Laser processing device and laser processing method

Abstract

To form an energy distribution of a laser beam into a top-hat distribution while suppressing loss of the laser beam.SOLUTION: A laser processing device 1 is provided with: an oscillator 22; an aspheric cylindrical lens 27 that forms an energy distribution of a laser beam 21 into a top-hat distribution without shielding the laser beam 21 emitted from the oscillator 22; a mask 28 that shields a portion of the laser beam 21 formed into the top-hat distribution by the aspheric cylindrical lens 27; and a condensing unit 26 having a condensing lens 261 that condenses the laser beam 21 passing through the mask 28 onto a work-piece 200.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] When dividing a device wafer, in order to prevent peeling of the low-k dielectric film (Low-K film) on the surface, a laser beam is irradiated to form a laser-processed groove, which is then cut with a cutting blade.

[0003] Furthermore, the energy distribution of the laser beam emitted from the oscillator is shaped into a top-hat distribution by a mask (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-072174 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the groove bottom of a laser-machined groove is not flat, the cutting blade may bend during cutting, potentially damaging the device. Therefore, in the conventional method shown in Patent Document 1, in order to flatten the groove bottom of a laser-machined groove, only the central part of a laser beam with a Gaussian energy distribution is passed through a mask, thereby shaping the energy distribution of the laser beam into a top-hat distribution. However, since most of the laser beam emitted from the oscillator is blocked by the mask, significant loss occurs, and improvements such as reducing loss have been eagerly sought.

[0006] An object of the present invention is to provide a laser processing apparatus and a laser processing method that can shape the energy distribution of a laser beam into a top-hat distribution while suppressing loss of the laser beam. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the laser processing apparatus of the present invention is characterized by comprising: an oscillator; a shaping unit that shapes the energy distribution of the laser beam emitted from the oscillator into a top hat distribution without blocking the laser beam; a mask that blocks a portion of the laser beam that has been shaped into a top hat distribution by the shaping unit; and a focusing unit having a focusing lens that focuses the laser beam that has passed through the mask onto a workpiece.

[0008] The laser processing apparatus may further include a scanning unit that moves the focal point, where the laser beam is focused by the focusing lens, relative to the workpiece in a first direction, and the scanning unit moves the focal point relative to the workpiece, thereby forming a laser-processed groove extending in the first direction in the workpiece. The shaping unit may shape the energy distribution of the laser beam in a second direction orthogonal to the first direction into a top hat distribution while leaving the energy distribution in the first direction as a Gaussian distribution, and the mask may block both ends in the second direction of the laser beam that has been shaped into a top hat distribution by the shaping unit.

[0009] In the laser processing apparatus, the shaping unit may be made of an aspherical cylindrical lens.

[0010] In the laser processing apparatus, the aspherical cylindrical lens may include a first surface having a shape that shapes the energy distribution of the laser beam emitted from the oscillator into a top hat distribution, and a second surface having a shape that converts the laser beam shaped into a top hat distribution into a parallel beam.

[0011] In the laser processing device, the shaping unit may be made of a diffractive optical element.

[0012] The laser processing method of the present invention is characterized in that a laser beam emitted from an oscillator is shaped into a top-hat distribution by a shaping unit without blocking the energy distribution of the laser beam, a portion of the laser beam shaped into a top-hat distribution by the shaping unit is blocked by a mask, and the laser beam that has passed through the mask is focused onto the workpiece by a focusing unit having a focusing lens, thereby performing laser processing on the workpiece.

[0013] In the laser processing method, the focusing point of the laser beam focused on the workpiece by the focusing unit is moved in a first direction relative to the workpiece, thereby forming a laser-processed groove in the workpiece that extends in the first direction, and the shaping unit may shape the energy distribution of the laser beam in a second direction perpendicular to the first direction into a top-hat distribution while leaving the energy distribution in the first direction as a Gaussian distribution, and the mask may block both ends in the second direction of the laser beam that has been shaped into a top-hat distribution by the shaping unit.

[0014] In the laser processing method, the shaping unit may be made of an aspherical cylindrical lens.

[0015] In the laser processing method, the aspherical cylindrical lens may include a first surface having a shape that shapes the energy distribution of the laser beam emitted from the oscillator into a top hat distribution, and a second surface having a shape that converts the laser beam shaped into a top hat distribution into a parallel beam.

[0016] In the laser processing method, the shaping unit may be made of a diffractive optical element. [Effects of the Invention]

[0017] The present invention has the effect of being able to shape the energy distribution of a laser beam into a top-hat distribution while suppressing loss of the laser beam. [Brief explanation of the drawings]

[0018] [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 energy distribution in the Y-axis direction of the laser beam reflected by the mirror 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 that has passed through the aspherical cylindrical lens of the laser beam irradiation unit shown in FIG. [Figure 6] FIG. 6 is a diagram showing the energy distribution in the Y-axis direction of the laser beam that has passed through the mask of the laser beam irradiation unit shown in FIG. [Figure 7] FIG. 7 is a diagram schematically showing a beam spot and the like of the laser beam irradiation unit shown in FIG. [Figure 8] FIG. 8 is a flowchart showing the flow of the laser processing method according to the first embodiment. [Figure 9] FIG. 9 is a diagram schematically showing a protective film forming step of the laser processing method shown in FIG. [Figure 10] FIG. 10 is a side view, partly in section, showing a state in which two first laser-processed grooves are formed on both ends of each planned dividing line in the laser processing step of the laser processing method shown in FIG. [Figure 11] FIG. 11 is a plan view showing a main part of a workpiece in which two first laser-processed grooves are formed on both ends of each planned dividing line in the laser processing step of the laser processing method shown in FIG. [Figure 12] 12 is a side view, partly in section, showing a state in which second laser-processed grooves are formed in the centers of the respective planned dividing lines in the laser processing step of the laser processing method shown in FIG. [Figure 13]FIG. 13 is a plan view showing a main part of a workpiece in which second laser-processed grooves are formed in the centers of the respective planned dividing lines in the laser processing step of the laser processing method shown in FIG. [Figure 14] FIG. 14 is a diagram schematically showing the protective film removing step of the laser processing method shown in FIG. [Figure 15] FIG. 15 is a side view, partially in section, schematically showing the dividing step of the laser processing method shown in FIG. [Figure 16] FIG. 16 is a diagram showing the configuration of a laser beam irradiation unit of a laser processing apparatus according to the second embodiment. [Figure 17] FIG. 17 is a diagram showing the energy distribution in the Y-axis direction of the laser beam reflected by the mirror of the laser beam irradiation unit shown in FIG. [Figure 18] FIG. 18 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 19] FIG. 19 is a diagram showing the energy distribution in the Y-axis direction of the laser beam transmitted through the mask of the laser beam irradiation unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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.

[0020] [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. FIG. 3 is a view showing the configuration of a laser beam irradiation unit of the laser processing apparatus shown in FIG. 2. FIG. 4 is a view showing the energy distribution in the Y-axis direction of a laser beam reflected by a mirror of the laser beam irradiation unit shown in FIG. 3. FIG. 5 is a view showing the energy distribution in the Y-axis direction of a laser beam transmitted through an aspherical cylindrical lens of the laser beam irradiation unit shown in FIG. 3. FIG. 6 is a view showing the energy distribution in the Y-axis direction of a laser beam transmitted through a mask of the laser beam irradiation unit shown in FIG. 3. FIG. 7 is a view schematically showing the beam spot and the like of the laser beam irradiation unit shown in FIG. 3.

[0021] (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, the substrate of which is, for example, a silicon substrate, a sapphire substrate, a gallium substrate, a SiC substrate, or the like.

[0022] In the first embodiment, as shown in Fig. 2, a workpiece 200 has a surface 201 on which a plurality of devices 203 are formed in regions defined by a plurality of mutually intersecting planned division lines 202. The devices 203 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).

[0023] In the first embodiment, the workpiece 200 has a central portion of a tape 205 attached to a back surface 204 behind the front surface 201, the tape 205 having a diameter larger than the workpiece 200 and an annular frame 206 attached to its outer edge, and the workpiece 200 is supported within an opening on the inside of the frame 206. In the present invention, the workpiece 200 is not limited to being attached to the tape 205.

[0024] (Laser processing equipment) As shown in FIG. 1, the laser processing apparatus 1 of embodiment 1 includes a holding table 10, a moving unit 30, a first laser beam irradiation unit 20-1 (shown in FIG. 10), 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.

[0025] The holding table 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 table 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 where the workpiece 200 is carried in and out.

[0026] The holding table 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 table 10 sucks and holds the back surface 204 of the workpiece 200 via tape 205. Also, as shown in FIG. 1, a plurality of clamps 12 for clamping a frame 206 are provided around the periphery of the holding table 10.

[0027] The moving unit 30 moves the holding table 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 table 10 in the Y-axis direction, which is a second direction parallel to the horizontal direction, an X-axis moving unit 32, which is a processing feed unit that moves the holding table 10 in the X-axis direction, which is a first direction parallel to the horizontal direction and perpendicular to the Y-axis direction, and a rotational moving unit 33 that rotates the holding table 10 around an axis parallel to the Z-axis direction, which is parallel to the vertical direction.

[0028] The Y-axis moving unit 31 is installed in the apparatus 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 table 10 in the Y-axis direction. The X-axis moving unit 32 is a scanning unit that moves the focal point 214 (shown in FIG. 3) where the laser beam 21 is focused by the focusing lens 261 relative to the workpiece 200 in the X-axis direction.

[0029] The X-axis movement unit 32 is mounted on the moving plate 3, and moves the second moving plate 4, on which the rotational movement unit 33 is mounted, in the X-axis direction, thereby moving the holding table 10 in the X-axis direction. The rotational movement unit 33 is mounted on the second moving plate 4, and supports the holding table 10, thereby rotating the holding table 10 about its axis.

[0030] The Y-axis movement unit 31 moves each of the moving plates 3, the X-axis movement unit 32, the second moving plate 4, the rotational movement unit 33, and the holding table 10 in the Y-axis direction. The X-axis movement unit 32 moves each of the second moving plate 4, the rotational movement unit 33, and the holding table 10 in the X-axis direction.

[0031] The Y-axis moving unit 31 and the X-axis moving unit 32 each include a well-known ball screw rotatably mounted about its axis, a well-known motor for rotating the ball screw about its axis, and well-known guide rails for supporting the moving plates 3 and 4 movably in the X-axis or Y-axis direction. The rotational moving unit 33 includes a well-known motor for rotating the holding table 10 about its axis.

[0032] As shown in FIG. 1, the laser beam irradiation units 20-1 and 20-2 are partially provided at the tips of support columns 6, the base ends of which are supported by upright walls 5 erected from the end of the apparatus 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 by irradiating a workpiece 200 held on a holding table 10 with a laser beam 21. In the first embodiment, the shape of the beam spot at the focal point 214 of the laser beam 21 of the first laser beam irradiation unit 20-1 is circular. As shown in FIG. 3, the second laser beam irradiation unit 20-2 includes an oscillator 22, an output adjustment unit 23, a mirror 24, an aspherical cylindrical lens 27 serving as a shaping unit, a mask 28, and a focusing unit 26.

[0033] The oscillator 22 is a device that oscillates a laser beam 21 having a wavelength that is absorbed by the workpiece 200. 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 mirror 24 reflects the laser beam 21, the output of which has been adjusted by the output adjustment unit 23, to the focusing unit 26. The energy distribution of the laser beam 21 reflected by the mirror 24 in the X-axis and Y-axis directions is a Gaussian distribution 211 (Gaussian-type distribution), as shown in FIG. 4. In FIG. 4, the horizontal axis indicates the position in the X-axis and Y-axis directions, 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 aspherical cylindrical lens 27 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 212 (top hat type distribution) as shown in Fig. 5 without blocking the laser beam 21 emitted from the oscillator 22 and reflected by the mirror 24, and keeps the energy distribution of the laser beam 21 in the X-axis direction as a Gaussian distribution 211. The aspherical cylindrical lens 27 has a first surface 271 on the mirror 24 side and a second surface 272 on the mask 28 side formed into an aspherical curved surface.

[0035] The aspherical cylindrical lens 27 has a first surface 271 shaped to shape the energy distribution in the Y-axis direction of the laser beam 21, which is emitted from the oscillator 22 and reflected by the mirror 24, into a top-hat distribution 212 as shown in Fig. 5, and to maintain the energy distribution in the X-axis direction of the laser beam 21 as a Gaussian distribution 211 as shown in Fig. 4. The aspherical cylindrical lens 27 has a second surface 272 shaped to convert the laser beam 21, which has been shaped into the top-hat distribution 212, into parallel light. Thus, the aspherical cylindrical lens 27 includes a first surface 271 and a second surface 272.

[0036] The energy distribution in the Y-axis direction of the laser beam 21 that has passed through the aspherical cylindrical lens 27 is a top-hat distribution 212, as shown in Fig. 5. In Fig. 5, 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.

[0037] The mask 28 blocks a portion of the laser beam 21 that has been shaped into the top hat distribution 212 by the aspherical cylindrical lens 27. The mask 28 has an opening 281 that transmits the laser beam 21, whose longitudinal direction is parallel to the Y-axis direction and whose lateral direction is parallel to the X-axis direction. The mask 28 blocks both ends in the Y-axis direction of the laser beam 21 that has been shaped into the top hat distribution 212 by the aspherical cylindrical lens 27, and transmits the remainder of the laser beam 21.

[0038] For this reason, the energy distribution in the Y-axis direction of laser beam 21 that has passed through mask 28 becomes top-hat distribution 213, as shown in Fig. 6, in which both ends in the Y-axis direction of top-hat distribution 212 shown in Fig. 5 have been removed. In Fig. 6, the horizontal axis represents the position in the Y-axis direction, and the vertical axis represents the energy of laser beam 21. The center of the horizontal axis represents optical axis 210 of laser beam 21.

[0039] The focusing unit 26 includes a focusing lens 261 that focuses the laser beam 21 that has passed through the mask 28 onto the workpiece 200, and an imaging lens 262. The imaging lens 262 transmits the laser beam 21 that has passed through the mask 28 toward the focusing lens 261, and makes the position of the laser beam 21 immediately after passing through the mask 28 conjugate with the focal point 214 of the laser beam 21 that is irradiated onto the workpiece 200.

[0040] 7, the second laser beam irradiation unit 20-2 can form a beam spot 215 at a focal point 214 on the surface 201 of the workpiece 200 such that the longitudinal direction is parallel to the Y-axis direction and the lateral direction is parallel to the X-axis direction. The second laser beam irradiation unit 20-2 sets the energy distribution of the beam spot 215 in the X-axis direction to a Gaussian distribution 211, and sets the energy distribution of the beam spot 215 in the Y-axis direction to a top-hat distribution 213.

[0041] In the present invention, the second laser beam irradiation unit 20-2 may be configured such that the first surface 271 is shaped to shape the laser beam into a top hat distribution 212 and the second surface 272 is an aspherical cylindrical lens 27 that is not shaped to collimate the laser beam, to shape the energy distribution of the laser beam 21 in the Y-axis direction into the top hat distribution 212, and a collimating lens is disposed between the aspherical cylindrical lens 27 and the mask 28 or between the mask 28 and the condenser lens 261 to collimate the laser beam 21 whose energy distribution in the Y-axis direction has been shaped into the top hat distribution 212.

[0042] When placing a collimating lens, adjustment is required so that the generatrix of the aspherical cylindrical lens 27 coincides with the generatrix of the collimating lens, but by giving the aspherical cylindrical lens 27 a collimating function, this adjustment can be made unnecessary.

[0043] The imaging unit includes an imaging element that images an area to be divided of the workpiece 200 held on the holding table 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 on the holding table 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.

[0044] Protective film forming and cleaning unit 40 forms a protective film (not shown) on surface 201 of workpiece 200 before laser processing, and cleans workpiece 200 after laser processing to remove the protective film. Protective film forming and cleaning unit 40 is disc-shaped and includes spinner table 41, which has a flat holding surface formed of porous ceramic or the like along the horizontal direction for holding workpiece 200, coating nozzle 42, and cleaning nozzle 43 (shown in FIG. 9). Spinner table 41 is rotated about an axis parallel to the Z-axis direction by a rotation drive source (not shown).

[0045] 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 204 of workpiece 200 via tape 205. In addition, a plurality of clamps 44 that clamp frame 206 are provided around spinner table 41.

[0046] Coating nozzle 42 applies a liquid water-soluble resin 45 (e.g., HogoMax (registered trademark) manufactured by Disco Corporation) such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) to surface 201 of workpiece 200 held by spinner table 41, and dries liquid water-soluble resin 45 to coat the entire surface 201 of workpiece 200 with a protective film. Cleaning nozzle 43 supplies cleaning water (pure water in the first embodiment) to surface 201 of workpiece 200 held by spinner table 41 to remove the protective film and clean surface 201 of workpiece 200.

[0047] The transport unit 50 transports the workpiece 200 between the holding table 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 table 10 and the protective film forming and cleaning unit 40.

[0048] 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.

[0049] 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.

[0050] (Laser processing method) Next, a laser processing method according to embodiment 1 will be described. Fig. 8 is a flowchart showing the flow of the laser processing method according to embodiment 1. The laser processing method according to embodiment 1 is a method of laser processing a workpiece 200 and dividing the workpiece 200 into individual devices 203. As shown in Fig. 8, the laser processing method according to embodiment 1 includes a protective film forming step 1001, a laser processing step 1002, a protective film removing step 1003, and a dividing step 1004.

[0051] (Protective film formation step) Fig. 9 is a diagram schematically showing the protective film forming step of the laser processing method shown in Fig. 8. Protective film forming step 1001 is a step of coating a protective film on surface 201 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 205, and control unit 100 receives an instruction to start the processing operation from the operator or the like.

[0052] In the protective film forming step 1001, the laser processing apparatus 1 according to the first embodiment suction-holds the back surface 204 of the workpiece 200 on the holding surface of the spinner table 41 via the tape 205, clamps the frame 206 with the clamp unit 44, rotates the spinner table 41 about its axis, and drips liquid water-soluble resin 45 from the coating nozzle 42 onto the center of the front surface 201 of the workpiece 200. The dripped water-soluble resin 45 flows from the center toward the outer periphery on the front surface 201 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 201 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 about its axis, dries the water-soluble resin 45, and coats the front surface 201 of the workpiece 200 with a protective film.

[0053] (Laser processing step) Fig. 10 is a side view, partially in cross section, showing the state in which two first laser-processed grooves are formed at both ends of each planned dividing line in the laser processing step of the laser processing method shown in Fig. 8. Fig. 11 is a plan view showing a main part of a workpiece in which two first laser-processed grooves are formed at both ends of each planned dividing line in the laser processing step of the laser processing method shown in Fig. 8. Fig. 12 is a side view, partially in cross section, showing the state in which second laser-processed grooves are formed in the centers of each planned dividing line in the laser processing step of the laser processing method shown in Fig. 8. Fig. 13 is a plan view showing a main part of a workpiece in which second laser-processed grooves are formed in the centers of each planned dividing line in the laser processing step of the laser processing method shown in Fig. 8.

[0054] The laser processing step 1002 is a step in which laser processing is performed on the front surface 201 side of each planned division line 202 of the workpiece 200. In the laser processing step 1002, the control unit 100 of the laser processing apparatus 1 stops the rotation of the spinner table 41 around its axis and the suction holding of the holding surface, and stops clamping of the frame 206 of the clamp section 44. In the laser processing step 1002, 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 table 10.

[0055] In the first embodiment, in the laser processing step 1002, the control unit 100 of the laser processing apparatus 1 controls the vacuum suction source to suck and hold the back surface 204 side of the workpiece 200 to the holding surface 11 of the holding table 10 via the tape 205, exposing the front surface 201 side of the workpiece 200, and clamps the frame 206 with the clamp section 12. In the first embodiment, in the laser processing step 1002, the control unit 100 of the laser processing apparatus 1 controls the moving unit 30 to move the holding table 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] 10, in the laser processing step 1002, 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 table 10 in the X-axis direction while setting the focal point 214 of the laser beam 21 on the surface 201 of the workpiece 200, and the first laser beam application unit 20-1 irradiates both ends in the width direction of the surface 201 of each planned division line 202 of the workpiece 200 with the laser beam 21. In the laser processing step 1002 in the embodiment 1, the laser processing apparatus 1 irradiates both ends in the width direction of all planned division lines 202 of the workpiece 200 held on the holding table 10 with the laser beam 21, thereby forming two first laser-processed grooves 220 on each planned division line 202, as shown in FIG.

[0057] In embodiment 1, in the laser processing step 1002, as shown in FIG. 12, the control unit 100 of the laser processing apparatus 1 controls the second laser beam application unit 20-2 and the moving unit 30, etc. to move the second laser beam application unit 20-2 and the holding table 10 relatively in the X-axis direction while setting the focal point 214 of the laser beam 21 on the surface 201 of the workpiece 200, and the second laser beam application unit 20-2 irradiates the laser beam 21 at the center in the width direction of the surface 201 of each planned division line 202 of the workpiece 200. In embodiment 1, in the laser processing step 1002, the laser processing apparatus 1 irradiates the laser beam 21 onto the center of the width of all of the planned division lines 202 of the workpiece 200 held on the holding table 10, and forms a second laser processing groove 221 that straddles two first laser processing grooves 220 on each planned division line 202, as shown in Figure 13, and forms a laser processing groove 222 consisting of the first laser processing groove 220 and the second laser processing groove 221 on each planned division line 202.

[0058] (Protection film removal step) Fig. 14 is a diagram schematically showing the protective film removing step of the laser processing method shown in Fig. 8. Protective film removing step 1003 is a step of removing the protective film from surface 201 of workpiece 200. In protective film removing step 1003, in laser processing apparatus 1, control unit 100 controls movement unit 30 and the like to move holding table 10 to the loading / unloading area, stops suction holding of holding surface 11 of holding table 10 in the loading / unloading area, and stops clamping of frame 206 of clamp unit 12.

[0059] In protective film removing step 1003, the control unit 100 of the laser processing apparatus 1 controls the transport unit 50 to place the workpiece 200 from the holding table 10 onto the holding surface of the spinner table 41. In protective film removing step 1003, the laser processing apparatus 1 according to the first embodiment suction-holds the back surface 204 of the workpiece 200 onto the holding surface of the spinner table 41 via the tape 205, clamps the frame 206 with the clamp unit 44, rotates the spinner table 41 around its axis, and drips liquid cleaning water 46 from the cleaning nozzle 43 onto the center of the front surface 201 of the workpiece 200. The dripped cleaning water 46 flows from the center toward the outer periphery over the front surface 201 of the workpiece 200 due to centrifugal force generated by the rotation of the spinner table 41, washing away the protective film on the front surface 201 of the workpiece 200 and cleaning the front surface 201 of the workpiece 200. In the protective film removing step 1003, 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 201 of the workpiece 200.

[0060] (Split Step) Fig. 15 is a side view, partially in cross section, schematically showing the dividing step of the laser processing method shown in Fig. 2. Dividing step 1004 is a step of dividing workpiece 200 into individual devices 203. In embodiment 1, in dividing step 1004, cutting device 60 shown in Fig. 15 suction-holds back surface 204 of workpiece 200 to holding surface 62 of chuck table 61 via tape 205, and clamps frame 206 with clamping section 63 around chuck table 61.

[0061] In embodiment 1, in the dividing step 1004, the cutting device 60, as shown in FIG. 15, moves the chuck table 61 and the cutting blade 64, which rotates around its axis by the spindle of the cutting unit, relatively along the planned dividing lines 202, and cuts the cutting blade 64 into the bottom of the laser-processed grooves 222 formed on each planned dividing line 202 from the surface 201 side of the workpiece 200 until it reaches the tape 205, thereby dividing the workpiece 200 into individual devices 203.

[0062] As described above, the laser processing apparatus 1 and the laser processing method according to the first embodiment shape the energy distribution in the Y-axis direction of the laser beam 21 into the top hat distribution 212 by the aspherical cylindrical lens 27 without blocking the laser beam 21 emitted from the oscillator 22, thereby achieving the effect of being able to shape the energy distribution in the Y-axis direction of the laser beam 21 into the top hat distribution 212 while suppressing loss of the laser beam 21.

[0063] Furthermore, in the laser processing apparatus 1 and the laser processing method according to the first embodiment, a portion of the laser beam 21, whose energy distribution in the Y-axis direction has been shaped into a top-hat distribution 212, is blocked by the mask 28, so that the bottom surface of the laser-processed groove 222 can be formed flat and the inner surface can be formed approximately vertically.

[0064] [Embodiment 2] A laser processing apparatus according to a second embodiment will be described with reference to the drawings. Fig. 16 is a diagram showing the configuration of a laser beam irradiation unit of a laser processing apparatus according to the second embodiment. Fig. 17 is a diagram showing the energy distribution in the Y-axis direction of a laser beam reflected by a mirror of the laser beam irradiation unit shown in Fig. 16. Fig. 18 is a diagram showing the energy distribution in the Y-axis direction of a laser beam transmitted through a diffractive optical element of the laser beam irradiation unit shown in Fig. 16. Fig. 19 is a diagram showing the energy distribution in the Y-axis direction of a laser beam transmitted through a mask of the laser beam irradiation unit shown in Fig. 16. In Figs. 16, 17, 18 and 19, the same parts as those of the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0065] The laser processing apparatus 1 according to the second embodiment is the same as that according to the first embodiment, except that the second laser beam irradiation unit 20-2 includes a diffractive optical element 29, which is a shaping unit, instead of the aspherical cylindrical lens 27, as shown in FIG. 16. In the second embodiment, as in the first embodiment, the energy distribution in the X-axis and Y-axis directions of the laser beam 21 reflected by the mirror 24 is a Gaussian distribution 211-2, as shown in FIG. 17. In FIG. 17, the horizontal axis indicates the position in the X-axis and Y-axis directions, 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.

[0066] The diffractive optical element 29 shapes the energy distribution of the laser beam 21 in the Y-axis direction into a top hat distribution 212-2 without blocking the laser beam 21 emitted from the oscillator 22 and reflected by the mirror 24, and keeps the energy distribution of the laser beam 21 in the X-axis direction as a Gaussian distribution 211-2. The diffractive optical element 29 shapes the energy distribution of the laser beam 21 in the Y-axis direction, emitted from the oscillator 22 and reflected by the mirror 24, into a top hat distribution 212-2 as shown in Fig. 17, and keeps the energy distribution of the laser beam 21 in the X-axis direction as a Gaussian distribution 211-2 as shown in Fig. 16.

[0067] The energy distribution in the Y-axis direction of the laser beam 21 that has passed through the diffractive optical element 29 is a top-hat distribution 212-2, as shown in Fig. 18. In Fig. 18, 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.

[0068] The mask 28 blocks a portion of the laser beam 21 that has been shaped into the top hat distribution 212-2 by the diffractive optical element 29. The mask 28 has an opening 281 that transmits the laser beam 21, whose longitudinal direction is parallel to the Y-axis direction and whose lateral direction is parallel to the X-axis direction. The mask 28 blocks both ends in the Y-axis direction of the laser beam 21 that has been shaped into the top hat distribution 212-2 by the diffractive optical element 29, and transmits the remainder of the laser beam 21.

[0069] For this reason, the energy distribution in the Y-axis direction of laser beam 21 that has passed through mask 28 becomes, as shown in Fig. 19, a top hat distribution 213-2 in which both ends in the Y-axis direction of top hat distribution 212-2 shown in Fig. 18 have been removed. In Fig. 19, the horizontal axis represents the position in the Y-axis direction, and the vertical axis represents the energy of laser beam 21. The center of the horizontal axis represents optical axis 210 of laser beam 21.

[0070] The laser processing apparatus 1 and the laser processing method according to the second embodiment use the diffractive optical element 29 to shape the energy distribution in the Y-axis direction into a top hat distribution 212-2 without blocking the laser beam 21 emitted from the oscillator 22, and therefore have the effect of being able to shape the energy distribution in the Y-axis direction of the laser beam 21 into a top hat distribution 212-2 while suppressing loss of the laser beam 21, similar to the first embodiment.

[0071] 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]

[0072] 1. Laser processing equipment 21 Laser beam 22 Oscillator 26 Light collecting unit 27 Aspherical cylindrical lens (shaping unit) 28 Mask 29 Diffractive optical element (shaping unit) 32 X-axis direction movement unit (scanning unit) 200 Workpiece 211,211-2 Gaussian distribution 212,212-2,213,213-2 Top-hat distribution 214 Focus point 222 Laser-machined groove 261 Condenser Lens 271 First Side 272 Second Side X 1st direction Y Second direction

Claims

1. an oscillator; a shaping unit that shapes the energy distribution of the laser beam emitted from the oscillator into a top-hat distribution without blocking the laser beam; a mask for blocking a part of the laser beam shaped into a top-hat distribution by the shaping unit; a focusing unit having a focusing lens for focusing the laser beam that has passed through the mask onto the workpiece;

2. a scanning unit that moves a focal point of the laser beam focused by the focusing lens relative to the workpiece in a first direction; The scanning unit moves the focal point relative to the workpiece, thereby forming a laser-processed groove extending in the first direction in the workpiece; the shaping unit shapes the energy distribution of the laser beam in a second direction perpendicular to the first direction into a top hat shape while leaving the energy distribution in the first direction as a Gaussian distribution; 2. The laser processing apparatus according to claim 1, wherein the mask blocks both ends in the second direction of the laser beam shaped into a top-hat distribution by the shaping unit.

3. 3. The laser processing device according to claim 1, wherein the shaping unit comprises an aspherical cylindrical lens.

4. the aspherical cylindrical lens has a first surface having a shape that shapes the energy distribution of the laser beam emitted from the oscillator into a top-hat distribution; 4. The laser processing device according to claim 3, further comprising: a second surface having a shape that converts the laser beam shaped into a top-hat distribution into a parallel beam.

5. 3. The laser processing device according to claim 1, wherein the shaping unit comprises a diffractive optical element.

6. shaping the energy distribution of the laser beam emitted from the oscillator into a top hat distribution by a shaping unit without blocking the laser beam; a mask is used to block a portion of the laser beam shaped into a top-hat distribution by the shaping unit; The laser beam that has passed through the mask is focused onto the workpiece by a focusing unit having a focusing lens, thereby performing laser processing on the workpiece.

7. a focusing point of the laser beam focused on the workpiece by the focusing unit is moved in a first direction relative to the workpiece, thereby forming a laser-processed groove in the workpiece that extends in the first direction; the shaping unit shapes the energy distribution of the laser beam in a second direction perpendicular to the first direction into a top-hat distribution while leaving the energy distribution in the first direction as a Gaussian distribution; 7. The laser processing method according to claim 6, wherein the mask blocks both ends in the second direction of the laser beam shaped into a top-hat distribution by the shaping unit.

8. 8. The laser processing method according to claim 6, wherein the shaping unit comprises an aspherical cylindrical lens.

9. the aspherical cylindrical lens has a first surface having a shape that shapes the energy distribution of the laser beam emitted from the oscillator into a top-hat distribution; The laser processing method according to claim 8, further comprising: a second surface having a shape that converts the laser beam shaped into a top-hat distribution into parallel light.

10. 8. The laser processing method according to claim 6, wherein the shaping unit comprises a diffractive optical element.

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