelengths of 400 nm, 480 nm, and 560 nm are obtained. That is, the reflection intensity is proportional to the reflectance. The calculation of such reflection intensity is performed by the comparison and judgment unit 29. The comparison and judgment unit 29 may not perform the calculation, and the reflection intensity value may be stored in the storage unit 30 in advance. The maximum value of the reflectance is 1. Also, the horizontal axis of the graph in FIG. 4 is the wavelength, and the vertical axis is the reflectance, which is the same for all graphs used in the following explanation. Here, the value obtained by multiplying the reflectance by 10 is the reflection intensity, but since the reflection intensity does not have to be 10 and may be an integer, it may be multiplied by 100 or 1000. Converting the detected value into an integer makes it easier for the comparison and judgment unit 29 to handle the numerical values.

Next, the comparison and judgment unit 29 calculates the rate of change of the signal intensity (reflection intensity) between each wavelength. That is, the value of the rate of change between the reflection intensity of light of two wavelengths among the multiple wavelengths is calculated. Here, the rate of change between the output at the shortest wavelength and the output at the intermediate wavelength among the three reflection intensities (outputs) is calculated, and further, the rate of change between the output at the intermediate wavelength and the output at the longest wavelength is calculated. As shown in FIG. 6, for example, 86.065 is calculated as the rate of change of the reflection intensity between the wavelengths of 400 nm and 480 nm by the formula of short wavelength side output ÷ long wavelength side output × 100. Similarly, for example, 89.994 is calculated as the rate of change of the reflection intensity between the wavelengths of 480 nm and 560 nm. This formula is stored in the storage unit 30. In step S21, these two rate of change are stored as the reference reflection intensity registration value (reference value c).

In addition, in a graph in which the reflectance increases as the wavelength increases as in FIG. 4, the rate of change is a positive value, and conversely, in a graph in which the reflectance decreases as the wavelength increases, the rate of change is a negative value. With the above, pre-inspection preparation is completed. Also, instead of the comparison and judgment unit 29 performing calculations such as calculation of reflection intensity and calculation of the rate of change in reflection intensity as described above, such calculations may be performed by an external computer and the calculation results (values of the rate of change in reflection intensity between specified wavelengths) may be stored in the memory unit 30.

Next, we will explain how to inspect the test object.

Here, the inspection object W1 is placed on the surface inspection device 1 and inspected. The inspection object W1 is an object suspected of having a foreign object on its inspection surface SF, or the presence of a foreign object has been confirmed. When the surface inspection device 1 is started, the signal processing system performs initial settings such as inspection conditions. As a result, devices such as the moving stage 12 and the light source 16 are set to a drivable state. When the start switch of the operation panel (not shown) provided on the surface inspection device 1 is operated by the user in step S1, the rotary motor 13 and the moving stage 12 are driven and the light source 16 is turned on, and light containing at least three types of wavelengths (here, laser light) is irradiated toward the inspection surface SF. As a result, a scanning movement process is executed, the irradiation position of the laser light on the inspection surface is scanned and moved, and the reflectance of each of the three wavelengths (wavelengths A to C) on the inspection surface SF and the irradiation position data of the laser light on the inspection surface SF are read into the signal processing circuit 31 (step S2 in FIG. 3).

If a foreign substance is present on the surface SF to be inspected, in step S2, the photodetectors 2A, 2B, and 2C receive scattered light (reflected light 3) from the foreign substance (comparison material). That is, light of different wavelengths is detected by the photodetectors 2A, 2B, and 2C, respectively. The detection signals detected by the photodetectors 2A, 2B, and 2C are converted into voltage signals by the I/V converter 32 shown in FIG. 2, amplified by the amplifier 33, and then converted into digital signals by the A/D converter 34 and sent to the signal processing circuit 31. In this way, the signals sent from the photodetectors are detected. After that, these digital signals are sent to the comparison and judgment unit 29 as data on the reflection intensity of wavelength A, the reflection intensity of wavelength B, and the reflection intensity of wavelength C. These reflection intensity data may be stored in the memory unit 30.

For example, in step S2, the reflected light 3 is received by the photodetectors 2A, 2B, and 2C, and the reflectance at three wavelengths is measured as shown in FIG. 7. FIG. 7 is a graph of the reflectance of a material of a comparative substance. When the object W1 is irradiated with light of wavelengths of 400 nm, 480 nm, and 560 nm at three points circled in FIG. 7, the reflectance for each wavelength is measured (detected). These three wavelengths must be the same as the three wavelengths of the light detected in step S21. As shown in FIG. 8, the result of irradiating the object W1 with light of wavelengths of 400 nm, 480 nm, and 560 nm is three reflectances x 10. The reflection intensity is calculated by the comparison and judgment unit 29.

Next, the comparison and judgment unit 29 calculates the rate of change of the signal intensity (reflection intensity) between each wavelength (step S3 in FIG. 3). That is, the value of the rate of change between the reflection intensity of light of two wavelengths among the multiple wavelengths is calculated. Here, the rate of change between the output at the shortest wavelength and the output at the intermediate wavelength among the three reflection intensities (outputs) is calculated, and further, the rate of change between the output at the intermediate wavelength and the output at the longest wavelength is calculated. As shown in FIG. 9, for example, 81.972 is calculated as the rate of change of the reflection intensity between 400 nm and 480 nm by the formula of short wavelength side output ÷ long wavelength side output × 100. Similarly, for example, 93.336 is calculated as the rate of change of the reflection intensity between 480 nm and 560 nm. In step S3, these two rate of change are calculated by calculation as a comparative reflection intensity value (comparison value d).

Next, the comparison and determination unit 29 performs a comparison operation between the reference value c and the comparison value d in the same wavelength range to determine whether they match or not (step S4 in FIG. 3). That is, a threshold is set as a range by which the reference value c is increased or decreased, and it is determined whether the comparison value d is within the matching range. In other words, if the value of the change rate which is the comparison value d is within a predetermined matching range centered on the value of the change rate which is the reference value c (if it is included in the matching range), it is determined that there is a match, and if the value of the change rate which is the comparison value d is outside the matching range (if it is not included in the matching range), it is determined that there is a mismatch.

As shown in FIG. 10, the reference value c in the wavelength range between 400 nm and 480 nm is 86.065, and when the threshold is set to ±3, the matching range of the change rate of the reflection intensity in which the foreign object (comparison material) is deemed to match the reference material is 83.065 or more and 89.065 or less. The threshold (here ±3) is stored in the memory unit 30. The threshold can be changed by the user's operation. The comparison value d is 81.972, which is outside the matching range. Therefore, the comparison judgment unit 29 judges that the foreign object does not match the reference material (nickel in this case). In other words, the foreign object is made of a material different from the reference material (a material dissimilar to the reference material).

As shown in Figure 10, here, as in the above, a comparison is made between the reference value c and the comparison value d in the wavelength range between 480 nm and 560 nm. Even in this wavelength range, the judgment result is a mismatch.

The threshold value is determined based on various factors, such as the purpose of use of the object W1 to be inspected, the similarity of the properties of the material of the foreign object whose presence is estimated to be present and the reference material, and the type of foreign object whose presence is permitted. As another example, FIG. 11 shows the comparison judgment result when the threshold value is set to ±4. Here, the judgment result in the wavelength range between 400 nm and 480 nm is a mismatch, whereas the judgment result in the wavelength range between 480 nm and 560 nm is a match because the comparison value d is within the matching range. However, if any one of the judgment results in the multiple wavelength ranges is a mismatch, the overall judgment is a mismatch. Therefore, even in the case of FIG. 11, the foreign object present on the inspection surface SF is judged to be made of a material different from the reference material (a material not similar to the reference material).

If the judgment results for all of the multiple wavelength ranges are judged to be a match, the overall judgment is a match. Therefore, the foreign matter present on the inspected surface SF is judged to be the same material as the reference material or a similar material.

If the material of the surface SF to be inspected when the object W1 is free of defects is the same as the reference material, and the inspection results indicate that the reference material and the material of the surface SF to be inspected are overall the same, then the object W1 can be determined to be a good product. In other words, it can be determined that the surface to be inspected is made of the same material as the reference material. Conversely, if the inspection results indicate that the reference material and the material of the surface SF to be inspected are overall inconsistent, then the object W1 can be determined to be a defective product. In other words, it can be determined that the surface to be inspected contains a material that is different from the reference material.

Furthermore, if the reference material is a material of an attachment whose presence can be predicted, and the inspection results indicate that the reference material and the material of the inspected surface SF are overall identical, then the inspected object W1 can be determined to be a defective product. In other words, it can be determined that the predicted foreign matter is present on the inspected surface. Conversely, if the inspection results indicate that the reference material and the material of the inspected surface SF are overall inconsistent, then the inspected object W1 may be a good product. In other words, it can be determined that the predicted foreign matter is not present on the inspected surface.

To be precise, even if it is determined that there is a possibility that a foreign object or material composition differs from the standard, that determination alone does not necessarily determine whether the item is good or bad. For example, an object with a reflection intensity lower than a predefined signal threshold may be determined to be good, or a good or bad item may be determined depending on the total number of defects on the surface SF to be inspected, and the criteria for determining whether a product is good or bad may be changed as appropriate. In other words, it is not necessarily possible to determine whether the inspected object W1 is good or bad based on only one discrimination/determination result. The surface inspection device of this embodiment determines the possibility of whether the reference material is present, and the possibility indicated by this can be used as one of the elements for determining whether a product is good or bad.

Next, the position information of the foreign object on the surface SF to be inspected (the encoder signal, the scanning position data in step S9 in FIG. 3) is read into the signal processing circuit 31, and the comparison and judgment unit 29 calculates defect position data of the foreign object and stores the result in the memory unit 30 (step S5 in FIG. 3). In addition, from the defect position data, the mapping unit 37 creates a map of the foreign object on the surface SF to be inspected (step S6 in FIG. 3).

Next, the defect number determination unit 38 refers to the image of the map and determines whether the object is good or bad based on the number of foreign objects (step S7 in FIG. 3). In other words, if the number of foreign objects is less than a reference value, the object W1 is determined to be good, and if the number of foreign objects is more than the reference value, the object W1 is determined to be bad. This completes the inspection of one object W1 (step S8 in FIG. 3).

As an example of an object to be inspected, the object to be inspected W1 may be made of aluminum (Al) and the material of the foreign matter on its surface may be nickel (Ni). As another example, the object to be inspected W1 may be made of copper (Cu) and the material of the foreign matter on its surface may be aluminum (Al), nickel (Ni), or iron (Fe), etc.

In this embodiment, when a laser oscillator is used for the light source 16, foreign objects with a diameter of, for example, about 0.6 μm can be detected and the difference in material can be determined. Furthermore, depending on the inspection mechanism and various conditions, foreign objects with a diameter of 0.3 μm or less can be inspected. To increase the accuracy of the judgment, it is desirable to narrow the irradiation range of the light irradiated on the foreign object so that only the foreign object is irradiated.

As a spectroscopic analyzer or inspection device, it has a wide field of view of several millimeters to several (tens) centimeters, so if there are multiple foreign objects of different materials within the field of view, their spectra will overlap or mix, resulting in poor discrimination accuracy per point. Also, the intensity of the light hitting a single point will decrease (light energy per unit area will decrease). In addition, the position resolution will be unclear, making it unsuitable for analyzing small foreign objects. On the other hand, to analyze small metallic foreign objects, SEMs (Scanning Electron Microscopes) or analytical devices that combine spark emission from plasma, etc. with spectroscopy are used. However, these methods have difficulty scanning the entire surface of a large inspection target, and they cause some damage to the analysis points, making them unsuitable for use on production lines.

The surface inspection device 1 of this embodiment can inspect the object W1 quickly and non-destructively in real time. It can also inspect a wide object while scanning the entire surface. Therefore, the surface inspection device 1 can be installed and used, for example, in the production line where the object W1 is manufactured.

<Effects of this embodiment>
When a foreign object occurs on the surface of a substrate or the like made of a certain material, identifying the type (material) of the foreign object makes it easier to review (feedback) the manufacturing process, improving the manufacturing yield and improving the reliability of the product. Possible types of foreign object include broken plating or surface deposits. Here, it is possible to distinguish the material by comparing the reflection intensity (reflectance) of light of a certain wavelength with a reference value, taking advantage of the fact that the reflection intensity (reflectance) differs depending on the material. That is, it is possible to detect foreign objects on the surface of the object to be inspected by irradiating light of a single wavelength, for example, and detecting the strength of the reflected light (the strength of the reflection intensity).

In this case, for example, if the break in the plating is large, strong reflected light (high reflection intensity) is detected, and if the break is small, weak reflected light (low reflection intensity) is detected. Also, if there is an attachment made of a specific material on the surface of the object being inspected, strong reflected light (high reflection intensity) is detected if the attachment is large, and weak reflected light (low reflection intensity) is detected if the attachment is small. In other words, the reflection intensity varies not only depending on the material of the foreign object, but also on its size. For this reason, it is difficult to accurately identify the material by comparing only the measured reflection intensity with the reflection intensity stored in advance in the memory unit. Also, it is difficult to determine from the detected reflected light whether the defect is due to a foreign object (an object made of a different material) or a break in the plating.

In addition, foreign matter (e.g., deposits) are often not limited to being made up of a single element, but are often made up of a mixture of multiple elements.

In contrast, in this embodiment, the rate of change in reflection intensity of a specified material is stored in advance, and this rate of change is compared with the rate of change in reflection intensity of the test object to determine the material of the test object. Here, light of three wavelengths is irradiated onto the surface of the test object, two rate of change in reflection intensity between two wavelengths is calculated, and these rate of change are compared with two pre-stored reference rate of change in reflection intensity between the two wavelengths. More specifically, whether the materials match or not is determined based on whether the value of the rate of change of the test object falls within a range (matching range) in which a ± threshold is set for the reference rate of change in a specified wavelength range. If the value of the rate of change of the test object is within the threshold, the material on the surface of the test object is considered to be the same material as the reference material, and if it is outside the threshold, it is considered to be a different material.

Whether the reflection intensity of the reflected light is large or small due to the size of the foreign object does not affect the rate of change in reflection intensity. In other words, the rate of change in reflection intensity is constant regardless of the size of the foreign object if the material is the same. In this embodiment, the rate of change in reflection intensity is compared to a registered standard rate of change. Therefore, regardless of the size of the foreign object, the material of the foreign object can be determined with greater accuracy than when a single-wavelength light is irradiated as described above and foreign objects on the surface of the object are detected based on the strength of the reflected light. In other words, the performance of the surface inspection device and surface inspection method can be improved.

The inspection in this embodiment is not limited to metals, nonmetals, alloys, organic matter, oxidized/reduced matter, organic matter, etc., and does not identify a specific type of element. Rather, the reflection intensity pattern (rate of change) for each wavelength of the material to be distinguished is recorded (registered) in advance, and materials that match this pattern are distinguished from those that do not. For this reason, the reflection intensity pattern of the material to be distinguished must be registered prior to inspection (step S21 in Figure 3).

The reflection intensity pattern to be registered is not limited to one, and multiple patterns can be registered as long as the material shows a unique reflection intensity. In addition, when checking whether the material matches a specified reference material, it is not necessary to limit the type of wavelength of light to be irradiated and measured during the inspection. In other words, the light to be irradiated and measured can be changed appropriately, for example, to 450 nm, 520 nm, and 600 nm, rather than 400 nm, 480 nm, and 560 nm as described above. For example, even if white light such as an LED is irradiated, the same effect can be obtained by selecting two or more wavelengths on the detector side and comparing and judging. In other words, the wavelength of light received on the receiver side can be selected without limiting the incident wavelength.

If the substances used at the manufacturing site can be identified, materials that cannot be mixed in as foreign bodies can also be identified. For this reason, there is no need to compare with the spectra of all materials, and there is no need to store such a huge variety of spectra in a database. In other words, materials that can adhere as foreign bodies can be predicted to some extent before surface inspection is performed. In that case, it becomes easier to identify the material of the foreign body. When the material of the foreign body that exists in advance can be predicted to some extent, it is most effective to set the wavelength of light detected by the photodetector to a range that has a characteristic pattern of the reflection intensity of the reference material. Also, when the material of the foreign body that exists in advance can be predicted to some extent, it is also effective to set the wavelength of light detected by the photodetector to a range that has a characteristic pattern of the reflection intensity of the material in question.

Regardless of whether the type of foreign matter can be identified or predicted or not, if it is known for certain that a foreign matter is present, the foreign matter can be irradiated and measured, and the spectrum that is judged to be defective can be stored and used as a material (database) that can be judged as defective (defective) from the next inspection onwards. In this case, even if the foreign matter is not made up of a single element but of a combination of multiple types of elements, the database can be used to detect defects. If the unique reflectance (pattern of reflection intensity) is suitable for the sorting conditions, multiple types of substances can also be distinguished simultaneously.

12 to 20 show examples of reflection intensity patterns (spectra) of each material. FIG. 12 shows a nickel (Ni) pattern. FIG. 13 shows an aluminum (Al) pattern. FIG. 14 shows an iron (Fe) pattern. FIG. 15 shows a magnesium oxide (MgO) pattern. FIG. 16 shows a carbon graphite pattern. FIG. 17 shows an iron oxide (Fe ₂ O ₃ ) pattern. FIG. 18 shows a silicon (Si) pattern. FIG. 19 shows a PET (polyethylene terephthalate) pattern. FIG. 20 shows a PMMA (Poly Methyl Methacrylate, an acrylic resin) pattern. The wavelength range of the horizontal axis of each of the figures in FIG. 12 to FIG. 20 is the same. The reflectance values of the vertical axis of each figure are not the same, but the width of one scale (numerical range) is the same.

As shown in Figures 12 to 20, the reflection intensity pattern differs depending on the material. Metals and organic materials are easy to distinguish because the slope of the reflection intensity pattern is significantly different. It is particularly easy to determine that something is "not a metal." However, in the case of materials that show similar reflectance trends, as in Figures 19 and 20, it is difficult to distinguish between them.

If it is determined that the foreign matter is a break in the plating and that the material of the detected foreign matter matches the material of the plating base on the surface of the inspection object W1, it can be inferred that a plating break defect exists on the surface of the inspection object W1.

In this embodiment, the wavelengths of the reflected light received by the photodetector may be multiple, that is, two or more, and the accuracy of the discrimination is improved by increasing the number of wavelengths from two to three or four. When the wavelengths of the reflected light received by the photodetector are two, for example, the photodetector 2C, the plate 4C, and the half mirror 19C shown in FIG. 1 are not necessary. In this case, the reflectance and reflection intensity used for comparison in FIG. 4 and FIG. 5, and the reflectance and reflection intensity obtained by measurement and calculation in FIG. 7 and FIG. 8 are only two, respectively. Therefore, there is only one change rate of the reference reflection intensity and one change rate of the reflection intensity calculated in step S3 of FIG. 3 (see FIG. 6 and FIG. 9). Since there are materials in which the slopes (change rates) of the reflection intensity patterns are locally similar to each other, it is particularly preferable that the wavelengths of the reflected light received by the photodetector are three or more.

When the reflected light received by the photodetector has four wavelengths, a detection mechanism having the same configuration as the photodetector 2C, plate 4C, and half mirror 19C shown in FIG. 1 is provided. The newly provided half mirror is placed, for example, between the half mirror 19C and the condenser lens 18b. In this case, the reflectances and reflection intensities used for comparison in FIG. 4 and FIG. 5, and the reflectances and reflection intensities obtained by measurement and calculation in FIG. 7 and FIG. 8 each have four values. Therefore, the change rate of the reference reflection intensity and the change rate of the reflection intensity calculated in step S3 of FIG. 3 (see FIG. 6 and FIG. 9) have three values.

<Modification 1>
In Fig. 1, a half mirror (e.g., a prism) is used as a means for dispersing reflected light. Alternatively, as shown in Fig. 21, a diffraction grating 40 may be used as a means for dispersing reflected light. That is, the reflected light 3 reflected by the surface SF to be inspected passes through the condenser lenses 18a and 18b in order and is collected. When the reflected light 3 is reflected by the surface of the diffraction grating 40 arranged on the optical axis of the light receiving system, it is split into different optical paths for each wavelength. The light of each wavelength thus split is detected by the photodetectors 2A, 2B, and 2C, respectively. Note that the structure (moving stage 12, etc.) below the object W1 to be inspected is not shown in Fig. 21.

<Modification 2>
1 is a spiral scan type in which the inspection object W1 is rotated, the inspection surface SF is irradiated with laser light, and the moving stage 12 is moved in the X-axis direction. In contrast, the inspection surface SF may be inspected without rotating the inspection object W1 by, for example, scanning the inspection surface SF with laser light in a linear or arc shape and moving the moving stage 12 in the X-axis direction.

Figure 22 is a schematic diagram showing an embodiment of this modified example in which the surface SF to be inspected is inspected by linearly scanning the surface SF with laser light in the Y-axis direction and moving the moving stage 12 in the X-axis direction. As shown in Figure 22, the irradiation range L1 of the laser light is a linear range extending in the X-axis direction in a plan view. When scanning the laser light, the irradiation range L1 of the laser light is scanned linearly in the Y-axis direction, and then the moving stage 12 is moved in the X-axis direction, and the irradiation range L1 of the laser light is scanned linearly again in the Y-axis direction in another area. This makes it possible to scan the surface SF to be inspected. If turning around is required to inspect a wide area of the surface SF to be inspected, the moving stage 12 may be further moved in the Y-axis direction.

The laser light scanning method used here is not a so-called line laser, but a scanning method in which the laser light moves linearly over a specific distance. This laser light scanning in the Y-axis direction can be performed, for example, by using a mirror and changing the angle of the mirror. The laser light scanning method may be either a raster type or a progressive type.

Here, we have described scanning the laser light in the Y direction and moving the movable stage 12 in the X-axis direction, but it is also possible to move the scanning unit in both the X-axis and Y-axis directions without moving the stage. In other words, the object to be inspected W1 may be fixed and the laser scanning line may move (in the Y-axis direction) and turn around (in the X-axis direction). Also, the irradiation position of the laser light itself may not be moved, but the movable stage 12 carrying the object to be inspected W1 may be moved in both the X-axis and Y-axis directions to perform the inspection.

When the moving stage 12 does not rotate the object W1 to be inspected, as in this modified example, the scanning encoder 35 in FIG. 2 becomes a linear encoder for laser beam scanning. Here, the scanning encoder 35 detects the moving distance of the moving stage 12 during scanning and sends an encoder signal to the signal processing circuit 31.

(Embodiment 2)
<Structure of Surface Inspection Device and Surface Inspection Method Using the Same>
Alternatively, a method or device may be used that compares the rate of agreement between the slope of the regression line of the scattering intensity between wavelengths of a previously registered reference material and the slope of the regression line of the scattering intensity between the same wavelengths of a material obtained by a new test that was initially registered, and indicates whether the material is the same or different. In this embodiment, instead of comparing the rate of change in reflection intensity as in the first embodiment, a matching rate is calculated from the slope of the regression line of each wavelength output value, and a threshold value is set for the matching rate to determine whether the material matches or does not match. The reflectance in this embodiment may be reflection intensity.

The configuration of the surface inspection device of this embodiment is the same as that described with reference to Figures 1 and 2. Unlike the above-mentioned embodiment 1, the reflection intensity is not calculated (reflectance x 10), and the slope coefficient (slope) b is obtained using equation (1) shown in Figure 23. Here, b is the slope coefficient of the regression line of the inter-wavelength output, x is the wavelength, and y is the reflectance (reflection intensity, output). When drawing the regression line, the equation y = bx + a can be obtained. a is the intercept.

The surface inspection process in this embodiment is the same as in embodiment 1 above in that light containing three types of wavelengths is irradiated from light source 16, and reflected light 3 reflected from the surface SF to be inspected is separated and received by photodetectors 2A, 2B, and 2C, respectively.

Here, the relationship between wavelength and reflectance is shown in graphs in Fig. 24, Fig. 25 and Fig. 26 for silicon oxide (SiO ₂ ), nickel (Ni) and copper (Cu). In this embodiment, the reflectance is measured at each of the three wavelengths shown in these graphs (values circled in each figure). That is, the reflectance of light at three types of wavelengths, 400 nm, 480 nm and 560 nm, is measured as an example. The measurement results are shown in Fig. 27. However, it is not necessary to measure the reference material. Fig. 27 is a table showing the reflectance at each wavelength for silicon oxide, nickel and copper. The values of each wavelength shown here are examples and are not limited to these.

Next, the comparison and judgment unit 29 calculates the slope coefficient b of the regression line of the output (reflectance) between each wavelength using formula (1). That is, among the three reflectances, the slope coefficient b between the output at the shortest wavelength and the output at the intermediate wavelength is calculated, and the slope coefficient b between the output at the intermediate wavelength and the output at the longest wavelength is calculated. As shown in FIG. 28, for example, the slope coefficient b of the reflectance of silicon oxide between the wavelengths of 400 nm and 480 nm is -0.0000145. Also, the slope coefficient b of the reflectance of silicon oxide between the wavelengths of 480 nm and 560 nm is -0.0000083. The slope coefficient b is calculated similarly for nickel and copper. Note that in a graph in which the reflectance increases as the wavelength increases as in FIG. 25, the slope coefficient b is a positive value, and conversely, in a graph in which the reflectance decreases as the wavelength increases, the slope coefficient b is a negative value.

Figure 28 shows the slope coefficient b for each wavelength of silicon oxide, nickel, and copper. Among these, the slope coefficient b for the reference material is stored in the memory unit 30 before the start of the test.

Next, the match rate between the two materials in each wavelength range is calculated. If the slope coefficient of the reference material is b1 and the slope coefficient of the comparison material (material to be inspected) is b2, the match rate can be calculated using the following formula (2).

Match rate = (|b2-b1|)/|b1| ...(2)
29 shows a table of the coincidence rate of the slope coefficient between each material and the result of the coincidence/non-coincidence judgment. As shown in FIG. 29, for example, silicon oxide, which is a reference material, and The coincidence rate of the slope coefficient between the target material, nickel, in the wavelength range between 480 nm and 560 nm is calculated to be -86666.73%. The closer the coincidence rate is to 100%, the higher the coincidence rate is. The degree of agreement is high. When the slope of the regression line of the reference material and the slope of the regression line of the comparison material are positive and negative, and have opposite slopes, the agreement rate is a negative value. Since the coincidence rate is a negative value, the comparison result in the wavelength region between the wavelengths of 480 nm and 560 nm (determination of wavelength-specific comparison) is a mismatch.

The coincidence rate of the slope coefficient between the reference material, silicon oxide, and the comparison material, nickel, in the wavelength range between 400 nm and 480 nm is calculated to be -6984.42%. Because the coincidence rate is a negative value, the comparison results in the wavelength range between 400 nm and 480 nm (judgment of the wavelength-specific comparison) are not consistent.

At least one of the results of the comparison of the wavelength range between 480 nm and 560 nm and the results of the comparison of the wavelength range between 400 nm and 480 nm is inconsistent, so the overall judgment is inconsistent.

Similarly to the above, FIG. 29 shows the results of comparing silicon oxide with copper, and the results of comparing nickel with copper. Note that the table in FIG. 29 shows a comparison of two materials, silicon oxide, nickel, and copper, but either of the two materials can be the reference material.

When comparing two materials, nickel and copper, the match rate is 48% in one wavelength range and 90% in the other wavelength range. In this case, the overall match rate is the smaller of the match rates in each wavelength range. Therefore, the overall judgment here is a 48% match.

Next, a final determination is made as to whether the reference material and the comparison material are the same material or different materials. Here, if the overall judgment match rate value in the table shown in FIG. 29 is, for example, 60% or higher, it is determined that the reference material and the comparison material are the same material or similar materials. Of the two materials, nickel and copper, the overall judgment match rate is 48%, which is not 60% or higher, so it can be ultimately determined that the reference material and the comparison material are different materials. This standard value of 60% can be changed as appropriate.

In this manner, in this embodiment, the slope coefficient of the regression line of the reflectance between multiple wavelengths for the reference material is stored (registered) in the storage unit 30. Then, in the inspection process, the surface of the inspection object W1 is irradiated with light of the multiple wavelengths, the reflected light of the multiple wavelengths is received, and the slope coefficient of the regression line of the reflectance between those wavelengths is calculated by the comparison judgment unit 29 using formula (1). After that, the comparison judgment unit 29 calculates the agreement rate between the pre-stored slope coefficient and the slope coefficient obtained by the inspection using formula (2), and judges the agreement rate in each wavelength range and the agreement rate obtained by combining the agreement rates in each wavelength range. Next, if the agreement rate of the overall judgment is equal to or greater than a reference value, it is judged that the reference material and the comparison material are the same material or similar materials, and if the agreement rate of the overall judgment is less than the reference value, it is judged that the reference material and the comparison material are different materials.

<Effects of the embodiment>
In this embodiment, as in the first embodiment, the rate of change in reflectance is not affected even if the reflection intensity of the reflected light is large or small depending on the size of the foreign matter. Therefore, the material of the foreign matter can be determined with high accuracy regardless of the size of the foreign matter. In other words, the performance of the surface inspection device and the surface inspection method can be improved.

The inspection in this embodiment is not limited to metals, nonmetals, alloys, organic matter, oxidized/reduced matter, organic matter, etc., and does not identify a specific type of element, but rather records (registers) the slope coefficient of the regression line of the reflectance for each wavelength of the material to be distinguished in advance, and judges whether it matches that pattern or not. For this reason, it is necessary to register the slope coefficient of the regression line of the reflectance of the material to be distinguished before inspection. If the material of the foreign matter that is present in advance can be predicted to some extent, it is also effective to set the wavelength of light detected by the photodetector to a range that has a characteristic pattern of the reflection intensity of the material.

In this embodiment, the wavelengths of the reflected light received by the photodetector need only be multiple, i.e., two or more, and increasing the number of wavelengths from two to three or four increases the accuracy of discrimination. Since there are materials in which the slopes of the regression lines of reflectance are locally similar to each other, it is particularly preferable that the wavelengths of the reflected light received by the photodetector are three or more.

The invention made by the inventor has been specifically described above based on the embodiment, but it goes without saying that the invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention.

Some of the other contents described in the embodiments are described below.

(Supplementary Note 1) A surface inspection method for inspecting a surface of an object to be inspected for foreign particles using a surface inspection device having a control unit and a storage unit, comprising:
(a) irradiating the inspection surface of the inspection object with light of a plurality of wavelengths;
(b) detecting a reflection intensity for each of the plurality of wavelengths of light by detecting a reflected light from the foreign matter;
(c) a step in which the control unit compares a value of a first change rate between the reflection intensities of light of two wavelengths among the plurality of wavelengths with a value of a second change rate between the reflection intensities of light of the two wavelengths of a reference material, the value being a value stored in advance in the storage unit, thereby determining whether the reference material and the material of the foreign matter match;
having
the number of the plurality of wavelengths is three or more;
The step (c) comprises:
(c1) comparing the value of the first rate of change between the reflection intensities of the light at the two wavelengths with a value of the second rate of change between the reflection intensities of the light at the two wavelengths of a reference material, the value being stored in advance in the storage unit;
(c2) comparing a value of a third change rate between the reflection intensities of light of other two wavelengths, which is a combination different from the two wavelengths among the plurality of wavelengths, with a value of a fourth change rate between the reflection intensities of light of the other two wavelengths of the reference material, which is a value stored in advance in the storage unit;
having
(c3) A surface inspection method for comprehensively determining whether the reference material and the material of the foreign matter match or not based on the comparison results of the (c1) step and the (c2) step.

(Appendix 2) A surface inspection apparatus for inspecting a surface of an object to be inspected for foreign matter, comprising:
a light source that irradiates the surface to be inspected with light of a plurality of wavelengths;
a photodetector for detecting reflected light from the foreign object irradiated with light of the plurality of wavelengths;
A control unit connected to the photodetector;
A storage unit connected to the control unit;
having
the control unit calculates reflection intensities corresponding to the respective wavelengths from the reflected light detected by the photodetector, and compares a value of a first rate of change between the reflection intensities of light of two wavelengths among the plurality of wavelengths with a value of a second rate of change between the reflection intensities of light of the two wavelengths of a reference material, the second rate of change being a value stored in advance in the storage unit, the second rate of change being a value of a reference material; and
the number of the plurality of wavelengths is three or more;
The control unit compares the value of the first change rate between the reflection intensities of the light of the two wavelengths with the value of the second change rate between the reflection intensities of the light of the two wavelengths of the reference material, which is a value pre-stored in the memory unit, and compares the value of a third change rate between the reflection intensities of the light of other two wavelengths, which is a combination different from the two wavelengths among the multiple wavelengths, with a value pre-stored in the memory unit and a fourth change rate between the reflection intensities of the light of the other two wavelengths of the reference material, and makes a comprehensive judgment on whether the reference material and the material of the foreign matter match from the two comparison results obtained by these two comparisons.

1 Surface inspection device 2A, 2B, 2C Photodetector 3 Reflected light 4A, 4B, 4C Plate 11 Support table 12 Moving stage 13 Rotation motor 15 Chuck 16 Light source 17 Focus lens 18a, 18b Condenser lens 19B, 19C Half mirror 23 Optical filter 29 Comparison judgment unit 30 Memory unit 31 Signal processing circuit 32 I/V converter 33 Amplifier 34 A/D converter 35 Scanning encoder 37 Mapping unit 38 Defect number judgment unit 39 Comparison judgment processing unit 40 Diffraction grating SF Inspected surface W1 Inspected object

Claims (8)

A surface inspection method for inspecting a surface of an object to be inspected for foreign matter using a surface inspection device having a control unit and a storage unit, comprising:
(a) irradiating the inspection surface of the inspection object with light of a plurality of wavelengths;
(b) detecting a reflection intensity for each of the plurality of wavelengths of light by detecting a reflected light from the foreign matter;
(c) a step in which the control unit compares a value of a first change rate between the reflection intensities of light of two wavelengths among the plurality of wavelengths with a value of a second change rate between the reflection intensities of light of the two wavelengths of a reference material, the value being a value stored in advance in the storage unit, thereby determining whether the reference material and the material of the foreign matter match;
A surface inspection method comprising the steps of: 2. The surface inspection method according to claim 1,
In the step (c), a match is determined when the value of the first change rate is within a matching range centered on the value of the second change rate, and a mismatch is determined when the value of the first change rate is not within the matching range. A surface inspection method for inspecting a surface of an object to be inspected for foreign matter using a surface inspection device having a control unit and a storage unit, comprising:
(a) irradiating the inspection surface of the inspection object with light of a plurality of wavelengths;
(b) detecting a reflectance for each of the plurality of wavelengths of light by detecting reflected light from the foreign matter;
(c) the control unit calculates a rate of agreement between a slope of a regression line between the reflectances of light at two wavelengths among the plurality of wavelengths and a value stored in advance in the storage unit, the slope of a regression line between the reflectances of light at the two wavelengths of the reference material, and determines whether the reference material and the material of the foreign matter match based on the rate of agreement;
A surface inspection method comprising the steps of: A surface inspection device for inspecting a surface of an object to be inspected for foreign matter, comprising:
a light source that irradiates the surface to be inspected with light of a plurality of wavelengths;
a photodetector for detecting reflected light from the foreign object irradiated with light of the plurality of wavelengths;
A control unit connected to the photodetector;
A storage unit connected to the control unit;
having
The control unit calculates reflection intensities corresponding to each of the multiple wavelengths from the reflected light detected by the photodetector, and compares the value of a first change rate between the reflection intensities of light of two of the multiple wavelengths with a value stored in advance in the memory unit, which is a second change rate between the reflection intensities of light of the two wavelengths of a reference material, thereby determining whether the reference material and the material of the foreign matter match. 5. The surface inspection apparatus according to claim 4,
The control unit determines that there is a match when the value of the first change rate is within a matching range centered on the value of the second change rate, and determines that there is a mismatch when the value of the first change rate is not within the matching range. 5. The surface inspection apparatus according to claim 4,
The surface inspection apparatus further comprises a scanner that relatively scans an irradiation position of the light of the plurality of wavelengths irradiated from the light source on the surface to be inspected. 7. The surface inspection apparatus according to claim 6,
The control unit displays the position of the foreign matter on the inspected surface based on position information from the scanner. A surface inspection device for inspecting a surface of an object to be inspected for foreign matter, comprising:
a light source that irradiates the surface to be inspected with light of a plurality of wavelengths;
a photodetector for detecting reflected light from the foreign object irradiated with light of the plurality of wavelengths;
A control unit connected to the photodetector;
A storage unit connected to the control unit;
having
The control unit calculates a rate of agreement between the slope of a regression line between the reflectance of light at two of the multiple wavelengths and the slope of a regression line between the reflectance of light at the two wavelengths of the reference material, the value being pre-stored in the memory unit, and determines whether the reference material and the material of the foreign matter match based on the rate of agreement.

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