Laser processing apparatus and laser processing method

Abstract

To provide a laser beam machining apparatus and a laser beam machining method capable of machining a workpiece by accurately irradiating a target position with a laser beam even when adjusting an irradiation position of the laser beam using a machining mark formed by irradiation of the laser beam.SOLUTION: In the laser processing device 100, the control unit 60 controls the camera 20 to image the transmitted illumination light 51, which is the illumination light that has passed through the through-hole 43 of the processing mark 41, in a state in which the processing mark 41 is irradiated with the visible ray as the illumination light from the transmission layer 40b side by the illumination unit 50.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method that adjust the irradiation position of laser light by image processing. [Background technology]

[0002] BACKGROUND ART Conventionally, a laser processing apparatus and a laser processing method are known that adjust the irradiation position of laser light by image processing (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a laser processing device that forms processed grooves in a wafer by irradiating a laser beam along streets that divide multiple devices formed on the wafer into a grid pattern. The laser processing device of the above-mentioned Patent Document 1 performs alignment detection that detects the position of the street, which is the target position, based on a captured image of an alignment reference formed on the surface of the wafer before laser processing the wafer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-17863 Summary of the Invention [Problem to be solved by the invention]

[0005] In a laser processing apparatus having a configuration such as that disclosed in Patent Document 1, the laser beam irradiation position may change due to the influence of the laser beam transmission optical system over time and changes in ambient temperature. However, conventional laser processing apparatuses such as those described in Patent Document 1, which perform alignment detection based on captured images of alignment fiducials formed on the wafer surface, are unable to detect changes in the laser beam irradiation position. Therefore, processing may be performed while the target processing position and the actual laser beam irradiation position are misaligned. Therefore, in conventional laser processing apparatuses such as those described in Patent Document 1, a method has been proposed for adjusting the laser beam irradiation position based on captured images of the processing marks formed by the laser beam irradiation to match the target processing position and the actual laser beam irradiation position. However, the opening edge of the processing mark on the side where the laser beam is irradiated may be distorted due to burrs or other defects caused by the laser beam irradiation, and therefore the position of the processing mark (the laser beam irradiation position) may not be accurately determined from the captured image of the processing mark. Therefore, there is a demand for a laser processing device and a laser processing method that can accurately irradiate laser light at a target position to process a workpiece, even when adjusting the irradiation position of the laser light using the processing marks formed by irradiating the laser light.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a laser processing apparatus and a laser processing method that are capable of processing a workpiece by irradiating the laser light to a target position with high precision, even when the irradiation position of the laser light is adjusted using the processing marks formed by irradiating the laser light. [Means for solving the problem]

[0007] In order to achieve the above object, a laser processing apparatus according to a first aspect of the present invention includes a laser light irradiating unit that irradiates a workpiece with laser light, an illumination light irradiating unit that irradiates illumination light, an imaging unit that images the illumination light irradiated from the illumination light irradiating unit, and a control unit that controls laser processing of the workpiece, wherein the laser light irradiating unit irradiates a calibration substrate having a transparent layer that transmits the illumination light and a calibration processing layer that is processed by the laser light, the calibration processing layer having a transparent layer that transmits the illumination light and a calibration processing layer that is processed by the laser light, the calibration processing layer having a transparent layer that transmits the illumination light and a calibration processing layer that is processed by the laser light, the calibration processing layer having a transparent layer that transmits the illumination light and a calibration processing layer that is processed by the laser light, the calibration processing layer having a transparent layer that transmits the illumination light and a calibration processing layer having a calibration ... The control unit is configured to irradiate laser light from the calibration processing layer side so as to form a mark, and the control unit controls the illumination light irradiation unit to irradiate the processing mark from the transmission layer side, and the imaging unit to capture transmitted illumination light, which is illumination light that has passed through the through hole of the processing mark, while acquiring the amount of deviation between the position of the transmitted illumination light shown in the image of the transmitted illumination light captured by the imaging unit and the calculated irradiation position of the laser light in the image, and based on the acquired amount of deviation, controls to adjust the irradiation position of the laser light so that the laser light is irradiated at the processing position on the workpiece.

[0008] In the laser processing apparatus according to the first aspect, as described above, the control unit controls the illumination light irradiating unit to irradiate the processing mark with illumination light from the transparent layer side, and the imaging unit to capture transmitted illumination light, which is illumination light that has passed through the through-hole in the processing mark. This prevents the captured image of the transmitted illumination light from showing a distorted shape of the opening end of the processing mark on the side irradiated with the laser light, and allows the captured image of the transmitted illumination light to show a relatively less distorted shape of the opening end of the processing mark on the side opposite to the side irradiated with the laser light. This allows the position of the processing mark to be obtained with high accuracy, allowing the irradiation position of the laser light to be adjusted with high accuracy. As a result, even when the irradiation position of the laser light is adjusted using the processing mark formed by irradiation with the laser light, the laser light can be accurately irradiated to the target position to process the workpiece.

[0009] In the laser processing apparatus according to the first aspect, the laser light irradiating unit is preferably configured to irradiate the calibration substrate with laser light to form a processing mark in which the area of ​​the opening end of the through-hole on the side facing the transparent layer is smaller than the area of ​​the opening end of the through-hole on the side opposite the transparent layer. This configuration can prevent the transmitted illumination light from contacting the opening end of the through-hole on the side facing the transparent layer, thereby efficiently preventing an irregular shape of the opening end of the processing mark on the side irradiated with the laser light from appearing in an image captured with the transmitted illumination light.

[0010] In this case, the laser light irradiation unit is preferably configured to irradiate laser light having a substantially Gaussian distribution profile with the intensity highest at the center. With this configuration, the processing marks formed by irradiation with laser light whose intensity is highest at the center and whose intensity decreases with increasing distance from the center become less processed as the distance from the center decreases, resulting in a tapered through-hole shape that widens from the transparent layer side toward the opposite side of the transparent layer. As a result, contact between the transmitted illumination light and the opening end of the through-hole on the opposite side of the transparent layer can be more efficiently prevented, thereby more efficiently preventing the irregular shape of the opening end of the processing mark on the side irradiated with the laser light from appearing in an image captured with the transmitted illumination light. The term "substantially Gaussian distribution" is a broad concept that includes both a Gaussian distribution and an intensity distribution that is slightly different from a Gaussian distribution.

[0011] The laser processing apparatus of the first aspect preferably further includes a stage for supporting a processing substrate on which the workpiece is placed, and the height of the upper surface of the stage when processing the workpiece is approximately the same as the height of the upper surface of the calibration substrate when processing the calibration substrate. With this configuration, the irradiation position of the laser light when processing the workpiece and the irradiation position of the laser light when processing the calibration substrate are approximately the same, so that the adjusted irradiation position of the laser light can be more accurately matched with the workpiece actually processed. Note that "approximately the same" is a broad concept that includes both the same and slight differences.

[0012] In the laser processing apparatus of the first aspect, the control unit is preferably configured to acquire the position of the transmitted illumination light shown in the captured image of the transmitted illumination light multiple times, acquire an average deviation amount which is the deviation amount between the average value of the acquired positions of the transmitted illumination light and the calculated irradiation position of the laser light, and perform control to adjust the irradiation position of the laser light so that the laser light is irradiated to the processing position based on the acquired average deviation amount. With this configuration, it is possible to reduce the influence of errors in image processing, and therefore it is possible to prevent a decrease in the adjustment accuracy of the irradiation position of the laser light.

[0013] A laser processing method according to a second aspect of the present invention includes a processing mark forming step of irradiating a calibration substrate having a transparent layer that transmits illumination light and a calibration processing layer that is processed by laser light from the calibration processing layer side so that a processing mark is formed that penetrates the calibration processing layer and causes a burr due to the irradiation of the laser light to be generated on the outside as viewed from the calibration processing layer; a transmitted illumination light imaging step of imaging the transmitted illumination light, which is the illumination light that has passed through the through hole of the processing mark while the illumination light is irradiated from the transparent layer side; an adjustment step of acquiring the amount of deviation between the position of the transmitted illumination light shown in the image of the transmitted illumination light captured in the transmitted illumination light imaging step and the calculated irradiation position of the laser light in the image, and adjusting the irradiation position of the laser light so that the laser light is irradiated at the processing position on the workpiece based on the acquired amount of deviation; and a processing step of processing the workpiece by irradiating the laser light.

[0014] As described above, the laser processing method according to the second aspect includes a transmitted illumination light imaging step of irradiating the processing mark from the transmission layer side and imaging the transmitted illumination light, which is illumination light that has passed through the through-hole of the processing mark. This prevents the captured image of the transmitted illumination light from showing a distorted shape of the opening end of the processing mark on the side irradiated with the laser light, and allows the captured image of the transmitted illumination light to show a relatively less distorted shape of the opening end of the processing mark on the side opposite to the side irradiated with the laser light. This allows the position of the processing mark to be obtained with high accuracy, allowing the irradiation position of the laser light to be adjusted with high accuracy. As a result, a laser processing method can be provided that allows the laser light to be accurately irradiated to the target position to process the workpiece, even when the irradiation position of the laser light is adjusted using the processing mark formed by irradiation with the laser light. [Effects of the Invention]

[0015] As described above, the laser processing apparatus and laser processing method of the present invention can accurately irradiate the laser light at the target position to process the workpiece, even when adjusting the irradiation position of the laser light using the processing marks formed by irradiating the laser light. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing the overall configuration of a laser processing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a top view of a workpiece on a wafer according to one embodiment of the present invention. [Figure 3] 3 is a flowchart illustrating a process of a laser processing method according to an embodiment of the present invention. [Figure 4] FIG. 10 is a plan view showing processing marks formed on a calibration substrate according to an embodiment of the present invention. [Figure 5] 10 is a cross-sectional view of processing marks formed on a calibration substrate according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view illustrating transmitted illumination light according to an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing a captured image of transmitted illumination light according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing a captured image of processing marks according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0018] [Embodiment] (Configuration of laser processing equipment) The configuration of a laser processing apparatus 100 according to one embodiment of the present invention will be described with reference to FIGS.

[0019] As shown in FIGS. 1 and 2, the laser processing apparatus 100 is an apparatus for irradiating a workpiece on a wafer with laser light to perform processing. For example, the laser processing apparatus 100 is an apparatus for irradiating a processing position 2a of a wiring pattern 2 on a wafer 1 with laser light L to perform processing. The wiring pattern 2 is, for example, a fuse having a width of 1 μm and a length of 10 μm. Processing may be, for example, blowing the fuse. The processing position 2a may be, for example, the center of gravity of the wiring pattern 2. The wiring pattern 2 is an example of a "workpiece" in the claims. The wafer 1 is an example of a "processed substrate" in the claims.

[0020] As shown in FIG. 1, the laser processing apparatus 100 includes a laser beam irradiation unit 10, a mirror 11, a camera 20, a mirror 21, a stage 30, a moving mechanism 31, a calibration substrate 40, an illumination unit 50, and a control unit 60. In FIG. 1, the left-right direction of the laser processing apparatus 100 (one direction in a horizontal plane) is defined as the X direction. The up-down direction (vertical direction) of the laser processing apparatus 100 is defined as the Z direction. The direction perpendicular to the X and Z directions of the laser processing apparatus 100 (the other direction in a horizontal plane) is defined as the Y direction. In the following description, one side of the X direction is defined as the X1 direction, and the other side is defined as the X2 direction. The back side of the Y direction in FIG. 1 is defined as the Y2 direction, and the front side is defined as the Y1 direction. In the Z direction, the upward direction is defined as the Z1 direction, and the downward direction is defined as the Z2 direction. The camera 20 is an example of an "imaging unit" in the claims. The illumination unit 50 is an example of the "illumination light irradiation unit" in the claims.

[0021] The laser light irradiation unit 10 is a light source that irradiates laser light L having a near-infrared wavelength, for example, a wavelength of 780 nm or more and less than 2500 nm, and a profile of an approximately Gaussian distribution with the highest intensity at the center. When processing the wiring pattern 2, the laser light irradiation unit 10 is controlled by the control unit 60 and configured to irradiate the wiring pattern 2 on the wafer 1 with pulsed laser light L. The spot diameter on the wiring pattern 2 of the laser light L irradiated by the laser light irradiation unit 10 is, for example, 3 μm. The approximately Gaussian distribution is a broad concept that includes a Gaussian distribution and an intensity distribution that is slightly different from the Gaussian distribution.

[0022] Camera 20 includes an internal imaging element (not shown) that is sensitive to at least the wavelength of the illumination light emitted by illumination unit 50. Camera 20 is, for example, a camera that includes an internal imaging element that is sensitive to visible light. Camera 20 is also configured to capture images of processing marks 41 (see FIG. 4) formed on calibration substrate 40 (described later). Camera 20 is configured to output the captured images to control unit 60.

[0023] The mirror 11 is configured to reflect most of the incident laser light L. The mirror 11 is also configured to transmit most of the incident visible light. The mirror 11 reflects most of the laser light L irradiated from the laser light irradiating unit 10 toward the wafer 1 side (Z2 direction). The mirror 11 also transmits most of the visible light irradiated from the wafer 1 side toward the mirror 21 side (Z1 direction). The mirror 11 is, for example, a dichroic mirror.

[0024] The mirror 21 is configured to reflect most of the incident visible light. The mirror 21 reflects most of the visible light that is irradiated from the wafer 1 side and transmitted through the mirror 21 toward the camera 20 (X1 direction).

[0025] The positions and angles of the laser light emitting unit 10, camera 20, mirror 11, mirror 21, and illumination unit 50 (described later) are fixed in an appropriately adjusted state. In addition, the visible light incident on the camera 20 and the laser light L irradiated from the laser light emitting unit 10 are coaxial with the alignment of the mirror 11 and mirror 21.

[0026] The stage 30 is capable of placing the wafer 1 on a flat top plate (surface on the Z1 side). The stage 30 includes a moving mechanism 31. The moving mechanism 31 is configured to be able to move the stage 30 at least in the X and Y directions by being controlled by the control unit 60. As a result, the moving mechanism 31 controlled by the control unit 60 moves the relative position of the laser light L irradiated by the laser light irradiation unit 10 and the stage 30.

[0027] The calibration substrate 40 is mounted on the stage 30 with its relative position relative to the stage 30 fixed. The calibration substrate 40 includes a calibration processing layer 40a and a transmissive layer 40b. The calibration processing layer 40a does not transmit visible light and is processed by laser light L. That is, the calibration processing layer 40a is formed of a material that absorbs laser light L. The calibration processing layer 40a is, for example, a chromium layer vapor-deposited on the transmissive layer 40b. The transmissive layer 40b transmits visible light. The transmissive layer 40b is, for example, a glass substrate.

[0028] The laser processing device 100 is configured to be able to irradiate the wiring pattern 2 on the wafer 1 and the calibration processing layer 40a (calibration substrate 40) with the laser light L by changing the irradiation position of the laser light L using a moving mechanism 31 controlled by a control unit 60. Furthermore, the laser processing device 100 is configured to be able to irradiate the laser light L onto the entire area of ​​the calibration processing layer 40a.

[0029] The illumination unit 50 is, for example, a lighting fixture that irradiates visible light as illumination light. The illumination unit 50 is configured to be able to continuously irradiate visible light under the control of the control unit 60. The illumination unit 50 is provided on the stage 30 so that it can irradiate visible light toward the calibration substrate 40 from the side opposite to the side irradiated with the laser light L, while its relative positional relationship with the calibration substrate 40 is fixed. The illumination unit 50 is configured to be able to irradiate the entire calibration processing layer 40a with visible light. That is, in this embodiment, the illumination unit 50 is a surface light source in which the irradiation area of ​​the illumination light on the calibration substrate 40 has an area equal to or larger than the area of ​​the entire calibration processing layer 40a in which multiple processing marks 41 (see FIG. 4) can be formed.

[0030] The control unit 60 includes, for example, a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a GPU (Graphics Processing Unit). The control unit 60 is configured to execute a program (software) to perform various controls of the laser light irradiation unit 10, the camera 20, the moving mechanism 31, and the illumination unit 50 in accordance with a laser processing process flow (see FIG. 3) described below. Details of the control performed by the control unit 60 will be described later.

[0031] (Laser processing method) Next, the laser processing method according to the present embodiment will be described with reference to FIGS.

[0032] 3, in step S1, the control unit 60 (see FIG. 1) controls the moving mechanism 31 (see FIG. 1) to move the stage 30 to a position on the calibration substrate 40 where the calibration processing layer 40a is irradiated with the laser light L. After step S1 is completed, step S2 is started.

[0033] In step S2, the control unit 60 (see FIG. 1) controls the laser light irradiation unit 10 (see FIG. 1) to irradiate the calibration processing layer 40a of the calibration substrate 40 with laser light L to form processing marks 41 (see FIG. 4). Step S2 is an example of the "processing mark forming step" in the claims.

[0034] As shown in FIGS. 4 and 5 , the processing marks 41 are portions of the calibration processing layer 40a that have been locally processed (deformed) by irradiation with the laser light L. The processing marks 41 include burrs 42 and through holes 43. The burrs 42 are formed by a portion of the calibration processing layer 40a that has been deformed by irradiation with the laser light L, protruding from the side (Z1 side) where the laser light L is irradiated and outside the processing marks 41 when viewed from the side (Z1 side) where the laser light L is irradiated. The burrs 42 are generated in an irregular shape outside the processing marks 41 when viewed from the calibration processing layer 40a side (Z1 side) in the direction in which the calibration processing layer 40a and the transmissive layer 40b are aligned. Note that the calibration substrate 40 and the illumination unit 50 are spaced apart in the direction in which the laser light L is irradiated (the Z-axis direction), so that the illumination unit 50 will not be damaged by the laser light L that has passed through the transmissive layer 40b in step S2.

[0035] The through hole 43 is a portion of the processing mark 41 where the calibration processing layer 40a has been removed. The through hole 43 penetrates the calibration processing layer 40a. That is, in this embodiment, the laser light irradiation unit 10 irradiates the calibration substrate 40, which includes a transparent layer 40b that transmits illumination light (visible light) and a calibration processing layer 40a that is processed by the laser light L, with laser light L from the calibration processing layer 40a side so as to penetrate the calibration processing layer 40a and form a processing mark 41 in which burrs 42 caused by irradiation of the laser light L are generated on the outside as viewed from the calibration processing layer 40a. Furthermore, the area of ​​the opening end 43a of the through hole 43 on the transparent layer 40b side is smaller than the area of ​​the opening end 43b of the through hole 43 on the side opposite the transparent layer 40b. In other words, in this embodiment, the laser light irradiation unit 10 irradiates the calibration substrate 40 with laser light L, thereby forming a processing mark 41 in which the area of ​​the opening end 43a on the transparent layer 40b side of the through hole 43 is smaller than the area of ​​the opening end 43b on the opposite side of the through hole 43 from the transparent layer 40b.

[0036] Returning to FIG. 3, in step S3, the control unit 60 (see FIG. 1) acquires an image and coordinates of the transmitted illumination light 51 (see FIG. 6). Here, as shown in FIG. 6, the transmitted illumination light 51 is the visible light emitted by the illumination unit 50 that has passed through the through-hole 43 of the processing mark 41. The transmitted illumination light 51 has a cross-sectional shape corresponding to the opening end 43a and does not contact the outer periphery of the opening end 43b or the burr 42. The opening end 43b and the burr 42 have irregular shapes, while the opening end 43a has a shape with relatively little distortion. A shape with relatively little distortion is, for example, a circular shape. Therefore, the cross-sectional shape of the transmitted illumination light 51 has a shape with relatively little distortion. Note that step S3 is an example of a "transmitted illumination light imaging process" in the claims.

[0037] In step S3, as shown in FIGS. 6 and 7 , the control unit 60 causes the illumination unit 50 to emit visible light and causes the camera 20 (see FIG. 1 ) to capture the transmitted illumination light 51, thereby acquiring a transmitted illumination light image 70 and the coordinates (xa, ya) of the transmitted illumination light 51 captured in the transmitted illumination light image 70. That is, in this embodiment, the control unit 60 controls the illumination unit 50 to emit visible light as illumination light toward the processing marks 41 from the transmissive layer 40b side, and causes the camera 20 to capture the transmitted illumination light 51, which is illumination light that has passed through the through-holes 43 in the processing marks 41. Here, the coordinates represent the amount of deviation in the left-right direction (X direction) and the up-down direction (Y direction) in the captured image, based on the coordinates (0, 0) of the center point C1 of the captured image. Note that, for example, in the case of deviation in the left-right direction, a positive value is obtained when the image is deviated to the right from the coordinates (0, 0) of the center point C1, and a negative value is obtained when the image is deviated to the left. In the case of vertical deviation, if the deviation is in the upward direction from the coordinates (0, 0) of the center point C1 in the captured image, the value is positive, and if the deviation is in the downward direction, the value is negative.

[0038] In step S3, the control unit 60 is configured to acquire the coordinates of the transmitted illumination light 51 appearing in the transmitted illumination light image 70 multiple times. Specifically, the control unit 60 is configured to acquire the coordinates of the transmitted illumination light 51 appearing in the transmitted illumination light image 70 a predetermined number of times set in advance by the user.

[0039] The coordinates of the transmitted illumination light 51 are acquired with respect to a coordinate reference 51b of the contour 51a of the transmitted illumination light 51. The coordinate reference 51b is, for example, the center of gravity of the contour 51a of the transmitted illumination light 51. The contour 51a of the transmitted illumination light 51 in the transmitted illumination light image 70 is calculated using a known image processing method that connects pixels having a large difference in brightness value between adjacent pixels. As described above, the cross-sectional shape of the transmitted illumination light 51 has a relatively small distortion corresponding to the shape of the opening end 43a of the through-hole 43 on the transparent layer 40b side. Therefore, the coordinate reference 51b accurately matches the actual irradiation position of the laser light L. The transmitted illumination light image 70 is an example of a "captured image of transmitted illumination light" in the claims. The center point C1 of the captured image of the camera 20 is also an example of a "calculated irradiation position of the laser light in the captured image" in the claims.

[0040] Here, as shown in FIG. 8 as a comparative example, unlike the present embodiment, in step S3, the control unit 60 (see FIG. 1 ) causes the camera 20 to capture an image of the processing mark 41 while irradiating visible light as illumination light from an illumination unit (not shown) that irradiates illumination light from the side where the laser light L is irradiated, thereby acquiring a comparative captured image 71. Unlike the transmitted illumination light 51, the visible light irradiated from the side where the laser light L is irradiated in the comparative example is reflected upon contact with the opening edge 43b and the burr 42, so that the shapes of the opening edge 43b and the burr 42 are captured in the comparative captured image 71. The position of the processing mark 41 is calculated based on the coordinate reference 42b, which is the center of gravity of the contour 42a having an irregular shape that reflects the shapes of the opening edge 43b and the burr 42. However, because the coordinate reference 42b is the center of gravity of the contour 42a having an irregular shape as described above, the calculated position of the processing mark 41 in the comparative example does not accurately match the actual irradiation position of the laser light L.

[0041] After step S3 is completed, step S4 is started. In step S4, the control unit 60 (see FIG. 1) calculates the average value of the coordinates of the multiple transmitted illumination lights 51 acquired in step S3. Here, as an example, a case will be described in which the coordinates of the multiple transmitted illumination lights 51 acquired in step S3 are all the same coordinates (xa, xb). In this case, the average value of the coordinates calculated by the control unit 60 is (xa, xb). Note that if the coordinates of the transmitted illumination light 51 have been acquired once in step S3 (if the predetermined number of times set in advance by the user is once), step S4 is not executed. After step S4 is completed, step S5 is started.

[0042] In step S5, the control unit 60 (see FIG. 1) adjusts the irradiation position of the laser light L based on the positional relationship between the transmitted illumination light 51 and the calculated irradiation position of the laser light L. Specifically, as shown in FIGS. 3 and 7, the control unit 60 calculates the amount of deviation between the average value (xa, xb) of the coordinates of the multiple transmitted illumination lights 51 calculated in step S4 (the coordinates acquired in step S3 if the predetermined number of times set in advance by the user is 1 time) and the calculated irradiation position of the laser light L.

[0043] That is, in this embodiment, the control unit 60 acquires the amount of deviation between the position of the transmitted illumination light 51 shown in the transmitted illumination light image 70, which is an image of the transmitted illumination light 51 captured by the camera 20, and the calculated irradiation position of the laser light L in the transmitted illumination light image 70, and, based on the acquired amount of deviation, performs control to adjust the irradiation position of the laser light L so that the laser light L is irradiated onto the processing position 2 a on the wiring pattern 2. Furthermore, in this embodiment, the control unit 60 acquires the position of the transmitted illumination light 51 shown in the transmitted illumination light image 70, which is an image of the transmitted illumination light 51, multiple times, acquires the amount of deviation between the average value of the acquired multiple positions of the transmitted illumination light 51 and the calculated irradiation position of the laser light L in the transmitted illumination light image 70, and, based on the acquired amount of deviation, performs control to adjust the irradiation position of the laser light L so that the laser light L is irradiated onto the processing position 2 a.

[0044] In this embodiment, the calculated irradiation position of the laser light L is the center of the field of view of the image captured by the camera 20. In other words, the deviation represents the deviation of the position of the transmitted illumination light 51 (the irradiation position of the laser light L) from the center point C1 (0, 0) of the transmitted illumination light image 70, and the deviation is calculated as (0-xa, 0-ya) = (-xa, -ya). The control unit 60 then controls the moving mechanism 31 to move the stage 30 so as to move the irradiation position of the laser light L by the calculated deviation (-xa, -ya). The deviation is an example of the "deviation amount" and "average deviation amount" in the claims. Step S5 is also an example of the "adjustment step" in the claims. After step S5 is completed, step S6 is started.

[0045] As shown in FIGS. 1 to 3, in step S6, the control unit 60 controls the moving mechanism 31 to move the stage 30 to a position where the wiring pattern 2 can be processed (a position where the laser light L is irradiated onto the wiring pattern 2). Specifically, for example, the control unit 60 causes the camera 20 to capture an image of an alignment mark (not shown) formed on the wafer 1, and controls the moving mechanism 31 to move the stage 30 to a position where the wiring pattern 2 can be processed based on the position of the alignment mark captured in the captured image of the alignment mark. The positional relationship between the alignment mark and the wiring pattern 2 is stored in advance in the control unit 60. At this time, the control unit 60 moves the stage 30 so that the center of the field of view of the camera 20 (the calculated irradiation position of the laser light) and the processing position 2a of the wiring pattern 2 coincide with each other. Since the center of the field of view of the camera 20 (the calculated irradiation position of the laser light) and the actual irradiation position of the laser light L are aligned in step S5, as a result of step S6, the actual irradiation position of the laser light L and the processing position 2a of the wiring pattern 2 coincide with each other. After step S6 is completed, step S7 is started.

[0046] Returning to FIG. 3, in step S7, the control unit 60 (see FIG. 1) processes the wiring pattern 2. Specifically, the control unit 60 controls the laser light irradiation unit 10 to irradiate a processing position 2a of the wiring pattern 2 with pulsed laser light L, thereby processing the wiring pattern 2. Note that in this embodiment, the height of the upper surface (the surface on the Z1 side in FIG. 1) of the stage 30 when processing the wiring pattern 2 is approximately the same as the height of the upper surface (the surface on the Z1 side in FIG. 1) of the calibration substrate 40 when processing the calibration substrate 40 in step S2. Here, "approximately the same" is a broad concept that includes cases where the heights are the same and cases where the heights are slightly different. Furthermore, "approximately the same height" means that the laser light L is at approximately the same position in the direction (Z-axis direction) in which the stage 30 and the calibration substrate 40 are irradiated. Note that step S7 is an example of a "processing step" in the claims. After step S7 is completed, the process of the laser processing method ends. Steps S1 to S7 are performed for each wafer 1, for each predetermined number of wafers 1, for each processing, for each predetermined number of processings, or at predetermined time intervals.

[0047] (Effects of the embodiment) Next, the effects of this embodiment will be described.

[0048] In this embodiment, as described above, the control unit 60 controls the camera 20 to capture transmitted illumination light 51, which is illumination light that has passed through the through-hole 43 of the processing mark 41, while the illumination unit 50 irradiates the processing mark 41 with visible light as illumination light from the transmissive layer 40b side. This prevents the distorted shape of the opening end 43b of the processing mark 41 on the side irradiated with the laser light L from appearing in the transmitted illumination light image 70, which is the captured image of the transmitted illumination light 51. Furthermore, the transmitted illumination light image 70, which is the captured image of the transmitted illumination light 51, captures a relatively less distorted shape of the opening end 43a of the processing mark 41 on the side opposite to the side irradiated with the laser light L. This allows the position of the processing mark 41 to be acquired with high accuracy, thereby enabling the irradiation position of the laser light L to be adjusted with high accuracy. As a result, even when the irradiation position of the laser light L is adjusted using the processing mark 41 formed by irradiation with the laser light L, the laser light L can be accurately irradiated to the target position to process the wiring pattern 2.

[0049] Furthermore, in this embodiment, as described above, the laser light irradiation unit 10 is configured to irradiate the calibration substrate 40 with laser light L to form processing marks 41 in which the area of ​​the opening end 43a on the transparent layer 40b side of the through-hole 43 is smaller than the area of ​​the opening end 43b on the opposite side from the transparent layer 40b of the through-hole 43. This makes it possible to prevent the transmitted illumination light 51 from coming into contact with the opening end 43b on the opposite side from the transparent layer 40b of the through-hole 43, and therefore makes it possible to efficiently prevent the irregular shape of the opening end 43b of the processing marks 41 on the side irradiated with the laser light L from appearing in the transmitted illumination light image 70, which is an image captured of the transmitted illumination light 51.

[0050] Furthermore, in this embodiment, as described above, the laser light irradiation unit 10 is configured to irradiate laser light L having a substantially Gaussian distribution profile with the intensity highest at the center. As a result, the processed mark 41 formed by irradiation with laser light L, which has the highest intensity at the center and decreases in intensity with increasing distance from the center, is formed into a shape having a tapered through-hole 43 that widens from the transmissive layer 40b side toward the side opposite the transmissive layer 40b side, since the degree of processing decreases with increasing distance from the center. As a result, contact between the transmitted illumination light 51 and the opening end 43b of the through-hole 43 on the side opposite the transmissive layer 40b can be more efficiently prevented, and therefore, the irregular shape of the opening end 43b of the processed mark 41 on the side irradiated with the laser light L can be more efficiently prevented from appearing in the transmitted illumination light image 70, which is a captured image of the transmitted illumination light 51.

[0051] Furthermore, as described above, this embodiment further includes a stage 30 for placing the wafer 1 on which the wiring pattern 2 is to be arranged, and the height of the upper surface of the stage 30 when processing the wiring pattern 2 is approximately the same as the height of the upper surface of the calibration substrate 40 when processing the calibration substrate 40. This makes the irradiation position of the laser light L when processing the wiring pattern 2 approximately the same as the irradiation position of the laser light L when processing the calibration substrate 40, so that the adjusted irradiation position of the laser light L can be more accurately matched with the wiring pattern 2 that is actually processed.

[0052] Furthermore, in this embodiment, as described above, the control unit 60 is configured to acquire the position of the transmitted illumination light 51 reflected in the transmitted illumination light image 70, which is an image captured of the transmitted illumination light 51, multiple times, acquire an average deviation amount, which is the amount of deviation between the average value of the acquired positions of the transmitted illumination light 51 and the center point C1 of the image captured by the camera 20, which is the calculated irradiation position of the laser light, and perform control to adjust the irradiation position of the laser light L so that the laser light L is irradiated to the processing position 2a, based on the acquired average deviation amount. This reduces the influence of errors in image processing, and therefore prevents a decrease in the adjustment accuracy of the irradiation position of the laser light L.

[0053] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0054] For example, in this embodiment, an example in which the workpiece is a wiring pattern on a wafer has been shown, but the present invention is not limited to this. For example, the workpiece may be a wiring that is not formed on a wafer, or may be an object made of resin or the like that can be processed by laser light. Furthermore, the wiring pattern may be a simple wiring pattern other than a fuse.

[0055] In addition, in this embodiment, an example has been shown in which the laser light L is near-infrared light (infrared light), but the present invention is not limited to this. For example, the laser light L may be ultraviolet light.

[0056] Furthermore, in the present embodiment, an example has been shown in which the illumination unit 50 emits visible light and the camera 20 has an image sensor sensitive to visible light, but the present invention is not limited to this. For example, the illumination unit 50 may emit infrared light and the camera 20 may have an image sensor sensitive to infrared light, or the illumination unit 50 may emit ultraviolet light and the camera 20 may have an image sensor sensitive to ultraviolet light. In other words, as long as the camera 20 has sensitivity to the wavelength range of the illumination light emitted by the illumination unit 50, the illumination light does not have to be visible light.

[0057] In the present embodiment, the laser light irradiation unit 10 is configured to irradiate laser light L having a substantially Gaussian profile with the highest intensity at the center, but the present invention is not limited to this. For example, the laser light irradiation unit 10 may be configured to irradiate laser light L having a substantially flat-top profile with constant intensity throughout.

[0058] Furthermore, in the present embodiment, an example has been shown in which the height of the upper surface of the stage 30 when processing the wiring pattern 2 and the height of the upper surface of the calibration substrate 40 when processing the calibration substrate 40 are approximately the same, but the present invention is not limited to this. For example, the height of the upper surface of the stage 30 when processing the wiring pattern 2 and the height of the upper surface of the calibration substrate 40 when processing the calibration substrate 40 may be different.

[0059] Furthermore, in the present embodiment, the control unit 60 forms one processing mark 41 in step S2, and performs steps S3 and S4 on the one processing mark 41 formed in step S2, but the present invention is not limited to this. For example, the control unit 60 may form multiple processing marks 41 in step S2, perform steps S3 and S4 on the multiple processing marks 41 formed in step S2, and adjust the irradiation position of the laser light L based on the median value of the coordinates of the multiple transmitted illumination lights 51 corresponding to the multiple processing marks 41.

[0060] Furthermore, in the present embodiment, an example has been shown in which a deviation amount between the position of the transmitted illumination light 51 shown in the transmitted illumination light image 70, which is an image of the transmitted illumination light 51 captured by the camera 20, and a calculated irradiation position of the laser light L in the transmitted illumination light image 70 is acquired, and based on the acquired deviation amount, control is performed to adjust the irradiation position of the laser light L so that the laser light L is irradiated onto the processing position 2 a on the wiring pattern 2, but the present invention is not limited to this. For example, a deviation amount between the position of the transmitted illumination light 51 shown in the transmitted illumination light image 70, which is an image of the transmitted illumination light 51 captured by the camera 20, and the position of the processing position 2 a on the wiring pattern 2, which is imaged by the camera 20, may be acquired, and based on the acquired deviation amount, control may be performed to adjust the irradiation position of the laser light L so that the laser light L is irradiated onto the processing position 2 a on the wiring pattern 2. [Explanation of symbols]

[0061] 1. Wafer (processed substrate) 2. Wiring pattern (workpiece) 2a Processing position 10 Laser light irradiation unit 20 Camera (imaging unit) 30 stages 40 Calibration Board 40a Calibration processing layer 40b Transparent layer 41 Machining marks 42 Bali 43 Through hole 43a, 43b open end 50 Lighting Department 51 Transmitted illumination light 60 Control Unit 70 Transmitted illumination image (image captured by transmitted illumination light) 100 Laser processing equipment L laser light C1 Center point of the captured image (calculated laser beam irradiation position)

Claims

1. a laser light irradiation unit that irradiates a laser light toward a workpiece; an illumination light irradiation unit that irradiates illumination light; an imaging unit that captures an image of the illumination light emitted from the illumination light irradiation unit; a control unit that controls laser processing of the workpiece, the laser light irradiation unit is configured to irradiate a calibration substrate, which has a transparent layer that transmits the illumination light and a calibration processing layer that is processed by the laser light, from the calibration processing layer side so that the laser light penetrates the calibration processing layer and forms a processing mark in which a burr caused by irradiation of the laser light is generated on the outside as viewed from the calibration processing layer; The control unit The illumination light irradiation unit irradiates the processing mark with the illumination light from the transmission layer side, and the imaging unit controls to capture an image of the transmitted illumination light, which is the illumination light that has passed through the through hole of the processing mark; a laser processing device configured to acquire a deviation amount between a position of the transmitted illumination light shown in an image of the transmitted illumination light captured by the imaging unit and a calculated irradiation position of the laser light in the captured image, and to perform control to adjust the irradiation position of the laser light based on the acquired deviation amount so that the laser light is irradiated at a processing position on the workpiece.

2. 2. The laser processing device according to claim 1, wherein the laser light irradiation unit is configured to irradiate the calibration substrate with the laser light to form the processing mark in which the area of ​​the opening end of the through hole on the side of the transparent layer is smaller than the area of ​​the opening end of the through hole on the side opposite to the transparent layer.

3. 3. The laser processing device according to claim 2, wherein the laser light irradiating unit is configured to irradiate the laser light having a profile of approximately Gaussian distribution with the intensity highest at a central portion.

4. Further, a stage is provided on which a processing substrate on which the workpiece is placed is placed, 2. The laser processing device according to claim 1, wherein the height of the upper surface of the stage when processing the workpiece is approximately the same as the height of the upper surface of the calibration substrate when processing the calibration substrate.

5. 2. The laser processing device according to claim 1, wherein the control unit is configured to acquire the position of the transmitted illumination light appearing in the captured image of the transmitted illumination light multiple times, acquire an average deviation amount which is the deviation amount between the average value of the acquired positions of the transmitted illumination light and the calculated irradiation position of the laser light, and perform control to adjust the irradiation position of the laser light so that the laser light is irradiated to the processing position based on the acquired average deviation amount.

6. a processing mark forming step of irradiating a calibration substrate, which has a transparent layer that transmits illumination light and a calibration processing layer that is processed by laser light, with the laser light from the calibration processing layer side so as to form a processing mark that penetrates the calibration processing layer and in which a burr caused by irradiation of the laser light is generated on the outside as viewed from the calibration processing layer; a transmitted illumination light imaging step of imaging transmitted illumination light, which is the illumination light that has passed through a through hole of the processing mark, in a state in which the illumination light is irradiated onto the processing mark from the transmission layer side; an adjusting step of acquiring a deviation amount between a position of the transmitted illumination light shown in an image of the transmitted illumination light captured in the transmitted illumination light capturing step and a calculated irradiation position of the laser light in the captured image, and adjusting the irradiation position of the laser light based on the acquired deviation amount so that the laser light is irradiated to a processing position on a workpiece; a processing step of processing the workpiece by irradiating the workpiece with the laser light.

Images