CN113001034A

CN113001034A - Laser processing method

Info

Publication number: CN113001034A
Application number: CN202011396490.3A
Authority: CN
Inventors: 荒川太朗; 河野文弥
Original assignee: Disco Corp
Current assignee: Disco Corp
Priority date: 2019-12-04
Filing date: 2020-12-03
Publication date: 2021-06-22
Also published as: KR20210070212A; TW202128333A; JP2021089974A; JP7353157B2

Abstract

Provided is a laser processing method capable of suppressing a defective division of a workpiece having a curvature. A laser processing method of forming a work piece having a curvature into a desired shape, the laser processing method comprising the steps of: a holding step (ST1) for holding the workpiece; a coating step (ST2) of coating the workpiece with a coating member that transmits the laser beam so that the surface of the workpiece having the curvature is flat, after the holding step (ST 1); a laser processing step (ST3) of, after the covering step (ST2), irradiating a laser beam having a wavelength that is transparent to the covering member and the workpiece from the side of the workpiece covered by the covering member, and performing predetermined laser processing on the workpiece; and a dividing step (ST4) for dividing the workpiece by applying an external force to the workpiece after the laser processing step (ST 3).

Description

Laser processing method

Technical Field

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

Background

In order to form a workpiece into a desired shape, there is known a laser processing method in which a laser beam having a wavelength that is transparent to the workpiece is irradiated to form a division starting point and an external force is applied to divide the workpiece (see patent documents 1 and 2).

Patent document 1: japanese patent laid-open publication No. 2005-129607

Patent document 2: japanese patent No. 6151557

However, in the laser processing methods disclosed in

patent documents

1 and 2, when the workpiece is a workpiece having a curvature such as a lens or an object having a curvature such as a bump on a processing line of the workpiece, the laser beam is refracted and it is difficult to form a division start point at a desired position, and thus there is a problem that a division failure occurs and the quality is degraded.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a laser processing method capable of suppressing a defective division of a workpiece having a curvature.

In order to solve the above problems and achieve the object, a laser processing method according to the present invention is a laser processing method for forming a workpiece having a curvature into a desired shape, and includes the steps of: a holding step of holding the workpiece; a covering step of, after the holding step, covering the workpiece with a material that transmits the laser beam so as to flatten a surface of the workpiece having a curvature; a laser processing step of irradiating a laser beam having a wavelength that is transparent to the material and the workpiece from a side of the workpiece coated with the material that transmits the laser beam after the coating step, and performing predetermined laser processing on the workpiece; and a dividing step of dividing the workpiece by applying an external force to the workpiece after the laser processing step.

The laser processing method may include the following lift-off step: before or after the dividing step, the material coated on the surface of the workpiece having the curvature is peeled off from the workpiece.

In the laser processing method, in the laser processing step, a pore and an amorphous state surrounding the pore may be formed in the object to be processed.

The present invention has the effect of suppressing defective division of a workpiece having curvature.

Drawings

Fig. 1 is a perspective view illustrating a workpiece to be processed in the laser processing method according to embodiment 1.

Fig. 2 is a sectional view taken along line II-II in fig. 1.

Fig. 3 is a flowchart illustrating a flow of the laser processing method according to embodiment 1.

Fig. 4 is a side view showing a holding step of the laser processing method shown in fig. 3 in a partial section.

Fig. 5 is a side view, partially in section, showing a coating step of the laser processing method shown in fig. 3, in a state where a liquid coating material is dropped onto one surface of a workpiece.

Fig. 6 is a side view, partially in cross section, showing a state in which a pressing member is opposed to a coating member dropped on one surface of a workpiece in the coating step of the laser processing method shown in fig. 3.

Fig. 7 is a side view, partially in cross section, showing a state in which a liquid coating member is formed flatly on one surface of a workpiece in the coating step of the laser processing method shown in fig. 3.

Fig. 8 is a cross-sectional view illustrating refractive indexes of the clad member and the workpiece shown in fig. 7.

Fig. 9 is a side view, partially in section, showing a state in which a laser beam irradiation unit is positioned at one end of a line to be processed in the laser processing step of the laser processing method shown in fig. 3.

Fig. 10 is a side view, partially in section, showing a state in which the laser beam irradiation unit is moved to a position facing the other end of the line to be processed shown in fig. 9.

Fig. 11 is a sectional view showing a section XI in fig. 10.

Fig. 12 is a perspective view schematically showing the structure of a shield tunnel formed in the workpiece shown in fig. 11.

Fig. 13 is a cross-sectional view showing a state in which the workpiece is held by the expanding device in the dividing step of the laser processing method shown in fig. 3.

Fig. 14 is a cross-sectional view of the workpiece divided along the processing scheduled line in the dividing step of the laser processing method shown in fig. 3.

Fig. 15 is a sectional view schematically showing a peeling step of the laser processing method shown in fig. 3.

Fig. 16 is a perspective view of the workpiece after the peeling step in the laser processing method shown in fig. 3.

Fig. 17 is a flowchart illustrating a flow of the laser processing method according to embodiment 2.

Fig. 18 is a perspective view illustrating a workpiece to be processed in the laser processing method according to embodiment 3.

Fig. 19 is a sectional view of a main portion of the workpiece shown in fig. 18.

Description of the reference symbols

1: a workpiece; 2: one surface (a surface having curvature); 3: the other surface (surface having curvature); 20: a laser beam; 30: a cladding member (a material that transmits a laser beam); 41: fine pores; 42: amorphous; ST 1: a maintaining step; ST 2: coating; ST 3: a laser processing step; ST 4: a step of dividing; ST 5: and (5) stripping.

Detailed Description

A mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. The components described below include substantially the same components as can be easily conceived by those skilled in the art. The following structures can be combined as appropriate. Various omissions, substitutions, and changes in the structure can be made without departing from the spirit of the invention.

[ embodiment mode 1 ]

A laser processing method according to embodiment 1 of the present invention will be described with reference to the drawings. First, the object 1 to be processed by the laser processing method according to embodiment 1 will be described. Fig. 1 is a perspective view illustrating a workpiece to be processed in the laser processing method according to embodiment 1. Fig. 2 is a sectional view taken along line II-II in fig. 1.

(processed article)

As shown in fig. 1 and 2, both of the one surface 2 of the object 1 to be processed and the other surface 3 on the back side of the one surface 2 are formed as curved surfaces having curvature in the laser processing method according to embodiment 1. That is, both

surfaces

2 and 3 are surfaces having curvature. In embodiment 1, the workpiece 1 is made of a light-transmitting material, and is a convex lens in which both

surfaces

2 and 3 are formed into convex curved surfaces and the planar shape is circular. In embodiment 1, the workpiece 1 is made of glass and has a thickness of 300 μm or more and 1mm or less. In the present invention, in a cross section passing through the centers of both

surfaces

2 and 3 of the workpiece 1, a straight line passing through the centers of curvature of both

surfaces

2 and 3 is referred to as an axial center 4 of the workpiece 1 (indicated by a single-dot chain line in fig. 1 and 2).

(laser processing method)

The laser processing method according to embodiment 1 is a method of forming the planar shape of the workpiece 1 into a desired shape. In embodiment 1, the laser processing method is a method of forming the planar shape of the workpiece 1 into a quadrilateral shape (square shape in embodiment 1), but in the present invention, the desired shape of the workpiece 1 is not limited to a quadrilateral shape. In embodiment 1, the laser processing method is a method of cutting the outer edge portion of the object 1 along the line 5 indicated by a straight broken line in fig. 1. In embodiment 1, four lines to be processed 5 are set.

Fig. 3 is a flowchart illustrating a flow of the laser processing method according to embodiment 1. As shown in fig. 3, the laser processing method of embodiment 1 includes a holding step ST1, a coating step ST2, a laser processing step ST3, a dividing step ST4, and a peeling step ST 5. Next, each step of the laser processing method of embodiment 1 will be explained.

(maintenance step)

Fig. 4 is a side view showing a holding step of the laser processing method shown in fig. 3 in a partial section. The holding step ST1 is a step of holding the workpiece 1 on the holding table 10 (shown in fig. 4).

In embodiment 1, the holding table 10 includes: a disc-shaped table main body 11 having an outer diameter larger than the diameter of the workpiece 1; and an annular holding member 13 provided at an outer edge portion of the table main body 11. The upper surface 12 of the table main body 11 is formed flat along the horizontal direction. The holding member 13 is formed so that the inner and outer diameters are smaller than the diameter of the workpiece 1, and is disposed coaxially with the table body 11 on the upper surface 12 of the table body 11. In embodiment 1, the cross-sectional shape of the holding member 13 is formed in a semicircular shape that is convex upward. In embodiment 1, in the holding step ST1, the outer edge portion of the other front surface 3 of the workpiece 1 is placed on the holding member 13 of the holding table 10, and the workpiece 1 is held at a position where the axial center 4 is perpendicular to the upper surface 12 and is coaxial with the holding table 10. In the present invention, the shape of the holding table 10 is not limited to the shape described in embodiment 1, and may be, for example, a holding table made of a material (sponge, gel, or the like) that changes its shape in accordance with the shape of the workpiece 1.

(coating step)

Fig. 5 is a side view, partially in section, showing a coating step of the laser processing method shown in fig. 3, in a state where a liquid coating material is dropped onto one surface of a workpiece. Fig. 6 is a side view, partially in cross section, showing a state in which a pressing member is opposed to a coating member dropped on one surface of a workpiece in the coating step of the laser processing method shown in fig. 3. Fig. 7 is a side view, partially in cross section, showing a state in which a liquid coating member is formed flatly on one surface of a workpiece in the coating step of the laser processing method shown in fig. 3. Fig. 8 is a cross-sectional view illustrating refractive indexes of the clad member and the workpiece shown in fig. 7.

The coating step ST2 is a step of: after the holding step ST1, the workpiece 1 (shown in fig. 5, 6, and 7) is coated with the coating member 30, which is a material that transmits the laser beam 20 (shown in fig. 8), so that the one surface 2 side having a curvature is flat. In the coating step ST2, after the coating nozzle 31 is positioned on the one surface 2 of the workpiece 1, the liquid coating material 30 is dropped from the coating nozzle 31 as shown in fig. 5, and the entire one surface 2 is coated with the coating material 30 as shown in fig. 6.

The covering member 30 is cured when irradiated with ultraviolet rays, has a light-transmitting property at least after curing, and transmits the laser beam 20 having a wavelength (1030 nm in embodiment 1) that is transparent to the workpiece 1. That is, the laser beam 20 has a wavelength that is transparent to the cured coating member 30 and the workpiece 1. As shown in fig. 5 and 6, the one surface 2 of the workpiece 1 is entirely covered with the dripped covering member 30 by surface tension. In the present invention, even if the covering member 30 does not cover the entire one surface 2 of the workpiece 1 at the time of dropping, the entire one surface 2 of the workpiece 1 can be covered by pressing with the pressing member 32 shown in fig. 6. In embodiment 1, the covering member 30 is TEMPLOC (registered trademark) manufactured by electrochemical co, but the present invention is not limited thereto.

In the coating step ST2, when the one surface 2 of the workpiece 1 is entirely coated with the dripped coating member 30, the pressing member 32 is positioned on the one surface 2 with the coating member 30 interposed therebetween, as shown in fig. 6. A lower surface 33 of the pressing member 32 facing the one surface 2 through the covering member 30 is formed flat, and in embodiment 1, the lower surface 33 is perpendicular to the axial center 4 of the workpiece 1 held by the holding member 13. In the coating step ST2, the pressing member 32 is lowered to press the lower surface 33 against the coating member 30, thereby flatly forming the upper surface 34 of the coating member 30 as shown in fig. 7. In the present invention, the liquid covering member 30 has a predetermined viscosity. The predetermined viscosity is a viscosity to the extent that it can be prevented from drooping from the workpiece 1 due to dripping or pressing, and the predetermined viscosity of the liquid coating member 30 is because a flat surface cannot be formed when the liquid coating member 30 droops from the workpiece 1 due to dripping or pressing. In the coating step ST2, the coating member 30 is irradiated with ultraviolet rays, and the coating member 30 is cured with the upper surface 34 flat. In embodiment 1, the upper surface 34 of the covering member 30 is perpendicular to the axial center 4.

In the present invention, the refractive index (absolute refractive index) of the cured coating member 30 is equal to the refractive index (absolute refractive index) of the workpiece 1. The refractive index of the cured coating member 30 is equal to the refractive index of the workpiece 1, and means that, as shown in fig. 8, the focal point 21 of the laser beam 20 incident on the coating member 30 from the flat upper surface 34 and transmitted through the coating member 30 and the workpiece 1 to be condensed in the workpiece 1 is located in the range 22 in which the laser beam 20 of the upper surface 34 is incident in the horizontal direction (the direction parallel to the upper surface 34 or the direction perpendicular to the axial center 4). Alternatively, in the present invention, the fact that the refractive index of the cured cladding member 30 is equal to the refractive index of the workpiece 1 means that the formation position (depth position) of the modified layer (modified region) or the like is within ± 10 μm of the target position. In embodiment 1, the refractive index of the cured coating member 30 and the refractive index of the workpiece 1 are both about 1.5.

(laser processing step)

Fig. 9 is a side view, partially in section, showing a state in which a laser beam irradiation unit is positioned at one end of a line to be processed in the laser processing step of the laser processing method shown in fig. 3. Fig. 10 is a side view, partially in section, showing a state in which the laser beam irradiation unit is moved to a position facing the other end of the line to be processed shown in fig. 9. Fig. 11 is a sectional view showing a section XI in fig. 10. Fig. 12 is a perspective view schematically showing the structure of a shield tunnel formed in the workpiece shown in fig. 11.

The laser processing step ST3 is a step of: after the coating step ST2, the laser beam 20 having a wavelength that is transparent to the coating member 30 and the workpiece 1 is irradiated from the side of the workpiece 1 coated with the coating member 30 through which the laser beam 20 is transmitted, and the workpiece 1 is subjected to predetermined laser processing. In embodiment 1, in the laser processing step ST3, the laser beam 20 shown in fig. 9 is irradiated to the object 1 along the line to be processed 5, and the shield tunnel 40 shown in fig. 10 is formed as a division starting point along the line to be processed 5 as predetermined laser processing on the object 1.

In embodiment 1, in the laser processing step ST3, when the laser beam 20 is irradiated along each line to be processed 5, as shown in fig. 9, the laser beam irradiation unit 24 for irradiating the laser beam 20 is positioned at one end of the line to be processed 5, and the converging point 21 of the laser beam 20 irradiated by the laser beam irradiation unit 24 is set in the object 1. In embodiment 1, the laser beam irradiation means 24 sets the converging point 21 in the vicinity of the other surface 3 in the workpiece 1, but may be set in the vicinity of the one surface 2, or may change the converging position and perform a plurality of processes when sufficient processing cannot be performed in the thickness direction of the workpiece 1 by one process. In the present invention, the laser beam irradiation unit 24 may include a spherical lens or a plurality of lenses, and the converging point 21 may extend along the axial center 4 inside the workpiece 1 to form a converging region.

In embodiment 1, in the laser processing step ST3, the object 1 and the laser beam irradiation unit 24 are relatively moved along the line 5 while the laser beam irradiation unit 24 is irradiated with the pulse-shaped laser beam 20, and the laser beam irradiation unit 24 is moved toward the other end portion of the line 5. In embodiment 1, in the laser processing step ST3, as shown in fig. 10, when the laser beam irradiation unit 24 is positioned on the other end portion of the line 5 to be processed, the relative movement of the object 1 and the laser beam irradiation unit 24 and the irradiation of the laser beam 20 are stopped.

In embodiment 1, in the laser processing step ST3, a plurality of shield tunnels 40 are formed along the line to be processed 5 inside the object 1, and the shield tunnels 40 have the fine holes 41 shown in fig. 11 and 12 and amorphous material 42 surrounding the fine holes 41. The fine holes 41 and the amorphous substance 42 are formed in the range from the other surface 3 side where the focal point 21 of the laser beam 20 is located to the upper surface 34 of the covering member 30 on which the laser beam 20 is incident, the fine holes 41 extend parallel to the axial center 4 and penetrate the covering member 30 and the work 1 in the range of the upper surface 34 and the other surface 3, and the amorphous substance 42 is formed around the fine holes 41 in the range of the other surface 3 and the upper surface 34. A plurality of shield tunnels 40 are formed at predetermined intervals along the planned processing line 5.

In embodiment 1, as shown in fig. 12, the inner diameter 411 of the pore 41 is about 1 μm, and the outer diameter 421 of the amorphous phase 42 is about 5 μm. The intervals between the amorphous phases 42 adjacent to each other are about 10 μm, and the amorphous phases 42 of the shield tunnels 40 adjacent to each other are connected to each other.

(dividing step)

Fig. 13 is a cross-sectional view showing a state in which the workpiece is held by the expanding device in the dividing step of the laser processing method shown in fig. 3. Fig. 14 is a cross-sectional view of the workpiece divided along the processing scheduled line in the dividing step of the laser processing method shown in fig. 3. The dividing step ST4 is a step of: after the laser processing step ST3, an external force is applied to the object 1 to be processed, and the object is divided along the lines to be processed 5.

In embodiment 1, in the dividing step ST4, the workpiece 1 is removed from the holding table 10, the outer peripheral edge of the disc-shaped adhesive tape 14 having a larger diameter than the workpiece 1 is attached to the annular frame 15, and the upper surface 34 of the covering member 30 covering the workpiece 1 is attached to the center portion of the adhesive tape 14. In the dividing step ST4, the annular frame 15 is placed on the frame mounting plate 51 of the expanding device 50 with the adhesive tape 14 interposed therebetween, and as shown in fig. 13, the expanding device 50 sandwiches the annular frame 15 on the frame mounting plate 51 with the jig 52. At this time, in embodiment 1, the expanding device 50 positions the upper end of the expanding drum 53 on the same plane as the surface of the frame mounting plate 51, and brings the upper end of the expanding drum 53 into contact with the adhesive tape 14.

In embodiment 1, in the dividing step ST4, as shown in fig. 14, the expanding device 50 moves the expanding drum 53 upward by a not-shown lift cylinder, and relatively moves the annular frame 15 attached to the outer peripheral edge of the adhesive tape 14 and the workpiece 1 in the thickness direction thereof. Then, the upper end of the expansion drum 53 abuts on the adhesive tape 14, and the adhesive tape 14 expands in the planar direction, and a radial tensile force as an external force acts on the adhesive tape 14.

When a tensile force is radially applied to the adhesive tape 14 attached to the upper surface 34 of the covering member 30 covering the workpiece 1, a tensile force is also applied to the workpiece 1. Since the shield tunnel 40 is formed at a predetermined interval along the line to be processed 5 in the laser processing step ST3, the object 1 is broken starting from the shield tunnel 40 and divided along the line to be processed 5 as shown in fig. 14. In embodiment 1, the expansion drum 53 is raised to expand the adhesive tape 14 in the dividing step ST4, but the present invention is not limited to this, and the frame mounting plate 51 may be lowered, and in short, the expansion drum 53 may be raised relative to the frame mounting plate 51, and the frame mounting plate 51 may be lowered relative to the expansion drum 53.

(peeling step)

Fig. 15 is a sectional view schematically showing a peeling step of the laser processing method shown in fig. 3. Fig. 16 is a perspective view of the workpiece after the peeling step in the laser processing method shown in fig. 3. The peeling step ST5 is a step of: after the dividing step ST4, the covering member 30 covering the one surface 2 of the workpiece 1 is peeled off from the workpiece 1.

In the peeling step ST5, the work 1 having the outer edge portion divided is picked up from the adhesive tape 14, and as shown in fig. 15, the work 1 is immersed in hot water 61 heated to a temperature higher than the normal temperature in the hot water tank 60. Then, the covering member 30 is peeled off from the one surface 2 of the workpiece 1. In the present invention, the covering member 30 is peeled by immersing the workpiece 1 in the hot water 61, but the covering member 30 may be peeled by immersing the workpiece 1 in the chemical solution in the present invention. After the covering member 30 is peeled off, the workpiece 1 is taken out from the warm water tank 60, and the outer edge portion is removed as shown in fig. 16.

As described above, in the laser processing method according to embodiment 1, since the one surface 2 having a curvature of the object 1 is coated with the coating member 30 and the upper surface 34 of the coating member 30 is formed flat in the coating step ST2, the shield tunnel 40 serving as a division start point can be formed at a desired position by positioning the focal point 21 at a desired position when the laser beam 20 is irradiated in the laser processing step ST 3. As a result, the laser processing method of embodiment 1 achieves the following effects: the occurrence of a defective division of the workpiece 1 and the deterioration of the quality can be suppressed, and a defective division of the workpiece 1 having the curvature on the

surfaces

2 and 3 can be suppressed.

In the laser processing method according to embodiment 1, since the refractive index of the cured cladding member 30 is equal to the refractive index of the workpiece 1, the shield tunnel 40 serving as a division starting point can be formed at a desired position.

[ embodiment 2 ]

A laser processing method according to embodiment 2 of the present invention will be described with reference to the drawings. Fig. 17 is a flowchart illustrating a flow of the laser processing method according to embodiment 2. In fig. 17, the same components as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

The laser processing method of embodiment 2 is the same as embodiment 1 except that the peeling step ST5 is performed before the dividing step ST 4. In the peeling step ST5 of the laser processing method according to embodiment 2, the covering member 30 covering the one surface 2 of the workpiece 1 is peeled from the workpiece 1 as in embodiment 1 before the dividing step ST 4.

In the laser processing method according to embodiment 2, since the covering member 30 covers the one surface 2 having curvature of the workpiece 1 and the upper surface 34 of the covering member 30 is formed flat in the covering step ST2, the shield tunnel 40 serving as a division starting point can be formed at a desired position, and as in embodiment 1, an effect of suppressing a defective division of the workpiece 1 having curvature of the

surfaces

2 and 3 is obtained.

[ embodiment 3 ]

A laser processing method according to embodiment 3 of the present invention will be described with reference to the drawings. Fig. 18 is a perspective view illustrating a workpiece to be processed in the laser processing method according to embodiment 3. Fig. 19 is a sectional view of a main portion of the workpiece shown in fig. 18.

The laser processing method according to embodiment 3 is the same as

embodiments

1 and 2 except that the object 1-3 to be processed is different.

The object 1-3 to be processed in the laser processing method according to embodiment 3 is a wafer such as a disc-shaped semiconductor wafer or an optical device wafer having a substrate 70 made of silicon, sapphire, SiC (silicon carbide), gallium arsenide, or the like. As shown in fig. 18, the object 1-3 is formed with devices 73 in each region defined by a plurality of lines to be processed 72 formed in a lattice shape on the front surface 71 of the substrate 70. The device 73 is an Integrated Circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration). In embodiment 3, as shown in fig. 19, a plurality of spherical bumps 74 are mounted on the front surface of a device 73 in a workpiece 1-3. Bumps 74 protrude from the front side of device 73. The workpiece 1-3 is formed with a curved surface having curvature by mounting a spherical bump 74 on the front surface of the device 73. When a surface having a curvature such as a bump 74 is formed in the object 1-3 to be processed in the laser processing method according to embodiment 3 in the vicinity of the line to be processed 72, the bump 74 may come into contact with the object when the laser beam 20 is condensed. This may cause the laser beam 20 to be refracted, and thus the laser beam may not be processed to a predetermined position (depth).

In the laser processing method according to embodiment 3, since the covering member 30 covers the one surface 2 having curvature of the workpiece 1 and the upper surface 34 of the covering member 30 is formed flat in the covering step ST2, the shield tunnel 40 serving as a division starting point can be formed at a desired position, and as in embodiment 1, an effect of suppressing a defective division of the workpiece 1 having curvature of the

surfaces

2 and 3 is obtained.

The present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the scope of the present invention. In the embodiment, the shield tunnel 40 is formed at predetermined intervals along the line to be processed 5 as the predetermined laser processing, but the present invention is not limited to this, and the modified layer may be formed inside the object 1 along the line to be processed 5. The modified layer is a region having a density, a refractive index, a mechanical strength, and other physical properties different from those of the surrounding region, and examples thereof include a melt-processed region, a crack region, an insulation breakdown region, a refractive index change region, and a region in which these regions are mixed. The modified layer has a mechanical strength lower than that of the other parts of the workpiece 1.

The structure of the holding member 13 of the present invention is not limited to the structure described in the embodiment, and may be any structure as long as it can hold the other surface 3 side as in the above-described embodiment. The present invention is not limited to the expansion of the adhesive tape 14 by the expanding device 50, and may be a breaking device that divides the tape along the line 5.

Claims

1. A laser processing method for forming a workpiece having a curvature into a desired shape,

the laser processing method comprises the following steps:

a holding step of holding the workpiece;

a covering step of, after the holding step, covering the workpiece with a material that transmits the laser beam so as to flatten a surface of the workpiece having a curvature;

a laser processing step of irradiating a laser beam having a wavelength that is transparent to the material and the workpiece from a side of the workpiece coated with the material that transmits the laser beam after the coating step, and performing predetermined laser processing on the workpiece; and

and a dividing step of dividing the workpiece by applying an external force to the workpiece after the laser processing step.

2. The laser processing method according to claim 1,

the laser processing method comprises the following stripping steps: before or after the dividing step, the material coated on the surface of the workpiece having the curvature is peeled off from the workpiece.

3. The laser processing method according to claim 1 or 2,

in the laser processing step, pores and an amorphous phase surrounding the pores are formed in the object to be processed.