KR20170048969A

KR20170048969A - Laser processing method and laser processing apparatus using multi focusing

Info

Publication number: KR20170048969A
Application number: KR1020150149730A
Authority: KR
Inventors: 박정래; 이홍
Original assignee: 주식회사 이오테크닉스
Priority date: 2015-10-27
Filing date: 2015-10-27
Publication date: 2017-05-10
Also published as: TW201714694A; WO2017073907A1

Abstract

A laser processing method and a laser processing apparatus using multiple focal points are disclosed. The disclosed laser machining method comprises: machining an object to be processed placed on a stage using a laser, the method comprising: dividing a laser beam into a plurality of laser beams; Transmitting the plurality of divided laser beams to the object to form light-converging points at different depths; And processing the object by moving the laser beam relative to the stage along a line along which the object is intended to be machined, wherein the light-converging point formed at a deeper position from the surface on which the laser beam is incident, Is formed on the side of the movement of the laser beam in the line along which the laser beam is to be machined than a light-converging point formed at a shallower position.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and a laser processing method using a multi-

And more particularly, to a laser processing method and a laser processing apparatus for forming and cutting a plurality of light-converging points in an object to be processed.

The laser processing apparatus irradiates an object to be processed with a laser beam emitted from a laser oscillator by using an optical system. The object to be processed is exposed by such a laser beam to perform marking, exposure, etching, punching, scribing, Laser processing such as dicing is performed.

Recently, in order to prevent the surface of the object to be damaged, a method of processing the object by forming a light-converging point within the object to be processed having a laser beam transmissive to generate a crack has attracted attention. For example, when a high-power laser beam of a semiconductor wafer is focused to form a light-converging point, a modified region is formed near the light-converging point, and a crack is generated from the modified region. Then, when the laser beam is moved along the line to be machined of the semiconductor wafer, cracks are formed in the object, and then the object is cut off naturally or by an external force to expand the crack to the surface of the semiconductor wafer.

However, in the conventional laser machining method and laser machining apparatus, the light converging points are arranged in the transverse direction, and the light converging points are formed at the same depth, so that the number of processing required for cutting the object is large, have.

The present invention provides a laser machining method and a laser machining apparatus for forming and processing a plurality of light-converging points in an object to be processed.

According to another aspect of the present invention, there is provided a laser processing method for processing an object to be processed placed on a stage using a laser, comprising: dividing a laser beam into a plurality of laser beams; Transmitting the plurality of divided laser beams to the object to form light-converging points at different depths; And processing the object by moving the laser beam relative to the stage along a line along which the object is intended to be machined, wherein the light-converging point formed at a deeper position from the surface on which the laser beam is incident, Is formed on the side of the movement of the laser beam in the line along which the laser beam is to be machined than a light-converging point formed at a shallower position.

The step of dividing the laser beam into a plurality of laser beams may split the laser beam through a plurality of lenses having different focal lengths from each other.

The plurality of lenses may have a focal length greater than that of a lens positioned in a moving direction of the laser beam, the lens being positioned in a direction opposite to the moving direction of the laser beam.

The step of dividing the laser beam into a plurality of laser beams may split the laser beam by passing the laser beam through a diffractive optical element lens.

The step of moving the laser beam relative to the stage along the line to be machined to process the object may move the stage or scan the laser beam to machine the object.

The object to be processed may be a transparent medium.

A laser processing method according to an embodiment of the present invention is a laser processing method for processing an object to be processed placed on a stage by using a laser. The laser processing method includes passing a laser beam through a spherical lens having a plurality of curved surfaces, Dividing the laser beam into a plurality of laser beams; Transmitting the plurality of divided laser beams to the object to form light-converging points at different depths; And moving the laser beam relatively to the stage along a line to be machined to machine the object.

The plurality of curved surfaces of the spherical lens may have different focal lengths.

A laser processing apparatus according to an embodiment of the present invention is a laser processing apparatus for processing an object to be processed placed on a stage using a laser, comprising: a laser light source for emitting a laser beam; And an optical system for dividing the laser beam into a plurality of laser beams and forming light-converging points at different depths of the object to be processed, wherein the light-converging point is formed at a position deeper from the surface on which the laser beam is incident The point is formed closer to the moving direction of the laser beam in the line along which the laser beam is intended to be machined than the light-converging point formed at a shallower position.

The optical system may include a plurality of lenses having different focal distances from each other.

The optical system may include a diffractive optical element lens.

And the stage moves relative to the laser beam to machine the object.

The laser beam can be moved relative to the stage along the line to be processed.

A laser processing apparatus according to an embodiment of the present invention is a laser processing apparatus for processing an object to be processed placed on a stage using a laser, comprising: a laser light source for emitting a laser beam; And a spherical lens having a plurality of curved surfaces for dividing the laser beam into a plurality of laser beams and forming light-converging points at different depths of the object, wherein the spherical lens has a plurality of curved surfaces As shown in FIG.

And the stage moves relative to the laser beam to machine the object.

And a scanner for relatively moving the laser beam along the line to be processed with respect to the stage.

According to the embodiment of the present invention, it is not necessary to form a plurality of light-converging points in the depth direction of the object within the object to be processed repeatedly in the process of cutting or the like, so that the time required can be shortened .

Further, according to the embodiment of the present invention, the light-converging point formed at a deeper position from the surface on which the laser beam is incident is formed closer to the moving direction of the laser beam than the light-converging point formed at a shallower position, It is possible to prevent interference by the modified region.

1 schematically shows a laser processing apparatus according to an exemplary embodiment of the present invention.
2A to 2C show a laser machining method according to an embodiment of the present invention.
3A to 3D illustrate a laser processing method according to another embodiment of the present invention.
4A to 4C show a laser machining method according to another embodiment of the present invention.
Figure 5 shows a processed object processed according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

1 schematically shows a laser processing apparatus according to an exemplary embodiment of the present invention.

1, the laser processing apparatus according to the present embodiment includes a laser light source 110 for emitting a laser beam L, a beam delivery system 120, a scanner 130, Stage 160 as shown in FIG.

The laser light source 110 is a means for emitting a laser. The laser light source 110 can be variously classified into a gas, a liquid, a solid laser light source, or the like depending on the kind of a material generating the laser.

The laser beam L emitted from the laser light source 110 is incident on the beam delivery system 120. The beam transmission system 120 is for transmitting the laser beam L emitted from the laser light source 110 along a predetermined path, and may include, for example, a plurality of mirrors or an optical cable .

The laser beam L having passed through the beam delivery system 120 is incident on the scanner 130. The scanner 130 performs a machining operation on the object 150 by scanning the laser beam L onto the object 150. [ The scanner 130 can position the laser beam L in an area to be processed and can control the linear motion of the laser beam L. [

The optical system 140 functions to adjust the focus of the laser beam L so that the laser beam L passed through the scanner 130 can form a light-converging point inside the object 150. Specific embodiments, roles and operating principles of the optical system 140 will be described below

The object to be processed 150 may be formed of a transparent medium through which the laser beam L can pass.

The object to be processed 150 is seated and fixed on the stage 160. The object 150 can be processed by the movement of the stage 160 on which the object 150 is placed when the laser beam L passing through the optical system 140 is irradiated on the object 150. [ That is, if the stage 160 is moved to a desired shape while continuously irradiating the laser beam L onto the object 150, the object 150 to be processed can be processed.

In addition, even when the laser beam L is scanned to a desired shape using the scanner 130 while the stage 160 is fixed, the object 150 can be processed in a desired shape. That is, the path of the laser beam L is changed by the movement of the mirror included in the scanner 130, and the object 150 can be processed through the movement relative to the object 150 on the stage 160 .

Hereinafter, a process of cutting the object 150 using the laser processing apparatus shown in Fig. 1 will be described with reference to Figs. 2A to 5B.

2A to 2C show a laser machining method according to an embodiment of the present invention.

2A shows a state in which the laser beam emitted from the laser processing apparatus is divided into a plurality of laser beams L1 and L2 to form first and second light-converging points P1 and P2 inside the object to be processed 250, 1 and the second light-converging points P1 and P2 move.

Referring to FIG. 2A, the object to be processed 250 is first prepared. The object to be processed 250 may be formed of a transparent medium through which the laser beam L can pass.

The first and second lenses 10 and 20 can be used as the optical system 140 of the laser processing apparatus shown in Fig. The laser beam L emitted from the scanner 130 in FIG. 1 may be divided into first and second laser beams L1 and L2 after passing through the first and second lenses 10 and 20. The focal length of the second lens 20 positioned in the moving direction of the laser beam L is different from the focal length of the second lens 20 in the moving direction of the laser beam L2, The focal length may be larger than that of the first lens 10 positioned in the opposite direction.

The curvature of the first lens 10 and the curvature of the second lens 20 may be different from each other so that the first lens 10 and the second lens 20 have different focal lengths. Alternatively, even if the first lens 10 and the second lens 20 have the same curvature, the refractive index of the first lens 10 and the refractive index of the second lens 20 may be different from each other. Alternatively, the curvature and the refractive index of the first lens 10 and the second lens 20 may be different from each other.

The first and second laser beams L1 and L2 are transmitted through the object to be processed 250 to form first and second light-converging points P1 and P2, respectively. The focal length of the second lens 20 is larger than the focal length of the first lens 10 so that the second focal point P2 is closer to the focal point of the object 250 than the first focal point P1. 1 and the second laser beams L1, L2 may be formed at a deeper position from the incident plane.

The second lens 20 having a focal length larger than that of the first lens 10 can be positioned on the movement direction of the laser beams L1 and L2 from the first lens 10 on the line to be processed S have. Accordingly, the second light-converging point P2 can be formed in the moving direction of the laser beams L1 and L2 more than the first light-converging point P1 in the line to be processed S.

As described above, as the first and second light-converging points P1 and P2 are formed in the object 250, the modified region can be formed around the first and second light-converging points P1 and P2. A crack can be formed from the modified region. Since the second light-converging point P2 is formed closer to the moving direction of the laser beams L1 and L2 at the line S to be machined than the first light-converging point P1, the second light- Can be formed without being disturbed by the modified region formed by the point P1.

2B is a sectional view taken along the line I-I 'in FIG. 2A.

2B, when the first and second light-converging points P1 and P2 are formed at different depths within the object to be processed 250 as shown in FIG. 2A, the first and second light- P1 and P2 relatively move along the line along which the work is to be performed. Accordingly, the first and second light-converging points P1 and P2 move in a certain direction (i.e., the direction opposite to the moving direction of the object to be processed). The movement of the first and second light-converging points P1 and P2 can be controlled by driving the scanner (130 in FIG. 1). On the other hand, the movement of the first and second light-converging points P1 and P2 can be controlled also by the movement of the stage (160 in Fig. 1) on which the object 250 is placed.

In this process, in accordance with the movement of the first and second light-converging points P1 and P2, crack lines 211 and 212 are formed along the line to be processed S in the interior of the object to be processed 250, Cracks can be extended from the heat 211, 212 to the upper surface and the lower surface of the object 250. When the movement of the first and second light-converging points P1 and P2 within the object to be processed 250 ends, the cracks 211 and 212 are formed in the object 250 as shown in FIG. The formation is completed.

In the above embodiment, the laser processing method and the laser processing apparatus are described with the two condensing points P1 and P2 having different forming depths from the two lenses 10 and 20 having different focal lengths. However, the present invention is not limited thereto, It is also possible to process the object to be processed by forming more than two lenses and two or more light-converging points.

According to the embodiment, the object to be processed 250 is formed by forming a plurality of light-converging points P1 and P2 at different depths within the object to be processed 250, Therefore, the time required can be shortened. The light-converging point P2 formed at a deeper position from the plane on which the laser beams L1 and L2 are incident is shorter than the light-converging point P1 formed at a shallower position by the laser beams L1 and L2 at the line to be processed S, The second light-converging point P2 at the time of processing the object 250 can be formed without being disturbed by the modified region formed from the first light-converging point P1.

3A to 3D illustrate a laser processing method according to another embodiment of the present invention.

3A shows a state in which the laser beam emitted from the laser processing apparatus is divided into a plurality of laser beams L1 ', L2', and L3 'to form first, second, and third light-converging points P1' The first, second and third light-converging points P1 ', P2' and P3 'move in the state where the light-converging points P2' and P3 'are formed.

Referring to FIG. 3A, the diffractive optical element 170 and the focusing lens 175 can be used as the optical system 140 of the laser processing apparatus shown in FIG. 1, the laser beam L from the scanner 130 may be split into first, second and third laser beams L1 ', L2', L3 'after passing through the diffractive optical element 170 have.

The structure of the diffraction optical element 170 will now be described in more detail. Unlike a refractive optical element such as a generally used convex lens, a diffractive optical element performs a function of a lens through a plurality of diffraction gratings formed on a surface thereof. Fig. 3B illustrates the structure of this diffractive optical element 170. Fig. 3B, the diffractive optical element 170 has a shape in which the surface 172 of a general convex lens is divided at a constant height and the lens surface shape of each divided section is transferred onto the substrate 171 as it is. Generally, since the portion of the convex lens where the light is deflected is directly on the surface of the lens, the function of the general lens can be performed as it is even if the side on which the focus is formed is cut as shown in FIG. 3B.

Referring again to FIG. 3A, the first, second and third laser beams L1 ', L2', and L3 'having passed through the diffraction optical element 170 pass through the focusing lens 175, The first, second, and third light-converging points P1 ', P2', and P3 'are formed in the first and second light-incident portions 350 and 350, respectively. The first, second and third light-converging points P1 ', P2', and P3 'may be formed at different depths in the object 350. The second light-converging point P2 'is formed at a position deeper than the first light-converging point P1' from the upper surface of the object 350 and the third light-converging point P3 ' The position and shape of the diffractive optical element 170 can be adjusted so as to be formed at a deeper position than the second light-converging point P2 '.

Further, the second light-converging point P2 'is located on the side of the movement of the laser beam in the movement direction of the laser beam in the line S to be processed and the first light-converging point P1' The position and shape of the diffractive optical element 170 can be adjusted so as to be positioned closer to the moving direction of the laser beam than the second light-converging point P2 '.

As the first, second and third light-converging points P1 ', P2' and P3 'are formed in the object 350, the first, second and third light-converging points P1' and P2 ' ', P3'), and a crack may be formed from the modified region. Since the second light-converging point P2 'is formed on the movement direction of the laser beam more than the first light-converging point P1' in the line S to be processed, the second light-converging point P2 ' Lt; RTI ID = 0.0 > P1 '). &Lt; / RTI > In addition, since the third light-converging point P3 'is formed on the side of the laser beam to be moved in the movement direction of the laser beam than the second light-converging point P2' in the line S to be processed, the third light- Can be formed without being disturbed by the modified regions formed by the second regions P2 '.

3C is a sectional view taken along line II-II 'in FIG. 3A.

Referring to FIG. 3C, the first, second and third light-converging points P1 ', P2' and P3 'are formed at different depths in the interior of the object 350, as shown in FIG. 3A The first, second and third light-converging points P1 ', P2' and P3 'are relatively moved along the line along which the workpiece is to be machined. Accordingly, the first, second, and third light-converging points P1 ', P2', and P3 'move in a certain direction (that is, the direction opposite to the moving direction of the object). The movement of the first, second and third light-converging points P1 ', P2' and P3 'can be controlled by driving the scanner (130 in FIG. 1). The movement of the first, second and third light-converging points P1 ', P2' and P3 'can also be controlled by the movement of the stage (160 in FIG. 1) on which the object 350 is placed.

In this process, in accordance with the movement of the first, second and third light-converging points P1 ', P2' and P3 ', crack lines 311, 312 and 313 are arranged in the interior of the object 350, And the cracks can be extended from the crack lines 311, 312, and 313 to the upper surface and the lower surface of the object to be processed 350. When the movement of the first, second, and third light-converging points P1 ', P2', and P3 'within the object to be processed 350 ends as described above, The formation of the crack lines 311, 312, and 313 is completed.

In the above embodiment, the laser beam is divided into three by using the diffraction optical element 170 and the focusing lens 175, and three light-converging points P1 'and P2' P3 'are formed in the object 350 A laser processing method and a laser processing apparatus for processing the object 350 have been described. However, the present invention is not limited to this, and the object to be processed may be processed by dividing the laser beam into three or more laser beams through the diffractive optical element and forming three or more light-converging points in the object.

According to the embodiment, a plurality of light-converging points P1 'and P2' P3 'are formed at different depths within the object to be processed 350 to process the object 350, The time required can be shortened. Further, the light-converging point formed at a deeper position from the plane on which the laser beams L1 ', L2', and L3 'are incident is formed closer to the moving direction of the laser beam in the line to be processed S than the light- , The light-converging point formed at a deeper position at the time of processing the object 350 can be formed without being disturbed by the modified region formed from the light-converging point formed at a shallower position.

4A to 4B show a laser processing method according to another embodiment of the present invention.

4A shows a state in which the laser beam emitted from the laser processing apparatus is divided into a plurality of laser beams L1 ", L2", and L3 ", and the first, second, and third light-converging points P1" Second, and third light-converging points P1 ", P2 ", and P3 "

Referring to FIG. 4A, the spherical lens 180 can be used as the optical system 140 of the laser processing apparatus shown in FIG. The laser beam L from the scanner 130 in FIG. 1 may be divided into first, second and third laser beams L1 ", L2", L3 "after passing through the spherical lens 180.

The spherical lens 180 may have a plurality of curved surfaces 181, 182 and 183 and the plurality of curved surfaces 181, 182 and 183 may have different focal lengths. For example, the first curved surface 181 may have a larger focal distance than the second curved surface 182, and the second curved surface 182 may have a larger focal distance than the third curved surface 183. Accordingly, the first light-converging point P1 "formed by the first laser beam L1" divided by the first curved surface 181 is divided into the second laser beam L2 "divided by the second curved surface 182, The second light-converging point P2 " formed by the second light-converging point P2 " The second light-converging point P2 "formed by the second laser beam L2" divided by the second curved surface 182 is the third laser beam L3 "divided by the third curved surface 183, Converging point P3 ", which is formed at a position closer to the surface of the object 450 than the second light-converging point P3 "

The curved surfaces 181, 182, and 183 may have different curvatures so that the spherical lens 180 has a different focal length from each of the plurality of curved surfaces 181, 182, and 183. For example, the first curved surface 181 may have a greater curvature than the second curved surface 182 and the third curved surface 183, and the second curved surface 182 may have a curvature larger than that of the third curved surface 183 .

As described above, since the first, second and third light-converging points P1 ", P2" and P3 "are formed in the object 450, the first, second and third light-converging points P1" &Quot;, P3 "), and a crack may be formed from the modified region.

4B is a cross-sectional view taken along line III-III 'of FIG. 4A.

4B, when the first, second, and third light-converging points P1 ", P2", and P3 "are formed at different depths in the interior of the object 450 as shown in FIG. 4A, The first, second and third light-converging points P1 ", P2 ", and P3 " Accordingly, the first, second, and third light-converging points P1 ", P2", and P3 "move in a certain direction (that is, the direction opposite to the moving direction of the object). The movement of the first, second and third light-converging points P1 ", P2" and P3 'can be controlled by driving the scanner (130 in FIG. 1). On the other hand, the movement of the first, second and third light-converging points P1 ", P2" and P3 "can also be controlled by the movement of the stage (160 in FIG. 1) on which the object 450 is placed.

In this process, in accordance with the movement of the first, second and third light-converging points P1 ", P2" and P3 ", the crack columns 411, 412, 413 are arranged in the interior of the object 450, And the cracks can be extended from the crack lines 411, 412, and 413 to the upper and lower surfaces of the object 450. When the movement of the first, second, and third light-converging points P1 ", P2", and P3 "within the object to be processed 350 ends as described above, The formation of the crack lines 411, 412 and 413 is completed.

In the above embodiment, the laser beam is divided into three parts using the spherical lens 180 having a plurality of curved surfaces 181, 182 and 183 and three light-converging points P1 " and P2 " P3 &Quot;) to form a workpiece 450, and a laser processing apparatus and a laser processing apparatus for processing the object 450 are described. However, the present invention is not limited to this, and the object to be processed may be processed by dividing the laser beam into three or more laser beams through spherical lenses having three or more curved surfaces and forming three or more light-converging points in the object.

According to this embodiment, a plurality of light-converging points P1 " and P2 " P3 " are formed at different depths in the object to be processed 450 to process the object 450, The time required can be shortened.

Figure 5 illustrates a processed object 150 ', 150 ", processed in accordance with an exemplary embodiment of the present invention.

5, crack lines 211, 212, 311, 312, 313, 411, 412 and 413 are formed in the object to be processed 250, 350 and 450 along a line S to be processed, 350, 450 by braking when an impact is applied to the object to be processed 250, 350, 450 naturally or externally in a state where the object 150 &Quot;).

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

110 ... Laser light source 120 ... Beam delivery system
130 ... Scanner 140 ... Optical system
150, 150, 150, 250, 350, 450,
160 ... Stage L ... Laser beam
L1, L1 'L1 "... First laser beam L2, L2'L2" ... The second laser beam L3, L3 'L3 "... the third laser beam P1, P1'P1" ... The first light-converging point P2, P2 'P2 ", the second light-converging point P3, P3'P3" The third light-converging point S ... Line to be processed 10 ... The first lens 20 ... The second lens
211, 212, 311, 312, 313, 411, 412, 413 ... Crack heat
170 ... Diffractive optical element 171 ... Board
172 ... Surface of convex lens 180 ... Spherical lens
181 ... The first curved surface 182 ... The second curved surface
183 ... The third curved surface

Claims

1. A laser processing method for processing an object to be processed placed on a stage using a laser,
Dividing the laser beam into a plurality of laser beams;
Transmitting the plurality of divided laser beams to the object to form light-converging points at different depths; And
And moving the laser beam relatively to the stage along a line to be machined to machine the object,
Converging point formed at a deeper position from the surface on which the laser beam is incident is formed closer to the moving direction of the laser beam in the line along which the laser beam is to be machined than a light-converging point formed at a shallower position.

The method according to claim 1,
Wherein dividing the laser beam into a plurality of laser beams comprises passing the laser beams through a plurality of lenses having different focal distances from each other to divide the laser beam.

3. The method of claim 2,
Wherein the plurality of lenses has a focal length greater than a lens positioned in a direction of movement of the laser beam, the lens being positioned in a direction opposite to the direction of movement of the laser beam.

The method according to claim 1,
Wherein dividing the laser beam into a plurality of laser beams comprises passing the laser beam through a diffractive optical element lens to divide the laser beam.

The method according to claim 1,
Wherein the step of moving the laser beam relative to the stage along the line to be machined to process the object comprises moving the stage or scanning the laser beam to process the object.

The method according to claim 1,
Wherein the object to be processed is a transparent medium.

1. A laser processing method for processing an object to be processed placed on a stage using a laser,
Passing a laser beam through a spherical lens having a plurality of curved surfaces to divide the laser beam into a plurality of laser beams having different focal lengths;
Transmitting the plurality of divided laser beams to the object to form light-converging points at different depths; And
And moving the laser beam relative to the stage along a line to be machined to machine the object to be processed.

8. The method of claim 7,
Wherein the plurality of curved surfaces of the spherical lens have different focal lengths.

8. The method of claim 7,
Wherein the step of moving the laser beam relative to the stage along the line to be machined to process the object comprises moving the stage or scanning the laser beam to process the object.

A laser processing apparatus for processing an object to be processed placed on a stage using a laser,
A laser light source for emitting a laser beam;
And an optical system for dividing the laser beam into a plurality of laser beams and forming light-converging points at different depths of the object,
Converging point formed at a deeper position from the surface of the object to be processed on which the laser beam is incident is formed closer to the moving direction of the laser beam on a line to be processed than a light-converging point formed at a shallower position.

11. The method of claim 10,
Wherein the optical system includes a plurality of lenses having different focal distances from each other.

12. The method of claim 11,
Wherein the plurality of lenses has a focal length greater than that of a lens positioned in a moving direction of the laser beam, the lens being positioned in a direction opposite to the moving direction of the laser beam.

11. The method of claim 10,
Wherein the optical system includes a diffractive optical element lens.

11. The method of claim 10,
Wherein the stage relatively moves relative to the laser beam to machine the object.

11. The method of claim 10,
And a scanner for moving the laser beam relative to the stage along the line to be machined.

A laser processing apparatus for processing an object to be processed placed on a stage using a laser,
A laser light source for emitting a laser beam;
And a spherical lens having a plurality of curved surfaces for dividing the laser beam into a plurality of laser beams and forming light-converging points at different depths of the object,
Wherein the spherical lens is formed of a plurality of curved surfaces having different focal lengths.

17. The method of claim 16,
Wherein the plurality of curved surfaces of the spherical lens have different focal lengths.

17. The method of claim 16,
Wherein the stage relatively moves relative to the laser beam to machine the object.

17. The method of claim 16,
Further comprising a scanner for relatively moving the laser beam along the line to be processed with respect to the stage.