Laser processing device and laser processing method

Abstract

A laser processing device for forming a modified region by irradiating an object with laser light, the laser processing device comprising: a support portion for supporting the object; a laser irradiation portion for irradiating the object supported by the support portion with the laser light; a movement mechanism for moving at least one of the support portion and the laser irradiation portion to move a focal point of the laser light relative to the object; and a control portion for controlling the laser irradiation portion and the movement mechanism. When the object is viewed from a direction intersecting a plane of incidence of the laser light, a first line extending in a first direction and a second line extending beyond the first line in a second direction intersecting the first direction are defined.

Description

Technical Field

[0001] One aspect of the present invention relates to a laser processing apparatus and a laser processing method. Background Art

[0002] Patent Document 1 describes a laser processing device. The laser processing device includes a focusing lens that forms a processing layer on a single crystal component using laser light emitted from the focusing lens. The focusing lens comprises a secondary focusing system for incident laser light, and a primary focusing system for incident laser light emitted from the secondary focusing system and irradiating the single crystal component with the laser light. The secondary focusing system comprises a cylindrical lens array composed of a plurality of cylindrical lenses arranged integrally, and a cylindrical convex lens for transmitting light from the cylindrical lens array.

[0003] This laser processing device is configured such that laser light incident on a cylindrical lens is split into multiple beams, forming a focal point that then enters a cylindrical convex lens. The irradiated surface is transformed into a long, narrow, parallel beam that enters the main focusing system. Laser light emitted from the main focusing system then enters the irradiated surface of the single crystal component as split laser light, forming multiple focal points within the single crystal component.

[0004] [Prior art literature]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-19120 Summary of the Invention

[0006] [Technical problem to be solved by the invention]

[0007] According to the above-mentioned laser processing device, by forming a processing layer while forming a plurality of laser focal points, the speed of forming the processing layer can be increased. That is, the above-mentioned technical field is expected to achieve an increase in processing speed. On the other hand, according to the knowledge and insights of the present inventors, if the laser is irradiated while forming a plurality of focal points in the thickness direction of the object, the crack extending from the modified area formed at one focal point affects the formation of the modified area at another focal point and the progress of the crack, and as a result, there is a problem of instability in the amount of cracks (the length of the crack). When the amount of cracks is unstable, the quality of the cut surface (i.e., the processing quality) when the object is cut with the crack as the boundary is reduced.

[0008] The amount of cracks tends to be smaller near the laser irradiation start position and larger at a certain distance from the irradiation start position. Furthermore, when laser irradiation is performed across an already formed modified region (the modified region and the cracks extending from the modified region), similar to the relationship with the irradiation start position, the amount of cracks tends to be smaller near the modified region and larger at a certain distance from the modified region.

[0009] Therefore, for example, when laser irradiation is performed over the entire object before the formation of the modified area, the crack amount becomes constant at a relatively high level in most areas except near the irradiation start position, so the instability of the overall crack amount has a relatively small impact on the processing quality.

[0010] On the other hand, if, after forming a modified region or the like in a first direction, the object is irradiated with laser light in a second direction different from the first direction, straddling the already formed modified region or the like, the portion with less cracking and the portion with more cracking will repeatedly occur at a shorter cycle (the formation pitch of the modified region or the like in the second direction) than the object as a whole. Therefore, the overall destabilization of the cracking amount has a relatively greater impact on the processing quality. Therefore, in such cases, it is important to suppress the destabilization of the cracking amount and thus the degradation of the processing quality.

[0011] Therefore, an object of one aspect of the present invention is to provide a laser processing device and a laser processing method that can achieve both improved processing speed and suppressed degradation of processing quality.

[0012] [Technical means for solving technical problems]

[0013] 18. The laser processing apparatus according to claim 17, wherein the laser processing apparatus comprises: a support portion for supporting the object; a laser irradiation portion for irradiating the object supported by the support portion with laser light; a moving mechanism for moving at least one of the support portion and the laser irradiation portion so as to move a focal point of the laser light relative to the object; and a control portion for controlling the laser irradiation portion and the moving mechanism, wherein, when the object is viewed from a direction intersecting with an incident surface of the laser light, a first line extending along a first direction and a second line extending across the first line in a second direction intersecting with the first direction are set, the control portion performing the following first, second and third processes: in the first process, by controlling the laser irradiation portion and the moving mechanism, the object is irradiated with laser light while the focal point is relatively moved along the first line, thereby forming a modified region along the first line; in the second process, after the first process, the laser irradiation portion and the moving mechanism are controlled to move the focal point relative to the object. The moving mechanism is controlled to form a first focal point of the laser and a second focal point of the laser located on the side of the incident surface of the object compared to the first focal point, and the first focal point and the second focal point are relatively moved along the second line while irradiating the object with laser light in such a manner that the cracks extending from the modified area formed at the first focal point and the cracks extending from the modified area formed at the second focal point are not connected to each other, thereby forming a modified area along the second line. The third treatment, after the second treatment, a third focal point of the laser is formed at a third position between the first position of the first focal point and the second position of the second focal point in a direction intersecting the incident surface by controlling the laser irradiation part and the moving mechanism, and the third focal point is relatively moved along the second line while irradiating the object with laser light to form a modified area along the second line at the third position, thereby forming a crack extending between the modified area formed at the first position and the modified area formed at the second position.

[0014] A laser processing method according to one aspect of the present invention is used for irradiating an object with a laser to form a modified region, the laser processing method comprising: a laser irradiation step of irradiating the object with the laser while causing a focal point of the laser to move relative to the object to form the modified region, wherein, when the object is observed from a direction intersecting an incident surface of the laser, a first line extending along a first direction and a second line extending across the first line in a second direction intersecting the first direction are set, the laser irradiation step comprising: a first step of irradiating the object with the laser while causing the focal point to move relative to the first line to form the modified region along the first line; and a second step of forming, after the first step, a first focal point of the laser and a second focal point of the laser located on the incident surface of the object relative to the first focal point. 2 focusing points, and while irradiating the object with laser light while relatively moving the first focusing point and the second focusing point along the second line in a manner such that the crack extending from the modified area formed at the first focusing point and the crack extending from the modified area formed at the second focusing point are not connected to each other, thereby forming a modified area along the second line; and a third process, after the second process, forming a third focusing point of laser light at a third position between the first position of the first focusing point and the second position of the second focusing point in a direction intersecting the incident surface, and while irradiating the object with laser light while relatively moving the third focusing point along the second line, thereby forming a modified area along the second line at the third position, thereby forming a crack extending between the modified area formed at the first position and the modified area formed at the second position.

[0015] In an apparatus and method according to one aspect of the present invention, a first line extending along a first direction and a second line extending across the first line along a second direction intersecting the first direction are set for the object. Furthermore, after laser irradiation along the first line forms a modified region, laser irradiation along the second line forms a modified region. When laser irradiation is performed along the second line, at least two focal points are formed in a direction intersecting the incident surface of the laser on the object. Therefore, an increase in processing speed can be achieved. On the other hand, in an apparatus and method according to one aspect of the present invention, laser irradiation occurs across the modified region already formed along the first line. Therefore, it is important to suppress the destabilization of cracks.

[0016] Here, according to the knowledge and insights of the present inventors, while irradiating the laser in a direction intersecting the incident surface of the laser on the object while forming the first and second focal points, a modified region corresponding to the first and second focal points is formed in a manner such that the cracks extending from the modified region formed at the first focal point and the cracks extending from the modified region formed at the second focal point are not connected to each other, and then a modified region corresponding to another third focal point between the position of the first focal point and the position of the second focal point is formed, thereby forming cracks that extend between the modified region corresponding to the first focal point and the modified region corresponding to the second focal point. If constructed in this way, the instability of the overall crack amount can be suppressed.

[0017] Therefore, in an apparatus and method according to one aspect of the present invention, after forming a modified region along a first line, the first and second laser focal points are moved relative to each other along a second line while irradiating the object with laser light, so that cracks extending from the modified region formed at the first laser focal point and cracks extending from the modified region formed at the second laser focal point are not connected to each other, thereby forming a modified region along the second line. Subsequently, a third laser focal point is formed at a third position between the first position of the first laser focal point and the second position of the second laser focal point, and the object is irradiated with laser light while the third laser focal point is moved relative to each other along the second line, thereby forming a modified region along the second line at the third position. This results in cracks extending between the modified region formed at the first position and the modified region formed at the second position. As a result, as shown by the above-mentioned knowledge and insights, instability in the overall crack amount is suppressed. Consequently, degradation in processing quality is suppressed.

[0018] In the laser processing apparatus according to one aspect of the present invention, the control unit may be configured such that, during the second process, the control unit controls the laser irradiation unit so that the first focal point is positioned forward of the second focal point in the direction of relative movement between the first and second focal points. In this case, the amount of crack extension from the modified regions formed at the first and second focal points can be increased. This reduces the number of rows of modified regions required in a direction intersecting the laser incident surface of the object, thereby increasing processing speed.

[0019] In the laser processing apparatus according to one aspect of the present invention, the control unit may be configured such that, during the second process, the control unit controls the laser irradiation unit so that the first and second light-converging points are aligned in the direction of relative movement of the first and second light-converging points. In this case, the amount of crack extension from the modified regions formed at the first and second light-converging points can be reduced. This reliably prevents cracks extending from the modified region formed at the first light-converging point from connecting with cracks extending from the texture region formed at the second light-converging point.

[0020] In the laser processing apparatus according to one aspect of the present invention, the control unit may control the laser irradiation unit and the movement mechanism in the third process to form a third light-converging point and a fourth light-converging point of the laser beam located to the side of the incident surface relative to the third light-converging point, and irradiate the object with the laser beam while relatively moving the third and fourth light-converging points along the second line. In this case, the processing speed can be further improved.

[0021] In the laser processing apparatus according to one aspect of the present invention, the control unit may be configured such that, during the first process, the control unit controls the laser irradiation unit and the movement mechanism to form a fifth focal point of the laser light and a sixth focal point of the laser light located closer to the incident surface of the object than the fifth focal point, and irradiates the object with the laser light while relatively moving the fifth and sixth focal points along the first line. In this case, the processing speed can be further improved.

[0022] In the laser processing device of one aspect of the present invention, it can also be configured that the control unit performs the following fourth and fifth processes in the first process: in the fourth process, by controlling the laser irradiation unit and the moving mechanism, the fifth and sixth light-converging points are moved relative to each other along the first line while irradiating the object with laser light, so that the crack extending from the modified area formed at the fifth light-converging point and the crack extending from the modified area formed at the sixth light-converging point are not connected to each other, thereby forming a modified area along the first line; in the fifth process, after the fourth process, the seventh light-converging point of the laser is formed at the seventh position between the fifth position of the fifth light-converging point and the sixth position of the sixth light-converging point in a direction intersecting the incident surface by controlling the laser irradiation unit and the moving mechanism, and the seventh light-converging point is moved relative to each other along the first line while irradiating the object with laser light, thereby forming a modified area along the first line at the seventh position, thereby forming a crack extending between the modified area formed at the fifth position and the modified area formed at the sixth position. In this case, for the same reasons as described above, it is possible to improve the processing speed and suppress the reduction in processing quality in the first process as well.

[0023] A laser processing device according to one aspect of the present invention is used for irradiating an object with laser light to form a modified region, the laser processing device comprising: a support portion for supporting the object; a laser irradiation portion for irradiating the object supported by the support portion with laser light; a moving mechanism that moves at least one of the support portion and the laser irradiation portion so that a focal point of the laser light moves relative to the object; and a control portion that controls the laser irradiation portion and the moving mechanism, the control portion performing the following modified region forming process and crack forming process, wherein the modified region forming process forms a first focal point of the laser light and a second focal point of the laser light that is located on the side of an incident surface of the laser light of the object than the first focal point by controlling the laser irradiation portion and the moving mechanism, and is so formed that a second focal point of the laser light is formed from the first focal point of the laser light. The crack extending from the formed modified area is not connected to the crack extending from the modified area formed at the second focal point, and the first focal point and the second focal point are moved relative to each other while the laser is irradiated on the object to form the modified area, and the crack formation process is performed. After the modified area formation process, the laser irradiation part and the moving mechanism are controlled to form a third focal point of the laser at a third position between the first position of the first focal point and the second position of the second focal point in a direction intersecting the incident surface, and the laser is irradiated on the object while the third focal point is moved relative to each other to form the modified area at the third position, thereby forming a crack extending between the modified area formed at the first position and the modified area formed at the second position.

[0024] In this laser processing device, a modified region is formed by irradiating an object with laser light while relatively moving the first and second laser focal points so that cracks extending from a modified region formed at a first laser focal point and cracks extending from a modified region formed at a second laser focal point are not connected to each other. Subsequently, a third laser focal point is formed at a third position between the first position of the first laser focal point and the second position of the second laser focal point. The object is irradiated with laser light while relatively moving the third laser focal point, thereby forming a modified region at the third position. This results in cracks extending between the modified region formed at the first position and the modified region formed at the second position. As a result, as shown by the above-mentioned knowledge and insights, instability in the amount of cracks can be suppressed. Consequently, a decrease in processing quality can be suppressed.

[0025] [Effects of the Invention]

[0026] According to one aspect of the present invention, it is possible to provide a laser processing apparatus and a laser processing method that can simultaneously achieve an improvement in processing speed and a suppression of a decrease in processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram showing the structure of a laser processing apparatus according to one embodiment of the present invention.

[0028] Figure 2 Yes Figure 1 Schematic diagram of the structure of the laser irradiation part shown.

[0029] Figure 3 Yes Figure 1 Schematic diagram of the structure of the laser irradiation part shown.

[0030] Figure 4 It is a cross-sectional view showing the processing of the first example.

[0031] Figure 5 This is a cross-sectional photograph showing the processing result of the first example.

[0032] Figure 6 It is a cross-sectional view showing the processing of the second example.

[0033] Figure 7 This is a cross-sectional photograph showing the processing result of the second example.

[0034] Figure 8 This is a flowchart showing an example of the laser processing method according to this embodiment.

[0035] Figure 9 Yes Figure 8 A diagram showing one process step of the laser processing method.

[0036] Figure 10 Yes Figure 8 A diagram showing one process step of the laser processing method.

[0037] Figure 11 Yes Figure 8 A diagram showing one process step of the laser processing method.

[0038] Figure 12 This is a diagram showing an example of a setting screen displayed on the input acceptance unit.

[0039] Figure 13 Yes Figure 8 A diagram showing one process step of the laser processing method.

[0040] Figure 14 Yes Figure 8 A diagram showing one process step of the laser processing method.

[0041] Figure 15 Yes Figure 8 A diagram showing one process step of the laser processing method. DETAILED DESCRIPTION

[0042] Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In each figure, the same or corresponding parts are given the same reference numerals, and repeated descriptions may be omitted. In addition, each figure may sometimes illustrate an orthogonal coordinate system defined by the X-axis, Y-axis, and Z-axis.

[0043] Figure 1 Schematic diagram showing the structure of a laser processing device according to one embodiment of the present invention. Figure 1 As shown, the laser processing apparatus 1 includes a stage (support unit) 2, a laser irradiation unit 3, drive units (movement mechanisms) 4 and 5, and a control unit 6. The laser processing apparatus 1 is an apparatus for forming a modified (reformed) region 12 in an object 11 by irradiating the object 11 with laser light L.

[0044] The stage 2 supports the object 11 by, for example, holding a film attached to the object 11. The stage 2 can rotate about an axis parallel to the Z direction. The stage 2 can also move in both the X and Y directions. The X and Y directions are first and second horizontal directions that intersect (orthogonal to) each other, while the Z direction is a vertical direction.

[0045] The laser irradiation unit 3 focuses laser light L that is transparent to the object 11 and irradiates the object 11. When the laser light L is focused inside the object 11 supported by the stage 2, the laser light L is particularly absorbed in the portion corresponding to the focal point C of the laser light L, forming a modified region 12 inside the object 11.

[0046] The modified region 12 is a region whose physical properties, such as density, refractive index, and mechanical strength, differ from those of the surrounding unmodified region. Examples of the modified region 12 include a melt-processed region, a crack region, a dielectric breakdown region, and a region with a changed refractive index. The modified region 12 can be formed so that cracks extend from the modified region 12 toward the incident side of the laser light L and the opposite side. Such modified regions 12 and cracks are used, for example, to cut the object 11.

[0047] For example, if the stage 2 is moved in the X direction and the focal point C is moved relative to the object 11 in the X direction, a plurality of modified points 12s are formed so as to be arranged in a single column (row) in the X direction. One modified point 12s is formed by irradiation with a single pulse of laser light L. A single column of modified regions 12 is a collection of multiple modified points 12s arranged in a single column. Adjacent modified points 12s may be connected to each other or spaced apart, depending on the relative movement speed of the focal point C with respect to the object 11 and the repetition frequency of the laser light L.

[0048] The drive unit 4 rotates the stage 2 about an axis parallel to the Z direction. The drive unit 4 can also move the stage 2 in each of the X and Y directions. The drive unit 5 supports the laser irradiation unit 3. The drive unit 5 moves the laser irradiation unit 3 in the X, Y, and Z directions. In a state where the focal point C of the laser light L is formed, the focal point C is moved relative to the object 11 by moving the stage 2 and / or the laser irradiation unit 3. That is, the drive units 4 and 5 are moving mechanisms that move at least one of the stage 2 and the laser irradiation unit 3 to move the focal point C of the laser light L relative to the object 11.

[0049] The control unit 6 controls the operation of the stage 2, the laser irradiation unit 3, and the driving units 4 and 5. The control unit 6 includes: a processing unit 61, a storage unit 62, and an input acceptance unit (display unit, input unit) 63. The processing unit 61 is configured as a computer device including a processor, a memory, a storage, and a communication device. In the processing unit 61, the processor executes software (programs) read into the memory, etc., controls the reading and writing of data in the memory and the storage, and controls the communication of the communication device. The storage unit 62 is, for example, a hard disk, etc., which stores various data. The input acceptance unit 63 is an interface unit that displays various information and accepts input of various information from the user. In this embodiment, the input acceptance unit 63 constitutes a GUI (Graphical User Interface).

[0050] Figure 2 and Figure 3 Yes Figure 1 Schematic diagram of the structure of the laser irradiation part shown in FIG. Figure 2 、 3 As shown, the laser irradiation unit 3 includes a light source 31, a spatial light modulator 32, and a condenser lens 33. The light source 31 outputs laser light L by, for example, pulse oscillation. However, the laser irradiation unit 3 may not include the light source 31, but may be configured to introduce laser light L from outside the laser irradiation unit 3.

[0051] The spatial light modulator 32 modulates the laser light L output from the light source 31. The spatial light modulator 32 is a spatial light modulator (SLM) of reflective liquid crystal (LCOS: Liquid Crystal on Silicon). The focusing lens 33 focuses the laser light L modulated by the spatial light modulator 32. The spatial light modulator 32 includes a liquid crystal layer (not shown) and modulates the laser light L according to the modulation pattern displayed by the liquid crystal layer. Here, the spatial light modulator 32 at least displays a beam splitting (branching) pattern for splitting the laser light L into a plurality of beams (here, two). As a result, the laser light L incident on the spatial light modulator 32 is split into two laser lights L1 and L2 in the spatial light modulator 32, and is focused by the focusing lens 33 to form a focal point C1 and a focal point C2.

[0052] This point will be described in more detail below. The spatial light modulator 32 at least splits the laser light L to form a focal point C1 and a focal point C2 at different positions in the Z direction intersecting the back surface 11b, the incident surface of the laser light L, within the object 11. Consequently, by moving the focal points C1 and C2 relative to the object 11, two rows of modified regions 121 and 122 are formed as the modified regions 12 at different positions in the Z direction.

[0053] Modified region 121 corresponds to laser light L1 and its focal point C1, while modified region 122 corresponds to laser light L2 and its focal point C2. Converging point C1 and modified region 121 are located on the opposite side of rear surface 11b (on the surface 11a side of object 11) relative to converging point C2 and modified region 122. The spatial light modulator 32 is configured to change the distance Dz (the amount of longitudinal beam splitting) between converging points C1 and C2 in the Z direction by adjusting the beam splitting pattern.

[0054] Furthermore, the spatial light modulator 32 is configured to change the distance Dx (lateral splitting amount) between the focal points C1 and C2 in the horizontal direction (X direction in the example shown) when splitting the laser light L into the laser lights L1 and L2. Figure 2 In the example, the spatial light modulator 32 makes the distance Dx greater than 0 so that the focal point C1 is located ahead of the focal point C2 in the X direction (processing direction). Figure 3 In the example of , the spatial light modulator 32 sets the distance Dx between the focal point C1 and the focal point C2 to zero.

[0055] Next, the present inventors' knowledge and findings will be described by comparing processing examples. Figure 4This is a cross-sectional view showing the processing of Example 1. In Example 1, focal point C1 is located ahead of focal point C2 in the X direction (distance Dx > 0), and the distance Dz between focal points C1 and C2 in the Z direction is smaller. Here, crack 121c extending from modified region 121 formed at the preceding focal point C1 is connected to crack 122c extending from modified region 122 formed at focal point C2. This forms crack 12c extending between modified regions 121 and 122 and toward both front surface 11a and back surface 11b.

[0056] Figure 5 This is a cross-sectional photograph showing the processing result of the first example. Figure 5 (a) is an example of a situation in which the first irradiation (scan P1) of the laser light L1 and L2 according to the first example is performed on the side of the object 11 that is away from the incident surface of the laser light L1 and L2, that is, the back side 11b (the side close to the surface 11a), and the second irradiation (scan P2) of the laser light L1 and L2 according to the first example is performed on the side close to the back side 11b. Figure 5 (b) is an example of a case where the first scan P1 according to the first example is performed on the side close to the back surface 11b, and the second scan P2 according to the second example is performed on the side far from the back surface 11b.

[0057] The irradiation conditions of the lasers L1 and L2 in the scans P1 and P2 are as follows: frequency 80 kHz, processing speed 530 mm / s, pulse spacing 6.625 μm, pulse width 400 nsec, and pulse energy of 15.40625 μj at the focal points C1 and C2.

[0058] Figure 5 In any case, Figure 4 The crack 12c shown, particularly the portion of crack 122c extending from the modified region 122 to the back surface 11b, exhibits a varying degree of extension (crack extent) depending on the X-direction position. As a result, for example, crack 12c can meander to a depth of 10 μm or more before reaching the back surface 11b. Furthermore, uncut regions may occur, leaving a portion of the other side of the object 11 as if it had been pulled apart. Specifically, this deteriorates processing quality.

[0059] In particular, in the first example, multiple reformed regions 12 extending in the Y direction (line M1) have already been formed, and laser beams L1 and L2 are irradiated in the X direction across these reformed regions 12. The crack size tends to increase as the process moves past one reformed region 12 (extending in the Y-axis direction) and toward another reformed region 12 immediately following the reformed region 12 in the X direction, the processing direction.

[0060] Furthermore, the crack size of crack 12c decreases immediately after passing the other modified region 12, then increases again as it moves toward another modified region 12. In other words, in this case, the crack size repeatedly increases and decreases with the spacing of the modified regions 12 extending in the Y direction. As a result, the unstable crack size has a greater impact on processing quality. This effect is particularly pronounced as the spacing (chip size) of the modified regions 12 extending in the Y direction decreases.

[0061] on the other hand, Figure 6 This is a cross-sectional view showing the processing of the second example. In the second example, as in the first example, the focal point C1 is located ahead of the focal point C2 in the X direction (distance Dx>0), but the distance Dz between the focal point C1 and the focal point C2 in the Z direction is larger. Figure 6 As shown in (a) and (b) of FIG. 1 , irradiation with the laser beams L1 and L2 is performed while preventing the cracks 121 c extending from the reformed region 121 and the cracks 122 c extending from the reformed region 122 from connecting to each other.

[0062] Moreover, in the second example, if Figure 6 As shown in (b) and (c) of FIG. 1 , by positioning the third focal point C3 of laser light L3 between the focal points C1 and C2 and irradiating the object 11 with laser light L3, crack 123c is formed, extending from the modified region 123 formed at the third focal point C3 and extending between the modified regions 121 and 122. Crack 122c and crack 121c further extend due to the formation of crack 123c, forming crack 12c extending from the front surface 11a to the back surface 11b as a whole.

[0063] Figure 7 This is a cross-sectional photograph showing the processing result of the second example. Figure 7 (a) is an example of a case where, after the first irradiation (scan P1) of the laser L1 and L2 according to the second example, only the focal point C1 is located between the position of the focal point C1 of the first scan P1 and the position of the focal point C2, and the second irradiation (scan P2) of the laser L1 and L2 according to the second example is performed. Figure 7 (b) is an example of a case where, after performing the first scan P1 according to the second example, both the focal points C1 and C2 are positioned between the positions of the focal points C1 and C2 in the first scan P1, and a second scan P2 according to the second example is performed. The irradiation conditions of the laser beams L1 and L2 are the same as those in the first example.

[0064] exist Figure 7 In any case, the crack amount is stable regardless of the position in the X direction. As a result, for example, the meandering amount of the crack 12c reaching the back surface 11b is Figure 7 In the case of (a), it is 4.5 μm. Figure 7 In the case of (b), it is 3.2 μm, which is smaller than that of Example 1. This can suppress the degradation of processing quality.

[0065] Next, an example of a laser processing method executed by the laser processing apparatus 1 will be given to explain the laser processing apparatus in detail. Figure 8 : is a flow chart showing an example of the laser processing method of this embodiment. Figure 9 As shown, the object 11 is supported on the stage 2 with its back surface 11b facing the laser irradiation unit 3. Multiple lines (first lines) M1 and multiple lines (second lines) M2 are set on the object 11. The lines M1 and M2 are set by the control unit 6. For example, the lines M1 and M2 are virtual lines or lines with specified coordinates.

[0066] Multiple lines M1 extend parallel to one another. Furthermore, multiple lines M2 extend parallel to one another. Lines M1 and M2 extend so as to intersect (orthogonally intersect) one another when viewed in the Z direction. That is, line M2 extends so as to cross (stride over) multiple lines M1 when viewed in the Z direction. Here, processing is first performed along lines M1, and then object 11 is positioned so that lines M1 extend along the X direction (here, the first direction) and lines M2 extend along the Y direction (here, the second direction).

[0067] In the laser processing apparatus 1 (laser processing method), processing conditions for processing along line M1 are first input (step S1). More specifically, in step S1, the control unit 6 causes the input receiving unit 63 to display a message urging the input of processing conditions. The input receiving unit 63 then receives the input of processing conditions.

[0068] Furthermore, the processing along the line M1 is performed under the condition that the modified region 12 is not formed in the object 11. Therefore, as described above, the unstable crack amount has little influence on the processing quality. Therefore, the processing along the line M1 can be performed according to either the first or second example described above. Therefore, the processing conditions that can be input in this step S1 are also arbitrary. As an example, the processing conditions described below can be input. Figure 12 The processing conditions shown are the same processing conditions (according to the processing conditions of the above-mentioned Example 2).

[0069] Next, the control unit 6 sets (generates) a modulation pattern to be displayed on the spatial light modulator 32 based on the processing conditions input in step S1 (step S2). Here, the control unit 6 sets a modulation pattern including a splitting pattern for splitting the laser light L into a plurality of beams. As a result, the laser light L passing through the spatial light modulator 32 displaying the modulation pattern is as follows: Figure 10As shown, the laser light is divided into the laser light L1A and the laser light L2A, forming the focusing point (the fifth focusing point) C1A and the focusing point (the sixth focusing point) C2A of the laser light L1A.

[0070] Then, if Figure 10 As shown, processing is performed along line M1 (step S3, first treatment, first step). In summary, the control unit 6 controls the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) to irradiate the object 11 with laser light L while relatively moving the focal point C along line M1, thereby forming a modified region 12 along line M1 (laser irradiation step).

[0071] More specifically, here, control unit 6 controls laser irradiation unit 3 and drive unit 5 (and / or drive unit 4) to form a focal point C1A of laser light L1A and a focal point C2A of laser light L2A located on the back surface 11b side of object 11 relative to focal point C1A. Furthermore, while relatively moving focal points C1A and C2A along line M1, laser light L1A and laser light L2A are irradiated onto object 11. Consequently, modified region 12 is formed as modified region 12: modified region 121A corresponding to laser light L1A and focal point C1A, and modified region 122A corresponding to laser light L2A and focal point C2A.

[0072] In particular, in processing along line M1, as described above, any processing can be performed, but processing according to the second example can also be performed. In this case, the control unit 6 can first control the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) to irradiate the object 11 with laser light L1A and L2A while relatively moving the focal points C1A and C2A along line M1 so that the cracks extending from the modified region 121A formed at the focal point C1A and the cracks extending from the modified region 122A formed at the focal point C2A are not connected to each other, thereby forming the modified regions 121A and 122A along line M (the fourth process).

[0073] Afterwards, the control unit 6 further performs the following process, that is, by controlling the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4), a focal point (7th focal point) of the laser L is formed at a position (7th position) between the position of the focal point C1A (5th position) and the position of the focal point C2A (6th position) in the Z direction, and while the 7th focal point is relatively moved along the line M1, the laser L is irradiated to the object 11, thereby forming a modified region 12 along the line M1 at the 7th position, thereby forming a crack between the modified region 121A formed at the 5th position and the modified region 122A formed at the 6th position (5th treatment).

[0074] The above first process is performed on all lines M1. Figure 11 As shown, the reformed regions 12 are formed along all the lines M1. As a result, in the processing along the subsequent lines M2, the laser light L is irradiated over (across) the reformed regions 12 already formed along the lines M1.

[0075] In the next step, processing is performed along line M2. To this end, control unit 6 controls drive unit 4 to rotate stage 2, positioning object 11 so that line M2 is along the X direction. During processing along line M2, laser light L is at least split into laser light L1 and laser light L2. Laser light L1 and laser light L2 are irradiated (scanned) along line M2 while moving respective focal points C1 and C2 relative to object 11.

[0076] Next, the processing conditions for processing along line M2 are input (step S4). More specifically, in step S4, the control unit 6 causes the input receiving unit 63 to display a message urging the input of processing conditions. The input receiving unit 63 then receives the input of processing conditions. In this case, the input receiving unit 63 receives at least the input of the distance Dz. The input receiving unit 63 also receives input of various other processing conditions. This will be described in detail.

[0077] Figure 12 : is a diagram showing an example of a setting screen displayed by the input receiving unit. Figure 12 As shown, here, the input of wafer thickness, LBA-X offset, and LBA-Y offset (and the input of distance Dx) is accepted as the selection Q. The LBA-X offset is the offset in the X direction (along the line M2) between the center of the spherical aberration correction pattern, one of the various patterns displayed by the spatial light modulator 32, and the center of the entrance pupil plane of the condenser lens 33. The LBA-Y offset is similarly the offset in the Y direction (a direction intersecting the line M2) between the center of the spherical aberration correction pattern and the center of the entrance pupil plane of the condenser lens 33.

[0078] The input receiving unit 63 also receives input of the number of focal points, number of passes, processing speed, pulse width, and frequency, which serve as basic processing conditions H0. The number of focal points refers to the number of beams into which the spatial light modulator 32 splits the laser light L, which is two in this example. The number of passes refers to the number of times the second process (described later) is performed on one line M2, representing the number of scans by the laser light L1 and L2. A number of modified regions 12 corresponding to the number of focal points multiplied by the number of passes is formed in the Z direction. The processing speed refers to the speed at which the focal points C1 and C2 move relative to the object 11.

[0079] Furthermore, the input accepting unit 63 accepts input of detailed processing conditions for each scan. Here, since 3 is entered as the pass number, the input accepting unit 63 accepts input of processing conditions H1 to H3 for each of the three scans. In processing conditions H1 to H3, ZH (lower point) corresponds to the position of the focal point C1 in the Z direction. ZH (upper point) corresponds to the position of the focal point C2 in the Z direction. Since ZH (lower point) and ZH (upper point) are based on the back surface 11b, the incident surface of laser beams L1 and L2, larger values indicate greater distance from the back surface 11b.

[0080] The longitudinal splitting distance (VD) is the distance Dz, equivalent to the difference between ZH (lower point) and ZH (upper point). The processing power (lower point) is the power of laser L1, and the processing power (upper point) is the power of laser L2. Here, the processing power (lower point) and the processing power (upper point) are input with the same value. Therefore, the power ratio of laser L1 to laser L2 is 50:50.

[0081] In the next step, the control unit 6 sets (generates) a modulation pattern to be displayed by the spatial light modulator 32 based on the processing conditions input in step S4 (step S5). Here, the control unit 6 sets a modulation pattern including a splitting pattern for splitting the laser light L into a plurality of beams. Thus, the laser light L passing through the spatial light modulator 32 displaying the modulation pattern is as follows: Figure 13 As shown in FIG. 1 , the laser beam is split into the laser beam L1 and the laser beam L2 , forming a converging point (first converging point) C1 of the laser beam L1 and a converging point (second converging point) C2 of the laser beam L1 .

[0082] Next, processing is actually performed along line M2 (step S6, second treatment, second step). Briefly, the control unit 6 controls the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) to irradiate the object 11 with laser light L while relatively moving the focal point C along line M2, thereby forming a modified region 12 along line M2 (laser irradiation step).

[0083] More specifically, the first scan is performed. Figure 13 As shown in (a), the control unit 6 forms a focal point C1 of the laser L1 and a focal point C2 of the laser L2 located on the back side 11b of the focal point C1 by controlling the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4) as in the second example above, and irradiates the laser lights L1 and L2 onto the object 11 while moving the focal point C1 and the focal point C2 relative to each other along the line M2 in a manner such that the crack 121c extending from the modified region 121 formed at the focal point C1 and the crack 122c extending from the modified region 122 formed at the focal point C2 are not connected to each other, thereby forming a modified region 12 along the line M2.

[0084] Here, the control unit 6 adjusts the beam splitting pattern displayed on the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the distance Dz between the light-converging points C1 and C2 becomes the input value of the processing condition H1 corresponding to the first scan. Furthermore, as an example, the control unit 6 adjusts the beam splitting pattern displayed on the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the light-converging point C1 is positioned ahead of the light-converging point C2 in the X direction, which is the relative movement direction of the light-converging points C1 and C2. Specifically, the distance Dx is set to be greater than 0.

[0085] The control unit 6 can also adjust the beam splitting pattern displayed on the spatial light modulator 32 (i.e., by controlling the laser irradiation unit 3) based on the input, so that the focal points C1 and C2 coincide with each other in the X direction. In other words, the distance Dx can also be set to 0.

[0086] As described above, the modified region 12 has already been formed along the line M1 in the object 11. Therefore, in the first scan, the laser beams L1 and L2 are irradiated across (across) the modified region 12 that has already been formed. Figure 13 As shown in (b), the modified regions 121 and 122 are formed over the entire line M2 so that the cracks 121c and 122c are not connected to each other. In this case, the crack 121c does not reach the front surface 11a, and the crack 122c does not reach the back surface 11b.

[0087] Next, the second scan is performed (step S6, second processing, second step). Figure 14 As shown in (a), the control unit 6 forms a focal point C1 of the laser L1 and a focal point C2 of the laser L2 located on the back side 11b of the focal point C1 by controlling the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4) as in the second example above, and irradiates the laser lights L1 and L2 onto the object 11 while moving the focal points C1 and C2 relative to each other along the line M2 in a manner such that the crack 121c extending from the modified region 121 formed at the focal point C1 and the crack 122c extending from the modified region 122 formed at the focal point C2 are not connected to each other, thereby forming a modified region 12 along the line M2.

[0088] Here, the control unit 6 adjusts the beam splitting pattern displayed on the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the distance Dz between the focal points C1 and C2 becomes the input value of the processing condition H2 corresponding to the second scan. Specifically, the control unit 6 performs the second scan with both the focal points C1 and C2 positioned between the position of the focal point C1 (modified region 121) and the position of the focal point C2 (modified region 122) in the first scan. In other words, the distance Dz in the second scan is smaller than the distance Dz in the first scan.

[0089] Here, as an example, the control unit 6 adjusts the beam splitting pattern displayed by the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the focal point C1 is positioned ahead of the focal point C2 in the processing direction, i.e., the direction of relative movement between the focal points C1 and C2, in the X direction. In other words, the distance Dx is set larger than 0.

[0090] The control unit 6 can also adjust the beam splitting pattern displayed on the spatial light modulator 32 (i.e., by controlling the laser irradiation unit 3) based on the input so that the focal points C1 and C2 are aligned in the X direction. In other words, the distance Dx can also be set to 0.

[0091] Here, the laser beams L1 and L2 are irradiated across (across) the formed reformed region 12. Figure 14 As shown in (b), modified regions 121 and 122 are formed between the modified regions 121 and 122 formed in the first scan, extending across the entirety of line M2, so that crack 121c and crack 122c are not connected to each other. Furthermore, crack 121c formed in the first scan and crack 121c formed in the second scan are not connected to each other (although they may be connected). Furthermore, crack 122c formed in the first scan and crack 122c formed in the second scan are not connected to each other. Crack 121c does not reach surface 11a, and crack 122c does not reach back surface 11b.

[0092] In the subsequent process, the control unit 6 further controls the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4) to irradiate the laser L onto the object 11 while moving the focal point C relatively along the line M2, thereby forming a modified area 12 along the line M2.

[0093] More specifically, the control unit 6 performs the third scan (step S7, third processing, third step). Figure 15As shown in (a), the control unit 6 splits the laser L into lasers L3a and L3b, and forms a focal point (third focal point) C3a of the laser L3a and a focal point (fourth focal point) C3b of the laser L3b located on the back side 11b relative to the focal point C3a.

[0094] Then, the control unit 6 controls the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4) to form the focal points C3a and C3b of the laser beams L3a and L3b at the third position between the position of the focal point C1 (first position) and the position of the focal point C2 (second position) in the Z direction of the second scan, and irradiates the laser beams L3a and L3b onto the object 11 while relatively moving the focal points C3a and C3b along the line M2. Figure 15 As shown in (b), modified regions 123a and 123b are formed at the third position along line M2, thereby forming a crack 123c that extends between the modified region 121 formed at the first position and the modified region 122 formed at the second position and toward the surface 11a and the back surface 11b.

[0095] Here, the control unit 6 adjusts the beam splitting pattern displayed by the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the distance Dz between the focal points C3a and C3b becomes the input value of the processing condition H3 corresponding to the third scan. Specifically, the control unit 6 performs the third scan with both the focal points C3a and C3b positioned between the first position (modified region 121) of the focal point C1 in the second scan and the second position (modified region 122) of the focal point C2 in the second scan. In other words, the distance Dz is smaller than the distances Dz of the first and second scans.

[0096] Here, as an example, the control unit 6 adjusts the beam splitting pattern displayed by the spatial light modulator 32 (i.e., controls the laser irradiation unit 3) so that the light-converging point C3a is located ahead of the light-converging point C3b in the X direction, which is the processing direction, which is the direction of relative movement between the light-converging points C3a and C3b. In other words, here, the distance Dx is greater than 0.

[0097] However, the control unit 6 can also adjust the beam splitting pattern displayed by the spatial light modulator 32 (i.e., by controlling the laser irradiation unit 3) based on input, thereby aligning the focal points C3a and C3b in the X direction. In other words, the distance Dx can also be set to zero. The above second and third processes are performed on all lines M2. Thus, modified regions 12 are formed along all lines M1 and M2. As a result, the object 11 can be cut along the lines M1 and M2.

[0098] As described above, in the laser processing apparatus 1 and its laser processing method, a line M1 and a line M2 extending beyond line M1 are set for the object 11. After laser light L is irradiated along line M1 to form a modified region 12, laser light L is irradiated along line M2 to form a modified region 12. When laser light L is irradiated along line M2, at least two focal points C1 and C2 are formed in the Z direction. This increases the processing speed. On the other hand, in the laser processing apparatus 1 and its laser processing method, laser light L is irradiated beyond the modified region 12 already formed along line M1. Therefore, it is important to suppress the destabilization of cracks.

[0099] Therefore, in the laser processing device 1 and the laser processing method thereof, after the modified region 12 is formed along the line M1, the lasers L1 and L2 are first irradiated onto the object 11 while the focal point C1 and the focal point C2 are relatively moved along the line M2 in a manner such that the crack 121c extending from the modified region 121 formed at the focal point C1 of the laser L1 and the crack 122c extending from the modified region 122 formed at the focal point C2 of the laser L2 are not connected to each other, thereby forming the modified regions 121 and 122 along the line M2. Then, a focal point C3a of laser light L3a is formed at a third position between the first position of focal point C1 and the second position of focal point C2. While focal point C3a is relatively moved along line M2, laser light L3a is irradiated onto object 11. This forms modified region 123a along line M2 at the third position, thereby forming crack 123c extending between modified region 121 and modified region 122. This prevents the overall cracking amount from becoming unstable, thereby suppressing degradation in processing quality.

[0100] Furthermore, in the laser processing apparatus 1, the control unit 6 controls the laser irradiation unit 3 during the second process so that the focal point C1 is positioned forward of the focal point C2 in the direction of relative movement between the focal points C1 and C2. This increases the extent to which cracks 121c and 122c extend from the modified regions 121 and 122 formed at the focal points C1 and C2, respectively. This reduces the number of rows of modified regions 12 required in the Z direction, thereby increasing processing speed.

[0101] On the other hand, in the laser processing apparatus 1, the control unit 6 can also control the laser irradiation unit 3 during the second process to align the focal point C1 with the focal point C2 in the X direction. In this case, the amount by which cracks 121c and 122c extend from the reformed regions 121 and 122 formed at the focal points C1 and C2, respectively, can be reduced. This reliably prevents the crack 121c extending from the reformed region 121 formed at the focal point C1 from connecting with the crack 122c extending from the reformed region 122 formed at the focal point C2.

[0102] Furthermore, in the laser processing apparatus 1, the control unit 6 controls the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) in the third process to form a light-converging point C3a and a light-converging point C3b of the laser light L3b located on the back surface 11b side of the light-converging point C3a, and irradiates the object 11 with the laser light L3a and L3b while relatively moving the light-converging points C3a and C3b along the line M2. Consequently, the processing speed can be further increased.

[0103] Furthermore, in the laser processing apparatus 1, the control unit 6 controls the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) in the first process to form a focal point C1A of the laser beam L1A and a focal point C2A of the laser beam L2A located closer to the back surface 11b than the focal point C1A. The control unit 6 then irradiates the object 11 with the laser beams L1A and L2A while relatively moving the focal points C1A and C2A along the line M1. Consequently, the processing speed can be further improved.

[0104] Furthermore, in the laser processing device 1, the control unit 6 can also perform in the first process: by controlling the laser irradiation unit 3 and the driving unit 5 (and / or the driving unit 4), the crack extending from the modified area 121A formed at the focal point C1A and the crack extending from the modified area 122A formed at the focal point C2A are not connected to each other, while the focal point C1A and the focal point C2A are moved relative to each other along the line M2, and the laser L1A and L2A are irradiated onto the object 11, thereby forming the fourth process of modifying the areas 121A and 122A along the line M1.

[0105] In this case, after the fourth process, a fifth process may be performed in which the laser irradiation unit 3 and the drive unit 5 (and / or the drive unit 4) are controlled to form a focal point of laser light L at a seventh position between the fifth position of the focal point C1A and the sixth position of the focal point C2A in the Z direction, and while relatively moving the focal point along the line M1, the laser light L is irradiated onto the object 11, thereby forming a reformed region 12 along the line M1 at the seventh position, thereby forming a crack extending between the reformed region 121A and the reformed region 122A. In this case, for the same reasons as described above, it is possible to achieve an increase in processing speed and a suppression of degradation in processing quality in the first process as well.

[0106] The above embodiment is an example of the present invention, and therefore, the present invention is not limited to the above embodiment and can be modified.

[0107] For example, in the above embodiment, a case where three scans are performed by the second process and the third process is described. However, the number of scans by the second process and the third process is arbitrary.

[0108] Furthermore, in the above-described embodiment, in the third process, irradiation with laser light L3a and laser light L3b is performed with both the focal points C3a and C3b of laser light L3a and laser light L3b located between the modified regions 121 and 122 formed in the second process. However, in the third process, laser light irradiation may be performed while at least one focal point is located between the modified regions 121 and 122 formed in the second process, thereby forming a crack extending between the modified regions 121 and 122.

[0109] Furthermore, the relationship between the distance Dz during scanning in the second process and the third process is not limited to the above example.

[0110] Furthermore, in the above embodiment, the control unit 6 (input receiving unit 63) displays the prompt Figure 12 However, the control unit 6 may also be configured to cause the input receiving unit 63 to display a prompt Figure 12 The information of the input of a part of the values shown is obtained, and when the input accepting unit 63 accepts the input of the part, the other part of the processing conditions is proposed.

[0111] As an example, the control unit 6 may cause the input accepting unit 63 to display information prompting input of the selection content Q and the values included in the basic processing condition H0 , and propose the most appropriate processing conditions H1 to H3 when the input accepting unit 63 accepts the input.

[0112] In addition, Figure 7In the example (a), in the scan P2, a modified region 121 is formed between the modified regions 121 and 122 formed by the scan P1, and another modified region 122 is formed outside the modified regions 121 and 122 (that is, the modified regions are formed alternately by the scans P1 and P2). The formation of such modified regions can also be Figure 15 The third process shown is performed. That is, Figure 15 , an example is shown in which a pair of modified regions 123a and 123b are formed in the third process between the modified regions 121 and 122 formed in the second process. However, for example, in the third process, modified region 123a may be formed between modified regions 121 and 122, while modified region 123b may be formed outside modified regions 121 and 122. In other words, in the third process, cracks extending between modified regions 121 and 122 may be formed by forming at least one row of modified regions between modified regions 121 and 122 formed in the second process.

[0113] Here, as described above, the following meaning is explained: after the modified region 12 is formed along multiple lines M1, when the modified region 12 is formed on the line M2 set in a manner that crosses the line M1, the part with less crack amount and the part with more crack amount repeatedly occur in a short period (the formation spacing of the modified region 12, etc.), so the overall instability of the crack amount has a relatively large impact on the processing quality, so it is important to use the laser irradiation method with the above characteristics.

[0114] However, even when laser light L is irradiated only on the portion of object 11 where modified region 12 is not formed, as in the case of forming modified region 12 along line M1, the cracking amount may vary from the start point to the end point of laser light L irradiation. Therefore, by employing the aforementioned characteristic laser irradiation method, it is possible to increase processing speed and suppress degradation in processing quality. In other words, the aforementioned characteristic laser irradiation method can be employed regardless of whether the processing is along line M1 or line M2. Therefore, the following additional notes are provided.

[0115] (Note) The laser processing device 1 is used to irradiate the laser L onto the object 11 to form a modified area 12, and includes: a stage 2 for supporting the object 11; a laser irradiation unit 3 for irradiating the object 11 supported by the stage 2 with the laser L; driving units 4, 5 for moving at least one of the stage 2 and the laser irradiation unit 3 to move the focal point C of the laser L relative to the object 11; and a control unit 6 for controlling the laser irradiation unit 3 and the driving units 4, 5. The control unit 6 is capable of performing the following processing: by controlling the laser irradiation unit 3 and the driving units 4 and 5, a focal point C1 of the laser L1 and a focal point C2 of the laser L2 located on the back side 11b side than the focal point C1 are formed, and the focal points C1 and C2 are moved relative to each other in a manner such that the crack 121c extending from the modified area 121 formed at the focal point C1 and the crack 122c extending from the modified area 122 formed at the focal point C2 are not connected to each other, thereby irradiating the laser L1 and L2 onto the object 11, thereby forming the processing of the modified areas 121 and 122.

[0116] In addition, after this processing, the control unit 6 can perform the following other processing: by controlling the laser irradiation unit 3 and the driving units 4 and 5, the focal point C3a of the laser L3a is formed at the third position between the first position of the focal point C1 and the second position of the focal point C2 in the direction intersecting the back side 11b, and while the focal point C3a is relatively moved, the laser L3a is irradiated to the object 11, thereby forming the modified area at the third position, thereby forming a crack between the modified area 121 formed at the first position and the modified area 122 formed at the second position.

[0117] Industrial applicability

[0118] The present invention provides a laser processing device and a laser processing method that can simultaneously achieve an increase in processing speed and a suppression of a decrease in processing quality.

[0119] Description of Reference Signs

[0120] 1: Laser processing equipment

[0121] 2: Stage (supporting part)

[0122] 3: Laser irradiation part

[0123] 4: Driving unit (moving mechanism)

[0124] 5: Driving unit (moving mechanism)

[0125] 6: Control Department

[0126] 11: Object

[0127] 12,121,122,123a,123b: Modified region

[0128] 12c, 121c, 122c: cracks

[0129] C: Spotlight

[0130] C1: Converging point (first converging point)

[0131] C2: Converging point (second converging point)

[0132] C3a, C3b: Converging point (the third converging point)

[0133] L, L1, L2, L3a, L3b: Laser

[0134] M1: Line (1st line)

[0135] M2: line (second line).

Claims

1. A laser processing apparatus for forming a modified region by irradiating an object with laser light, the laser processing apparatus comprising: a supporting portion for supporting the object; a laser irradiation unit for irradiating the object supported by the support unit with the laser light; a moving mechanism that moves at least one of the support portion and the laser irradiation portion to move the focal point of the laser light relative to the object; and a control unit that controls the laser irradiation unit and the moving mechanism, When the object is viewed from a direction intersecting the incident surface of the laser beam, a first line extending in a first direction and a second line extending beyond the first line in a second direction intersecting the first direction are set. The control unit performs the following first process, second process and third process: The first process forms the modified region along the first line by irradiating the object with the laser light while relatively moving the focal point along the first line by controlling the laser irradiation unit and the moving mechanism. The second process, after the first process, forms a first light-converging point of the laser light and a second light-converging point of the laser light that is located on the side of the incident surface of the object relative to the first light-converging point by controlling the laser irradiation unit and the moving mechanism, and irradiates the object with the laser light while relatively moving the first light-converging point and the second light-converging point along the second line in a manner such that cracks extending from the modified region formed at the first light-converging point and cracks extending from the modified region formed at the second light-converging point are not connected to each other, thereby forming the modified region along the second line. The third treatment is to form a third light-converging point of the laser light at a third position between the first position of the first light-converging point and the second position of the second light-converging point in a direction intersecting the incident surface by controlling the laser irradiation unit and the moving mechanism after the second treatment, and to irradiate the object with the laser light while relatively moving the third light-converging point along the second line, thereby forming the modified region along the second line at the third position, thereby forming a crack extending between the modified region formed at the first position and the modified region formed at the second position. The control unit prevents, in the second process, cracks extending from the first modified region, which is the modified region formed at the first light-converging point, from reaching the back surface of the object opposite to the incident surface, and prevents cracks extending from the second modified region, which is the modified region formed at the second light-converging point, from reaching the incident surface. In the third process, the control unit forms cracks extending between the first modified region and the second modified region, and causes the cracks extending from the first modified region to reach the rear surface and the cracks extending from the second modified region to reach the incident surface.

2. The laser processing device according to claim 1, wherein: The control unit controls the laser irradiation unit in the second process so that the first light-converging point is positioned ahead of the second light-converging point in the relative movement direction of the first light-converging point and the second light-converging point.

3. The laser processing device according to claim 1, wherein: The control unit controls the laser irradiation unit in the second process so as to make the first light-converging point coincide with the second light-converging point in the direction of relative movement between the first light-converging point and the second light-converging point.

4. The laser processing device according to any one of claims 1 to 3, wherein: The control unit forms the third focal point and the fourth focal point of the laser light located on the side of the incident surface compared to the third focal point by controlling the laser irradiation unit and the moving mechanism in the third process, and irradiates the object with the laser light while moving the third focal point and the fourth focal point relative to each other along the second line.

5. The laser processing device according to any one of claims 1 to 3, wherein: The control unit forms a fifth focal point of the laser and a sixth focal point of the laser located on the side of the incident surface of the object relative to the fifth focal point by controlling the laser irradiation unit and the moving mechanism in the first process, and irradiates the object with the laser while causing the fifth focal point and the sixth focal point to move relative to each other along the first line.

6. The laser processing device according to claim 4, wherein: The control unit forms a fifth focal point of the laser and a sixth focal point of the laser located on the side of the incident surface of the object relative to the fifth focal point by controlling the laser irradiation unit and the moving mechanism in the first process, and irradiates the object with the laser while causing the fifth focal point and the sixth focal point to move relative to each other along the first line.

7. The laser processing device according to claim 5, wherein: The control unit executes the following fourth and fifth processes in the first process: The fourth process is to irradiate the object with the laser light while relatively moving the fifth and sixth light-converging points along the first line, thereby forming the modified region along the first line, by controlling the laser irradiation unit and the moving mechanism so that the crack extending from the modified region formed at the fifth light-converging point and the crack extending from the modified region formed at the sixth light-converging point are not connected to each other. The fifth treatment, after the fourth treatment, forms the seventh focal point of the laser at the seventh position between the fifth position of the fifth focal point and the sixth position of the sixth focal point in the direction intersecting the incident surface by controlling the laser irradiation part and the moving mechanism, and irradiates the object with the laser while relatively moving the seventh focal point along the first line, thereby forming the modified area at the seventh position along the first line, thereby forming a crack between the modified area formed at the fifth position and the modified area formed at the sixth position.

8. The laser processing device according to claim 6, wherein: The control unit executes the following fourth and fifth processes in the first process: The fourth process is to irradiate the object with the laser light while relatively moving the fifth and sixth light-converging points along the first line, thereby forming the modified region along the first line, by controlling the laser irradiation unit and the moving mechanism so that the crack extending from the modified region formed at the fifth light-converging point and the crack extending from the modified region formed at the sixth light-converging point are not connected to each other. The fifth treatment, after the fourth treatment, forms the seventh focal point of the laser at the seventh position between the fifth position of the fifth focal point and the sixth position of the sixth focal point in the direction intersecting the incident surface by controlling the laser irradiation part and the moving mechanism, and irradiates the object with the laser while relatively moving the seventh focal point along the first line, thereby forming the modified area at the seventh position along the first line, thereby forming a crack between the modified area formed at the fifth position and the modified area formed at the sixth position.

9. A laser processing method for forming a modified region by irradiating an object with laser light, the laser processing method comprising: a laser irradiation step of irradiating the object with the laser light while moving the focal point of the laser light relative to the object to form a modified region; When the object is viewed from a direction intersecting the incident surface of the laser beam, a first line extending in a first direction and a second line extending beyond the first line in a second direction intersecting the first direction are set. The laser irradiation process includes: a first step of irradiating the object with the laser light while relatively moving the focal point along the first line, thereby forming the modified region along the first line; a second step of forming, after the first step, a first light-converging point of the laser light and a second light-converging point of the laser light on a side closer to the incident surface of the object than the first light-converging point, and irradiating the object with the laser light while relatively moving the first light-converging point along the second line so that cracks extending from the modified region formed at the first light-converging point and cracks extending from the modified region formed at the second light-converging point are not connected to each other, thereby forming the modified region along the second line; and A third step is to form a third light-converging point of the laser beam at a third position between the first position of the first light-converging point and the second position of the second light-converging point in a direction intersecting the incident surface after the second step, and to irradiate the object with the laser beam while relatively moving the third light-converging point along the second line, thereby forming the modified region along the second line at the third position, thereby forming a crack extending between the modified region formed at the first position and the modified region formed at the second position. In the second step, cracks extending from the first modified region, which is the modified region formed at the first light-converging point, are prevented from reaching the back surface of the object opposite to the incident surface, and cracks extending from the second modified region, which is the modified region formed at the second light-converging point, are prevented from reaching the incident surface. In the third step, cracks are formed extending between the first reformed region and the second reformed region, and the cracks extending from the first reformed region are made to reach the rear surface, while the cracks extending from the second reformed region are made to reach the incident surface.

10. A laser processing device for forming a modified region by irradiating an object with laser light, the laser processing device comprising: a supporting portion for supporting the object; a laser irradiation unit for irradiating the object supported by the support unit with the laser light; a moving mechanism that moves at least one of the support portion and the laser irradiation portion to move the focal point of the laser light relative to the object; and a control unit that controls the laser irradiation unit and the moving mechanism, The control unit performs the following modified region forming process and crack forming process, wherein: The modified region forming process forms a first focal point of the laser light and a second focal point of the laser light that is located on the side of the incident surface of the laser light of the object with respect to the first focal point by controlling the laser irradiation unit and the moving mechanism, and irradiates the object with the laser light while relatively moving the first focal point and the second focal point so that cracks extending from the modified region formed at the first focal point and cracks extending from the modified region formed at the second focal point are not connected to each other, thereby forming the modified region. The crack forming process, after the modified region forming process, forms a third light-converging point of the laser light at a third position between the first position of the first light-converging point and the second position of the second light-converging point in a direction intersecting the incident surface by controlling the laser irradiation unit and the moving mechanism, and irradiates the object with the laser light while relatively moving the third light-converging point, thereby forming the modified region at the third position, thereby forming a crack extending between the modified region formed at the first position and the modified region formed at the second position, The control unit prevents cracks extending from a first modified region, which is the modified region formed at the first light-converging point, from reaching a back surface of the object opposite to the incident surface, and prevents cracks extending from a second modified region, which is the modified region formed at the second light-converging point, from reaching the incident surface during the modified region forming process. The control unit forms a crack extending between the first modified region and the second modified region in the crack forming process, and causes the crack extending from the first modified region to reach the back surface and the crack extending from the second modified region to reach the incident surface.

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