Laser processing equipment

Abstract

To monitor the output of a laser beam without arranging a mirror on an optical path of the laser beam and without interrupting laser processing.SOLUTION: A laser processing device is provided which comprises a suction holding plate, a laser beam irradiation unit for irradiating a workpiece under suction holding by the suction holding plate with a laser beam, an alarm unit for emitting alarms when the output of the laser beam exceeds a predetermined range, and a control unit for controlling the operation of the alarm unit, where the laser beam irradiation unit has a laser oscillator, a condenser lens, and a power measurement unit for measuring the power of a laser beam reflected and diffused by at least the condenser lens, and the control unit estimates, on the basis of the power measured by the power measurement unit, the output of the laser beam emitted from the laser oscillator to make the alarm unit emit alarms when the output of the laser beam estimated exceeds a predetermined range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a laser processing apparatus. [Background technology]

[0002] As a method of processing workpieces such as semiconductor wafers with a laser beam, laser processing is known in which a laser beam having a wavelength absorbed by the workpiece is irradiated onto the surface side of the workpiece to form processing grooves on the surface side of the workpiece by ablation processing (see, for example, Patent Document 1).

[0003] Another method of processing a workpiece with a laser beam is known, which involves irradiating the workpiece with a laser beam having a wavelength that penetrates the workpiece so that the laser beam is focused into the workpiece's interior, thereby forming a vulnerable region (also called a modified region) that serves as the starting point for splitting (see, for example, Patent Document 2).

[0004] To perform this type of laser processing, a laser processing device is used. Before laser processing is performed on the workpiece, the output of the laser beam is pre-set in the laser processing device. However, if the actual output deviates from the initial setting, processing defects may occur.

[0005] Therefore, a laser processing apparatus has been proposed that can monitor the output of the laser beam without interrupting the laser processing, even when laser processing is being performed on a workpiece (see, for example, Patent Document 3).

[0006] In this laser processing apparatus, one or more mirrors (e.g., two or three) are placed between the laser oscillator and the focusing lens. The laser beam is mostly reflected by each mirror, but a small amount is transmitted through each mirror without being reflected. For example, a few percent of the laser beam's output is transmitted through the mirrors.

[0007] This laser processing device allows for the measurement of the laser beam output based on a portion of the laser beam that passes through the mirror, enabling the measurement of the laser beam output without interrupting the laser processing of the workpiece. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2003-320466 [Patent Document 2] Japanese Patent Publication No. 2002-192370 [Patent Document 3] Japanese Patent Publication No. 2021-30283 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, if one or more mirrors are placed between the laser oscillator and the focusing lens, the optical system becomes larger compared to when no mirrors are used.

[0010] This invention has been made in view of the aforementioned problems, and aims to provide a laser processing apparatus that can monitor the output of a laser beam without placing a mirror in the optical path of the laser beam and without interrupting the laser processing. [Means for solving the problem]

[0011] According to one aspect of the present invention, a laser processing apparatus comprising: a suction holding plate for holding a workpiece by suction; a laser beam irradiation unit for irradiating a laser beam onto the workpiece held by the suction holding plate; an alarm unit for issuing an alarm when the output of the laser beam exceeds a predetermined range; and a control unit comprising a memory and a processor for controlling the operation of the alarm unit, wherein the laser beam irradiation unit comprises a laser oscillator; a focusing lens for focusing the laser beam emitted from the laser oscillator; and a power measuring unit for measuring the power of the laser beam reflected and scattered by at least the focusing lens. The laser beam irradiation unit and the suction holding plate are arranged relative to each other such that the path of the laser beam extending from the focusing lens to the holding surface of the suction holding plate is not perpendicular to the holding surface of the suction holding plate but is tilted by a predetermined angle. The provided laser processing apparatus includes a control unit that estimates the output of the laser beam emitted from the laser oscillator based on the power measured by the power measurement unit, and causes the alarm unit to issue an alarm if the estimated output of the laser beam exceeds a predetermined range.

[0012] Preferably, the power measuring unit has at least a light-receiving unit that receives the laser beam reflected and scattered by the focusing lens, wherein the light-receiving unit is not located on the extension of the path of the laser beam from the laser oscillator to the focusing lens, and is located away from the optical axis of the focusing lens.

[0013] Preferably, the laser processing apparatus further includes a laser beam output adjustment unit that adjusts the output of the laser beam so that the output of the laser beam, estimated based on the power measured by the power measuring unit, falls within a predetermined range.

[0014] Preferably, the focusing lens is positioned such that its optical axis is not perpendicular to the holding surface of the suction holding plate but is tilted by a predetermined angle. [Effects of the Invention]

[0015] A laser processing apparatus according to an aspect of the present invention includes a laser beam irradiation unit. The laser beam irradiation unit includes a laser oscillator, a condenser lens, and a power measurement unit that measures the power of the laser beam reflected and scattered by at least the condenser lens.

[0016] The control unit of the laser processing apparatus estimates the output of the laser beam emitted from the laser oscillator based on the power measured by the power measurement unit. Therefore, the output of the laser beam can be monitored without arranging a mirror on the optical path of the laser beam and without interrupting the laser processing.

Brief Description of the Drawings

[0017] [Figure 1] It is a perspective view of the laser processing apparatus. [Figure 2] FIG. 2(A) is a perspective view of the laser beam irradiation unit, and FIG. 2(B) is a partial cross-sectional side view of the laser beam irradiation unit. [Figure 3] It is a graph showing the power at the condensing point of the laser beam and the voltage value corresponding to the power of the reflected and scattered light. [Figure 4] It is a partial cross-sectional side view showing the inclination of the optical axis of the condenser lens. [Figure 5] It is a partial cross-sectional side view of the laser beam irradiation unit according to the second embodiment. [Figure 6] It is a partial cross-sectional side view of the laser beam irradiation unit according to the third embodiment. [Figure 7] FIG. 7(A) is a diagram showing a first modification of the laser beam output adjustment unit, FIG. 7(B) is a diagram showing a second modification of the laser beam output adjustment unit, and FIG. 7(C) is a diagram showing a third modification of the laser beam output adjustment unit.

Modes for Carrying Out the Invention

[0018] An embodiment of one aspect of the present invention will be described with reference to the attached drawings. Figure 1 is a perspective view of a laser processing apparatus 2 according to the first embodiment. The X-axis direction (processing feed direction), Y-axis direction (indexing feed direction), and Z-axis direction (vertical direction, height direction) shown in Figure 1 are orthogonal to each other.

[0019] The laser processing apparatus 2 includes a base 4 that supports each structure. The base 4 includes a flat plate portion 6 and a wall portion 8 that extends upward on the rear side (one side in the Y-axis direction) of the flat plate portion 6.

[0020] A Y-axis movement unit 10 is provided on the upper surface of the flat plate portion 6. The Y-axis movement unit 10 has a pair of Y-axis guide rails 12 arranged substantially parallel to each other in the Y-axis direction. The pair of Y-axis guide rails 12 are fixed to the upper surface of the flat plate portion 6.

[0021] A movable table 14 is slidably mounted on the Y-axis guide rail 12. A nut portion (not shown) is provided on the underside of the movable table 14. A screw shaft 16, positioned approximately parallel to the Y-axis direction, is rotatably connected to the nut portion via a plurality of balls (not shown).

[0022] A drive source 18, such as a stepping motor, is connected to one end of the screw shaft 16. When the drive source 18 rotates the screw shaft 16, the mobile table 14 moves along the Y-axis guide rail 12.

[0023] An X-axis movement unit 20 is provided on the upper surface of the mobile table 14. The X-axis movement unit 20 has a pair of X-axis guide rails 22 that are arranged substantially parallel to the X-axis direction. The pair of X-axis guide rails 22 are fixed to the upper surface of the mobile table 14.

[0024] A movable table 24 is slidably mounted on the X-axis guide rail 22. A nut portion (not shown) is provided on the underside of the movable table 24. A screw shaft 26, positioned approximately parallel to the X-axis direction, is rotatably connected to the nut portion via a plurality of balls (not shown).

[0025] A drive source 28, such as a stepping motor, is connected to one end of the screw shaft 26. When the drive source 28 rotates the screw shaft 26, the mobile table 24 moves along the X-axis guide rail 22.

[0026] A rotary drive mechanism 30 having a cylindrical housing is provided on the upper surface of the movable table 24. The rotary drive mechanism 30 has a rotating shaft (not shown) that can be rotated by a drive source such as a motor. This rotating shaft is arranged substantially parallel to the Z-axis direction.

[0027] A disc-shaped chuck table (suction holding plate) 32 for suction holding the workpiece 11 is provided at the upper end of the rotating shaft. The chuck table 32 has a disc-shaped frame made of metal. A disc-shaped recess is formed on the upper surface of the frame.

[0028] A disc-shaped porous plate made of porous ceramics is fixed in this recess. Multiple grooves are formed radially on the bottom surface of the recess, and a cylindrical channel is formed so as to penetrate the center of the bottom surface of the recess.

[0029] A suction source (not shown), such as a vacuum pump, is connected to the cylindrical flow path via a solenoid valve (not shown). When the solenoid valve is opened while the suction source is operating, negative pressure is transmitted to the porous plate. The upper surface of the porous plate and the upper surface of the frame are formed to be substantially flush, forming a substantially flat holding surface 32a (see Figure 4) that holds the workpiece 11 by suction.

[0030] A laser beam irradiation unit 34 is positioned above the chuck table 32. The laser beam irradiation unit 34 is fixed to the tip of a cantilevered arm portion 8a that extends forward from the wall portion 8 (to the other side in the Y-axis direction).

[0031] The configuration of the laser beam irradiation unit 34 will now be explained with reference to Figures 2(A) and 2(B). Figure 2(A) is a perspective view of the laser beam irradiation unit 34. However, Figure 2(A) shows the laser beam irradiation unit 34 viewed from a different orientation than that shown in Figure 1. Figure 2(B) is a partial cross-sectional side view of the laser beam irradiation unit 34.

[0032] The laser beam irradiation unit 34 has a laser oscillator 36 that includes a laser medium. The laser medium is, for example, a rod such as an Nd:YVO4 crystal or an Nd:YAG crystal, or an optical fiber having a core doped with rare earth elements. The laser medium is irradiated with excitation light from an excitation light source (not shown), such as a laser diode.

[0033] When the laser medium receives excitation light and the laser oscillates, a laser beam L is emitted from the laser oscillator 36. For example, by Q-switched pulse oscillation, a pulsed, linearly polarized laser beam L with a predetermined repetition frequency is emitted from the laser oscillator 36.

[0034] The output (i.e., power) (in watts) of the laser beam L corresponds to the power of the excitation light emitted from the excitation source. For example, when using a laser diode as the excitation source, increasing the amount of current supplied between the N-side and P-side electrodes of the laser diode will increase the output of the laser beam L.

[0035] The wavelength of the laser beam L is set appropriately according to the type of laser processing. For example, when forming a weak region (modified region) that serves as the starting point for splitting in a workpiece 11, a laser beam L having a wavelength that penetrates the workpiece 11 (e.g., 1064 nm) is used.

[0036] Furthermore, when performing ablation processing on the workpiece 11, a laser beam L having a wavelength absorbed by the workpiece 11 (for example, 355 nm) is used. For example, by using a nonlinear optical crystal to wavelength-convert a laser beam L (fundamental wave) having a wavelength of 1064 nm, a laser beam L (third harmonic) having a wavelength of 355 nm can be obtained.

[0037] A nonlinear optical crystal (wavelength conversion unit) that converts the wavelength of the laser beam L may be provided inside the housing 38. The upper end of the cylindrical housing 38 is connected to the lower side of the laser oscillator 36 (the right side shown in Figures 2(A) and 2(B)).

[0038] One side 40a of a rectangular parallelepiped connecting member 40 is fixed to the lower end of the housing 38. The connecting member 40 is provided with an opening (not shown) for allowing the laser beam L to pass through.

[0039] On the other side 40b of the connecting member 40, which is located opposite to one side 40a, a lens mount 44 to which a focusing lens 42 is fixed is attached. The laser beam L emitted from the laser oscillator 36 is focused by the focusing lens 42 onto the workpiece 11 held by the chuck table 32 (see Figure 1).

[0040] In Figures 2(A) and 2(B), the optical axis 42a of the focusing lens 42 is shown by a dashed line. The optical axis 42a approximately coincides with the central axis of the housing 38. Note that, as will be described later, the optical axis 42a is not parallel to the Z-axis direction but is tilted with respect to the Z-axis direction.

[0041] A power measurement unit 46 is fixed to the side surface 40c of the connecting member 40, which is located between one surface 40a and the other surface 40b. The power measurement unit 46 is provided with a light receiving section 48, and an opening is formed in the side surface 40c to allow light to pass through to the light receiving section 48.

[0042] The light-receiving unit 48 is not located on the extension of the path of the laser beam L from the laser oscillator 36 to the focusing lens 42, and is positioned away from the optical axis 42a. In this embodiment, as shown in Figure 2(B), the light-receiving unit 48 is positioned at a predetermined distance from the optical axis 42a in a direction perpendicular to the optical axis 42a.

[0043] The light-receiving unit 48 does not receive the laser beam L that slightly passes through the mirror (i.e., transmitted light), but rather the laser beam L that has been reflected and scattered by optical components such as the focusing lens 42 (i.e., at least the focusing lens 42) (reflected and scattered light L in Figure 2(B)). A It receives light (which is written as ).

[0044] The laser beam L can be scattered due to fine irregularities on the surface of the focusing lens 42 or due to the crystalline structure inside the focusing lens 42, and it can also be reflected by the surface of the focusing lens 42. Furthermore, the scattered light may be scattered or reflected again.

[0045] Furthermore, if the condensing lens 42 is composed of a combination of multiple lenses, the light scattered by the first lens may be scattered or reflected by the surface of the second lens.

[0046] By the way, reflected and scattered light L A The power (in watts) may be lower than the power of the laser beam L that slightly penetrates the mirror. However, in this embodiment, by providing the housing 38 and connecting member 40 to the laser beam irradiation unit 34, even when the power is relatively small, the reflected and scattered light L A The light receiving unit 48 can measure it without any problems.

[0047] Furthermore, by providing the housing 38 and the connecting member 40, reflected and scattered light L A Another advantage is that it can reduce the amount of light incident on the light-receiving section 48 other than the light being received. Furthermore, an optical thin film such as an ND (Neutral Density) filter may be provided on the light-receiving section 48.

[0048] The light-receiving unit 48 includes a photoelectric conversion element such as a photodiode. The light-receiving unit 48 generates an electric charge corresponding to the amount of light it receives, and the generated charge is converted into a voltage value by an A / D conversion circuit (analog-to-digital converter) or the like (not shown) connected to the light-receiving unit 48. This voltage value signal is then output to a control unit 50, which will be described later.

[0049] As shown in Figure 1, the control unit 50 is composed of a computer having a processor (processing unit) 50a and a memory (storage device) 50b. The processor 50a is, for example, a CPU (Central Processing Unit).

[0050] Memory 50b includes main memory such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and ROM (Read Only Memory), and auxiliary memory such as flash memory, hard disk drives, and solid-state drives.

[0051] The auxiliary storage device stores software, including a predetermined program. By operating the processor 50a and other components according to this software, the functions of the control unit 50 are realized.

[0052] The control unit 50 has an estimation adjustment unit 52. The estimation adjustment unit 52 is realized by executing a predetermined program on the processor 50a. The estimation adjustment unit 52 adjusts the reflected and scattered light L based on predetermined relational formulas such as calculation formulas and tables. A It has the function of estimating the output of the laser beam L by converting the power of the device into the output of the laser beam L.

[0053] Figure 3 shows the power of the laser beam L at its focal point (horizontal axis, unit: W) and the reflected and scattered light L. A This graph shows the voltage value (vertical axis, unit: V) corresponding to the power, and the power output.

[0054] As shown in FIG. 3, an output measuring device such as a power meter (not shown) is arranged at the condensing point of the laser beam L to measure the power at the condensing point, and the reflected and scattered light L A is obtained by measuring the voltage value obtained by photoelectrically converting

[0055] As shown in FIG. 3, for the output (W) of the laser beam L at the condensing point and the voltage value (V) corresponding to the reflected and scattered light L A a linear approximation formula (the first approximation formula) holds.

[0056] Furthermore, for the power (nW) of the reflected and scattered light L A received by the light receiving unit 48 and the voltage value (V) output from the power measurement unit 46, it is known that a linear approximation formula (the second approximation formula) holds in a double logarithmic graph (not shown).

[0057] The estimation adjustment unit 52 estimates the output (power) of the laser beam L emitted from the laser oscillator 36 based on the power of the reflected and scattered light L A by using these first and second approximation formulas stored in advance in the memory 50b.

[0058] Therefore, in the present embodiment, the output of the laser beam L can be monitored without arranging a mirror on the optical path of the laser beam L and without interrupting the laser processing. Also, if a mirror is arranged on the optical path of the laser beam L, dirt attached to the mirror or the like may affect the laser processing performance. However, in the present embodiment, since no mirror is arranged, a decrease in the laser processing performance due to the mirror can be prevented.

[0059] Referring to FIG. 1 again, a microscope camera unit 54 is provided adjacent to the laser beam irradiation unit 34 at the tip of the arm portion 8a. An image obtained by imaging the workpiece 11 sucked and held by the chuck table 32 with the microscope camera unit 54 is displayed on the touch panel 56.

[0060] The touch panel 56 is located on the front side of an exterior material (i.e., a panel) not shown, which constitutes the outer surface of the laser processing apparatus 2. The touch panel 56 functions as a display device that shows images obtained by the microscope camera unit 54, as well as predetermined screens, characters, numbers, etc. In addition, the touch panel 56 also functions as an input device for inputting operator instructions to the control unit 50.

[0061] A cylindrical indicator light 58 is provided on the upper surface of the exterior material of the laser processing device 2. The indicator light 58 has an LED (Light Emitting Diode) lamp that lights up in a predetermined color such as red, yellow, or blue. By lighting up the LED lamp, the operating status of the laser processing device 2 can be notified to the operator.

[0062] The indicator light 58 is also equipped with a speaker (not shown). The speaker emits a predetermined sound to notify the operator of an abnormality or completion of processing, for example, when an abnormality occurs in the laser processing device 2 or when a pre-set processing stage is completed. The speaker may be provided separately from the indicator light 58 in the laser processing device 2.

[0063] At least one of the touch panel 56, indicator light 58, and speaker functions as an alarm unit whose operation is controlled by the control unit 50. When the output of the laser beam L estimated by the estimation adjustment unit 52 exceeds a predetermined range, the control unit 50 causes the alarm unit to issue an alarm.

[0064] For example, the touch panel 56 displays an alarm indicating that an abnormality has occurred using predetermined characters, colors, etc. The indicator light 58 illuminates a red LED lamp and sounds a predetermined alarm sound via a speaker to indicate that an abnormality has occurred.

[0065] If the estimated output of the laser beam L exceeds a predetermined range, the estimation adjustment unit 52 adjusts the output of the laser beam L so that the output of the laser beam L falls within the predetermined range. In other words, the estimation adjustment unit 52 functions as a laser beam output adjustment unit.

[0066] The estimation adjustment unit 52 adjusts the output of the laser beam L by, for example, changing the voltage value applied to the laser diode constituting the laser oscillator 36, thereby adjusting the amount of current injected into the laser diode.

[0067] By the way, when performing laser processing on the workpiece 11, first, as shown in Figure 4, the back surface 11b of the workpiece 11 is held in place by suction on the holding surface 32a. Note that multiple streets (planned division lines) 13 are set in a grid pattern on the front surface 11a of the workpiece 11.

[0068] A device 15 is formed in each of the rectangular regions demarcated by multiple streets 13. The devices 15 include ICs (Integrated Circuits), LEDs, MEMS (Micro Electro Mechanical Systems), etc.

[0069] Using the microscope camera unit 54, alignment is performed, and the orientation of the chuck table 32 is adjusted so that the street 13 is approximately parallel to the X-axis direction. Then, with the focusing point of the laser beam L positioned at a predetermined height near the surface 11a, the chuck table 32 is fed along the X-axis direction for machining.

[0070] In this manner, laser processing is performed on the workpiece 11 by irradiating it with a laser beam L. The laser beam L is a pulsed laser beam with linear polarization and has a predetermined wavelength that is transmitted through or absorbed by the workpiece 11.

[0071] As shown in Figure 4, the condensing lens 42 is positioned such that its optical axis 42a is not perpendicular to the holding surface 32a but is tilted by a predetermined angle α. Figure 4 is a partial cross-sectional side view showing the tilt of the optical axis 42a of the condensing lens 42.

[0072] In the YZ planar view of Figure 4, the angle of the optical axis 42a with respect to the normal 32b of the holding surface 32a (predetermined angle α) is, for example, 30 degrees. However, 30 degrees is just one example, and the predetermined angle α is not limited to 30 degrees.

[0073] If the optical axis 42a is made parallel to the normal 32b, the laser beam L reflected and scattered from the workpiece 11 is more likely to return to the laser beam irradiation unit 34, so the noise measured by the light receiving section 48 of the power measurement unit 46 will be larger compared to when the optical axis 42a is tilted.

[0074] In this embodiment, by tilting the optical axis 42a by a predetermined angle α with respect to the normal 32b, noise caused by reflection and scattering at the workpiece 11 can be reduced compared to the case where the optical axis 42a is parallel to the normal 32b, thus reducing reflected and scattered light L A This allows for higher measurement accuracy.

[0075] (Second Embodiment) Next, a second embodiment will be described with reference to Figure 5. Figure 5 is a partial cross-sectional side view of the laser beam irradiation unit 34 according to the second embodiment. The laser beam irradiation unit 34 of this embodiment does not have a housing 38. Therefore, the laser oscillator 36, lens mount 44, and power measurement unit 46 are each fixed to the arm portion 8a, not to the housing 38.

[0076] As shown in Figure 5, the power measurement unit 46 is tilted with respect to the optical axis 42a such that the light receiving unit 48 faces the surface of the focusing lens 42 on the laser oscillator 36 side. As a result, compared to the first embodiment, reflected and scattered light L A This makes it easier for light to enter the light-receiving unit 48.

[0077] Therefore, in the second embodiment, compared to the first embodiment, the reflected and scattered light L incident on the light receiving unit 48 is greater.A This has the advantage of increasing the amount of light and improving measurement sensitivity. A To block out light other than the specified light, the light-receiving section 48 may be provided with an optical thin film such as a bandpass filter or an ND filter.

[0078] (Third Embodiment) Next, a third embodiment will be described with reference to Figure 6. Figure 6 is a partial cross-sectional side view of the laser beam irradiation unit 34 according to the third embodiment. The laser beam irradiation unit 34 of this embodiment also does not have a housing 38. The laser oscillator 36, lens mount 44, and power measurement unit 46 are each fixed to the arm portion 8a, not to the housing 38.

[0079] As shown in Figure 6, the power measurement unit 46 is tilted with respect to the optical axis 42a such that the light receiving unit 48 faces the surface of the focusing lens 42 opposite to the laser oscillator 36 (i.e., the chuck table 32 side). As a result, compared to the first embodiment, the reflected and scattered light L A This makes it easier for light to enter the light-receiving unit 48.

[0080] Therefore, in the third embodiment as well, the reflected and scattered light L incident on the light receiving unit 48 is different from that in the first embodiment. A This has the advantage of increasing the amount of light and improving measurement sensitivity. A To block out light other than the specified light, the light-receiving section 48 may be provided with an optical thin film such as a bandpass filter or an ND filter.

[0081] (Modified Versions) Next, the first to third modified versions will be described with reference to Figures 7(A) to 7(C). Although the laser beam irradiation unit 34 in the first to third modified versions has a housing 38, it may also be configured without a housing 38, as in the second and third embodiments.

[0082] Figure 7(A) shows a first modified example of the laser beam output adjustment unit. In the first modified example shown in Figure 7(A), a half-wave plate 60 and a polarizer 62, positioned on the optical axis 42a, are used as the laser beam output adjustment unit.

[0083] The optical axis of the half-wave plate 60 is positioned perpendicular to the optical axis 42a. The half-wave plate 60 is mounted on a rotating mount 60a with a motor so that its optical axis can rotate around the optical axis 42a. For convenience, the rotating mount 60a is shown in a simplified form in Figure 7(A).

[0084] The rotation angle of the optical axis of the half-wave plate 60 by the rotating mount 60a is precisely controlled by the control unit 50 described above. The half-wave plate 60 has the function of rotating the vibration direction of linearly polarized light (for example, the vibration direction of the electric field) around the optical axis 42a. In contrast, the polarizer 62 is positioned on the optical axis 42a so as to transmit only linearly polarized light having a predetermined specific vibration direction.

[0085] By adjusting the vibration direction of linearly polarized light passing through the half-wave plate 60 using the rotating mount 60a, the output of the laser beam L irradiated from the laser beam irradiation unit 34 onto the workpiece 11 can be continuously adjusted between a state in which the laser beam L does not pass through the polarizer 62 at all (0%, i.e., crossed nicols) and a state in which it completely passes through the polarizer 62 (100%).

[0086] In the first modified example, the reflected and scattered light L from the condensing lens 42 is also present. A In addition, the reflected and scattered light L of the laser beam L is reflected and scattered by the half-wave plate 60. A This can also be received by the light receiving unit 48 of the power measurement unit 46.

[0087] Figure 7(B) shows a second modified example of the laser beam output adjustment unit. In this second modified example, an electro-optic modulator (EOM) 64 is provided on the optical axis 42a instead of the half-wave plate 60.

[0088] The electro-optic modulator 64 has the function of rotating the direction of oscillation of linearly polarized light around the optical axis 42a according to the voltage value applied to the electro-optic modulator 64. In other words, in the second modified example, the electro-optic modulator 64 and the polarizer 62 are used as a laser beam output adjustment unit. In the second modified example as well, the output of the laser beam L irradiated onto the workpiece 11 can be adjusted steplessly.

[0089] Figure 7(C) shows a third modified example of the laser beam output adjustment unit. In this third modified example, an acousto-optic modulator (AOM) 66 is mounted on the optical axis 42a. In this third modified example, the acousto-optic modulator 66 is used as the laser beam output adjustment unit.

[0090] When a predetermined voltage is applied to the acousto-optic modulator 66, the laser beam L is diffracted due to the acousto-optic effect. At this time, the laser beam L is diffracted such that, for example, the first diffracted light has the highest power.

[0091] By setting the optical system so that the first-order diffracted light is not directed towards the focusing lens 42, the acousto-optic modulator 66 functions as a switch element that switches between an ON state, which outputs the laser beam L, and an OFF state, which does not output the laser beam L.

[0092] For example, if the output of the laser beam L estimated by the estimation adjustment unit 52 exceeds a predetermined range, the control unit 50 applies a predetermined voltage to the acousto-optic modulator 66 to turn off the laser beam L. This prevents abnormal laser processing of the workpiece 11.

[0093] Furthermore, the structures, methods, etc., according to the embodiments described above can be modified as appropriate without departing from the scope of the object of the present invention. The first to third modifications may also be applied to the second or third embodiment.

[0094] Furthermore, although the above description mentions an example where the laser beam irradiation unit 34 is located on the upper side and the chuck table 32 is located on the lower side, the chuck table 32 may also be located on the upper side and the laser beam irradiation unit 34 on the lower side.

[0095] The above-described embodiments and modifications can also be applied to a laser processing apparatus in which a workpiece 11 is held by suction using a chuck table 32 located on the upper side, and a laser beam L is irradiated onto the workpiece 11 from a laser beam irradiation unit 34 located on the lower side. [Explanation of symbols]

[0096] 2: Laser processing device, 4: Base, 6: Flat plate section, 8: Wall section, 8a: Arm section 10: Y-axis movement unit, 12: Y-axis guide rail, 14: Movement table 11: Workpiece, 11a: Front surface, 11b: Back surface, 13: Street, 15: Device 16: Screw shaft, 18: Drive source 20: X-axis movement unit, 22: X-axis guide rail, 24: Movement table 26: Screw shaft, 28: Drive source 30: Rotary drive mechanism, 32: Chuck table, 32a: Holding surface, 32b: Normal vector 34: Laser beam irradiation unit, 36: Laser oscillator 38: Housing, 40: Connecting member, 40a: One side, 40b: Other side, 40c: Side 42: Focusing lens, 42a: Optical axis, 44: Lens mount 46: Power measurement unit, 48: Light receiving unit 50: Control unit, 50a: Processor, 50b: Memory, 52: Estimation adjustment unit 54: Microscope camera unit, 56: Touch panel, 58: Indicator light 60: Half-wave plate, 60a: Rotating mount, 62: Polarizer 64: Electro-optic modulator, 66: Acousto-optic modulator L: Laser beam, L A :Reflected scattered light, α: Predetermined angle

Claims

1. A laser processing device, A suction holding plate for holding the workpiece by suction, A laser beam irradiation unit that irradiates a laser beam onto the workpiece held by the suction holding plate, An alarm unit that issues an alarm when the output of the laser beam exceeds a predetermined range, A control unit comprising memory and a processor, which controls the operation of the alarm unit, Equipped with, The laser beam irradiation unit is Laser oscillator and, A focusing lens for focusing the laser beam emitted from the laser oscillator, A power measuring unit that measures the power of the laser beam reflected and scattered by the focusing lens, It has, The laser beam irradiation unit and the suction holding plate are arranged relative to each other such that the path of the laser beam extending from the focusing lens to the holding surface of the suction holding plate is not perpendicular to the holding surface of the suction holding plate but is tilted by a predetermined angle. The control unit is, Based on the power measured by the power measurement unit, the output of the laser beam emitted from the laser oscillator is estimated. A laser processing apparatus characterized in that it issues an alarm to the alarm unit when the estimated output of the laser beam exceeds a predetermined range.

2. The laser processing apparatus according to claim 1, wherein the power measurement unit has at least a light-receiving section that receives the laser beam reflected and scattered by the focusing lens, and the light-receiving section is not located on the extension of the path of the laser beam from the laser oscillator to the focusing lens, and is located away from the optical axis of the focusing lens.

3. The laser processing apparatus according to claim 1, further comprising a laser beam output adjustment unit that adjusts the output of the laser beam so that the output of the laser beam, estimated based on the power measured by the power measuring unit, falls within a predetermined range.

4. The laser processing apparatus according to any one of claims 1 to 3, characterized in that the focusing lens is arranged such that the optical axis of the focusing lens is not perpendicular to the holding surface of the suction holding plate but is tilted by a predetermined angle.

Images