Laser machining device and laser machining method

Abstract

This laser machining device comprises: a protective film inspection mechanism for determining the application state of a protective film applied to a workpiece; and a positioning mechanism for placing and positioning the workpiece on a machining table during laser machining. After the positioning mechanism positions the workpiece on the machining table, the protective film inspection mechanism determines the application state of the protective film. This laser machining method comprises: a positioning step for placing and positioning a workpiece yet to be laser-machined on a machining table; and a determination step for measuring, after the positioning step, the application state of a protective film applied to the workpiece positioned on the machining table and determining the application state of the protective film.

Description

Laser processing device and laser processing method

[0001] This application claims priority to Japanese Patent Application No. 2024-053604, filed on March 28, 2024, the contents of which are incorporated herein by reference.

[0002] Laser ablation processing is used in semiconductor manufacturing, which can cause melted debris to adhere to the device layer. Therefore, a protective film made of a water-soluble resin is typically formed on the wafer surface before laser ablation processing. This protective film protects the device layer from debris generated during laser ablation processing. After laser ablation processing, the debris can be washed away along with the protective film.

[0003] The protective film is applied by methods such as spin coating, but coating defects occasionally occur. Specifically, there are cases where areas of the wafer surface are left uncoated, or the film thickness is either too thick or too thin compared to the specified thickness. If areas are left uncoated or the film thickness is too thin, the device layer in that area may be affected by debris. Conversely, if the film thickness is too thick, the laser light may be blocked by the protective film, which may cause defects in the laser ablation process. Therefore, from the perspective of improving yield, it is necessary to form a protective film with an appropriate thickness, so the film thickness must be inspected in advance.

[0004] As an example of a method for inspecting film thickness, for example, Patent Document 1 discloses a protective film thickness measurement method. This thickness measurement method includes a pre-protective film formation measurement step in which light is irradiated onto the surface of a substrate without a protective film formed thereon and a first reflection intensity of light reflected from the surface is measured; a protective film formation step in which a protective film containing a light-absorbing material is formed on the surface; a post-protective film formation measurement step in which excitation light having a wavelength at which the light-absorbing material fluoresces is irradiated onto the protective film and a second reflection intensity including the fluorescence of the protective film and the light reflected from the surface is measured using a measurement unit; a protective film fluorescence intensity calculation step in which the first reflection intensity measured in the pre-protective film formation measurement step is subtracted from the second reflection intensity measured in the post-protective film formation measurement step to remove the reflection intensity due to the pattern formed on the surface, thereby calculating the fluorescent intensity of the protective film; and a protective film thickness recognition step in which the thickness of the protective film is recognized based on previously acquired correlation data between the fluorescent intensity of the protective film and the thickness of the protective film and the calculated fluorescent intensity of the protective film. It is described that this thickness measurement method enables accurate measurement of the thickness of a protective film formed on the surface of a substrate having a pattern on its surface.

[0005] Japanese Patent Application Publication No. 2022-178427

[0006] In the thickness measurement method described in Patent Document 1, both the pre-formation measurement step and the post-formation measurement step of the protective film are performed on a coating table on which the protective film is formed. Because the coating table is not intended for high-precision alignment, it is difficult to precisely align the position of the pattern before and after the protective film is formed.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a laser processing apparatus and a laser processing method that can perform processing based on a more accurate determination of coating defects.

[0008] The present invention employs the following means to solve the above problems and achieve the above objects. (1) A laser processing apparatus according to one aspect of the present invention is a laser processing apparatus including a protective film inspection mechanism that determines the coating state of a protective film applied to a workpiece, and a positioning mechanism that places the workpiece on a processing table and positions it during laser processing, wherein after the positioning mechanism positions the workpiece on the processing table, the protective film inspection mechanism determines the coating state of the protective film. According to the laser processing apparatus described in (1) above, high-precision position information regarding each position on the workpiece positioned on the processing table by the positioning mechanism can be combined with measurement results of the coating state of the protective film applied at each position to perform a pass / fail determination.

[0009] (2) The laser processing apparatus described in (1) above may be configured as follows: the protective film inspection mechanism includes an irradiation unit that irradiates the protective film with excitation light, a detection unit that detects fluorescence emitted by the protective film, and a control unit that determines the coating state by acquiring a fluorescence intensity distribution based on the detection result of the detection unit, and the control unit has threshold distribution data in which a threshold is set for each position on the workpiece based on a first pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is not coated, and the control unit determines the coating state by comparing the threshold distribution data with post-protective film application fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent is formed. In the laser processing apparatus described in (2) above, the coating state can be determined based on threshold distribution data in which a threshold is set individually for each position on the workpiece. Specifically, the determination can be made after removing the influence of fluorescence from the device layer at each position on the workpiece. Therefore, more precise determination can be made than when the threshold value on the workpiece is constant at each position. When processing multiple workpieces having the same pattern, threshold distribution data may be obtained only for the first workpiece, and the same threshold distribution data may be used for the subsequent workpieces.

[0010] (3) The laser processing apparatus described in (1) above may be configured as follows: The protective film inspection mechanism includes an irradiation unit that irradiates the protective film with excitation light, a detection unit that detects fluorescence emitted by the protective film, and a control unit that determines the coating state by acquiring a fluorescence intensity distribution based on the detection results of the detection unit. The control unit has threshold distribution data in which a threshold is set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is coated with the protective film. The control unit determines the coating state by comparing the threshold distribution data with post-protective film application fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent is formed. In the laser processing apparatus described in (3) above, the coating state can be determined based on threshold distribution data individually set corresponding to each position on the workpiece. Specifically, the influence of fluorescence emitted by the light absorbent in the protective film and reflected by the device layer can be eliminated. Therefore, more precise determination can be made than when the threshold value on the workpiece is constant at each position. When processing multiple workpieces having the same pattern, threshold distribution data may be obtained only for the first workpiece, and the same threshold distribution data may be used for the subsequent workpieces.

[0011] (4) The laser processing apparatus described in (1) above may be configured as follows: the protective film inspection mechanism includes an irradiation unit that irradiates the protective film with excitation light, a detection unit that detects fluorescence emitted by the protective film, and a control unit that determines the coating state by obtaining a distribution of fluorescence intensity based on the detection result of the detection unit, wherein the control unit has: first pre-measured data that is a lower limit threshold set for each position on the workpiece based on a first pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is not coated; and second pre-measured data that is an upper limit threshold set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is coated; and calculates threshold distribution data that is set between the first pre-measured data and the second pre-measured data, The workpiece is positioned on the processing table with the protective film containing the light-absorbing agent and is irradiated with the excitation light to obtain post-protective film fluorescence intensity data, which is then compared with the threshold distribution data to determine the coating condition. In the laser processing device described in (4) above, the coating condition can be determined based on threshold distribution data individually set for each position on the workpiece. Specifically, it is possible to eliminate both the influence of fluorescence from the device layer at each position on the workpiece and the influence of fluorescence emitted by the light-absorbing agent in the protective film and reflected by the device layer. Therefore, more precise determination can be made than when the threshold value on the workpiece is constant at each position. Note that when processing multiple workpieces with the same pattern, threshold distribution data may be obtained only for the first workpiece, and the same threshold distribution data may be used for subsequent workpieces.

[0012] (5) The laser processing apparatus described in (1) above may be configured as follows: the workpiece has a plurality of identical reticle shots each forming the same pattern; the positioning mechanism acquires position information for each of the identical reticle shots; and the protective film inspection mechanism determines the coating state by comparing the coating state at each position of the identical reticle shots linked to each other by the position information. In the laser processing apparatus described in (5) above, the same reticle shots each have the same pattern, so chips are formed with the same pattern. Therefore, by comparing the measurement results of the protective film at positions of the same reticle shots, a precise determination can be made that eliminates light scattering due to unevenness in the pattern on the workpiece.

[0013] (6) The laser processing apparatus described in (1) above may be configured as follows: the workpiece has a reference position chip arranged at its center and inspection position chips arranged around the reference position chip; the positioning mechanism acquires position information for each of the reference position chip and the inspection position chip; and the protective film inspection mechanism sets the application state of the protective film at the position of the reference position chip as an acceptance criterion, and judges the application state of the protective film at the position of the inspection position chip by comparing it with the acceptance criterion. In the laser processing apparatus described in (6) above, the position of the reference position chip is at the center of the workpiece, and at this position, defective application of the protective film is less likely to occur. Therefore, the application state of the inspection position chip can be judged using the protective film formed on this reference position chip as the acceptance criterion.

[0014] (7) The laser processing apparatus described in (1) above may be configured as follows: The laser processing apparatus may further include a coating mechanism that applies the protective film to the workpiece by spin coating, the workpiece having a plurality of inspection target position chips, the positioning mechanism acquiring position information for each of the inspection target position chips, and the protective film inspection mechanism comparing the coating state at each of the inspection target position chips having position information on positions concentric with the center position of the workpiece to determine the protective film coating state. In the laser processing apparatus described in (7) above, the thickness of the protective film formed by spin coating is the same at each position on a concentric circle from the center position of the workpiece. Therefore, if the protective film is applied properly, the thickness of the protective film will also be the same at each position on each of the inspection target position chips on this concentric circle. Therefore, the protective film coating state can be determined by comparing the protective film thickness at each position on the concentric circle and determining whether there are any locations where the thickness significantly differs.

[0015] (8) The laser processing apparatus described in any one of (5) to (7) above may be configured as follows: Before comparing the coating states, the protective film inspection mechanism aligns the relative positions of the images to be compared based on position information acquired from the positioning mechanism. In the laser processing apparatus described in (8) above, since the relative positions of the images to be compared are aligned, pre-measurement before applying a protective film is not required. Note that the position information associated with an image acquired for a workpiece can also be used when determining the protective film coating state of another workpiece having the same pattern. Therefore, the comparison target may be acquired from the same individual, or from a different individual having the same pattern. Here, if the comparison target is acquired from the same individual, pre-measurement before applying a protective film is completely unnecessary.

[0016] (9) The laser processing apparatus according to any one of (1) to (7) above may be configured as follows: the protective film inspection mechanism excludes from the judgment of the coating state portions of the workpiece that are not related to the presence or absence of processing defects after laser processing. In the case of the laser processing apparatus according to (9) above, since highly accurate position information obtained by the positioning mechanism can be used, it is possible to prevent incorrect judgment of defects in positions that do not lead to product defects, such as portions away from the processing line (street) or chipped chip portions on the outer periphery, thereby improving throughput.

[0017] (10) A laser processing method according to one aspect of the present invention includes a positioning step of placing a workpiece before laser processing on a processing table and positioning it, and a judging step of measuring, after the positioning step, the coating state of a protective film applied to the workpiece positioned on the processing table and judging the coating state of the protective film. According to the laser processing method described in (10) above, high-precision position information regarding each position on the workpiece positioned on the processing table in the positioning step can be combined with measurement results of the coating state of the protective film applied to each position in the judging step to perform a pass / fail judgment.

[0018] (11) The laser processing method described in (10) above may be configured as follows: the determination step may include: a threshold distribution creation step of creating threshold distribution data, in which a threshold is set for each position on the workpiece, based on a first pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table without the protective film; and a comparison step of determining the coating state by comparing the threshold distribution data with post-protective film fluorescence intensity data obtained by irradiating excitation light onto the workpiece positioned on the processing table with the protective film containing a light absorbent. In the laser processing method described in (11) above, the coating state can be determined based on threshold distribution data individually set corresponding to each position on the workpiece. Specifically, the influence of fluorescence from the device layer at each position on the workpiece can be eliminated. Therefore, more precise determination can be performed than when the threshold on the workpiece is constant at each position. Note that when processing multiple workpieces with the same pattern, threshold distribution data may be obtained only for the first workpiece, and the same threshold distribution data may be used for subsequent workpieces.

[0019] (12) The laser processing method described in (10) above may be configured as follows: the determination step may include: a threshold distribution creation step of creating threshold distribution data in which a threshold is set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state in which the protective film is coated; and a comparison step of determining the coating state by comparing the threshold distribution data with post-protective film fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state in which the protective film containing a light-absorbing agent is formed. In the laser processing method described in (12) above, the coating state can be determined based on threshold distribution data individually set corresponding to each position on the workpiece. Specifically, the influence of fluorescence emitted by the light-absorbing agent in the protective film and reflected by the device layer can be eliminated. Therefore, a more precise determination can be made compared to when the threshold on the workpiece is constant at each position. When processing a plurality of workpieces having the same pattern, threshold distribution data may be acquired only for the first workpiece, and the same threshold distribution data may be used for subsequent workpieces.

[0020] (13) The laser processing method described in (10) above may be configured as follows: the determination step may include a threshold distribution creation step of calculating threshold distribution data formed between first pre-measurement data, which is a lower threshold set for each position on the workpiece, based on first pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film is not applied, and second pre-measurement data, which is an upper threshold set for each position on the workpiece, based on second pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film is applied, and a comparison step of comparing post-protective film application fluorescence intensity data, which is obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent is formed, with the threshold distribution data to determine the coating state. In the laser processing method described in (13) above, the coating state can be determined based on threshold distribution data individually set corresponding to each position on the workpiece. Specifically, it is possible to eliminate both the influence of the fluorescence from the device layer at each position on the workpiece and the influence of the fluorescence emitted by the light absorbing agent in the protective film and reflected by the device layer. Therefore, more precise determination can be performed than when the threshold value on the workpiece is constant at each position. Note that when processing multiple workpieces with the same pattern, threshold distribution data may be obtained only for the first workpiece, and the same threshold distribution data may be used for subsequent workpieces.

[0021] (14) The laser processing method described in (10) above may be configured as follows: the workpiece has a plurality of identical reticle shots that form the same pattern; the positioning step acquires position information for each of the identical reticle shots; and the determination step compares the coating states at the positions of the identical reticle shots linked to each other by the position information to determine the coating state of the protective film. In the laser processing method described in (14) above, the same reticle shots each have the same pattern because chips are formed with the same pattern. Therefore, by comparing the measurement results of the protective film at positions of the same reticle shots, it is possible to accurately determine the protective film while excluding light scattering due to unevenness in the pattern on the workpiece.

[0022] (15) The laser processing method described in (10) above may be configured as follows: the workpiece has a reference position chip arranged at its center and an inspection position chip arranged around the reference position chip; in the positioning step, position information for each of the reference position chip and the inspection position chip is acquired; and in the judging step, the application state of the protective film at the position of the reference position chip is set as an acceptance criterion, and the application state of the protective film at the position of the inspection position chip is judged by comparing it with the acceptance criterion. In the laser processing method described in (15) above, the position of the reference position chip is at the center of the workpiece, and at this position, defective application of the protective film is unlikely to occur. Therefore, the application state of the inspection position chip can be judged using the protective film formed on this reference position chip as the acceptance criterion.

[0023] (16) The laser processing method described in (10) above may be configured as follows: The method further includes a coating step of applying the protective film to the workpiece having a plurality of inspection target position chips by spin coating before the positioning step; The positioning step acquires position information for each of the inspection target position chips on the workpiece; and the judging step compares the coating state at each of the inspection target position chips located on concentric circles from the center of the workpiece to judge the coating state. In the laser processing method described in (16) above, the thickness of the protective film formed by spin coating is the same at each of the positions on the concentric circles from the center of the workpiece. Therefore, if the protective film is applied normally, the thickness of the protective film will also be the same at each of the positions on the concentric circles. Therefore, the coating state of the protective film can be judged by comparing the thicknesses of the protective film at each of the concentric circles to see if the thickness partially deviates from the standard.

[0024] (17) In the laser processing method described in (14) to (16) above, the determination step may include: an imaging step of acquiring images of each inspection position on the workpiece; and an image adjustment step of matching the relative positions of the images to be compared based on the position information acquired in the positioning step before comparing the coating states. In the laser processing method described in (17) above, since the relative positions of the images to be compared are matched, pre-measurement before applying a protective film is not required. Note that the position information associated with an image acquired for a workpiece is also effective when determining the protective film coating state of another workpiece on which the same pattern is formed. Therefore, the comparison object may be acquired from the same individual object or from a different individual object. Here, if the comparison object is acquired from the same individual object, pre-measurement before applying a protective film is not required.

[0025] (18) In the laser processing method described in (10) to (16) above, the following may be performed: the judgment step includes an exclusion step of excluding, from the judgment of the coating state, portions of the workpiece that are not involved in the presence or absence of processing defects after laser processing. In the laser processing method described in (18) above, the exclusion step can utilize highly accurate position information obtained in the positioning step, so that it is possible to prevent unnecessary defect judgments at positions that do not lead to product defects, such as portions away from the processing line (street) or chipped chip portions on the outer periphery, thereby improving throughput.

[0026] According to the laser processing apparatus and the laser processing method according to the above aspects of the present invention, processing can be performed based on a more accurate coating defect judgment.

[0027] 1 is a perspective view showing a schematic configuration of a protective film inspection device provided in a laser processing apparatus according to a first embodiment of the present invention; 2 is a plan view showing the relative positional relationship between a spinner table on the loader side and a processing table on the processing side provided in the laser processing apparatus; 3 is a diagram explaining how threshold data used in protective film inspection by the protective film inspection mechanism of the laser processing apparatus is determined, where the horizontal axis indicates the position along the wafer surface and the vertical axis indicates the fluorescence intensity at each position; 4 is a diagram explaining a protective film inspection method by the protective film inspection mechanism of a laser processing apparatus according to a second embodiment of the present invention; 5 (A) shows a form in which film thicknesses are compared between reticle shots, 6 (B) shows a form in which the film thickness of a reference chip located near the wafer center is compared with the film thickness of chips at inspection positions around it, and 7 (C) shows a form in which film thicknesses are compared between chips at inspection positions equidistant from the wafer center; 8 is a diagram explaining a form in which film thicknesses are compared at the same pattern position in the second embodiment, where 9 (A) shows a case in which comparison is made using images captured at the same inspection position, and 10 (B) shows a case in which the same inspection position is obtained using position information and then compared. 10A and 10B are diagrams illustrating a protective film inspection method using a protective film inspection mechanism of a laser processing apparatus according to a third embodiment of the present invention, where (A) shows a case where film thickness determination at positions away from the wafer streets is excluded, and (B) shows a form where film thickness determination at positions of chipped chips on the outer peripheral edge of the wafer is excluded.

[0033] FIG. 10B is a flowchart illustrating each step of protective film inspection in the third embodiment.

[0034] FIG. 10C is a diagram illustrating a protective film inspection method using a protective film inspection mechanism of a laser processing apparatus according to a fourth embodiment of the present invention, where the diagram illustrates a form where inspection is limited to only the wafer streets and their peripheral portions.

[0035] FIG. 10D is a flowchart illustrating each step of protective film inspection in the fourth embodiment.

[0036] FIG. 10E is a diagram illustrating a modification of the fourth embodiment, where the diagram illustrates a plan view illustrating a form where film thickness inspection is performed by linearly scanning along the wafer streets.

[0037] FIG. 10F is a diagram illustrating a further modification of the fourth embodiment, where the diagram illustrates a partially enlarged view of a portion on the wafer.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing apparatus and a laser processing method according to embodiments of the present invention and modifications thereof will be described below with reference to the drawings.

[0029] First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In this description, the overall configuration of a laser processing apparatus will first be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing the schematic configuration of a protective film inspection device provided in the laser processing apparatus according to this embodiment. FIG. 2 is a plan view showing the relative positional relationship between a loader-side spinner table and a processing-side processing table provided in the laser processing apparatus. As shown in FIGS. 1 and 2, the laser processing apparatus according to this embodiment includes a protective film forming apparatus 100 that forms a protective film p on a wafer W, which is a workpiece, by spin coating; a processing apparatus 200 that performs laser ablation processing (hereinafter sometimes referred to as "laser processing" or simply "processing") on the wafer W after the protective film p has been formed by the protective film forming apparatus 100; a protective film inspection apparatus 300 that inspects the protective film p on a processing table 32 of the processing apparatus 200 before laser processing; and a control unit 400 that controls the protective film forming apparatus 100, the processing apparatus 200, and the protective film inspection apparatus 300.

[0030] The protective film forming apparatus 100 includes a loader-side base 10, spinner tables 11 and 12, a cleaning mechanism (not shown), and a protective film coating mechanism (not shown). The loader-side base 10 is a pedestal installed in a fixed position. The spinner table 11 is a circular table supported on the loader-side base 10 and is rotatable about a vertical axis passing through its center. The spinner table 11 can suction-fix a wafer W placed on its upper surface. The spinner table 12 is a circular table supported on the loader-side base 10 at a position adjacent to the spinner table 11 and is rotatable about a vertical axis passing through its center. The spinner table 12 can suction-fix a wafer W placed on its upper surface.

[0031] One protective film coating mechanism is provided for each of the spinner tables 11 and 12. The protective film coating mechanism provided on the spinner table 11 side dispenses a chemical solution for the protective film p (or a protective film) coaxially on the spinner table 11. Therefore, after the wafer W is coaxially suction-fixed on the spinner table 11, the chemical solution coated on the wafer W spreads radially from the center of the wafer W to form a protective film p that covers the entire surface of the wafer W. Similarly, the protective film coating mechanism provided on the spinner table 12 side dispenses a chemical solution for the protective film p (or a protective film) coaxially on the spinner table 12. Therefore, after the wafer W is coaxially suction-fixed on the spinner table 12, the chemical solution coated on the wafer W spreads radially from the center of the wafer W to form a protective film p that covers the entire surface of the wafer W. Although the protective film p in this embodiment is formed by spin coating, other methods may be used. One cleaning mechanism is provided for each of the spinner tables 11 and 12, and washes away the protective film p on the wafer W if the inspection result of the protective film p is negative. Specifically, the cleaning mechanism provided on the spinner table 11 side washes away the protective film p by discharging a cleaning liquid onto the wafer W on the spinner table 11 and discharging the waste liquid after cleaning. After cleaning, a new protective film p is formed on the upper surface of the wafer W by the protective film application mechanism. Similarly, the cleaning mechanism provided on the spinner table 12 side washes away the protective film p by discharging a cleaning liquid onto the wafer W on the spinner table 12 and discharging the waste liquid after cleaning. After cleaning, a new protective film p is formed on the upper surface of the wafer W by the protective film application mechanism.

[0032] The processing apparatus 200 includes a laser irradiation unit (not shown), a processing-side base 30, a positioning mechanism 31, and a processing table 32. The laser irradiation unit is disposed on the processing-side base 30 and includes a light source and an optical system. The laser irradiation unit irradiates a wafer W fixed by suction on the processing table 32 with laser light to perform processing. The processing-side base 30 is a pedestal installed in a fixed position adjacent to the loader-side base 10. While FIGS. 1 and 2 illustrate the processing-side base 30 and the loader-side base 10 as separate units for the sake of explanation, they may be integrated. The positioning mechanism 31 includes a Y-axis positioning unit 31a, an X-axis positioning unit 31b, a θ-axis angle adjustment mechanism 31c, and the processing table 32.

[0033] The Y-axis direction positioning unit 31a includes a Y-axis direction moving base 31a0, a pair of guide rails 31a1 that support the Y-axis direction moving base 31a0 on the processing-side base 30, a ball screw 31a2 that is arranged on the processing-side base 30 parallel to the guide rails 31a1 and rotatably supported about its central axis, and a servo motor 31a3 that rotates the ball screw 31a2. The ball screw 31a2 is threadedly engaged with a female threaded hole (not shown) formed on the underside of the Y-axis direction moving base 31a0. According to the Y-axis direction positioning unit 31a, the ball screw 31a2 rotates when the servo motor 31a3 is rotated. As a result, the Y-axis direction moving base 31a0, which has the female threaded hole that is threadedly engaged with the ball screw 31a2, moves horizontally along the Y-axis direction. At this time, the control unit 400 appropriately adjusts the rotation amount of the servo motor 31a3 to precisely adjust the movement amount along the Y-axis direction of the Y-axis moving base 31a0, i.e., the position of the processing table 32 along the Y-axis direction.

[0034] The X-axis direction positioning unit 31b includes an X-axis moving base 31b0, a pair of guide rails 31b1 that support the X-axis direction moving base 31b0 on the Y-axis direction moving base 31a0, and a linear motor 31b3 that is arranged on the Y-axis direction moving base 31a0 so as to be parallel to the guide rails 31b1 and that moves the X-axis direction moving base 31b0 along the X-axis. The X-axis direction positioning unit 31b moves the X-axis direction moving base 31b0, which is supported by the guide rails 31b1 so as to be movably in the X-axis direction, along the X-axis direction by the linear motor 31b3, thereby performing precise adjustment of the amount of movement of the X-axis direction moving base 31b0, i.e., the position of the machining table 32 along the X-axis direction.

[0035] The θ-axis angle adjustment mechanism 31c includes a shaft (not shown) that is erected on the X-axis moving base 31b0 and supports the processing table 32, and a servo motor (not shown) that rotates the shaft about a vertical axis (about the Z-axis). The θ-axis angle adjustment mechanism 31c allows the control unit 400 to rotate the servo motor about the Z-axis, thereby precisely adjusting the rotation angle of the processing table 32. The processing table 32 is a circular table that is rotatable about a vertical axis passing through its center. The processing table 32 can suction-fix a wafer W placed on its upper surface. The processing table 32 can be positioned with high precision in the X-axis direction, Y-axis direction, and θ-axis angle by the positioning mechanism 31 described above.

[0036] The protective film inspection apparatus 300 includes an irradiation unit 50, a detection unit 60, and the processing table 32. In the laser processing apparatus of this embodiment, both laser processing of the wafer W and protective film inspection of the wafer W are performed on the processing table 32. Therefore, the processing table 32 is a component shared by the processing apparatus 200 and the protective film inspection apparatus 300.

[0037] The irradiation unit 50 includes a light source 51, a lens 52, and a filter 53. The light source 51 emits light such as excitation light, which is adjusted to be parallel light by the lens 52 and then irradiated onto the processing table 32 via the filter 53. During protective film inspection, the wafer W having the protective film p formed thereon is attracted and placed on the processing table 32, and the light emitted from the irradiation unit 50 is irradiated onto a desired area on the wafer W.

[0038] The detection unit 60 includes a detector 61, a lens 62, and a filter 63. This detection unit 60 can capture an image of the area on the wafer W irradiated with light from the irradiation unit 50. When the light irradiated from the irradiation unit 50 is ultraviolet light (an example of excitation light), the light absorbent contained in the protective film emits fluorescence. The intensity of this fluorescence (hereinafter referred to as "fluorescence intensity") is determined mainly by the illumination intensity of the ultraviolet light, the irradiation time of the ultraviolet light, and the film thickness of the protective film p. In other words, the thicker the film thickness of the protective film p, the greater the amount of light absorbent, and therefore the higher the fluorescence intensity. Therefore, this relationship can be utilized to measure the film thickness of the protective film p.

[0039] Although this embodiment illustrates an example in which an area sensor camera is used as the detection unit 60, other devices such as a line sensor camera, a photomultiplier tube, or a spectroscope can also be used. The area sensor camera is a camera having a sensor with pixels arranged two-dimensionally. In this case, a coaxial epi-illumination or ring illumination can be used as the irradiation unit 50. The line sensor camera is a camera having a sensor with pixels arranged one-dimensionally. The wafer W is moved linearly in one direction to capture the entire surface of the protective film p. In this case, a bar illumination is preferably used as the irradiation unit 50. The photomultiplier tube is a light detection unit that can amplify and capture weak light. Unlike the two cameras described above, the photomultiplier tube measures only one spot. In this case, a spot illumination is preferably used as the irradiation unit 50. The spectroscope is a detection unit that can measure the intensity (spectrum) for each wavelength. Like the photomultiplier tube, the spectroscope also measures only one spot. In this case, a spot illumination is preferably used as the irradiation unit 50.

[0040] The irradiation unit 50 and the detection unit 60 described above are controlled by the control unit 400. Therefore, by the control unit 400 individually and simultaneously controlling the Y-axis direction positioning unit 31 a, the X-axis direction positioning unit 31 b, and the θ-axis angle adjustment mechanism 31 c, it is possible to perform scanning by the detection unit 60 on the protective film p in any of a spiral, concentric, or linear manner (one-way scanning or reciprocating scanning).

[0041] The wafer W, which is a workpiece processed by the laser processing apparatus having the above-described configuration, has a substrate made of a semiconductor material and having a circular shape in a plan view, and a device layer formed on the upper surface of the substrate. A protective film p is formed on the upper surface of the device layer of the wafer W on the spinner table 11 or 12 by the protective film forming apparatus 100 to protect the device layer from debris generated during laser processing performed after the protective film inspection. The protective film p is a water-soluble resin film that is washed away along with debris after processing. The protective film p is inspected on the processing table 32 of the protective film inspection apparatus 300 for its coating condition, such as whether or not there is any incomplete coating or an abnormal film thickness. That is, if there is any incomplete coating or if the protective film p is too thin, the device layer in that area may be affected by debris, and therefore a "protective film abnormality" is determined. Conversely, if the film thickness is too thick, the protective film p may obstruct the laser light during processing, resulting in processing defects, and therefore a "protective film abnormality" is also determined in this case. If it is determined that there is an abnormality in the protective film, the wafer W is not subjected to processing, but is temporarily returned to the spinner table 11 or 12, where the protective film p is washed off and a new protective film p is applied. On the other hand, if the protective film inspection device 300 determines that there is no abnormality in the protective film, the wafer W is subjected to laser processing by the protective film forming device 100 while it is positioned on the processing table 32.

[0042] The laser processing method using the laser processing apparatus having the above-described configuration will be described below, focusing mainly on a positioning step in which a wafer W before laser processing is placed on the processing table 32 and positioned, and a judging step in which, after this positioning step, the coating state of the protective film p applied to the wafer W positioned on the processing table 32 is measured to judge whether the coating state of the protective film p is good or bad. Note that the following description will exemplify a case in which ultraviolet light is irradiated onto the protective film p from the irradiation unit 50 and the fluorescence is received by the detection unit 60, thereby obtaining the fluorescence intensity. However, the coating state of the protective film p of the present invention may be judged by an ultraviolet absorption method instead of the fluorescence method.

[0043] As described above, the coating table is not designed for high-precision alignment, and therefore, precise alignment between the position of the pattern before and after the protective film is formed is not possible. Therefore, in this embodiment, the above-mentioned evaluation process is performed using the positioning mechanism 31 of the processing apparatus 200, which can obtain high-precision positioning and position information, rather than the spinner tables 11 and 12. Specifically, when determining the quality of the protective film p in the evaluation process, a threshold value is individually set for each position, as shown in FIG. 3 , rather than using a uniform threshold value for the entire surface of the protective film p as in the conventional method. That is, on the wafer W before the protective film p is formed, a pattern of protrusions and recesses is formed in the device layer. Therefore, when ultraviolet light is irradiated from the irradiation unit 50, for example, scattered light is generated by the protrusions and recesses, and the pattern itself also emits fluorescence. Since the scattered light and fluorescence from the device layer also enter the detection unit 60, in this embodiment, the influence of the scattered light and fluorescence from the device layer is eliminated in order to accurately detect coating defects and incomplete coating of the protective film p.

[0044] For example, at position A on the left side of the page in Figure 3, the reflectance of the device layer is high and the device layer emits fluorescence when exposed to ultraviolet light. Therefore, the threshold value a at position A is set higher than those at other positions B, C, and D. Next, at position B, the reflectance of the device layer is low, but the device layer emits fluorescence when exposed to ultraviolet light. Therefore, the threshold value b at position B is set lower than that at position A and higher than that at positions C and D. Next, at position C, the device layer does not emit fluorescence when exposed to ultraviolet light, but the reflectance of the device layer is high. Therefore, the threshold value c at position C is set lower than that at positions A and B and higher than that at position D. Finally, at position D, the device layer does not emit fluorescence when exposed to ultraviolet light and the reflectance of the device layer is low. Therefore, the threshold value d at position D is set lower than that at all of the other positions A, B, and C.

[0045] The thresholds a, b, c, and d are set more specifically in a three-step process: preliminary measurement 1, preliminary measurement 2, and threshold determination, as described below. First, in preliminary measurement 1, a wafer W without a protective film p is fixed and positioned on the processing table 32. Then, while the wafer W is positioned in this state, ultraviolet light UV is irradiated onto the wafer W from the irradiation unit 50, and fluorescence (first preliminary measurement fluorescence intensity) emitted by the device layer on the wafer W is received by the detection unit 60. As a result of receiving the light, there is a difference between the presence and absence of fluorescence at positions A, B, C, and D, so the fluorescence intensity received by the detection unit 60 is a1 at position A, b1 at position B, c1 at position C, and d1 at position D. Here, since "fluorescence is present" at both positions A and B, the fluorescence intensities at those positions are a1 and b1, whereas "no fluorescence" is present at positions C and D, so the fluorescence intensities at those positions are c1 and d1, which are close to zero. The fluorescence intensity of the fluorescence emitted from each position on the device layer obtained in this manner is stored in the control unit 400 as first pre-measurement data, which is a lower threshold value, together with coordinate information on the surface of the wafer W (X-axis position and Y-axis position, or radial position and circumferential angle).

[0046] The subsequent preliminary measurement 2 is performed after the protective film is formed on the wafer W, and its details will be described later. That is, after the preliminary measurement 1, the control unit 400 moves the wafer W from the processing table 32 to the spinner table 11 or 12. The protective film forming device 100 then spin-coats the wafer W on the spinner table 11 or 12 to form a protective film p. Since this wafer W is a reference sample for determining the threshold distribution, a wafer with a properly coated protective film p is used. After the protective film p is formed, the wafer W is again moved onto the processing table 32 and positioned and fixed thereon. At this time, the control unit 400 stores the pattern of the device layer on the wafer W together with coordinate information, and the positioning mechanism 31 can reproduce the positioning with high precision based on this coordinate information. Therefore, although the wafer W is temporarily removed from the processing table 32 after the preliminary measurement 1, the coordinate information before removal can be used as is.

[0047] Next, the pre-measurement 2 is performed. In this pre-measurement 2, the fluorescence intensity after application of the protective film (second pre-measurement fluorescence intensity) is measured at each position along the surface of the protective film p using the same measurement method as in the pre-measurement 1. The fluorescence measured at this time will now be described with reference to FIG. 3. First, when ultraviolet light UV is irradiated onto the light absorbent ab, the light absorbent ab emits fluorescence isotropically in a 360° direction. This fluorescence follows one of three paths: (i) light that directly reaches the detector 61, (ii) light that is reflected by the device layer and then reaches the detector 61, or (iii) light that is emitted in a direction that does not reach the detector 61. Of these, there is "(ii) light that is reflected by the device layer and then reaches the detector 61." Therefore, the level of the fluorescence intensity received by the detector 61 depends on the difference in reflectivity of the device layer. Furthermore, the detector 61 also receives the fluorescence from the device layer measured in the pre-measurement 1. In summary, the fluorescence received by the detector 61 consists of three components: "(i) light that directly reaches the detector 61," "(ii) light that reaches the detector 61 after being reflected by the device layer," and fluorescence from the device layer. The fluorescence intensity, which is the sum of these three components, is measured as the second pre-measurement data, which is the upper threshold, and is illustrated by the thick solid line in FIG. 3. That is, in this example, the fluorescence intensity after the protective film is formed is a2 at position A, b2 at position B, c2 at position C, and d2 at position D. The component of the fluorescence intensity due to the device layer is the portion indicated by P, and the component of the fluorescence intensity of the protective film p, which includes the influence of the reflectance of the device layer, is the portion indicated by Q.

[0048] Next, the threshold value is determined. In determining this threshold value, the fluorescence from the device layer is removed based on the first preliminary measurement data obtained in the preliminary measurement 1, and the influence of fluorescence reflection by the device layer is removed based on the second preliminary measurement data obtained in the preliminary measurement 2. Specifically, as shown in FIG. 3 , the control unit 400 sets the threshold values ​​for each of positions A, B, C, and D so that the threshold values ​​are between the first preliminary measurement data obtained in the preliminary measurement 1 and the second preliminary measurement data obtained in the preliminary measurement 2. For example, at position A, threshold value a is calculated and set so that the threshold value is between (e.g., the median) the fluorescence intensity a1 from preliminary measurement 1 and the fluorescence intensity a2 from preliminary measurement 2. At position B, threshold value b is calculated and set so that the threshold value is between (e.g., the median) the fluorescence intensity b1 from preliminary measurement 1 and the fluorescence intensity b2 from preliminary measurement 2. At position C, threshold value c is calculated and set so that the threshold value is between (e.g., the median) the fluorescence intensity c1 from preliminary measurement 1 and the fluorescence intensity c2 from preliminary measurement 2. At position D, threshold value d is calculated and set to be between (for example, the median value) the fluorescence intensity d1 from preliminary measurement 1 and the fluorescence intensity d2 from preliminary measurement 2. In this way, threshold distribution data having appropriate threshold values ​​for each of positions A, B, C, and D can be obtained.

[0049] Following the threshold distribution creation process described above, a comparison process is performed. In this comparison process, excitation light is irradiated onto a wafer W positioned on the processing table 32 with a protective film p containing light absorbents ab, and post-protective film fluorescence intensity data is acquired. This post-protective film fluorescence intensity data is then compared with the threshold distribution data to determine the state of the protective film p. If uniform threshold values ​​were used for each of positions A, B, C, and D, erroneous determinations could occur. In contrast, this embodiment provides threshold distribution data with appropriate threshold values ​​a, b, c, and d for each of positions A, B, C, and D, and further associates this threshold distribution data with highly accurate position information. This enables highly accurate protective film determination with reduced risk of erroneous determinations.

[0050] Second Embodiment Next, a second embodiment of the present invention will be described below with reference to FIGS. 4 and 5. The following description will focus on differences from the first embodiment, and the remaining aspects are the same as those of the first embodiment, so redundant description will be omitted. FIG. 4 illustrates a protective film inspection method using a protective film inspection mechanism of a laser processing apparatus according to this embodiment. Here, (A) illustrates a configuration in which film thicknesses are compared between reticle shots, (B) illustrates a configuration in which the film thickness of a reference chip located near the wafer center is compared with that of chips at inspection positions around it, and (C) illustrates a configuration in which film thicknesses are compared between chips at inspection positions equidistant from the wafer center. Furthermore, FIG. 5 illustrates a configuration in which film thicknesses are compared using images obtained in an imaging process that captures the same pattern position in this embodiment. (A) illustrates a case in which images captured at the same inspection position are compared, and (B) illustrates a case in which the same inspection position is obtained using position information and then compared.

[0051] In the first embodiment, the thickness of the protective film p is determined by comparing it with a threshold distribution. In this embodiment, the thickness of the protective film p is determined by comparing the fluorescence intensity at each position on the wafer W after the protective film p is formed. The following comparison and determination are performed by the control unit 400. First, in FIG. 4A , portions having the same device layer formation pattern are compared. That is, for each of the ranges R1, R2, R3, and R4 in FIG. 4A , if the device layer pattern is the same, the fluorescence intensity distributions measured at the positions of these four ranges R1, R2, R3, and R4 are compared. This makes it possible to eliminate variations in fluorescence intensity due to differences in the device layer formation pattern. If the thickness of the protective film p is normal, the fluorescence intensity distributions in all ranges will be approximately the same. If there is a partial abnormality in the thickness, the fluorescence intensity in that portion will be higher or lower than in the other ranges.

[0052] 4B, the chip at the center of the circular surface of the device layer is set as the reference-position chip Pr, and the distribution of fluorescence intensity corresponding to the film thickness measured at the position of this reference-position chip Pr is set as appropriate (acceptance standard), and then the measurement results of the inspection-position chips Pe located around the reference-position chip Pr are judged. In other words, when a protective film p is applied and formed by a coating process such as spin coating, coating defects tend not to occur at the center of the device layer, so the distribution of fluorescence intensity of the reference-position chip Pr located at this center is used as a reference value.

[0053] 4C, a concentric range is set around the center CL on the circular surface of the device layer, and the distribution of fluorescence intensity is compared between the positions of multiple inspection target chips Pe within that range. In other words, when a protective film p is applied and formed by spin coating or the like, the film thickness tends to be the same within the concentric range around the center CL, so the quality of the film thickness of the protective film p is judged based on whether or not there are any deviations in the fluorescence intensity among these.

[0054] When comparing images shown in FIGS. 4A to 4C, no additional process is required if the images are compared between which the position of the inspection target chip Pe is the same, as shown on the left and right sides of FIG. 5A. However, as shown in FIG. 5B, the position of the inspection target chip Pe may generally be slightly shifted between the captured images. In such cases, it is preferable to perform an image adjustment process to match the relative positions of the images so that the position information associated with each image matches before comparing them. Furthermore, when inspecting multiple wafers W having the same pattern, the device layer patterns are identical between each wafer W, and the position information of each chip when positioned on the processing table 32 is also identical. Therefore, the comparison target for the protective film inspection at the position of the inspection target chip Pe may be the position of another chip on the same wafer W, or the position of another chip on another wafer W. In this embodiment, since wafers W after protective film formation are compared, only the pre-measurement 2 is performed for comparison, without the pre-measurement 1. On the other hand, when the position of another chip on the same wafer W is selected (that is, when comparing objects within the same individual), not only pre-measurement 1 but also pre-measurement 2 becomes unnecessary.

[0055] Third Embodiment Next, a third embodiment of the present invention will be described below with reference to FIGS. 6 and 7. FIG. 6 illustrates a protective film inspection method using a protective film inspection mechanism of a laser processing apparatus according to this embodiment, where (A) shows a case in which film thickness determination at positions away from the wafer street (st) is excluded, and (B) shows a form in which film thickness determination at positions of chips on the outer peripheral edge of the wafer is excluded. FIG. 7 is a flowchart illustrating each step of protective film inspection in this embodiment. Because this embodiment can be suitably combined with the first and second embodiments, the following description will focus on additions and differences from the first and second embodiments. The remaining aspects are the same as those of the apparatus and method of the first or second embodiment, and therefore will not be described again.

[0056] In this embodiment, throughput can be improved by preventing an incorrect defect determination from being included in the determination content. Specifically, if the thickness of the protective film p at the center of the inspection target chip Pe shown in FIG. 6A is outside the specified range, conventionally, it would be determined that the protective film p has a defective portion df and would need to be recoated. However, in this embodiment, as described in the first embodiment, the pattern of the device layer formed on the wafer W and its position information are associated with each other with high precision. Therefore, if debris adheres to the location where the defective portion df occurs, it can be determined whether it will affect the inspection target chip Pe. Therefore, if the defective portion df is only located in a position where it will not have an effect (a position where it will not cause processing defects), it can be processed without being determined as a defective protective film p. In this case, incorrect defect determinations can be avoided, eliminating the need for unnecessary rework such as recoating, and significantly improving throughput. Referring again to FIG. 6A, the defective portion df is located at the center of the inspection target chip Pe and is located furthest from the street st formed between adjacent chips. The adhesion of debris becomes a problem when it adheres to or near the street st, and neither of these situations applies to Figure 6(A). Therefore, even if the protective film p is thick enough to cover a defective portion df and debris adheres there, no problem will arise. Therefore, although the symbol Pe is used here, from the perspective of improving throughput, it is preferable to perform an exclusion process to exclude it from the inspection target.

[0057] The same applies to the case of FIG. 6B. FIG. 6B shows the outer peripheral edge of the wafer W, and the arc at the top of the page indicates the outer peripheral edge of the wafer W. This outer peripheral edge contains chipped chips that cannot be used as products. Here, if a thickness defect in the protective film p is found at the position indicated by the reference character df in the figure, in the conventional case, the formation position of the defective portion df would be deemed to overlap with the street st, and the chip would be sent for recoating. However, in this embodiment, as described in the first embodiment above, the device layer pattern formed on the wafer W and its position information are associated with each other with high accuracy. Therefore, even if the position information of the chipped chip is known with high accuracy, a process of excluding the defective portion df from the determination can be performed, and the chip can be processed without being deemed defective. In this case, an incorrect defect determination can be avoided, eliminating unnecessary rework such as recoating, and significantly improving throughput.

[0058] 7, in the protective film inspection of this embodiment, first, in step ST1, a wafer W having a protective film p formed thereon is positioned on the processing table 32. In the subsequent step ST2, ultraviolet light is irradiated onto the positioned wafer W, and the film thickness distribution is determined by measuring the fluorescence intensity. In the subsequent step ST3, the presence or absence of a coating defect in the protective film p is determined. If no coating defect is found, the process proceeds to step ST6, where the wafer W is determined to be a non-defective product and is then subjected to processing. On the other hand, if a coating defect is determined to be present in step ST3, the process proceeds to step ST4.

[0059] In step ST4, it is determined whether the location of the coating defect affects the manufacturing defect. That is, for example, if a defective portion df occurs at a position away from the street st as shown in FIG. 6A, this is excluded from the defect determination. Also, if a defective portion df occurs at the position of a chipped chip as shown in FIG. 6B, this is also excluded from the defect determination. If, after taking these exclusions into consideration, it is determined that the defect does not affect the manufacturing defect, the process proceeds to step ST6, where the wafer W is determined to be a non-defective product, and the wafer W is then subjected to processing. On the other hand, if it is determined in step ST4 that there is a coating defect, the process proceeds to step ST5, where the wafer W is determined to be a defective product. After the protective film p is washed and removed from the wafer W determined to be a defective product, the protective film p is coated again. The wafer W thus recoated is then subjected to re-inspection from step ST1 onwards.

[0060] [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described below with reference to FIGS. 8 and 9. FIG. 8 is a diagram illustrating a protective film inspection method using a protective film inspection mechanism of a laser processing apparatus according to this embodiment, and is an explanatory diagram showing a form in which only the street st of a wafer W and its surrounding area are inspected. FIG. 9 is a flowchart showing each step of the protective film inspection in this embodiment. Note that this embodiment can be suitably combined with the first and second embodiments, and therefore, the following description will focus on the additions and differences to the first and second embodiments. The remaining aspects are the same as those of the apparatus and method of the first or second embodiment, and therefore a repeated description thereof will be omitted.

[0061] In the case of the third embodiment, in order to improve throughput, incorrect defective judgments were excluded. In contrast, in this embodiment, a portion that may affect manufacturing defects is determined as an inspection position, and inspection is performed only on this inspection position. For example, in FIG. 8, if debris adheres to street st and the surrounding area adjacent to both sides of street st, it will affect manufacturing defects, so only this area is judged for the presence or absence of coating defects. On the other hand, portions other than street st and the surrounding area adjacent to both sides of street st are excluded from inspection. This significantly improves throughput.

[0062] In the protective film inspection of this embodiment, as shown in FIG. 9 , first, in step ST1A, a wafer W having a protective film p formed thereon is positioned on the processing table 32. In the subsequent step ST2A, an inspection position is determined. That is, a street st and peripheral areas adjacent to both sides of the street st are set as inspection positions. In the subsequent step ST3A, ultraviolet light is irradiated onto the wafer W at the position determined in step ST2A, and the fluorescence intensity is measured to determine the film thickness distribution. Meanwhile, the area excluded in step ST2A is excluded from the inspection target. In the subsequent step ST4A, the presence or absence of a coating defect in the protective film p is determined. If no coating defect is found, the process proceeds to step ST6A, where the wafer W is determined to be a non-defective product and is then subjected to processing. On the other hand, if a coating defect is determined to be present in step ST4A, the wafer W is sent to step ST5A and determined to be a defective product. A wafer W determined to be a defective product has the protective film p washed and removed, and then the protective film p is re-coated. The wafer W thus recoated is then re-inspected from step ST1A onwards.

[0063] As an example, an example to which this embodiment is applied is shown below. In this example, the following measurement conditions were used: Wafer W size: φ300 mm Chip size: 12 mm x 12 mm Number of streets: 24 vertical x 24 horizontal Field of view width during inspection: 4 mm (field of view width w = 4 mm in Figure 10) Scanning method: Two methods were used: scanning the entire surface (comparative example), and scanning linearly along the streets as shown in Figure 10 (inventive example).

[0064] Under the above measurement conditions, the number of scans required for the comparative example was 75, while the number of scans required for the inventive example was 48 (24 scans along the vertical streets + 24 scans along the horizontal streets). This result confirmed that the number of scans could be reduced by 36%. As such, it was confirmed that this example can significantly reduce the number of scans, thereby enabling a significant improvement in throughput.

[0065] In the above example, the field of view width w was set to 4 mm to allow for some leeway, as shown in Fig. 11(A). In contrast, as shown in Fig. 11(B), if the field of view width w is narrowed to 2 mm by limiting the measurement range to 1 mm on either side of the center line of the street st, more precise measurements become possible due to the narrowed field of view width. As a result, the measurement resolution is improved, making it possible to achieve both improved throughput and improved measurement accuracy.

[0066] Although the embodiments of the present invention have been described above, the embodiments may be combined as needed. In particular, when the first or second embodiment is combined with the third or fourth embodiment, it is possible to improve throughput in addition to highly accurate determination of coating defects.

[0067] The laser processing apparatus and method described above enable processing based on more accurate coating defect determination, and therefore have great industrial applicability.

[0068] 10 Loader side base 11 Spinner table 12 Spinner table 30 Processing side base 31 Positioning mechanism 31a Axial positioning unit 31b Axial positioning unit 31c Shaft angle adjustment mechanism 32 Processing table 50 Irradiation unit 51 Light source 52 Lens 53 Filter 60 Detector 61 Detector 62 Lens 63 Filter 100 Protective film forming device (coating mechanism) 200 Processing device 300 Protective film inspection device (protective film inspection mechanism) 31a0 Y-axis direction moving base 31b0 X-axis direction moving base 31a1 Guide rail 31b1 Guide rail 31a2 Ball screw 31a3 Servo motor 31b3 Linear motor 400 Control unit CL Center (central position) Pe Inspection target position chip Pr Reference position chip UV Ultraviolet light W Wafer (workpiece) w Field of view width

Claims

1. A laser processing device comprising a protective film inspection mechanism that determines the coating condition of a protective film applied to a workpiece, and a positioning mechanism that places and positions the workpiece on a processing table during laser processing, wherein after the positioning mechanism has positioned the workpiece on the processing table, the protective film inspection mechanism determines the coating condition of the protective film.

2. The laser processing device according to claim 1, wherein the protective film inspection mechanism comprises: an irradiation unit that irradiates the protective film with excitation light; a detection unit that detects fluorescence emitted by the protective film; and a control unit that determines the coating state by obtaining a distribution of fluorescence intensity based on the detection result of the detection unit, wherein the control unit has threshold distribution data in which a threshold is set for each position on the workpiece based on a first pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent has been formed, and determines the coating state by comparing the threshold distribution data with post-protective film application fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent has been formed.

3. The laser processing device according to claim 1, wherein the protective film inspection mechanism comprises: an irradiation unit that irradiates the protective film with excitation light; a detection unit that detects fluorescence emitted by the protective film; and a control unit that determines the coating state by obtaining a distribution of fluorescence intensity based on the detection result of the detection unit, wherein the control unit has threshold distribution data in which a threshold is set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state in which the protective film containing a light absorbent has been formed, and determines the coating state by comparing the post-protective film application fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state in which the protective film containing a light absorbent has been formed with the threshold distribution data.

4. The laser processing device according to claim 1, wherein the protective film inspection mechanism comprises: an irradiation unit that irradiates the protective film with excitation light; a detection unit that detects fluorescence emitted by the protective film; and a control unit that determines the coating state by obtaining a distribution of fluorescence intensity based on the detection result of the detection unit, wherein the control unit has: first pre-measurement data that is a lower threshold set for each position on the workpiece based on a first pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is not applied; and second pre-measurement data that is an upper threshold set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film is applied; and calculates threshold distribution data that is set between the first pre-measurement data and the second pre-measurement data, and determines the coating state by comparing post-protective film application fluorescence intensity data obtained by irradiating the excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent has been formed, with the threshold distribution data.

5. The laser processing device according to claim 1, characterized in that the workpiece has a plurality of identical reticle shots that form the same pattern, the positioning mechanism acquires position information for each of the identical reticle shots, and the protective film inspection mechanism determines the coating state by comparing the coating state at the position of each of the identical reticle shots that are linked to each other by the position information.

6. The laser processing device according to claim 1, wherein the workpiece has a reference position chip placed at its center and inspection position chips placed around the reference position chip, the positioning mechanism acquires position information for each of the reference position chip and the inspection position chip, and the protective film inspection mechanism sets the coating state of the protective film at the position of the reference position chip as an acceptance standard, and judges the coating state of the protective film at the position of the inspection position chip by comparing it with the acceptance standard.

7. The laser processing device according to claim 1, further comprising a coating mechanism that applies the protective film to the workpiece by spin coating, wherein the workpiece has a plurality of inspection target position chips, the positioning mechanism acquires position information for each of the inspection target position chips, and the protective film inspection mechanism makes a judgment by comparing the coating state between each position of the inspection target position chips that have position information on concentric positions from the center position of the workpiece.

8. A laser processing device according to any one of claims 5 to 7, characterized in that the protective film inspection mechanism matches the relative positions of the images to be compared based on position information acquired from the positioning mechanism before comparing the coating conditions.

9. The laser processing device according to any one of claims 1 to 7, characterized in that the protective film inspection mechanism excludes from the judgment of the coating state portions of the workpiece that are not related to the presence or absence of processing defects after laser processing.

10. A laser processing method comprising: a positioning step of placing a workpiece on a processing table before laser processing and positioning it; and a determination step of measuring, after the positioning step, the state of application of a protective film applied to the workpiece positioned on the processing table and determining the state of application of the protective film.

11. The laser processing method according to claim 10, characterized in that the judgment step comprises: a threshold distribution creation step of creating threshold distribution data in which a threshold is set for each position on the workpiece based on a first pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film is not applied; and a comparison step of judging the coating state by comparing fluorescence intensity data after protective film application, obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent has been formed, with the threshold distribution data.

12. The laser processing method according to claim 10, characterized in that the judgment step comprises: a threshold distribution creation step of creating threshold distribution data in which a threshold is set for each position on the workpiece based on a second pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state in which the protective film is applied; and a comparison step of judging the coating state by comparing fluorescence intensity data after protective film application, obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state in which the protective film containing a light absorbent is formed, with the threshold distribution data.

13. The laser processing method according to claim 10, characterized in that the judgment step comprises: a threshold distribution creation step of calculating threshold distribution data formed between: first pre-measurement data, which is a lower limit threshold set for each position on the workpiece, based on a first pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film is not applied; and second pre-measurement data, which is an upper limit threshold set for each position on the workpiece, based on a second pre-measured fluorescence intensity obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film is applied; and a comparison step of judging the application state by comparing, with the threshold distribution data, fluorescence intensity data after protective film application, which is obtained by irradiating excitation light onto the workpiece positioned on the processing table in a state where the protective film containing a light absorbent is formed.

14. The laser processing method according to claim 10, characterized in that the workpiece has a plurality of identical reticle shots that form the same pattern, the positioning step acquires position information for each of the identical reticle shots, and the determination step compares the coating states at the positions of the identical reticle shots linked to each other by the position information to determine the coating state of the protective film.

15. The laser processing method according to claim 10, characterized in that the workpiece has a reference position chip placed at its center and inspection position chips placed around the reference position chip, and in the positioning step, position information for each of the reference position chip and the inspection position chip is acquired, and in the judging step, the coating state of the protective film at the position of the reference position chip is set as an acceptance standard, and the coating state of the protective film at the position of the inspection position chip is judged by comparing it with the acceptance standard.

16. The laser processing method according to claim 10, further comprising a coating step of applying the protective film to the workpiece having a plurality of inspection target position chips by spin coating before the positioning step, wherein the positioning step acquires position information for each of the inspection target position chips on the workpiece, and the judging step compares the coating state between each of the positions of the inspection target position chips on concentric circles from the center position of the workpiece to make a judgment.

17. A laser processing method according to any one of claims 14 to 16, characterized in that the judgment step comprises: an imaging step of acquiring an image of each inspection position on the workpiece; and an image adjustment step of matching the relative positions of the images to be compared based on the position information acquired in the positioning step, before comparing the coating states.

18. A laser processing method according to any one of claims 10 to 16, characterized in that the judgment step includes an exclusion step of excluding from the judgment of the coating state any portion of the workpiece that is not related to the presence or absence of processing defects after laser processing.

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