Laser processing apparatus and laser processing method

Abstract

To avoid the appearance of a sharp seam between adjacent areas in performing laser processing in which a line beam scans a plurality of strip-like areas on a workpiece.SOLUTION: In a laser processing apparatus that performs scanning by moving a line beam B expanded along the Y-axis direction relative to a workpiece W along the X-axis direction intersecting the Y-axis, and irradiates strip-shaped regions P1, P2, and P3 on the workpiece W with a laser beam B, after irradiating certain strip-shaped regions P1 and P3 on the workpiece W, when irradiating another strip-shaped region P2 adjacent thereto, by rotating the workpiece W by 180° relative to the line beam B around the Z-axis that intersects the X-axis and the Y-axis, the line beam B scans the other band-shaped area P2, such that the same edge of the line beam B hits both the boundary between the former regions P1 and P3 and the latter region P2, and the boundary between the latter region P2 and the former regions P1 and P3.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a laser processing apparatus and method for performing scanning by moving a line beam relatively to a workpiece and irradiating a strip-shaped area on the workpiece. [Background technology]

[0002] Specific examples of processes in which a wide area of ​​a workpiece is irradiated with laser light include LLO (Laser Lift Off), which peels off a device film formed on a substrate from the substrate, annealing, which removes residual stress by heating, cleaning, etc. LLO is used in the manufacturing process of OEL (Organic Electro-Luminescence) or OLED (Organic Light-Emitting Diode), which are becoming more widespread recently.

[0003] In performing such laser processing, it is common to generate a line beam by expanding the laser light in a predetermined Y-axis direction, and then perform scanning by moving the line beam relative to the workpiece along the X-axis direction (see, for example, the following patent document). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-012886 Summary of the Invention [Problem to be solved by the invention]

[0005] The length of the line beam along the Y-axis is finite. If the line length is small compared to the overall width of the workpiece, the laser can only be applied to a limited portion of the workpiece in one scan, that is, a strip-shaped area whose width in the Y-axis direction is approximately the same as the line length. In order to apply the laser evenly over a wide area of ​​the workpiece, it is necessary to repeat the procedure of shifting the line beam in the Y-axis direction while scanning in the X-axis direction each time.

[0006] Ideally, the profile of a line beam would have uniform light intensity from one end to the other along the Y-axis direction. However, in reality, as shown in the example of Figure 9, the light intensity is not completely uniform, and it is not rare for the light intensity on one end side L to be asymmetric with the light intensity on the other end side R.

[0007] When performing a process of irradiating a wide area of ​​a workpiece with a laser, a strip area on the workpiece is scanned with a line beam, and then another adjacent strip area is scanned with the line beam. At this time, one end of the line beam hits the boundary of the former area that abuts on the latter area, and the other end of the line beam hits the boundary of the latter area that abuts on the former area.

[0008] As a result, a difference occurs between the processing or machining state of the former boundary portion and the processing or machining state of the latter boundary portion, and a boundary line or seam J that is visible to the naked eye may appear as shown in Fig. 10. This raises concerns that it may call into question the performance of the laser processing device, even though there is no problem with the accuracy or quality of the processing or machining.

[0009] The present invention, which was developed with the above-mentioned problems in mind, aims to avoid the appearance of clear seams between adjacent areas when performing laser processing in which a line beam is used to scan multiple band-shaped areas on a workpiece. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention provides a laser processing device that performs scanning by moving a line beam, which is a laser beam expanded along a Y-axis direction, along an X-axis direction intersecting the Y-axis relative to a workpiece, and irradiates the laser beam onto a band-shaped region on the workpiece, the laser processing device comprising: The present invention includes a stage that supports the workpiece and transports it along the X-axis direction, and a rotation mechanism that rotates the workpiece supported by the stage about the Z-axis, and by transporting the workpiece along the X-axis direction of the stage, first scanning with the line beam a first band region and a third band region that are not adjacent to each other and sandwich another second band region therebetween among a first band region, a second band region, and a third band region that are aligned in the Y-axis direction on the workpiece, the first band region and the third band region being sandwiched between the first band region and the third band region, the first band region and the third band region being sandwiched between the first band region and the third band region, the rotation mechanism flips the orientation of the workpiece by 180° about the Z-axis that intersects the X-axis and Y-axis relative to the line beam, and in this state, by transporting the workpiece along the X-axis direction of the stage, the second band region sandwiched between the first band region and the third band region is scanned with the line beam. A laser processing system was constructed that allowed the line beams to strike the same ends.

[0011] The laser processing apparatus is used, for example, to perform a process of peeling off a film or layer from a substrate by irradiating a processing object having a film or layer provided on the substrate with the line beam.

[0013] The optical system for generating the line beam to be irradiated onto the workpiece includes, for example, a lens for expanding the laser light supplied from the laser light source and adjusting the line length along the Y-axis direction, a lens for adjusting the beam width of the laser light along the X-axis direction, a lens for homogenizing the light intensity of the laser light along the Y-axis direction, and a focusing lens for reducing the beam width of the laser light along the X-axis direction.

[0014] A laser processing method according to the present invention is a laser processing method for performing scanning by moving a line beam, which is a laser beam expanded along a Y-axis direction, along an X-axis direction intersecting the Y-axis relative to a workpiece, and irradiating the laser beam onto a band-shaped region on the workpiece, comprising: The workpiece and the line beam are moved relatively in the X-axis direction, and the first and third band-shaped regions, which are not adjacent to each other and sandwich another second band-shaped region therebetween, are first scanned with the line beam and laser-treated, among a first band-shaped region, a second band-shaped region, and a third band-shaped region aligned in the Y-axis direction on the workpiece, and the orientation of the workpiece is inverted by 180° around a Z-axis intersecting the X-axis and Y-axis relative to the line beam, and the workpiece and the line beam are moved relatively in the X-axis direction, and the untreated second band-shaped region sandwiched between the first band-shaped region and the third band-shaped region is scanned with the line beam and laser-treated, so that the end of the line beam on the same side hits both the boundary between the first band-shaped region and the second band-shaped region and the boundary between the second band-shaped region and the third band-shaped region. It is characterized by: Effect of the Invention

[0015] According to the present invention, when performing laser processing in which a plurality of band-shaped regions on a processing object are scanned with a line beam, it is possible to effectively prevent the appearance of clear seams between adjacent regions. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view showing an overall outline of a laser processing apparatus according to an embodiment of the present invention; [Diagram 2]FIG. 2 is a diagram illustrating a schematic configuration of an optical system that generates a line beam in the laser processing device of the embodiment. [Diagram 3] FIG. 2 is a cross-sectional view illustrating a workpiece to be laser-processed by the laser processing apparatus according to the embodiment. [Figure 4] 3A to 3C are diagrams illustrating a laser processing performed by the laser processing apparatus of the embodiment. [Diagram 5] 3A to 3C are diagrams illustrating a laser processing performed by the laser processing apparatus of the embodiment. [Figure 6] 3A to 3C are diagrams illustrating a laser processing performed by the laser processing apparatus of the embodiment. [Figure 7] 3A to 3C are diagrams illustrating a laser processing performed by the laser processing apparatus of the embodiment. [Figure 8] 3A to 3C are diagrams illustrating a laser processing performed by the laser processing apparatus of the embodiment. [Figure 9] FIG. 2 is a diagram showing a beam profile of a line beam generated by the laser processing apparatus of the embodiment. [Figure 10] 1A and 1B are diagrams for explaining a laser processing pattern by a conventional laser processing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the present invention will be described with reference to the drawings. The laser processing device of this embodiment generates a line beam B by expanding the laser light in the Y-axis direction, and performs scanning by moving the line beam B relative to the workpiece W along the X-axis direction perpendicular to the Y-axis, thereby irradiating the laser light B over a wide range of the workpiece W. As shown in Fig. 1, the laser processing device of this embodiment includes a support 1 for supporting the workpiece W, a stage 2 for supporting and transporting the support 1, a rotation mechanism 3 interposed between the support 1 and the stage 2, and an irradiation unit 4 for irradiating the line beam B toward the workpiece W supported by the support 1.

[0018] The stage 2 is, for example, a known XYZ stage. The XYZ stage 2 can move the support 1 supporting the workpiece W in three-dimensional directions, including the X-axis direction which is the short axis of the line beam B, the Y-axis direction which is the long axis of the line beam B, and the Z-axis direction which is perpendicular to the X-axis and Y-axis. The optical axis A of the line beam B, in other words, the direction of the laser light emitted from the nozzle 47 of the irradiation unit 4 toward the workpiece W, may be parallel to the Z-axis or may be inclined with respect to the Z-axis, but always intersects with the XY plane at a constant angle.

[0019] The rotation mechanism 3 enables the support 1 to rotate around a rotation axis parallel to the Z axis relative to the stage 2. The rotation mechanism 3 can be configured using, for example, an NC (Numerical Control) circular table, a rotary actuator, a DD (Direct Drive) motor, etc. However, the rotation mechanism 3 may also be a mechanism that supports the support 1 on an axis so that it can be rotated manually relative to the stage 2.

[0020] 2 shows the configuration of the optical system included in the irradiation unit 4. This optical system has a Y-axis beam expander 42 for expanding the laser light supplied from an oscillator 41 serving as a laser light source in the Y-axis direction, an X-axis beam expander 43 for expanding the laser light that has passed through the Y-axis beam expander 42 in the X-axis direction, an array lens 44 and an illumination lens 45 for homogenizing the light intensity along the Y-axis direction of the laser light that has passed through the X-axis beam expander 43, and a condenser lens 46 for condensing the laser light that has passed through the array lens 44 and the illumination lens 45.

[0021] The Y-axis beam expander 42 is made of one or more cylindrical lenses and serves to adjust the line length along the Y-axis direction of the line beam B emitted from the nozzle 47 of the irradiation unit 4. The X-axis beam expander 43 is also made of one or more cylindrical lenses and serves to adjust the beam width along the X-axis direction of the line beam B emitted from the nozzle 47 of the irradiation unit 4. Note that, as elements of the beam expanders 42 and 43, rod lenses, rod integrators, fly-eye lenses, Powell lenses, etc. can be used instead of or together with the cylindrical lenses. The array lens 44 is an accumulation of many small cylindrical lenses.

[0022] The condenser lens 46 is made up of one or more toroidal lenses (toric lenses), and reduces the beam width along the X-axis direction of the line beam B emitted from the nozzle 47 of the irradiation unit 4. In the illustrated example, the first condenser lens 461 located on the upstream side closer to the illumination lens 45 is displaceable along the optical path along which the laser light propagates, thereby making it possible to variably adjust the NA (Numerical Aperture) of the condenser lens 46.

[0023] The laser processing apparatus of this embodiment is used for performing LLO processing, in which a laser B is irradiated onto a processing object W on which a device film W2 is formed on a substrate W1, and the device film W2 is peeled off from the substrate W1. LLO is performed in the manufacturing process of OEL or OLED displays, which are becoming more and more popular. FIG. 3 shows the structure of the processing object W to be processed. The substrate W1 is, for example, a glass substrate or a sapphire substrate, and has a thickness of about several mm. The device film W2 is, for example, a polyimide film W21 on the substrate W1 on which elements W22 such as thin film transistors or LEDs are arranged. The thickness of the polyimide film W21 is several tens of μm to several hundreds of μm.

[0024] When a laser (particularly an ultraviolet laser) B is irradiated from the substrate W1 side of the workpiece W, the laser that passes through the substrate W1 is absorbed by the surface of the polyimide film W21 that is in close contact with the substrate W1, and the bonds between molecules or atoms in the polyimide film W21 are broken. As a result, the surface of the polyimide film W21 is removed through decomposition, vaporization, or transpiration, and the device film W2 can be peeled off cleanly from the substrate W1. This LLO method does not cause thermal damage to the device film W2.

[0025] In the LLO process, scanning is performed by moving the line beam B expanded in the Y-axis direction in the X-axis direction relative to the workpiece W. In this embodiment, the line beam B is irradiated from the nozzle 47 of the irradiation unit 4 toward the workpiece W while driving the stage 2 to move the support 1 supporting the workpiece W in the X-axis direction.

[0026] The length of the line beam B along the Y-axis direction is finite. If the line length is smaller than the overall width of the workpiece W, the laser B can be irradiated with only a limited portion of the workpiece W in one scan, that is, only one belt-like region P1, P2, P3 whose width in the Y-axis direction is approximately the same as the line length and which extends in the X-axis direction. In order to irradiate the laser B evenly over a wide range of the workpiece W, after scanning the regions P1, P2, P3 directly below the nozzle 47, the stage 2 is driven to displace the support 1 in the Y-axis direction, thereby shifting the position on the workpiece W where the line beam B is irradiated along the Y-axis direction, and then another scan is performed on the other regions P1, P2, P3, which is repeated.

[0027] Ideally, the profile of the line beam B irradiated onto the workpiece W has a uniform light intensity from one end to the other end along the Y-axis direction. However, in reality, as shown in Fig. 9, the light intensity is not completely uniform, and the intensity is unequal on one end side L and the other end side R of the line beam B, or the change in intensity (gradient) along the Y-axis direction at one end side L of the line beam B is asymmetric with that at the other end side R.

[0028] The difference in light intensity between one end L and the other end R of the line beam B is due to the mode and individual differences of the laser oscillator 41 itself, but is also thought to be due to the large number of optical components, represented by lenses 42, 43, 44, 45, and 46, which make up the optical system, and to variations in their precision and misalignment of the optical axis.

[0029] If a number of strip-shaped regions P1, P2, and P3 on the workpiece W are simply scanned with the line beam B, one end side L of the line beam B will always strike one side edge of each of the strip-shaped regions P1, P2, and P3, and the other end side R of the line beam B will always strike the other side edge. As a result, due to the difference in light intensity between the one end side L and the other end side R of the line beam B, a step will occur in the processing or machining state of the boundary portion where two adjacent strip-shaped regions P1, P2, and P3 contact each other, and as shown in Figure 10, a boundary line or seam J visible to the naked eye may appear between the two adjacent strip-shaped regions P1, P2, and P3.

[0030] To avoid this phenomenon, in the laser processing by the laser processing device of this embodiment, as shown in Fig. 4, of multiple strip-shaped regions P1, P2, and P3 aligned in the Y-axis direction on the workpiece W, the strip-shaped regions P1 and P3 that are not adjacent to each other and have another strip-shaped region P2 sandwiched between them are first scanned with the line beam B. In other words, every other strip-shaped region P1, P2, and P3 aligned in the Y-axis direction is laser-processed. The orientation of the workpiece W when these strip-shaped regions P1 and P3 are laser-processed is kept constant, i.e., the workpiece W is not flipped 180° around the Z-axis.

[0031] 5, the support 1 is rotated by the rotation mechanism 3 to invert the orientation of the workpiece W supported by it by 180° around the Z axis. In this state, the strip area P2 that has not yet been laser-processed, that is, the strip area P2 sandwiched between the strip areas P1 and P3 that have already been laser-processed, is scanned with the line beam B and laser-processed.

[0032] According to the above procedure, the boundary between two adjacent strip regions P1, P2, and P3 is irradiated with the end of the line beam B on the same side. In accordance with the example shown in FIG. 5, the end L of one end of the line beam B hits the right side edge of the strip regions P1 and P3 in the figure and the left side edge of the adjacent strip region P2 in the figure. Also, the end R of the other end of the line beam B hits the left side edge of the strip regions P1, P2, and P3 in the figure and the right side edge of the adjacent strip region P2 in the figure. Therefore, no step is generated in the processing or machining state of the boundary between the two adjacent strip regions P1, P2, and P3, and no boundary line or seam J visible to the naked eye appears between the two adjacent strip regions P1, P2, and P3.

[0033] Alternatively, as shown in Fig. 6, one strip-shaped region P1 on the workpiece W is scanned with the line beam B. Next, as shown in Fig. 7, the orientation of the workpiece W is flipped 180° around the Z axis, and in this state, a strip-shaped region P2 adjacent to the most recently processed strip-shaped region P1 is scanned with the line beam B. Furthermore, as shown in Fig. 8, the orientation of the workpiece W is flipped 180° around the Z axis to return it to its original orientation, and in this state, a strip-shaped region P3 adjacent to the most recently processed strip-shaped region P2 is scanned with the line beam B. In this manner, the strip-shaped regions P1, P2, and P3 are sequentially laser-processed one by one while rotating the workpiece W 180° each time, thereby obtaining similar processing results.

[0034] When scanning the strip regions P1, P2, and P3 sequentially with the line beam B, the line beam B irradiated onto the strip regions P1 and P3 is positioned in the Y-axis direction (the workpiece W is positioned in the Y-axis direction relative to the nozzle 47), and the line beam B irradiated onto the strip region P2 adjacent to the strip regions P1 and P2 is positioned in the Y-axis direction. This is intended to realize fine adjustments to match the energy intensity of the laser beam B irradiated onto the boundary between the adjacent regions P1, P2, and P3.

[0035] In this embodiment, a laser processing device is configured to perform scanning by moving a line beam B, which is an extension of laser light along the Y-axis direction, along the X-axis direction intersecting the Y-axis relative to the workpiece W, and irradiate the laser light B onto strip-shaped regions P1, P2, and P3 on the workpiece W. When irradiating one strip-shaped region P1, P3 on the workpiece W and then irradiating another adjacent strip-shaped region P2, the workpiece W is rotated 180 degrees around the Z-axis intersecting the X-axis and Y-axis relative to the line beam B, and the other strip-shaped region P2 is scanned with the line beam B, so that the end of the line beam B on the same side hits both the boundary portion of the former regions P1, P3 that abuts the latter region P2, and the boundary portion of the latter region P2 that abuts the former regions P1, P3. According to this embodiment, when performing laser processing in which multiple strip-shaped regions P1, P2, and P3 on the workpiece W are scanned with a line beam B, the appearance of clear seams J between adjacent regions P1, P2, and P3 can be effectively avoided.

[0036] The present invention is not limited to the embodiment described above. For example, in the above embodiment, the stage 2 moves the support 1 and the workpiece W to scan the strip areas P1, P2, and P3 with the line beam B emitted from the nozzle 47. However, it is also possible to adopt a mode in which the nozzle 47 itself is drivable (particularly along the X-axis direction) and the nozzle 47 is moved to scan the strip areas P1, P2, and P3 with the line beam B.

[0037] In addition, instead of rotating the support 1 and the workpiece W 180° around the Z axis, it is also possible to rotate the nozzle 47 itself 180° around the Z axis to sequentially scan multiple strip regions P1, P2, and P3.

[0038] The application of the laser processing apparatus according to the present invention is not limited to the LLO process, and the laser processing apparatus according to the present invention can also be used for processes such as annealing and cleaning.

[0039] In addition, the specific configuration of each part and the processing procedure can be modified in various ways without departing from the spirit of the present invention. [Industrial Applicability]

[0040] The present invention can be applied to a laser processing apparatus and method for irradiating a workpiece with laser light to perform a desired process. [Explanation of symbols]

[0041] 2. Stage 3. Rotation mechanism 4...Optical system (illumination unit) 42...Lens for adjusting the line length along the Y axis (Y axis beam expander) 43...Lens for adjusting the beam width along the X-axis (X-axis beam expander) 44, 45...Lens for uniformizing the light intensity along the Y-axis direction (array lens, illumination lens) 46…Condenser lens for reducing the beam width along the X-axis B…Line beam P1, P2, P3...band-shaped areas on the workpiece W: Processing object W1...Substrate W2: Device membrane

Claims

1. A laser processing device that performs scanning by moving a line beam, which is a laser beam expanded along a Y-axis direction, along an X-axis direction intersecting the Y-axis relative to a workpiece, and irradiates a band-shaped region on the workpiece with the laser beam, a stage that supports the workpiece and transports it along an X-axis direction, and a rotation mechanism that rotates the workpiece supported by the stage around a Z-axis; by moving the workpiece along the X-axis direction of the stage, first scanning with the line beam the first stripe region and the third stripe region that are not adjacent to each other and sandwich another second stripe region therebetween, among a first stripe region, a second stripe region, and a third stripe region that are aligned in the Y-axis direction on the workpiece; the rotation mechanism rotates the workpiece by 180° around a Z-axis intersecting the X-axis and the Y-axis relative to the line beam, and in this state, the stage moves the workpiece along the X-axis direction to scan the second strip region sandwiched between the first strip region and the third strip region with the line beam; A laser processing device that causes the end of the line beam on the same side to hit both the boundary between the first stripe region and the second stripe region and the boundary between the second stripe region and the third stripe region.

2. The workpiece is a substrate having a film or layer thereon, 2. The laser processing apparatus according to claim 1, wherein a process of peeling off a film or layer from a substrate is carried out by irradiating the workpiece with the line beam.

3. An optical system for generating a line beam to be irradiated onto the workpiece, a lens for expanding the laser light provided from the laser light source and adjusting the line length along the Y-axis direction; a lens for adjusting a beam width of the laser light along an X-axis direction; a lens for uniformizing the light intensity of the laser light along the Y-axis direction; 3. The laser processing apparatus according to claim 1, further comprising a condenser lens for reducing the beam width of the laser light along the X-axis direction.

4. A laser processing method in which a line beam formed by expanding laser light along a Y-axis direction is moved along an X-axis direction intersecting the Y-axis relative to a workpiece to scan the workpiece, and the laser light is irradiated onto a strip-shaped region on the workpiece, comprising: the workpiece and the line beam are moved relative to each other in the X-axis direction, and a first stripe region and a third stripe region that are not adjacent to each other and have another second stripe region therebetween are first scanned with the line beam and laser-processed among a first stripe region, a second stripe region, and a third stripe region that are aligned in the Y-axis direction on the workpiece; a direction of the workpiece is inverted by 180° around a Z-axis intersecting the X-axis and Y-axis relative to the line beam, and the workpiece and the line beam are moved relatively in the X-axis direction, and the unprocessed second strip area sandwiched between the first strip area and the third strip area is scanned with the line beam to perform laser processing; A laser processing method in which the end of the line beam on the same side hits both the boundary between the first band region and the second band region and the boundary between the second band region and the third band region.

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