JP2014013833A - Laser beam reshaping device, laser beam reshaping method, laser processing device, and laser processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam reshaping device, laser beam reshaping method, laser processing device, and laser processing method capable of reducing interference to occur inside a wave guide for guiding laser beams and irradiating a processed object with a laser beam having a top flat intensity distribution.SOLUTION: A laser beam reshaping device includes: a laser beam division unit 3 for dividing a laser beam L0 into multiple laser beams L1-LN, giving optical path differences among the multiple laser beams L1-LN, and allowing the multiple laser beams to be the laser beams L1-LN having optical path differences mutually exceeding a spatial coherent length; an optical fiber 5 to which multiple laser beams L1-LN having optical path differences exceeding a spatial coherent length are guided and where the beam shapes of the laser beams are reshaped; and an irradiation optical system 6 for guiding a laser beam LS to be emitted from the optical fiber 5 in order to irradiate a processed object 10 with the laser beam.

Description

  The present invention relates to a laser light shaping apparatus and a laser light shaping method, and a laser processing apparatus and a laser processing method for performing predetermined processing by irradiating a workpiece with laser light.

  In a manufacturing process of a semiconductor device, a heat treatment for the purpose of activating impurities and recovering damage to crystals is performed on a semiconductor wafer into which impurities are introduced by ion implantation or the like. As such a heat treatment method, in addition to furnace annealing for heating a semiconductor wafer in a heating furnace, laser annealing for irradiating and heating the semiconductor wafer with laser light is known.

  In laser processing, such as laser annealing, which irradiates a target object with laser light, the laser light preferably has a top flat intensity distribution at an irradiation position on the target object. Since the laser beam has a top-flat intensity distribution, the laser beam can be uniformly applied to the object to be processed.

  For example, in Patent Document 1, as a method for forming a crystallized film that crystallizes a thin film with laser light, a laser light source that emits laser light as a light bundle having a predetermined divergence angle is formed of a plurality of cylindrical lenses. A first array lens, a second array lens composed of a plurality of cylindrical lenses, an optical path difference generating member having a plurality of block portions for providing an optical path difference, a condensing lens, and an irradiated surface are sequentially arranged, and laser light is emitted. What irradiates the surface to be irradiated is described. In this method, the laser light emitted from the laser light source is transmitted through the first array lens, and a plurality of reduced divided beams corresponding to the number of adjacent cylindrical lenses having the width of the first array lens are obtained. The divided light beams are individually transmitted through the corresponding cylindrical lenses of the second array lens to obtain a plurality of reduced divided light beams that are reduced to be narrower than the width of the cylindrical lenses of the first array lens. After that, each reduced divided beam is individually transmitted through the corresponding block portion of the optical path difference generating member while reducing reflection on the divided surface side, and an optical path difference is generated between the reduced divided beams so as to adjust coherency. After that, each reduced divided light beam is superimposed on the condensing lens to irradiate the irradiated surface. According to this method, it is possible to reduce the coherence by causing an optical path difference between the reduced divided light beams and to prevent interference between the reduced divided light beams, and to obtain a uniform top flat intensity distribution without interference fringes. The irradiated surface can be irradiated with a laser beam having

  Further, in Patent Document 2, as a method for reducing the coherence of a light beam such as a longitudinal multimode laser beam, a plurality of light beams oscillated at different wavelengths are branched into a plurality of light beams. Are described in which a plurality of light beams are converted into a single light flux or a collective light flux after giving a certain optical path length difference between them.

Japanese Patent No. 4291230 Japanese Patent Laid-Open No. 11-326827

  However, the conventional method described in Patent Document 1 has a problem that it is difficult to reduce the beam size of the laser light applied to the object to be processed, for example, to 1 mm square or less. That is, in the conventional method described in Patent Document 1, in order to reduce the beam size, it is necessary to reduce the array lens composed of a plurality of cylindrical lenses and the optical path difference generating member. It is not easy to manufacture these optical elements with a beam size that can be realized.

When irradiating the object to be processed with laser light, it is conceivable to guide the laser light through a waveguide such as an optical fiber or a kaleidoscope before irradiating the object to be processed with laser light. As a result, a beam having a desired flatness and shape can be obtained without requiring a special optical element. However, when a waveguide is used, there is a problem in that laser beams having different reflection angles overlap each other in the waveguide, interference occurs in the waveguide, and interference fringes are generated in the laser beam emitted from the waveguide. .
Moreover, although the conventional method described in the said patent document 2 can reduce the coherence of light beams, such as a laser beam, it is difficult to obtain intensity distribution of a top flat. A method for obtaining a top flat intensity distribution is not described for laser light.

  The present invention has been made against the background of the above circumstances, and has a laser beam shaping device, a laser beam shaping method, a laser processing device and a laser using the laser beam, which obtain a laser beam having little interference and a top-flat intensity distribution. An object is to provide a processing method.

That is, among the laser light shaping devices of the present invention, the first present invention is a device for shaping laser light irradiated for heat treatment of an object to be processed,
A laser beam splitting unit that splits the laser beam into a plurality of laser beams;
A laser beam optical path difference providing unit that provides an optical path difference between the plurality of laser beams, and a plurality of laser beams having optical path differences exceeding a spatial coherent length;
The plurality of laser beams having an optical path difference exceeding the spatial coherent length are guided, and a waveguide for shaping a beam shape of the laser beams is provided.

  The laser beam shaping apparatus according to a second aspect of the present invention is the light condensing device according to the first aspect of the present invention, wherein the plurality of laser beams extracted from the laser beam optical path difference providing unit are condensed and guided to one end of the waveguide. It has an optical system.

  In the laser beam shaping device according to a third aspect of the present invention, in the first or second aspect of the present invention, the laser beam splitting unit functions as a laser beam path difference applying unit that gives the optical path difference to the plurality of laser beams. It is characterized by having.

A laser beam shaping device according to a fourth aspect of the present invention is the laser beam shaping device according to any one of the first to third aspects, wherein the laser beam dividing section reflects a part of the laser beam and transmits the remaining portion. A reflective plate that reflects the laser light reflected on the transflective plate and disposed opposite to the reflective side of the transflective plate,
The semi-transmission plate and the reflection plate are arranged such that plate surfaces are inclined with respect to the optical path of the laser light before division, and a part of the plate surface of the semi-transmission plate is positioned on the optical path. It is characterized by.

  In the laser beam shaping apparatus of the fifth aspect of the present invention, in the fourth aspect of the present invention, the distance between the facing surfaces of the semi-transmissive plate and the reflective plate is d, and the incident angle of the laser beam to the semi-transmissive plate is θ. 2d · cos θ is set to a length exceeding the spatial coherent length.

  The laser beam shaping apparatus according to a sixth aspect of the present invention is characterized in that, in any of the first to fifth aspects of the present invention, the waveguide is an optical fiber or a kaleidoscope.

A laser processing apparatus according to a seventh aspect of the present invention is the laser light shaping apparatus according to any one of the first to sixth aspects,
And an irradiation optical system for guiding the laser beam emitted from the waveguide included in the laser beam shaping device to irradiate the object to be processed.

  The laser processing apparatus according to an eighth aspect of the present invention is the laser processing apparatus according to the seventh aspect, wherein the irradiation optical system continuously or intermittently changes the irradiation direction of the laser beam on the object to be processed. It has a scanning part which moves the irradiation position of the laser beam.

  According to a ninth aspect of the present invention, in the eighth aspect, the scanning unit includes a galvano mirror and an fθ lens.

  A laser beam shaping method according to a tenth aspect of the present invention is a method for shaping laser beam irradiated for heat treatment of an object to be processed, the laser beam being divided into a plurality of laser beams, An optical path difference exceeding a spatial coherent length is given to laser light, the plurality of laser lights to which the optical path difference is given are introduced into one end of a waveguide, and guided in the waveguide to cause the laser light to It is characterized by shaping the beam shape.

  A laser processing method according to an eleventh aspect of the present invention is characterized in that a laser beam shaped by the laser light shaping method according to the tenth aspect of the present invention is irradiated to a workpiece.

  A laser processing method according to a twelfth aspect of the present invention is characterized in that, in the eleventh aspect of the present invention, the object to be processed is irradiated while scanning with the laser light shaped by the laser light shaping method.

  According to the present invention, since a plurality of divided laser beams are introduced into one end of the waveguide with an optical path difference exceeding the spatial coherent length, the beam shape of the laser beam is shaped by the waveguide. At the same time, interference fringes generated at the other end of the waveguide from which the laser light is emitted can be sufficiently reduced. Therefore, a laser beam having a top flat intensity distribution with little interference can be obtained. By irradiating the target object with laser light having a top-flat intensity distribution, the target object can be subjected to uniform laser processing.

  In the laser processing in the present invention, the object to be processed is subjected to, for example, heat treatment by irradiating the object to be processed with laser light. The target object to be subjected to laser processing is not particularly limited, and examples of the target object include a semiconductor layer formed on a substrate such as a semiconductor wafer or a glass substrate. For example, the object to be processed can include Si wafers, SiC wafers and other semiconductor wafers into which impurities have been introduced by ion implantation or the like. In this case, laser processing is performed by irradiating the semiconductor wafer with laser light. Thus, the impurities introduced into the semiconductor wafer are activated.

  As the laser beam divided into a plurality of laser beams, a pulsed laser beam is used. However, the laser beam is not limited to this, and a continuous wave laser beam or a pulsed continuous wave laser beam is used. be able to. Further, the laser light source from which these laser beams are output is not particularly limited, and can be appropriately selected according to the content of the laser processing, and the laser oscillation medium is not limited. For example, as the laser light source, a solid laser, a semiconductor laser, a gas excitation laser, or the like can be used.

  The configuration of the laser beam splitting unit is not particularly limited as long as the laser beam can be split into a plurality of laser beams, and various beam splitters can be used. In addition, for example, a semi-transmissive plate that reflects a part of the laser light and transmits the remaining portion and a reflective plate that is disposed to face the reflective side of the semi-transmissive plate with an interval therebetween can be used. In this way, in the laser beam splitting unit having the semi-transmissive plate and the reflective plate, a plurality of reflections are performed by repeating the partial reflection and remaining transmission of the laser beam on the semi-transmissive plate and the reflection of the laser beam on the reflective plate. Laser light can be emitted from the transmission side of the semi-transmissive plate, and at this time, an optical path difference can be provided between the divided laser lights together with the division of the laser light.

The configuration of the laser beam path difference providing unit is not particularly limited as long as the laser beam path difference providing a plurality of laser beams with an optical path difference exceeding the spatial coherent length is provided. The laser beam optical path difference providing unit can provide the optical path difference by, for example, a plurality of laser beams passing through different optical paths or passing through different optical members. The laser beam path difference providing unit may have a function of only giving the laser beam optical path difference, or may be shared with the laser beam splitting unit. That is, a laser beam splitting unit that functions as a laser beam optical path difference providing unit may be used. A plurality of laser light path difference providing units may be provided, and finally a plurality of laser beams may be provided with optical path differences exceeding the spatial coherent length by a plurality of combinations.
The spatial coherent length can be defined as an optical path difference that can cause interference between two divided light beams.

  When the transflective plate and the reflective plate are used so as to be inclined in the optical path, the facing distance between the transflective plate and the reflective plate is d, and the incident angle of the laser light with respect to the transflective plate is θ. -Cos θ may be set to a length exceeding the spatial coherent length.

  In the waveguide, a plurality of laser beams having an optical path difference exceeding the spatial coherent length are guided, and the beam shape of the laser beam can be shaped according to the waveguide cross-sectional shape. As the waveguide, for example, an optical fiber, a kaleidoscope, or the like can be used, and these can be used in appropriate combination. The waveguide may have a predetermined waveguide cross-sectional shape according to the beam shape to be shaped, for example, a waveguide cross-sectional shape such as a square shape, a circular shape, or an elliptical shape. Can do.

  Note that a condensing optical system for condensing and guiding a plurality of laser lights extracted from the laser light optical path difference providing unit to one end of the waveguide can be provided for the laser light optical path difference providing unit. The condensing optical system is not particularly limited. For example, it may have a condensing lens.

The irradiation optical system guides the object to be irradiated with laser light emitted from the other end of the waveguide. The irradiation optical system can be appropriately selected according to the irradiation mode in which the object to be processed is irradiated with laser light.
For example, the irradiation optical system can include a scanning unit that moves the irradiation position of the laser light on the object to be processed by changing the irradiation direction of the laser light to the object to be processed continuously or intermittently. As the scanning unit, for example, a galvanometer mirror that continuously or intermittently changes the irradiation direction of the laser beam, and a laser beam whose irradiation direction has been changed by the galvanometer mirror moves at a constant speed while condensing on the object to be processed. And an fθ lens to be configured. The scanning unit can irradiate the object to be processed while scanning the laser beam emitted from the other end of the waveguide.

  As described above, according to the present invention, it is possible to reduce the interference of laser light in the waveguide and obtain laser light having a top flat intensity distribution.

It is the schematic which shows the laser processing apparatus of one Embodiment of this invention.

A laser processing apparatus including a laser beam shaping apparatus according to an embodiment of the present invention will be described with reference to FIG.
As shown, the laser processing apparatus 1 includes a laser light source 2, a laser beam splitting unit 3, a condensing optical system 4, an optical fiber 5, an irradiation optical system 6, a stage 7 and a stage moving device 8, And a control unit 9. The laser beam splitting unit 3, the condensing optical system 4, and the optical fiber 5 constitute a laser beam shaping device.

  The laser light source 2 outputs laser light L0 and can be selected according to the content of laser processing. As the laser light source 2, for example, a pulse oscillation double wave YAG laser (wavelength of 532 nm) can be used.

  On the laser light output end side of the laser light source 2, a laser light dividing unit 3 is disposed. The laser beam splitting unit 3 splits the laser beam L0 output from the laser light source 2 into a plurality of N (N is an integer of 2 or more) laser beams L1 to LN, and between the plurality of laser beams L1 to LN. An optical path difference exceeding the spatial coherent length is given. For this reason, the laser beam splitting unit 3 has a function as a laser beam optical path difference providing unit. The laser beam splitting unit 3 includes a semi-transmissive plate 31 that is inclined on the optical path of the laser light L0 output from the laser light source 2, and a reflective plate 32 that is disposed to face the reflective side of the semi-transmissive plate 31. ing. The semi-transmissive plate 31 and the reflective plate 32 are disposed so that the opposed surfaces are parallel and have a distance d between the opposed surfaces.

Further, the semi-transmissive plate 31 and the reflecting plate 32 are disposed with their plate surfaces inclined so that the laser light L0 is incident on the one end side of the semi-transmissive plate 31 at an incident angle θ. Although the incident angle θ can be selected as appropriate, it is desirable to set the incident angle θ so that the distance between adjacent plural-order transmitted lights that pass through the semi-transmissive plate 31 becomes the beam size of the laser light L0. The incident angle θ can be suitably selected within a range of 5 to 10 °, for example.
One end side of the reflection plate 32 is located farther from the optical path than the semi-transmissive plate 31. Thereby, a part of the plate surface on one end side of the semi-transmissive plate 31 is positioned on the optical path of the laser beam L0 without being blocked by the reflecting plate 32, and an incident optical path of the laser beam L0 to the semi-transmissive plate 31 is secured. Is done.
As the transflective plate 31, a transmissivity T of, for example, 5 to 20% can be used, and for example, a transflective mirror or the like can be used. Further, as the reflection plate 32, for example, a total reflection mirror can be used.

  As will be described later, the laser beam splitting unit 3 repeats the partial reflection and the remaining transmission of the laser beam on the semi-transmissive plate 31 and the reflection of the laser beam on the reflective plate 32, thereby generating a plurality of laser beams L 0. Are emitted from the transmission side of the semi-transmissive plate 31. The optical path difference between adjacent laser beams in the plurality of laser beams L1 to LN is obtained by using the distance d between the opposed surfaces of the semi-transmissive plate 31 and the reflective plate 32 and the incident angle θ of the laser beam L0 with respect to the semi-transmissive plate 31. It is expressed by 2d · cos θ. The distance d between the opposing surfaces and the incident angle θ are set so that the optical path difference 2d · cos θ exceeds the spatial coherent length of the laser light L0 output from the laser light source 2.

The semi-transmissive plate 31 and the reflective plate 32 disposed so as to face the semi-transmissive plate 31 can be installed so that the inclination angle with respect to the laser light L0 can be adjusted. In this case, the incident angle θ of the laser light L0 can be appropriately changed by appropriately changing the inclination angles of the semi-transmissive plate 31 and the reflecting plate 32.
The number (N) of the laser beams divided by the laser beam splitting unit 3 is not particularly limited as the present invention. If the laser beam is partially transmitted and the remaining portion is repeatedly reflected, the laser beam intensity gradually decreases. Therefore, the laser beam exceeding the Nth order may be excluded so as not to use a divided laser beam having a predetermined intensity or less. Further, all of the Nth-order laser light may be advanced.

A condensing optical system 4 is disposed on the transmission side of the semi-transmissive plate 31. The condensing optical system 4 includes a condensing lens 41. As will be described later, the condenser lens 41 is disposed perpendicular to the optical paths of the plurality of laser beams L1 to LN so as to collect the plurality of laser beams L1 to LN that are transmitted through the semi-transmissive plate 31 and are parallel to each other. ing.
One end of the optical fiber 5 is disposed at the condensing position of the condensing lens 41, and a plurality of laser beams L <b> 1 to LN condensed by the condensing lens 41 are guided to one end side of the optical fiber 5. .
In this embodiment, the condensing optical system 4 is arranged. However, a plurality of laser beams are guided to the waveguide without using the condensing optical system, and are guided in the waveguide as a collective light beam. There may be.

The optical fiber 5 corresponds to the waveguide of the present invention, and has a predetermined waveguide cross-sectional shape such as a square shape according to the beam shape to which the laser light is to be shaped. The optical fiber 5 is a combined laser beam composed of a plurality of laser beams L1 to LN that are guided to a predetermined beam shape by guiding a plurality of laser beams L1 to LN guided to one end thereof. The laser beam LS is emitted from the other end.
The optical fiber 5 can be appropriately selected according to the content of the laser processing, and is not particularly limited. One or a plurality of bundles can be used.

An irradiation optical system 6 is disposed on the other end side of the optical fiber 5. The irradiation optical system 6 guides and irradiates the laser beam LS emitted from the other end of the optical fiber 5 to the workpiece 10 on the stage 7.
The irradiation optical system 6 includes an imaging lens 61 arranged on the optical path of the laser light LS emitted from the other end of the optical fiber 5, a galvano mirror 62 arranged in the transmission direction of the imaging lens 61, and a galvano mirror. And an fθ lens 63 arranged in the reflection direction 62.
The galvanometer mirror 62 can oscillate the reflection surface within a predetermined angle range, and thereby the reflection direction of the laser light incident on the galvanometer mirror 62 can be changed. Although the moving speed of the laser beam which moves on the to-be-processed object 10 by the galvanometer mirror 62 is not specifically limited, For example, the range of 100-500 mm / sec can be illustrated.

  In the transmission direction of the fθ lens 63, a stage 7 for holding the target object 10 such as a semiconductor wafer is disposed. The stage 7 is provided on a stage moving device 8 that can move the stage 7 in the X and Y directions. Although the moving speed of the stage 7 by the stage moving apparatus 8 is not specifically limited, For example, the range of 2-10 mm / sec can be illustrated. For example, the laser beam can be scanned in the X direction by the galvano mirror 62, and the stage 7 can be scanned in the Y direction by the stage moving device 8 for processing.

  The control unit 9 controls the entire laser processing apparatus 1 and mainly includes a CPU and a program for operating the CPU. Specifically, the control unit 9 controls the movement of the stage moving device 8 and further controls the swing of the galvanometer mirror 62. The control unit 9 controls the output of the laser light source 2. In addition, when the semi-transmissive plate 31 and the reflective plate 32 are installed so that the tilt angle with respect to the laser light L0 can be adjusted, the control unit 9 controls the tilt angles of the semi-transmissive plate 31 and the reflective plate 32 to a predetermined angle. be able to.

Next, the operation of the laser processing apparatus 1 will be described.
A target object 10 such as a semiconductor wafer is placed and held on the stage 7.
The laser light L0 output from the laser light source 2 is incident on the semi-transmissive plate 31 at an incident angle θ. In the semi-transmissive plate 31, the laser beam L0 is partially reflected at the reflection angle θ, and the remaining portion is transmitted at the transmittance T. When the intensity of the laser beam L0 is F, the intensity of the transmitted laser beam L1 is FT. The intensity of the reflected laser beam is F · (1-T).

  The laser beam having the intensity F · (1-T) reflected by the semi-transmissive plate 31 is incident on the reflective plate 32 at an incident angle θ. In the reflecting plate 32, the incident laser beam having the intensity F · (1-T) is reflected at the reflection angle θ. Note that the reflection on the reflecting plate 32 is not necessarily total reflection, and may be reflection with a high reflectance of 90 to 99%, for example.

The laser beam having the intensity F · (1-T) reflected by the reflecting plate 32 enters the semi-transmissive plate 31 at an incident angle θ. In the semi-transmissive plate 31, the incident laser beam having the intensity F · (1-T) is partially reflected at the reflection angle θ, and the remaining part is transmitted at the transmittance T. The intensity of the transmitted laser beam L2 is F · T · (1-T). The intensity of the reflected laser beam is F · (1-T) ² .
Between the laser beam L1 and the laser beam L2, the laser beam reflected by the semi-transmissive plate 31 is reflected by the reflective plate 32, and then at the same position as the position reflected by the semi-transmissive plate 31 in the traveling direction. The optical path length to reach is given as an optical path difference. That is, an optical path difference 2d · cos θ is given between the laser light L1 and the laser light L2.

Thereafter, in the same manner as described above, partial reflection and residual transmission at the semi-transmissive plate 31 and total reflection at the reflective plate 32 are repeated, whereby a plurality of laser beams L1 to LN are transmitted through the semi-transmissive plate 31. It is emitted from the side. The intensity of the laser light LN obtained in this way is FT · (1−T) ^N−1 . Further, between adjacent laser beams, an optical path difference 2d · cos θ is given to each other.

The plurality of laser beams L <b> 1 to LN emitted from the transmission side of the semi-transmissive plate 31 are condensed and guided to one end of the optical fiber 5 by the condenser lens 41. In the optical fiber 5, a plurality of laser beams L1 to LN are guided and shaped into a predetermined beam shape, and are combined laser beams of the plurality of laser beams L1 to LN, and a laser beam LS having a top flight intensity distribution is obtained. The light is emitted from the other end of the optical fiber 5.
Between the laser beams of the plurality of laser beams L1 to LN, there is an optical path difference that exceeds the spatial coherent length, so that interference between the laser beams is avoided.
In addition, since each laser beam itself in the plurality of laser beams L <b> 1 to LN is not divided, interference due to a phase difference occurs in the optical fiber 5. Since each laser beam has a different reflection angle in the fiber 5, it has different interference patterns in interference. For this reason, the laser beams LS 1 to LN are guided in the optical fiber 5 to average the intensity and to obtain the laser beam LS with significantly reduced interference.

For example, the laser light source 2 outputs laser light L0 having an intensity F of 10 mJ, a wavelength of 532 nm, an oscillation frequency of 10 kHz, an M square of 20, a spatial coherent length of 5 mm, and a beam diameter of 2 mm. When the incident angle θ of the light L0 is 5.74 °, the transflective plate 31 having a transmittance T of 10% is used, and the distance d between the transflective plate 31 and the reflective plate 32 is 10 mm, specifically, It becomes as follows.
First, the intensities of the plurality of laser beams L1, L2,..., LN are ¹ mJ, 0.9 mJ, ... 1 × 0.9 ^N−1 mJ, respectively, and N = 22 is about 0.11 mJ.

The optical path difference between adjacent laser beams in the plurality of laser beams L1 to LN is 19.9 mm, which is sufficiently longer than the spatial coherent length of 5 mm.
Further, the interval between adjacent laser beams is 2d · sin θ = 2 mm, which matches the beam diameter. The total beam size of all 22 laser beams L1 to L22 is 44 mm. Note that, after the laser beam L23 with N = 23 or more, the intensity is less than 0.1 mJ, and can be ignored.

Further, the plurality of laser beams L1 to LN divided as described above are rectangular using a condenser lens 41 having a focal length f of 20 mm, a numerical aperture NA of 0.22, and a waveguide cross-sectional shape of 600 μm × 600 μm. When the light beam is incident on the optical fiber 5, the NA of the beam for condensing the laser light incident on the optical fiber 5 is 2 mm / 2/20 mm = 0.05 because the beam diameter of the laser light L 0 is 2 mm. Thus, since the numerical aperture NA is smaller than that of the optical fiber 5, most of the laser light L0 output from the laser light source 2 can be incident on the optical fiber 5.
The condensed beam diameter of each laser beam in the divided laser beams L1 to LN can be approximated by (2λ / π) × (1 / NA) × (M square), and M square is 20. The condensed beam diameter is 135 μm, which is sufficiently smaller than the fiber diameter of the optical fiber 5.

The laser light LS emitted from the other end of the optical fiber 5 as described above enters the galvanometer mirror 62 through the imaging lens 61. The laser beam LS is reflected by the oscillating galvanometer mirror 62 while changing the reflection direction. The laser light LS reflected by the galvano mirror 62 is condensed on the object 10 by the fθ lens 63 and moves on the object 10 at a constant speed. The oscillation of the galvanometer mirror 62 may be either continuous or intermittent.
Further, in addition to the swinging of the galvanometer mirror 62, the stage 7 is moved by the stage moving device 8, so that the irradiation position of the laser light LS on the object 10 can be moved over a wide range. The laser beam LS can be irradiated over the entire surface of the processing object 10 to be processed. The movement of the stage 7 by the stage moving device 8 may be either continuous or intermittent.
The burden of the stage moving device 8 is reduced by scanning the laser beam LS on the workpiece 10 at a relatively high speed by the galvanometer mirror 62 and moving the stage 7 at a relatively low speed by the stage moving device 8. Moreover, generation | occurrence | production of the vibration by operation | movement of the stage moving apparatus 8, etc. can be minimized.

  The laser beam LS having a top flat intensity distribution is irradiated while being scanned on the object to be processed 10, so that the object 10 is subjected to uniform laser processing.

  In the above embodiment, the optical fiber 5 is used as a waveguide for guiding and shaping laser light. However, in addition to the optical fiber, a kaleidoscope or the like may be used as the waveguide. it can.

  In the above embodiment, the laser beam splitting unit 3 has the function as the laser beam optical path difference providing unit of the present invention, but the laser beam splitting unit and the laser beam optical path difference providing unit are separate from each other. You may comprise as an independent thing.

  As described above, the present invention has been described based on the above embodiment, but the present invention is not limited to the contents of the above description, and can be appropriately changed without departing from the scope of the present invention. .

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Laser light source 3 Laser beam split part 31 Semi-transmissive plate 32 Reflector plate 4 Condensing optical system 41 Condensing lens 5 Optical fiber 6 Irradiation optical system 61 Imaging lens 62 Galvano mirror 63 f (theta) lens 7 Stage 8 Stage movement Device 9 Control unit 10 Object L0 Laser light L1 to LN Multiple laser light LS Laser light

Claims (12)

An apparatus for shaping laser light irradiated for heat treatment of an object,
A laser beam splitting unit that splits the laser beam into a plurality of laser beams;
A laser beam optical path difference providing unit that provides an optical path difference between the plurality of laser beams, and a plurality of laser beams having optical path differences exceeding a spatial coherent length;
A laser beam shaping device comprising: a waveguide through which the plurality of laser beams having an optical path difference exceeding the spatial coherent length are guided, and a beam shape of the laser beam is shaped.   2. The laser beam shaping device according to claim 1, further comprising a condensing optical system that condenses and guides the plurality of laser beams extracted from the laser beam optical path difference providing unit to one end of the waveguide.   The laser beam shaping device according to claim 1, wherein the laser beam splitting unit functions as a laser beam beam path difference providing unit that gives the optical path difference to the plurality of laser beams. The laser beam splitting unit reflects a part of the laser beam and transmits the remaining part, and a laser reflected at the transflective plate disposed opposite to the reflecting side of the transflective plate with an interval. A reflector that reflects light,
The semi-transmission plate and the reflection plate are arranged such that plate surfaces are inclined with respect to the optical path of the laser light before division, and a part of the plate surface of the semi-transmission plate is positioned on the optical path. The laser beam shaping device according to claim 1, wherein   2d · cos θ is set to a length exceeding the spatial coherent length, where d is the distance between the opposing surfaces of the semi-transmissive plate and the reflective plate, and θ is the incident angle of the laser beam to the semi-transmissive plate. The laser beam shaping device according to claim 4.   The laser light shaping apparatus according to claim 1, wherein the waveguide is an optical fiber or a kaleidoscope. A laser beam shaping device according to any one of claims 1 to 6;
An irradiation optical system for guiding a laser beam emitted from a waveguide included in the laser beam shaping device to irradiate the object to be processed.   The irradiation optical system includes a scanning unit that moves the irradiation position of the laser light on the object to be processed by changing the irradiation direction of the laser light to the object to be processed continuously or intermittently. The laser processing apparatus according to claim 7.   The laser processing apparatus according to claim 8, wherein the scanning unit includes a galvanometer mirror and an fθ lens.   A method of shaping laser light irradiated for heat treatment of an object to be processed, wherein the laser light is divided into a plurality of laser lights, and an optical path difference exceeding a spatial coherent length is obtained for each of the divided laser lights. The laser beam is characterized in that the plurality of laser beams given the optical path difference are introduced into one end of a waveguide and guided in the waveguide to shape the beam shape of the laser beam. Formatting method.   A laser processing method, comprising: irradiating an object to be processed with laser light shaped by the laser light shaping method according to claim 10.   12. The laser processing method according to claim 11, wherein the object to be processed is irradiated while scanning with the laser beam shaped by the laser beam shaping method.

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