JP7805806B2 - Processing method of workpiece - Google Patents

Description

The present invention relates to a method for processing a workpiece.

Workpieces such as wafers with multiple imaging devices or optical devices formed on them are divided into individual devices using a processing device, and the divided devices are widely used in various electrical equipment, etc. A known processing device used here is a laser processing device that irradiates the workpiece with a laser beam of an absorbent wavelength to ablate it (see, for example, Patent Document 1).

When processing using this type of laser beam irradiation, debris (processing chips) is generated when the workpiece is ablated, and this debris may re-adhere to the workpiece and adversely affect the device's characteristics. To prevent this, a method has been proposed in which a protective film is applied to the workpiece before ablation processing, and then the workpiece is washed after processing to wash away any debris adhering to the protective film (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2003-320466 Japanese Patent Application Laid-Open No. 2004-188475

However, these imaging devices and optical devices are generally highly water-repellent, meaning that many have a contact angle of 60 degrees or more with pure water, which creates the problem that the protective film is repelled by the surface of the workpiece, making it impossible to apply it evenly.

The present invention was made in consideration of these problems, and its purpose is to provide a method for processing a workpiece that can prevent poor device characteristics by uniformly applying a protective film to a water-repellent workpiece.

In order to solve the above-mentioned problems and achieve the object, the method for processing a workpiece of the present invention is a method for processing a workpiece having a water-repellent surface, and is characterized by having a coating step in which one side of the workpiece is coated with fine particles of a material that is not water-repellent and the fine particles form irregularities on the one side of the workpiece; a protective film forming step in which a water-soluble liquid resin is applied to the one side coated with the fine particles to form a protective film that protects the workpiece; and a laser beam irradiation step in which a laser beam of a wavelength that is absorbable by the workpiece is irradiated from the side of the workpiece on which the protective film has been formed, thereby processing the workpiece.

In the coating step, the workpiece may be rotated while the fine particles are sprayed from a nozzle at the tip of a nozzle of a fine particle coating unit toward the one side of the workpiece located vertically below, thereby coating the one side of the workpiece with the fine particles. In the coating step, the workpiece and the fine particle coating unit may be moved horizontally relative to each other while the fine particles are sprayed from multiple nozzles of the fine particle coating unit toward the one side of the workpiece located vertically below, thereby coating the one side of the workpiece with the fine particles. In the coating step, the fine particles may be sprayed into a chamber to create a state in which the fine particles are suspended, and the workpiece may be placed in the chamber where the fine particles are suspended and left there for a certain period of time, thereby coating the one side of the workpiece with the fine particles. After coating the one side of the workpiece with the fine particles in the coating step, areas where excess fine particles have accumulated may be confirmed and inspected, and the excess fine particles may be removed.

The particle diameter of the fine particles may be 100 nm or more and 30 μm or less. In the coating step, the fine particles may be set to cover 40% or more of one surface of the workpiece.

After the laser beam irradiation step, the method may further include a cleaning step of cleaning the one surface of the workpiece to remove the protective film.

The workpiece may contain silicone resin.

The present invention prevents poor device characteristics by uniformly applying a protective film to a water-repellent workpiece.

FIG. 1 is a flowchart showing a processing procedure of a method for processing a workpiece according to an embodiment. FIG. 2 is a perspective view showing an example of the coating step of FIG. FIG. 3 is a cross-sectional view showing an example of a fine particle supply unit that supplies fine particles to be coated in the coating step of FIG. FIG. 4 is a perspective view showing another example of the coating step of FIG. FIG. 5 is a cross-sectional view showing another example of the coating step of FIG. FIG. 6 is a perspective view showing an example of the protective film forming step of FIG. FIG. 7 is a cross-sectional view illustrating the coverage area ratio of the fine particles coated in the coating step of FIG. FIG. 8 is a top view illustrating the coverage area ratio of the particles coated in the coating step of FIG. FIG. 9 is a graph illustrating the relationship between the radius of the particles coated in the coating step of FIG. 1 and the coverage area ratio of the particles. FIG. 10 is a cross-sectional view showing an example of the laser beam irradiation step of FIG. FIG. 11 is a cross-sectional view showing an example of the cleaning step of FIG. FIG. 12 is a diagram illustrating the effects of the method for processing a workpiece according to the embodiment.

Modes for carrying out the present invention (embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that would be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications to the configuration can be made without departing from the spirit of the present invention.

[Embodiment]
A method for processing a workpiece according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a flowchart showing the processing procedure of the method for processing a workpiece according to the embodiment. The method for processing a workpiece according to the embodiment is a method for processing a workpiece 1 having a water-repellent surface on one side thereof, as shown in Figs. 2 and 4 (to be described later), by irradiating the workpiece 1 with a laser beam 63 (see Fig. 10). As shown in Fig. 1, the method includes a coating step 1001, a protective film forming step 1002, a laser beam irradiation step 1003, and a cleaning step 1004.

Figure 2 is a perspective view showing an example of the coating step 1001 in Figure 1. Figure 3 is a cross-sectional view showing an example of a particle supply unit 30 that supplies the particles 100 to be coated in the coating step 1001 in Figure 1. Figure 4 is a perspective view showing another example of the coating step 1001 in Figure 1. Figure 5 is a cross-sectional view showing another example of the coating step 1001 in Figure 1. As shown in Figures 2, 4, and 5, the coating step 1001 is a step in which one water-repellent surface of the workpiece 1 is coated with particles 100 (see Figure 3).

In this embodiment, the workpiece 1, which is the target of processing in the workpiece processing method, is, for example, a disk-shaped imaging device wafer or optical device wafer made of silicon, sapphire, silicon carbide (SiC), gallium arsenide, or the like, as shown in FIG. 2. In the present invention, the workpiece 1 is not limited to the disk shape shown in FIG. 2, and may be a rectangular plate shape as shown in FIG. 3, or another plate shape.

In this embodiment, the workpiece 1 has a flat surface 2, with chip-like devices 4 (see FIG. 10) formed in each region defined by a plurality of intersecting (orthogonal in this embodiment) planned division lines 3 (see FIG. 10). If the workpiece 1 is an imaging device wafer, the devices 4 are image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors), and if the workpiece 1 is an optical device wafer, they are optical devices. The workpiece 1 has a device region where the devices 4 are formed and a peripheral excess region where no devices 4 are formed and surrounds the device region, with through-holes formed in the peripheral excess region that penetrate the thickness, allowing alignment.

In this embodiment, the workpiece 1 has a water-repellent surface 2, and the steps of the workpiece processing method (1001-1004) are performed on the surface 2 side. However, the present invention is not limited to this. The back surface 5, opposite the surface 2, may also have water-repellent properties, and the steps of the workpiece processing method may be performed on the back surface 5 side. In this specification, water-repellent refers to the property of having a contact angle with pure water of 60 degrees or more, thereby repelling the liquid resin 200 (see Figure 6) supplied in the protective film formation step 1002.

In this embodiment, the water-repellent surface 2 of the workpiece 1 is provided with a resin layer 8 that protects the device 4. The water-repellent properties of the surface 2 are imparted by the resin layer 8. The resin layer 8 is formed to contain a silicone resin. Specifically, the resin layer 8 is a silicone resin film formed from a silicone resin, or a silicone-mixed resin film formed from a mixed resin in which another resin, such as an epoxy resin, is added to a silicone resin. Note that in the present invention, the surface 2 is not limited to a form in which the water-repellent properties are imparted by the resin layer 8, and any form that is water-repellent is acceptable.

Furthermore, as shown in FIG. 4, the workpiece 1 may have adhesive tape 6 attached to one side (front side 2 in the example shown in FIG. 4) opposite to the other side (back side 5 in the example shown in FIG. 4) on which each step of the workpiece processing method is carried out, and an annular frame 7 attached to the outer edge of the adhesive tape 6, or as shown in FIG. 2, neither adhesive tape 6 nor annular frame 7 may be attached, but the present invention is not limited to this, and the other side may have adhesive tape 6 attached but no annular frame 7 attached.

As shown in FIG. 2, the particle-coating apparatus 10-1, which is an example of a particle-coating unit that performs the coating step 1001, includes a holding table 20-1, a particle supply unit 30, and a particle-coating unit 40-1. The holding table 20-1 holds the workpiece 1 from the other side of the workpiece 1. In this embodiment, the holding table 20-1 is a so-called chuck table having, for example, a disk-shaped frame with a recess formed therein and a disk-shaped suction portion fitted into the recess. Negative pressure is applied from a suction source (not shown) connected to the suction portion to the upper surface of the suction portion, which is formed parallel to the horizontal plane, thereby suction-holding the workpiece 1, placed on the upper surface of the suction portion with its other side facing downward, from the upper surface of the suction portion. The holding table 20-1 is rotatable about an axis perpendicular to the upper surface of the suction portion and parallel to the vertical direction by a rotary drive source (not shown), as indicated by arrow 21 in FIG. 2. The microparticle coating unit 40-1 is a nozzle whose base end is connected to the microparticle supply unit 30. The microparticles 100 supplied from the microparticle supply unit 30 are sprayed from the injection hole at the tip toward one side of the workpiece 1 held on the holding table 20-1, which is located vertically below.

As shown in FIG. 3, the particle supply unit 30 includes a sealed container 31, an air supply source 32, an on-off valve 33, a filter 34, an air supply pipe 35, and a particle supply pipe 36. The sealed container 31 is, for example, a tank or a bottle. Particles 100 are placed inside the sealed container 31. One end of the air supply pipe 35 and one end of the particle supply pipe 36 are inserted into two openings formed at the top of the sealed container 31. The air supply pipe 35 is inserted deeper into the sealed container 31 than the particle supply pipe 36.

The other end of the air supply pipe 35 is connected to the air supply source 32, which is in communication with the inside of the sealed container 31 via the air supply pipe 35. The on-off valve 33 is provided midway along the air supply pipe 35. When opened, the on-off valve 33 opens the communication passage within the air supply pipe 35, allowing air from the air supply source 32 to pass through the air supply pipe 35 and enter the sealed container 31. When closed, the on-off valve 33 closes the communication passage within the air supply pipe 35, stopping the introduction of air from the air supply source 32 into the sealed container 31.

The other end of the particle supply pipe 36 is connected to the base end of the particle coating unit 40-1, and the particle supply pipe 36 connects the inside of the particle coating unit 40-1 to the inside of the sealed container 31. The filter 34 is provided midway along the particle supply pipe 36. The filter 34 allows particles 100 of a predetermined particle size to pass through. The filter 34 has pores of a predetermined diameter, for example, and prevents the passage of particles 100 with a particle size exceeding the predetermined diameter.

The microparticle supply unit 30 opens the on-off valve 33 to introduce air from the air supply source 32 into the sealed container 31. The microparticles 100 stirred up by the air introduced into the sealed container 31 are introduced into the microparticle supply pipe 36, and the filter 34 prevents microparticles with a diameter exceeding a predetermined size from passing through. The microparticles 100 of the predetermined diameter that pass through the filter 34 are supplied to the microparticle coating unit 40-1.

In this embodiment, the particles 100 supplied by the particle supply unit 30 and coated on one side of the workpiece 1 are preferably particles made of a material that is not water-repellent, such as calcium carbonate (CaCO ₃ ) or carbon (C) particles.

The particle size of the microparticles 100 supplied by the microparticle supply unit 30 and coated on one side of the workpiece 1 is narrowed to a predetermined size by restricting the particle size of the microparticles 100 enclosed in the sealed container 31 and further restricting the particle size of the microparticles 100 using the filter 34. In this embodiment, the particle size (predetermined particle size) of the microparticles 100 is preferably between 100 nm and 30 μm. This eliminates the need for a filter with an excessively fine mesh, which increases manufacturing costs. This significantly reduces the cost of the filter 34 that narrows the particle size of the microparticles 100. Furthermore, the particle size of the microparticles 100 is not so large that the liquid resin 200 cannot be applied to the area coated with the microparticles 100. Therefore, the unevenness formed by the microparticles 100 does not prevent the liquid resin 200 from being applied in the protective film formation step 1002 described below. The particle size of the microparticles 100 can be expressed using known methods, such as geometric diameter and equivalent diameter. Geometric diameters include the Feret diameter, maximum diameter in a specific direction (i.e., Krummbein diameter), Martin diameter, and sieve diameter, while equivalent diameters include the diameter equivalent to a circle with a projected area (i.e., Heywood diameter), the diameter equivalent to a sphere with an equal surface area, the diameter equivalent to a sphere with an equal volume, the Stokes diameter, and the light scattering diameter.

In a first example of coating step 1001, coating step 1001 is performed using particle coating device 10-1. In the first example of coating step 1001, as shown in FIG. 2, workpiece 1 is held on holding table 20-1 with one water-repellent side facing upward, and while holding table 20-1 is rotated to rotate workpiece 1, particle coating unit 40-1 sprays particle 100 supplied from particle supply unit 30 toward one side of workpiece 1 on holding table 20-1, thereby coating one side of workpiece 1 evenly with particle 100.

As shown in FIG. 4, the particle coating apparatus 10-2, which is another example of a particle coating unit that performs the coating step 1001, includes a holding table 20-2, a particle supply unit 30, and a particle coating unit 40-2. Unlike the previously described holding table 20-1, which is rotatable, the holding table 20-2 is modified so that it is movable in a direction parallel to the upper surface of the suction unit by a drive source (not shown), as indicated by arrow 22 in FIG. 4. The particle coating unit 40-2 replaces the single injection hole for injecting particles 100 in the particle coating unit 40-1 with multiple injection holes arranged at equal intervals in a straight line parallel to the horizontal plane and perpendicular to the direction of movement of the holding table 20-2, over a length greater than the width of the workpiece 1.

In a second example of the coating step 1001, the coating step 1001 is performed by the particle coating device 10-2. In the second example of the coating step 1001, as shown in FIG. 4, the workpiece 1 is held by the holding table 20-2 with one water-repellent surface facing upward, and while the holding table 20-2 is moved horizontally to move the workpiece 1 horizontally, particles 100 supplied from the particle supply unit 30 by the particle coating unit 40-2 are sprayed toward one surface of the workpiece 1 on the holding table 20-2, thereby coating the one surface of the workpiece 1 evenly with the particles 100. Note that in the second example of the coating step 1001, since it is only necessary for the particle coating unit 40-2 to move relative to the holding table 20-2, instead of fixing the particle coating unit 40-2 and moving the holding table 20-2 horizontally, the particle coating unit 40-2 may be fixed and moved horizontally.

As shown in FIG. 5, a particle-coating apparatus 10-3, which is another example of a particle-coating unit that performs the coating step 1001, includes a holding table 20-3, a particle supply unit 30, and a particle-coating unit 40-3. The holding table 20-3 holds the other side of the workpiece 1 on its holding surface, and transports the workpiece 1 in a direction parallel to the holding surface by a transport unit (not shown) connected to its side, as indicated by arrow 23 in FIG. 5. The particle-coating unit 40-3 includes a chamber 41 having an opening 42 formed on its side through which the holding table 20-3 holding the workpiece 1 can pass, an opening/closing door 43 that opens and closes the opening 42, and an injection unit 44. The injection unit 44 is provided on the bottom surface of the chamber 41. The base end of the injection unit 44 is connected to the particle supply unit 30, and the particle 100 supplied from the particle supply unit 30 is injected into the chamber 41 from an injection hole at the tip, causing the particle 100 to float within the chamber 41.

In a third example of coating step 1001, coating step 1001 is performed using particle coating apparatus 10-3. In this third example of coating step 1001, as shown in FIG. 5, the spray unit 44 creates a state in which the particles 100 supplied from the particle supply unit 30 are suspended within chamber 41, the workpiece 1 is held on holding table 20-3 with one water-repellent side facing upward, and the door 43 is opened, and the holding table 20-3 holding workpiece 1 is carried through opening 42 into chamber 41 where the particles 100 are suspended. The workpiece 1 is then left in chamber 41 for a certain period of time, thereby evenly coating one side of the workpiece 1 with the particles 100.

In the third example of the coating step 1001, instead of carrying the holding table 20-3 holding the workpiece 1 into the chamber 41, the holding table 20-3 may be installed inside the chamber 41, and the workpiece 1 may be carried in and placed on the holding table 20-3 inside the chamber 41. In this case, there may be a mechanism such as an air blower to clean the holding surface of the holding table 20-3 before the workpiece 1 is carried in and placed on the holding table 20-3 inside the chamber 41.

In the coating step 1001, in both the first and second examples, the amount of microparticles 100 supplied (amount of coating) to one side of the workpiece 1 is controlled by the on-off valve 33 or the like, and in the third example, the time the workpiece is placed in the chamber 41 is controlled by controlling the coating area ratio, which is the ratio of the projected area of the microparticles 100 in a plan view to the area to which the liquid resin 200 is to be applied (or the area to which the liquid resin 200 has been applied) on one side of the workpiece 1. After one side of the workpiece 1 is coated with microparticles 100 in the coating step 1001, areas where excess microparticles 100 have accumulated can be checked and inspected, and the excess microparticles 100 can be removed with air or the like.

Figure 6 is a perspective view showing an example of the protective film forming step 1002 in Figure 1. As shown in Figure 6, the protective film forming step 1002 is a step in which a liquid resin 200 is applied to one surface of the workpiece 1 coated with the microparticles 100 in the coating step 1001 to form a protective film 201 (see Figure 10, etc.) that protects the workpiece 1.

In the protective film forming step 1002, as shown in FIG. 6, the workpiece 1, one side of which is coated with microparticles 100, is held from the other side by the holding table 51 of the protective film forming unit 50, and the holding table 51 is rotated around an axis parallel to the vertical direction to rotate the workpiece 1 on the holding table 51. Liquid resin 200, supplied from a resin supply source (not shown), is ejected by the resin supply nozzle 52 of the protective film forming unit 50 toward the one side of the workpiece 1 on the holding table 51 that is coated with microparticles 100, thereby applying the liquid resin 200 to the one side of the workpiece 1 that is coated with microparticles 100, and a protective film 201 that protects the workpiece 1 is formed with the applied liquid resin 200. In protective film formation step 1002, liquid resin 200 is repelled by one surface of workpiece 1, which has water repellency, but is not repelled by the surface of the microparticles 100, so protective film 201 is formed on one surface of workpiece 1 starting from the microparticles 100. Here, because there are fine irregularities on one surface of workpiece 1 to which microparticles 100 are applied, an effect similar to the anchor effect occurs, and liquid resin 200 penetrates into the gaps between the microparticles 100, making it possible to form protective film 201 on one surface of workpiece 1, which has water repellency.

In this embodiment, the liquid resin 200 applied in the protective film formation step 1002 is a water-soluble resin, such as polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP). The protective film 201 formed in the protective film formation step 1002 prevents debris (machining chips) 300 (see Figure 10) generated in the laser beam irradiation step 1003 from adhering to the workpiece 1.

Here, the relationship between the particle diameter of the microparticle 100, the thickness d of the protective film 201, and the coverage area ratio of the microparticle 100 will be explained. Figures 7 and 8 are cross-sectional and top views, respectively, illustrating the coverage area ratio of the microparticle 100 coated in coating step 1001 of Figure 1. Both Figures 7 and 8 show an example of the state of one surface of the workpiece 1 after the microparticle 100 is coated in coating step 1001 and the protective film 201 is formed in protective film formation step 1002. Note that the resin layer 8 is omitted in Figure 7. Note that while Figures 7 and 8 show the radius r of the microparticle 100, in this specification, the radius r of the microparticle 100 refers to half the particle diameter of the microparticle 100.

Assuming that the microparticles 100 are perfectly spherical, uniformly arranged at a constant interval L to cover one surface of the water-repellent workpiece 1, and that the protective film 201 is formed to uniformly cover the microparticles 100, then, referring to Figure 7, the minimum value of the interval L between adjacent microparticles 100 is the sum of twice the radius r of the microparticle 100 and twice the thickness d of the protective film 201 covering the microparticle 100, as shown in the following (Equation 1).

L (minimum value) = 2r + 2d ... (Equation 1)

Referring to Figure 8, the coverage area ratio of the microparticles 100 is calculated using Equation 1 as shown in Equation 2 below.

Coverage area ratio = πr ² /L (minimum value) ² = πr ² /(2r+2d) ² ... (Formula 2)

Furthermore, based on the assumption that the protective film 201 uniformly covers the microparticle 100, and assuming that the radius r of the microparticle 100 is equal to the thickness d of the protective film 201, the coverage area ratio of the microparticle 100 can be calculated using (Equation 2) as shown in the following (Equation 3).

Coverage area ratio = πr ² / (2r + 2d) ² = π/8≒39.2% (Formula 3)

Therefore, calculations based on these assumptions show that by setting the supply amount of microparticles 100 in coating step 1001 so that the microparticles 100 cover 40% or more of one side of the workpiece 1, i.e., so that the coverage area ratio is 40% or more, it is possible to form a protective film 201 in protective film formation step 1002 by applying liquid resin 200 uniformly over the entire surface of one side of the workpiece 1.

Next, we will explain the relationship between the radius r of the microparticles 100 and the coverage area ratio of the microparticles 100 when the thickness d of the protective film 201 is constant. Figure 9 is a graph illustrating the relationship between the radius r of the microparticles 100 coated in the coating step 1001 of Figure 1 and the coverage area ratio of the microparticles 100. As in the example described using Figures 7 and 8, assuming that the microparticles 100 are perfectly spherical, uniformly arranged at a constant interval L to coat one side of the water-repellent workpiece 1, and that the protective film 201 is formed to uniformly cover the microparticles 100, as shown in the graph of Figure 9, the coverage area ratio of the microparticles 100 increases as the radius r of the microparticles 100 increases. When the radius r of the microparticles 100 becomes equal to the thickness d of the protective film 201 and the coverage area ratio of the microparticles 100 reaches approximately 40%, the increase in the coverage area ratio of the microparticles 100 relative to the increase in radius r of the microparticles 100 is suppressed. Therefore, calculations based on these assumptions also show that by setting the supply amount of microparticles 100 so that the coverage area ratio is 40% or more in the coating step 1001, the liquid resin 200 can be applied uniformly to the entire surface of one side of the workpiece 1 in the protective film formation step 1002, thereby forming a protective film 201.

Figure 10 is a cross-sectional view showing an example of the laser beam irradiation step 1003 in Figure 1. The laser beam irradiation step 1003 is a step that takes place after the protective film formation step 1002, in which a laser beam 63 having a wavelength that is absorbed by the workpiece 1 is irradiated from the side of the workpiece 1 on which the protective film 201 has been formed, as shown in Figure 10, to process the workpiece 1.

In the laser beam irradiation step 1003, first, an imaging unit (not shown) images the workpiece 1 from the side where the protective film 201 is formed to obtain an image, and then, based on the obtained image, alignment is performed to align the workpiece 1 with the laser beam irradiator 62 that irradiates the laser beam 63 of the laser processing unit 60. In the laser beam irradiation step 1003, alignment may be performed using an imaging unit that captures images through the microparticles 100 and the protective film 201, or alignment may be performed based on the through-holes formed in the peripheral excess region.

In the laser beam irradiation step 1003, after alignment, as shown in FIG. 10, the workpiece 1, which has a protective film 201 formed on one side, is held from the other side by the holding table 61 of the laser processing unit 60, and the laser beam irradiator 62 of the laser processing unit 60 irradiates a laser beam 63 of a wavelength that is absorbed by the workpiece 1 toward the one side of the workpiece 1 on the holding table 61 on which the protective film 201 is formed, while a drive source (not shown) moves the workpiece 1 on the holding table 61 relative to the laser beam irradiator 62 along the planned division line 3, thereby laser processing the workpiece 1 with the laser beam 63 along the planned division line 3 from the side on which the protective film 201 is formed, and dividing the workpiece 1 into each device 4. In the laser beam irradiation step 1003, since a protective film 201 of sufficient thickness d has been formed on one surface of the workpiece 1 by the previously performed coating step 1001 and protective film formation step 1002, debris 300 generated when the workpiece 1 is irradiated with the laser beam 63 to ablate it adheres to the protective film 201 rather than directly to one surface of the workpiece 1.

11 is a cross-sectional view showing an example of cleaning step 1004 in FIG. 1. Cleaning step 1004 is a step of cleaning one side of workpiece 1 to remove protective film 201 after laser beam irradiation step 1003, as shown in FIG. 11. In cleaning step 1004, as shown in FIG. 11, the workpiece 1, on one side of which protective film 201 has been formed and which has been irradiated with laser beam 63, is held from the other side by holding table 71 of cleaning unit 70. While rotating holding table 71 about an axis parallel to the vertical direction to rotate workpiece 1 on holding table 71, cleaning water 73 supplied from a cleaning liquid supply source (not shown) is sprayed by cleaning liquid supply nozzle 72 of cleaning unit 70 toward one side of workpiece 1 on holding table 71, thereby removing protective film 201 formed on one side of workpiece 1. In cleaning step 1004, debris 300 generated by the previously performed laser beam irradiation step 1003 is attached to the protective film 201, so the debris 300 attached to the protective film 201 is also removed when the protective film 201 is removed. The cleaning water 73 is, for example, pure water or a two-fluid mixture of pure water and compressed air, and dissolves the protective film 201, which is made of water-soluble resin 200.

Conventionally, it has been difficult to form a uniform protective film of liquid resin on one side of a water-repellent workpiece because water-soluble liquid resin is repelled by the surface of the workpiece. Therefore, in the workpiece processing method according to the embodiment configured as described above, one side of the water-repellent workpiece 1 is coated with microparticles 100 in a coating step 1001 performed before the protective film formation step 1002. Because the microparticles 100 themselves are not water-repellent and do not repel the liquid resin 200, and because the irregularities formed on the one side of the workpiece 1 by the microparticles 100 have an anchoring effect, the liquid resin 200 can be uniformly applied to the one side of the water-repellent workpiece 1 to form a uniform protective film 201. This protective film 201 prevents debris 300 generated in the subsequent laser beam irradiation step 1003 from reattaching to the workpiece 1, thereby preventing the debris 300 from adversely affecting the characteristics of the device 4 and causing performance defects.

In the workpiece processing method according to the embodiment, the particle diameter of the microparticles 100 coating one side of the workpiece 1 in coating step 1001 is between 100 nm and 30 μm, so there is no need to use a filter with an excessively fine mesh, which increases manufacturing costs, and the cost of the filter 34 can be sufficiently reduced. Furthermore, the particle diameter of the microparticles 100 is not so large that the liquid resin 200 cannot be applied to the areas coated with the microparticles 100. Therefore, the unevenness formed by the microparticles 100 does not prevent the liquid resin 200 from being applied in protective film formation step 1002. In protective film formation step 1002, the liquid resin 200 can be uniformly applied to the entire surface of one side of the workpiece 1 to form the protective film 201.

In the workpiece processing method according to the embodiment, in the coating step 1001, the supply amount of microparticles 100 is set so that the microparticles 100 cover 40% or more of one surface of the workpiece 1. Therefore, in the protective film formation step 1002, the liquid resin 200 can be more stably and uniformly applied to the entire surface of one surface of the workpiece 1 to form the protective film 201.

The workpiece processing method according to the embodiment further includes a cleaning step 1004 for cleaning the protective film 201 after the laser beam irradiation step 1003. This removes the protective film 201 from the workpiece 1 along with the debris 300 attached to the protective film 201, further reducing the risk of the debris 300 re-adhering to the workpiece 1 and further preventing the debris 300 from adversely affecting the characteristics of the device 4 and causing characteristic defects.

In the past, it was particularly difficult to form a uniform protective film of liquid resin on one side of a workpiece, especially when the workpiece contained water-repellent properties due to the silicone resin it contained. However, the workpiece processing method according to the embodiment can more significantly achieve the above-mentioned effects, even when one side of the workpiece 1 is highly water-repellent due to the silicone resin it contains.

Next, the inventors of the present invention confirmed the effects of the method for processing a workpiece according to the embodiment. Figure 12 is a diagram explaining the effects of the method for processing a workpiece according to the embodiment. Figure 12 summarizes the results obtained when confirming the effects.

The "Comparative Example" column in Figure 12 shows the coverage area ratio of the microparticles and the protective film application state when a conventional workpiece processing method is performed on a workpiece 1 having one surface containing silicone resin and having water repellency, without performing the coating step 1001 of the workpiece processing method according to the embodiment, in which a protective film is formed by applying a liquid resin to the water-repellent surface, processing with a laser beam, and cleaning the protective film. The "Example 1,""Example2,""Example3,""Example4," and "Example 5" columns in Figure 12 show the coverage area ratio of the microparticles ₁₀₀ and the protective film application state when a workpiece 1 having one surface containing silicone resin and having water repellency is processed by the method of processing a workpiece according to the embodiment including the coating step 1001, in which the supply amount of the microparticles 100 is set so that 10%, 30%, 40%, 50%, and 100%, respectively, of the water-repellent surface of the workpiece 1 is covered with calcium carbonate (CaCO 3 ) microparticles 100 in the coating step 1001.

The "Covered area ratio" row in Figure 12 shows the covered area ratio of the microparticles as a percentage. In the "Protective film coating status" row in Figure 12, "◎" indicates that a protective film was formed uniformly over the entire surface of one of the water-repellent surfaces, "○" indicates that a protective film was formed almost uniformly over the entire surface of one of the water-repellent surfaces, and "×" indicates that a protective film was not formed over the entire surface of one of the water-repellent surfaces.

As shown in FIG. 12 , in the "Comparative Example," in which a conventional workpiece processing method was performed without performing coating step 1001 of the workpiece processing method according to the embodiment, the protective film application state was "×," meaning that a protective film was never formed over the entire surface, resulting in debris 300 adhering to the workpiece. On the other hand, in "Example 1," "Example 2," "Example 3," "Example 4," and "Example 5," in which the workpiece processing method according to the embodiment including coating step 1001 was performed, the protective film application state was "○" or "◎," meaning that a protective film 201 was formed at least generally uniformly over the entire surface, resulting in the results being that adhesion of debris 300 to the workpiece 1 was largely suppressed. This demonstrates that, in the example shown in FIG. 12 , performing coating step 1001 enables the application of liquid resin 200 to uniformly form protective film 201 over the entire surface of one of the water-repellent surfaces of workpiece 1.

Furthermore, in "Example 3," "Example 4," and "Example 5," in which the supply amount of microparticles 100 was set so that the microparticles 100 covered 40% or more of the water-repellent surface of the workpiece 1 in the coating step 1001, the protective film coating state was rated "Excellent," meaning that the protective film 201 was formed uniformly over the entire surface of the water-repellent surface of the workpiece 1. This demonstrates that in the example shown in Figure 12, by performing the coating step 1001 by setting the supply amount of microparticles 100 so that the supply amount of microparticles 100 covers 40% or more of the water-repellent surface of the workpiece 1, the protective film 201 can be more stably and uniformly formed over the entire surface of the water-repellent surface of the workpiece 1 by applying the liquid resin 200.

Furthermore, although Figure 12 shows examples and comparative examples in which calcium carbonate (CaCO ₃ ) microparticles 100 were used, similar trends and results to those of the example shown in Figure 12 were obtained even when carbon (C) microparticles 100 were used.

Note that the present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, while the above embodiment uses one microparticle coating unit 40-1, 40-2, there may be multiple units. Using multiple microparticle coating units 40-1, 40-2 can shorten the time required to coat the microparticles 100.

REFERENCE SIGNS LIST 1 Workpiece 2 Front surface 5 Back surface 63 Laser beam 100 Fine particles 200 Resin 201 Protective film

Claims (9)

A processing method for processing a workpiece having a water-repellent surface, comprising:
a coating step of coating one surface of the workpiece with fine particles of a material that does not have water repellency , and forming irregularities on the one surface with the fine particles ;
a protective film forming step of applying a water-soluble liquid resin to the one surface coated with the fine particles to form a protective film for protecting the workpiece;
a laser beam irradiation step of irradiating a laser beam having a wavelength that is absorbed by the workpiece from the side of the workpiece on which the protective film is formed, thereby processing the workpiece;
A method for processing a workpiece, comprising: In the coating step, while rotating the workpiece, the fine particles are sprayed from a spray hole at the tip of a nozzle of a fine particle coating unit toward the one surface of the workpiece located vertically below, thereby coating the one surface of the workpiece with the fine particles.
The method for processing a workpiece according to claim 1. In the coating step, the workpiece and the microparticle coating unit are moved relatively in a horizontal direction, and the microparticles are sprayed from a plurality of spray holes of the microparticle coating unit toward the one surface of the workpiece located vertically below, thereby coating the one surface of the workpiece with the microparticles.
The method for processing a workpiece according to claim 1. In the coating step, the fine particles are injected into a chamber to create a state in which the fine particles are floating, the workpiece is carried into the chamber in which the fine particles are floating, and the workpiece is left in the chamber for a certain period of time, thereby coating the one surface of the workpiece with the fine particles.
The method for processing a workpiece according to claim 1. 2. A method for processing a workpiece as described in claim 1, wherein after coating one side of the workpiece with the fine particles in the coating step, areas where excess fine particles have accumulated are confirmed and inspected, and the areas where excess fine particles have accumulated are removed. 6. The method for processing a workpiece according to claim 1, wherein the particle diameter of the fine particles is 100 nm or more and 30 [mu]m or less. 7. The method for processing a workpiece according to claim 1, wherein in the coating step, the particles are set so as to cover 40% or more of one surface of the workpiece. 8. The method for processing a workpiece according to claim 1 , further comprising, after the laser beam irradiation step, a cleaning step of cleaning the one surface of the workpiece to remove the protective film. The method for processing a workpiece according to claim 1 , wherein the workpiece contains a silicone resin.