JP5293791B2 - Laser processing apparatus and processing method of workpiece using laser processing apparatus - Google Patents

Description

  The present invention relates to a laser processing apparatus for processing a workpiece by irradiating laser light, and a processing method for the workpiece using the same.

  A laser scribing apparatus that forms a processing groove (scribe line) by irradiating a workpiece such as a semiconductor substrate with pulsed laser light (hereinafter referred to as laser light) is already known (see, for example, Patent Document 1). In the technique disclosed in Patent Document 1, a semiconductor substrate (LED substrate) on which an LED circuit pattern in which unit patterns each constituting an LED are two-dimensionally arranged is formed on the surface is an object to be processed. Specifically, the LED substrate is divided into LED chips by irradiating the laser light while relatively scanning along the planned division positions (called streets) set in a grid pattern according to the LED circuit pattern. A scribe line is formed.

  Further, the laser light emitted from the laser light source is branched into two kinds of laser lights having different polarization states by the first polarization beam splitter, and the intensity of both is individually adjusted by the half-wave plate, and then the second Also known is a laser processing apparatus that irradiates the two laser beams separately using a polarizing beam splitter (see, for example, Patent Document 2).

JP 2004-1114075 A JP 2010-284669 A

  When a scribe line is formed in a lattice pattern in a conventional laser processing apparatus as disclosed in Patent Document 1, the laser light is scanned in two orthogonal directions. This is, for example, a planned processing position while moving the stage in each of the XY directions with the LED substrate fixed on an XY stage that can move in two XY directions so that the street coincides with the moving direction of the stage. This is realized by irradiating laser light along the line.

  At this time, from the viewpoint of LED quality stability, it is preferable that the scribe lines are formed with the same processing accuracy in both XY directions. For this purpose, the beam profile of the laser beam (spatial distribution of the intensity of the laser beam) is used. Must be isotropic with respect to the irradiation direction or at least equivalent in both XY directions. However, since it is very expensive to realize such laser light irradiation, it is difficult to realize it simply by using a commercially available laser light source.

  Alternatively, after the scribe line is formed in one direction (first direction), the LED substrate is rotated 90 degrees in the horizontal plane, and the scribe line is formed in the second direction orthogonal to the first direction. Is also possible. In this case, the equivalence of the beam profile is not required, but the alignment of the LED substrate may be shifted by the rotation operation. Therefore, in order to ensure the processing accuracy, the alignment operation is performed again after the rotation, and the laser It is necessary to reset the light irradiation position. Therefore, there exists a problem that processing time is required.

  Further, the apparatus disclosed in Patent Document 2 is merely a device that can irradiate two types of laser beams separately in one processing progress direction, and cannot suppress variation in processing accuracy depending on the processing direction.

  The present invention has been made in view of the above problems, and even if the beam profile of the laser beam is not isotropic with respect to the irradiation direction, variation in processing accuracy when processing in two orthogonal directions is reduced. An object of the present invention is to provide a laser processing apparatus.

  In order to solve the above problems, the invention of claim 1 is a laser processing apparatus for processing a workpiece by irradiating a laser beam, a stage portion for fixing the workpiece, and a laser emitted from a laser light source. An optical system that irradiates light onto the workpiece fixed to the stage portion from a condenser lens, and the optical system converts the laser light emitted from the laser light source into first branched light. Branch means for branching to the second branch light, conversion means for rotating the beam profile of the second branch light by 90 ° about the traveling direction, and the second branch light passing through the first branch light and the conversion means An optical path commoning means for sharing an irradiation optical path to the condenser lens, and the first branched light and the second branched light are selectively selected between the branching means and the optical path commoning means. Selective to block Cutting means, and the first branched light that has passed through the optical path sharing means is used as the first irradiation laser light, and the second branched light that has passed through the sharing means is used as the second irradiation laser light. In addition, by switching the blocking of the first branched light and the second branched light by the selective blocking means, the workpiece fixed to the stage unit has the same beam profile and the orientation is One of the first irradiation laser beam and the second irradiation laser beam orthogonal to each other can be selectively irradiated.

  A second aspect of the present invention is the laser processing apparatus according to the first aspect, wherein the stage portion is movable in a first direction and a second direction orthogonal to each other, and is used for the first irradiation. The stage portion is moved in the first direction when the workpiece is irradiated with laser light, and the stage portion is moved to the second direction when the workpiece is irradiated with the second irradiation laser light. It is characterized by moving in the direction.

  A third aspect of the present invention is the laser processing apparatus according to the first or second aspect, wherein the conversion means is configured by combining a plurality of mirrors.

  A fourth aspect of the present invention is the laser processing apparatus according to the first or second aspect, wherein the converting means is constituted by a prism having a plurality of reflecting surfaces.

  Invention of Claim 5 is a processing method of the workpiece using the laser processing apparatus of Claim 2, Comprising: The fixing process which fixes the said workpiece to the said stage part, and setting to the said workpiece An alignment step of causing the extending directions of the grid-like processing target positions orthogonal to each other to match the first direction and the second direction, and moving the stage portion in the first direction. A first processing step of processing a processing target position extending in the first direction by irradiating the first irradiation laser beam; and the second irradiation laser light while moving the stage portion in the second direction. And a second machining step for machining a machining target position extending in the second direction.

  According to the first to fourth aspects of the present invention, there is realized a laser processing apparatus capable of performing processing by selectively using two types of laser beams having beam profiles having the same shape and orthogonal directions.

  In particular, according to the invention of claim 2, even when the beam profile of the laser beam emitted from the laser light source is not isotropic with respect to the processing direction, the processing accuracy varies when processing is performed in two orthogonal directions. A laser processing apparatus that can reduce the above is realized.

  According to the invention of claim 5, even if the beam profile of the laser light emitted from the laser light source is not isotropic, it is possible to perform processing in two orthogonal directions with the same processing accuracy. .

It is a perspective view which shows the structure of the laser processing apparatus 100 which concerns on this Embodiment. It is a figure which shows the state by which the 2nd optical path P2 was interrupted | blocked by the 2nd optical path shutter 24b while the 1st optical path shutter 24a was open | released. It is a figure showing the state where the 1st optical path P1 was intercepted by the 1st optical path shutter 24a, and the 2nd optical path shutter 24b was opened. 3 is a perspective view showing a configuration of a beam profile conversion unit 30. FIG. It is a top view of the stage part 10 in the state in which the irradiation laser beam LB3 is irradiated. 3 is a perspective view showing a beam profile conversion prism 130. FIG.

<Overview of laser processing equipment>
FIG. 1 is a perspective view showing a configuration of a laser processing apparatus 100 according to the present embodiment. The laser processing apparatus 100 is an apparatus that performs grooving or drilling on a workpiece by irradiating the workpiece with pulsed laser light (hereinafter referred to as laser light). As shown in FIG. 1, the laser processing apparatus 100 mainly includes a stage unit 10 and an optical system 20. The laser processing apparatus 100 also includes a control unit (not shown) that controls the operation of each unit.

  The stage unit 10 is a part where a workpiece is placed and fixed. The stage unit 10 mainly includes an X stage 11, a Y stage 12, a θ stage 13, and a suction chuck 14.

The X stage 11 is a moving mechanism provided to be movable in a first direction within a horizontal plane. The Y stage 12 is a moving mechanism that is provided on the X stage 11 and is movable in a second direction orthogonal to the first direction in the horizontal plane. The θ stage 13 is a rotation mechanism that is provided on the Y stage 12 and is rotatable in a horizontal plane. The movement operation of the X stage 11 and the Y stage 12 and the rotation operation of the θ stage 13 can be realized by a known drive mechanism (not shown).

  The suction chuck 14 is a table provided on the θ stage 13 for sucking and fixing a workpiece. The suction chuck 14 has a number of suction holes (not shown) on its upper surface 14s, and a negative pressure is applied to the suction holes by suction means (not shown) in a state where a workpiece is placed on the upper surface 14s. Thus, the workpiece can be adsorbed and fixed.

  In FIG. 1 and the subsequent figures, the movement direction (first direction) of the X stage 11 is the X-axis direction, the movement direction (second direction) of the Y stage 12 is the Y-axis direction, and the vertical direction is The right-handed XYZ coordinates in the Z-axis direction are attached.

  In the stage unit 10 having the above-described configuration, the workpiece is driven by driving the X stage 11, the Y stage 12, and the θ stage 13 while the workpiece is placed and fixed on the suction chuck 14. Can be moved horizontally in the XY2 axis direction or rotated in a horizontal plane.

  The optical system 20 is a part for irradiating a workpiece placed and fixed on the stage unit 10 with laser light. The optical system 20 includes a laser light source 21, two half-wave plates 22 (first half-wave plate 22a and second half-wave plate 22b), and two polarization beam splitters 23 (first Polarization beam splitter 23a, second polarization beam splitter 23b), two optical path shutters 24 (first optical path shutter 24a, second optical path shutter 24b), quarter wavelength plate 25, and condenser lens 26. And a first horizontal reflection mirror 27, a second horizontal reflection mirror 28, a vertical reflection mirror 29, and a beam profile conversion unit 30. Among these components, components other than the condenser lens 26 are arranged at predetermined positions on the arrangement table 20A provided above the stage unit 10.

The laser light source 21 emits linearly polarized laser light LB0. As the laser light source 21, various known light sources can be used. An appropriate light source may be selected and used according to the processing purpose. An embodiment using an Nd: YAG laser, an Nd: YVO ₄ laser, or other solid-state laser is preferable. The laser light source 21 preferably has a Q switch.

  For example, when a scribe line is formed at the street position of an LED substrate in which a sapphire single crystal substrate is used as a base substrate, it is preferable to use a third harmonic (wavelength: 355 nm) of an Nd: YAG laser. is there. In the present embodiment, the LED substrate refers to a semiconductor substrate on the surface of which an LED circuit pattern in which unit patterns each constituting an LED are two-dimensionally arranged is formed. This refers to the planned division position when the substrate is divided into individual LED chips (divided into individual pieces).

  The polarization direction of the laser beam LB0 emitted from the laser light source 21 is appropriately adjusted by the first half-wave plate 22a provided on the optical path P0.

  The laser beam LB0 that has passed through the first half-wave plate 22a reaches the first polarization beam splitter 23a provided on the optical path P0. In the first polarization beam splitter 23a, the laser light LB0 is branched into a first branched light LB1 traveling on the first optical path P1 and a second branched light LB2 traveling on the second 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, in the first polarization beam splitter 23a, the first branched light LB1 is emitted as P-polarized transmitted light, and the second branched light LB2 is emitted as S-polarized reflected light. In the case shown in FIG. 1, the laser beam LB0 emitted from the laser light source 21 in the negative Y-axis direction is transmitted through the first polarization beam splitter 23a as it is in the negative Y-axis direction and the first branched light LB1. Then, the light is branched to the second branched light LB2 reflected in the positive X-axis direction by the first polarization beam splitter 23a. As the first polarizing beam splitter 23a, one having a transmission efficiency of 90% to 95% and a reflection efficiency of about 99% is used. Thereby, the optical loss in the first polarizing beam splitter 23a is reduced to the minimum.

  On the first optical path P1, a first horizontal reflecting mirror 27, a first optical path shutter 24a, and a second half-wave plate 22b are provided. On the other hand, a beam profile conversion unit 30, a second horizontal reflection mirror 28, and a second optical path shutter 24b are provided on the second optical path P2.

When the first optical path P1 is not blocked by the first optical path shutter 24a (when the first optical path P1 is in the released state), the first branched light LB1 is reflected by the first horizontal reflection mirror 27. Then, after the traveling direction in the horizontal plane is appropriately changed , the light passes through the position of the first optical path shutter 24a and reaches the second half-wave plate 22b. By passing through the second half-wave plate 22b, the first branched light LB1 that was P-polarized light becomes S-polarized light. The first branched light LB1 that has become S-polarized light reaches the second polarizing beam splitter 23b. On the other hand, when the first optical path P1 is blocked by the first optical path shutter 24a, the first branched light LB1 that has reached the first optical path shutter 24a is directed to a beam diffuser (not shown) by the first optical path shutter 24a. And does not reach the second polarizing beam splitter 23b.

In addition, when the second optical path P2 is not blocked by the second optical path shutter 24b (when the second optical path P2 is in the released state), the second branched light LB2 passes through the beam profile conversion unit 30 and thereby has a beam profile. After being changed , the traveling direction in the horizontal plane is appropriately changed by being reflected by the second horizontal reflecting mirror 28, and then reaches the second polarization beam splitter 23b. The polarization direction of the second branched light beam LB2 that has reached the second polarization beam splitter is changed by passing through the beam profile conversion unit 30, and is changed from S-polarized light to P-polarized light. On the other hand, when the second optical path P2 is blocked by the second optical path shutter 24b, the second branched light LB2 that has reached the second optical path shutter 24b is directed to a beam diffuser (not shown) by the second optical path shutter 24b. And does not reach the second polarizing beam splitter 23b. In the present embodiment, the beam profile refers to a spatial distribution of the intensity of laser light with the traveling direction (optical path direction) as an axis. For convenience, the beam profile can be understood as an intensity distribution in an arbitrary cross section perpendicular to the traveling direction of the laser light.

  Although FIG. 1 shows a case where four first horizontal reflection mirrors 27 and one second horizontal reflection mirror 28 are provided, the first horizontal reflection mirror 27 and the second horizontal reflection mirror are shown. The number of 28 is not limited to this, and may be provided in an appropriate number and arrangement position according to the requirements on the arrangement layout of each element constituting the optical system 20.

  Further, FIG. 1 shows a state in which both are opened for convenience of explanation. However, the first optical path P1 is blocked by the first optical path shutter 24a, and the second optical path P2 is blocked by the second optical path shutter 24b. Is done exclusively. Therefore, when one is in a shut-off state, the other is always in a released state.

  FIG. 2 is a diagram illustrating a state where the first optical path shutter 24a is opened and the second optical path P2 is blocked by the second optical path shutter 24b. FIG. 3 is a diagram showing a state in which the first optical path shutter 24a is blocked by the first optical path shutter 24a while the second optical path shutter 24b is opened. In the case shown in FIG. 2, only the first branched light LB1 reaches the second polarization beam splitter 23b and proceeds further, and in the case shown in FIG. 3, only the second branched light LB2 is the second polarized light. It has reached the beam splitter 23b and is further advanced.

  More specifically, the second polarization beam splitter 23b emits the first branched light LB1 as reflected light toward the third optical path P3, and emits the second branched light LB2 as transmitted light toward the third optical path P3. To do. In other words, the second polarization beam splitter 23b functions as an optical path sharing unit that shares the optical paths of the first branched light LB1 and the second branched light LB2.

  In the case shown in FIGS. 1 to 3, the first branched light beam LB1 that travels straight in the negative Y-axis direction and enters the second polarizing beam splitter 23b is reflected in the negative X-axis direction by the second polarizing beam splitter 23b. The second branched light beam LB2 that travels straight in the negative X-axis direction and enters the second polarization beam splitter 23b is transmitted as it is in the negative X-axis direction. As the second polarizing beam splitter 23b, one having a transmission efficiency of 90% to 95% and a reflection efficiency of about 99% is used. Thereby, the optical loss in the second polarizing beam splitter 23b is reduced to the minimum.

  Hereinafter, the first branched light beam LB1 reflected by the second polarizing beam splitter 23b is referred to as a first irradiation laser beam LB3a, and the second branched light beam LB2 transmitted through the second polarizing beam splitter 23b is used for the second irradiation. This is referred to as laser beam LB3b, and both are collectively referred to as irradiation laser beam LB3.

  The irradiating laser beam LB3 is circularly polarized by the quarter wavelength plate 25 provided on the optical path P3, and then vertically downward (Z-axis negative direction) by the vertical reflecting mirror 29 also provided on the optical path P3. ) Is reflected toward. The reflected laser beam for irradiation LB3 passes through the through hole 20B provided in the arrangement table 20A, and is then condensed by the condenser lens 26 arranged on the optical path P3 and immediately below the through hole 20B. In addition, the workpiece is irradiated and fixed on the stage unit 10 (on the suction chuck 14) while the irradiation direction is maintained in the vertical direction. More specifically, either the first irradiation laser beam LB3a or the second irradiation laser beam LB3b is selectively irradiated according to the open / cut-off state of the first optical path shutter 24a and the second optical path shutter 24b. Is done. The focusing lens 26 is provided with a focusing adjustment mechanism (not shown) that can adjust the focusing state of the irradiation laser beam LB3 by moving the condenser lens 26 in the Z-axis direction. By the action of the focus adjustment mechanism, the focus position of the irradiation laser beam LB3 is adjusted to the workpiece surface, or a defocus state in which the focus position is intentionally set inside the workpiece is realized. It becomes possible.

  In laser processing apparatus 100 having the above-described configuration, generally, irradiation with irradiation laser beam LB3 and movement with X stage 11, Y stage 12, and θ stage 13 provided in stage unit 10 are appropriately combined. Thus, it is possible to perform processing on a desired processing position of the workpiece. For example, in the case of forming a scribe line on the street of the LED substrate, the X stage 11 or the Y stage 12 is moved in a state where the extending directions of the streets arranged in a lattice form coincide with the XY both axis directions. This is realized by irradiating the street position with the irradiation laser beam LB3.

  In the laser processing apparatus 100, either the first irradiation laser beam LB3a or the second irradiation laser beam LB3b is selected according to the open / cut-off state of the first optical path shutter 24a and the second optical path shutter 24b. Selectively irradiated. This will be described in detail next.

<Relationship between laser beam profile and selective irradiation>
First, the beam profile conversion unit 30 that generates a difference in beam profile between the first irradiation laser beam LB3a and the second irradiation laser beam LB3b will be described.

  In the laser processing apparatus 100 according to the present embodiment, the laser light LB0 emitted from the laser light source 21 is branched into the first branched light LB1 and the second branched light LB2 in the first polarization beam splitter 23a, and the second Only the second branched light LB2 traveling along the optical path P2 passes through the beam profile conversion unit 30.

  FIG. 4 is a perspective view showing the configuration of the beam profile conversion unit 30. The beam profile conversion unit 30 is a component of the laser processing apparatus 100 that converts the beam profile of the emitted laser light (emitted light) into a beam profile different from the beam profile of the incident laser light (incident light).

  The beam profile conversion unit 30 includes a first mirror 31 that reflects laser light LB (incident light LBα) incident in the horizontal direction (X-axis positive direction in FIG. 4) from the outside vertically upward (Z-axis positive direction); A second mirror 32 that reflects the laser beam LB reflected by the first mirror 31 in a horizontal plane and perpendicular to the direction of incidence on the first mirror 31 (the Y-axis negative direction in FIG. 4); A third mirror 33 that reflects the laser beam LB reflected by the mirror 32 vertically downward (Z-axis negative direction), and a laser beam LB that is reflected by the third mirror 33 in the horizontal plane from the second mirror 32. A mirror group including four mirrors including a fourth mirror 34 that reflects in a direction parallel to the reflected light (Y-axis negative direction in FIG. 4) is provided. The laser light LB reflected by the fourth mirror 34 becomes the outgoing light LBβ emitted to the outside.

  Note that the beam profile conversion unit 30 illustrated in FIG. 4 includes a casing 35 that stores a group of mirrors, and incident light LBα from the outside passes through an incident hole 35A provided in the casing 35 and is first. The emitted light LBβ, which is irradiated onto the mirror 31 and reflected from the fourth mirror, is emitted to the outside through the emission hole 35B provided in the housing 35. The beam profile conversion unit 30 It is not an essential aspect that the housing 35 is provided.

  In the beam profile conversion unit 30 having the above-described configuration, the incident laser beam LB is sequentially reflected by the mirror group, so that the beam profile of the incident beam LBα is rotated by 90 ° about the traveling direction. Is emitted.

  For example, in the case shown in FIG. 4, the beam profile of the incident light LBα has a longitudinal direction in the Y-axis direction, which is one direction in the horizontal plane, as indicated by an arrow AR1, but the beam profile of the emitted light LBβ is an arrow. As indicated by AR2, it has a longitudinal direction in the Z-axis direction. That is, the beam profile of the incident light LBα and the beam profile of the outgoing light LBβ are orthogonal when viewed in the traveling direction.

  In the laser processing apparatus 100, since the beam profile conversion unit 30 is provided on the second optical path P2, the beam profile of the second branched light LB2 is rotated by 90 ° about the traveling direction by the beam profile conversion unit 30. It will be. Since only the second horizontal reflection mirror 28 and the second optical path shutter 24b are provided between the beam profile conversion unit 30 and the second polarization beam splitter 23b in the second optical path P2, the beam profile conversion unit 30 is provided. Thus, the beam profile of the second branched light beam LB2 emitted in the horizontal plane is maintained until it reaches the second polarization beam splitter 23b.

  On the other hand, since the first optical path P1 only includes the first horizontal reflection mirror 27 and the first optical path shutter 24a, the beam profile of the first branched light LB1 traveling along the first optical path P1 is the first From the polarizing beam splitter 23a to the second polarizing beam splitter 23b.

  Therefore, also in the first branched light beam LB1 and the second branched light beam LB2 incident on the second polarizing beam splitter 23b, the beam profiles of each other are rotated by 90 ° about the traveling direction as in the case shown in FIG. (The beam profile matches if rotated 90 °). This is called that both beam profiles are orthogonal or in an orthogonal relationship. Since the first branched light beam LB1 and the second branched light beam LB2 are originally branched from the laser beam LB0 emitted from the same laser light source 21, their beam profiles have different directions with respect to the axial direction. The same.

  A quarter-wave plate 25 and a vertical reflection mirror 29 are provided on the optical path P3 from the second polarizing beam splitter 23b to the stage unit 10, and the first irradiation laser beam LB3a which is the first branched light beam LB1 is provided. The second irradiating laser beam LB3b, which is the second branched light beam LB2, passes through the second polarizing beam splitter 23b and is then circularly polarized by the quarter-wave plate 25 and then reflected by the vertical reflecting mirror 29. Is done. For this reason, the traveling directions of the first irradiation laser beam LB3a and the second irradiation laser beam LB3b themselves change, but the beam profiles of both the beams remain orthogonal after being reflected by the vertical reflection mirror 29.

  As described above, the first irradiation laser beam LB3a and the second irradiation laser beam LB3b are selectively covered depending on which of the first optical path shutter 24a and the second optical path shutter 24b is opened / closed. Since the workpiece is irradiated, after all, in the laser processing apparatus 100, the first irradiation laser beam LB3b and the second irradiation laser beam LB3b which have the same shape but are orthogonal to each other. Can be selectively irradiated to the workpiece.

  For example, FIG. 2 and FIG. 3 show the first irradiation on the workpiece when the beam profile of the laser beam LB0 emitted from the laser light source 21 in the negative Y-axis direction has the longitudinal direction in the X-axis direction. The difference in beam profile between the irradiation laser beam LB3a and the second irradiation laser beam LB3b is shown. As shown in FIG. 2, the first optical path shutter 24a is opened, while the second optical path P2 is blocked by the second optical path shutter 24b, the first irradiation laser beam LB3a irradiated to the workpiece. Has a longitudinal direction in the Y-axis direction. On the other hand, as shown in FIG. 3, the second optical path shutter 24b is opened while the first optical path shutter 24a is blocked by the first optical path shutter 24a. The light LB3b has a longitudinal direction in the X-axis direction.

<Street processing>
As described above, the laser processing apparatus 100 capable of selectively irradiating the two types of irradiation laser beams LB3 whose beam profiles are orthogonal to each other is street processing such as an LED substrate, that is, a square lattice pattern on the surface of the LED substrate. This is suitable for scribing in two orthogonal directions, as in the case where a scribe line is formed at a street position set in (1). Hereinafter, this point will be described.

  In FIG. 5, as shown in FIGS. 2 and 3, the irradiation laser beam LB3 is irradiated when the beam profile of the laser beam LB0 emitted from the laser light source 21 has a longitudinal direction in the X-axis direction. It is a top view of the stage part 10 in a state. Specifically, FIG. 5A is a top view of the stage unit 10 when the first irradiation laser beam LB3a is irradiated, and FIG. 5B is a diagram illustrating the second irradiation laser beam LB3b. It is a top view of the stage part 10 when being irradiated. However, in any case, the illustration of the LED substrate which is a workpiece is omitted. Moreover, the relationship of the size of each part differs from an actual thing. Actually, the width of the street is about several tens of μm, and the longitudinal size of the beam profile of the laser beam irradiated to the LED substrate is slightly smaller than or smaller than the width of the street. It is.

  As shown in FIG. 5A, the first irradiation laser beam LB3a is irradiated so that the beam profile has a longitudinal direction in the Y-axis direction. On the other hand, as shown in FIG. 5B, the second irradiation laser beam LB3b is irradiated such that the beam profile has a longitudinal direction in the X-axis direction. That is, both beam profiles have the same shape and are orthogonal. Therefore, the processing progress direction (relative scanning direction of the first irradiation laser beam LB3a with respect to the workpiece) when the first irradiation laser beam LB3a is irradiated and the second irradiation laser beam LB3b is irradiated. If the processing progress direction (the relative scanning direction of the second irradiation laser beam LB3b with respect to the workpiece) is orthogonal to each other when the processing is performed, the beam profile having the same shape can be seen in each processing progress direction. Processing is performed by a laser beam having

  In the present embodiment, a scribe line for the street position is formed using this relationship. Specifically, by adjusting (aligning) the arrangement position of the LED substrate sucked and fixed to the suction chuck 14 by a known method, the two extending directions of the streets arranged in a lattice shape are orthogonal to each other. After matching the axial direction, the X stage 11 is moved along the X-axis direction by moving the X stage 11 as indicated by an arrow AR3 while irradiating the first irradiation laser beam LB3a as shown in FIG. 5A. A scribe line is formed with respect to the street position. Similarly, as shown in FIG. 5B, the Y stage 12 is moved as indicated by an arrow AR4 while irradiating the second irradiation laser beam LB3b, thereby scribing the street position along the Y-axis direction. To form a line.

  In this way, the beam profile of the first irradiation laser beam LB3a viewed along the X-axis direction is the same as the beam profile of the second irradiation laser beam LB3b viewed along the Y-axis direction. As a result, the scribe lines in two orthogonal directions XY are formed with the same processing accuracy. In addition, in this case, the beam profile itself of the laser beam LB0 emitted from the laser light source 21 does not have to be isotropic, so the above-described processing does not necessarily guarantee the isotropicity of the beam profile. The laser processing apparatus 100 configured using a commercially available laser light source 21 that is not, can be suitably realized.

  Specific processing conditions in the case of performing street processing in such an embodiment may be appropriately determined within a range where a desired scribe line is formed. For example, if the LED substrate is formed using a sapphire single crystal base material, the wavelength of the laser beam LB0 preferably belongs to a wavelength range of 150 nm to 563 nm, and in particular, an Nd: YAG laser is used as the laser light source 21. In this case, it is preferable to use the third harmonic (wavelength: about 355 nm). At that time, the pulse repetition frequency is preferably 50 kHz to 150 kHz, and the pulse width is preferably 50 nsec to 150 nsec. The peak power is preferably 100 W or more and 500 W or less. The moving speed of the X stage 11 and the Y stage 12 is preferably 100 mm / sec or more and 300 mm / sec or less.

  The first irradiation laser beam LB3a and the second irradiation laser beam LB3b are circularly polarized by the quarter wavelength plate 25 and then irradiated to the workpiece, so that the polarization state Does not affect the machining accuracy.

  As described above, according to the present embodiment, a stage that is movable in two directions orthogonal to each other in a state where the workpiece is sucked and fixed is provided, and has a beam profile that has the same shape and an orthogonal direction. A laser processing apparatus capable of processing that selectively uses two types of laser beams is realized. According to such a laser processing apparatus, for example, when scribing is performed in two orthogonal directions, as in the case of forming a scribe line at a street position provided in a square lattice pattern on the surface of the LED substrate, the scribe line The beam profile of the laser beam emitted from the laser light source itself is not isotropic by determining the laser beam to be irradiated according to the moving direction after matching the forming direction of the stage and the moving direction of the stage part. In both cases, scribe lines in two orthogonal directions can be formed with the same processing accuracy. That is, variations in the processing accuracy of the scribe lines in two orthogonal directions are reduced.

<Modification>
As shown in FIG. 4, the beam profile conversion unit 30 according to the above-described embodiment is configured such that incident light and outgoing light travel in the same YX plane, and the incident direction and outgoing direction are different. Although configured to be orthogonal in the XY plane, these are not essential aspects. For example, in the case of the beam profile conversion unit 30 having the configuration in which the third mirror 33 and the fourth mirror 34 are omitted, although the height positions of the incident light and the outgoing light are different, the beam profiles of both are orthogonal in a plan view. become. Alternatively, in the case of the beam profile conversion unit 30 provided with the fifth mirror that reflects the reflected light from the fourth mirror 34 in the positive X-axis direction, the emission direction is the same as the incident direction. That is, the configuration of the beam profile conversion unit 30 may be appropriately determined according to the arrangement position of other components such as a horizontal reflection mirror.

  Moreover, in the above-mentioned embodiment, although the laser processing apparatus 100 demonstrated the aspect provided with the beam profile conversion unit 30 which consists of a mirror group on the 2nd optical path P2, the structure of a beam profile unit is restricted to this. Absent. FIG. 6 is a perspective view showing a beam profile conversion prism 130 that can be used in place of the beam profile conversion unit 30.

  In the beam profile conversion prism 130, the first reflection surface 131, the second reflection surface 132, the third reflection surface 133, and the fourth reflection surface 134 convert the beam profile to incident light and reflected light, respectively. The first mirror 31, the second mirror 32, the third mirror 33, and the second mirror 34 of the unit 30 are configured to have the same positional relationship. Also in the beam profile conversion prism 130, the incident laser beam LB is sequentially reflected by the mirror group, so that the output beam has a beam profile obtained by rotating the beam profile of the incident beam LBα by 90 ° about the traveling direction. LBβ is emitted.

  In the laser processing apparatus according to the above-described embodiment, the beam profile conversion unit rotates the profile direction of the second branched light beam LB2 by 90 °. However, various mirrors inside and outside the beam profile conversion unit are appropriately arranged. Accordingly, it is possible to realize a laser processing apparatus including a beam profile conversion unit that rotates the profile direction of the second branched light beam LB2 by 180 °. When such a laser processing apparatus is used, it is possible to perform forward processing and backward processing with different laser beams having the same beam profile in reciprocal processing in which a plurality of scribe lines are formed in parallel. As a result, in the reciprocating process, variations in machining accuracy in both reciprocating directions are reduced.

DESCRIPTION OF SYMBOLS 10 Stage part 11 X stage 12 Y stage 13 θ stage 14 Adsorption chuck 20 Optical system 20A Arrangement stand 20B Through hole 21 Laser light source 22 (22a, 22b) Wave plate 23 (23a, 23b) Polarizing beam splitter 24 (24a, 24b) Optical path shutter 25 Wave plate 26 Condensing lens 27, 28 Horizontal reflection mirror 29 Vertical reflection mirror 30 Beam profile conversion unit 100 Laser processing device 130 Beam profile conversion prism LBα (to beam profile conversion unit) Incident light LBβ (Beam profile conversion unit) Emission light LB0 Laser light (emitted from laser light source) LB1 First branched light LB2 Second branched light LB3 (LB3a, LB3b) Laser light for irradiation

Claims (5)

A laser processing apparatus for processing a workpiece by irradiating a laser beam,
A stage for fixing the workpiece;
An optical system for irradiating a laser beam emitted from a laser light source to a workpiece fixed to the stage unit from a condenser lens;
With
The optical system is
Branching means for branching the laser light emitted from the laser light source into first branched light and second branched light;
Conversion means for rotating the beam profile of the second branched light by 90 ° about the traveling direction;
Optical path sharing means for sharing an irradiation optical path from the first branched light and the second branched light that has passed through the converting means to the condenser lens;
Selective blocking means for selectively blocking the first branched light and the second branched light between the branching means and the optical path sharing means;
Have
When the first branched light that has passed through the optical path sharing means is the first irradiation laser light, and the second branched light that has passed through the sharing means is the second irradiation laser light,
By switching the blocking of the first branched light and the second branched light by the selective blocking means, the workpiece fixed to the stage unit has the same beam profile and the direction is orthogonal. Either of the first irradiation laser light and the second irradiation laser light can be selectively irradiated.
Laser processing equipment characterized by that. The laser processing apparatus according to claim 1,
The stage portion is movable in a first direction and a second direction orthogonal to each other;
When irradiating the workpiece with the first irradiation laser beam, the stage unit is moved in the first direction, and when irradiating the workpiece with the second irradiation laser beam, the stage unit. Moving in the second direction,
Laser processing equipment characterized by that. The laser processing apparatus according to claim 1 or 2,
The conversion means is configured by combining a plurality of mirrors.
Laser processing equipment characterized by that. The laser processing apparatus according to claim 1 or 2,
The converting means is constituted by a prism having a plurality of reflecting surfaces.
Laser processing equipment characterized by that. A processing method for a workpiece using the laser processing apparatus according to claim 2,
A fixing step of fixing the workpiece to the stage portion;
An alignment step of matching the extending directions perpendicular to each other of the lattice-shaped processing target positions set in the workpiece to the first direction and the second direction;
A first processing step of processing the processing target position extending in the first direction by irradiating the first irradiation laser beam while moving the stage portion in the first direction;
A second processing step of processing the processing target position extending in the second direction by irradiating the second irradiation laser beam while moving the stage portion in the second direction;
A processing method for a workpiece using a laser processing apparatus.

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