Laser irradiation device

Abstract

To propose a laser irradiation technique capable of achieving improvement in processing accuracy and acceleration in a processing speed.SOLUTION: In a laser irradiation device, a stage has a plurality of workpieces or a workpiece including a plurality of processing object portions placed thereon and is movable in a uniaxial or biaxial coordinate system; a scanner includes a condenser lens which converges laser light and can scan the laser light converged by the condenser lens; and a distance measuring sensor measures a distance from the scanner to the workpiece or the processing object portion. In a control unit, a conveyance processing unit moves one of the plurality of workpieces or one of the plurality of processing object portions into a scan region of the scanner by moving the stage; a measurement processing unit measures a distance to the workpiece or processing object portion in the scan region with the distance measuring sensor after the movement of the stage by the conveyance processing unit, and then a focus position adjustment processing unit adjusts a focus position of the condenser lens on the basis of the distance measured by the distance measuring sensor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laser irradiation technique for performing laser processing such as peeling, drilling, cutting, and machining on a workpiece.

Background Art

[0002] As a laser irradiation technique for performing laser processing such as peeling, drilling, cutting, and machining, for example, Patent Document 1 discloses a technique in which laser light oscillated by a laser oscillator is adjusted by an optical module such as an attenuator or an expander and then irradiated onto a workpiece through a condenser lens.

[0003] In order to improve the processing accuracy in such a laser irradiation technique, it is important to accurately focus the laser light at the irradiation target position. If this cannot be achieved, the desired energy or spot diameter cannot be obtained at the irradiation target position, and the processing accuracy may decrease. Particularly in microfabrication where high processing accuracy is required, the deviation between the irradiation target position and the focal position greatly affects the processing accuracy.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Under the above-described background, the present inventors have proposed enabling the laser light to be scanned using an fθ lens in order to bring the processing speed to a practical level in microfabrication using laser light.

[0006] However, when scanning a laser beam using an fθ lens, the further away from the center of the scanning area (where it intersects the optical axis of the fθ lens), the greater the discrepancy between the irradiation target position and the focus position. This discrepancy becomes more pronounced as the scanning area increases, leading to a significant decrease in processing accuracy.

[0007] Therefore, the objective of the present invention is to propose a laser irradiation technology that can achieve both improved processing accuracy and high processing speed. [Means for solving the problem]

[0008] The laser irradiation apparatus according to the present invention comprises a laser oscillator that outputs laser light, a stage, a scanner, a distance sensor, and a control unit. The stage is on which a workpiece containing multiple workpieces or multiple parts to be processed is placed, and is movable within a one-axis or two-axis coordinate system. The scanner has a focusing lens that focuses the laser light and is capable of scanning the laser light focused by the focusing lens. The distance sensor measures the distance from the scanner to one of the multiple workpieces or one of the multiple parts to be processed. The control unit includes a transport processing unit, a measurement processing unit, and a focus position adjustment processing unit. The transport processing unit moves the stage to move one of the multiple workpieces or one of the multiple parts to be processed into the scanning area of ​​the scanner. After the stage is moved by the transport processing unit, the measurement processing unit measures the distance to the workpiece or part to be processed within the scanning area using the distance sensor. The focus position adjustment processing unit adjusts the focal position of the focusing lens based on the distance measured by the distance sensor.

[0009] With the above-described laser irradiation device, by moving the stage, one of several workpieces or one of several parts to be processed can be moved into the scanning area of ​​the scanner, and then laser beam irradiation and scanning (laser processing) can be performed on the workpiece or part to be processed within that scanning area. Furthermore, after the completion of the laser processing, by moving the stage again, another workpiece or another part to be processed can be moved into the scanning area of ​​the scanner, and then laser beam irradiation and scanning (laser processing) can be performed on the workpiece or part to be processed within that scanning area. By performing such laser processing by sequentially moving the stage, laser processing can be performed on all of the multiple workpieces or parts to be processed on the stage.

[0010] Therefore, with the above-described laser irradiation device, the scanning area can be reduced compared to when laser beam irradiation and scanning (laser processing) are performed on multiple workpieces or multiple processing targets simultaneously. As a result, the discrepancy between the irradiation target position and the laser beam focus position within the scanning area is reduced, and high processing accuracy is achieved throughout the entire scanning area. Furthermore, with the above-described laser irradiation device, each time the stage is moved to bring a new workpiece or processing target into the scanning area, the distance from the scanner to the workpiece or processing target is measured, and the focal position of the focusing lens is adjusted based on that distance. Therefore, laser processing can be performed with high accuracy on any workpiece or processing target.

[0011] Furthermore, with the above-mentioned laser irradiation device, as described above, the stage can be moved sequentially to perform laser processing, allowing for high-speed processing of workpieces or target areas one after another while maintaining a high processing configuration. [Effects of the Invention]

[0012] According to the present invention, it is possible to achieve both improved machining accuracy and increased machining speed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a conceptual diagram showing a laser irradiation device according to an embodiment. [Figure 2] This is a conceptual diagram showing a modified laser irradiation device. [Modes for carrying out the invention]

[0014] [1] Embodiment Figure 1 is a conceptual diagram showing a laser irradiation device according to an embodiment. As shown in this figure, the laser irradiation device comprises a laser oscillator 1, a stage 2, a laser characteristic adjustment unit 3, a scanner 4, a distance measuring sensor 5, and a control unit 6. This laser irradiation device is used for laser processing of workpieces such as peeling, drilling, cutting, and machining. The configuration of each part will be described in detail below.

[0015] <Laser oscillator> Laser oscillator 1 is an oscillator that outputs laser light. For example, laser oscillator 1 outputs laser light with a wavelength of 190 nm to 360 nm in pulse form at an oscillation frequency of 1 Hz to 300 kHz. However, laser oscillator 1 is not limited to outputting laser light at these wavelengths and oscillation frequencies, and can be changed as appropriate.

[0016] <Stage> Stage 2 is movable within a one-axis or two-axis coordinate system (for example, a one-axis or two-axis coordinate system set in the horizontal plane), and a drive mechanism (not shown) for moving Stage 2 within the coordinate system is connected to Stage 2. In this embodiment, multiple workpieces or workpieces containing multiple parts to be machined are placed on Stage 2.

[0017] <Laser Characteristics Adjustment Section> The laser characteristic adjustment unit 3 includes an attenuator 31, an expander 32, a spot shape adjustment module 33, and a spot diameter adjustment module 34.

[0018] The attenuator 31 is an optical module that stabilizes the intensity of the laser light output from the laser oscillator 1. Specifically, even when there is variation in the intensity of the laser light (the output of the laser oscillator 1), the attenuator 31 stabilizes the laser light by attenuating and equalizing the intensity of the laser light to a predetermined value.

[0019] The expander 32 is an optical module that expands the beam diameter of the laser light stabilized by the attenuator 31. In the present embodiment, the expander 32 is composed of a plurality of optical lenses and is configured such that the distance between the optical lenses is variable. Then, by adjusting the distance between the optical lenses, the position of the focus of the laser light passing through the scanner 4 can be changed in the direction perpendicular to the stage 2 (the height direction with respect to the stage 2). Note that the expander 32 may have a fixed beam diameter expansion ratio or may be capable of changing the expansion ratio.

[0020] The spot shape adjustment module 33 is a part that converts the characteristics (laser characteristics) of the Gaussian laser light whose beam diameter has been expanded by the expander 32 into flat-top or doughnut-shaped laser light at the irradiation target position, and is composed of a plurality of optical lenses so as to enable such conversion.

[0021] The spot diameter adjustment module 34 is a part that converts the characteristics (laser characteristics) of the laser light converted by the spot shape adjustment module 33 so that the spot diameter at the irradiation target position becomes the target diameter (desired diameter) while maintaining the spot shape at the irradiation target position as flat-top or doughnut-shaped. In the present embodiment, the spot diameter adjustment module 34 is composed of a concave lens 341 and a convex lens 342 so as to enable such conversion, and the laser light incident from the spot shape adjustment module 33 is once diverged by the concave lens 341 and then converted into parallel light by the convex lens 342. Also, the spot diameter adjustment module 34 is configured such that the distance Ld between the concave lens 341 and the convex lens 342 is variable.

[0022] <Scanner> The scanner 4 is a part including a condenser lens 41 that converges the laser beam adjusted by the laser characteristic adjustment unit 3, and a scanning unit 42 that scans the laser beam in a two-axis coordinate system (i.e., two-dimensionally). As an example, an fθ lens is used for the condenser lens 41, and a galvanometer mirror that changes the irradiation position of the laser beam by changing the incident angle or incident position of the laser beam to the fθ lens is used for the scanning unit 42.

[0023] And in such a scanner 4, its scanning region Rs is determined by the maximum value of the scanning angle θs when scanning the laser beam and the distance Lf from the scanner 4 to the stage 2 (or the workpiece placed on the stage 2).

[0024] In the present embodiment, in order to achieve high processing accuracy, the scanning angle θs and the distance Lf are set so that the deviation width between the irradiation target position and the focusing position within the scanning region Rs is within 5 μm, preferably within 1 μm. For this reason, in the present embodiment, the scanning region Rs is a smaller region (5 to 100 mm 2 or so) compared to conventional laser irradiation devices that do not require high processing accuracy.

[0025] Therefore, in the present embodiment, the laser irradiation device moves the stage 2 to move one or more of the plurality of workpieces or one of the plurality of processing target parts into the scanning region Rs of the scanner 4, and then irradiates and scans (laser processing) the laser beam on the workpiece or the processing target part within the scanning region Rs. After the completion of the laser processing, the laser irradiation device moves the stage 2 again to move another workpiece or another processing target part into the scanning region Rs of the scanner 4, and irradiates and scans (laser processing) the laser beam on the workpiece or the processing target part within the scanning region Rs. Thus, the laser irradiation device of the present embodiment performs laser processing on all of the plurality of workpieces or the plurality of processing target parts on the stage 2 by sequentially moving the stage 2 to perform laser processing.

[0026] <Distance measuring sensor> The distance measuring sensor 5 measures the distance Lf from the scanner 4 to the workpiece or part to be machined within the scanning area Rs. Specifically, the distance measuring sensor 5 measures the distances Le1 and Le2 to two points on the periphery of the scanning area Rs. The control unit 6 then calculates the distance Lf using the distances Le1 and Le2 measured by the distance measuring sensor 5. Note that the measurement of distance Lf by the distance measuring sensor 5 is not limited to this method and may be appropriately changed to another method that can measure distance Lf with high accuracy.

[0027] <Department Head> The control unit 6 is a component consisting of a processing unit such as a CPU, and controls each part of the laser irradiation device. Specifically, the control unit 6 performs the following processes during laser processing: transport processing, measurement processing, and focus position adjustment processing.

[0028] First, as part of the transport process, the control unit 6 controls the drive mechanism (not shown) to move the stage 2, thereby moving one of the multiple workpieces or one of the multiple parts to be processed placed on the stage 2 into the scanning area Rs of the scanner 4.

[0029] After the stage 2 moves due to the transport process, the control unit 6 performs a measurement process by measuring the distance Lf to the workpiece or part to be processed within the scanning area Rs using the distance measuring sensor 5. Specifically, the control unit 6 causes the distance measuring sensor 5 to measure the distances Le1 and Le2 to two points on the periphery of the scanning area Rs. Then, the control unit 6 calculates the distance Lf using the distances Le1 and Le2 measured by the distance measuring sensor 5.

[0030] Subsequently, the control unit 6 adjusts the focal position of the condensing lens 41 based on the distance Lf measured by the distance measuring sensor 5 (specifically, the calculated distance Lf) as part of the focal position adjustment process. Specifically, the control unit 6 adjusts the distance between the optical lenses constituting the expander 32 based on the distance Lf, thereby adjusting the focal position of the condensing lens 41 to match the illumination target position (position in a direction perpendicular to the stage 2; depth) at the center of the scanning area Rs (the position where it intersects with the optical axis of the condensing lens 41).

[0031] Furthermore, the control unit 6 performs laser characteristic adjustment processing as a setting process before the start of laser processing.

[0032] As a specific example, when the spot diameter is changed (when it is desired to intentionally change the laser characteristics), the control unit 6 controls the spot diameter adjustment module 34 (specifically, by adjusting the distance Ld between the concave lens 341 and the convex lens 342) to change the characteristics of the laser beam so that the spot diameter at the irradiation target position becomes the target diameter (desired diameter) while maintaining the spot shape at the irradiation target position to be flat-topped or donut-shaped.

[0033] As another example, if the control unit 6 wants to maintain a flat-top or donut-shaped spot at the irradiation target position even when changing the size of the scanning area Rs by changing the distance from the scanner 4 to the stage 2 (in other words, if it wants to intentionally maintain the laser characteristics under circumstances where they would otherwise be altered), it controls the spot diameter adjustment module 34 (specifically, by adjusting the distance Ld between the concave lens 341 and the convex lens 342) to maintain the characteristics of the laser beam so that the spot shape at the irradiation target position remains flat-top or donut-shaped even after changing the distance from the scanner 4 to the stage 2.

[0034] Such transport processing, measurement processing, focus position adjustment processing, and laser characteristic processing are performed by transport processing unit 61, measurement processing unit 62, focus position adjustment processing unit 63, and laser characteristic adjustment processing unit 64 (see Figure 1) built within the control unit 6. In this embodiment, these processing units are composed of software by causing the control unit 6 to execute a program. Such a program may be stored in a readable state on a portable storage medium (e.g., flash memory), read from the storage medium and installed, and then stored in the storage unit (ROM, RAM, etc., not shown) of the laser irradiation device, or it may be stored in a downloadable state on another server, and then downloaded and installed from the server and stored in the above-mentioned storage unit. Note that the transport processing unit 61, measurement processing unit 62, focus position adjustment processing unit 63, and laser characteristic adjustment processing unit 64 may also be composed of hardware by building a circuit within the laser irradiation device.

[0035] According to the laser irradiation device of this embodiment, by moving the stage 2, one of multiple workpieces or one of multiple processing targets can be moved into the scanning area Rs of the scanner 4, and then laser beam irradiation and scanning (laser processing) can be performed on the workpiece or processing target within the scanning area Rs. Furthermore, after the completion of the laser processing, by moving the stage 2 again, another workpiece or another processing target can be moved into the scanning area Rs of the scanner 4, and then laser beam irradiation and scanning (laser processing) can be performed on the workpiece or processing target within the scanning area Rs. By performing such laser processing by sequentially moving the stage 2, laser processing can be performed on all of the multiple workpieces or multiple processing target areas on the stage 2.

[0036] Therefore, with the laser irradiation device of this embodiment, the scanning area Rs can be made smaller compared to the case where laser beam irradiation and scanning (laser processing) are performed on multiple workpieces or multiple processing target parts at once. As a result, the deviation between the irradiation target position and the laser beam focus position within the scanning area Rs is reduced, and high processing accuracy is achieved throughout the entire scanning area Rs. Furthermore, with the laser irradiation device of this embodiment, each time the stage 2 is moved to bring a new workpiece or processing target part into the scanning area Rs, the distance Lf from the scanner 4 to the workpiece or processing target part is measured, and the focal position of the focusing lens 41 is adjusted based on that distance Lf. Therefore, laser processing can be performed with high accuracy on any workpiece or any processing target part.

[0037] Furthermore, with this laser irradiation device, as described above, the stage 2 can be moved sequentially to perform laser processing, allowing for high-speed processing of workpieces or target areas one after another while maintaining a high processing configuration. Thus, the laser irradiation device of this embodiment makes it possible to achieve both improved processing accuracy and high processing speed.

[0038] [2] Variant Figure 2 is a conceptual diagram showing a modified laser irradiation device. As shown in this figure, the laser irradiation device may be appropriately modified so that the laser characteristic adjustment unit 3 does not include the spot shape adjustment module 33 and the spot diameter adjustment module 34.

[0039] The above-described embodiments and modifications should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, rather than by the above-described embodiments and modifications. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

[0040] Furthermore, from the above-described embodiments and modifications, the subject matter of the invention is not limited to a laser irradiation device, but may also be individually extracted from each component constituting the laser control device, the control processes and programs executed by the laser control device, or only a part of them may be partially extracted. [Explanation of symbols]

[0041] 1. Laser oscillator 2 stages 3. Laser characteristic adjustment section 4 Scanners 5. Distance measuring sensor 6 Control Unit 31 Attenuator 32 Expander 33 Spot Shape Adjustment Module 34 Spot Diameter Adjustment Module 41 Focusing lens 42 Scanning Unit 61 Conveying Processing Unit 62 Measurement Processing Unit 63 Focus position adjustment processing unit 64 Laser characteristic adjustment processing unit Ld, Le1, Le2, Lf distance Rs scanning area θs scan angle 341 Concave lens 342 Convex Lens

Claims

1. a laser oscillator that outputs laser light; a stage on which a plurality of workpieces or a workpiece including a plurality of processing target portions is placed and which is movable within a one-axis or two-axis coordinate system; a condenser lens that converges the laser light; a distance measuring sensor that measures a distance to one of the plurality of workpieces or one of the plurality of processing target portions; A control unit; Equipped with The control unit a focal position adjustment processing unit that adjusts a focal position of the condenser lens based on the distance measured by the distance measuring sensor; a laser characteristic adjustment processing unit that adjusts a spot diameter of the laser light; A laser irradiation device comprising:

2. A spot shape adjustment module that converts the characteristics of the laser light output from the laser oscillator so that the spot shape at the irradiation target position becomes flat-top or doughnut-shaped. The laser irradiation device according to claim 1 , further comprising:

3. A scanning unit capable of scanning the laser light converged by the condenser lens. Further provided with 3. The laser irradiation device according to claim 1, wherein the control unit adjusts a focal position of the condenser lens using the focal position adjustment processing unit, and then controls the scanning unit to scan the laser light converged by the condenser lens.

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