JP2004095792A - Unified laser beam irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unified laser beam irradiation apparatus which has reduced swell resulting from the interference generated when a plurality of laser beams are overlapped. <P>SOLUTION: A laser beam emitted from a laser source is incident to a first lens array. The first lens array divides the incident laser beam to a plurality of beams in regard to a first direction with a plurality of lenses arranged in the first direction crossing the travelling direction of the laser beam. A first polarized control means changes the polarizing condition of the laser beam to provide different polarizing conditions of the two laser beams having passed the adjacent lenses. A condenser lens overlaps a plurality of beams divided by the first lens array on the surface to be irradiated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniformized laser beam irradiation apparatus, and more particularly, to a uniformed laser beam that divides one laser beam into a plurality of beams using a lens array, makes the divided beams incident on a common area, and overlaps them. The present invention relates to an irradiation device.
[0002]
[Prior art]
Laser beams are used for various applications. In crystallization annealing and photolithography of amorphous silicon, a laser beam having a uniform intensity distribution in a target region is desired. Laser beams are inherently coherent. When beams having different optical paths are superimposed on each other, interference occurs and an undulation (speckle pattern) occurs. Further, the intensity of the laser beam is generally not uniform within the beam cross section. The strength at the center is high and the strength at the periphery is low.
[0003]
As a technique for forming a laser beam having a uniform intensity distribution, a method using a lens array is known. A laser beam emitted from a laser light source is divided into a plurality of beams by a lens array, and the divided laser beams are superimposed on a surface to be irradiated, so that the intensity distribution can be made uniform.
[0004]
[Patent Document 1]
JP-A-11-16851
[0005]
[Problems to be solved by the invention]
If laser beams having good coherence are to be made uniform by the lens array, the divided laser beams may interfere with each other when they are superimposed, resulting in a speckle pattern. When an excimer laser is used as a laser light source, its spatial coherence length is short, so that a speckle pattern hardly occurs. However, when using a laser light source having a long spatial coherence length, for example, a solid-state laser such as Nd: YAG, a speckle pattern is likely to occur.
[0006]
In a stepper or the like for photolithography, the influence of the swell of intensity due to interference is eliminated by vibrating a mirror at the previous stage of the lens array and integrating power densities of a plurality of shots. However, according to this method, when only one shot is irradiated, the influence of the undulation of the intensity cannot be excluded.
[0007]
An object of the present invention is to provide a uniformized laser beam irradiation apparatus capable of reducing the swell of intensity caused by interference when a plurality of laser beams are superimposed.
[0008]
[Means for Solving the Problems]
According to one aspect of the present invention, a laser light source that emits a laser beam, and a plurality of lenses that receive a laser beam emitted from the laser light source and are arranged in a first direction that intersects with the traveling direction of the laser beam. A first lens array that divides an incident laser beam into a plurality of beams in a first direction, and a polarization state of two laser beams that have passed through adjacent lenses of the first lens array. A first polarization state control means for changing the polarization state of the laser beam, and a superposition optical system for superposing a plurality of beams split by the first lens array on a surface to be irradiated. A uniformized laser beam irradiation device is provided.
[0009]
By making the polarization states of two laser beams that have passed through mutually adjacent lenses different from each other, the influence of interference when the two laser beams are superimposed can be reduced, and the occurrence of a speckle pattern can be suppressed.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1A is a sectional view of a beam homogenizing optical system according to an embodiment of the present invention. A laser beam 1 emitted from a solid-state laser light source such as a Nd: YAG laser or an Nd: YLF laser enters a lens array 2. The laser beam 1 incident on the lens array 2 is linearly polarized and has a diameter D. The intensity distribution of the laser beam 1 at the incident position of the lens array 2 is approximated by, for example, a Gaussian distribution. An XYZ orthogonal coordinate system in which the traveling direction of the laser beam 1 is the Z axis is introduced. It is assumed that the polarization direction of the laser beam 1 is parallel to the X axis.
[0011]
The lens array 2 includes a plurality of convex cylindrical lenses. Each cylindrical lens has a convex columnar surface composed of a generatrix parallel to the Y-axis, and is arranged in close contact with each other at a pitch h in the X-axis direction. The laser beam 1 is divided by the lens array 2 into a plurality of laser beams 3 converging in the ZX plane. Each laser beam 3 is condensed on a straight line parallel to the Y axis at the focal point of the cylindrical lens, and then becomes a light beam diverging in the ZX plane and enters the condenser lens (superposition optical system) 4.
[0012]
The condenser lens 4 causes the plurality of laser beams 3 to be incident on a common irradiation area 5 </ b> A on the homogenization surface 5. By superimposing a plurality of laser beams 3 having different intensity distributions on the homogenized surface 5, the intensity distribution can be made uniform.
[0013]
A polarization state control element 6 is disposed between the lens array 2 and the condenser lens 4. The polarization state control element 6 is constituted by a half-wave plate 6A arranged in every other path in the X-axis direction among paths of the plurality of laser beams 3 passing through the lenses constituting the lens array 2. . In FIG. 1A, when numbers are sequentially assigned to each lens from the bottom to the top from 1 in the figure, a half-wave plate 6A is arranged in the path of the laser beam passing through the odd-numbered lens. ing.
[0014]
FIG. 1B is a front view of the polarization control element 6. Four half-wave plates 6A long in the Y-axis direction are arranged in the X-axis direction. The width of each half-wave plate 6A and the interval between the adjacent half-wave plates 6A are equal to the pitch h of the lens array 2. The slow axis 6S and the fast axis 6F of each half-wave plate 6A are inclined by 45 ° from the X-axis direction, that is, the polarization direction of the incident laser beam 1. Therefore, the polarization direction 10A of the laser beam transmitted through the half-wave plate 6A is parallel to the Y axis. On the other hand, the polarization direction 10B of the laser beam passing between the half-wave plates is parallel to the X axis.
[0015]
Returning to FIG. 1A, the description will be continued. Since the polarization directions of the laser beam 3 that has passed through the two lenses adjacent to each other in the X-axis direction are orthogonal to each other, no interference occurs even when both are superimposed.
[0016]
When a plurality of laser beams split by the lens array 3 have coherence, a speckle pattern occurs. When an arbitrary two laser beams among a plurality of laser beams split by the lens array 2 are superimposed, an angle formed by both central rays is α, and a wavelength of the laser beam is λ, a pitch P of a speckle pattern is obtained. Is
[0017]
(Equation 1)
P = λ / (2 × sin (α / 2)) (1)
It becomes.
[0018]
Since the angle α formed by the center light beam differs depending on the combination of the focused laser beams, speckle patterns having various pitches P are formed. When the polarization state controlling element 6 is not arranged, the combination of the laser beams adjacent to each other is the largest, and the coherence is the highest, so that the combination is based on the angle α formed by the central rays of the laser beams adjacent to each other. The speckle pattern of the pitch P appears most strongly. Since the polarization controlling element 6 is disposed in the uniforming optical system shown in FIG. 1, a speckle pattern caused by laser beams adjacent to each other does not appear.
[0019]
In FIG. 1A, the polarization state control element 6 is disposed at a position where the laser beam 3 is converged and its thickness in the X-axis direction is reduced. For this reason, the half-wave plate 6A can be arranged with a sufficient margin without the half-wave plate 6A penetrating into the passage of the adjacent laser beam. If the half-wave plate 6A is arranged at the condensing position of the laser beam 3, a larger margin can be secured.
[0020]
If the positional accuracy of the half-wave plate can be increased, the polarization state control element 6 may be arranged in front of the lens array 2.
[0021]
Hereinafter, interference by a laser beam that has passed through two lenses of the lenses constituting the lens array 2 that are arranged at an interval h will be considered. One of the parameters representing the characteristics of the laser beam is a spatial coherence length. Spatial coherence length is the maximum length that interferes with each other within the same beam. That is, beam elements passing through two points having an interval larger than the spatial coherence length do not have mutual interference. Conversely, beam elements passing through two points having an interval smaller than the spatial coherence length interfere with each other.
[0022]
As described above, by arranging the polarization state control element 6, it is possible to prevent interference between laser beams whose optical paths are adjacent to each other. Next, a method for preventing interference between two laser beams arranged one optical path apart from each other will be described.
[0023]
The pitch in the X-axis direction of a plurality of cylindrical lenses constituting the lens array 2 is h, and the spatial coherence length of the laser beam is Xc. Since the center-to-center distance between the two lenses arranged at an interval h is 2h,
[0024]
(Equation 2)
Xc <2h (2)
When satisfies, the two laser beams do not interfere.
[0025]
Assuming that the minimum beam spot that can be collected by the aberration-free lens having the focal length f is d, the following relational expression is established.
[0026]
[Equation 3]
d ≒ 2.44λf / Xc (3)
When the minimum beam spot that can be focused is d, the quality index M of the laser beam ² Is defined by the following equation.
[0027]
(Equation 4)
M ² = (Π / 4λ) dθ (4)
Here, θ is the far-field spread angle. Assuming that the diameter of the laser beam incident on the lens array 2 is D,
[0028]
(Equation 5)
θ ≒ D / f (5)
Considering that
[0029]
(Equation 6)
Xc ≒ 0.61πfθ / M ² = 0.61πD / M ² ... (6)
Holds. From Expression (6) and Conditional Expression (2) that does not cause interference,
[0030]
(Equation 7)
M ² > 0.61πD / (2h) (7)
Is obtained. Therefore, the quality index M of the laser beam ² When the optical system is designed so that the beam diameter D and the pitch h of the lens array 2 satisfy the conditional expression (7), two lens arrays 2 arranged at an interval h (center distance 2h) are arranged. Interference between laser beams passing through the cylindrical lens can be prevented, and the uniformity of the intensity of the beam irradiation area on the homogenized surface 5 can be increased.
[0031]
If the distance between two points through which the beam passes exceeds the spatial coherence length Xc, coherence is not completely eliminated, but coherence may remain slightly. Therefore, assuming that the safety factor is κ> 1,
[0032]
(Equation 8)
M ² > 0.61κπD / (2h) (8)
May be designed to satisfy.
[0033]
For example, if the diameter D of the laser beam incident on the lens array 2 is 45 mm and the pitch h of the lens array is 5 mm, M ² > 8.63κ is obtained. If the safety factor κ is 1.2, then M ² > 10.4. That is, the quality index M ² Is selected to be larger than 10.4, it is possible to prevent the generation of a speckle pattern due to interference between laser beams having a center-to-center distance of 2 h.
[0034]
Conversely, the quality index M ² If a laser light source with a value of 10 is used and the safety factor κ is 1.2, h> 0.12D. That is, if the number of cylindrical lenses constituting the lens array 2 is nine and the laser beam is divided into nine, the occurrence of a speckle pattern can be prevented. When the diameter of the laser beam emitted from the laser light source is 5 mm, and the laser beam is enlarged eight times with a telescope to make the beam diameter 40 mm and incident on the lens array 2, if h> 4.8 mm, Good.
[0035]
In equations (7) and (8), the quality index M of the laser beam ² The upper limit of is not limited. However, the quality index M ² Becomes larger, the minimum beam spot that can be collected becomes larger. When the laser beam is focused on a linear area, the focused linear area cannot be made thin. Assuming that the width of the focused linear region is w and the focal length of the condenser lens is f, the quality index M ² Is defined by the following equation.
[0036]
(Equation 9)
M ² ≦ (π / 4λ) w (D / f) (9)
FIG. 2 shows another configuration example of the polarization state control element 6. In FIG. 1B, the slow axis 6S and the fast axis 6F of the half-wave plate 6A constituting the polarization control element 6 are inclined by 45 ° from the X axis. In the polarization control element 6 shown in FIG. 2, the slow axis 6S of the half-wave plate 6A is parallel to the Y axis, and the fast axis 6F is parallel to the X axis. Instead, the polarization direction of the laser beam 1 incident on the lens array 2 is inclined by 45 ° from the X axis.
[0037]
Therefore, the polarization direction 10B of the laser beam that has passed between the half-wave plates 6A is inclined by 45 ° from the X axis in the same direction as the polarization direction of the original laser beam 1. The polarization direction 10A of the laser beam that has passed through the half-wave plate 6A is inclined by 45 ° from the X axis in a direction opposite to the polarization direction 10B of the laser beam that has passed between the half-wave plates 6A. Therefore, the polarization directions of the two laser beams passing through the lenses adjacent to each other are orthogonal to each other. Note that the first axis 6F may be arranged so as to be parallel to the Y axis.
[0038]
In the half-wave plate 6A shown in FIG. 2, since the slow axis 6S or the fast axis 6F is parallel to the longitudinal direction of the half-wave plate 6A, the manufacture of the half-wave plate becomes easy.
[0039]
In the above embodiment, the polarization directions of the laser beams passing through the lenses adjacent to each other of the lens array 2 are made orthogonal. By making the polarization directions orthogonal, the influence of interference between the two laser beams can be almost completely eliminated. Even when the polarization directions of the two laser beams are not orthogonal, if the polarization states of the two laser beams are different, the influence of interference can be reduced as compared with the case where the polarization states of the two laser beams are the same. .
[0040]
In the above-described embodiment, the half-wave plate 6A is disposed in every other path of the laser beam passing through the plurality of lenses constituting the lens array 2 in the X-axis direction. Since the laser beams adjacent to each other are most likely to interfere with each other, the greatest effect is expected by arranging the half-wave plates 6A every other one. However, even if a half-wave plate is arranged in the path of a laser beam that has passed through an arbitrary part of the lens rather than every other lens, the influence of interference is greater than when a polarization state control element is not arranged. Could be reduced.
[0041]
3A and 3B are cross-sectional views of a beam homogenizing optical system (beam homogenizer) combining a plurality of lens arrays. An xyz orthogonal coordinate system with the traveling direction of the laser beam as the z-axis is introduced. FIG. 3A is a sectional view parallel to the yz plane, and FIG. 3B is a sectional view parallel to the xz plane.
[0042]
As shown in FIG. 3A, seven equivalent cylindrical lenses are arranged in a direction parallel to the x-axis and in the y-axis direction, and are arranged in a cylinder array along a virtual plane parallel to the xy plane. 45A and 45B are configured. The optical axis plane of each of the cylindrical lenses of the cylinder arrays 45A and 45B is parallel to the xz plane. Here, the optical axis plane means a plane of symmetry of a plane-symmetric imaging system of a cylindrical lens (a plane of symmetry of an imaging system including a center line of curvature of a cylindrical surface of a cylindrical lens). The cylinder array 45A is arranged on the light incident side (left side in the figure), and the cylinder array 45B is arranged on the light emission side (right side in the figure).
[0043]
As shown in FIG. 3 (B), equivalent seven cylindrical lenses have their generatrix directions arranged parallel to the y-axis and arranged in the x-axis direction, and a cylinder array 46A along a virtual plane parallel to the xy plane. And 46B are constituted. The optical axis plane of each of the cylindrical lenses of the cylinder arrays 46A and 46B is parallel to the yz plane. The cylinder array 46A is arranged in front of the cylinder array 45A (left side in the figure), and the cylinder array 46B is arranged between the cylinder arrays 45A and 45B. The optical axis planes of the corresponding cylindrical lenses of the cylinder arrays 45A and 45B match, and the optical axis planes of the corresponding cylindrical lenses of the cylinder arrays 46A and 46B also match.
[0044]
A polarization state control element 45C is disposed behind (to the right of the figure) the lens array 45B. A polarization state control element 46C is arranged between the cylinder arrays 46A and 46B. The polarization state control elements 45C and 46C have the same configuration as the polarization state control element 6 shown in FIGS. 1A and 1B or the polarization state control element 6 shown in FIG.
[0045]
A condenser lens 49 is disposed behind the polarization state control element 45C. The optical axis of the condenser lens 49 is parallel to the z-axis.
[0046]
With reference to FIG. 3A, the state of propagation of a light beam in the yz plane will be described. In the yz plane, since the cylinder arrays 46A and 46B are merely flat plates, they do not affect the convergence and divergence of the light beam. When the x-coordinate of a cross section parallel to the yz plane is fixed, the polarization state of the laser beam that has passed through the polarization state control element 46C is uniform in the y-axis direction.
[0047]
A parallel light beam 47 having an optical axis parallel to the z-axis is incident on the cylinder array 46A from the left side of the cylinder array 46A. The parallel light beam 47 has a light intensity distribution that is strong at the center and weak at the periphery, as shown by a curve 51y, for example.
[0048]
The parallel light beam 47 passes through the cylinder array 46A and enters the cylinder array 45A. The incident light beam is divided by the cylinder array 45A into seven focused light beams corresponding to each cylindrical lens. In FIG. 3A, only the light beams at the center and both ends are representatively shown. The seven converged light beams have light intensity distributions indicated by curves 51ya to 51yg, respectively. The light beam focused by the cylinder array 45A is focused again by the cylinder array 45B.
[0049]
The polarization state of the seven focused light beams 48 focused by the cylinder array 45B is controlled by the polarization state control element 45C, and forms an image in front of the focusing lens 49. This image forming position is closer to the lens than the focal point on the incident side of the condenser lens 49. Therefore, the seven light beams transmitted through the condenser lens 49 become divergent light beams, respectively, and overlap on the homogenizing surface 50. The light intensity distribution in the y-axis direction of the seven light beams that irradiate the homogenized surface 50 is equal to the distribution obtained by extending the light intensity distributions 51ya to 51yg in the y-axis direction. Since the light intensity distributions 51ya and 51yg, 51yb and 51yf, and 51yc and 51ye each have an inverted relationship with respect to the y-axis direction, the light intensity distribution obtained by superimposing these light fluxes is uniform as shown by a solid line 52y. Approach distribution.
[0050]
Further, since the polarization state control element 45C is disposed, laser beams passing through the cylindrical lenses adjacent to each other of the cylinder arrays 45A and 45C do not interfere with each other. For this reason, generation of a speckle pattern in the y-axis direction can be prevented.
[0051]
With reference to FIG. 3B, the state of propagation of a light beam in the xz plane will be described. In the xz plane, since the cylinder arrays 45A and 45B are simply flat plates, they do not affect the convergence and divergence of the light beam. The parallel light beam 47 is incident on the cylinder array 46A. The parallel light beam 47 has a light intensity distribution that is strong at the center and weak at the periphery, for example, as shown by a curve 51x.
[0052]
The parallel light beam 47 is divided by the cylinder array 46A into seven focused light beams corresponding to the respective cylindrical lenses. In FIG. 3B, only the light beams at the center and both ends are shown as a representative. Each of the seven focused light beams has a light intensity distribution indicated by curves 51xa to 51xg.
[0053]
Each light beam is controlled in its polarization state by the polarization state control element 46C, forms an image in front of the cylinder array 46B, and enters the cylinder array 46B as a divergent light beam. Each ray bundle incident on the cylinder array 46B exits at a certain exit angle, and enters the condenser lens 49.
[0054]
Each of the seven light beams transmitted through the condenser lens 49 becomes a convergent light beam and overlaps on the homogenizing surface 50. The light intensity distribution in the x-axis direction of the seven light beams irradiating the homogenized surface 50 approaches a uniform distribution as shown by a solid line 52x as in the case of FIG. Further, since the polarization state control element 46C is provided, it is possible to prevent the generation of a speckle pattern in the x-axis direction.
[0055]
The light irradiation area on the homogenized surface 50 has a linear shape that is long in the y-axis direction and short in the x-axis direction. By arranging the surface of the irradiation object at the position of the homogenized surface 50, a long linear region in the y-axis direction on the surface can be irradiated almost uniformly.
[0056]
Quality index M of laser beam incident on cylinder array 46A ² When the beam diameter D and the pitch h of the cylindrical lenses forming each cylinder array satisfy the above-mentioned conditional expression (7) or (8), the coherence between laser beams separated by the interval h disappears, and the homogenized surface The intensity distribution on the surface 50 can be made more uniform.
[0057]
FIG. 4 shows a plan view of a laser annealing apparatus using the homogenizer of FIG. The laser annealing device includes a processing chamber 40, a transfer chamber 82, loading / unloading chambers 83 and 84, a laser light source 71, a homogenizer 72, a CCD camera 88, and a video monitor 89. The homogenizer 72 is the same as the homogenizer shown in FIG. A linear motion mechanism 60 including a bellows 67, coupling members 63 and 65, a linear guide mechanism 64, a linear motor 66, and the like is attached to the processing chamber 40. The translation mechanism 60 can translate the stage 44 disposed in the processing chamber 60.
[0058]
The processing chamber 40 and the transfer chamber 82 are connected via a gate valve 85, and the transfer chamber 82 and the transfer chamber 83, and the transfer chamber 82 and the transfer chamber 84 are connected via gate valves 86 and 87, respectively. . Vacuum pumps 91, 92 and 93 are attached to the processing chamber 40 and the loading / unloading chambers 83 and 84, respectively, so that the inside of each chamber can be evacuated.
[0059]
A transfer robot 94 is accommodated in the transfer chamber 82. The transfer robot 94 transfers the processing substrate between the processing chamber 40 and the loading / unloading chambers 83 and 84.
[0060]
A quartz window 38 for transmitting a laser beam is provided on the upper surface of the processing chamber 40. Note that a visible optical glass such as BK7 may be used instead of quartz. The laser beam output from the continuously oscillated laser light source 71 enters the homogenizer 72 through the attenuator 76. The homogenizer 72 changes the cross-sectional shape of the laser beam into an elongated shape. The laser beam that has passed through the homogenizer 72 passes through an elongated quartz window 38 corresponding to the cross-sectional shape of the beam, and irradiates the processing substrate held on the stage 44 in the processing chamber 40. The relative position between the homogenizer 72 and the processing substrate is adjusted so that the surface of the substrate coincides with the homogenized surface.
[0061]
The direction in which the stage 44 is translated by the translation mechanism 60 is a direction orthogonal to the longitudinal direction of the quartz window 38. This makes it possible to irradiate the laser beam to a large area on the surface of the substrate and to polycrystallize the amorphous semiconductor film formed on the surface of the substrate. The substrate surface is photographed by a CCD camera 88, and the substrate surface being processed can be observed on a video monitor 89.
[0062]
When the laser light source 71 and the homogenizer 72 satisfy the above-mentioned conditional expression (7) or (8), it is possible to prevent the generation of a speckle pattern on the processing substrate and to improve the quality of the formed polycrystalline film.
[0063]
The laser annealing apparatus shown in FIG. 4 can be used not only for polycrystallization of an amorphous semiconductor but also for activation annealing of impurities injected into a semiconductor film.
[0064]
Next, a laser beam homogenizing optical system according to another embodiment will be described with reference to FIGS.
[0065]
FIG. 5A shows a front view of the lens array 21, and FIG. 5B shows a front view of the polarization control element 20. The lens array 21 and the polarization state control element 20 replace the lens array 2 and the polarization state control element 6 shown in FIG.
[0066]
As shown in FIG. 5A, a plurality of convex lenses 21A are arranged in the X-axis direction (column direction) and the Y-axis direction (row direction). The pitch in both the row and column directions is h. A plurality of convex lenses 21A arranged in a matrix divide one laser beam into a plurality of laser beams whose beam cross sections are arranged in a matrix in an XY plane.
[0067]
As shown in FIG. 5B, a unit area corresponding to each of the plurality of lenses 21A of the lens array 21 is defined in the polarization state control element 20. The 波長 wavelength plate is arranged in every other unit area 20A (unit area hatched in FIG. 5B) in the row direction and the column direction. The laser beam passing through the unit area 20A rotates its polarization direction by 90 °. The polarization direction of the laser beam passing through the other unit areas 20B does not change.
[0068]
For this reason, the polarization directions of the laser beams passing through the unit areas adjacent to each other in the row direction and the column direction are orthogonal to each other. Therefore, interference between the two can be prevented, and the occurrence of a speckle pattern can be prevented.
[0069]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
[0070]
【The invention's effect】
As described above, according to the present invention, interference between two laser beams divided from one laser beam can be reduced by changing the polarization state of the beams traveling on mutually adjacent paths. be able to. Thus, it is possible to prevent a speckle pattern from being generated when a plurality of divided laser beams are superimposed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a laser beam homogenizing optical system according to an embodiment of the present invention, and a front view of a polarization control element used therein.
FIG. 2 is a front view showing another configuration example of the polarization control element.
FIG. 3 is a sectional view of a laser beam homogenizing optical system according to another embodiment.
FIG. 4 is a plan view of a laser annealing apparatus using a laser beam homogenizing optical system according to an embodiment.
FIG. 5A is a front view of a lens array, and FIG. 5B is a front view of a polarization control element.
[Explanation of symbols]
1,3 laser beam
2, 21, 45A, 45B, 46A, 46B Lens array
4,49 Condenser lens
5,50 homogenized surface
6, 20, 45C, 46C Polarization state control element
6A 1/2 wave plate
6S slow axis
6F First axis
10A, 10B Polarization direction
38 Quartz window
40 processing chamber
44 stages
60 linear motion mechanism
63, 65 connecting member
64 linear guide mechanism
66 linear motor
67 Bellows
71 Laser Light Source
72 Homogenizer
76 Attenuator
82 transfer chamber
83, 84 Loading / unloading chamber
85, 86, 87 Gate valve
88 CCD camera
89 Video Monitor
91, 92, 93 vacuum pump
94 Transfer robot

Claims (10)

A laser light source for emitting a laser beam,
A laser beam emitted from the laser light source is incident, and the incident laser beam is divided into a plurality of beams in the first direction by a plurality of lenses arranged in a first direction intersecting the traveling direction of the laser beam. A first lens array;
First polarization state control means for changing the polarization state of the laser beam such that the polarization states of the two laser beams passing through the adjacent lenses of the first lens array are different from each other;
A uniformized laser beam irradiation apparatus, comprising: a superimposing optical system for superimposing a plurality of beams split by the first lens array on a surface to be irradiated. The laser beam emitted from the laser light source is linearly polarized,
The said 1st polarization state control means changes the polarization state so that the polarization direction of two laser beams which passed the mutually adjacent lens of the said 1st lens array may mutually be orthogonal. Laser beam irradiation equipment. The first polarization state control means includes a half-wave plate disposed in every other path in a first direction among paths of the plurality of laser beams divided by the first lens array. The apparatus for irradiating a uniformized laser beam according to claim 2. The plurality of lenses forming the first lens array are cylindrical lenses having a columnar surface parallel to a second direction orthogonal to the first direction, and the plurality of lenses of the laser beam incident on the first lens array are 4. The uniform laser beam irradiation apparatus according to claim 3, wherein a polarization direction is inclined by 45 degrees from the second direction, and a slow axis or a fast axis of the half-wave plate is parallel to the second direction. . 5. The method according to claim 1, wherein each of the plurality of lenses constituting the first lens array is a condenser lens, and the first polarization state control unit is disposed behind the first lens array. 6. The uniformized laser beam irradiation device according to any one of the above. The uniformized laser beam irradiation device according to claim 5, wherein the first polarization state control means is disposed at a light condensing position of a light condensing lens constituting the first lens array. Further, a plurality of laser beams split by the first lens array enter, and a plurality of lenses arranged in a second direction orthogonal to the first direction, each of the plurality of incident laser beams, A second lens array for splitting into a plurality of beams in a second direction;
Second polarization state control means for changing the polarization state of the laser beam so that the polarization states of the two laser beams passing through mutually adjacent lenses of the second lens array are different from each other,
The laser beam irradiation apparatus according to claim 1, wherein the superposition optical system superposes a plurality of beams split by the second lens array on a surface to be irradiated. It said laser light source emits a laser beam quality index M ^2,
When the diameter of the laser beam incident on the first lens array is D and the arrangement pitch of the plurality of lenses constituting the first lens array is h, M ² > (0.61πD / (2h)) The uniformized laser beam irradiation device according to any one of claims 1 to 7, which satisfies. A laser light source for emitting a laser beam,
A laser beam emitted from the laser light source is incident, and a plurality of lenses arranged in a matrix along a first surface intersecting the traveling direction of the laser beam causes the incident laser beam to be moved in a row direction and a column direction. A lens array for splitting into multiple beams with respect to
Polarization state control means for changing the polarization state of the laser beam so that the polarization states of the two laser beams passing through the lenses adjacent to each other in the row and column directions are different from each other;
A homogenizing laser beam irradiation apparatus, comprising: a superimposing optical system for superimposing a plurality of beams split by the lens array on a surface to be irradiated. The laser beam emitted from the laser light source is linearly polarized,
The polarization state control means defines a plurality of unit areas arranged in a matrix corresponding to each of the plurality of lenses constituting the lens array, and every other unit area in the row direction and the column direction. The homogenized laser beam irradiation device according to claim 9, wherein a half-wave plate is disposed in the inside.

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