Laser processing device and laser processing method

Abstract

To provide a technique capable of reducing the waviness of a substrate.SOLUTION: A laser processing apparatus comprises: a holder configured to hold a substrate; a light source configured to oscillate a laser beam to be radiated to a first main surface of the substrate; a moving unit configured to move a position of a radiation point of the laser beam on the first main surface of the substrate in a state that the substrate is held by the holder; and a controller configured to control the light source and the moving unit. The controller controls the light source and the moving unit to radiate the laser beam to the first main surface of the substrate to reduce waviness of the first main surface of the substrate. The holding part holds the substrate so as not be deformed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Patent Document 1 describes a semiconductor wafer processing method in which semiconductor wafers obtained by slicing a single crystal ingot are subjected to a chamfering step, a lapping step, an etching step, and a mirror polishing step. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2002-203823 Summary of the Invention [Problem to be solved by the invention]

[0004] One aspect of the present disclosure provides a technique for reducing waviness in a substrate. [Means for solving the problem]

[0005] A laser processing apparatus according to one aspect of the present disclosure includes a holder for holding a substrate, a light source for emitting a laser beam to be irradiated onto a first main surface of the substrate, a moving unit for moving a position of an irradiation point of the laser beam on the first main surface of the substrate while the substrate is held by the holder, and a control unit for controlling the light source and the moving unit. held by the holding part The laser beam is irradiated onto the first main surface of the substrate, thereby reducing waviness of the first main surface of the substrate. Laser processing Take control. When performing the laser processing control, The holding portion holds the substrate without deforming it. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, waviness of a substrate can be reduced. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a laser processing device according to an embodiment. [Figure 2] FIG. 2 is a front view of the laser processing apparatus of FIG. [Figure 3] FIG. 3(A) is a side view showing an example of a substrate before laser processing, and FIG. 3(B) is a side view showing an example of a substrate after laser processing. [Figure 4] FIG. 4 is a flowchart showing a laser processing method according to one embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a waviness measurement module. [Figure 6] FIG. 6 is a diagram illustrating an example of a laser processing module. [Figure 7] FIG. 7(A) is a diagram showing a first example of the intensity distribution of a laser beam, and FIG. 7(B) is a diagram showing a second example of the intensity distribution of a laser beam. [Figure 8] Figure 8(A) is a plan view showing a first example of how the irradiation points are arranged, Figure 8(B) is a plan view showing a second example of how the irradiation points are arranged, and Figure 8(C) is a plan view showing a third example of how the irradiation points are arranged. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In this specification, the X-axis, Y-axis, and Z-axis directions are perpendicular to each other. The X-axis and Y-axis directions are horizontal directions, and the Z-axis direction is vertical.

[0009] First, a laser processing apparatus 1 according to this embodiment will be described with reference to Figures 1 and 2. The laser processing apparatus 1 performs laser processing on a substrate W obtained by slicing a single crystal ingot.

[0010] The substrate W is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is not particularly limited, but may be, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. The substrate W is a bare wafer.

[0011] As shown in FIG. 3A, the substrate W includes a first main surface Wa and a second main surface Wb facing opposite to the first main surface Wa. The first main surface Wa and the second main surface Wb are formed by slicing a single crystal ingot. During slicing, debris may adhere to the first main surface Wa and the second main surface Wb. The debris may be, for example, abrasive grains from a cutting blade.

[0012] 3(B), the laser processing apparatus 1 removes the surface layer Wa1 from the entire first main surface Wa of the substrate W, and removes the surface layer Wb1 from the entire second main surface Wb of the substrate W. This removes debris that has adhered to the substrate W when the single crystal ingot is sliced, and suppresses the occurrence of defects in the substrate W due to the debris.

[0013] 1, the laser processing device 1 includes a carry-in / out station 2, a processing station 3, and a control module 9. The carry-in / out station 2 and the processing station 3 are arranged in this order in the positive direction of the X axis.

[0014] The loading / unloading station 2 comprises a mounting table 20 and a transport section 23. The mounting table 20 comprises a plurality of mounting plates 21. The plurality of mounting plates 21 are arranged in a row in the Y-axis direction. A cassette C is placed on each of the plurality of (e.g., three) mounting plates 21. One cassette C accommodates a plurality of substrates W before processing. Another cassette C accommodates a plurality of substrates W after processing. The remaining cassette C accommodates a plurality of substrates W that have experienced an abnormality during processing. The number of mounting plates 21 and the number of cassettes C are not particularly limited.

[0015] The transport unit 23 is disposed adjacent to the mounting table 20 on the positive side of the X-axis, and adjacent to the processing station 3 on the negative side of the X-axis. The transport unit 23 includes a transport arm 24 that holds the substrate W. The transport arm 24 is capable of moving horizontally (in both the X-axis and Y-axis directions) and vertically, and of rotating about a vertical axis. The transport arm 24 transports the substrate W between the cassette C on the mounting table 20 and the third processing block G3 of the processing station 3.

[0016] The processing station 3 includes a first processing block G1, a second processing block G2, a third processing block G3, a fourth processing block G4, and a transport block G5. The transport block G5 is located in an area surrounded by the first processing block G1, the second processing block G2, the third processing block G3, and the fourth processing block G4. The third processing block G3 is located adjacent to the transport block G5 on the negative side of the X-axis.

[0017] The transport block G5 is equipped with a transport arm 38 that holds the substrate W. The transport arm 38 is capable of moving horizontally (in both the X-axis and Y-axis directions) and vertically, and of rotating about a vertical axis. The transport arm 38 transports the substrate W between the first processing block G1, the second processing block G2, the third processing block G3, and the fourth processing block G4.

[0018] The first processing block G1 is disposed adjacent to the transport block G5 on the positive side of the Y axis. The first processing block G1 includes, for example, a laser processing module 31. The laser processing module 31 irradiates a first main surface Wa of the substrate W with a laser beam to remove a surface layer Wa1 from the entire first main surface Wa. The laser processing module 31 also irradiates a second main surface Wb of the substrate W with a laser beam to remove a surface layer Wb1 from the entire second main surface Wb. The surface layers Wa1, Wb1 absorb the laser beam and either change from a solid phase to a gas phase and scatter, or remain in the solid phase and scatter.

[0019] The second processing block G2 is disposed adjacent to the transport block G5 on the negative side of the Y axis. The second processing block G2 includes, for example, a cleaning module 32 and an etching module 33. The cleaning module 32 scrubs the substrate W to remove debris scattered from the substrate W at the point of irradiation with the laser beam. The etching module 33 etches the substrate W to reduce the surface roughness of the substrate W or remove a discolored layer caused by irradiation with the laser beam. Note that if debris removal is not required, the cleaning module 32 is not required. Also, if surface roughness reduction or discolored layer removal is not required, the etching module 33 is not required. The arrangement of the cleaning module 32 and the etching module 33 is not limited to that shown in FIG. 2.

[0020] The third processing block G3 is disposed adjacent to the transfer block G5 on the negative side of the X-axis. As shown in FIG. 2, the third processing block G3 includes, for example, a transition module 34, a swell measurement module 35, and an inversion module 36. The transition module 34 transfers the substrate W between the transfer arm 24 of the load / unload station 2 and the transfer arm 38 of the processing station 3. The swell measurement module 35 measures the swell of the first main surface Wa of the substrate W. The swell measurement module 35 also measures the swell of the second main surface Wb of the substrate W. A commercially available three-dimensional shape measuring device or the like is used for measuring the swell. The inversion module 36 inverts the substrate W. The arrangement of the transition module 34, the swell measurement module 35, and the inversion module 36 is not limited to that shown in FIG.

[0021] The fourth processing block G4 is disposed adjacent to the transport block G5 on the positive side of the X axis. The fourth processing block G4 includes, for example, a grinding module 37. The grinding module 37 grinds the first main surface Wa of the substrate W to improve the flatness of the first main surface Wa. The grinding module 37 also grinds the second main surface Wb of the substrate W to improve the flatness of the second main surface Wb. Note that if sufficient flatness can be obtained by irradiating the substrate with a laser beam, the grinding module 37 is not necessary.

[0022] It is sufficient that the processing station 3 has at least the laser processing module 31. The types, arrangement, and number of modules constituting the processing station 3 are not limited to those shown in FIGS.

[0023] The control module 9 is, for example, a computer, and includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory. The storage medium 92 stores programs that control various processes executed in the laser processing apparatus 1. The control module 9 controls the operation of the laser processing apparatus 1 by having the CPU 91 execute the programs stored in the storage medium 92.

[0024] Next, the laser processing method according to this embodiment will be described with reference to Fig. 4. Steps S101 to S109 shown in Fig. 4 are performed under the control of the control module 9.

[0025] First, the transfer arm 24 of the load / unload station 2 takes out the substrate W from the cassette C on the mounting table 20 and transfers it to the transition module 34. Next, the transfer arm 38 of the processing station 3 receives the substrate W from the transition module 34 and transfers it to the waviness measurement module 35. During this time, the substrate W is held horizontally with its first main surface Wa facing upward.

[0026] Next, the swell measurement module 35 measures the swell of the first main surface Wa of the substrate W (step S101). The swell measurement is performed in a natural state where no external forces other than gravity and its resistance, such as an adsorption force, are acting. The natural state is a state in which the substrate W is not deformed and the stress on the substrate surface is substantially zero. For example, as shown in FIG. 5, the swell measurement is performed with the substrate W simply placed on the horizontal surface of the stage 35a. The swell measurement module 35 has a displacement meter 35b. The displacement meter 35b measures the height distribution of the upper surface (e.g., the first main surface Wa) of the substrate W. In this embodiment, the displacement meter 35b is of a non-contact type, but may be of a contact type. The swell measurement module 35 transmits the measurement data to the control module 9. After step S101, the transfer arm 38 removes the substrate W from the swell measurement module 35 and transfers it to the laser processing module 31.

[0027] Next, the laser processing module 31 performs laser processing on the first main surface Wa of the substrate W (step S102). Specifically, as shown in Fig. 6, the laser processing module 31 irradiates the first main surface Wa with a laser beam LB, moves the position of the irradiation point P over the entire first main surface Wa, and removes the surface layer Wa1 over the entire first main surface Wa.

[0028] Debris adheres to the surface layer Wa1 when the single crystal ingot is sliced. If grinding (including polishing) is performed on the substrate W with the debris still attached, the debris will be pressed against the substrate W, causing defects in the substrate W. The resulting defects may be enlarged by subsequent etching.

[0029] According to this embodiment, since the surface layer Wa1 is removed, it is possible to remove debris adhering to the surface layer Wa1. Furthermore, since the surface layer Wa1 is removed, it is possible to remove debris that cannot be removed by brush cleaning or the like. Therefore, it is possible to suppress the occurrence of defects in the substrate W due to debris.

[0030] Furthermore, the laser processing module 31 may reduce waviness of the first principal surface Wa when removing the surface layer Wa1. The removal amount is controlled by the integrated irradiation amount (unit: J), which is the product of the output (unit: W) of the laser beam LB and the irradiation time. The greater the integrated irradiation amount, the greater the removal amount.

[0031] The control module 9 refers to the measurement data of the waviness measurement module 35 and controls the integrated dose of the laser beam LB per unit area of ​​the first principal surface Wa so as to reduce waviness of the first principal surface Wa. The control includes one or more selected from control of the output of the light source 31b and control of the irradiation time.

[0032] If the substrate W is pressed against a surface plate during polishing in order to reduce the waviness of the first main surface Wa, the substrate W will be elastically deformed. Therefore, it is difficult to reduce the waviness of the substrate W. Furthermore, debris will be pressed against the substrate W, causing defects in the substrate W.

[0033] According to this embodiment, the control module 9 controls the integrated irradiation amount per unit area by referring to measurement data of the waviness of the first principal surface Wa in its natural state, so that the waviness can be efficiently reduced and efficiently corrected to a flat surface.

[0034] The laser processing of the first principal surface Wa is performed in a natural state, for example, with the substrate W simply placed on the horizontal surface of the stage 31a. Even if a foreign object is present between the substrate W and the stage 31a, the foreign object is not pressed against the substrate W, so no defects are produced on the substrate W.

[0035] Unlike waviness measurement, laser processing of the first principal surface Wa may be performed while the substrate W is attached to the horizontal surface of the stage 31a. Since the amount of surface layer Wa1 removed is determined by the cumulative irradiation dose, waviness can be reduced. Furthermore, suction prevents the substrate W from shifting position.

[0036] After step S102, the transfer arm 38 takes out the substrate W from the laser processing module 31 and transfers it to the cleaning module 32.

[0037] Next, the cleaning module 32 scrubs the substrate W (step S103) to remove debris scattered from the irradiation point P of the laser beam LB from the substrate W. After step S103, the transport arm 38 takes out the substrate W from the cleaning module 32 and transports it to the inversion module 36.

[0038] Next, the inversion module 36 inverts the substrate W (step S104) so ​​that the second main surface Wb of the substrate W faces upward. After step S104, the transport arm 38 takes out the substrate W from the inversion module 36 and transports it again to the waviness measurement module 35. During this time, the substrate W is held horizontally with the second main surface Wb facing upward.

[0039] Next, the swell measurement module 35 measures the swell of the second main surface Wb of the substrate W (step S105). The swell measurement is performed in a natural state, for example, with the substrate W simply placed on the horizontal surface of the stage 35a. The displacement gauge 35b measures the height distribution of the second main surface Wb of the substrate W. The swell measurement module 35 transmits the measurement data to the control module 9. After step S105, the transport arm 38 takes the substrate W out of the swell measurement module 35 and transports it again to the laser processing module 31.

[0040] Next, the laser processing module 31 performs laser processing on the second main surface Wb of the substrate W (step S106). Specifically, the laser processing module 31 irradiates the second main surface Wb with a laser beam LB, moves the position of the irradiation point P over the entire second main surface Wb, and removes the surface layer Wb1 over the entire second main surface Wb.

[0041] According to this embodiment, since the surface layer Wb1 is removed, it is possible to remove debris adhering to the surface layer Wb1. Furthermore, since the surface layer Wb1 is removed, it is possible to remove debris that cannot be removed by brush cleaning or the like. Therefore, it is possible to suppress the occurrence of defects on the substrate W due to debris.

[0042] Furthermore, the laser processing module 31 may reduce waviness of the second principal surface Wb when removing the surface layer Wb1. The removal amount is controlled by the integrated irradiation amount (unit: J), which is the product of the output (unit: W) of the laser beam LB and the irradiation time. The greater the integrated irradiation amount, the greater the removal amount.

[0043] The control module 9 controls the integrated dose of the laser beam LB per unit area of ​​the second principal surface Wb so as to reduce the waviness of the second principal surface Wb, with reference to the measurement data of the waviness measurement module 35. The control includes one or more selected from control of the output of the light source 31b and control of the irradiation time.

[0044] According to this embodiment, the control module 9 controls the integrated irradiation amount per unit area by referring to measurement data of the waviness of the second main surface Wb in its natural state, thereby efficiently reducing the waviness and efficiently straightening it to a flat surface.

[0045] The laser processing of the second main surface Wb is performed in a natural state, for example, with the substrate W simply placed on the horizontal surface of the stage 31a. Even if a foreign object is present between the substrate W and the stage 31a, the foreign object is not pressed against the substrate W, so no defects are produced on the substrate W.

[0046] Unlike waviness measurement, laser processing of the second main surface Wb may be performed while the substrate W is attached to the horizontal surface of the stage 31a. Since the amount of surface layer Wb1 removed is determined by the cumulative irradiation dose, waviness can be reduced. Furthermore, suction prevents the substrate W from shifting position.

[0047] After step S106, the transfer arm 38 takes out the substrate W from the laser processing module 31 and transfers it to the cleaning module 32 again.

[0048] Next, the cleaning module 32 scrubs the substrate W (step S107) to remove debris scattered from the irradiation point P of the laser beam LB from the substrate W. After step S107, the transport arm 38 takes out the substrate W from the cleaning module 32 and transports it to the etching module 33.

[0049] Next, the etching module 33 etches the substrate W (step S108) to reduce the surface roughness of the substrate W or remove a discolored layer by irradiating it with a laser beam. The etching module 33, for example, wet-etches the substrate W, simultaneously etching the first main surface Wa and the second main surface Wb of the substrate W. The etching module 33 may dry-etch the substrate W, or may sequentially etch the first main surface Wa and the second main surface Wb of the substrate W. After step S108, the transfer arm 38 removes the substrate W from the etching module 33 and transfers it to the grinding module 37.

[0050] Next, the grinding module 37 grinds the substrate W (step S109) to improve the flatness of the substrate W. The grinding module 37 grinds the first main surface Wa of the substrate W to improve the flatness of the first main surface Wa. The grinding module 37 may also grind the second main surface Wb of the substrate W to improve the flatness of the second main surface Wb. Grinding of the first main surface Wa and grinding of the second main surface Wb are performed in order, with the substrate W being turned over midway. Note that the grinding includes polishing. The order of grinding the substrate W (step S109) and etching the substrate W (S108) may be reversed. For example, grinding of the substrate W may be performed, followed by cleaning of both surfaces of the substrate W, and then etching of the substrate W. The etching may be double-sided etching or single-sided etching.

[0051] Finally, the transfer arm 38 takes the substrate W out of the grinding module 37 and transfers it to the transition module 34. Subsequently, the transfer arm 24 of the load / unload station 2 takes the substrate W out of the transition module 34 and stores the substrate W in the cassette C on the mounting table 20.

[0052] Next, a laser processing module 31 according to this embodiment will be described with reference to Fig. 6. The laser processing module 31 includes, for example, a stage 31a serving as a holding unit, a light source 31b, and a galvanometer scanner 31c serving as a moving unit. The laser processing module 31 also includes an fθ lens 31d, a homogenizer 31e, and an aperture 31f.

[0053] The stage 31a holds the substrate W. For example, the stage 31a holds the substrate W horizontally from below with the main surface of the substrate W, which is to be irradiated with the laser beam LB, facing upward. The stage 31a holds the substrate W in its natural state without suction. Note that although the stage 31a in this embodiment does not suction the substrate W, it may suction it. In the latter case, the stage 31a is a vacuum chuck or an electrostatic chuck.

[0054] The light source 31b emits a laser beam LB that is irradiated onto the upper surface (e.g., the first main surface Wa) of the substrate W. The laser beam LB is absorbed by the substrate W. If the substrate W is a silicon wafer, the laser beam LB is, for example, UV light. The substrate W absorbs the laser beam LB and either changes state from a solid phase to a gas phase and scatters, or scatters while remaining in the solid phase. As a result, the surface layer Wa1 of the first main surface Wa of the substrate W is removed. The laser beam LB may be focused and irradiated onto the upper surface of the substrate W. In this embodiment, the irradiation point P is a focal point where the power density is highest. However, the irradiation point P does not have to be a focal point.

[0055] The light source 31b is, for example, a pulsed laser. The irradiation time per pulse is, for example, 30 nsec or less. If the irradiation time per pulse is 30 nsec or less, the substrate W can be irradiated with a laser beam LB of high power density in a short period of time, and overheating of the substrate W can be suppressed. Therefore, deterioration of the substrate W due to heat can be suppressed, and for example, the occurrence of a discolored layer can be suppressed. The irradiation time per pulse is preferably 10 psec or less. If the irradiation time per pulse is 10 psec or less, deterioration of the substrate W due to heat can be suppressed even if irradiation points P are formed multiple times in the same location.

[0056] The galvanometer scanner 31c is disposed, for example, above the substrate W held by the stage 31a. The galvanometer scanner 31c allows the position of the irradiation point P of the laser beam LB on the upper surface of the substrate W to be moved without moving the stage 31a. Even when the stage 31a does not adsorb the substrate W, no positional deviation of the substrate W with respect to the stage 31a occurs as long as the stage 31a does not move. Therefore, the position of the irradiation point P can be controlled with high precision.

[0057] The galvanometer scanner 31c includes two pairs of a galvanometer mirror 31c1 and a galvanometer motor 31c2 (only one pair is shown in FIG. 6). One galvanometer motor 31c2 rotates one galvanometer mirror 31c1 to displace the irradiation point P in the X-axis direction. Another galvanometer motor 31c2 rotates another galvanometer mirror 31c1 to displace the irradiation point P in the Y-axis direction.

[0058] Although the moving unit in this embodiment is a galvanometer scanner 31c, the technology of the present disclosure is not limited thereto. The moving unit may include a polygon scanner instead of the galvanometer scanner 31c. A polygon scanner has a faster scanning speed and can use a high-frequency pulse laser compared to the galvanometer scanner 31c. The moving unit may move the position of the irradiation point P of the laser beam LB on the first main surface Wa of the substrate W while the substrate W is held on the stage 31a. For example, the moving unit may move the stage 31a in the X-axis and Y-axis directions, or may include a motor and a ball screw mechanism that converts the rotational motion of the motor into linear motion of the stage 31a. The moving unit may also include a mechanism that rotates the stage 31a around a vertical axis.

[0059] The fθ lens 31d forms a focal plane perpendicular to the Z-axis direction. While the galvanometer scanner 31c moves the position of the irradiation point P in the X-axis direction or the Y-axis direction, the fθ lens 31d maintains the Z-axis position of the irradiation point P on the focal plane, and also maintains the shape and dimensions of the irradiation point P on the focal plane. As a result, as will be described later, rectangular irradiation points P can be arranged regularly and two-dimensionally without gaps on the upper surface of the substrate W. The height of the irradiation point P is the height of the focal plane.

[0060] The homogenizer 31e converts the intensity distribution of the laser beam LB from the Gaussian distribution shown in FIG. 7(A) to the top-hat distribution shown in FIG. 7(B), thereby homogenizing the intensity distribution.

[0061] Aperture 31f shapes the cross section of laser beam LB into a rectangle. Rectangles include not only rectangular but also square shapes. Aperture 31f is a light-blocking film with a rectangular opening. The opening allows laser beam LB to pass through within the range indicated by arrow D in FIG. 7(B), for example.

[0062] The homogenizer 31e and the aperture 31f can form rectangular irradiation points P with a uniform intensity distribution. By arranging the irradiation points P regularly and without gaps two-dimensionally as described below, the cumulative irradiation amount of the laser beam LB per unit area can be controlled with high precision.

[0063] As shown in Figure 8(A), the irradiation point P is a rectangle with a uniform intensity distribution, with two sides of the rectangle parallel to the X-axis direction and the remaining two sides of the rectangle parallel to the Y-axis direction. The X-axis dimension X0 of the irradiation point P may be the same as or different from the Y-axis dimension Y0 of the irradiation point P. This is the same in Figures 8(B) and 8(C).

[0064] 8(A), while pulsating the laser beam LB, the control module 9 moves the irradiation point P in the X-axis direction by X0 increments during the pulse off times, arranging the irradiation points P in a line without gaps across the entire X-axis direction of the upper surface of the substrate W. Thereafter, while pulsating the laser beam LB, the control module 9 repeatedly moves the irradiation point P in the Y-axis direction by Y0 in the pulse off times and moves the irradiation point P in the X-axis direction by X0 increments during the pulse off times, thereby arranging the irradiation points P in a two-dimensional line without gaps across the entire upper surface of the substrate W.

[0065] Alternatively, as shown in FIG. 8(B), the control module 9, while pulsating the laser beam LB, moves the irradiation point P in the X-axis direction by half the value of X0 during the pulse-off time, thereby arranging the irradiation points P in a line while overlapping them across the entire X-axis direction of the upper surface of the substrate W. Thereafter, while pulsing the laser beam LB, the control module 9 repeatedly moves the irradiation point P in the Y-axis direction by Y0 during the pulse-off time and moves the irradiation point P in the X-axis direction by half the value of X0 during the pulse-off time, thereby arranging the irradiation points P two-dimensionally without gaps across the entire upper surface of the substrate W. Note that, instead of moving the irradiation point P in the Y-axis direction by Y0 during the pulse-off time, the control module 9 may also move the irradiation point P in the Y-axis direction by half the value of Y0 during the pulse-off time while pulsing the laser beam LB.

[0066] Alternatively, as shown in Figure 8(C), the control module 9, while pulsating the laser beam LB, moves the irradiation point P in the X-axis direction by twice X0 during the pulse off time, forming gaps SP across the entire X-axis direction of the upper surface of the substrate W and arranging the irradiation points P in a line. Next, the control module 9, while pulsating the laser beam LB again, moves the irradiation point P in the X-axis direction by twice X0 during the pulse off time so as to fill the gaps SP with the irradiation points P. Thereafter, while pulsing the laser beam LB, the control module 9 repeats the following steps: moves the irradiation point P in the Y-axis direction by Y0 during the pulse off time, moves the irradiation point P in the X-axis direction by twice X0 during the pulse off time, and moves the irradiation point P in the X-axis direction by twice X0 during the pulse off time so as to fill the gaps SP with the irradiation points P, thereby arranging the irradiation points P two-dimensionally without gaps.

[0067] In this embodiment, a waviness measurement module 35 and an inversion module 36 are provided in addition to the laser processing module 31, but the technology of the present disclosure is not limited to this. The laser processing module 31 may have the function of the waviness measurement module 35. Furthermore, the laser processing module 31 may have the function of the inversion module 36.

[0068] Although the embodiments of the laser processing apparatus and laser processing method according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0069] This application claims priority based on Japanese Patent Application No. 2020-151606, filed with the Japan Patent Office on September 9, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0070] 1. Laser processing equipment 9 Control module (control unit) 31 Laser Processing Module 31a Stage (holding part) 31b Light source 31c Moving part (galvanometer scanner)

Claims

1. a holder for holding the substrate; a light source that emits a laser beam to be irradiated onto the first main surface of the substrate; a moving unit that moves a position of an irradiation point of the laser beam on the first main surface of the substrate while the substrate is held by the holding unit; a control unit that controls the light source and the moving unit; Equipped with the control unit controls the light source and the moving unit to irradiate the laser beam onto the first main surface of the substrate held by the holding unit, and performs laser processing control to reduce waviness of the first main surface of the substrate; The laser processing device, wherein the holding unit holds the substrate without deforming it when performing the laser processing control.

2. The laser processing apparatus according to claim 1 , wherein the control unit performs the laser processing control to reduce the waviness of the first main surface by referring to measurement data of the waviness of the first main surface.

3. 3. The laser processing apparatus according to claim 2, wherein the control unit performs the laser processing control to reduce the waviness of the first main surface by referring to measurement data of the waviness of the first main surface and controlling an integrated irradiation amount of the laser beam per unit area of ​​the first main surface.

4. 4. The laser processing apparatus according to claim 1, further comprising a waviness measuring unit that measures waviness of the first main surface of the substrate in a state in which stress on the first main surface of the substrate is substantially zero.

5. 5. The laser processing device according to claim 1, further comprising a grinding unit that grinds the first main surface after the laser beam has been irradiated.

6. 6. The laser processing device according to claim 1, further comprising an etching unit that etches the first main surface after the laser beam has been irradiated.

7. an inversion unit that inverts the substrate, The control unit 7. The laser processing device according to claim 1, wherein after irradiating the first main surface of the substrate with the laser beam, the device performs control to invert the substrate and control to irradiate a second main surface of the substrate opposite to the first main surface, in this order.

8. The laser processing device according to claim 7 , further comprising a grinding unit that grinds the second main surface after the laser beam has been irradiated.

9. The laser processing apparatus according to claim 7 or 8, further comprising an etching unit that etches the second main surface after the laser beam has been irradiated thereon.

10. holding the substrate with a holder; irradiating a laser beam onto a first main surface of the substrate while the substrate is held by the holding unit, thereby performing laser processing to reduce waviness of the first main surface of the substrate; Including, The laser processing method, wherein the holding part holds the substrate without deforming it when performing the laser processing.

11. The laser processing method according to claim 10 , wherein the laser processing is performed to reduce the waviness of the first main surface by referring to measurement data of the waviness of the first main surface.

12. 12. The laser processing method according to claim 11, wherein the laser processing is performed to reduce the waviness of the first main surface by referring to measurement data of the waviness of the first main surface and controlling an integrated irradiation amount of the laser beam per unit area of ​​the first main surface.

13. The laser processing method according to any one of claims 10 to 12, further comprising measuring waviness of the first main surface of the substrate in a state where stress on the first main surface of the substrate is substantially zero.

14. The laser processing method according to any one of claims 10 to 13, further comprising grinding the first main surface after the irradiation with the laser beam.

15. The laser processing method according to any one of claims 10 to 14, further comprising etching the first main surface after being irradiated with the laser beam.

16. 16. The laser processing method according to claim 10, further comprising: irradiating the first main surface of the substrate with the laser beam, then inverting the substrate; and irradiating a second main surface of the substrate facing opposite to the first main surface with the laser beam, in this order.

17. The laser processing method according to claim 16, further comprising grinding the second main surface after the irradiation with the laser beam.

18. The laser processing method according to claim 16 or 17, further comprising etching the second main surface after being irradiated with the laser beam.

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