Laser processing apparatus and method of adjusting phase pattern

Abstract

A laser processing apparatus and a method for adjusting the phase pattern are provided, which can suppress performance differences of the laser beams irradiating the workpiece between processing devices, thereby achieving the desired processing result. The laser processing apparatus includes a laser beam irradiation unit that irradiates the workpiece with a laser beam and a control unit. The laser beam irradiation unit includes: a laser oscillator that oscillates laser light; a focusing lens; a concave mirror that has a focal point at the focusing point of the focusing lens and has a spherical reflecting surface; a beam splitter that allows the laser beam emitted from the laser oscillator to pass through the focusing lens and branches the reflected light; and a wavefront measurement unit that receives the reflected light and acquires the wavefront data of the laser beam. The control unit changes the phase pattern displayed on the display unit of a spatial light modulator based on the wavefront data.

Description

Technical Field

[0001] This invention relates to a laser processing apparatus and a method for adjusting the phase pattern. Background Technology

[0002] In order to divide a plate-shaped object such as a semiconductor wafer into chip sizes, there are known laser processing methods that irradiate a laser beam along a predetermined dividing line of the plate-shaped object to form a modified layer as the dividing starting point (for example, see Patent Document 1).

[0003] However, in the optical system of a laser processing apparatus that performs the aforementioned laser processing, various optical distortions occur in the optical path from the laser oscillator to the condenser lens due to the use of various optical components, sometimes resulting in differences in processing results between processing apparatuses.

[0004] Therefore, the following technique has been proposed: using a chuck stage to hold a concave mirror and photographing the light reflected from the concave mirror to determine the shape of the light spot at the processing point (for example, see Patent Document 2). However, in the technique shown in Patent Document 2, even if the shape of the light spot can be determined, it is not known where the optical deformation occurs in the laser oscillator or multiple optical elements, so the operation of determining the location of the deformation is time-consuming.

[0005] In addition, a technique for compensating for wavefront deformation using wavefront sensors and spatial light modulators has been proposed (for example, see Patent Document 3).

[0006] Patent Document 1: Japanese Patent No. 3408805

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-41437

[0008] Patent Document 3: Japanese Patent Application Publication No. 2014-236795

[0009] However, in the technology shown in Patent Document 3, since the measurement is not performed using a focusing lens, it may differ from the actual processing point and may not be able to fully compensate for the performance differences of the laser beams irradiating the workpiece between devices. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a laser processing apparatus and a method for adjusting the phase pattern that can suppress performance differences of laser beams irradiating a workpiece between processing devices and obtain desired processing results.

[0011] According to one aspect of the invention, a laser processing apparatus is provided, comprising: a chuck stage for holding a workpiece; a laser beam irradiation unit for irradiating a laser beam onto the workpiece held by the chuck stage; and a control unit, the laser beam irradiation unit comprising: a laser oscillator for oscillating laser light; a focusing lens for focusing the laser beam emitted from the laser oscillator; a concave mirror positioned to have a focal point at the focusing point of the focusing lens, wherein the reflecting surface of the concave mirror reflecting the laser beam is spherical; and a beam splitter. It directs the laser beam emitted from the laser oscillator to the focusing lens and branches the reflected light that is focused by the focusing lens and reflected by the reflecting surface of the concave mirror; and a wavefront measurement unit receives the reflected light that is reflected by the reflecting surface of the concave mirror and branched by the beam splitter, and obtains wavefront data as the spatial distribution of the phase of the laser beam. The control unit changes the phase pattern displayed on the display unit of the spatial light modulator disposed between the laser oscillator and the focusing lens according to the wavefront data measured by the wavefront measurement unit.

[0012] Preferably, the concave mirror is disposed on the periphery of the chuck table.

[0013] Preferably, the control unit further includes: a calculation unit that performs a Zernike polynomial approximation on the wavefront data, which is the spatial distribution of the phase of the laser beam measured by the wavefront measurement unit, to calculate the Zernike coefficients; a phase pattern generation unit that generates a phase pattern having predetermined Zernike coefficients and displays the phase pattern on the display unit of the spatial light modulator; and a storage unit that pre-stores the correlation between the Zernike coefficients input into the phase pattern and the Zernike coefficients of the laser beam measured by the wavefront measurement unit when the phase pattern with the input Zernike coefficients is displayed on the display unit of the spatial light modulator, and performs an inverse operation on the Zernike coefficients in the phase pattern displayed on the display unit according to the table of correlation stored in the storage unit, so that the Zernike coefficients of the laser beam measured by the wavefront measurement unit are the desired values.

[0014] Preferably, the control unit further includes: a calculation unit that performs a Zernike polynomial approximation on the wavefront data, which is the spatial distribution of the phase of the laser beam measured by the wavefront measurement unit, to calculate the Zernike coefficients; a phase pattern generation unit that generates a phase pattern with predetermined Zernike coefficients and displays the phase pattern on the display unit of the spatial light modulator; a modification unit that modifies any one of the multiple Zernike coefficients of the wavefront data obtained by the wavefront measurement unit; and a determination unit that determines whether the wavefront data measured by the wavefront measurement unit is close to ideal wavefront data. The laser oscillator continuously emits a laser beam, and alternately repeats the actions of the modification unit modifying any one of the Zernike coefficients and the phase pattern generation unit displaying the phase pattern with the modified Zernike coefficients on the display unit of the spatial light modulator, until the determination unit determines that the wavefront data measured by the wavefront measurement unit is close to ideal wavefront data.

[0015] According to another aspect of the present invention, a method for adjusting a phase pattern is provided, which is a method for adjusting a phase pattern displayed on a display section of a laser processing apparatus. The laser processing apparatus includes a laser beam irradiation unit that irradiates a workpiece held on a chuck table with a laser beam. The laser beam irradiation unit comprises: a laser oscillator that oscillates and emits laser light; a focusing lens that focuses the laser beam emitted from the laser oscillator; a concave mirror positioned to have a focal point at the focusing point of the focusing lens, and the reflecting surface of the concave mirror reflecting the laser beam is spherical; a beam splitter that directs the laser beam emitted from the laser oscillator to the focusing lens and branches the reflected light focused by the focusing lens and reflected by the reflecting surface of the concave mirror; and a wavefront determination unit that receives the reflected light reflected by the reflecting surface of the concave mirror and branched by the beam splitter, and obtains the spatial distribution of the phase of the laser beam. The method for adjusting the phase pattern includes the following steps: a Zernike coefficient input step, in which a phase pattern having a predetermined Zernike coefficient is displayed on the display of the spatial light modulator; a laser beam irradiation step, in which a laser beam is emitted from the laser oscillator and wavefront data is obtained through the wavefront measurement unit; and a Zernike coefficient adjustment step, in which any one of the Zernike coefficients of the wavefront data obtained by the wavefront measurement unit is changed, and a phase pattern having the changed Zernike coefficient is displayed on the display of the spatial light modulator, and the Zernike coefficient adjustment step is repeated until the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data.

[0016] Preferably, the phase pattern adjustment method further includes the following Zernike coefficient inverse operation step: based on a table showing the correlation between the Zernike coefficients input into the phase pattern and the Zernike coefficients of the laser beam measured by the wavefront measurement unit when the phase pattern with the input Zernike coefficients is displayed on the display unit of the spatial light modulator, the Zernike coefficients input into the phase pattern are inversely operated on, so that the Zernike coefficients of the laser beam measured by the wavefront measurement unit are the desired values.

[0017] The invention of this application has the following effect: it can suppress the performance difference of the laser beam irradiating the workpiece between processing devices, thereby obtaining the desired processing result. Attached Figure Description

[0018] Figure 1 This is a perspective view showing a structural example of the laser processing apparatus according to the first embodiment.

[0019] Figure 2 Yes Figure 1 The diagram illustrates the structure of the laser beam irradiation unit of the laser processing apparatus shown.

[0020] Figure 3 It is shown Figure 1 The figure shows an example of the Zernike coefficient of the reflected light from the laser beam, calculated by the calculation unit of the laser processing apparatus and measured by the wavefront measurement unit.

[0021] Figure 4 It is shown Figure 1 A diagram illustrating an example of the relationships stored in the storage unit of the laser processing apparatus.

[0022] Figure 5 Yes Figure 1 The flowchart illustrates the method for adjusting the phase pattern implemented by the laser processing apparatus shown.

[0023] Figure 6 It is shown Figure 1 The diagram shows an example of the beam profile of the reflected light from the laser beam when the wavefront measurement unit of the laser processing apparatus displays a phase pattern with Zernike coefficients of a specified value on the display unit.

[0024] Figure 7 It is shown as Figure 6 A graph showing an example of the Zernike coefficient values ​​for the wavefront data of the reflected light from a laser beam.

[0025] Figure 8 It shows through Figure 1 The phase pattern generation unit of the laser processing apparatus shown is from Figure 7The figure shown is an example of the values ​​of the Zernike coefficients as wavefront data of the reflected light from the laser beam, after the values ​​have been changed.

[0026] Figure 9 It shows having Figure 8 The phase pattern of the Zernike coefficients shown is an example of the beam profile of the reflected light from the laser beam when displayed on the display unit.

[0027] Figure 10 This is a perspective view showing a structural example of the laser processing apparatus according to the second embodiment.

[0028] Figure 11 This is a flowchart illustrating the phase pattern adjustment method of the second embodiment.

[0029] Figure 12 This is a perspective view showing a structural example of a laser processing apparatus modified according to the first embodiment.

[0030] Label Explanation

[0031] 1, 1-1, 1-2: Laser processing device; 10: Chuck table; 20: Laser beam irradiation unit; 21: Laser beam; 22: Laser oscillator; 23: Focusing lens; 24: Spatial light modulator; 25: Concave mirror; 26: Beam splitter (branching component); 28: Wavefront measurement unit; 100: Control unit; 101: Calculation unit; 102: Phase pattern generation unit; 103: Storage unit; 104: Modification unit; 105: Judgment unit; 200: Processed laser beam (SPL) Components; 211: Focusing point; 212: Reflected light; 241: Display unit; 251: Focal point; 252: Reflecting surface; 300: Correlation; 401, 402: Beam profile; 500, 501: Wavefront data (wavefront information as spatial distribution of phase); 502: Ideal wavefront data; ST2: Zernike coefficient input step; ST3: Laser beam irradiation step; ST4: Zernike coefficient adjustment step; ST6: Zernike coefficient inverse operation step. Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the structural elements described below include substantially the same structural elements that can be readily conceived by those skilled in the art. Moreover, the structures described below can be appropriately combined. In addition, various omissions, substitutions, or modifications to the structure can be made without departing from the spirit of the present invention.

[0033] [First Embodiment]

[0034] The laser processing apparatus of the first embodiment of the present invention will be described with reference to the accompanying drawings. First, the structure of the laser processing apparatus 1 will be described. Figure 1 This is a perspective view showing a structural example of the laser processing apparatus according to the first embodiment. (First Embodiment) Figure 1 The laser processing apparatus 1 shown is a device that performs laser processing on the workpiece 200 by irradiating the workpiece 200 with a pulsed laser beam 21.

[0035] As Figure 1 The workpiece 200 processed by the laser processing apparatus 1 shown is a wafer, such as a disc-shaped semiconductor wafer or optical device wafer, having a substrate 201 made of silicon, sapphire, gallium arsenide, etc. Figure 1 As shown, the workpiece 200 has pre-defined dividing lines 203 arranged in a grid pattern on the front side 202 of the substrate 201 and devices 204 formed in the regions divided by the pre-defined dividing lines 203. The devices 204 are, for example, integrated circuits such as IC (Integrated Circuit) or LSI (Large Scale Integration), image sensors such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor).

[0036] In the first embodiment, the workpiece 200 is supported within the opening of an annular frame 206 by an adhesive tape 207 adhered to the back side 205 of the front side 202. The adhesive tape 207 is a circular plate with a diameter larger than the outer diameter of the workpiece 200, and the annular frame 206 is adhered to its outer edge. In the first embodiment, the workpiece 200 is divided into individual components 204 along a predetermined dividing line 203.

[0037] (Laser processing equipment)

[0038] like Figure 1 As shown, the laser processing apparatus 1 includes a chuck table 10, a laser beam irradiation unit 20, a moving unit 30, an imaging unit 40, and a control unit 100. The chuck table 10 holds the workpiece 200 using a holding surface 11.

[0039] The chuck stage 10 holds the workpiece 200 using a holding surface 11. The chuck stage 10 is disc-shaped and includes: a disc-shaped suction part 12 made of porous ceramic or the like with multiple holes, having a flat holding surface 11 on its upper surface for holding the workpiece 200; and a frame 13 that embeds and fixes the suction part 12 into a central recess on the upper surface. The upper surface of the frame 13 is on the same plane as the holding surface 11. In the first embodiment, the upper surface of the frame 13 is the periphery of the chuck stage 10. The suction part 12 of the chuck stage 10 is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The chuck stage 10 attracts and holds the workpiece 200 placed on the holding surface 11. In the first embodiment, the holding surface 11 is a plane parallel to the horizontal direction. A plurality of clamping parts 14 are arranged around the chuck table 10, which clamp the workpiece 200 supported in the opening by the annular frame 206.

[0040] Furthermore, the chuck table 10 rotates about an axis parallel to the Z-axis direction via the rotary moving unit 34 of the moving unit 30. The Z-axis direction is perpendicular to the holding surface 11 and parallel to the vertical direction. The chuck table 10, together with the rotary moving unit 34, moves along the X-axis direction (parallel to the horizontal direction) via the X-axis moving unit 31 of the moving unit 30, and moves along the Y-axis direction (parallel to the horizontal direction and perpendicular to the X-axis direction) via the Y-axis moving unit 32.

[0041] The laser beam irradiation unit 20 irradiates the workpiece 200 held by the chuck stage 10 with a pulsed laser beam 21 of a wavelength that is transparent to the workpiece 200, forming a modified layer inside the workpiece 200 that serves as a fracture initiation point. The modified layer refers to a region whose density, refractive index, mechanical strength, and other physical properties differ from those of its surroundings. Examples of modified layers include melt-processed regions, cracked regions, insulation failure regions, regions with refractive index changes, and regions where these regions are mixed. In this embodiment, the mechanical strength of the modified layer is lower than that of other parts of the substrate 201.

[0042] Furthermore, in the first embodiment, the laser beam irradiation unit irradiates the workpiece 200 with a laser beam 21 of a wavelength that is transparent to the workpiece 200. However, in this invention, a laser beam 21 of a wavelength that is absorbent to the workpiece 200 may also be used to irradiate the workpiece 200, thereby performing an ablation process on the workpiece 200. In the first embodiment, as... Figure 1As shown, a portion of the laser beam irradiation unit 20 is supported by a lifting component 4, which moves along the Z-axis direction via a Z-axis moving unit 33 of a moving unit 30 mounted on an erected wall 3 that extends from the main body 2. The structure of the laser beam irradiation unit 20 will be described later.

[0043] The moving unit 30 moves the chuck table 10 and the laser beam irradiation unit 20 relative to each other along the X-axis, Y-axis, and Z-axis. Furthermore, the X-axis and Y-axis are parallel to the holding surface 11. The moving unit 30 includes: an X-axis moving unit 31, which serves as a machining feed member and moves the chuck table 10 along the X-axis; a Y-axis moving unit 32, which serves as an indexing feed member and moves the chuck table 10 along the Y-axis; a Z-axis moving unit 33, which moves the laser beam irradiation unit 20 along the Z-axis; and a rotational moving unit 34, which rotates the chuck table 10 about an axis parallel to the Z-axis.

[0044] In the first embodiment, the Y-axis moving unit 32 is mounted on the main body 2 of the laser processing apparatus 1. The Y-axis moving unit 32 supports the moving plate 15, which supports the X-axis moving unit 31, allowing it to move freely along the Y-axis direction. The X-axis moving unit 31 is mounted on the moving plate 15. The X-axis moving unit 31 supports a second moving plate 16, which is movable freely along the X-axis direction. This second moving plate 16 supports a rotary moving unit 34 that rotates the chuck table 10 about an axis parallel to the Z-axis direction. The Z-axis moving unit 33 is mounted on the vertical wall 3 and supports the lifting component 4, allowing it to move freely along the Z-axis direction.

[0045] The X-axis moving unit 31, Y-axis moving unit 32, and Z-axis moving unit 33 each have: a known ball screw rotatably disposed about an axis; a known pulse motor for rotating the ball screw about an axis; and known guide rails that support the moving plates 15 and 16 for free movement along the X-axis or Y-axis and support the lifting member 4 for free movement along the Z-axis.

[0046] Additionally, the laser processing apparatus 1 includes: an X-axis position detection unit (not shown) for detecting the position of the chuck table 10 in the X-axis direction; a Y-axis position detection unit (not shown) for detecting the position of the chuck table 10 in the Y-axis direction; and a Z-axis position detection unit for detecting the position of the laser beam irradiation unit 20 in the Z-axis direction. Each position detection unit outputs the detection results to the control unit 100.

[0047] The imaging unit 40 captures images of the workpiece 200 held by the chuck stage 10. The imaging unit 40 includes an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) imager for capturing images of the workpiece 200 held by the chuck stage 10. In the first embodiment, the imaging unit 40 is mounted at the front end of the housing of the laser beam irradiation unit 20 and is positioned adjacent to the laser beam irradiation unit 20. Figure 2 The position of the focusing lens 23 in the X-axis direction is shown. The imaging unit 40 captures an image of the workpiece 200 to obtain an image for aligning the workpiece 200 and the laser beam irradiation unit 20, and outputs the obtained image to the control unit 100.

[0048] The control unit 100 controls the aforementioned structural elements of the laser processing apparatus 1, causing the laser processing apparatus 1 to perform processing operations on the workpiece 200. Furthermore, the control unit 100 is a computer, comprising: an arithmetic processing unit having a microprocessor such as a CPU (central processing unit); a storage device having a memory such as ROM (read-only memory) or RAM (random access memory); and an input / output interface device. The arithmetic processing unit of the control unit 100 performs arithmetic processing according to the computer program stored in the storage device, and outputs control signals for controlling the laser processing apparatus 1 to the aforementioned structural elements of the laser processing apparatus 1 via the input / output interface device, thereby realizing the function of the control unit 100.

[0049] Additionally, the laser processing apparatus 1 includes: a display unit 110, which comprises a liquid crystal display device or the like that displaying the status or images of the processing operation; and an input unit (not shown), used when the operator registers processing content information, etc. The display unit 110 and the input unit are connected to the control unit 100. The input unit comprises at least one of an external input device such as a touch panel and a keyboard provided on the display unit 110.

[0050] Next, the laser beam irradiation unit 20 will be described. Figure 2 Yes Figure 1 The diagram illustrates the structure of the laser beam irradiation unit in the laser processing apparatus shown. (See diagram for example.) Figure 2As shown, the laser beam irradiation unit 20 includes: a laser oscillator 22 that oscillates to generate a laser for processing the workpiece 200; a focusing lens 23 that focuses the laser beam 21 emitted from the laser oscillator 22 onto the workpiece 200 held on the holding surface 11 of the chuck stage 10; a spatial light modulator 24; a concave mirror 25; a beam splitter 26 as a branching member; an attenuation member 27; a wavefront measurement unit 28; and a plurality of optical components 29.

[0051] The focusing lens 23 is positioned opposite the holding surface 11 of the chuck stage 10 in the Z-axis direction, allowing the laser beam 21 oscillating from the laser oscillator 22 to pass through, thereby focusing the laser beam 21 onto the focusing point 211.

[0052] A spatial light modulator 24 is disposed in the optical path of the laser beam 21 between the laser oscillator 22 and the condenser lens 23. It is a so-called LCOS-SLM (Liquid Crystal on Silicon-Spatial Light Modulator) that adjusts the optical characteristics of the laser beam 21 emitted from the laser oscillator 22 and emits a laser beam 21 with adjusted optical characteristics. In the first embodiment, the spatial light modulator 24 is a modulator that reflects the laser beam 21 emitted from the laser oscillator 22. In the first embodiment, the optical characteristics of the laser beam 21 adjusted by the spatial light modulator 24 are, for example, at least one of the phase, polarization plane, amplitude, intensity, and propagation direction of the laser beam 21.

[0053] In the first embodiment, the spatial light modulator 24 has a display unit 241. This display unit 241 is illuminated by a laser beam 21 emitted from a laser oscillator 22 and its optical characteristics are adjusted upon reflection of the laser beam 21. The spatial light modulator 24 emits the laser beam 21, whose optical characteristics have been adjusted by the display unit 241, towards a focusing lens 23 via a beam splitter 26, etc. Furthermore, in the first embodiment, the display unit 241 of the spatial light modulator 24 displays a phase pattern for adjusting the optical characteristics of the laser beam 21, and the optical characteristics of the laser beam 21 are adjusted by reflecting it. The phase pattern is controlled by a control unit 100. The spatial light modulator 24 adjusts the optical characteristics of the emitted laser beam 21 by controlling the phase pattern displayed on the display unit 241 by the control unit 100.

[0054] A concave mirror 25 is positioned to face the condenser lens 23 along the Z-axis, and has a reflective surface 252 that, when facing the condenser lens 23 along the Z-axis, can be positioned to have a focal point 251 at the focusing point 211 of the condenser lens 23. In the first embodiment, the concave mirror 25 is disposed within the frame 13 of the chuck stage 10, and the reflective surface 252 is positioned to face the condenser lens 23 along the Z-axis. In the first embodiment, the Z-axis position of the condenser lens 23 is adjusted by the Z-axis movement unit 33 so that the focusing point 211 of the condenser lens 23 is located at the focal point 251, thereby positioning the focal point 251 of the reflective surface 252 at the focusing point 211 of the condenser lens 23. The reflective surface 252 is spherical and reflects the laser beam 21 emitted from the condenser lens 23 facing the Z-axis towards the condenser lens 23.

[0055] Beam splitter 26 directs the laser beam 21, which is emitted from laser oscillator 22 and whose optical properties have been adjusted by spatial light modulator 24, toward condenser lens 23. Beam splitter 26 also directs the reflected light 212 of the laser beam 21, which has been focused by condenser lens 23 and reflected by the reflecting surface 252 of concave mirror 25 and has passed through condenser lens 23, toward attenuation member 27, thus branching the laser beam 21.

[0056] The attenuation member 27 is used to attenuate the intensity of the reflected light 212 reflected by the beam splitter 26. In the first embodiment, the attenuation member 27 attenuates the intensity of the reflected light 212 and reflects it toward the wavefront measurement unit 28. The attenuation member 27 is, for example, made of a wedge-shaped substrate.

[0057] The wavefront measurement unit 28 receives the reflected light 212, which is reflected by the reflecting surface 252 of the concave mirror 25, branched from the laser beam 21 by the beam splitter 26, and whose intensity is attenuated by the attenuation member 27. By performing measurement, it obtains information 500 on the wavefront, which is the spatial distribution of the phase of the laser beam 21. Figure 2 As shown (hereinafter referred to as wavefront data). The wavefront measurement unit 28 is a so-called wavefront sensor that measures the wavefront shape, intensity distribution, and especially the aberrations of the wavefront of the reflected light 212 of the laser beam 21, as well as the wavefront data 500. The wavefront measurement unit 28 outputs the measured wavefront data 500 of the reflected light 212 of the laser beam 21 to the control unit 100.

[0058] Optical component 29 propagates the laser beam 21 emitted from laser oscillator 22 toward the processing point or concave mirror 25 that processes the workpiece 200, and propagates the reflected light 212 of the laser beam 21 reflected by the reflecting surface 252 of the concave mirror 25 toward wavefront measurement unit 28. In the first embodiment, optical component 29 includes a beam expander 29-1, a reflector 29-2, and a wavelength plate 29-3 disposed in the optical path of the laser beam 21 between laser oscillator 22 and spatial light modulator 24. In the first embodiment, beam expander 29-1, reflector 29-2, and wavelength plate 29-3 are arranged sequentially from laser oscillator 22 toward spatial light modulator 24. In addition, optical component 29 includes: a relay optical system 29-4 disposed in the optical path of the laser beam 21 between spatial light modulator 24 and beam splitter 26; and a reflector 29-5 disposed in the optical path of the laser beam 21 between beam splitter 26 and condenser lens 23.

[0059] In addition, such as Figure 1 As shown, the control unit 100 of the laser processing apparatus 1 in the first embodiment includes a calculation unit 101, a phase pattern generation unit 102, and a storage unit 103. Next, the structural elements of the control unit 100 will be described. Figure 3 It is shown Figure 1 The figure shows an example of the Zernike coefficient of the reflected light from the laser beam, calculated by the calculation unit of the laser processing apparatus and measured by the wavefront measurement unit. Figure 4 It is shown Figure 1 A diagram illustrating an example of the relationships stored in the storage unit of the laser processing apparatus.

[0060] The calculation unit 101 approximates the wavefront data 500 of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28 using Zernike polynomials, and calculates each Zernike coefficient. Furthermore, a Zernike polynomial refers to an orthogonal polynomial defined on the unit circle. The Zernike coefficients are values ​​calculated using the Zernike polynomial approximated by the wavefront data 500 of the reflected light 212 of the laser beam 21, and are used to correspond one-to-one with the aberrations of the optical system of the laser beam irradiation unit 20. The calculation unit 101 approximates the wavefront data 500 of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28 using the Zernike polynomial, and calculates the Zernike coefficients using the approximate Zernike polynomial. Figure 3 The Zernike coefficients are shown, thus quantifying the Zernike coefficients. Additionally, Figure 3 The horizontal axis represents the Zernike coefficients, and the vertical axis represents the values ​​of the Zernike coefficients. Figure 3In the equation, the Zernike coefficients “Astig 0_deg” and “Astig 45_deg” correspond to astigmatism, the Zernike coefficients “coma X” and “coma Y” correspond to coma, and the Zernike coefficient “spherical aberr” corresponds to spherical aberration.

[0061] Storage unit 103 pre-stores Figure 4 The correlation shown is 300. Figure 4 The correlation 300 shown is obtained by correlating the Zernike coefficient value in the phase pattern displayed on the display unit 241 of the spatial light modulator 24 with the Zernike coefficient value calculated by the calculation unit 101 based on the wavefront data 500 of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28 when the phase pattern with the input Zernike coefficient is displayed on the display unit 241 of the spatial light modulator 24. Figure 4 The horizontal axis represents the Zernike coefficient value in the phase pattern displayed by the display unit 241 of the spatial light modulator 24. Figure 4 The vertical axis represents the value of the Zernike coefficient calculated by the calculation unit 101 based on the wavefront data 500 of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28 when a phase pattern with the input Zernike coefficient is displayed on the display unit 241 of the spatial light modulator 24.

[0062] Storage unit 103 stores data according to each Zernike coefficient, i.e., each aberration. Figure 4 The correlation 300 is shown. That is, the storage unit 103 stores the same number of Zernike coefficients, i.e., aberrations of the optical system, calculated by the Zernike polynomial. Figure 4 The example shown is a correlation of 300. Additionally, Figure 4 The correlation 300 shown corresponds to the correlation at 0° astigmatism. Regarding correlation 300, by displaying a phase pattern with predetermined values ​​as Zernike coefficients on the display unit 241 of the spatial light modulator 24, the laser beam 21 emitted from the laser oscillator 22 is calculated by the calculation unit 101 based on the wavefront data 500 of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28, thereby... Figure 4 The values ​​of each Zernike coefficient shown on the phase pattern displayed on the display unit 241, as shown on the horizontal axis, are... Figure 4The calculation unit 101, shown on the central axis, calculates the correlation relationships 300 in advance based on the values ​​of each Zernike coefficient calculated from the wavefront data 500 obtained by the wavefront measurement unit 28, and stores them in the storage unit 103. Furthermore, in the first embodiment, the storage unit 103 stores the correlation relationships 300 according to each Zernike coefficient, i.e., each aberration. However, in this invention, where it is possible to adjust all aberrations without using the correlation relationships 300, for example, when only 0° astigmatism needs to be corrected, only the correlation relationships 300 corresponding to 0° astigmatism need to be stored. That is, in this invention, the storage unit 103 only needs to store information corresponding to the aberrations adjusted using the correlation relationships 300, and it is not necessary to store the same number of correlation relationships 300 as the aberrations.

[0063] The phase pattern generation unit 102 generates a phase pattern having Zernike coefficients with predetermined values ​​input from the input unit, and displays the generated phase pattern on the display unit 241 of the spatial light modulator 24. The phase pattern generation unit 102 receives predetermined values ​​for each Zernike coefficient input from the input unit, and when it receives all the Zernike coefficient values, it generates a phase pattern having the received Zernike coefficient values. The phase pattern generation unit 102 displays the generated phase pattern on the display unit 241.

[0064] Furthermore, when the operator manipulates the input unit to change the value of any Zernike coefficient and receives the changed Zernike coefficient value, the phase pattern generation unit 102 generates a phase pattern of the Zernike coefficient with the changed value and displays it on the display unit 241. Additionally, the phase pattern generation unit 102 also uses data stored in the storage unit 103... Figure 4 The table of correlation 300, as illustrated, performs an inverse operation on the Zernike coefficients in the phase pattern input to the display unit 241, so that each Zernike coefficient of the reflected light 212 of the laser beam 21 measured by the wavefront measurement unit 28 is a desired value. Furthermore, the phase pattern generation unit 102 generates a phase pattern with the inversely operated Zernike coefficients, changing the phase pattern displayed on the display unit 241 to the generated phase pattern.

[0065] Furthermore, the functions of the storage unit 103 are implemented through a storage device. The functions of the calculation unit 101 and the phase pattern generation unit 102 are implemented by an arithmetic processing device performing arithmetic processing according to a computer program stored in the storage device.

[0066] When the operator registers the processing content information in the control unit 100 and places the workpiece 200 on the holding surface 11 of the chuck table 10 through the adhesive tape 207, and the control unit 100 receives the operator's processing action start instruction from the input unit, the laser processing apparatus 1 starts the processing action according to the registered processing content information.

[0067] During the processing operation, the laser processing apparatus 1 attracts and holds the workpiece 200 on the holding surface 11 of the chuck table 10 through the adhesive tape 207, and clamps the annular frame 206 using the clamping part 14. Next, the moving unit 30 moves the chuck table 10 downwards toward the imaging unit 40, which then takes an image of the workpiece 200. The laser processing apparatus 1 performs alignment based on the image captured by the imaging unit 40.

[0068] According to the processing content information, the laser processing apparatus 1 moves the laser beam irradiation unit 20 and the workpiece 200 relative to each other along the predetermined dividing line 203 via the moving unit 30, irradiating a pulsed laser beam 21 from the laser beam irradiation unit 20 towards the predetermined dividing line 203. In the first embodiment, the laser processing apparatus 1 irradiates the laser beam 21, forming a modified layer inside the substrate 201 along the predetermined dividing line 203. When the modified layer is formed inside the substrate 201 along all the predetermined dividing lines 203, the laser processing apparatus 1 stops irradiating the laser beam 21 and ends the processing operation.

[0069] Before the laser processing apparatus 1 begins processing, it performs the following method for adjusting the phase pattern. The method for adjusting the phase pattern will now be explained. Figure 5 Yes Figure 1 The flowchart illustrates the method for adjusting the phase pattern implemented by the laser processing apparatus shown. Figure 6 It is shown Figure 1 The diagram shows an example of the beam profile of the reflected light from the laser beam when the wavefront measurement unit of the laser processing apparatus displays a phase pattern with Zernike coefficients of a specified value on the display unit. Figure 7 It is shown as Figure 6 A graph showing an example of the Zernike coefficient values ​​for the wavefront data of the reflected light from a laser beam. Figure 8 It shows through Figure 1 The phase pattern generation unit of the laser processing apparatus shown is from Figure 7 The figure shown is an example of the values ​​of the Zernike coefficients as wavefront data of a laser beam after the values ​​have been changed. Figure 9 It displays on the display unit that has Figure 8 The figure shows an example of the beam profile of the reflected light from a laser beam when the phase pattern of the Zernike coefficient is shown.

[0070] The phase pattern is adjusted by making the wavefront data 500 of the laser beam 21 measured by the wavefront measurement unit 28 close to the ideal wavefront data 502 (in Figure 8(Example shown) A method for adjusting the phase pattern displayed on the display unit 241 of the spatial light modulator 24 to an ideal phase pattern that can irradiate the laser beam 21, which can achieve an ideal processing result at the processing point during the processing operation. Furthermore, the ideal wavefront data 502 refers to the wavefront data obtained by the wavefront measurement unit 28 upon receiving the laser beam 21, which can achieve an ideal processing result at the processing point during the processing operation. Additionally, the Zernike coefficient values ​​of the ideal wavefront data 502 are the expected values ​​of each Zernike coefficient. For example... Figure 5 As shown, the phase pattern adjustment method includes a preparation step ST1, a Zernike coefficient input step ST2, a laser beam irradiation step ST3, a Zernike coefficient adjustment step ST4, and a Zernike coefficient inverse operation step ST6.

[0071] Preparation step ST1 involves storing the Zernike coefficient values ​​of the ideal wavefront data 502 in the storage unit 103 and aligning the focusing lens 23 of the laser beam irradiation unit 20 with the reflecting surface 252 of the concave mirror 25. In the first embodiment, in preparation step ST1, the control unit 100 controls the X-axis movement unit 31 and the Y-axis movement unit 32 to align the focusing lens 23 of the laser beam irradiation unit 20 with the reflecting surface 252 of the concave mirror 25 along the Z-axis direction, and controls the Z-axis movement unit 33 to position the focusing point 211 of the focusing lens 23 at the focal point 251 of the reflecting surface 252.

[0072] In addition, in the preparation step ST1, the control unit 100 accepts the operator's operation on the input unit and stores the values ​​of each Zernike coefficient of the ideal wavefront data 502 in the storage unit 103.

[0073] The Zernike coefficient input step ST2 is a step of inputting a predetermined Zernike coefficient value and displaying a phase pattern of the Zernike coefficients with the input predetermined value on the display unit 241. In the Zernike coefficient input step ST2, the control unit 100 receives the operator's operation on the input unit and stores each Zernike coefficient with the predetermined value. Furthermore, in the first embodiment, the predetermined value is arbitrary. In the Zernike coefficient input step ST2, when the phase pattern generation unit 102 receives all the Zernike coefficient values, it generates a phase pattern of the Zernike coefficients with the received values. In the Zernike coefficient input step ST2, the phase pattern generation unit 102 displays the generated phase pattern on the display unit 241.

[0074] The laser beam irradiation step ST3 is as follows: A laser beam 21 is emitted from the laser oscillator 22, and the laser beam 21, whose optical characteristics have been adjusted by a phase pattern having a Zernike coefficient with a predetermined value input in the Zernike coefficient input step ST2, is irradiated onto the reflecting surface 252 of the concave mirror 25. Wavefront data 500 is obtained by the wavefront measurement unit 28. In the laser beam irradiation step ST3, with the phase pattern generation unit 102 displaying the phase pattern generated in the Zernike coefficient input step ST2 on the display unit 241, the laser beam 21 is emitted from the laser oscillator 22, and the laser beam 21 emitted from the laser oscillator 22 is irradiated onto the reflecting surface 252 of the concave mirror 25 via the spatial light modulator 24, the beam splitter 26, and the condenser lens 23. The optical characteristics of the laser beam 21 irradiating the reflecting surface 252 are adjusted by the phase pattern generated by the phase pattern generation unit 102 and displayed on the display unit 241.

[0075] In the laser beam irradiation step ST3, the reflected light 212 of the laser beam 21, reflected by the reflecting surface 252, is reflected towards the attenuation member 27 via the beam splitter 26 and received by the wavefront measurement unit 28. In the laser beam irradiation step ST3, the wavefront data 500 of the reflected light 212 of the laser beam 21 received by the wavefront measurement unit 28 is acquired and output to the control unit 100. In the laser beam irradiation step ST3, the calculation unit 101 of the control unit 100 performs a Zernike polynomial approximation on the wavefront data 500 acquired by the wavefront measurement unit 28, calculates the values ​​of each Zernike coefficient, and quantifies them, thereby... Figure 3 The wavefront data 500 shown is displayed on the display unit 110. Additionally, the laser oscillator 22 then emits a laser beam 21 at a predetermined repetition frequency until the phase pattern adjustment method is completed.

[0076] Zernike coefficient adjustment step ST4 involves changing the value of any one of the multiple Zernike coefficients in the wavefront data 500 obtained by the wavefront measurement unit 28, and displaying a phase pattern of the Zernike coefficient with the changed value on the display unit 241. In Zernike coefficient adjustment step ST4, the operator confirms the wavefront data 500 displayed on the display unit 110, operates the input unit to change the value of any one of the multiple Zernike coefficients in the wavefront data 500, and inputs the changed value. In Zernike coefficient adjustment step ST4, when the phase pattern generation unit 102 of the control unit 100 receives the changed Zernike coefficient value, it generates a phase pattern of the Zernike coefficient with the changed value and displays it on the display unit 241.

[0077] In the Zernike coefficient adjustment step ST4, the reflected light 212 of a laser beam 21, whose optical properties have been adjusted by a phase pattern of Zernike coefficients with values ​​changed by the wavefront measurement unit 28, is received, and wavefront data 500 of the received reflected light 212 of the laser beam 21 is obtained. In the Zernike coefficient adjustment step ST4, the calculation unit 101 calculates the values ​​of each Zernike coefficient in the wavefront data 500, and the control unit 100 displays the obtained values ​​of each Zernike coefficient in the wavefront data 500 on the display unit 110. Furthermore, among the Zernike coefficients calculated by the calculation unit 101 using a Zernike polynomial approximation of the wavefront data 500 obtained by the wavefront measurement unit 28, the values ​​of Zernike coefficients other than those whose values ​​have been changed also change.

[0078] The operator determines whether the values ​​of each Zernike coefficient of the wavefront data 500 displayed on the display unit 110 are close to the expected values ​​(step ST5). If the operator determines that the values ​​of each Zernike coefficient of the wavefront data 500 displayed on the display unit 110 are not close to the expected values, it is determined that the adjustment of the values ​​of each Zernike coefficient of the wavefront data 500 is not yet complete (step ST5: No), and returns to the Zernike coefficient adjustment step ST4. Conversely, if the values ​​of each Zernike coefficient are close to the expected values, such as... Figure 7 As shown, the wavefront data 501 obtained by the wavefront measurement unit 28 is close to the ideal wavefront data 502.

[0079] When the operator determines that the values ​​of each Zernike coefficient of the wavefront data 501 displayed on the display unit 110 are close to the expected values, it is determined that the adjustment of the values ​​of each Zernike coefficient of the wavefront data 501 is roughly completed (step ST5: Yes), and the operator proceeds to the inverse operation step ST6 of the Zernike coefficient.

[0080] Thus, in the Zernike coefficient adjustment step ST4, firstly, when the value of any Zernike coefficient is adjusted to the desired value, among the Zernike coefficients calculated by the calculation unit 101 using a Zernike polynomial approximation of the wavefront data 500 obtained by the wavefront measurement unit 28, the Zernike coefficients other than the changed Zernike coefficient also change. Therefore, the phase pattern adjustment method of the first embodiment repeatedly performs the operation of adjusting arbitrary Zernike coefficients one by one and the operation of the wavefront measurement unit 28 obtaining the wavefront data 500 of the reflected light 212 of the laser beam 21, until the value of each Zernike coefficient of the laser beam 21 obtained by the wavefront measurement unit 28 approaches the value of each Zernike coefficient of the ideal wavefront data 502 stored in the storage unit 103 by repeatedly performing the Zernike coefficient adjustment step ST4. Thus, the phase pattern adjustment method of the first embodiment repeatedly performs the Zernike coefficient adjustment step ST4 until the wavefront data 500 obtained by the wavefront measurement unit 28 approaches the ideal wavefront data 502. In addition, Figure 6The beam profile 401 shown was obtained in the wavefront measurement unit 28. Figure 7 The wavefront data shown was obtained along with time 501.

[0081] The Zernike coefficient inverse calculation step ST6 is a step in which the control unit 100 performs an inverse calculation on the values ​​of each Zernike coefficient input into the phase pattern according to the table of correlation 300, so that the values ​​of each Zernike coefficient of the reflected light 212 measured by the wavefront measurement unit 28 are the values ​​of each Zernike coefficient of the ideal wavefront data 502, i.e., the desired values. Specifically, in the Zernike coefficient inverse calculation step ST6, the operator operates the input unit to select the Zernike coefficient whose value is adjusted, and when the control unit 100 receives the selected Zernike coefficient, the phase pattern generation unit 102 calculates... Figure 7 The Zernike coefficient values ​​shown are approximately the difference between the adjusted wavefront data 501 and the Zernike coefficient values ​​corresponding to the selected aberrations, and the expected values. This difference is then input into the [database / system / database ... Figure 4 The vertical axis of the correlation 300 is shown as an example.

[0082] In the Zernike coefficient inverse calculation step ST6, the phase pattern generation unit 102 calculates the value of the horizontal axis corresponding to the difference from the desired value, and calculates the value of the horizontal axis as the value of each Zernike coefficient of the ideal wavefront data 502. In the Zernike coefficient inverse calculation step ST6, the phase pattern generation unit 102 changes the value of the selected Zernike coefficient input into the phase pattern to the calculated value. Figure 4 The value of the horizontal axis is used to end the phase pattern adjustment method.

[0083] For example, in the Zernike coefficient inverse operation step ST6, when the phase pattern generation unit 102 selects astigmatism 0°, such as Figure 8 As shown, when the expected value of the Zernike coefficient corresponding to 0° astigmatism is "0", Figure 7 The Zernike coefficient corresponding to 0° astigmatism is shown as "-0.037", therefore, the difference between the expected value of the Zernike coefficient corresponding to 0° astigmatism is calculated as "+0.037".

[0084] The phase pattern generation unit 102 inputs "+0.037" to... Figure 4 In the Zernike coefficient values ​​of the vertical axis of the correlation 300 shown, the Zernike coefficient value of the horizontal axis corresponding to "+0.037" on the vertical axis is calculated to be "0.65". Thus, in the Zernike coefficient inverse calculation step ST6, the phase pattern generation unit 102 calculates the Zernike coefficient value corresponding to the astigmatism 0° of the ideal wavefront data 502, which is the desired value. In the Zernike coefficient inverse calculation step ST6, the phase pattern generation unit 102 changes the Zernike coefficient value input to the phase pattern corresponding to astigmatism 0° to the value using... Figure 4The correlation 300 shown yielded a value of "0.65".

[0085] As described above, when the phase pattern generation unit 102 sets the Zernike coefficients of the laser beam 21 obtained by the wavefront measurement unit 28 to the values ​​of the Zernike coefficients of the ideal wavefront data 502 based on the correlation 300 stored in the storage unit 103, the phase pattern adjustment method ends. Additionally, the wavefront measurement unit 28 receives the reflected light 212 of the laser beam 21 whose phase pattern has been adjusted through the Zernike coefficient inverse calculation step ST6. Figure 8 The ideal wavefront data 502 is shown, and is obtained along with it. Figure 9 The beam profile 402 shown is output to the control unit 100. The laser processing apparatus 1 displays a phase pattern with each Zernike coefficient having a value changed by the phase pattern generation unit 102 on the display unit 241 and performs the above-mentioned processing operation.

[0086] Furthermore, in the phase pattern adjustment method of the first embodiment, when repeatedly performing the Zernike coefficient adjustment step ST4, the values ​​of all Zernike coefficients may be adjusted sequentially one by one, or it may not be necessary to adjust the values ​​of all Zernike coefficients sequentially one by one. Additionally, in the phase pattern adjustment method of the first embodiment, when repeatedly performing the Zernike coefficient adjustment step ST4, the values ​​of each Zernike coefficient may be adjusted only once, or the values ​​of each Zernike coefficient may be adjusted multiple times.

[0087] Furthermore, in the phase pattern adjustment method of the first embodiment, it is preferable that the Zernike coefficient of the inverse operation value in the Zernike coefficient inverse operation step ST6 is less than the number of times the Zernike coefficient adjustment step ST4 is repeated, for example, once or twice.

[0088] As explained above, the laser processing apparatus 1 of the first embodiment includes: a beam splitter 26 that branches the reflected light 212 of the laser beam 21; a wavefront measurement unit 28 that receives the reflected light 212 of the laser beam 21 after being branched by the beam splitter 26; and a calculation unit 101. Therefore, it is possible to calculate the Zernike coefficients of the wavefront data 500, 501, 502 of the laser beam 21 at the processing point (i.e., the wavefront data 500, 501, 502 of the laser beam 21 that have passed through all the optical systems of the laser processing apparatus 1), thereby enabling the wavefront data 500, 501, 502 of the laser beam 21 to be processed into numerical values. As a result, the laser processing apparatus 1 is capable of quantitatively measuring the wavefront data 500, 501, 502 of the laser beam 21.

[0089] Furthermore, the laser processing apparatus 1 of the first embodiment includes a phase pattern generation unit 102. This phase pattern generation unit 102 performs an inverse operation on the Zernike coefficient values ​​in the phase pattern displayed on the display unit 241 based on the correlation 300 stored in the storage unit 103, so that the Zernike coefficient values ​​of each laser beam 21 obtained by the wavefront measurement unit 28 are the values ​​of each Zernike coefficient of the ideal wavefront data 502. Therefore, the laser processing apparatus 1 can change the phase pattern displayed on the display unit 241 of the spatial light modulator 24 according to the wavefront data 500 of the reflected light 212, thereby forming a laser beam 21 with ideal wavefront data 502 at the processing point, which can suppress the performance differences of the laser beams 21 irradiating the workpiece 200 between laser processing apparatuses 1.

[0090] Therefore, the laser processing apparatus 1 has the following effect: it can suppress the performance difference of the laser beam 21 irradiating the workpiece 200 between the laser processing apparatus 1, thereby obtaining the desired processing result.

[0091] Furthermore, the wavefront measurement unit 28 of the laser processing apparatus 1 receives reflected light 212 that passes through the condenser lens 23, is not transmitted through the workpiece 200, is reflected by the back surface 205, and is reflected by the reflecting surface 252 of the concave mirror 25. As a result, the laser processing apparatus 1 obtains the wavefront data 500 of the laser beam 21 that passes through all optical systems of the laser beam irradiation unit 20 but does not pass through (or through restricted) items other than the optical systems of the laser beam irradiation unit 20. As a result, the laser processing apparatus 1 is able to accurately perform quantitative measurement of the wavefront data 500 of the laser beam 21 of the laser beam irradiation unit 20.

[0092] In the phase pattern adjustment method of the first embodiment, since the Zernike coefficient adjustment step ST4 is repeated until the wavefront data 500 obtained by the wavefront measurement unit 28 is close to the ideal wavefront data 502, the performance difference of the laser beam 21 irradiating the workpiece 200 between the laser processing devices 1 is suppressed.

[0093] In addition, the phase pattern adjustment method of the first embodiment has the following Zernike coefficient inverse operation step ST6: the Zernike coefficients in the phase pattern input to the display unit 241 are inversely operated according to the table of correlation 300, so that the Zernike coefficients of the laser beam 21 obtained by the wavefront measurement unit 28 are the desired values, thus achieving the effect of forming an ideal wavefront data 502 laser beam 21 at the processing point.

[0094] [Second Implementation]

[0095] The laser processing apparatus and phase pattern adjustment method of the second embodiment of the present invention will be described with reference to the accompanying drawings. Figure 10 This is a perspective view showing a structural example of the laser processing apparatus according to the second embodiment. Figure 11 This is a flowchart illustrating the phase pattern adjustment method of the second embodiment. Additionally, in Figure 10 and Figure 11 In this document, the parts that are the same as those in the first embodiment are marked with the same reference numerals and the descriptions are omitted.

[0096] In the laser processing apparatus 1-2 of the second embodiment, as Figure 10 As shown, the control unit 100 has a modification unit 104 and a determination unit 105. Except for the modification unit 104, i.e., the control unit 100, executing the Zernike coefficient adjustment step ST4, and the determination unit 105, i.e. the control unit 100, executing the step ST5, the other parts are the same as in the first embodiment.

[0097] The modification unit 104 modifies any one of the multiple Zernike coefficients of the wavefront data 500 obtained by the wavefront measurement unit 28. The determination unit 105 determines whether the wavefront data 500 measured by the wavefront measurement unit 28 is close to the ideal wavefront data 502. The functions of the modification unit 104 and the determination unit 105 are realized by the arithmetic processing device performing arithmetic processing according to the computer program stored in the storage device.

[0098] Furthermore, the phase pattern generation unit 102 of the control unit 100 of the laser processing apparatus 1-2 in the second embodiment is the same as that in the first embodiment, generating a phase pattern with Zernike coefficients having predetermined values ​​and displaying the generated phase pattern on the display unit 241 of the spatial light modulator 24. The phase pattern generation unit 102 receives predetermined values ​​for each Zernike coefficient input from the input unit, and when it receives the values ​​of all Zernike coefficients, it generates a phase pattern with the received Zernike coefficient values. The phase pattern generation unit 102 displays the generated phase pattern on the display unit 241. Additionally, when the changing unit 104 changes the value of any one Zernike coefficient, the phase pattern generation unit 102 of the second embodiment generates a phase pattern with the changed Zernike coefficient value and displays it on the display unit 241.

[0099] like Figure 11 As shown, the Zernike coefficient adjustment step ST4 of the phase pattern adjustment method in the second embodiment includes a Zernike coefficient selection step ST41 and a Zernike coefficient modification step ST42. The Zernike coefficient selection step ST41 is a step in which the modification unit 104 selects any one of the multiple Zernike coefficients of the wavefront data 500 obtained by the wavefront measurement unit 28.

[0100] In the second embodiment, in the Zernike coefficient selection step ST41, the Zernike coefficient with the largest difference from the Zernike coefficient of the wavefront data 500 obtained by the wavefront measurement unit 28, calculated by the calculation unit 101, is selected as an arbitrary Zernike coefficient. Furthermore, in the Zernike coefficient selection step ST41, it is not limited to selecting the Zernike coefficient with the largest difference as an arbitrary Zernike coefficient; the present invention may also select the Zernike coefficient that has the greatest impact on processing as an arbitrary Zernike coefficient.

[0101] The Zernike coefficient modification step ST42 is a step of modifying the value of any Zernike coefficient selected by the modification unit 104. In the second embodiment, in the Zernike coefficient modification step ST42, the Zernike coefficient selected by the modification unit 104 is modified to the Zernike coefficient value of the ideal wavefront data 502. Therefore, in the Zernike coefficient modification step ST42, the phase pattern generation unit 102 of the control unit 100 generates a phase pattern with the modified Zernike coefficient value and displays it on the display unit 241.

[0102] In the Zernike coefficient modification step ST42, the wavefront measurement unit 28 receives the reflected light 212 of the laser beam 21, whose optical properties have been adjusted by a phase pattern with modified Zernike coefficient values, and obtains the wavefront data 500 of the received reflected light 212 of the laser beam 21. In the Zernike coefficient modification step ST42, the calculation unit 101 calculates the values ​​of each Zernike coefficient in the wavefront data 500, and the control unit 100 displays the obtained values ​​of each Zernike coefficient in the wavefront data 500 on the display unit 110.

[0103] The determination unit 105 of the control unit 100 determines whether the values ​​of each Zernike coefficient of the wavefront data 500 calculated by the calculation unit 101 are close to the expected values, thereby determining whether the wavefront data 500 measured by the wavefront measurement unit 28 and calculated by the calculation unit 101 is close to the ideal wavefront data 502 (step ST5). In the second embodiment, the determination unit 105 calculates the difference between the values ​​of each Zernike coefficient of the wavefront data 500 calculated by the calculation unit 101 and the values ​​of each Zernike coefficient of the ideal wavefront data 502, and calculates the sum of the differences. When it is determined that the sum of the calculated differences exceeds a predetermined value, it is determined that the wavefront data 500 measured by the wavefront measurement unit 28 is not close to the ideal wavefront data 502 (step ST5: No), and returns to the Zernike coefficient selection step ST41. In this way, the laser processing apparatus 1-2 of the second embodiment continuously emits a laser beam 21 from the laser oscillator 22, and alternately repeats the operation of the modification unit 104 changing any one of the Zernike coefficients and the operation of the phase pattern generation unit 102 displaying the phase pattern with the modified Zernike coefficients on the display unit 241 of the spatial light modulator 24, until the determination unit 105 determines that the wavefront data 500, 501 measured by the wavefront measurement unit 28 is close to the ideal wavefront data 502.

[0104] Furthermore, in step ST5, the determination is not limited to the sum of the differences between the Zernike coefficients and the Zernike coefficients of the ideal wavefront data 502. The present invention can also determine the value of the selected Zernike coefficients by whether the difference between the value of the ideal coefficient and the value of the actual coefficient is below a predetermined value and whether the sum of the differences is below a predetermined value. In this case, if the difference between the value of the ideal coefficient and the value of the actual coefficient is below a predetermined value and the sum of the differences is below a predetermined value, then the wavefront data 501 measured by the wavefront measurement unit 28 is determined to be close to the ideal wavefront data 502. If the difference between the value of the ideal coefficient and the value of the actual coefficient exceeds a predetermined value or the sum of the differences exceeds a predetermined value, then the wavefront data 501 measured by the wavefront measurement unit 28 is determined to be not close to the ideal wavefront data 502.

[0105] In the second embodiment, when it is determined that the sum of the calculated differences is below a predetermined value, the determination unit 105 determines that the wavefront data 501 measured by the wavefront measurement unit 28 is close to the ideal wavefront data 502 (step ST5: Yes), and proceeds to the Zernike coefficient inverse calculation step ST6. In the second embodiment, in the Zernike coefficient inverse calculation step ST6, the phase pattern generation unit 102 of the control unit 100 selects the Zernike coefficient with the largest difference from the Zernike coefficient value of the ideal wavefront data 502 as the Zernike coefficient for value adjustment, and uses it... Figure 4The example shown is related relationship 300, and the value is adjusted in the same way as in the first embodiment.

[0106] In the laser processing apparatus 1-2 and the phase pattern adjustment method of the second embodiment, the beam splitter 26, the wavefront measurement unit 28 and the calculation unit 101 are similar to those in the first embodiment. Therefore, the Zernike coefficients of the wavefront data 500, 501, 502 of the laser beam 21 at the processing point (i.e., the wavefront data 500, 501, 502 of the laser beam 21 that has passed through all the optical systems of the laser processing apparatus 1) can be calculated, thereby enabling quantitative measurement of the wavefront data 500, 501, 502 of the laser beam 21.

[0107] Furthermore, in the laser processing apparatus 1-2 of the second embodiment, the laser oscillator 22 continuously emits a laser beam 21, and alternately repeats the operation of the modification unit 104 changing any one of the Zernike coefficients and the operation of the phase pattern generation unit 102 displaying the phase pattern with the modified Zernike coefficients on the display unit 241 of the spatial light modulator 24, until the determination unit 105 determines that the wavefront data 500, 501 measured by the wavefront measurement unit 28 is close to the ideal wavefront data 502. Therefore, a laser beam 21 with ideal wavefront data 502 can be formed at the processing point, thereby achieving the effect of suppressing the performance difference of the laser beam 21 irradiating the workpiece 200 between the laser processing apparatuses 1-2.

[0108] [Variation Example]

[0109] The laser processing apparatus of the first and second embodiments of the present invention will be described with reference to the accompanying drawings. Figure 12 This is a perspective view showing a structural example of a laser processing apparatus according to modifications of the first and second embodiments. Additionally, in Figure 12 In this document, the parts that are the same as those in the first embodiment are marked with the same reference numerals and the descriptions are omitted.

[0110] like Figure 12 As shown, in the modified example, the laser processing apparatus 1-1 is provided with a concave mirror 25 at a predetermined position on the second moving plate 16. Except that in the preparation step ST1, the focusing lens 23 of the laser beam irradiation unit 20 is aligned with the reflecting surface 252 of the concave mirror 25 on the second moving plate 16 in the Z-axis direction, the other parts are the same as in the first embodiment.

[0111] The modified laser processing apparatus 1-1 includes a beam splitter 26, a wavefront measurement unit 28, a calculation unit 101, and a phase pattern generation unit 102. Therefore, it can quantitatively measure the wavefront data 500, 501, and 502 of the laser beam 21, and can change the phase pattern displayed on the display unit 241 of the spatial light modulator 24 based on the wavefront data 500, 501, and 502 of the reflected light 212. This allows for the formation of a laser beam 21 with ideal wavefront data 502 at the processing point, thereby suppressing performance differences in the laser beams 21 irradiating the workpiece 200 between laser processing apparatuses. Therefore, similar to the first embodiment, the laser processing apparatus 1-1 achieves the following effect: it can suppress performance differences in the laser beams 21 irradiating the workpiece 200 between laser processing apparatuses 1, thereby obtaining the desired processing result. Furthermore, in this invention, similar to the second embodiment, Figure 12 The control unit 100 of the laser processing apparatus 1-1 shown in the modified example may also have a change unit 104 and a determination unit 105.

[0112] Furthermore, the present invention is not limited to the embodiments described above. That is, it can be implemented in various modifications without departing from the spirit of the present invention. For example, in the laser processing apparatus 1, 1-1 and the phase pattern adjustment method of the present invention, the Zernike coefficient inverse operation step ST6 can be repeated multiple times while changing the Zernike coefficient of the inverse operation value, or the Zernike coefficient inverse operation step ST6 can be repeated multiple times without performing the Zernike coefficient adjustment step ST4. In addition, in the phase pattern adjustment method of the laser processing apparatus 1 of the first embodiment of the present invention, the Zernike coefficient adjustment steps ST4 and ST5 can be performed in the same manner as in the second embodiment.

Claims

1. A laser processing apparatus, comprising: A chuck table holds the workpiece in place; A laser beam irradiation unit that irradiates a laser beam onto the workpiece held on the chuck table; and Control unit The laser beam irradiation unit includes: A laser oscillator that oscillates to produce laser light; A focusing lens that focuses the laser beam emitted from the laser oscillator; A concave mirror is positioned to have a focal point at the focusing point of the condenser lens, and the reflecting surface of the concave mirror that reflects the laser beam is spherical. A beam splitter directs the laser beam emitted from the laser oscillator to the focusing lens and branches the reflected light that has been focused by the focusing lens and reflected by the concave mirror; and The wavefront measurement unit receives the reflected light, which is reflected by the concave mirror and branched by the beam splitter, and obtains wavefront data, which represents the spatial distribution of the phase of the laser beam. Based on the wavefront data measured by the wavefront measurement unit, the control unit modulates the phase pattern displayed on the display unit of the spatial light modulator located between the laser oscillator and the condenser lens. The control unit also includes: The calculation unit performs Zernike polynomial approximation on the wavefront data, which is the spatial distribution of the phase of the laser beam, as measured by the wavefront measurement unit, and then calculates the Zernike coefficients. A phase pattern generating unit generates a phase pattern having a predetermined Zernike coefficient and displays the phase pattern on the display unit of the spatial light modulator; as well as The storage unit stores in advance the correlation between the Zernike coefficients input into the phase pattern and the Zernike coefficients of the laser beam measured by the wavefront measurement unit when the phase pattern with the input Zernike coefficients is displayed on the display unit of the spatial light modulator. The phase pattern generation unit performs an inverse operation on the Zernike coefficients in the phase pattern input to the display unit based on a table of correlations stored in the storage unit, so that the Zernike coefficients of the laser beam measured by the wavefront measurement unit are the desired values.

2. A laser processing apparatus, comprising: A chuck table holds the workpiece in place; A laser beam irradiation unit that irradiates a laser beam onto the workpiece held on the chuck table; and Control unit The laser beam irradiation unit includes: A laser oscillator that oscillates to produce laser light; A focusing lens that focuses the laser beam emitted from the laser oscillator; A concave mirror is positioned to have a focal point at the focusing point of the condenser lens, and the reflecting surface of the concave mirror that reflects the laser beam is spherical. A beam splitter directs the laser beam emitted from the laser oscillator to the focusing lens and branches the reflected light that has been focused by the focusing lens and reflected by the concave mirror; and The wavefront measurement unit receives the reflected light, which is reflected by the concave mirror and branched by the beam splitter, and obtains wavefront data, which represents the spatial distribution of the phase of the laser beam. Based on the wavefront data measured by the wavefront measurement unit, the control unit modulates the phase pattern displayed on the display unit of the spatial light modulator located between the laser oscillator and the condenser lens. The control unit also includes: The calculation unit performs Zernike polynomial approximation on the wavefront data, which is the spatial distribution of the phase of the laser beam, as measured by the wavefront measurement unit, and then calculates the Zernike coefficients. A phase pattern generating unit generates a phase pattern having a predetermined Zernike coefficient and displays the phase pattern on the display unit of the spatial light modulator; The modification section modifies any one of the multiple Zernike coefficients of the wavefront data obtained by the wavefront measurement unit. as well as The determination unit determines whether the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data. The laser oscillator continuously emits a laser beam and alternately repeats the actions of the alteration unit changing any one of the Zernike coefficients and the phase pattern generation unit displaying the phase pattern with the changed Zernike coefficients on the display unit of the spatial light modulator, until the determination unit determines that the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data.

3. The laser processing apparatus according to claim 1 or 2, wherein, The concave mirror is located on the periphery of the chuck table.

4. A method for adjusting a phase pattern, which is a method for adjusting a phase pattern displayed on a display unit of a laser processing apparatus, the laser processing apparatus having a laser beam irradiation unit for irradiating a workpiece held in a chuck table with a laser beam and a control unit. The laser beam irradiation unit includes: A laser oscillator that oscillates to produce laser light; A focusing lens that focuses the laser beam emitted from the laser oscillator; A concave mirror is positioned to have a focal point at the focusing point of the condenser lens, and the reflecting surface of the concave mirror that reflects the laser beam is spherical. A beam splitter directs the laser beam emitted from the laser oscillator to the focusing lens and branches the reflected light that is focused by the focusing lens and reflected by the reflecting surface of the concave mirror. The wavefront measurement unit receives the reflected light reflected by the reflective surface of the concave mirror and branched by the beam splitter, and obtains wavefront data as the spatial distribution of the phase of the laser beam. as well as A spatial light modulator, disposed between the laser oscillator and the focusing lens, has a display unit for adjusting the optical characteristics of the laser beam emitted from the laser oscillator. The control unit also includes: The calculation unit performs Zernike polynomial approximation on the wavefront data, which is the spatial distribution of the phase of the laser beam, as measured by the wavefront measurement unit, and then calculates the Zernike coefficients. A phase pattern generating unit generates a phase pattern having a predetermined Zernike coefficient and displays the phase pattern on the display unit of the spatial light modulator; The modification section modifies any one of the multiple Zernike coefficients of the wavefront data obtained by the wavefront measurement unit. as well as The determination unit determines whether the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data. The laser oscillator continuously emits a laser beam and alternately repeats the actions of the modification unit changing any one of the Zernike coefficients and the phase pattern generation unit displaying the phase pattern with the modified Zernike coefficients on the display unit of the spatial light modulator, until the determination unit determines that the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data, wherein, The method for adjusting the phase pattern has the following steps: The Zernike coefficient input step involves inputting a Zernike coefficient with a specified value and displaying the phase pattern of the input Zernike coefficient with the specified value on the display unit of the spatial light modulator. The laser beam irradiation step involves emitting a laser beam from the laser oscillator and obtaining wavefront data through the wavefront measurement unit; and... The Zernike coefficient adjustment step involves changing any one of the multiple Zernike coefficients from the wavefront data obtained by the wavefront measurement unit, and displaying the phase pattern with the changed Zernike coefficient on the display unit of the spatial light modulator. Repeat the Zernike coefficient adjustment step until the wavefront data measured by the wavefront measurement unit is close to the ideal wavefront data.

5. The phase pattern adjustment method according to claim 4, wherein, The phase pattern adjustment method also includes the following Zernike coefficient inverse operation step: based on a table showing the correlation between the Zernike coefficients input into the phase pattern and the Zernike coefficients of the laser beam measured by the wavefront measurement unit when the phase pattern with the input Zernike coefficients is displayed on the display unit of the spatial light modulator, the Zernike coefficients input into the phase pattern are inversely operated on so that the Zernike coefficients of the laser beam measured by the wavefront measurement unit are the desired values.

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