Laser processing device and laser processing method

Abstract

To provide a laser processing device that uses branch laser light and can perform laser processing more uniformly in a short time.SOLUTION: A laser processing device comprises: a laser light source which emits laser light; a branch mechanism which branches the laser light into two or more branched laser beams; a 4f optical system which focuses a branched laser beam on a first focus; a blocking mechanism which blocks the branched laser beam at the first focus according to predetermined timing; and a condenser lens which focuses the branched laser beam, having passed through the 4f optical system, on a workpiece.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] In the field of semiconductors, wafers (semiconductor wafers) are known that form multiple devices using a laminate consisting of a low-dielectric-constant insulating film (low-k film) and a functional film that forms circuits on the surface of a substrate such as silicon.

[0003] In such a wafer, a plurality of devices are partitioned in a lattice pattern by lattice streets, and the individual devices are manufactured by dividing the wafer along the planned dividing lines.

[0004] Low-k films tend to peel easily, so dicing using a blade can result in the film peeling off. To address this issue, there is a method in which two first grooves that divide the low-k film are formed on both sides of the intended separation area using laser ablation, and then a second groove is formed between the two first grooves.

[0005] When performing laser processing on a workpiece, it is required that the processing time be short and that the thermal impact on divided devices be suppressed. To shorten the processing time, it is possible to perform the processing in one pass (one processing feed), but in this case the energy per beam must be increased. If the energy per beam is increased, heat is more likely to be generated during laser processing, increasing the impact on the device. On the other hand, in order to reduce the thermal impact on the device, it is possible to reduce the energy per beam and perform laser processing in multiple passes. However, in this case it becomes difficult to shorten the processing time.

[0006] As a technology for solving these problems, Patent Document 1 discloses a laser optical system that includes a plurality of optical element units arranged in series on the optical path of laser light, each having a half-wave plate and a Wollaston prism, a wave plate rotation mechanism that rotates the half-wave plate around the optical path, and a prism rotation mechanism that rotates the Wollaston prism around the optical path, and in which the plurality of optical element units cause the laser light to be incident on the Wollaston prism via the half-wave plate and split into two branch laser light beams. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2023-148477 Summary of the Invention [Problem to be solved by the invention]

[0008] However, with the technology of Patent Document 1, there is a risk that the number of overlapping laser spot groups will differ between the processing start end and processing end end, resulting in uneven processing in some areas. Therefore, when processing non-orthogonal devices such as hexagonal devices, processing without branching the laser beam is required, which may increase the number of passes compared to normal processing.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a laser processing apparatus and a laser processing method that use branched laser light and are capable of performing laser processing more uniformly in a short time. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention proposes the following means. <1> The laser processing apparatus according to aspect 1 of the present invention comprises: a laser light source that emits laser light; a branching mechanism for branching the laser beam into two or more branched laser beams; a 4f optical system that focuses the branched laser beams at a first focal point; a blocking mechanism that blocks the branched laser beam at the first focal point in accordance with a predetermined timing; a condenser lens that condenses the branched laser beams after passing through the 4f optical system onto a workpiece; Equipped with. <2> A second aspect of the present invention is the laser processing apparatus of the first aspect, The blocking mechanism may be a beam shutter capable of blocking the branched laser beam at time intervals of 10 ms or less. <3> A third aspect of the present invention is the laser processing apparatus of the first aspect, The shielding mechanism may be an electro-optical element and a polarizing beam splitter. <4> A fourth aspect of the present invention is the laser processing apparatus according to the first or second aspect, The branching mechanism may be arranged in series on the optical path of the laser light, and may include an optical element having a half-wave plate and a Wollaston prism, a wave plate rotation mechanism that rotates the half-wave plate around the optical path, and a prism rotation mechanism that rotates the Wollaston prism around the optical path. <5> A fifth aspect of the present invention is the laser processing apparatus of the first or second aspect, The branching mechanism may be a liquid crystal on silicon. <6> According to a sixth aspect of the present invention, in the laser processing apparatus according to the fourth aspect, the branching mechanism may further include a laser beam adjusting unit that adjusts the branching direction of the branched laser beam. <7> A laser processing method according to a seventh aspect of the present invention uses the laser processing apparatus according to the first aspect, and processes the workpiece by arranging the spots of the branched laser beams linearly in the processing progression direction. <8> Aspect 8 of the present invention is the laser processing method of aspect 7, The workpiece has a region to be machined and a region not to be machined, The blocking mechanism may be used to block the branched laser beam in the non-processing region. <9> A ninth aspect of the present invention is the laser processing method of the seventh aspect, The workpiece has a region to be processed and a region that has already been processed, The blocking mechanism may be used to block the branched laser beam in the processed region. <10> A tenth aspect of the present invention is the laser processing method of the seventh aspect, the workpiece has a high-rate region made of a material with a high processing rate and a low-rate region made of a material with a low processing rate, The blocking mechanism may be used to block the branched laser beams so that the number of spots in the low rate region is greater than the number of spots in the high rate region. [Effects of the Invention]

[0011] According to the above aspects of the present invention, a laser processing apparatus and a laser processing method are provided that use branched laser light and enable more uniform laser processing in a short time. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a laser processing device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of a wafer that is a workpiece. [Figure 3] FIG. 10 is an explanatory diagram for explaining laser processing along the outgoing direction X1. [Figure 4] 10 is an explanatory diagram for explaining laser processing along the backward direction X2. FIG. [Figure 5] FIG. 1 is a block diagram illustrating an example of a laser optical system. [Figure 6] 1A to 1C are diagrams for explaining a laser processing method according to a first embodiment. [Figure 7] FIG. 10 is a diagram for explaining a first modified example of the laser processing method. [Figure 8] FIG. 10 is a diagram for explaining a second modification of the laser processing method. [Figure 9] FIG. 10 is a diagram for explaining a third modification of the laser processing method. [Figure 10] FIG. 10 is a block diagram of a first modified example of the laser optical system. [Figure 11] FIG. 10 is a block diagram of a second modified example of the laser optical system. [Figure 12] FIG. 10 is a block diagram of a third variation of the laser optical system. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing apparatus and a laser processing method according to an embodiment of the present invention will be described below with reference to the drawings.

[0014] [Laser processing overview] In this embodiment, the energy per beam is reduced by branching the laser beam for processing emitted from the laser light source into multiple beams. Furthermore, by using the multiple branched laser beams, laser processing can be performed in one pass. Additionally, when the spot of the branched laser beam moving along the processing direction enters a non-processing area of ​​the workpiece, the branched laser beam is blocked to prevent the branched laser beam from being emitted (irradiated) onto the non-processing area. This makes it possible to reduce unevenness in processing at the processing start and processing end.

[0015] First Embodiment [Laser processing equipment] Next, an example of a laser processing device will be described with reference to FIG.

[0016] FIG. 1 is a schematic diagram of a laser processing apparatus according to one embodiment of the present invention. As shown in FIG. 1, the laser processing apparatus 1 performs laser processing (laser ablation processing) on ​​a wafer W1 as a pre-process before dividing the wafer W1 into multiple chips C (see FIG. 2). Here, the X, Y, and Z directions in the figure are defined. The X and Y directions are directions along the surface W1a of the wafer W1, which will be described later. The Y direction is a direction that intersects (e.g., is perpendicular to) the X direction. The Z direction is a direction that intersects (e.g., is perpendicular to) the X and Y directions and is the thickness direction of the wafer W1. The X direction corresponds to the processing feed direction in the present invention.

[0017] Figure 2 is a plan view of a wafer W1, which is a workpiece. As shown in Figure 2, the wafer W1 is a laminate in which a low-k film and a functional film that forms a circuit are laminated on the surface of a substrate such as silicon. The wafer W1 is divided into multiple regions by multiple streets S (planned division lines) arranged in a grid pattern. Each of these divided regions is provided with a device D that constitutes a chip C.

[0018] The laser processing device 1 performs laser processing on the wafer W1 along each street S, as indicated by the bracketed numbers (1) to (4) in the figure, thereby removing the low-k film, a portion of the substrate, and the like.

[0019] At this time, in order to reduce the processing time of the laser processing of the wafer W1, the laser processing apparatus 1 may alternately switch the relative movement direction when moving the laser optical system 14 described below in the X direction relative to the wafer W1 for each street S.

[0020] For example, when laser processing is performed along odd-numbered streets S such as those indicated by parenthesized numbers (1) and (3) in Fig. 2, the laser optical system 14 is moved relative to the wafer W1 in a forward direction X1, which is one side in the X direction. When laser processing is performed along even-numbered streets S such as those indicated by parenthesized numbers (2) and (4) in Fig. 2, the laser optical system 14 is moved relative to the wafer W1 in a backward direction X2, which is opposite to the forward direction X1.

[0021] FIG. 3 is an explanatory diagram for explaining laser processing along the forward direction X1. 4 is an explanatory diagram for explaining laser processing along the even-numbered backward direction X2. As shown in FIGS. 3 and 4, in this embodiment, the laser processing involves simultaneously (concurrently) performing edge cutting, which forms two parallel, thin first grooves G1 along the street S so as not to affect the chip side, and hollowing, which removes unnecessary material inside the first grooves G1 to expose the base material (e.g., silicon). The edge cutting is laser processing performed using two first laser beams (split lasers) LA1 and LA2, and forms two parallel edge cutting grooves G1 (two first grooves G1; ablation grooves) along the street S.

[0022] The hollowing process is a laser process for forming a hollow groove (second groove) G2 between the two first grooves G1 formed by the edge cutting process. In this embodiment, the hollowing process is performed using second branch laser beams (line lasers) LB1, LB2, LB3, and LB4 having a larger diameter than the two first branch laser beams LA1 and LA2.

[0023] In the laser processing device 1, in either case where the laser optical system 14 is moved relative to the wafer W1 in the forward direction X1 or in the backward direction X2, the edge cutting process is performed before the hollowing process.

[0024] As shown in FIG. 1, the laser processing device 1 includes a control device 10, a first laser light source 12A, a second laser light source 12B, a laser optical system 14, a microscope 20, and a relative movement mechanism 22.

[0025] Under the control of the control device 10, the stage ST is moved in the X and Y directions by a relative movement mechanism 22 and rotated around the Z axis.

[0026] The first laser light source 12A emits laser light LA, which is a pulsed laser light having conditions (laser light wavelength, pulse width, repetition frequency, etc.) suitable for edge cutting, to the laser optical system 14. The second laser light source 12B emits laser light LB, which is a pulsed laser light having conditions (laser light wavelength, pulse width, repetition frequency, etc.) suitable for center cutting, to the laser optical system 14.

[0027] The laser optical system 14 forms two first branched laser beams LA1 and LA2 for edge cutting based on the laser beam LA from the first laser light source 12A. The laser optical system 14 also forms multiple second branched laser beams LB1, LB2, LB3, and LB4 for center cutting based on the laser beam LB from the second laser light source 12B. The laser optical system 14 then emits (irradiates) the two first branched laser beams LA1 and LA2 from the first condenser lens 16 toward the street S. The laser optical system 14 also selectively emits (irradiates) the second branched laser beams LB1, LB2, LB3, and LB4 from the second condenser lens 18B toward the street S under the control of the control device 10. The laser optical system 14 is moved in the Y and Z directions by the relative movement mechanism 22 under the control of the control device 10.

[0028] The microscope 20 is fixed to the laser optical system 14 and moves integrally with the laser optical system 14. The microscope 20 photographs an alignment reference (not shown) formed on the wafer W1 before the edge cutting and hollowing processes. The microscope 20 also photographs the two first grooves G1 and the second grooves G2 formed along the street S by the edge cutting and hollowing processes. The photographed image (image data) taken by the microscope 20 is output to the control device 10, which displays it on a monitor (not shown). Based on this image, the control device 10 controls the shielding mechanism 70, which will be described later, from the positional relationship between the position of the spot of the branched laser light and the region to be processed.

[0029] The relative movement mechanism 22 includes an XYZ actuator and a motor, and moves the stage ST in the XY directions, rotates it about a rotation axis, and moves the laser optical system 14 in the Z direction under the control of the control device 10. This allows the relative movement mechanism 22 to move the laser optical system 14 relative to the stage ST and the wafer W1. Note that the method of relative movement is not particularly limited as long as it is possible to move the laser optical system 14 relative to the stage ST (wafer W1) in each direction (including rotation).

[0030] The control device 10 is configured, for example, by a personal computer, and includes various processors (for example, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit)), a memory, and a storage device. The various functions of the control device 10 may be realized by one processor, or may be realized by multiple processors of the same or different types. The control device 10 comprehensively controls the operations of the first laser light source 12A, the second laser light source 12B, the laser optical system 14, the microscope 20, the relative movement mechanism 22, the shielding mechanism 70, etc.

[0031] By driving the relative movement mechanism 22, it is possible to align the laser optical system 14 with the processing start end, which is one end of the street S to be processed, and to relatively move the laser optical system 14 in the X direction (the forward direction side X1 or the backward direction side X2) along the street S. In addition, by driving the relative movement mechanism 22 to rotate the stage ST by 90°, it is possible to make each street S along the Y direction of the wafer W1 parallel to the X direction, which is the processing feed direction.

[0032] [Laser optics] Next, an example of the laser optical system 14 will be described with reference to FIG. 5. FIG. 5 is a block diagram showing an example of the laser optical system. In the following description, an example in which laser light LB from the second laser light source 12B is branched will be described, but the present invention is also applicable to laser light LA. The first condenser lens 16 is disposed, for example, between the second condenser lens 18A and the second condenser lens 18B. In other words, the second condenser lenses 18A and 18B are disposed so as to sandwich the first condenser lens 16 therebetween. The second condenser lens 18A is disposed on the backward direction side X2 with respect to the first condenser lens 16. The second condenser lens 18B is disposed on the forward direction side X1 with respect to the first condenser lens 16. The branching of the second laser light LB is similar on the second condenser lens 18A side and the second condenser lens 18B side, and therefore, in the following description, the second condenser lenses 18A and 18B will be described as the condenser lens 18.

[0033] The laser optical system 14 includes a branching mechanism 60 that branches the laser light LB into two or more branched laser lights LB1, LB2, LB3, and LB4, a 4f optical system 30 that focuses the branched laser lights LB1, LB2, LB3, and LB4 at a first focal point F1, a shielding mechanism 70 that shields the branched laser lights LB1, LB2, LB3, and LB4 at the first focal point F according to a predetermined timing, and a focusing lens 18 that focuses the branched laser lights LB1, LB2, LB3, and LB4 on the workpiece after passing through the 4f optical system 30.

[0034] The branching mechanism 60 may be, for example, a diffractive optical element, a refractive optical element, a prism, or a combination thereof. In this embodiment, the branching mechanism 60 is described as including optical element units U1, U2, and U3 arranged in series on the optical path of the laser beam LB, each of which includes half-wave plates WB1, WB2, and WB3 and Wollaston prisms WP1, WP2, and WP3; a wave plate rotation mechanism that rotates the half-wave plates WB1, WB2, and WB3 around the optical path; and a prism rotation mechanism that rotates the Wollaston prisms WP1, WP2, and WP3 around the optical path. In this example, two or more of the optical element units U1 to U3 for branching the laser beam LB are selectively inserted and removed from the optical path of the laser beam LB and arranged in series on the optical path, thereby enabling branched laser beams to be output.

[0035] Optical element units U1 to U3 for splitting the laser light LB are disposed between the optical elements for adjusting the laser light LB and the condenser lens 18. The optical element units U1 to U3 include half-wave plates WB1 to WB3 and Wollaston prisms WP1 to WP3, respectively.

[0036] The half-wave plates WB1 to WB3 are optical elements containing birefringent material, which create a phase difference of 180° between the orthogonal polarization components of the laser light LB. When linearly polarized light is incident on the half-wave plates WB1 to WB3 at an angle θ to the optical axis, the light is output as linearly polarized light whose vibration direction has been rotated by 2θ.

[0037] The Wollaston prisms WP1 to WP3 split the single beam of laser light LB incident via the half-wave plates WB1 to WB3 into two beams, respectively. That is, the Wollaston prism WP1 splits the single beam of laser light LB into two beams, the Wollaston prism WP2 splits the split laser light LB into four beams, and the Wollaston prism WP3 splits the split laser light LB into eight beams.

[0038] In this embodiment, the number of splits of the laser light LB can be adjusted by changing the number of optical element units U1 to U3 on the optical path of the laser light LB.

[0039] The half-wave plates WB1 to WB3 are arranged upstream of the Wollaston prisms WP1 to WP3 in the optical element units U1 to U3, and are used to adjust the energy ratio of the split laser light LB.

[0040] The adjustment mechanism 50 controls the optical element units U1 to U3 in response to control signals from the control device 10. The adjustment mechanism 50 includes a drive unit (wave plate rotation mechanism and prism rotation mechanism) for controlling the angles of the half-wave plates WB1 to WB3 included in the optical element units U1 to U3 and the positions and angles of the Wollaston prisms WP1 to WP3. The wave plate rotation mechanism and prism rotation mechanism are, for example, an optical element holding mechanism (stage) and an actuator. The adjustment mechanism 50 also includes an optical element unit moving mechanism for moving the optical element units U2 and U3 between an insertion position and a retraction position on the optical path of the laser light LB, so that the optical element units appear and disappear from the optical path. The optical element unit moving mechanism is, for example, a ball screw mechanism or an actuator. In other words, the control device 10 and the adjustment mechanism 50 function as a laser light adjustment unit.

[0041] The adjustment mechanism 50 can adjust the energy intensity of the split laser light LB by rotating the half-wave plates WB1 to WB3 around the optical path of the laser light LB. Also, the adjustment mechanism 50 can adjust the emission direction (split direction) of the split laser light LB by rotating the Wollaston prisms WP1 to WP3 around the optical path of the laser light LB.

[0042] The number and arrangement of the units U1 to U3 are not limited to those shown in Fig. 5, and may be, for example, four or more (16 or more branches). Also, for example, in this embodiment, the downstream units U2 and U3 are capable of appearing and disappearing on the optical path of the laser light LB, but any of the three units U1 to U3 may be capable of appearing and disappearing.

[0043] The 4f optical system 30 focuses the split laser light split by the splitting mechanism 60 at a first focal point F1. The 4f optical system includes a first lens 31 and a second lens 32. The first lens 31 and the second lens 32 are arranged to configure the 4f optical system 30.

[0044] The first lens 31 and the second lens 32 are disposed at a position where the distance between them is equal to the sum of the focal length f1 of the first lens 31 and the focal length f2 of the second lens 32.

[0045] The shielding mechanism 70 shields the branched laser beam at a predetermined timing under the control of the control device 10. The shielding mechanism 70 shields the branched laser beam by driving in synchronization with the processing operation. The shielding mechanism 70 shields the branched laser beam at the focal point F1, and therefore can efficiently shield the branched laser beam. The predetermined timing is, for example, the timing when the spot of the branched laser beam enters a non-processing area, which will be described later. It is preferable that the shielding mechanism 70 can shield the branched laser beam at a time interval of 10 ms or less. The shorter the time interval at which the beam can be shielded, the faster the laser processing speed can be. The shielding mechanism 70 is, for example, a beam shutter. The shutter operation is performed, for example, by an electric actuator (not shown).

[0046] The second condenser lens 18 condenses the branched laser light that has passed through the 4f optical system 30 onto the wafer W1.

[0047] The laser processing apparatus 1 according to this embodiment has been described above. According to the laser processing apparatus 1 according to this embodiment, by branching the laser light, it is possible to perform laser processing in a short time while reducing the thermal influence on the workpiece. Furthermore, since the branched laser light can be emitted only to the region to be processed and the branched laser light can be prevented from being emitted to the non-processing region, it is possible to process the wafer W1 more uniformly.

[0048] The laser processing apparatus 1 according to this embodiment may further include an attenuator (not shown), a beam expander (not shown), and a beam shaping element (not shown). The attenuator is an optical element for adjusting (attenuating) the light intensity of the laser light LB to an appropriate light intensity. The attenuator is disposed, for example, between the laser light source 12 and the branching mechanism 60.

[0049] The beam expander is an optical element for adjusting (expanding) the beam diameter of the laser light LB and shaping the laser light LB into collimated light (parallel light). The beam expander is disposed, for example, between the laser light source 12 and the attenuator.

[0050] The beam shaping element is an optical element for adjusting the beam profile (for example, the shape of the beam and the intensity distribution of the beam) of the laser light LB. The beam shaping element is disposed, for example, between the laser light source 12 and the beam expander.

[0051] The laser processing apparatus 1 according to this embodiment may further include an imaging element (not shown). The imaging element is an optical element for capturing a spot image of the branched laser beam, and is, for example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging element captures the spot image of the branched laser beam. The control device 10 calculates the branching ratio (intensity) and branching direction (position) of the branched laser beam from the captured spot image, and controls the optical element units U1 to U3 so as to obtain a desired branching ratio and a desired branching direction.

[0052] The blocking mechanism 70 only needs to be able to block the branched laser light, and may have a structure in which a metal plate or the like is attached to an actuator such as a motor.

[0053] [Laser processing method] Next, a laser processing method according to this embodiment will be described. FIG. 6 is a diagram illustrating the laser processing method according to the first embodiment. The laser processing method according to this embodiment is a laser processing method for processing a workpiece having a processing region T1 and a non-processing region T2, in which a plurality of spots S1, S2, and S3 of the branched laser beam are linearly arranged in the processing direction to process the wafer W1. In the non-processing region T2, the branched laser beam is blocked using a shielding mechanism 70. For the sake of explanation, the laser processing method according to this embodiment will be described using an example in which the number of second branched laser beams (branched laser beams) is four. The branched laser beams have four spots, S1, S2, S3, and S4, which are linearly arranged in the processing direction X1. In addition, spots S1, S2, S3, and S4 move along the processing direction X1. Each diagram in FIG. 6 shows the processing state at each time from t0 to t6. The state of the branched laser beam at each time will be described below.

[0054] At time t0, the spots S1, S2, and S3 are present in the non-processing region T2 where no processing is to be performed, and therefore the branched laser beams LB1, LB2, and LB3 corresponding to the spots S1, S2, and S3 are blocked by the blocking mechanism 70. Therefore, at time t0, the branched laser beam LB4 is emitted only to the position of the spot S4 in the processing target region T1.

[0055] At time t1, the spot S3 enters the intended processing region T1, so the shading mechanism 70 stops shading the branched laser beam LB3 corresponding to the spot S3 and starts emitting the branched laser beam LB3 corresponding to the spot S3. Specifically, when there is no longer an overlapping region between the spot S3 and the non-processing region T2, the shading of the branched laser beam LB3 is stopped. Therefore, at time t1, the branched laser beams LB3 and LB4 corresponding to each spot are emitted only to the positions of the spots S3 and S4.

[0056] At time t2, the spot S2 enters the intended processing region T1, so the shading mechanism 70 stops shading the branched laser beam LB2 corresponding to the spot S2 and starts emitting the branched laser beam LB2 corresponding to the spot S2. Specifically, when there is no longer an overlapping region between the spot S2 and the non-processing region T2, the shading of the branched laser beam LB2 is stopped. Therefore, at time t2, the branched laser beams LB2, LB3, and LB4 corresponding to each spot are emitted to the positions of the spot S2, spot S3, and spot S4.

[0057] At time t3, the spot S1 enters the intended processing region T1, so the shading mechanism 70 stops shading the branched laser beam LB1 corresponding to the spot S1 and starts emitting the branched laser beam LB1 corresponding to the spot S1. Specifically, when there is no longer an overlapping region between the spot S1 and the non-processing region T2, the shading of the branched laser beam LB1 is stopped. Therefore, at time t3, the branched laser beams LB1, LB2, LB3, and LB4 corresponding to each spot are emitted to the positions of the spot S1, spot S2, spot S3, and spot S4.

[0058] At time t4, the wafer W1 is processed while the spots S1, S2, S3, and S4 move in the processing direction X1. The area through which the spots S1, S2, S3, and S4 have passed becomes the processed area T3 where laser processing is complete.

[0059] At time t5, the spot S4 comes into contact with the non-processing region T2, so the branched laser beam LB4 corresponding to the spot S4 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the non-processing region T2 and the spot S4 overlap, the branched laser beam LB4 corresponding to the spot S4 is blocked. Therefore, at time t5, the branched laser beams LB1, LB2, and LB3 corresponding to each spot are emitted only to the positions of the spots S1, S2, and S3.

[0060] At time t6, the spot S3 comes into contact with the non-processing region T2, so the blocking mechanism 70 blocks the branched laser beam LB3 corresponding to the spot S3. Specifically, when an overlapping region appears where the non-processing region T2 and the spot S3 overlap, the branched laser beam LB3 corresponding to the spot S3 is blocked. Therefore, at time t6, the branched laser beams LB1 and LB2 corresponding to the respective spots are emitted to the positions of the spots S1 and S2.

[0061] At time t7, the spot S2 comes into contact with the non-processing region T2, so the blocking mechanism 70 blocks the branched laser beam LB2 corresponding to the spot S2. Specifically, when an overlapping region appears where the non-processing region T2 and the spot S2 overlap, the branched laser beam LB2 corresponding to the spot S2 is blocked. Therefore, at time t7, the branched laser beam LB1 corresponding to the spot S1 is emitted only to the position of the spot S1.

[0062] At time t8, the spot S1 comes into contact with the non-processed region T2, so the blocking mechanism 70 blocks the branched laser beam LB1 corresponding to the spot S1. Specifically, when an overlapping region appears where the non-processed region T2 and the spot S1 overlap, the branched laser beam LB1 corresponding to the spot S1 is blocked. Therefore, at time t8, none of the branched laser beams are emitted.

[0063] As described above, the laser processing method according to this embodiment can perform laser processing in a short time while reducing the thermal influence on the workpiece by branching the laser beam. Furthermore, since the branched laser beam is emitted only to the region to be processed and not to the non-processing region, the wafer W1 can be processed uniformly.

[0064] [Laser processing method variation 1] Next, a first modified example of the laser processing method according to this embodiment will be described. Fig. 7 is a diagram for explaining the first modified example of the laser processing method. The first modified example of the laser processing method is a laser processing method in which a non-processing area T2a exists between a processing target area T1a and a processing target area T1b. Hereinafter, the first modified example of the laser processing method will be described with reference to Fig. 7.

[0065] At time t0, spots S1, S2, S3, and S4 are all within the to-be-processed region T1a, and therefore none of the branched laser beams are blocked by the blocking mechanism 70. Therefore, at time t0, branched laser beams LB1, LB2, LB3, and LB4 corresponding to the positions of spots S1, S2, S3, and S4 are emitted. Spots S1, S2, S3, and S4 move along the processing direction X1, and the region through which spots S1, S2, S3, and S4 pass becomes the processed region T3a.

[0066] At time t1, the spot S4 comes into contact with the non-processing region T2a where no processing is to be performed, and therefore the branched laser beam LB4 corresponding to the spot S4 is blocked by the blocking mechanism 70. Specifically, when an overlapping region where the non-processing region T2a and the spot S4 overlap appears, the branched laser beam LB4 corresponding to the spot S4 is blocked. Therefore, at time t1, the branched laser beams LB1, LB2, and LB3 corresponding to each spot are emitted only to the positions of the spots S1, S2, and S3 in the processing target region T1.

[0067] At time t2, the spot S3 comes into contact with the non-processed region T2a, and the branched laser beam LB3 corresponding to the spot S3 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the non-processed region T2a and the spot S3 overlap, the branched laser beam LB3 corresponding to the spot S3 is blocked. Therefore, at time t2, the branched laser beams LB1 and LB2 corresponding to the spots S1 and S2 are emitted only to the positions of the spots S1 and S2.

[0068] At time t3, the spot S2 comes into contact with the non-processed region T2a, and the branched laser beam LB2 corresponding to the spot S2 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the non-processed region T2a and the spot S2 overlap, the branched laser beam LB2 corresponding to the spot S2 is blocked. Therefore, at time t3, the branched laser beam LB1 corresponding to the spot S1 is emitted only to the position of the spot S1.

[0069] At time t4, the spot S1 comes into contact with the non-processed region T2a, and the branched laser beam LB1 corresponding to the spot S1 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the non-processed region T2a and the spot S1 overlap, the branched laser beam LB1 corresponding to the spot S1 is blocked. Therefore, at time t4, none of the branched laser beams are emitted.

[0070] At time t5, the spot S4 enters the intended processing region T1b, so the shading mechanism 70 stops shading the branched laser beam LB4 corresponding to the spot S4 and emits the branched laser beam LB4 corresponding to the spot S4. Specifically, when there is no longer an overlapping region where the non-processing region T2a and the spot S3 overlap, the shading of the branched laser beam LB4 corresponding to the spot S4 is stopped. Therefore, at time t5, the branched laser beam LB4 corresponding to the spot S4 is emitted only to the position of the spot S4.

[0071] At time t6, the spot S3 comes into contact with the intended processing region T1b, so the shading mechanism 70 stops shading the branched laser beam LB3 corresponding to the spot S3, and emits the branched laser beam LB3 corresponding to the spot S3. Specifically, when there is no overlapping region where the non-processing region T2a and the spot S3 overlap, the shading of the branched laser beam LB2 corresponding to the spot S3 is stopped. Therefore, at time t6, the branched laser beams LB3 and LB4 corresponding to the spots S3 and S4 are emitted to the positions of the spots S3 and S4.

[0072] At time t7, the spot S2 comes into contact with the intended processing region T1b, so the shading mechanism 70 stops shading the branched laser beam LB2 corresponding to the spot S2, and emits the branched laser beam LB2 corresponding to the spot S2. Specifically, when there is no overlapping region where the non-processing region T2a and the spot S2 overlap, the shading of the branched laser beam LB2 corresponding to the spot S2 is stopped. Therefore, at time t7, the branched laser beams LB2, LB3, and LB4 corresponding to the spots are emitted to the positions of the spots S2, S3, and S4.

[0073] At time t8, the spot S1 comes into contact with the intended processing region T1b, so the shading mechanism 70 stops shading the branched laser beam LB1 corresponding to the spot S1, and emits the branched laser beam LB1 corresponding to the spot S1. Specifically, when there is no overlapping region where the non-processing region T2a and the spot S1 overlap, the shading of the branched laser beam LB1 corresponding to the spot S1 is stopped. Therefore, at time t8, the branched laser beams LB1, LB2, LB3, and LB4 corresponding to each spot are emitted to the positions of the spots S1, S2, S3, and S4.

[0074] At time t9, spots S1, S2, S3, and S4 are all within the to-be-processed region T1b, and therefore none of the branched laser beams are blocked by the blocking mechanism 70. Therefore, at time t9, branched laser beams LB1, LB2, LB3, and LB4 corresponding to the positions of spots S1, S2, S3, and S4 are emitted. Spots S1, S2, S3, and S4 move along the processing direction X1, and the region through which spots S1, S2, S3, and S4 pass becomes the processed region T3b.

[0075] As described above, the laser processing method according to the first modification of the present embodiment can perform laser processing in a short time while reducing the thermal effects on the workpiece by branching the laser beam. Furthermore, because the branched laser beam is emitted only to the region to be processed and not to the non-processing region, the wafer W1 can be processed uniformly. This allows for uniform processing in a short time even if there is a non-processing region between multiple regions to be processed.

[0076] [Laser processing method variation 2] Next, a second modification of the laser processing method according to this embodiment will be described. Fig. 8 is a diagram for explaining the second modification of the laser processing method. The second modification of the laser processing method is a laser processing method in which a processed area T3c exists between the planned processing area T1c and the planned processing area T1d. Hereinafter, the second modification of the laser processing method will be described with reference to Fig. 8.

[0077] At time t0, spots S1, S2, S3, and S4 are all within the to-be-processed region T1c, and therefore none of the branched laser beams are blocked by the blocking mechanism 70. Therefore, at time t0, branched laser beams LB1, LB2, LB3, and LB4 corresponding to the positions of spots S1, S2, S3, and S4 are emitted. Spots S1, S2, S3, and S4 move along the processing direction X1, and the region through which spots S1, S2, S3, and S4 pass becomes the processed region T3d.

[0078] At time t1, the spot S4 comes into contact with the processed region T3c where processing has been completed, and the branched laser beam corresponding to the spot S4 is blocked by the blocking mechanism 70. Specifically, when an overlapping region where the processed region T3c and the spot S4 overlap appears, the branched laser beam LB4 corresponding to the spot S4 is blocked. Therefore, at time t1, the branched laser beams LB1, LB2, and LB3 corresponding to the spots S1, S2, and S3 are emitted only to the positions of the spots S1, S2, and S3 in the region to be processed T1c.

[0079] At time t2, the spot S3 comes into contact with the processed region T3c, and the branched laser beam LB3 corresponding to the spot S3 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the processed region T3c and the spot S3 overlap, the branched laser beam LB3 corresponding to the spot S3 is blocked. Therefore, at time t2, the branched laser beams LB1 and LB2 corresponding to the spot S1 and the spot S2 are emitted only to the positions of the spots S1 and S2.

[0080] At time t3, the spot S2 comes into contact with the processed region T3c, and the branched laser beam LB2 corresponding to the spot S2 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the processed region T3c and the spot S2 overlap, the branched laser beam LB2 corresponding to the spot S2 is blocked. Therefore, at time t3, the branched laser beam LB1 corresponding to the spot S1 is emitted only to the position of the spot S1.

[0081] At time t4, the spot S1 comes into contact with the processed region T3c, and the branched laser beam LB1 corresponding to the spot S1 is blocked by the blocking mechanism 70. Specifically, when an overlapping region appears where the processed region T3c and the spot S1 overlap, the branched laser beam LB1 corresponding to the spot S1 is blocked. Therefore, at time t4, none of the branched laser beams are emitted.

[0082] At time t5, the spot S4 enters the to-be-processed region T1d, so the shading mechanism 70 stops shading the branched laser beam LB4 corresponding to the spot S4 and emits the branched laser beam LB4 corresponding to the spot S4. Specifically, when there is no overlapping region where the processed region T3c and the spot S4 overlap, the shading of the branched laser beam LB4 corresponding to the spot S4 is stopped. Therefore, at time t5, the branched laser beam LB4 corresponding to the spot S4 is emitted only to the position of the spot S4.

[0083] At time t6, the spot S3 enters the to-be-processed region T1d, so the shading mechanism 70 stops shading the branched laser beam LB3 corresponding to the spot S3, and emits the branched laser beam LB3 corresponding to the spot S3. Specifically, when there is no overlapping region where the processed region T3c and the spot S3 overlap, the shading of the branched laser beam LB3 corresponding to the spot S3 is stopped. Therefore, at time t6, the branched laser beams LB3 and LB4 corresponding to the spots are emitted only to the positions of the spots S3 and S4.

[0084] At time t7, the spot S2 enters the to-be-processed region T1d, so the shading mechanism 70 stops shading the branched laser beam LB2 corresponding to the spot S2, and emits the branched laser beam LB2 corresponding to the spot S2. Specifically, when there is no longer an overlapping region where the processed region T3c and the spot S2 overlap, the shading of the branched laser beam LB2 corresponding to the spot S2 is stopped. Therefore, at time t7, the branched laser beams LB2, LB3, and LB4 corresponding to the respective spots are emitted to the positions of the spots S2, S3, and S4.

[0085] At time t8, the spot S1 enters the to-be-processed region T1d, so the shading mechanism 70 stops shading the branched laser beam LB1 corresponding to the spot S1, and emits the branched laser beam LB1 corresponding to the spot S1. Specifically, when there is no overlapping region where the processed region T3c and the spot S1 overlap, the shading of the branched laser beam LB1 corresponding to the spot S1 is stopped. Therefore, at time t8, the branched laser beams LB1, LB2, LB3, and LB4 corresponding to each spot are emitted to the positions of the spot S1, spot S2, spot S3, and spot S4.

[0086] At time t9, spots S1, S2, S3, and S4 are all within the to-be-processed region T1d, and therefore none of the branched laser beams are blocked by the blocking mechanism 70. Therefore, at time t9, branched laser beams LB1, LB2, LB3, and LB4 corresponding to the positions of spots S1, S2, S3, and S4 are emitted. Spots S1, S2, S3, and S4 move along the processing direction X1, and the region through which spots S1, S2, S3, and S4 pass becomes the processed region T3e.

[0087] As described above, the laser processing method according to the second modification of the present embodiment can perform laser processing in a short time while reducing the thermal effects on the workpiece by branching the laser beam. Furthermore, the branched laser beam is emitted only to the region to be processed, and the branched laser beam is not emitted to the processed region, so that the wafer W1 can be processed uniformly. This allows for uniform processing in a short time, even if there is a processed region between multiple regions to be processed.

[0088] [Laser processing method variation 3] Next, a third modification of the laser processing method according to this embodiment will be described. FIG. 9 is a diagram for explaining the third modification of the laser processing method. The third modification of the laser processing method is a laser processing method that processes materials with different processing rates to the same depth. In this third modification, the wafer W1 has a processing-intended region T1e between the non-processing region T2c and the non-processing region T2d. The processing-intended region T1e has a low-rate region T4a made of a material with a low processing rate and a high-rate region T4b made of a material with a high processing rate. Below, the third modification of the laser processing method will be described using FIG. 9.

[0089] At time t0, the spots S1, S2, and S3 are within the non-processing region T2c, and therefore the branched laser beams LB1, LB2, and LB3 corresponding to the spots S1, S2, and S3 are blocked by the blocking mechanism 70. The spot S4 is within the low-rate region T4a of the intended processing region T1e, and therefore the branched laser beam LB4 corresponding to the spot S3 is not blocked by the blocking mechanism 70. Therefore, at time t0, the branched laser beam LB4 corresponding to the spot S4 is emitted to the position of the spot S3.

[0090] At time t1, the spots S1 and S2 are within the non-processing region T2c, so the shading mechanism 70 shades the branched laser beams LB1 and LB2 corresponding to the spots S1 and S2. Since the spot S3 enters the low-rate region T4a, the shading mechanism 70 stops shading the branched laser beams and emits the branched laser beam LB3 corresponding to the position of the spot S3. Specifically, when the overlapping region where the non-processing region T2c and the spot S3 overlap disappears, the shading mechanism 70 stops shading the branched laser beams. Since the spot S4 is within the low-rate region T4a of the processing target region T1e, the branched laser beam LB4 continues to be emitted to the spot S4. Therefore, at time t1, the branched laser beams LB3 and LB4 corresponding to the spots S3 and S4 are emitted to the positions of the spots S3 and S4.

[0091] At time t2, since spot S1 is within the non-processing region T2c, the shading mechanism 70 shades the branched laser beam LB1 corresponding to spot S1. Since spot S2 enters the low-rate region T4a, the shading mechanism 70 stops shading the branched laser beam and emits branched laser beam LB2 corresponding to the position of spot S2. Specifically, when the overlapping region where non-processing region T2c and spot S2 overlap disappears, the shading mechanism 70 stops shading the branched laser beam. Since spots S3 and S4 are within the low-rate region T4a of the intended processing region T1e, the branched laser beams LB3 and LB4 continue to be emitted to spots S3 and S4. Therefore, at time t1, branched laser beams LB2, LB3, and LB4 corresponding to each spot are emitted to the positions of spots S2, S3, and S4.

[0092] At time t3, spot S1 is within the low-rate region T4a, so the shading mechanism 70 stops shading the branched laser beam corresponding to spot S1 and emits branched laser beam LB1 corresponding to spot S1 at the position of spot S1. Spots S2 and S3 are within the low-rate region T4a, so the shading mechanism 70 continues emitting branched laser beams LB2 and LB3 at the positions of spots S2 and S3. Spot S4 is within the high-rate region T4b, so the shading mechanism 70 shading the branched laser beam LB4 corresponding to spot S4. Specifically, when an overlapping region appears where the high-rate region T4b and spot S34 overlap, the shading mechanism 70 shading the branched laser beam LB4 corresponding to spot S3. Therefore, at time t3, branched laser beams LB1, LB2, and LB3 corresponding to each spot are emitted at the positions of spots S1, S2, and S3. In the low rate region T4a, the wafer W1 is processed by branched laser beams LB1, LB2, LB3, and LB4 corresponding to four spots, ie, the spot S1, the spot S2, the spot S3, and the spot S4.

[0093] At time t4, because spots S1 and S2 are within the low-rate region T4a, the branched laser beams LB1 and LB2 continue to be emitted toward the positions of spots S1 and S2. Spot S3 falls within the high-rate region T4b, but the branched laser beam LB3 continues to be emitted toward the position of spot S3 to adjust for the difference in processing amount due to the difference in processing rate between the low-rate region T4a and the high-rate region T4b. For spot S4, the shading mechanism 70 continues to block the branched laser beam LB4 corresponding to spot S4 while spot S4 is within the high-rate region T4b to adjust for the difference in processing amount due to the difference in processing rate between the low-rate region T4a and the high-rate region T4b. Therefore, at time t4, the branched laser beams LB1, LB2, and LB3 corresponding to each spot are emitted toward the positions of spots S1, S2, and S3.

[0094] At time t5, spots S1 and S2 enter the high-rate region T4b, but to adjust for the difference in processing amount due to the difference between the processing rate in the low-rate region T4a and the processing rate in the high-rate region T4b, branched laser beams LB1 and LB2 continue to be emitted to the positions of spots S1 and S2 while spots S1 and S2 are in the high-rate region T4b. Since spots S3 and S4 enter the non-processing region T2d, the shielding mechanism 70 shields the branched laser beams LB3 and LB4 corresponding to spots S3 and S4. Therefore, at time t5, branched laser beams LB1 and LB2 corresponding to each spot are emitted to the positions of spots S1 and S2.

[0095] At time t6, since spot S1 is within the high-rate region T4b, the branched laser beam LB1 continues to be emitted toward the position of spot S1 to adjust for the difference in processing amount due to the difference between the processing rate of the low-rate region T4a and the processing rate of the high-rate region T4b. Since spot S2 enters the non-processing region T2d, the shading mechanism 70 shading the branched laser beam LB2 corresponding to spot S2. Specifically, when an overlapping region appears where the non-processing region T2d and spot S2 overlap, the branched laser beam corresponding to spot S2 is shading. Since spots S3 and S4 are within the non-processing region T2d, the shading mechanism 70 continues to shading the branched laser beams LB3 and LB4 corresponding to spots S3 and S4. Therefore, at time t6, the branched laser beam LB1 is emitted only toward the position of spot S1. Here, in the high rate region T4b, the workpiece is processed by branched laser beams LB1, LB2, and LB3 corresponding to three spots, namely, spot S1, spot S2, and spot S3.

[0096] At time t7, the spot S1 enters the non-processing region T2d, so the shading mechanism 70 shading the branched laser beam LB1 corresponding to the spot S1. Specifically, when an overlapping region appears where the non-processing region T2d and the spot S1 overlap, the branched laser beam LB1 corresponding to the spot S1 is shading. Since the spots S2, S3, and S4 are in the non-processing region T2d, the shading mechanism 70 continues to shading the branched laser beams LB2, LB3, and LB4 corresponding to the spots S2, S3, and S4. Therefore, at time t7, all of the branched laser beams are shading.

[0097] As described above, in the laser processing method according to the third modification of the present embodiment, by branching the laser beam, it is possible to perform laser processing in a short time while reducing the thermal influence on the workpiece. Furthermore, the branched laser beams are blocked using the blocking mechanism 70 so that the number of spots of the branched laser beam in the low-rate region T4a is greater than the number of spots of the branched laser beam in the high-rate region T4b, so that even workpieces made of materials with different processing rates can be processed uniformly. As described above, this technology can be applied not only to the edges of a workpiece or intermittent machining, but also to machining areas in the middle of the machining area where the machining rate differs due to the workpiece's characteristics (material, shape, etc.) at the same depth.

[0098] [Laser processing device modification example 1] 10 is a block diagram of laser optical system Variation 1. Laser optical system 14A, which is laser optical system Variation 1, includes a branching mechanism 60 that branches laser light LB into two or more branched laser lights LB1, LB2, LB3, and LB4, a first mirror 41 that reflects the branched laser lights LB1, LB2, LB3, and LB4 toward a 4f optical system 30, the 4f optical system 30 that focuses the branched laser lights LB1, LB2, LB3, and LB4 at a first focal point F1, a blocking mechanism 70 that blocks the branched laser lights LB1, LB2, and LB3 at the first focal point F in accordance with a predetermined timing, a second mirror 42 that reflects the branched laser lights LB1, LB2, and LB3 that have passed through the 4f optical system 30 toward a focusing lens 18, and the focusing lens 18 that focuses the branched laser lights LB1, LB2, and LB3 that have passed through the 4f optical system 30 on a workpiece.

[0099] As described above, even with the configuration of the laser processing device of Variation 1, by branching the laser beam, it is possible to reduce the thermal impact on the workpiece and perform laser processing in a short time. Furthermore, since the branched laser beam can be emitted only to the region to be processed and not to the non-processing region, the wafer W1 can be processed more uniformly. Furthermore, although the components of the laser optical system 14 were arranged in a straight line, even if the direction of the laser beam is changed using mirrors such as the first mirror 41 and the second mirror 42, it is possible to obtain the same effect as with a straight line arrangement.

[0100] [Laser processing device modification example 2] 11 is a block diagram of laser optical system variation 2. Laser optical system 14B, which is laser optical system variation 2, includes a branching mechanism 60 that branches laser light LB into two or more branched laser light beams LB1, LB2, LB3, and LB4, a 4f optical system 30 that focuses the branched laser light beams LB1, LB2, LB3, and LB4 at a first focal point F1, a blocking mechanism 70B that blocks the branched laser light beams LB1, LB2, LB3, and LB4 at the first focal point F in accordance with a predetermined timing, and a focusing lens 18 that focuses the branched laser light beams LB1, LB2, LB3, and LB4 on a workpiece after passing through the 4f optical system 30.

[0101] (Shielding mechanism 70B) The shielding mechanism 70B includes a first electro-optical element (EO element) 71A, a second electro-optical element (EO element) 71B, a third electro-optical element (EO element) 71C, a fourth electro-optical element (EO element) 71D, a polarizing beam splitter 72, and a diffuser 73.

[0102] The control device 10 adjusts the polarization direction of the branched laser beam by electrically controlling the first electro-optical element (EO element) 71A, the second electro-optical element (EO element) 71B, the third electro-optical element (EO element) 71C, and the fourth electro-optical element (EO element) 71D in synchronization with the machining operation. For example, when it is desired to block only LB4 as shown in FIG. 11, the fourth electro-optical element 71D adjusts the branched laser beam to the polarization direction reflected by the polarizing beam splitter 72, and the first electro-optical element 71A, the second electro-optical element 71B, and the third electro-optical element 71C adjust the branched laser beam to the polarization direction transmitted by the polarizing beam splitter 72. This allows the branched laser beam to be blocked at time intervals of, for example, 100 μs or less. The number of electro-optical elements (EO elements) is equal to the number of branched laser beams.

[0103] The split laser light, the polarization direction of which has been adjusted, is incident on the polarizing beam splitter 72. Depending on the polarization direction, the split laser light that has entered the polarizing beam splitter 72 is either transmitted toward the second lens 32 or reflected toward the diffuser 73. The beam reflected by the polarizing beam splitter 72 is irradiated onto the diffuser 73 and absorbed.

[0104] As described above, even with the configuration of Modification 2 of the present laser processing apparatus 1, by branching the laser light, it is possible to perform laser processing in a short time while reducing the thermal impact on the workpiece. Furthermore, since the branched laser light can be emitted only to the region to be processed and the branched laser light can be prevented from being emitted to the non-processing region, the wafer W1 can be processed more uniformly. Furthermore, by using an electro-optical element, it is possible to block the branched laser light more quickly, thereby further improving the processing speed.

[0105] [Laser processing device modification example 3] 12 is a block diagram of laser optical system Variation 3. Laser optical system 14C, which is laser optical system Variation 3, includes: a branching mechanism 60C that branches laser light LB into two or more branched laser beams LB1, LB2, LB3, and LB4; a first mirror 41 that reflects the branched laser beams LB1, LB2, LB3, and LB4 toward a 4f optical system 30; a 4f optical system 30 that focuses the branched laser beams LB1, LB2, and LB3 at a first focal point F1; a shielding mechanism 70 that shields the branched laser beams LB1, LB2, LB3, and LB4 at the first focal point F in accordance with a predetermined timing; a second mirror 42 that reflects the branched laser beams LB1, LB2, and LB3 that have passed through the 4f optical system 30 toward a focusing lens 18; and a focusing lens 18 that focuses the branched laser beams LB1, LB2, and LB3 that have passed through the 4f optical system 30 on a workpiece.

[0106] The branching mechanism 60C is, for example, a liquid crystal on silicon (LCOS) device. The LCOS device allows the number of branches of the branched laser light to be appropriately changed under the control of the control device 10.

[0107] As described above, even with the configuration of Modification 2 of the present laser processing apparatus 1, by branching the laser light, it is possible to reduce the thermal impact on the workpiece and perform laser processing in a short time. Furthermore, since the branched laser light can be emitted only to the region to be processed and the branched laser light can be prevented from being emitted to the non-processing region, the wafer W1 can be processed more uniformly. Furthermore, by using LCOS, the number of branches of the branched laser light can be appropriately changed under the control of the control device 10 without increasing or decreasing the number of optical units that are in use.

[0108] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the laser optical system 14 of the laser processing apparatus 1 can be replaced with any one of the above-described modified examples 1 to 3. In addition, it is possible to replace the components in the above-described modified examples with well-known components as appropriate, and the elements of the above-described modified examples may be combined as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0109] 1 laser processing device, 12A first laser light source, 12B second laser light source, 20 microscope, 22 relative movement mechanism, 30 4f optical system, 60 branching mechanism, 70 shielding mechanism

Claims

1. a laser light source that emits laser light; a branching mechanism for branching the laser beam into two or more branched laser beams; a 4f optical system that focuses the branched laser beams at a first focal point; a blocking mechanism that blocks the branched laser beam at the first focal point in accordance with a predetermined timing; a condenser lens that condenses the branched laser beams after passing through the 4f optical system onto a workpiece; A laser processing device comprising:

2. 2. The laser processing device according to claim 1, wherein the blocking mechanism is a beam shutter capable of blocking the branched laser beams at time intervals of 10 ms or less.

3. 2. The laser processing device according to claim 1, wherein the shielding mechanism is an electron optical element and a polarizing beam splitter.

4. 3. The laser processing apparatus according to claim 1, wherein the branching mechanism is arranged in series on the optical path of the laser light, and the branching mechanism comprises an optical element having a half-wave plate and a Wollaston prism, a wave plate rotation mechanism that rotates the half-wave plate around the optical path, and a prism rotation mechanism that rotates the Wollaston prism around the optical path.

5. 3. The laser processing device according to claim 1, wherein the branching mechanism is made of liquid crystal on silicon.

6. The laser processing device according to claim 4 , further comprising a laser beam adjusting unit configured to adjust a direction in which the branching mechanism branches the branched laser beam.

7. 2. A laser processing method using the laser processing apparatus according to claim 1, wherein the plurality of split laser beam spots are linearly arranged in the processing direction to process the workpiece.

8. The workpiece has a region to be machined and a region not to be machined, The laser processing method according to claim 7 , wherein the blocking mechanism is used to block the branched laser beam in the non-processing region.

9. The workpiece has a region to be processed and a region that has already been processed, The laser processing method according to claim 7 , wherein the blocking mechanism is used to block the branched laser beam in the processed region.

10. the workpiece has a high-rate region made of a material with a high processing rate and a low-rate region made of a material with a low processing rate, The laser processing method according to claim 7 , wherein the blocking mechanism is used to block the branched laser beams so that the number of the spots in the low rate region is greater than the number of the spots in the high rate region.

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