CN108373694B

CN108373694B - Resin agent for forming protective film and laser processing method

Info

Publication number: CN108373694B
Application number: CN201611040545.0A
Authority: CN
Inventors: 大浦幸伸; 梁仙一; 山下阳平
Original assignee: Disco Corp
Current assignee: Disco Corp
Priority date: 2016-11-10
Filing date: 2016-11-10
Publication date: 2021-08-17
Anticipated expiration: 2036-11-10
Also published as: CN108373694A

Abstract

The present invention relates to a resin agent for forming a protective film and a laser processing method. In the processing using the laser beam, the processability, the processing quality and the yield are further improved. As the resin agent for forming a protective film used for laser processing, a resin agent for forming a protective film containing a water-soluble resin and fine particles of a metal oxide dispersed in an aqueous resin solution and having an elongated shape with a cross section having a major axis and a minor axis orthogonal to the major axis is used. Since fine particles of a metal oxide having a long and thin shape with a cross section having a major axis and a minor axis perpendicular to the major axis are dispersed in an aqueous resin solution, when laser processing is performed by applying the fine particles to a workpiece to form a protective film, the absorption rate of a laser beam in the protective film increases, and thus processing efficiency improves, and laser processing can be efficiently performed also on a substrate having low absorption at the wavelength of the laser beam. In addition, the processing quality is also improved, and the yield of products manufactured by processing can be improved.

Description

Resin agent for forming protective film and laser processing method

Technical Field

The present invention relates to a resin agent for forming a protective film for laser processing and a laser processing method for applying the resin agent for forming a protective film on a substrate to perform laser processing.

Background

Conventionally, a laser beam is used for cutting and dividing a plate-like object such as glass. Patent document 1 describes that when a glass substrate is irradiated with a laser beam to perform ablation processing, titanium dioxide (TiO) is dispersed therein₂) And the resin of the micro metal oxide is coated on the glass substrate to form a protective film, thereby improving the absorption efficiency of the laser beam and improving the processability of the glass substrate.

By using this technique, the rate of occurrence of chipping and laser erroneous sintering points (レーザ sintered け) can be reduced as compared to the case where a resin in which no metal oxide is dispersed is used as the liquid for forming the protective film.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-81951

Disclosure of Invention

Problems to be solved by the invention

However, in the invention described in cited document 1, further improvement is required from the viewpoint of workability, processing quality, and yield.

The present invention has been made in view of the above circumstances, and an object thereof is to further improve workability, processing quality, and yield in processing using a laser beam.

Means for solving the problems

The present invention is a resin agent for forming a protective film for laser processing, which contains a water-soluble resin and fine particles of a metal oxide dispersed in the water-soluble resin and having an elongated shape having a long axis and a short axis perpendicular to the long axis in cross section.

Preferably, the metal oxide fine particles have a major axis length of 500nm or less and a minor axis length of 1/10 to 1/5 of the major axis length. Preferably, the protective film-forming resin agent contains 0.1 to 10 vol% of fine particles of a metal oxide.

The present invention is a laser processing method for performing ablation processing on a substrate by irradiating a laser beam, including: a protective film forming step of applying the protective film forming resin agent to at least a region of a substrate to be subjected to ablation processing to form a protective film containing fine particles of a metal oxide; and a laser processing step of irradiating the region where the protective film is formed with a laser beam to perform ablation processing after the protective film forming step is performed.

Effects of the invention

The resin agent for forming a protective film of the present invention has excellent dispersibility in a resin because fine particles of a metal oxide having a long and thin shape with a cross section having a long axis and a short axis perpendicular to the long axis are dispersed in a water-soluble resin. Therefore, when the protective film is formed by applying the coating material to the workpiece and laser processing is performed, the absorbance of the laser beam in the protective film is increased, and thus the processing efficiency is improved, and the laser processing can be efficiently performed even for a substrate having low absorption of the wavelength of the laser beam. In addition, the processing quality is also improved, and the yield of products manufactured by processing can be improved.

Drawings

Fig. 1 is a perspective view showing an example of a laser processing apparatus.

Fig. 2 is a perspective view showing a protective film forming unit provided in the laser processing apparatus.

Fig. 3 is an enlarged sectional view showing a plate-like workpiece having a protective film coated on the surface thereof.

Fig. 4 is an enlarged photograph showing a protective film using the resin agent for forming a protective film of the present invention.

Fig. 5 is an enlarged photograph showing a protective film using a conventional resin agent for forming a protective film.

FIG. 6 is an enlarged photograph of a portion of a substrate subjected to ablation under processing conditions of a power of 3W, a repetition frequency of 40kHz, and a feed rate of 150mm/s, and (a) is an enlarged photograph of a portion of a substrate coated with a protective film of an example subjected to ablation; (b) shown is an enlarged photograph of a portion of the substrate coated with the protective film of the comparative example, which was subjected to ablation processing.

FIG. 7 is an enlarged photograph of a portion of a substrate subjected to ablation under processing conditions of a power of 3W, a repetition frequency of 40kHz, and a feed rate of 250mm/s, and (a) is an enlarged photograph of a portion of a substrate coated with a protective film of an example subjected to ablation; (b) shown is an enlarged photograph of a portion of the substrate coated with the protective film of the comparative example, which was subjected to ablation processing.

FIG. 8 is an enlarged photograph of a portion of a substrate subjected to ablation under processing conditions of a power of 3W, a repetition frequency of 120kHz, and a feed rate of 150mm/s, and (a) is an enlarged photograph of a portion of a substrate coated with a protective film of an example subjected to ablation; (b) shown is an enlarged photograph of a portion of the substrate coated with the protective film of the comparative example, which was subjected to ablation processing.

FIG. 9 is an enlarged photograph of a portion of a substrate subjected to ablation under processing conditions of a power of 3W, a repetition frequency of 120kHz, a feed rate of 150mm/s, and a defocus of 30 μm toward the back side of the substrate, and (a) is an enlarged photograph of a portion of a substrate coated with a protective film of an example subjected to ablation; (b) shown is a magnified photograph of a portion where ablation processing was performed in comparison with a substrate coated with a protective film of comparative example.

Fig. 10 is a graph showing a relationship between the wavelength of the laser beam and the absorbance.

Detailed Description

A laser processing apparatus 1 shown in fig. 1 is an apparatus for processing a plate-like workpiece W held on a chuck table 2 by a laser processing unit 3. The back surface of the plate-like work W is bonded to the belt T, and an annular frame F is bonded to the belt T, and the plate-like work W is supported by the frame F with the belt T interposed therebetween.

A cassette mounting area 4 on which a cassette 40 is mounted is provided on the front surface side (-Y direction side) of the laser processing apparatus 1, and the cassette 40 accommodates a plurality of plate-shaped workpieces W supported by a frame F. The cassette mounting area 4 can be lifted and lowered. A temporary placement area 41 is provided behind (+ Y direction side) the cassette placement area 4, and the plate-shaped workpiece W supported by the frame F is temporarily placed on the temporary placement area 41. The temporary placement area 41 is provided with a position alignment unit 42 that aligns the plate-like workpiece W with a predetermined position. Further, a carrying-in/out unit 43 is disposed behind the temporary placement area 41 (+ Y direction side), and the carrying-in/out unit 43 carries the plate-like workpiece W supported by the frame F out of the cassette 40 and into the cassette 40.

The chuck table 2 is movable in the X-axis direction and in the Y-axis direction between a mounting and demounting region a where a plate-like workpiece W supported by a frame F is mounted on and demounted from the chuck table 2 and a machining region B where laser machining is performed.

The protective film forming unit 6 is disposed on the + Y direction side of the detachable area a, and forms a protective film on the surface of the plate-shaped workpiece W before laser processing. As shown in fig. 2, the protective film forming unit 6 includes: a holding unit 60 for fixing and rotating the plate-like workpiece W supported by the frame F; a resin nozzle 61 for dropping a liquid resin onto the plate-like work W fixed to the holding portion 60; and a cleaning liquid nozzle 62 for dropping a cleaning liquid onto the plate-like work W. The holding unit 60 can be moved up and down by the lifting unit 63 and can be rotated by the motor 64.

The elevating unit 63 is composed of a plurality of cylinders 630 fixed to the side surface of the motor 64 and a piston rod 631, and is configured to elevate the motor 64 and the holding unit 60 by elevating and lowering the cylinders 630.

As shown in fig. 1, a 1 st conveying unit 5 is disposed in the vicinity of the temporary placement area 41, and the 1 st conveying unit 5 conveys the plate-like workpiece W supported by the 1 st frame between the temporary placement area 41 and the protective film forming unit 6.

Above the protective film forming unit 6, a 2 nd conveying unit 7 is disposed, and the 2 nd conveying unit 7 conveys the plate-like workpiece W supported by the frame F from the protective film forming unit 6 onto the chuck table 2 located in the mounting/demounting region a. The conveyance unit 7 of the 2 nd includes: an adsorption part 70 for adsorbing the plate-shaped workpiece W, an elevating part 71 for elevating the adsorption part 70, and an arm part 72 for moving the adsorption part 70 and the elevating part 71 in the Y-axis direction.

The laser processing unit 3 includes: an oscillation unit 30 for oscillating the laser beam, a frequency setting unit 31 for setting a repetition frequency for the laser beam, a power adjusting unit 32 for adjusting the power of the laser beam, and a condenser 8 for condensing the laser beam.

Next, an outline of the operation of the laser processing apparatus 1 for laser processing a plate-shaped workpiece W shown in fig. 1 will be described. First, the cassette 40 accommodates therein a plurality of plate-like workpieces W supported by a frame F. Then, the frame F is held by the carrying-in and carrying-out unit 43, and the plate-like workpiece W is carried out to the temporary placement area 41 together with the frame F.

(protective film formation step)

In the temporary placement area 41, after the plate-shaped workpiece W is positionally aligned with a predetermined position by the position alignment unit 42, the plate-shaped workpiece W supported by the frame F is conveyed to the holding section 60 of the protective film forming unit 6 by the 1 st conveying unit 5, and as shown in fig. 2, the holding surface W1 is exposed upward. Then, the resin agent 610 for forming a protective film is dropped onto the surface W1 of the plate-like work W from the resin nozzle 61 shown in fig. 2, and the resin agent 610 for forming a protective film is applied to the entire surface W1 by rotating the holding portion 60. The protective film-forming resin agent 610 may be applied by a spin coating method as in the present embodiment, or may be applied by being discharged from a slit-shaped nozzle.

After the protective film forming resin agent 610 is applied to the front surface W1 of the plate-like workpiece W, the protective film 9 shown in fig. 3 is coated by drying and curing the protective film forming resin agent 610 by, for example, rotating the holding portion 60. The protective film-forming resin agent 610 may be dried by irradiation with light from a lamp (e.g., a xenon flash lamp). In this case, pulsed light may be irradiated to avoid a temperature rise. Furthermore, hot plate based baking may be performed.

As shown in fig. 3, after the front surface W1 of the wafer W is coated with the protective film 9 containing fine particles of metal oxide, the elevating portion 71 of the 2 nd conveying unit 7 shown in fig. 1 is lowered, and the plate-shaped workpiece W is adsorbed by the adsorbing portion 70. Then, the lifting unit 71 is raised, and the arm 72 is moved in the-Y direction, whereby the plate-like workpiece 2 is moved to above the chuck table 2 located in the mounting/demounting area a, and the lifting unit 71 is lowered to release the suction of the plate-like workpiece W, whereby the plate-like workpiece W is placed on the chuck table 2 and sucked and fixed.

(laser processing step)

Then, the chuck table 2 is moved in the-X direction, the planned dividing line to be processed is detected, and the condenser 8 is aligned with the planned dividing line in the Y axis direction. Then, the machining is further performed in the X-axis direction by the chuck table 2, and the laser beam is irradiated by the condenser 8 through the protective film 9 to the region of the protective film on which the front surface W1 of the plate-shaped workpiece W is formed, thereby performing the ablation along the planned dividing lines. The processing feed rate may be, for example, 10 to 300 mm/sec. In addition, the laser beam can have a wavelength of 355nm, a power of 0.5-10W, and a repetition frequency of 10-200 kHz, for example.

Next, the protective film 9 coated by the protective film forming means 6 will be described in detail. The dropped resin agent 610 for forming a protective film shown in fig. 2 is formed by dispersing a metal oxide in a water-soluble resin. Here, as the water-soluble resin, for example, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyethylene glycol, polyethylene oxide, polyethyleneimine, carboxymethyl cellulose, carboxyethyl cellulose, or the like can be used. The viscosity of polyvinyl alcohol or polyvinyl pyrrolidone can be 20-400 cp. Further, as the metal oxide, for example, titanium dioxide (TiO) is used₂) The fine particles of (1). In addition to titanium dioxide, F may also be usede₂O₃、ZnO、CeO₂、CuO、Cu₂O or MgO. These metal oxides are selected based on the absorbance of the wavelength of the laser beam used in processing.

The photograph 100 of fig. 4 is an enlarged view of the protective film 9 using the resin agent 610 for forming a protective film according to the present invention, and shows that the fine particles of the metal oxide are formed into an amorphous elongated shape having a major axis and a minor axis orthogonal to the major axis, instead of a circular shape. The elongated shape includes an ellipse, a polygon, a needle, and the like, and the directions thereof are irregular, and these include a shape having high anisotropy. For example, the length of the major axis is 500nm or less, and the length of the minor axis is 1/10 to 1/5 of the length of the major axis. The length of the major axis may preferably be 1 to 100nm, more preferably 20 to 50 nm. When the length of the long axis exceeds 500nm, the scattering effect of the laser beam becomes dominant, and is not desirable in laser processing.

The concentration of the fine particles of the metal oxide may be 0.1 to 10% by volume, preferably 0.5 to 5% by volume, and more preferably 1 to 2.5% by volume, based on the total volume (volume of the metal oxide + volume of the resin).

The protective film 9 is used as an etching mask in plasma dicing (dry etching), and can improve plasma resistance.

Example 1

The metal oxide (titanium oxide (TiO) shown in photograph 100 of FIG. 4₂) A dispersion (TiO) obtained by dispersing fine particles in water₂Concentration: 30% by weight) was mixed into an aqueous solution of polyvinyl alcohol (GL-05, manufactured by Nippon synthetic chemical Co., Ltd.), and the mixture was stirred by a stirrer to prepare TiO in an elongated shape₂The fine particles of (2) were dispersed in an aqueous polyvinyl alcohol solution to obtain a sample (water-soluble resin) of example. As TiO₂The fine particles of (2) are used in a particle size (long axis length) of 20 to 50 nm. TiO relative to the volume of the whole containing the water-soluble resin₂The occupancy ratio of the fine particles of (4) was 62%.

On the other hand, as a comparative example, the fine particles of titanium oxide having a substantially spherical shape, not an elongated shape, shown in photograph 101 of FIG. 5 were dispersed in waterDispersion (TiO)₂Concentration: 30% by weight) was mixed with an aqueous solution of water-soluble polyvinyl alcohol (GL-05, manufactured by Nippon synthetic chemical Co., Ltd.), and the mixture was stirred with a stirrer to prepare TiO₂The fine particles of (2) were dispersed in an aqueous polyvinyl alcohol solution to obtain a sample (water-soluble resin) of a comparative example. TiO relative to the volume of the whole containing the water-soluble resin₂The occupancy ratio of the fine particles of (4) was 80%.

The water-soluble resins of the examples and the water-soluble resins of the comparative examples were coated on the surface of glass to form a protective film, and laser beams were irradiated along the streets of the glass to perform ablation processing.

The photographs shown in fig. 6 to 9 were taken of a processed portion obtained by ablation processing of a glass coated with protective films of examples and comparative examples using the laser processing apparatus 1 shown in fig. 1. In fig. 6 to 9, (a) photograph 201,301,401,501 in each figure shows the processing results of the examples, and (b) photograph 202,302,402,502 in each figure shows the processing results of the comparative examples.

Photograph 201,301,401,501 (a) of fig. 6 to 9 was obtained by forming a portion coated with a protective film by applying only a liquid resin (left side) and a portion coated with the protective film of the example (right side) on both sides (left and right sides) of a boundary 601,603,605,607 of the surface of glass, respectively, and then performing ablation processing on each portion to photograph the processed state. On the other hand, photograph 202,302,402,502 (b) of fig. 6 to 9 is obtained by forming a portion (left side) coated with a protective film by applying only a liquid resin and a portion (right side) coated with a protective film by using a resin agent for forming a protective film in which substantially spherical titanium oxide is dispersed on both sides (left and right) of the boundaries 602,604,606,608 of the glass surface, and then performing ablation processing on each portion to photograph the processed state.

The processing conditions of the laser beam common to all examples and comparative examples are as follows.

Wavelength: 355nm

Power: 3W

Fig. 6 (a) and (b) show the machining results when the repetition frequency was set to 40kHz and the feed speed of the chuck table 2 shown in fig. 1 was set to 150 mm/sec. The portion coated with the protective film not containing titanium oxide, which is reflected on the left side from the boundary 601 of the photograph 201 in fig. 6 (a), is not formed linearly in the processing tank 203, and a large amount of debris is generated on both sides of the processing tank 203. On the other hand, in the portion where the protective film of the example was coated on the right side from the boundary 601 of the photograph 201 in fig. 6 (a), it was confirmed that there was no chipping on both sides of the processing groove 204, the processing groove 204 was formed linearly, and the processing quality was high. In addition, it was confirmed that a large amount of the resin agent constituting the protective film was scattered on both sides of the processing tank 204, and the processing could be efficiently performed.

The portion coated with the protective film containing no titanium oxide, which is reflected on the left side from the boundary 602 of the photograph 202 (b) of fig. 6, is not formed linearly in the processing tank 205, and a large amount of debris is generated on both sides of the processing tank 205. On the other hand, the processing bath 206 is formed linearly in a portion where the protective film of approximately spherical titanium oxide is coated on the right side from the boundary 602 of the photograph 202 (b) of fig. 6. However, it was confirmed that the processing tank 206 was narrower in tank width and less in scattering amount of the resin agent constituting the protective film than the processing tank 204 of photograph 201 (a) of fig. 6, and that the processing tank 204 of photograph 201 (a) of fig. 6 was able to process more efficiently. Therefore, it was confirmed that the amorphous fine particles having a long and thin shape can improve the processing quality and the processing efficiency of the titanium oxide contained in the protective film more than the substantially spherical fine particles.

Fig. 7 (a) and (b) show the results of the machining when the repetition frequency was set to 40kHz and the feed speed of the chuck table 2 shown in fig. 1 was set to 250 mm/sec. The portion coated with the protective film containing no titanium oxide, which is reflected on the left side from the boundary 603 of the photograph 301 (a) of fig. 7, is not formed linearly in the processing tank 303, and chipping occurs on both sides of the processing tank 303. On the other hand, in the portion where the protective film of the example was coated on the right side from the boundary 603 of the photograph 301 (a) of fig. 7, it was confirmed that there was no chipping on both sides of the processing groove 304, the processing groove 304 was formed linearly, and the processing quality was high. In addition, it was confirmed that a large amount of the resin agent constituting the protective film was scattered on both sides of the processing tank 304, and the processing could be efficiently performed.

The portion coated with the titanium oxide-free protective film on the left side from the boundary 604 of the photograph 302 (b) of fig. 7 is not formed linearly in the processing tank 305, and a large amount of debris is generated on both sides of the processing tank 305. On the other hand, the processing bath 306 is formed linearly from the boundary 604 of the photograph 302 (b) of fig. 7, reflecting the portion covered with the protective film in which the substantially spherical titanium oxide is dispersed on the right side. However, it was confirmed that the processing tank 306 has a narrower tank width and a smaller amount of scattering of the resin agent constituting the protective film than the processing tank 304 of photograph 301 (a) of fig. 7, and that the processing tank 304 of photograph 301 (a) of fig. 7 can be processed more efficiently. Therefore, it was confirmed that the fine particles having a slender shape can improve the processing quality of the titanium oxide contained in the protective film more than the fine particles having a substantially spherical shape.

Fig. 8 (a) and (b) show the machining results when the repetition frequency was set to 120kHz and the feed speed of the chuck table 2 shown in fig. 1 was set to 150 mm/sec. The groove width of the processing groove 403 is narrowed in the portion covered with the protective film containing no titanium oxide, which is reflected on the left side from the boundary 605 of the photograph 401 (a) of fig. 8. On the other hand, in the processing tank 404 in which the portion covered with the protective film of the example on the right side is reflected from the boundary 605 of the photograph 401 (a) of fig. 8, it can be confirmed that the tank width is wide, and the resin agent constituting the protective film on both sides is scattered in a large amount, and the processing can be performed efficiently.

The groove width of the processed groove 405 is narrowed in the portion covered with the protective film containing no titanium oxide, which is reflected on the left side from the boundary 606 of the photograph 402 (b) of fig. 8. On the other hand, the processing bath 406, which is shown from the boundary 606 of the photograph 402 of fig. 8 (b) and has the right side coated with the protective film in which the substantially spherical titanium oxide is dispersed, has a wider bath width than the processing bath 405. However, it was confirmed that the machining tank 406 has a smaller tank width than the machining tank 404 in fig. 8 (a), and the machining tank 404 in fig. 8 (a) can be machined more efficiently. Therefore, it was confirmed that the fine particles having a slender shape can improve the processing quality of the titanium oxide contained in the protective film more than the fine particles having a substantially spherical shape.

Fig. 9 (a) and (b) show the processing results when the repetition frequency is 120kHz, the feed speed of the chuck table 2 shown in fig. 1 is 150 mm/sec, and the focal depth of the laser beam is defocused from the front surface to the back surface side of 30 μm. The portion coated with the protective film containing no titanium oxide, which is reflected on the left side from the boundary 607 of the photograph 501 (a) of fig. 9, is not formed with a continuous processing groove, and thus ablation processing cannot be performed. On the other hand, it was confirmed that the machining groove 504, which reflects the portion covered with the protective film of the example on the right side of the boundary 607 in the photograph 501 (a) of fig. 9, is formed continuously linearly, and can be subjected to ablation machining. Further, it was confirmed that the machining groove 504 has a wide groove width and can be efficiently machined.

The portion coated with the protective film not containing titanium oxide, which is shown on the left side of the boundary 608 of the photograph 501 (b) in fig. 9, is not formed with a continuous processing groove, and thus is not processed by ablation. On the other hand, it was confirmed that the processing bath 506, which was reflected from the boundary 608 of the photograph 502 (b) of fig. 9 and covered with the protective film in which the substantially spherical titanium oxide was dispersed on the right side, was formed continuously and linearly. However, it was confirmed that the machining tank 504 of fig. 9 (a) can perform machining more efficiently because the width of the machining tank 506 is narrower than the machining tank 504 of fig. 9 (a). Therefore, even when the focal point of the laser beam is shifted from the surface to the depth direction, it is confirmed that the titanium oxide particles having an elongated shape such as an elliptical shape can improve the processing quality more than the particles having a substantially spherical shape.

Table 1 shown below shows the average values of the laser false firing point generation rate, the chipping generation rate, and the yield when a workpiece (hereinafter referred to as the present workpiece) obtained by forming a polyimide film on silicon is subjected to laser processing. The processing conditions were as follows.

Wavelength: 355nm

Power: 2W

Repetition frequency: 200kHz

The diameter of the light spot: 10 μm

Feeding speed: 200mm/sec

In table 1, "metal oxide-free" indicates a case where a liquid resin containing no fine particles of a metal oxide is applied to the work to be coated with a protective film; "comparative example" shows a case where the work is coated with a protective film-forming resin agent in which fine particles of substantially spherical titanium oxide are dispersed, and the protective film is coated; the "present invention" refers to a case where a protective film is coated by applying a protective film-forming resin agent in which fine particles of titanium oxide having a long and narrow shape are dispersed on the work. The laser erroneous firing point is a phenomenon in which the scattered protective film reflects the laser beam and the laser beam is irradiated to a position where the irradiation is not performed.

[ Table 1]

The chipping generation rate of the present invention is 0.00% or less as indicated by the detection limit.

As is clear from Table 1, the resin agent for forming a protective film of the present invention is superior to the resin agent without a metal oxide or the resin agent of the comparative example in any of the rate of occurrence of laser erroneous firing spots, the rate of occurrence of chipping, and the yield.

Fig. 10 is a graph showing the results of determining the relationship between the wavelength and the absorbance of a laser beam by measuring the absorption spectrum of a sapphire substrate (reference), a resin agent in which substantially spherical fine particles of titanium oxide are dispersed, and a resin agent in which fine particles of titanium oxide having a slender shape are dispersed, using V-670 manufactured by japan spectrography.

As is clear from the graph of fig. 10, the absorbance is low for the sapphire substrate (reference), and is independent of the wavelength value. On the other hand, it was confirmed that the absorbance decreased as the wavelength was longer for the resin agent in which the fine particles of titanium oxide were dispersed, but the rate of decrease in absorbance was lower as the wavelength was longer in the case of the elongated shape than in the case where the shape of titanium oxide constituting the resin agent was substantially spherical, and higher absorbance could be maintained. Therefore, it is considered that, when a resin agent in which titanium oxide fine particles are formed into a slender shape is used as the protective film, laser processing can be efficiently performed even if the wavelength is increased, as compared with the case where titanium oxide fine particles are substantially circular.

Description of the symbols

W: a plate-shaped workpiece T: a belt F: frame structure

1: laser processing apparatus

2: chuck working table

3: the laser processing unit 30: the oscillation unit 31: frequency setting unit 32: power adjustment unit

4: cartridge mounting area 40: the box 41: temporary placement area 42: position alignment unit

43: carry-in/out unit

5: 1 st conveying unit

6: protective film forming unit 60: the stabilizer 61: resin nozzle 610: resin agent for forming protective film

62: cleaning solution nozzle 63: the elevating unit 630: the air cylinder 631: piston rod

64: motor with a stator having a stator core

7: the 2 nd conveying unit 70: adsorption section 71: the lifting part 72: arm part

8: light collector

201,202,301,302,401,402,501,502: photograph

203 to 206,303 to 306,403 to 406,504,506: processing tank

601-608: boundary of

Claims

1. A resin agent for forming a protective film for laser processing, which contains a water-soluble resin and fine particles of a metal oxide dispersed in the water-soluble resin and having an elongated shape having a major axis and a minor axis perpendicular to the major axis in cross section,

the length of the long axis is 500nm or less, and the length of the short axis is 1/10-1/5 of the length of the long axis.

2. The protective film-forming resin agent according to claim 1, wherein the fine particles of the metal oxide are contained in an amount of 0.1 to 10 vol%.

3. A laser processing method for performing ablation processing on a substrate by irradiating a laser beam,

it is provided with:

a protective film forming step of applying the resin agent for forming a protective film according to claim 1 or 2 to at least a region on a substrate to be subjected to ablation processing to form a protective film containing fine particles of the metal oxide; and

and a laser processing step of irradiating a laser beam to a region where the protective film is formed to perform ablation processing after the protective film forming step is performed.