Residue inspection method and residue inspection device

Abstract

In a residue inspection of a protective film after processing and cleaning of a processed object processed by irradiating laser light to a surface on which the protective film is formed, it is appropriately determined whether or not there is a residue. The residue inspection method determines whether or not there is a residue of the protective film after processing and cleaning of a processed object processed by irradiating laser light to a surface on which the protective film is formed. The residue inspection method determines whether or not there is a residue by determining, using a threshold value, an intensity of reflected light of measurement light irradiated to a surface of the processed object or fluorescence excited by the measurement light. The threshold value is set based on an intensity distribution of the reflected light or the fluorescence acquired with respect to the processed object on which the protective film is not formed.

Description

Technical Field

[0001] The disclosed technology relates to residue inspection methods and residue inspection devices. Background Technology

[0002] In laser processing, where lasers are used to process semiconductor wafers and other workpieces, after the workpiece coated with a protective film is ablated using a laser, every piece of debris and protective film that has been scattered and adhered during the ablation process is cleaned. Sometimes, after cleaning, protective film residue remains on the surface of the workpiece. This residue, or protective film contamination, can be a major cause of poor electrical properties. Therefore, it is desirable to inspect for protective film contamination remaining on the surface of the workpiece after cleaning.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2022-178427 Patent Document 2: Japanese Patent Application Publication No. 2006-310395 Summary of the Invention The purpose of the disclosed technology is to properly determine the presence or absence of residue during the inspection of the protective film residue after processing and cleaning of a workpiece processed by irradiating a surface with a protective film with a laser.

[0004] The residue inspection method disclosed herein is a method for determining the presence or absence of residue of the protective film after processing and cleaning of a workpiece processed by irradiating a surface with a protective film with a laser. The residue inspection method determines the presence or absence of residue by using a threshold to determine the intensity of reflected light or fluorescence excited by the measurement light irradiating the surface of the workpiece. The threshold is set based on the intensity distribution of the reflected light or fluorescence obtained for the workpiece without the protective film.

[0005] The workpiece may also have a first portion with relatively high intensity of reflected light or fluorescence and a second portion with relatively low intensity for workpieces without the protective film. The threshold values ​​set for the first portion and the second portion may differ from each other.

[0006] The inspection device used to determine the presence or absence of the residue can also be used to determine the formation state of the protective film on the workpiece before processing. The inspection device can also be positioned around the cleaning workbench where the workpiece is cleaned or around the transport path of the workpiece. Abnormalities in the inspection device can be detected based on the determination result of the protective film formation state or the presence or absence of the residue. When determining the presence or absence of the residue versus determining the formation state of the protective film, at least one of the determination area on the workpiece, the irradiation range of the measuring light, and the irradiation time of the measuring light may differ.

[0007] The presence or absence of the residue can be determined for a specific area of ​​the workpiece. This specific area may be at least one of the following: the outer peripheral area of ​​the workpiece, the area where the electrode pads are formed on the workpiece and its surrounding area, an area with uneven surfaces, an area along the radial direction of the workpiece, an area prone to residue formation, and an area determined to be abnormal in the determination of the protective film's formation state.

[0008] The processing of the object to be processed can be carried out by forming a groove on the object by laser irradiation. In determining whether or not the residue is present, areas where the groove has been formed or areas where the groove is expected to be formed can be excluded from the object to be processed.

[0009] The processing state of the object being processed can be determined based on the image formed by the reflected light obtained in the determination of the presence or absence of the residue.

[0010] If the presence of residue is determined to be present, re-cleaning conditions for removing the residue can be set based on any one of the location where the residue is generated, the area of ​​the residue, and the thickness of the residue.

[0011] If the presence or absence of residue is determined to be present, the implementation conditions for determining the presence or absence of residue again after the re-washing to remove the residue can be set according to any one of the location where the residue is generated, the area of ​​the residue, and the thickness of the residue.

[0012] Other residue inspection methods disclosed in the technology involve determining the presence or absence of residue of the protective film after processing and cleaning of a workpiece processed by irradiating a surface with a protective film with a laser. The residue inspection method determines the presence or absence of residue based on the interference spectrum of the reflected light of the measurement light irradiated to the electrode pads provided on the workpiece.

[0013] The residue inspection device disclosed herein is a device for determining whether or not residue of the protective film is present after processing and cleaning of a workpiece processed by irradiating a surface with a protective film with a laser. The residue inspection device determines the presence or absence of residue by using a threshold value to determine the intensity of reflected light or fluorescence excited by the measuring light irradiating the surface of the workpiece. The threshold value is set based on the intensity distribution of the reflected light or fluorescence obtained for the workpiece without the protective film.

[0014] Invention Effects According to the disclosed technology, the presence or absence of residue can be appropriately determined during the inspection of the protective film residue after processing and cleaning of a workpiece processed by irradiating a surface with a protective film with a laser. Attached Figure Description

[0015] Figure 1 This is a process flow diagram illustrating an example of the processing steps of the object to be processed according to an embodiment of the disclosed technology.

[0016] Figure 2A This is a cross-sectional view showing an example of the state of the workpiece in each processing step involved in the implementation of the disclosed technology.

[0017] Figure 2B This is a cross-sectional view showing an example of the state of the workpiece in each processing step involved in the implementation of the disclosed technology.

[0018] Figure 2C This is a cross-sectional view showing an example of the state of the workpiece in each processing step involved in the implementation of the disclosed technology.

[0019] Figure 2D This is a cross-sectional view showing an example of the state of the workpiece in each processing step involved in the implementation of the disclosed technology.

[0020] Figure 3 This is a diagram illustrating an example of the structure of a cleaning apparatus according to an embodiment of the disclosed technology.

[0021] Figure 4 This is a diagram illustrating an example of the structure of a residue inspection device according to an embodiment of the disclosed technology.

[0022] Figure 5A This is a diagram illustrating other structural examples of a residue inspection device according to an embodiment of the disclosed technology.

[0023] Figure 5B This is a diagram illustrating other structural examples of a residue inspection device according to an embodiment of the disclosed technology.

[0024] Figure 6A This is a schematic diagram illustrating an example of the fluorescence intensity distribution when a protective film residue is present on the surface of the workpiece.

[0025] Figure 6B This is a schematic diagram illustrating an example of fluorescence intensity distribution when no protective film is formed on the surface of the object being processed.

[0026] Figure 6C This is a schematic diagram illustrating an example of the fluorescence intensity distribution when a protective film residue is present on the surface of the workpiece.

[0027] Figure 7A This diagram schematically illustrates an example of the intensity distribution of reflected light when no protective film is formed on the surface of the object being processed.

[0028] Figure 7B This is a schematic diagram illustrating an example of the intensity distribution of reflected light when protective film residue is present on the surface of the workpiece.

[0029] Figure 7C This is a diagram illustrating an example of a threshold set based on the intensity distribution of reflected light when no protective film is formed on the surface of the object being processed.

[0030] Figure 7D This is a schematic diagram illustrating an example of the intensity distribution of reflected light when protective film residue is present on the surface of the workpiece.

[0031] Figure 8A This is a diagram showing an example of a protective film residue pattern.

[0032] Figure 8B This is a diagram showing an example of a protective film residue pattern.

[0033] Figure 8C This is a diagram showing an example of a protective film residue pattern.

[0034] Figure 9 It is a diagram showing the outer perimeter area of ​​the object being processed.

[0035] Figure 10A This is a diagram illustrating an example of the trajectory of measuring light illuminating the surface of a workpiece during residue inspection.

[0036] Figure 10B This is a diagram illustrating an example of the trajectory of measuring light illuminating the surface of a workpiece during residue inspection.

[0037] Figure 11 This is a cross-sectional view showing the area around the electrode pads on the object being processed.

[0038] Figure 12 This is a diagram showing the region along the radial direction of the object being processed.

[0039] Figure 13 This is a diagram schematically illustrating the structure of a processing system involved in an embodiment of the disclosed technology.

[0040] Figure 14 This is a diagram schematically illustrating the structure of a processing system involved in an embodiment of the disclosed technology.

[0041] Figure 15 This is a diagram illustrating an example of the configuration of the transport path and inspection device involved in an embodiment of the disclosed technology.

[0042] Figure 16 This is a graph showing an example of the relationship between the fluorescence intensity emitted from the protective film and the thickness of the protective film.

[0043] Figure 17 This is a flowchart illustrating an example of a process for detecting abnormalities in an inspection device based on the determination of the formation state of the protective film or the determination of the presence or absence of residue.

[0044] Figure 18 This is a diagram illustrating an example of the processing of a determiner corresponding to a fluorescence mode.

[0045] Figure 19 This is a diagram illustrating an example of the processing of a determiner corresponding to a fluorescence mode.

[0046] Figure 20 This diagram illustrates an example of the processing of a determiner corresponding to the reflected light mode.

[0047] Figure 21 This diagram illustrates an example of the processing of a determiner corresponding to the reflected light mode.

[0048] Figure 22A This is a diagram showing an example of re-cleaning condition settings corresponding to the state of residue formation on the protective film.

[0049] Figure 22B This is a diagram showing an example of re-cleaning condition settings corresponding to the state of residue formation on the protective film.

[0050] Figure 22C This is a diagram showing an example of re-cleaning condition settings corresponding to the state of residue formation on the protective film.

[0051] Figure 22D This is a diagram showing an example of re-cleaning condition settings corresponding to the state of residue formation on the protective film.

[0052] Figure 23 This is a diagram showing the reflected light reflected from the surface of the protective film and the reflected light reflected from the surface of the electrode pads.

[0053] Figure 24AThis is a diagram showing an example of an interference spectrum.

[0054] Figure 24B This is a diagram showing an example of an interference spectrum.

[0055] Figure 25 It is a curve obtained by plotting the sum of the differences between the interference spectrum of a certain film thickness and the interference spectrum when the film thickness is zero.

[0056] Explanation of reference numerals in the attached figures 10: The object being processed; 11: Protective film; 11a: Residue; 12: slot; 18: Electrode pads; 20: Cleaning device; 22: Nozzle; 30: Residue inspection device; 31: Optical unit; 32: Light source unit; 33: Optical receiving unit; 36: Light source; 39: Detector; 50: Processing system; 52: Coating workbench; 53: Processing workbench; 54: Clean the workbench; 55: Inspection device; 56: Conveying path. Detailed Implementation

[0057] The following description, with reference to the accompanying drawings, illustrates an example of an embodiment of the disclosed technology. Furthermore, identical or equivalent constituent elements and parts in each drawing are given the same reference numerals, and repeated descriptions are omitted.

[0058] [First Implementation Method] Figure 1 This is a process flow diagram illustrating an example of the processing steps of the object to be processed according to an embodiment of the disclosed technology. Figures 2A to 2D This is a cross-sectional view showing an example of the state of the workpiece at each processing step. The workpiece 10 is typically a semiconductor wafer ( Figure 2A ).

[0059] In process P1, a protective film 11 is formed on the surface of the workpiece 10. Figure 2BIn laser processing, debris containing molten material scattered by laser irradiation adheres to the surface of the workpiece 10. This debris is difficult to remove by cleaning with a cleaning solution alone; for example, debris adhering to electrodes is a major cause of poor electrical properties. By forming a water-soluble protective film 11 on the surface of the workpiece before laser processing, direct contact between the debris and the surface of the workpiece 10 can be prevented because the debris accumulates on the protective film 11. The protective film 11 is formed, for example, by spin coating.

[0060] In step P2, the formation state of the protective film 11 formed in step P1 is inspected. During the inspection of the formation state of the protective film 11, it is determined whether the thickness of the formed protective film 11 is within an appropriate range. If it is determined that the thickness of the protective film 11 is too thick or insufficient (in the case of NG determination), the process is transferred to step P3.

[0061] In step P3, the protective film 11 is removed by cleaning. Then, the process returns to step P1. On the other hand, in the inspection of the formation state of the protective film 11, if it is determined that the thickness of the protective film 11 is within the appropriate range (in the case of OK determination), the process is transferred to step P4. In the inspection of the formation state of the protective film 11, an inspection device of the same type as the inspection device used in the residue inspection of the protective film 11 described later is used.

[0062] In process P4, laser processing is performed on the workpiece 10. Figure 2C In laser processing, a laser is irradiated onto the surface of the workpiece 10, on which a protective film 11 is formed. Laser processing can be any of the following: grooving, full cutting, and scribing. Figure 2C The grooving shown is a process of forming grooves 12 along a dicing track, which divides multiple chips formed on a semiconductor wafer. Full dicing is a process of monolithizing multiple chips formed on a semiconductor wafer. Dicing is a process of forming fine grooves along the dicing track as the starting point for cutting. Debris 13, containing molten material scattered by laser irradiation, accumulates on the surface of the protective film 11. The surface of the workpiece 10 is covered by the protective film 11, thereby preventing direct contact between the debris 13 and the surface of the workpiece 10.

[0063] In process P5, the protective film 11 formed on the surface of the workpiece 10 is removed by cleaning. Figure 2D Since the protective film 11 is water-soluble, it can be removed by cleaning with a cleaning solution. The debris 13 generated by laser irradiation is removed along with the protective film 11.

[0064] Figure 3This figure shows an example of the structure of a single-piece cleaning device 20 used in cleaning the workpiece 10. The cleaning device 20 has a cleaning worktable 21, a nozzle 22, and a control unit 23. The workpiece 10 is placed on a rotatable cleaning worktable 21.

[0065] Nozzle 22 sprays cleaning fluid 24 toward the surface of the workpiece 10 placed on the cleaning worktable 21. Nozzle 22 can move its tip by rotating the support column 25 as a rotation axis. Control unit 23 controls the start, stop, and rotation speed of the cleaning worktable 21, the start, stop, and movement speed of nozzle 22, the supply amount of cleaning fluid 24, and the spray pressure. Control unit 23 controls the movement of the tip of nozzle 22 while rotating the cleaning worktable 21, so that the flow of cleaning fluid 24 washes the entire surface of the workpiece 10.

[0066] In step P6, a residue check of the protective film 11 is performed. The residue of the protective film 11 remaining on the surface of the workpiece 10 after cleaning is a major cause of poor electrical properties. Therefore, a residue check is performed after cleaning to determine the presence or absence of protective film 11 residue. If the residue check indicates the presence of protective film 11 residue (NG determination), the process returns to step P5. That is, cleaning and residue checks are repeated until the protective film 11 is completely removed from the surface of the workpiece 10.

[0067] Figure 4 This diagram illustrates an example of the structure of a residue inspection device 30 used for residue inspection of the protective film 11. The residue inspection device 30 determines the presence or absence of residue on the protective film 11 using either a fluorescence method or a reflected light method. The fluorescence method utilizes fluorescence excited by irradiating the protective film 11, to which a phosphor has been added, with ultraviolet light. The thicker the residue on the protective film 11, the higher the fluorescence intensity. Corresponding to the fluorescence method, the residue inspection device 30 uses fluorescence L1 excited by measurement light L1 irradiated onto the surface of the workpiece 10. 2A The strength is used to determine the threshold to determine whether there is residue in the protective film 11.

[0068] On the other hand, the reflected light method utilizes the reflected light from light irradiating a protective film 11 containing light-absorbing additives. The thicker the residue on the protective film 11, the lower the intensity of the reflected light. The residue inspection device 30, corresponding to the reflection intensity method, measures the reflected light L1 from the measurement light L1 irradiating the surface of the workpiece 10. 2B The strength is used to determine a threshold to identify the presence or absence of residue on the protective film 11. This can be applied in any manner. Figure 4 The coaxial incident illumination device shown.

[0069] The residue inspection device 30 has an optical unit 31 including a light source unit 32, a light receiving unit 33, and an optical element 34, and a detector 35. The light source unit 32 includes a light source 36, a lens 37, and a filter 38. The light receiving unit 33 includes a detector 39, a lens 40, and a filter 41.

[0070] Light source 36 outputs measurement light L1. In the fluorescence mode, a light source that outputs ultraviolet light to excite the phosphor is used as the light source 36. In the reflected light mode, a light source that outputs light with a wavelength corresponding to the light absorption of the protective film 11 is used. Lens 37 determines the size of the spot of measurement light L1 formed on the surface of the workpiece 10. Filter 38 limits the wavelength width of measurement light L1. In the fluorescence mode, a dichroic mirror is used as the optical element 34. The dichroic mirror guides the measurement light L1, which is ultraviolet light, onto the surface of the workpiece 10 by reflecting it, so that the fluorescence L1 emitted from the protective film 11... 2A Through, thus transmitting the fluorescent L 2A The light is guided to the light receiving unit 33. In the case of reflected light, a semi-reflective mirror is used as the optical element 34. The semi-reflective mirror guides the measurement light L1 to the surface of the workpiece 10 by reflecting a portion of the measurement light L1, and guides the reflected light L1 to the surface of the workpiece 10 by reflecting a portion of the measurement light L1. 2B Part of the reflected light passes through L 2B Guided to optical receiving unit 33.

[0071] Filter 41 restricts fluorescence L 2A Or reflected light L 2B The wavelength width. Lens 40 is based on fluorescence L... 2A Or reflected light L 2B The image is formed on the light-receiving surface of the detector 39 by the imaging lens.

[0072] Detector 39 detects fluorescence L 2A Or reflected light L 2B The detector 39 can detect the intensity of the light and output an image corresponding to the detected intensity. The detector 39 may include, for example, a region sensor camera, a linear array sensor camera, a photomultiplier tube, and a beam splitter.

[0073] The workpiece 10 is placed on an inspection table 42. At least one of the inspection table 42 and the optical unit 31 is movable in the XY direction parallel to the main surface of the workpiece 10. That is, the relative position of the inspection table 42 and the optical unit 31 is variable. Therefore, by scanning the entire surface of the workpiece 10 with the measuring light L1, the fluorescence L of the entire surface of the workpiece 10 can be obtained. 2A Or reflected light L 2BWhen the inspection table 42 can rotate, the optical unit 31 can be moved radially along the workpiece 10 while the inspection table 42 is rotated, thereby scanning the entire surface of the workpiece 10 using the measuring light L1. The inspection table 42 can also serve as the cleaning table 21 of the cleaning device 20 (see reference). Figure 3 ).

[0074] The determiner 35 determines the fluorescence L detected by the detector 39. 2A Or reflected light L 2B The intensity of the fluorescence is used to determine a threshold, thereby determining whether there is residue on the protective film 11. The determiner 35 determines the presence or absence of residue by analyzing the fluorescence intensity output from the detector 39. 2A Or reflected light L 2B The computer structure that analyzes images.

[0075] In the fluorescence mode, the determiner 35 detects the fluorescence L detected by the detector 39. 2A In areas where the intensity is higher than the threshold, it is determined that there is residue of protective film 11 on the surface of the workpiece 10 (NG determination), and in the absence of fluorescence L detected by detector 39 2A If the intensity of the area is higher than the threshold, it is determined that there is no residue of the protective film 11 on the surface of the processed object 10 (OK determination).

[0076] In the case of reflected light, the determiner 35 determines the presence of reflected light L detected by the detector 39. 2B In areas where the intensity is lower than the threshold, it is determined that there is residue of protective film 11 on the surface of the workpiece 10 (NG determination), and no reflected light L is detected by detector 39. 2B In areas where the intensity is lower than the threshold, it is determined that there is no residue of protective film 11 on the surface of the processed object 10 (OK determination).

[0077] Detector 35 can also be based on fluorescence L 2A Or reflected light L 2B The intensity of the fluorescence was used to deduce the residue thickness of the protective film 11. 2A and reflected light L 2B The strength of each component is correlated with the thickness of the residue on the protective film 11. The determiner 35 can then determine the fluorescence intensity based on the value of the fluorescent L. 2A Or reflected light L 2B The information on the relationship between the intensity and the residue thickness of the protective film 11 was used to deduce the fluorescence L detected by the detector 39. 2A Or reflected light L 2B The strength corresponds to the thickness of the residue in the protective film 11.

[0078] Figure 5AThis is a diagram showing other structural examples of the residue inspection device 30 corresponding to the fluorescence method. Figure 5A In the example shown, the light source unit 32 is configured such that the measuring light L1 enters from a direction inclined relative to the surface of the workpiece 10. The light receiving unit 33 is positioned directly above the workpiece 10. Furthermore, due to the fluorescence L... 2A It scatters isotropically regardless of the incident angle of the measured light L1, so it is not necessary to position the light receiving unit 33 symmetrically relative to the light source unit 32. Figure 5A The structure shown illuminates the measuring light L1 over a wide area of ​​the surface of the workpiece 10, enabling it to receive fluorescence L emitted from the workpiece 10 over a wide area. 2A That is, according to Figure 5A The structure shown can expand the shooting range for each shot, thus reducing the time required for residue inspection.

[0079] Figure 5B This is a diagram showing other structural examples of the residue inspection device 30 corresponding to the reflected light method. Figure 5B In the example shown, the light source unit 32 is configured such that the measurement light L1 enters from a direction inclined relative to the surface of the workpiece 10. The light receiving unit 33 is positioned symmetrically relative to the light source unit 32 so as to receive the reflected light L1, which is reflected at a reflection angle equal to the incident angle of the measurement light L1. 2B .according to Figure 5B The structure shown illuminates the measuring light L1 over a wide area of ​​the surface of the workpiece 10, and is able to receive the reflected light L emitted from the workpiece 10 over a wide area. 2B That is, according to Figure 5B The structure shown can expand the shooting range for each shot, thus reducing the time required for residue inspection.

[0080] As described above, the determiner 35 determines the fluorescence L by... 2A Or reflected light L 2B The intensity of the light is used to determine the threshold value to identify the presence or absence of residue on the protective film 11. The threshold setting for residue inspection will be explained below. First, the threshold setting in the fluorescence mode will be explained. Figure 6A This is a schematic diagram illustrating an example of the fluorescence intensity distribution when a protective film residue 11a exists on the surface of the workpiece 10. Figure 6A In the example 10, a semiconductor wafer with multiple chips is shown as the object of processing.

[0081] The protective film 11 containing the phosphor fluoresces upon exposure to ultraviolet light. Therefore, fluorescence is detected in the region where the protective film is present on the residue 11a. Since the residue 11a is typically thin, the intensity of the detected fluorescence is low. To reliably detect the residue 11a, a threshold TH1 lower than the fluorescence intensity in the region where the residue 11a is present is required.

[0082] On the other hand, in the semiconductor wafer 10 being processed, there exists a specific region 15 that emits fluorescence regardless of the presence or absence of a protective film 11. This specific region 15 is thought to be caused by impurities, oxide films, nanostructures, or damaged areas within the semiconductor wafer. If the intensity of the fluorescence emitted from the specific region 15 is higher than the fluorescence intensity of the region where residue 11a is present, and a threshold TH1 is used for determination, the specific region 15 would be mistakenly identified as a region containing protective film residue. To avoid this misjudgment, if a threshold TH2, which has a higher fluorescence intensity than the specific region 15, is used for determination, the residue 11a would be missed.

[0083] Thus, when using a single threshold TH1 or TH2 to determine the presence or absence of residue, it is difficult to avoid misjudgments and missed detections. Therefore, in the residue inspection method according to the embodiments of the disclosed technology, the threshold TH is set based on the intensity distribution of fluorescence obtained for the processed object 10 for which a protective film 11 has not been formed.

[0084] Figure 6B This is a diagram showing an example of the fluorescence intensity distribution obtained for a processed object 10 without a protective film 11. In the processed object 10 without a protective film 11, a fluorescence intensity distribution can be obtained where the fluorescence intensity of a specific portion 15 is higher than that of other portions. Figure 6B The threshold TH, indicated by the dashed line, is achieved by making Figure 6B The fluorescence intensity distribution shown by the solid line is set to shift towards the high intensity side. For example, the threshold TH can also be set by adding or multiplying the fluorescence intensity at each location of the processed object 10 for which the protective film 11 has not been formed by a predetermined value.

[0085] For the threshold TH set as described above, the value set for the specific portion 15 is different from the value set for the portions other than the specific portion 15. By using the threshold TH set as described above, such as Figure 6C As shown, it is possible to detect the residue 11a of the protective film while avoiding misjudgment of the specific part 15.

[0086] Next, the threshold setting for the reflected light mode will be explained. Figure 7A This diagram schematically illustrates an example of the intensity distribution of reflected light when a protective film 11 is not formed on the surface of the workpiece 10. Figure 7AIn this example, a semiconductor wafer having multiple chips is used as the workpiece 10. In the reflected light method, the intensity distribution of reflected light, including bright and dark areas, corresponding to the pattern formed on the workpiece 10 is obtained.

[0087] Here, as Figure 7B As shown, suppose that in the case of residue 11a with a protective film present in the bright area, the intensity of reflected light in the area where residue 11a is present is higher than the intensity of reflected light in the dark area. In this case, to reliably detect residue 11a, a threshold TH3 higher than the intensity of reflected light in the area where residue 11a is present is required. However, in this case, the dark area is misclassified as an area where residue 11a with a protective film is present. To avoid this misclassification, if a threshold TH4 lower than the intensity of reflected light in the dark area is used for judgment, the residue 11a will be missed.

[0088] Thus, in the case of reflected light, it is difficult to avoid misjudgment and missed detection when using a single threshold TH3 or TH4 to determine the presence or absence of residue. Therefore, in the residue inspection method according to the embodiments of the disclosed technology, the threshold TH is set based on the intensity distribution of reflected light obtained for the workpiece 10 for which the protective film 11 has not been formed. Figure 7C The threshold TH, indicated by the dashed line, is achieved by making Figure 7C The intensity distribution of reflected light obtained from the workpiece 10 without a protective film 11, as shown by the solid line in the middle, is set to shift towards the low intensity side. For example, the threshold TH can also be set by adding or multiplying a predetermined value to the intensity of reflected light obtained from each location of the workpiece 10 without a protective film 11.

[0089] For the threshold TH set as described above, the values ​​set for the bright areas and the values ​​set for the dark areas are different from each other. By using the threshold TH set as described above, such as Figure 7D As shown, it is possible to detect residue 11a of the protective film while avoiding misjudgment of dark areas.

[0090] Furthermore, the threshold TH is preferably set to a value that deviates from the intensity fluctuation range of the fluorescence or reflected light obtained from the processed object 10 to which the protective film 11 has not been formed. For example, the threshold TH can also be set with a margin of 20% relative to the maximum value of the intensity fluctuation. Alternatively, the threshold TH can be set with a margin of 6 times the standard deviation σ of the intensity fluctuation.

[0091] Regarding the protective film, its formation state is inspected before processing the workpiece. During this inspection, the thickness of the formed protective film is confirmed, and any areas of insufficient film formation are identified. It is also possible to apply the method for inspecting the formation state of the protective film to the inspection of protective film residue. However, since the thickness of the protective film differs between the inspection of its formation state and the inspection of its residue, the method for inspecting the formation state cannot be directly applied to the inspection of protective film residue. According to the residue inspection method and residue inspection apparatus 30 disclosed in the embodiments, the presence or absence of residue can be appropriately determined during the residue inspection of the protective film 11 performed after processing and cleaning of the workpiece 10 processed by irradiating the surface on which the protective film 11 is formed with a laser.

[0092] [Second Implementation] The residue inspection method according to the second embodiment of the disclosed technology determines whether there is residue of protective film 11 only for a part of the processed object 10.

[0093] In residue inspection using optical methods such as fluorescence or reflected light, one method to improve the detection sensitivity of residue on the protective film 11 is to extend the exposure time (slow down the shutter speed) when the detector 39 takes a picture. Alternatively, by focusing the measurement light L1 illuminating the workpiece 10, the inspection sensitivity can also be improved by increasing the illuminance of the measurement light L1.

[0094] However, extending the exposure time increases the time required for a single shot, thus increasing the inspection time. Furthermore, focusing the measuring light L1 narrows the shooting range in a single shot, requiring more shots. Consequently, the inspection time increases. By determining the presence or absence of residue from the protective film 11 only on a portion of the workpiece 10, the increase in inspection time due to improved residue detection sensitivity can be suppressed. An example of a portion of the workpiece being inspected for residue is given below.

[0095] (1) The outer perimeter area of ​​the object being processed; (2) The area where the electrode pads are formed and its surrounding area; (3) It has an uneven area; (4) The region along the radial direction of the object being processed; (5) Areas where protective film residue is easily generated; (6) Areas that are judged as abnormal in the determination of the formation state of the protective film.

[0096] (1) The outer periphery of the object being processed Figures 8A to 8CThese are figures showing an example of the residue pattern on the protective film 11 when the cleaning method performed before residue inspection is rotary cleaning.

[0097] Figure 8A This is a residue pattern of the protective film 11 when the supply of cleaning fluid is insufficient. Since the cleaning fluid flows from the center of the workpiece 10 to the outer periphery, the insufficient supply of cleaning fluid becomes particularly noticeable in the outer peripheral region of the workpiece 10. At this time, residue 11a of the protective film is formed along the outer edge of the workpiece 10.

[0098] Figure 8B This refers to the residue pattern of the protective film 11 when foreign matter 16 adheres to the surface of the workpiece 10. In this case, because the supply of cleaning fluid is obstructed on the downstream side of foreign matter 16, radial residue 11a is generated starting from foreign matter 16.

[0099] Figure 8C This refers to the residue pattern of the protective film 11 when droplets 17 of the protective film adhere to the surface of the workpiece 10. The adhesion of the protective film droplets 17 can occur, for example, due to droplets of the protective film 11 that have been scattered during rotary cleaning re-adhering to the surface of the workpiece 10. In this case, the droplets 17 of the protective film trail towards the outer edge of the workpiece 10, thereby generating residue 11a.

[0100] exist Figures 8A to 8C In any of the patterns shown, the residue 11a of the protective film is present in the outer peripheral region of the workpiece 10, therefore, as Figure 9 As shown, by using a portion of the outer peripheral region 10A containing the workpiece 10 as the residue inspection target, residue 11a can be detected effectively. Compared to using the entire workpiece 10 as the residue inspection target, using only a portion of the outer peripheral region 10A containing the workpiece 10 as the residue inspection target reduces the inspection time.

[0101] In determining whether there is any residue of the protective film 11 on the entire surface of the workpiece 10, for example, the optical unit 31 of the residue inspection device 30 is moved radially along the workpiece 10 while the workpiece 10 is rotated. Thus, as... Figure 10A As shown, the measuring light L1 is scanned in a spiral manner, with the scanning trajectory 19 of the measuring light L1 illuminating the surface of the workpiece 10. In this case, the workpiece 10 needs to be rotated about 500 times, requiring an inspection time of about 10 seconds.

[0102] On the other hand, when the outer peripheral area 10A of the workpiece 10 is used as the object for residue inspection, such as Figure 10BAs shown, the measuring light L1 scans along the outer edge of the workpiece 10 in a circular pattern using the scanning trajectory 19. In this case, only one rotation of the workpiece 10 is required, reducing the inspection time to 0.02 seconds compared to the 10 seconds required to inspect the entire workpiece 10. Furthermore, if residue of the protective film 11 is detected, the inspection time can be further reduced by immediately ending the inspection.

[0103] (2) The formation area of ​​the electrode pad and its surrounding area Figure 11 This is a cross-sectional view showing the periphery of the electrode pad 18 provided on the workpiece 10. A step is formed at the edge of the electrode pad 18. The protective film 11 extending in and around the formation area of ​​the electrode pad 18 is not easily removed by cleaning. Therefore, residue 11a of the protective film easily forms in and around the formation area of ​​the electrode pad 18. Furthermore, if residue 11a of the protective film is present on the electrode pad 18, poor contact may occur with the leads (not shown) bonded to the electrode pad 18. Poor contact between the electrode pad 18 and the leads is a typical problem caused by residue of the protective film 11; it is preferable to ensure that there is no residue of the protective film 11 in and around the formation area of ​​the electrode pad 18.

[0104] By targeting the area containing the electrode pad 18 and a portion of its surrounding area for residue inspection, residue 11a can be effectively detected. Furthermore, poor contact between the electrode pad 18 and the conductor can be avoided. Compared to inspecting the entire workpiece 10 for residue, targeting the area containing the electrode pad 18 and a portion of its surrounding area for residue inspection reduces inspection time.

[0105] Alternatively, the area subject to residue inspection can be limited to a portion of the surface of the electrode pad 18. For example, for a single electrode pad, the corners and the center portion can also be considered for residue inspection. Alternatively, the electrode pads subject to residue inspection can be limited to those disposed within a portion of the workpiece 10. For example, several locations along the radial direction of the workpiece 10 (e.g., the center, outer edge, and middle portion) can also be considered for residue inspection.

[0106] (3) Areas with uneven surfaces The bumps and other uneven areas on the workpiece 10, like the electrode pads 18, are areas where residue of the protective film 11 is easily formed. Furthermore, if residue of the protective film 11 is present in the uneven areas, poor electrical connection may occur. By inspecting a portion of the workpiece 10 containing the uneven areas for residue, residue detection can be performed effectively. Additionally, poor electrical connection can be avoided. By inspecting a portion of the workpiece 10 containing the uneven areas for residue, the inspection time can be shortened compared to inspecting the entire workpiece 10.

[0107] (4) The area along the radial direction of the workpiece When the cleaning method performed before residue inspection is rotary cleaning, the residue trend on the protective film 11 also exhibits a concentric circular distribution due to the concentric circular distribution of the cleaning trend. Therefore, as... Figure 12 As shown, by using the region 10B along the radial direction of the workpiece 10 as the residue inspection target, the residue trend throughout the entire workpiece 10 can be effectively grasped. By using a portion of the region 10B along the radial direction of the workpiece 10 as the residue inspection target, the inspection time can be shortened compared to using the entire workpiece 10 as the residue inspection target.

[0108] In determining whether there is any residue of the protective film 11 on the entire surface of the workpiece 10, such as Figure 10A As shown, the light L1 is scanned by depicting a spiral along the scanning trajectory 19 of the measurement light L1. In this case, the number of measurement points is, for example, approximately 350,000 points, and the radial movement speed of the optical unit 31 is 15 mm / s. As a result, the inspection time is approximately 10 seconds.

[0109] On the other hand, when the region 10B along the radial direction of the workpiece 10 is used as the object for residue inspection, the workpiece 10 is not rotated, but the optical unit 31 is moved radially along the workpiece 10. In this case, even when a full inspection is performed along the radial direction of the workpiece 10, the number of measurement points is 500, and the radial movement speed of the optical unit 31 is 1000 mm / s. As a result, the inspection time can be reduced to 0.15 seconds compared to 10 seconds when inspecting the entire workpiece 10.

[0110] (5) Areas where protective film residue is prone to form By designating a specific area containing a region that is prone to forming a protective film 11 as the residue inspection target, residue inspection can be performed efficiently. For example, a workpiece of the same type as the workpiece 10 that is the residue inspection target can be cleaned under conditions that easily form a protective film 11, and the area where the protective film 11 is formed after cleaning can be designated as the residue inspection target area.

[0111] Alternatively, the locations where residues are detected during residue inspection of the processed object 10 in mass production can be recorded as residue data. By analyzing the residue data, areas prone to residue formation can be identified, and these identified areas can be designated as the target areas for residue inspection. For a portion of the processed object 10, the entire object can also be considered for residue inspection, and the residue data can be updated accordingly. Furthermore, by analyzing the residue data, structures prone to protective film residue formation can be identified, and areas with defined structures can be designated as the target areas for residue inspection.

[0112] (6) Areas identified as abnormal in the determination of the formation state of the protective film. In the determination of the protective film formation state (process P2), areas deemed abnormal (NG) (especially areas with insufficient protective film thickness) are those that are difficult to promote or easily hinder the formation of the protective film. Such areas are prone to producing protective film residue. That is, areas deemed abnormal in the determination of the protective film formation state can be said to have a high probability of producing protective film residue. Therefore, by including a portion of the areas deemed abnormal in the determination of the protective film formation state (process P2) as the target area for residue inspection, residue inspection can be performed effectively.

[0113] Only one of the areas described in (1) to (6) above may be selected as the area to be inspected for residue. Alternatively, residue inspection may be performed on at least one of the areas described in (1) to (6) above, and if residue with protective film 11 is determined to be present (in the case of NG determination), the entire workpiece 10 may be selected as the area to be inspected for residue. Alternatively, residue inspection may be terminated at the point in time when residue with protective film 11 is determined to be present.

[0114] [Third Implementation Method] In the residue inspection method according to the third embodiment of the disclosed technology, the residue inspection device 30 used in the determination of the presence or absence of residue of the protective film 11 (step P6) is also used for the determination of the formation state of the protective film 11 (step P2). That is, the inspection device is used in both the inspection of the formation state of the protective film 11 (step P2) and the residue inspection (step P6).

[0115] Figure 13 It is an illustrative representation of the implementation. Figure 1The diagram shows the structure of the processing system 50 for each process from process P1 to process P6 in the process flow diagram shown. The processing system 50 includes a material box 51, a coating workbench 52, a processing workbench 53, a cleaning workbench 54, and an inspection device 55.

[0116] Multiple workpieces 10 are stored in the material box 51. A protective film 11 is formed on the surface of the workpieces 10 in the coating table 52 (step P1). The workpieces 10 taken from the material box 51 are placed on the coating table 52 via a transport path (not shown). The protective film 11 is formed on the surface of the workpieces 10 in the coating table 52, for example, by spin coating.

[0117] Laser processing (step P4) is performed on the workpiece 10 in the processing worktable 53. The workpiece 10, with a protective film 11 coated on its surface, is placed on the processing worktable 53 via a transport path (not shown).

[0118] In the cleaning worktable 54, the protective film 11 formed on the surface of the workpiece 10 is removed by cleaning (step P5). The workpiece 10, which has undergone laser processing, is placed on the cleaning worktable 54 via a transport path (not shown). In the cleaning worktable 54, the protective film 11 is removed, for example, by rotational cleaning.

[0119] Inspection device 55 is equivalent to the above-mentioned residue inspection device 30 (refer to) Figure 4 , Figure 5A , Figure 5B The inspection device 55 is used to inspect the formation state of the protective film 11 (step P2) and to inspect for residues (step P6). To prevent foreign matter from adhering to the inspection device 55, it is preferably positioned around the periphery of the cleaning workbench 54 or around the transport path of the workpiece 10. Since foreign matter generated during processing at the coating workbench 52 and processing workbench 53 is prone to scattering around them, it is preferable not to position the inspection device 55 around these workbench areas.

[0120] like Figure 13 As shown, the inspection device 55 can also be positioned directly above the cleaning worktable 54. In this case, after the protective film 11 is formed in the coating worktable 52, the workpiece is placed on the cleaning worktable 54 via a transport path (not shown). The workpiece 10 placed on the cleaning worktable 54 is inspected for the formation status of the protective film 11 using the inspection device 55 (step P2). Furthermore, after cleaning is completed in the cleaning worktable 54 (step P5), the workpiece 10 placed on the cleaning worktable 54 is inspected for residue using the inspection device 55 (step P6).

[0121] like Figure 14As shown, the inspection device 55 can also be positioned directly above the transport path 56 of the workpiece 10. The transport path 56 is provided between worktables and between the worktable and the material box. After the protective film 11 is formed, the workpiece 10 transported from the coating worktable 52 toward the processing worktable 53 is inspected using the inspection device 55 to check the formation state of the protective film 11 (step P2). After cleaning, the workpiece 10 transported from the cleaning worktable 54 toward the material box 51 is inspected for residue using the inspection device 55 (step P6).

[0122] like Figure 15 As shown, the conveying path 56 may have a first conveying path 56A for conveying the workpiece 10 before cleaning and a second conveying path 56B for conveying the cleaned workpiece 10 after cleaning. The first conveying path 56A and the second conveying path 56B may be set at different heights. In this case, the inspection device 55 is configured to be able to change its position in the height direction (Z direction). Alternatively, the optical system of the inspection device 55 is designed such that both the first conveying path 56A and the second conveying path 56B are included in the depth of field.

[0123] In the inspection of the formation state of the protective film 11 (step P2), it is determined whether the thickness of the formed protective film 11 is within an appropriate range. By using the threshold used in this determination and the data (e.g., fluorescence intensity) obtained in the residue inspection (step P6), the appropriateness of the cleaning (step P5) can be evaluated.

[0124] Figure 16 This is a graph showing an example of the relationship between the fluorescence intensity emitted from the protective film 11 and the thickness of the protective film 11. The thicker the protective film 11, the higher the fluorescence intensity emitted from the protective film 11. In the inspection of the formation state of the protective film 11 (step P2), a threshold for fluorescence intensity is set according to an appropriate range of the thickness of the formed protective film 11.

[0125] If the fluorescence intensity obtained during residue inspection (step P6) falls within the upper and lower limits of the fluorescence intensity set during the inspection of the protective film formation state (step P2) (e.g., around 200 lx), it can be presumed that there is no cleaning effect at all. In this case, the cause is considered to be a malfunction in the cleaning fluid supply mechanism or inappropriate cleaning conditions, and it can be determined that countermeasures need to be taken based on the cause (repairing the cleaning fluid supply mechanism or fundamentally readjusting the cleaning conditions).

[0126] If the fluorescence intensity obtained during residue inspection (step P6) is slightly lower than the lower limit of fluorescence intensity set in the inspection of the protective film formation state (step P2) (e.g., 100 to 150 lx), it can be inferred that although a cleaning effect is observed, the cleaning is insufficient. In this case, it can be determined that the cleaning conditions need to be significantly readjusted.

[0127] If the fluorescence intensity obtained during residue inspection (step P6) is significantly lower than the lower limit of fluorescence intensity set in the inspection of the protective film formation state (step P2), but exceeds the threshold set in residue inspection (step P6) (e.g., 50 lx), it can be inferred that cleaning has been largely but not completely performed. In this case, it can be determined that optimization by fine-tuning the cleaning conditions is necessary.

[0128] In the inspection of the formation state of the protective film 11 (process P2) and the inspection of residue (process P6), when the inspection device 55 (residue inspection device 30) is used, the abnormality of the inspection device 55 can also be detected based on the determination result of the formation state of the protective film 11 or the determination result of whether there is residue.

[0129] For example, suppose that fluorescent foreign matter (e.g., droplets of the protective film) is attached to the optical path of the inspection device 55 corresponding to the fluorescence method. In this case, the portion with attached fluorescent foreign matter is determined by the detector 35 to be the presence of the protective film 11. During the inspection of the formation state of the protective film 11 (step P2), if the portion of the protective film 11 that is insufficient is obscured by the fluorescent foreign matter, the insufficiency of the protective film 11 cannot be detected. On the other hand, during the residue inspection (step P6), since the fluorescent foreign matter is detected as residue, NG (no good) judgments occur frequently. Therefore, during the residue inspection (step P6), if NG judgments occur frequently, it can be presumed that the inspection device 55 is malfunctioning (fluorescent foreign matter attachment).

[0130] Next, let's assume a situation where non-fluorescent foreign matter (e.g., cutting chips, dust) adheres to the optical path of the inspection device 55 corresponding to the fluorescent method. In this case, the determination unit 35 determines that the portion with the non-fluorescent foreign matter is missing the protective film 11. During the residue inspection (step P6), when the residue of the protective film 11 is obscured by the non-fluorescent foreign matter, the residue of the protective film 11 cannot be detected. On the other hand, during the inspection of the formation state of the protective film 11 (step P2), since the non-fluorescent foreign matter is detected as a portion of the protective film 11 that is insufficient, NG (no good) determinations occur frequently. Therefore, during the inspection of the formation state of the protective film 11 (step P2), if NG determinations occur frequently, it can be presumed that the inspection device 55 is malfunctioning (non-fluorescent foreign matter adhesion).

[0131] Next, let's assume that no measuring light L1 is output from the light source 36 of the inspection device 55. In this case, the determiner 35 corresponding to the fluorescence mode determines that there is no protective film covering the entire surface of the workpiece 10. In the residue inspection (step P6), since no residue of the protective film 11 is detected, all workpieces 10 are judged as OK. On the other hand, in the inspection of the formation state of the protective film 11 (step P2), since insufficient protective film 11 is detected, all workpieces 10 are judged as NG. Therefore, in the inspection of the formation state of the protective film 11 (step P2), if NG judgments occur frequently, it can be presumed that the inspection device 55 is malfunctioning (abnormal output of the measuring light).

[0132] On the other hand, in the determiner 35 corresponding to the reflected light mode, without outputting the measuring light L1, it is determined that a protective film 11 exists on the entire surface of the workpiece 10. During the inspection of the formation state of the protective film 11 (step P2), since no deficiency of the protective film 11 is detected, all workpieces 10 are determined to be OK. On the other hand, during the residue inspection (step P6), residue that is part of the protective film 11 is detected, therefore all workpieces 10 are determined to be NG. Therefore, during the residue inspection (step P6), if NG determinations occur frequently, it can be presumed that the inspection device 55 is malfunctioning (the output of the measuring light is abnormal).

[0133] Figure 17 This is a flowchart illustrating an example of a process for detecting abnormalities in inspection device 55 based on the determination of the formation state of the protective film or the determination of the presence or absence of residue. Figure 17 In the flowchart shown, relative to Figure 1 The process flow shown includes additional processes P0, P2A, P2B, P2C, P4A, P6A, P6B, and P6C. The following is a description of each of these additional processes.

[0134] In process P0, the initial value 0 is set to the count value p of the number of NG (Not Good) determinations in the determination of the formation state of the protective film 11 (process P2). If an NG determination is made in the determination of the formation state of the protective film 11 (process P2), the count value p of the number of NG determinations increases in process P2A. In process P2B, it is determined whether the count value p of the number of NG determinations has reached the maximum value p. max The count p of the number of times an NG decision was made has not reached its maximum value p. max In this case, the process is transferred to process P3, where the count p of the number of times an NG decision is made reaches its maximum value p. maxIn the event of an abnormality, the process is transferred to process P2C. In process P2C, an alarm is triggered to notify the inspection device 55 that an abnormality has occurred. For example, the alarm can be triggered using a display, speaker, and lights provided by the processing system 50.

[0135] After laser processing of the workpiece 10 in process P4, in process P4A, the initial value 0 is set to the count value q of the number of NG (Not Good) judgments in the residue presence / absence determination (process P6). If an NG judgment is made in the residue presence / absence determination (process P6), the count value q of the NG judgment count increases in process P6A. In process P6B, it is determined whether the count value q of the NG judgment count has reached its maximum value q. max The count q for the number of times an NG decision was made has not reached its maximum value q. max In this case, the process returns to step P5, where the count q of the number of times an NG decision is made reaches its maximum value q. max In the event of an abnormality, the process is transferred to step P6C. In step P6C, an alarm is triggered to inform the inspection device 55 that an abnormality has occurred. Furthermore, in determining the formation status of the protective film (step P2), it can also be indicated that insufficient protective film may not have been properly detected. For example, the alarm can be triggered using the display, speaker, and lights provided by the processing system 50.

[0136] In the case of determining whether there is protective film residue (step P6) and in the case of determining the formation state of the protective film (step P2), at least one of the determination object part, the irradiation range of the measuring light L1 and the irradiation time of the measuring light L1 in the processing object 10 may be different.

[0137] When determining the presence or absence of residue on the protective film 11 (step P6), a higher detection sensitivity is required for detecting the protective film 11 than when determining the formation state of the protective film 11 (step P2). Therefore, the irradiation range of the measuring light L1 when determining the presence or absence of residue on the protective film 11 (step P6) can be smaller than that when determining the formation state of the protective film 11 (step P2). The irradiation time of the measuring light L1 when determining the presence or absence of residue on the protective film 11 (step P6) can also be longer than that when determining the formation state of the protective film 11 (step P2). If the irradiation range of the measuring light L1 is reduced and the irradiation time of the measuring light L1 is extended, the inspection time will increase. Therefore, in order to suppress the increase in inspection time, in the determination of whether there is residue of the protective film 11 (process P6), only a part of the processed object 10 can be used as the determination object area, and in the determination of the formation state of the protective film 11 (process P2), the entire processed object 10 can be used as the determination object area.

[0138] In addition, the inspection device 55 can also be configured to switch optical elements such as light source, filter, and lens, and can switch optical elements when determining whether there is residue on the protective film 11 (step P6) and when determining the formation state of the protective film 11 (step P2).

[0139] Alternatively, an inspection device 55 corresponding to the reflected light method can be used to determine the processing status of the workpiece 10. The processing status determination can be performed, for example, before or after determining the presence or absence of residue of the protective film 11 (step P6). In determining the processing status, the reflected light L1 of the measuring light L1 irradiating the workpiece 10 can also be used. 2B The resulting image is used to determine the shape (width, depth), location of the groove 12 formed by laser processing, and the adhesion of debris.

[0140] [Fourth Implementation Method] In the fourth embodiment of the disclosed technology, the residue inspection method excludes areas where grooves 12 are formed by laser processing or areas where grooves 12 are expected to be formed from the determination of whether there are residues (step P6).

[0141] Figure 18 This is a diagram showing an example of the processing of the determiner 35 corresponding to the fluorescence mode. Figure 18 (a) is a diagram showing an example of a decision object region 60 of a unit determined by the decision maker 35. Figure 18 (b) is a diagram showing an example of a reference region 61 having the same intermediate mask pattern as the determination object region 60. As shown... Figure 18 As shown in (a), the target area 60 includes a groove 12 formed by laser processing of the workpiece 10, residue 11a of the protective film, and a fluorescent special portion 15, assuming that the special portion 15 and a portion of the groove 12 overlap. The reference area 61 does not contain residue of the protective film 11. Figure 18 (c) is the fluorescence image I of the target region 60. F1 , Figure 18 (d) is the fluorescence image of reference region 61. F2 .

[0142] Detector 35 generates a fluorescence image I of the target region 60. F1 Fluorescence image I of reference region 61 F2 The difference image is obtained from the difference, and then a binary image I is generated by binarizing the difference image. B In the binarized image I BIf the total number of pixels with a pixel value of "1" assigned to pixels with high fluorescence intensity exceeds a predetermined number, the determiner 35 determines that residue of the protective film 11 is present (NG determination). This is based on the fluorescence image I of the target region 60. F1 Fluorescence image I of reference region 61 F2 The differential image is used to determine the presence or absence of residue, which can prevent the exclusion of specific parts 15 with high fluorescence intensity from the determination object and detect specific parts 15 as residue of the protective film 11.

[0143] However, according to the determination based on the differential image, a problem arises when the formation position of the groove 12 contained in the reference region 61 is offset from the formation position of the groove 12 in the determination object region 60. Specifically, if the formation position of the groove 12 is deviated when the special portion 15 and a portion of the groove 12 overlap, then... Figure 19 As shown, the specific portion 15 cannot be completely removed in the differential image. The remaining portion of the specific portion 15 that has not been removed may be detected as residue of the protective film 11.

[0144] Figure 20 This is a diagram showing an example of the processing of the determiner 35 corresponding to the reflected light mode. Figure 20 (a) is a diagram showing an example of a decision object region 60 of a unit determined by the decision maker 35. Figure 20 (b) is a diagram showing an example of a reference region 61 having the same intermediate mask pattern as the determination object region 60. As shown... Figure 20 As shown in (a), the determination object area 60 contains residue 11a of the groove 12 and protective film formed by laser processing of the processing object 10. The reference area 61 does not contain residue of the protective film 11. Figure 20 (c) is the reflected light image I of the target area 60. R1 , Figure 20 (d) is the reflected light image I of reference region 61. R2 .

[0145] Determiner 35 generates a reflected light image I extracted from the target region 60. R1 Image I of reflected light from reference region 61 R2 The difference image is obtained from the difference, and then a binary image I is generated by binarizing the difference image. B In the binarized image I B If the total number of pixels with a pixel value of "1" assigned to pixels with low reflected light intensity exceeds a predetermined number, the determiner 35 determines that residue of the protective film 11 exists (NG determination). This is based on the reflected light image I of the target region 60. R1 Image I of reflected light from reference region 61 R2The differential image is used to determine whether there is residue, which can prevent the exclusion of the groove 12 with low reflected light intensity from the judgment object. The groove 12 is detected as residue of the protective film 11.

[0146] However, similar to the fluorescence method, in the reflected light method, a problem arises when the formation position of the groove 12 contained in the reference region 61 deviates from the formation position of the groove 12 in the determination object region 60, based on the differential image determination. Specifically, if the formation position of the groove 12 deviates, then as... Figure 21 As shown, groove 12 cannot be completely removed in the differential image, and groove 12 may be detected as residue of protective film 11.

[0147] As described above, based on the differential image-based determination, in either the fluorescence mode or the reflected light mode, if the formation position of the groove 12 contained in the reference region 61 is offset from the formation position of the groove 12 in the determination target region 60, a misjudgment may occur.

[0148] In the determination of whether there is residue (process P6), the above-mentioned misjudgment problem can be eliminated by excluding the area with groove 12 formed by laser processing or the area expected to form groove 12 from the judgment object in advance.

[0149] In the area where the groove 12 is formed, the protective film 11 is removed by laser processing, and generally no residue is produced. Therefore, it is not a problem to exclude the area with the groove 12 from the object to be judged. Assuming that even if there is residue of the protective film 11 in the groove 12, the risk of adverse events is extremely small because the workpiece 10 is cut off by the blade cutting performed subsequently. Therefore, it is not a problem to exclude the area with the groove 12 from the object area for residue inspection. Information indicating the area with the groove 12 can also be extracted, for example, from an image of the workpiece 10 obtained after laser processing.

[0150] The area where the groove 12 is expected to form is typically the cutting path. Even if the area where the groove 12 is expected to form is excluded from the judgment object, no problem will arise for the same reason as the area where the groove 12 is expected to form. Information indicating the area where the groove 12 is expected to form can also be extracted, for example, from the pattern information of the workpiece 10.

[0151] [Fifth Implementation Method] In the fifth embodiment of the disclosed technology, when the presence of residue is determined in the determination of whether there is residue on the protective film 11 (step P6) (NG determination), the re-cleaning conditions for removing the residue and the implementation conditions for determining whether there is residue again after re-cleaning are set according to any one of the location where the residue is generated, the area of ​​the residue, and the thickness of the residue.

[0152] If the presence of residue on the protective film 11 is determined in process P6 (NG judgment), the workpiece 10 is re-cleaned to remove the residue. The re-cleaning conditions are set differently from the initial cleaning conditions, depending on the state of residue formation on the protective film 11. Parameters for determining the cleaning conditions include, for example, cleaning time, nozzle operating range, rotational speed of the workpiece, type of cleaning fluid, supply volume of cleaning fluid, and spray pressure of the cleaning fluid.

[0153] The re-cleaning conditions are set, for example, to focus on cleaning the residue-generating areas identified in the residue inspection (process P6). Figures 22A to 22D This is a diagram showing an example of re-cleaning condition settings corresponding to the formation of residue on the protective film 11.

[0154] like Figure 22A As shown, when the residue 11a of the protective film is widely distributed throughout the workpiece 10, the operating range of the nozzle 22 is set such that the tip of the nozzle 22, which sprays the cleaning fluid, travels back and forth between the center and the outer edge of the workpiece 10. This supplies cleaning fluid to the entire workpiece 10, promoting the removal of the residue 11a widely distributed throughout the workpiece 10.

[0155] like Figure 22B As shown, when the residue 11a of the protective film is distributed along the outer edge of the workpiece 10, the operating range of the nozzle 22 is set such that the tip of the nozzle 22 travels back and forth across the outer peripheral region of the workpiece 10. This concentrates the supply of cleaning fluid to the outer peripheral region of the workpiece 10, promoting the removal of the residue 11a distributed along the outer edge of the workpiece 10.

[0156] like Figure 22C As shown, when residue 11a is locally present on the protective film, the nozzle 22 is positioned such that it is fixed at the location where residue 11a is present, and the rotation angle of the workpiece 10 is also positioned. This concentrates the supply of cleaning fluid to the location where residue 11a is present, promoting the removal of the locally present residue 11a.

[0157] like Figure 22D As shown, when the residue 11a of the protective film is distributed in a band along the radial direction of the workpiece 10, the operating range of the nozzle 22 is set such that the tip of the nozzle 22 travels back and forth between the center and the outer edge of the workpiece 10, and the rotation angle of the workpiece 10 is positioned. This concentrates the supply of cleaning fluid to the areas where the residue 11a is present, promoting the removal of the residue 11a that is distributed in a band along the radial direction of the workpiece 10.

[0158] The larger the area of ​​residue 11a, the longer the cleaning time can be, the greater the supply of cleaning fluid, and the higher the spray pressure of the cleaning fluid. The thicker the residue 11a, the longer the cleaning time can be, the greater the supply of cleaning fluid, and the higher the spray pressure of the cleaning fluid.

[0159] Alternatively, during the re-cleaning process, only specific areas can be cleaned before cleaning the entire object 10. This allows the protective film 11 that re-adheres to the object 10 to be dissolved and removed through re-cleaning, thus reducing the risk of repeated re-cleaning.

[0160] After the second cleaning is completed, a second check for residue is performed. In this second residue check, for example, only the areas where residue was identified in the initial check can be considered for inspection. Therefore, compared to the case where the entire workpiece 10 is considered for inspection, the inspection time can be shortened in this second residue check.

[0161] [Sixth Implementation Method] Regarding the residue inspection method according to the sixth embodiment of the disclosed technology, based on the reflected light L1 of the measurement light L1 irradiated onto the electrode pads provided on the workpiece 10, 2B The presence or absence of residue on the protective film 11 is determined by the interference spectrum. That is, in the residue inspection method according to the sixth embodiment, a residue inspection device corresponding to the spectroscopic interference method is used. For example, a residue inspection device corresponding to the spectroscopic interference method is used... Figure 4 The coaxial incident illumination type residue inspection device shown or Figure 5B The light source unit 32 and the light receiving unit 33 shown are symmetrically arranged oblique illumination type residue inspection device.

[0162] In the residue inspection apparatus corresponding to the spectroscopic interferometry method, the residue thickness of the protective film 11 is measured using optical interferometry. When the measuring light L1 from the light source 36 enters the protective film 11, part of it is reflected on the surface of the protective film 11, and the other part is reflected on the surface of the workpiece 10 after passing through the protective film 11. By analyzing the interference spectrum of these reflected lights obtained by the detector 39 through the decision 35, the thickness of the protective film 11 can be measured.

[0163] When the workpiece 10 has a multilayer oxide film covered by a protective film 11, it is difficult to measure the film thickness using spectroscopic interferometry. This is because the interference spectrum of the reflected light from the multilayer oxide film covered by the protective film 11 becomes complex, making it difficult to determine the film thickness by pattern fitting of the interference spectrum. In the residue inspection method according to this embodiment, the object area for determining the presence or absence of residue is limited to the electrode pads. That is, as... Figure 23 As shown, based on the reflected light L reflected from the surface of the protective film 112B1 and the reflected light L reflected from the surface of electrode pad 18 2B2 By analyzing the interference spectrum, the thickness of the protective film 11 on the electrode pad 18 is derived, and the presence or absence of residue of the protective film 11 on the electrode pad 18 is determined based on the result. By limiting the target area for residue inspection to the electrode pad 18, the interference spectrum can be kept from becoming complicated, thus making it easy to determine whether or not there is residue of the protective film 11.

[0164] Figure 24A This is a diagram showing an example of the interference spectrum when the thickness of the protective film 11 on the electrode pad 18 is 0 nm and 50 nm, respectively. Figure 24B This is a diagram showing an example of the interference spectrum when the thickness of the protective film 11 on the electrode pad 18 is 0 nm and 200 nm, respectively. The thicker the protective film 11 on the electrode pad 18, the more waves appear in the interference spectrum.

[0165] Figure 25 The curve is obtained by plotting the sum of the differences (cumulative values ​​in the frequency direction) between the interference spectrum of a certain film thickness and the interference spectrum when the film thickness is zero. In the region where the protective film 11 is thinner, the "sum of differences" changes monotonically with respect to the film thickness. Therefore, by using a threshold to determine the "sum of differences", it is possible to determine whether there is residue in the protective film 11.

[0166] The configuration of the electrode pads 18 in the workpiece 10 can be determined based on the pattern information of the workpiece 10. Interference spectra can also be obtained by irradiating the electrode pads 18, whose formation positions are determined by the pattern information, with measurement light L1.

[0167] In the residue inspection apparatus corresponding to the spectroscopic interference method, a spectrometer or a hyperspectral camera is used as detector 39. When a spectrometer is used as detector 39, the interference spectrum corresponding to the electrode pad 18 can be extracted from the interference spectrum obtained by scanning the entire surface of the workpiece 10 with measurement light L1 through pattern matching. When a hyperspectral camera is used as detector 39, the position of the electrode pad 18 can be determined based on the image acquired by the hyperspectral camera, and the interference spectrum at the determined formation position of the electrode pad 18 can be obtained.

Claims

1. A residue inspection method, wherein the residue inspection method is a residue inspection method for determining whether there is a protective film on a workpiece after processing and cleaning, wherein the workpiece is a workpiece processed by irradiating a surface on which the protective film is formed with a laser. The residue inspection method determines the presence or absence of residue by using a threshold to judge the intensity of reflected light or fluorescence excited by the measuring light illuminating the surface of the workpiece. The threshold is set based on the intensity distribution of the reflected light or the fluorescence obtained for the processed object for which the protective film has not been formed.

2. The residue inspection method according to claim 1, wherein, The workpiece being processed has a first portion with relatively high intensity of the reflected light or fluorescence and a second portion with relatively low intensity for workpieces without the protective film. The values ​​set for the first part and the values ​​set for the second part are different from each other for the threshold.

3. The residue inspection method according to claim 1, wherein, The inspection device used to determine the presence or absence of the residue is used to determine the formation state of the protective film on the workpiece before processing.

4. The residue inspection method according to claim 3, wherein, The inspection device is positioned around the cleaning workbench where the workpiece is cleaned or around the transport path of the workpiece.

5. The residue inspection method according to claim 3, wherein, The abnormality of the inspection device is detected based on the determination result of the formation state of the protective film or the determination result of the presence or absence of the residue.

6. The residue inspection method according to claim 3, wherein, When determining whether the residue is present or absent, or when determining the formation state of the protective film, at least one of the following is different: the part of the object to be determined in the processed object, the irradiation range of the measuring light, and the irradiation time of the measuring light.

7. The residue inspection method according to claim 1, wherein, The presence or absence of residue is determined for a specific area of ​​the object being processed.

8. The residue inspection method according to claim 7, wherein, The portion of the region is at least one of the following: the outer peripheral region of the workpiece, the area where the electrode pads are formed on the workpiece and its surrounding area, the region with unevenness, the region along the radial direction of the workpiece, the region where the residue is easily generated, and the region that is determined to be abnormal in the determination of the formation state of the protective film.

9. The residue inspection method according to claim 1, wherein, The processing of the workpiece is achieved by forming a groove on the workpiece using laser irradiation. In determining whether or not the residue exists, areas where the groove has been formed or areas where the groove is expected to be formed are excluded from the determination object.

10. The residue inspection method according to claim 1, wherein, The processing state of the workpiece is determined based on the image formed by the reflected light obtained in the determination of the presence or absence of the residue.

11. The residue inspection method according to claim 1, wherein, If it is determined that there is residue in the determination of whether or not the residue exists, the re-cleaning conditions for removing the residue are set according to any one of the location where the residue is generated, the area of ​​the residue, and the thickness of the residue.

12. The residue inspection method according to claim 1, wherein, If the presence or absence of residue is determined to be present, the implementation conditions for determining the presence or absence of residue again after the re-washing to remove the residue are set according to any one of the location where the residue is generated, the area of ​​the residue, and the thickness of the residue.

13. A residue inspection method, wherein the residue inspection method is a residue inspection method for determining whether there is a protective film on a workpiece after processing and cleaning, wherein the workpiece is a workpiece processed by irradiating a surface on which the protective film is formed with a laser. The residue inspection method determines the presence or absence of residue based on the interference spectrum of the reflected light from the measurement light irradiated onto the electrode pads of the workpiece.

14. A residue inspection device, wherein the residue inspection device is used to determine whether there is residue with a protective film after processing and cleaning of a workpiece, wherein the workpiece is processed by irradiating a surface on which the protective film is formed with a laser. The residue inspection device determines the presence or absence of residue by using a threshold to judge the intensity of reflected light or fluorescence excited by the measuring light illuminating the surface of the workpiece. The threshold is set based on the intensity distribution of the reflected light or the fluorescence obtained for the processed object for which the protective film has not been formed.

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