TWI498182B - Laser processing apparatus - Google Patents

Description

Laser processing device

The present invention relates to a laser processing apparatus for processing a workpiece by irradiating laser light.

A technique for processing a workpiece (hereinafter, also referred to simply as a laser processing or a laser processing technique) as irradiation pulsed laser light (hereinafter also referred to as laser light for short) is well known as the following method (for example, referring to a patent) Document 1): Laser light having an ultrashort pulse having a pulse width of psec is irradiated on the upper surface of the workpiece while scanning, thereby sequentially causing the workpiece to be opened between the irradiated regions of the respective unit pulsed lights or The splitting is formed as a starting point (dividing starting point) for dividing as a continuous surface of the split surface or the split surface formed in each of the irradiated regions.

In Patent Document 1, a workpiece having a light-emitting element structure such as an LED (Light Emitting Diode) structure is formed on a substrate including a material such as a hard brittle and optically transparent material such as sapphire, and is divided into wafers. The above method is particularly effective when the unit is in the case of a unit. This is because the total reflectance at the position is lowered by forming fine concavities and convexities on the cleaved/cleaved surface, whereby the light extraction efficiency of the light-emitting element can be improved.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-131256

In the case where the starting point of the division is set for the workpiece, generally, the deeper the division starting point is formed, the easier the division is thereafter. However, in the case of the method disclosed in Patent Document 1, since the portion where the split/split is generated is only the vicinity of the surface of the workpiece, if the thickness of the workpiece becomes large, it is difficult to open the position to a deeper position. / Splitting to form a good starting point for segmentation. Even if the irradiation power of the laser light or the irradiation energy per unit length of the scribe line is simply increased, it will cause unnecessary damage to the workpiece, which is not preferable.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a laser processing apparatus capable of forming a division starting point when a workpiece is divided, so that a splitting/cracking can be generated at a deeper position inside the workpiece than before. .

In order to solve the above problems, the invention of claim 1 is a laser processing apparatus characterized in that it irradiates laser light to process a workpiece, and includes a stage portion that fixes a workpiece; An optical system that irradiates, to a workpiece fixed to the stage portion, a pulsed laser light emitted from a laser light source from a lens for illumination; and the optical system includes a pulsed laser light that is emitted from the laser light source. The branching unit is branched into a plurality of branched optical paths, and each of the plurality of branched optical paths includes a lens group that includes the illumination lens in common but has a different combined focal length, thereby passing through the plurality of branched optical paths and from the illumination lens The focus position of each of the plurality of pulsed laser beams irradiated to the illuminated position is different.

According to a second aspect of the invention, in the laser processing apparatus of the first aspect, the branching unit branches the one-pulse laser light into the first and second branched optical paths, and the first branched optical path includes only the above-mentioned The irradiation lens is the lens group, and the second branch optical path includes the lens group having the composite focal length different from a focal length of the illumination lens by the illumination lens and the at least one focus position adjustment lens. When the first plurality of pulsed lasers are the first pulsed laser light along the first optical path, and the plurality of pulsed lasers are used as the second pulsed laser light along the second optical path, the The first pulse laser light is irradiated so that the position of the focal length of the illumination lens is at the focus position, and the second pulse laser light is made to be the same as the first pulse laser light. Irradiation is performed such that the position at which the focus position is different becomes the above-described focus position.

According to a third aspect of the invention, in the laser processing apparatus of the second aspect, the focus position adjusting lens includes at least one of a concave lens and a convex lens.

The laser processing apparatus according to any one of claims 1 to 3, further comprising: an optical path length variable unit that changes at least one of the first or second branched optical paths The light path is long.

The laser processing apparatus according to any one of claims 1 to 3, characterized in that the laser light source emits ultrashort pulse light having a pulse width of psec as the pulsed laser light.

According to the inventions of claims 1 to 5, by the carrier to which the workpiece is fixed The stage portion is appropriately moved, and a plurality of pulsed laser beams having different focus positions are irradiated to the workpiece, and a plurality of types of processing positions of the workpiece can be processed. For example, by appropriately setting the irradiation conditions of the pulsed laser light or the like, the plurality of pulsed laser beams are spatially and temporally identical in the irradiated position on the illuminated surface of each unit of pulsed light, and the respective focal points are When the position is a different depth position inside the workpiece, the irradiation lens is superimposed and irradiated, and when the irradiation position is scanned along the processing line under the condition that the irradiation surface is discrete, the processing can be performed. The different depth positions of the objects produce a process of splitting/cracking along the direction of the planned line.

<Basic Principles of Processing>

The basic principle of the processing realized in the embodiment of the present invention is the same as the processing principle disclosed in Patent Document 1. Therefore, only the outline will be described below. The processing performed in the present invention is generally a process in which pulsed laser light (hereinafter also referred to simply as laser light) is irradiated onto the upper surface (processed surface) of the workpiece while scanning, thereby causing each pulse A split or split of the workpiece is sequentially generated between the irradiated regions, and a starting point (divided starting point) for division is formed as a continuous surface of the split surface or the split surface formed in each of the irradiated regions.

Further, in the present embodiment, the cleavage means a phenomenon in which the workpiece is substantially regularly broken along the crystal plane other than the cleavage surface, and the crystal surface is referred to as a cleavage surface. In addition, in addition to being split or split as a microscopic phenomenon completely along the crystal plane, there is also a crack along the macroscopic fracture along the approximate The situation in which a fixed crystal orientation is produced. Depending on the substance, there is also a case where only one of splitting, cracking, or cracking is mainly generated. However, in order to avoid the cumbersomeness of the description, the splitting, cracking, and cracking are not collectively referred to as splitting/cracking. Further, the processing of the above-described form is sometimes simply referred to as splitting/cracking processing or the like.

Hereinafter, a case will be described in which the workpiece is a hexagonal single crystal substance, and each of the a1 axis, the a2 axis, and the a3 axis which are at a mutually symmetrical position in the C plane thereof at an angle of 120°. The axial direction is an easy-opening/cleaving direction, and the planned line is perpendicular to any of the a1 axis direction, the a2 axis direction, and the a3 axis direction. More generally, this is the case where the direction equivalent to the two different easy-open/cleavage directions (the direction of the symmetry axis of the two easy-open/cleavage directions) becomes the direction of the planned line. In addition, hereinafter, laser light irradiated for each pulse is referred to as unit pulse light.

Fig. 1 is a view schematically showing a processing form of a splitting/cracking process. In FIG. 1, the case where the a1 axis direction is orthogonal to the process planned line L is illustrated. Fig. 1(a) is a view showing the azimuthal relationship between the a1 axis direction, the a2 axis direction, and the a3 axis direction and the planned planned line L in the above case. Fig. 1(b) shows a state in which the unit pulse light of the first pulse of the laser light is irradiated onto the irradiated region RE11 at the end of the planned line L.

In general, the irradiation of the unit pulsed light applies a relatively high energy to a very small region of the workpiece, and therefore, the irradiation causes the illuminated surface to be equal to or more irradiated than the irradiated region of the unit pulsed light (laser light). A larger range produces material deterioration, melting, evaporation, and the like.

However, if the irradiation time of the unit pulse light, that is, the pulse width is set When it is extremely short, the material having a narrow spot size of the laser light and having a substantially central portion of the irradiated region RE11 obtains kinetic energy from the irradiated laser light, thereby causing deterioration due to plasmaization or high temperature to a gas state or the like. Further, it is scattered in a direction perpendicular to the surface to be illuminated. On the other hand, an impact or stress generated by irradiation of the unit pulse light, which is represented by a reaction force generated by the scattering, acts on the periphery of the irradiated region, in particular Acts in the a1 axis direction, the a2 axis direction, and the a3 axis direction which are easy to open/crack directions. Thereby, in this direction, although the contact state is maintained in appearance, a slight crack or split occurs locally, or a state in which thermal strain is present inside is generated although the split or split is not achieved. In other words, it can be said that the irradiation of the unit pulse light of the ultrashort pulse functions as a driving force for forming a weak-strength portion which is substantially linear in a plan view in the easy-opening/cracking direction.

In FIG. 1(b), the dotted line arrow schematically indicates the -a2 direction and the +a3 direction in the weak intensity portion formed in each of the easy opening/dissecting directions which are close to the extending direction of the planned line L. Weak strength portions W11a, W12a.

Then, as shown in FIG. 1(c), when the unit pulse light of the second pulse of the laser light is irradiated, and the irradiated area RE12 is formed on the planned line L at a position separated from the illuminated area RE11 by a certain distance, Similarly to the first pulse, a weak intensity portion along the easy-opening/cleaving direction is also formed under the second pulse. For example, the weak intensity portion W11b is formed in the -a3 direction, the weak intensity portion W12b is formed in the +a2 direction, the weak intensity portion W12c is formed in the +a3 direction, and the weak intensity portion W11c is formed in the -a2 direction.

However, at this point in time, the irradiation of the unit pulse light by the first pulse The weak portions W11a and W12a formed are respectively present in the extending directions of the weak portions W11b and W12b. In other words, the direction in which the weak-strength portions W11b and W12b extend can be a portion that can be cleaved or split (high energy absorption rate) by using energy smaller than other portions. Therefore, in actuality, if the unit pulse light of the second pulse is irradiated, the impact or stress generated at this time propagates toward the easy-opening/cracking direction and the weak intensity portion existing at the front end thereof, substantially at the moment of irradiation. The self-weakening strength portion W11b to the weak strength portion W11a and the weakening strength portion W12b to the weak strength portion W12a are completely split or split. Thereby, the split/cleavage surfaces C11a and C11b shown in Fig. 1(d) are formed. Further, the split/cleavage surfaces C11a and C11b can be formed to a depth of about several μm to several tens of μm in the vertical direction in the drawing of the workpiece. Further, on the split/cleavage surfaces C11a and C11b, the crystal surface is slid as a result of strong impact or stress, and undulation occurs in the depth direction.

Further, as shown in FIG. 1(e), if the unit pulse light is sequentially irradiated to the irradiated areas RE11, RE12, RE13, RE14, . . . by scanning the laser light along the processing line L, the The impact/stress generated during the irradiation is sequentially formed along the line to be processed L in order to form linear split/cleavage surfaces C11a and C11b, C12a and C12b, C13a and C13b, C14a and C14b. In the above embodiment, the split/cleavage surface is continuously formed, which is the basic principle of the split/cleavage processing in the present embodiment.

On the other hand, it can be said that the thermal energy is imparted by the irradiation of the unit pulsed light, whereby the surface layer portion of the workpiece is inflated, and each of the irradiated regions RE11, RE12, RE13, RE14, ... is compared. Approximate central area Further to the outside, the vertical tensile stress acts on the split/cleavage surfaces C11a and C11b, C12a and C12b, C13a and C13b, C14a and C14b... to cause the splitting/cracking progress.

That is, in the case shown in FIG. 1, the plurality of irradiated regions discretely existing along the planned line L and the split/cleavage plane formed between the plurality of irradiated regions are integrally processed along the processing. The starting point of the division when the line L divides the workpiece. After the division start point is formed, division by a specific jig or device is performed, whereby the workpiece can be divided substantially in the form of the planned line L.

Further, in the case shown in FIG. 1, the unit pulse light is irradiated so that the planned line is perpendicular to any of the a1 axis direction, the a2 axis direction, and the a3 axis direction. Alternatively, the planned line may be processed. The unit pulse light is irradiated so as to be parallel to any of the a1 axis direction, the a2 axis direction, and the a3 axis direction, or two of the irradiated regions may be alternately arranged along the predetermined line L for clamping. In the form of a zigzag (zigzag shape) in a form that is easy to open/crack, a form of unit pulse light that forms each of the irradiated regions is irradiated.

In order to realize the split/crack processing as described above, it is necessary to irradiate the short-pulse laser light having a short pulse width. Specifically, it is necessary to use laser light having a pulse width of 100 psec or less. For example, it is preferable to use laser light having a pulse width of about 1 psec to 50 psec.

<At the same time multi-focus processing>

In the present embodiment, the multi-focus processing is further developed by the split/cleavage processing of the above principle, and the division is started on the workpiece. point. Fig. 2 is a view schematically showing a state of simultaneous multifocal processing. Fig. 3 is a view showing a pulsed laser light forward mode and a focus position in simultaneous multifocal processing in comparison with a conventional split/split process according to the above-described processing principle. Fig. 3(a) shows the case of simultaneous multifocal processing, and Fig. 3(b) shows the case of the usual split/split processing of irradiating only a single pulsed laser light LB.

In the present embodiment, the simultaneous multifocal processing generally refers to a processing form in which a plurality of pulsed laser beams are spatially and temporally illuminated on the illuminated surface of each unit pulsed light. The same, and the respective focus positions are different from each other in the depth position of the workpiece, and are irradiated from the irradiation lens, and scanned along the planned line under the condition that the irradiation position is dispersed on the irradiation surface. The splitting/cracking in the direction along the planned line is generated at different depth positions of the workpiece.

In the present embodiment, the position to be irradiated refers to the center position (target position) of the region to be irradiated of the unit pulse light on the surface to be irradiated of the workpiece. Specifically, in the simultaneous multifocal processing, the unit pulsed light of each pulsed laser light is irradiated at the same position, but the irradiated area may be different.

In addition, the lens for irradiation refers to a lens that is disposed opposite to the surface to be irradiated (machined surface) of the workpiece, and is a direct source of the pulsed laser light for the workpiece.

In addition, the irradiation position of the unit pulse light on the illuminated surface is spatially and temporally the same, and the pointer is processed along the workpiece. The respective illuminated positions of the predetermined lines cause the illumination timings of all the pulsed lasers to be the same.

According to the simultaneous multifocal processing, by appropriately setting the distance from the illumination lens of each pulsed laser light to the focus position, the split/cleavage plane formed by the respective pulsed laser light is continuously opened/split open. surface. That is, the division starting point can be formed at a deeper position than in the case of irradiating only a single pulsed laser light.

Further, the focus position referred to in the present embodiment does not necessarily mean a position at which the focal length of the lens for illumination is separated. The reason for this is that the focus is a value inherent to the lens or the lens group. Generally, there is only one focus on one side of the lens. Therefore, one illumination lens cannot define a plurality of different focus positions on the one side. In the case of the present embodiment, the illumination lens is used in common, but a plurality of different lens groups are prepared, and the combined focal lengths of the respective lenses are different, thereby realizing a state in which the focus positions of the plurality of pulsed laser beams are different, which will be described later. Detailed situation. In the above case, for the sake of convenience, the case where only the lens having the illumination lens is formed is also considered to form the lens group. In the above case, the focal length of the illumination lens is regarded as the combined focal length.

As a typical example of simultaneous multifocal processing, FIG. 2 and FIG. 3(a) show a case where two pulsed laser beams having different focus positions are superimposed and irradiated. More specifically, as an example of the irradiation form of the pulsed laser light at the time of simultaneous multifocal processing, a case in which the optical axis AX is shared and the lens LE from the illumination is focused to the focus position is illustrated in FIGS. 2 and 3(a). The first processing laser light LBα and the second processing laser light LBβ which are different in the depth direction (thickness direction) of the workpiece S are irradiated with the irradiation timing of each unit pulse light. The irradiated position on the emitting surface is uniformly superimposed while being irradiated, and the irradiated position is relatively scanned with respect to the workpiece S so as to be discrete along the planned line.

More specifically, in FIG. 2 and FIG. 3(a), the focal point Fα of the first processing laser light LBα incident on the illumination lens LE as parallel light is incident on the incident light of the non-parallel light. The focus Fβ of the second processing laser light LBβ to the irradiation lens LE is located deeper.

Further, in the present embodiment, the term "roar light" refers to a parallel light system in which the beam diameter of the laser light does not substantially change (inadvertently changes). On the other hand, the laser light whose beam diameter changes in the direction of the optical axis changes is referred to as non-parallel light. For example, when parallel light is incident on a concave lens or the like, the outgoing light from the concave lens becomes non-parallel light (divergent light).

In the case shown in FIG. 2 and FIG. 3(a), the split/cleavage of the unit pulse light by the first processing laser light LBα is generated at the depth position of the focus Fα and its vicinity, and the depth position of the focus Fβ is generated. In the vicinity thereof, splitting/cracking of the unit pulse light using the second processing laser light LBβ is generated. As shown by the arrow AR1 in Fig. 2, when the first processing laser light LBα and the second processing laser light LBβ are superimposed on each other while moving relative to the workpiece S, the splitting/cracking formed by the two is performed. The open surface is continuous not only in the relative moving direction but also in the depth direction, and as a result, a split/cleaving surface having a large diffusion in the depth direction is formed.

In the normal case where only a single pulsed laser light LB is irradiated as shown in Fig. 3(b), it is necessary to surely generate the split/clearing from the surface of the workpiece. The method defines the position of the focus F. When the multifocal processing is performed as shown in FIG. 2 and FIG. 3(a), the second processing laser light LBβ is generated in the vicinity of the surface of the workpiece to cause the splitting/ Since the splitting/disintegration surface directly formed by the irradiation of the first processing laser light LBα does not have to reach the surface of the workpiece.

Therefore, in the case of simultaneous multifocal processing, the position of the focus Fα of the first processing laser light LBα can be set to be deeper than the position of the focus F when the single pulse laser light LB is irradiated/split. The location.

In the case where the two pulsed laser beams are superimposed to perform simultaneous multifocal processing, in order to make the split/cleavage plane formed by each of them continuous in the depth direction, the focus position of each of the laser light is preferably the distance to be irradiated. The closer surface (the second processing laser light LBβ in FIG. 2) is about 4 μm to 45 μm, and the distance from the illuminated surface (the first processing laser light LBα in FIG. 2) is about 16 μm to 60 μm.

There are various forms for providing a plurality of pulsed laser beams in simultaneous multifocal processing. As a preferred example, there is a form in which pulsed laser light emitted from one source is optically branched into two directions, and The lens for the illumination is shared and the lens groups provided in the two are different, thereby superimposing the pulsed laser light of both. In the above case, it is easy to make the irradiation timing of the unit pulse light of each pulsed laser light to the illuminated surface substantially the same.

Alternatively, instead of the branch as described above, it is possible to work on the configuration of the illumination lens itself, thereby generating a plurality of pulsed laser beams having different focus positions.

In the case of performing simultaneous multifocal processing, the irradiation pitch of the unit pulse light (the center interval of the irradiation position) may be specified in the range of 3 μm to 50 μm. If the irradiation pitch is larger than the range, the formation of the weak strength portion in the easy splitting/cleaving direction does not progress to the extent that the splitting/cleaving plane can be formed, and thus the formation of the splitting as described above is surely formed. The view of the starting point of the split surface is not good. Further, in terms of scanning speed, processing efficiency, and product quality, the larger the irradiation pitch, the better, but in order to form the cleaving/cleaving surface more reliably, it is preferably in the range of 3 μm to 30 μm, more preferably 3 μm. About 20μm.

At present, when the repetition frequency of the laser light is R (kHz), unit pulse light is emitted from the laser light source every 1/R (msec). When the laser light is relatively moved at a speed V (mm/sec) with respect to the workpiece, the irradiation pitch Δ (μm) is defined by Δ = V / R. Therefore, the scanning speed V of the laser light and the repetition frequency are defined such that Δ is about several μm. For example, the scanning speed V is preferably about 50 mm/sec to 3,000 mm/sec, and the repetition frequency R is from 1 kHz to 200 kHz, and particularly preferably from about 10 kHz to about 200 kHz. The specific value of V or R may be appropriately determined in consideration of the material of the workpiece, the absorptivity, the thermal conductivity, the melting point, and the like.

The laser light is preferably irradiated with a beam diameter of about 1 μm to 10 μm. However, the beam diameter of each of the overlapping laser beams may also be different.

Further, the irradiation energy (pulse energy) of each of the laser beams may be appropriately defined within the range of 0.1 μJ to 50 μJ. However, in the present embodiment, a sufficiently good process can be performed in the range of 0.1 μJ to 10 μJ.

Figure 4 shows the simultaneous sapphire single crystal substrate by two pulsed laser beams. The SEM (Scanning Electron Microscope) image of the divided single piece obtained by dividing the substrate along the split/cleavage surface formed by the focus processing. More specifically, FIG. 4 is an SEM image of the vicinity of the intersection of the upper surface of the divided single piece (the irradiated surface of the workpiece) and the divided surface including the split/cleavage surface. In the figure, about 1/3 of the upper side is the upper surface, and the other part is the dividing surface. In the simultaneous multifocal processing, the focus position of each pulsed laser light is set to 6 μm from the closer to the illuminated surface, and is set to 16 μm from the far side to be illuminated, and the irradiation interval of the unit pulse light (the center of the illuminated position) The interval is set to 10 μm.

According to Fig. 4, in the portion where the distance of the dividing surface is farther from the irradiation surface, there is a wedge-shaped region extending in the vertical direction and a stripe-shaped portion which is substantially symmetrical with respect to the left and right in the oblique direction. The former is irradiated to the area of the unit pulsed light. The latter is a split/cleaved surface, and the stripe-shaped portion has a slight unevenness of a height difference of about 0.1 μm to 1 μm, and is a strong impact or stress on the workpiece by irradiating the pulsed laser light. The specific crystal face is formed by sliding.

In Fig. 4, the irradiation pitch of the unit pulse light is 10 μm. If this is taken as a reference, it is understood that the maximum depth of the split/cleavage surface is about 33 μm. Generally, the maximum depth (depth of the starting point of the splitting) of the splitting/cleaving plane in the splitting/cracking process is at most about 12 μm. Therefore, by performing simultaneous multifocal processing, it can be formed at a depth of about 2 times. Split the starting point. Thereby, by performing simultaneous multifocal processing and dividing, the workpiece can be divided with higher precision.

As described above, in the present embodiment, the above-described splitting/cracking is performed by performing At the same time, the multi-focus processing is further developed to limit the occurrence of deterioration or scattering of the workpiece, and on the other hand, the opening or splitting of the workpiece is not only actively generated in the direction of the planned line, It is also actively generated in the depth direction, whereby the division starting point can be formed on the divided body at an extremely high speed as compared with the prior art.

<Overview of laser processing equipment>

Fig. 5 is a view schematically showing the configuration of a laser processing apparatus 100 capable of realizing simultaneous multifocal processing of the present embodiment. Further, the laser processing apparatus 100 is not limited to the simultaneous multi-focus processing, and the laser processing apparatus 100 may perform groove processing, hole drilling, or the like on the workpiece by appropriately changing the irradiation mode of the optical system or the pulsed laser light. As shown in FIG. 5, the laser processing apparatus 100 mainly includes a stage portion 10 and an optical system 20. Further, the laser processing apparatus 100 includes a control unit (not shown) that controls the operation of each unit.

The stage unit 10 mounts a portion where the workpiece S is fixed. The stage unit 10 includes an adsorption mechanism (not shown) that can adsorb and fix the workpiece S placed on the upper surface 10a of the stage unit 10. Further, the stage unit 10 includes a moving mechanism 10m, and the horizontal movement in two orthogonal directions and the rotational movement in the horizontal plane can be performed by the action of the moving mechanism 10m.

The optical system 20 is a portion for irradiating the workpiece S mounted on the stage portion 10 with laser light. The optical system 20 mainly includes a laser light source 21 and three 1/2 wavelength plates 22 (a first 1/2 wavelength plate 22a, a second 1/2 wavelength plate 22b, and a third 1/2 wavelength plate 22c), Four polarization beam splitters 23 (first polarization beam splitter 23a, second polarization beam splitter 23b, third polarization beam splitter 23c, fourth polarization beam splitter 23d), and focus position adjustment lens 24 (first adjustment lens) 24a, second adjustment lens 24b) and illumination lens 25.

The laser light source 21 emits laser light LB0 which is linearly polarized and parallel light. As the above-described laser light source 21, a variety of well-known light sources can be used. It is only necessary to use an appropriate light source depending on the purpose of processing. It is preferred to use a Nd:YAG laser, a Nd:YVO ₄ laser or other solid laser. In addition, the shutter ST is attached to the laser light source 21.

For example, in the case where a scribe line is formed at a dicing street position of an LED substrate on which a sapphire single crystal substrate is used as a base substrate, a psec laser is preferably used. Further, in the present embodiment, the LED substrate refers to a semiconductor substrate on which an LED circuit pattern constituting a unit pattern of each of the LEDs is two-dimensionally arranged, and the dicing means means dividing the LED substrate into individual LEDs. The predetermined position is divided when the wafer is singulated.

The laser light LB0 emitted from the laser light source 21 by opening the shutter ST is appropriately adjusted by the first 1/2 wavelength plate 22a provided on the optical path P0 (the ratio of the P-polarized light to the S-polarized light) .

The laser beam LB0 passing through the first 1/2 wavelength plate 22a reaches the first polarization beam splitter 23a provided on the optical path P0. The first polarization beam splitter 23a branches the laser light LB0 into the first branched light LB1 that advances along the first branched optical path P1 and the second branched light LB2 that travels along the second branched optical path P2. In other words, the first polarization beam splitter 23a functions as a branching unit that branches the laser light LB0 into the first branched light LB1 and the second branched light LB2.

More specifically, the first polarization beam splitter 23a emits the first branched light LB1 as P-polarized transmitted light, and the second branched light LB2 is emitted as reflected light of the S-polarized light. In addition, as a representative of the first polarization beam splitter 23a The vibration splitting mirror 23 uses a transmission efficiency of 90% to 95% and a reflection efficiency of about 99%. Thereby, the optical loss of the polarization beam splitter 23 is minimized.

The first branch optical path P1 and the second branched optical path P2 are appropriately changed in direction by the first mirror 26 or the second mirror 27 provided in the middle thereof by reflecting the first branched light LB1 or the second branched light LB2.

In addition, in FIG. 5, the first mirror 26 and the second mirror 27 are arranged in a plane in which only the pulsed laser light is reflected in the plane formed in the drawing, but this is merely for convenience of illustration. Further, the number of the first reflecting mirror 26 and the second reflecting mirror 27 is not limited to the case illustrated in Fig. 5 . In other words, the first mirror 26 and the second mirror 27 are provided in an appropriate number, arrangement position, and posture in accordance with the layout and the like of the components constituting the optical system 20.

The first branched optical path P1 includes the second half-wavelength plate 22b and the second polarization beam splitter 23b in this order in the direction in which the first branched light LB1 advances. In addition, the first branch optical path P1 is configured such that the first branched light LB1 that is P-polarized and transmitted through the second polarization beam splitter 23b reaches the fourth polarization beam splitter 23d.

The second half-wavelength plate 22b and the second polarization beam splitter 23b are provided for adjusting the amount of light of the first branched light LB1. Specifically, when the first branched light LB1 emitted from the first polarization beam splitter 23a as the P-polarized light does not have the second 1/2 wavelength plate 22b, the second polarization beam splitter 23b is transmitted through the transmission efficiency. On the other hand, when the second 1/2 wavelength plate 22b is provided as described above, the degree of polarization can be adjusted by the second 1/2 wavelength plate 22b, so that the second polarization beam splitter 23b can be transmitted. The ratio of the P-polarized light of the first branched light LB1 is adjusted. Thereby, as a result, the first branch light LB1 The amount of light is adjusted.

On the other hand, the second branch optical path P2 includes the third 1/2 wavelength plate 22c, the third polarization beam splitter 23c, and the focus position adjustment lens 24 in this order in the direction in which the second branch light LB2 advances. In addition, in the second branch optical path P2, the second branched light LB2 which is the S-polarized light reflected by the third polarization beam splitter 23c passes through the focus position adjustment lens 24 and reaches the fourth polarization beam splitter. The structure of 23d.

Further, in the second branch optical path P2, the two second mirrors 27 are freely movable by the moving mechanism 27m. Thereby, in the laser processing apparatus 100, the optical path length of the 2nd branched optical path P2 can be adjusted suitably.

The third half-wavelength plate 22c and the third polarization beam splitter 23c are provided to be capable of adjusting the amount of light of the second branched light LB2. Specifically, when the third 1/2 wavelength plate 22c is not present, the second branched light LB2 emitted as the S-polarized light from the first polarization beam splitter 23a is reflected by the third polarization beam splitter 23c by the reflection efficiency. . On the other hand, when the third 1/2 wavelength plate 22c is provided as described above, the degree of polarization can be adjusted by the third 1/2 wavelength plate 22c, so that the third polarization beam splitter 23c can be adjusted. The ratio of the S-polarized light of the second branched light LB2. Thereby, as a result, the amount of light of the second branched light LB2 can be adjusted.

Further, in the case shown in FIG. 5, the first position adjustment lens 24a as a concave lens and the second adjustment lens 24b as a convex lens constitute a focus position adjustment lens 24. In the above-described case, the second branch light LB2 that is incident on the first adjustment lens 24a as the parallel light is a divergent light that is non-parallel light that is diffused around the optical axis as it goes forward, and is emitted from the first adjustment lens 24a. Out The second adjustment lens 24b adjusts the degree of diffusion around the optical axis, and reaches the fourth polarization beam splitter 23d in a state of non-parallel light.

The first branch optical path P1 and the second branched optical path P2 merge with the fourth polarization beam splitter 23d to form a common optical path P3. The illumination lens 25 is provided on the common optical path P3, and the stage 10 is located in front of the illumination lens 25.

The first branched light LB1 which is P-polarized light passing through the first branched optical path P1 passes through the fourth polarizing beam splitter 23d and travels along the common optical path P3, passes through the irradiation lens 25, and is irradiated onto the workpiece placed on the stage 10 S. Since the lens provided on the first branch optical path P1 and the common optical path P3 connected thereto is only the illumination lens, the first branch light LB1 is irradiated to the position by the position of the focal length of the illumination lens 25 at a focal position. On the workpiece S.

On the other hand, the second branched light LB2, which is the S-polarized light passing through the second branched optical path P2, is reflected by the fourth polarization beam splitter 23d and travels along the common optical path P3, passes through the irradiation lens 25, and is irradiated onto the stage 10; The workpiece S on it. In this case, since the second branch optical path P2 and the common optical path P3 connected thereto are provided with the lens group including the focus position adjustment lens 24 and the illumination lens 25, the second branched light LB2 is separated from the illumination lens 25. The position of the composite focal length of the lens group is the focus position and is irradiated onto the workpiece S.

According to the laser processing apparatus 100 having the above-described configuration, in general, the stage portion 10 on which the workpiece S is placed and fixed is appropriately moved, and the focus is irradiated to the workpiece S. The first branched light LB1 and the second branched light LB2 having different positions can perform various processing on the desired processing position of the workpiece S. A representative processing form is the simultaneous multifocal processing described above.

In other words, as the laser light source 21, it is possible to emit pulsed laser light having ultrashort pulse light having a pulse width of 100 psec or less, and the optical path lengths of the first branched optical path P1 and the second branched optical path P2 are equal. The position of the second reflecting mirror 27 is adjusted by the moving mechanism 27m, and the height position of the irradiation lens 25 and the arrangement position of the focus position adjusting lens 24 on the second branch optical path P2 are appropriately defined, whereby the first branch light LB1 is set. The laser processing device can be used in a laser processing apparatus in which the focus position of the second branched light LB2 is set inside the workpiece S, and the irradiation frequency of the pulsed laser light, the beam diameter, or the moving speed of the stage portion 10 is appropriately set. Simultaneous multifocal processing is preferably performed in 100. In this case, when the focus position adjustment lens 24 is disposed such that the combined focal length of the lens group including the focus position adjustment lens 24 and the illumination lens 25 is shorter than the focal length of the illumination lens 25, the first branch light LB1 becomes The first processing laser light LBα and the second branch light LB2 are the second processing laser light LBβ, and the simultaneous multifocal processing in the form shown in FIGS. 2 and 3( a ) can be performed.

<Modification>

The processing that can be performed in the laser processing apparatus 100 is not limited to the simultaneous multifocal processing described above. For example, it is also possible to perform processing using a laser light source 21 that emits pulsed laser light having a larger pulse width. Further, it is also possible to perform processing in the form of irradiating pulsed laser light under the condition that the irradiation position of each single pulse light is continuous. In addition, it is possible to perform processing in a state where the irradiation timing of the first processing laser light LBα and the second processing laser light LBβ is different by adjusting the optical path length of the second branched optical path P2.

Further, in the above laser processing apparatus, by branching the laser light LB0 Two of the first branched optical path P1 and the second branched optical path P2 are capable of irradiating the workpiece S with two pulsed laser beams having different focal positions. The laser processing apparatus may have the following configuration: by providing more branches The optical path and the combined focal lengths of the respective lens groups are different from each other, and the workpiece S can be irradiated with three or more pulsed laser beams having different focal positions.

10‧‧‧The Stage Department

10a‧‧‧Top surface of the stage

10m‧‧‧Mobile agencies

11a‧‧‧Weak strength section

20‧‧‧Optical system

21‧‧‧Laser light source

22‧‧‧1/2 wavelength plate

22a‧‧‧1st 1/2 wavelength plate

22b‧‧‧2nd 1/2 wavelength plate

22c‧‧‧3rd 1/2 wavelength plate

23‧‧‧Polarizing beam splitter

23a‧‧‧1st polarization beam splitter

23b‧‧‧2nd polarization beam splitter

23c‧‧‧3rd polarization beam splitter

24‧‧‧ Focus position adjustment lens

24a‧‧‧1st adjustment lens

24b‧‧‧2nd adjustment lens

25, LE‧‧‧ illumination lens

26‧‧‧1st mirror

27‧‧‧2nd mirror

27m‧‧‧Mobile agencies

100‧‧‧ Laser processing equipment

AR1‧‧‧ arrow

AX‧‧‧ optical axis

+a1, +a2, -a3‧‧‧ axis direction

C11a~C14a, C11b~C14b‧‧‧劈open/cleavage

F, Fα, Fβ‧‧‧ focus

L‧‧‧Processing line

LBα‧‧‧1st processing laser light

LBβ‧‧‧2nd processing laser light

LB, LB0‧‧‧ (pulse) laser light

LB1‧‧‧1st branch light

LB2‧‧‧2nd branch light

P0‧‧‧Light Road

P1‧‧‧1st branch light path

P2‧‧‧2nd branch light path

P3‧‧‧ shared light path

RE11, RE12, RE13, RE14‧‧‧ illuminated areas

S‧‧‧Processed objects

ST‧‧·Shutter

W11a~W11c, W12a~W12c‧‧‧ weak intensity part

Fig. 1 (a) to (e) are diagrams schematically showing a processing form of the splitting/cracking process.

Fig. 2 is a view schematically showing a state of simultaneous multifocal processing.

3(a) and 3(b) are diagrams showing the comparison of the pulsed laser light forward mode and the focus position in the simultaneous multifocal processing with the normal split/split processing.

4 is an SEM image of a divided single piece obtained by dividing a sapphire single crystal substrate obtained by simultaneous multifocal processing.

FIG. 5 is a view schematically showing the configuration of the laser processing apparatus 100.

10‧‧‧The Stage Department

10a‧‧‧Top surface of the stage

10m‧‧‧Mobile agencies

20‧‧‧Optical system

21‧‧‧Laser light source

22‧‧‧1/2 wavelength plate

22a‧‧‧1st 1/2 wavelength plate

22b‧‧‧2nd 1/2 wavelength plate

22c‧‧‧3rd 1/2 wavelength plate

23‧‧‧Polarizing beam splitter

23a‧‧‧1st polarization beam splitter

23b‧‧‧2nd polarization beam splitter

23c‧‧‧3rd polarization beam splitter

24‧‧‧ Focus position adjustment lens

24a‧‧‧1st adjustment lens

24b‧‧‧2nd adjustment lens

25‧‧‧Illumination lens

26‧‧‧1st mirror

27‧‧‧2nd mirror

27m‧‧‧Mobile agencies

100‧‧‧ Laser processing equipment

LBα‧‧‧1st processing laser light

LBβ‧‧‧2nd processing laser light

LB0‧‧‧(pulse) laser light

LB1‧‧‧1st branch light

LB2‧‧‧2nd branch light

P0‧‧‧Light Road

P1‧‧‧1st branch light path

P2‧‧‧2nd branch light path

P3‧‧‧ shared light path

S‧‧‧Processed objects

ST‧‧·Shutter

Claims (4)

A laser processing apparatus characterized in that it irradiates laser light to process a workpiece, and includes: a stage portion that fixes a workpiece; and an optical system that is fixed to the self-illuminating lens pair The workpiece of the stage portion is irradiated with pulsed laser light emitted from a laser light source; and the laser light source emits ultrashort pulse light having a pulse width of 1 to 50 psec as the pulsed laser light, and the optical system includes The pulsed laser light emitted from the laser light source is optically branched into a plurality of branching optical path branching units, and each of the plurality of branched optical paths includes a lens group that includes the illumination lens in common but has a different combined focal length, thereby causing The plurality of branching optical paths are different in focus positions of the plurality of pulsed laser beams that are irradiated from the irradiation position by the illumination lens. The laser processing apparatus according to claim 1, wherein the branching unit branches the one-pulse laser light into the first and second branched optical paths, and the first branched optical path includes only the illumination lens as the lens group, and the first The branching optical path includes the lens group including the composite focal length different from the focal length of the illumination lens by the illumination lens and the at least one focus position adjustment lens, and the plurality of pulse lasers are The first optical path along the first optical path is set as the first pulsed laser light, and when the plurality of pulsed lasers are advanced along the second optical path as the second pulsed laser light, The first pulsed laser light is irradiated so that the position of the focal length of the illumination lens is set to be the focus position, and the second pulsed laser light is caused by the first pulsed laser light. Irradiation is performed such that the position where the focus position is different is the focus position. The laser processing apparatus of claim 2, wherein the focus position adjustment lens comprises at least one of a concave lens and a convex lens. The laser processing apparatus according to any one of claims 1 to 3, further comprising: an optical path length variable unit that changes an optical path length of at least one of the first or second branched optical paths.