KR20200063996A - Laser processing apparatus - Google Patents

Abstract

The present invention relates to a laser processing apparatus for simultaneously processing a bonded substrate from both sides thereof, in which a laser beam does not return to a laser light source. The laser processing apparatus (1) which is an apparatus for simultaneously processing a bonded substrate (W) from both sides thereof, comprises a laser oscillator (15), a polarizing beam splitter (37), and first and second optical systems (5B, 5C). The polarizing beam splitter (37) branches a laser beam (L) from the laser oscillator into first and second branch beams (L1, L2). The polarization beam splitter (37) rotates the polarization direction of the second branch beam (L2) with respect to the first branch beam (L1) at a predetermined angle. The first optical system (5B) irradiates a first surface of a substrate (W) with the first branch beam (L1). The second optical system (5C) irradiates a second surface of the substrate (W) with the second branch beam (L2).

Description

Laser processing equipment {LASER PROCESSING APPARATUS}

The present invention relates to a laser processing apparatus, particularly a laser processing apparatus for simultaneously processing from both sides of a substrate.

As a method of scribing a glass substrate, laser processing is known. In laser processing, an infrared picosecond laser is used, for example. In this case, a method is known in which a scribe line is formed by intermittently performing a laser pulsed internal processing in a plane direction to form a plurality of laser filaments (for example, refer to Patent Document 1).

In the technique shown in Patent Document 1, the convergent laser beam is composed of pulses having energy and pulse duration selected to produce filaments in the substrate. Then, a plurality of filaments are formed side by side in the plane direction, thereby forming a scribe line.

Japanese Patent Publication No. 2013-536081

When the object is a bonded substrate, it is desired to simultaneously divide the scribe lines of the two substrates. The bonded substrate is, for example, a mother substrate on which a substrate on which a thin film transistor (TFT) is formed and a substrate on which a color filter (CF) is formed are bonded through a sealing material. By splitting this mother substrate, individual liquid crystal panels are obtained.

The above-described processing is a laser processing apparatus that divides laser light emitted from a laser generating apparatus and simultaneously irradiates them to both surfaces of a bonded substrate.

In the above structure, the optical system of one laser light after division is set as the first optical system, and the optical system of the other laser light after division is set as the second optical system. When the laser light of the first optical system is irradiated to a position where there is no bonded substrate, or when it is irradiated but passed through the bonded substrate, there is a possibility that it returns to the laser generator through the second optical system. Moreover, there is a possibility that the laser light of the second optical system is irradiated to a position where there is no bonding substrate or is irradiated to the bonding substrate, but passes through and returns to the laser generating device through the first optical system. When the above occurs, the laser generating device may fail, or the laser oscillation may become unstable.

An object of the present invention is to prevent a laser light from returning to a laser light source in a laser processing apparatus for processing simultaneously from both sides of a substrate.

Hereinafter, a plurality of aspects will be described as a means for solving the problem. These aspects can be arbitrarily combined as needed.

A laser processing apparatus according to one aspect of the present invention is an apparatus for simultaneously processing from both sides of a substrate, and includes a single laser light source, a diverging portion, a polarization direction rotating portion, a first optical system, and a second optical system. .

The branching unit splits the laser light from the laser light source into first and second branched lights.

The polarization direction rotating unit rotates the polarization direction of the second branch light with respect to the first branch light by a predetermined angle.

The first optical system irradiates the first branch light to the first surface of the substrate.

The second optical system irradiates the second branch light to the second surface of the substrate.

In this apparatus, the first branch light is irradiated to the first surface of the substrate. The first branch light passing through the substrate or passing through the substrate passes through the second optical system and is incident on the rotating portion in the polarization direction. In this case, the 1st branch light is reflected by the rotation part of a polarization direction, and does not return to a laser light source. The second branch light is irradiated to the second surface of the substrate. The second branch light passing through the substrate or passing through the substrate passes through the first optical system and is incident on the rotating portion in the polarization direction. In this case, the second branch light is reflected by the rotating portion in the polarization direction, and does not return to the laser light source. Therefore, in the laser processing apparatus for simultaneously processing from both sides of the substrate, it is prevented that the laser light is returned to the laser light source.

The branching portion and the rotating portion in the polarization direction may be formed of one polarizing beam splitter.

The branch part may consist of one unpolarized beam splitter.

The polarization direction rotating portion may include a first polarizing plate formed on the first optical system and a second polarizing plate formed on the second optical system.

In the present invention, in the laser processing apparatus for simultaneously processing from both sides of the substrate, the laser light does not return to the laser light source.

1 is a schematic view of a laser processing apparatus according to a first embodiment of the present invention.
2 is a schematic cross-sectional view of a substrate in a scribe line forming process.
3 is a schematic plan view of a substrate in a scribe line forming process.
4 is a schematic view of a laser processing apparatus according to a second embodiment of the present invention.
5 is a schematic view of a laser processing apparatus according to a third embodiment of the present invention.

1. First embodiment

(1) Overall composition

The overall configuration of the laser processing apparatus 1 will be described with reference to FIG. 1. 1 is a schematic view of a laser processing apparatus according to a first embodiment of the present invention.

The laser processing apparatus 1 is an apparatus for forming a scribe line on a bonded substrate W (hereinafter, referred to as "substrate W"). The substrate W has a first substrate W1 and a second substrate W2. The substrate W is, for example, a liquid crystal glass substrate.

2, the 1st board|substrate W1 and the 2nd board|substrate W2 are bonded by the sealing material 30. As shown in FIG. The first substrate W1 has an outer surface 25 and an inner surface 26. The second substrate W2 has an outer surface 27 and an inner surface 28. The sealing material 30 is arrange|positioned between the inner surface 26 and the inner surface 28.

The laser processing device 1 has a laser device 3. The laser device 3 forms a first scribe line S1 on the first substrate W1 of the substrate W, and a laser light for forming a second scribe line S2 on the second substrate W2. It is a device that generates.

The laser device 3 has a laser oscillator 15 (an example of a laser light source) and a laser control unit 17. The laser oscillator 15 oscillates a picosecond laser of a predetermined wavelength, for example, at a wavelength between 340 and 1100 nm. The laser control unit 17 can control driving of the laser oscillator 15 and laser power.

The laser processing device 1 has a transmission optical system 5. The transmission optical system 5 has a lead-out section 5A, a first optical system 5B, and a second optical system 5C. The lead-out portion 5A is a portion from which the laser light is derived from the laser oscillator 15. In the 1st optical system 5B and the 2nd optical system 5C, the laser light L from the lead-out part 5A diverges, and the 1st branch light L1 and the 2nd branch light L2 pass through. .

The lead-out section 5A has a shutter 31, a first mirror 32, two beam expanders 33, 34, and a wave plate 35 in this order from the laser oscillator 15. . The shutter 31 is connected to a shutter driving device (not shown) and is movable between a position to block the laser light and a position to pass it. The beam expanders 33 and 34 enlarge the beam diameter of the emitted laser light to a predetermined diameter, and make it approximately parallel light. The wavelength plate 35 is a 1/2 wavelength plate, and by rotating, the ratio of the first branch light L1 and the second branch light L2, which will be described later, can be adjusted.

The transmission optical system 5 has a polarizing beam splitter 37 (an example of a branching portion and a rotating portion of the polarization direction). The polarizing beam splitter 37 is formed at the end of the lead-out portion 5A. The polarization beam splitter 37 diverts the laser light L into the first branch light L1 and the second branch light L2. Specifically, the first branch light L1 is reflected light of s polarization, and the second branch light L2 is transmitted light of p polarization. The polarization beam splitter 37 rotates the polarization direction of the second branch light L2 at a predetermined angle with respect to the first branch light L1. Specifically, the polarization directions of the first branch light L1 and the second branch light L2 are 90 degrees different from each other. In this embodiment, the polarizing beam splitter 37 is of a prism type, but may be a flat type or a wedge substrate type.

In the first optical system 5B, the second mirror 41, the third mirror 42, the fourth mirror 43, and the first condensing lens 44 are in this order from the polarizing beam splitter 37. I have it. The second mirror 41 is 90 degrees so that the direction of the first branch light L1 extending parallel to the main surface of the substrate W from the polarization beam splitter 37 is perpendicular to the substrate W Different. The third mirror 42 makes the direction of the first branch light L1 from the second mirror 41 different by 90 degrees so as to be parallel to the substrate W. The fourth mirror 43 makes the first branch light L1 from the third mirror 42 different by 90 degrees so as to be orthogonal to the substrate W. As described above, the first branch light L1 is incident on the first substrate W1 of the substrate W through the first condensing lens 44. In addition, the second mirror 41, the third mirror 42, and the fourth mirror 43 do not change the polarization direction of the first branch light L1 (polarization perpendicular to the paper in FIG. 1). Direction).

The first optical system 5B further has an optical path length adjusting unit 61. The optical path length adjustment unit 61 moves the second mirror 41 and the third mirror 42 in the same direction at the same time, so that the optical path length of the first optical system 5B is the same as the optical path length of the second optical system 5C. It is a device to do. The optical path length adjusting part 61 has a support part (not shown) integrally supporting the second mirror 41 and the third mirror 42, and a moving part (not shown) for moving the support part. The optical path length adjustment unit 61 is controlled by the control unit 9.

The 2nd optical system 5C has the 5th mirror 51, the 6th mirror 52, and the 2nd condensing lens 53 from the polarizing beam splitter 37 in this order. The fifth mirror 51 makes the direction of the second branch light L2 extending perpendicular to the main surface of the substrate W from the polarization beam splitter 37 to be 90 degrees different from the substrate W side. The sixth mirror 52 makes the direction of the second branch light L2 from the fifth mirror 51 different by 90 degrees so as to be orthogonal to the substrate W. As described above, the second branch light L2 is incident on the second substrate W2 of the substrate W through the second condensing lens 53. Further, the fifth mirror 51 and the sixth mirror 52 are set so as not to change the polarization direction of the second branch light L2 (to maintain the polarization direction parallel to the paper surface in FIG. 1). have.

The laser processing device 1 has a driving device 7 that holds and drives the substrate W. Specifically, the drive device 7 adsorbs the substrate W. The drive unit 7 is moved by the drive unit operation unit 13. The driving device operation unit 13 moves the driving device 7 in the horizontal direction.

The laser processing device 1 includes a control unit 9. The control unit 9 includes a processor (eg, CPU), a storage device (eg, ROM, RAM, HDD, SSD, etc.), and various interfaces (eg, A/D converter, D/A converter) , Communication interface, etc.). The control unit 9 performs various control operations by executing a program stored in the storage unit (corresponding to part or all of the storage area of the storage device).

The control unit 9 may be composed of a single processor, or may be composed of a plurality of independent processors for each control.

The control unit 9 can control the laser control unit 17, the driving device operation unit 13, and the optical path length adjustment unit 61.

Although not shown, a sensor for detecting the size, shape and position of the substrate W, a sensor and a switch for detecting the state of each device, and an information input device are connected to the control unit 9.

(2) Method of scribing

The scribe processing method by the laser processing apparatus 1 is demonstrated using FIG. 2 and FIG. 2 is a schematic cross-sectional view of a substrate in a scribe line forming process. 3 is a schematic plan view of a substrate in a scribe line forming process.

(2-1) First branch light irradiation step

The first scribe line S1 is formed by irradiating the first branch light L1 from the first substrate W1 side. Specifically, a plurality of first processing marks 21 formed along the optical axis inside the first substrate W1 are continuously formed in a plane direction (in the direction perpendicular to the ground).

In this embodiment, at one point when viewed from the plane of the first scribe line S1, the plurality of first machining marks 21 are simultaneously formed in the thickness direction.

(2-2) Second branch light irradiation step

The second scribe line S2 is formed by irradiating the second branch light L2 from the second substrate W2 side. Specifically, a plurality of second processing marks 23 formed along the optical axis inside the second substrate W2 are continuously formed in the plane direction (orthogonal to the ground) along the first processing marks 21.

In this embodiment, at one point when viewed from the plane of the second scribe line S2, a plurality of second processing marks 23 are simultaneously formed in the thickness direction.

(2-3) Irradiation conditions for the substrate W of the first branch light and the second branch light

The first branch light L1 and the second branch light L2 are simultaneously irradiated to the same position when viewed from the plane of the substrate W. In short, both are not offset in position and timing.

Moreover, the 1st branch light L1 and the 2nd branch light L2 are irradiated perpendicularly to the main surface of the board|substrate W.

(2-4) Shape when viewed from the plane of the scribe line

3, the 1st scribe line S1 and the 2nd scribe line S2 form the outer periphery of the substantially rectangular cell C. As shown in FIG. The cell C has a curved corner. Therefore, the laser processing apparatus in which the 1st branch light L1 and the 2nd branch light L2 are irradiated to the same position from both sides as mentioned above is preferable.

(2-5) Treatment of retrograde divergent light

In this embodiment, a principle will be described in which the first branch light L1 and the second branch light L2 that reverse the optical systems on opposite sides do not return to the laser oscillator 15.

When the first branch light L1 irradiated to the position without the substrate W passes through the processing point of the substrate W, the second optical system 5C is reversed to enter the polarization beam splitter 37. In this case, the first branch light L1 that reverses the second optical system 5C is reflected on the right side of the drawing in the polarization beam splitter 37 and does not return to the laser oscillator 15. The above operation is the same for the first branch light L1 that has been irradiated onto the substrate W but has passed.

When the second branch light L2 irradiated to the position without the substrate W passes through the processing point of the substrate W, it reverses the first optical system 5B and enters the polarization beam splitter 37. In this case, the second branch light L2 that reverses the first optical system 5B passes through the polarization beam splitter 37 to the right side of the drawing, and does not return to the laser oscillator 15. The above operation is the same in the case of the second branch light L2 irradiated to the substrate W but passed.

Therefore, in the laser processing apparatus 1 for simultaneously processing from both sides of the bonding substrate W, the laser light does not return to the laser oscillator 15.

(2-6) Effect of optical path length adjuster

Further, the optical path length adjusting unit 61 can make the optical path length of the first optical system 5B and the optical path length of the second optical system 5C the same. Therefore, in the substrate W, the beam diameter of the first branch light L1 and the beam diameter of the second branch light L2 are the same or almost the same (within 5% of error). Therefore, the first scribe line S1 and the second scribe line S2 are formed under the same conditions. Moreover, there is no need to change other conditions of the first optical system 5B and the second optical system 5C.

2. Second embodiment

In the first embodiment, a polarizing beam splitter is used to make the polarization direction of the branch light different, but other means may be used to make the polarization direction of the branch light different.

4, such an embodiment is described as a 2nd embodiment. 4 is a schematic view of a laser processing apparatus according to a second embodiment of the present invention.

The basic configuration of the second embodiment is the same as that of the first embodiment, and the following description will be mainly focused on different points.

In this embodiment, the laser processing apparatus 1A has a non-polarization beam splitter 37A (an example of a polarization direction rotating portion) instead of the polarization beam splitter.

The first optical system 5B has a first polarizing plate 71. The first polarizing plate 71 is formed between the unpolarized beam splitter 37A and the second mirror 41. The position of the 1st polarizing plate 71 is not specifically limited.

The laser processing apparatus 1A has a second polarizing plate 72. The second polarizing plate 72 is formed between the fifth mirror 51 and the sixth mirror 52. The position of the second polarizing plate 72 is not particularly limited.

The 1st polarizing plate 71 and the 2nd polarizing plate 72 of the optical axis with respect to the polarization direction of incident laser light are made so that the polarization direction of the 1st branch light L1 and the 2nd branch light L2 differs 90 degrees from each other. The angle is set.

When the first branch light L1 passes through the processing point of the substrate W, the second optical system 5C is reversed and absorbed or reflected by the second polarizing plate 72. In other words, the first branch light L1 that reverses the second optical system 5C cannot pass through the second polarizing plate 72.

When the second branch light L2 passes through the processing point of the substrate W, the first optical system 5B is reversed and absorbed or reflected by the first polarizing plate 71. That is, the second branch light L2 that has passed through the first optical system 5B cannot pass through the first polarizing plate 71.

In addition, when the retrograde divergent light is reflected from the first polarizing plate 71 or the second polarizing plate 72, the retrograde divergent light is reflected in an oblique direction (for example, 90°) from the optical path of the processing laser. .

As a result of the above, the first branch light L1 and the second branch light L2 that reverse the optical systems on opposite sides do not return to the laser oscillator 15.

3. Third embodiment

In the first embodiment, the first optical system has an optical path length adjustment unit, but the optical path length adjustment unit may be omitted.

5, such an embodiment is described as a third embodiment. 5 is a schematic view of a laser processing apparatus according to a third embodiment of the present invention.

The basic configuration of the third embodiment is the same as that of the first embodiment, and the following description will mainly focus on different points.

The 1st optical system 5B does not have the 3rd mirror 42 of the 1st Embodiment, and the 4th mirror 43, and further has no optical path length adjustment part.

Also in this embodiment, the first branch light L1 and the second branch light L2 that reverse the optical systems on opposite sides do not return to the laser oscillator 15.

4. Other embodiments

As mentioned above, although several embodiment of this invention was described, this invention is not limited to the said embodiment, Various changes are possible within the range which does not deviate from the summary of invention. In particular, the plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

The substrate may be a brittle material substrate such as glass, semiconductor wafer, or ceramics, and is not particularly limited.

The present invention can be widely applied to laser processing devices for processing simultaneously from both sides of a substrate.

1: laser processing device
3: laser device
5: transmission optical system
5A: Derivation part
5B: 1st optical system
5C: Second optical system
15: laser oscillator
37: polarized beam splitter
71: 1st polarizing plate
72: second polarizing plate
W: Bonding board
W1: first substrate
W2: Second substrate

Claims (4)

A laser processing device for simultaneously processing from both sides of a substrate,
A single laser light source,
A branching section for splitting the laser light from the laser light source into first and second branched light,
A polarization direction rotation unit for rotating a polarization direction of the second branch light with respect to the first branch light at a predetermined angle;
A first optical system for irradiating the first branch light to the first surface of the substrate;
And a second optical system that irradiates the second branch light to the second surface of the substrate. According to claim 1,
The branching part and the rotation part of the polarization direction are made of one polarizing beam splitter, and a laser processing device. According to claim 1,
The branching part is composed of one unpolarized beam splitter,
The polarization-direction rotating portion is composed of a first polarizing plate formed on the first optical system and a second polarizing plate formed on the second optical system. According to claim 1,
A laser processing apparatus further comprising an optical path length adjusting unit capable of adjusting the length of the optical path length of the first optical system.

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