JP2006007619A - Laser machining method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the splitting of a hardly machinable material and the marking of the interior of a transparent object to be machined. <P>SOLUTION: This laser machining device comprises a laser generator 1, condensing point setting means 21 and 43 which set a condensing point at a specified position, in the thickness direction, of the interior of the lat plate-like object 3 to be machined by condensing/entering a laser light from a surface A 31 of the object 3 having two surfaces A/B 31 and 32 positioned back-to-back and condensing point transfer means 41 and 42 which transfer the condensing point set by the condensing point setting means 21 and 43 in parallel with the surface A 31. In addition, the laser machining means splits the object 3 by forming a modification region due to the multiple photon absorption of the laser light in a transfer trajectory of the condensing point by the condensing point transfer means 41 and 42. The object 3 is split by sequentially setting the specified position in the thickness direction, in the surface A 31 direction from a position near a surface B 32 opposite to the surface A 31 by the condensing point setting means 41 and 42, and the interior of the object 3 is marked. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a processing method and a processing apparatus for cleaving or marking a glass plate or the like using multiphoton absorption at a condensing point of laser light.

  Up to now, a processing method for aligning a laser beam condensing point inside a substrate such as a semiconductor and moving the condensing point along a planned cutting line to form a modified region by multiphoton absorption inside the substrate and cleaving it. (For example, see Patent Document 1).

  However, with this conventional cleaving method, it is difficult to cleave a hard and brittle difficult-to-work material with a high yield.

  On the other hand, in order to cause the nonlinear phenomenon of multiphoton absorption, the power density at the focal point must be high, and the laser light has an ultrashort optical pulse with a pulse width (duration) on the order of femtoseconds to picoseconds. Must. However, conventional lasers that generate ultrashort light pulses are lasers having a regenerative amplifier using a titanium sapphire crystal, the laser light wavelength is in the 800 nm band, and the repetition frequency is about 1 kHz. There is a problem that the surface is processed and the processing speed is slow.

  As a method of marking the inside of an object to be processed with a laser, there has been known a processing method in which an absorption layer inside a liquid crystal panel composed of a plurality of transparent layers is absorbed and marked (for example, see Patent Document 2). ).

However, in this conventional marking processing method, since a linear phenomenon called laser light absorption is used, it is impossible to mark the inside of a processing object transparent to the laser light.
JP 2002-192367 A JP 2003-322832 A

  As described above, in the conventional laser cleaving method, it is difficult to cleave a hard and brittle difficult-to-work material with a high yield. In addition, silicon and the like have a problem that the surface is processed and a processing speed is slow.

  In the conventional laser marking processing method, it was not possible to mark the inside of the processing object transparent to the laser beam.

  Therefore, the problem to be solved by the present invention is to make it possible to cleave difficult-to-work materials with a high yield, to prevent the surface from being processed, and to increase the processing speed.

  Another problem to be solved by the present invention is to enable marking inside a transparent workpiece.

  The invention according to claim 1 made to solve the problem is a laser processing method, in which a laser beam is emitted from a laser generator from a surface A of a flat plate-like workpiece having two back surfaces A and B. A condensing point setting step in which light is focused and incident to set a condensing point at a predetermined position in the thickness direction inside the workpiece, and the condensing point set in the condensing point setting step is the A surface And a modified region forming step for forming a modified region by multiphoton absorption of the laser beam on the focal point movement locus by moving in parallel to the focal point movement path, and the predetermined position in the thickness direction of the focal point setting step Are sequentially set in the direction of the A surface from a position close to the B surface opposite to the A surface, the steps are repeated, and the modified region is formed in the thickness direction inside the processing object to form the processing object. It is characterized by cleaving things.

  Since the modified region is sequentially formed in parallel to the A surface from a position close to the B surface opposite to the A surface on which the laser beam is incident, the laser beam is not absorbed or scattered in the formed modified region, and the thickness is increased. The modified region can be effectively formed in the direction. In addition, since a plurality of modified regions are formed in the thickness direction, a difficult-to-work material that is not cleaved only by applying a slight stress can be cleaved regardless of the crystal orientation.

  The invention according to claim 2 is a laser processing method, wherein the laser beam from the laser generator is focused and incident on the inside of the object to be processed from a predetermined direction, so that the condensing point is modified by multiphoton absorption. In the laser processing method of forming a region and cleaving the processing object, the processing object has a flat plate shape having two back surfaces A and B, and the predetermined surface is formed on the A surface of the processing object. The laser beam is focused and incident from the direction to set the focusing point inside the workpiece, and the two focusing points A and B of the workpiece are set within the incident plane of the laser beam. A zigzag modified region is formed by zigzag movement between the surfaces, and the workpiece is cleaved.

  Since the modified region is formed in a zigzag shape between the A and B surfaces, the difficult-to-work material can be cleaved with a high yield by applying a slight stress.

  The invention according to claim 3 is the laser processing method according to claim 2, wherein the zigzag movement is performed from the B surface toward the A surface when the direction of the movement coincides with the predetermined direction. It is characterized by being performed.

  The zigzag movement is performed from the B surface toward the A surface when the direction of the movement coincides with a predetermined direction in which the laser light is focused and incident on the A surface, so that the laser light is absorbed by the formed modified region. Alternatively, the modified region can be efficiently formed in a zigzag shape without being scattered.

  The invention according to claim 4 is the laser processing method according to claim 1, wherein the object to be processed is any one of glass, sapphire, crystal, and silicon.

  The invention according to claim 5 is the laser processing method according to claims 1 to 4, wherein the laser generator has a wavelength of 1 to 2 μm, a pulse width of 10 fs to 20 ps, a repetition frequency of 100 kHz to 10 MHz, The pulse laser is generated.

  A laser beam having a wavelength of 1 to 2 μm and a pulse width of 10 fs to 20 ps is reliably multiphoton absorbed only at a condensing point of an object to be processed such as glass, sapphire, crystal, silicon, etc. A reformed region without any defects is formed. Furthermore, since the repetition frequency is 100 kHz to 10 MHz, it is possible to speed up the focal point movement and increase the processing speed.

  The invention according to claim 6 made to solve the problem is a laser processing method, having at least one plane, from the plane of a workpiece to be processed is any one of glass, sapphire, crystal, and silicon. A focusing point setting step for focusing a laser beam having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz from the laser generator to set a focusing point at a predetermined position inside the workpiece; A modified region forming step of moving the focused point set in the focused point setting step in parallel to the plane and forming a modified region by multiphoton absorption of the laser light on the focused point movement locus; The laser generator includes a fiber laser oscillator doped with at least Er or Yb and a fiber amplifier, and is characterized by marking the inside of the workpiece.

  Since a non-linear phenomenon called multiphoton absorption of laser light is used, it is possible to mark the inside of a workpiece transparent to the laser light.

  The invention according to claim 7, which has been made to solve the problem, is a laser generator and a laser beam from the laser generator A, B A surface of a flat plate-like workpiece having two back surfaces A focusing point setting means for setting the focusing point at a predetermined position in the thickness direction inside the object to be focused, and the focusing point set by the focusing point setting means parallel to the A plane A laser beam processing apparatus for forming a modified region by multiphoton absorption of the laser beam on a movement locus of the light focusing point by the light focusing point moving unit, The condensing point setting means sequentially sets the predetermined position in the thickness direction from the position close to the B surface opposite to the A surface to the A surface direction, sequentially forms the modified region, and cleaves the workpiece. It is characterized by doing.

  In the invention according to claim 8, the laser generator and the laser beam from the laser generator are perpendicular to the A-plane (Z-axis) of a flat plate-like workpiece having two back surfaces A and B. A condensing point setting means for setting a condensing point at a predetermined position in the Z-axis direction inside the processing object by condensing incident from the direction, and the condensing point set by the condensing point setting means A condensing point moving means for moving in a direction perpendicular to the axis, and forming a modified region by multiphoton absorption of the laser light on a moving locus of the condensing point by the condensing point moving means, A laser processing apparatus for cleaving a workpiece, wherein the two focusing points A and B of the workpiece in the laser light incident surface are formed by the focal point setting means and the focal point moving means. It is characterized by zigzag movement between B surfaces.

  The invention according to claim 9 is the laser processing apparatus according to claim 8, wherein the zigzag movement is performed from the B surface toward the A surface when the movement direction coincides with the Z-axis direction. It is characterized by being performed.

  The invention according to claim 10 is the laser processing apparatus according to any one of claims 7 to 9, wherein the object to be processed is any one of glass, sapphire, crystal, and silicon.

  The invention according to claim 11 is the laser processing apparatus according to any one of claims 7 to 10, wherein the laser generator generates a pulse laser having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz. It is characterized by that.

  The invention according to claim 12 is the laser processing apparatus according to claim 11, wherein the laser generator amplifies the output from the fiber laser oscillator that oscillates and outputs the pulse laser, and the fiber laser oscillator. The fiber laser oscillator and the fiber amplifier are doped with at least Er or Yb.

  The invention according to claim 13 made to solve the problem is a laser processing apparatus comprising a fiber laser oscillator and a fiber amplifier doped with at least Er or Yb, having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz. A laser generator that generates a laser beam of 10 MHz, and the laser beam from the laser generator that has at least one plane and is a plane of a workpiece that is one of glass, sapphire, quartz, and silicon A condensing point setting means for setting the condensing point at a predetermined position inside the processing object by condensing the incident light from the workpiece, and the condensing point set by the condensing point setting means is moved parallel to the plane A condensing point moving means for forming a modified region by multiphoton absorption of the laser light on a moving locus of the condensing point by the condensing point moving means, and marking the inside of the workpiece. It is characterized by that.

  Since the modified regions are sequentially formed in parallel to the A surface from a position close to the B surface opposite to the A surface on which the laser light is incident, the thickness direction is such that the laser light is not absorbed or scattered in the formed modified region. Thus, the modified region can be formed effectively. In addition, since a plurality of modified regions are formed in the thickness direction, it is possible to cleave difficult-to-work materials with a high yield by applying a slight stress.

  Since the modified region is formed in a zigzag shape between the A and B surfaces, a difficult-to-work material that is not cleaved only by applying a slight stress can be cleaved with a high yield.

  Laser light having a wavelength of 1 to 2 μm and a pulse width of 10 fs to 20 ps is surely absorbed by multiple photons only at a condensing point of an object to be processed such as glass, sapphire, crystal, silicon, etc. No modified region is formed. Furthermore, since the repetition frequency is 100 kHz to 10 MHz, it is possible to speed up the focal point movement and increase the processing speed.

  Since the laser beam having a pulse width of 10 fs to 20 ps is absorbed by multiphotons only at the condensing point of the processing object, it can be marked inside the processing object transparent to the laser beam.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a laser processing apparatus according to the present invention, FIGS. 2 to 5 are enlarged views of essential parts of FIG. 1 for explaining focusing point setting, and FIGS. 6 to 7 are processes after forming a modified region. FIG. 8 is a perspective view of the object to be processed after forming the modified region.

  The laser processing apparatus includes a laser generator 1 that generates laser light L, a condensing lens 2 that condenses the laser light L at a condensing point p, and the laser light L that is condensed by the condensing lens 2 is Z-axis. The stage 7 on which the workpiece 3 incident from the direction is placed, the X-axis stage 41 for moving the stage 7 in the X-axis direction, and the Y-axis direction perpendicular to the X-axis direction A Y-axis stage 42 for moving the stage 7, a Z-axis stage 43 for moving the mounting table 7 in the Z-axis direction orthogonal to the X-axis and Y-axis directions, the output from the laser generator 1, the pulse width, and the three And a control unit 5 that controls movement of the two stages 41, 42, 43.

  The processing object 3 has a flat plate shape having two back-facing surfaces 31 and 32, A and B, and the laser beam L is condensed and incident from the surface 31 (A). A and B are preferably parallel to each other. In the case of parallel, the condensing point p can be easily set as follows.

  Since the Z-axis direction is a direction perpendicular to the surface 32 (B) of the workpiece 3, the Z-axis direction is the direction of the focal depth of the condenser lens 2 that focuses and enters the laser beam L onto the workpiece 3. Therefore, the condensing point p of the laser light L can be set inside the workpiece 3 by moving the Z-axis stage 43 in the Z-axis direction. Therefore, in the laser processing apparatus of the present embodiment, the Z-axis moving stage 43 serves as a focal point setting unit.

  When the surface 31 (A) and the surface 32 (B) are not parallel, the surface 31 is parallel to the X-axis and Y-axis directions instead of the gonio stage that can rotate the mounting table 7 in the XZ plane. Adjust it. The incident surface of the laser beam L on the surface 31 is in the XZ plane.

  The converging point p is moved in the X (Y) axis direction by moving the workpiece 3 in the X (Y) axis direction by the X (Y) axis stage 41 (42). Therefore, in the present embodiment, the X (Y) axis stage 41 (42) serves as the focal point moving means.

  As the processing object 3, glass, sapphire, crystal, or silicon can be used.

  As the laser generator 1, it is preferable to use a fiber laser doped with Er or Yb that generates laser light having a wavelength of 1 to 2 μm, a pulse width of 10 fs to 20 ps, and a repetition frequency of 100 kHz to 10 MHz. Laser light having a wavelength of 1 to 2 μm and a pulse width of 10 fs to 20 ps is surely absorbed by multiphotons at the condensing point of the processing object such as glass, sapphire, crystal, silicon, etc. A quality region is formed. Furthermore, since the repetition frequency is 100 kHz to 10 MHz, it is possible to speed up the focal point movement and increase the processing speed.

  Next, various aspects of focusing point setting and focusing point movement by the laser processing apparatus of this embodiment will be described.

  FIG. 2 shows a state in which the condensing points p are sequentially set at equal intervals in the direction of the surface 31 (A) (arrow a direction) at a predetermined pitch from a position close to the surface 32 (B). This setting is achieved by moving the workpiece 3 by a predetermined pitch in the Z-axis direction on the Z-axis stage 43 as described above. FIG. 6 shows the modified region 6 formed by moving the set condensing point p, for example, in the X-axis direction every time the condensing point p is set at a predetermined pitch. The movement of the condensing point p in the X-axis direction is achieved by moving the workpiece 3 in the X-axis direction using the X-axis stage 41 as described above. By applying stress in the vicinity of the modified region 6, the workpiece 3 can be cleaved.

  FIG. 3 shows a state in which the condensing points p are sequentially set so that nine points continue in the direction of the surface 31 (A) (the direction of the arrow a) at a predetermined pitch from a position close to the surface 32 (B). FIG. 7 shows the modified region 6 that is formed by moving the focused point p, for example, in the X-axis direction every time the focused point p is set at a predetermined pitch. Since the modified region is continuously formed from the vicinity of the surface 32 to the vicinity of the surface 31, it can be cleaved with a slight stress, and the yield of cleaving is high.

  FIG. 4 shows a modified region 6 formed by moving the condensing point p in a zigzag manner in the laser light incident plane (in the XY plane). This zigzag movement is performed in the direction of arrow a from the surface 32 side to the surface 31 side when the movement direction coincides with the Z-axis direction that is the incident direction of the laser light. The condensing point p is moved in the arrow a direction by moving the workpiece 3 in the Z-axis direction by the Z-axis stage 43. Further, when the moving direction of the zigzag movement does not coincide with the Z-axis direction, the condensing point p is performed in the arrow b direction from the surface 31 side to the surface 32 side. The condensing point p is moved in the arrow b direction by moving the workpiece 3 in the X and Z directions by the Z-axis stage 43 and the X-axis moving stage 41.

  In this embodiment, the focal point is moved in a zigzag manner between the surface 31 and the surface 32, and the modified region is continuously formed from the vicinity of the surface 32 to the vicinity of the surface 31, so that it can be cleaved with a slight stress, The cleaving yield is also high.

  Next, marking by the laser processing apparatus of this embodiment will be described.

  FIG. 5 shows a state where the condensing point p is set at a predetermined position inside the workpiece 3. This setting is performed by moving the workpiece 3 in the Z-axis direction by the Z-axis stage 43. FIG. 8 shows the reformed region 6 of the “A” shape formed by moving the condensing point p parallel to the surface 31, that is, in the XY plane. The condensing point p is moved in the XY plane by being moved in the X and Y directions by the X axis stage 41 and the Y axis stage 42.

  FIG. 9 shows a schematic configuration diagram of the laser processing apparatus according to the first embodiment. The laser processing apparatus according to this embodiment includes a laser generator 1 that generates laser light L, a shutter 8 that controls ON / OFF of the laser light L, a dichroic mirror 9 that transmits the laser light L, and a dichroic mirror 9 that passes through the laser processing apparatus. A condensing lens 2 for condensing the laser beam L, a mounting table 7 on which a workpiece 3 on which the laser light L collected by the condensing lens 2 is incident from the Z-axis direction is mounted, and a mounting table X-axis stage 41 for moving 7 in the X-axis direction, Y-axis stage 42 for moving the mounting table 7 in the Y-axis direction orthogonal to the X-axis direction, and the mounting table 7 in the X-axis and Y-axis directions And a Z-axis stage 43 for moving in the Z-axis direction orthogonal to the control PC 5.

  The laser processing apparatus further includes an observation light source 23 for generating visible light for illuminating and observing the workpiece 3 placed on the mounting table 7 with visible light, and 90 ° of visible light from the observation light source 23. A half mirror 10 that is bent and incident on a dichroic mirror 9, a condenser lens 2, a dichroic mirror 9, and a CCD camera 22 that images the workpiece 3 through the half mirror 10 are provided.

  The laser processing apparatus further includes an optical bench 24 in which a laser generator 1, a shutter 8, a dichroic mirror 9, a condenser lens 2, a half mirror 10, an observation light source 23, and a CCD camera 22 are arranged, and the optical bench 24 in the Z-axis direction. And a drive unit 21 for driving the motor.

  The shutter 8, the observation light source 23, the CCD camera 22, and the drive unit 21 are connected to the control personal computer 5, and the shutter 8 and the observation light source 23 are turned on / off, the imaging data processing of the CCD camera 22, and the drive unit 21. Drive control is performed. Accordingly, the condensing point of the laser beam L, that is, the modified region can be imaged by the CCD camera 22 and observed on the monitor of the control personal computer 5 in accordance with a command from the control personal computer 5.

  The laser generator 1 includes an oscillation module 11, a fiber 13 that propagates the laser light oscillated from the oscillation module 11, an amplification module 12 that amplifies the laser light propagated through the fiber 13, and a laser light from the oscillation module 11. And a laser controller 14 for controlling the output, pulse width, and repetition frequency. The laser controller 14 is connected to the personal computer 5 and operates according to a command from the personal computer 5. The oscillation module 11 receives an Er-doped mode-locked fiber laser, a fiber stretcher that receives a pulsed laser beam oscillated from the fiber laser, and outputs a stretched pulsed laser beam, and a stretched pulsed laser beam. A pulse thinning device that thins out the pulses and an Er-doped fiber preamplifier that receives the amplified and thinned pulse laser light and outputs the amplified pulse laser light. The amplification module 12 receives the pulsed laser light from the oscillation module 11 through the fiber 13 and further amplifies the Er-doped fiber main amplifier, and the compressed light that receives the amplified pulsed laser light and outputs the compressed pulsed laser light. A vessel. The amplification module 12 is fixed to the optical bench 24 so that the laser light L is emitted in the Z-axis direction. Laser light L having a wavelength of 1.55 μm, an average output of 250 mW, a pulse width of 400 to 600 fs, and a repetition frequency of 10 to 200 kHz is emitted from the amplification module 12.

  Processing was carried out using a processing object 3 as a quartz plate having a thickness of 60 μm and a condenser lens 2 as a microscope objective lens having a numerical aperture of 0.5 and a magnification of 50 times.

  First, the shutter 5 is turned on to generate laser light L with an average output of 10 mW from the amplification module 12. Next, while observing the image captured by the CCD camera 22 on the monitor of the personal computer 5, the optical bench 24 is finely moved in the Z-axis direction by the drive unit 21 so that the focal point p is located on the surface of the crystal plate 3. Next, the crystal plate 3 is raised by 34.6 μm on the Z-axis stage 43 so that the focal point p is located at a depth of 50 μm from the surface of the crystal plate 3. Since the refractive index of the quartz plate 3 with respect to light having a wavelength of 1.55 μm is 1.445, the condensing point p is located at a depth of 50 μm (= 34.6 μm × 1.445) from the surface of the quartz plate 3. Next, the shutter 8 is turned off, and laser light L having an average output of 250 mW, a pulse width of 800 fs, and a repetition frequency of 200 kHz is emitted from the amplification module 12. Next, the quartz plate 3 was moved in the X-axis direction at a speed of 20 mm / s by the X-axis stage 41 while turning on the shutter 8 and condensing and irradiating the laser beam L to the condensing point p.

  Next, the condensing point p is set to a depth of 40 μm from the surface of the crystal plate 3 and the crystal plate 3 is moved in the X-axis direction by the X-axis stage 41 while condensing and irradiating the laser beam L to the condensing point p. It was moved at a speed of 20 mm / s.

  Next, the condensing point p is set to a depth of 30 μm from the surface of the crystal plate 3, and the crystal plate 3 is moved in the X-axis direction by the X-axis stage 41 while condensing and irradiating the laser beam L to the condensing point p. It was moved at a speed of 20 mm / s.

  Further, the condensing point p is set to a depth of 20 μm from the surface of the quartz plate 3, and the quartz plate 3 is 20 mm in the X axis direction by the X axis stage 41 while condensing and irradiating the laser beam L to the condensing point p. It was moved at a speed of / s.

  Four condensing points are set from the surface of the quartz plate to the surface side at a pitch of 10 μm sequentially from the depth of 50 μm and moved in the X-axis direction while irradiating the condensing point with the laser beam. When an appropriate impact force was applied around the moving line, the quartz plate could be cut cleanly along the moving line. As a result of observing the section after cleaving, it was confirmed that the modified region induced by the multiphoton absorption was clearly generated on the moving locus of the condensing point.

  In this example, the quartz crystal plate which is the processing target of Example 1 is made sapphire with a thickness of 250 μm, and the condensing points are set from the surface of sapphire to the surface at a pitch of 10 μm sequentially from the depth of 100 μm. The same as Example 1, except that the laser beam is irradiated to the condensing point and moved in the X-axis direction. That is, the laser beam L irradiated to the condensing point has an average output of 250 mW, a pulse width of 800 fs, a repetition frequency of 200 kHz, and the moving speed of sapphire in the X-axis direction is 20 mm / s.

  After 10 focusing points are set from the surface of sapphire to the surface at a pitch of 10 μm sequentially from the surface of sapphire and moved 10 times while irradiating the focusing point with laser light When a suitable impact force was applied around the moving line of the condensing point, sapphire could be cleaved cleanly along the moving line. As a result of observing the cleaved cross section, the modified region induced by multiphoton absorption is clearly generated on the moving locus of the condensing point, and the modified region is continuous in the thickness direction (Z-axis direction). I was able to confirm that.

  In Example 2, the condensing point is set from the depth of 100 μm from the surface of sapphire to 5 points sequentially toward the surface at a pitch of 20 μm, and the laser beam is irradiated in the condensing point except moving in the X-axis direction. The same as in the second embodiment.

  After five focusing points are set from the surface of sapphire to the surface with a depth of 100 μm from the surface of sapphire toward the surface at a pitch of 20 μm, and moving in the X axis direction while irradiating the condensing point with laser light five times When a suitable impact force was applied around the moving line of the condensing point, sapphire could be cleaved cleanly along the moving line. As a result of observing the cleaved cross section, the modified region induced by multiphoton absorption is clearly generated on the moving locus of the condensing point, and the modified region is separated by 10 μm in the thickness direction (Z-axis direction). It was confirmed that it was formed.

  In this example, the quartz crystal plate, which is the object to be processed in Example 1, is a silicon wafer having a thickness of 50 μm, and the condensing points are sequentially set from the surface of the silicon wafer to the surface at a pitch of 10 μm from the depth of 40 μm. Thus, the second embodiment is the same as the first embodiment except that it moves in the X-axis direction while irradiating the condensing point with the laser beam.

  Four focusing points were set from the surface of the silicon wafer to the surface at a pitch of 10 μm sequentially from the surface of the silicon wafer at a pitch of 10 μm, and moving in the X-axis direction was performed four times while irradiating the focusing point with laser light. Later, when an appropriate impact force was applied around the moving line of the condensing point, the silicon wafer could be cleaved cleanly along the moving line. As a result of observing the section after cleaving, it was confirmed that the modified region induced by the multiphoton absorption was clearly generated on the moving locus of the condensing point.

  In this embodiment, the 60 μm-thick quartz crystal plate, which is the object to be processed in the first embodiment, is changed to a 16 μm-thick quartz plate, the focusing point is set at a depth of 10 μm from the surface of the quartz, Is the same as that of Example 1 except that the light is moved in the X-axis direction while irradiating the condensing point.

  After moving in the X-axis direction while irradiating the condensing point with laser light, an appropriate impact force was applied to the periphery of the moving line at the condensing point, and the crystal was successfully cut along the moving line. As a result of observing the cross section after cleaving, it was confirmed that the modified region induced by multiphoton absorption was clearly generated on the moving locus of the condensing point.

  In this example, the crystal plate which is the processing target of Example 1 is a plate glass (BK7) having a thickness of 100 μm, and the condensing points are sequentially directed from the surface of the plate glass to the surface at a pitch of 10 μm from the depth of 90 μm. This is the same as in Example 1 except that the laser beam is set and moved in the X-axis direction while irradiating the condensing point.

  After nine focusing points are set from the surface of the plate glass to the surface at a pitch of 10 μm sequentially from the depth of 90 μm, and 9 times moving in the X-axis direction while irradiating the focusing point with laser light When an appropriate impact force was applied around the moving line of the condensing point, the plate glass could be cut cleanly along the moving line. As a result of observing the section after cleaving, it was confirmed that the modified region induced by the multiphoton absorption was clearly generated on the moving locus of the condensing point.

  In this example, the crystal plate, which is the object to be processed in Example 1, is a plate glass for plasma display (PD200 manufactured by Asahi Glass) with a thickness of 5 mm, and the focal point is set at a position 8 μm deep from the surface of the plate glass. Thus, the second embodiment is the same as the first embodiment except that it moves in the X-axis direction while irradiating the condensing point with the laser beam.

  After moving in the X-axis direction while irradiating the condensing point with the laser beam, the moving line of the condensing point is illuminated with the observation light source 23 and observed with the CCD camera 22, and the modified region due to multiphoton absorption is not processed. It was clearly confirmed through the glass layer. That is, it was possible to mark the inside of the plate glass. It was also found that the contrast was visible when image data of the CCD camera 22 was processed by the personal computer 5.

It is a schematic block diagram of the laser processing apparatus of the best form for implementing this invention. It is a principal part enlarged view of FIG. 1 for demonstrating that a condensing point is set in the inside of a workpiece in a predetermined pitch. It is a principal part enlarged view of FIG. 1 for demonstrating setting a condensing point continuously in the inside of a workpiece. FIG. 2 is an enlarged view of a main part of FIG. 1 for explaining that a condensing point is moved in a zigzag manner within a laser light incident plane (in an XY plane) to form a zigzag modified region. It is a principal part enlarged view of FIG. 1 for demonstrating setting a condensing point inside a workpiece. FIG. 4 is a cross-sectional view of an object to be processed showing a modified region formed by moving in the X-axis direction every time a condensing point set in FIG. 3 is set. FIG. 5 is a cross-sectional view of an object to be processed showing a modified region formed by moving in the X-axis direction every time the condensing point set in FIG. 4 is set. FIG. 6 is a perspective view of an object to be processed showing a modified region formed by moving the condensing point set in FIG. 5 in the X-axis direction and the Y-axis direction. It is a schematic block diagram of the laser processing apparatus of Example 1. FIG.

Explanation of symbols

1... Laser generator 3. .... B surfaces 21 and 43 of the object to be processed, ... condensing point setting means 41, 42 ... .. condensing point moving means

Claims (13)

A, B A laser beam from a laser generator is focused and incident from the A surface of a flat plate-like workpiece having two opposite surfaces, and a focusing point is set at a predetermined position in the thickness direction inside the workpiece. A focusing point setting step to be set;
A modified region forming step of forming a modified region by multi-photon absorption of the laser beam on the focal point movement locus by moving the focal point set in the focal point setting step in parallel with the A plane. When,
And sequentially setting the predetermined position in the thickness direction of the focusing point setting step from the position close to the B surface opposite to the A surface in the A surface direction, and repeating the steps. A laser processing method, wherein the modified region is formed in an internal thickness direction to cleave the processing object. In the laser processing method of cleaving the processing object by forming a modified region by multiphoton absorption at the condensing point by condensing and entering the laser beam from the laser generator into the processing object from a predetermined direction,
The object to be processed has a flat plate shape having two facing surfaces A and B, and the laser beam is focused and incident on the A surface of the object to be processed from the predetermined direction. The focusing point is set on the laser beam, and the focusing point is zigzag moved between the two A and B surfaces of the workpiece within the laser light incident surface to form a zigzag modified region, A laser processing method comprising cutting a workpiece.   3. The laser processing method according to claim 2, wherein the zigzag movement is performed from the B surface toward the A surface when the direction of the movement coincides with the predetermined direction.   The laser processing method according to claim 1, wherein the object to be processed is any one of glass, sapphire, crystal, and silicon.   5. The laser processing method according to claim 1, wherein the laser generator generates a pulse laser having a wavelength of 1 to 2 [mu] m, a pulse width of 10 fs to 20 ps, and a repetition frequency of 100 kHz to 10 MHz. A laser beam having at least one plane and having a pulse width of 10 fs to 20 ps from a laser generator and a repetition frequency of 100 kHz to 10 MHz is collected from the plane of the workpiece, which is one of glass, sapphire, crystal, and silicon. A condensing point setting step for setting the condensing point at a predetermined position inside the workpiece by making light incident; and
A modified region forming step of moving the focused point set in the focused point setting step in parallel with the plane to form a modified region by multiphoton absorption of the laser light on the focused point movement locus;
The laser generator comprises a fiber laser oscillator and a fiber amplifier doped with at least Er or Yb, and marking the inside of the workpiece. A laser generator;
The laser beam from the laser generator is focused and incident from a surface A of a flat plate-like workpiece having two back surfaces A and B, and focused at a predetermined position in the thickness direction inside the workpiece. Focusing point setting means for setting
A condensing point moving means for moving the condensing point set by the condensing point setting means in parallel with the A plane;
And a laser processing apparatus for forming a modified region by multiphoton absorption of the laser light on the movement locus of the condensing point by the condensing point moving means, wherein the condensing point setting means performs the thickness direction A laser processing apparatus, wherein a predetermined position is sequentially set in a direction of the A surface from a position close to the B surface opposite to the A surface, the modified regions are sequentially formed, and the processing object is cleaved. A laser generator;
The laser light from the laser generator is focused and incident from the perpendicular (Z-axis) direction to the A surface of a flat plate-like workpiece having two back faces A and B, and the inside of the workpiece is A focusing point setting means for setting a focusing point at a predetermined position in the Z-axis direction;
A condensing point moving means for moving the condensing point set by the condensing point setting means in a direction perpendicular to the Z axis;
A laser processing apparatus that forms a modified region by multiphoton absorption of the laser light on the movement locus of the condensing point by the condensing point moving means, and cleaves the workpiece. A laser processing apparatus characterized in that the condensing point is zigzag moved between the two A and B surfaces of the object to be processed within the incident surface of the laser beam by the light point setting means and the condensing point moving means. .   The laser processing apparatus according to claim 8, wherein the zigzag movement is performed from the B surface toward the A surface when the direction of the movement coincides with the Z-axis direction.   The laser processing apparatus according to claim 7, wherein the object to be processed is any one of glass, sapphire, crystal, and silicon.   11. The laser processing apparatus according to claim 7, wherein the laser generator generates a pulse laser having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz.   The laser generator includes a fiber laser oscillator that oscillates and outputs the pulse laser and a fiber amplifier that amplifies the output from the fiber laser oscillator, and the fiber laser oscillator and the fiber amplifier are doped with at least Er or Yb. The laser processing apparatus according to claim 11, wherein: A laser generator including a fiber laser oscillator and a fiber amplifier doped with at least Er or Yb, and generating a laser beam having a pulse width of 10 fs to 20 ps and a repetition frequency of 100 kHz to 10 MHz;
The laser beam from the laser generator has at least one plane and is focused and incident from the plane of the workpiece, which is one of glass, sapphire, crystal, and silicon, to be inside the workpiece. Condensing point setting means for setting the condensing point at a predetermined position;
Condensing point moving means for moving the condensing point set by the condensing point setting means parallel to the plane;
And forming a modified region by multiphoton absorption of the laser beam on the movement locus of the condensing point by the condensing point moving means and marking the inside of the workpiece apparatus.

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