Laser processing apparatus and laser processing method

Abstract

The laser processing apparatus includes a protective film inspection mechanism that determines a coating state of a protective film coated on an object to be processed, and a positioning mechanism that places and positions the object to be processed at the time of laser processing on a processing table, and the protective film inspection mechanism determines the coating state of the protective film after the positioning mechanism positions the object to be processed on the processing table. In addition, the laser processing method includes a positioning step of placing and positioning an object to be processed before laser processing on a processing table, and a determination step of determining a coating state of a protective film coated on the object to be processed positioned on the processing table after the positioning step to determine the coating state of the protective film.

Description

Technical Field

[0001] This invention relates to laser processing apparatus and laser processing method.

[0002] This application claims priority based on Japanese Patent Application No. 2024-053604, filed on March 28, 2024, the contents of which are incorporated herein by reference. Background Technology

[0003] When manufacturing semiconductors, molten debris can adhere to the device layers due to laser ablation. Therefore, a protective film made of a water-soluble resin is formed on the wafer surface before laser ablation. This protective film protects the device layers from the debris generated during laser ablation. Furthermore, after laser ablation, the debris, along with the protective film, can be washed away.

[0004] Although protective films are applied using methods such as spin coating, coating defects can occasionally occur. Specifically, incomplete coating may occur locally on the wafer surface, or the film thickness may be too thick or too thin than specified. In cases of incomplete coating or excessively thin film, the device layer in that area may be affected by debris. Conversely, in cases of excessively thick film, the laser may be obstructed by the protective film, potentially leading to defects in laser ablation processing. Therefore, from the perspective of improving yield, it is necessary to form a protective film with an appropriate thickness, thus requiring prior inspection of the film thickness.

[0005] As an example of a method for checking film thickness, Patent Document 1 discloses a method for measuring the thickness of a protective film. This thickness measurement method includes the following steps: a pre-protective film formation measurement step, in which light is irradiated onto the surface of a substrate without a protective film and the first reflection intensity of reflected light from the surface is measured; a protective film formation step, in which a protective film comprising a light-absorbing material is formed on the surface; a post-protective film formation measurement step, in which excitation light of a wavelength that causes the light-absorbing material to fluoresce is irradiated onto the protective film and a second reflection intensity comprising the fluorescence of the protective film and reflected light from the surface is measured by a measurement unit; a protective film fluorescence intensity calculation step, in which the fluorescence intensity of the protective film is calculated by subtracting the first reflection intensity measured in the pre-protective film formation measurement step from the second reflection intensity measured in the post-protective film formation measurement step to remove the reflection intensity caused by the pattern formed on the surface; and a protective film thickness identification step, in which the thickness of the protective film is identified based on pre-obtained correlation data between the protective film fluorescence intensity and the protective film thickness, and the calculated protective film fluorescence intensity. Furthermore, it is explained that according to this thickness measurement method, the thickness of a protective film formed on the surface of a substrate having a pattern on its surface can be accurately measured.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2022-178427

[0007] However, in the thickness measurement method described in Patent Document 1, both the measurement step before and after the protective film is formed are performed on the coating stage where the protective film is formed. Since the coating stage is not designed for high-precision alignment, it is difficult to achieve precise alignment between the pattern position before and after the protective film is formed. Summary of the Invention

[0008] The present invention was made in view of the above circumstances, and its purpose is to provide a laser processing apparatus and a laser processing method that can perform processing based on a more accurate coating defect determination.

[0009] To address the aforementioned issues and achieve the stated objectives, the present invention employs the following approach.

[0010] (1) A laser processing apparatus according to one aspect of the present invention comprises: a protective film inspection mechanism for determining the coating state of the protective film applied to the workpiece; and a positioning mechanism for placing and positioning the workpiece during laser processing on a processing worktable.

[0011] After the positioning mechanism positions the workpiece on the processing table, the protective film inspection mechanism determines the coating status of the protective film.

[0012] According to the laser processing apparatus described in (1) above, it is possible to combine the high-precision position information related to each position on the workpiece positioned by the positioning mechanism on the processing worktable with the measurement results of the coating state of the protective film coated at each position to determine whether the product is good or bad.

[0013] (2) The laser processing apparatus described in (1) above can also be configured as follows:

[0014] The protective film inspection mechanism is equipped with:

[0015] The irradiation section irradiates the protective film with excitation light;

[0016] The detection unit detects the fluorescence emitted by the protective film; and

[0017] The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit.

[0018] The control unit has threshold distribution data, which is obtained by setting a threshold for each position on the workpiece based on a first pre-measured fluorescence intensity. The first pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table without the protective film, with the excitation light.

[0019] The control unit is configured to determine the coating state by comparing fluorescence intensity data after coating the protective film with the threshold distribution data. The fluorescence intensity data after coating the protective film is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0020] In the case of the laser processing apparatus described in (2) above, the coating state can be determined based on threshold distribution data obtained by setting thresholds 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. Thus, compared to the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with the same pattern, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0021] (3) The laser processing apparatus described in (1) above can also be configured as follows:

[0022] The protective film inspection mechanism is equipped with:

[0023] The irradiation section irradiates the protective film with excitation light;

[0024] The detection unit detects the fluorescence emitted by the protective film; and

[0025] The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit.

[0026] The control unit has threshold distribution data, which is obtained by setting a threshold for each position on the workpiece based on a second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, which is positioned on the processing table with the protective film coated, with the excitation light.

[0027] The control unit is configured to determine the coating state by comparing fluorescence intensity data after coating the protective film with the threshold distribution data. The fluorescence intensity data after coating the protective film is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0028] In the case of the laser processing apparatus described in (3) above, the coating state can be determined based on threshold distribution data set for each position on the workpiece. Specifically, the influence of fluorescence emitted by the light-absorbing agent within the protective film and reflected by the device layer can be eliminated. Thus, compared to the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with identical patterns, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0029] (4) The laser processing apparatus described in (1) above can also be configured as follows:

[0030] The protective film inspection mechanism is equipped with:

[0031] The irradiation section irradiates the protective film with excitation light;

[0032] The detection unit detects the fluorescence emitted by the protective film; and

[0033] The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit.

[0034] The control unit has:

[0035] The first pre-measured data is a lower limit threshold set for each location on the workpiece based on a first pre-measured fluorescence intensity, the first pre-measured fluorescence intensity being obtained by irradiating the workpiece, positioned on the processing table without the protective film coated, with the excitation light; and

[0036] The second pre-measured data is an upper limit threshold set for each location on the workpiece based on the second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, which is positioned on the processing table with the protective film coated, with the excitation light.

[0037] The control unit is configured to:

[0038] Calculate the threshold distribution data set between the first pre-measured data and the second pre-measured data.

[0039] The coating state is determined by comparing the fluorescence intensity data after the protective film is applied with the threshold distribution data. The fluorescence intensity data after the protective film is applied is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0040] In the case of the laser processing apparatus described in (4) above, the coating state can be determined based on threshold distribution data set for each position on the workpiece. Specifically, the influence of fluorescence from the device layer at each position on the workpiece, as well as the influence of fluorescence emitted by the light-absorbing agent in the protective film and reflected by the device layer, can be removed simultaneously. Thus, compared to the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with the same pattern, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0041] (5) The laser processing apparatus described in (1) above can also be configured as follows:

[0042] The workpiece has multiple identical photomask exposure areas (reticle shots) with the same pattern as each other.

[0043] The positioning mechanism is configured to obtain the position information of each of the identical photomask exposure areas.

[0044] The protective film inspection mechanism is configured to determine the coating state by comparing the coating state at the respective positions of the same photomask exposure areas that are associated with each other using the position information.

[0045] In the case of the laser processing apparatus described in (5) above, the chips in the same photomask exposure areas are formed with the same pattern as each other, and therefore the patterns are identical. Thus, by comparing the measurement results of the protective film between the positions of the same photomask exposure areas, a precise determination can be made, which eliminates light scattering caused by the unevenness of the pattern on the workpiece.

[0046] (6) The laser processing apparatus described in (1) above can also be configured as follows:

[0047] The workpiece has a reference position chip disposed at the center of the workpiece and inspection object position chips disposed around the reference position chip.

[0048] The positioning mechanism is configured to acquire the position information of the reference position chip and the inspection object position chip, respectively.

[0049] The protective film inspection mechanism is configured as follows:

[0050] The coating state of the protective film at the location of the reference chip is set as a qualified benchmark, and

[0051] The coating state is determined by comparing the coating state of the protective film at the location of the chip being inspected with the pass / fail benchmark.

[0052] In the case of the laser processing apparatus described in (6) above, the reference position chip is located at the center of the workpiece, where it is less likely for the protective film to be poorly coated. Therefore, the coating state of the chip at the inspection target position can be determined using the protective film formed on the reference position chip as a pass / fail standard.

[0053] (7) The laser processing apparatus described in (1) above can also be configured as follows:

[0054] It also includes a coating mechanism that applies the protective film to the workpiece via spin coating.

[0055] The workpiece has multiple chips for checking the location of the target object.

[0056] The positioning mechanism is configured to obtain the position information of each of the inspection object's position chips.

[0057] The protective film inspection mechanism is configured to determine the coating state by comparing the coating state between the positions of the inspection object position chips, which have position information located in concentric circles from the center position of the workpiece.

[0058] In the case of the laser processing apparatus described in (7) above, the thickness of the protective film formed by spin coating is the same at all positions on a concentric circle starting from the center of the workpiece. Therefore, if the protective film is coated normally, the thickness of the protective film is also the same at each position of the chip at each inspection location on the concentric circle. Thus, the coating state of the protective film can be determined by comparing the thickness of the protective film at each position on the concentric circle to see if there are any areas with large differences in local film thickness.

[0059] (8) The laser processing apparatus described in any one of (5) to (7) above may also be configured as follows:

[0060] The protective film inspection mechanism is configured to ensure that the relative positions of the images being compared are consistent, based on position information obtained from the positioning mechanism, before comparing the coating states.

[0061] In the case of the laser processing apparatus described in (8) above, since the relative positions between the compared images are made consistent, it is not necessary to perform a preliminary measurement before applying the protective film. It should be noted that the positional information associated with the image obtained for a certain workpiece can also be used when determining the coating state of the protective film on other workpieces with the same pattern. Therefore, the comparison objects can be obtained from the same individual or from different individuals with the same pattern. Here, when the comparison objects are obtained from the same individual, it is not necessary to perform a preliminary measurement before applying the protective film at all.

[0062] (9) The laser processing apparatus described in any one of (1) to (7) above may also be configured as follows:

[0063] The protective film inspection mechanism is configured to exclude parts of the workpiece that are unrelated to whether there are defects after laser processing from the determination of the coating state.

[0064] In the case of the laser processing apparatus described in (9) above, the high-precision position information obtained by the positioning mechanism can be used to prevent improper defect judgments from being made at locations that would not result in product defects, such as parts far from the processing line (cutting track) or defective chip parts located on the outer periphery, thereby improving processing capacity.

[0065] (10) A laser processing method according to one aspect of the present invention includes:

[0066] The positioning process involves placing and positioning the workpiece on the processing table before laser processing; and

[0067] In the determination process, after the positioning process, the coating state of the protective film applied to the workpiece positioned on the processing table is measured to determine the coating state of the protective film.

[0068] According to the laser processing method described above (10), the high-precision position information of each position on the workpiece positioned on the processing worktable through the positioning process can be combined with the measurement results of the coating state of the protective film coated at each position in the judgment process to determine whether it is qualified or not.

[0069] (11) The laser processing method described in (10) above can also be configured as follows:

[0070] The determination process includes:

[0071] The threshold distribution fabrication process involves generating threshold distribution data for each location on the workpiece by setting a threshold based on a first pre-measured fluorescence intensity. The first pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table without the protective film, with excitation light.

[0072] The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0073] In the case of the laser processing method described in (11) above, the coating state can be determined based on threshold distribution data set for each position on the workpiece. Specifically, the influence of fluorescence from the device layer at each position on the workpiece can be removed. Thus, compared to the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with the same pattern, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0074] (12) The laser processing method described in (10) above can also be configured as follows:

[0075] The determination process includes:

[0076] The threshold distribution fabrication process involves generating threshold distribution data for each location on the workpiece by setting a threshold based on a second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table with the protective film coated, with excitation light.

[0077] The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0078] In the case of the laser processing method described above (12), the coating state can be determined based on threshold distribution data set for 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 removed. Thus, compared with the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with the same pattern, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0079] (13) The laser processing method described in (10) above can also be configured as follows:

[0080] The determination process includes:

[0081] The threshold distribution fabrication process involves calculating the threshold distribution data formed between the first pre-measured data and the second pre-measured data, wherein...

[0082] The first pre-measured data is a lower threshold value set for each location on the workpiece based on a first pre-measured fluorescence intensity, the first pre-measured fluorescence intensity being obtained by irradiating the workpiece, positioned on the processing table without the protective film, with excitation light; and

[0083] The second pre-measured data is an upper limit threshold set for each location on the workpiece based on a second pre-measured fluorescence intensity, the second pre-measured fluorescence intensity being obtained by irradiating the workpiece, positioned on the processing table with the protective film coated, with the excitation light; and

[0084] The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

[0085] In the case of the laser processing method described above (13), the coating state can be determined based on threshold distribution data set for each position on the workpiece. Specifically, 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 can be removed. Thus, compared to the case where the threshold on the workpiece is set constant at each position, a more precise determination can be made. It should be noted that when processing multiple workpieces with the same pattern, the threshold distribution data can be obtained only for the first workpiece, and the same threshold distribution data can be used for subsequent workpieces.

[0086] (14) The laser processing method described in (10) above can also be configured as follows:

[0087] The workpiece has multiple identical photomask exposure areas with the same pattern as each other.

[0088] In the positioning process, the position information of each of the identical photomask exposure areas is obtained.

[0089] In the determination process, the coating state of the protective film is determined by comparing the coating states at the respective positions of the same photomask exposure areas that are associated with each other using the position information.

[0090] In the case of the laser processing method described above (14), since the chips in each identical photomask exposure area are formed with the same pattern, the patterns are identical. Therefore, by comparing the measurement results of the protective film between the positions of the identical photomask exposure areas, a precise protective film determination can be made, which eliminates light scattering caused by the unevenness of the pattern on the workpiece.

[0091] (15) The laser processing method described in (10) above can also be configured as follows:

[0092] The workpiece has a reference position chip disposed at the center of the workpiece and inspection object position chips disposed around the reference position chip.

[0093] In the positioning process, the position information of the reference position chip and the inspection object position chip is obtained respectively.

[0094] In the determination process,

[0095] The coating state of the protective film at the location of the reference chip is set as a qualified benchmark, and

[0096] The coating state is determined by comparing the coating state of the protective film at the location of the chip being inspected with the pass / fail benchmark.

[0097] In the case of the laser processing method described above (15), the reference position chip is located at the center of the workpiece, where it is less likely for the protective film to be poorly coated. Therefore, the coating state of the chip at the inspection target position can be determined by using the protective film formed on the reference position chip as a pass / fail standard.

[0098] (16) The laser processing method described in (10) above can also be configured as follows:

[0099] Prior to the positioning process, a coating process is also included, in which the protective film is applied to the workpiece having multiple inspection target position chips by spin coating.

[0100] In the positioning process, the position information of each of the inspection object position chips of the workpiece is obtained.

[0101] In the determination process, the coating state is determined by comparing the coating state between the positions of the inspection target position chips located in concentric circles from the center position of the workpiece.

[0102] In the case of the laser processing method described above (16), the thickness of the protective film formed by spin coating is the same at all positions on a concentric circle starting from the center of the workpiece. Therefore, if the protective film is coated normally, the thickness of the protective film is also the same at each position of the chip at each inspection location on the concentric circle. Thus, the coating state of the protective film can be determined by comparing the thickness of the protective film at each position on the concentric circle to see if there are any local thickness deviations from the reference.

[0103] (17) The laser processing method described in any one of (14) to (16) above may also be configured as follows:

[0104] The determination process includes:

[0105] The photographic process acquires images of each inspection location of the workpiece; and

[0106] In the image adjustment process, before comparing the coating states, the relative positions of the images being compared are made consistent based on the position information obtained in the positioning process.

[0107] In the case of the laser processing method described above (17), since the relative positions between the compared images are made consistent, it is not necessary to perform a preliminary measurement before applying the protective film. It should be noted that the positional information associated with the image obtained for a certain workpiece is also effective when determining the coating state of the protective film on other workpieces with the same pattern. Therefore, the comparison objects can be obtained from the same individual or from different individuals. Here, when the comparison objects are obtained from the same individual, it is not necessary to perform a preliminary measurement before applying the protective film.

[0108] (18) The laser processing method described in any one of (10) to (16) above may also be configured as follows:

[0109] The determination process includes an exclusion process, in which parts of the workpiece that are unrelated to whether there are defects after laser processing are excluded from the determination of the coating state.

[0110] In the case of the laser processing method described above (18), when performing the rejection process, the high-precision position information obtained in the positioning process can be used to prevent unnecessary defect judgments from being made in locations that would not cause product defects, such as parts far from the processing line (cutting track) or defective chip parts located on the outer periphery, thereby improving processing capability.

[0111] According to the laser processing apparatus and laser processing method of the present invention, processing can be performed based on more accurate coating defect judgment. Attached Figure Description

[0112] Figure 1 This is a perspective view showing the schematic configuration of the protective film inspection device included in the laser processing apparatus of the first embodiment of the present invention.

[0113] Figure 2 This is a plan view showing the relative positional relationship between the loading-side spin coating stage and the processing-side processing stage of the laser processing device.

[0114] Figure 3 This is a diagram illustrating the method for determining the threshold data used in the protective film inspection performed by the protective film inspection agency. The horizontal axis represents the position along the surface of the wafer, and the vertical axis represents the fluorescence intensity at each position.

[0115] Figure 4This is a diagram illustrating the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus according to the second embodiment of the present invention. Here, (A) shows the method of comparing film thicknesses between each other in the photomask exposure areas; (B) shows the method of comparing the film thickness of a reference chip near the center of the wafer with the film thickness of the chip at the inspection target location around it; and (C) shows the method of comparing film thicknesses between the chips at the inspection target location located at an equal distance from the center of the wafer.

[0116] Figure 5 The diagram illustrates how the film thickness is compared at the same pattern position in this second embodiment. (A) shows the comparison based on images obtained from taking pictures at the same inspection position; (B) shows the comparison after obtaining the same inspection position using position information.

[0117] Figure 6 The diagram illustrates the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus according to the third embodiment of the present invention. (A) shows the case where film thickness determination is excluded for locations far from the wafer dicing track; (B) shows the method where film thickness determination is excluded for locations of defective chips at the outer periphery edge of the wafer.

[0118] Figure 7 This is a flowchart illustrating the various steps of the protective film inspection in this third embodiment.

[0119] Figure 8 This diagram illustrates the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus according to the fourth embodiment of the present invention, and is an explanatory diagram showing a method of inspection limited to the dicing track of the wafer and its surrounding area.

[0120] Figure 9 This is a flowchart illustrating the steps involved in the protective film inspection in this fourth embodiment.

[0121] Figure 10 This is a diagram showing a variation of the fourth embodiment, which is a plan view of a method for checking film thickness by scanning in a straight line along the dicing path of the wafer.

[0122] Figure 11 This is a diagram illustrating another variation of the fourth embodiment, and is a magnified view of a portion of the wafer. Detailed Implementation

[0123] Hereinafter, with reference to the accompanying drawings, laser processing apparatus and laser processing method of various embodiments and modifications thereof of the present invention will be described.

[0124] [First Implementation Method]

[0125] The following reference Figures 1-3The first embodiment of the present invention will now be described.

[0126] In this instruction, first refer to Figure 1 and Figure 2 The overall structure of the laser processing device will be described here. Figure 1 This is a perspective view showing the schematic configuration of the protective film inspection device included in the laser processing apparatus of this embodiment. Figure 2 This is a plan view showing the relative positional relationship between the loading-side spin coating stage and the processing-side processing stage of the laser processing device.

[0127] like Figure 1 and Figure 2 As shown, the laser processing apparatus of this embodiment includes: a protective film forming apparatus 100 for forming a protective film p by spin coating on a wafer W, which is a workpiece; a processing apparatus 200 for performing 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 for inspecting the protective film p before laser processing above the processing worktable 32 of the processing apparatus 200; and a control unit 400 for controlling the protective film forming apparatus 100, the processing apparatus 200, and the protective film inspection apparatus 300, etc.

[0128] The protective film forming apparatus 100 includes a loading side base 10, a spin coating worktable 11 and 12, a cleaning mechanism (not shown) and a protective film coating mechanism (not shown).

[0129] The loading side base 10 is a base that is assembled in a specified position.

[0130] The spin coating stage 11 is a circular stage supported by an axis on the loading side base 10. The spin coating stage 11 can rotate freely about a vertical axis passing through its center. The spin coating stage 11 can adsorb and fix the wafer W placed on its upper surface.

[0131] The spin coating stage 12 is a circular stage that is axially supported on the loading side base 10 adjacent to the spin coating stage 11. The spin coating stage 12 can rotate freely about a vertical axis passing through its center. The spin coating stage 12 can adsorb and fix the wafer W placed on its upper surface.

[0132] One protective film coating mechanism is provided for each of the spin coating stages 11 and 12. The protective film coating mechanism provided on the spin coating stage 11 dispenses the protective film coating solution (or protective film) onto the spin coating stage 11 coaxially. Thus, after the wafer W is coaxially adsorbed and fixed on the spin coating stage 11, the coating solution applied to the wafer W extends radially from the center of the wafer W, thereby forming a protective film p covering the entire surface of the wafer W. Similarly, the protective film coating mechanism provided on the spin coating stage 12 dispenses the protective film coating solution (or protective film) onto the spin coating stage 12 coaxially. Thus, after the wafer W is coaxially adsorbed and fixed on the spin coating stage 12, the coating solution applied to the wafer W extends radially from the center of the wafer W, thereby forming a protective film p covering the entire surface of the wafer W. While this embodiment illustrates the formation of the protective film p through spin coating, other methods can also be used to form the protective film p.

[0133] The aforementioned cleaning mechanism is installed on both spin coating stages 11 and 12. If the protective film p fails inspection, it washes away the protective film p on the wafer W. Specifically, the cleaning mechanism located on spin coating stage 11 dispenses cleaning fluid onto the wafer W on spin coating stage 11 and discharges the waste fluid after cleaning, thereby washing away the protective film p. A new protective film p is then formed on the upper surface of the cleaned wafer W by the aforementioned protective film coating mechanism. Similarly, the cleaning mechanism located on spin coating stage 12 dispenses cleaning fluid onto the wafer W on spin coating stage 12 and discharges the waste fluid after cleaning, thereby washing away the protective film p. A new protective film p is then formed on the upper surface of the cleaned wafer W by the aforementioned protective film coating mechanism.

[0134] The processing apparatus 200 includes a laser irradiation unit (not shown), a processing side base 30, a positioning mechanism 31, and a processing worktable 32.

[0135] The aforementioned laser irradiation unit is mounted on the processing side base 30 and includes a light source and an optical system. Processing is performed by irradiating the wafer W, which is adsorbed and fixed on the processing stage 32, with a laser.

[0136] The machining-side base 30 is a base adjacent to the loading-side base 10 and positioned in a designated location. It should be noted that... Figure 1 and Figure 2 Although the processing-side base 30 and the loading-side base 10 are shown as separate for ease of explanation, they can also be integrated into one unit.

[0137] The positioning mechanism 31 includes a Y-axis positioning part 31a, an X-axis positioning part 31b, an θ-axis angle adjustment mechanism 31c, and a machining worktable 32.

[0138] The Y-axis positioning unit 31a includes: a Y-axis movable base 31a0; a pair of guide rails 31a1 for supporting the Y-axis movable base 31a0 on a machining-side base 30; a ball screw 31a2 arranged parallel to the guide rails 31a1 on the machining-side base 30 and rotatably supported about its central axis; and a servo motor 31a3 for rotating and driving the ball screw 31a2. The ball screw 31a2 engages with an internally threaded hole (not shown) formed on the lower surface of the Y-axis movable base 31a0. According to the Y-axis positioning unit 31a, the ball screw 31a2 rotates due to the rotation of the servo motor 31a3. As a result, the Y-axis movable base 31a0, having the aforementioned internally threaded hole engaged with the ball screw 31a2, moves horizontally along the Y-axis. At this time, the rotation amount of the servo motor 31a3 is appropriately adjusted by the control unit 400, thereby adjusting the movement amount of the Y-axis moving base 31a0 along the Y-axis direction, that is, the precise position of the machining table 32 along the Y-axis direction.

[0139] The X-axis positioning unit 31b includes: an X-axis movable base 31b0; a pair of guide rails 31b1 for supporting the X-axis movable base 31b0 on a Y-axis movable base 31a0; and a linear motor 31b3 arranged parallel to the guide rails 31b1 on the Y-axis movable base 31a0, and for moving the X-axis movable base 31b0 along the X-axis. According to this X-axis positioning unit 31b, the linear motor 31b3 moves the X-axis movable base 31b0, supported by the guide rails 31b1 in a manner that allows free movement along the X-axis, along the X-axis, thereby adjusting the amount of movement of the X-axis movable base 31b0 along the X-axis, i.e., the precise position of the machining table 32 along the X-axis.

[0140] The θ-axis angle adjustment mechanism 31c includes: a shaft (not shown) vertically mounted on an X-axis movable base 31b0 and providing shaft support for the machining table 32; and a servo motor (not shown) for rotating the shaft about a vertical axis (Z-axis). According to this θ-axis angle adjustment mechanism 31c, the servo motor is rotated about the Z-axis by a control unit 400, thereby precisely adjusting the rotation angle of the machining table 32.

[0141] The processing table 32 is a circular table that can rotate freely about a vertical axis passing through its center. The processing table 32 can hold and fix the wafer W placed on its upper surface. Through the positioning mechanism 31, the X-axis position, Y-axis position and θ-axis angle of the processing table 32 can be positioned with high precision.

[0142] The protective film inspection device 300 includes an irradiation unit 50, an inspection unit 60, and the aforementioned processing table 32. In this embodiment, the laser processing apparatus performs both laser processing of the wafer W and protective film inspection of the wafer W on the processing table 32. Therefore, the processing table 32 is a shared component of both the processing apparatus 200 and the protective film inspection device 300.

[0143] The irradiation unit 50 includes a light source 51, a lens 52, and a filter 53. Light, such as excitation light, is emitted from the light source 51, and this light is adjusted into parallel light by the lens 52 and further irradiated onto the processing stage 32 via the filter 53. During protective film inspection, a wafer W on which a protective film p is formed is adsorbed and arranged on the processing stage 32, so the light emitted from the irradiation unit 50 is irradiated onto the desired area of ​​the wafer W.

[0144] The detection unit 60 includes a detector 61, a lens 62, and a filter 63. This detection unit 60 can capture images of the area on the wafer W illuminated by light from the irradiation unit 50. Here, when the light irradiated from the irradiation unit 50 is ultraviolet light (an example of excitation light), the light-absorbing agent contained in the protective film emits fluorescence. The intensity of this fluorescence (hereinafter referred to as "fluorescence intensity") is mainly determined by the illumination intensity of the ultraviolet light, the irradiation time of the ultraviolet light, and the thickness of the protective film p. That is, the thicker the protective film p, the more light-absorbing agent is present, and therefore the higher the fluorescence intensity. Thus, the thickness of the protective film p can be determined using this relationship.

[0145] In this embodiment, the detection unit 60 is exemplified by using an area array sensor camera, but in addition, a linear array sensor camera, a photomultiplier tube, a beam splitter, etc., can also be used.

[0146] An area array sensor camera is a camera with a sensor having pixels arranged in a two-dimensional array. In this case, the illumination unit 50 can employ coaxial incident illumination or ring illumination.

[0147] A linear array sensor camera is a camera with a sensor having a one-dimensional arrangement of pixels, which moves the wafer W in a unidirectional linear motion to image the entire surface of the protective film p. In this case, strip illumination is preferably used as the illumination unit 50.

[0148] A photomultiplier tube (PMT) is a light detection unit capable of amplifying and capturing weak light. Unlike the two types of cameras mentioned above, a PMT measures only a single point of light. In this case, point illumination is preferably used as the illumination unit 50.

[0149] A spectrometer is a detection unit capable of measuring the intensity (spectrum) of each wavelength. Like a photomultiplier tube, a spectrometer measures only one spot of light. In this case, point illumination is preferably used as the illumination unit 50.

[0150] The irradiation unit 50 and the detection unit 60 described above are both controlled by the control unit 400. Therefore, by controlling the Y-axis positioning unit 31a, the X-axis positioning unit 31b and the θ-axis angle adjustment mechanism 31c respectively and simultaneously, the control unit 400 can enable the detection unit 60 to perform any one of spiral, concentric circle or linear (unidirectional scanning, reciprocating scanning) scanning on the protective film p.

[0151] The wafer W, processed by the laser processing apparatus having the above-described configuration, has a semiconductor material substrate that is circular in plan view, and a device layer formed on the upper surface of the substrate. To protect the device layer from debris generated during laser processing after the protective film is inspected, a protective film p is formed on the upper surface of the device layer of the wafer W by the aforementioned protective film forming apparatus 100 on a spin coater 11 or spin coater 12. The protective film p is a water-soluble resin film and is washed away along with the debris after processing.

[0152] Regarding the protective film p, the coating status is checked on the processing table 32 of the aforementioned protective film inspection device 300 for any omissions or abnormal film thickness. Specifically, if the protective film p is missed or too thin, the device layer in that area may be affected by debris, thus it is determined that "a protective film abnormality exists." Conversely, if the film thickness is too thick, the laser during processing may be obstructed by the protective film p, potentially resulting in processing defects; therefore, this is also determined to be "a protective film abnormality exists." In cases where a "protective film abnormality exists," the wafer W is not supplied for processing but is temporarily returned to the spin coating table 11 or spin coating table 12. After rinsing off the protective film p, the protective film p is coated again.

[0153] 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 the wafer W is positioned on the processing stage 32.

[0154] Regarding the laser processing method performed by the laser processing apparatus with the above-described configuration, the following description mainly focuses on the following steps: a positioning step, in which the wafer W to be laser processed is placed and positioned on the processing stage 32; and a judgment step, after the positioning step, in which the coating state of the protective film p coated on the wafer W positioned on the processing stage 32 is measured to determine whether the coating state of the protective film p is good. It should be noted that in the following description, the following case is illustrated by irradiating the protective film p with ultraviolet light from the irradiation unit 50 and receiving the fluorescence through the detection unit 60, thereby obtaining the fluorescence intensity. However, in this invention, the determination of the coating state of the protective film p can also be performed using an ultraviolet light absorption method instead of a fluorescence method.

[0155] As described above, the coating worktable is not designed for high-precision alignment, and therefore cannot precisely align the pattern position before and after the protective film is formed. Therefore, this embodiment does not utilize the spin coating worktables 11 and 12, but instead utilizes the positioning mechanism 31 of the processing device 200 capable of high-precision positioning and obtaining high-precision position information to perform the above-mentioned determination process.

[0156] Specifically, when determining whether the protective film p is good through the judgment process, instead of using a uniform threshold for the entire surface of the protective film p as in the past, it is as follows: Figure 3 As shown, a threshold is set for each location. That is, in the wafer W before the protective film p is formed, since the device layer has a raised pattern, when irradiated with, for example, ultraviolet light from the irradiation unit 50, in addition to the scattered light caused by the raised pattern, the pattern itself also emits fluorescence. The scattered light and fluorescence generated by these device layers also enter the detection unit 60. Therefore, in this embodiment, in order to detect poor coating and missing coating of the protective film p with high accuracy, the influence of scattered light and fluorescence generated by the device layers is removed.

[0157] For example, Figure 3 Position A on the left side of the paper represents the part of the device layer with high reflectivity that emits fluorescence when exposed to ultraviolet light. Therefore, the threshold a at position A is set higher than the thresholds at other positions B, C, and D.

[0158] Next, position B is the part of the device layer that emits fluorescence when exposed to ultraviolet light, even though the reflectivity of the device layer is low. Therefore, the threshold b at position B is set lower than that at position A and higher than that at positions C and D.

[0159] Next, although position C is the part of the device layer that does not emit fluorescence when exposed to ultraviolet light, the reflectivity of the device layer is relatively high. Therefore, the threshold c of position C is set lower than that of positions A and B and higher than that of position D.

[0160] Finally, position D is the portion of the device layer that does not emit fluorescence when exposed to ultraviolet light and has low reflectivity. Therefore, the threshold d for position D is set lower than the thresholds for any of the other positions A, B, and C.

[0161] The more specific settings of the above thresholds a, b, c, and d are as follows, and are carried out in three stages: pre-determination 1, pre-determination 2, and threshold determination.

[0162] First, in the preliminary measurement 1, the wafer W, in its uncoated state (without protective film p), is fixed and positioned on the processing stage 32. While maintaining this positioning, ultraviolet light (UV) is irradiated onto the wafer W from the irradiation unit 50, and the fluorescence emitted by the device layer on the wafer W (first preliminary measurement of fluorescence intensity) is received by the detection unit 60. Regarding the received light, at positions A, B, C, and D, since the presence or absence of fluorescence differs, 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, positions A and B are both "fluorescent," so their fluorescence intensities are a1 and b1, respectively; conversely, positions C and D are both "non-fluorescent," so their fluorescence intensities are close to zero, c1 and d1, respectively. The fluorescence intensity of the fluorescence emitted from each position of the device layer, obtained in this way, together with the coordinate information (X-axis position and Y-axis position, or radial position and circumferential angle) on the surface of the wafer W, is stored in the control unit 400 as a lower limit threshold, i.e., the first pre-measured data.

[0163] The subsequent preliminary measurement 2 was performed after a protective film was formed on wafer W, and its details will be described below.

[0164] That is, after the aforementioned pre-measurement 1, the control unit 400 moves the wafer W from the processing stage 32 to the spin coating stage 11 or spin coating stage 12. Next, the protective film forming apparatus 100 applies a protective film p to the wafer W on the spin coating stage 11 or spin coating stage 12 via spin coating. It should be noted that this wafer W is a sample used as a reference for determining the threshold distribution; therefore, a wafer W with a normal protective film p is used. After the protective film p is formed, the wafer W is moved back to the processing stage 32 and positioned. At this time, the control unit 400 stores the pattern and coordinate information of the device layer on the wafer W, 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 stage 32 after the pre-measurement 1, the coordinate information before removal can still be used as is.

[0165] Next, the aforementioned preliminary measurement 2 was performed.

[0166] In this preliminary measurement 2, the fluorescence intensity after the protective film was applied was measured at various locations along the surface of the protective film p using the same measurement method as in preliminary measurement 1 (second preliminary fluorescence intensity measurement). Here, refer to... Figure 3The fluorescence measured at this time will be explained in advance. First, if the absorber ab is irradiated with ultraviolet light (UV), fluorescence is emitted isotropically from the absorber ab in 360°. This fluorescence propagates along any of the following three paths: (i) light directly reaching detector 61; (ii) light reflected from the device layer and reaching detector 61; and (iii) light emitted in a direction that does not reach detector 61. Among these, since there is "(ii) light reflected from the device layer and reaching detector 61", the intensity of fluorescence received by detector 61 will be affected by the difference in the reflectivity of the device layer. Furthermore, detector 61 also receives the fluorescence of the device layer measured in the aforementioned preliminary measurement 1. In summary, the fluorescence received by detector 61 includes the following three: "(i) light directly reaching detector 61"; "(ii) light reflected from the device layer and reaching detector 61"; and the fluorescence of the device layer. As a sum of these three types of light, Figure 3 The fluorescence intensity, illustrated by the thick solid line, is measured as a second pre-determined data serving as the upper limit threshold. 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. Furthermore, the fluorescence intensity component generated by the device layer is represented by P, and the fluorescence intensity component of the protective film p, which includes the influence of the device layer's reflectivity, is represented by Q.

[0167] Next, the aforementioned thresholds are determined.

[0168] In determining this threshold, fluorescence in the device layer is removed based on the first pre-measurement data obtained in the aforementioned pre-measurement 1, and further, the influence of reflected fluorescence in the device layer is removed based on the second pre-measurement data obtained in the aforementioned pre-measurement 2. Specifically, as... Figure 3As shown, the control unit 400 sets a threshold value for each of positions A, B, C, and D at each of these positions, such that these threshold values ​​fall between the first pre-measurement data obtained in pre-measurement 1 and the second pre-measurement data obtained in pre-measurement 2. For example, at position A, a threshold value a is calculated and determined such that it falls between the fluorescence intensity a1 obtained in pre-measurement 1 and the fluorescence intensity a2 obtained in pre-measurement 2 (e.g., median). Similarly, at position B, a threshold value b is calculated and determined such that it falls between the fluorescence intensity b1 obtained in pre-measurement 1 and the fluorescence intensity b2 obtained in pre-measurement 2 (e.g., median). Furthermore, at position C, a threshold value c is calculated and determined such that it falls between the fluorescence intensity c1 obtained in pre-measurement 1 and the fluorescence intensity c2 obtained in pre-measurement 2 (e.g., median). Finally, at position D, a threshold value d is calculated and determined such that it falls between the fluorescence intensity d1 obtained in pre-measurement 1 and the fluorescence intensity d2 obtained in pre-measurement 2 (e.g., median). Based on the above operations, threshold distribution data with thresholds suitable for positions A, B, C, and D can be obtained.

[0169] Following the threshold distribution fabrication process described above, a comparison process is performed.

[0170] In this comparison process, fluorescence intensity data after the protective film is coated is obtained. This fluorescence intensity data is obtained by irradiating an excitation light onto a wafer W positioned on a processing stage 32 while a protective film p containing the light-absorbing agent ab is formed. Furthermore, the coating state of the protective film p is determined by comparing this fluorescence intensity data after the protective film is coated with the aforementioned threshold distribution data.

[0171] If the same uniform threshold is used for all locations A, B, C, and D, misjudgments may occur. However, in this embodiment, threshold distribution data is provided, which has thresholds a, b, c, and d suitable for each location A, B, C, and D, and this threshold distribution data is associated with high-precision location information. Therefore, high-precision protective film determination that is less prone to misjudgments can be performed.

[0172] [Second Implementation]

[0173] Next, refer to the following. Figure 4 and Figure 5 The second embodiment of the present invention will now be described. It should be noted that the following description focuses on the differences from the first embodiment described above; other parts are the same as the apparatus and method of the first embodiment, and therefore, repetition of those descriptions is omitted. Figure 4This diagram illustrates the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus according to this embodiment. Here, (A) shows a method of comparing film thicknesses between the photomask exposure areas; (B) shows a method of comparing the film thickness of a reference chip located near the wafer center with the film thickness of the inspection target chip located around it; and (C) shows a method of comparing the film thicknesses of the inspection target chips located at equal distances from the wafer center. Furthermore, Figure 5 This diagram illustrates how film thickness is compared using images obtained by photographing the same pattern position in this embodiment. (A) shows the comparison of images obtained by photographing the same inspection position; (B) shows the comparison of images obtained by photographing the same inspection position using position information.

[0174] In the first embodiment described above, the thickness of the protective film p was determined by comparing it with a threshold distribution. In contrast, in this embodiment, the thickness of the protective film p is determined by comparing the fluorescence intensity between different locations on the wafer W after the protective film p is formed. It should be noted that the following comparisons and determinations are all performed by the control unit 400.

[0175] First of all, Figure 4 In (A), the portions of the device layer with identical patterns are compared with each other. That is, for Figure 4 For each of the ranges R1, R2, R3, and R4 in (A), assuming the device layer pattern is identical, the fluorescence intensity distribution measured at each location within these four ranges is compared with each other. This eliminates fluorescence intensity deviations caused by differences in the formed pattern of the device layer. Furthermore, if the protective film p has a normal thickness, the fluorescence intensity distribution across all ranges is approximately the same; however, if there are localized anomalies in the film thickness, the fluorescence intensity in that region will be higher or lower than in other ranges.

[0176] On the other hand, Figure 4 In (B), the chip located at the center of the circular surface of the device layer is designated as the reference chip Pr, and the fluorescence intensity distribution corresponding to the film thickness measured at the reference chip Pr is set as appropriate (acceptance standard). Based on this, the measurement results at the inspection target chip Pe located around the reference chip Pr are judged. That is, when a protective film p is formed by coating through a coating process such as spin coating, the center of the device layer tends to be less prone to coating defects; therefore, the fluorescence intensity distribution of the reference chip Pr located at this center is used as a reference value.

[0177] Furthermore, in Figure 4In (C), a concentric circle is defined around the center CL on the circular surface of the device layer, and the fluorescence intensity distribution of multiple inspection target chips Pe within this circle is compared with each other. That is, when a protective film p is formed by coating or other methods, the film thickness tends to be the same within the concentric circle around the center CL. Therefore, the thickness of the protective film p is determined to be good based on whether there is a deviation in fluorescence intensity.

[0178] It should be noted that, in Figure 4 (A) ~ Figure 4 In comparisons of (C), for example, in such cases... Figure 5 As shown on the left and right sides of the paper in (A), when comparing images of the same position of the chip Pe being inspected, no special additional steps are required. However, generally, as Figure 5 As shown in (B), the position of the object location chip Pe may sometimes be slightly offset between captured images. In this case, it is preferable to compare the images after performing an image adjustment process that establishes a correspondence between the relative positions of the images so that the position information associated with each of the two images is consistent.

[0179] Furthermore, when inspecting multiple wafers W with the same pattern, the device layer patterns of each wafer W are completely identical, and the position information of each chip during positioning on the processing stage 32 is also completely identical. Therefore, when performing protective film inspection on the position of the chip Pe at the inspection target location, the position of another chip located on the same wafer W can be selected, or the position of another chip on another wafer W can be selected. It should be noted that, in this embodiment, since the wafers W after the protective film has been formed are compared with each other, the aforementioned preliminary measurement 1 is not performed, but only the aforementioned preliminary measurement 2 is performed for comparison. On the other hand, when selecting the position of another chip located on the same wafer W (i.e., when comparing the comparison targets within the same individual), neither preliminary measurement 1 nor preliminary measurement 2 is required.

[0180] [Third Implementation Method]

[0181] Next, refer to the following. Figure 6 and Figure 7 The third embodiment of the present invention will be described.

[0182] Figure 6 This diagram illustrates the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus of this embodiment. (A) shows the case where film thickness determination is excluded for locations remote from the dicing track st on the wafer; (B) shows the case where film thickness determination is excluded for locations with defects located at the outer periphery of the wafer. Furthermore, Figure 7 This is a flowchart illustrating the various steps involved in the protective film inspection in this embodiment.

[0183] It should be noted that this embodiment is an embodiment that can be appropriately combined with the first embodiment and the second embodiment described above. Therefore, the description focuses on the additional points and differences relative to the first embodiment and the second embodiment described above. Other parts are the same as the apparatus and method of the first embodiment or the second embodiment described above, so repeated descriptions are omitted.

[0184] In this embodiment, processing capability can be improved by preventing inappropriate or flawed judgments contained in the judgment content.

[0185] The specific explanation is as follows. Figure 6 In the case shown in (A), if the thickness of the protective film p at the central position of the chip Pe being inspected exceeds the specified range, conventionally, it would be determined that the protective film p has a defective part df, thus requiring recoating. However, in this embodiment, as described in the first embodiment above, the pattern of the device layer formed on the wafer W is associated with its position information with high precision. Therefore, if debris is attached to the location where the defective part df occurs, it can be determined whether it affects the chip Pe being inspected. Therefore, if the defective part df only exists in a location that will not cause any impact (a location that does not produce processing defects), it can not be determined as a defect in the protective film p and can be returned to the processing step. In this case, improper defect determination can be avoided, thus eliminating the need for unnecessary rework such as recoating, thereby significantly improving processing capacity. Referring again... Figure 6 In (A), the defective area df is located in the center of the inspected chip Pe, and is at the furthest point inward from the dicing track st formed between adjacent chips. The problem arises when debris adheres to or near the dicing track st. Figure 6 (A) does not fall under any of these cases. Therefore, even if, for example, the thickness of the protective film p is defective at the defective location df, and debris adheres to that location, no problem will arise. Therefore, although the figure shows Pe, from the viewpoint of improving processing capacity, it is preferable to implement an exclusion process that removes it from the inspection target.

[0186] Figure 6 The same applies to case (B). Figure 6(B) shows the outer peripheral edge of wafer W, with the arc above the paper representing the outer peripheral edge of wafer W. At this outer peripheral edge, there exists a defective chip that cannot be used as a product. Here, if there is a thickness defect in the protective film p at the location indicated by reference numeral df in this figure, conventionally, it would be determined that the formation location of the defective area df overlaps with the dicing path st, and the chip would be returned for recoating. However, in this embodiment, as described in the first embodiment above, the pattern of the device layer formed on wafer W and its position information are associated with high precision. Therefore, the position information of the defective chip is also accurately determined, so even if there is a defective area df on the defective chip, it can be excluded from the determination process, thus preventing it from being judged as a defect in the protective film p and returning it for processing. In this case, improper defect determination can be avoided, thus eliminating unnecessary rework such as recoating, thereby significantly improving processing capacity.

[0187] Regarding the inspection of the protective film in this embodiment, such as Figure 7 As shown, in step ST1, the wafer W with the protective film p is first positioned on the processing stage 32.

[0188] Next, in step ST2, the positioned wafer W is irradiated with ultraviolet light, and the fluorescence intensity is measured to obtain the film thickness distribution.

[0189] Next, in step ST3, it is determined whether there is a coating defect of the protective film p. If not, the process proceeds to step ST6, where the wafer W is determined to be good and is supplied for processing.

[0190] On the other hand, if a coating defect is determined in step ST3, the process returns to step ST4.

[0191] In step ST4, it is determined whether the location of the coating defect affects the manufacturing defect. That is, for example, in... Figure 6 In cases where a defective part df occurs at a location far from the cutting path st, as shown in (A), it is excluded from the defect determination. Additionally, in cases such as... Figure 6 In cases where a defective chip location as shown in (B) results in a defective part df, it is also excluded from the defect determination. Taking these exclusions into account, if it is determined that the defect will not affect manufacturing, proceed to step ST6, determine it as a good product, and supply the wafer W for processing.

[0192] On the other hand, if a coating defect is determined in step ST4, the process returns to step ST5 and the wafer is determined to be defective. After cleaning and rinsing off the protective film p, the defective wafer W is recoated with the protective film p. The wafer W, after this recoating, undergoes another inspection starting from step ST1.

[0193] [Fourth Implementation Method]

[0194] Next, refer to the following. Figure 8 and Figure 9 The fourth embodiment of the present invention will be described.

[0195] Figure 8 This diagram illustrates the protective film inspection method performed by the protective film inspection mechanism of the laser processing apparatus according to this embodiment. It is an explanatory diagram showing the method of inspecting only the dicing path st of the wafer W and its surrounding area. Furthermore, Figure 9 This is a flowchart illustrating the various steps involved in the protective film inspection in this embodiment.

[0196] It should be noted that this embodiment is an embodiment that can be appropriately combined with the first and second embodiments described above. Therefore, the description focuses on the additional points and differences relative to the first and second embodiments described above, while other parts are the same as the apparatus and method of the first or second embodiments described above, and therefore, repeated descriptions are omitted.

[0197] In the third embodiment described above, improper defect determinations were eliminated when improving processing capacity. In contrast, in this embodiment, the parts that affect manufacturing defects are identified as inspection locations, and only these inspection locations are inspected.

[0198] For example, in Figure 8 If debris adheres to the cutting slit (ST) and the surrounding area adjacent to both sides of ST, it will affect manufacturing defects. Therefore, the presence of coating defects is determined only for this area. On the other hand, areas outside the cutting slit (ST) and the surrounding area adjacent to both sides of ST are excluded from inspection. As a result, processing capacity can be greatly improved.

[0199] Regarding the inspection of the protective film in this embodiment, such as Figure 9 As shown, in step ST1A, the wafer W with the protective film p is first positioned on the processing stage 32.

[0200] Next, in step ST2A, the inspection location is determined. That is, the cutting track st and the surrounding area adjacent to both sides of the cutting track st are set as the inspection location.

[0201] Next, in step ST3A, ultraviolet light is irradiated onto the wafer W at the locations determined in step ST2A, and the fluorescence intensity is measured to determine the film thickness distribution. On the other hand, areas excluded in step ST2A are excluded from the inspection.

[0202] Next, in step ST4A, it is determined whether there is a coating defect of the protective film p. If there is no coating defect, the process proceeds to step ST6A, where the wafer W is determined to be good and is ready for processing.

[0203] On the other hand, if a coating defect is determined in step ST4A, the process returns to step ST5A and the wafer is determined to be defective. The wafer W determined to be defective is cleaned and the protective film p is rinsed off, and then the protective film p is recoated. The wafer W that has undergone this recoating process is then subjected to a re-inspection starting from step ST1A.

[0204] It should be noted that, as an example, the following is an embodiment to which this implementation method applies.

[0205] In this embodiment, the following conditions are set as the measurement conditions:

[0206] Wafer W dimensions: φ300mm;

[0207] Chip size: 12mm × 12mm;

[0208] Number of cutting grooves: 24 longitudinal grooves × 24 transverse grooves;

[0209] Field of view during inspection: 4mm ( Figure 10 (The field of view width is set to w = 4mm).

[0210] Scanning methods: Two methods were used, namely scanning the entire surface (comparative example), and scanning the entire surface as well as... Figure 10 The case shown is a linear scan along the cutting path (invention example).

[0211] Under the aforementioned measurement conditions, the number of scans in the comparative example was 75, while in the inventive example, the inspection was completed in 48 scans (24 scans along the longitudinal cutting path + 24 scans along the transverse cutting path). This result confirms that the number of scans can be reduced by 36%. Thus, according to this embodiment, the number of scans can be significantly reduced, thereby confirming a further substantial improvement in processing capacity.

[0212] It should be noted that in the above embodiments, as Figure 11 As shown in (A), a margin of 4mm is left for the field of view width w. In contrast, as... Figure 11 As shown in (B), by setting the measurement range to 1 mm on both sides of the centerline of the cutting path st, thus reducing the field of view to w = 2 mm, a more precise measurement can be performed due to the narrower field of view. As a result, the measurement resolution is improved, thus achieving both improved processing power and improved measurement accuracy.

[0213] The various embodiments of the present invention have been described above, but the embodiments can be appropriately combined as needed. In particular, when the first or second embodiment described above is combined with the third or fourth embodiment described above, in addition to enabling high-precision determination of coating defects, the processing capacity can also be improved.

[0214] Industrial availability

[0215] Based on this laser processing device and method, processing can be performed using more precise coating defect judgment. Therefore, it has significant industrial applicability.

[0216] Explanation of reference numerals in the attached figures

[0217] 10 Loading side base

[0218] 11 Spin Coating Workbench

[0219] 12 Spin Coating Workbench

[0220] 30 Machining side base

[0221] 31 Positioning Mechanism

[0222] 31a Axial Direction Positioning Part

[0223] 31b Axial Direction Positioning Part

[0224] 31c Axis Angle Adjustment Mechanism

[0225] 32. Machining workbench

[0226] 50 irradiation department

[0227] 51 Light Source

[0228] 52 Lenses

[0229] 53 Filter

[0230] 60 Testing Department

[0231] 61 detectors

[0232] 62 Lenses

[0233] 63 Filter

[0234] 100 Protective film forming apparatus (coating mechanism)

[0235] 200 processing equipment

[0236] 300 Protective Film Inspection Device (Protective Film Inspection Mechanism)

[0237] 31a0 Y-axis moving base

[0238] 31b0 X-axis moving base

[0239] 31a1 guide rail

[0240] 31b1 guide rail

[0241] 31a2 ball screw

[0242] 31a3 servo motor

[0243] 31b3 Linear Motor

[0244] 400 Control Department

[0245] CL Center (Central Location)

[0246] Pe checks the location of the chip

[0247] Pr reference position chip

[0248] UV light

[0249] W: Wafer (workpiece)

[0250] w Field of view

Claims

1. A laser processing apparatus, characterized in that, include: A protective film inspection agency determines the coating condition of the protective film applied to the workpiece. as well as The positioning mechanism places and positions the workpiece on the processing table during laser processing. After the positioning mechanism positions the workpiece on the processing table, the protective film inspection mechanism determines the coating status of the protective film.

2. The laser processing apparatus according to claim 1, characterized in that, The protective film inspection mechanism is equipped with: The irradiation section irradiates the protective film with excitation light; The detection unit detects the fluorescence emitted by the protective film; and The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit. The control unit has threshold distribution data, which is obtained by setting a threshold for each position on the workpiece based on a first pre-measured fluorescence intensity. The first pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table without the protective film, with the excitation light. The control unit is configured to determine the coating state by comparing fluorescence intensity data after coating the protective film with the threshold distribution data. The fluorescence intensity data after coating the protective film is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

3. The laser processing apparatus according to claim 1, characterized in that, The protective film inspection mechanism is equipped with: The irradiation section irradiates the protective film with excitation light; The detection unit detects the fluorescence emitted by the protective film; and The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit. The control unit has threshold distribution data, which is obtained by setting a threshold for each position on the workpiece based on a second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, which is positioned on the processing table with the protective film coated, with the excitation light. The control unit is configured to determine the coating state by comparing fluorescence intensity data after coating the protective film with the threshold distribution data. The fluorescence intensity data after coating the protective film is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

4. The laser processing apparatus according to claim 1, characterized in that, The protective film inspection mechanism is equipped with: The irradiation section irradiates the protective film with excitation light; The detection unit detects the fluorescence emitted by the protective film; and The control unit determines the coating state by obtaining the fluorescence intensity distribution based on the detection results from the detection unit. The control unit has: The first pre-measured data is a lower limit threshold set for each position on the workpiece based on the first pre-measured fluorescence intensity, which is obtained by irradiating the workpiece, which is positioned on the processing table without the protective film, with the excitation light. as well as The second pre-measured data is an upper limit threshold set for each location on the workpiece based on the second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, which is positioned on the processing table with the protective film coated, with the excitation light. The control unit is configured to: Calculate the threshold distribution data set between the first pre-measured data and the second pre-measured data, and The coating state is determined by comparing the fluorescence intensity data after the protective film is applied with the threshold distribution data. The fluorescence intensity data after the protective film is applied is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

5. The laser processing apparatus according to claim 1, characterized in that, The workpiece has multiple identical photomask exposure areas with the same pattern as each other. The positioning mechanism is configured to obtain the position information of each of the identical photomask exposure areas. The protective film inspection mechanism is configured to determine the coating state by comparing the coating state at the respective positions of the same photomask exposure areas that are associated with each other using the location information.

6. The laser processing apparatus according to claim 1, characterized in that, The workpiece has a reference position chip disposed at the center of the workpiece and inspection object position chips disposed around the reference position chip. The positioning mechanism is configured to acquire the position information of the reference position chip and the inspection object position chip, respectively. The protective film inspection mechanism is configured as follows: The coating state of the protective film at the location of the reference chip is set as a qualified benchmark, and The coating state is determined by comparing the coating state of the protective film at the location of the chip being inspected with the pass / fail benchmark.

7. The laser processing apparatus according to claim 1, characterized in that, It also includes a coating mechanism that applies the protective film to the workpiece via spin coating. The workpiece has multiple chips for checking the location of the target object. The positioning mechanism is configured to obtain the position information of each of the inspection object's position chips. The protective film inspection mechanism is configured to determine the coating state by comparing the coating state between the positions of the inspection object position chips, which have position information located in concentric circles from the center position of the workpiece.

8. The laser processing apparatus according to any one of claims 5 to 7, characterized in that, The protective film inspection mechanism is configured to ensure that the relative positions of the images being compared are consistent, based on position information obtained from the positioning mechanism, before comparing the coating states.

9. The laser processing apparatus according to any one of claims 1 to 7, characterized in that, The protective film inspection mechanism is configured to exclude parts of the workpiece that are unrelated to whether there are defects after laser processing from the determination of the coating state.

10. A laser processing method, characterized in that, include: The positioning process involves placing and positioning the workpiece before laser processing on the processing worktable. as well as In the determination process, after the positioning process, the coating state of the protective film applied to the workpiece positioned on the processing table is measured to determine the coating state of the protective film.

11. The laser processing method according to claim 10, characterized in that, The determination process includes: The threshold distribution fabrication process involves generating threshold distribution data for each location on the workpiece by setting a threshold based on a first pre-measured fluorescence intensity. The first pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table without the protective film, with excitation light. The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

12. The laser processing method according to claim 10, characterized in that, The determination process includes: The threshold distribution fabrication process involves generating threshold distribution data for each location on the workpiece by setting a threshold based on a second pre-measured fluorescence intensity. The second pre-measured fluorescence intensity is obtained by irradiating the workpiece, positioned on the processing table with the protective film coated, with excitation light. The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

13. The laser processing method according to claim 10, characterized in that, The determination process includes: The threshold distribution fabrication process involves calculating the threshold distribution data formed between the first pre-measured data and the second pre-measured data, wherein... The first pre-measured data is a lower limit threshold set for each position on the workpiece based on the first pre-measured fluorescence intensity. The first pre-measured fluorescence intensity is obtained by irradiating the workpiece, which is positioned on the processing table without the protective film, with excitation light. The second pre-measured data is an upper limit threshold set for each location on the workpiece based on a second pre-measured fluorescence intensity, the second pre-measured fluorescence intensity being obtained by irradiating the workpiece, positioned on the processing table with the protective film coated, with the excitation light; and The comparison process determines the coating state by comparing the fluorescence intensity data after the protective film is coated with the threshold distribution data. The fluorescence intensity data after the protective film is coated is obtained by irradiating the workpiece positioned on the processing table with excitation light while the protective film containing the light absorber is formed.

14. The laser processing method according to claim 10, characterized in that, The workpiece has multiple identical photomask exposure areas with the same pattern as each other. In the positioning process, the position information of each of the identical photomask exposure areas is obtained. In the determination process, the coating state of the protective film is determined by comparing the coating states at the respective positions of the same photomask exposure areas that are associated with each other using the position information.

15. The laser processing method according to claim 10, characterized in that, The workpiece has a reference position chip disposed at the center of the workpiece and inspection object position chips disposed around the reference position chip. In the positioning process, the position information of the reference position chip and the inspection object position chip is obtained respectively. In the determination process, The coating state of the protective film at the location of the reference chip is set as a qualified benchmark, and The coating state is determined by comparing the coating state of the protective film at the location of the chip being inspected with the pass / fail benchmark.

16. The laser processing method according to claim 10, characterized in that, Prior to the positioning process, a coating process is also included, in which the protective film is applied to the workpiece having multiple inspection target position chips by spin coating. In the positioning process, the position information of each of the inspection object position chips of the workpiece is obtained. In the determination process, the coating state is determined by comparing the coating state between the positions of the inspection target position chips located in concentric circles from the center position of the workpiece.

17. The laser processing method according to any one of claims 14 to 16, characterized in that, The determination process includes: The photographic process acquires images of each inspection location of the workpiece; and In the image adjustment process, before comparing the coating states, the relative positions of the images being compared are made consistent based on the position information obtained in the positioning process.

18. The laser processing method according to any one of claims 10 to 16, characterized in that, The determination process includes an exclusion process, in which parts of the workpiece that are unrelated to whether there are defects after laser processing are excluded from the determination of the coating state.

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