JP2001023919A - Precisely variable rectangular double beam optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To project efficiently a processing beam on a work, even when combining with each other a plurality of laser light sources, by joining spatially to each other a pair of projective beams to synthesize them, by dividing once the synthesized synthetic beam into a plurality of divided beams, and further, by superimposing on each other the divided synthetic beams to project them on the work. SOLUTION: A projective optical system 40 projects on a work W with a predetermined illuminance a synthetic beam CL synthesized by a synthetic optical system 30. The synthetic optical system 30 joins spatially to each other a pair of laser beams LB1, LB2 emitted from both laser light sources 21, 22 to form the synthetic beam CL, and it comprises a pair of knife-edge mirrors 31, 32 provided in parallel with each other. A homogenizer 41 of the projective optical system 40 divides once into a plurality of divided beams the synthetic beam CL outputted from the synthetic optical system 30, and makes rectangular the sections of the divided beams to superimpose the divided beams on each other and project them uniformly on a predetermined surface. A lens optical system 42 of the projective optical system 40 forms into the beam of a predetermined shape the uniform beam outputted from the homogenizer 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam forming apparatus for causing irradiation light to enter a target surface in a desired beam shape, and a laser processing apparatus using the same.
In particular, it is suitable for application to an annealing device, a surface modification device, and the like.

[0002]

2. Description of the Related Art For example, a laser annealing apparatus for polycrystallizing an amorphous Si film includes an optical system called a homogenizer as a beam shaping apparatus for irradiating annealing light onto a substrate on which an amorphous Si film is formed. In particular, when the laser annealing apparatus is of a scan type that irradiates a linear laser beam on the substrate in a short-axis direction by one-axis scan, a linear beam homogenizer that forms a linear beam from a rectangular beam is used.

[0003]

However, in the laser annealing apparatus as described above, since a single light source is used, processing light depending on the characteristics of the laser light source has to be irradiated. Here, in order to set the characteristics of the processing light in various ways, it is conceivable to combine a plurality of laser light sources.

For example, when combining a pair of laser light sources to obtain a combined light, it is conceivable to superpose two beams from the pair of light sources using a polarizing beam splitter before making the combined light enter the homogenizer. In such a configuration, for example, considering that the p-polarized light component of the first beam from one light source passes through the combining surface of the polarizing beam splitter and enters the homogenizer, the second light beam from the other light source is considered. Of these, the s-polarized light component is reflected by this combining unit and enters the homogenizer. That is, the s-polarized light component of the first beam and the p-polarized light component of the second beam do not enter the homogenizer, and these polarized components are not used and are lost.

Accordingly, the present invention provides a beam forming apparatus capable of efficiently irradiating processing light even when a plurality of laser light sources are combined and enabling high-precision processing, and a laser processing apparatus using the same. It is intended to provide a device.

[0006]

In order to solve the above-mentioned problems, a beam forming apparatus according to the present invention comprises: a combining optical system for spatially joining a pair of irradiation lights from a pair of different light sources; A homogenizer that splits the combined light combined by the optical system into a plurality and irradiates the combined combined light in a superimposed manner so that the pair of irradiation lights are incident on a predetermined surface as uniform beams of substantially the same size. It has a lens optical system.

In this device, since the combining optical system spatially joins and combines a pair of irradiation lights from a pair of different light sources, it is possible to combine the pair of irradiation lights with a minimum loss. After the synthesis, a uniform beam can be formed on a predetermined surface for each of the pair of irradiation lights by the homogenizer and the lens optical system.

In a preferred aspect of the apparatus, the combining optical system causes the first beam, which is one of the pair of irradiation lights, to enter a central pupil region including an optical axis of the homogenizer, and A second beam, which is the other of the irradiation light,
The light is split into two and made incident on a pair of outer pupil regions provided at both ends of the central pupil region of the homogenizer.

In this case, the combining optical system causes the first beam to enter the central pupil region of the homogenizer, and divides the second beam into two beams to enter the pair of outer pupil regions of the homogenizer. Light from both light sources can be supplied symmetrically to the optical axis of the homogenizer, and the symmetry of a beam image formed on a predetermined surface can be increased.

In a preferred aspect of the apparatus, the combining optical system includes two slit-type mirrors arranged at a predetermined interval, and the first beam passes between the two slit-type mirrors. While passing, the second beam is individually reflected by the two slit-type mirrors and divided, and passes through both ends of the first beam.

In this case, the structure of the combining optical system is simplified, and the joining of a pair of irradiation lights from a pair of different light sources becomes smooth.

In a preferred aspect of the above apparatus, before the pair of irradiation lights enter the combining optical system, at least one of the pair of irradiation lights is a beam to be incident on the combining optical system. The image forming apparatus further includes adjusting means for adjusting a size or an image forming position by the homogenizer.

In this case, even if the pair of irradiation light beams from the pair of light sources have different beam sizes and divergence angles, they can be incident on the combining optical system with the same geometric optical characteristics. Can be complemented more easily.

In a preferred aspect of the above-mentioned apparatus, before the combining optical system, the second light incident on the combining optical system is provided.
An afocal optical system that matches a beam size of the beam with a beam size of the first beam incident on the combining optical system.

In this case, even if a pair of irradiation lights from both light sources have different beam sizes, they can be incident on the combining optical system with the same beam size.

In a preferred aspect of the above-mentioned apparatus, the first light incident on the combining optical system is provided before the combining optical system.
The apparatus further includes an adjustment optical system for finely adjusting an image forming position of the beam by the homogenizer.

In this case, even if the characteristics of the pair of irradiation lights from both light sources are different, it is possible to adjust the subtle mismatch between the irradiation of the pair of irradiation lights by matching the imaging positions of the homogenizer. it can.

Further, the laser processing apparatus according to the present invention includes a beam forming apparatus for irradiating a pair of irradiation lights from a pair of different light sources as uniform beams of substantially the same size, and a stage for mounting a work.

In this apparatus, since the beam forming apparatus irradiates a pair of irradiation lights from a pair of different light sources as uniform beams of substantially the same size, the characteristics of the processing light can be set in various ways, and There is little loss on generation.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment FIG. 1 is a view for explaining the structure of a laser annealing apparatus which is a laser processing apparatus incorporating a beam forming apparatus according to a first embodiment of the present invention. This laser annealing apparatus mounts a work W which is a glass plate having a semiconductor thin film of amorphous Si or the like formed on the surface thereof and can move three-dimensionally smoothly.
0, a pair of laser light sources 21 and 22 for generating a pair of laser beams LB1 and LB2 having different characteristics, and a combining optical system 3 for combining these laser beams LB1 and LB2.
0 and an irradiation optical system 40 that causes the combined light CL combined by the combining optical system 30 to enter the work W with a predetermined illuminance.
And the stage 10 on which the work W is placed,
A stage driving device 60 for appropriately moving a required amount of the laser annealing device, and a main control device 100 for integrally controlling the operation of each part of the entire laser annealing apparatus are provided.

Each of the pair of laser light sources 21 and 22 is an excimer laser or another pulse light source for heating a semiconductor thin film on the work W, and has a pair of lasers having different characteristics such as emission time, peak intensity, and wavelength. Beam L
B1 and LB2 are individually generated.

The combining optical system 30 includes both laser light sources 21 and 2
The pair of laser beams LB1 and LB2 from the two are spatially spliced together to form a combined light CL, and includes a pair of knife edge mirrors 31 and 32 arranged in parallel. A divergence optical system 71 and a telescope optical system 72 are provided between the combining optical system 30 and the two laser light sources 21 and 22 as adjustment devices. The divergence optical system 71 has a role as an adjustment optical system that finely adjusts an image forming position (beam forming position) in the optical axis direction of the first beam LB1 from the laser light source 21 by the homogenizer 41 provided in the irradiation optical system 40. . The telescope optical system 72 serves as an afocal optical system that adjusts the beam size of the second beam LB2 from the laser light source 22 to match the beam size of the first beam LB1 incident on the combining optical system 30. Have.

FIG. 2 is a diagram for explaining the combined light CL formed by the combining optical system 30. The synthetic optical system 30
The first beam LB1 from the laser light source 21 is applied to the central pupil area CA including the optical axis OA of the entrance pupil P of the irradiation optical system 40.
Incident on Further, the combining optical system 30 includes the laser light source 2
The second beam LB2 from No. 2 is split into two beams, and is incident on a pair of outer pupil regions SA1 and SA2 provided at both ends of the central pupil region CA in the entrance pupil P of the irradiation optical system 40, respectively.

Returning to FIG. 1, the irradiation optical system 40 once divides the combined light CL from the combining optical system 30 into a plurality of beams, and converts these divided beams into rectangular beams to be superimposed on a predetermined surface and uniformly. The apparatus includes a homogenizer 41 for incidence, and a lens optical system 42 for shaping uniform light from the homogenizer 41 into a predetermined shape.

Returning to FIG. 1, the stage driving device 60
The stage 10 is driven to perform alignment for positioning a predetermined region on the work W with respect to the irradiation optical system 40.
Further, when the laser annealing is completed in a predetermined region on the work W, the stage driving device 60 performs alignment for step-moving the work W to a region adjacent to the above described predetermined region. The driving amount of the stage 10 by the stage driving device 60 is constantly monitored by the position detecting device 80.

The operation of the apparatus shown in FIG. 1 will be described below. First, the work W is transported and placed on the stage 10 of the laser annealing apparatus. Next, the work W on the stage 10 is aligned with the irradiation optical system 40. Next, the combined light CL obtained from the pair of laser light sources 21 and 22 is incident on a predetermined area on the work W. On the work W,
A thin film of an amorphous semiconductor such as amorphous Si is formed, and a predetermined region of the semiconductor is annealed and recrystallized by irradiation, so that a semiconductor thin film having excellent electric characteristics can be provided. Laser annealing as described above is performed for the work W
Is repeated in a plurality of predetermined regions provided in the workpiece W, and the semiconductor thin film is annealed in a plurality of predetermined regions provided in the work W.

At this time, in the above apparatus, the combining optical system 30 spatially joins the pair of laser beams LB1 and LB2 from the pair of laser light sources 21 and 22 to form the combined light CL. LB1 and LB2 can be combined while minimizing loss. After the combination, the homogenizer 41 can form a uniform rectangular beam for each of the pair of laser beams LB1 and LB2 on a predetermined surface. Further, a beam AB incident on the workpiece W
Is an efficient synthesis of the laser beams LB1 and LB2, and enables various laser annealing.

FIG. 3 is a view for explaining the structure of the synthetic optical system 30 and its surroundings. As described above, the combining optical system 30 includes a pair of knife edge mirrors 31 and 32, and applies the first beam LB1 to the pair of knife edges 31a and 31a.
The second beam LB2 is split between a pair of knife edges 31a and 32a while passing between the two beams. The divergence optical system 71 that finely adjusts the image forming position of the first beam LB1 by the homogenizer 41 includes the convex lens 7
It is an afocal system combining the lens 1a and the concave lens 71b. The beam size of the second beam LB2 is set to the first
The telescope optical system 72 for matching the beam size of the beam LB1 is also an afocal system combining a concave lens 72a and a convex lens 72b. A turn mirror 33 is provided between the telescope optical system 72 and the combining optical system 30 to guide the second beam LB2. on the other hand,
The homogenizer 41 on which the combined light CL obtained by combining the two laser beams LB1 and LB2 is incident includes first to fourth cylindrical lens arrays CA1 to CA4 and a condenser lens 41a of a convex lens. Here, the first and third cylindrical lens arrays CA1 and CA3 have a curvature in a cross section parallel to the plane of the paper, and the second and fourth cylindrical lens arrays CA2 and CA4 have a cross section perpendicular to the plane and including the optical axis. Has curvature.

The outline of the operation will be described below. First
The beam LB1 passes between the knife edges 31a and 32a, that is, passes through the central pupil region including the optical axis OA of the homogenizer 41, and the second beam LB2 passes through the knife edge mirror 31,
The first beam LB1 is split into two beams, and passes through both ends of the first beam LB1, that is, a pair of outer pupil regions of the homogenizer 41, and enters the homogenizer 41, respectively. The homogenizer 41 has an entrance pupil size corresponding to two beams so that the combined light CL can be incident thereon.
A lens system such as a is aberration-corrected in accordance with its entrance pupil.

The synthetic light CL incident on the homogenizer 41
Are the first to fourth cylindrical lens arrays CA1 to CA
With A4, a secondary light source divided into the number of segments constituting the cylindrical lens is formed. Divided 2
The light beam from the next light source enters the condenser lens 41a and is superimposed on the irradiated surface IS arranged at the back focus position of the condenser lens 41a to form a uniform rectangular beam.

Here, the divergence optical system 71 and the telescope optical system 72 focus on a rectangular beam formed by the homogenizer 41 due to the beam characteristics of the first beam LB1 and the second beam LB2 and their differences. This prevents differences in beam size, beam size, and uniformity.

The former divergence optical system 71 adjusts the best focus position and beam size of the homogenizer 41 by slightly changing the NA of the first beam LB1 incident on the homogenizer 41. The latter telescope optical system 72 outputs the first beam L incident on the homogenizer 41.
The beam size of the second beam LB2 matches the beam size of B1. As a result, both laser beams LB1, LB2
Can be obtained with the same number of divisions by the cylindrical lens arrays CA1 to CA4.

The details of the operation will be described below. First
The beam LB1 is incident on a divergence optical system 71 for the first beam via a beam delivery (turn mirror or the like) not shown. This divergence optical system 71
Is an almost equal magnification afocal system, and has two lenses 7
By changing the distance between the lenses 1a and 71b, the first beam L emitted from the divergence optical system 71 is changed.
The NA of the first beam LB1 can be slightly changed without substantially changing the beam size of B1. In a specific example, the variable adjustment range of the emission NA (divergence angle of the first beam LB1) by the divergence optical system 71 is set to about several mrad. The two lenses 71
Since a and 71b are a two-unit system having convex and concave portions and each of which has a small power, even if the distance between both lenses 71a and 71b is changed, almost no change in aberration occurs.

The first beam LB1 emitted from the divergence optical system 71 is applied to two knife edge mirrors 31, 3
2, that is, only passes through the optical axis center side of the homogenizer 41. The first beam LB1 that has passed between the knife edge mirrors 31 and 32 then enters the central portion (the cylindrical lens assigned to the first beam LB1) of the cylindrical lens array CA1 of the homogenizer 41, and the number of cylindrical lenses (FIG. 3) Are divided into six). The split beams are superimposed by the condenser lens 41a to form a uniform beam on the irradiation surface IS.

On the other hand, the second beam LB2 is incident on the telescope optical system 72 for the second beam via a beam delivery (not shown). The second beam LB2 that has entered the telescope optical system 72 is enlarged or reduced by the present optical system to have the same beam size as the first beam LB1, and exits therefrom toward the combining optical system 30. In the combining optical system 30, the second beam LB2 is split into two beam portions LB2a and LB2b by the knife edge mirrors 31 and 32, and passes through both ends of the first beam LB1 toward the homogenizer 41. Both beam parts LB2a, LB
2b is incident outside the optical axis center of the homogenizer 41, that is, both ends of the cylindrical lens array CA1 of the homogenizer 41 (the cylindrical lenses assigned to the second beam LB2), and the number of cylindrical lenses (upper and lower three in FIG. 3). (Total of 6 lines each). The split beams are superimposed by the condenser lens 41a to form a uniform beam on the irradiation surface IS.

In the above description, both the first beam LB1 and the second beam LB2 are described as "forming a uniform beam on the irradiated surface IS". However, the best focus position of both is mainly the beam emitted from the light source. May differ due to differences in characteristics such as the spread angle of the When the best focus is different, the beam size is often different. Therefore, it is necessary to compensate for the difference between the characteristics of the first beam LB1 and the second beam LB2. For this reason, the best focus position of the second beam LB2 is set as a true irradiation surface IS (reference surface), and the best focus position of the first beam LB1 is made to coincide with this reference surface. Specifically, the divergence optical system 71 changes the output NA of the first beam LB1, that is, the incident NA as viewed from the homogenizer 41. When the incident NA viewed from the homogenizer 41 is changed, the best focus position after passing through the homogenizer 41 changes accordingly. As a result, the best focus position of the first beam LB1 is finely adjusted,
It can be matched to that of the beam LB2. In addition,
The correspondence between the output NA and the shift of the best focus position differs depending on the lens configuration of the homogenizer 41, and thus detailed description of such adjustment will be omitted.

[Second Embodiment] Hereinafter, a beam forming apparatus according to a second embodiment will be described. The device of the second embodiment is a modification of the device of the first embodiment,
The same portions are denoted by the same reference numerals, and redundant description will be omitted.
The beam forming apparatus according to the second embodiment is incorporated in a laser processing apparatus similar to that shown in FIG. FIG. 4 is a diagram illustrating a main part of the beam forming apparatus according to the second embodiment. This beam forming apparatus corresponds to FIG. 3 of the first embodiment, but has a configuration excluding a divergence optical system 71 arranged in the optical path of the first beam LB1 in FIG.

In this case, the second beam L incident on the homogenizer 41 is changed by changing the distance between the pair of lenses 72 a and 72 b constituting the telescope optical system 72.
The NA of B2 can be changed slightly. In this embodiment, the telescope optical system 72 also performs the role of the divergence optical system 71 for the first beam in FIG. 3, that is, adjusts the focus positions of the first beam LB1 and the second beam LB2.

[Third Embodiment] Hereinafter, a beam forming apparatus according to a third embodiment will be described. The device of the third embodiment is a modification of the device of the first embodiment.
Note that the beam forming apparatus according to the third embodiment is incorporated in a laser processing apparatus similar to that shown in FIG. FIG. 5 is a diagram illustrating a main part of the beam forming apparatus according to the third embodiment. This beam forming apparatus corresponds to FIG. 3 of the first embodiment, but has a configuration excluding the telescope optical system 72 arranged in the second beam LB2 in FIG.

Two laser beams LB1, LB2 to be used
When the beam sizes are almost the same, a telescope optical system 7 as shown in FIG.
There is no need to dispose 2. Also, in an application where the two laser beams LB1 and LB2 used may have different beam sizes, the telescope optical system 72 as shown in FIG. 3 is not required.

[Fourth Embodiment] Hereinafter, a beam forming apparatus according to a fourth embodiment will be described. The device of the fourth embodiment is a modification of the device of the first embodiment.
FIG. 6 is a diagram illustrating a main part of the beam forming apparatus according to the fourth embodiment. In this beam forming apparatus, the split optical system 13
As 0, a knife edge prism 135 is used instead of a pair of knife edge mirrors. If symmetry or the like is not a problem with respect to the uniformity of the beam after passing through the homogenizer 41, the knife edge prism 135 as in this embodiment is used.
Using the knife edge portion 135a of the
The first beam LB1 is incident on the upper side from the first optical axis OA,
The second beam LB is provided below the optical axis OA of the homogenizer 41.
2 is incident. That is, both laser beams LB1, LB2
Can be simply arranged side by side.
It is to be noted that beam delivery for causing the first beam LB1 and the second beam LB2 to enter the knife edge prism 135 from opposite directions is not shown.

[Fifth Embodiment] Hereinafter, a beam forming apparatus according to a fifth embodiment will be described. The device of the fifth embodiment is a modification of the device of the first embodiment.
FIG. 7 is a diagram illustrating a main part of a beam forming apparatus according to a fifth embodiment. In this beam forming apparatus, the split optical system 23
As 0, the knife edge mirrors 131 and 132 have the knife edge portions 131a and 132a which are opposed to each other.

As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments. In the above embodiment, the divergence optical system 71 and the telescope optical system 72 have been described as spherical systems. However, a cylindrical lens system acting on one of the cross sections orthogonal to the X axis or the Y axis may be used. In the case of using a cylindrical lens system, focus adjustment is performed on a more important cross section while focusing on that cross section. In the case of a normal excimer laser, beam characteristics such as a divergence angle are different between an electrode direction and a direction perpendicular thereto, and a cylindrical system is often arranged by focusing on one cross section.
Further, in order to individually match the best focus of both sections, a divergence optical system or a telescope optical system constituted by a cylindrical lens system may be individually arranged for each orthogonal section.

The irradiation optical system 40 of the above embodiment is
Although the mask 42 is illuminated by the homogenizer 41 and the image of the mask 42 is irradiated on the projection lens 43, the work W can be directly arranged on the irradiation surface IS of the homogenizer 41.

[0046]

As is apparent from the above description, according to the beam forming apparatus of the present invention, the combining optical system spatially joins a pair of irradiation lights from a pair of different light sources and combines them. Can be combined while minimizing the loss, and after the combination, a uniform beam can be formed on the predetermined surface for each of the pair of irradiation lights by the homogenizer.

According to the laser processing apparatus of the present invention,
Since the beam forming device irradiates a pair of irradiation lights from a pair of different light sources as uniform beams of substantially the same size, the characteristics of the processing light can be set in various ways, and a loss in generating the processing light is small.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a structure of a laser annealing apparatus incorporating a beam forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating combined light formed by the combining optical system of FIG. 1;

FIG. 3 is a diagram illustrating a detailed structure of a synthetic optical system 30 and its periphery.

FIG. 4 is a diagram illustrating a main part of a beam forming apparatus according to a second embodiment.

FIG. 5 is a diagram illustrating a main part of a beam forming apparatus according to a third embodiment.

FIG. 6 is a diagram illustrating a main part of a beam forming apparatus according to a fourth embodiment.

FIG. 7 is a diagram illustrating a main part of a beam forming apparatus according to a fifth embodiment.

[Explanation of symbols]

 Reference Signs List 10 stage 21, 22 laser light source 30 synthetic optical system 31, 32 knife edge mirror 40 irradiation optical system 41 homogenizer 42 lens optical system 60 stage driving device 71 divergence optical system 71a, 71b lens 72 telescope optical system 72a, 72b lens 80 position Detecting device 100 Main controller AB Linear beam CL Synthetic light LB1 First beam LB2 Second beam W Work

Claims (6)

[Claims] 1. A combining optical system for spatially splicing and combining a pair of irradiation lights from a pair of different light sources, and a combined light divided by the combining optical system and divided by the combining optical system. And a homogenizer that irradiates the pair of irradiation lights as uniform beams of substantially the same size on predetermined surfaces. 2. The combining optical system according to claim 1, wherein the first beam, which is one of the pair of irradiation lights, is incident on a central pupil region including an optical axis of the homogenizer, and a first beam, which is the other of the pair of irradiation lights, 2. The beam forming apparatus according to claim 1, wherein the two beams are split into two beams and are incident on a pair of outer pupil regions provided at both ends of the central pupil region of the homogenizer. 3. The combining optical system includes two slit-type mirrors arranged at a predetermined interval. The first beam passes between the two slit-type mirrors and the second slit-type mirror. 3. The beam forming apparatus according to claim 2, wherein the beams are individually reflected and split by the two slit mirrors, and pass through both ends of the first beam. 4. A beam size to be incident on the combining optical system or an image formed by the homogenizer with respect to at least one of the pair of irradiation lights before the pair of irradiation lights enters the combining optical system. The beam forming apparatus according to claim 1, further comprising an adjusting unit that adjusts a position. 5. An afocal optical system for matching the beam size of the second beam incident on the combining optical system with the beam size of the first beam incident on the combining optical system before the combining optical system. The beam forming apparatus according to claim 2, further comprising: 6. The optical system according to claim 3, further comprising an adjusting optical system for finely adjusting an image forming position of the first beam incident on the synthesizing optical system by the homogenizer before the synthesizing optical system. Beam forming equipment.