Laser processing equipment

Abstract

To provide a laser processing device that can accurately determine a processing state from processing sound without being influenced by environmental sound.SOLUTION: A laser processing device 1 comprises a chuck table 10 on which a work-piece 100 is held, a laser beam irradiation unit 20 that irradiates the work-piece 100 held on the chuck table 10 with a laser beam 21 with a wavelength having absorptivity, and a control unit 90 that controls constitutive elements, which further has sound collection means 50 that collects sound that is generated when the work-piece 100 held on the chuck table 10 is ablated by being irradiated with the laser beam 21. The control unit 90 comprises an analysis unit 91 that extracts, as processing sound, sound with frequencies corresponding to repetitive frequencies of the laser beam 21, of sound collected by the sound collection means 50, and a determination unit 92 that determines a processing state of the work-piece 100 on the basis of sound pressure of the processing sound analyzed by the analysis unit 91.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser processing device. [Background technology]

[0002] In order to divide a workpiece such as a semiconductor wafer, a laser processing device is used that performs ablation processing by irradiating a laser beam along a planned dividing line set on the workpiece. It is known that such laser processing devices generate processing noise due to plasma generated during processing and the accompanying air expansion, and various technologies have been proposed that use this processing noise to detect the threshold at which ablation begins, the position of the laser beam, output, etc. (See Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-090261 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since environmental noises caused by the vacuum pump and axis operation are also generated during machining, it is difficult to accurately determine the machining state from the machining sounds.

[0005] The present invention has been made in view of the above problems, and its object is to provide a laser processing apparatus that can accurately determine the processing state from the processing sound without being affected by environmental sounds. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the laser processing apparatus of the present invention comprises: The planned division line was formedA laser processing apparatus comprising: a chuck table for holding a workpiece; a laser beam irradiation unit for irradiating a laser beam having a wavelength absorbable by the workpiece held on the chuck table; and a control unit for controlling each component, the apparatus having a sound collection means for collecting sound generated when the workpiece held on the chuck table is ablated by irradiation of the laser beam, the control unit comprising: an analysis unit for extracting, from the sound collected by the sound collection means, sound having a frequency corresponding to the repetition frequency of the laser beam as processing sound; and a judgment unit for judging the processing state of the workpiece based on the sound pressure of the processing sound analyzed by the analysis unit. The control unit further includes a storage unit that stores in advance a correlation between the irradiation conditions of the laser beam irradiated to the workpiece and the sound pressure of a processing sound generated when the workpiece is processed under the irradiation conditions, the irradiation conditions of the laser beam including a processing count that is the number of times the laser beam is irradiated along the planned division line to perform the ablation processing on the workpiece, and the storage unit stores in advance the sound pressure of the processing sound for each processing count, and the control unit further includes a storage unit that stores in advance a correlation between the irradiation conditions of the laser beam irradiated to the workpiece and the sound pressure of a processing sound generated when the workpiece is processed under the irradiation conditions, and the judgment unit judges that the workpiece has not been properly processed when there is a difference of a predetermined value or more between the sound pressure stored in the storage unit and the sound pressure obtained when the workpiece is actually processed under the irradiation conditions. It is characterized by the following. The analysis unit extracts the sound pressure of the processing sound for each of the processing counts, and the judgment unit may determine, based on the sound pressure of the processing sound for each of the processing counts extracted by the analysis unit, that the processing state of the workpiece is normal if the sound pressure of the processing sound monotonically decreases according to the processing count, or may determine that the processing state of the workpiece is abnormal if the sound pressure of the processing sound does not monotonically decrease according to the processing count.

[0007] Furthermore, in order to solve the above-mentioned problems and achieve the object, the laser processing apparatus of the present invention is a laser processing apparatus comprising: a chuck table for holding a workpiece; a laser beam irradiation unit for irradiating a laser beam of a wavelength that is absorbed by the workpiece held on the chuck table; and a control unit for controlling each of the components, and has a sound collection means for collecting sound generated when the workpiece held on the chuck table is ablated by the irradiation of the laser beam, and the control unit comprises: an analysis unit for extracting, from the sounds collected by the sound collection means, sound of a frequency corresponding to the repetition frequency of the laser beam as processing sound; and a judgment unit for judging the processing state of the workpiece based on the sound pressure of the processing sound analyzed by the analysis unit, and the judgment unit is characterized in that, when actually irradiating the laser beam to process the workpiece to process it, if the sound pressure of the acquired processing sound rises by a predetermined threshold value or more above the sound pressure of the processing sound acquired immediately before.

[0008] The analysis unit extracts, as the processing sound, a sound having a frequency equivalent to the repetition frequency of the laser beam, a sound having a harmonic frequency of the repetition frequency of the laser beam, or a sum of a sound having a frequency equivalent to the repetition frequency of the laser beam and a sound having a harmonic frequency of the repetition frequency of the laser beam. You may do so.

[0009] The determining unit may determine that the workpiece is completely cut when the sound pressure of the cutting sound becomes smaller than a predetermined value.

[0010] The control unit may further include a notification unit that stops machining and notifies of an abnormality when the determination unit determines that the workpiece has not been machined appropriately. [Effects of the Invention]

[0011] The present invention can accurately determine the processing state from the processing sound without being affected by environmental sounds. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a laser processing device according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a main part of the laser processing apparatus of FIG. [Figure 3] FIG. 3 is a graph showing an example of sound that does not include processing sound from the laser processing device of FIG. [Figure 4] FIG. 4 is a graph showing an example of sounds including processing sounds of the laser processing device of FIG. [Figure 5] FIG. 5 is a graph showing another example of sounds including processing sounds of the laser processing device of FIG. [Figure 6] FIG. 6 is a graph showing another example of sounds including processing sounds of the laser processing device of FIG. [Figure 7] FIG. 7 is a graph illustrating the change in sound pressure of the processing sound of the laser processing device of FIG. 1 due to defocusing. [Figure 8] FIG. 8 is a graph showing an example of the measurement results of the sound pressure of the processing sound for each processing number of the laser processing device of FIG. [Figure 9] FIG. 9 is a table showing correlation data stored in the storage unit of the laser processing apparatus of FIG. [Figure 10] FIG. 10 is a flowchart showing the procedure of the operation process of the laser processing apparatus of FIG. [Figure 11] FIG. 11 is a flowchart showing the procedure of the operation process of the laser processing device according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] [Embodiment] A laser processing apparatus 1 according to an 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 1 according to the embodiment. FIG. 2 is a cross-sectional view showing a main part of the laser processing apparatus 1 of FIG. 1. As shown in FIGS. 1 and 2, the laser processing apparatus 1 according to the embodiment includes a chuck table 10, a laser beam irradiation unit 20, an imaging unit 30, an X-axis direction moving unit 41, a Y-axis direction moving unit 42, a Z-axis direction moving unit 43, a sound collecting means 50, a display unit 60, an input unit 70, a dust collection nozzle 80, and a control unit 90.

[0015] In the embodiment, the workpiece 100, which is the object to be processed by the laser processing apparatus 1, is, for example, a disk-shaped semiconductor wafer or optical device wafer made of a base material such as silicon, sapphire, silicon carbide (SiC), gallium arsenide, or glass. As shown in FIG. 1 , the workpiece 100 has a flat surface 101, and chip-sized devices 103 are formed in areas defined by a plurality of planned division lines 102 formed in a grid pattern on the surface 101. In this embodiment, the workpiece 100 has an adhesive tape 105 attached to a back surface 104 behind the surface 101, and an annular frame 106 attached to the outer edge of the adhesive tape 105. However, the present invention is not limited to this. Furthermore, in the present invention, the workpiece 100 may be a rectangular package substrate, a ceramic plate, a glass plate, or the like, having a plurality of devices sealed with resin.

[0016] The chuck table 10 includes a disk-shaped frame body with a recess and a disk-shaped suction portion fitted into the recess. The suction portion of the chuck table 10 is formed of a porous ceramic or the like with numerous porous holes and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). As shown in FIG. 2, the upper surface of the suction portion of the chuck table 10 is a holding surface 11 on which a workpiece 100 is placed and which suction-holds the placed workpiece 100 by negative pressure introduced from the vacuum suction source. In this embodiment, the workpiece 100 is placed with its front surface 101 facing upward, and the holding surface 11 suction-holds the placed workpiece 100 from its back surface 104 via adhesive tape 105. The holding surface 11 and the upper surface of the frame body of the chuck table 10 are located on the same plane and are parallel to the horizontal XY plane.

[0017] The chuck table 10 is provided so as to be movable in the X-axis direction, which is parallel to the horizontal direction, by an X-axis movement unit 41, and so as to be movable in the Y-axis direction, which is parallel to the horizontal direction and perpendicular to the X-axis direction, by a Y-axis movement unit 42. The chuck table 10 is moved along the X-axis and Y-axis by the X-axis movement unit 41 and the Y-axis movement unit 42, respectively, to move the irradiation position of the laser beam 21 on the surface 101 of the workpiece 100 held on the chuck table 10 in the X-axis and Y-axis directions (both of which are opposite to the movement direction of the chuck table 10). The chuck table 10 is provided so as to be rotatable about the Z-axis, which is parallel to the vertical direction and perpendicular to the XY plane, by a rotary drive source (not shown).

[0018] 2, in this embodiment, the laser beam irradiation unit 20 irradiates a pulsed laser beam 21 with a predetermined repetition frequency and a wavelength that is absorbed by the workpiece 100 toward the surface 101 of the workpiece 100 held on the chuck table 10, thereby performing so-called ablation processing in which the workpiece 100 is ablated (sublimated or evaporated) from the surface 101 side by the laser beam 21. The laser beam irradiation unit 20 is configured, for example, to include a laser beam oscillator (not shown) that generates the laser beam 21, and a condenser that focuses the laser beam 21 generated by the laser beam oscillator and irradiates it toward the surface 101 side of the workpiece 100.

[0019] The laser beam irradiation unit 20 is provided so as to be movable in the Z-axis direction by the Z-axis direction movement unit 43. The laser beam irradiation unit 20 is moved along the Z-axis direction by the Z-axis direction movement unit 43, thereby moving in the Z-axis direction relative to the workpiece 100 held on the chuck table 10.

[0020] The imaging unit 30 includes an imaging element that captures images of the planned dividing lines 102 of the workpiece 100 held on the chuck table 10 before ablation processing, and the processed grooves formed in the workpiece 100 after ablation processing. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. In this embodiment, the imaging unit 30 is fixed adjacent to the condenser included in the laser beam irradiation unit 20 so as to move integrally with the condenser.

[0021] The imaging unit 30 images the workpiece 100 held on the chuck table 10 before ablation processing, to obtain images for performing alignment to align the workpiece 100 with the irradiation position of the laser beam 21 from the laser beam irradiation unit 20, and outputs the obtained images to the control unit 90. The imaging unit 30 also images the workpiece 100 held on the chuck table 10 after ablation processing, to obtain images for performing a so-called kerf check to automatically check whether the processed groove is within the planned division line 102 and whether any large chipping has occurred, and outputs the obtained images to the control unit 90.

[0022] The X-axis direction moving unit 41 and the Y-axis direction moving unit 42 move the chuck table 10 along the X-axis direction and the Y-axis direction, respectively, relative to the focal point formed by the laser beam application unit 20. The Z-axis direction moving unit 43 moves the focal point formed by the laser beam application unit 20 along the Z-axis direction relative to the chuck table 10. The X-axis direction moving unit 41, the Y-axis direction moving unit 42, and the Z-axis direction moving unit 43 are each configured to include, for example, a well-known ball screw rotatable about the X-axis, Y-axis, and Z-axis, a well-known pulse motor for rotating the ball screw about the axis, and a well-known guide rail for supporting a collector included in the chuck table 10 or the laser beam application unit 20 so as to be movable in the X-axis, Y-axis, or Z-axis direction.

[0023] The X-axis direction moving unit 41, the Y-axis direction moving unit 42, and the Z-axis direction moving unit 43 each include an encoder that reads the rotational position of the pulse motor, and detects the relative positions of the chuck table 10 and the focal point formed by the laser beam application unit 20 in the X-axis direction, the Y-axis direction, and the Z-axis direction based on the rotational position of the pulse motor read by the encoder, and outputs the detected relative positions to the control unit 90. Note that the X-axis direction moving unit 41, the Y-axis direction moving unit 42, and the Z-axis direction moving unit 43 are not limited to a configuration in which the relative position of the chuck table 10 and the focal point formed by the laser beam application unit 20 is detected by an encoder, and may each be configured by a linear scale parallel to the X-axis direction, the Y-axis direction, and the Z-axis direction, and a read head that is movable in the X-axis direction, the Y-axis direction, and the Z-axis direction by the X-axis direction moving unit 41, the Y-axis direction moving unit 42, and the Z-axis direction moving unit 43, respectively, and that reads the graduations of the linear scale.

[0024] The laser processing apparatus 1 holds the workpiece 100 on the chuck table 10 with the surface 101 facing upward, performs alignment, aligns the irradiation line of the laser beam 21 with the planned dividing line 102 of the workpiece 100 using the Y-axis movement unit 42, and adjusts the focal point of the laser beam 21 to a predetermined height (for example, on the surface 101 of the workpiece 100) using the Z-axis movement unit 43. Then, while irradiating the laser beam 21 toward the surface 101 of the workpiece 100, the X-axis movement unit 41 moves the focal point formed by the laser beam irradiation unit 20 along the planned dividing line 102 relative to the workpiece 100 on the chuck table 10, thereby ablating the workpiece 100 along the planned dividing line 102 to form a groove. The laser processing apparatus 1 further irradiates the laser beam 21 along the planned dividing line 102 along which the groove has been formed, similarly to ablate the workpiece 100, thereby deepening the groove formed along the planned dividing line 102. In this way, the laser processing device 1 performs ablation processing by irradiating the laser beam 21 multiple times along the planned dividing line 102, thereby causing the bottom surface of the processed groove to reach the back surface 104 and dividing the workpiece 100 along the planned dividing line 102.

[0025] As shown in FIG. 2 , the sound collecting means 50 is disposed facing the position on the surface 101 of the workpiece 100 held on the chuck table 10 where the laser beam 21 is irradiated by the laser beam irradiating unit 20, and where the collected sound is not blocked by the dust collection nozzle 80 (described later). In this embodiment, the sound collecting means 50 is fixed adjacent to the condenser of the laser beam irradiating unit 20 so as to move integrally with the condenser included in the laser beam irradiating unit 20, similar to the imaging unit 30. The sound collecting means 50 collects sounds 54, including processing sounds 55 (see FIGS. 4 , 5 , and 6 ), generated when the workpiece 100 held on the chuck table 10 is ablated by the irradiation of the laser beam 21 by the laser beam irradiating unit 20, and outputs the collected sounds 54 including the processing sounds 55 to the control unit 90. In this embodiment, the sound collecting means 50 is, for example, a unidirectional microphone capable of measuring frequencies from 50 Hz to 16 kHz.

[0026] The processing sound 55 is a sound generated by air expanding due to plasma generated when ablation processing is performed on the workpiece 100. Fig. 3 is a graph showing an example of a sound 54 that does not include the processing sound 55 of the laser processing apparatus 1 of Fig. 1. Fig. 4 is a graph showing an example of a sound 54 that includes the processing sound 55 of the laser processing apparatus 1 of Fig. 1. The sound 54 that includes the processing sound 55 collected by the sound collecting means 50 will be described with reference to Figs. 3 and 4.

[0027] The graph in Fig. 3 shows the spectrum of sound 54, i.e., environmental sound, not including processing sound 55 of the laser processing apparatus 1, generated when axial operations are performed to move the workpiece 100 held on the chuck table 10 along the X-axis and Y-axis directions, respectively, relative to the laser beam application unit 20, using the X-axis movement unit 41 and the Y-axis movement unit 42, without irradiating the laser beam 21 by the laser beam application unit 20. The graph in Fig. 4 shows the spectrum of sound 54, including processing sound 55 of the laser processing apparatus 1, generated when the workpiece 100 held on the chuck table 10 is ablated by irradiating the workpiece 100 with a pulsed laser beam 21 having a repetition frequency of 10 kHz, while the workpiece 100 is moved relative to the laser beam application unit 20 by performing axial operations. Note that the unit of spectral intensity on the vertical axis in Figs. 3 and 4 is arbitrary unit (au), and this also applies to the spectral intensity graphs in the following figures. Comparing the graphs of Figures 3 and 4, it can be seen that the processing sound 55 resulting from ablation processing of the workpiece 100 by irradiating it with a pulsed laser beam 21 having a repetition frequency of 10 kHz significantly includes, for example, sound 54 shown in Figure 4 having a frequency of 10 kHz, which is equivalent to the repetition frequency of the laser beam 21, 10 kHz.

[0028] 5 and 6 are graphs showing another example of sound 54 including processing sound 55 of the laser processing apparatus 1 of FIG. 1. The graphs of FIGS. 5 and 6 show the spectrum of sound 54 including processing sound 55 of the laser processing apparatus 1 generated when ablation processing is performed on a workpiece 100 by irradiating the workpiece 100 with a pulsed laser beam 21 having a repetition frequency of 5 kHz and 15 kHz, respectively, while performing axial operation. Comparing the graph of FIG. 3 with the graphs of FIGS. 5 and 6, it can be seen that the processing sound 55 resulting from ablation processing of the workpiece 100 by irradiating the workpiece 100 with a pulsed laser beam 21 having a repetition frequency of 5 kHz and 15 kHz significantly includes, for example, sounds having frequencies of 5 kHz and 15 kHz, which are equivalent to the repetition frequencies of the laser beam 21, of the sound 54 shown in FIGS. 5 and 6.

[0029] 3 and 5, it can be seen that the processing sound 55 resulting from ablation of the workpiece 100 by irradiating it with a pulsed laser beam 21 having a repetition frequency of 5 kHz not only includes sound of 5 kHz, which is the same as the repetition frequency of the laser beam 21, but also significantly includes sounds of frequencies of 10 kHz, 15 kHz, 20 kHz, and so on, which are harmonics of the 5 kHz repetition frequency of the laser beam 21. Here, the harmonics of the repetition frequency of the laser beam 21 refer to frequencies that are integer multiples of the repetition frequency of the laser beam 21 that are two or more.

[0030] In this way, the processing sound 55 prominently includes, for example, a sound of a frequency corresponding to the repetition frequency of the laser beam 21 among the sounds 54, and this sound can be extracted and used suitably. Here, the frequency corresponding to the repetition frequency of the laser beam 21 refers to a frequency that is equal to the repetition frequency of the laser beam 21 or a frequency that is an overtone of the repetition frequency of the laser beam 21. Therefore, if the repetition frequency of the laser beam 21 is high, the processing sound 55 will be high, and if the repetition frequency of the laser beam 21 is low, the processing sound 55 will be low.

[0031] The display unit 60 is provided on a cover (not shown) of the laser processing apparatus 1 with its display surface facing outward, and displays a screen for setting the irradiation conditions of the laser beam 21 of the laser processing apparatus 1, a screen showing the results of alignment and kerf checks, a screen showing the analysis results of the analysis unit 91 (described later), a screen showing the judgment results of the judgment unit 92, etc., so that the operator can see them. The display unit 60 is configured with a liquid crystal display device or the like. The display unit 60 is provided with an input unit 70 that the operator uses to input command information regarding various operations of the laser processing apparatus 1, the irradiation conditions of the laser beam 21 of the laser processing apparatus 1, image display, etc. The input unit 70 provided on the display unit 60 is configured with at least one of a touch panel provided on the display unit 60, a keyboard, etc.

[0032] The dust collection nozzle 80 has one end disposed horizontally at the lower end of the condenser of the laser beam irradiation unit 20 so as to cover the irradiation position of the laser beam 21, and the other end connected to a suction source (not shown). The dust collection nozzle 80 has an opening formed at one end through which the laser beam 21 passes and through which fine dust processing chips called debris generated by ablation processing of the workpiece 100 at the irradiation position of the laser beam 21 pass. The dust collection nozzle 80 uses negative pressure introduced from the suction source to suck and remove debris generated at the irradiation position of the laser beam 21 from the opening formed at one end.

[0033] The control unit 90 controls the operation of each component of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform ablation processing on the workpiece 100 by irradiating it with the laser beam 21. As shown in FIG. 1 , the control unit 90 includes an analysis unit 91, a determination unit 92, an alarm unit 93, and a memory unit 95. The analysis unit 91 extracts, from the sound 54 collected by the sound collection means 50, a sound having a frequency corresponding to the repetition frequency of the laser beam 21 as the processing sound 55. For example, the analysis unit 91 performs a fast Fourier transform (FFT) on the sound 54 collected by the sound collection means 50 to resolve the frequency components of the sound 54, and extracts, as the spectrum of the processing sound 55, a sound spectrum of a certain range of frequencies centered around the frequency corresponding to the repetition frequency of the laser beam 21. The analysis unit 91 may extract a sound having a frequency equivalent to the repetition frequency of the laser beam 21 as the processing sound 55, or may extract a sound having a frequency that is an overtone of the repetition frequency of the laser beam 21 as the processing sound 55, or may extract the sum of the sounds of these frequencies as the processing sound 55.

[0034] Furthermore, the analysis unit 91 calculates the sound pressure of the extracted processing sound 55. In this embodiment, for example, the analysis unit 91 calculates the integrated intensity of the spectrum of the extracted processing sound 55 by integrating the spectrum of the processing sound 55, and sets this calculated integrated intensity as the sound pressure of the processing sound 55.

[0035] The properties of the sound pressure of the processing sound 55 calculated by the analysis unit 91 will be described. FIG. 7 is a graph illustrating the change in sound pressure of the processing sound 55 of the laser processing apparatus 1 of FIG. 1 due to defocus. The graph in FIG. 7 shows the sound pressure of the processing sound 55 when the defocus of the laser beam 21 is changed in 20-μm increments from −100 μm to 100 μm without changing other irradiation conditions of the laser beam 21. Here, the defocus of the laser beam 21 refers to the amount of movement of the focal point of the laser beam 21 in the thickness direction of the workpiece 100, toward or away from the workpiece 100, from a just focus (JF) state in which the focal point of the laser beam 21 is positioned on the surface 101 of the workpiece 100. Note that the units of sound pressure on the vertical axis of FIG. 7 are arbitrary units, similar to the units of the spectral intensity described above, and the same applies to the sound pressure graphs in the following figures. 7, it can be seen that the sound pressure of the processing sound 55 varies depending on the position (height) of the focal point, and is greatest when the laser beam 21 is just in focus. Furthermore, by utilizing this property, the laser processing device 1 can detect the position at which the sound pressure of the processing sound 55 is greatest when processing the workpiece 100 by changing only the position of the focal point without changing other irradiation conditions of the laser beam 21.

[0036] Fig. 8 is a graph showing an example of the measurement results of the sound pressure of the processing sound 55 for each processing count of the laser processing apparatus 1 of Fig. 1. The graph in Fig. 8 shows the sound pressure of the processing sound 55 when ablation processing is performed by irradiating the laser beam 21 multiple times along the same planned division line 102 without changing other irradiation conditions of the laser beam 21. The processing count is the number of times the laser beam 21 is irradiated along the planned division line 102 to ablate the workpiece 100.

[0037] In the graph of FIG. 8 , data points 201, represented by hollow circles, indicate the sound pressure of the machining sound 55 when the ablation process of the workpiece 100 was performed normally by the laser beam 21 for all processing runs. Here, "successful ablation" refers to a situation in which no abnormalities are detected when a kerf check is performed under specified conditions on the processed groove after the ablation process. Referring to data points 201 in the graph of FIG. 8 , it can be seen that the sound pressure of the machining sound 55 monotonically decreases with the number of processing runs. This phenomenon occurs because, when the number of processing runs is small, the plasma that generates the machining sound 55 is generated close to the surface 101 of the workpiece 100, making the sound more likely to spread and resulting in a higher sound pressure. However, as the number of processing runs increases, the groove irradiated by the laser beam 21 becomes deeper, and the plasma that generates the machining sound 55 is generated inside the processed groove, making it more difficult for the sound to spread, resulting in a lower sound pressure.

[0038] In the graph of Figure 8, data point 202, represented by a solid circle, indicates the sound pressure of processing sound 55 when abnormal ablation processing of workpiece 100 occurs due to deviation of the irradiation position of laser beam 21 from the processed groove during the fifth processing run. Referring to data point 202 in the graph of Figure 8, it can be seen that the sound pressure of processing sound 55 during the fifth processing run increases significantly compared to the fourth processing run. This phenomenon occurs because the portion where the irradiation position of laser beam 21 is deviated from the processed groove is processed by laser beam 21 near the surface 101 of workpiece 100 rather than the bottom surface of the processed groove, and plasma, which generates processing sound 55, is generated near the surface 101 of workpiece 100, making it easier for the sound to spread and increasing the sound pressure.

[0039] The determination unit 92 determines the machining state of the workpiece 100 based on the sound pressure of the machining sound 55 analyzed by the analysis unit 91. For example, when the analysis unit 91 obtains the sound pressure of the machining sound 55 shown at data point 201 on the graph in Fig. 8, the determination unit 92 determines that the machining state of the workpiece 100 is normal. When the analysis unit 91 obtains the sound pressure of the machining sound 55 shown at data point 202 on the graph in Fig. 8 for the fifth machining iteration, the determination unit 92 determines that the machining state of the workpiece 100 is not properly machined. When the determination unit 92 obtains a sound pressure of the machining sound 55 lower than a predetermined value, the determination unit 92 determines that the machining state of the workpiece 100 is a state in which the bottom surface of the machined groove has reached the back surface 104, i.e., a state in which the workpiece 100 has been completely cut.

[0040] When the determination unit 92 determines that the workpiece 100 has not been properly machined, the notification unit 93 stops the irradiation of the laser beam 21 by the laser beam application unit 20, stops the ablation processing, and notifies the user that the processing has not been properly performed, i.e., that an abnormality has occurred. The notification unit 93 notifies the user of the abnormality, for example, by displaying a screen on the display unit 60 showing the result of the determination that the workpiece 100 has not been properly machined. The notification unit 93 may also notify the user of the abnormality that the workpiece 100 has not been properly machined by turning on, blinking, or extinguishing a light-emitting unit configured by a light-emitting diode (not shown) connected to the control unit 90, or may notify the user of the abnormality that the workpiece 100 has not been properly machined by audio using a speaker (not shown) connected to the control unit 90.

[0041] FIG. 9 is a table showing correlation data 200 stored in the memory unit 95 of the laser processing apparatus 1 of FIG. 1 . The memory unit 95 stores correlation data 200, such as that shown in FIG. 9 , in advance before the laser processing apparatus 1 irradiates the workpiece 100 with the laser beam 21 to perform ablation processing. As shown in FIG. 9 , the correlation data 200 is correlation data linking the irradiation conditions of the laser beam 21 irradiated onto the workpiece 100 with the sound pressure of the processing sound 55 generated when ablation processing is normally performed on the workpiece 100 with the laser beam 21 under the irradiation conditions. Here, in this embodiment, the irradiation conditions of the laser beam 21 are, for example, the irradiation power (W), repetition frequency (kHz), movement speed (mm / s), defocus (μm), and number of processing times (times), as shown in FIG. 9 . The irradiation power is the light intensity of the laser beam 21. The moving speed is the relative moving speed of the focal point formed by the laser beam irradiation unit 20 with respect to the workpiece 100 held on the chuck table 10 during irradiation with the laser beam 21. The memory unit 95 preferably stores correlation data 200 for each of various irradiation conditions.

[0042] In the first embodiment, the control unit 90 includes a computer system. The computer system included in the control unit 90 includes an arithmetic processing device having a microprocessor such as a CPU (Central Processing Unit), a storage device having memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input / output interface device. The arithmetic processing device of the control unit 90 performs arithmetic processing in accordance with a computer program stored in the storage device of the control unit 90, 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 of the control unit 90.

[0043] In this embodiment, the functions of the analysis unit 91, the determination unit 92, and the notification unit 93 are realized by the arithmetic processing unit of the control unit 90 executing a computer program stored in a storage device. In this embodiment, the function of the storage unit 95 is realized by the storage device of the control unit 90.

[0044] Next, this specification will explain the operation process of the laser processing apparatus 1 according to the embodiment with reference to the drawings. FIG. 10 is a flowchart showing the procedure of the operation process of the laser processing apparatus 1 of FIG. 1. The flowchart shown in FIG. 10 shows the procedure of the operation process for processing one planned division line 102. After holding the workpiece 100 on the chuck table 10, the control unit 90 of the laser processing apparatus 1 causes the laser beam application unit 20 to irradiate the workpiece 100 with the laser beam 21 along the planned division line 102, thereby ablating the workpiece 100, while collecting sounds 54 including processing sounds 55 with the sound collection means 50, extracting the processing sounds 55 from the sounds 54 collected by the sound collection means 50 with the analysis unit 91, and calculating the sound pressure of the processing sounds 55 (step 1001 in FIG. 10).

[0045] After performing step 1001, the control unit 90 compares the sound pressure of the processing sound 55 actually acquired in the immediately preceding step 1001 with the sound pressure of the processing sound 55 linked to the irradiation conditions of the laser beam 21 in the immediately preceding step 1001 in the correlation data 200 pre-stored in the memory unit 95 (step 1002 in FIG. 10).

[0046] If the difference between the sound pressures of the two compared machining sounds 55 is equal to or greater than a predetermined value previously stored in the memory unit 95 (Yes in step 1002 in FIG. 10 ), the control unit 90 determines via the judgment unit 92 that the machining state of the workpiece 100 in the immediately preceding step 1001 was a state in which the workpiece 100 was not properly machined (step 1003 in FIG. 10 ), and causes the alarm unit 93 to stop the irradiation of the laser beam 21 by the laser beam irradiation unit 20, stop the ablation machining, and alarm the abnormality (step 1004 in FIG. 10 ). Here, the predetermined value previously stored in the memory unit 95 is appropriately set to, for example, a value that is sufficiently larger than the error in the sound pressure of the machining sound 55 determined by the analysis unit 91 and sufficiently smaller than the amount of change in the sound pressure of the machining sound 55 caused by a major abnormality in the ablation machining.

[0047] For example, if the sound pressure of the processing sound 55 at data point 201, which is the fifth processing iteration on the graph in FIG. 8, is stored in advance in the memory unit 95, and the sound pressure of the processing sound 55 at data point 202, which is the fifth processing iteration on the graph in FIG. 8, is acquired in the immediately preceding step 1001, there is a difference of a predetermined value or more between the sound pressures of these two processing sounds 55, and therefore the judgment unit 92 judges that the processing state of the workpiece 100 in the immediately preceding step 1001 is a state in which the workpiece 100 has not been properly processed.

[0048] If there is no difference between the sound pressures of these two compared processing sounds 55 that is equal to or greater than a predetermined value previously stored in the storage unit 95 (No in step 1002 in FIG. 10), the control unit 90 uses the judgment unit 92 to judge that the processing state of the workpiece 100 in the immediately preceding step 1001 was a state in which processing was performed normally, and further judges whether the sound pressure of the processing sound 55 actually acquired in the immediately preceding step 1001 is smaller than a predetermined value previously stored in the storage unit 95 (step 1005 in FIG. 10). Here, the predetermined value previously stored in the storage unit 95 is appropriately set to, for example, a sufficiently small value that it can be considered that the processing sound 55 has substantially disappeared in this embodiment.

[0049] If the sound pressure of the processing sound 55 actually acquired in the immediately preceding step 1001 is smaller than a predetermined value pre-stored in the memory unit 95 (Yes in step 1005 in FIG. 10), the control unit 90 determines, via the judgment unit 92, that the workpiece 100 has been completely cut (step 1006 in FIG. 10), and terminates processing of this planned division line 102 (step 1007 in FIG. 10).

[0050] If the sound pressure of the processing sound 55 actually acquired in the immediately preceding step 1001 is equal to or greater than a predetermined value previously stored in the memory unit 95 (No in step 1005 in FIG. 10), the control unit 90 determines, via the judgment unit 92, that the workpiece 100 has not been completely cut, and returns the operation processing to step 1001 again.

[0051] In this way, the control unit 90 repeats the processing of step 1001 and repeats the ablation processing along the same planned division line 102 until the judgment unit 92 determines in step 1002 that the processing state of the workpiece 100 is a state in which the workpiece 100 has not been properly processed, or determines in step 1005 that the workpiece 100 has been completely cut.

[0052] Furthermore, the predetermined value stored in advance in the storage unit 95 and used in step 1005 may be set to the sound pressure of the processing sound 55 linked to the irradiation conditions of the laser beam 21 in the final processing cycle in which the workpiece 100 is completely cut, in the correlation data 200 stored in advance in the storage unit 95, instead of a small value at which the processing sound 55 can be considered to be substantially absent. In this way, it is possible to reduce the possibility that step 1001 will be performed one extra time in order to detect the disappearance of the processing sound 55.

[0053] In the laser processing apparatus 1 according to the embodiment having the above-described configuration, the analysis unit 91 extracts, from the sound 54 collected by the sound collection means 50 when the workpiece 100 is subjected to ablation processing, the sound having a frequency corresponding to the repetition frequency of the laser beam 21 as the processing sound 55, and the judgment unit 92 judges the processing state of the workpiece 100 based on the sound pressure of the processing sound 55 extracted by the analysis unit 91. This provides the advantageous effect of being able to accurately judge the processing state from the processing sound 55 without being influenced by environmental sounds other than the processing sound 55 among the sounds 54.

[0054] Furthermore, in the laser processing apparatus 1 according to the embodiment, if there is a difference of a predetermined value or more between the sound pressure of the processing sound 55 generated when ablation processing is performed on the workpiece 100 under predetermined irradiation conditions of the laser beam 21 stored in advance in the memory unit 95 and the sound pressure of the processing sound 55 acquired when ablation processing is actually performed under those irradiation conditions, the determination unit 92 determines that the workpiece 100 has not been properly processed. This allows the processing state to be accurately determined based on the sound pressure of the processing sound 55 without being affected by environmental sounds. Furthermore, in the laser processing apparatus 1 according to the embodiment, if the determination unit 92 determines that the workpiece 100 has not been properly processed, the alarm unit 93 stops the ablation processing and notifies the operator of the laser processing apparatus 1 of an abnormality. This appropriately prompts the operator of the laser processing apparatus 1 to make corrections promptly so that the workpiece 100 can be properly processed. This reduces the number of corrections throughout the entire processing of the workpiece 100, thereby improving processing efficiency.

[0055] Furthermore, in the laser processing apparatus 1 according to the embodiment, the determination unit 92 determines that the workpiece 100 has been completely cut when the sound pressure of the processing sound 55 becomes smaller than a predetermined value, so that the processing state can be accurately determined based on the sound pressure of the processing sound 55 without being affected by environmental sounds. As a result, the laser processing apparatus 1 according to the embodiment can end the ablation processing at the correct timing based on the sound pressure of the processing sound 55 without being affected by environmental sounds.

[0056] [Modification] A laser processing apparatus 1 according to a modified example of the embodiment will be described with reference to the drawings. Fig. 11 is a flowchart showing the procedure of the operation process of the laser processing apparatus 1 according to the modified example. In Fig. 11, the same parts as those in the embodiment are assigned the same reference numerals and their description will be omitted.

[0057] The laser processing apparatus 1 according to the modification has a modified operation process from the embodiment, but other configurations are the same as those of the embodiment. As shown in FIG. 11, the operation process of the laser processing apparatus 1 according to the modification is the same as that of the embodiment, except that step 1002 is replaced with step 1009.

[0058] 11, after performing step 1001, the control unit 90 of the laser processing apparatus 1 according to the modified example compares the sound pressure of the processing sound 55 actually acquired in the immediately previous step 1001 with the sound pressure of the processing sound 55 actually acquired in the step 1001 immediately before the immediately previous step 1001, and determines whether the sound pressure of the processing sound 55 immediately before has increased by a predetermined threshold or more compared to the sound pressure of the processing sound 55 immediately before that. Here, the predetermined threshold stored in advance in the storage unit 95 is appropriately set to a value that is approximately the error in the sound pressure of the processing sound 55 by the analysis unit 91 in this embodiment, for example.

[0059] If the sound pressure of the immediately preceding processed sound 55 has increased by a predetermined threshold value or more pre-stored in the memory unit 95 compared to the sound pressure of the processed sound 55 just before that (Yes in step 1009 in FIG. 11), the control unit 90 proceeds with the operation processing to step 1003. On the other hand, if the sound pressure of the immediately preceding processed sound 55 has not increased by a predetermined threshold value or more compared to the sound pressure of the processed sound 55 just before that (No in step 1009 in FIG. 11), the control unit 90 proceeds with the operation processing to step 1005.

[0060] In the laser processing apparatus 1 according to the modified example having the above-described configuration, when the judgment unit 92 actually irradiates the laser beam 21 to process the workpiece 100, if the sound pressure of the acquired processing sound 55 rises by a predetermined threshold or more compared to the sound pressure of the processing sound 55 acquired immediately before the processing sound 55 in question, the judgment unit 92 judges that the workpiece 100 has not been properly processed. Therefore, as in the embodiment, the processing state can be accurately judged based on the sound pressure of the processing sound 55 without being affected by environmental sounds.

[0061] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention. [Explanation of symbols]

[0062] 1. Laser processing equipment 10 Chuck table 20 Laser beam irradiation unit 21 Laser Beam 50 Sound collection means 54 sounds 55 Processing sound 90 Control Unit 91 Analysis Unit 92 Judgment Unit 93 Announcement Unit 95 Memory section 100 Workpiece 200 Correlation Data

Claims

1. A chuck table for holding a workpiece on which a planned dividing line is formed; a laser beam irradiation unit that irradiates a laser beam having a wavelength that is absorbed by the workpiece held on the chuck table; A laser processing apparatus comprising: a control unit for controlling each component; a sound collection means for collecting a sound generated when the workpiece held on the chuck table is ablated by irradiation with the laser beam; The control unit an analysis unit that extracts, from the sounds collected by the sound collecting means, sounds having a frequency corresponding to the repetition frequency of the laser beam as processing sounds; a determination unit for determining the machining state of the workpiece based on the sound pressure of the machining sound analyzed by the analysis unit; Equipped with The control unit further includes a storage unit that stores in advance a correlation between the irradiation conditions of the laser beam irradiated onto the workpiece and the sound pressure of the processing sound generated when the workpiece is processed under the irradiation conditions, the laser beam irradiation conditions include a processing count, which is the number of times the laser beam is irradiated along the planned division line to perform the ablation processing on the workpiece; The storage unit stores in advance the sound pressure of the processing sound for each of the processing times, The laser processing device is characterized in that the judgment unit judges that the workpiece has not been properly processed if there is a difference of a predetermined value or more between the sound pressure stored in the memory unit and the sound pressure obtained when processing is actually performed under the irradiation conditions.

2. The analysis unit extracts the sound pressure of the processing sound for each of the processing times, 2. The laser processing device according to claim 1, wherein the judgment unit judges that the processing state of the workpiece is normal when the sound pressure of the processing sound monotonically decreases according to the number of processing times, based on the sound pressure of the processing sound for each of the number of processing times extracted by the analysis unit, and judges that the processing state of the workpiece is abnormal when the sound pressure of the processing sound does not monotonically decrease according to the number of processing times.

3. a chuck table for holding the workpiece; a laser beam irradiation unit that irradiates a laser beam having a wavelength that is absorbed by the workpiece held on the chuck table; A laser processing apparatus comprising: a control unit for controlling each component; a sound collection means for collecting a sound generated when the workpiece held on the chuck table is ablated by irradiation with the laser beam; The control unit an analysis unit that extracts, from the sounds collected by the sound collecting means, sounds having a frequency corresponding to the repetition frequency of the laser beam as processing sounds; a determination unit for determining the machining state of the workpiece based on the sound pressure of the machining sound analyzed by the analysis unit; Equipped with The laser processing device is characterized in that, when actually irradiating the workpiece with a laser beam to process it, if the sound pressure of the processing sound acquired increases by a predetermined threshold value or more compared to the sound pressure of the processing sound acquired immediately before, the judgment unit judges that the workpiece has not been properly processed.

4. A laser processing device as described in claim 1, claim 2 or claim 3, characterized in that the analysis unit extracts as the processing sound a sound of a frequency equivalent to the repetition frequency of the laser beam, a sound of a frequency that is an overtone of the repetition frequency of the laser beam, or the sum of a sound of a frequency equivalent to the repetition frequency of the laser beam and a sound of a frequency that is an overtone of the repetition frequency of the laser beam.

5. 5. The laser processing device according to claim 1, wherein the determination unit determines that the workpiece has been completely cut when the sound pressure of the processing sound becomes smaller than a predetermined value.

6. 5. The laser processing apparatus according to claim 1, wherein the control unit further comprises an alarm unit that stops processing and notifies of an abnormality when the judgment unit determines that the workpiece has not been properly processed.

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