JP2008036641A - Laser beam machining apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus and method capable of increasing machining speed for a workpiece. <P>SOLUTION: Laser light sources 200, 300, 400 each generate a machining laser beam different in parameter. Lens pairs 230, 330, 430 adjust a spreading angle when the laser beams of parallel light generated by the laser light sources 200, 300, 400 are made incident on an objective lens 500. Mirrors 240, 340, 440 are each provided with a different tilt angle, reflecting the laser beams from telescope optical systems 210, 310, 410 to the objective lens 500. The objective lens 500 converges the laser beams made incident from the mirrors 240, 340, 440 and continuously emits the converged laser beam to a plurality of converged irradiation positions which are different with respect to both the depth direction of the workpiece S and the direction orthogonal thereto. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly, to a laser processing apparatus and a laser processing method that cause damage to a material to be processed.

  The industrial usefulness of microfabrication technology for dielectric materials used as devices such as semiconductors and various substrates is now in doubt. Conventionally, a mechanical processing technique using a diamond blade has been used as a fine processing technique by scribing and dicing. These processing techniques are sufficiently matured as mechanical processing techniques, but have certain limitations with respect to processing resolution, processing shape control, chip reduction, and the like.

  On the other hand, in recent years, laser processing technology has attracted much attention in place of such mechanical processing technology. According to the laser processing technology by laser scribing and laser dicing, the problems in the mechanical processing technology described above can be greatly improved.

  As a conventional laser processing technique, for example, there is one described in Patent Document 1.

Patent Document 1 discloses a technique for condensing two laser beams having different wavelengths from each other inside a workpiece by a condenser lens to form two modified regions inside the workpiece. ing. Of the two laser beams, the focal point of the long wavelength laser beam is adjusted to a deep position from the surface of the workpiece, and the focal point of the short wavelength laser beam is shallow from the surface of the workpiece. Adapted. In this state, the stage on which the workpiece is placed is driven along the planned cutting line of the processing target, so that the two condensing points are scanned along the planned cutting line, and 1 along the planned cutting line. Two modified regions can be formed by one scan.
JP 2004-337903 A

  However, in the conventional laser processing technology, when a typical laser device currently on the market is used for laser processing, the performance does not necessarily satisfy the desired laser processing in terms of output and pulse oscillation frequency. There is a problem that is not.

  Among them, a major problem is that the processing speed defined by the scribing distance or dicing distance per unit time is low. In the current laser apparatus, even when the output and pulse oscillation frequency are maximized, the time required for processing at a desired depth (several tens of μm or more) is mechanical processing, for example, processing using a diamond blade. It takes several times to about 10 times the time required for. This is because the processing depth per pulse is small, and it is necessary to scan the irradiated laser so that a plurality of lasers repeatedly supplied spatially overlap on the processing surface. In order to improve the processing speed while satisfying such an irradiation mode, it is conceivable to increase the repetition frequency of the laser. However, there is a limit in the current technology, and it is not easy to realize a desired processing speed. .

  Even when laser processing is performed using two condensing points by two laser beams as in the laser processing technique described in Patent Document 1, the processing speed has a certain limit. This is because the two light condensing points are located on the same axis perpendicular to the line to be cut, that is, on the same axis perpendicular to the surface of the workpiece. In other words, the processing speed in the depth direction of the processing target can be improved, but the processing speed in the direction intersecting the depth direction of the processing target, for example, the scanning direction of the condensing point cannot be improved.

  In addition, the lack of knowledge about the shape of the condensing point, which is an important factor for forming a processing region on the processing target, is also one of the limitations of the above-described improvement in processing speed.

  This invention is made | formed in view of this point, and it aims at providing the laser processing apparatus and laser processing method which can improve the processing speed to a workpiece.

  The laser processing apparatus of the present invention includes a first focused irradiation position determining unit that determines a focused irradiation position of each of the plurality of laser beams in the depth direction of the workpiece, and an incident angle of the plurality of laser beams. A second condensing irradiation position determining means for adjusting and determining respective condensing irradiation positions of the plurality of laser beams in a direction perpendicular to the depth direction of the workpiece; and the first condensing irradiation An objective lens for continuously condensing and irradiating each of the plurality of laser beams to a plurality of condensing irradiation positions determined by a position determining unit and the second condensing irradiation position determining unit; and the plurality of laser beams Scanning means for scanning the focused irradiation position in a direction orthogonal to the depth direction of the workpiece, at least one of the focused irradiation positions of the plurality of laser beams is the workpiece The direction perpendicular to the depth direction of Te, take different configurations and other condensing irradiation position.

  In the laser processing method of the present invention, a first focused irradiation position determining step for determining a focused irradiation position of each of the plurality of laser beams in the depth direction of the workpiece, and an incident angle of the plurality of laser beams are determined. A second condensing irradiation position determining step for adjusting and determining respective condensing irradiation positions of the plurality of laser beams in a direction orthogonal to the depth direction of the workpiece; and the first condensing irradiation. A plurality of condensing irradiation steps for continuously condensing and irradiating each of the plurality of laser beams to a plurality of condensing irradiation positions determined by the position determining step and the second condensing irradiation position determining step; A scanning step of scanning a laser beam condensing irradiation position in a direction orthogonal to a depth direction of the workpiece, and at least one of the plurality of laser light condensing irradiation positions is the processing Of the object It is in the direction perpendicular to the direction, and so different from the other converging and irradiating positions.

  According to the present invention, it is possible to improve the processing speed of a processing object. Further, it is possible to control the shape of damage caused to the workpiece.

(Basic principle)
First, the basic principle of the present invention will be described.

The laser processing technology of the present invention
(1) a first focused irradiation position determining step for determining a focused irradiation position of each of the plurality of laser beams in the depth direction of the workpiece;
(2) Second condensing irradiation for adjusting respective incident angles of the plurality of laser beams to determine respective condensing irradiation positions of the plurality of laser beams with respect to a direction orthogonal to the depth direction of the workpiece. A positioning step;
(3) Continuously irradiate each of the plurality of laser beams to the plurality of condensing irradiation positions determined by the first condensing irradiation position determining step and the second condensing irradiation position determining step. A condensing irradiation step,
(4) a scanning step of scanning the focused irradiation positions of the plurality of laser beams in a direction orthogonal to the depth direction of the workpiece,
(5) At least one of the condensing irradiation positions of the plurality of laser beams is different from other condensing irradiation positions in a direction orthogonal to the depth direction of the workpiece.

  The workpiece is, for example, a dielectric material such as glass, quartz, or sapphire, or a semiconductor material such as silicon or silicon carbide (SiC). Further, the object to be processed may be, for example, a metal such as copper or stainless steel and various alloys. Further, the “depth direction of the workpiece” means a direction orthogonal to the surface of the workpiece.

The plurality of laser beams may be, for example, a plurality of laser beams having different parameters such as wavelength, pulse width, power, or repetition frequency, or may be the same laser beam having the same parameters. The plurality of laser beams are a fundamental wave (wavelength 1064 nm), second harmonic wave (wavelength 532 nm), third harmonic wave (wavelength 355 nm), and fourth harmonic wave (wavelength 266 nm) of a nanosecond to picosecond pulse oscillation YAG laser. Laser light such as femtosecond to picosecond titanium sapphire laser and its harmonics, or parametric oscillation light (wavelength 400 nm to 2000 nm). Further, the plurality of laser beams may be various CW (Continuous Wave) lasers, carbon dioxide (CO ₂ ) lasers, lasers with different media, and the like. The plurality of laser beams may be generated by separate laser light sources or may be generated by one laser light source.

  The focused irradiation position of the laser beam in the depth direction of the workpiece can be determined by the spread angle of the laser beam when it enters the objective lens.

  More specifically, the condensing irradiation position of the laser beam in the depth direction of the workpiece is determined closer to the surface of the workpiece in the depth direction of the workpiece as the spread angle of the laser beam is smaller. Is done. Further, the condensing irradiation position of the laser light in the depth direction of the processing object is determined at a position farther from the surface of the processing object in the depth direction of the processing object as the spread angle of the laser light is larger. Here, the “expansion angle” decreases in proportion to the degree of aperture reduction, and increases in proportion to the extent of aperture expansion. “Laser beam having a negative spread angle” means a laser beam that is incident while the aperture is narrowed, and “laser beam having a positive spread angle” is a laser beam that is incident while the aperture is enlarged. . Furthermore, “laser light with a zero spread angle” means laser light that is parallel light.

  The spread angle of the laser light when entering the objective lens can be changed, for example, by passing the laser light through a lens pair composed of a concave lens and a convex lens. More specifically, the spread angle of the laser light when entering the objective lens can be controlled by adjusting the distance between the concave lens and the convex lens constituting the lens pair, or its numerical aperture NA (Numerical Aperture). it can.

  The spread angle of the laser light when entering the objective lens is allowed to pass through, for example, an optical system constituted by at least one concave lens or convex lens, or a combination thereof, in addition to the lens pair as described above. Can also change. As described above, the spread angle of the laser light when entering the objective lens can be changed using various optical systems.

  The focused irradiation position of the laser beam with respect to the direction orthogonal to the depth direction of the workpiece can be determined by the incident angle of the laser beam to the objective lens.

  The incident angle of the laser light on the objective lens can be changed by reflecting the laser light using a mirror, for example. More specifically, the incident angle of the laser beam to the objective lens can be controlled by adjusting the tilt angle of the mirror.

  As described above, the position of the focus image formed by the focused irradiation of the laser light can be determined by the spread angle of the laser light when entering the objective lens and the incident angle of the laser light on the objective lens.

  In the present invention, each of a plurality of laser beams is provided at a plurality of condensing irradiation positions determined by adjusting the spread angle of the laser beam when entering the objective lens and the incident angle of the laser beam to the objective lens. Is continuously focused and irradiated.

  “Continuous” means that laser light that is first condensed and irradiated among a plurality of laser beams is irradiated with another laser beam once in a time-series manner (hereinafter referred to as “one-cycle condensing”). Irradiation) ”. In other words, after the laser beam first focused and irradiated, other laser beams are successively focused and irradiated.

  Here, the focus images formed by condensing and irradiating a plurality of laser beams may or may not overlap each other. In the former case, a plurality of laser beams that are focused and irradiated for one cycle form a series of focused images that are spatially overlapped. Even in the latter case, the positions where the plurality of laser beams are focused and irradiated are overlapped with the damage or modified region caused by the focused irradiation of the laser beams to be followed, respectively. It is preferable to set. In this way, each of the plurality of laser beams is always focused on the damaged or modified region caused by the focused irradiation of the other laser beams, and the processing speed is dramatically increased. We can expect improvement.

  The condensing irradiation positions of the plurality of laser beams irradiated with one cycle of condensing irradiation can be scanned by driving the stage on which the object to be processed is placed along the processing line. More specifically, this stage is driven by a predetermined distance along the planned processing line each time a plurality of laser beams are condensed and irradiated to the processing object for one cycle. Here, the one-time driving distance of the stage is preferably included in the width of the damaged or modified region caused by the focused irradiation of the respective laser beams. In this way, one-cycle focused irradiation of a plurality of laser beams is continuously performed with respect to the processing scheduled line.

  Here, the “scheduled processing line” means, for example, a direction orthogonal to the depth direction of the processing object.

  As a result of diligent research, the present inventor has found that, in a laser processing technique that causes damage to a processing target, at least one of the plurality of laser beam condensing irradiation positions is orthogonal to the depth direction of the processing target. It has been found that it is effective to improve the processing speed to be different from other focused irradiation positions with respect to the direction. In addition, the present inventor has found that the converging irradiation positions of the plurality of laser beams are different from each other in both the depth direction of the processing object and the direction orthogonal to the depth direction of the processing object. We found it more effective for improvement.

  The “positions different from each other” herein mean positions that are neither coaxial with the depth direction of the workpiece or coaxial with the direction orthogonal to the depth direction of the workpiece.

  Further, the laser processing technology of the present invention is the above-described laser processing technology, wherein the plurality of laser beams are arranged so that a focused image formed when the plurality of laser beams are condensed and irradiated has a tetrahedral shape. A step of adjusting may further be included.

  A focal image having a tetrahedral shape can be formed by passing laser light through an astigmatism optical system including, for example, a concave cylindrical lens, a convex cylindrical lens, and a circular lens.

  Here, the concave cylindrical lens diverges only one component of the laser beam, for example, the horizontal component in the horizontal direction, and transmits the other component of the laser beam, for example, the vertical component as it is. The convex cylindrical lens reduces only one component of the laser beam, for example, the horizontal component in the horizontal direction, and transmits the other component of the laser beam, for example, the vertical component as it is. The circular lens narrows down the horizontal component and the vertical component of the laser beam to form a linear focus of the horizontal component and a linear focus in the vertical direction.

  Of course, the concave cylindrical lens and the convex cylindrical lens can be configured so as to act only on the horizontal component and not on the vertical component by changing the structure or arrangement direction thereof.

  In this way, the concave cylindrical lens and the convex cylindrical lens diverge and reduce only one of the mutually orthogonal components of the laser beam, so that the focus image of one component of the laser beam and the other component of the laser beam These focal images are formed on different focal planes. More specifically, the focus image of one component of the laser beam and the focus image of the other component are a pair of linear focal points orthogonal to each other formed on different focal planes due to astigmatism.

  The horizontal component focus image and the vertical component focus image of the laser light that are twisted and orthogonal to each other are a tetrahedral focus that is a processing region virtually formed by the mutual force between these focus images. An image is formed.

  Further, the length of each of the pair of focus images and the distance between these focus images can be controlled by adjusting parameters such as the focal position, the arrangement distance, and the tilt angle of the cylindrical lens. As a result, the shape of the tetrahedral focus image can be controlled. Therefore, it is possible to control the shape of damage caused to the workpiece within a predetermined range. For example, by increasing the length of the focal image on the surface side of the object to be processed among a pair of linear focal points orthogonal to each other, the scribing groove generated on the object to be processed is formed into a wide V-shape. be able to. Further, by reducing the length of the focal image on the surface side of the workpiece, of a pair of linear focal points orthogonal to each other, the scribing groove generated in the workpiece is made into a sharp V-shape. be able to.

  By processing the object to be processed using the tetrahedral focus image whose shape is controlled, it becomes possible to cause damage to the object to be processed in a desired shape.

  The astigmatism optical system is not necessarily limited to the configuration described above. For example, the astigmatism optical system can be configured by at least one concave cylindrical lens, convex cylindrical lens, circular lens, or a combination thereof.

  As described above, the depth direction of the workpiece and the depth of the workpiece can be adjusted by adjusting the spread angle of the laser beam when entering the objective lens and the incident angle of the laser beam to the objective lens. The feature of continuously condensing and irradiating a plurality of laser beams at different positions with respect to not only one of the directions orthogonal to the direction is the present invention from the viewpoint of improving the processing speed on the processing object. This is a new finding that has come to mind.

  In addition to the above features, the focus image formed at the laser beam condensing irradiation position, that is, the feature that the processing region is controlled to a tetrahedral shape is the feature that the processing speed to the processing object is improved. In addition, this is a new finding that the present inventors have conceived from the viewpoint of controlling the processing shape.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing an example of the configuration of a laser processing apparatus 100 according to Embodiment 1 of the present invention.

  In FIG. 1, a laser processing apparatus 100 includes laser light sources 200, 300, 400, telescope optical systems 210, 310, 410, mirrors 240, 340, 440, an objective lens 500, a protective window plate 510, a stage 520, and a measuring instrument. A light source 530, a beam shaper 540, a half mirror 550, a photodetector 560, a controller 570, an illumination light source 580, a CCD (Charge-Coupled Devices) camera 590, a computer 600, and a monitor 610 are provided.

  Laser light sources 200, 300, and 400 serving as laser light generating means generate single-pulse laser light for processing for condensing and irradiating the workpiece S. The laser light generated by the laser light source 200, 300, 400 is, for example, a fundamental wave (wavelength 1064 nm), a second harmonic wave (wavelength 532 nm), or a third harmonic wave (wavelength 355 nm) of a nanosecond to picosecond pulse oscillation YAG laser. ), Or the fourth harmonic (wavelength 266 nm). As the laser light generated by the laser light sources 200, 300, and 400, a femtosecond to picosecond titanium sapphire laser, its harmonics, parametric oscillation light (wavelength 400 nm to 2000 nm), and the like can be used. Further, as the laser light, various CW lasers, carbon dioxide lasers, lasers with different media, and the like can be used.

  The laser light sources 200, 300, and 400 can change the parameters of the generated laser light, such as the wavelength, the pulse width, the power, and the repetition frequency, respectively. The laser light sources 200, 300, and 400 can change the wavelength of the generated laser light in the range of 266 nm to 2000 nm. The laser light sources 200, 300, and 400 can change the pulse width of the generated laser light in the range of 10 fs to 100 ns. The laser light sources 200, 300, and 400 can change the power of the generated laser light in the range of 0.1W to 5.0W. The laser light sources 200, 300, and 400 can change the repetition frequency of the generated laser beam in the range of 30 kHz to 500 kHz. Various parameters of laser light generated by the laser light sources 200, 300, and 400 are controlled by control signals from the computer 600.

  The telescope optical system 210 includes a variable ND (Neutral Density) filter 220 and a lens pair 230. The telescope optical system 310 includes a variable ND filter 320 and a lens pair 330. The telescope optical system 410 includes a variable ND filter 420 and a lens pair 430.

  The variable ND filter 220 transmits part of the laser light generated by the laser light source 200 and reflects or absorbs other parts. The variable ND filter 220 is configured, for example, by coating chrome on the surface of glass, and the transmittance can be varied by adjusting the film thickness of the chrome. Thereby, the pulse energy of the laser beam generated by the laser light source 200 can be adjusted to a desired value.

  It should be noted that as an optical component that performs the function of the variable ND filter 220, an attenuation mechanism that combines polarization optical components can be substituted.

  The lens pair 230 as the first focused irradiation position determining means is configured by a combination of a concave lens 231 and a convex lens 232 (see FIG. 2A). The lens pair 230 adjusts the aperture when the laser light transmitted through the variable ND filter 220 enters the objective lens 500 and the spread angle of the laser light. In the example of FIG. 2A, the lens pair 230 adjusts the spread angle of the laser light that is parallel light generated by the laser light source 200 so that the spread angle becomes negative. The aperture of the laser beam and the spread angle of the laser beam when entering the objective lens 500 can be controlled by adjusting the distance between the concave lens 231 and the convex lens 232 constituting the lens pair 230 or the numerical aperture NA thereof. .

  The condensing irradiation position of the laser light in the depth direction of the workpiece S is determined by the spread angle of the laser light when entering the objective lens 500 adjusted by the lens pair 230.

  More specifically, the condensing irradiation position of the laser beam with respect to the depth direction of the workpiece S is closer to the surface of the workpiece S with respect to the depth direction of the workpiece S as the spread angle of the laser beam is smaller. Determined in position. Further, the condensing irradiation position of the laser beam in the depth direction of the workpiece S is determined at a position farther from the surface of the workpiece S in the depth direction of the workpiece S as the spread angle of the laser beam is larger. The

  The variable ND filter 320 and the lens pair 330 of the telescope optical system 310 perform processing similar to that of the telescope optical system 210 described above on the laser light generated by the laser light source 300. In addition, the variable ND filter 420 and the lens pair 430 of the telescope optical system 410 perform the same processing as the telescope optical systems 210 and 310 on the laser light generated by the laser light source 400.

  Here, the distances between the concave lenses 231, 331, 431 and the convex lenses 232, 332, 432 constituting the lens pairs 230, 330, 430 or their numerical apertures NA are set to different values. Therefore, the lens pairs 230, 330, and 430 adjust the laser light generated by the laser light sources 200, 300, and 400 so that the spread angles when entering the objective lens 500 are different from each other (FIG. 2A to FIG. 2). 2 (C)).

  In this example, the laser light adjusted by the lens pair 230 has a negative divergence angle, that is, laser light that is incident while the aperture is reduced, and the laser light adjusted by the lens pair 330 has a divergence angle of zero. That is, it is parallel light, and the laser light adjusted by the lens pair 430 is laser light that is incident while the spread angle is positive, that is, the aperture is enlarged.

  Then, the laser light adjusted by the lens pair 230 is condensed and irradiated on the position closest to the surface of the processing object S in the depth direction of the processing object S, for example, substantially the same surface as the surface of the processing object S. . Further, the laser light adjusted by the lens pair 330 is condensed and irradiated from the surface of the processing object S to the position next to the laser light adjusted by the lens pair 230 in the depth direction of the processing object S. . In addition, the laser light adjusted by the lens pair 430 is condensed and irradiated from the surface of the processing object S to the position next to the laser light adjusted by the lens pair 330 in the depth direction of the processing object S. .

  The mirror 240 as the second focused irradiation position determining means reflects the laser light from the telescope optical system 210 downward without losing its energy and makes it incident on the objective lens 500. The incident angle of the laser beam on the objective lens 500 can be controlled by adjusting the tilt angle of the mirror 240. The condensing irradiation position of the laser light in the direction orthogonal to the depth direction inside the workpiece S is determined by the incident angle of the laser light on the objective lens 500.

  Further, the mirror 240 allows the measurement laser light input from the half mirror 550 to pass through approximately 100% and enter the objective lens 500.

  The mirror 340 performs the same processing as the above-described mirror 240 on each of the laser light from the telescope optical system 310 and the measurement laser light from the half mirror 550. The mirror 440 performs the same processing as the mirrors 240 and 340 on the laser light from the telescope optical system 410 and the measurement laser light from the half mirror 550, respectively.

  Here, the tilt angles of the mirrors 240, 340, and 440 are set to different values. Therefore, the mirrors 240, 340, and 440 reflect the laser beams from the telescope optical systems 210, 310, and 410 to the objective lens 500 at different incident angles, respectively (see FIGS. 3A to 3C). . In this example, the mirror 240 has the largest tilt angle, the mirror 340 has the second largest tilt angle, and the mirror 440 has the smallest tilt angle.

  Therefore, the laser beam reflected by the mirror 240 is focused and irradiated on the processing start position in the direction orthogonal to the depth direction of the processing target S. Further, the laser beam reflected by the mirror 340 is condensed and irradiated at a position closest to the processing start position in a direction orthogonal to the depth direction of the processing target S. Further, the laser light reflected by the mirror 440 is condensed and irradiated from the processing start position to a position next to the laser light reflected by the mirror 340 with respect to a direction orthogonal to the depth direction of the workpiece S. .

  The objective lens 500 condenses the laser light incident from the mirrors 240, 340, and 440. The objective lens 500 continuously irradiates the condensed laser light on either the upper side of the workpiece S, the substantially same surface as the surface of the workpiece S, or the inside of the workpiece S. Thereby, a focus image is formed at the focused irradiation position of the laser beam.

  Here, the laser beams incident on the objective lens 500 from the mirrors 240, 340, and 440 have different spread angles and incident angles as described above. Therefore, the objective lens 500 has a plurality of different laser beams incident from the mirrors 240, 340, and 440 in both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S. Irradiate continuously to the focused irradiation position.

  The protective window plate 510 protects the objective lens 500 from minute debris scattered from the surface of the processing object S when processing the substantially same surface as the surface of the processing object S.

  A stage 520 as a scanning unit is a stage on which the workpiece S is placed. The stage 520 moves in parallel along the XYZ axes so as to change the focused irradiation position of the laser beam on the processing target S placed thereon. The stage 520 rotates about any of the XYZ axes. That is, the stage 520 scans the focused irradiation position of the laser beam on the workpiece S along an arbitrary scheduled processing position or scheduled processing line by driving the XYZ axis coordinates. As a result, the laser beam can be focused and applied to a desired position of the workpiece S placed on the stage 520.

  More specifically, the stage 520 is driven by a predetermined distance along the planned processing line every time the laser light incident from the mirrors 240, 340, and 440 is condensed and irradiated for one cycle. Here, it is preferable that the driving distance of the stage 520 with respect to one-cycle focused irradiation is such that it is included in the size of the damaged or modified region caused by the focused irradiation of each laser beam. As a result, the laser light focused and irradiated for one cycle from the mirrors 240, 340, and 440 is continuously focused and irradiated with respect to the processing scheduled line.

  The stage 520 incorporates a high-resolution sensor (for example, a capacitance sensor) (not shown), and has a driving resolution of, for example, several nanometers to several tens of nanometers. The driving of the stage 520 is precisely controlled by the computer 600 via the controller 570. For example, information indicating the processing position or processing line on the processing object S is stored in the computer 600, and the stage 520 is scanned based on this information, so that the processing object S is moved to a desired position. Laser light can be focused and irradiated. Further, the scanning speed of the stage 520 is controlled by the computer 600 via the controller 570.

  The measurement light source 530 generates measurement laser light for measuring the position of the surface of the workpiece S placed on the stage 520 in accordance with a control signal from the computer 600.

  The beam shaper 540 adjusts the beam shape of the measurement laser light generated by the measurement light source 530. Thereby, the laser beam for measurement is optimized.

  The half mirror 550 reflects and transmits the measurement laser beam optimized by the beam shaper 540 in a translucent manner. That is, the half mirror 550 transmits the measurement laser beam input from the beam shaper 540. The measurement laser light passes through the mirrors 240, 340, 440 and the objective lens 500, reaches the surface of the workpiece S, and is reflected. This reflected light again passes through the objective lens 500 and the mirrors 240, 340, and 440 and enters the half mirror 550. The half mirror 550 further reflects this reflected light and makes it incident on the photodetector 560.

  The light detector 560 detects the reflected light from the surface of the workpiece S incident from the half mirror 550 and detects the position of the surface of the workpiece S. The photodetector 560 outputs the detection result to the controller 570.

  The controller 570 includes a feedback circuit (not shown). The controller 570 uses this feedback circuit to determine whether or not the focused irradiation position of the laser beam is a processing target position on the processing object S or based on the information on the surface position of the processing object S input from the photodetector 560. The stage 520 is feedback-controlled so as to match the planned processing line.

  The illumination light source 580 is disposed above the stage 520, and generates illumination light for observing the processing site of the processing object S placed on the stage 520.

  The CCD camera 590 takes in the illumination light emitted from the illumination light source 580 and transmitted through the object to be processed, and images the condensing irradiation position of a part of the laser light of the object S to be processed. Further, the CCD camera 590 outputs the captured data to the computer 600.

  The computer 600 is connected to the laser light sources 200, 300, 400, the measurement light source 530, the controller 570, and the CCD camera 590, and comprehensively controls each of these units. For example, the computer 600 drives the stage 520 through feedback control by the controller 570 to scan the focused irradiation position of the laser light along the planned processing position or the planned processing line of the processing target S. The computer 600 can control the start or stop timing of laser light irradiation and the stage operation in synchronization.

  The monitor 610 displays the image data of the CCD camera 590 via the computer 600. Thereby, the process part of the process target S, ie, the damage which arose in the process target S, can be observed.

  Hereinafter, the operation of the laser processing apparatus 100 configured as described above will be described in detail with reference to FIG.

  FIG. 4 is a diagram illustrating an example of occurrence of damage to the workpiece S by the laser processing apparatus 100.

  Here, it is assumed that the “direction perpendicular to the depth direction of the workpiece S” is the scanning direction of the laser beam condensing irradiation position, that is, the processing target line of the workpiece S.

  First, the laser light sources 200, 300, and 400 generate a single pulse laser beam for processing for condensing and irradiating the workpiece S according to a control signal from the computer 600. The laser beams generated by the laser light sources 200, 300, and 400 may be laser beams having different parameters such as wavelength, pulse width, power, or repetition frequency, or the same laser beams having the same parameters. There may be. Here, laser light generated by the laser light source 200 is denoted by L1, laser light generated by the laser light source 300 is denoted by L2, and laser light generated by the laser light source 400 is denoted by L3. The pulse energy of the laser light L1 is adjusted by the variable ND filter 220. Similarly, the pulse energy of the laser beam L2 is adjusted by the variable ND filter 320, and the pulse energy of the laser beam L3 is adjusted by the variable ND filter 420.

  The lens pair 230 adjusts the aperture when the laser light L1 transmitted through the variable ND filter 220 enters the objective lens 500, and the spread angle of the laser light L1. The lens pair 330 adjusts the aperture when the laser light L2 transmitted through the variable ND filter 320 enters the objective lens 500, and the spread angle of the laser light L2. The lens pair 430 adjusts the aperture when the laser light L3 transmitted through the variable ND filter 420 enters the objective lens 500, and the spread angle of the laser light L3.

  In this example, the aperture when the laser beam L1 enters the objective lens 500 is the smallest, the aperture when the laser beam L2 enters the objective lens 500 is the second smallest, and the laser beam L3 enters the objective lens 500. The aperture is the largest.

  The laser beam L1 has a negative spread angle, that is, a laser beam that is incident while the aperture is reduced, the laser beam L2 has a zero spread angle, that is, a parallel beam, and the laser beam L3 has a spread range. The laser beam is incident at a positive angle, that is, with an enlarged aperture.

  The mirror 240 reflects the laser light L1 and makes it incident on the objective lens 500. The mirror 340 reflects the laser beam L2 and makes it incident on the objective lens 500. The mirror 440 reflects the laser beam L3 and makes it incident on the objective lens 500. In this example, as shown in FIGS. 3A to 3C, the mirrors 240, 340, and 440 have different tilt angles, so that the laser beams L1, L2, and L3 are different from each other. The light enters the objective lens 500 at an incident angle.

  The objective lens 500 condenses the laser light L1 incident from the mirror 240 and irradiates the surface substantially the same as the surface of the workpiece S, for example. Thereby, the focus image P1 is formed at the condensing irradiation position of the laser beam L1.

  The objective lens 500 condenses the laser beam L2 incident from the mirror 340 and irradiates the laser beam L2, for example, at a position overlapping the focal image P1 inside the workpiece S. Thereby, the focus image P2 is formed at the condensing irradiation position of the laser beam L2. Here, the focus image P2 is formed at a position different from the focus image P1 in both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S.

  The objective lens 500 condenses the laser beam L3 incident from the mirror 440 and irradiates the laser beam L3, for example, at a position overlapping the focal image P2 inside the workpiece S. Thereby, the focus image P3 is formed at the condensing irradiation position of the laser beam L3. Here, the focus image P3 is formed at a position different from the focus images P1 and P2 in both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S.

  That is, the focus images P1, P2, and P3 are both in the depth direction of the workpiece S (z-axis direction in FIG. 4) and in the direction orthogonal to the depth direction of the workpiece S (x-axis direction in FIG. 4). Are continuously formed at different positions.

  Further, since the focus image P1 and the focus image P2 are spatially overlapped, and the focus image P2 and the focus image P3 are spatially overlapped, the focus images P1, P2, and P3 are spatially overlapped. A series of focused images are formed. Further, the focus image P2 is formed so as to follow the focus image P1 formed first, and the focus image P3 is formed so as to follow the focus image P2. Therefore, the focus images P1, P2, P3 are It is formed so as to follow in time series from the initially formed focus image P1.

  Here, the energy of the laser beam L1 for forming the focus image P1 is the highest, and the energy of the laser beam L2 for forming the focus image P2 is the next highest, so that the focus image P3 is formed. It is also possible to adjust so that the energy of the laser beam L3 is the lowest. That is, energy can be individually adjusted for each of a plurality of laser beams that are condensed and irradiated for one cycle. This is because the energy efficiency of the occurrence of damage by the laser light that is focused and irradiated differs before and after the occurrence of the damaged or modified region.

  The above principle can be applied to the size of a focused image as well. For example, it can be considered that laser processing with higher efficiency can be performed by adjusting the size of the focus image P1 to be the largest, the size of the focus image P2 to be the next largest, and the size of the focus image P3 to be the smallest. Here, the size of the focus image can be adjusted by changing the aperture of the laser beam for forming the focus image.

  The condensing irradiation position of the laser light L2 does not necessarily overlap the focal image P1, and the condensing irradiation position of the laser light L3 does not necessarily overlap the focal image P2. For example, the laser beam L3 is condensed and irradiated so that the laser beam L3 overlaps the damaged or modified region generated by the focus image P1, and the laser beam L3 overlaps the damaged or modified region generated by the focused image P2. May be.

  Further, the focus images P1, P2, and P3 are not necessarily formed at different positions with respect to the direction orthogonal to the depth direction of the workpiece S. For example, any two focus images of the focus images P1, P2, and P3 may be formed at the same position in the direction orthogonal to the depth direction of the workpiece S. Even in this case, since one focus image is formed at a position protruding with respect to the planned processing line, a certain effect can be expected to improve the processing speed.

  Then, the stage 520 on which the workpiece S is placed is controlled by the computer 600 via the controller 570, and in a direction perpendicular to the depth direction of the workpiece S at a predetermined scanning speed v (the x-axis direction in FIG. 4). ). More specifically, the stage 520 translates by a predetermined distance in a direction orthogonal to the depth direction of the workpiece S when the focus images P1, P2, and P3 are formed (one-cycle condensed irradiation). . Thereby, the focus images P1, P2, and P3 are scanned along the planned processing lines.

  Thus, in the direction of the laser energy that is truly required to cause damage to the workpiece S, that is, in both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S. Along with this, focus images P1, P2, and P3 are formed and scanned. As a result, it is possible to prevent laser energy from being lost due to processing of a portion that is not a processing scheduled line, and to realize highly efficient transmission of laser energy.

  That is, by improving the consumption efficiency (propagation efficiency and machining efficiency) of the limited laser energy with respect to the workpiece S, a portion that is not a desired energy consumption target (for example, a space generated near the damaged site due to ablation). It is possible to reduce the loss of energy due to processing scraps scattered on the surface.

  In the present embodiment, in order to determine the condensing irradiation positions of a plurality of laser beams in the depth direction of the workpiece S, the spread angle of the laser beams when entering the objective lens 500 is determined by telescope optics. Although the adjustment is performed using the lens pair of the system, the present invention is not limited to this. For example, the spread angle of the laser light when entering the objective lens can be adjusted after being reflected by a mirror.

  In the present embodiment, a plurality of laser beams are focused and irradiated at different positions in the depth direction of the workpiece S, but the present invention is not limited to this.

  For example, as shown in FIG. 5, a plurality of laser beams are condensed and irradiated at the same position in the depth direction of the workpiece S and at mutually different positions in the direction orthogonal to the depth direction of the workpiece S. It may be done (tandem irradiation). In FIG. 5, laser beams L1, L2, and L3 are parallel beams having the same spread angle, and are incident on the objective lens 500 at different incident angles. As described above, the size of the focus image is defined by the aperture of the laser beam, the focus image P1 is the smallest, the focus image P2 is the next smallest, and the focus image P3 is the largest.

  In the present embodiment, the number of laser beams continuously focused on the workpiece S has been described as 3, but the present invention is not limited to this. For example, two laser beams or four or more laser beams may be continuously focused on the workpiece S. When four or more laser beams are condensed and irradiated, greater damage can be caused in the depth direction of the workpiece S.

  In the present embodiment, the converging irradiation position of the laser beam in the depth direction of the workpiece S is controlled by changing the spread angle using the lens pair, but the present invention is based on this. It is not limited. For example, even if the spread angle of the laser beam is the same, the focused irradiation position of the laser beam in the depth direction of the workpiece S can be controlled by changing the wavelength of the laser beam.

  Thus, according to the present embodiment, a plurality of laser beams are applied to a plurality of condensing irradiation positions that are different with respect to both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S. Since the light is continuously collected and irradiated, the laser energy can be transmitted to the workpiece S with high efficiency. Thereby, the processing speed to the processing target object S can be improved.

(Embodiment 2)
In this embodiment, the astigmatism of laser light is used to control the focus image formed when the laser light is focused and irradiated so as to have a tetrahedral shape.

  “Astigmatism” is an aberration of a lens system in which an image of an object point outside the optical axis is not connected as a single image point, but forms a pair of linear focal points orthogonal to each other on different focal planes. is there. In an optical system with astigmatism, the focal length of the lens has different values in two orthogonal sections including the optical axis, so the two plane directions orthogonal to the optical axis, that is, the horizontal direction and the vertical direction are the same. Cannot focus on the plane. That is, either the radial line or the concentric line is out of focus with respect to the center of the optical axis.

  The cause of astigmatism is that the amount of aberration that occurs is different because the horizontal and vertical light rays are incident at different angles. Therefore, in order to generate astigmatism remarkably, the spread angle between the light beam in two orthogonal planes including the optical axis, that is, the vertical direction and the horizontal direction of the light beam may be different.

  In the present embodiment, a cylindrical lens is used to generate the astigmatism. A cylindrical lens is a lens in which only one of the two orthogonal directions functions as a lens and the other direction functions only as a window. If a cylindrical lens is used, it is possible to change the magnification only in one direction out of two orthogonal directions. For example, when a light beam having a circular beam shape is focused and imaged by a single concave cylindrical lens, the beam cross-sectional shape can be converted into a linear shape (linear shape).

  FIG. 6 is a block diagram showing an example of the configuration of the laser processing apparatus 700 according to Embodiment 2 of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description of overlapping portions is omitted.

  In FIG. 6, the laser processing apparatus 700 includes astigmatism optical systems 710, 720, and 730.

  The astigmatism optical system 710 uses the astigmatism of the laser beam to generate the laser light source 200 so that the focal image formed when the laser beam L1 is condensed and irradiated has a tetrahedral shape. The adjusted laser beam L1 is adjusted.

  Here, the astigmatism optical system 710 will be described in detail with reference to FIGS. 7 (A) to 7 (C).

  FIG. 7A is a perspective view showing a component of laser light incident on the astigmatism optical system, and FIG. 7B is a plan view showing a component of laser light incident on the astigmatism optical system. FIG. 7C is a diagram showing an example of a tetrahedral focus image formed by the astigmatism optical system. For simplification of description, the traveling direction (optical axis direction) of the laser light L1 is the z-axis as the spatial coordinate axis in FIGS. 7A and 7B, and each other on a plane orthogonal to the z-axis. Two axes orthogonal to each other are defined as an x-axis (horizontal direction) and a y-axis (vertical direction).

  7A and 7B, the astigmatism optical system 710 is configured by a combination of a concave cylindrical lens 711, a convex cylindrical lens 712, and a circular lens 713.

Concave cylindrical lens 711 diverge horizontal component L _h of the laser beam L1 laser light source 200 is generated in the horizontal direction, as it passes through the vertical component L _v.

Convex cylindrical lens 712 reduces the horizontal component L _h of the laser beam L1 from the concave cylindrical lens 711 in the horizontal direction, as it passes through the vertical component L _v.

Circular lens 713, narrow the horizontal component of the laser beam L1 L _h and vertical components L _v from convex cylindrical lens 712, to form a focused image P _h and vertical focus image P _v of the horizontal component. Here, the horizontal component focal image _Ph and the vertical component focal image _Pv are a pair of orthogonal linear focal points formed on different focal planes by astigmatism.

Further, as shown in FIG. 7C, the horizontal component focus image _Ph and the vertical component focus image _Pv that are spatially twisted and orthogonal to each other are caused by the forces acting between these focus images. A tetrahedral focus image P _s 1, which is a virtually formed processing region, is formed.

Here, the lengths of the horizontal component focus image _Ph and the vertical focus image _Pv and the distance between these focus images are adjusted by adjusting parameters such as the focal position, the arrangement distance, and the tilt angle of the cylindrical lens. Can be controlled by Thereby, the shape of the tetrahedron type focus image P _s 1 can be controlled. Therefore, the shape of damage caused to the workpiece S can be controlled within a predetermined range. For example, by increasing the length of the focused image P _h of the horizontal component of the laser beam L1, the scribing groove to occur in the object S, it can be wide V-shape of the. Moreover, by reducing the length of the focused image P _h of the horizontal component of the laser beam L1, the scribing groove to occur in the object S, it can be sharp V-shape of the.

  The astigmatism optical system 720 is configured by a combination of a concave cylindrical lens, a convex cylindrical lens, and a circular lens, similarly to the astigmatism optical system 710 described above, and uses the astigmatism of laser light to perform laser The laser light L2 generated by the laser light source 300 is adjusted so that the focus image formed when the light L2 is condensed and irradiated has a tetrahedral shape. The astigmatism optical system 730 is composed of a combination of a concave cylindrical lens, a convex cylindrical lens, and a circular lens, similar to the astigmatism optical systems 710 and 720, and utilizes the astigmatism of laser light. The laser light L3 generated by the laser light source 400 is adjusted so that the focus image formed when the laser light L3 is condensed and irradiated has a tetrahedral shape.

  Hereinafter, the operation of the laser processing apparatus 700 configured as described above will be described in detail with reference to FIG.

  FIG. 8 is a diagram illustrating an example of occurrence of damage to the workpiece S by the laser processing apparatus 700.

  First, the laser light sources 200, 300, and 400 generate a single pulse laser beam for processing for condensing and irradiating the workpiece S according to a control signal from the computer 600. The laser beams generated by the laser light sources 200, 300, and 400 may be laser beams having different parameters such as wavelength, pulse width, power, or repetition frequency, or the same laser beams having the same parameters. There may be. Here, laser light generated by the laser light source 200 is denoted by L1, laser light generated by the laser light source 300 is denoted by L2, and laser light generated by the laser light source 400 is denoted by L3.

  The astigmatism optical system 710 is formed when the laser beam L1 is condensed and irradiated using the astigmatism of the laser beam, as described with reference to FIGS. 7A to 7C. The laser light L <b> 1 generated by the laser light source 200 is adjusted so that the focused image has a tetrahedral shape. The astigmatism optical system 720 uses the astigmatism of the laser light to generate the laser light source 300 so that the focused image formed when the laser light L2 is condensed and irradiated has a tetrahedral shape. The adjusted laser beam L2 is adjusted. The astigmatism optical system 730 uses the astigmatism of the laser beam to generate the laser light source 400 so that the focal image formed when the laser beam L3 is condensed and irradiated has a tetrahedral shape. The adjusted laser beam L3 is adjusted.

  The pulse energy of the laser light L 1 that has passed through the astigmatism optical system 710 is adjusted by the variable ND filter 220. Similarly, the pulse energy of the laser beam L 2 that has passed through the astigmatism optical system 720 is adjusted by the variable ND filter 320, and the laser beam L 3 that has passed through the astigmatism optical system 730 has its pulse pulse adjusted by the variable ND filter 420. Energy is adjusted.

  The lens pair 230 adjusts the spread angle when the laser light L1 transmitted through the variable ND filter 220 enters the objective lens 500. The lens pair 330 adjusts the spread angle when the laser light L <b> 2 that has passed through the variable ND filter 320 is incident on the objective lens 500. The lens pair 430 adjusts the spread angle when the laser light L3 transmitted through the variable ND filter 420 enters the objective lens 500.

  In this example, the laser beam L1 has a negative spread angle, that is, a laser beam that is incident while the aperture is reduced, the laser beam L2 has a zero spread angle, that is, a parallel beam, and the laser beam L3 is The laser beam is incident while the spreading angle is positive, that is, the aperture is enlarged.

  The mirror 240 reflects the laser light L1 and makes it incident on the objective lens 500. The mirror 340 reflects the laser beam L2 and makes it incident on the objective lens 500. The mirror 440 reflects the laser beam L3 and makes it incident on the objective lens 500.

The objective lens 500 condenses the laser light L1 incident from the mirror 240 and irradiates the surface substantially the same as the surface of the workpiece S, for example. As a result, a tetrahedral focus image P _s 1 is formed at the focused irradiation position of the laser beam L1. At this time, the tetrahedral focus image P _s 1 is preferably formed such that the horizontal component focus image _Ph is substantially flush with the surface of the workpiece S. Thereby, the efficiency of energy transmission of the laser beam L1 in processing can be improved.

The objective lens 500 condenses the laser beam L2 incident from the mirror 340 and irradiates the laser beam L2 on a position overlapping the tetrahedral focus image P _s 1 inside the workpiece S, for example. As a result, a tetrahedral focus image P _s 2 is formed at the focused irradiation position of the laser beam L2.

The objective lens 500 condenses the laser beam L3 incident from the mirror 440 and irradiates the laser beam L3 on a position overlapping the tetrahedral focus image P _s 2 inside the workpiece S, for example. As a result, a tetrahedral focus image P _s 3 is formed at the focused irradiation position of the laser beam L3.

Here, the tetrahedral focus images P _s 1, P _s 2, and P _s 3 are formed so that the linear focal points on the upper side of the workpiece S are orthogonal to the planned processing line of the workpiece S, respectively. It is preferable. In this case, the linear focus on the lower side of the workpiece S is formed along the planned machining line of the workpiece S. Therefore, a V-shaped damage line can be efficiently generated along the planned processing line of the workpiece S by the tetrahedral focus images P _s 1, P _s 2, and P _s 3.

Further, the laser beams L1, L2, and L3 are incident on the objective lens 500 at different spread angles and incident angles, respectively. As a result, the tetrahedral focus images P _s 1, P _s 2, and P _s 3 formed by these laser beams are obtained in the depth direction of the workpiece S (z-axis direction in FIG. 8) and the workpiece S. Are continuously formed at different positions with respect to both the direction perpendicular to the depth direction (the x-axis direction in FIG. 8).

Further, the tetrahedral focus image P _s 1 and the tetrahedral focus image P _s 2 are spatially overlapped, and the tetrahedral focus image P _s 2 and the tetrahedral focus image P _s 3 are spatial. Therefore, the tetrahedral focus images P _s 1, P _s 2, and P _s 3 form a series of spatially overlapping focus images. The focus image P _s 2 is formed so as to follow the focus image P _s 1 formed first, and the focus image P _s 3 is formed so as to follow the focus image P _s 2. The images P _s 1, P _s 2, and P _s 3 are formed so as to follow in time series from the initially formed focus image P _s 1.

Then, the stage 520 on which the workpiece S is placed is controlled by the computer 600 via the controller 570, and in a direction perpendicular to the depth direction of the workpiece S at a predetermined scanning speed v (the x-axis direction in FIG. 8). ). More specifically, the stage 520 is predetermined in a direction orthogonal to the depth direction of the workpiece S when the focus images P _s 1, P _s 2, and P _s 3 are formed (one-cycle focused irradiation). Translate by the distance of. As a result, the tetrahedral focus images P _s 1, P _s 2, and P _s 3 are scanned along the planned processing lines.

Thus, in the direction of the laser energy that is truly required to cause damage to the workpiece S, that is, in both the depth direction of the workpiece S and the direction orthogonal to the depth direction of the workpiece S. Along with this, tetrahedral focus images P _s 1, P _s 2, and P _s 3 are formed and scanned. As a result, it is possible to prevent laser energy from being lost due to processing of a portion that is not a processing scheduled line, and to realize highly efficient transmission of laser energy.

  That is, by improving the consumption efficiency (propagation efficiency and machining efficiency) of the limited laser energy with respect to the workpiece S, a portion that is not a desired energy consumption target (for example, a space generated near the damaged site due to ablation). It is possible to reduce the loss of energy due to processing scraps scattered on the surface.

  In this embodiment, two cylindrical lenses, a concave cylindrical lens and a convex cylindrical lens are used. However, the present invention is not limited to this. For example, in FIG. 7A, only the concave cylindrical lens 711 may be used.

  That is, as described above, the tetrahedral focus image is a processing region virtually formed by a pair of linear focal points orthogonal to each other, and is a pair of lines orthogonal to each other at the laser beam condensing irradiation position. As long as the focal point can be formed, it is not always necessary to use a plurality of lenses in the astigmatism optical system.

  As described above, a plurality of forms are conceivable as a method of forming a focal image of a tetrahedral shape and a method of adjusting the shape of this tetrahedral shape. Either method can be realized by appropriately combining existing optical components, can be easily introduced, and has an advantage of excellent versatility.

  Thus, according to this Embodiment, the focus image for processing the process target S can be controlled to a desired tetrahedral shape. Thereby, it becomes possible to cause damage of a desired shape to the workpiece S. For example, the shape of the damage line generated in the workpiece S can be changed to, for example, a sharp V-shape or a wide V-shape according to the use of the workpiece S after processing.

  As described above in detail, according to each of the above-described embodiments, the processing speed of the processing target S is improved, and the shape of the damage caused to the processing target S is used for the processing target S after processing. Can be controlled according to.

  Hereinafter, more specific embodiments (examples) of the present invention will be described. In addition, this invention is limited to a following example and is not interpreted.

  In the present embodiment, scribing was performed using a laser processing apparatus shown in FIG. 6 by focusing and irradiating a single beam, that is, one tetrahedral focus image on substantially the same surface of the workpiece (single beam scribing). ). Further, by using the same laser processing apparatus, a double beam, that is, two tetrahedron-type focused images, which are different from each other in both the depth direction of the processing object and the direction orthogonal to the depth direction of the processing object. The irradiation position was continuously focused and irradiated for scribing (double beam scribing). And the effect of the laser processing technique of this invention was confirmed by confirming the result of these scribing with an optical microscope.

Each experimental instrument and experimental conditions used in this example are as follows.
<Laser light source> LD excitation pulse oscillation YAG laser device (THG)
<Lens pair> F = -100 / + 200
<Objective lens> NA = 0.4
<Cylindrical lens> + 100 / + 100
<Processing object> Sapphire

Various parameters of the laser beam used in this example are as follows.
<Wavelength> 355 (nm)
<Pulse width> 10 (ns) to 100 (ns)
<Power> 0.3 (W) to 2.0 (W)
<Repetition frequency> 130 (kHz)
<Beam scanning speed> 5 (mm / s) to 50 (mm / s)
<Mirror tilt angle> +/- 1 °

  FIG. 9A is an optical micrograph of the scribing groove formed by single beam scribing as viewed from above, and FIG. 9B is a sectional view of the sapphire substrate cleaved from the scribing groove of FIG. 9A. FIG. 9C is an optical micrograph showing a cross section of the scribing groove of FIG. 9A.

  From FIG. 9A to FIG. 9C, it can be seen that V-shaped damage has occurred in sapphire from the tetrahedral focus image. Further, when the width W1 and the depth D1 of the cross section of the scribing groove were measured, the width W1 was 7 μm and the depth D1 was 23 μm (see FIG. 9C). Thereby, it can be seen that a scribing groove having a somewhat sharp V-shaped cross-sectional shape is generated.

  FIG. 10A is an optical micrograph of a scribing groove formed by double beam scribing as viewed from above. FIG. 10B is a cross-sectional view of a sapphire substrate that is cleaved from the scribing groove of FIG. FIG. 10C is an optical micrograph showing a cross section of the scribing groove in FIG. 10A.

  10A to 10C show that a significantly deeper scribing groove is generated as compared with the case of single beam scribing. Further, when the width W2 and the depth D2 of the cross section of the scribing groove were measured, the width W1 was 8.2 μm and the depth D1 was 49 μm (see FIG. 10C).

  From the above, in double beam scribing, the width of the scribing groove is hardly changed (7 μm → 8.2 μm) and only the depth of the scribing groove is greatly increased (23 μm → 49 μm) compared to single beam scribing. The cross-sectional shape of the scribing groove can be made sharper. A scribing groove having a sharp cross-sectional shape can be said to be a structure suitable for suitable cleaving or singulation.

  INDUSTRIAL APPLICABILITY The laser processing apparatus and laser processing method according to the present invention are effective as a laser processing apparatus and a laser processing method that have the effect of improving the processing speed of a processing target and cause damage to the processing target material. .

The block diagram which shows an example of a structure of the laser processing apparatus which concerns on Embodiment 1 of this invention. (A) The figure which shows an example of the change of the spreading angle of the laser beam by a lens pair, (B) The figure which shows the other example of the change of the spreading angle of the laser beam by a lens pair, (C) The spreading of the laser beam by a lens pair The figure which shows the further another example of the change of an angle (A) The figure which shows an example of reflection of the single pulse laser by a mirror, (B) The figure which shows the other example of reflection of the single pulse laser by a mirror, (C) Still other of the reflection of the single pulse laser by a mirror Figure showing an example The figure which shows an example of generation | occurrence | production of the damage to the workpiece by the laser processing apparatus of FIG. The figure which shows the other example of generation | occurrence | production of the damage to the workpiece by the laser processing apparatus of FIG. The block diagram which shows an example of a structure of the laser processing apparatus which concerns on Embodiment 2 of this invention. (A) Perspective view showing components of laser light incident on astigmatism optical system, (B) Plan view showing components of laser light incident on astigmatism optical system, (C) Formed by astigmatism optical system Of an example of a focused tetrahedral focus image The figure which shows an example of generation | occurrence | production of the damage to the workpiece by the laser processing apparatus of FIG. (A) An optical microscope photograph of a scribing groove formed by single beam scribing as viewed from above, (B) an optical microscope photograph showing a broken section of a sapphire substrate cleaved from the scribing groove of FIG. 9 (A), (C) FIG. An optical micrograph showing a cross section of the scribing groove of (A). (A) Optical micrograph showing a scribing groove by double beam scribing as viewed from above, (B) Optical micrograph showing a cross section of a sapphire substrate cleaved from the scribing groove of FIG. 10 (A), (C) FIG. An optical micrograph showing a cross section of the scribing groove of (A).

Explanation of symbols

100, 700 Laser processing apparatus 200, 300, 400 Laser light source 210, 310, 410 Telescope optical system 220, 320, 420 Variable ND filter 230, 330, 430 Lens pair 231, 331, 431 Concave lens 232, 332, 432 Convex lens 240 340, 440 Mirror 500 Objective lens 510 Protection window plate 520 Stage 530 Measurement light source 540 Beam shaper 550 Half mirror 560 Photo detector 570 Controller 580 Illumination light source 590 CCD camera 600 Computer 610 Monitor 710, 720, 730 Astigmatism aberration optical system 711 concave cylindrical lens 712 convex cylindrical lens 713 circular lens L1, L2, the L3 laser light P1, P2, P3 focus image L _h laser beam Heisei min L _v focused image P _s 1 of the vertical component of the focal image P _v laser beam of the horizontal component of the vertical component P _h laser light of the laser _{light, P} s _2, P s 3 tetrahedral focus image

Claims (12)

First focusing irradiation position determining means for determining the respective focusing irradiation positions of the plurality of laser beams in the depth direction of the workpiece;
Second condensing irradiation position determining means that adjusts incident angles of the plurality of laser lights to determine respective condensing irradiation positions of the plurality of laser lights in a direction orthogonal to the depth direction of the workpiece. When,
Objective lens for continuously condensing and irradiating each of the plurality of laser beams to the plurality of condensing irradiation positions determined by the first condensing irradiation position determining means and the second condensing irradiation position determining means. When,
Scanning means for scanning the focused irradiation positions of the plurality of laser beams in a direction perpendicular to the depth direction of the workpiece,
At least one of the condensing irradiation positions of the plurality of laser beams is different from other condensing irradiation positions with respect to a direction orthogonal to the depth direction of the workpiece.
The laser processing apparatus characterized by the above-mentioned. The first focused irradiation position determining means includes
The optical system is configured by at least one concave lens or convex lens, or a combination thereof, and adjusts the spread angle of each of the plurality of laser beams.
The laser processing apparatus according to claim 1. The second focused irradiation position determining means is
A mirror that adjusts an incident angle of each of the plurality of laser beams to the objective lens;
The laser processing apparatus according to claim 1. Condensing irradiation positions of the plurality of laser beams are different from each other with respect to a direction orthogonal to the depth direction of the workpiece.
The laser processing apparatus according to claim 1. The focused irradiation positions of the plurality of laser beams are different from each other with respect to both the depth direction of the processing object and the direction orthogonal to the depth direction of the processing object.
The laser processing apparatus according to claim 1. The focus images formed when the plurality of laser beams are focused and irradiated form a series of spatially overlapping focus images.
The laser processing apparatus according to claim 1. The direction orthogonal to the depth direction of the workpiece is the same direction as the machining target line of the workpiece.
The laser processing apparatus according to claim 1. Further comprising an astigmatism optical system for adjusting the plurality of laser beams so that the focused images formed when the plurality of laser beams are condensed and irradiated have a tetrahedral shape, respectively.
The laser processing apparatus according to claim 1. The astigmatism optical system is configured by at least one concave cylindrical lens, convex cylindrical lens, or circular lens, or a combination thereof.
The laser processing apparatus according to claim 8. A first focused irradiation position determining step for determining a focused irradiation position of each of the plurality of laser beams in the depth direction of the workpiece;
A second focused irradiation position determining step of adjusting the incident angles of the plurality of laser lights to determine the focused irradiation positions of the plurality of laser lights in a direction orthogonal to the depth direction of the workpiece. When,
Condensation for continuously condensing and irradiating each of the plurality of laser beams to the plurality of condensing irradiation positions determined by the first condensing irradiation position determining step and the second condensing irradiation position determining step. An irradiation step;
A scanning step of scanning the focused irradiation positions of the plurality of laser beams in a direction orthogonal to the depth direction of the workpiece,
At least one of the condensing irradiation positions of the plurality of laser beams is different from other condensing irradiation positions with respect to a direction orthogonal to the depth direction of the workpiece.
The laser processing method characterized by the above-mentioned. Condensing irradiation positions of the plurality of laser beams are different from each other with respect to a direction orthogonal to the depth direction of the workpiece.
The laser processing method according to claim 10. The focused irradiation positions of the plurality of laser beams are different from each other with respect to both the depth direction of the processing object and the direction orthogonal to the depth direction of the processing object.
The laser processing method according to claim 10.