JP2011110591A - Laser machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To condense light to form a reformed region at a position distributed in the depth direction inside a material. <P>SOLUTION: The laser machining device 1 includes: a first irradiation means 24 for irradiating a material 200 with a first laser light L1 for forming a reformed region; a second irradiation means 11 for irradiating the material with a second laser light L2; a condensing means 15 for forming a first condensing point F1 as a condensing point of the first laser light in the inside of the material and a second condensing point F2 as a condensing point of the second laser light at a predetermined position of the material respectively; a focus control means 17, 20, 23 for determining the position of the second condensing point on the basis of the reflected second laser light; and a moving means 28 for moving the material. The condensing means forms the second condensing point at a position determined by the focus control means, forms the first condensing point at a position determined based on the position of the second condensing point, and moves at least the first condensing point to the optical axis direction of the first laser light in accordance with the movement of the material by the moving means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of a laser processing apparatus that performs processing by, for example, forming a condensing point of laser light in a material to cause a change in a structure inside the material.

  As this type of device, a laser beam condensing point is typically formed inside a material such as a silicon substrate or a glass substrate, and a chemical or physical change is caused by heat treatment in a minute volume near the condensing point. A laser cutting device that cuts a material by utilizing a crack generated by the change is known. In such a laser processing apparatus, various ideas have been made to improve the accuracy of the cut surface.

  For example, the configuration disclosed in Patent Document 1 irradiates a resist layer formed on a substrate with laser light with high-frequency superimposition and detects the reflected light, thereby defocusing the recording laser light. By detecting this, it is possible to form a latent image with a fine pattern on the resist layer.

  Further, Patent Document 2 discloses a configuration in which a material is relatively moved so that a locus of a condensing point formed inside the material is formed obliquely in the optical axis direction with respect to the material surface.

JP 2000-33487 A JP 2007-167875 A

  In laser cutting in which a material is cut starting from a modified region to be formed, the modified region is formed along a cut surface perpendicular to the optical axis direction in order to cut the material at a desired cut surface. The material was cut from the quality region.

  However, with only the modified region formed linearly on the cut surface, the cut surface is not sufficiently limited, and cutting may occur in an unintended direction. In particular, when cutting a material having a crystal orientation, when a modified region is formed linearly in the material as in the conventional method, cutting occurs along the crystal orientation starting from the modified region. There is. At this time, if the crystal orientation does not coincide with the cut surface, cutting at an unintended position may occur, and a desired cutting material may not be obtained. For example, in the case of a material having a crystal orientation inclined with respect to an intended cutting plane, a parallelogram cutting material is obtained instead of the originally intended rectangular parallelepiped cutting material.

  In order to avoid such unintentional cutting, for example, a method of enlarging a modified region formed by condensing laser light and limiting the cut surface can be considered. However, if the modified region is enlarged, cracks generated on the cut surface increase, and the flatness and accuracy of the cut surface may deteriorate.

  In addition, it is possible to limit the cut surface by forming a plurality of modified regions at different positions in the optical axis direction. However, according to the conventional laser focusing technology, the accuracy of the focusing position control is not sufficient. There is a possibility of deteriorating the accuracy of the cut surface. This is particularly noticeable when, for example, a material obtained by bonding a plurality of glass substrates is cut. In order to cut such a laminated glass, it is necessary to form a modified region for each glass substrate to be divided. However, as described above, since the restriction of the cut surface along the modified region is not sufficient, cutting occurs at a different cut surface for each glass substrate, and the flatness and surface roughness of the cut surface are deteriorated. Deviation may occur.

  For example, as described in Patent Document 2, it is possible to limit the cut surface by forming the modified region while moving the position in the optical axis direction. However, according to the technique described in Patent Document 2, the focus control of the focusing point of the processing laser for forming the modified region is not sufficient, and the modified region cannot be accurately formed at a desired position. Problems remain. Even when the focus control described in Patent Document 1 is performed, there is a possibility that accurate focus control cannot be performed if irregularities such as structures and scratches are formed on the surface of the material on which the laser beam is incident.

  The present invention has been made in view of, for example, the above-described problems, and provides a laser processing apparatus that can stably and highly accurately form a modified region inside a material while performing appropriate focus control. The issue is to provide.

  In order to solve the above-described problems, a laser processing apparatus of the present invention is a laser processing apparatus for forming a modified region by condensing laser light inside a material, wherein the modified region is formed on the material. A first irradiating means for irradiating a first laser light for forming a second irradiating means for irradiating the material with a second laser light, and a first condensing point of the first laser light inside the material. And forming the modified region by forming one condensing point, and condensing means for forming a second condensing point that is a condensing point of the second laser light at a predetermined position of the material, A focusing control unit that determines a position of the second focusing point based on the second laser beam reflected from the material; and a moving unit that moves the material; The second position is determined based on the focus control of the condensing point. A light spot is formed, the first light collection point is formed at a position determined based on the position of the second light collection point, and at least the first light collection point according to the movement of the material by the moving means Is moved in the optical axis direction of the first laser beam.

It is a block diagram which shows the basic composition of the laser processing apparatus of a present Example. It is a schematic diagram which shows schematically the pattern of the modification area | region formed in material inside. It is a schematic diagram which shows schematically the pattern of the modification area | region formed in material inside. It is a schematic diagram which shows schematically the pattern of the modification area | region formed in material inside. It is a schematic diagram which shows schematically the pattern of the modification area | region formed in material inside. It is a schematic diagram which shows schematically the pattern of the modification area | region formed in material inside. It is a block diagram which shows the structure of the 1st modification of a laser processing apparatus. It is a block diagram which shows the structure of the 2nd modification of a laser processing apparatus.

  An embodiment of a laser processing apparatus of the present invention is a laser processing apparatus for forming a modified region by condensing laser light inside a material, and for forming the modified region in the material A first irradiating means for irradiating the first laser light; a second irradiating means for irradiating the material with the second laser light; and a first condensing point which is a condensing point of the first laser light inside the material. Forming the modified region and forming a second condensing point which is a condensing point of the second laser light at a predetermined position of the material; and the second reflected light A light receiving means for receiving laser light, a focus control means for determining the position of the second condensing point based on the second laser light received by the light receiving means, and a moving means for moving the material. The light collecting means is connected to the focus control means. The second condensing point is formed at a position determined by the moving means, the first condensing point is formed at a position determined based on the position of the second condensing point, and the movement of the material by the moving means is performed. Accordingly, at least the first condensing point is moved in the optical axis direction of the first laser beam.

  According to the embodiment of the laser processing apparatus of the present invention, the material is irradiated with the first laser light for forming the modified region (in other words, for processing) by the first irradiation means, and the second The irradiation unit typically irradiates a second laser beam having a wavelength different from that of the first laser beam.

  The irradiated first laser light and second laser light are condensed by a condensing unit to form a condensing point (that is, a first condensing point and a second condensing point). The first condensing point, which is the condensing point of the first laser light, is typically formed at a predetermined position inside the material in order to form the modified region. The second condensing point, which is the condensing point of the second laser light, is formed so as to form a beam spot of a predetermined size on the material surface in order to perform focus control described later.

  Further, the position of the second condensing point is determined by the focus control performed by the operations of the light receiving unit, the focus control unit, and the condensing unit, in particular, the position of the second laser beam in the optical axis direction. It is formed at the determined position.

  Specifically, the light receiving means receives, for example, a cylindrical lens that deforms the spot shape of the reflected light from the material surface of the second laser light into an ellipse, and the reflected light having the elliptical spot in each split element. And a four-part light receiving element that outputs a current corresponding to the amount of received light. The focus control unit is, for example, a servo mechanism that determines an appropriate focus position based on a current corresponding to the amount of reflected light of the second laser beam output from the four-divided light receiving element of the light receiving unit. The condensing means is formed by the objective lens by focusing the first laser beam and the second laser beam, and moving the objective lens in the optical axis direction of the second laser beam typically. And an actuator for moving the position of the focused point.

  The focus control performed by the operations of the light receiving unit, the focus control unit, and the light collecting unit will be described. First, the second laser light irradiated so as to form a beam spot on the material surface is reflected by the material surface, and the reflected light is received by the quadrant light receiving element via the cylindrical lens. The 4-split light receiving element generates a focus error signal by the astigmatism method based on the amount of reflected light received by each split element. The servo mechanism in the focus control unit adjusts the position where the condensing point is formed by driving the actuator to move the objective lens of the condensing unit in the optical axis direction based on the focus error signal.

  As described above, the position of the second condensing point is appropriately determined by the focus servo control. According to the focus control means of this embodiment, the focus position is determined by the astigmatism method based on the reflected light of the second laser light received by the light receiving means, and the objective lens is moved by the actuator provided in the light collecting means. Focus control is performed by moving it. However, the focus control may be performed by some other method.

  Further, the condensing means preferably moves the first condensing point so that the movement amount of the second condensing point by the focus control described above is also applied to the first condensing point. For example, if the first laser beam and the second laser beam are condensed using the same objective lens, the objective lens is simply moved according to the focus control of the second focal point, The amount of movement of the second condensing point by the focus control can also be applied to the first condensing point. On the other hand, when the first laser beam and the second laser beam are configured to be focused by different focusing means such as an objective lens, the first laser beam is set according to the amount of movement of the second focusing point by focus control. By moving the objective lens that condenses the light, the position of the first condensing point can be appropriately adjusted. With this configuration, the position adjustment of the first condensing point can be performed with the same accuracy as the position adjustment of the second condensing point by focus control.

  The moving means is a moving table or the like on which the material is fixed, and moves the material during irradiation of the first laser beam and the second laser beam. At this time, the modified region is formed intermittently or continuously along the movement of the material inside the material by the first laser light irradiated intermittently or continuously. Therefore, it is possible to form a modified region at a desired position inside the material. The moving means is typically configured to move the material in a plane perpendicular to the optical axis direction of the first laser beam, but it is not necessarily limited to such a configuration. Absent.

  In accordance with the movement of the material by the moving means described above, the condensing means of this embodiment moves at least the first condensing point in the optical axis direction of the first laser light (in other words, the depth direction of the material). For example, the condensing means moves the position of the first condensing point in the optical axis direction of the first laser light by moving the objective lens by the operation of the actuator described above. For this reason, a modified region in which positions are distributed in the depth direction of the material can be formed in accordance with the movement of the material.

  In this way, by forming the modified region having positions distributed in the depth direction, for example, when cutting the material from the modified region, only the direction perpendicular to the optical axis of the first laser beam is used. In addition, since the modified region is distributed also in the optical axis direction of the first laser beam, the cut surface can be more suitably limited. For this reason, the material can be cut with a desired cut surface relatively easily. Further, the material can be cut at a desired cut surface without being affected by the crystal orientation inside the material as described above.

  Further, the position of the second condensing point can be determined with high accuracy by the operation of the focus control means, and the position of the first condensing point is determined based on the position of the second condensing point by the condensing means. It is determined. For this reason, the position of the first condensing point can also be determined with high accuracy, and even when the position is distributed in the depth direction inside the material, the position where the first condensing point is formed is accurately positioned. Adjustment is possible.

  For this reason, for example, the deformation of the material such as warpage is suitably suppressed from causing the position of the first condensing point for forming the modified region to deviate from the desired position. It becomes possible to form the 1st condensing point accurately. As a result, highly accurate laser processing of the material becomes possible.

  One aspect of the embodiment of the laser processing apparatus of the present invention is characterized in that the condensing means includes first condensing means for moving the position of the light receiving means in the optical axis direction of the reflected second laser light, The focus control unit determines the position of the second condensing point based on the reflected light of the second laser beam received by the light receiving unit moved by the first condensing unit.

  According to this aspect, the condensing unit further includes the first condensing unit such as an actuator capable of moving the four-divided light receiving element which is an example of the above-described light receiving unit in the optical axis direction of the reflected light of the second laser light. . As an example of the focus control operation by the astigmatism method using the four-divided light receiving element implemented in the above-described focus control means, the four-part received light of the reflected light deformed to have an elliptical spot by the cylindrical lens. The spot shape in the element is circular when the focus is at an appropriate position, and the amount of light received by each divided element is uniform. On the other hand, when the focus position is closer to or farther than the predetermined position (that is, in the defocus state), the spot shape becomes an ellipse, and a difference occurs in the amount of light received by each divided element. The focus control means detects such a difference in light amount by adding or subtracting the input of the current converted in the light receiving element, and generates a focus error signal. And based on a focus error signal, the 2nd condensing point is moved by moving the objective lens which is a specific example of a condensing means so that the light quantity received in each division | segmentation element may become uniform.

  In this aspect, particularly during the focus control operation, the light receiving means is moved in the optical axis direction of the reflected light of the second laser light by the operation of the first light collecting means. For this reason, the target of the focus servo in the focus control means is changed, and the position of the second condensing point determined by the focus control is also changed according to the position of the light receiving means after the movement. Further, if the focus position is appropriate when the light receiving means is moved, the defocusing state is again caused by the movement of the light receiving means. Therefore, the second state is determined according to the position of the light receiving means after the movement by the focus control means. The position of the condensing point is determined.

  Note that the position of the second condensing point determined by the focus control means after the movement of the light receiving means is typically the movement of the light receiving means by the first light collecting means from the position of the second condensing point before the movement. The amount of movement depends on the amount. Further, the position of the second condensing point is moved by the focus control, so that the position of the first condensing point is also moved. For this reason, it becomes possible to determine the formation position of the 1st condensing point and the 2nd condensing point to a desired position by adjusting the movement amount of the light-receiving means by operation | movement of a 1st condensing means.

  With this configuration, it is possible to form the first light collection point at a desired position inside the material relatively easily. For this reason, it is possible to form the modified region while moving the position in the depth direction according to the movement of the material.

  In another aspect of the laser processing apparatus according to the present invention, the condensing unit includes a second condensing unit that moves the position of the first condensing point relative to the second condensing point. In addition.

  According to this aspect, it is possible to move the position of the first condensing point by fixing the position of the second condensing point at a predetermined position in the material by the operation of the second condensing unit. Specifically, the second condensing unit is, for example, a diver that is provided in the optical axis of the first laser light between the objective lens and the first light source described above and adjusts the angle of the light flux of the first laser light. It comprises a zing lens and an actuator that moves the diverging lens in the optical axis direction of the first laser beam.

  The second condensing unit moves the diverging lens by an actuator, thereby changing the angle of the light beam of the first laser beam entering the objective lens which is a specific example of the above-described condensing unit. For this reason, since the position of the 1st condensing point of the 1st laser beam formed with an objective lens changes according to the light beam angle of the 1st lens which enters into an objective lens, the position of the 1st condensing point is changed. It can be moved.

  At this time, by configuring the diverging lens so as not to be located on the optical path of the second laser light, only the position of the first condensing point is moved without moving the position of the second condensing point of the second laser light. Can be moved, and the position of the first condensing point can be moved relative to the second condensing point.

  As described above, in the configuration in which the first laser beam and the second laser beam are collected by different objective lenses, it is relatively easy to move the objective lens that collects the first laser beam. The relative movement of the second condensing point with respect to the second condensing point can be realized. Needless to say, the first focusing point can be moved relative to the second focusing point by the movement of the first focusing point by the diverging lens and the actuator described above.

  Thus, by adjusting the position of the first condensing point relative to the second condensing point, the first condensing point is maintained while maintaining the position of the second condensing point determined by the focus control. Can be moved in the optical axis direction. For this reason, it becomes possible to form the first focusing point at a desired position inside the material relatively easily, and the modified region can be formed while moving the position in the depth direction according to the movement of the material. Is possible.

  In another aspect of the embodiment of the laser processing apparatus of the present invention, the condensing means is configured such that the first condensing point and the other first light are within a plane orthogonal to the optical axis direction of the first laser light. When the condensing point is formed at the same position, one of the first condensing points is formed at a position different from the other first condensing points in the optical axis direction of the first laser light.

  According to this aspect, the moving means and the collector are arranged so that the modified region is not formed by the other first condensing point in the same region as the one modified region formed by the first condensing point. The operation of the light means is limited. Specifically, when the material moves due to the movement of the moving means, and the relative position of the first light condensing point in the material moves, the modified region is already formed at the first light condensing point. When formed in the region, the position of the first laser beam in the optical axis direction of the first laser beam is moved by the focusing unit. For this reason, in the plane orthogonal to the optical axis direction of the first laser light, another first light condensing is performed in a region where one first light condensing point is formed (in other words, a region where the modification is generated). When a point is to be formed, the condensing means moves the position of the other first condensing point in the optical axis direction of the first laser beam, so that the first condensing point is again in the same region. Suppresses formation.

  For this reason, for example, in laser processing for forming a modified region that is a starting point for cutting a material, when performing a process for forming a cut surface that intersects each other, a modified region (in other words, a first region) The locus of one condensing point) and the modified region on the other cut surface are formed at positions that do not overlap each other in the optical axis direction of the first laser beam.

  For this reason, it can avoid that the modification | denaturation by the heat processing by a 1st laser beam is implemented repeatedly in the same area | region, and the unintended change in a modification | reformation area | region can be avoided. Further, since the modified regions can be formed continuously or intermittently in the planes intersecting each other while avoiding such unintended changes, it is possible to form a complicated modified region pattern.

  In another aspect of the embodiment of the laser processing apparatus of the present invention, the first laser beam and the second laser beam are in positions that do not overlap each other inside the material.

  According to this aspect, the first laser beam and the second laser beam are, for example, the first irradiation means and the second irradiation so that the other laser beam does not enter the region where one laser beam is incident inside the material. Each positional relationship between the means and the light collecting means is set. At this time, typically, the objective lens for condensing the first laser light and the objective lens for condensing the second laser light are arranged in the laser processing apparatus as different configurations. .

  By configuring in this way, it is possible to avoid the existence of a region where the first laser beam and the second laser beam are simultaneously irradiated inside the material. On the other hand, when the first laser beam and the second laser beam are incident on the same region in the material, the temperature rises inside the material due to the respective laser beams, which is an unintended modification. May occur. According to the aspect described above, the incident position of the laser beam is set so that the first laser beam and the second laser beam do not overlap in any region within the material. Unintended modification can be prevented. Therefore, even an apparatus using two laser beams can perform suitable laser processing without being affected by such technical problems.

  In another aspect of the embodiment of the laser processing apparatus of the present invention, the condensing means forms the first condensing point so that the modified region is not included in the optical path of the first laser light.

  According to this aspect, when the light condensing unit forms the first light condensing point, when the modified region is already formed in the material, the light condensing unit forms the first light condensing point for forming the first light condensing point. The first condensing point is formed so that the modified region is not included in the optical path of the laser beam.

  If the first laser beam passes through the region once modified by the formation of the first condensing point inside the material, unexpected further modification in the modified region due to the heat of the first laser beam or the like. Quality can arise. As such further modification, for example, generation of cracks in the material and expansion of the modified region are conceivable, and should be avoided for appropriate laser processing.

According to the above-described configuration, for example, the condensing unit has an objective lens having a relatively small numerical aperture, and the optical path of the first laser light at the time of forming the first condensing point is within a plane perpendicular to the optical axis direction It is adjusted to be relatively narrow. The condensing means may adjust the pattern of the locus of the first condensing point to be formed so that the modified region is not included in the optical path.
By comprising in this way, the technical problem resulting from the further modification | reformation mentioned above can be avoided.

  In another aspect of the embodiment of the laser processing apparatus of the present invention, the condensing means forms the first condensing point so as to form a modified region in a region within 10 μm cube in the material. .

  According to this aspect, the first condensing point of the first laser beam for processing formed in the material has a strength and size so as to form a modified region in a region within approximately 10 μm cube in the material. Is set. By forming such a relatively small modified region inside the material, for example, when cutting the material along the modified region, it is possible to improve the surface roughness and flatness of the cut surface. In addition, even if the modified region is relatively small, the modified region is formed while changing the position in the depth direction along the processing axis of the material as described above, thereby sufficiently limiting the cut surface. Can be cut, so that cutting is not hindered. Further, in the processing for drawing a pattern or the like by the modified region formed inside the material, it becomes possible to draw a more detailed pattern.

  When laser light having a general intensity used for such processing is used, the size of the first focusing point for forming the modified region within 10 μm cube is, for example, about 1 μm cube. It becomes. When forming such a first condensing point, the error in the depth direction remaining after the servo close for focus control is about 10 nanometers. Since the allowable amount of error in processing a material such as a glass substrate is about 1 micrometer, it is sufficiently larger than the remaining error. From this, the accuracy of the servo gain is allowed even if it is not relatively strict, and therefore, even when the servo gain accuracy in the focus control means is relatively low, it is preferable to form the first focusing point. Focus control can be implemented. Note that the servo gain at this time may be reduced by at least one of an electrical method and an optical method.

  In another aspect of the embodiment of the laser processing apparatus of the present invention, the condensing means is located at a position that is within a predetermined range from the material surface in the optical axis direction of the second laser light and is not the material surface. A second focusing point is formed.

  According to this aspect, the second focusing point where the second laser beam is focused is formed at a position on the optical axis of the second laser beam and not within the predetermined range from the material surface. For this reason, the diameter of the beam spot of the second laser beam formed on the surface of the material is larger than that in the case where the second focal point is formed on the surface of the material.

  Such a relatively large beam spot reduces the influence on the focus error signal caused by minute irregularities such as scratches on the material surface and structures, etc., thus suppressing the influence on the focus control. I can do it.

  Note that the range of the position of the second condensing point formed in this aspect is that the above-described focus control can be appropriately performed, and the influence on the focus control due to the unevenness of the material surface can be eliminated as much as possible. The purpose is to indicate a certain range. In focus control, position adjustment by a servo is performed so that the second condensing point is positioned at a predetermined position appropriately determined from within such a range.

  As described above, according to the embodiment of the laser processing apparatus of the present invention, the first irradiation unit, the second irradiation unit, the light collecting unit, the light receiving unit, the focus control unit, and the moving unit are provided. Prepare.

  Therefore, it is possible to provide a laser processing apparatus capable of stably and highly accurately forming a modified region inside a material while performing appropriate focus control.

  Embodiments of the present invention will be described below with reference to the drawings.

(1) Configuration of Laser Processing Apparatus First, a basic configuration of a laser cutting apparatus 1 which is a specific example of the laser processing apparatus of the present invention will be described with reference to FIG. As shown in FIG. 1, the laser cutting apparatus 1 is configured to irradiate a transparent material 200 with a processing laser beam L1 and a focus control laser beam L2.

  As shown in FIG. 1, the laser cutting apparatus 1 mainly includes two optical systems, a processing optical system 3 related to the processing laser light L1 and a focus control optical system 2 related to the focus control laser light L2. A system is provided.

  First, the configuration of each part of the focus control optical system 2 and the configuration of each part arranged in the transmission path of the signal generated in the focus control optical system 2 will be described.

  The focus control optical system 2 includes a focus light source 11 that emits a laser beam L2 for focus control, a beam splitter 12 that is disposed on the optical path of the laser beam L2 for focus control, and focus control that is transmitted through the beam splitter 12. Laser light L2 for focus control irradiated to the transparent material 200 via the quarter-wave plate 13, the dichroic mirror 14, the objective lens 15, and the objective lens 15 disposed on the optical path of the laser beam L2 for use. And a cylindrical lens 16 disposed on the optical path of the reflected light (in other words, return light) and a four-divided light receiving element (PD: Photo Detector) 17.

  The laser beam L2 for focus control is a specific example of the second laser beam of the present invention, and is, for example, a laser beam having a wavelength of about 680 nm on which high frequency superimposition has been performed.

  The focus light source 11 is a specific example of the second irradiation means of the present invention, and includes, for example, a laser diode for generating laser light and an application for applying a high-frequency superimposed pulse to the irradiated laser light. And a laser beam L2 for focus control is emitted.

  The laser beam L2 for focus control emitted from the focus light source 11 passes through the beam splitter 12, the quarter wavelength plate 13, and the dichroic mirror 14 and enters the objective lens 15.

  The beam splitter 12 and the quarter wavelength plate 13 cause the incident focus control laser beam L2 to enter the objective lens 15 and return the focus control laser beam L2 from the transparent material 200 via the objective lens 15. Light is incident on the cylindrical lens 16.

  The dichroic mirror 14 is configured to transmit or reflect incident light according to the wavelength, and transmits incident focus control laser light L2 in the direction of the objective lens 15 and 1 return light through the objective lens 15. / 4 Transmits light toward the wavelength plate 13. Further, as will be described later, the dichroic mirror 14 is disposed on the optical path of the laser beam L2 for focus control and on the optical path of the laser beam L1 for processing. The light L1 is reflected toward the objective lens 15. For this reason, it is preferable that the transmittance of the dichroic mirror 14 is set such that appropriate reflection and transmission are performed according to the wavelengths of the processing laser beam L1 and the focus control laser beam L2.

  The laser light L2 for focus control that has passed through the dichroic mirror 14 is applied to the transparent material 200 through the objective lens 15. As will be described later, the focus control laser light L2 incident on the transparent material 200 forms a condensing point F2 inside the transparent material 200 by focus control.

  On the other hand, the return light of the focus control laser beam L2 reflected on the surface of the transparent material 200 enters the quadrant PD 17 via the dichroic mirror 14, the quarter reflector 13, the beam splitter 12 and the cylindrical lens 16. To do.

  Here, the cylindrical lens 16 is a semi-cylindrical lens which is an example of one component of the light receiving unit in the present embodiment, and appropriately changes the spot shape of the return light of the laser light L2.

  The 4-split PD 17 is an example of one component of the light receiving means in the present embodiment. For example, the light receiving unit is configured by a photodetector divided into four, and the return light is determined from the difference in the amount of light received by each light receiving unit. A light reception signal corresponding to the incident position is generated and input to the calculation unit 20.

  The quadrant PD 17 is configured to be movable in the optical axis direction of the return light by the operation of the actuator 18. The actuator 18 is supplied with a drive current based on the Z-axis target value input to the drive amplifier 19 from the drive amplifier 19 and moves the quadrant PD 17. At this time, since the return light received by the four-divided PD 17 is in a defocused state, the calculation unit 20 moves the objective lens 15 by a drive amplifier 22 and an actuator 23 (to be described later) so as to be in the focus state again.

  Specifically, astigmatism is added to the return light of the laser beam L2 for focus control as it passes through the cylindrical lens 16. For this reason, the spot shape of the return light incident on the quadrant PD 17 is circular when the focus is at an appropriate position, and elliptic when the focus is shifted. The 4-split PD 17 supplies a current corresponding to the amount of return light received by each split PD to the calculator 20.

  The arithmetic unit 20 detects a focus deviation amount based on the return light by adding and subtracting a current based on the light amount received in each divided PD in the four-divided PD 17, and generates a focus error signal indicating the focus deviation amount. For example, the arithmetic unit 20 assumes that the divided PDs in the four-divided PD 17 are A, B, C, and D, respectively, and the current value supplied by the divided PDBs and D from the sum of the current values supplied by the divided PDAs and C. A focus error signal is generated by subtracting the sum of. For example, if the focus is at an appropriate position, the amount of light received by each divided PD, and hence the amount of current supplied from each divided PD, is uniform, and the subtraction result in the focus error signal is zero. On the other hand, when the focus position is closer than the appropriate position, the light amount received by each of the divided PDAs and C is received by each of the divided PDBs and C, for example, by an elliptical beam spot that is long in the AC direction. It becomes larger than the light amount, and the subtraction result in the focus error signal is positive. On the other hand, when the focus position is far from the proper position, for example, the amount of light received in each of the divided PDBs and D is received in each of the divided PDAs and C by an elliptical beam spot that is long in the BD direction. It becomes larger than the amount of light, and the subtraction result in the focus error signal is negative.

  The computing unit 20 supplies the focus error signal generated in this way to the drive amplifier 22. The drive amplifier 22 supplies a drive current for moving the objective lens 15 to the lens actuator 23 so as to move the focus to an appropriate position based on the input focus error signal. The lens actuator 23 moves the objective lens 15 to the optical axis of the laser light L2 for focus control so that the condensing point F2 is formed at a position based on the focus error signal and the Z-axis target value based on the supplied drive current. Move in the direction to perform focus control. As a result, the condensing point F2 of the laser light L2 for focus control is formed at an appropriate focus position.

  Although the focus control optical system 2 for detecting the focus shift amount by the astigmatism method using the cylindrical lens 16 has been described, the present invention is not limited to this example. For example, the spot size method or some other method is used. May be configured to detect the amount of focus shift, and may further include a configuration for that purpose.

  Next, the configuration of the processing optical system 3 of the laser cutting apparatus 1 will be described. The processing optical system 3 is reflected by the processing light source 24 that irradiates the processing laser beam L1, the diverging lens 25 disposed on the optical path of the processing laser beam L1, the dichroic mirror 14, and the dichroic mirror 14. And an objective lens 15 arranged on the optical path of the processed laser beam L1.

  The processing laser beam L1 is a specific example of the position of the first laser beam of the present invention, and is, for example, an ultraviolet laser.

  The processing light source 24 is a specific example of the first irradiation means of the present invention, and includes a laser generator, a concentrating element, a phase modulator, a resonator, and the like (not shown), and a processing laser beam L1. Is irradiated in the direction of the diverging lens 25.

  The laser beam L1 for processing incident on the diverging lens 25 is adjusted in light beam angle and incident on the dichroic mirror 14. The position and aperture ratio of the dichroic mirror 25 are preferably set based on the relative positions of the condensing point F2 and the condensing point F1. For example, when the position of the condensing point F2 is determined so that the laser beam L2 forms a beam spot of a predetermined size on the surface of the transparent material 200, the condensing point F1 is a predetermined depth position inside the transparent material 200. To be formed.

  In addition, in the optical path of the processing laser beam L1, various configurations for adjusting the laser output, the optical axis, the laser shape, and the like in order to form a modified region in the transparent material 200 are disposed. May be.

  As described above, since the transmittance of the dichroic mirror 14 is set so as to reflect the processing laser beam L1, the incident processing laser beam L1 is reflected toward the objective lens 15. The processing laser light L1 incident on the objective lens 15 is focused on the inside of the transparent material 200 to form a condensing point F1.

  As described above, the position of the condensing point F1 in the optical axis direction is the position of the diverging lens 25 set based on the relative value target value and the objective moved by the lens actuator 23 based on the Z axis target value. It is determined by the position of the lens 15. For this reason, the condensing points F1 follow the movement of the condensing point F2 by focus control, and are formed at a distance determined by the relative value target value.

  In the laser cutting device 1, the focus control optical system 2 and the processing optical system 3 are configured on a fixed base (not shown). On the other hand, the transparent material 200 is installed on a table 30 configured to be movable relative to the base.

  The table 30 is configured to be movable by the actuator 28 within a plane (within the XY plane in FIG. 1) perpendicular to the optical axes of the processing laser beam L1 and the focus control laser beam L2. The actuator 28 is supplied with drive current from the drive amplifier 29 based on the XY-axis target value, which is a target value for material movement input to the drive amplifier 29, and moves the table 30. For this reason, the table 30 can move the transparent material 200 in the XY plane.

  Then, the laser cutting device 1 moves the table 30 in the XY plane while switching between irradiation and stop of the processing laser light L1, thereby converting the processing processing laser light L1 into the transparent material 200. Further, for example, the modified region is formed in a desired position inside the transparent material 200 by scanning linearly.

  In the laser processing apparatus 1 of the present embodiment, as described above, the four-divided PD 17 is arranged in the optical axis direction of the return light of the laser light L2 for focus control by the actuator 18 that is supplied with the current by the drive amplifier 19. It is configured to be movable according to the Z-axis target value input to the drive amplifier 19.

  As the quadrant PD 17 moves, an appropriate focus position in the focus control changes. In particular, when the focus is at an appropriate position, the 4-division PD 17 may be in a defocused state. Accordingly, the computing unit 20 generates a focus error signal based on the changed proper focus position, the drive amplifier 22 drives the lens actuator 23 based on the focus error signal, and the objective lens 15 moves to thereby perform focus control. The condensing point F2 of the laser beam L2 for use is moved to an appropriate focus position. Similarly, the condensing point F1 of the processing laser beam L1 also moves in conjunction with the condensing point F2.

  The amount of movement of the condensing point F2 and the condensing point F1 at this time is preferably the amount of movement according to the Z-axis target value input to the drive amplifier 19. For this reason, the condensing point F1 and the condensing point F2 can be formed in a desired position by appropriately setting the Z-axis target value. For this reason, the position of the condensing point F1 in the optical axis direction of the laser beam L1 for processing inside the transparent material 200 can be adjusted with high accuracy, and the light is condensed while enjoying the effect of position adjustment by focus control. The point F1 can be moved with high accuracy in the optical axis direction of the processing laser beam L1.

  By moving the condensing point F1 in the optical axis direction of the laser beam L1 for processing in this way, a modified region is formed in the locus of the condensing point F1 whose position is distributed in the depth direction of the transparent material 200. I can do it. By forming a modified region in which the position is distributed in the depth direction of the transparent material 200, for example, when the material is cut from the modified region, the optical axis of the processing laser beam L1 is orthogonal. Since the modified region is distributed not only in the direction but also in the optical axis direction of the laser beam L1 for processing, the cut surface can be more suitably limited. For this reason, the material can be cut with a desired cut surface relatively easily. Even when the transparent material 200 has a crystal orientation inside, the material can be cut at a desired cut surface. The effect obtained by the condensing points F1 whose positions are distributed in the optical axis direction of the laser beam L1 for processing will be described in detail later.

  As another example of the operation of the laser cutting device 1, the position of the condensing point F1 with respect to the condensing point F2 is changed by appropriately changing the relative value target value after determining the position of the condensing point F2 by focus control. You may change relatively. If comprised in this way, the position of the condensing point F1 can be changed, without changing the position of the condensing point F2, by moving the diverging lens 25 in the optical axis direction of the laser beam L1 for processing. I can do it. Even in such a configuration, it is possible to perform irradiation by moving the condensing point F1 in the optical axis direction of the laser beam L1 for processing while receiving the effect of highly accurate position adjustment by focus control.

  In the laser cutting apparatus 1 of the present embodiment, the condensing point F1 of the processing laser beam L1 is preferably formed with a modified region inside a minute volume of about 10 micrometers cubic inside the transparent material 200. Thus, the beam intensity and the size of the condensing point are set. For example, in order to form such a small modified region, the size of the condensing point F1 is adjusted to about 1 micrometer cube. As described above, according to the minute condensing point F1, it is possible to form a relatively large number of modified regions inside the material 200, and it is possible to obtain a more accurate cross section.

  Further, the movement in the optical axis direction due to the residual error after the focus servo close can also be suppressed to a minute region of about 10 nanometers, for example. In general laser processing on the transparent material 200, an error range of about 1 micrometer is allowed at the position of the modified region to be formed. For example, it is assumed that the servo gain in focus control is set low. However, the modified region can be formed with sufficient accuracy.

  Further, in the laser cutting apparatus 1 of the present embodiment, as shown in FIG. 1, the focusing point F2 of the laser light L2 for focus control is not a surface of the transparent material 200 but a predetermined inside the transparent material 200. A Z-axis target value for focus control is set so as to be formed at the position. For this reason, the beam spot of the laser beam L2 for focus control formed on the surface of the transparent material 200 is larger than that when the condensing point F2 is formed on the surface of the transparent material 200. For this reason, the influence on the focus control due to relatively small irregularities such as scratches and structures formed on the surface of the transparent material 200 can be suppressed.

  The beam spot diameter at this time is determined according to the numerical aperture of the objective lens 15 and the position in the optical axis direction of the condensing point F2 (in other words, the depth inside the transparent material 200). It is preferable to set appropriately so that the influence of surface irregularities can be suppressed.

  As described above, the laser cutting apparatus 1 has the condensing point F1 so as to form a modified region in the XY plane inside the transparent material 200 and at a desired position in the optical axis direction of the processing laser light L1. Can be formed.

(2) Operation of Laser Processing Device Next, effects obtained by the operation of the laser cutting device 1 of the present embodiment will be described with reference to FIGS.

  For example, as shown in FIG. 2A, according to a conventional laser processing apparatus that does not perform the above-described focus control and change of the position of the condensing point F1 in the depth direction of the transparent material 200, The modified region is formed linearly at a position where the position of the processing laser beam on the optical axis (in other words, the position in the depth direction inside the transparent material 200) is constant. Here, FIGS. 2 to 6 are schematic views schematically showing the pattern of the modified region formed inside the transparent material 200. FIG.

  On the other hand, according to the laser cutting apparatus 1 of the present invention, the modified region can be formed while appropriately changing the position in the optical axis direction inside the transparent material 200 as shown in FIG. .

  Further, as shown in FIG. 2C, the modified region can be formed at a desired position in the optical axis direction by performing the focus control even on the transparent material 200 having unevenness on the surface.

  According to the laser cutting apparatus 1 of this embodiment, the position where the condensing point F1 is formed is determined for processing according to the relative movement of the condensing point F1 and the condensing point F2 due to the movement of the material. The modified region can be formed while moving in the optical axis direction of the laser beam L1.

  According to the laser cutting apparatus 1 of the present embodiment as described above, for example, the modified region serving as a starting point for cutting the transparent material 200 at the cutting plane AA ′ shown in FIG. In the formation, the modified region can be formed in a pattern as shown in FIGS. 3B to 3D. Here, FIG. 3B is a schematic diagram showing a pattern of the locus of the modified region when the condensing point F1 is continuously formed so that the locus of the modified region has a wave shape in the cross section AA ′. FIG. Further, FIG. 3C shows the processing while switching the irradiation and stop of the processing laser beam L1 so that the condensing point F1 is intermittently formed so that the locus of the modified region has a wave shape. The locus pattern of the reforming region when performing is shown. FIG. 3D shows a locus pattern of the modified region formed obliquely in the cross section AA ′.

  Thus, in the cross section AA ′, the modified region is formed in the depth direction inside the transparent material 200 by forming the modified region while moving the condensing point F1 in the optical axis direction of the processing laser beam L1. A quality region can be formed, and the cut surface of the transparent material 200 can be suitably limited.

  Further, for example, the modified region has a pattern as shown in FIGS. 3B to 3D even for the transparent material 200 having a crystal orientation inclined with respect to the optical axis direction of the laser beam L1 for processing. By forming the cross section AA ′, it is possible to limit the cut surface particularly in the optical axis direction of the laser beam L1 for processing. For this reason, it becomes possible to suppress suitably the situation which the unintentional cutting | disconnection produces along a crystal orientation.

  Further, in accordance with the movement of the condensing point L1 in the optical axis direction, the cut surface inclined with respect to the optical axis of the processing laser beam L1 by moving the transparent material 200 in a direction perpendicular to the cross section AA ′. Can also be obtained.

  As described above, according to the modified region distributed in the depth direction inside the transparent material 200, for example, a plurality of glasses can be applied to the transparent material 200 such as a laminated glass on which a plurality of glass substrates are bonded. A modified region can be formed on each substrate. FIG. 4 shows a mode of laser processing when the transparent material 200, which is a laminated glass formed by bonding the glasses 200a, 200b, and 200c, is cut from the modified region. It is a schematic diagram. FIG. 4A shows an aspect of laser processing that does not use the configuration in which the positions of the modified regions are distributed in the depth direction of the transparent material 200 described in this embodiment (in other words, the conventional type). (B) illustrates the mode of laser processing according to the laser cutting apparatus 1 of the present embodiment.

  In the conventional laser processing shown in FIG. 4A, the condensing point F1 is formed by bonding a plurality of glasses in order to form a modified region at a certain depth in the transparent material 200. For laminated glass, a modified region is formed only in one glass (for example, glass 200c). For this reason, when attempting to cut the transparent material 200 starting from the modified region formed by applying a force, the modified region is not formed in the glass 200a and the glass 200b, and thus appropriate cutting cannot be performed. . In order to perform appropriate cutting, it is necessary to form a modified region at a position corresponding to the glass 200c in the glass 200a and the glass 200b, and a plurality of laser processings are required.

  Further, in the case where the modified region is formed in each of the glasses thus bonded, the modified region needs to be formed on a desired cut surface in each of the glass 200a, the glass 200b, and the glass 200c. At this time, if a shift occurs in the position of the modified region formed in each glass, the cut surface cannot be suitably limited, even if the laminated glass is cut from the modified region, There is a concern that the accuracy of the cut surface may deteriorate.

  On the other hand, as shown in FIG. 4 (b), by setting the locus pattern of the condensing point F1 so as to form a modified region in which the position is distributed in the depth direction of the transparent material 200, each glass is set. It is possible to form a modified region in the same plane. By performing cutting with the modified region thus formed as a starting point, it is possible to suitably limit the cut surfaces of each glass within the same plane, and it becomes possible to cut the laminated glass with high accuracy. .

  When forming the modified region in which the depth position inside the transparent material 200 is changed in this way, the processing laser beam L1 when forming one modified region is generated inside the transparent material 200. The pattern of the modified region and the laser for processing are not irradiated so that the region where the other modified region is formed and the region where the other modified region in the transparent material 200 is set to be formed are not irradiated. The numerical aperture of the light L1 needs to be set. For example, as shown in FIG. 5A, the laser beam when forming the condensing point F1 at the position P1 in the transparent material 200 is a place where the condensing point F1 different from the position P1 is formed. Alternatively, passing the position P2, which is a place to be formed in the future, causes over-irradiation of the processing laser beam L1 at the position P2. Such over-irradiation may cause unintentional modification of the transparent material 200 at the position P2, leading to technical problems such as inability to perform appropriate processing.

  In order to prevent such a problem, in the laser cutting apparatus 1 of the present embodiment, as shown in FIG. 5B, the condensing point F1 is condensed at a position (for example, P1) in the transparent material 200. In order to prevent the laser beam L1 for processing in the irradiation range from entering a relatively shallow position in the transparent material 200 (in other words, a position closer to the objective lens 15, for example, P2), The numerical aperture of the laser beam L1 for processing is adjusted.

  For this reason, it is possible to preferably avoid unintentional irradiation of the laser beam L1 for processing at a position where the condensing point F1 is formed, and to appropriately prevent further unintended modification.

  Further, as shown in FIG. 6A, in order to obtain a cross section AA ′ and a cross section BB ′ intersecting each other, for example, with respect to the cross section AA ′, the locus of the modified region shown in FIG. A pattern is formed, and the cross section BB ′ can be processed so as to form a pattern of a modified region locus shown in FIG. If comprised in this way, the condensing point F1 of the laser beam L1 for a process will not be formed again with respect to the modified area | region which modification | denaturation generate | occur | produced with the laser beam L1 for a process once. For this reason, some further modification | reformation in a modification area | region by irradiating the laser beam L1 for a process can be suppressed, and it becomes possible to form a suitable modification | reformation area | region.

(3) First Modification Next, the configuration of a first modification of the laser processing apparatus according to the present embodiment will be described with reference to FIG. FIG. 7 is a schematic diagram schematically showing a configuration of a laser cutting apparatus 1 ′ which is a first modification of the laser processing apparatus. In the first modified example, the same components as those described with reference to FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  The first modification of the laser processing apparatus according to the present embodiment is a specific example of the second condensing unit of the present invention, in which a diverging lens 25 disposed on the optical path of the processing laser beam L1 is used as the processing laser. A second lens actuator 26 that moves in the optical axis direction of the light L1 and a drive amplifier 27 that drives the second lens actuator 26 are provided.

  The laser beam L1 for processing incident on the diverging lens 25 is adjusted in the light beam angle by the diverging lens 25 and is incident on the dichroic mirror 14. Particularly in the first modified example, the diverging lens 25 is configured to be movable in the optical axis direction of the processing laser beam L1 by the operation of the second lens actuator 26.

  The drive amplifier 27 supplies a drive current for driving the second lens actuator 26 according to a relative value target value that is input in advance or appropriately during a laser processing operation by the laser processing apparatus. Then, the second lens actuator 26 is supplied with the drive current, and moves the diverging lens 25 to a position corresponding to the relative value target value. As the diverging lens 25 moves, the beam angle of the processing laser beam L1 incident on the dichroic mirror 14 and the objective lens 15 changes, and as a result, the formation position of the condensing point F1 becomes the processing laser beam. It moves in the optical axis direction of L1.

  The relative value target value input to the drive amplifier 27 is intended to include a numerical value indicating the relative position of the condensing point F1 with respect to the condensing point F2, and for example, the condensing point F2 in FIG. 7 is formed. And a value indicating the distance between the desired position where the condensing point F1 is formed. By appropriately setting or changing such a relative value target value, the position of the condensing point F1 with respect to the condensing point F2 is appropriately determined or changed.

  By setting the relative value target value, for example, it is possible to move the first condensing point relative to the second condensing point whose position is determined at one point by focus control. For this reason, it is possible to form the condensing point F1 at a desired position where the modified region in the transparent material 200 is formed while the position of the second condensing point is fixed at a predetermined position determined by the focus control. It becomes.

  In the first modification, a configuration in which the position of the condensing point F1 is moved together with the condensing point F2 by moving the quadrant light receiving element 17 as described above may be employed. According to the present embodiment, the position of the condensing point F1 can be determined or moved relative to the condensing point F2.

(4) Second Modification According to the laser cutting apparatus 1 described above, the focusing optical system 2 and the processing optical system 3 are configured using the same objective lens 15, and a focus control laser is used. The light L2 and the processing laser light L1 have the same optical axis. On the other hand, the focusing optical system 2 and the processing optical system 3 have independent optical systems as in a laser cutting apparatus 1 ″ which is a second modification of the laser processing apparatus shown in FIG. The laser beam L2 for control and the laser beam L1 for processing may have different optical axes.

  According to the laser cutting apparatus 1 '' which is a modified configuration example of the laser processing apparatus of the present invention shown in FIG. 8, in the focusing optical system 2, the focus control laser beam L2 is the objective lens 15 in the basic configuration example. Instead of this, it is condensed inside the transparent material by an additional objective lens 15 '. The objective lens 15 ′ is configured to be movable in the optical axis direction of the laser light L 2 for focus control by the lens actuator 23 in the same manner as the objective lens 15, and the input Z-axis target value and focus error signal are input. The movement is performed based on the above.

  Such a laser cutting device 1 ″ can also enjoy the various effects related to the laser cutting device 1 described above. Further, for example, the influence of heat on the transparent material 200 due to the mutual laser light due to irradiation of the laser beam L2 for focus control and the laser beam L1 for processing on the same optical axis, or for processing It is possible to avoid the influence of the stray light of the laser beam L1 on the focus control.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and a laser accompanying such a change. Processing devices and the like are also included in the technical scope of the present invention.

1 ... Laser cutting device,
2 ... Focus control optical system,
3 ... Processing optical system,
11 ... Focus light source,
12 ... Beam splitter,
13: 1/4 wavelength plate,
14 ... Dichroic mirror,
15 ... Objective lens,
16 ... Cylindrical lens,
17... 4 divided light receiving element (PD: Photo Detector),
18 ... PD actuator,
19, 22, 27, 29 ... drive amplifier,
20 ... an arithmetic unit,
23, 26 ... Lens actuator,
24 ... Processing light source,
25 ... Diverging lens,
28 ... Actuator,
30 ... table,
200 ... transparent material,
L1 ... Laser beam for processing,
L2: Laser light for focus control F1 ... Condensing point of laser light for processing,
F2: Focusing point of laser light for focus control.

Claims (8)

A laser processing apparatus for forming a modified region by condensing laser light inside a material,
A first irradiation means for irradiating a first laser beam for forming the modified region in the material;
A second irradiation means for irradiating the material with a second laser beam;
The modified region is formed by forming a first condensing point that is a condensing point of the first laser light inside the material, and a condensing point of the second laser light at a predetermined position of the material. Condensing means for forming a second condensing point,
A light receiving means for receiving the reflected second laser light;
A focus control means for determining a position of the second condensing point based on the second laser light received by the light receiving means;
A moving means for moving the material,
The condensing unit forms the second condensing point at a position determined by the focus control unit, and forms the first condensing point at a position determined based on the position of the second condensing point. Then, at least the first condensing point is moved in the optical axis direction of the first laser light in accordance with the movement of the material by the moving means. The condensing means includes first condensing means for moving the position of the light receiving means in the optical axis direction of the reflected second laser light,
The focus control means determines the position of the second focusing point based on the reflected light of the second laser light received by the light receiving means moved by the first focusing means. Item 3. The laser processing apparatus according to Item 1 or 2.   The said condensing means is further equipped with the 2nd condensing means which moves the position of the said 1st condensing point relatively with respect to the said 2nd condensing point, The Claim 1 or 2 characterized by the above-mentioned. Laser processing equipment.   In the case where one of the first condensing points and the other first condensing point are formed at the same position in a plane orthogonal to the optical axis direction of the first laser light, The said 1st condensing point is formed in the position different from the said other 1st condensing point in the optical axis direction of the said 1st laser beam, It is any one of Claim 1 to 3 characterized by the above-mentioned. The laser processing apparatus as described.   5. The laser processing apparatus according to claim 1, wherein the first laser beam and the second laser beam are in positions that do not overlap each other inside the material. 6.   The said condensing means forms the said 1st condensing point so that the said modification | reformation area | region may not be included in the optical path of the said 1st laser beam, The any one of Claim 1 to 5 characterized by the above-mentioned. The laser processing apparatus as described.   The said condensing means forms the said 1st condensing point so that a modified area | region may be formed in the area | region within 10 micrometers cube in the said material, The any one of Claim 1 to 5 characterized by the above-mentioned. The laser processing apparatus as described in.   The said condensing means forms the said 2nd condensing point in the position which is in the predetermined range from the said material surface in the optical axis direction of a said 2nd laser beam, and is not the said material surface. The laser processing apparatus according to any one of 1 to 7.

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