JPH09295175A - Laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machine which can avoid machining irregularity or degradation of energy efficiency due to change in the optical axis or the divergent angle of a laser beam and which always enables a superior machining quality, by merely making a simple adjustment. SOLUTION: An optical system consists of a beam expander 25 for variably adjusting the diameter of a laser beam, cylindrical lens groups 27, 28 for variably adjusting the aspect ratio of the shape of the laser beam emitted from the beam expander 25, and a prism provided with a retracting surface of a gable roof shape with edges orthogonally crossed with each other on the incident and the outgoing light sides. In addition, the machine is so structured that it is provided with a homogenizer lens 29 that uniformizes energy density distribution around the optical axis of the laser beam emitted from the cylindrical lens group 27, 28, and that the laser beam emitted from this homogenizer lens 29 is guided to the through hole 37a of an aperture 37 to form a beam shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine suitable for use in thin film precision processing such as trimming of color filters for liquid crystal display devices.

[0002]

2. Description of the Related Art Recently, a technique for performing precision thin film processing by a YAG laser processing machine has been established, and for example, trimming processing of a color filter required when manufacturing a liquid crystal display device is shortened by using such a laser processing machine. It can be done accurately in time.

This type of laser processing machine usually has a processing machine main body for guiding a laser beam (YAG laser) supplied from a laser oscillator along a predetermined optical path by an optical system to irradiate the work, and a mounted processing machine. It is roughly configured by an XY table capable of transferring a workpiece in two directions orthogonal to each other by a linear motor or the like, and a base plate (surface plate) on which the processing machine main body and the XY table are mounted. In addition to various lens groups, the optical system of the main body of the processing machine is provided with an aperture that has a predetermined shape through which the laser beam passes and that functions as a beam shaping member. The formed laser beam is shaped into a beam by passing through the aperture, so that the laser beam having a predetermined beam shape is spotted toward the workpiece from the objective lens disposed at the tip of the optical path. It is designed to be illuminated.

By the way, the energy density distribution around the optical axis of the laser beam supplied from the laser oscillator is generally expressed as a Gaussian distribution curve, and the energy density of the central portion is the highest, and the energy density becomes an exponential function as the distance from the central portion increases. Is gradually decreasing. Therefore, when such a laser beam is guided to the aperture of the aperture, even if the optical axis is slightly deviated from the center of the aperture, the low energy region of the laser beam is emitted from the aperture. , Processing unevenness on the workpiece is likely to occur. In other words, the laser beam with a Gaussian energy density distribution has a narrow high-energy region. If the deviation occurs, unless the through hole is very narrow, the low energy region of the laser beam passes through the aperture and is irradiated on the workpiece, and satisfactory laser processing cannot be performed there. As a result, for example, when laser trimming of a color filter for a liquid crystal display device is performed, a dimensional error or variation occurs in the trimming width, which easily causes deterioration in display quality. In order to avoid such a problem, the aperture through hole is formed as narrow as possible so that even if the optical axis is slightly displaced, only the high energy region of the laser beam passes through the aperture. Although it is possible to do so, in that case, the ratio of the laser beam that is blocked by the aperture and is not effectively used is significantly increased, which is not preferable.

Therefore, as disclosed in Japanese Patent Laid-Open No. Sho 60-191689, an energy distribution conversion member for uniformizing the energy density distribution around the optical axis of the laser beam supplied from the laser oscillator is conventionally used in the optical system. There is proposed a laser processing machine which is incorporated so as to prevent the low energy region of the laser beam from irradiating the work piece even if the optical axis is slightly changed. That is, in such a conventional technique, a prism having a quadrangular pyramid refracting surface on the side on which a laser beam is incident (incident light side) is used as an energy distribution conversion member, and the refracting surface of this prism refracts in multiple directions. The energy density distribution of the laser beams is made uniform by superimposing the laser beams, which expands the high-energy region of the laser beam, making it less susceptible to optical axis fluctuations and irradiating the workpiece. Unevenness due to variations in the energy density of the laser beam is less likely to occur. Note that this publication also describes an example of using a prism having a gable roof type refracting surface on the incident light side as the energy distribution conversion member, but a quadrangular pyramid refracting surface is used rather than the prism. The energy density distribution of the laser beam can be made more uniform by using the prism.

[0006]

However, even if the high energy region of the laser beam is expanded by incorporating the energy distribution conversion member into the optical system as in the above-mentioned prior art, the laser beam is guided to the beam forming member such as the aperture. Since the divergence angle of the beam changes according to the characteristics of the laser oscillator, when the laser oscillator is replaced to perform the desired laser processing, the proportion of the laser beam that is blocked by the beam shaping member increases and energy efficiency increases. May worsen. Further, generally, the beam shaping member is provided with a rectangular through hole for shaping the beam shape into a rectangle suitable for high-speed laser processing. However, in the above-mentioned conventional technique, a laser beam having a substantially circular beam shape is energized. Since the laser beam having a substantially square beam shape and a substantially uniform energy distribution density is emitted from the distribution conversion member by being incident on the distribution conversion member, a laser beam that cannot pass through the rectangular through hole of the beam shaping member is generated. It was difficult to increase the energy efficiency by setting the ratio low.

[0007]

According to the present invention, before a laser beam supplied from a laser oscillator is guided to a member for making its energy density distribution uniform, the beam diameter of the laser beam and the aspect ratio of the beam shape are set. Variably adjusted. As a result, it is possible to avoid machining unevenness and deterioration of energy efficiency due to changes in the optical axis of the laser beam and the divergence angle, and to always obtain good processing quality, simply by performing adjustment.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In a laser processing machine of the present invention, a laser beam supplied from a laser oscillator is guided to a through hole of a beam forming member in an optical system to form a beam shape, and then directed toward a workpiece. In the laser processing machine for irradiation, the optical system includes a beam expander that variably adjusts the beam diameter of the laser beam, and a cylindrical lens group that variably adjusts the aspect ratio of the beam shape of the laser beam emitted from the beam expander. And an energy distribution conversion member for making the energy density distribution around the optical axis of the laser beam emitted from this cylindrical lens group uniform, and guiding the laser beam emitted from this energy distribution conversion member to the beam shaping member. It is configured as follows. As the cylindrical lens group,
A first cylindrical lens that expands the lateral width of the laser beam and a second cylindrical lens that expands the vertical width may be used in a plane perpendicular to the optical axis.

As described above, the laser beam machine in which the beam expander, the cylindrical lens group, and the energy distribution conversion member are incorporated in the optical system is the beam diameter of the laser beam supplied from the laser oscillator. By variably adjusting, even if the divergence angle changes, the size (cross-sectional area) of the laser beam toward the beam shaping member can be kept substantially constant, and
By variably adjusting the aspect ratio of the beam shape of the laser beam with the cylindrical lens group, it is possible to form an elliptical beam shape that matches the shape of the through hole of the beam shaping member. By making the laser beam that has passed through the panda and the cylindrical lens group incident on the energy distribution conversion member,
It is possible to make the energy density distribution around the optical axis of the laser beam whose beam shape and size have been adjusted uniform. Therefore, for example, when the laser oscillator is replaced and the divergence angle changes, the size of the laser beam is adjusted by the beam expander, and when the beam forming member is replaced and the through-hole shape changes, the cylindrical lens is changed. As long as the beam shape is adjusted in groups, it is possible to guide a laser beam having a substantially uniform energy density distribution to a predetermined region including the through hole of the beam shaping member. Therefore, it becomes easy to avoid unevenness in processing and deterioration in energy efficiency due to changes in the optical axis and divergence angle of the laser beam, and good processing quality can be stably obtained at low cost.

Further, as the energy distribution conversion member, a gable roof type refracting surface is provided on each of the incident light side and the outgoing light side, and the ridge line of the incident light side refracting surface and the ridge line of the outgoing light side refracting surface are provided. The use of prisms that are orthogonal to each other makes it possible to fabricate parts without impairing the function of making the energy density distribution of the laser beam uniform, as compared with the case of using a prism having a quadrangular pyramid refracting surface on the incident light side. The cost can be reduced.

[0011]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 is an explanatory view showing a layout of an optical system of a laser processing machine according to the present embodiment, FIG. 2 is a perspective view showing a homogenizer lens in the optical system, FIG. 3 is an overall side view of the laser processing machine, and FIG. Is a front view of an XY table incorporated in the laser processing machine, FIG. 5 is a side view of the XY table, a portion of which is not shown, and FIG. 6 is a liquid crystal display device for trimming a color filter using the laser processing machine. 7 is a process explanatory view showing the manufacturing technique of FIG. 7, and FIG. 7 is an explanatory view showing a process of laser trimming the color filter in the manufacturing process shown in FIG.

As shown in FIG. 3, the laser beam machine according to this embodiment guides a laser beam (YAG laser) supplied from a laser oscillator 5 by an optical system including a lens group, a beam splitter and the like to be processed. Machine body 1 to irradiate
An XY table 2 capable of transferring the mounted workpiece in two directions orthogonal to each other by a linear motor, a surface plate (base plate) 3 on which the processing machine body 1 and the XY table 2 are mounted, It is roughly configured by a vibration isolation table 4 on which the board 3 is placed. Note that reference numeral 21 in FIG. 4 indicates an optical surface plate on which the processing machine body 1 is mounted, and the optical surface plate 21 is supported by the surface plate 3 via columns 22.
Further, this laser processing machine is covered with a vacuum pump 8 and the like by a safety cover (not shown) made of a ferromagnetic material and having a degaussing effect, and a cover frame 6 shown by a chain line in FIG. 3 supports the safety cover. It becomes a frame.

The XY table 2 has a suction table 9 capable of sucking and fixing a workpiece to be mounted thereon by sucking air through a large number of suction holes provided on the upper surface.
An X table 10 for rotatably supporting the suction table 9 by inserting a columnar support shaft 10a into a shaft hole formed in the center of the bottom surface of the suction table 9, and the X table 1
A pair of parallel X-axis rail portions 11 slidably supporting 0
A support base 11 having a concave cross section formed by providing a on both side edges
X which is installed inside the support base 11 and linearly moves the X table 10 back and forth along the X-axis rail portion 11a.
Axis linear motor 12, X axis linear encoder 13 for detecting the position data of X table 10, Y table 14 on which support 11 is placed, and Y table 14 extending in the direction orthogonal to said X axis rail portion 11a. Of the three Y-axis rails 15 and 16 that slidably support the Y-axis, a Y-axis linear motor 17 that linearly reciprocates the Y-table 14 along these Y-axis rails 15 and 16, and position data of the Y-table 14. And a Y-axis linear encoder 18 for detecting However, between the X table 10 and each X-axis rail portion 11a, and between the Y table 14 and each Y-axis rail 1a.
Compressed air is blown out between the nozzles 5 and 16 from the air nozzles provided on the table side, so that the workpiece is moved to X-axis.
It can be smoothly transferred in the axial direction and the Y-axis direction.

In FIG. 4, reference numeral 3a designates a mounting groove provided on the upper surface of the surface plate 3 for inserting the bottom portions of the Y-axis rails 15 and 16 and positioning them in the width direction, and reference numeral 17
Reference numerals a, 17b, and 17c denote coils, magnets, and yokes forming the Y-axis linear motor 17, respectively.
Reference numerals 8b respectively indicate a detecting portion and a scale portion which constitute the Y-axis linear encoder 18. Further, in FIG. 5, reference numeral 10b indicates an air blowing surface of the X table 10, reference numerals 12a, 12b, and 12c respectively indicate a coil, a magnet, and a yoke constituting the X-axis linear motor 12, and a reference numeral 13
Reference numerals a and 13b respectively denote a detection portion and a scale portion which constitute the X-axis linear encoder 13, and a reference numeral 20 denotes a motor for rotationally driving the suction table 9 with the support shaft 10a as a rotation center.

The laser beam machine incorporating such an XY table 2 can move the workpiece mounted on the suction table 9 with high position accuracy in the horizontal plane by controlling the drive of the XY table 2. Therefore, by moving the workpiece along a predetermined locus with respect to the spot-shaped laser beam emitted from the tip (objective lens) of the optical system of the processing machine main body 1, a desired processing pattern by beam irradiation is obtained. Can be drawn on the work piece.

Next, the optical system of the processing machine body 1 will be described. The laser beam supplied from the laser oscillator 5 is reflected by the reflecting mirrors 23 and 24 and then expanded by the beam expander as shown in FIG. 25, the beam diameter is expanded to three times, for example, and then the first phase difference plate 26, which is also called a ¼λ polarizing plate, is incident to convert the linearly polarized light into circularly polarized light. Then, the circularly polarized laser beam emitted from the first retardation plate 26 is first incident on the first cylindrical lens 27, and the lateral width of the laser beam is expanded in a plane perpendicular to the optical axis. When the laser beam is incident on the second cylindrical lens 28 and the vertical width of the laser beam is expanded in a plane perpendicular to the optical axis, the beam shape of the laser beam becomes an elliptical shape by passing through the cylindrical lens groups 27 and 28. Become. In the present embodiment, the distance between the plurality of lenses forming the beam expander 25 can be changed, so that the beam expander 25 can variably adjust the beam diameter of the laser beam. In addition, in this embodiment, since the distance between the first and second cylindrical lenses 27 and 28 can be changed,
The cylindrical lens groups 27 and 28 can variably adjust the aspect ratio of the beam shape of the laser beam.

The laser beam having an elliptical cross section emitted from the second cylindrical lens 28 is a homogenizer lens 2 having a predetermined shape which is an energy distribution conversion member.
Since it is incident on the laser beam 9, the light beam is refracted in four directions and superposed, the energy density distribution around the optical axis of the laser beam is made uniform. In this embodiment, as the homogenizer lens 29, as shown in FIG. 2, the gabled roof-shaped refracting surfaces 29a and 29 are provided on the incident light side and the outgoing light side, respectively.
Since a prism having b and having the ridge line 29c of the refracting surface 29a on the incident light side and the ridge line 29d of the refracting surface 29b on the outgoing light side orthogonal to each other is used, a quadrangular pyramid refracting surface is formed on one surface. Compared with the case where the prism provided is used, the component manufacturing cost can be reduced without impairing the function of making the energy density distribution of the laser beam uniform.

The laser beam having a substantially uniform energy density distribution emitted from the homogenizer lens 29 is reflected by the reflection mirror 30, and then the first beam splitter 3
It is split into linearly polarized light which is incident on 1 and travels in two directions, whereby two split beams capable of simultaneously laser processing a plurality of locations are obtained. Then, the first beam splitter 3
One of the split beams emitted from the first
After being incident on the phase difference plate 32 of the above and converted into circularly polarized light again, it passes through the reflection mirror 34 and the second beam splitter 36.
And is split into two parallel linearly polarized lights. Similarly, the other split beam emitted from the first beam splitter 31 is rotated by the rotatable third retardation plate 33.
Is incident on the second beam splitter 36 through the reflection mirror 35, and is then split into two parallel linearly polarized lights. That is, one laser beam emitted from the laser oscillator 5 is emitted from the second beam splitter 36 in a state of being divided into a total of four laser beams parallel to each other after passing through a predetermined optical path. Has become. By appropriately rotating the second and third retardation plates 32 and 33, the power adjustment for correcting the variation in the power (energy level) of each split beam can be relatively easily performed.

Each split beam emitted from the second beam splitter 36 in this way passes through the through hole 37a of the aperture 37, which is a beam shaping member, and then passes through the lens group or the like to the objective lens located at the tip of the optical path. (See FIG. 7), and the objective lens irradiates the workpiece on the XY table 2 with four parallel split beams in spots. That is, a rectangular through hole 37a is formed at four positions in the aperture 37, and when each split beam passes through the through hole 37a opened in the optical path, the beam shape is a rectangular shape suitable for high-speed laser processing. It is designed to be molded into. In addition,
Since the laser processing machine according to the present embodiment is for performing laser trimming processing of the color filter for the liquid crystal display device, the width dimension of the through hole 37a of the aperture 37 is set to be equal to the trimming processing width.

As described above, the processing machine main body 1 in which the beam expander 25, the cylindrical lens groups 27 and 28, and the homogenizer lens 29 are incorporated in the optical system is
By variably adjusting the beam diameter of the laser beam supplied from the laser oscillator 5 with the beam expander 25, the size (cross-sectional area) of the laser beam heading to the aperture 37 can be made substantially constant even when the divergence angle changes. Further, the aspect ratio of the beam shape of the laser beam can be variably adjusted by the cylindrical lens groups 27 and 28 to form an oval beam shape that matches the shape of the through hole 37a of the aperture 37. The laser beam that has passed through the beam expander 25 and the cylindrical lens groups 27 and 28 is made incident on the homogenizer lens 29, so that the energy around the optical axis of the laser beam whose beam shape and size have been adjusted is adjusted. The density distribution can be made uniform. Therefore, for example, when the laser oscillator 5 is replaced and the divergence angle changes, the size of the laser beam is adjusted by the beam expander 25, and when the aperture 37 is replaced and the through hole shape changes, the If the beam shape is adjusted by changing the distance between the first and second cylindrical lenses 27 and 28, it is possible to guide a laser beam having a substantially uniform energy density distribution to a predetermined region including the through hole 37a of the aperture 37. it can. In other words, the processing machine body 1 is configured to avoid processing unevenness and energy efficiency deterioration due to changes in the optical axis of the laser beam and the divergence angle by performing simple adjustments. Various processing qualities can be stably obtained at low cost.

Next, as an example of using the above-mentioned laser processing machine, laser trimming processing of a color filter in the manufacturing process of a liquid crystal display device will be described.

Before performing such laser trimming processing,
First, as shown in FIG. 6A, by patterning ITO or the like on one surface of a transparent substrate 50 such as a glass substrate, a large number of transparent electrodes 51 extending in one direction at regular pitch intervals are formed. Then, as shown in FIG. 6B, R is formed on each transparent electrode 51 by a method such as an electrodeposition method or a printing method.
(Red), G (green), and B (blue) color filters 52 are laminated in a predetermined arrangement. By the way, in the example of FIG. 6 (b),
The color filters 52 are laminated in the order of R, G, B, R, G, B, R, .... And after stacking, about 250 ℃
Is baked to solidify the color filter 52.

Thereafter, the transparent substrate 50 is mounted on the suction table 9 of the XY table 2, and the XY table 2 is attached.
While controlling the R, G, B color filters 52 by irradiating a plurality of split beams at a constant pitch in a direction orthogonal to the longitudinal direction of the color filters 52.
Is partially removed by laser trimming, and as a result, as shown in FIG. 6C, a color filter 52 in which a light-shielding film is not formed but is arranged in a predetermined arrangement is obtained. Note that, in FIG. 7 schematically showing such laser trimming, the transparent substrate 50 on the suction table 9 is shown.
Are transported in the direction orthogonal to the paper surface of the figure, and the spot-shaped laser beam S emitted from the objective lens 38 of the processing machine main body 1 removes unnecessary portions of the color filter 52 with the movement.

After the unnecessary portion of the color filter 52 is removed, a black resist is applied to the color filter forming surface of the transparent substrate 50 and dried, and then exposure light is irradiated from the other surface side and development is performed after exposure. By processing and removing the unexposed black resist, the light-shielding film 53 is formed in the gap portion around the color filter 52, as shown in FIG. 6D.

In such a manufacturing technique, since the laser beam machine irradiates a plurality of divided beams to a plurality of positions on the color filter forming surface of the transparent substrate 50 at the same time, the laser trimming process of the color filter 52 is efficiently performed in a short time. You can do it well. At that time, since the laser beam having a substantially uniform energy density distribution is emitted from the objective lens 38 of the processing machine body 1 at any time, highly accurate laser processing with few dimensional errors and variations in the trimming width of the color filter 52 can be performed. Good processing quality can be expected.

[0026]

The present invention is embodied in the form described above and has the following effects.

Since a laser beam whose beam shape and size are appropriately adjusted by the beam expander and the cylindrical lens group is passed through an energy distribution conversion member such as a homogenizer lens, it is incident on a beam forming member such as an aperture. , A laser beam having a substantially uniform energy density distribution can be guided to a predetermined region including the through hole, and therefore, it is possible to avoid machining unevenness and deterioration of energy efficiency due to changes in the optical axis and divergence angle of the laser beam. It becomes easier and good processing quality can be stably obtained at low cost.

As the energy distribution conversion member, a gable roof type refracting surface is provided on each of the incident light side and the outgoing light side, and the ridge line of the incident light side refracting surface and the ridge line of the outgoing light side refracting surface are provided. The use of prisms that are orthogonal to each other makes it possible to fabricate parts without impairing the function of making the energy density distribution of the laser beam uniform, as compared with the case of using a prism having a quadrangular pyramid refracting surface on the incident light side. The cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a layout of an optical system of a laser beam machine according to this embodiment.

FIG. 2 is a perspective view showing a homogenizer lens in the optical system.

FIG. 3 is an overall side view of the laser processing machine.

FIG. 4 is a front view of an XY table incorporated in the laser processing machine.

FIG. 5 is a side view of the XY table, a part of which is not shown.

FIG. 6 is a process explanatory view showing a manufacturing technique of a liquid crystal display device which performs trimming processing of a color filter using the laser processing machine.

FIG. 7 is an explanatory diagram showing a step of laser-trimming a color filter in the manufacturing process shown in FIG.

[Explanation of symbols]

1 Processing Machine Main Body 2 XY Table 5 Laser Oscillator 9 Adsorption Table 10 X Table 14 Y Table 25 Beam Expander 26, 32, 33 Phase Difference Plate (1 / 4λ Polarizing Plate) 27, 28 Cylindrical Lens 29 Homogenizer Lens (Energy Distribution Conversion) Member) 29a, 29b Refractive surface 29c, 29d Ridge line 31, 36 Beam splitter 37 Aperture (beam shaping member) 37a Through hole 50 Transparent substrate 51 Transparent electrode 52 Color filter

Claims (4)

[Claims] 1. A laser processing machine for guiding a laser beam supplied from a laser oscillator to a through hole of a beam forming member in an optical system to form a beam shape, and thereafter irradiating the beam to a workpiece. The optical system includes a beam expander that variably adjusts the beam diameter of the laser beam, a cylindrical lens group that variably adjusts the aspect ratio of the beam shape of the laser beam emitted from this beam expander, and a cylindrical lens group that emits the laser beam. An energy distribution conversion member for making the energy density distribution around the optical axis of the laser beam uniform, and guiding the laser beam emitted from the energy distribution conversion member to the beam shaping member. Laser processing machine. 2. The cylindrical lens group according to claim 1, wherein the cylindrical lens group includes a first cylindrical lens that expands a lateral width of a laser beam in a plane perpendicular to the optical axis and a second cylindrical lens that expands a longitudinal width. A laser processing machine characterized by comprising. 3. The energy distribution conversion member according to claim 1, wherein the energy distribution conversion member has a gable roof-shaped refracting surface on each of an incident light side and an outgoing light side, and a ridgeline of the refracting surface on the incident light side. A laser beam machine using a prism in which a ridge line of a refracting surface on the outgoing light side is orthogonal to each other. 4. The laser processing machine according to claim 1, wherein the object to be processed is a color filter which is a constituent member of a liquid crystal display device.