JP2005109359A - Laser device, and manufacturing method of liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the energy density of a region irradiated by continuously oscillating laser beams, by coupling them to each other. <P>SOLUTION: A laser apparatus has a plurality of laser oscillators, a plurality of arranged optical fibers 16, having respectively their incident laser beams emitted from the one or more laser oscillators, wherein a line X obtained by connecting in parallel with each other the respective centers of their light-emitting end surfaces is made nearly straight, a collimator lens 18 for collimating the lights emitted from the plurality of arranged optical fibers 16, a first cylindrical-lens array 24, comprising a plurality of cylindrical lenses which are so arranged in the direction of the line X as to make their respective generatrixes vertical to the line X respectively, and a condenser lens 26 for condensing the lights transmitted by the first cylindrical-lens array 24. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a laser device and a liquid crystal display device.

Conventionally, in the manufacturing process of a liquid crystal display device, after forming an amorphous silicon thin film on a light-transmitting substrate by a low temperature process, this silicon thin film is annealed with a laser to be polycrystallized to obtain semiconductor characteristics. A significant improvement has been made.

In this annealing step, an excimer laser is usually used as the type of laser. However, the excimer laser has a problem that the crystal grains cannot be enlarged due to a pulse wave, and a problem that the running cost is high.

In recent years, a method for polycrystallizing silicon using a continuous wave solid-state laser has been developed in place of the excimer laser having such problems. However, the wavelength of absorption 5 in silicon
The output of laser light of 50 nm or less and continuous oscillation is at most about 10 W.

For this reason, in order to ensure the energy density required for polycrystallization, there is a problem that the irradiation area must be reduced, resulting in a decrease in throughput.
JP 2003-59858 A

In order to solve these problems and increase the laser output, it is conceivable to combine a plurality of laser beams. Conventional laser beam combining methods include a method of combining two laser beams having different deflections using a deflecting element, and a method of combining laser beams having different wavelengths using a mirror having different transmittance depending on the wavelength. . However, in these methods, the number of laser beams that can be coupled is limited.

In addition, there are other coupling methods, but in the case of a coupling method in which the beam size increases as a result of the coupling, it is difficult to ensure the necessary energy density.

In particular, when used in a polycrystallization process of silicon or the like, there is also a demand for making the energy density in the longitudinal direction of the line beam substantially uniform.

Accordingly, the present invention provides a plurality of laser oscillators and a plurality of optical fibers on which laser beams output from at least one of the laser oscillators are respectively incident and lines connecting the centers of the emission end faces are arranged in a substantially straight line. A collimating lens for collimating light emitted from the plurality of optical fibers, a first cylindrical lens array comprising a plurality of cylindrical lenses arranged in the straight line direction so that the straight line and each bus line are perpendicular to each other, A laser apparatus comprising: a condensing lens that condenses light transmitted through the first cylindrical lens array.

A plurality of first laser oscillators each emitting laser light having a wavelength of 550 nm or less; at least one second laser oscillator emitting laser light having a wavelength of 550 nm or more; and at least one first laser. A plurality of optical fibers on which laser beams output from an oscillator and / or laser beams output from the second laser oscillator are respectively incident and lines connecting the centers of the emission end faces are arranged in a straight line; A collimating lens for collimating light emitted from a plurality of optical fibers, a first cylindrical lens array including a plurality of cylindrical lenses arranged in the straight line direction so that the straight line and each bus line are perpendicular to each other; And a condensing lens that condenses the light transmitted through the cylindrical lens array. A laser device.

A liquid crystal display device comprising: a step of forming a semiconductor on a light-transmitting substrate; and a polycrystallization step of irradiating the formed semiconductor with laser light that continuously oscillates to polycrystallize the semiconductor. In the manufacturing method, the polycrystallizing step includes a step of scanning while irradiating the same portion with a laser beam having a wavelength of 550 nm or longer and a laser beam having a wavelength of 550 nm or less. This is a method for manufacturing a liquid crystal display device.

(First embodiment)
According to the laser device of the present invention, it is possible to irradiate high-power laser light. In addition, according to the method for manufacturing a liquid crystal display device according to the present invention, it is possible to improve the manufacturing throughput of the liquid crystal display device.

  Hereinafter, the laser apparatus 10 according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a laser apparatus 10 according to the present invention. FIG. 2 shows the laser device 1.
It is a schematic block diagram of 0 coupling | bond part 12, FIG. 1 (a) is a top view, (b) is a front view.

As shown in FIG. 1A, the laser apparatus 10 includes a total of ten laser oscillators 14. Each laser oscillator 14 emits SHG light (532 nm) of an Nd: YAG laser with continuous oscillation, and each output is about 10 W at maximum. The two laser oscillators 14 form a set and are configured to emit laser beams whose polarizations are different from each other by 90 degrees.

A total of five optical fibers 16 are provided, and the core diameter of each fiber 16 is 100 μm. FIG. 3 is a view showing the emission end face of the optical fiber 16, and as shown in this figure, the center-to-center distance D of each emission end face is 0.5 mm to 1.0 mm. The line X passing through the center is arranged to be a straight line.

The optical coupling unit 12 includes a collimating lens 18, a random phase plate 20,
A second cylindrical lens array 22, a first cylindrical lens array 24, and a condenser lens 26 are arranged.

The collimating lens 18 has an effective focal length of 500 mm and is disposed 500 mm away from the emission end face of the optical fiber 16.

A random phase plate 20 is arranged immediately after the collimating lens 18. FIG. 4 schematically shows the random phase plate 20, and the phase difference of the disc is 0 degree, 90 degrees, 180 degrees, 27
A four-gradation pattern of 0 degree is formed at a 50 μm square pitch. The random phase plate 20 can be rotated at 1000 to 3000 rpm by a rotating means (not shown).

FIG. 5 shows the second cylindrical lens array 22. As shown in this figure, one cylindrical lens has a width of 50 mm, a height of 5 mm, and a thickness of 3 mm. One end surface is a plane, and the other end surface has a curvature of about 50 mm (effective focal length: 100 mm). Convex surface. Ten cylindrical lenses are arranged in the height direction to form a cylindrical lens array 22.

As shown in FIG. 2A, the second cylindrical lens array 22 has a convex surface facing the incident surface of the laser beam, and each generatrix of each cylindrical lens (a straight line forming the vertex of the convex surface of the cylindrical lens) is a light beam. The fiber 16 is disposed so as to face a direction perpendicular to the straight line X connecting the centers of the emission end faces of the fiber 16.

The first cylindrical lens array 24 is also the same optical element as the second cylindrical lens array 22, and the convex surface serves as a laser light emitting surface, and the respective generatrixes of each cylindrical lens face the direction perpendicular to the straight line X. Has been placed. The distance between the first cylindrical lens array 24 and the second cylindrical lens array 22 is 100 mm.

The condensing lenses 26 arranged thereafter have an effective focal length of 100 mm and are processed objects.
It is disposed 100 mm away from W.

  Here, the workpiece W is an amorphous silicon film formed on a translucent substrate.

  Hereinafter, the operation of the laser device 10 having such a configuration will be described.

Each laser oscillator 14 emits laser light having a wavelength of 532 nm. Laser light from the two laser oscillators 14 forming a pair is polarization-coupled. That is, one laser oscillator 14
The laser light output from a passes through the deflector 28, and the laser light output from the other laser oscillator 14 b is totally reflected by the total reflection mirror 30 and then reflected by the deflector 28.

In this way, the two laser beams are polarization-coupled, and the optical fiber 16 is collected by the condenser lens 32.
Is incident on.

  The laser light propagated in each optical fiber 16 is emitted from the emission end face of the optical fiber 16.

The beam divergence angle of the emitted laser light is about 0.05 rad as a half angle. On the other hand, since the distance between the collimating lens 18 and the exit end face is approximately 500 mm, the beam cross-sectional diameter of the collimated laser light is approximately 50 mm (500 mm × tan (0.05 rad) × 2 = 50 m).
m).

Next, the collimated laser light is incident on the random phase plate 20. The random phase plate 20 is rotated at 1000 rpm to 3000 rpm by a rotating means (not shown). For this reason, the coherence of the laser light is reduced by the transmission of the random phase plate 20.

Further, the laser light passes through the first and second cylindrical lens arrays 24 and 22 and the condenser lens 26.

Here, image formation of laser light is divided into a case where it is viewed from a direction perpendicular to the arrangement direction of the optical fibers 16 (FIG. 2A) and a case where it is viewed from a parallel direction (FIG. 2B). explain.

First, as viewed from a direction perpendicular to the arrangement direction of the optical fibers 16, the first and second cylindrical lens arrays 24, 22 have the same shape and are perpendicular to the plane perpendicular to the optical path of the laser. They are arranged almost symmetrically. Therefore, the first cylindrical lens array 24
The laser beam that has passed through is incident on the condenser lens 26 substantially in parallel. The effective focal length of each cylindrical lens of the first cylindrical lens array 24 is 100 mm, and the convex surface of each cylindrical lens of the second cylindrical lens array 22 is located at a position of 100 mm from each cylindrical lens. Accordingly, the convex surfaces of the cylindrical lenses of the second cylindrical lens array 22 are overlapped on the surface of the workpiece W to form an image.

In addition, since the effective focal length of the cylindrical lens of the second cylindrical lens array 22 and the effective focal length of the condenser lens 26 are equal (100 mm), the cylindrical lens of the second cylindrical lens array 22 is equal on the surface of the workpiece W. The image is formed at a magnification, and since the cylindrical lens has a width of 5 mm, the image is formed on the surface of the workpiece W at 5 mm. In addition, since the laser beams transmitted through the respective cylindrical lenses of the first cylindrical lens array 24 overlap, the intensity distribution of the laser beams is equalized.

On the other hand, when viewed from a direction parallel to the arrangement direction of the optical fibers 16 (FIG. 2B), the laser light collimated by the collimator lens 18 is collected on the surface of the workpiece W by the condenser lens 26. As a result, the image of the exit end face of the optical fiber 16 is formed on the surface of the workpiece W. Here, the effective focal length of the collimating lens 18 is 500 mm, the effective focal length of the condenser lens 26 is 100 mm, and the core diameter of the optical fiber 16 is 10 here.
Since it is 0 μm, it is 20 μm (100 μm × 100/500) on the surface of the workpiece W.

As described above, in the laser apparatus 10 according to the first embodiment of the present invention, 20 μm ×
It becomes possible to irradiate the workpiece W with a 5 mm line beam. Here, as described above, the energy intensity of the laser light can be equalized in the arrangement direction of the optical fibers 16. Further, the output of each laser oscillator 14 is 10 W, and a total of 10 laser oscillators 14 are used. Therefore, it is possible to ensure an output of around 100 W while continuous oscillation. Furthermore, it becomes possible to reduce the problem of speckle and interference caused by superimposing laser beams by inserting the random phase plate 20.

Note that by increasing the number of oscillators 14 and the number of optical fibers 16, the output can be increased without substantially changing the irradiation region.

That is, the number of laser oscillators 14 and the number of optical fibers 16 can be variously changed according to the output to be obtained.

In addition, it is not always necessary to couple the light beams by the deflector 28 so that the light beams 16 enter the optical fiber 16, and one optical fiber 16 may include one laser oscillator 14. Further, a configuration may be adopted in which laser light is incident on each optical fiber 16 by wavelength coupling instead of polarization coupling.

Further, the number of cylindrical lenses included in each cylindrical lens array is not limited to ten. However, as the number increases, the energy intensity can be equalized.

Further, the random phase plate 20 may not be used as necessary. Random phase plate 2
The insertion position of 0 may be before the laser beams are superimposed, for example, between the first cylindrical lens array 24 and the second cylindrical lens array 22, or between the first cylindrical lens array 24 and the condenser lens 26. The structure inserted between may be sufficient.

Further, the second cylindrical lens array 22 may not be used. Even in this case, since the laser light transmitted through each cylindrical lens of the first cylindrical lens array 24 is superimposed by the condenser lens 26, it is possible to equalize the laser light and increase the irradiation area. Because. However, the efficiency may be reduced as compared with the case where the second cylindrical lens array 22 is provided.

Further, the effective focal length of the cylindrical lens of the first cylindrical lens array 24 (
100 mm) and the effective focal length (100 mm) of the condenser lens 26 do not necessarily match. In this case, the beam width on the surface of the workpiece W changes. For example, the focal length of the cylindrical lens of the first cylindrical lens array 24 is set as the condensing lens 26.
When the distance between the first cylindrical lens array 24 and the second cylindrical lens array 22 is made closer to the focal distance, the beam width can be increased.

If a cylindrical lens array having different cylindrical lens widths is used, the beam width can be changed.

In addition, the direction of each convex surface of the first cylindrical lens array and the second cylindrical lens array may be arbitrary, as long as it faces either the incident side or the emission side.

Further, the curvature of the convex surface of the second cylindrical lens array does not necessarily match the curvature of the convex surface of the first cylindrical lens array.

Also, it is not limited to YAG laser SHG light, but YAG laser THG light, Nd: YVO ₄
SHG light, THG light, or Ar + (argon ion laser) may be used.

The application of the laser device 10 can be widely used in general processing, and can be preferably used particularly when the energy density is high and equalization is required.

  In addition, the present invention can be variously modified.

(Second Embodiment)
The second embodiment relates to an invention in which the beam width is changed by appropriately adjusting the distance between the first cylindrical lens array 24 and the second cylindrical lens array 22.

That is, the beam width at the imaging position can be changed by moving the second cylindrical lens array 22 in the optical axis direction with a drive table (not shown). Since other configurations are the same as those in the first embodiment, description thereof will be omitted.

6A shows the case where the distance between the two is equal to the effective focal length of the cylindrical lens of the first cylindrical lens array 24, and FIG.
(C) is a case where the second cylindrical lens array 22 is brought closer than the case (a). For simplicity, only one cylindrical lens is illustrated.

Case (a) is the case of the first embodiment. In this case, the width of the cylindrical lens (
5 mm) is imaged at the same magnification.

In the case of (b), at a point 100 mm from the first cylindrical lens array 24,
The beam width when viewed from the direction perpendicular to the arrangement direction of the fibers 16 is 4 mm. Therefore, even if an image is formed, the beam width when viewed from this direction is 4 mm. For this reason, the irradiation area of the beam is 4 mm × 20 μm.

In the case of (c), at a point 100 mm from the first cylindrical lens array 24,
The beam width when viewed from the direction perpendicular to the arrangement direction of the fibers 16 is equivalent to 6 mm. Therefore, even if an image is formed, the beam width when viewed from this direction is 6 mm. For this reason,
The irradiation area of the beam is 6 mm × 20 μm.

Thus, the first cylindrical lens array 24 and the second cylindrical lens array 2
It is possible to change the beam width by arranging a distance adjusting means for adjusting the distance between the two and appropriately adjusting the distance between the two.

More specifically, in the case of a configuration in which the distance between the first cylindrical lens array 24 and the second cylindrical lens array 22 is shorter than the effective focal length of the cylindrical lens of the first cylindrical lens array 24, the beam width is increased. In the case where the distance between the first cylindrical lens array 24 and the second cylindrical lens array 22 is longer than the effective focal length of the cylindrical lens of the first cylindrical lens array 24, the beam width can be shortened. It becomes.

Other modifications can be applied in the same manner as described in the description of the first embodiment.

(Third embodiment)
The third embodiment relates to a method of manufacturing a liquid crystal display device, and in particular, a laser animation.
It has a feature in the polycrystallization process by the use of copper.

The configuration of the laser device 10 used in this polycrystallization process is different from that of the first embodiment in that two of the ten laser oscillators 14 are continuously oscillated and the output is 50 W each (not shown). It is a point to change. Therefore, one of the five optical fibers 16
YAG laser light (1064 nm) propagates through the book.

  Other configurations are the same as those in the first embodiment.

Using such a laser device 10, an amorphous silicon film formed on a translucent substrate G
Irradiate laser light to Si. FIG. 7 schematically shows a state when laser light is irradiated, and FIG. 8 is a graph schematically showing the absorption rate of silicon for each wavelength when solid and when liquid. is there.

As shown in FIG. 8, the absorption rate of silicon is low when the wavelength is 550 nm or more in the case of solid, and the absorption rate is solid even when the wavelength is 550 nm or more when silicon is liquid. Not as bad as the case.

Therefore, as shown in FIG. 7A, in the case of a solid, 532 nm SHG light is absorbed, but 1064 nm YAG laser light has low absorption.

However, once a part of the silicon film Si becomes liquid, the laser light of 1064 nm is absorbed, and the melting of the surrounding silicon film Si in the surrounding solid phase is promoted by heat conduction from this part. In this state, the substrate G is moved in the direction perpendicular to the longitudinal direction of the line beam and the laser beam is scanned, so that suitable polycrystallization can be achieved.

As described above, continuous oscillation laser is obtained by irradiating silicon with a combination of laser light of 550 nm or less, which has a high absorptance with respect to silicon, and laser light of 550 nm or more capable of high output to perform polycrystallization. It is possible to promote suitable polycrystallization even with light. Therefore, it is possible to improve the throughput as compared with the conventional continuous oscillation type polycrystallization, which leads to an improvement in the throughput of the liquid crystal display device.

Note that annealing may be performed using the laser device 10 shown in the first or second embodiment. Even in this case, the output can be increased as compared with the conventional continuous oscillation type, and as a result, it contributes to the improvement of the throughput. Even in this embodiment, various modifications can be made as in the case of the other embodiments.

1 is a schematic configuration diagram of a laser apparatus 10 according to a first embodiment of the present invention. 1 is a schematic configuration diagram of a coupling unit 12 of a laser device 10 according to a first embodiment of the present invention. FIG. 3 is a schematic diagram of an emission end face of the optical fiber 16 in the first embodiment of the present invention. 1 is a schematic diagram of a random phase plate 20 according to a first embodiment of the present invention. FIG. 3 is a schematic configuration diagram of a second cylindrical lens array 22 according to the first embodiment of the present invention. Explanatory drawing of the relationship between the distance of the 1st cylindrical lens array 24 and the 2nd cylindrical lens array 22, and a line beam width concerning the 2nd Embodiment of this invention. FIG. 9 is a schematic diagram showing a state in which a line beam is irradiated to an amorphous silicon film Si formed on a light-transmitting substrate G according to the third embodiment of the present invention. The graph which shows the relationship between the absorption factor of a silicon | silicone, and a wavelength.

Explanation of symbols

10 laser device, 14 laser oscillator, 16 optical fiber, 20 random phase plate,
22 2nd cylindrical lens array, 24 1st cylindrical lens array.

Claims (9)

A plurality of laser oscillators;
A plurality of optical fibers on which laser beams output from at least one of the laser oscillators are respectively incident, and lines connecting the centers of the emission end faces are arranged in a substantially straight line;
A collimating lens for collimating light emitted from the plurality of optical fibers;
A first cylindrical lens array comprising a plurality of cylindrical lenses arranged in the straight line direction so that the straight line and each bus line are perpendicular to each other;
A laser apparatus comprising: a condensing lens that condenses light transmitted through the first cylindrical lens array. Between the first cylindrical lens array and the collimating lens, the straight lines and the generatrixes are arranged in the straight line direction so as to be perpendicular to each other, and the same number of the plurality of cylindrical lenses included in the first cylindrical lens array are provided. The laser apparatus according to claim 1, further comprising a second cylindrical lens array made of cylindrical lenses. In the first cylindrical lens array, the convex curved surface of each of the cylindrical lenses is disposed so as to face the emission surface of the laser light,
In the second cylindrical lens array, the convex curved surface of each cylindrical lens is arranged facing the incident surface of the laser beam, and
3. The laser apparatus according to claim 2, wherein a distance between the first cylindrical lens array and the second cylindrical lens array is an effective focal length of each cylindrical lens of the first cylindrical lens array. Between the collimating lens and the second cylindrical lens array, between the first cylindrical lens array and the second cylindrical lens, or between the first cylindrical lens array and the condenser lens. The laser device according to claim 2, further comprising a random phase plate disposed between the laser devices. The laser apparatus according to claim 1, wherein the laser light having a different wavelength is propagated for each optical fiber. Two laser oscillators are provided corresponding to each of the optical fibers, and the laser beams emitted from the two optical units are combined by a deflecting element and incident on the optical fiber. The laser device according to claim 1. A plurality of first laser oscillators each emitting laser light having a wavelength of 550 nm or less;
At least one second laser oscillator that emits laser light having a wavelength of 550 nm or more;
Laser light output from at least one of the first laser oscillators and / or laser light output from the second laser oscillator are respectively incident, and lines connecting the centers of the emission end faces are arranged in a straight line. A plurality of optical fibers,
A collimating lens for collimating light emitted from the plurality of optical fibers;
A first cylindrical lens array comprising a plurality of cylindrical lenses arranged in the straight line direction so that the straight line and each bus line are perpendicular to each other;
A laser apparatus comprising: a condensing lens that condenses light transmitted through the first cylindrical lens array. Forming a semiconductor film on a light-transmitting substrate;
In a manufacturing method of a liquid crystal display device comprising a polycrystallization step of polycrystallizing the semiconductor by irradiating the formed semiconductor with laser light that continuously oscillates,
In the polycrystallization step, a laser beam having a wavelength of 550 nm or longer and a wavelength of 550 nm are continuously oscillated.
A method for manufacturing a liquid crystal display device, comprising: a step of scanning while irradiating the same portion with a laser beam that continuously oscillates at a wavelength of nm or less. Forming a semiconductor film on a light-transmitting substrate;
In a manufacturing method of a liquid crystal display device comprising a polycrystallization step of polycrystallizing the semiconductor by irradiating the formed semiconductor with laser light that continuously oscillates,
8. A method of manufacturing a liquid crystal display device according to claim 1, wherein the laser beam irradiation in the polycrystallization step uses the laser device according to any one of claims 1 to 7.

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