JP2006054480A - Laser process apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser process apparatus, capable of simple and easy configuration and adjustment for further uniformizing of irradiation beam, by preventing interference between split beams due to superimposing, and further, enabling stable homogeneous irradiation. <P>SOLUTION: The apparatus is provided with at least one laser oscillator for generating a laser beam, in which an M2 value being an index representing collection performance of beams generated from a laser oscillator is not more than 100, a laser beam splitting means for spatially splitting a laser beam from the laser oscillator into N-pieces of split beams in beam cross section, a superimposing irradiation means for substantially superimposing the split beams on an irradiation plane to irradiate the superimposed beam, and an optical path length control means for differentiating the optical path lengths of adjacent split beams adjacent to each other of the beams split into N-pieces. In this apparatus, the M2 value is at least M2≥N/2, in at least the beam splitting direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser process apparatus that improves the homogeneity of an irradiation laser beam on an irradiation surface during laser processing of an irradiation object.

  As an example of heat treatment by laser irradiation, when a polycrystalline silicon film is manufactured, an amorphous silicon film is previously deposited on a suitable substrate, for example, a glass substrate, by a vapor deposition method such as CVD. In addition, a method of polycrystallizing this amorphous silicon film by scanning with a laser beam is known.

  In the method for polycrystallizing a silicon film, for example, a laser beam from a laser light source is focused on an amorphous silicon film by a lens and irradiated with a laser, and the silicon film is scanned at the time of irradiation, so There is something that crystallizes in the process. This laser beam is usually an axially symmetric Gaussian distribution because the axial intensity profile of the beam at the irradiation position depends on the profile of the laser source. The polycrystalline silicon film formed by irradiation with such a beam has a very low uniformity of crystallinity in the plane direction, and it has been difficult to use a thin film transistor as a semiconductor substrate for manufacturing.

  Further, a technique is known in which a semiconductor film is irradiated and heated using a short-wavelength excimer laser so that the profile of the irradiation beam is distributed in a rectangular shape. For example, a laser beam from an oscillator is focused on a semiconductor film surface through a converging lens in front of two cylindrical lens da array that intersect each other in a plane perpendicular to the optical axis. In this method, a laser beam having a Gaussian distribution is made to have a uniform intensity distribution in two orthogonal directions by means of two cylindrical lens arrays, and the irradiation laser beam on the semiconductor film surface is orthogonal on the semiconductor surface. The width is different in the two directions, and a polycrystalline band having a certain width is repeatedly formed on the semiconductor film by sweeping and moving the irradiation laser beam (for example, see Patent Documents 1 and 2). .

Recently, the maximum output of the YAG laser has been significantly improved. Since the YAG laser is a solid-state laser, it is easier to handle and maintain than an excimer laser that is a gas laser. A silicon film polycrystallization method using the second harmonic of a YAG laser, which has this feature, has attracted attention because of its potential for high mobility. However, the coherent length of the excimer laser is about several microns to several tens of microns, and the optical interference when passing through an optical system that splits the laser beam into one is very weak, whereas the YAG laser , And its second harmonic coherent length is very long, about 1 cm. The influence of this interference cannot be ignored.
The interference generated in the superimposed beams on the irradiated surface is because the intensity profile in the moving direction of the laser beam greatly affects crystal growth when a semiconductor film is heated and crystallized using a rectangular irradiation laser beam. It is not preferable to grow large in the crystal grain of the silicon film.

  There has been proposed a method for removing the non-uniformity of the irradiation laser intensity due to this interference. For example, a beam from a light source is collimated by a collimator, irradiated onto a mirror having a stepped reflecting surface, and a beam divided by the mirror is irradiated. An optical system configured to irradiate with a cylindrical lens array to be synthesized and a cylindrical lens for convergence is disclosed. This is to prevent interference between the divided beams on the irradiation surface by providing an optical path difference equal to or greater than the coherent length of the laser beam due to the step between the reflecting surfaces in each divided beam (for example, Patent Document 3). reference).

  Also, the laser beam from the light source is converted into parallel light by a beam collimator, irradiated to a plurality of small reflecting mirrors, and the reflected light from each reflecting mirror is irradiated onto the irradiation surface to superimpose, and the laser that reflects each flat mirror Similarly, there is one that prevents interference by ensuring the optical path difference of the beam to be equal to or longer than the coherent length (for example, see Patent Document 4).

Japanese Patent Laid-Open No. 10-333077 (page 2-5, FIGS. 1 and 2) JP-A-6-69415 (page 2-6, FIG. 1-15) Japanese Patent Laid-Open No. 2001-127003 (page 2-10, FIG. 6-10) Japanese Patent Laid-Open No. 2001-244213 (page 2-20, FIG. 3-13)

The beam homogenization technique described above prevents interference when laser beams from the same light source are split and overlapped on the irradiation surface by using a reflecting mirror having multiple reflecting surfaces to provide an optical path difference. However, these optical systems require special reflecting mirrors. In particular, the optical system of Patent Document 4 requires an arrangement that bends the optical axis of the optical system by a reflecting mirror. Further, each reflecting mirror of the optical system accurately corresponds to the irradiation surface corresponding to a large number of divided beams. Therefore, there is a problem in that the arrangement of the reflecting mirrors is complicated, and the degree of freedom of the optical system to be arranged as a heat treatment apparatus is reduced.
In addition, if the optical path difference is provided for all the divided beams, the transfer conditions for each beam are greatly different, so that there is a problem that the divided beams cannot be superimposed on the irradiation surface in the same manner. For a large laser oscillation source, the apparatus becomes large and complicated, which is not practical and optical adjustment is difficult.

  The present invention provides a uniform intensity distribution on the irradiation surface by superimposing the divided beams obtained by dividing the laser beam having an M2 value (an index indicating the condensing property of the beam generated from the laser oscillator) of 100 or less. In the laser processing equipment that forms the irradiated beam, it is intended to prevent the interference between the divided beams due to superposition and to make the irradiated beam more uniform, especially to prevent such interference. Thus, it is an object of the present invention to provide a laser processing apparatus that is simple and easy to configure and adjust for uniformizing an irradiation beam and that enables stable uniform irradiation.

  The laser processing apparatus according to the present invention includes at least one laser oscillator that generates a laser beam having an M2 value of 100 or less, which is an index indicating the condensing property of a beam generated from the laser oscillator, and a laser beam from the laser oscillator. Beam splitting means for spatially dividing the beam into N divided beams in the beam cross section, superimposing irradiation means for irradiating each of the divided beams approximately on the irradiation surface, and the N divided beams. Optical path length control means for changing the optical path length of adjacent split beams adjacent to each other, and optical delay means for delaying one of the adjacent split beams longer than the time coherence distance of the laser beam with respect to the other, The M2 value is M2 ≧ N / 2 at least in the beam splitting direction.

  As described above, according to the present invention, at least one laser oscillator that generates a laser beam having an M2 value of 100 or less, which is an index indicating the condensing property of the beam generated from the laser oscillator, and the laser oscillator A laser beam splitting unit that splits the laser beam spatially into N divided beams in a beam cross section, a superimposing irradiation unit that irradiates each of the split beams approximately on the irradiation surface, and the N splits. Optical path length control means for changing the optical path lengths of adjacent split beams adjacent to each other, and optical delay means for delaying one of the adjacent split beams longer than the temporal coherence distance of the laser beam with respect to the other. And the M2 value is M2 ≧ N / 2 at least in the beam splitting direction, thereby preventing interference between split beams due to superposition. Illumination beam are more easy and uniform configuring for the adjustment and is easy and laser processing apparatus is obtained which enables a stable homogeneous illumination.

Embodiment 1 FIG.
1A and 1B are plan views showing a configuration of a laser processing apparatus according to Embodiment 1 of the present invention, in which FIG. 1A is a view seen from the y direction, and FIG. 1B is a view seen from the x direction.
In this embodiment, the laser processing apparatus shown in FIGS. 1A and 1B has a linear irradiation profile that spreads in a uniform distribution in the y direction on the irradiation surface and converges linearly in the x direction. The example which forms is shown.

  The laser process apparatus includes a laser oscillator 100, a laser beam splitting means 3, a superimposing irradiation means 6, and an optical delay means 2. The laser beam splitting means 3 uses a waveguide 4 to make a laser beam. Is divided into a desired number of divided beams 16 a to 16 e, and the divided beams are imaged as an irradiation beam 19 of a linear profile on the irradiation surface 90 of the irradiation object 9 by the overlapping irradiation means 6.

  In the present embodiment, the laser beam splitting means 3 includes an optical system for making the laser beam 1 from the laser oscillator 100 incident into the waveguide 4, a beam expanding lens 31 for making a parallel beam, and a y-direction collimator. It includes a lens 32 and an x-direction collimating lens 33, and then includes a cylindrical lens condensing lens 34 that condenses light in the y direction and enters the waveguide 4.

  In the waveguide 4, parallel main surfaces facing each other have reflection surfaces 41 and 42, and the reflection surfaces 41 and 42 are perpendicular to the y direction in this drawing. An incident end face 43 and an exit end face 44 through which the laser beam 1 passes between both reflecting surfaces are orthogonal to the optical axis of the laser beam. The incident laser beam 1 is a split beam of a component that passes between the reflecting surfaces and radiates from the exit end, and a split beam of two components (m = 1) that is reflected once by either of the reflecting surfaces 41 and 42 (m = 1). = + 1, m = -1) and two split beams (m = + 2, m = -2) of the component reflected twice on both reflecting surfaces (m = 2), and further three or more times Each of the reflected pair of split beams is split into components emitted from the emission end.

  The split beam from the waveguide 4 is projected by being superimposed on the irradiation surface 90 by the superimposing irradiation means 6, and the superimposing irradiation means 6 transfers the split beam onto the irradiation surface 90 in the y direction. The transfer lens 61 (cylindrical lens) in the direction and the condensing lens 62 (cylindrical lens) that collects light in the x direction can be used. The y-direction transfer lens 61 extends through the x-direction condensing lens 62 to a prescribed length in the y-direction on the irradiation surface 90, and the x-direction condensing lens 62 converges linearly in the x-direction. An irradiation beam 19 of a linear profile is obtained on the irradiation surface.

  The transfer lens 61 in the y direction of the superimposing irradiation means 6 is set so that each divided beam forms a real focus and is projected onto the irradiation surface 19, and the divided beams are spatially separated from each other in the vicinity of the real focus position. The delay light transmitting body 2 is arranged at the position as an optical delay means. This delay plate 2 is arranged so that either one of the optical paths of the split beams is present in a region adjacent to each other before splitting. Is delayed with respect to the other optical path to provide an optical path difference to prevent interference between the two split beams when they are superimposed on the irradiation surface 19. In the example of FIG. 1, the delay plate 2 is disposed every other split beam at the actual focal position on the exit side of the transfer lens 61.

More specifically, FIG. 2 shows a mode of splitting the laser beam from the laser oscillator 100 with respect to the waveguide of the laser beam splitting means, but the laser beam from the laser oscillator 100 is the condensing lens 34 of the cylindrical lens. and it enters the waveguide 4 through the focal point F ₀ by. In the waveguide, there is a split beam (reflection number m = 0) in which a part of the incident beam is transmitted without reflection on the reflection surface, and the split beam reflected only once by the reflection surfaces 41 or 42 facing each other. There are two types in the y direction (m = ± 1), and there are also two types of split beams reflected by the reflecting surfaces 41 and 42 in the y direction (m = ± 2). Radiated from. The plane perpendicular to the optical axis and including the focal point F ₀ has virtual image focal points F ₊₁ , F ₋₁ , F ₊₂ , and F _{−2 of the} divided beams emitted from the emission surface 43. These virtual image focal points F ₊₁ ... Appear to be emitted through the opening of the emission surface 43.

  Assuming that the laser beam spread through the focal point by the condensing lens 34 when it is assumed that there is no waveguide is projected on the surface at the position of the exit surface 44, the profile of the projected laser beam 14 Can be decomposed into components corresponding to each of a number of divided beams. If each component in the cross section of the laser beam 1 is divided in the order of m = −2, −1, 0, +1, +2 in the y direction on the cross section, the component radiated from the output surface 44 of the waveguide 4, that is, Note that the split beams are arranged in the order of components of the number of reflections m = + 2, −1, 0, +1, −2 in the y direction.

  FIG. 2 shows only the arrangement of the divided beams of components of m = 0, +1, +2 radiated from the exit surface 44 of the waveguide 4, and the divided beams of m = + 1 and m = + 2 are reflected on the reflecting surface. Radiated in opposite directions with respect to the intermediate plane. On the other hand, the split beams of m = −1 and −2 are in a symmetric direction with respect to the central surface of the reflection surface of m = + 1 and +2, but are omitted in the drawing.

FIG. 3A schematically shows the split width of the split beam in the laser beam 14 projected on the plane corresponding to the exit surface 44 of the waveguide 4 without reflecting the laser beam from the focal point F ₀ by the waveguide 4. It has become. This is an example in which a laser beam 14 having a circular profile is divided into seven by a waveguide.

  In the waveguide 4, the split beams adjacent to each other are folded and superimposed on the exit surface 44 of the waveguide 4. Therefore, the components adjacent to each other due to the division of the laser beam 1 coincide with each other at the folded portion of the divided beam at the exit surface of the waveguide in FIG. For example, in FIG. 3A, the boundary portion III of the m = + 1 component and the boundary portion iii of m = 0 in contact therewith are folded back at the exit surface 44 of the waveguide, as shown in FIG. Overlap.

  When such a folded split beam is projected on the irradiation surface 90 through the y-direction transfer lens 61 and the x-direction condenser lens 62, the irradiation beam interferes with the irradiation surface. A wavy distribution is formed in the intensity.

Furthermore, this embodiment includes an optical delay means for delaying any one of the adjacent split beams adjacent to each other among the split beams formed by the above-mentioned waveguide with respect to the other longer than the temporal coherence distance. It is out.
This optical delay means can be used for both a hollow mirror and a solid translucent body, but the split beams from adjacent areas interfere with each other with an optical path difference between them. This is to prevent interference.

The temporal coherence distance ΔL of the laser beam is
ΔL = cΔt≈λ ² / Δλ
Given in. Here, c is the speed of light, Δt is the coherence time, Δλ is the wavelength width (spectrum width) of the laser, and the narrower the laser wavelength width, the longer the coherence distance.
For example, in a YAG laser (Nd: YAG laser), the spectral width Δλ = 0.12 to 0.30 nm for a beam having a center wavelength of λ = 1.06 μm, so the temporal coherence distance ΔL is ΔL = 3.8 to 9.4 mm. The value of ΔL is approximately the same for the second harmonic laser (YAG2ω laser) of the YAG laser.

In FIG. 1, a translucent delay plate 2, that is, an optical glass plate 2 is inserted as an optical delay unit in one of split beams that are likely to interfere with each other at a position where a plurality of split beams are separated from each other. Thus, an optical path difference is formed between the adjacent split beams. In this example, the beam divided by the waveguide 4 is transferred by the y-direction transfer lens 61, and the irradiation beam 19 is formed on the irradiation surface by the x-direction condenser lens 62. A focal point f is formed on each beam by the y-direction transfer lens 61 between the optical lens 62, and the glass plate as the delay plate 2 is inserted into one of the adjacent beams at the focal point f or before and after the focal point f. An optical path difference is provided. In this example, a glass plate is inserted in every other five divided beams, and other divided beams pass through the space between the delay plates 2 and 2 adjacent to each other. By the delay plate 2 having such an arrangement, the irradiation beam superimposed on the irradiation surface does not cause interference between the adjacent divided beams, so that a profile with a substantially uniform intensity distribution can be obtained. .
The optical path difference Δa by the glass plate is obtained from the thickness a of the glass plate, the refractive index n _{1 of the} glass, and the refractive index n _{0 of the} air.
Δa = a (n ₁ −n ₀ )
Given in.

Since the optical path difference Δa by the glass plate is set to be equal to or greater than the temporal coherence distance ΔL (Δa ≧ ΔL), the glass that gives the optical path difference equal to or greater than the temporal coherence distance ΔL between the divided beams adjacent to each other from these equations. A thickness a is required. The thickness of the delay plate is preferably set so as to provide an optical path difference of 2 times or more, more preferably 4 times or more of the temporal coherence distance ΔL by the delay plate. For example, in a YAG laser (Nd: YAG laser) or YAG2ω laser, when quartz (n ₁ = 1.46) is used as the optical delay means, the temporal interference distance ΔL is 3.8 to 9.4 mm. The optical path difference Δa is 12 to 30 mm.

  In the present embodiment, the laser oscillator 100 generates a YAG second harmonic laser (YAG 2ω laser) having a wavelength of 532 nm. Further, the M2 value, which is an index representing the condensing property of the beam generated from the laser oscillator 100, is N / 2 or more when the beam division number N is at least in the beam division direction (y direction). The M2 value is an index indicating how many times the diameter of the focused beam is larger than that of the single mode (TEM00) beam when the same focusing optical system is used. Naturally, the larger the M2 value, the larger the focused beam diameter, and the lower the beam quality.

As described above, when every other delay plate 2 is inserted into the divided beams, any combination of two divided beams adjacent to each other (for example, a divided beam with the number of reflections m = + 1 and m = 0). However, interference between two beams other than those adjacent to each other (for example, between split beams with the number of reflections m = -2 and m = 0) cannot be prevented.
Therefore, in the present embodiment, as will be described in detail below, when the M2 value is the number of beam divisions N, by setting N / 2 or more, interference between all the divided beams is prevented. ing.

  FIG. 4 shows only two components of the split beam from the waveguide when the division number N is approximately 7, for example, two components of the number of reflections m = + 1 and m = 0, and the y-direction transfer lens 61 and x. The measurement result of the intensity distribution on the irradiation surface when superimposed and irradiated on the irradiation surface 90 via the direction condensing lens 62 etc. is shown. Here, the delay plate 2 that gives an optical path difference to the adjacent split beams is not inserted. 4A shows the result when M2 = 5.7, and FIG. 4B shows the result when M2 = 11.3. FIG. 4 shows that the spatial coherence distance is clearly reduced by increasing M2 from 5.7 to 11.3.

When the beam diameter is defined as the diameter at the peak intensity 1 / e ² (where e is the base of the natural logarithm), the spatial coherence distance with respect to the M2 value when the beam diameter is 100% is shown in FIG. Show. Here, the spatial coherence distance X is defined as the distance between two points that attenuate to 1 / e with respect to the intensity of interference generated when laser beams at the same position are superimposed, and is standardized by the beam diameter. Distance. FIG. 5 shows a space when the M2 value of each laser oscillator is changed using three YAG2ω laser oscillators A, B, and C having different power levels as the laser oscillator 100 in the laser processing apparatus having the configuration shown in FIG. The measurement result of the effective coherence distance X is shown. In both cases, the division number N is 7, and the coherence distance between two components of the number of reflections m = + 1 and m = 0 is shown. As is clear from the figure, it has been found that the spatial coherence distance X is 1 / M2 or less. In the example in the figure, the measurement result of the coherence distance between two components of the number of reflections m = + 1 and m = 0 is shown. However, even when data between other adjacent components is used, spatial permitting is possible. The result is the same because it is a number defined by the interference distance.

As described above, in the configuration of FIG. 1 in which the delay plate 2 is inserted, interference between adjacent beams can be suppressed by inserting the delay plate 2, but further, between the divided beams, for example, Since m = 0 and m = ± 2 are in phase in time, interference cannot be suppressed. In order to suppress the interference between the further divided beams, the spatial coherence distance is a distance between two or more divided components (ie, between two adjacent points) (ie, 2 / N) The following may be used. When every other delay plate 2 is inserted into the divided beams, the necessary condition for preventing the interference from appearing is:
X = 1 / M2 ≦ 2 / N (N is a positive number)
That is, M2 ≧ N / 2
It can be seen that it is.

  As described above, when using a laser oscillator that generates a laser beam having a relatively low M2 value of 100 or less at maximum, the present inventors split the beam into N split beams, In the present invention, it was found that there is a close relationship between the M2 value, which is an index representing the condensing property of the beam generated from the laser oscillator, and the spatial coherence distance when superposed on the irradiation surface. It has come. In general, the smaller the M2 value, the smaller the focused beam diameter and the better the beam quality. However, the present invention has found that there is an optimum M2 value according to the number of beam divisions.

As described above, according to the present embodiment, the laser beam from the laser oscillator is spatially divided into N divided beams in the beam cross section using the reflecting surfaces facing each other, and the N divided beams are obtained. In contrast, when the delay plate 2 is inserted as an optical path length or polarization direction control means for every other beam and the respective divided beams are superimposed and irradiated on the irradiation surface, an index indicating the condensing property of the beam generated from the laser oscillator 100 When the value of M2 is N / 2 or more when the number of beam divisions is N, interference between all the divided beams due to superposition can be prevented. In particular, when every other delay plate 2 is inserted into N divided beams and the M2 value is set to the number of beam divisions N, it is only N / 2 or more, as shown in Patent Documents 3 and 4. Thus, since it is not necessary to provide an optical path difference for all of the split beams, the configuration and adjustment are simple and easy. In addition, when the value of M2 is N, the number of beam divisions is N / 2 or more, so that interference between two beams other than those adjacent to each other can be reliably suppressed, enabling stable homogeneous irradiation. It becomes.
Note that the YAG2ω laser shown in the present embodiment is typically used for homogenization, but the M2 value widely used in the industrial field is also used for other lasers. Is required even for lasers with a relatively good beam quality of 100 or less. In reality, the configuration of this patent is required for lasers of 50 or less, which require more light condensing performance.

Embodiment 2. FIG.
6A and 6B are plan views showing the configuration of the laser processing apparatus according to the second embodiment of the present invention. FIG. 6A is a view seen from the y direction, and FIG. 6B is a view seen from the x direction.
In this embodiment mode, the laser process apparatus shown in FIGS. 6A and 6B spreads in a uniform distribution in the y direction on the irradiation surface and extends in the x direction as in the case of the first embodiment. An example of forming a linear irradiation profile converged linearly is shown.

In the first embodiment, when the delay plate (optical delay means) 2 is used as the optical path length or polarization direction control means for changing the optical path length or polarization direction of adjacent split beams adjacent to each other into N divided beams. However, in this embodiment, the optical rotation means 7 is used to make one of the adjacent split beams adjacent to each other divided into N beams substantially orthogonal to the polarization direction with respect to the other.
Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  The transfer lens 61 in the y direction of the superimposing irradiation means 6 is set so that each divided beam forms a real focus and is projected onto the irradiation surface 19, and the divided beams are spatially separated from each other in the vicinity of the real focus position. At this position, a half-wave plate for polarization rotation is disposed as the optical rotation means 7, but the optical rotation means 7 has one of the split beams in the adjacent regions before the splitting and the polarization angle with respect to the other. They are substantially orthogonal and prevent interference between the two split beams when superimposed on the irradiation surface 19. In the example of FIG. 6, the wavelength plate 7 is disposed every other split beam at the actual focal position on the exit side of the transfer lens 61.

  The optical rotator 7 rotates the polarization angle so that the two split beams do not interfere with each other so that the polarization angles are substantially orthogonal. Preferably, a half-wave plate made of quartz is used. . In FIG. 6, the focal point f is formed in front of the y-direction transfer lens 61 (cylindrical lens) in front of the waveguide 4 and the half-wave plate 7 is disposed at this focal position. The half-wave plate 7 is inserted only into the three split beams of the number of reflections m = 0, m = + 2 and m = -2, and is not inserted in the other number of reflections m = + 1 and m = -1. In this configuration, half-wave plates 7 are interposed for every other split beam arranged in the y direction. Thus, referring to FIG. 3A, half-wave plate 7 is inserted into only one of the two split beams adjacent to each other, and the polarization angle is substantially reduced with respect to the other split beam. It is orthogonal. Thus, no interference occurs even when two split beams of any combination adjacent to each other are superimposed on the irradiation surface 90. Therefore, the uniformity of the irradiated beam is improved by the substantial superposition of the polarized beams.

  However, in this specification, the fact that the polarization angle (polarization direction) is substantially orthogonal may mean that one split beam is shifted from the orthogonal state to a range of ± 30 ° with respect to one split beam. This can substantially reduce the interference between the split beams.

As described above, when every other half-wave plate 7 is inserted into the divided beams, any combination of two divided beams adjacent to each other (for example, division of the number of reflections m = + 1 and m = 0) Interference is prevented even between the beams), but interference between two beams other than those adjacent to each other (for example, between the divided beams with the number of reflections m = -2 and m = 0) cannot be prevented.
Therefore, in the present embodiment as well, as described in the first embodiment, when the M2 value, which is an index indicating the condensing property of the beam generated from the laser oscillator 100, is set as the beam division number N, N By setting it to / 2 or more, interference between all split beams is suppressed.

Embodiment 3 FIG.
As described in the first embodiment, the laser beam from the laser oscillator is spatially divided into N divided beams in the beam cross section using the reflecting surfaces facing each other, and 1 for each of the N divided beams. When every other delay plate 2 is inserted and each divided beam is superimposed and irradiated on the irradiation surface, the M2 value, which is an index indicating the condensing property of the beam generated from the laser oscillator 100, is set as the number N of beam divisions. In this case, interference between all the divided beams can be suppressed by setting N / 2 or more.

The degree of interference suppression at this time largely depends on the optical path difference Δa between adjacent split beams. When the optical path difference is large, it becomes perfect due to the interference suppression effect, but on the other hand, the transfer condition for each divided beam is shifted, and good transfer cannot be performed on the processing table. Therefore, it is desirable to make the spatial coherence distance shorter, and experimentally,
M2 ≧ N
It has been found that this result can be obtained.

Further, even when the half-wave plate 7 described above in the second embodiment is alternately inserted between adjacent beams to suppress interference, the half-wave plate 7 cannot be completely rotated by 90 degrees. Interference remains. Even at this time, M2 ≧ N
If the spatial coherence distance is shortened under the above conditions, a more uniform beam can be obtained on the irradiation surface 90.

Embodiment 4 FIG.
FIG. 7 is a plan view showing the configuration of the laser processing apparatus according to the fourth embodiment of the present invention, and shows the arrangement of the optical system viewed from the x direction. The optical path length or polarization direction control means (optical delay means 2) Except for the difference in arrangement, the laser processing apparatus is basically the same as that shown in FIGS. 1 (A) and 1 (B). Hereinafter, differences from the first embodiment will be mainly described.

  In the present embodiment, in particular, the optical path length or polarization direction control means includes the shield 29, and the straight beam when the number of reflections m = 0 is arranged at the focal position f after the y-direction transfer lens 61. It is blocked by the shield 29. Since the straight beam of m = 0 does not reach the irradiation surface, this does not contribute to interference. Therefore, as the optical delay means 2, only one of the divided beam groups (m = + 1, -2) or (m = -1, +2) arranged symmetrically with respect to the straight beam (m = 0). Since the optical delay means 2 is not disposed in the other group, the interference between the split beams on the irradiation surface is thereby reduced, and the optical delay means 2 is provided with one split beam group ( One glass plate or glass rod that transmits m = + 1, -2) at a time can be used, which is advantageous in that the optical system can be simplified. The shield 29 can be made of a solid that absorbs or reflects a laser beam, such as graphite, ceramics, or metal.

Embodiment 5. FIG.
FIG. 8 is a plan view showing the configuration of the laser processing apparatus according to the fifth embodiment of the present invention, and shows the arrangement of the optical system viewed from the x direction. The arrangement of the optical path length or polarization direction control means (optical rotation means 7) is shown in FIG. Except for these differences, the laser process apparatus is basically the same as that shown in FIGS. 6A and 6B. Hereinafter, differences from the second embodiment will be mainly described.

In the second embodiment, as the optical path length or polarization direction control means for changing the optical path length or polarization direction of adjacent split beams adjacent to each other of the N split beams, half of every other split beam arranged in the y direction. Although the wave plate 7 is interposed, it is necessary to provide a gap between the half wave plates 7 and 7 to transmit other divided beams, and the structure of the half wave plate is somewhat complicated.
In order to solve this problem, in the present embodiment, in particular, the optical path length or polarization direction control means includes the shield 29, and the straight beam when the number of reflections m = 0 is changed to the rear of the y direction transfer lens. It is blocked by the shield 29 arranged at the focal position f. Since the straight beam of m = 0 does not reach the irradiation surface, this does not contribute to interference. Therefore, the optical rotation means 7 is inserted into only one of the divided beam groups (m = + 1, -2) or (m = -1, +2) arranged symmetrically with respect to the straight beam (m = 0). In the other group, the optical rotation means 7 is not disposed, so that the interference between the divided beams on the irradiation surface is reduced, and the optical rotation means 7 is provided with one of the divided beam groups (m = + 1, −2). ) Can be used to transmit a single half-wave plate, and the optical system can be simplified. The shield 29 can be made of a solid that absorbs or reflects a laser beam, such as graphite, ceramics, or metal, and can be integrated with the optical rotation means 7 and placed at the focal position f.

Embodiment 6 FIG.
FIG. 9 is a plan view showing the configuration of the laser processing apparatus according to the sixth embodiment of the present invention, showing the arrangement of the optical system viewed from the x direction, except for the difference in the arrangement of the optical path length or the polarization direction control means. This is basically the same as the laser process apparatus shown in FIGS. 6 (A) and 6 (B). Hereinafter, differences from the second embodiment will be mainly described.

  In the present embodiment, in the second embodiment shown in FIG. 6, a glass-made delay plate 2 is inserted into the other split beam as optical path length compensation means. As described above, the half-wave plate 7 is arranged as one optical rotation means for the one split beam, but the interposition of the half-wave plate 7 extends the optical path length of the split beam. If the optical path length differs between the two types of split beams, the imaging positions on the irradiation surface are shifted from each other, and the profile becomes unclear. In order to correct this, the other split beam is provided with a delay plate 2 that extends the optical path length as optical path length compensation means. As the delay plate 2, the same one as described in the first embodiment is used. For example, the optical glass plate is set to a thickness that produces the same optical path as the optical path length of the half-wave plate 7.

Embodiment 7 FIG.
10A and 10B are plan views showing the configuration of the laser processing apparatus according to the seventh embodiment of the present invention. FIG. 10A is a view seen from the y direction, and FIG. 10B is a view seen from the x direction.
In this embodiment mode, the laser processing apparatus shown in FIGS. 10A and 1B has a linear irradiation profile that spreads uniformly on the irradiation surface in the y direction and converges linearly in the x direction. The example which forms is shown.

  The laser process apparatus includes a laser oscillator 100, a laser beam splitting unit, a superimposing irradiation unit, and an optical delay unit 2. The laser beam splitting unit uses a cylindrical lens array 5 to obtain a desired laser beam. The beam is divided into a number of divided beams 15a to 15e, and the divided beams are imaged as an irradiation beam 19 of a linear profile on the irradiation surface 90 of the irradiation object 9 by the overlapping irradiation means.

  In the present embodiment, the laser beam splitting means includes an optical system for making the laser beam 1 from the laser oscillator 100 incident on the cylindrical lens array 5 for splitting, and a beam expanding lens 31 for making a parallel beam and y A directional collimating lens 32 and an x-directional collimating lens 33 are included, and a parallel beam from the collimating lens 33 is incident on the cylindrical lens array 5.

  The dividing cylindrical lens array 5 is a lens in which the convex lenses in the x direction in the drawing are stacked in the y direction with the cross-sectional convex lenses facing the optical axis, but the illustrated example includes five stages of cylindrical lenses 5a to 5e. As a result, the laser beam 1 from the laser oscillator 100 is one-dimensionally divided into five divided beams 15a to 15e in the beam cross section.

  The split beam from the split cylindrical lens array 5 is projected on the irradiation surface 90 by the superimposing irradiation unit, and the superimposition irradiation unit applies the split beam from the split cylindrical lens array 5 to the irradiation surface. 90 includes a transfer cylindrical lens array 51 (consisting of five stages of cylindrical lenses 51 a to 51 e), a condensing lens 62 that condenses light in the x direction, and a field lens 63.

  A split beam in the y direction from the split cylindrical lens array 5 is arranged in front of the split cylindrical lens array 5 and is incident on a separate transfer cylindrical lens array 51. The split beam from the transfer cylindrical lens array 51 has a focal point fa˜. After passing through fe, it is projected onto the irradiation surface 90 by a condenser lens 62 (cylindrical lens) that condenses in the x direction, and is applied to the irradiation beam 19 having a linear profile that is uniform in the y direction and thinly converged in the x direction. It is to be molded. Further, a field lens 63 is disposed between the transfer cylindrical lens array 51 and the condenser lens 62.

  A delay plate 2 is inserted as an optical delay means in the split beams 15a to 15e split in the y direction from the split cylindrical lens array 5, but the delay plate 2 (delay plates 2a, 2c, 2e) It is inserted into every other split beam 15a, 15c, 15e and not inserted into the other split beams 15b, 15d. As a result, interference on the irradiation surface 90 between the adjacent split beams (for example, between the split beams 15a and 15b or between the split beams 15b and 15c) is suppressed, and interference of the superimposed irradiation beams is suppressed. Accordingly, the intensity distribution can be made uniform.

  Further, since the M2 value of the laser oscillator 100 is set to at least N / 2 or more with respect to the division number N, the spatial coherent length X is N / 2 or less as described in the first embodiment. Although there is no difference in the optical path length, interference between one or more divided components, for example, between the divided beams 15a and 15c, between the divided beams 15a and 15d, and between the divided beams 15a and 15a, Interference between the split beams 15b and 15d, between the split beams 15b and 15e, and between the split beams 15c and 15e is suppressed during 15e. As a result, a uniform top hat beam can be obtained.

Now, in the case of the division by the waveguide shown in the first embodiment, the divided beams are overlapped so as to be folded at the boundary line. As a result, since light components at the same spatial location are overlapped at the boundary, strong interference is observed at the end as seen in FIG. On the other hand, in the configuration according to this embodiment shown in FIG. 10 using the cylindrical lens array 5, the divided beams are superimposed in parallel. In other words, when overlapping on the irradiation surface 90, there is no folding, and only superimposition. That is, light at the same spatial position is not superimposed, and if the beam diameter is 1, components that are always separated by 1 / N or more are superimposed. The interference suppression effect by this is large, and effectively,
M2 ≧ N / 2
It has been found that the interference between the divided components (between two adjacent elements) can be sufficiently suppressed if the above condition is established.

In the above description, the case where the lens array is used for the division of the laser beam and the overlapping irradiation on the irradiation surface of each divided beam has been described. However, the present invention is not limited to this. For example, an optical system using a prism, a diffraction grating, a hologram, or the like that divides the divided beams in parallel to achieve homogenization can be used. Optical delay means for delaying one of the adjacent adjacent divided beams longer than the temporal coherence distance of the laser beam with respect to the other, and M2 ≧ N / 2
By doing so, it is possible to prevent interference between all the divided beams due to superposition.
Further, every other delay plate 2 is inserted into every N divided beams, and the M2 value is set to N / 2 or more. As shown in Patent Documents 3 and 4, all of the divided beams are used. Since there is no need to provide an optical path difference, the configuration and adjustment are simple and easy. In addition, by setting the M2 value to N / 2 or more, interference between two beams other than those adjacent to each other can be reliably suppressed, so that stable homogeneous irradiation can be performed.

Embodiment 8 FIG.
11A and 11B are plan views showing the configuration of the laser processing apparatus according to the eighth embodiment of the present invention. FIG. 11A is a view seen from the y direction, and FIG. 11B is a view seen from the x direction.
In this embodiment mode, the laser process apparatus shown in FIGS. 11A and 11B spreads in a uniform distribution in the y direction on the irradiation surface and extends in the x direction as in the case of the seventh embodiment. An example of forming a linear irradiation profile converged linearly is shown.

In the seventh embodiment, when the delay plate (optical delay means) 2 is used as the optical path length or polarization direction control means for changing the optical path length or polarization direction of adjacent split beams adjacent to each other of the N divided beams. However, in this embodiment, the optical rotation means 7 is used to make one of the adjacent split beams adjacent to each other divided into N beams substantially orthogonal to the polarization direction with respect to the other.
Since other configurations are the same as those in the seventh embodiment, differences from the seventh embodiment will be mainly described below.

  Half-wave plates 7 are inserted in the split beams 15a to 15e split in the y direction from the split cylindrical lens array 5 as optical rotation means. The half-wave plate 7 is provided with every other split beam 15a, 15c, It is inserted into 15d and not inserted into the other split beams 15b and 15d. Thereby, between the split beams adjacent to each other (for example, between the split beams 15a and 15b, between the split beams 15b and 15c, or between other adjacent split beams), the polarization angle is substantially orthogonal, Interference on the irradiation surface 90 is suppressed, and the intensity distribution due to interference of the superimposed irradiation beams 19 can be made uniform.

As described above, when every other half-wave plate 7 is inserted into the divided beams, interference is prevented between two divided beams of any combination adjacent to each other (for example, between the divided beams 15a and 15c). However, interference between two beams other than those adjacent to each other (for example, between the split beams 15a and 15c) cannot be prevented.
Therefore, in the present embodiment as well, as described in the seventh embodiment, by setting the M2 value, which is an index indicating the condensing property of the beam generated from the laser oscillator 100, to N / 2 or more, Interference between all split beams is suppressed.

Embodiment 9 FIG.
FIG. 12 is a plan view showing the configuration of the laser processing apparatus according to the ninth embodiment of the present invention, showing the arrangement of the optical system viewed from the x direction, except for the difference in the arrangement of the optical path length or the polarization direction control means. This is basically the same as the laser process apparatus shown in FIGS. 11 (A) and 11 (B). In the following, differences from the eighth embodiment will be mainly described.

  In this embodiment, in the eighth embodiment shown in FIG. 11, the glass for the delay plate 2 is used as the optical path length compensation means for the other split beam (15b, 15d in this example) into which the optical rotation means is not inserted. Inserting the body. As described above, the half-wave plate 7 is arranged as one optical rotation means in the above-mentioned one split beam. However, the interposition of the half-wave plate 7 extends the optical path length of the split beam, so that If the optical path lengths of the split beams are different, the imaging positions on the irradiation surface are shifted from each other, and the profile becomes unclear. In order to correct this, a delay plate 72 for extending the optical path length is inserted in the other split beam as means for compensating the optical path length. As the delay plate 2, the same one as described in the first embodiment is used. For example, the optical glass plate is set to a thickness that produces the same optical path length as that of the half-wave plate 7.

  In the y-direction transfer cylindrical lens array 51, different focal lengths are used for the micro cylindrical lens for the split beam with the half-wave plate 7 inserted therein and the micro cylindrical lens for the split beam without the half-wave plate 7 inserted. The optical path length may be compensated by providing.

Embodiment 10 FIG.
13A and 13B are diagrams showing the configuration of the laser processing apparatus according to the tenth embodiment of the present invention. FIG. 13A is a plan view seen from the y direction, FIG. 13B is a plan view seen from the x direction, and FIG. It is sectional drawing of a delay plate.
In the present embodiment, the laser process apparatus shown in FIGS. 13A and 13B spreads in a uniform distribution in the y direction on the irradiation surface and in the x direction, as in the first embodiment. An example of forming a linear irradiation profile converged linearly is shown.

  The laser process apparatus includes a laser oscillator 100, a laser beam splitting unit, a superimposing irradiation unit, and an optical delay unit. The laser beam splitting unit orthogonally crosses the x-direction cylindrical lens array and the y-direction cylindrical lens array. Thus, split beams divided two-dimensionally are formed. As another laser beam splitting means, a two-dimensional lens array can also be used. In this case, instead of the x-direction cylindrical lens array 5 and the y-direction cylindrical lens array 52, a single two-dimensional lens array is used. It is possible to form a split beam two-dimensionally in the xy direction. In addition, it is a rectangular parallelepiped having four main reflecting surfaces around the axis connecting the incident surface and the emitting surface, and the four reflecting surfaces reflect the laser beam introduced from the incident surface. A two-dimensional waveguide that emits a split beam can also be used from the exit surface.

In the present embodiment, the x-direction cylindrical lens array 5 and the y-direction cylindrical lens array 52 are arranged orthogonally to form a large number of two-dimensionally separated beams in parallel.
The laser beam splitting means further includes a magnifying lens 51 and a collimating lens 32 for making the laser beam incident on the cylindrical lens array 5, and an expanded parallel laser beam is incident on the cylindrical lens array 5.

  The superimposing irradiation means superimposes a number of divided beams on the irradiation surface 90 of the irradiation object 9 to form an irradiation beam. Here, the superimposing irradiation means is a cylindrical cylinder for transfer in the y direction. The lens array 51 is focused in the x direction by the cylindrical lens array 5 and the x direction condenser lens 62 (cylindrical lens) in the x direction so that it can be transferred onto the irradiation surface over a predetermined length. As a result, an image is formed on the irradiation beam having a linear profile on the irradiation surface.

In the present embodiment, the laser beam 1 is incident on the cylindrical lens array 5 for splitting by a magnifying lens 31 and a collimating lens 32 as laser beam splitting means. In this example, the split beam is split into five in the x direction. Are then further divided by the y-direction cylindrical lens array 52 in the y-direction, and the two-dimensionally divided beam having the number of divisions N _x × N _y in two directions, the x-direction and the y-direction. Get. The number of divisions N _x and N _y is preferably set to an appropriate number of 5 or more, and particularly preferably 7 or more. In this embodiment, the number of divisions N _x × N _y is a two-dimensional division beam having a combination of 5 × 5.

  Each of the two-dimensional split beams has a rectangular cross section and is parallel to each other, and then passes through the delay plate 2 as an optical delay means and enters the y-direction transfer cylindrical lens array 51, and Transfer to a certain length on the irradiation surface 90.

  As shown in FIG. 13C, the delay plate 2 is configured by alternately arranging the delay elements 20 and the gaps 290. The delay elements 20 are made of a small glass plate having a constant thickness, and the gaps 290 are simply air. Is a layer. Specifically, the delay elements 20 and the gaps 290 are alternately arranged in the y direction on the delay plate, and the delay elements 20 and the gaps 290 are alternately arranged also in the x direction.

  In the arrangement of the delay elements 20 in the delay plate 2, one of the split beams adjacent to each other passes through the delay element, the other passes through the air layer in the gap, and an optical path difference is provided between them. Yes. Originally, the split beams adjacent to each other interfere with each other when irradiated on the irradiation surface. However, the arrangement of the delay elements of the delay plate is made by superimposing irradiation means including the cylindrical lens array 51 for transfer in the y direction. Interference between split beams irradiated on the irradiation surface is reduced, and fluctuations in the combined irradiation beam are prevented.

As described above, when every other delay element 20 is inserted into the divided beams, interference is prevented between two divided beams of any combination adjacent to each other, but two other than adjacent to each other. Interference between the two beams cannot be prevented.
Therefore, in the present embodiment as well, as described in the seventh embodiment, the M2 value that is an index representing the condensing property of the beam generated from the laser oscillator 100 is set to N _x / 2 in each division direction. By making the above and N _y / 2 or more, interference between all split beams is suppressed.

When the laser beam from the laser oscillator is two-dimensionally divided into N _x × N _y divided beams in the beam cross section using a two-dimensional waveguide, the M2 value in each division direction is expressed as N _x / 2. By making the above and N _y / 2 or more, more desirably N _x or more and N _y or more, interference between all the divided beams can be suppressed.

  In addition, by arranging the optical delay means before and after the transfer cylindrical lens array 51 separately for the first delay plate and the second delay plate, the surface to which the divided beam is transferred and the surface to be transferred are conjugated. There is an advantage that the influence of diffraction on the irradiation surface can be minimized. Further, a third delay plate is arranged as a delay means between the cylindrical lens array 53 and the x-direction condenser lens 62, and an optical path difference Δa is provided between the adjacent divided beams separated in the x direction. Thus, mutual interference on the irradiated surface may be reduced.

Embodiment 11 FIG.
14A and 14B are diagrams showing a configuration of a laser processing apparatus according to an eleventh embodiment of the present invention. FIG. 14A is a plan view seen from the y direction, FIG. 14B is a plan view seen from the x direction, and FIG. It is sectional drawing of a half-wave plate.
In the tenth embodiment, the case where the optical delay means (delay plate 2) is used as the optical path length or polarization direction control means for changing the optical path length or polarization direction of adjacent split beams adjacent to each other has been described. An optical rotation means that makes the polarization direction substantially orthogonal to the other may be used. In this case, the M2 value in each division direction is set to N _x / 2 or more and N _y / 2 or more. Interference between all split beams can be suppressed.

  As such an optical rotation means 7, as shown in FIG. 14C, an optical rotation plate 7 in which optical rotation elements 70 and gaps 290 are alternately arranged in the x direction and the y direction is used. The optical rotation plate 7 is disposed in front of the dividing cylindrical lens arrays 5 and 52 so that the divided beam passes through the optical rotator 70 and the adjacent divided beam passes through the gap 290. Thereby, the polarization planes of adjacent split beams are substantially orthogonal. The optical rotator 70 of the optical rotator 7 is preferably made of an optical rotatory material, preferably a crystal single crystal, and is optically a half-wave plate, as shown in FIG. Arranged.

Note that the split beam into which the optical rotatory element 70 of the optical rotator 7 is inserted is compared with the split beam that passes only through the gap, so that the optical rotation surface is rotated and the optical path length is increased. On the upper side, a deviation of the imaging position due to the difference in optical path length with the split beam occurs.
Therefore, instead of the optical path length compensation delay element in the gap 290 in FIG. 14C, the optical rotation elements 70 and the optical path length compensation delay elements may be alternately arranged. An optical glass plate is used for the optical path length compensation delay element, and the thickness a of the optical path length compensation delay element is substantially equal to the optical path length generated by the quartz half-wave plate as the optical rotation element 70. To be decided. Due to the compensation of the optical path length, there is no deviation of the imaging position by the cylindrical lens array for transfer between the adjacent split beams, thereby obtaining a clear image and the irradiation beam on the irradiation surface A more uniform intensity distribution can be obtained.
Further, in the cylindrical lens array 51 for y-direction transfer, a micro cylindrical lens that allows the split beam that passes through the optical rotator 70 of the optical rotation plate 7 to pass, and a micro cylindrical lens that allows the split beam that passes through the air gap 290, which is an air layer, to pass. In addition, the optical path length may be compensated by providing different focal lengths.

Embodiment 12 FIG.
15A and 15B are diagrams showing a configuration of a laser processing apparatus according to a twelfth embodiment of the present invention. FIG. 15A is a plan view seen from the y direction, FIG. 15B is a plan view seen from the x direction, and FIG. Sectional drawing of a half-wave plate, (D) is sectional drawing of a delay plate.

  A delay unit that transmits the split beam and an optical rotation unit are arranged in front of the laser beam splitting unit, so that interference on the irradiation surface between the split beams adjacent to each other can be prevented. In the example shown in FIG. 7A and FIG. 7B, both the optical rotation plate 7 and the delay plate 2 are arranged in front of the dividing cylindrical lens arrays 5 and 52, and in front of them. The cylindrical lens array 51 for y-direction transfer, the field lens 63, the transfer cylindrical lens array 62 for x-direction, and the x-direction condensing lens 62 are arranged, and the irradiated split beam passing through the irradiation surface 90 is irradiated to form a line. An irradiation beam 19 of a profile is obtained.

  In this example, the optical rotatory plate 7 is arranged with the optical rotatory elements 70 and the gaps 290 alternately in the x direction and separately in the y direction. As a result, the split beams from the split cylindrical lens arrays 5 and 52 are orthogonally polarized between the adjacent split beams in the x direction by the optical rotation plate 7, but the polarization angles are not changed in the y direction. As a result, the polarization angle can be rotated between a certain split beam and a split beam adjacent to the split beam in an oblique direction. Since the optical rotator 70 of the optical rotator 7 does not change the polarization angle in the y direction, the delay plate 2 disposed in front of the optical rotator 7 has the same configuration as that of the tenth embodiment in order to compensate for this. The delay elements 20 and the air gaps 290 are alternately arranged in the x direction and the y direction, and an optical path difference Δa is provided between the split beams adjacent in the x direction and the y direction.

  Therefore, the arrangement of the optical rotation plate 7 and the delay plate 2 reduces the interference due to the optical path difference due to the delay plate 2 for the split beams adjacent in the x direction and the y direction, and for the split beams adjacent in the oblique direction. Interference is prevented by optical rotation by an optical rotation plate, whereby a certain split beam and all adjacent split beams surrounding it can reduce mutual interference.

In each of the above embodiments, the solid laser having a long spatial coherence distance and its harmonic laser have been described as examples of the laser light source. However, a CO ₂ laser having high coherence like the solid laser, The same effect can be obtained even when applied to Ar lasers, other gas lasers, and semiconductor lasers. On the other hand, an excimer laser is currently applied to a method for polycrystallizing silicon. Here, the laser light source is homogenized by simply dividing the lens using a lens array and simply superimposing them. While the excimer laser has an oscillation wavelength in the ultraviolet region, the beam extraction cross section is structurally as large as several centimeters, and the M2 value is sufficiently greater than at least 100 in a system to which a normal stable oscillator is applied. If it is large, it is on the order of more than 1000, and the spatial coherent length is extremely short. Further, since the spectrum width is extremely wide, the temporal coherent length is also short. In that sense, excimer lasers are exceptional as a laser light source characterized by a long temporal and spatial coherence length. Most lasers other than excimer lasers are used to emit a homogeneous beam. The present invention can be applied.

It is a top view which shows the structure of the laser process apparatus by Embodiment 1 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is sectional drawing explaining the aspect of the division | segmentation of the laser beam in a waveguide. It is a figure explaining the aspect of the division | segmentation of the laser beam in a waveguide. It is a figure which shows the intensity distribution of the synthetic | combination irradiation beam when the two division beams adjacent to each other divided by the waveguide are overlapped on the irradiation surface. It is a figure which shows the relationship between M2 value and spatial coherence distance. It is a top view which shows the structure of the laser process apparatus by Embodiment 2 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 4 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 5 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 6 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 7 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 8 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a top view which shows the structure of the laser process apparatus by Embodiment 9 of this invention, (A) is the figure seen from the y direction, (B) is the figure seen from the x direction. It is a figure which shows the structure of the laser processing apparatus by Embodiment 10 of this invention, (A) is the top view seen from the y direction, (B) is the top view seen from the x direction, (C) is a delay board. It is sectional drawing. It is a figure which shows the structure of the laser process apparatus by Embodiment 11 of this invention, (A) is the top view seen from the y direction, (B) is the top view seen from the x direction, (C) is a half-wave plate FIG. It is a figure which shows the structure of the laser process apparatus by Embodiment 12 of this invention, (A) is the top view seen from the y direction, (B) is the top view seen from the x direction, (C) is a half-wave plate (D) is sectional drawing of a delay plate.

Explanation of symbols

100 laser oscillator, 2 delay plate, 20 delay element, 29 shield, 290 gap, 31 beam expansion lens, 32 y-direction collimating lens, 33 x-direction collimating lens, 34 focusing lens, 4 waveguide, 41 reflecting surface, 42 Reflective surface, 5 split cylindrical lens array, 51 transfer cylindrical lens array, 61 transfer lens, 62 condenser lens, 7 half-wave plate (optical rotator), 70 optical rotator, 9 irradiated object, 90 irradiated surface.

Claims (5)

At least one laser oscillator that generates a laser beam having an M2 value of 100 or less, which is an index indicating the condensing property of a beam generated from the laser oscillator, and N spatially laser beams from the laser oscillator in the beam cross section. Laser beam splitting means for splitting the beam into split beams, superimposing irradiation means for irradiating the split beams approximately on the irradiation surface, and optical path lengths of adjacent split beams adjacent to the N split beams. And optical delay means for delaying one of the adjacent split beams with respect to the other longer than the temporal coherence distance of the laser beam, and the M2 value is at least of the beam. In the dividing direction M2 ≧ N / 2
A laser process apparatus characterized by the above. 2. The laser processing apparatus according to claim 1, wherein the laser beam splitting unit splits the laser beam from the laser oscillator into N split beams spatially in a beam cross section using mutually opposing reflecting surfaces. 2. The laser beam splitting unit splits a laser beam from a laser oscillator into N split beams in a one-dimensional or two-dimensional manner in a beam cross section using reflection surfaces facing each other. Laser process equipment. The M2 value is at least M2 ≧ N in the beam splitting direction
The laser process apparatus according to claim 2, wherein 2. The laser process apparatus according to claim 1, wherein the laser oscillator generates a fundamental wave or a harmonic of a solid-state laser or a semiconductor laser.

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