KR101425729B1 - Processing method of processed object and splitting method - Google Patents

Abstract

A problem to be solved by the present invention is to provide a machining method capable of generating a cleavage / deformation to a deep position inside a workpiece in the dividing of a workpiece, as compared with the conventional method.
An irradiation step of irradiating a plurality of pulsed laser beams having a pulse width of psec order from one collimating lens in an overlapping manner so that irradiated positions on the irradiated surface of each of the unit pulse lights become substantially the same spatially and temporally, And a scanning step of scanning a plurality of pulsed laser beams along a line to be machined under the condition that the irradiated positions are dispersed on the irradiated surface so that the respective focal positions of the plurality of laser beams are moved to different depth positions inside the workpiece Then, by performing the above process, the workpiece along the direction of the line to be machined is cleaved or opened at different depth positions of the workpiece, thereby forming a base point for dividing the workpiece.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a processing method and a dividing method,

The present invention relates to a processing method for processing a workpiece by irradiating a laser beam.

A laser beam of a short pulse having a pulse width of psec order is irradiated (hereinafter referred to simply as " laser processing ") as a technique of processing a workpiece by irradiating pulsed laser light (hereinafter simply referred to as laser beam) And then irradiating the upper surface of the workpiece while scanning the workpiece to scan the surface of the workpiece so that cleavage or cracking of the workpiece is sequentially generated between irradiated regions for each individual unit pulse light, A method of forming a starting point (division starting point) for division as a continuous surface of a surface is well known (see, for example, Patent Document 1).

In Patent Document 1, in the case where a workpiece on which a light emitting device structure such as an LED structure is formed on a substrate made of a light-curable and optically transparent material such as sapphire is divided into chips (divided pieces) Method is said to be particularly effective. The reason for this is that since the fine irregularities are formed on the cleavage / deformation face, the total reflectance at the position is reduced and the light extraction efficiency in the light emitting element can be improved.

Japanese Patent Application Laid-Open No. 2011-131256

In the case of forming a dividing base point on a workpiece, it is generally easier to divide the dividing base point as the dividing base point is formed. However, in the case of the method disclosed in Patent Document 1, since the cleavage / deformation occurs only near the surface of the workpiece, when the thickness of the workpiece increases, cleavage / deformation is caused to a deeper position to form a good division origin There is a problem that it becomes difficult. Even if the irradiation power of the laser beam or the irradiation energy per unit length of the scribe line is simply increased, the workpiece is damaged more than necessary, which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a machining method capable of generating a cleavage / deformation to a deep position inside a workpiece, as compared with the conventional method.

According to a first aspect of the present invention, there is provided a processing method for forming a dividing base point on a workpiece, comprising the steps of: applying a plurality of pulse laser beams, which are ultrarapillary pulses of a pulse width of psec order, Irradiating the plurality of pulsed laser beams from a single collimating lens disposed so as to oppose the workpiece in such a manner that the positions to be irradiated on the workpiece are spatially and temporally the same, A scanning step of scanning along the line to be machined under the discrete conditions on the irradiation surface is performed by setting the focal positions of the plurality of laser beams to different depth positions within the workpiece, To cause cleavage or deformation of the workpiece along the direction of the line to be machined at different depth positions of the workpiece, To form a starting point for division in the workpiece.

According to a second aspect of the present invention, there is provided a method of processing a workpiece according to the first aspect, wherein a plurality of branch lights generated by optically branching one pulse laser light emitted from one light source into a plurality of different branch light paths, And a lens group having a different focal length from each other is provided in each of the plurality of branching optical paths so as to include the one of the plurality of laser light sources, And the focal position of each of the plurality of pulsed laser beams irradiated to the plurality of pulsed laser beams is different.

According to a third aspect of the present invention, in the method of processing a workpiece according to the second aspect, the one pulsed laser light emitted from the one light source is optically branched into first and second branched optical paths, The first pulsed laser light is used as the first pulsed laser light and the lens group provided in the first branched optical path is made only the one used lens, By providing the lens group including the one focusing lens and the at least one focus position adjusting lens in the second branching optical path so that a position spaced by a focal distance of the lens becomes the focus position, The combined focal distance of the second pulsed laser light is set to a value different from the focal length of the tuning lens, Wherein the focal point position a first pulse laser beam is characterized in that different from the focus position.

According to a fourth aspect of the invention, there is provided a method of processing a workpiece according to any one of the first to third aspects, wherein in the scanning step, the direction of the line to be machined is set in two different directions of cleavage or opening In the same direction.

According to a fifth aspect of the present invention, in the method of processing a workpiece according to any one of the first to third aspects, in the scanning step, the direction of the line to be processed coincides with the direction of cleavage or opening of the workpiece .

According to a sixth aspect of the present invention, in the method of processing a workpiece according to any one of the first to third aspects, in the scanning step, the direction of the line to be machined is set to be two different opening / In the second embodiment.

According to a seventh aspect of the present invention, a method for dividing a workpiece is characterized in that a workpiece on which a dividing base point is formed by the method according to any one of claims 1 to 3 is divided along the dividing base point.

According to the invention of Claims 1 to 7, occurrence of deterioration or scattering of the workpiece can be limited to a local one, and the cleavage or opening of the workpiece can be positively generated not only in the direction of the line to be processed but also in the depth direction, It is possible to form a division origin point with respect to the workpiece at an extremely high speed.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing a machining mode by a clevis / opening process; Fig.
Fig. 2 is a view schematically showing a state of simultaneous multi-focus processing; Fig.
Fig. 3 is a view showing the progressing method and focal position of pulsed laser light in simultaneous multi-focus processing, in comparison with normal cleavage / deformation processing. Fig.
Fig. 4 is an SEM image of a split specimen obtained by dividing a sapphire single crystal substrate subjected to simultaneous multiple focus processing. Fig.
5 is a diagram schematically showing the configuration of a laser machining apparatus 100;

<Basic principle of processing>

The basic principle of processing realized in the embodiment of the present invention is similar to the principle of processing disclosed in Patent Document 1. [ Therefore, only the outline will be described below. The processing to be carried out in the present invention is roughly performed by irradiating the top surface (work surface) of the workpiece while scanning the pulsed laser light (hereinafter simply referred to as laser light) And a starting point (division starting point) for dividing is formed as a continuous surface of the cleavage surface or the opening surface formed in each of them.

In the present embodiment, the term "tearing" refers to a phenomenon that the workpiece is cracked approximately regularly along a crystal plane other than the cleaved plane, and the crystal plane is referred to as a "cracking plane". Further, in addition to microscopic phenomena completely cleaving the crystal plane, cleavage or cracking, macroscopic cracking may occur along a nearly constant crystal orientation. Depending on the material, only the cleavage, the crack or the crack may occur. However, in order to avoid the complicated explanation, the cleavage, the crack and the crack are collectively referred to as the cleavage / crack. In addition, the above-described processing may be referred to as simply cleavage / opening processing.

In the following description, it is assumed that the workpiece is a hexagonal single crystal material, and the directions of axes of the a1 axis, the a2 axis and the a3 axis, which are symmetrical with each other at an angle of 120 deg. , And the line to be machined is perpendicular to any one of the a1 axis direction, the a2 axis direction, and the a3 axis direction. More generally, this is the case in which the directions that are equivalent to the two different cleavage / opening direction directions (the direction that is the symmetry axis of the two cleavage / opening direction) are the direction of the intended processing line. In the following description, the laser light irradiated for each individual pulse is referred to as a unit pulse light.

Fig. 1 is a diagram schematically showing a machining mode by cleavage / deformation processing. In Fig. 1, a case where the a1 axis direction and the line to be machined L are perpendicular to each other is illustrated. Fig. 1 (a) is a diagram showing a bearing relationship between the a1 axis direction, the a2 axis direction and the a3 axis direction and the line to be machined L in this case. Fig. 1 (b) shows a state in which the unit pulse light of the first pulse of laser light is irradiated to the irradiated region RE11 at the end of the line to be processed L. Fig.

In general, the irradiation of the unit pulse light gives a high energy to a very small region of the workpiece, and therefore, such irradiation is carried out in such a manner that the irradiation is performed in a range corresponding to the irradiated region of the unit pulse light (laser beam) Which causes degeneration, melting, evaporation, etc. of the material.

If the irradiation time of the unit pulse light and eventually the pulse width are set to be extremely short, the material present in the substantially central region of the irradiated region RE11, which is narrower than the spot size of the laser light, obtains kinetic energy from the irradiated laser light, And the impact or stress generated by the irradiation of the unit pulse light including the reaction force generated by the scattering in the direction perpendicular to the surface to be irradiated, In the direction of the a1 axis, the a2 axis direction, and the a3 axis direction which are the directions of the irradiation area, in particular, the cleaving / opening direction. As a result, there occurs a state in which minute cleavage or cracking occurs partially while keeping the contact state in the apparent state along the direction, or a thermal deformation is inherent even when cleavage or cracking does not occur. In other words, it can be said that the irradiation of the unit pulse light of the ultrahigh pulse acts as a driving force for forming a weakly strong portion having a substantially linear shape when viewed from the upper face facing the cleaving / opening direction.

In Fig. 1 (b), among the weak strength portions formed in the respective cleavage / opening direction directions, the weak strength portions W11a in the -a2 direction and the + a3 direction close to the extending direction of the line to be processed L And W12a are schematically shown by dashed arrows.

Subsequently, as shown in Fig. 1 (c), the unit pulse light of the second pulse of the laser beam is irradiated and is irradiated on the line to be processed L at a position spaced apart from the irradiated region RE11 by a predetermined distance When the irradiation region RE12 is formed, a weak intensity portion along the easy cleaving / opening direction is formed in the second pulse similarly to the first pulse. For example, a weak strength portion W11b is formed in the -a3 direction, a weak strength portion W12b is formed in the + a2 direction, a weak strength portion W12c is formed in the + a3 direction, and a weak strength portion W12b is formed in the- The portion W11c is formed.

However, at this point, the weak intensity portions W11a and W12a formed by the irradiation of the unit pulse light of the first pulse exist in the extending directions of the weak intensity portions W11b and W12b, respectively. That is, the extending directions of the weak intensity portions W11b and W12b are positions where the cleavage or deformation can occur (energy absorption rate is high) with energy smaller than other points. Therefore, in practice, when the irradiation of the unit pulse light of the second pulse is performed, the impact or stress generated at that time is propagated to the weak strength portion existing in the cleavage / Over the portion W11a, and from the weaker portion W12b to the weaker portion W12a, complete cleavage or deformation occurs almost at the moment of irradiation. Thereby, the cleavage / opening surfaces C11a and C11b shown in FIG. 1 (d) are formed. In addition, the cleavage / opening surfaces C11a and C11b can be formed to a depth of several micrometers to several tens of micrometers in a direction perpendicular to the view of the workpiece. Further, in the cleavage / cracking surfaces C11a and C11b, slipping occurs on the crystal face as a result of a strong impact or stress, and undulations are generated in the depth direction.

Then, as shown in Fig. 1 (e), by sequentially irradiating the irradiated regions RE11, RE12, RE13, RE14, ... with the unit pulse light by scanning the laser beam along the line to be processed L Cut planes C11a and C11b, C12a and C12b, C13a and C13b, C14a and C14b ... of the straight line shape as viewed in the drawing are to be cut by the impact or stress generated at the time of irradiation, As shown in FIG. It is the basic principle of the cleavage / opening process in the present embodiment that the cleavage / deformation face is formed continuously in this manner.

In other respects, thermal energy is applied by the irradiation of the unit pulse light, so that the surface layer portion of the workpiece is expanded, and on the outer side of each substantially central region of the irradiated regions RE11, RE12, RE13, RE14, / &Quot;, the tensile stress perpendicular to the openings C11a and C11b, C12a and C12b, C13a and C13b, C14a and C14b · · · · acts.

That is, in the case shown in Fig. 1, the plurality of irradiated regions discretely existing along the line to be processed L and the cleavage / Is to be divided along the line L to be machined. After the division starting point is formed, the workpiece can be divided into a shape substantially following the line to be machined L by performing division using a predetermined jig or apparatus.

1, the unit pulse light is irradiated so that the line to be processed is perpendicular to any of the a1 axis direction, the a2 axis direction, and the a3 axis direction. Instead, the unit pulse light may be irradiated so as to be parallel to any one of the a1 axis direction, the a2 axis direction, and the a3 axis direction, or the individual irradiated regions may be divided into two cleavage / The unit pulse light for forming the to-be-irradiated areas may be irradiated so as to be formed in a zigzag shape (zigzag shape) in a manner of alternately following the direction of easy opening.

In order to realize the cleavage / opening processing as described above, it is necessary to irradiate laser light having a short pulse width and a short pulse. 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.

<Simultaneous multi-focus processing>

In the present embodiment, division starting points are formed in the workpiece by simultaneous multi-focal processing in which the cleavage / opening processing of the above-mentioned principle is further developed. 2 is a diagram schematically showing a state of simultaneous multiple focus processing. Fig. 3 is a view showing the progressing method and the focal position of the pulsed laser beam in the simultaneous multiple focus processing, in comparison with the normal cleavage / deformation processing according to the above-described processing principle. 3 (a) shows a state of simultaneous multiple focus processing, and Fig. 3 (b) shows a state of a normal cleavage / deformation processing in which only a single pulse laser beam LB is irradiated.

In the present embodiment, the simultaneous multi-focal processing is roughly referred to as a method in which a plurality of pulsed laser beams are irradiated so that the positions to be irradiated on the surface to be irradiated with each unit pulse light are spatially and temporally the same, Scanning is performed along the line to be machined under the condition that the irradiated position is dispersed on the irradiated surface while being superimposedly irradiated from the calibration lens so that the focal position is at a different depth position inside the workpiece, In the form of a cleavage / deformation along the direction of the line to be processed.

In this embodiment, the irradiated position refers to the center position (target position) of the irradiated area of the unit pulse light on the irradiated surface of the workpiece. As a confirmation, in the simultaneous multi-focus processing, irradiation positions of the unit pulse light beams of the respective pulsed laser beams are the same, but the irradiated areas may be different.

The lens used is a lens which is disposed opposite to the surface to be processed (surface to be processed) of the workpiece, and is a source of direct emission of the pulsed laser light in the workpiece.

The reason that the irradiated positions of the unit pulse light on the irradiated surface are spatially and temporally the same means that the irradiating timings of all pulsed laser beams are the same for each irradiated position along the workpiece and the line to be processed .

According to the simultaneous multi-focus processing, by appropriately setting the distance from the tuning lens to the focus position of each pulsed laser light, a large cleavage / degeneracy plane formed by the respective cleavage / do. That is, as compared with the case of irradiating only a single pulse laser beam, it is possible to form a dividing origin at a deeper position.

Note that the focal position in the present embodiment does not always mean a position spaced from the photographing lens by the focal distance. Since the focal length is a value unique to a lens or a lens group, and usually only one focal point exists on one side of the lens, a plurality of focal positions on one side of one lens can not be conceived with respect to one irradiation lens . The details of this embodiment will be described later. In the case of this embodiment, however, a plurality of groups of lenses having different configurations are used while using a common use lens, and the respective combined focal distances are made different, State. In this case, for the sake of convenience, it is assumed that a lens group including only the tuning lens constitutes a lens group, and in that case, the focal length of the tuning lens is regarded as a combined focal length.

Figs. 2 and 3 (a) show a case where two pulsed laser beams having different focus positions are superimposed on one another as a typical example of simultaneous multiple focus processing. More specifically, Figs. 2 and 3 (a) show, as an example of an irradiation form of pulsed laser light during simultaneous multiple focal processing, the optical axis AX is common, while the distance from the focusing lens LE to the focal position In the depth direction (thickness direction) of the workpiece S, the first processing laser beam LB? And the second processing laser beam LB? Are made to coincide with the irradiation timing of each unit pulse light and the irradiation position on the surface to be irradiated And scanning relative to the workpiece S such that the irradiated positions are dispersed along the line to be machined is exemplified.

More specifically, in Figs. 2 and 3A, the focal point F alpha of the first processing laser beam LB alpha incident on the controlling lens LE as parallel light is used as converging light, which is a kind of non-parallel light, Is located deeper than the focal point F? Of the second processing laser beam LB? Incident on the lens LE.

In the present embodiment, the parallel light means that the beam diameter of the laser light is not substantially changed (intentionally not changed) in the direction of the optical axis. On the other hand, a laser beam whose beam diameter changes in the optical axis direction 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 Figs. 2 and 3 (a), the cleavage / deformation due to the unit pulse light of the first processing laser beam LBa occurs at and near the depth position of the focal point F alpha, , The second processing laser beam LB? Is cleaved / opened by the unit pulse light. As shown by the arrow AR1 in Fig. 2, when the first processing laser beam LB? And the second processing laser beam LB? Are moved relative to the workpiece S while maintaining the overlapping state, the cleavage / This is continued not only in the relative movement direction but also in the depth direction, and consequently, a cleavage / deformation face having a large spread in the depth direction is formed.

In the usual case of irradiating only the single pulsed laser light LB shown in Fig. 3 (b), it is necessary to determine the position of the focal point F so that cleavage / In the case of the simultaneous multi-focal processing shown in Figs. 2A and 2B and Figs. 3A and 3B, in the vicinity of the surface of the workpiece, the second processing laser beam LBβ is irradiated to cause cleavage / The cleavage / deformation face directly formed by the irradiation need not reach the surface of the workpiece.

Therefore, in the case of the simultaneous multiple focus processing, the position of the focal point F alpha of the first processing laser beam LB alpha is set at a position deeper than the position of the focal point F in the case of performing the cleavage / opening processing by irradiating a single pulse laser beam LB .

In the case where two pulsed laser beams are superimposed to perform simultaneous multiple focus processing, the focal position of each laser beam is set so as to be closer to the target surface 2, the second processing laser beam LB?) Is about 4 to 45 占 퐉, and the second processing laser beam LB? From the surface to be irradiated (the first processing laser beam LB? In Fig. 2) is about 16 to 60 占 퐉.

There are various types of methods for giving each pulse laser light in the simultaneous multiple focus processing. As a suitable example of such a method, pulse laser light emitted from one emission source is optically branched in two directions, And the two types of lens groups are different from each other so that both pulse laser beams are superimposed. In this case, it is easy to make the irradiation timings of the unit pulse light of each pulse laser light substantially equal to the irradiated surface.

Alternatively, a plurality of pulsed laser beams having different focus positions may be generated by devising the configuration of the tuning lens itself instead of branching as such.

The irradiation pitch of the unit pulse light (center distance of the irradiated position) in the case of performing simultaneous multiple focus processing may be set in the range of 3 탆 to 50 탆. If the irradiation pitch is larger than this, the formation of the weak strength portion in the cleavage / opening direction may not progress to such an extent that cleavage / deformation can be formed. Therefore, the cleavage / It is not preferable from the viewpoint of forming the division starting point reliably. It is preferable that the irradiation pitch is larger in terms of the scanning speed, the processing efficiency and the product quality. In order to make the formation of the cleavage / deformation face more reliable, it is preferably set in the range of 3 탆 to 30 탆, Mu] m to 20 [mu] m.

When the repetition frequency of the laser light is R (kHz), the unit pulse light is generated from the laser light source every 1 / R (msec). When the laser beam moves relative to the workpiece at a speed V (mm / sec), the irradiation pitch DELTA (mu m) is determined as DELTA = V / R. Therefore, the scanning speed V and the repetition frequency of the laser beam are set so that? Is about several micrometers. For example, it is preferable that the scanning speed V is about 50 mm / sec to 3000 mm / sec, and the repetition frequency R is about 1 kHz to 200 kHz, particularly about 10 kHz to 200 kHz. The specific values of V and R may be appropriately determined in consideration of the material, the water absorption rate, the thermal conductivity, the melting point, and the like of the workpiece.

It is preferable that the laser beam is irradiated with a beam diameter of about 1 탆 to 10 탆. However, the beam diameters of the overlapping laser beams may be different.

The irradiation energy (pulse energy) of each laser beam may be appropriately determined within a range of 0.1 μJ to 50 μJ. However, in the present embodiment, it is possible to carry out sufficiently satisfactory processing in the range of 0.1 μJ to 10 μJ.

4 is an SEM (scanning electron microscope) image of a divided piece obtained by performing simultaneous multiple focal processing with two pulsed laser beams on a sapphire single crystal substrate, and dividing the substrate along the cleavage / open face formed thereby. More specifically, FIG. 4 is an SEM image of the vicinity of the intersection of the upper surface (the surface to be processed of the workpiece) of the divided piece and the dividing surface including the cleavage / dehiscence surface. In the figure, approximately one third of the upper side is the upper surface, and the other is the divided surface. In the simultaneous multiple focus processing, the focal position of each pulse laser beam is set to 6 mu m in the side closer to the surface to be irradiated, 16 mu m in the farther side from the irradiated surface, and the irradiation pitch of the unit pulse light Center interval) is set to 10 mu m.

According to Fig. 4, there are wedge-shaped regions extending in the vertical direction and striped portions in which a plurality of lines are formed in an oblique direction, which are substantially symmetrical on the left and right, at a portion far from the surface to be irradiated. The former is a region irradiated with the unit pulse light. The latter is a cleavage / deformation face, but the stripe-shaped portion is a minute irregularity having a height difference of about 0.1 mu m to 1 mu m. When a pulsed laser beam is irradiated, a strong impact or stress acts on the workpiece, .

4 shows that the irradiation pitch of the unit pulse light was 10 占 퐉. By referring to this, it can be seen that the maximum depth of the cleavage / deformation face is around 33 占 퐉. Since the maximum depth of the cleavage / opening face (the depth of the dividing origin) in the normal cleavage / opening process is only about 12 占 퐉, by performing simultaneous multiple focus processing, Can be formed. Therefore, by performing simultaneous multi-focal processing and then performing division, it becomes possible to divide the workpiece with higher accuracy.

As described above, in the present embodiment, by performing the simultaneous multiple focus processing in which the above-mentioned cleavage / deformation processing is further developed, the occurrence of deterioration or scattering of the workpiece is left as a local one, Is generated not only in the direction of the line to be machined but also in the depth direction, it is possible to form a dividing origin point at the extremely high speed as compared with the conventional one.

<Outline of Laser Processing Apparatus>

5 is a diagram schematically showing a configuration of a laser machining apparatus 100 capable of realizing simultaneous multiple focus machining according to the present embodiment. The laser machining apparatus 100 is not limited to simultaneous multiple focus machining, and it is also possible to perform groove machining, punch machining, or the like on the workpiece by appropriately changing the irradiation form of the optical system or the pulse laser beam. As shown in Fig. 5, the laser machining apparatus 100 mainly includes a stage unit 10 and an optical system 20. As shown in Fig. The laser machining apparatus 100 also includes a control unit (not shown) for controlling the operation of each unit.

The stage portion 10 is a portion where the workpiece S is mounted and fixed. The stage unit 10 includes an adsorption mechanism (not shown) and can adsorb and fix the workpiece S placed on the upper surface 10a of the stage unit 10. The stage unit 10 is provided with a moving mechanism 10m. By the action of the moving mechanism 10m, horizontal movement in two orthogonal directions and rotational movement in a horizontal plane are enabled.

The optical system 20 is a portion for irradiating the workpiece S mounted and fixed on the stage portion 10 with laser light. The optical system 20 includes a laser light source 21 and three half wave plates 22 (first half wave plate 22a, second half wave plate 22b, (The first polarizing beam splitter 23c and the second polarizing beam splitter 23c) and the four polarizing beam splitters 23 (the first polarizing beam splitter 23a, the second polarizing beam splitter 23b, the third polarizing beam splitter 23c, (The first adjusting lens 24a, the second adjusting lens 24b), and the adjusting lens 25, as shown in Fig.

The laser light source 21 emits laser light LB0, which is linearly polarized light and parallel light. As the laser light source 21, various known light sources can be used. An appropriate light source may be selected and used depending on the processing purpose. Nd: YAG lasers, Nd: YVO ₄ lasers or other solid state lasers are suitable. A shutter ST is attached to the laser light source 21.

For example, in the case where a sapphire single crystal substrate forms a scribe line at a street position of an LED substrate used as a base substrate, it is suitable to use a psec laser. In the present embodiment, the LED substrate refers to a semiconductor substrate on which an LED circuit pattern, in which unit patterns constituting LEDs are two-dimensionally arranged, is formed on the surface, Refers to a predetermined division position at the time of dividing (individualizing) into individual LED chips.

The laser light LB0 emitted from the laser light source 21 with the shutter ST opened is reflected by the first 1/2 wave plate 22a provided on the optical path P0 and the degree of polarization thereof And S polarized light) is appropriately adjusted.

The laser light LB0 passed through the first 1/2 wave plate 22a reaches the first polarization beam splitter 23a provided on the optical path P0. In the first polarizing beam splitter 23a, the laser light LB0 is incident on the first polarized beam splitter 23a through the first branched light LB1 traveling in the first branched optical path P1 and the second branched light LB2 propagating through the second branched optical path P2 Branching to the second branch light LB2. In other words, the first polarization beam splitter 23a functions as a branching means for branching the laser light LB0 into the first branched light LB1 and the second branched light LB2.

More specifically, the first polarized beam splitter 23a emits the first branched light LB1 as P-polarized transmitted light and the second branched light LB2 as S-polarized reflected light. The polarizing beam splitter 23 including the first polarizing beam splitter 23a has a transmission efficiency of 90% to 95% and a reflection efficiency of about 99%. Thereby, the optical loss in the polarization beam splitter 23 is reduced to a minimum.

The first branch light path P1 and the second branch light path P2 are branched from the first reflecting mirror 26 or the second reflecting mirror 27 installed in the middle of the first branch light path P1 and the second branch light path P2, (LB2) is reflected, so that the respective directions are appropriately changed.

5, the first reflection mirror 26 and the second reflection mirror 27 are disposed in a posture that reflects the pulsed laser light only in the plane of the drawing, but this is merely a matter of convenience . The number of the first reflecting mirror 26 and the second reflecting mirror 27 is not limited to the example shown in Fig. That is, the first reflecting mirror 26 and the second reflecting mirror 27 are installed in an appropriate number, arrangement position and attitude in accordance with a request on the arrangement layout of each element constituting the optical system 20 and the like.

The first quarter wave plate P1 is provided with the second 1/2 wave plate 22b and the second polarization beam splitter 23b in this order in the direction in which the first quarter wave plate LB1 advances . The first branch light path P1 is configured so that the first branched light LB1 that is P-polarized light transmitted through the second polarized beam splitter 23b reaches the fourth polarized beam splitter 23d.

The second 1/2 wave plate 22b and the second polarized beam splitter 23b are provided to adjust the light quantity of the first branched light LB1. Specifically, in the case where the second 1/2 wave plate 22b does not exist, the first branched light LB1 emitted as the P polarized light from the first polarizing beam splitter 23a, Polarized beam splitter 23b. On the other hand, when the second 1/2 wave plate 22b is provided as described above, the degree of polarization of the second 1/2 wave plate 22b is adjusted so that the second polarizing beam splitter 23b is transmitted The ratio of the P-polarized light of the first branched light LB1 can be adjusted. As a result, the light quantity of the first branched light LB1 is adjusted as a result.

On the other hand, in the second branch optical path P2, the third 1/2 wave plate 22c, the third polarization beam splitter 23c, and the focus position adjusting lens 24 are arranged so as to form the second branch light LB2, In this order. Although the second branched light path P2 is simplified in FIG. 5, the second branched light LB2, which is the S-polarized light reflected by the third polarized beam splitter 23c, passes through the focus position adjusting lens 24 And is configured to reach the fourth polarization beam splitter 23d.

In the second branch optical path P2, the two second reflecting mirrors 27 are made movable by the moving mechanism 27m. Thus, in the laser machining apparatus 100, the optical path length of the second branch optical path P2 can be appropriately adjusted.

The third 1/2 wave plate 22c and the third polarized beam splitter 23c are provided to adjust the light quantity of the second branched light LB2. Specifically, in the case where the third 1/2 wave plate 22c does not exist, the second branched light LB2 emitted as the S polarized light from the first polarizing beam splitter 23a, 3 polarization beam splitter 23c. On the other hand, when the third 1/2 wave plate 22c is provided as described above, the degree of polarization in the third 1/2 wave plate 22c is adjusted so that reflection from the third polarization beam splitter 23c It is possible to adjust the ratio of the S polarized light of the second branched light LB2 as much as possible. As a result, the light amount of the second branched light LB2 is adjusted as a result.

In the case shown in Fig. 5, the focus adjustment lens 24 is constituted by the first adjustment lens 24a, which is a concave lens, and the second adjustment lens 24b, which is a convex lens. In this case, the second branched light LB2 incident on the first adjusting lens 24a as parallel light is emitted from the first adjusting lens 24a as divergent light that is nonparallel light having a larger spread around the optical axis, The degree of spreading around the optical axis is adjusted by the second adjusting lens 24b and reaches the fourth polarization beam splitter 23d in the state of non-parallel light.

The first branch optical path P1 and the second branch optical path P2 join together in the fourth polarization beam splitter 23d to become the common optical path P3. The common optical path P3 is provided with a tuning lens 25 and the stage 10 is located at the end of the tuning lens 25. [

The first branched light LB1 that is P-polarized light via the first branch light path P1 travels through the fourth polarization beam splitter 23d to travel through the common optical path P3, And is irradiated onto the workpiece S loaded on the stage portion 10 via the above- Since the lens provided on the first branch optical path P1 and the common optical path P3 subsequent thereto is only the reference lens, the first branched light LB1 is separated from the collimating lens 25 by the focal distance Is irradiated onto the work (S) with the position as a focus position.

On the other hand, the second branched light LB2, which is the S-polarized light via the second branched light path P2, is reflected by the fourth polarization beam splitter 23d and travels through the common light path P3, To the workpiece S placed on the stage portion 10 via the workpiece W. At this time, since the lens group consisting of the focus position adjusting lens 24 and the tuning lens 25 is provided on the second branch optical path P2 and the common optical path P3 subsequent thereto, the second branch light LB2 Is irradiated onto the workpiece S from the adjusting lens 25 with a position separated by the combined focal distance of the lens group as the focal position.

According to the laser machining apparatus 100 having the above-described configuration, the stage section 10, on which the workpiece S is mounted and fixed, is appropriately moved while the first branching lights LB1 and LB2, Various processing can be performed on a desired machining position of the workpiece S by superimposing the light beam LB2 on the workpiece S in an overlapping manner. The representative processing type is the simultaneous multi-focal processing described above.

That is, it is possible to emit pulsed laser light, which is ultraraparated pulse light having a pulse width of 100 psec or less, as the laser light source 21 so that the optical path lengths of the first branch light path P1 and the second branch light path P2 become equal The position of the second reflecting mirror 27 is adjusted by the moving mechanism 27m so that the height position of the focusing lens 25 and the height position of the focus position adjusting lens 24 The focal positions of the first branched light LB1 and the second branched light LB2 are set in the interior of the workpiece S by appropriately determining the arrangement position and the repetition frequency of the pulsed laser light, 10 can appropriately be set in the laser processing apparatus 100, the simultaneous multiple focus processing can be appropriately performed. When the focus position adjusting lens 24 is arranged such that the combined focal length of the lens group consisting of the focus position adjusting lens 24 and the tuning lens 25 is shorter than the focal distance of the tuning lens 25 , The first branched light LB1 is the first processing laser beam LBα and the second branched light LB2 is the second processing laser beam LBβ, Concurrent multi-focus processing can be performed.

<Modifications>

The processing that can be performed in the laser processing apparatus 100 is not limited to the simultaneous multiple focus processing. For example, it is possible to perform processing using the laser light source 21 that emits pulsed laser light having a larger pulse width. It is also possible to process in the form of irradiating the pulsed laser light under the condition that the irradiating positions of the individual short pulse beams are continuous. Further, by adjusting the optical path length of the second branch optical path P2, it is possible to perform processing in a state in which the irradiation timings of the first processing laser beam LB? And the second processing laser beam LB? Are different.

Further, in the above-described laser machining apparatus, by branching the laser light LB0 into the first branch light path P1 and the second branch light path P2, It is possible to irradiate the laser beam S onto the workpiece S, but the laser beam machining apparatus is provided with more branch optical paths, and the combined focal distances of the respective lens groups are made different from each other, S may be irradiated.

10:
10m: Moving mechanism
11a: weak intensity portion
20: Optical system
21: Laser light source
22: 1/2 wave plate
23: polarizing beam splitter
24: Focusing position adjusting lens
25, LE: Lens for adjustment
26: first reflection mirror
27: a second reflection mirror
27m: mobile device
100: laser processing device
AX: optical axis
C11a to C14a, C11b to C14b: cleavage /
F, F ?, F?: Focus
L: Line to be processed
LB?: Laser beam for first processing
LB?: Second processing laser beam
LB, LB0: (pulse) laser light
LB1: 1st quarter light
LB2: second quarter light
P0: Optical path
P1: 1st quarter optical path
P2: second branch optical path
P3: Common optical path
RE11, RE12, RE13, RE14: irradiated region
S: Workpiece
ST: Shutter
W11a to W11c, W12a to W12c:

Claims (7)

A machining method for forming a dividing base point on a workpiece,
Which is obtained by optically branching one pulsed laser light emitted from one light source into first and second branched optical paths adjusted so that the optical path lengths become equal, Irradiating the two-pulse laser light superimposedly from a single lens used to face the surface to be processed of the workpiece so that the irradiation positions of the respective unit pulse lights are spatially and temporally the same,
And a scanning step of scanning the first and second pulsed laser lights along a line to be machined under the condition that the irradiated positions are dispersed on the irradiated surface,
Irradiating the first pulsed laser light such that the position of the first pulsed laser light is spaced apart from the one focusing lens by a focal distance of the focusing lens, Wherein a combined focal length of said lens group is set to a value different from said focal length of said lens for use by providing a lens group composed of a focus position adjusting lens of said first lens and said second lens, Of the workpiece along the direction of the line to be machined at different depth positions of the workpiece by performing the irradiation step and the scanning step in combination, , And thereby forming a starting point for dividing the workpiece . The method of processing a workpiece according to claim 1, wherein in the scanning step, the direction of the line to be processed is set to a direction equivalent to two different cleavage or easy opening directions of the workpiece. The method of processing a workpiece according to claim 1, wherein in the scanning step, the direction of the line to be machined is made coincident with the direction of cleavage or opening of the workpiece. The method of processing a workpiece according to claim 1, wherein in the scanning step, the direction of the line to be machined is alternately changed in two different directions of cleavage or opening of the workpiece. A method for dividing a workpiece by forming a dividing base point,
A machining method for forming a dividing base point in a workpiece according to any one of claims 1 to 4, characterized in that the workpiece is divided along the dividing base point formed by the machining method In which a division starting point is formed. delete delete

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