Processing apparatus, microscope, three dimensional image generation method, and workpiece processing method

Abstract

To improve productivity when generating a three dimensional image of the inside of a workpiece.SOLUTION: The processing apparatus includes the holding unit that holds the workpiece 200, the laser beam irradiation unit that performs laser processing of the workpiece 200, and the microscope 50 that observes the workpiece 200, and the microscope 50 includes the light receiving element 51, the first lens 61 that condenses light from the inside of the workpiece 200, the second lens 62 that condenses the light condensed by the first lens 61 and forms the intermediate image 66, and the imaging optical system 80 that forms an image of the light from the intermediate image 66 on the light receiving element 51. The imaging optical system 80 has an optical axis inclined with respect to the optical axis of the second lens 62 and forms an image of the inclined face in the inside of the workpiece 200 inclined in a direction not orthogonal to the optical axis of the second lens 62 in the intermediate image 66 on the light receiving element 51.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a processing device, a microscope, a method for generating a three-dimensional image, and a method for processing a workpiece. [Background technology]

[0002] One method for dividing a workpiece such as a semiconductor wafer involves positioning the focal point of a laser beam with a wavelength that is transparent to the workpiece inside the workpiece and irradiating it, thereby forming a modified layer inside the workpiece, and dividing the workpiece using the formed modified layer as the starting point (see, for example, Patent Document 1).

[0003] In the method of Patent Document 1, it is known that the position and length of the modified layer are correlated with the divisibility of the workpiece, and by understanding information such as the position and length of the modified layer, it is possible to determine whether a modified layer optimal for divisibility has been formed.

[0004] Therefore, a processing device has been proposed that allows the modified layer formed inside the workpiece to be observed before the workpiece is divided (see, for example, Patent Document 2).

[0005] The processing device of Patent Document 2 performs an image acquisition process in which an objective lens is intermittently moved at predetermined intervals in the Z-axis direction perpendicular to the XY plane, and acquires and records XY plane images of the interior of the wafer for each of a plurality of Z-axis coordinate values, and generates a three-dimensional image at the captured position from the recorded XY plane images for each of the plurality of Z-axis coordinate values. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3408805 [Patent Document 2] Japanese Patent Application Publication No. 2019-140167 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in order to generate a three-dimensional image of the interior of a certain region of the workpiece using the method of Patent Document 2, it is necessary to repeat a process of generating a three-dimensional image by moving the objective lens in the Z-axis direction while the objective lens is positioned so that a predetermined XY position can be imaged, and an XY movement process of moving the objective lens so that an XY position different from the position already imaged can be imaged, leaving room for improvement in productivity.

[0008] The present invention has been made in view of the above problems, and has as its object to improve productivity when generating a three-dimensional image of the inside of a workpiece. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the processing apparatus of the present invention comprises a holding unit for holding a workpiece, a processing unit for processing the workpiece, and a microscope for observing the workpiece, wherein the microscope has a light receiving element, a first lens for collecting light from inside the workpiece, a second lens for collecting the light collected by the first lens to form an intermediate image, and an imaging optical system for imaging the light from the intermediate image onto the light receiving element, wherein the imaging optical system has an optical axis that is inclined with respect to the optical axis of the second lens, and images an inclined surface in the intermediate image that is inclined in a direction that is not perpendicular to the optical axis of the second lens onto the light receiving element.

[0010] The processing apparatus may further include a moving unit that moves the microscope and the holding unit relatively along a moving direction that intersects with the optical axis direction of the first lens, and a controller that controls the processing apparatus, wherein the microscope images a slope inside the workpiece that is inclined in a direction that is not perpendicular to the optical axis direction via the slope of the intermediate image, and the controller moves the microscope and the holding unit relatively to each other to image the slope multiple times, and generates a three-dimensional image of the inside of the workpiece from the multiple images obtained.

[0011] The processing device may further include a diffraction grating that is disposed at a position of the intermediate image and diffracts the light from the second lens and guides it to the imaging optical system.

[0012] In the processing device, the refractive index of the workpiece may be n, and the optical magnification of the intermediate image may be M, so that the following relational expression may be satisfied:

[0013] |Mn|≦n×0.1

[0014] The processing apparatus may further include a height correction unit that keeps a constant distance between the first lens and the holding surface of the holding unit or the workpiece.

[0015] The microscope of the present invention is a microscope for observing an object, and comprises a light receiving element, a first lens that receives light from the object, a second lens that collects the light that has passed through the first lens and forms an intermediate image of optical magnification M that satisfies the following relational expression, where n is the refractive index of the object, an imaging optical system that focuses the light from the intermediate image on the light receiving element, and a diffraction grating that is disposed at the position of the intermediate image and diffracts the light from the second lens and directs it to the imaging optical system, wherein the imaging optical system has an optical axis that is inclined with respect to the optical axis of the second lens, and focuses an inclined surface in the intermediate image that is inclined in a direction that is not perpendicular to the optical axis of the second lens on the light receiving element, and the diffraction grating is disposed so that its normal is parallel to the optical axis of the imaging optical system.

[0016] |Mn|≦n×0.1

[0017] The three-dimensional image generating method of the present invention is a three-dimensional image generating method for generating a three-dimensional image of the interior of an object using the microscope, and is characterized by comprising: a moving step for relatively moving the microscope and the object along a moving direction intersecting the optical axis direction of the first lens; an imaging step for using the microscope to image a slope inside the object that is inclined in a direction not perpendicular to the optical axis direction via the slope of the intermediate image; and a generating step for generating a three-dimensional image of the interior of the object from multiple images obtained by repeating the moving step and the imaging step.

[0018] The method for processing a workpiece of the present invention is a method for processing a workpiece using the processing device, wherein the processing unit includes a laser oscillator that emits a laser beam of a wavelength that is transparent to the workpiece, and a condenser that condenses the laser beam, and is characterized by comprising: a holding step for holding the workpiece with the holding unit; a modified layer forming step for positioning the focal point of the laser beam inside the workpiece and irradiating the workpiece with the laser beam to form a modified layer inside the workpiece; a moving step for relatively moving the microscope and the workpiece on which the modified layer has been formed along a moving direction that intersects with the optical axis direction of the first lens; an imaging step for using the microscope to image, via the inclined surface of the intermediate image, an inclined surface inside the workpiece that is inclined in a direction that is not perpendicular to the optical axis direction; and a generation step for generating a three-dimensional image of the area inside the workpiece that includes the modified layer from a plurality of images obtained by repeating the moving step and the imaging step. [Effects of the Invention]

[0019] The present invention has an effect of improving productivity when generating a three-dimensional image of the inside of a workpiece. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a processing device according to the first embodiment. [Figure 2]FIG. 2 is a diagram schematically illustrating the configuration of a microscope of the processing apparatus shown in FIG. [Figure 3] FIG. 3 is a side view schematically showing the first lens of the microscope shown in FIG. 2 and the internal slope of the workpiece to be imaged. [Figure 4] FIG. 4 is a diagram showing a schematic diagram of the second lens and the coupling optical system of the microscope shown in FIG. [Figure 5] FIG. 5 is a flowchart showing the flow of the method for processing a workpiece according to the first embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating the configuration of a microscope of the processing apparatus according to the second embodiment. [Figure 7] FIG. 7 is a side view schematically showing the first lens of the microscope shown in FIG. 6 and the internal slope of the workpiece to be imaged. [Figure 8] FIG. 8 is a diagram showing a schematic diagram of the second lens and the coupling optical system of the microscope shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] Modes (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 a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0022] [Embodiment 1] A processing device according to a first embodiment of the present invention will be described with reference to the drawings, in which: Fig. 1 is a perspective view showing an example of the configuration of the processing device according to the first embodiment.

[0023] (Workpiece) 1 according to the first embodiment is a processing apparatus that laser processes a target object, that is, a workpiece 200. The workpiece 200 that is the processing target of the processing apparatus 1 according to the first embodiment is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with a substrate 201 made of, for example, silicon, sapphire, gallium, SiC, or the like.

[0024] 1, the workpiece 200 has a surface 202 divided into a grid pattern by a plurality of mutually intersecting planned division lines 203, and devices 204 are formed in each of the divided regions. The devices 204 are, 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), MEMS (Micro Electro Mechanical Systems), or semiconductor memories (storage devices).

[0025] In embodiment 1, the workpiece 200 has the center of a disk-shaped tape 206 with a larger diameter than the workpiece 200 attached to the back surface 205, and a ring-shaped frame 207 with an inner diameter larger than the outer diameter of the workpiece 200 attached to the outer edge of the tape 206, and is then laser processed.

[0026] (Processing equipment) Next, we will explain the processing device 1. The processing device 1 is a processing device that irradiates a workpiece 200 with a laser beam 21 to form a modified layer along a planned dividing line 203 inside a substrate 201 of the workpiece 200. As shown in Fig. 1, the processing device 1 includes a holding unit 10, a moving unit 30, a laser beam irradiation unit 20, an imaging unit (not shown), a distance measuring device 40, a microscope 50, and a controller 100.

[0027] The holding unit 10 is disk-shaped, and has a flat holding surface 11 formed of porous ceramic or the like along the horizontal direction for holding the workpiece 200. The holding unit 10 is also provided so as to be movable by a moving unit 30 between a processing area below the laser beam irradiation unit 20 and a carry-in / out area spaced from below the laser beam irradiation unit 20 where the workpiece 200 is carried in and out.

[0028] The holding unit 10 is connected to a vacuum suction source (not shown), and is sucked by the vacuum suction source to suck and hold the workpiece 200 placed on the holding surface 11. In the first embodiment, the holding unit 10 sucks and holds the back surface 205 of the workpiece 200 via tape 206 attached to the back surface 205 of the workpiece 200.

[0029] The moving unit 30 moves the holding unit 10 and the laser beam irradiation unit 20 relatively. The moving unit 30 includes a Y-axis moving unit 31 which is an indexing feed unit that moves the holding unit 10 in the Y-axis direction parallel to the horizontal direction, an X-axis moving unit 32 which is a processing feed unit that moves the holding unit 10 in the X-axis direction parallel to the horizontal direction and perpendicular to the Y-axis direction, a rotational moving unit 33 that rotates the holding unit 10 around an axis parallel to the Z-axis direction that is perpendicular to both the X-axis and Y-axis directions and parallel to the vertical direction, and a Z-axis moving unit 34 that moves the laser beam irradiation unit 20 in the Z-axis direction.

[0030] The Y-axis moving unit 31 is installed on the device main body 2, and moves the moving plate 3 on which the X-axis moving unit 32 is installed in the Y-axis direction, thereby moving the holding unit 10 in the Y-axis direction. The X-axis moving unit 32 is installed on the moving plate 3, and moves the second moving plate 4 on which the rotational moving unit 33 is installed in the X-axis direction, thereby moving the holding unit 10 in the X-axis direction.

[0031] The rotational movement unit 33 is installed on the second moving plate 4 and supports the holding unit 10, thereby rotating the holding unit 10 around its axis. The Z-axis movement unit 34 is installed on an upright wall 5 erected from the end of the device body 2 in the Y-axis direction, and moves a support column 6, which has the laser beam irradiation unit 20, the distance measuring device 40, and the microscope 50 mounted on its tip, in the Z-axis direction, thereby moving the laser beam irradiation unit 20, the distance measuring device 40, and the microscope 50 in the Z-axis direction.

[0032] The Y-axis moving unit 31 moves each moving plate 3, the X-axis moving unit 32, the second moving plate 4, the rotational moving unit 33, and the holding unit 10 in the Y-axis direction. The X-axis moving unit 32 moves each second moving plate 4, the rotational moving unit 33, and the holding unit 10 in the X-axis direction.

[0033] The Y-axis moving unit 31, the X-axis moving unit 32, and the Z-axis moving unit 34 each include a well-known ball screw rotatably mounted about its axis, a well-known motor that rotates the ball screw about its axis, and well-known guide rails that support the moving plates 3 and 4 and the support column 6 so that they can move in the Y-axis, X-axis, or Z-axis direction. The rotational moving unit 33 includes a well-known motor that rotates the holding unit 10 about its axis.

[0034] The Y-axis moving unit 31 and X-axis moving unit 32 described above are moving units that move the microscope 50 and the holding unit 10 relatively along the Y-axis direction or the X-axis direction, which are moving directions that intersect (or are perpendicular to in embodiment 1) the optical axis direction of the first lens 61 of the microscope 50, which will be described later.

[0035] 1, a part of the laser beam irradiation unit 20 is provided at the tip of the support column 6. The laser beam irradiation unit 20 is a processing unit that irradiates a laser beam 21 onto a workpiece 200 held by the holding unit 10 to perform laser processing.

[0036] In embodiment 1, the laser beam irradiation unit 20 includes a laser oscillator 22 that emits a laser beam 21 having a wavelength that is transparent to the workpiece 200, a focusing lens 23 (corresponding to a focusing device) that focuses the laser beam 21 inside the workpiece 200 held by the holding unit 10, and a reflecting mirror 24 that reflects the laser beam 21 emitted by the laser oscillator 22 toward the focusing lens 23.

[0037] In the first embodiment, the laser beam irradiation unit 20 irradiates the workpiece 200 with a laser beam 21, which is transparent to the workpiece 200, along the planned dividing line 203, with the focal point set inside the substrate 201, to form a modified layer inside the workpiece 200. The modified layer refers to a region where the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area, and examples of such a modified layer include a melt-treated region, a crack region, a dielectric breakdown region, a refractive index change region, and a region where these regions are mixed. The modified layer also has lower mechanical strength and the like than other parts of the workpiece 200.

[0038] The imaging unit includes an imaging element that images an area where a modified layer is to be formed on the workpiece 200 before laser processing, which is held in the holding unit 10. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The imaging unit images the workpiece 200 held in the holding unit 10, obtains an image for performing alignment between the workpiece 200 and the laser beam irradiation unit 20, and outputs the obtained image to the controller 100.

[0039] The distance measuring device 40 is provided at the tip of the support column 6, and in the first embodiment, is arranged at a position aligned in the X-axis direction with the laser beam irradiation unit 20. The distance measuring device 40 measures the distance in the Z-axis direction to the holding surface 11 of the holding unit 10 or the workpiece 200 held by the holding unit 10, and outputs the measurement result to the controller 100.

[0040] (microscope) Next, the microscope 50 will be described. Fig. 2 is a diagram showing a typical configuration of the microscope of the processing apparatus shown in Fig. 1. Fig. 3 is a side view showing a typical first lens of the microscope shown in Fig. 2 and an internal slope of the workpiece to be imaged. Fig. 4 is a diagram showing a typical second lens of the microscope shown in Fig. 2 and a coupling optical system.

[0041] The microscope 50 shown in FIG. 2 is used to observe the inside of the workpiece 200 held on the holding surface 11 of the holding unit 10. In the first embodiment, the microscope 50 is an oblique plane microscope (OPM) that captures an image of an inclined surface 210 (shown in FIG. 3) inside the workpiece 200 held on the holding surface 11 of the holding unit 10. The inclined surface 210 is a plane that is part of the inside of the workpiece 200 located below the microscope 50 in the Z-axis direction, and has a constant angle θ with respect to the X-axis direction in the Y-axis direction. The angle θ is an angle that is greater than 0 degrees and less than 90 degrees.

[0042] 2, the microscope 50 includes a light receiving element 51, a relay optical system 60, a diffraction grating 70, and an imaging optical system 80. The light receiving element 51 includes an imaging element that captures an image formed by the imaging optical system 80. The light receiving element 51 includes, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element.

[0043] The relay optical system 60 includes a first lens 61 facing the workpiece 200 held on the holding surface 11 of the holding unit 10 in the Z-axis direction, a light source unit 64 that irradiates illumination light 63 onto the first lens 61, and a second lens 62 that focuses light 65 focused by the first lens 61 to form an intermediate image 66.

[0044] The light source unit 64 includes a light source 641, a lens 642, and a polarizing beam splitter (PBS) 643. In the first embodiment, the light source 641 is an LED (Light-Emitting Diode) that emits illumination light 63 with a wavelength of 1200 nm. The lens 642 outputs the illumination light 63 emitted by the light source 641 toward the PBS 643. The PBS 643 reflects the illumination light 63 toward the first lens 61.

[0045] The first lens 61 collects illumination light 63 from the PBS 643 onto the inclined surface 210 inside the workpiece 200, and also collects light 65 from the inclined surface 210 inside the workpiece 200, and emits the collected light toward the PBS 643. The PBS 643 transmits the light 65 collected by the first lens 61 toward the second lens 62. The second lens 62 collects the light 65 collected by the first lens 61 in space to form an intermediate image 66.

[0046] In the first embodiment, the relay optical system 60 is provided with a pair of lenses 67 and 68 between the PBS 643 and the second lens 62, which transmit the light 65 collected by the first lens 61 to the second lens 62. In the first embodiment, the relay optical system 60 is provided with a quarter-wave plate 69 between the first lens 61 and the PBS 643.

[0047] The diffraction grating 70 is disposed at the position of the intermediate image 66 formed by the second lens 62. In the first embodiment, the intermediate image 66 is formed on the surface by the second lens 62. The surface of the diffraction grating 70 is disposed so as to coincide with a plane conjugate with the inclined surface 210 inside the workpiece 200. In particular, when the optical magnification M = the refractive index n, the diffraction grating 70 is disposed so that the angle formed between the normal 71 of the diffraction grating 70 (a line segment perpendicular to the surface) and the optical axis 601 of the second lens 62 of the relay optical system 60 (also referred to as the optical axis of the first lens 61 or the optical axis of the relay optical system 60) is the angle θ, as shown in FIG. 4 . The diffraction grating 70 diffracts the light 65 from the second lens 62, i.e., the intermediate image 66, and guides it to the imaging optical system 80.

[0048] The imaging optical system 80 forms an intermediate image 66 diffracted by the diffraction grating 70 on the light receiving element 51. The imaging optical system 80 includes a pair of lenses 81 and 82 that form the intermediate image 66 on the light receiving element 51. In particular, when the optical magnification M=refractive index n holds, the lens 81 of the pair of lenses 81 and 82 of the imaging optical system 80 that is closer to the diffraction grating 70 is oriented such that the angle between the optical axis 801 (also referred to as the optical axis of the imaging optical system) and the optical axis 601 of the second lens 62 of the relay optical system 60 is the angle θ described above, as shown in FIG.

[0049] As described above, in the first embodiment, the normal 71 of the diffraction grating 70 is arranged so as to coincide with the optical axis 801 of the imaging optical system 80, but in the present invention, it is sufficient that they are arranged so as to be parallel. In particular, when the optical magnification M = refractive index n holds, the lens 81 is arranged in an orientation such that the angle between the optical axis 801 and the optical axis 601 of the second lens 62 is the angle θ described above, and therefore the optical axis 801 of the imaging optical system 80 is tilted with respect to the optical axis 601 of the second lens 62.

[0050] In particular, when the optical magnification M = refractive index n holds, the imaging optical system 80 is configured such that the lens 81 is oriented such that the angle between the optical axis 801 and the optical axis 601 of the second lens 62 is the angle θ described above, and thereby forms an image of the internal slope 210 of the workpiece 200, which is inclined in a direction such that the angle between the optical axis 801 and the optical axis 601 of the second lens 62 is angle θ in the intermediate image 66 (i.e., a direction that is not perpendicular to the optical axis 601 of the second lens 62), on the light receiving element 51.

[0051] In particular, when the optical magnification M=refractive index n holds, the microscope 50, by including the imaging optical system 80 described above, captures an image of the inclined surface 210 that is inclined in a direction that forms an angle θ with the optical axis 601 of the second lens 62 inside the workpiece 200 (i.e., a direction that is not perpendicular to the optical axis 601 of the second lens 62) via the intermediate image 66 formed by the second lens 62. The microscope 50 captures a predetermined number (e.g., 30) of images of the inclined surface 210 per second using the light receiving element 51.

[0052] Furthermore, in embodiment 1, the microscope 50 has the focal lengths F1, F4, F2, and F3 of the lenses 61, 62, 67, and 68 set so as to satisfy the following equations 1 and 2, where n is the refractive index of the workpiece 200, F1 is the focal length of the first lens 61, F2 is the focal length of the lens 67, F3 is the focal length of the lens 68, F4 is the focal length of the second lens 62, and M is the optical magnification of the intermediate image 66 relative to the inclined surface 210.

[0053]

number

[0054]

number

[0055] If the refractive index n of the workpiece 200, the focal length F1 of the first lens 61, the focal length F2 of the lens 67, and the focal length F3 of the lens 68 are determined, the focal length F4 of the second lens 62 satisfies the following equation 3.

[0056]

number

[0057] In the first embodiment, the workpiece 200 is made of silicon, the thickness of the workpiece 200 is 720 μm, the refractive index n of the workpiece 200 is 3.52, the focal length F1 of the first lens 61 is 1.8 mm, the numerical aperture (NA) of the first lens 61 is 0.85, the focal length F2 of the lens 67 is 153.5 mm, the focal length F3 of the lens 68 is 218 mm, the focal length F4 of the second lens 62 is 9.0 mm, the numerical aperture of the second lens 62 is 0.45, and the optical magnification M is 3.52. In the first embodiment, the focal length of the lens 81 of the imaging optical system 80 is 28.6 mm, the numerical aperture of the lens 81 is 0.22, and the focal length of the lens 82 is 130 mm.

[0058] In this way, in the first embodiment, the refractive index n and the optical magnification M satisfy the following formula 4.

[0059]

number

[0060] However, in the present invention, it is sufficient that the focal lengths F1, F4, F2, and F3 of the lenses 61, 62, 67, and 68 of the relay optical system 60 are set so that the refractive index n and the optical magnification M satisfy the following formula 5. If the difference between the optical magnification M and the refractive index n exceeds 10% of the refractive index n, optical aberration will be large even when an image of the slope 210 is acquired, and it may become difficult to grasp the state of the modified layer with high accuracy. Also, in the present invention, the relay optical system 60 does not need to include the lenses 67 and 68, and may include lenses other than these lenses 67 and 68. In any case, it is sufficient that the focal lengths of the lenses that constitute the relay optical system 60 are set so that the relay optical system 60 satisfies formula 5.

[0061]

number

[0062] The controller 100 controls each component of the processing device 1 to cause the processing device 1 to perform a processing operation on the workpiece 200. The controller 100 is a computer having an arithmetic processing device with a microprocessor such as a CPU (central processing unit), a storage device with memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing device of the controller 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the processing device 1 to each component of the processing device 1 via the input / output interface device.

[0063] The controller 100 is connected to a display unit (not shown) configured with a liquid crystal display device or the like that displays the status of the machining operation, images, etc., and an input unit (not shown) that the operator uses to register machining content information, etc. The input unit is configured with at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

[0064] (Processing method) Next, a method for processing a workpiece according to the first embodiment will be described. Fig. 5 is a flowchart showing the flow of the method for processing a workpiece according to the first embodiment. The method for processing a workpiece according to the first embodiment is a method for laser processing a workpiece 200 using the processing device 1 having the above-mentioned configuration. That is, the method for processing a workpiece is a method in which the processing device 1 having the above-mentioned configuration forms a modified layer along the planned dividing line 203 inside the workpiece 200, and generates a three-dimensional image including the modified layer along the planned dividing line 203 inside the workpiece 200.

[0065] As shown in FIG. 5, the method for processing a workpiece according to the first embodiment includes a holding step 1001, a modified layer forming step 1002, a moving step 1003, an imaging step 1004, a generating step 1005, and an inspecting step 1006.

[0066] The holding step 1001 is a step in which the holding unit 10 holds the workpiece 200. In the first embodiment, in the holding step 1001, the processing conditions are registered in the controller 100 by an operator or the like in the processing apparatus 1, and the back surface 205 of the workpiece 200 is placed on the holding surface 11 of the holding unit 10 via the tape 206. In the first embodiment, in the holding step 1001, when the controller 100 receives an instruction to start the processing operation from an operator or the like, the controller 100 suction-holds the back surface 205 of the workpiece 200 on the holding surface 11 of the holding unit 10 via the tape 206.

[0067] The modified layer forming step 1002 is a step of positioning the focal point of the laser beam 21 inside the workpiece 200 and irradiating the workpiece 200 with the laser beam 21 to form a modified layer inside the workpiece 200. In the first embodiment, in the modified layer forming step 1002, the processing apparatus 1 has the controller 100 control the moving unit 30 to move the holding unit 10 toward the processing area, photograph the workpiece 200 with the imaging unit, and perform alignment based on the image photographed by the imaging unit.

[0068] In embodiment 1, in the modified layer formation step 1002, the processing apparatus 1 has the controller 100 controlling the laser beam irradiation unit 20 and the moving unit 30 to relatively move the focusing lens 23 of the laser beam irradiation unit 20 and the holding unit 10 along the planned division line 203 while positioning the focusing point of the laser beam 21 inside the workpiece 200, and irradiating the laser beam 21 from the surface 202 side to the center of the width direction of the planned division line 203 of the workpiece 200.

[0069] In the first embodiment, in the modified layer forming step 1002, the laser beam 21 has a wavelength that is transparent to the workpiece 200, so that modified layers are formed inside the substrate 201 along the planned dividing lines 203. In the first embodiment, in the modified layer forming step 1002, the processing apparatus 1 forms modified layers inside the workpiece 200 along all of the planned dividing lines 203. Note that in the modified layer forming step 1002, the processing apparatus 1 raises and lowers the laser beam application unit 20 in the Z-axis direction using the Z-axis moving unit 34 based on the measurement result of the distance measuring device 40 so that the focal point of the laser beam 21 is positioned at a predetermined position in the thickness direction of the substrate 201 of the workpiece 200, thereby maintaining a constant distance between the laser beam application unit 20 and the workpiece 200.

[0070] The moving step 1003 is a step of relatively moving the microscope 50 and the workpiece 200 along the X-axis direction intersecting with the direction of the optical axis 601 of the first lens 61. In the first embodiment, in the moving step 1003, the controller 100 of the processing apparatus 1 controls the moving unit 30 to relatively move the workpiece 200 held by the holding unit 10 and the microscope 50 along the planned dividing lines 203. In the first embodiment, in the moving step 1003, the processing apparatus 1 relatively moves the workpiece 200 and the microscope 50 along all the planned dividing lines 203.

[0071] The imaging step 1004 is a step of imaging the inclined surface 210 inclined at an angle θ with respect to the X-axis direction inside the workpiece 200, i.e., the inclined surface 210 inclined in a direction not perpendicular to the direction of the optical axis 601, using the microscope 50 via a conjugate plane of the inclined surface 210 in the intermediate image 66. In the first embodiment, during the movement step 1003, the processing apparatus 1 controls the microscope 50 so that the microscope 50 captures a predetermined number of images per second of the modified layer inside the workpiece 200.

[0072] In the first embodiment, in the imaging step 1004, the processing apparatus 1 uses the microscope 50 to image the modified layers formed inside the workpiece 200 along all of the planned dividing lines 203. Note that in the moving step 1003 and the imaging step 1004, the processing apparatus 1 raises and lowers the microscope 50 in the Z-axis direction using the Z-axis moving unit 34 based on the measurement result of the distance measuring device 40 so that the modified layers formed inside the substrate 201 of the workpiece 200 along the planned dividing lines 203 are included in the inclined surface 210, thereby maintaining a constant distance between the microscope 50 and the workpiece 200. In this way, the distance measuring device 40 and the Z-axis moving unit 34 are height correction units that maintain a constant distance between the first lens 61 of the microscope 50 and the holding surface 11 of the holding unit 10 or the workpiece 200.

[0073] The generating step 1005 is a step of generating a three-dimensional image (corresponding to a three-dimensional image) of an area including the modified layer inside the workpiece 200 from a plurality of images including the modified layer inside the workpiece 200 obtained by repeating the moving step 1003 and the imaging step 1004. In the first embodiment, in the generating step 1005, the controller 100 of the processing apparatus 1 synthesizes the images captured by the microscope 50 in the imaging step 1004 to generate a three-dimensional image of an area including the modified layer inside the workpiece 200. In this way, the controller 100 moves the microscope 50 and the holding unit 10 relatively to capture images of the inclined surface 210 a plurality of times, and generates a three-dimensional image of the inside of the workpiece 200 from the plurality of obtained images.

[0074] The moving step 1003, the imaging step 1004, and the generating step 1005 are a method for generating a three-dimensional image using the microscope 50 described above to generate a three-dimensional image including the modified layer inside the workpiece 200.

[0075] Inspection step 1006 is a step of diagnosing the state of the modified layer based on the 3D image generated in generation step 1005. In embodiment 1, in inspection step 1006, the controller 100 of the processing apparatus 1 displays the 3D image generated in generation step 1005 on the display unit. In embodiment 1, in inspection step 1006, the operator determines whether the modified layer is good or bad based on the 3D image displayed on the display unit. Note that the determination of whether the modified layer is good or bad is made, for example, based on the position where the modified layer is formed inside the workpiece 200 and whether the length of the modified layer is appropriate.

[0076] After the workpiece processing method according to the first embodiment is performed, the workpiece 200 is divided into individual devices 204 along the modified layers.

[0077] As described above, the processing apparatus 1 according to the first embodiment collects light 65 from the inclined surface 210 inside the workpiece 200 to form the intermediate image 66, and particularly when the optical magnification M = the refractive index n, images the inside of the workpiece 200 using the microscope 50, which is a so-called oblique microscope that forms an image of the inclined surface 210 inside the workpiece 200, which is inclined in a direction such that the angle it forms with the optical axis 601 of the second lens 62 is the angle θ in the intermediate image 66, on the light-receiving element 51. For this reason, when acquiring a three-dimensional image of the inside of each planned division line 203, the processing apparatus 1 according to the first embodiment can image the inside of each planned division line 203 with one continuous scan in the X-axis direction while keeping the distance between the microscope 50 and the workpiece 200 in the Z-axis direction constant, without repeating a process of changing the position of the microscope 50 in the Z-axis direction and capturing images multiple times while intermittently changing the X- and Y-positions.

[0078] As a result, the processing device 1 according to the first embodiment has the effect of improving productivity when generating a three-dimensional image of the inside of the workpiece 200.

[0079] Furthermore, in an oblique microscope, it is known that an intermediate image 66 with reduced aberration effects can be generated by matching the refractive index n of the object to be imaged with the optical magnification M of the intermediate image 66 relative to the interior of the object to be imaged, as disclosed in EJ Botcherby et al., Optics Communications 281, 880 (2008) or https: / / amsikking.github.io / any_immersion_remote_refocus_microscopy / .

[0080] Therefore, in the processing apparatus 1 of embodiment 1, the microscope 50 has an imaging optical system 80 that satisfies the above-mentioned equation 4 or equation 5, so that aberration in the image of the inside of the workpiece 200 captured by the microscope 50 can be suppressed.

[0081] Furthermore, in the processing apparatus 1 according to the first embodiment, the second lens 62 of the microscope 50 forms an intermediate image 66 on the diffraction grating 70, and the imaging optical system 80 forms an image of the intermediate image 66 formed on the diffraction grating 70 on the light receiving element 51. For this reason, the processing apparatus 1 according to the first embodiment can image the inclined surface 210 inside the workpiece 200, where the angle θ is greater than, for example, 45 degrees, using the microscope 50. As a result, the processing apparatus 1 according to the first embodiment can image the inclined surface 210 including the modified layer inside the workpiece 200 using the microscope 50.

[0082] [Embodiment 2] A processing apparatus according to a second embodiment will be described with reference to the drawings. FIG. 6 is a diagram schematically illustrating the configuration of a microscope of the processing apparatus according to the second embodiment. FIG. 7 is a side view schematically illustrating a first lens of the microscope shown in FIG. 6 and an internal slope of a workpiece to be imaged. FIG. 8 is a diagram schematically illustrating a second lens of the microscope shown in FIG. 6 and a coupling optical system. In FIGS. 6, 7, and 8, the same parts as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0083] As shown in Fig. 6, the processing apparatus 1 according to the second embodiment has the same configuration as that of the first embodiment, except that the microscope 50 does not include the diffraction grating 70. In the processing apparatus 1 according to the second embodiment, the microscope 50 does not include the diffraction grating 70, and therefore the microscope 50 images an inclined surface 210-2 inside the workpiece 200, whose angle θ-2 with respect to the X-axis direction is smaller than the angle θ in the first embodiment, as shown in Fig. 7. For this reason, in the second embodiment, the angle θ-2 formed between the optical axis 601 of the relay optical system 60 and the optical axis 801 of the imaging optical system 80 is smaller than the angle θ in the first embodiment, as shown in Fig. 8.

[0084] As with embodiment 1, the processing apparatus 1 of embodiment 2 has the effect of improving productivity when generating a three-dimensional image of the interior of the workpiece 200 by using a microscope 50, which is a so-called oblique microscope, to capture an image of the interior of the workpiece 200.

[0085] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention. [Explanation of symbols]

[0086] 1 Processing equipment 10 Holding Unit 11 Holding surface 31 Y-axis moving unit (moving unit) 32 X-axis moving unit (moving unit) 34 Z-axis movement unit (height correction unit) 40 Distance measuring device (height correction unit) 50 Microscope 51 Photodetector 61 First Lens 62 Second Lens 65 light 66 Intermediate image 70 Diffraction Grating 80 Imaging optical system 100 Controllers 200 Workpiece (object) 210 Slope 601 Optical axis 801 Optical axis 1001 holding steps 1002 Modified layer formation step 1003 Movement Steps (3D image generation method) 1004 Imaging step (method of generating a 3D image) 1005 Generation step (3D image generation method)

Claims

1. a holding unit for holding the workpiece; a processing unit that processes the workpiece; a microscope for observing the workpiece, The microscope comprises: A light receiving element; a first lens for collecting light from inside the workpiece; a second lens that collects the light collected by the first lens to form an intermediate image; an imaging optical system that forms an image of the light from the intermediate image on the light receiving element, The imaging optical system has an optical axis that is inclined with respect to the optical axis of the second lens, and in the intermediate image, an inclined surface that is inclined in a direction that is not perpendicular to the optical axis of the second lens is imaged onto the light-receiving element.

2. a moving unit that moves the microscope and the holding unit relatively along a moving direction that intersects with the optical axis direction of the first lens; a controller for controlling the processing device, the microscope captures an image of an inclined surface inclined in a direction not perpendicular to the optical axis direction inside the workpiece via the inclined surface of the intermediate image; The processing apparatus according to claim 1 , wherein the controller takes images of the inclined surface a plurality of times by moving the microscope and the holding unit relative to each other, and generates a three-dimensional image of the interior of the workpiece from the obtained plurality of images.

3. 2. The processing apparatus according to claim 1, further comprising a diffraction grating disposed at the position of the intermediate image, for diffracting the light from the second lens and directing it to the imaging optical system.

4. 4. The processing apparatus according to claim 1, wherein the following relational expression is satisfied, where n is the refractive index of the workpiece and M is the optical magnification of the intermediate image: |M-n|≦n×0.1

5. 5. The processing apparatus according to claim 4, further comprising a height correction unit that keeps a constant distance between the first lens and the holding surface of the holding unit or the workpiece.

6. A microscope for observing an object, A light receiving element; a first lens that receives light from the object; a second lens that condenses the light that has passed through the first lens to form an intermediate image with an optical magnification M that satisfies the following relation, where n is the refractive index of the object; an imaging optical system that forms an image of the light from the intermediate image on the light receiving element; a diffraction grating disposed at a position of the intermediate image, for diffracting the light from the second lens and guiding it to the imaging optical system; the imaging optical system has an optical axis that is inclined with respect to the optical axis of the second lens, and forms an image of an inclined surface inclined in a direction that is not perpendicular to the optical axis of the second lens in the intermediate image on the light receiving element; The diffraction grating is arranged so that its normal is parallel to the optical axis of the imaging optical system. |M-n|≦n×0.1

7. A method for generating a three-dimensional image of the inside of an object using the microscope according to claim 6, comprising: a moving step of relatively moving the microscope and the object along a moving direction intersecting with an optical axis direction of the first lens; an imaging step of imaging, with the microscope, an inclined surface inclined in a direction not perpendicular to the optical axis direction within the object through the inclined surface of the intermediate image; a generating step of generating a three-dimensional image of the interior of the object from a plurality of images obtained by repeating the moving step and the imaging step; A method for generating a three-dimensional image comprising:

8. A method for processing a workpiece using the processing device according to claim 1, comprising: The processing unit includes a laser oscillator that emits a laser beam having a wavelength that is transparent to the workpiece, and a condenser that condenses the laser beam, a holding step of holding the workpiece with the holding unit; a modified layer forming step of positioning a focal point of the laser beam inside the workpiece and irradiating the workpiece with the laser beam to form a modified layer inside the workpiece; a moving step of relatively moving the microscope and the workpiece on which the modified layer is formed along a moving direction intersecting with an optical axis direction of the first lens; an imaging step of imaging, with the microscope, an inclined surface inclined in a direction not orthogonal to the optical axis direction inside the workpiece through the inclined surface of the intermediate image; a generating step of generating a three-dimensional image of a region including the modified layer inside the workpiece from a plurality of images obtained by repeating the moving step and the imaging step; A method for processing a workpiece, comprising:

Images