JP2014205168A - Laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To focus laser beam on a predetermined position of a work piece with ease and precisely according to thickness of the work piece.SOLUTION: A laser processing apparatus (1) is detachably fitted with a correction ring rotation means (7) which performs aberration correction of an objective lens (51) by rotating a correction ring (52) of the objective lens fitted with the correction ring. The correction ring rotation means includes an engaging and gripping part (73) which moves to an acting position for engaging with the correction ring and a non-acting position for departing from the acting position, and a rotation drive part (76) which rotates the correction ring through the engaging and gripping part according to thickness of a work piece (W). Before starting of laser processing, rotation angle of the correction ring is adjusted under a condition in which the engaging and gripping part is engaged with the correction ring, and during the laser processing, a height position of the objective lens is made to follow surface displacement of the work piece under a condition in which the engaging and gripping part is separated from the correction ring.

Description

  The present invention relates to a laser processing apparatus that processes a workpiece by irradiating the workpiece with a laser beam.

  In the manufacture of a semiconductor device such as an IC or LSI, the surface of a semiconductor substrate as a workpiece is partitioned into a number of rectangular regions by dividing lines arranged in a lattice pattern. A semiconductor device is formed in each rectangular region, and is divided into individual semiconductor devices by dividing the semiconductor substrate along a dividing line. Regarding the division of the semiconductor substrate, a laser beam that irradiates the inside of the semiconductor substrate along the dividing line with a laser beam that is transmissive to the semiconductor substrate to form a modified region that becomes the division starting point inside the semiconductor substrate. A processing apparatus has been proposed (see, for example, Patent Document 1). The semiconductor substrate in which the modified region is formed is divided along the dividing line by using the modified region as a division starting point by applying an external force.

Japanese Patent No. 3408805

  According to the inventor's experience, in the laser processing apparatus described in Patent Document 1, in order to generate a modified region inside the workpiece, a laser beam is precisely applied to a predetermined position in the thickness direction of the workpiece. It is important to collect light. However, an aberration is generated in the laser beam that passes through the atmosphere and passes through the workpiece according to the distance from the upper surface of the workpiece to a predetermined position in the thickness direction, that is, the transmission depth of the laser beam. In this case, since the aberration changes according to the penetration depth of the laser beam, it is difficult to accurately focus the laser beam to an appropriate depth with respect to the workpiece having various thicknesses.

  The present invention has been made in view of the above points, and provides a laser processing apparatus capable of condensing a laser beam at a predetermined position of a workpiece easily and precisely according to the thickness of the workpiece. The purpose is to do.

  The laser processing apparatus of the present invention includes a holding unit that holds a workpiece, a laser beam irradiation unit that irradiates a laser beam having a wavelength that is transmissive to the workpiece held by the holding unit, and a laser beam irradiation unit. An oscillator that oscillates on the workpiece, a condensing unit that condenses the laser beam inside the workpiece, a measuring unit that measures a surface displacement of a laser beam irradiation region of the workpiece, and supports the condensing unit; And a focusing point position adjusting unit that moves the focusing unit in a direction perpendicular to the workpiece based on the measurement result of the measuring unit, the focusing unit being arranged on the outer peripheral surface. And a correction ring rotating means for rotating the correction ring, comprising a correction ring having a plurality of concave and convex portions, and an objective lens in which the lens slides inside to perform aberration correction in accordance with the thickness by rotating the correction ring. prepare for The correction ring rotating means includes at least two engagement gripping portions that engage with the concave-convex portion and grip the correction ring, an action position that engages the engagement gripping portion with the concave-convex portion, and the A moving part that moves to a non-acting position separated from the concavo-convex part, and a rotation that rotates the correcting ring by a predetermined angle by moving the engaging and gripping part by a predetermined angle while the engaging and gripping part is positioned at the operating position. A drive unit, and a storage unit that stores rotation angle information of the correction ring that has an appropriate aberration according to the thickness of the workpiece, and when the thickness of the workpiece is changed, the storage unit The engagement gripping portion is positioned at the working position, and the correction ring is rotated at an appropriate rotation angle according to the thickness of the workpiece by the rotation angle information stored in the storage portion, and is covered by the laser beam irradiation means. When irradiating a workpiece with a laser beam, the engaging gripping part is inactive. Performing the processing while adjusting the focusing point in a state of being positioned in location, characterized by.

  According to this configuration, the engagement gripping portion is engaged with the uneven portion of the correction ring, and the correction ring is automatically adjusted to a rotation angle corresponding to the thickness of the workpiece. Accordingly, even when the workpiece is changed to another workpiece having a different thickness, appropriate aberration correction is performed according to the thickness of the workpiece. When the laser beam is irradiated, the condensing point position of the laser beam follows the surface displacement of the laser beam irradiation area of the workpiece. Thereby, the modified region can be formed at an appropriate depth according to the surface displacement of the workpiece. At this time, the laser beam is irradiated in a state where the engagement gripping part is separated from the uneven part of the correction ring, and therefore the follow-up operation of the light collecting means with respect to the surface displacement of the workpiece is not hindered by the engagement gripping part. .

  According to the present invention, even when the thickness of the workpiece is changed, the laser beam can be easily and accurately processed by automatically rotating the correction ring at a rotation angle corresponding to the thickness of the workpiece. The light can be condensed at a predetermined position.

It is a perspective view of the laser processing apparatus which concerns on this Embodiment. It is a perspective view which shows the attachment state of the correction | amendment ring | wheel rotation means which concerns on this Embodiment. It is a schematic diagram of the condensing means which concerns on this Embodiment. It is operation | movement explanatory drawing of the aberration correction by the correction | amendment ring | wheel rotation means which concerns on this Embodiment. It is a fragmentary sectional view of the correction ring rotation means concerning this embodiment. It is a perspective view of the engagement grip part which concerns on this Embodiment. It is a figure which shows the flow from the preparation before the laser processing which concerns on this Embodiment to laser processing.

  Hereinafter, the schematic configuration of the laser processing apparatus according to the present embodiment will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of the laser processing apparatus according to the present embodiment. FIG. 2 is a perspective view showing an attached state of the correction ring rotating means according to the present embodiment. FIG. 1 shows a state in which the correction ring rotating means 7 is removed from the laser processing apparatus 1. 2A shows a state before the correction ring rotating means 7 is attached, and FIG. 2B shows a state where the correction ring rotating means 7 is attached.

  As shown in FIG. 1, the laser processing apparatus 1 is configured to process the workpiece W by relatively moving a laser beam irradiation means 4 for irradiating a laser beam and a holding means 2 holding the workpiece W. ing. The workpiece W is formed in a substantially disk shape, and the surface is partitioned into a plurality of regions by a grid-like dividing line 81. Various devices are formed in each region partitioned by the dividing line 81. The workpiece W may be a semiconductor wafer in which devices such as IC and LSI are formed on a semiconductor substrate such as silicon and gallium arsenide, or an optical device such as an LED on a ceramic, glass, and sapphire inorganic material substrate. It may be a formed optical device wafer.

  The laser processing apparatus 1 has a rectangular parallelepiped base 11. On the upper surface of the base 11, there is provided a holding means moving mechanism 3 for processing and feeding the holding means 2 in the X-axis direction and indexing and feeding it in the Y-axis direction. A standing wall portion 12 is erected on the rear side of the holding means moving mechanism 3. An arm portion 13 protrudes from the standing wall portion 12, and a laser beam irradiation means 4 is provided on the arm portion 13 so as to face the holding means 2.

  The holding means moving mechanism 3 includes a pair of guide rails 31 arranged on the upper surface of the base 11 and parallel to the Y-axis direction, and a motor-driven Y-axis table 32 slidably installed on the pair of guide rails 31. Have. The holding means moving mechanism 3 includes a pair of guide rails 33 arranged on the upper surface of the Y-axis table 32 and parallel to the X-axis direction, and an X-axis table 34 for driving the motor slidably installed on the pair of guide rails 33. And have. A holding means 2 that holds the workpiece W under the laser beam irradiation means 4 is provided above the X-axis table 34.

  Note that nut portions (not shown) are formed on the back sides of the Y-axis table 32 and the X-axis table 34, and ball screws 35 and 36 are screwed to these nut portions. The holding motor 2 is moved along the guide rails 31 and 33 in the Y-axis direction and the X-axis direction by rotationally driving the drive motors 37 and 38 connected to one end portions of the ball screws 35 and 36.

  The holding means 2 is formed in a disk shape, and is rotatably provided on the upper surface of the X-axis table 34 via the θ table 21. On the upper surface of the holding means 2, a holding surface 22 is formed of a porous ceramic material. The holding surface 22 is connected to a suction source (not shown) through a flow path in the holding means 2, and the workpiece W is sucked and held by the negative pressure generated on the holding surface 22.

  The laser beam application means 4 has a processing head 41 provided at the tip of the arm portion 13. A condensing unit 5 that condenses the laser beam inside the workpiece W is provided below the processing head 41. The condensing means 5 is a so-called objective lens with a correction ring in which a correction ring 52 is provided on the outer surface of the objective lens 51. By rotating the correction ring 52, a lens (not shown) in the objective lens 51 is slid to cause aberration. to correct. By adjusting the rotation angle of the correction ring 52 before the start of laser processing, the aberration of the objective lens 51 is corrected in accordance with the thickness of the workpiece W.

  An oscillator 42 that oscillates a laser beam having a wavelength that is transmissive to the workpiece W is provided inside the arm portion 13. The laser beam oscillated from the oscillator 42 is condensed inside the workpiece W by the condensing means 5. The arm 13 is provided with measuring means 6 so as to be adjacent to the laser beam irradiation means 4 in the processing feed direction (X-axis direction). The measuring means 6 is a non-contact type height sensor, which irradiates the laser beam irradiation region on the surface of the workpiece W with detection light and detects the reflected light from the laser beam irradiation region, thereby detecting the surface of the workpiece W. Measure the displacement.

  Furthermore, a condensing point position adjusting unit 61 is provided in the processing head 41 to cause the condensing point position by the condensing unit 5 to follow the surface displacement of the workpiece W (see FIG. 3). The condensing point position adjusting unit 61 is configured by a piezo element or the like, and condenses by moving the condensing unit 5 in a direction perpendicular to the workpiece W according to the surface displacement of the workpiece W. Adjust the point position. At the time of laser processing after aberration correction, the surface displacement of the laser beam irradiation area on the workpiece W is measured by the measuring means 6, and the focal point position of the laser beam is determined by the focal point position adjusting means 61. Laser processing is carried out while following.

  In the laser processing apparatus 1 configured as described above, the injection port of the processing head 41 is aligned with the dividing line 81 of the workpiece W. Then, the holding means 2 is moved in a state in which the laser beam is irradiated from the processing head 41 to the inside of the workpiece W, so that the modified region 82 (see FIG. 7C) serving as the division start point is along the division line 81. It is formed. The modified region 82 is a region in which the density, refractive index, mechanical strength and other physical characteristics of the workpiece W are different from the surroundings due to the irradiation of the laser beam, and the strength is lower than the surroundings. That means. The modified region 82 is, for example, a melt processing region, a crack region, a dielectric breakdown region, or a refractive index change region, and may be a region where these are mixed.

  2A and 2B, the arm 13 is detachably attached with a correction ring rotating means 7 that automatically rotates the correction ring 52 in accordance with the thickness of the workpiece W. The case 71 of the correction ring rotating means 7 is rectangular and thin when viewed from above, and is notched so as to guide the light collecting means 5 from the attachment surface 711 toward the center when attached to the laser processing apparatus 1. When the case 71 is attached to the laser processing apparatus 1, a C-shaped rotating part 72 in a top view is positioned around the correction ring 52, and three engagement gripping parts 73 (1 in FIG. 2A) provided on the rotating part 72. (Only one is shown) faces the outer peripheral surface of the correction ring 52.

  Before the start of laser processing, each engagement gripping portion 73 moves inward from the rotation portion 72 and operates to engage with the uneven portion 56 on the outer peripheral surface of the correction ring 52. Then, the rotating portion 72 is rotated in a state where each engagement gripping portion 73 is engaged with the correction ring 52, and the rotation angle of the correction ring 52 is automatically adjusted to correct the aberration according to the thickness of the workpiece W. Done. The details of the adjustment method of the rotation angle will be described later. Further, at the time of laser processing, each engagement gripping portion 73 is accommodated in the rotating portion 72 and operates so as to be separated from the uneven portion 56 on the outer peripheral surface of the correction ring 52. Since each engagement gripping portion 73 is separated from the correction ring 52, the following operation of the light collecting unit 5 with respect to the surface displacement of the workpiece W during laser processing is not hindered.

  In this way, by attaching the correction ring rotating means 7 to the laser processing apparatus 1, the workpiece W is changed to another workpiece W having a different thickness without changing the configuration of the existing laser processing apparatus 1. Even in such a case, aberration correction can be automatically performed. The correction ring rotating means 7 may be configured to be detachably attached to the laser processing apparatus 1 and is fixed to the laser processing apparatus 1 by screwing, for example.

  With reference to FIG. 3, the peripheral part of a condensing means is demonstrated. FIG. 3 is a schematic diagram of the light collecting means according to the present embodiment. In FIG. 3, for the sake of convenience of explanation, the correction ring rotating means 7 is simplified except for a part thereof.

  As shown in FIG. 3, in the machining head 41, the mirror 43 and the light condensing means 5 are arranged on the optical path of the laser beam oscillated from the oscillator 42 (see FIG. 1). The mirror 43 reflects the laser beam oscillated from the oscillator 42 toward the condensing unit 5, and the condensing unit 5 condenses the laser beam inside the workpiece W.

  The upper half part of the light condensing means 5 is supported by the light condensing point position adjusting means 61 in the processing head 41, and the lower half part of the light converging means 5 protrudes below the processing head 41. A flange portion 54 is formed in the upper half of the light collecting means 5, and the flange portion 54 is supported by the support portion 44 of the processing head 41 via the light collecting point position adjusting means 61. The condensing point position adjusting means 61 is composed of an actuator such as a piezo element, for example, and expands and contracts in the optical axis direction when a voltage corresponding to the measurement result of the measuring means 6 (see FIG. 1) is applied. Thereby, the condensing means 5 is moved in the direction perpendicular to the workpiece W following the surface displacement of the laser beam irradiation area during laser processing.

  The lower half part of the condensing means 5 is comprised with the objective lens 51 with the correction ring 52, and the cyclic | annular slit board 53 is attached so that attachment or detachment is possible. The slit plate 53 is formed with an initial slit (not shown) for detecting the rotation angle of the correction ring 52 and a scale count slit (not shown). Further, a correction ring rotating means 7 is attached so as to surround the lower half portion of the light collecting means 5, and a photo sensor in which the light emitting element and the light receiving element are opposed to each other with the slit plate 53 sandwiched in the correction ring rotating means 7. 74 is provided. The photo sensor 74 detects the rotation angle of the correction ring 52 by repeatedly transmitting and blocking light through the slit plate 53.

  The correction ring rotation unit 7 includes a control unit 77 that controls the operation of the correction ring rotation unit 7 and a storage unit 78 that stores rotation angle information of the correction ring 52 that has an appropriate aberration according to the thickness of the workpiece W. And are provided. The control unit 77 reads rotation angle information from the storage unit 78 based on the thickness of the workpiece W before the start of laser processing, and drives each unit of the correction ring rotation means 7 based on the rotation angle information to correct the correction ring 52. Adjust the rotation angle. At this time, the rotation angle of the correction ring 52 is fed back from the photosensor 74 to the control unit 77, and the rotation angle of the correction ring 52 is adjusted while the drive motor 761 (see FIG. 4) serving as a drive source is servo-controlled.

  With reference to FIGS. 4 to 6, the detailed configuration of the correction ring rotation unit and the aberration correction by the correction ring rotation unit will be described. FIG. 4 is an explanatory diagram of the aberration correction operation by the correction ring rotating means according to the present embodiment. FIG. 5 is a partial cross-sectional view of the correction ring rotating means. FIG. 6 is a perspective view of the engagement gripping part according to the present embodiment. 4A shows a state before the correction ring 52 is gripped, FIG. 4B shows a state where the correction ring 52 is gripped, and FIG. 4C shows a state where the correction ring 52 is rotated. Further, in FIG. 4, the case 71 is omitted for convenience of explanation. 5A shows a cross section taken along line AA in FIG. 4A, and FIG. 5B shows a cross section taken along line BB in FIG. 4B.

  As shown in FIG. 4, when the correction ring rotating means 7 is attached to the laser processing apparatus 1 (see FIG. 1), a C-shaped rotating portion 72 is positioned around the correction ring 52. The rotating portion 72 is formed with an accommodating portion 721 (see FIG. 5) that slidably accommodates three engagement gripping portions 73 at predetermined angular intervals. As shown in FIG. 6, each engagement gripping portion 73 is formed in a disc shape, and an uneven gripping surface 731 that engages with the unevenness portion 56 of the correction ring 52 is formed on a part of the outer peripheral surface. ing. A cylindrical projection 732 is provided on the upper surface of the engagement gripping portion 73, and a linear convex portion 733 is provided on the lower surface of the engagement gripping portion 73.

  As shown in FIG. 5, the projection 732 is located on the back side of the housing portion 721, and the convex portion 733 extends forward from the back of the housing portion 721. A guide groove 722 that guides the protrusion 732 of the engaging gripping portion 73 is formed on the upper surface of the housing portion 721, and a guide groove 723 that guides the convex portion 733 of the engaging gripping portion 73 on the lower surface of the housing portion 721. Is formed. Returning to FIG. 4, the guide groove 723 extends in the radial direction of the correction ring 52, and the guide groove 722 extends in an oblique direction so as to form a predetermined angle with respect to the guide groove 723. The rotating unit 72 is connected to a moving unit 75 that slides the engagement gripping unit 73 in the radial direction of the correction ring 52. The moving unit 75 is configured to rotate the rotating unit 72 via the link mechanism 753 by expanding and contracting the rod 752 of the air cylinder 751. The reciprocating motion of the rod 752 of the air cylinder 751 applies a rotational force to the rotating portion 72 around the correction ring 52.

  The rotation unit 72 is connected to a rotation drive unit 76 that rotates the three engagement grips 73 together with the rotation unit 72 around the correction ring 52. The rotation drive unit 76 is configured to transmit power from a drive gear 762 fixed to the output shaft of the drive motor 761 to an arcuate driven gear 763 fixed to the rotation unit 72. The rotation drive unit 76 adjusts the rotation angle of the correction ring 52 by integrally rotating the rotation unit 72 and the correction ring 52 while holding the correction ring 52 by the three engagement gripping units 73. The rotation amount of the drive motor 761 at this time is controlled by reading the rotation angle information from the storage unit 78 by the control unit 77 as described above.

  Here, the operation of the correction ring rotating means 7 will be described. As shown in FIG. 4A, in the initial state, the rod 752 of the air cylinder 751 is drawn into the cylinder, and the three engaging grips 73 are positioned at the non-acting positions separated from the concavo-convex part 56 of the correction ring 52. Yes. At this time, as shown in FIG. 5A, each engagement gripping portion 73 is housed in the interior of the housing portion 721 of the rotating portion 72, and the projection portion 732 of the engagement gripping portion 73 and the back of the housing portion 721 The convex portion 733 is engaged with the guide grooves 722 and 723.

  Next, as shown in FIG. 4B, when the rod 752 of the air cylinder 751 is protruded, the rotating portion 72 is rotated by a predetermined angle around the correction ring 52 via the link mechanism 753. When the rotating portion 72 is rotated, the guide groove 722 is moved relative to the protrusion 732 on the upper surface of the engaging gripping portion 73, and the engaging gripping portion 73 is moved along the inner peripheral surface of the guide groove 722. It is pushed toward 52. At this time, as shown in FIG. 5B, the convex portion 733 on the lower surface of the engagement gripping portion 73 is guided by the guide groove 723, and the engagement gripping portion 73 is moved toward the correction ring 52. As a result, the three engaging grips 73 are positioned at the operating positions where they engage with the concave and convex portions 56 of the correction ring 52.

  In the above configuration, the expansion / contraction operation of the rod 752 of the air cylinder 751 is converted into the rotation operation of the rotation unit 72, and the rotation operation of the rotation unit 72 is further converted into the slide operation of the engagement gripping unit 73. In this way, the moving part 75 moves each engagement gripping part 73 to the operating position where it engages with the concavo-convex part 56 of the correction ring 52 and to the non-operating position where it moves away from the concavo-convex part 56.

  As shown in FIG. 4C, when the correction ring 52 is gripped by the three engagement gripping portions 73, the rotation operation of the correction ring 52 is started. In this case, according to the thickness of the workpiece W set in the device data in the laser processing apparatus 1, the rotation angle information of the correction ring 52 that causes an appropriate aberration is read from the storage unit 78 into the control unit 77. Based on this rotation angle information, the drive amount of the drive motor 761 is controlled by each control unit 77. Power is transmitted from the output shaft of the drive motor 761 to the driven gear 763 via the drive gear 762, and the rotating portion 72 fixed to the driven gear 763 is rotated. At this time, the rotating part 72 and the moving part 75 are rotated together with the foundation (not shown).

  Then, the rotating portion 72 rotates integrally with the correction ring 52 while maintaining the state where each engagement gripping portion 73 is engaged with the correction ring 52. At this time, the slit plate 53 (see FIG. 3) is also rotated together with the correction ring 52, and the rotation angle of the correction ring 52 is fed back to the drive motor 761 from the photosensor 74 (see FIG. 3). As a result, the drive amount of the drive motor 761 is accurately adjusted, and the correction ring 52 is adjusted to an appropriate rotation angle corresponding to the thickness of the workpiece W. With such a configuration, the aberration correction of the objective lens 51 is performed according to the thickness of the workpiece W by the rotation of the correction ring 52 before the start of laser processing.

  When the aberration correction is completed, the rod 752 of the air cylinder 751 is drawn into the cylinder, and each engagement gripping portion 73 is moved to the non-operating position separated from the uneven portion 56 of the correction ring 52 (see FIG. 4A). Thereby, the engagement of the correction ring 52 by each engagement gripping portion 73 is released, and laser processing is started.

  Hereinafter, the flow from preparation before laser processing to laser processing will be described with reference to FIG. FIG. 7 is a diagram showing a flow from preparation before laser processing to laser processing according to the present embodiment.

  As shown in FIG. 7A, an objective lens 51 with a slit plate 53 and a correction ring 52 is attached to the laser processing apparatus 1. At this time, it is attached so that the initial position (scale 0) of the objective lens 51 and the initial position (scale 0) of the scale counting slit of the slit plate 53 are matched. Further, the correction ring rotating means 7 is attached to the laser processing apparatus 1 so as to surround the objective lens 51. Thus, since the slit plate 53 and the correction ring rotating means 7 can be retrofitted, the existing laser processing apparatus 1 can be used. When the correction ring rotating means 7 is attached, the engaging grip 73 of the correction ring rotating means 7 is adjusted to the initial position, and the rotation angle of the correction ring 52 is adjusted to the initial angle.

  Next, as shown in FIG. 7B, the rotation angle information of the correction ring 52 is read from the storage unit 78 into the control unit 77 in accordance with the thickness of the workpiece W set in the device data in the laser processing apparatus 1. . Then, each engagement grip 73 is positioned at an operating position where it engages with the correction ring 52, and the correction ring 52 is rotated based on the rotation angle information. Thereby, the rotation angle of the correction ring 52 is adjusted, and the objective lens 51 is aberration-corrected in accordance with the thickness of the workpiece W. At this time, the rotation angle (aberration correction) of the correction ring 52 is accurately adjusted by feeding back the rotation angle of the slit plate 53 by the photosensor 74.

  Next, as shown in FIG. 7C, when the aberration correction is completed, each engagement gripping portion 73 is positioned at a non-acting position separated from the correction ring 52, and the gripping of the correction ring 52 by each engagement gripping portion 73 is performed. Canceled. Then, the surface displacement of the laser beam irradiation area of the workpiece W is measured by the measuring means 6 (see FIG. 1), and laser processing is performed while the focal point position of the laser beam follows the surface displacement of the workpiece W. . At this time, since each engagement gripping portion 73 is separated from the correction ring 52, the height position of the objective lens 51 can be made to follow the surface displacement of the workpiece W. Therefore, the modified region 82 is formed at an appropriate depth according to the surface displacement of the workpiece W.

  As described above, according to the laser processing apparatus 1 according to the present embodiment, the engagement gripping portion 73 engages with the concavo-convex portion 56 of the correction ring 52, and the correction ring 52 corresponds to the thickness of the workpiece W. Automatically adjusted to the rotation angle. Accordingly, even when the workpiece is changed to another workpiece having a different thickness, appropriate aberration correction is performed according to the thickness of the workpiece W. Further, when the laser beam is irradiated, the condensing point position of the laser beam follows the surface displacement of the laser beam irradiation region of the workpiece W. Thereby, the modified region 82 can be formed at an appropriate depth according to the surface displacement of the workpiece W. At this time, the laser beam is irradiated in a state where the engagement gripping portion 73 is separated from the concave and convex portion 56 of the correction ring 52, so that the follow-up operation of the light collecting means 5 with respect to the surface displacement of the workpiece W is performed by the engagement gripping portion 73. There is no hindrance.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the present embodiment, the measuring unit 6 is configured to measure the surface displacement of the workpiece W by irradiating the surface of the workpiece W with detection light, but is not limited to this configuration. The measuring means 6 may have any configuration as long as it measures the surface displacement of the workpiece W.

  Further, in the present embodiment, the condensing point position adjusting unit 61 is configured to move the condensing unit 5 in the vertical direction with respect to the workpiece W by a piezoelectric element, but is not limited to this configuration. The condensing point position adjusting unit 61 may adjust the height position of the condensing unit 5 as long as the height position of the condensing unit 5 can be adjusted, for example, using a voice coil motor.

  In the present embodiment, the correction ring rotating means 7 is configured to grip the correction ring 52 by the three engagement gripping portions 73, but is not limited to this configuration. The correction ring rotating means 7 only needs to have two or more engagement gripping portions 73. For example, the correction ring rotating means 7 may be configured to grip the correction ring 52 by four or more engagement gripping portions 73.

  Further, in the present embodiment, the moving unit 75 is configured to move each engagement gripping portion 73 to the operating position and the non-operating position by the piston operation of the air cylinder 751, but the present invention is not limited to this configuration. The moving part 75 may be configured to move each engagement gripping part 73 between the action position and the non-action position. For example, each movement gripping part 73 is moved by a piston operation of an electric actuator such as an electric cylinder. Also good.

  In the present embodiment, the rotational drive unit 76 transmits power from the drive motor 761 via the drive gear 762 and the driven gear 763. However, the present invention is not limited to this configuration. The rotation drive unit 76 may be configured to move each engagement gripping unit 73 by a predetermined angle to rotate the correction ring 52 by a predetermined angle. For example, a gear train is further provided between the drive gear 762 and the driven gear 763. It may be.

  As described above, the present invention has an effect that a laser beam can be easily and precisely focused on a predetermined position of a workpiece according to the thickness of the workpiece, and in particular, the workpiece. It is useful for a laser processing apparatus for processing a workpiece by irradiating a laser beam onto the workpiece.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Holding means 4 Laser beam irradiation means 5 Condensing means 6 Measuring means 7 Correction ring rotating means 42 Oscillator 51 Objective lens 52 Correction ring 56 Concavity and convexity part 61 Condensing point position adjusting means 72 Rotating part 73 Engagement gripping part 75 Moving unit 76 Rotation drive unit 77 Control unit 78 Storage unit 81 Dividing line 82 Reforming zone W Workpiece

Claims (1)

A holding means for holding the workpiece; a laser beam irradiation means for irradiating a laser beam having a wavelength that is transparent to the workpiece held by the holding means; an oscillator for oscillating the laser beam on the workpiece; Condensing means for condensing the laser beam inside the workpiece, measuring means for measuring the surface displacement of the laser beam irradiation area of the workpiece, and supporting the condensing means and based on the measurement result of the measuring means A condensing point position adjusting means for moving the condensing means in a direction perpendicular to the workpiece, and a laser processing apparatus comprising:
The condensing means includes a correction ring having a plurality of concave and convex portions on the outer peripheral surface, and an objective lens in which the lens slides inside by rotating the correction ring and aberration correction is performed according to the thickness.
A correction ring rotating means for rotating the correction ring;
The correction ring rotating means includes at least two engagement gripping portions that engage with the concave and convex portions to grip the correction ring, an operation position that engages the engagement gripping portions with the concave and convex portions, and the concave and convex portions. A moving portion that moves to a non-operating position that is separated from the rotation position, and a rotation drive portion that rotates the correction ring by a predetermined angle by moving the engaging gripping portion by a predetermined angle while the engaging gripping portion is positioned at the operating position. And a storage unit that stores rotation angle information of the correction ring that has an appropriate aberration according to the thickness of the workpiece,
When the thickness of the workpiece is changed, the engagement gripping portion is positioned at the working position, and an appropriate rotation angle corresponding to the thickness of the workpiece is determined by the rotation angle information stored in the storage portion. The correction ring is rotated,
When the laser beam is irradiated to the workpiece by the laser beam irradiation means, the engagement gripping part is processed while adjusting the position of the condensing point while being positioned at the non-operating position. Processing equipment.

Images