Inspection method for laser processing equipment and laser processing equipment

Abstract

To make it easy to confirm a device status.SOLUTION: An inspection method for a laser processing device includes: a preparation step 1001 which prepares a reference processed object on whose processed surface a regular processing pattern is formed by using a laser processing device in a normal device status to irradiate the laser beam; an imposing processing step 1002 which forms the regular processing pattern by imposing the same on the surface of the reference processed object by using a real laser processing device to irradiate laser beam to the reference processed object; and a determination step 1003 which determines that the laser processing device is not changed from the normal status when there is no Moire in the reference processed object to which overlapping processing is applied, and determines that the laser processing device is changed from the normal status when Moire exists.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an inspection method for a laser processing apparatus and a laser processing apparatus.

Background Art

[0002] Techniques for irradiating a workpiece such as a semiconductor wafer or an optical device wafer with a laser beam for processing are widespread (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, short-wavelength laser beams capable of reducing the condensing diameter of the laser beam at the irradiation position, short-pulse laser beams capable of reducing thermal damage, etc. have been put into practical use, and applications to materials that were conventionally difficult to process are expected.

[0005] In order to perform such processing, the laser processing apparatus used needs to frequently perform maintenance work for checking the apparatus state in order to achieve highly accurate processing.

[0006] Specifically, before using the apparatus, the output and profile measurement of the laser beam, confirmation of the condensing position, confirmation of the processing result, etc. are performed to check whether there is any abnormality in the apparatus state, and then processing is started.

[0007] Such maintenance work takes a lot of man-hours and often requires work by skilled workers, which has been a factor in reducing productivity.

[0008] The present invention has been made in view of the aforementioned problems, and aims to provide a laser processing apparatus inspection method and a laser processing apparatus that can easily check the status of the apparatus. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the objective, the present invention provides a laser processing apparatus inspection method, comprising: a preparation step of preparing a reference workpiece in which a regular processing pattern is formed on the surface of the workpiece by irradiating the workpiece with a laser beam using a laser processing apparatus in a normal state; a superposition processing step of superimposing the regular processing pattern onto the processing pattern formed on the surface of the reference workpiece by irradiating the reference workpiece with a laser beam using an actual laser processing apparatus; and a determination step of determining that the laser processing apparatus has not changed from a normal state if no moiré (interference fringes) are present on the superposition processed reference workpiece, and determining that the laser processing apparatus has changed from a normal state if moiré (interference fringes) are present.

[0010] The laser processing apparatus of the present invention comprises a holding table for holding a workpiece, a laser beam irradiation unit for irradiating a laser beam onto the workpiece held on the holding table to perform processing, an imaging unit for imaging the workpiece, and a control unit for controlling each component, wherein the control unit includes a storage unit that uses a normal laser processing apparatus to irradiate a reference workpiece with a laser beam to capture a regular processing pattern formed on the surface of the workpiece and stores it in advance as a reference pattern image. Under the same conditions that the laser processing apparatus in a normal state formed the regular processing pattern By irradiating a workpiece with a laser beam using an actual laser processing device, a regular processing pattern formed on the surface of the workpiece is captured, and the captured image and the reference pattern image are compared. Pixels of the same location on the workpiece By overlapping them, When the processing marks of the processing pattern formed by the laser processing device in its normal state and the processing marks formed by the actual laser processing device are misaligned, a moiré pattern is created.The system is characterized by comprising an image processing unit that forms a superimposed image, and a display unit that displays the superimposed image formed by the image processing unit.

[0011] The laser processing apparatus of the present invention comprises a holding table for holding a workpiece, a laser beam irradiation unit for irradiating a laser beam onto the workpiece held on the holding table to perform processing, an imaging unit for imaging the workpiece, and a control unit for controlling each component, wherein the control unit includes a storage unit that uses a normal laser processing apparatus to irradiate a reference workpiece with a laser beam to capture a regular processing pattern formed on the surface of the workpiece and stores it in advance as a reference pattern image. Under the same conditions that the laser processing apparatus in a normal state formed the regular processing pattern By irradiating a workpiece with a laser beam using an actual laser processing device, a regular processing pattern formed on the surface of the workpiece is captured, and the captured image and the reference pattern image are compared. Pixels of the same location on the workpiece By superimposing them, When the processing marks of the processing pattern formed by the laser processing device in its normal state and the processing marks formed by the actual laser processing device are misaligned, a moiré pattern is created. The system is characterized by comprising: an image processing unit that forms a superimposed image; and a determination unit that determines that the laser processing apparatus has not changed from a normal state if no moiré (interference fringes) are present in the superimposed image formed by the image processing unit, and determines that the laser processing apparatus has changed from a normal state if moiré (interference fringes) are present. In the laser processing apparatus, the determination unit may extract the pixel with the highest brightness and the pixel with the lowest brightness from the pixels of the superimposed image, and determine whether the laser processing apparatus has deviated from its normal state based on the difference in brightness between these pixels. [Effects of the Invention]

[0012] This invention has the effect of making it possible to easily check the status of the device. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic perspective view showing an example of the configuration of a laser processing apparatus according to Embodiment 1. [Figure 2] Figure 2 is a flowchart showing the flow of the inspection method for a laser processing apparatus according to Embodiment 1. [Figure 3]FIG. 3 is a perspective view schematically showing a preparation step of the inspection method of the laser processing apparatus shown in FIG. 2. [Figure 4] FIG. 4 is a view showing the surface of a reference workpiece prepared in the preparation step of the inspection method of the laser processing apparatus shown in FIG. 2. [Figure 5] FIG. 5 is a perspective view schematically showing a lamination processing step of the inspection method of the laser processing apparatus shown in FIG. 2. [Figure 6] FIG. 6 is a view showing an example of the surface of a reference workpiece determined in the determination step of the inspection method of the laser processing apparatus shown in FIG. 2. [Figure 7] FIG. 7 is a view showing another example of the surface of a reference workpiece determined in the determination step of the inspection method of the laser processing apparatus shown in FIG. 2. [Figure 8] FIG. 8 is a perspective view schematically showing a configuration example of the laser processing apparatus according to Embodiment 2. [Figure 9] FIG. 9 is a view showing a reference pattern image stored in the storage unit of the laser processing apparatus shown in FIG. 8. [Figure 10] FIG. 10 is a view showing an example of an overlapping image formed by the image processing unit of the laser processing apparatus shown in FIG. 8. [Figure 11] FIG. 11 is a view showing another example of an overlapping image formed by the image processing unit of the laser processing apparatus shown in FIG. 8. [Figure 12] FIG. 12 is a flowchart showing the flow of the inspection method of the laser processing apparatus according to Embodiment 2. [Figure 13] FIG. 13 is a perspective view schematically showing a configuration example of the laser processing apparatus according to Embodiment 3. [Figure 14] FIG. 14 is a flowchart showing the flow of the inspection method of the laser processing apparatus according to Embodiment 3.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[0015] [Embodiment 1] A laser processing apparatus according to Embodiment 1 of the present invention will be described based on the drawings. Figure 1 is a schematic perspective view showing an example of the configuration of the laser processing apparatus according to Embodiment 1. The laser processing apparatus 1 shown in Figure 1 is a processing apparatus that irradiates a wafer 200 with a laser beam 21 to perform laser processing.

[0016] (Waha) The wafer 200 to be processed by the laser processing apparatus 1 shown in Figure 1 is a disc-shaped semiconductor wafer or optical device wafer with a substrate made of silicon, sapphire, gallium, etc. Multiple intersecting division lines are set on the surface of the wafer 200, and devices are formed in the regions demarcated by these division lines. In this invention, the wafer 200 may not have division lines formed on it.

[0017] The devices include, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), image sensors such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors), or memory (semiconductor memory devices).

[0018] In Embodiment 1, as shown in Figure 1, the wafer 200 is supported within the opening of the annular frame 203 by attaching a tape 202, which is disc-shaped with a diameter larger than the outer diameter of the wafer 200 and has an annular frame 203 attached to its outer edge. The wafer 200 is divided into individual devices by irradiating the division lines with a laser beam 21 or the like. In this invention, the wafer 200 does not necessarily have to be attached to the tape 202.

[0019] In Embodiment 1, the wafer 200 is an optical device wafer in which a semiconductor layer (epitaxial layer) such as gallium nitride (GaN) is formed on the surface of an epitaxy substrate such as a sapphire substrate or a SiC substrate, multiple optical devices such as LEDs are formed on this semiconductor layer, and a transfer substrate 201 is bonded to the optical devices via an adhesive layer. In Embodiment 1, the wafer 200 is irradiated from the substrate side with a laser beam 21 having a wavelength of, for example, 266 nm by a laser processing apparatus 1 to form a modified layer near the interface between the substrate and the optical devices, and a so-called lift-off process is performed in which the optical devices are separated from the substrate and transferred to the transfer substrate 201, starting from this modified layer. In this invention, the wafer 200 may not have a division line formed on it.

[0020] (Laser processing equipment) The laser processing apparatus 1 shown in Figure 1 is a processing apparatus that irradiates a wafer 200 with a laser beam 21 to perform a so-called lift-off process. As shown in Figure 1, the laser processing apparatus 1 comprises a holding table 10 for holding the wafer 200, a laser beam irradiation unit 20, a moving unit 30, an imaging unit 40, and a control unit 100.

[0021] The holding table 10 holds a workpiece such as a wafer 200 on a holding surface 11 parallel to the horizontal direction. The holding surface 11 is a disc shape formed from porous ceramic or the like and is connected to a vacuum suction source (not shown) via a suction path (not shown). The holding table 10 holds the wafer 200 placed on the holding surface 11 by suction from the vacuum suction source. Multiple clamping parts 12 are arranged around the holding table 10 to hold an annular frame 203 that supports the wafer 200 within the opening.

[0022] Furthermore, the holding table 10 is rotated by the rotational movement unit 33 of the moving unit 30 around an axis that is perpendicular to the holding surface 11 and parallel to the Z-axis direction which is also parallel to the vertical direction. Together with the rotational movement unit 33, the holding table 10 is moved in the X-axis direction parallel to the horizontal direction by the X-axis movement unit 31 of the moving unit 30, and moved in the Y-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction by the Y-axis movement unit 32. The holding table 10 is moved by the moving unit 30 between the processing area below the laser beam irradiation unit 20 and the loading / unloading area away from below the laser beam irradiation unit 20 where the wafer 200 is loaded and unloaded.

[0023] The moving unit 30 moves the holding table 10 and the focal point of the laser beam 21 irradiated by the laser beam irradiation unit 20 relative to each other in the X-axis direction, Y-axis direction, Z-axis direction, and an axis parallel to the Z-axis direction. The X-axis direction and Y-axis direction are mutually orthogonal and parallel to the holding surface 11 (i.e., the horizontal direction). The Z-axis direction is perpendicular to both the X-axis direction and the Y-axis direction.

[0024] The moving unit 30 includes an X-axis moving unit 31, which is a machining feed unit that moves the holding table 10 in the X-axis direction; a Y-axis moving unit 32, which is an indexing feed unit that moves the holding table 10 in the Y-axis direction; a rotational moving unit 33 that rotates the holding table 10 around an axis parallel to the Z-axis direction; and a Z-axis moving unit 34 that moves the focal point of the laser beam 21 of the laser beam irradiation unit 20 in the Z-axis direction.

[0025] The Y-axis movement unit 32 is an indexing feed unit that moves the holding table 10 and the focusing point of the laser beam 21 of the laser beam irradiation unit 20 relative to each other in the Y-axis direction. In Embodiment 1, the Y-axis movement unit 32 is installed on the main body 2 of the laser processing apparatus 1. The Y-axis movement unit 32 supports the moving plate 5, which supports the X-axis movement unit 31, so that it can move freely in the Y-axis direction.

[0026] The X-axis movement unit 31 is a machining feed unit that moves the holding table 10 and the focusing point of the laser beam 21 of the laser beam irradiation unit 20 relative to each other in the X-axis direction. The X-axis movement unit 31 is installed on a movement plate 5. The X-axis movement unit 31 supports a second movement plate 6 that is movable in the X-axis direction, and the second movement plate 6 supports a rotational movement unit 33 that rotates the holding table 10 around an axis parallel to the Z-axis direction. The second movement plate 6 supports the rotational movement unit 33 and the holding table 10. The rotational movement unit 33 supports the holding table 10.

[0027] The Z-axis movement unit 34 is a feed unit that moves the holding table 10 and the focusing point of the laser beam 21 of the laser beam irradiation unit 20 relative to each other in the Z-axis direction. The Z-axis movement unit 34 is installed on an upright wall 3 that is erected from the main body of the device 2. The Z-axis movement unit 34 supports a support column 4, which has a part of the laser beam irradiation unit 20, including a focusing lens (described later), positioned at its tip, so as to be movable in the Z-axis direction.

[0028] The X-axis movement unit 31 includes a well-known ball screw that is rotatable around its axis and moves the second movement plate 6 in the X-axis direction when rotated around its axis, a well-known pulse motor that rotates the ball screw around its axis, and a well-known guide rail that supports the second movement plate 6 so as to be movable in the X-axis direction. The Y-axis movement unit 32 includes a well-known ball screw that is rotatable around its axis and moves the movement plate 5 in the Y-axis direction when rotated around its axis, a well-known pulse motor that rotates the ball screw around its axis, and a well-known guide rail that supports the movement plate 5 so as to be movable in the Y-axis direction. The Z-axis movement unit 34 includes a well-known ball screw that is rotatable around its axis and moves the support column 4 in the Z-axis direction when rotated around its axis, a well-known pulse motor that rotates the ball screw around its axis, and a well-known guide rail that supports the support column 4 so as to be movable in the Z-axis direction. The rotational movement unit 33 includes a motor that rotates the holding table 10 around its axis, etc.

[0029] Furthermore, the laser processing apparatus 1 includes an X-axis position detection unit (not shown) for detecting the position of the holding table 10 in the X-axis direction, a Y-axis position detection unit (not shown) for detecting the position of the holding table 10 in the Y-axis direction, and a Z-axis position detection unit (not shown) for detecting the position (corresponding to the height position) of the focusing lens of the laser beam irradiation unit 20 in the Z-axis direction. Each position detection unit outputs the detection result to the control unit 100. In this embodiment 1, the X-axis and Y-axis positions of the holding table 10 of the laser processing apparatus 1 and the Z-axis position of the focusing lens of the laser beam irradiation unit 20 are determined by the distances in the X-axis, Y-axis, and Z-axis directions from a predetermined reference position (not shown).

[0030] The laser beam irradiation unit 20 is a laser beam irradiation means that irradiates a workpiece such as a wafer 200 held on the holding surface 11 of the holding table 10 with a pulsed laser beam 21 to perform laser processing (lift-off processing in Embodiment 1). In Embodiment 1, a part of the laser beam irradiation unit 20 is positioned at the tip of a support column 4, which is supported by a Z-axis moving unit 34 installed on a vertical wall 3 erected from the main body of the apparatus 2, as shown in Figure 1.

[0031] The laser beam irradiation unit 20 includes a laser oscillator that emits a pulsed laser beam 21 and a focusing lens that focuses the laser beam 21 emitted from the laser oscillator and irradiates the wafer 200 with it.

[0032] The focusing lens is positioned opposite the holding surface 11 of the holding table 10 in the Z-axis direction. The focusing lens is a focusing optical element that focuses and irradiates a pulsed laser beam 21 onto a wafer 200 held on the holding table 10. The focusing lens transmits the laser beam 21 emitted from the laser oscillator and focuses the laser beam 21 to the focal point.

[0033] The imaging unit 40 images a workpiece, such as a wafer 200, held on the holding table 10. The imaging unit 40 is equipped with an image sensor such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor, whose objective lens is opposed to the object in the Z-axis direction. In Embodiment 1, as shown in Figure 1, the imaging unit 40 is positioned at the tip of the support column 4, with the objective lens aligned with the condensing lens along the X-axis direction.

[0034] The imaging unit 40 acquires the image captured by the image sensor and outputs the acquired image to the control unit 100. The imaging unit 40 also images the workpiece, such as the wafer 200, held on the holding surface 11 of the holding table 10, and acquires an image for performing alignment, which involves positioning the wafer 200 with the laser beam irradiation unit 20.

[0035] The control unit 100 controls each of the above-mentioned components of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform processing operations on the wafer 200. The control unit 100 is a computer having an arithmetic processing unit with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read-only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing unit of the control unit 100 performs calculations according to the computer program stored in the storage device and outputs control signals for controlling the laser processing apparatus 1 to the above-mentioned components of the laser processing apparatus 1 via the input / output interface device, thereby realizing the function of the control unit 100.

[0036] Furthermore, the laser processing apparatus 1 includes a display unit 110, which is a display means consisting of a liquid crystal display device that displays the status of processing operations and images, and an input unit, which is an input means used by the operator to input processing conditions and the like. The display unit 110 and the input unit are connected to the control unit 100. The input unit consists of at least one of a touch panel provided on the display unit 61 and an external input device such as a keyboard.

[0037] The laser processing apparatus 1 with the configuration described above performs laser processing on a workpiece such as a wafer 200 while maintaining the apparatus state (for example, the focal position of the laser beam irradiation unit 20, the output of the laser beam 21, and the beam shape of the laser beam 21 irradiated by the laser beam irradiation unit 20) in a normal state.

[0038] In Embodiment 1, during laser processing, the laser processing apparatus 1 moves the wafer 200 and the focal point of the laser beam 21 relative to each other using the galvanometer scanner of the laser beam irradiation unit 20. That is, during laser processing, the laser processing apparatus 1 fixes the position of the wafer 200 without driving the X-axis movement unit 31 and the Y-axis movement unit 32, and performs lift-off processing by scanning the laser beam 21 with the galvanometer scanner. Furthermore, when loading or unloading the wafer 200, the laser processing apparatus 1 drives the X-axis movement unit 31 and the Y-axis movement unit 32 to move the holding table 10 in the X-axis and Y-axis directions.

[0039] (Inspection method for laser processing equipment) Next, the inspection method for a laser processing apparatus according to Embodiment 1 of the present invention will be described based on the drawings. Figure 2 is a flowchart showing the flow of the inspection method for a laser processing apparatus according to Embodiment 1. The inspection method for a laser processing apparatus according to Embodiment 1 is a method for confirming whether the state of the laser processing apparatus 1 with the above-described configuration is normal and suitable for laser processing of a workpiece such as a wafer 200. As shown in Figure 2, the inspection method for a laser processing apparatus according to Embodiment 1 comprises a preparation step 1001, a superposition processing step 1002, and a determination step 1003.

[0040] (Preparation Steps) Figure 3 is a schematic perspective view showing the preparation steps of the inspection method for the laser processing apparatus shown in Figure 2. Figure 4 is a diagram showing the surface of the reference workpiece prepared in the preparation steps of the inspection method for the laser processing apparatus shown in Figure 2. Preparation step 1001 is a step in which a reference workpiece 301 (shown in Figure 3) is prepared by irradiating the workpiece 300 (shown in Figure 3) with a laser beam 21 using the laser processing apparatus 1 in a normal state, thereby forming a regular processing pattern 303 on the surface 302 of the workpiece 300. Preparation step 1001 is performed by the laser processing apparatus 1-1 (hereinafter referred to as reference numeral 1-1) in a normal state. Note that the laser processing apparatus 1-1 in a normal state is the same as the laser processing apparatus 1 in terms of configuration, only the device state is normal, so the same reference numerals are used for the same parts and their explanation is omitted.

[0041] In Embodiment 1, in preparation step 1001, the control unit 100 of the laser processing apparatus 1-1 in a normal state receives and registers the inspection conditions etc. input by the operator, and the back surface 304 side of the workpiece 300 is placed on the holding surface 11 of the holding table 10 located in the loading / unloading area. In Embodiment 1, the workpiece 300 is ablated by being irradiated with a laser beam 21 by the laser beam irradiation unit 20, and processing grooves as processing marks 305 are formed on the surface 302.

[0042] In other words, in Embodiment 1, the workpiece 300 has absorbent properties that absorb the laser beam 21 irradiated by the laser beam irradiation unit 20. Since the workpiece 300 has absorbent properties that absorb the laser beam 21, a focal point is positioned on the surface 302 and the laser beam 21 is irradiated there, forming a processing groove as a processing mark 305.

[0043] The machining marks 305 formed on the workpiece 300 are formed regularly in multiple locations on the workpiece 300, constituting a machining pattern 303.

[0044] Furthermore, the inspection conditions include the relative movement path and speed of the focal point of the laser beam 21 relative to the holding table 10 for forming a processing pattern 303 on the surface 302 of the workpiece 300, the Z-axis position of the focal point of the laser beam 21 irradiated by the laser beam irradiation unit 20, the repetition frequency and pulse width, etc. In Embodiment 1, the inspection conditions are such that the relative movement path of the laser beam irradiation unit 20 relative to the holding table 10 is spiral-shaped, gradually moving away from the center of the surface 302 of the workpiece 300 held on the holding table 10 while rotating around the center.

[0045] In Embodiment 1, the inspection conditions are such that the circumferential lengths of the multiple processing marks 305 constituting the processing pattern 303 are equal, the distances between adjacent processing marks 305 in the circumferential direction are equal, and the distances between adjacent processing marks 305 in the radial direction gradually increase towards the outer circumference, thereby forming a processing pattern 303 in which the processing marks 305 are arranged in a spiral (or vortex) pattern in a circular processing pattern formation region 306 in the center of the surface 302 of the workpiece 300. Thus, the processing pattern 303 is formed by arranging multiple processing marks 305 regularly as described above. In addition, in the present invention, the inspection conditions may also be conditions in which the circumferential lengths of the multiple processing marks 305 constituting the processing pattern 303 are equal, the distances between adjacent processing marks 305 in the circumferential direction are equal, and the distances between adjacent processing marks 305 in the radial direction are equal, thereby forming a processing pattern 303 in which the processing marks 305 are arranged in a spiral shape in the circular processing pattern forming region 306 in the center of the surface 302 of the workpiece 300.

[0046] In Embodiment 1, during preparation step 1001, when the control unit 100 receives an instruction from the operator to start an inspection operation, the laser processing apparatus 1-1, in a normal state, uses suction to hold the workpiece 300 on the holding surface 11 of the holding table 10. In Embodiment 1, during preparation step 1001, the control unit 100 of the laser processing apparatus 1-1, in a normal state, controls the movement unit 30 to move the holding table 10 to the processing area, and the imaging unit 40 images the workpiece 300 held by suction on the holding table 10 to perform alignment, aligning the workpiece 300 with the laser beam irradiation unit 20.

[0047] In Embodiment 1, in preparation step 1001, the control unit 100 of the laser processing apparatus 1-1 in a normal state controls the laser beam irradiation unit 20 and the moving unit 30, etc., and irradiates the surface 302 of the workpiece 300 with the laser beam 21 according to the inspection conditions, as shown in Figure 3, and forms a processing pattern 303 in the processing pattern formation region 306 of the surface 302 of the workpiece 300, as shown in Figures 3 and 4.

[0048] Thus, in Embodiment 1, in preparation step 1001, a reference workpiece 301 (shown in Figure 4) is prepared by forming a processing pattern 303 on the processing pattern formation area 306 of the surface 302 using the laser processing apparatus 1-1 in a normal state. In preparation step 1001, when the control unit 100 of the laser processing apparatus 1-1 in a normal state forms the processing pattern 303 on the processing pattern formation area 306 of the surface 302, the holding table 10 is positioned in the loading / unloading area, and the suction holding of the reference workpiece 301 by the holding table 10 is stopped. Hereafter, identical parts of the workpiece 300 and the reference workpiece 301 are denoted by the same reference numerals and their descriptions are omitted.

[0049] (Overlay processing step) Figure 5 is a schematic perspective view showing the overlapping processing step of the inspection method for the laser processing apparatus shown in Figure 2. The overlapping processing step 1002 is a step in which a laser beam 21 is irradiated onto a reference workpiece 301 using the actual laser processing apparatus 1, thereby superimposing the regular processing pattern 303 onto the processing pattern 303 formed on the surface 302 of the reference workpiece 301.

[0050] In Embodiment 1, the overlapping processing step 1002 is performed by a laser processing device 1-2 (hereinafter referred to as reference numeral 1-2) that is the subject of inspection and laser processing a workpiece such as a wafer 200. The laser processing device 1-2 that is the subject of inspection is the same model as the laser processing device 1-1 in a normal state in which a processing pattern 303 has been formed on a reference workpiece 301. Furthermore, the laser processing device 1-2 that is the subject of inspection is only the object whose state of operation is to be confirmed, and its configuration is the same as that of laser processing devices 1 and 1-1, so the same reference numerals are used for the same parts and their description is omitted.

[0051] The laser processing device 1-2 under inspection performs the overlapping processing step 1002 at predetermined timings. The predetermined timings are the timing each time the laser processing device 1-2 laser processes a predetermined number of workpieces such as wafers 200, or the timing at which a processing defect occurs in the processing result of the laser processing device 1.

[0052] In Embodiment 1, during the overlapping processing step 1002, the control unit 100 of the laser processing device 1-2 to be inspected receives and registers the same inspection conditions as those entered by the operator in the preparation step 1001, and the back surface 304 of the reference workpiece 301 is placed on the holding surface 11 of the holding table 10 located in the loading / unloading area. In Embodiment 1, during the overlapping processing step 1002, when the control unit 100 receives an instruction from the operator to start the inspection operation, the laser processing device 1-2 to be inspected uses suction to hold the reference workpiece 301 on the holding surface 11 of the holding table 10.

[0053] In Embodiment 1, during the overlapping processing step 1002, the control unit 100 of the laser processing apparatus 1-2 under inspection controls the movement unit 30 to move the holding table 10 to the processing area, and the imaging unit 40 images the reference workpiece 301 held by suction on the holding table 10 to perform alignment to position the reference workpiece 301 and the laser beam irradiation unit 20. In Embodiment 1, during the overlapping processing step 1002, the control unit 100 of the laser processing apparatus 1-2 under inspection controls the laser beam irradiation unit 20 and the movement unit 30, etc., and as shown in Figure 5, irradiates the processing pattern formation area 306 of the surface 302 of the reference workpiece 301 with the laser beam 21 according to the inspection conditions to form a new processing pattern 303 on top of the processing pattern 303 of the processing pattern formation area 306 of the surface 302 of the reference workpiece 301.

[0054] The processing pattern 303 newly formed in the overlapping processing step 1002 is the same as the processing pattern 303 formed on the reference workpiece 301 in the preparation step 1001. These processing patterns 303 have multiple processing marks 305 arranged regularly, so when the processing marks 305 overlap, moiré patterns 307 (shown in Figure 6) are not generated on the surface 302 of the reference workpiece 301, but when the processing marks 305 are misaligned, moiré patterns 307 are generated on the surface 302 of the reference workpiece 301.

[0055] In the overlapping processing step 1002, when the control unit 100 of the laser processing device 1-2 under inspection overlaps and forms the processing pattern 303 on the processing pattern formation area 306 of the surface 302, the holding table 10 is positioned in the loading / unloading area, and the suction holding of the reference workpiece 301 by the holding table 10 is stopped.

[0056] (Decision-making step) Figure 6 shows an example of the surface of a reference workpiece judged in the judgment step of the inspection method for the laser processing apparatus shown in Figure 2. Figure 7 shows another example of the surface of a reference workpiece judged in the judgment step of the inspection method for the laser processing apparatus shown in Figure 2.

[0057] The determination step 1003 is a step in which, if moiré patterns 307 (shown in Figure 6, also called interference fringes) are not present on the surface 302 of the reference workpiece 301 that has undergone overlapping processing, it is determined that the laser processing device 1-2 under inspection has not changed from a normal state, and if moiré patterns 307 are present, it is determined that the laser processing device 1-2 under inspection has changed from a normal state.

[0058] In Embodiment 1, in the determination step 1003, the operator visually inspects the processing pattern formation region 306 on the surface 302 of the reference workpiece 301, where the processing pattern 303 was formed by the laser processing device 1-2 to be inspected in the overlapping processing step 1002. In Embodiment 1, in the determination step 1003, the operator determines whether or not a moiré pattern 307 exists in the processing pattern formation region 306 on the surface 302 of the reference workpiece 301 that was visually inspected.

[0059] In Embodiment 1, in the determination step 1003, if the operator determines that moiré 307 exists in the processing pattern formation area 306 of the surface 302 of the reference workpiece 301 as seen by the operator, as shown in Figure 6, then the laser processing device 1-2 under inspection is determined to have changed from a normal state and is unsuitable for laser processing of workpieces such as wafers 200. In Embodiment 1, in the determination step 1003, if the operator determines that moiré 307 does not exist in the processing pattern formation area 306 of the surface 302 of the reference workpiece 301 as seen by the operator, as shown in Figure 7, then the laser processing device 1-2 under inspection is determined to have maintained a normal state and is suitable for laser processing of workpieces such as wafers 200.

[0060] In the laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 1 described above, in preparation step 1001, a reference workpiece 301 is prepared using the laser processing apparatus 1-1 in a normal state, on which a processing pattern 303 is formed in which processing marks 305 are regularly arranged on the workpiece 300. Then, in the superimposing processing step 1002, the laser processing apparatus 1-2 to be inspected performs the same laser processing on the reference workpiece 301 as in preparation step 1001, and in judgment step 1003, it is determined whether or not moiré 307 is present on the surface 302 of the reference workpiece 301.

[0061] For this reason, in the laser processing apparatus 1 and the inspection method for the laser processing apparatus according to Embodiment 1, if the device condition of the laser processing apparatus 1-2 to be inspected is normal, the processing marks 305 of the processing pattern 303 do not overlap and moiré 307 does not occur, so it can be determined that the device condition is normal and laser processing of the workpiece such as the wafer 200 of the laser processing apparatus 1-2 to be inspected can be started immediately.

[0062] Furthermore, in the laser processing apparatus 1 and the inspection method for the laser processing apparatus according to Embodiment 1, if there is any change from the normal state of the laser processing apparatus 1-2 to be inspected (for example, an increase or decrease in the output of the laser beam 21 or a change in the shape of the laser beam 21), moiré patterns 307 will be generated due to the misalignment of the processing marks 305, so it can be determined that the apparatus is not in a normal state, and it becomes possible to notify the laser processing apparatus 1-2 to be inspected to perform detailed confirmation, inspection, adjustment, etc.

[0063] As a result, the laser processing apparatus 1 and the inspection method for the laser processing apparatus according to Embodiment 1 make it possible to easily check the status of the apparatus, eliminating the need for skilled work to check the status of the apparatus, and also reducing the maintenance man-hours for the laser processing apparatus 1-2 being inspected.

[0064] [Embodiment 2] A laser processing apparatus and an inspection method for the laser processing apparatus according to Embodiment 2 will be described based on the drawings. Figure 8 is a schematic perspective view showing an example of the configuration of the laser processing apparatus according to Embodiment 2. Figure 9 is a diagram showing a reference pattern image stored in the memory unit of the laser processing apparatus shown in Figure 8. Figure 10 is a diagram showing an example of a superimposed image formed in the image processing unit of the laser processing apparatus shown in Figure 8. Figure 11 is a diagram showing another example of a superimposed image formed in the image processing unit of the laser processing apparatus shown in Figure 8. Figure 12 is a flowchart showing the flow of the inspection method for the laser processing apparatus according to Embodiment 2.

[0065] Note that in Figure 8, the same reference numerals are used for the same parts as in Embodiment 1, and their descriptions are omitted. The laser processing apparatus 1-2 to be inspected according to Embodiment 2 has the same configuration as the laser processing apparatuses 1, 1-1, and 1-2 according to Embodiment 1, except that the control unit 100 comprises a storage unit 101 and an image processing unit 102, as shown in Figure 8.

[0066] In Embodiment 2, the storage unit 101 of the control unit 100 of the laser processing apparatus 1-2 to be inspected irradiates a reference workpiece 300 with a laser beam 21 using the laser processing apparatus 1-1 in a normal state to capture an image of the regular processing pattern 303 formed on the surface 302 of the workpiece 300, and stores it in advance as a reference pattern image 401 (shown in Figure 9). In Embodiment 2, the storage unit 101 of the control unit 100 of the laser processing apparatus 1-2 to be inspected stores an image obtained by capturing an area including the processing pattern formation region 306 on the surface 302 of the reference workpiece 301, which was prepared in the preparation step 1001 of Embodiment 1, with the imaging unit 40, as the reference pattern image 401. The reference pattern image 401 is a grayscale image in which the brightness of each pixel is defined by multiple levels of gradation (for example, 256 levels).

[0067] The image processing unit 102 uses the actual laser processing apparatus 1 to irradiate the workpiece 300 with a laser beam 21, thereby capturing an image of the regular processing pattern 303 formed on the surface 302 of the workpiece 300. The captured image and the reference pattern image 401 are then superimposed to form a superimposed image 402 (shown in Figures 10 and 11). In Embodiment 2, the image processing unit 102 of the control unit 100 of the laser processing apparatus 1-2 under inspection captures an image obtained by the imaging unit 40 of the area including the processing pattern formation region 306 of the surface 302 of a workpiece 300 that is different from the reference workpiece 301 held on the holding surface 11 of the holding table 10, and where the processing pattern 303 has been formed by the laser beam 21, and superimposes this image with the reference pattern image 401 to form a superimposed image 402.

[0068] The image captured by the imaging unit 40 and the superimposed image 402 are both grayscale images in which the brightness of each pixel is defined by multiple gradations (for example, 256 gradations). Furthermore, the workpiece 300 is made of the same material as the reference workpiece 301.

[0069] In Embodiment 2, the image processing unit 102 superimposes the image obtained by the imaging unit 40 with the images of pixels of the same location on the workpiece 300, 301 of the reference pattern image 401. In Embodiment 2, the image processing unit 102 displays the formed superimposed image 402 on the display unit 110. The functions of the storage unit 101 are realized by the storage device described above. The functions of the image processing unit 102 are realized by the arithmetic processing unit performing arithmetic processing according to the computer program stored in the storage device.

[0070] The inspection method for a laser processing apparatus according to Embodiment 2 is a method performed by the laser processing apparatus 1-2 to be inspected to confirm the status of the laser processing apparatus 1-2 itself. As shown in Figure 12, the inspection method for a laser processing apparatus according to Embodiment 2 comprises a storage step 2001 and an image processing step 2002. The storage step 2001 is a step of storing a reference pattern image 401 in the storage unit 101. For example, the storage step 2001 is performed before the laser processing apparatus 1-2 to be inspected laser processes a workpiece such as a wafer 200.

[0071] In memory step 2001, the laser processing apparatus 1-2 to be inspected is placed on the holding surface 11 of the holding table 10, where the back surface 304 side of the reference workpiece 301, which has a processing pattern 303 formed on the processing pattern forming area 306 of the surface 302, is located in the loading / unloading area, similar to the preparation step 1001 of the inspection method for the laser processing apparatus according to Embodiment 1. In memory step 2001, when the control unit 100 receives a start instruction for memory step 2001 from the operator, the laser processing apparatus 1-2 to be inspected is held by suction on the holding surface 11 of the holding table 10.

[0072] In Embodiment 2, during the storage step 2001, the control unit 100 of the laser processing apparatus 1-2 under inspection controls the movement unit 30 to move the holding table 10 to the processing area, and the imaging unit 40 images the area including the processing pattern formation area 306 on the surface 302 of the reference workpiece 301 held by suction on the holding table 10 to acquire a reference pattern image 401 as illustrated in Figure 9, and stores the acquired reference pattern image in the storage unit 101. During the storage step 2001, once the control unit 100 of the laser processing apparatus 1-2 under inspection has stored the reference pattern image 401 in the storage unit 101, it positions the holding table 10 in the loading / unloading area and stops the suction holding of the reference workpiece 301 by the holding table 10.

[0073] The image processing step 2002 is performed by the laser processing device 1-2 under inspection at predetermined timings. These predetermined timings include the timing each time the laser processing device 1-2 laser processes a predetermined number of workpieces such as wafers 200, or the timing at which a processing defect occurs in the processing result of the laser processing device 1.

[0074] In Embodiment 2, during the image processing step 2002, the control unit 100 of the laser processing apparatus 1-2 to be inspected receives and registers inspection conditions identical to those input by the operator for forming a processing pattern 303 on a reference workpiece 301. The back surface 304 of a workpiece 300, which is different from the reference workpiece 301, is then placed on the holding surface 11 of the holding table 10, which is located in the loading / unloading area. In Embodiment 2, during the image processing step 2002, when the control unit 100 receives the instruction from the operator to start the image processing step 2002, the laser processing apparatus 1-2 to be inspected uses suction to hold the workpiece 300 on the holding surface 11 of the holding table 10.

[0075] In Embodiment 2, in the image processing step 2002, the image processing unit 102 of the control unit 100 of the laser processing apparatus 1-2 under inspection controls the movement unit 30 to move the holding table 10 to the processing area, and the imaging unit 40 images the workpiece 300 held by suction on the holding table 10 to perform alignment to position the workpiece 300 and the laser beam irradiation unit 20. In Embodiment 2, in the image processing step 2002, the image processing unit 102 of the control unit 100 of the laser processing apparatus 1-2 under inspection controls the laser beam irradiation unit 20 and the movement unit 30, etc. to irradiate the processing pattern formation area 306 on the surface 302 of the workpiece 300 with the laser beam 21 according to the inspection conditions, and form a processing pattern 303 on the processing pattern formation area 306 on the surface 302 of the workpiece 300. The processing pattern 303 formed in the image processing step 2002 is the same as the processing pattern 303 formed on the reference workpiece 301.

[0076] In the image processing step 2002, when the image processing unit 102 of the control unit 100 of the laser processing apparatus 1-2 under inspection forms a processing pattern 303 in the processing pattern formation region 306 of the surface 302 of the workpiece 300, the imaging unit 40 images the area of ​​the surface 302 of the workpiece 300 that includes the processing pattern formation region 306 where the processing pattern 303 is formed. In the image processing step 2002, the image acquired by the imaging unit 40 from the area of ​​the workpiece 300 that includes the processing pattern formation region 306 where the processing pattern 303 is formed, captured by the image processing unit 102 of the laser processing apparatus 1-2 under inspection, is superimposed with the reference pattern image 401 to form the superimposed image 402 shown in Figures 10 and 11.

[0077] In the image processing step 2002, the image processing unit 102 of the control unit 100 of the laser processing apparatus 1-2 under inspection displays the superimposed image 402 on the display unit 110. The superimposed image 402 is created by combining the image captured and acquired by the imaging unit 40 with the processing pattern 303 of the reference pattern image 401, in which multiple processing marks 305 are arranged regularly. Therefore, when the processing marks 305 overlap, no moiré pattern 307 is generated, but when the processing marks 305 are misaligned, a moiré pattern 307 is generated.

[0078] Furthermore, when the image processing unit 102 of the control unit 100 of the laser processing machine 1-2 to be inspected displays the superimposed image 402 on the display unit 110, the control unit 100 positions the holding table 10 in the loading / unloading area and stops the suction holding of the reference workpiece 301 on the holding table 10. In addition, the operator visually confirms the superimposed image 402 displayed on the display unit 110 and confirms the status of the laser processing machine 1-2 to be inspected, similar to the judgment step 1003 of Embodiment 1.

[0079] The laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 2 involve using the laser processing apparatus 1-1 in a normal state to image a reference workpiece 301 on which a processing pattern 303 with regularly arranged processing marks 305 has been formed, and storing the acquired reference pattern image 401 in the storage unit 101. In the image processing step 2002 of the laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 2, the same processing pattern 303 as the reference workpiece 301 is formed on a workpiece 300 different from the reference workpiece 301, and an image acquired by imaging unit 40 is captured, and a superimposed image 402 is formed by superimposing the reference pattern image 401.

[0080] For this reason, the laser processing apparatus 1 and the inspection method for the laser processing apparatus according to Embodiment 2 can confirm the device status of the laser processing apparatus 1-2 to be inspected by checking whether or not moiré 307 is present in the superimposed image 402. As a result, the laser processing apparatus 1 and the inspection method for the laser processing apparatus according to Embodiment 2 have the effect of making it possible to easily confirm the device status.

[0081] [Embodiment 3] A laser processing apparatus and an inspection method for the laser processing apparatus according to Embodiment 3 will be described based on the drawings. Figure 13 is a schematic perspective view showing an example of the configuration of the laser processing apparatus according to Embodiment 3. Figure 14 is a flowchart showing the flow of the inspection method for the laser processing apparatus according to Embodiment 3. Note that in Figures 13 and 14, the same reference numerals are used for the same parts as in Embodiments 1 and 2, and their descriptions are omitted.

[0082] The laser processing apparatus 1-2 to be inspected according to Embodiment 3 has the same configuration as the laser processing apparatus 1-2 to be inspected according to Embodiment 2, except that the control unit 100 includes a determination unit 103, as shown in Figure 13. The determination unit 103 of the control unit 100 of the laser processing apparatus 1-2 to be inspected according to Embodiment 3 determines that the laser processing apparatus 1-2 has not changed from a normal state if there is no moiré 307 in the superimposed image 402 formed by the image processing unit 102, and determines that the laser processing apparatus 1-2 has changed from a normal state if there is moiré 307. The function of the determination unit 103 is realized by the arithmetic processing unit performing calculation processing according to a computer program stored in the memory device.

[0083] The inspection method for a laser processing apparatus according to Embodiment 3 is a method performed by the laser processing apparatus 1-2 to be inspected to confirm the device status of the laser processing apparatus 1-2 itself. Similar to Embodiment 2, the inspection method for a laser processing apparatus according to Embodiment 3 comprises a storage step 2001 and an image processing step 2002, as shown in Figure 14, and further comprises a determination step 2003. In the image processing step 2002 of the inspection method for a laser processing apparatus according to Embodiment 3, the superimposed image 402 formed by the image processing unit 102 may or may not be displayed on the display unit 110.

[0084] The determination step 2003 is a step in which the laser processing device 1-2 to be inspected is determined to be in a normal state based on the superimposed image 402. In Embodiment 3, in the determination step 2003, the determination unit 103 of the control unit 100 of the laser processing device 1-2 to be inspected extracts the pixel with the highest brightness and the pixel with the lowest brightness from the pixels of the superimposed image 402, and calculates the difference in brightness between these pixels.

[0085] In Embodiment 3, in the determination step 2003, the determination unit 103 of the control unit 100 of the laser processing apparatus 1-2 under inspection determines whether the calculated difference in brightness is greater than or equal to a predetermined value. In Embodiment 3, in the determination step 2003, if the determination unit 103 of the control unit 100 of the laser processing apparatus 1-2 under inspection determines that the calculated difference in brightness is greater than or equal to a predetermined value, it determines that moiré 307 has occurred in the superimposed image 402, and determines that the laser processing apparatus 1-2 under inspection has changed from a normal state and is unsuitable for laser processing of workpieces such as wafers 200.

[0086] In Embodiment 3, in the determination step 2003, if the determination unit 103 of the control unit 100 of the laser processing apparatus 1-2 under inspection determines that the calculated brightness difference is not greater than or equal to a predetermined value (i.e., less than a predetermined value), it determines that no moiré pattern 307 is present in the superimposed image 402, and determines that the laser processing apparatus 1-2 under inspection maintains a normal state and is suitable for laser processing of workpieces such as wafers 200. In Embodiment 3, in the determination step 2003, the determination unit 103 of the control unit 100 of the laser processing apparatus 1-2 under inspection displays the determination result on the display unit 110.

[0087] The laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 3 involve using the laser processing apparatus 1-1 in a normal state to image a reference workpiece 301 on which a processing pattern 303 with regularly arranged processing marks 305 has been formed, and storing the acquired reference pattern image 401 in the storage unit 101. In the image processing step 2002 of the laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 3, the same processing pattern 303 as the reference workpiece 301 is formed on a workpiece 300 different from the reference workpiece 301, and an image acquired by imaging unit 40 is captured, and a superimposed image 402 is formed by superimposing the reference pattern image 401.

[0088] In the laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 3, in the judgment step 2003, a determination is made as to whether or not the apparatus is in a normal state based on the superimposed image 402, so the state of the laser processing apparatus 1-2 to be inspected can be confirmed. As a result, the laser processing apparatus 1 and inspection method for the laser processing apparatus according to Embodiment 3 have the effect of making it possible to easily confirm the state of the apparatus.

[0089] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. For example, in the present invention, the processing pattern 303 is not limited to arranging the processing marks 305 regularly in a coiled shape, but may also be arranged in various regular patterns. [Explanation of symbols]

[0090] 1. Laser processing device 1-1 Laser processing machine in normal working order (Laser processing machine in normal working order) 1-2 Laser processing equipment to be inspected (actual laser processing equipment) 10 Retention Table 20 Laser beam irradiation unit 21 Laser beam 40 Imaging Units 100 control units 101 Storage section 102 Image Processing Unit 103 Judgment Department 300 Workpiece 301 Reference workpiece 302 Surface 303 Processing Pattern 307 Moire 401 Reference Pattern Image 1001 Preparation Steps 1002 Overlay processing step 1003 Decision Step

Claims

1. A method for inspecting a laser processing device, A preparation step involves preparing a reference workpiece in which a regular processing pattern is formed on the surface of the workpiece by irradiating the workpiece with a laser beam using a laser processing device in normal working order. A superimposing step involves irradiating the reference workpiece with a laser beam using an actual laser processing device to form a regular processing pattern on top of a processing pattern formed on the surface of the reference workpiece, If no moiré patterns (interference fringes) are present in the reference workpiece that has undergone overlapping processing, it is determined that the laser processing device has not changed from its normal state. If moiré patterns (interference fringes) are present, it is determined that the laser processing device has changed from its normal state. A method for inspecting a laser processing apparatus, characterized by comprising the following features.

2. A laser processing device, A holding table for holding the workpiece, A laser beam irradiation unit that irradiates a workpiece held on the holding table with a laser beam to perform processing, An imaging unit for imaging the workpiece, It comprises a control unit that controls each component, The control unit is, A storage unit that, using a laser processing device in a normal state, irradiates a reference workpiece with a laser beam to capture a regular processing pattern formed on the surface of the workpiece and stores it in advance as a reference pattern image. The system includes an image processing unit that, by irradiating a workpiece with a laser beam using the actual laser processing unit under the same conditions as the normal laser processing unit formed the regular processing pattern, captures the regular processing pattern formed on the surface of the workpiece, and superimposes the pixels of the captured image and the reference pattern image that capture the same location on the workpiece, thereby forming a superimposed image that generates a moiré pattern when the processing marks of the processing pattern formed by the normal laser processing unit and the actual laser processing unit are misaligned. A laser processing apparatus characterized by comprising a display unit that displays a superimposed image formed by the image processing unit.

3. A laser processing device, A holding table for holding the workpiece, A laser beam irradiation unit that irradiates a workpiece held on the holding table with a laser beam to perform processing, An imaging unit for imaging the workpiece, It comprises a control unit that controls each component, The control unit is, A storage unit that, using a laser processing device in a normal state, irradiates a reference workpiece with a laser beam to capture a regular processing pattern formed on the surface of the workpiece and stores it in advance as a reference pattern image. An image processing unit that, by irradiating a workpiece with a laser beam using the actual laser processing unit under the same conditions as when the normal laser processing unit formed the regular processing pattern, captures the regular processing pattern formed on the surface of the workpiece, and superimposes the captured image and the pixels of the reference pattern image that capture the same location on the workpiece to form a superimposed image that generates a moiré pattern when the processing marks of the processing pattern formed by the normal laser processing unit and the actual laser processing unit are misaligned. A determination unit determines that if no moiré patterns (interference fringes) are present in the superimposed image formed by the image processing unit, the laser processing device has not changed from its normal state, and if moiré patterns (interference fringes) are present, the laser processing device has changed from its normal state. A laser processing apparatus characterized by comprising the following features.

4. The laser processing apparatus according to claim 3, wherein the determination unit extracts the pixel with the highest brightness and the pixel with the lowest brightness from the pixels of the superimposed image, and determines whether the laser processing apparatus has changed from a normal state based on the difference in brightness of these pixels.

Images