JP2013132651A - Laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus which can appropriately perform aberration correction even when machining positions which are different in the depth direction in the interior of an object to be machined.SOLUTION: The laser beam machining apparatus 1 of one embodiment includes: a light source 20; a plurality of intensity converting lenses 11 which convert the intensity distribution of a laser beam from the light source to reshape the intensity distribution into a desired intensity distribution, and which each generate the wave surfaces different from each other; a condensing lens 50 for condensing the laser beams from the intensity converting lenses 11 in a machining position in the interior of the object 100 to be machined; and a control section 80 for changing over the plurality of the intensity converting lenses 11 when changing the machining position.

Description

  The present invention relates to a laser processing apparatus and a laser processing method for processing inside a workpiece.

  In general, laser light often has an intensity distribution that is strongest near the center and gradually weakens toward the periphery, such as a Gaussian distribution. However, in laser processing or the like, a laser beam having a spatially uniform intensity distribution is desired. In this regard, Patent Document 1 discloses that the intensity distribution of laser light is made uniform using a homogenizer. The laser processing apparatus disclosed in Patent Document 1 processes (modifies) the inside of a wafer, and in order to shorten the processing time when processing a wafer having a wide thickness, the laser beam is inclined in the thickness direction. Condensed linearly.

JP 2009-172633 A

  By the way, when condensing a laser beam inside the object to be processed, aberration (wavefront distortion) occurs, and the condensing region is expanded. Since the laser processing apparatus disclosed in Patent Document 1 does not consider the aberration generated inside the processing target, the processing trace extends in the processing depth direction, and there is a possibility that an unexpected crack may occur. Moreover, when forming a process trace to the back surface vicinity, there exists a possibility of penetrating to the back surface.

  Furthermore, the aberration generated inside the processing object varies depending on the position in the depth direction inside the processing object.

  Accordingly, an object of the present invention is to provide a laser processing apparatus and a laser processing method capable of appropriately performing aberration correction even when processing different positions in the depth direction inside a processing target.

  As a result of intensive studies, the inventors of the present application can correct aberrations occurring inside the workpiece by using the wavefront change caused by the intensity conversion lens for making the intensity distribution of the laser light uniform. I found it possible. In addition, as a result of intensive studies, the inventors of the present application have found that the aberration generated inside the object to be processed is obtained by giving the phase correction lens a wavefront change in the homogenizer composed of the intensity conversion lens and the phase correction lens. It was found that it is possible to correct.

  Therefore, the laser processing apparatus of the present invention is a laser processing apparatus that condenses laser light inside a workpiece having optical transparency, and includes (a) a light source that generates laser light, and (b) a light source from the light source. A light shaping unit that converts the intensity distribution of the laser light into a desired intensity distribution, (c) a condensing lens that condenses the laser light from the light shaping unit at a processing position inside the object to be processed; And a control unit for controlling the light shaping unit. The light shaping unit (b1) is an intensity conversion lens that converts the intensity distribution of the laser light from the light source into a desired intensity distribution, and a plurality of intensity conversion lenses that generate different wavefronts, or (B2) An intensity conversion lens that converts the intensity distribution of the laser light from the light source into a desired intensity distribution, and a phase correction lens that corrects the phase of the emitted laser light from the intensity conversion lens, which are different from each other. The control unit has a plurality of phase correction lenses for generating a wavefront, and (d1) switches a plurality of intensity conversion lenses or a plurality of phase correction lenses when changing the processing position.

  The laser processing method of the present invention includes (a) a light source that generates laser light, (b) a light shaping unit that converts the intensity distribution of the laser light from the light source and shapes the laser light into a desired intensity distribution, and (c) ) A laser processing method of a laser processing apparatus including a condensing lens that condenses laser light from a light shaping unit at a processing position inside a processing target. Here, the light shaping unit (b1) is an intensity conversion lens that converts the intensity distribution of the laser light from the light source and shapes the laser light into a desired intensity distribution, and a plurality of intensity conversion lenses that generate different wavefronts, or (B2) an intensity conversion lens that converts the intensity distribution of the laser light from the light source and shapes it into a desired intensity distribution, and a phase correction lens that corrects the phase of the emitted laser light from the intensity conversion lens, A plurality of phase correction lenses each generating a different wavefront. In this laser processing method, (e1) a processing position within the processing object is set or changed, and (e2) a plurality of intensity conversion lenses or a plurality of phase correction lenses are switched in accordance with the setting or change of the processing position. e3) The laser beam from the light source is irradiated to the processing position on the processing object.

  According to this laser processing apparatus and laser processing method, for example, when the light shaping unit has a plurality of intensity conversion lenses, the plurality of intensity conversion lenses generate different correction wavefronts, and the control unit responds to the change of the processing position. Therefore, even if the processing position (processing depth) is changed, appropriate aberration correction can be performed. In addition, for example, when the light shaping unit includes an intensity conversion lens and a plurality of phase correction lenses, the plurality of phase correction lenses generate different correction wavefronts, and the control unit performs a plurality of phase corrections according to changes in the processing position. Since the lenses are switched, appropriate aberration correction can be performed even if the processing position (processing depth) is changed.

  The plurality of intensity conversion lenses or the plurality of phase correction lenses in the laser processing apparatus described above are correction wavefronts for correcting the aberration of the laser light, and each of the plurality of the corresponding lenses respectively corresponding to the plurality of processing positions inside the processing object. Preferably, each different one of the correction wavefronts is generated. In this case, in the laser processing apparatus described above, when the control unit changes (d1) a plurality of processing positions, the control unit converts a lens that generates a correction wavefront corresponding to the processing position to be changed to a plurality of intensity conversion lenses or a plurality of phases. It is preferable to select and switch from the correction lens. On the other hand, in the above laser processing method, (e2) a lens that generates a correction wavefront corresponding to a processing position to be set or changed according to setting or changing of a plurality of processing positions is replaced with a plurality of intensity conversion lenses or a plurality of phase corrections. It is preferable to select and switch from the lens.

  According to the present invention, it is possible to appropriately correct aberrations even when processing positions in the depth direction inside the processing object that are different in depth direction.

It is a block diagram which shows an example of a homogenizer. It is a figure which shows an example of intensity distribution of the incident laser beam in a homogenizer, and an example of desired intensity distribution of an emitted laser beam. It is a figure which shows an example of the shape of an intensity | strength conversion lens. It is a figure which shows an example of the shape of a phase correction lens. It is a figure which shows the measurement result of an example of the spatial mode (intensity distribution) of the incident laser beam to an intensity | strength conversion lens. It is a figure which shows the measurement result of an example of the spatial mode (intensity distribution) after the emitted laser beam from an intensity | strength conversion lens propagated 685 mm. It is a figure which shows an example of a measurement system. It is a figure which shows the result of having measured an example of the wave front in the position where a condensing lens is mounted in the measurement system shown in FIG. It is a figure which shows an example of the correction | amendment wavefront for correct | amending the spherical aberration which arises when condensing a laser beam to the process position (depth) inside a process target. It is a figure which shows the modification of the shape of a phase correction lens. It is a figure which shows the wave front produced by the phase correction lens shown in FIG. It is a lineblock diagram showing the laser processing device concerning a 1st embodiment of the present invention. It is a flowchart which shows the procedure of the laser processing method which concerns on the 1st Embodiment of this invention. It is a figure which shows the result of having observed the condensing point of the condensing lens in the state which does not use an intensity | strength conversion lens in the measurement system shown in FIG. It is a figure which shows the result of having observed the condensing point of the condensing lens in the state using an intensity | strength conversion lens in the measurement system shown in FIG. In the measurement system shown in FIG. 7, it is a figure which shows the result of having measured the beam profile before 10 micrometers from the condensing point of the condensing lens in the state which does not use an intensity | strength conversion lens. FIG. 8 is a diagram illustrating a result of measuring a beam profile 10 μm before the condensing point of the condensing lens in the state where the intensity conversion lens is used in the measurement system illustrated in FIG. 7. It is a block diagram which shows the laser processing apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the laser processing method which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the laser processing apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the laser processing apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the laser processing apparatus which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the laser processing apparatus which concerns on the modification of 1st Embodiment. It is a block diagram which shows the laser processing apparatus which concerns on the modification of 2nd Embodiment. It is a block diagram which shows the laser processing apparatus which concerns on the modification of 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  Before describing the embodiment of the present invention, a homogenizer and a method for designing the shape of the aspherical surface of the homogenizer will be described. FIG. 1 is a configuration diagram illustrating an example of a homogenizer. The homogenizer 10X is for shaping the intensity distribution of laser light into an arbitrary shape, and includes a pair of aspheric lenses 11X and 12X. The aspheric lens 11X on the incident side functions as an intensity conversion lens that shapes the intensity distribution of the laser light into an arbitrary shape, and the aspheric lens 12X on the emission side aligns the phase of the shaped laser light and corrects it to a plane wave. Functions as a phase correction lens. In the homogenizer 10X, it is possible to generate the outgoing laser light Oo in which the intensity distribution of the incident laser light Oi is shaped into a desired intensity distribution by the aspheric shape design of the pair of aspheric lenses 11X and 12X.

  Hereinafter, an example of the aspherical shape design of the pair of aspherical lenses 11X and 12X in the homogenizer 10X will be exemplified. For example, a desired intensity distribution is set to a spatially uniform intensity distribution desired in a laser processing apparatus or the like, that is, a uniform intensity distribution (Oo in FIG. 2). Here, the desired intensity distribution needs to be set so that the energy (area of the desired intensity distribution) of the emitted laser beam Oo is equal to the energy (area of the intensity distribution) of the incident laser beam Oi. Therefore, for example, the uniform intensity distribution may be set as follows.

The intensity distribution of the incident laser beam Oi is a concentric Gaussian distribution (wavelength 532 nm) as shown in FIG. Since the Gaussian distribution is expressed by the following equation (1), the energy within the radius r ₁ of the incident laser light Oi is expressed by the following equation (2).


In this case, since the Gaussian distribution is rotationally symmetric about a radius of 0 mm, an aspheric shape is designed by one-dimensional analysis.

On the other hand, the desired intensity distribution of the emitted laser beam Oo is set to a uniform intensity distribution (order N) as shown in FIG. Since the uniform intensity distribution is expressed by the following equation (3), the emission is made so that the energy within the radius r ₂ of the emission laser beam Oo is equal to the energy of the incident laser beam Oi as in the following equation (4). The value E _{0 of the} uniform intensity portion of the laser beam Oo is set.


Note that, based on this method, the desired intensity distribution of the shaped outgoing laser light can be not only a specified function but also an arbitrary intensity distribution.

  Thereafter, as shown in FIG. 1, the intensity distribution of the incident laser light Oi in the intensity conversion lens 11X becomes the outgoing laser light Oo having a desired intensity distribution in the phase correction lens 12X, that is, the center in the incident laser light Oi. An optical path from the aspherical surface 11a of the intensity conversion lens 11X to the aspherical surface 12a of the phase correction lens 12X so that light having a strong intensity in the vicinity is diffused to the peripheral part and light having a low intensity in the peripheral part is converged. The optical paths P1 to P8 at arbitrary coordinates in the radial direction of the aspherical lens are obtained.

Thereafter, the shape of the aspherical surface 11a of the intensity conversion lens 11X is obtained based on the obtained optical paths P1 to P8. Specifically, as the optical path P1~P8 is obtained, determine the difference in height of the aspheric surface 11a at each coordinate in the radial r ₁ direction with respect to the center of the intensity conversion lens 11X. Then, as shown in FIG. 3, the shape of the aspherical surface 11a of the intensity conversion lens 11X is obtained.

On the other hand, the shape of the aspherical surface 12a of the phase correction lens 12X is obtained so that the phases of the laser beams in the optical paths P1 to P8 are aligned and become a plane wave. Specifically, determining the difference in height of the aspheric surface 12a at each coordinate in the radial r ₂ direction center of the phase correction lens 12X as a reference. Then, as shown in FIG. 4, the shape of the aspherical surface 12a of the phase correction lens 12X is obtained.

3 and 4, MgF ₂ (n = 1.38) is used as the material of the aspherical lenses 11X and 12X, and the center position of the aspherical surface 11a (the position of the coordinate r ₁ = 0) and the aspherical surface 12a This is an example when the distance from the center position (position of coordinate r ₂ = 0) is designed as L = 685 mm.

  Here, the spatial mode (intensity distribution) of the laser beam incident on the intensity conversion lens 11X in the homogenizer 10X and the spatial mode (intensity distribution) after the 685 mm propagation of the laser beam emitted from the intensity conversion lens 11X are defined as an imaging lens. It was measured by a beam profiler through the system. These measurement results are shown in FIGS. Thus, according to the intensity conversion lens 11X, it was confirmed that the intensity distribution of the laser beam can be shaped into a spatially uniform intensity distribution almost as designed after propagation of L = 685 mm which is a lens interval design value.

  Next, the wavefront distortion caused by the intensity conversion lens 11X in the homogenizer 10X was measured with the measurement system shown in FIG. In this measurement system, the laser light from the laser light source 20 is enlarged by the expander 30 and is incident on the intensity conversion lens 11X. The laser beam emitted from the intensity conversion lens 11X is incident on the condenser lens 50 via the reflecting mirrors 21 and 22 and the imaging optical system 40. The expander 30 is composed of a pair of concave lens 31 and convex lens 32, and the laser light from the laser light source 20 is enlarged to adapt the beam diameter to the diameter of the intensity conversion lens 11X. The imaging optical system 40 includes a pair of lenses 41 and 42, which forms an image of the wavefront at the position where the phase correction lens is disposed on the pupil plane of the condenser lens 50, and the beam. The diameter was adapted to the pupil diameter of the condenser lens 50. This avoids the fact that the intensity distribution and the wavefront are actually distorted according to the propagation distance even when the phase correction lens is not arranged and even when the phase correction lens is arranged at the design position of the intensity conversion lens. Because.

  In this measurement system, the wavefront at the position where the condenser lens 50 is mounted was measured by a wavefront sensor. The measurement results are shown in FIG. According to FIG. 8, the intensity conversion lens 11X shapes the intensity distribution of the incident laser light, but at the same time, changes the wavefront of the incident laser light (in other words, the phase of the incident laser light).

  On the other hand, for example, a laser beam having a wavelength of 532 nm is condensed at a depth of 94 μm inside SiC (refractive index 2.6) using a condenser lens with NA = 0.8 and focal length f = 1.8 mm. FIG. 9 shows a correction wavefront that is necessary for correcting the spherical aberration generated in FIG.

  According to FIGS. 8 and 9, the wave fronts of both are similar. Thus, the inventors of the present application have found that it is possible to correct the aberration generated inside the object to be processed by using the wavefront change caused by the intensity conversion lens 11X.

Further, the inventors of the present application use the wavefront change generated by the phase correction lens 12X for fixing the intensity conversion lens 11X and aligning the phase of the laser light shaped by the intensity conversion lens 11X to correct the plane wave. The inventors have found that it is possible to correct aberrations occurring inside the workpiece. For example, as shown in FIG. 10, when the shape of the phase control lens is deformed, the wavefront shown in FIG. 11 is obtained. This wavefront corresponds to a correction wavefront for correcting spherical aberration occurring at a depth of 200 μm inside SiC (refractive index 2.6).
[First Embodiment]

  FIG. 12 is a configuration diagram showing the laser processing apparatus according to the first embodiment of the present invention. The laser processing apparatus 1 according to the first embodiment includes a laser light source 20, an expander 30, a plurality of intensity conversion lenses 11, a lens holder 15, a condenser lens 50, a drive unit 51, and a stage 52. , A surface observation unit 60, a dichroic mirror 61, an autofocus unit 70, a dichroic mirror 71, and a control unit 80. In the first embodiment, the plurality of intensity conversion lenses 11 correspond to the light shaping unit described in the claims.

  For example, the laser light source 20 generates laser light having a Gaussian distribution shape with a wavelength of 532 nm and outputs the laser light to the expander 30. The expander 30 is composed of, for example, a pair of concave lens 31 and convex lens 32, expands the laser light from the laser light source 20, and outputs it to any one of the plurality of intensity conversion lenses 11.

  The plurality of intensity conversion lenses 11 generate correction wavefronts that are correction wavefronts necessary for correcting spherical aberration that occurs when the laser beam is focused inside the workpiece. The correction wavefronts generated by the plurality of intensity conversion lenses 11 respectively correspond to a plurality of different processing positions (depths) inside the processing target. The plurality of intensity conversion lenses 11 are mounted on the lens holder 15.

  The lens holder 15 has a disk shape, and a plurality of intensity conversion lenses 11 are arranged on the periphery thereof. The lens holder 15 rotates to selectively correspond the plurality of intensity conversion lenses 11 to the laser light.

  The condensing lens 50 condenses the laser light from the intensity conversion lens 11 to a predetermined processing position (depth) inside the processing object 100 arranged on the stage 52. The condenser lens 50 is movable by the drive unit 51. The workpiece 100 is also movable by the stage 52. The movement of the drive unit 51 and the stage 52 is controlled by the control unit 80.

  In the present embodiment, dichroic mirrors 61 and 71 for the surface observation unit 60 and the autofocus unit 70 are sequentially disposed between the intensity conversion lens 11 and the condenser lens 50. The surface observation unit 60 observes the surface of the object to be processed via the dichroic mirror 61. The autofocus unit 70 detects the distance to the surface of the workpiece via the dichroic mirror 71.

  The control unit 80 controls the laser light source 20 to output / stop the laser light. The control unit 80 moves at least one of the drive unit 51 and the stage 52 when switching the processing position inside the processing object 100, and at least any of the condenser lens 50 and the processing object 100. To move. For example, the control unit 80 switches the processing position inside the processing object 100 by controlling the relative position between the condenser lens 50 and the processing object 100 using the autofocus unit 70.

  Further, when switching the processing position inside the processing object 100, the control unit 80 rotates the lens holder 15 and switches to the intensity conversion lens 11 capable of correcting the aberration at the processing position. For example, the control unit 80 stores information in which a plurality of processing positions and a plurality of intensity conversion lenses 11 that generate correction wavefronts that can correct aberrations generated at the plurality of processing positions are associated in advance. Based on this information, the control unit 80 selects and switches the intensity conversion lens 11 corresponding to the processing position to be switched from a plurality of intensity conversion lenses.

  FIG. 13 is a flowchart showing the procedure of the laser processing method according to the first embodiment of the present invention. First, a condensing point is set on the surface of the workpiece 100, and this position is set as the processing origin (step S01). Next, a processing position (depth) inside the processing object 100 is set (step S02).

  Next, an intensity conversion lens capable of correcting spherical aberration at the set processing position is selected and switched (step S03). Next, the stage 52 is moved so that the laser beam is focused on the set processing position. Next, the laser beam is irradiated to start processing. Then, the laser beam is condensed at the set processing position (step S04).

  Next, at the end of processing, laser beam irradiation is stopped (step S05). If there is another machining position, the process returns to step S02, and if not, the machining of the workpiece 100 is terminated (step S06).

  In order to focus the laser beam at the set processing position (depth), the relative position between the condenser lens and the processing target may be changed. Instead, the condensing lens 50 may be moved by the drive unit 51, or both may be moved. In the case where the condenser lens 50 is moved, when the entrance pupil of the condenser lens 50 and the intensity conversion lens 11 are in an imaging relationship, the unit of the condenser optical system from the intensity conversion lens 11 to the condenser lens 50 is used. Need to move in.

  As described above, according to the laser processing apparatus 1 and the laser processing method of the first embodiment, the plurality of intensity conversion lenses 11 that generate different correction wavefronts are provided, and the control unit 80 has a plurality of units according to the change of the processing position. Since the intensity conversion lens 11 is switched, appropriate aberration correction can be performed even if the processing position (processing depth) is changed. In other words, according to the laser processing apparatus 1 and the laser processing method of the first embodiment, it is possible to correct aberrations at an arbitrary processing position (depth).

  Incidentally, instead of providing a plurality of intensity conversion lenses as in the first embodiment, a method of changing the correction wavefront in the SLM using a spatial light modulator (hereinafter referred to as SLM) is also conceivable. However, when the SLM is used, it is expected that the laser beam is enlarged and only the center portion of the laser beam is cut out and used, and the utilization efficiency of the laser beam is expected to be poor. On the other hand, according to the first embodiment, since the intensity conversion lens itself has an aberration correction function, it is possible to use all the laser light incident on the pupil region of the condenser lens and improve the use efficiency of the laser light. It becomes possible to do.

  In addition, according to the laser processing apparatus 1 and the laser processing method of the first embodiment, the intensity conversion lens 11 can efficiently process only the inside without destroying the surface of the processing object. The verification results are shown below.

  FIG. 14 is a diagram illustrating a result of observing a condensing point of the condensing lens 50 in a state where the intensity conversion lens 11X is not used in the measurement system illustrated in FIG. 7, and FIG. 15 is a diagram illustrating the measurement system illustrated in FIG. FIG. 5 is a diagram showing a result of observing a condensing point of the condensing lens 50 in a state where the intensity conversion lens 11X is used. According to FIGS. 14 and 15, by using the intensity conversion lens 11X, the effective NA of the condenser lens 50 is increased and the spot diameter is reduced. Thus, the processing position inside the processing object can be processed efficiently.

On the other hand, FIG. 16 shows the measurement result of the beam profile 10 μm before (the condensing lens side) from the condensing point of the condensing lens 50 in the state where the intensity conversion lens 11X is not used in the measurement system shown in FIG. FIG. 17 is a diagram showing a result of measuring the beam profile 10 μm before the condensing point of the condensing lens 50 in the state where the intensity conversion lens 11X is used in the measurement system shown in FIG. is there. According to FIGS. 16 and 17, by using the intensity conversion lens 11 </ b> X, the beam area 10 μm before the condensing point of the condensing lens 50 is increased, and the light intensity per unit area is reduced. This avoids surface destruction of the workpiece.
[Second Embodiment]

  FIG. 18 is a block diagram showing a laser processing apparatus according to the second embodiment of the present invention. The laser processing apparatus 2 according to the second embodiment includes a single intensity conversion lens 11 instead of the plurality of intensity conversion lenses 11 in the laser processing apparatus 1, and further includes a plurality of phase correction lenses 12. Different from the first embodiment. Further, the laser processing apparatus 2 of the second embodiment is different from the first embodiment in a configuration including a control unit 80A instead of the control unit 80. Other configurations of the laser processing apparatus 2 are the same as those of the laser processing apparatus 1. In the second embodiment, the intensity conversion lens 11 and the plurality of phase correction lenses 12 correspond to the light shaping unit described in the claims.

  The plurality of phase correction lenses 12 generate correction wavefronts that are correction wavefronts necessary for correcting spherical aberration that occurs when the laser beam is focused inside the object to be processed. The correction wavefronts of the plurality of phase correction lenses 12 respectively correspond to a plurality of different processing positions (depths) inside the processing object. The plurality of phase correction lenses 12 are mounted on the lens holder 15.

  The lens holder 15 has a disk shape, and a plurality of phase correction lenses 12 are arranged on the periphery thereof. The lens holder 15 rotates to selectively cause the plurality of phase correction lenses 12 to correspond to the laser light.

  Similarly to the control unit 80, the control unit 80A controls the laser light source 20 to output / stop the laser light. Similarly to the control unit 80, the control unit 80A moves at least one of the drive unit 51 and the stage 52 to switch the condenser lens 50 and the processing target when switching the processing position inside the processing target 100. Move at least one of the objects 100.

  Further, when the processing position within the processing object 100 is switched, the control unit 80A rotates the lens holder 15 and switches to the phase correction lens 12 capable of correcting the aberration at the processing position. For example, the control unit 80A stores information in which a plurality of processing positions and a plurality of phase correction lenses 12 that generate correction wavefronts that can correct aberrations generated at the plurality of processing positions are associated in advance. Based on this information, the control unit 80A selects and switches the phase correction lens 12 corresponding to the processing position to be switched from among the plurality of phase correction lenses.

  FIG. 19 is a flowchart showing a procedure of a laser processing method according to the second embodiment of the present invention. First, similarly to the first embodiment, a condensing point is set on the surface of the processing object 100, and this position is set as a processing origin (step S01). Next, a processing position (depth) inside the processing object 100 is set (step S02).

  Next, in the second embodiment, a phase correction lens capable of correcting spherical aberration at the set processing position (depth) is selected and switched (step S13). Next, as in the first embodiment, the stage 52 is moved so that the laser beam is focused at the set processing position (depth). Next, the laser beam is irradiated to start processing. Then, the laser beam is condensed at the set processing position (step S04).

  Next, at the end of processing, laser beam irradiation is stopped (step S05). If there is another machining position, the process returns to step S02, and if not, the machining of the workpiece 100 is terminated (step S06).

  As described above, according to the laser processing apparatus 2 and the laser processing method of the second embodiment, the plurality of phase correction lenses 12 that generate different correction wavefronts are provided, and the control unit 80 </ b> A changes in accordance with the change of the processing position. Therefore, even when the processing position (processing depth) is changed, appropriate aberration correction can be performed. In other words, even with the laser processing apparatus 2 and the laser processing method of the second embodiment, aberration correction at an arbitrary processing position (depth) is possible.

Also in the second embodiment, since the phase correction lens itself has an aberration correction function, it is possible to use all of the laser light incident on the pupil region of the condenser lens and improve the efficiency of using the laser light. Is possible. In the laser processing apparatus 2 and the laser processing method of the second embodiment, the intensity conversion lens 11 can efficiently process only the inside without destroying the surface of the object to be processed.
[Third Embodiment]

  FIG. 20 is a configuration diagram showing a laser processing apparatus according to the third embodiment of the present invention. The laser processing apparatus 3 according to the third embodiment is different from the second embodiment in that the laser processing apparatus 2 further includes reflecting mirrors 21 and 22 and an imaging optical system 40. Other configurations of the laser processing apparatus 3 are the same as those of the laser processing apparatus 2.

  The reflecting mirrors 21 and 22 change the traveling direction of the laser light from the phase correction lens 12 by 90 °. Specifically, the reflecting mirrors 21 and 22 change the traveling direction of the laser light by 135 °, respectively. As a result, the traveling direction of the laser light from the phase correction lens 12 is changed by 90 °, and the imaging optical system 40 is changed. Directed.

  The imaging optical system 40 has a pair of lenses 41 and 42, and forms an image of the laser beam on the incident side imaging surface on the emission side imaging surface. The incident-side imaging plane of the imaging optical system 40 is set as the exit plane of the phase correction lens 12, and the exit-side imaging plane is set as the pupil plane of the condenser lens 50. The imaging optical system 40 preferably functions as an enlarging optical system or a reducing optical system that adapts the beam diameter of the laser light on the incident-side imaging surface to the size of the pupil plane of the condenser lens 50. Thereby, all the laser light incident on the pupil region of the condenser lens 50 can be used, and the utilization efficiency of the laser light is relatively improved.

  The laser processing apparatus 3 of the third embodiment can obtain the same advantages as the laser processing apparatus 2 of the second embodiment.

Furthermore, according to the laser processing apparatus 3 of the third embodiment, the wavefront after propagation of the phase correction lens 12 can be imaged on the pupil plane of the condenser lens 50 by the imaging optical system 40. This is suitable when the lens 12 cannot be disposed near the pupil plane of the condenser lens 50.
[Fourth Embodiment]

  FIG. 21 is a block diagram showing a laser processing apparatus according to the fourth embodiment of the present invention. The laser processing apparatus 4 according to the fourth embodiment includes a beam splitter 91 instead of the reflecting mirror 22 in the laser processing apparatus 3, and further includes a beam splitter 92 and an observation optical system 90. Different from form. Other configurations of the laser processing apparatus 4 are the same as those of the laser processing apparatus 3.

  The observation optical system 90 includes a camera 95, a lens 96, and a light source 97. The light source 97 irradiates the workpiece 100 with light via the beam splitters 92 and 91, the imaging optical system 40, the dichroic mirrors 61 and 71, and the condenser lens 50. The camera 95 is for observing the workpiece 100 through the lens 96, the beam splitters 92 and 91, the imaging optical system 40, the dichroic mirrors 61 and 71, and the condenser lens 50.

  The laser processing apparatus 4 of the fourth embodiment can obtain the same advantages as the laser processing apparatus 3 of the third embodiment.

Moreover, according to the laser processing apparatus 4 of 4th Embodiment, it becomes possible to observe the process target object 100 during laser processing.
[Fifth Embodiment]

  FIG. 22 is a block diagram showing a laser processing apparatus according to the fifth embodiment of the present invention. The laser processing apparatus 5 of the fifth embodiment is the same as the laser processing apparatus 3 except that the expander 30 and the reflecting mirrors 21 and 22 are replaced with an attenuator 30A and reflecting mirrors 23, 24, 25, 26, and 27. Different from the third embodiment.

  More specifically, each of the reflecting mirrors 23 to 27 changes the traveling direction of the laser light by 90 °, and as a result, the traveling direction of the laser light from the laser light source 20 is changed by 90 °. An attenuator 30A is disposed between the reflecting mirror 23 and the reflecting mirror 24, and the intensity conversion lens 11 is disposed between the reflecting mirror 24 and the reflecting mirror 25. The reflecting mirror 25, the reflecting mirror 26, and A plurality of phase correction lenses 12 and a lens holder 15 are disposed between them, and one lens 41 in the imaging optical system 40 is disposed between the reflecting mirror 26 and the reflecting mirror 27. Between the lens 27 and the dichroic mirror 61, the other lens 42 in the imaging optical system 40 is disposed.

  The attenuator 30A includes a λ / 2 wavelength plate 31A, a polarization beam splitter 32A, and a damper 33A, and outputs laser light having a predetermined polarization plane to the intensity conversion lens 11. Other configurations of the laser processing apparatus 5 are the same as those of the laser processing apparatus 3.

  The laser processing apparatus 5 of the fifth embodiment can obtain the same advantages as the laser processing apparatus 3 of the third embodiment.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the present embodiment, the mode in which the plurality of intensity conversion lenses 11 or the plurality of phase correction lenses 12 are switched by rotating the disk-shaped lens holder 15 is illustrated. However, the plurality of intensity conversion lenses 11 or the plurality of phase correction lenses are switched. The method of switching the lens 12 is not limited to this. For example, as in laser processing apparatuses 1A to 3A illustrated in FIGS. 23 to 25, in the laser processing apparatuses 1 to 3 of the first to third embodiments, a belt-shaped lens holder 15A is used instead of the disk-shaped lens holder 15. May be provided. In this case, the plurality of intensity conversion lenses 11 or the plurality of phase correction lenses 12 are arranged in a band-shaped lens holder 15A, and the plurality of intensity conversion lenses 11 or the plurality of phase correction lenses 12 are selected by sliding the lens holder 15A. Can be switched automatically.

  Further, in the present embodiment, an example in which only one of the plurality of intensity conversion lenses 11 and the plurality of phase correction lenses 12 is switched is illustrated, but both of the plurality of intensity conversion lenses 11 and the plurality of phase correction lenses 12 are switched. May be. According to this, it is possible to correct aberrations more precisely by combining the correction wavefronts of the plurality of intensity conversion lenses 11 and the correction wavefronts of the plurality of phase correction lenses 12.

  1, 2, 3, 4, 5, 1A, 2A, 3A ... laser processing apparatus, 10X ... homogenizer, 11, 11X ... intensity conversion lens (aspheric lens), 12, 12X ... phase correction lens (aspheric lens), DESCRIPTION OF SYMBOLS 15,15A ... Lens holder, 20 ... Laser light source, 21-27 ... Reflector, 30 ... Expander, 31 ... Concave lens, 32 ... Convex lens, 30A ... Attenuator, 31A ... λ / 2 wavelength plate, 32A ... Polarizing beam splitter, 33A ... damper, 40 ... imaging optical system, 41, 42 ... lens, 50 ... condensing lens, 51 ... drive unit, 52 ... stage, 60 ... surface observation unit, 61, 71 ... dichroic mirror, 70 ... autofocus unit 80, 80A ... control unit, 90 ... observation optical system, 92, 91 ... beam splitter, 95 ... camera, 96 ... lens, 97 ... Source, 100 ... workpiece.

Claims (4)

A laser processing apparatus for condensing laser light inside a workpiece having light permeability,
A light source for generating laser light;
A light shaping unit that converts the intensity distribution of the laser light from the light source into a desired intensity distribution; and
A condensing lens for condensing the laser light from the light shaping unit at a processing position inside the processing object;
A control unit for controlling the light shaping unit;
With
The light shaping unit is
An intensity conversion lens that converts the intensity distribution of the laser light from the light source into a desired intensity distribution, and a plurality of intensity conversion lenses that generate different wavefronts, or
An intensity conversion lens that converts the intensity distribution of the laser light from the light source and shapes it into a desired intensity distribution, and a phase correction lens that corrects the phase of the emitted laser light from the intensity conversion lens, each having a different wavefront Multiple phase correction lenses, which produce
Have
The control unit switches the plurality of intensity conversion lenses or the plurality of phase correction lenses when changing the processing position,
Laser processing equipment. The plurality of intensity conversion lenses or the plurality of phase correction lenses are correction wavefronts for correcting aberrations of laser light, and the plurality of correction wavefronts respectively corresponding to a plurality of processing positions inside the processing object. Create different ones of each,
The control unit, when changing the plurality of processing positions, select and switch a lens that generates a correction wavefront corresponding to the processing position to be changed from the plurality of intensity conversion lenses or the plurality of phase correction lenses,
The laser processing apparatus according to claim 1. A light source that generates laser light, a light shaping unit that converts the intensity distribution of the laser light from the light source and shapes the laser light into a desired intensity distribution, and a processing position of the laser light from the light shaping unit inside the workpiece A laser processing apparatus including a condensing lens that condenses the light shaping unit,
An intensity conversion lens that converts the intensity distribution of the laser light from the light source into a desired intensity distribution, and a plurality of intensity conversion lenses that generate different wavefronts, or
An intensity conversion lens that converts the intensity distribution of the laser light from the light source and shapes it into a desired intensity distribution, and a phase correction lens that corrects the phase of the emitted laser light from the intensity conversion lens, each having a different wavefront Multiple phase correction lenses, which produce
In the laser processing method of the laser processing apparatus having
Set or change the processing position within the processing object,
According to the setting or change of the processing position, the plurality of intensity conversion lenses or the plurality of phase correction lenses are switched,
Irradiating a laser beam from the light source to a processing position in the processing object;
Laser processing method. The plurality of intensity conversion lenses or the plurality of phase correction lenses are correction wavefronts for correcting aberrations of laser light, and the plurality of correction wavefronts respectively corresponding to a plurality of processing positions inside the processing object. Each of which produces a different one,
According to the setting or changing of the plurality of processing positions, a lens that generates a correction wavefront corresponding to the processing position to be set or changed is selected and switched from the plurality of intensity conversion lenses or the plurality of phase correction lenses.
The laser processing method according to claim 3.