Laser processing support device and laser processing method

Abstract

To provide a laser processing support device that can reduce bias in terms of regions to which laser beams are actually made incident, on a surface of an object to be processed.SOLUTION: Scanning operation of scanning an allowable irradiation region in a first direction, by making a pulse laser beam incident to the allowable irradiation region on a surface of an object to be processed, and stepping operation of moving beam spots of the pulse laser beam in a second direction orthogonal to the first direction are alternately repeated. A processing device obtains information for designating a dimension in the second direction of the allowable irradiation region, a dimension in the second direction of the beam spots and an overlap rate of the beam spots during the stepping operation. An offset width is determined so that a difference between the offset width that is a distance in the second direction from an end part in the second direction of the allowable irradiation region to a scanning region which is scanned by the first scanning operation, of the allowable irradiation region and an irradiation remaining width that is a distance from a region which is scanned by the last scanning operation to the end part in the second direction of the allowable irradiation region is equal to 20% or less of the sum of the offset width and the irradiation remaining width.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Laser annealing, in which a pulsed laser beam is incident on the wafer and the beam spot is moved within the wafer surface, is known as an annealing method for activating dopants doped in a semiconductor wafer (see, for example, Patent Document 1). If the beam spot extends beyond the wafer during laser annealing, the stage holding the wafer by suction will be damaged. Furthermore, as the wafer becomes thinner, the edge of the wafer becomes brittle, and irradiating this area with a laser beam may damage the wafer. To prevent damage to the stage or wafer, an irradiation-prohibited area is defined around the periphery of the wafer. A circular irradiation-permitted area surrounded by this irradiation-prohibited area is scanned with a pulsed laser beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-202242 Summary of the Invention [Problem to be solved by the invention]

[0004] When performing laser annealing, a scanning operation that moves the beam spot in a first direction from one end of the irradiation allowable area to the other end and a stepping operation that moves the beam spot in a second direction perpendicular to the first direction are repeated. In the scanning operation, the beam spot is moved so that it partially overlaps with the beam spot of the previous shot. In the stepping operation, the beam spot is moved so that the scanned area by the scanning operation after the stepping operation partially overlaps with the scanned area by the scanning operation before the stepping operation. The overlap rate of the beam spots is called the overlap rate.

[0005] The size of the beam spot in the moving direction of the stepping motion and the overlap rate during the stepping motion are predetermined. If the size of the irradiation allowable area in the moving direction of the stepping motion is not divisible by the amount of movement in the stepping motion, some of the area will remain unirradiated at the end of the processing end direction of the stepping motion. In this case, the area within the irradiation allowable area that is actually irradiated with the pulse laser beam will be biased toward the irradiation start side of the moving direction during the stepping motion.

[0006] An object of the present invention is to provide a laser processing support device and a laser processing method that can reduce bias in the area on the surface of an object to be processed that is actually irradiated with a laser beam. [Means for solving the problem]

[0007] According to one aspect of the present invention, A laser processing support device that supports laser processing by alternately repeating a scanning operation of scanning the surface of a processing object with the pulsed laser beam in a first direction and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction perpendicular to the first direction under a condition that the pulsed laser beam is incident on a surface of the processing object and the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object, Based on the dimension of the beam spot in the second direction, the moving distance of the beam spot in the second direction during the step operation, and the dimension of an irradiation allowable area inside the irradiation prohibited area in the second direction, There is provided a laser processing support device that determines an offset width, which is the distance in the second direction from an end of the irradiation allowance area in the second direction to an area of ​​the irradiation allowance area scanned by the first scanning operation.

[0008] According to another aspect of the present invention, A laser processing support device that supports laser processing by alternately repeating a scanning operation of scanning the surface of a processing object with the pulsed laser beam in a first direction and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction perpendicular to the first direction under a condition that the pulsed laser beam is incident on a surface of the processing object and the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object, an input / output device; Processing equipment Equipped with The processing device includes: acquiring, from the input / output device, information specifying a dimension in the second direction of an irradiation allowable region on the surface of the processing object that is inside the irradiation prohibition region, a dimension in the second direction of the beam spot, and an overlap rate of the beam spot during the step operation; A laser processing support device is provided that determines the offset width, which is the distance in the second direction from the end of the irradiation allowable area to the scanned area of ​​the irradiation allowable area by the first scanning operation, and the remaining irradiation width, which is the distance from the scanned area by the last scanning operation to the end of the irradiation allowable area in the second direction, so that the difference between the offset width and the remaining irradiation width is 20% or less of the sum of the offset width and the remaining irradiation width, and outputs information specifying the offset width to the input / output device.

[0009] According to yet another aspect of the present invention, A laser processing method comprising: a scanning operation of scanning the surface of a processing object with the pulsed laser beam in a first direction under a condition that the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object; and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction orthogonal to the first direction, the method comprising: The scanning operation is started from a position offset inward by an offset width from one end of the irradiation allowable area that is inside the irradiation prohibition area in the second direction, When the stepping operation causes the beam spot to extend beyond an end of the irradiation allowable area in the second direction, the scanning operation is terminated; There is provided a laser processing method in which the offset width is set so that the difference between the remaining irradiation width, which is the distance from the scanning area by the scanning operation after the last step operation to the other end of the irradiation allowable area in the second direction, and the offset width is 20% or less of the sum of the offset width and the remaining irradiation width. [Effects of the Invention]

[0010] By specifying the offset width as described above, it is possible to reduce the deviation of the area on the surface of the processing object onto which the laser beam is actually incident. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a laser processing support device and a laser processing device according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the movement of the beam spot of the pulse laser beam on the surface of the processing object. [Figure 3] FIG. 3 is a schematic diagram for explaining a target area on the surface of the processing object onto which the pulsed laser beam is incident. [Figure 4] FIG. 4 is a schematic diagram showing the trajectory of movement of the beam spot. [Figure 5] FIG. 5 is a flowchart showing the procedure for moving the beam spot. [Figure 6] FIG. 6 is a flowchart showing a procedure for determining the offset width OFFs. [Figure 7] FIG. 7 is a schematic diagram showing the relationship between the dimension Ay of the irradiation allowable area in the y direction, the dimension Ly of the beam spot in the y direction, the overlap rate ROVL in the y direction, and the number N of scanning operations. [Figure 8]Figure 8A is a schematic diagram showing a scanning area onto which a pulse laser beam is incident in one scanning operation when the method according to the embodiment shown in Figures 1 to 7 is applied, and Figure 8B is a schematic diagram showing a scanning area onto which a pulse laser beam is incident in one scanning operation when the scanning operation is performed by applying a method according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] A laser processing support device and a laser processing method according to one embodiment will be described with reference to FIGS.

[0013] 1 is a schematic diagram of a laser processing support device and a laser processing device according to this embodiment. A laser oscillator 10 outputs a pulsed laser beam. The pulsed laser beam output from the laser oscillator 10 passes through a beam expander 11, a beam shaping optical element 12, and a folding mirror 13 and is incident on a processing object 60. An aperture, a lens, etc. may be provided as necessary. The processing object 60 is, for example, a semiconductor wafer into which dopant ions have been implanted, and activation annealing of the dopant is performed by irradiating the pulsed laser beam.

[0014] The processing object 60 is held by a chuck mechanism 18 supported by a drive mechanism 17. The drive mechanism 17 moves the chuck mechanism 18 in two directions in a horizontal plane. The movement of the chuck mechanism 18 moves the processing object 60. An XY stage, for example, is used as the drive mechanism 17.

[0015] The laser oscillator 10 may be, for example, a fiber laser oscillator, a laser diode, or a solid-state laser oscillator. The beam expander 11 adjusts the beam size of the laser beam at the incident position on the beam shaping optical element 12. The beam shaping optical element 12 shapes the beam spot on the surface of the processing object 60 and homogenizes the intensity distribution. The beam shaping optical element 12 may be, for example, a diffractive optical element.

[0016] The control device 40 controls the driving mechanism 17 and the laser oscillator 10. For example, the control device 40 controls the driving mechanism 17 so that the pulsed laser beam is incident on a target position on the surface of the processing object 60. Furthermore, the control device 40 controls the output timing of the pulsed laser beam from the laser oscillator 10.

[0017] The laser processing support device 20 includes a processing device 21 and an input / output device 22. The input / output device 22 includes a keyboard and a pointing device that are operated by a user to input various information, a reader / writer that reads data from and writes data to removable media, a communication device that transmits and receives various information, a display that displays images, etc. The processing device 21 acquires the various information input to the input / output device 22 and obtains information that supports control by the control device 40. Detailed processing performed by the processing device 21 will be described later.

[0018] 2 is a schematic diagram showing the movement of the beam spot 30 of the pulsed laser beam on the surface of the processing object 60 (FIG. 1). In this embodiment, the path of the pulsed laser beam is fixed, and the processing object 60 is moved, thereby moving the beam spot 30 relative to the processing object 60.

[0019] An xyz Cartesian coordinate system is defined with the surface of the processing object 60 as the xy plane. The shape of the beam spot 30 is a rounded rectangle that is longer in the y direction. The dimension (length) of the beam spot 30 in the y direction is denoted as Ly, and the dimension (width) in the x direction is denoted as Lx.

[0020] Annealing is performed by alternately repeating a scanning process in which the surface of the processing object 60 is scanned with a pulsed laser beam in the x direction and a stepping operation in which the beam spot 30 is moved in the y direction. During the scanning operation, the distance that the beam spot 30 moves in the x direction during one pulse repetition period of the pulsed laser beam is denoted as Wx. The moving distance Wx is shorter than the width Lx of the beam spot 30. Therefore, the beam spot 30 of a given shot partially overlaps with the beam spot 30 of the previous shot in the x direction. The ratio of the dimension of the overlapping portion in the x direction, i.e., Lx - Wx, to the width Lx of the beam spot 30 is called the overlap ratio in the scanning operation.

[0021] The movement distance of the beam spot 30 in the y direction in one step operation is denoted as Wy. The movement distance Wy is shorter than the length Ly of the beam spot 30. Therefore, the area scanned in one scanning operation partially overlaps in the y direction with the area scanned in the previous scanning operation. The ratio of the dimension of the overlapping portion in the y direction, i.e., Ly-Wy, to the length Ly of the beam spot 30 is called the overlap ratio in the step operation.

[0022] FIG. 3 is a schematic diagram illustrating a target area on the surface of a processing object 60 onto which a pulsed laser beam is incident. The processing object 60 is, for example, a circular semiconductor wafer, and has a notch 61 formed at one location on its outer periphery. An xyz Cartesian coordinate system is defined so that a line passing through the notch 61 and the center O of the processing object 60 is parallel to the y axis. A circular non-irradiation area 62A is defined on the periphery of the surface of the processing object 60. The outer periphery of the circular non-irradiation area 62A coincides with the edge of the processing object 60. The width of the circular non-irradiation area 62A is denoted as EC.

[0023] An irradiation-prohibited region 62B is defined on the notch 61 side of a line obtained by moving an imaginary line parallel to the x-direction passing through the tip of the notch 61 toward the center O of the processing object 60 by a length equal to the width EC. The union of the annular irradiation-prohibited region 62A and the irradiation-prohibited region 62B near the notch is referred to as irradiation-prohibited region 62. The region inside the irradiation-prohibited region 62 is referred to as irradiation-permitted region 63.

[0024] The annealing is performed under the condition that the pulsed laser beam is not incident on the irradiation prohibited region 62, but is incident on as wide an area as possible of the irradiation permitted region 63. Next, the reason for providing the irradiation prohibited region 62 will be explained.

[0025] Annealing is performed while the processing object 60 is held on the chuck mechanism 18 (FIG. 1). If the beam spot 30 extends beyond the processing object 60, the chuck mechanism 18 may be damaged by the laser energy. By providing the irradiation prohibition area 62, it becomes less likely that the beam spot 30 will extend beyond the processing object 60, and the chuck mechanism 18 will be less likely to be damaged. Furthermore, if the processing object 60 becomes thin, the peripheral portion of the processing object 60 will be more susceptible to damage. By providing the irradiation prohibition area 62, it becomes less likely that the peripheral portion of the processing object 60 will be damaged by laser irradiation.

[0026] 4 and 5, a description will be given of the procedure and trajectory of movement of the beam spot 30 within the irradiation allowable area 63. Fig. 4 is a schematic diagram showing the trajectory of movement of the beam spot 30, and Fig. 5 is a flowchart showing the procedure of moving the beam spot 30.

[0027] As shown in FIG. 4, in the scanning operation of the beam spot 30, the beam spot 30 is moved in the x direction from one end to the other end of the irradiation allowable region 63. For example, in odd-numbered scanning operations, the beam spot 30 is moved in the positive direction of the x axis, and in even-numbered scanning operations, the beam spot 30 is moved in the negative direction of the x axis. In the stepping operation, the beam spot 30 is moved in the negative direction of the y axis by a distance Wy (FIG. 2). The intersection of a line extending from the center O of the processing object 60 in the positive direction of the y axis and the outer periphery of the irradiation allowable region 63 is referred to as the end Ps on the irradiation start side, and the intersection of a line extending from the center O of the processing object 60 in the negative direction of the y axis and the outer periphery of the irradiation allowable region 63 is referred to as the end Pf on the irradiation end side.

[0028] First, a position offset by an offset width OFFs from the end Ps on the irradiation start side in the y direction toward the inside of the irradiation allowable region 63 is set as the scanning start position in the y direction (step SA1). More specifically, the distance in the y direction from the edge on the positive side of the y axis of the scanning region through which the beam spot 30 moves in the first scanning operation to the end Ps on the irradiation start side is equal to the offset width OFFs.

[0029] Once the position of the scanning region in the y direction is determined, the number of step operations to be performed when performing annealing on the irradiation allowable region 63 is calculated (step SA2). Specifically, if, after one scanning operation is completed, the beam spot 30 is moved by the movement distance Wy (FIG. 2) of the beam spot 30 during the step operation, and the beam spot 30 extends beyond the end Pf on the irradiation end side, no step operation is performed, and the step operation immediately before that is set as the final step operation.

[0030] The number of step operations can be calculated from the dimension of the irradiation allowable region 63 in the y direction, the moving distance Wy during the step operation, and the length Ly of the beam spot 30.

[0031] Next, the number of shots in the scanning operation is calculated from the x-direction dimension of the irradiation allowable area 63 at the current y-direction position of the beam spot 30 (step SA3). This number of shots is the maximum number of shots when scanning the irradiation allowable area 63 under the condition that the beam spot 30 does not go outside the irradiation allowable area 63. For example, this number of shots can be calculated from the shorter of the lengths of the portions of the beam spot 30 that are cut out by the outer periphery of the irradiation allowable area 63, the movement distance Wx of the beam spot in the x-direction (FIG. 2), and the width Lx of the beam spot 30, which are parallel to the x-axis at each of the positions of the positive and negative edges of the y-axis of the beam spot 30.

[0032] Once the number of shots in the scanning operation is determined, a scanning operation is performed in which the beam spot 30 is moved from one end to the other end in the x direction of the irradiation allowable area 63 (step SA4). The position of the beam spot 30 in the first shot of one scanning operation is set so that one corner of the beam spot 30 coincides with the position of the outer periphery of the irradiation allowable area 63. If the beam spot 30 is further moved by a movement distance Wx (FIG. 2) from the position of the beam spot 30 in the last shot of the determined number of shots, the beam spot 30 will extend outside the irradiation allowable area 63.

[0033] In one scanning operation, the pulsed laser beam is incident on a rectangular area (scanning area) that is long in the x direction. In the scanning area other than the areas near both ends in the x direction, the pulsed laser beam is incident a predetermined number of times according to the overlap rate. Near both ends of the scanning area in the x direction, there are areas where the number of shots is less than the predetermined number.

[0034] After the step operations are performed the number of times calculated in step SA2, the annealing process is terminated (step SA5). If the number of step operations is less than the calculated number, step operations are performed (step SA6), and the procedure from step SA3 to step SA5 is performed again.

[0035] An area where the pulse laser beam is not incident remains between the area scanned in the last scanning operation and the end Pf on the irradiation end side of the irradiation allowable area 63. The dimension of this area in the y direction is referred to as the remaining irradiation width OFFf.

[0036] When the final scanning operation is completed, the pulsed laser beam is incident on most of the area within the irradiation allowable area 63 a predetermined number of times according to the overlap rate of the scanning operation and the overlap rate of the stepping operation. Of the areas where the pulsed laser beam has been incident at least once, areas remain near both ends in the y direction where the pulsed laser beam has been incident for fewer than the predetermined number of shots.

[0037] Figure 4 shows a case where the overlap rate during both scanning and stepping is 50%. In this case, the majority of the area where the pulsed laser beam is incident is hit by a total of four shots of the pulsed laser beam. The area where four shots of the pulsed laser beam are incident is referred to as the effective irradiation area 64. The number of shots incident on the effective irradiation area 64 depends on the overlap rate of the scanning and stepping operations. For example, the number of overlapping shots is determined by the overlap rate of the scanning and stepping operations. When the overlap rate during both scanning and stepping is 50%, the number of overlapping shots is four. When the overlap rate during both scanning and stepping is 2 / 3, the number of overlapping shots is nine. The effective irradiation area 64 can be defined as the area where laser pulses are incident a number of times equal to the number of overlapping shots.

[0038] In Fig. 4, the effective irradiation area 64 is hatched. The edges of the effective irradiation area 64 have a stepped shape. Note that Fig. 4 shows only a portion near the end Ps on the irradiation start side and the end Pf on the irradiation end side, and does not specifically show the central portion. The effective irradiation area 64 is the area that can actually be used as a semiconductor element.

[0039] The distance from the effective irradiation area 64 to the end Ps on the irradiation start side is denoted as Ws, and the distance from the effective irradiation area 64 to the end Pf on the irradiation end side is denoted as Wf. To make the effective irradiation area 64 as wide as possible, it is preferable to make the sum of the distance Ws and the distance Wf (Ws+Wf) small. Furthermore, it is preferable to prevent the effective irradiation area 64 from being unevenly distributed within the irradiation allowable area 63. In other words, it is preferable to make the difference |Ws-Wf| between the distance Ws and the distance Wf small, and it is more preferable to make the two equal.

[0040] The difference between the distance Ws and the offset width OFFs, and the difference between the distance Wf and the offset OFFf, are determined by the length Ly of the beam spot 30 and the overlap rate of the stepping operation. The size and overlap rate of the beam spot 30 are determined by the irradiation recipe of the pulsed laser beam. Therefore, (OFFs-Ws) and (OFFf-Wf) are equal and are fixed values ​​determined by the irradiation recipe. Therefore, to reduce (Ws+Wf) and |Ws-Wf|, it is necessary to reduce the sum (OFFs+OFFf) of the offset width OFFs and the remaining irradiation width OFFf, and to reduce the difference between them, |OFFs-OFFf|.

[0041] If (OFFs+OFFf) is equal to or greater than the movement distance Wy (FIG. 2) of the beam spot 30 during step movement, the number of step movements can be increased by narrowing the offset width OFFs. If (OFFs+OFFf) is less than the movement distance Wy, the number of step movements cannot be increased. Therefore, in order to make (OFFs+OFFf) as small as possible, the offset width OFFs should be set so that (OFFs+OFFf) is less than the movement distance Wy.

[0042] Next, a method for determining the offset width OFFs to reduce |OFFs-OFFf| will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the procedure for determining the offset width OFFs.

[0043] First, the user operates the input / output device 22 of the laser processing support device 20 (FIG. 1) to input information specifying the y-direction dimension of the irradiation allowable region 63 (FIG. 3), the second-direction dimension Ly (FIG. 2) of the beam spot 30, and the overlap rate during step operation (step SB1). The processing device 21 acquires the information input to the input / output device 22 (step SB2).

[0044] Based on the acquired information, the processing device 21 determines the value of the offset width OFFs to reduce |OFFs-OFFf| (step SB3), and then outputs the determined value of the offset width OFFs to the input / output device 22 (step SB4).

[0045] The user checks the offset width OFFs output to the input / output device 22 and commands the offset width OFFs to the control device 40 of the laser processing device. The control device 40 controls the drive mechanism 17 and the laser oscillator 10 (FIG. 1) based on the offset width OFFs commanded by the user.

[0046] Next, the process of step SB3 will be described with reference to FIG. 7 shows the relationship between the y-direction dimension Ay of the irradiation allowable region 63 (FIG. 3), the y-direction dimension Ly of the beam spot 30 (FIG. 2), and the y-direction overlap ratio R OVL 10 is a schematic diagram showing the relationship between the number of scanning operations N and the number of scanning operations N.

[0047] The beam spot 30 moves in the y direction by the stepping motion. The movement distance Wy in the y direction in one stepping motion can be calculated by the following formula. Wy=Ly(1-R OVL )···(1)

[0048] 7, the numbers inside the beam spot 30 represent serial numbers assigned to the scanning operations in order. For example, the y-direction position of the beam spot 30 in the i-th scanning operation is shifted in the positive direction of the y-axis by a movement distance Wy from the y-direction position of the beam spot 30 in the (i-1)-th scanning operation. The y-direction position of the beam spot 30 in the N-th scanning process is shifted in the positive direction of the y-axis by Wy(N-1) from the position of the beam spot 30 in the first scanning process.

[0049] The dimension By in the y direction of the region where the pulse laser beam is incident at least once during N scanning operations is given by the following equation: By = Wy(N-1) + Ly (2) Since the sum of the offset width OFFs, the y-direction dimension By of the area where the pulse laser beam is incident at least once, and the remaining irradiation width OFFf is equal to the y-direction dimension Ay of the irradiation allowable area 63, the following equation holds: Wy(N-1)+Ly+OFFs+OFFf=Ay...(3)

[0050] Furthermore, if the sum of the offset width OFFs and the remaining irradiation width OFFf is equal to or greater than the movement distance Wy, the number of scanning operations can be increased by adjusting the offset width OFFs. If the sum of the offset width OFFs and the remaining irradiation width OFFf is less than the movement distance Wy, the number of scanning operations cannot be increased. In other words, when the number of scanning operations N is at its maximum, the following formula is satisfied. 0≦OFFs+OFFf <Wy···(4)

[0051] From equations (3) and (4), the following equation is derived: (Ay-Ly) / Wy <N≦(Ay-Ly) / Wy+1···(5) An integer N that satisfies equation (5) is used as the number of scanning operations. Once the number of scanning operations N is determined, the value of OFFs+OFFf is determined from equation (3). The offset width OFFs should be determined so as to satisfy the following equation. OFFs = (OFFs + OFFf) / 2 (6)

[0052] By determining the number of scanning operations N so as to satisfy equation (5), the size of the effective irradiation area 64 (FIG. 4) in the y direction can be maximized. By using the determined number of scanning operations N to determine the offset width OFFs so as to satisfy equations (3) and (6), the effective irradiation area 64 (FIG. 4) can be positioned approximately at the center of the irradiation allowable area 63 in the y direction.

[0053] Next, the excellent effects of the above embodiment will be described. In the above embodiment, the offset width OFFs is set so that the difference between the offset width OFFs and the remaining irradiation width OFFf (FIG. 4) is small. This makes it possible to suppress bias in the effective irradiation area 64 within the irradiation allowance area 63. To obtain a sufficient effect, it is preferable to determine the offset width OFFs so that |OFFs-OFFf| is 20% or less of (OFFs+OFFf). Furthermore, it is more preferable to set the offset width OFFs so that the offset width OFFs and the remaining irradiation width OFFf are equal.

[0054] Furthermore, it is possible to widen the effective irradiation area 64, thereby improving the utilization efficiency of the processing object 60 such as a semiconductor wafer.

[0055] Next, we will explain the effect of the stepped edge shape of the effective irradiation area 64 (Fig. 4). In order to widen the effective irradiation area 64, it is preferable to shorten the distance Wa (Fig. 4) from the apex of the stepped edge that faces inward of the effective irradiation area 64 to the outer periphery of the irradiation allowance area 63. The offset width OFFs was changed to determine the effective irradiation area 64, and the distance Wa at that time was calculated. As a result, it was found that the distance Wa hardly changed even when the offset width OFFs was changed. Therefore, there is no need to consider changes in the distance Wa when determining the optimal value of the offset width OFFs.

[0056] Next, a modification of the above embodiment will be described. In the above embodiment, the path of the pulsed laser beam is kept stationary and the processing object 60 is moved in the x and y directions, but the processing object 60 may be kept stationary and the pulsed laser beam may be scanned in the x and y directions. Alternatively, the pulsed laser beam may be scanned in the x direction and the processing object 60 may be moved in the y direction.

[0057] In the above embodiment, during the scanning operation, the beam spot 30 is moved in a direction perpendicular to the line passing through the notch 61 and the center O of the processing object 60, but the relationship between the line passing through the notch 61 and the center O of the processing object 60 and the scanning direction may be changed. For example, the scanning direction may be parallel to or oblique to the line passing through the notch 61 and the center O of the processing object 60.

[0058] In the above embodiment, the shape of the processing object 60 is circular, but it is also possible to laser process objects of other shapes. For example, the above embodiment may be applied to laser processing for crystallizing an amorphous silicon film formed on a square or rectangular glass substrate.

[0059] Next, another modification of the above embodiment will be described. In this modified example, the offset width OFFs is determined so that the area of ​​the effective irradiation region 64 (FIG. 4) is maximized. The offset width OFFs can be determined based on the y-direction dimension Ly of the beam spot 30, the y-direction movement distance Wy of the beam spot 30 during stepping, and the y-direction dimension of the irradiation allowable region 63. During scanning operations, the incidence position in the x-direction is determined so that the number of shots in each scanning operation is maximized. It is not necessary to determine the offset width OFFs so that the area is maximized; it is advisable to determine the offset width OFFs so that it is larger than the target area.

[0060] Next, a laser processing support device and a laser processing method according to another embodiment will be described with reference to Figures 8A and 8B. Below, a description of the configuration common to the embodiment described with reference to Figures 1 to 7 will be omitted.

[0061] FIG. 8A is a schematic diagram showing a scanning area 65 onto which a pulsed laser beam is incident in one scanning operation when the method according to the embodiment described with reference to FIGS. 1 to 7 is applied. At the start of scanning, one vertex of the beam spot 30 is located on the outer periphery of the irradiation allowable area 63. From this position, the beam spot 30 is moved in the x direction at a predetermined overlap rate. The shortest distance in the x direction from the end of the scanning area 65 on the ending side to the outer periphery of the irradiation allowable area 63 is referred to as the remaining irradiation width OFFfx. Normally, the remaining irradiation width OFFfx is not zero. For this reason, the scanning area 65 is biased toward the scanning start side within the irradiation allowable area 63.

[0062] 8B is a schematic diagram showing a scan area 65 onto which a pulsed laser beam is incident in one scan operation when a scan operation is performed using the method of this embodiment. In this embodiment, one vertex of the beam spot 30 at the start of scanning is offset in the x direction by an offset width OFFsx from the outer periphery of the irradiation allowable area 63. The offset width OFFsx is set to be equal to the remaining irradiation width OFFfx.

[0063] Next, the excellent effects of the embodiment shown in FIG. 8B will be described. In this embodiment, not only the deviation in the y direction of the effective irradiation area 64 (FIG. 4) within the irradiation allowance area 63 but also the deviation in the x direction can be reduced.

[0064] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible. [Explanation of symbols]

[0065] 10 Laser oscillator 11 Beam Expander 12 Beam shaping optical elements 13 Folding mirror 17 Moving mechanism 18 Chuck mechanism 20 Laser processing support device 21 Processing equipment 22 Input / Output Devices 30 beam spots 40 Control device 60 Processing Objects 61 notches 62 Irradiation prohibited area 62A Circular No-Irradiation Area 62B No-irradiation area near the notch 63 Irradiation tolerance area 64 Effective irradiation area 65 Scanning Area

Claims

1. 1. A laser processing support device that supports laser processing, comprising: a pulsed laser beam being incident on a surface of a processing object; and alternately repeating a scanning operation of scanning the surface of the processing object with the pulsed laser beam in a first direction and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction perpendicular to the first direction, under a condition that the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object; based on the dimension of the beam spot in the second direction, the moving distance of the beam spot in the second direction during the step operation, and the dimension of an irradiation allowable area inside the irradiation prohibited area in the second direction, A laser processing support device that determines an offset width, which is the distance in the second direction from an end of the irradiation allowance area in the second direction to a scanned area of ​​the irradiation allowance area by the first scanning operation.

2. 1. A laser processing support device that supports laser processing, comprising: a pulsed laser beam being incident on a surface of a processing object; and alternately repeating a scanning operation of scanning the surface of the processing object with the pulsed laser beam in a first direction and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction perpendicular to the first direction, under a condition that the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object; an input / output device; Processing equipment Equipped with The processing device includes: acquiring, from the input / output device, information specifying a dimension in the second direction of an irradiation allowable region on the surface of the processing object that is inside the irradiation prohibition region, a dimension in the second direction of the beam spot, and an overlap rate of the beam spot during the step operation; A laser processing support device that determines the offset width so that the difference between an offset width, which is the distance in the second direction from the end of the irradiation allowable area to the scanned area of ​​the irradiation allowable area by the first scanning operation, and a remaining irradiation width, which is the distance from the scanned area by the last scanning operation to the end of the irradiation allowable area in the second direction, is 20% or less of the sum of the offset width and the remaining irradiation width, and outputs information specifying the offset width to the input / output device.

3. The laser processing support device according to claim 2 , wherein the processing device determines the offset width so that the offset width is equal to the remaining irradiation width.

4. the processing object is a circular wafer having a notch formed therein, and the second direction is parallel to a line passing through a center of the wafer and the notch; 4. The laser processing support device according to claim 2, wherein the prohibited irradiation area is defined by a union of an annular area having an outer periphery that coincides with the edge of the wafer and an area on the notch side of a line obtained by moving a virtual line that passes through the tip of the notch and is parallel to the first direction toward the center of the wafer by a length equal to the width of the annular area.

5. A laser processing method comprising: a scanning operation of scanning the surface of a processing object with the pulsed laser beam in a first direction under a condition that the pulsed laser beam is not incident on an irradiation prohibited area defined on a periphery of the processing object; and a stepping operation of moving a beam spot of the pulsed laser beam in a second direction orthogonal to the first direction, the method comprising: The scanning operation is started from a position offset inward by an offset width from one end of the irradiation allowable area that is inside the irradiation prohibition area in the second direction, When the stepping operation causes the beam spot to extend beyond an end of the irradiation allowable area in the second direction, the scanning operation is terminated; A laser processing method in which the offset width is set so that the difference between the remaining irradiation width, which is the distance from the scanning area by the scanning operation after the last step operation to the other end of the irradiation allowance area in the second direction, and the offset width is 20% or less of the sum of the offset width and the remaining irradiation width.

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