Processing method and laser processing device

Abstract

To suppress a detection error of a position of a laser processing groove.SOLUTION: A processing method is a processing method of a workpiece in which a planned processing line is set, and includes: a holding step 1002 of holding the workpiece by a holding unit; and a second laser processing step 1005 of forming a second laser processing groove by relatively moving a focusing point of a laser beam along the planned processing line while irradiating the workpiece held by the holding unit with a laser beam. The second laser processing groove includes: two deep groove parts which are deeper than a central part in a width direction on both end sides in the width direction; and a shallow groove part which is shallower than each deep groove part sandwiched between each deep groove part.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for processing a workpiece having a predetermined processing line set thereon, and a laser processing apparatus. [Background technology]

[0002] For example, when dividing a wafer, a laser beam may be irradiated along the streets to form laser-processed grooves, and then the laser-processed grooves may be cut with a cutting blade to divide the wafer.

[0003] Therefore, a technique for detecting the edge of a laser-processed groove in order to correct the cutting position has been disclosed (see, for example, Patent Document 1).

[0004] On the other hand, in order to prevent the cutting blade from cutting a position outside the laser-processed groove, it is important to detect the position of the laser-processed groove before cutting. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-010445 Summary of the Invention [Problem to be solved by the invention]

[0006] However, laser-processed grooves generally tend to be formed in a tapered shape, where the groove width narrows as the groove depth increases. Even when laser-processed grooves with sloped sidewalls are imaged from the top surface of the wafer, the edges of the grooves are not clearly visible in the captured image, making them difficult to detect. This leads to errors in detecting the positions of the laser-processed grooves, and improvements are needed to detect the edges of laser-processed grooves.

[0007] An object of the present invention is to provide a processing method and a laser processing apparatus that can suppress detection errors in the position of a laser-processed groove. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the processing method of the present invention is a method for processing a workpiece having a planned processing line set thereon, and comprises: a holding step of holding the workpiece with a holding unit; and a laser processing step of irradiating the workpiece held by the holding unit with a laser beam while moving the focal point of the laser beam relatively along the planned processing line to form a laser processed groove, wherein the laser processed groove has two deep groove portions at both ends in the width direction that are deeper than the central portion in the width direction, and a shallow groove portion sandwiched between the deep groove portions.

[0009] In the above processing method, the shallow groove portion may have a bottom portion having an uneven surface.

[0010] The processing method may further include a positioning step of shaping the laser beam generated by the oscillator with a diffractive optical element before performing the laser processing step, and positioning the focal point of the laser beam shaped by the diffractive optical element on the intended processing line of the workpiece held by the holding unit.

[0011] The laser processing apparatus of the present invention comprises a holding unit that holds a workpiece, an oscillator, a diffractive optical element that shapes the laser beam generated by the oscillator, a condenser having a focusing lens that focuses the laser beam shaped by the diffractive optical element on the workpiece held by the holding unit, and a moving unit that forms a laser-processed groove in the workpiece by moving the focusing point of the laser beam focused by the condenser relative to the workpiece held by the holding unit, and is characterized in that the diffractive optical element shapes the laser beam so that the laser-processed groove has two deep groove portions at both ends in the width direction that are deeper than the central portion in the width direction, and a shallow groove portion sandwiched between the deep groove portions.

[0012] In the laser processing device, the diffractive optical element may shape the laser beam so that irregularities are formed at the bottom of the shallow groove. [Effects of the Invention]

[0013] The present invention has the effect of suppressing detection errors in the position of the laser-processed groove. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a laser processing device according to the first embodiment. [Figure 2] FIG. 2 is a perspective view showing a workpiece to be processed by the laser processing apparatus shown in FIG. [Figure 3] FIG. 3 is a diagram showing the configuration of a laser beam irradiation unit of the laser processing apparatus shown in FIG. [Figure 4] FIG. 4 is a diagram showing the planar shape of a laser beam that has passed through the output adjustment unit of the laser beam irradiation unit shown in FIG. [Figure 5] FIG. 5 is a diagram showing the energy distribution in the Y-axis direction of the laser beam emitted from the output adjustment unit of the laser beam irradiation unit shown in FIG. [Figure 6] FIG. 6 is a diagram showing the planar shape of a laser beam that has passed through the diffractive optical element of the laser beam irradiation unit shown in FIG. [Figure 7] FIG. 7 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has passed through the diffractive optical element of the laser beam irradiation unit shown in FIG. [Figure 8] FIG. 8 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has passed through the unnecessary higher-dimensional elimination unit of the laser beam irradiation unit shown in FIG. [Figure 9] FIG. 9 is a flowchart showing the flow of the processing method according to the first embodiment. [Figure 10] FIG. 10 is a side view, partly in section, schematically showing the protective film forming step of the processing method shown in FIG. [Figure 11] FIG. 11 is a side view, partly in section, showing the holding step of the processing method shown in FIG. [Figure 12]FIG. 12 is a side view, partially in section, showing the first laser processing step of the processing method shown in FIG. [Figure 13] FIG. 13 is a plan view showing a main part of the workpiece after the first laser processing step of the processing method shown in FIG. [Figure 14] FIG. 14 is a plan view schematically showing a main part of a workpiece, showing the position of the focal point positioned in the positioning step of the processing method shown in FIG. [Figure 15] FIG. 15 is a side view, partially in section, showing the second laser processing step of the processing method shown in FIG. [Figure 16] FIG. 16 is a plan view showing a main part of the workpiece after the second laser processing step of the processing method shown in FIG. [Figure 17] FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. [Figure 18] FIG. 18 is a side view, partially in section, schematically showing the protective film removing step of the processing method shown in FIG. [Figure 19] FIG. 19 is a side view, partly in section, schematically showing the dividing step of the processing method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [Embodiment 1] A laser processing apparatus according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of the configuration of the laser processing apparatus according to the first embodiment. Fig. 2 is a perspective view showing a workpiece to be processed by the laser processing apparatus shown in Fig. 1.

[0017] (Workpiece) The laser processing apparatus 1 shown in Fig. 1 according to the first embodiment is a processing apparatus that processes a workpiece 200 shown in Fig. 2. The workpiece 200 to be processed by the laser processing apparatus 1 shown in Fig. 1 according to the first embodiment is, as shown in Fig. 2, a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with a substrate 201 such as a silicon substrate, a sapphire substrate, a gallium substrate, or a SiC substrate.

[0018] In the first embodiment, as shown in Fig. 2, the workpiece 200 has a plurality of devices 204 formed in areas defined by a plurality of intersecting processing lines 203 on the surface 202. 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), or memories (semiconductor storage devices). That is, the workpiece 200 has processing lines 203 set thereon.

[0019] 2, the workpiece 200 includes a functional layer 205 laminated on the substrate 201. The functional layer 205 includes a low-dielectric-constant insulating film (hereinafter referred to as a low-k film) made of an inorganic film such as SiOF or BSG (SiOB), an organic film such as a polymer film of a polyimide or parylene system, or carbon-containing silicon dioxide (SiOCH), and a circuit layer including a conductive metal pattern or metal film.

[0020] The low-k film is laminated with a circuit layer to form a device 204. The circuit layer constitutes the circuit of the device 204. For this purpose, the device 204 is composed of low-k films laminated on top of each other in the functional layer 205 and a circuit layer laminated between the low-k films. In the processing line 203, the functional layer 205 is composed of low-k films except for the TEG (Test Elementary Group).

[0021] In the first embodiment, the workpiece 200 has a central portion of a tape 207 attached to a back surface 206 behind the front surface 202, the tape 207 having a diameter larger than the workpiece 200 and an annular frame 208 attached to its outer edge, and is supported within an opening on the inside of the frame 208. In the present invention, the workpiece 200 is not limited to being attached to the tape 207.

[0022] (Laser processing equipment) As shown in FIG. 1, the laser processing apparatus 1 of embodiment 1 includes a holding unit 10, a moving unit 30, a first laser beam irradiation unit 20-1 (shown in FIG. 12), a second laser beam irradiation unit 20-2, an imaging unit (not shown), a protective film forming and cleaning unit 40, a conveying unit 50, and a control unit 100.

[0023] 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 units 20-1 and 20-2 and a carry-in / out area spaced from below the laser beam irradiation units 20-1 and 20-2 and for carrying in and out the workpiece 200.

[0024] 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 206 of the workpiece 200 via tape 207. Also, as shown in FIG. 1, a plurality of clamping portions 12 that clamp a frame 208 are provided around the periphery of the holding unit 10.

[0025] The moving unit 30 moves the holding unit 10 and the laser beam irradiation units 20-1 and 20-2 relatively. The moving unit 30 includes at least 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, and a rotational moving unit 33 that rotates the holding unit 10 around an axis parallel to the Z-axis direction parallel to the vertical direction.

[0026] The Y-axis movement unit 31 is installed on the apparatus main body 2, and moves the moving plate 3 on which the X-axis movement unit 32 is installed in the Y-axis direction, thereby moving the holding unit 10 in the Y-axis direction. The X-axis movement unit 32 is installed on the moving plate 3, and moves the second moving plate 4 on which the rotational movement unit 33 is installed in the X-axis direction, thereby moving the holding unit 10 in the X-axis direction. 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.

[0027] 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.

[0028] The Y-axis moving unit 31 and the X-axis moving unit 32 each include a well-known ball screw rotatably mounted around its axis, a well-known motor for rotating the ball screw around its axis, and a well-known guide rail for supporting the moving plates 3 and 4 so that they can move in the X-axis or Y-axis direction. The rotational moving unit 33 includes a well-known motor for rotating the holding unit 10 around its axis.

[0029] As shown in Fig. 1, the laser beam irradiation units 20-1 and 20-2 are partially provided at the tip of a support column 6 whose base end is supported by an erect wall 5 erected from the end of the device main body 2 in the Y-axis direction. Note that Fig. 1 does not show the first laser beam irradiation unit 20-1. The laser beam irradiation units 20-1 and 20-2 perform laser processing (also called ablation processing) by irradiating the workpiece 200 held in the holding unit 10 with a laser beam 21 having a wavelength that is absorbed by the workpiece 200.

[0030] In the first embodiment, the planar shape of the laser beam 21 at the focal point 216 of the first laser beam irradiation unit 20-1 is circular. Next, the second laser beam irradiation unit 20-2 will be described.

[0031] FIG. 3 is a diagram showing the configuration of the laser beam irradiation unit of the laser processing apparatus shown in FIG. 2. FIG. 4 is a diagram showing the planar shape of the laser beam that has passed through the output adjustment unit of the laser beam irradiation unit shown in FIG. 3. FIG. 5 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has been emitted from the output adjustment unit of the laser beam irradiation unit shown in FIG. 3. FIG. 6 is a diagram showing the planar shape of the laser beam that has passed through the diffractive optical element of the laser beam irradiation unit shown in FIG. 3. FIG. 7 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has passed through the diffractive optical element of the laser beam irradiation unit shown in FIG. 3. FIG. 8 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has passed through the unnecessary high-dimensional elimination unit of the laser beam irradiation unit shown in FIG. 3.

[0032] 3, the second laser beam irradiation unit 20-2 includes an oscillator 22, an output adjustment unit 23, a diffractive optical element (DOE) 24, an unwanted higher-dimensional removal unit 25, and a condenser 26. The oscillator 22 is a device that oscillates a laser beam 21 having a wavelength that is absorbed by the workpiece 200.

[0033] The output adjustment unit 23 adjusts the output of the laser beam 21 oscillated by the oscillator 22. In the first embodiment, the output adjustment unit 23 is an attenuator. The planar shape (the shape of a plane parallel to both the X-axis direction and the Y-axis direction) of the laser beam 21 transmitted through the output adjustment unit 23 is circular, as shown in FIG. 4. The energy distribution in the X-axis direction and the Y-axis direction of the laser beam 21 transmitted through the output adjustment unit 23 is a Gaussian distribution 212 (Gaussian type distribution), as shown in FIG. 5. In FIG. 5, the horizontal axis indicates the position in the X-axis direction and the Y-axis direction, and the vertical axis indicates the energy of the laser beam 21. The center of the horizontal axis indicates the optical axis 210 of the laser beam 21.

[0034] The diffractive optical element 24 shapes and transmits the laser beam 21 that is generated by the oscillator 22 and has been transmitted through the output adjustment unit 23. In the first embodiment, the diffractive optical element 24 shapes the laser beam 21 so that the planar shape of the laser beam 21 that has been transmitted through the diffractive optical element 24 becomes a rectangle whose longitudinal direction is parallel to the Y-axis direction and whose width direction is parallel to the Y-axis direction, as shown in FIG.

[0035] Furthermore, in the first embodiment, the diffractive optical element 24 does not block the laser beam 21 that has passed through the output adjustment unit 23, but shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top-hat distribution 214 (top-hat type distribution) in which the energy at both ends 214-1 in the Y-axis direction is stronger than the energy at a center 214-2 in the Y-axis direction and the energy at the center 214-2 in the Y-axis direction changes in the Y-axis direction, as shown in Fig. 7. In Fig. 7, the horizontal axis represents the position in the Y-axis direction, and the vertical axis represents the energy of the laser beam 21. The center of the horizontal axis represents the optical axis 210 of the laser beam 21.

[0036] In the first embodiment, the laser beam 21 transmitted through the output adjustment unit 23 and shaped by the diffractive optical element 24 has its energy distribution in the Y-axis direction shaped into a top-hat distribution 214, and also has an unnecessary higher-order portion 215 formed on the outside of the Y-axis direction by the higher-order light, in which the output changes in the Y-axis direction. The energy of the unnecessary higher-order portion 215 is lower than the energy of both ends 214-1 and the central portion 214-2 of the top-hat distribution 214.

[0037] The unnecessary high-dimensional elimination unit 25 transmits the laser beam 21 so as to remove unnecessary high-dimensional parts 215 from the energy distribution of the laser beam 21 in the Y-axis direction that has been transmitted through the diffractive optical element 24, leaving only a top-hat distribution 214, as shown in Fig. 8. In Fig. 7, the horizontal axis indicates the position in the Y-axis direction, and the vertical axis indicates the energy of the laser beam 21. The center of the horizontal axis indicates the optical axis 210 of the laser beam 21.

[0038] 3, the unwanted high-dimensional removal unit 25 has a first plano-convex lens 27, a mask 28, and a second plano-convex lens 29. The first plano-convex lens 27 has a convex surface 271 facing the diffractive optical element 24, and focuses the laser beam 21 that has passed through the diffractive optical element 24 and guides it to an opening 281 in the mask 28.

[0039] The mask 28 blocks a portion of the laser beam 21 focused by the first plano-convex lens 27. The mask 28 has an opening 281 at its center that transmits the laser beam 21 focused by the first plano-convex lens 27. The opening 281 has a rectangular shape with its longitudinal direction parallel to the Y-axis direction and its width direction parallel to the X-axis direction. The opening 281 is formed to a size that blocks unnecessary higher-order parts 215 caused by higher-order light.

[0040] The second plano-convex lens 29 has a convex surface 291 on the rear side of the mask 28, onto which the laser beam 21 that has passed through the opening 281 of the mask 28 is incident, and converts the laser beam 21 that has passed through the opening 281 into parallel light.

[0041] The condenser 26 has a condenser lens 261 that condenses the laser beam 21, which has been shaped by the diffractive optical element 24 and passed through the unnecessary high-dimensional removal unit 25, onto the workpiece 200, and an elevator unit 262 that moves the condenser lens 261 in the Z-axis direction to change the position of the focal point 216 of the laser beam 21 in the Z-axis direction.

[0042] The imaging unit includes an imaging element that images an area to be divided of the workpiece 200 held in the holding unit 10 before laser processing. 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 to obtain an image for performing alignment between the workpiece 200 and the laser beam irradiation units 20-1 and 20-2, and outputs the obtained image to the control unit 100.

[0043] The protective film forming and cleaning unit 40 forms a protective film (not shown) on the surface 202 of the workpiece 200 before laser processing, and cleans the workpiece 200 after laser processing to remove the protective film. The protective film forming and cleaning unit 40 is disc-shaped and includes a spinner table 41 having a flat holding surface formed of porous ceramic or the like along the horizontal direction for holding the workpiece 200, a coating nozzle 42, and a cleaning nozzle 43 (shown in FIG. 10). The spinner table 41 is rotated around an axis parallel to the Z-axis direction by a rotary drive source (not shown).

[0044] The holding surface of spinner table 41 is connected to a vacuum suction source (not shown), and is sucked by the vacuum suction source to suck and hold workpiece 200 placed on the holding surface. In the first embodiment, spinner table 41 sucks and holds back surface 206 of workpiece 200 via tape 207. In addition, a plurality of clamps 44 that clamp frame 208 are provided around spinner table 41.

[0045] The coating nozzle 42 applies a liquid water-soluble resin 45 (for example, HogoMax (registered trademark) manufactured by Disco Corporation) such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) to the surface 202 of the workpiece 200 held by the spinner table 41, and dries the liquid water-soluble resin 45 to coat the entire surface 202 of the workpiece 200 with a protective film. The cleaning nozzle 43 supplies cleaning water (pure water in the first embodiment) to the surface 202 of the workpiece 200 held by the spinner table 41 to remove the protective film and clean the surface 202 of the workpiece 200.

[0046] The transport unit 50 transports the workpiece 200 between the holding unit 10 and the protective film forming and cleaning unit 40. The transport unit 50 includes a transport arm 51 that transports the workpiece 200 between the holding unit 10 and the protective film forming and cleaning unit 40.

[0047] The control unit 100 controls each component of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform processing operations on the workpiece 200. The control unit 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 control unit 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the laser processing apparatus 1 to each component of the laser processing apparatus 1 via the input / output interface device.

[0048] The control unit 100 is connected to a display unit (not shown) that is 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.

[0049] (Processing method) Next, a processing method according to the first embodiment will be described. Fig. 9 is a flowchart showing the flow of the processing method according to the first embodiment. The processing method according to the first embodiment is a method of dividing a workpiece 200, on which a line to be processed 203 is set, into individual devices 204 by performing laser processing or the like on the workpiece 200 and cutting the line to be processed 203 of the workpiece 200 at a center 209 in the width direction (shown by a dashed line in Fig. 13 ) to divide the workpiece 200. As shown in Fig. 9 , the processing method according to the first embodiment includes a protective film forming step 1001, a holding step 1002, a first laser processing step 1003, a positioning step 1004, a second laser processing step 1005, a protective film removing step 1006, and a dividing step 1007.

[0050] (Protective film formation step) 9. Protective film forming step 1001 is a step of coating a protective film on surface 202 of workpiece 200. In protective film forming step 1001, laser processing apparatus 1 starts the processing operation, i.e., protective film forming step 1001, when an operator or the like registers processing conditions in control unit 100, workpiece 200 is placed on the holding surface of spinner table 41 via tape 207, and control unit 100 receives a command to start the processing operation from the operator or the like.

[0051] In the protective film forming step 1001, the laser processing apparatus 1 according to the first embodiment suction-holds the back surface 206 of the workpiece 200 on the holding surface of the spinner table 41 via the tape 207, clamps the frame 208 with the clamp unit 44, rotates the spinner table 41 around its axis, and drips liquid water-soluble resin 45 from the coating nozzle 42 onto the center of the front surface 202 of the workpiece 200. The dripped water-soluble resin 45 flows from the center to the outer periphery on the front surface 202 of the workpiece 200 due to centrifugal force generated by the rotation of the spinner table 41, and is applied to the entire front surface 202 of the workpiece 200. In the protective film forming step 1001, the laser processing apparatus 1 according to the first embodiment supplies the water-soluble resin 45 for a predetermined time while rotating the spinner table 41 around its axis, dries the water-soluble resin 45, and coats the front surface 202 of the workpiece 200 with a protective film.

[0052] (holding step) Fig. 11 is a side view, partially in cross section, showing the holding step of the processing method shown in Fig. 9. Holding step 1002 is a step in which workpiece 200 is held by holding unit 10. In embodiment 1, in holding step 1002, control unit 100 of laser processing apparatus 1 stops rotation of spinner table 41 around its axis and suction holding of the holding surface, and stops clamping of frame 208 of clamp section 44.

[0053] In the holding step 1002 of the embodiment 1, the control unit 100 of the laser processing apparatus 1 controls the transport unit 50 to place the workpiece 200 from the spinner table 41 onto the holding surface 11 of the holding unit 10. In the holding step 1002 of the embodiment 1, as shown in FIG. 11 , the control unit 100 controls the vacuum suction source to suction-hold the back surface 206 of the workpiece 200 onto the holding surface 11 of the holding unit 10 via the tape 207, exposing the front surface 202 of the workpiece 200, and clamping the frame 208 with the clamp section 12.

[0054] (First laser processing step) Fig. 12 is a side view, partially in cross section, showing the first laser processing step of the processing method shown in Fig. 9. Fig. 13 is a plan view showing a main part of the workpiece after the first laser processing step of the processing method shown in Fig. 9.

[0055] The first laser processing step 1003 is a step of forming first laser processing grooves 220 at both ends in the width direction of each planned processing line 203 of the workpiece 200, thereby preventing the functional layer 205 from peeling off from the substrate 201 when dividing the workpiece 200 into each device 204. In the first embodiment, in the first laser processing step 1003, the control unit 100 of the laser processing apparatus 1 controls the moving unit 30 to move the holding unit 10 toward the processing area, photographs the workpiece 200 with the imaging unit, and performs alignment based on the image photographed by the imaging unit.

[0056] 12, in the laser processing apparatus 1, the control unit 100 controls the first laser beam application unit 20-1, the moving unit 30, etc. to relatively move the first laser beam application unit 20-1 and the holding unit 10 in the X-axis direction while setting the focal point 216 of the laser beam 21 on the surface 202 of the workpiece 200, and the first laser beam application unit 20-1 irradiates both ends in the width direction of the surface 202 of each of the lines to be processed 203 on the workpiece 200 with the laser beam 21. In the first laser processing step 1003, the laser processing apparatus 1 irradiates both ends in the width direction of all of the lines to be processed 203 of the workpiece 200 held by the holding unit 10 with the laser beam 21 to perform ablation processing, and forms two first laser-processed grooves 220 on each of the lines to be processed 203, as shown in FIG. In the first embodiment, the two first laser-processed grooves 220 formed in each of the lines to be processed 203 are formed at positions equidistant from the center 209 of each of the lines to be processed 203 in the width direction.

[0057] (Positioning step) Fig. 14 is a plan view schematically showing a main part of a workpiece, showing the position of the focal point positioned in the positioning step of the processing method shown in Fig. 9. In the positioning step 1004, before the second laser processing step 1005 is performed, the laser beam 21 generated by the oscillator 22 is shaped by the diffractive optical element 24, and the focal point 216 of the laser beam 21 shaped by the diffractive optical element 24 is positioned on the intended processing line 203 of the workpiece 200 held by the holding unit 10.

[0058] In the first embodiment, in the positioning step 1004, as shown in Fig. 15, the control unit 100 of the laser processing apparatus 1 controls the second laser beam application unit 20-2, the moving unit 30, etc. to position the second laser beam application unit 20-2 at the center 209 in the width direction of one end of the line to be processed 203. In the first embodiment, in the positioning step 1004, as shown in Fig. 14, the control unit 100 controls the second laser beam application unit 20-2, the moving unit 30, etc. to generate the laser beam 21 with the oscillator 22 of the second laser beam application unit 20-2, and shapes the generated laser beam 21 with a diffractive optical element, etc., to set the focal point 216 of the laser beam 21 at the center 209 in the width direction of the surface 202 at one end of the line to be processed 203, as shown in Fig. 14.

[0059] (Second laser processing step) Fig. 15 is a side view, partially in cross section, showing the second laser processing step of the processing method shown in Fig. 9. Fig. 16 is a plan view showing a main part of the workpiece after the second laser processing step of the processing method shown in Fig. 9. Fig. 17 is a cross-sectional view taken along line XVII-XVII in Fig. 16.

[0060] The second laser processing step 1005 is a laser processing step in which the laser beam 21 is irradiated onto the workpiece 200 held by the holding unit 10 while the focal point 216 of the laser beam 21 is relatively moved along the to-be-processed line 203, thereby forming a second laser-processed groove 221. In the first embodiment, in the second laser processing step 1005, as shown in Fig. 15 , the control unit 100 of the laser processing apparatus 1 controls the second laser beam application unit 20-2, the moving unit 30, etc. to relatively move the second laser beam application unit 20-2 and the holding unit 10 in the X-axis direction while setting the focal point 216 of the laser beam 21 on the surface 202 of the workpiece 200, and irradiates the laser beam 21 from the second laser beam application unit 20-2 to the center 209 in the width direction of the surface 202 of each to-be-processed line 203 of the workpiece 200.

[0061] In the first embodiment, in the second laser processing step 1005, the laser processing apparatus 1 irradiates the laser beam 21 onto the center 209 in the width direction of all of the lines to be processed 203 of the workpiece 200 held by the holding unit 10, thereby forming a second laser-processed groove 221 spanning two first laser-processed grooves 220 in each of the lines to be processed 203, as shown in Fig. 16, and forming a laser-processed groove 222 consisting of the first laser-processed groove 220 and the second laser-processed groove 221 in each of the lines to be processed 203. In this manner, the moving unit 30 moves the focal point 216 of the laser beam 21 focused by the condenser 26 relative to the workpiece 200 held by the holding unit 10, thereby forming the second laser-processed groove 221 in the workpiece 200. Note that in the first embodiment, the depth of the second laser-processed groove 221 from the surface 202 is deeper than the depth of the first laser-processed groove 220 from the surface 202.

[0062] In addition, in the first embodiment, the diffractive optical element 24 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 214 (top hat-shaped distribution) in which the energy at both ends 214-1 in the Y-axis direction is stronger than the energy at a central portion 214-2 in the Y-axis direction, as shown in Fig. 7, so that the second laser-processed groove 221 has two deep groove portions 223 at both ends in the width direction that are deeper than the central portion in the width direction, and shallow groove portions 224 sandwiched between the deep groove portions 223 and shallower than the deep groove portions 223, as shown in Fig. 17. In addition, in the first embodiment, the diffractive optical element 24 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 214 in which the energy at the central portion 214-2 in the Y-axis direction changes in the Y-axis direction, so that the second laser-processed groove 221 has unevenness formed at the bottoms 224-1 of the shallow groove portions 224.

[0063] 7, the diffractive optical element 24 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 214 (top hat type distribution) in which the energy at both ends 214-1 in the Y-axis direction is stronger than the energy at a central portion 214-2 in the Y-axis direction, thereby shaping the laser beam 21 so that the second laser-processed groove 221 has two deep groove portions 223 that are deeper at both ends in the width direction than at the central portion in the width direction, and shallow groove portions 224 sandwiched between the deep groove portions 223 and shallower than the deep groove portions 223. Also, in the first embodiment, the diffractive optical element 24 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 214 in which the energy at a central portion 214-2 in the Y-axis direction changes in the Y-axis direction, thereby shaping the laser beam 21 so that unevenness is formed at the bottoms 224-1 of the shallow groove portions 224.

[0064] In the first embodiment, the height difference of the unevenness of the bottom 224-1 of the shallow groove portion 224 is 1 μm or more and 5 μm or less. Also, in the first embodiment, the angle of both inner side surfaces 225 of the second laser-processed groove 221 relative to the surface 202 is 70 degrees or more and 90 degrees or less.

[0065] (Protection film removal step) Fig. 18 is a side view, partially in cross section, schematically showing the protective film removing step of the processing method shown in Fig. 9. The protective film removing step 1006 is a step of removing the protective film from the surface 202 of the workpiece 200. In the protective film removing step 1006, the control unit 100 of the laser processing apparatus 1 controls the moving unit 30 and the like to move the holding unit 10 to the carry-in / out area, stops suction holding of the holding surface 11 of the holding unit 10 in the carry-in / out area, and stops clamping of the frame 208 of the clamping section 12.

[0066] In protective film removal step 1006, in laser processing apparatus 1, control unit 100 controls transport unit 50 to place workpiece 200 from holding unit 10 onto the holding surface of spinner table 41. In protective film removal step 1006, laser processing apparatus 1 according to embodiment 1 suction-holds back surface 206 of workpiece 200 on the holding surface of spinner table 41 via tape 207, clamps frame 208 with clamp unit 44, rotates spinner table 41 around its axis, and drips liquid cleaning water 46 from cleaning nozzle 43 onto the center of front surface 202 of workpiece 200.

[0067] The dropped cleaning water 46 flows from the center toward the outer periphery on the surface 202 of the workpiece 200 due to centrifugal force generated by the rotation of the spinner table 41, washing away the protective film on the surface 202 of the workpiece 200 and cleaning the surface 202 of the workpiece 200. In the protective film removal step 1006, the laser processing apparatus 1 according to the first embodiment supplies cleaning water 46 for a predetermined time while rotating the spinner table 41 about its axis, thereby cleaning the surface 202 of the workpiece 200.

[0068] (Split Step) Fig. 19 is a side view, partially in cross section, schematically showing the dividing step of the processing method shown in Fig. 2. Dividing step 1007 is a step of dividing workpiece 200 into individual devices 204. In embodiment 1, in dividing step 1007, cutting device 60 shown in Fig. 19 suction-holds back surface 206 of workpiece 200 to holding surface 62 of chuck table 61 via tape 207, and clamps frame 208 with clamping section 63 around chuck table 61.

[0069] In the first embodiment, in the dividing step 1007, the cutting device 60 photographs the workpiece 200 with the imaging unit as shown in Fig. 16, detects the center position of the laser-machined groove 222 in the width direction based on the image captured by the imaging unit, and performs alignment to align the workpiece 200 with the cutting blade 64. Note that Fig. 16 shows parallel oblique lines that become darker in the image captured by the imaging unit. In the present invention, alignment can be performed by imaging the laser-machined groove 222 and positioning the cutting blade 64 over the center of the laser-machined groove 222 in the width direction, or by imaging a target pattern formed on the workpiece 200 to identify the position of the laser-machined groove 222.

[0070] In the first embodiment, in the dividing step 1007, the cutting device 60 relatively moves the chuck table 61 and the cutting blade 64, which rotates around its axis by the spindle of the cutting unit, along the to-be-processed lines 203, as shown in FIG. 19 , and cuts the cutting blade 64 into the bottoms of the laser-machined grooves 222 formed along each to-be-processed line 203 from the surface 202 side of the workpiece 200 until it reaches the tape 207, thereby dividing the workpiece 200 into individual devices 204. Furthermore, in the dividing step 1007, even if alignment is performed using a target pattern, the cutting device 60 performs a kerf check, for example, by capturing images of the cut grooves and the laser-machined grooves 222 during cutting to check for misalignment between the laser-machined grooves 222 and the cut grooves. During the kerf check, the cutting device 60 can easily detect the edges of the second laser-machined grooves 221 from the captured images.

[0071] As described above, in the processing method and laser processing apparatus 1 according to the first embodiment, in the second laser processing step 1005, two deep groove portions 223 that are deeper than the central portion are formed at both widthwise ends of the second laser-processed groove 221, and shallow groove portions 224 that are shallower than the deep groove portions 223 are formed between the deep groove portions 223. In this way, in the processing method and laser processing apparatus 1 according to the first embodiment, both widthwise ends of the second laser-processed groove 221 are formed deeper than the central portion. Therefore, for example, as shown in Fig. 16, in an image captured by epi-illumination of the cutting device 60 used in the dividing step 1007, the vicinity of both widthwise ends of the second laser-processed groove 221 appears darker, and the boundary between the second laser-processed groove 221 and the unprocessed area outside the groove becomes clearer, making it possible to more accurately detect the position of the laser-processed groove 222 in the widthwise direction of the line to be processed 203.

[0072] As a result, the processing method and laser processing device 1 according to the first embodiment have the advantage of being able to suppress detection errors in the position of the laser-processed groove 222.

[0073] The present invention is not limited to the above-described embodiment. In other words, various modifications can be made without departing from the gist of the present invention. In the above-described first embodiment, the laser processing apparatus 1 includes the first laser beam irradiation unit 20-1 and the second laser beam irradiation unit 20-2. However, in the present invention, the workpiece 200 may be processed using a laser processing apparatus including a first laser beam irradiation unit 20-1 and a laser processing apparatus 1 including a second laser beam irradiation unit 20-2, which are separate from each other. Furthermore, in the present invention, the laser processing apparatus 1 does not necessarily have to include the protective film forming and cleaning unit 40. Furthermore, the laser processing apparatus 1 may include at least one of a unit that forms a protective film and a unit that cleans the workpiece 200. [Explanation of symbols]

[0074] 1. Laser processing equipment 10 Holding Unit 21 Laser beam 22 Oscillator 24 Diffractive optical element 26 Concentrator 30 Mobile Units 200 Workpiece 203 Processing line 216 Focusing point 221 Second laser processed groove (laser processed groove) 223 Deep groove part 224 Shallow groove 224-1 Bottom 261 Condenser Lens 1002 holding steps 1004 Positioning Step 1005 Second laser processing step (laser processing step)

Claims

1. A method for processing a workpiece in which a planned processing line is set, a holding step of holding the workpiece with a holding unit; a laser processing step of irradiating the workpiece held by the holding unit with a laser beam while relatively moving a focal point of the laser beam along the intended processing line, thereby forming a laser processed groove; The laser-processed groove has two deep groove portions at both ends in the width direction that are deeper than the central portion in the width direction, and a shallow groove portion sandwiched between the deep groove portions.

2. The processing method according to claim 1 , wherein the shallow groove portion has a bottom portion having an uneven surface.

3. 3. The processing method according to claim 1, further comprising a positioning step of shaping a laser beam generated by an oscillator with a diffractive optical element before carrying out the laser processing step, and positioning a focal point of the laser beam shaped by the diffractive optical element on the intended processing line of the workpiece held by the holding unit.

4. a holding unit for holding the workpiece; an oscillator; a diffractive optical element for shaping the laser beam generated by the oscillator; a condenser having a condenser lens that condenses the laser beam shaped by the diffractive optical element onto the workpiece held by the holding unit; a moving unit that moves a focal point of the laser beam focused by the focusing device relative to the workpiece held by the holding unit to form a laser-processed groove in the workpiece, The diffractive optical element is a laser processing device that shapes the laser beam so that the laser-processed groove has two deep groove portions that are deeper at both ends in the width direction than at the center in the width direction, and a shallow groove portion sandwiched between the deep groove portions.

5. 5. The laser processing device according to claim 4, wherein the diffractive optical element shapes the laser beam so that unevenness is formed at the bottom of the shallow groove.

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