JP2008311333A - Method for dividing substrate, and method for manufacturing display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser scribing method for dividing a division object substrate manufactured by sticking quartz substrates through an adhesive layer without generating air bubbles. <P>SOLUTION: In a laser scribing method for dividing a division object substrate 4 manufactured by sticking quartz substrates 1 and 2 through an adhesive layer 3 by irradiating a part of the quartz substrates 1 and 2 with a laser beam from a laser beam irradiator 10 and forming a modifying region in a predetermined range, the division object substrate 4 can be divided without generating air bubbles in the adhesive layer 3 by correcting the aberration of the laser beam irradiator 10 so that energy density becomes low in or near the adhesive layer 3 and becomes high at a part ahead of the adhesive layer 3 in the direction of laser beam irradiation when the modifying region is formed at a part ahead of the adhesive layer 3 in the direction of laser beam irradiation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for dividing a substrate by irradiating a laser beam, particularly a substrate dividing method for dividing a substrate by forming a modified region inside the substrate, and a display device for dividing a substrate for a display device thereby. It relates to a manufacturing method.

Examples of such a substrate dividing method include those described in the following patent documents. Among them, Patent Document 1 discloses that a modified region is generated inside a substrate, and an external force is applied to a portion where the modified region is formed to divide the substrate. Patent Document 2 discloses that a plurality of modified regions are formed in the thickness direction of the substrate, and an external force is applied to that portion to divide the substrate. Patent Document 3 discloses that the major axis of the laser beam polarization direction coincides with the scanning direction.
JP 2002-192367 A JP 2002-205180 A JP 2002-192369 A

By the way, for example, as a TFT (Thin Film Transistor) element substrate used in a liquid crystal display panel, two quartz substrates are bonded together through an adhesive layer to form a substrate to be divided, as described in each of the above patent documents. When the substrate to be divided is generated by irradiating the substrate to be divided with the laser beam and the substrate is divided by applying an external force, bubbles are generated when the laser beam is condensed on the adhesive layer. It has been found that it causes display defects even in the TFT pixel region. However, the above-mentioned patent documents do not disclose measures for effectively preventing the generation of bubbles in the adhesive layer.
The present invention has been made paying attention to the above problems, and a substrate dividing method capable of dividing a substrate bonded via an adhesive layer without generating bubbles, and An object of the present invention is to provide a method for manufacturing a display device.

The substrate dividing method of the present invention is a substrate dividing method for dividing a pair of substrates by irradiating a pair of substrates bonded via an adhesive layer with a laser beam. The laser beam aberration correction is performed so that the energy density in the vicinity of the layer is small and the energy density in the laser beam irradiation direction ahead of the adhesive layer is increased.
According to the present invention, since the energy density in the adhesive layer or in the vicinity of the adhesive layer is small and the aberration correction of the laser light is corrected so that the energy density ahead of the laser light irradiation direction is larger than the adhesive layer. The substrate can be divided without generating bubbles in the adhesive layer.

Further, the substrate dividing method of the present invention forms a plurality of modified regions in the thickness direction of a pair of substrates by irradiating the pair of substrates with laser light, and applies an external force to the pair of substrates. The substrate is divided.
According to the present invention, a plurality of modified regions are formed in the thickness direction of a pair of substrates by irradiating the pair of substrates with laser light, and the pair of substrates is divided by applying an external force to the pair of substrates. Since it was set as the structure, a board | substrate can be divided | segmented reliably, without generating a bubble in an adhesive bond layer.
The substrate dividing method of the present invention is characterized in that the laser beam is any one of a femtosecond laser, a picosecond pulse laser, and a YAG laser.

According to the present invention, since the laser light is any one of a femtosecond laser, a picosecond pulse laser, or a YAG laser, the substrate can be divided using a laser suitable for dividing the substrate.
The display device manufacturing method of the present invention is characterized in that a substrate for a display device is divided from a pair of substrates by the substrate dividing method of the present invention.
According to this invention, since the display device substrate is divided from the pair of substrates by the substrate dividing method of the present invention, the display device can be manufactured using a substrate having no bubbles in the adhesive layer.

  Next, embodiments of the substrate dividing method and the display device manufacturing method of the present invention will be described with reference to the drawings. In the present embodiment, in the process of manufacturing a liquid crystal display panel constituting a liquid crystal display device, a TFT element substrate used in the liquid crystal display panel is cut out (divided) from a wafer-shaped substrate to be divided. Incidentally, as is well known, a liquid crystal display panel includes an element substrate having a TFT element, a counter substrate having a counter electrode, and liquid crystal filled in a gap between the two substrates.

  FIG. 1 shows a plan view of a substrate to be divided immediately before being divided. A plurality of quartz substrates are bonded to the division target substrate, and pixel electrodes and the like (not shown) are also formed. FIG. 2 is a conceptual diagram of a laser scribing method for dividing a substrate to be divided with laser light (beam). In the figure, as an example of the substrate 4 to be divided, a dust-proof quartz substrate 2 having a thickness of 1.1 mm is bonded to an element quartz substrate 1 having a thickness of 1.2 mm with an adhesive layer 3 interposed therebetween. Is shown. Then, a modified region is generated by irradiating and condensing a laser beam from a laser beam irradiating apparatus, which will be described later, mainly on the quartz substrates 1 and 2 of the substrate to be divided 4, and in the thickness direction of a predetermined divided section. A plurality of layers are formed, and then the substrate is divided by applying an external force.

  FIG. 3 shows a schematic configuration of the laser beam irradiation apparatus. The laser beam irradiation apparatus 10 includes a laser light source 11 that emits a laser beam, a dichroic mirror 12 that reflects the emitted laser beam, and a condenser lens 13 that condenses the reflected laser beam. In addition, the laser beam irradiation apparatus 10 includes a stage 17 on which the above-described division target substrate 4 is placed, and the stage 17 with respect to the condenser lens 13 in two directions orthogonal to the horizontal plane, that is, the X axis and the Y axis shown in FIG. With respect to the X-axis slide portion 20 and the Y-axis slide portion 21 that are moved in the axial direction and the division target substrate 4 placed on the stage 17, the height direction of the condenser lens 13, that is, the Z-axis shown in FIG. A Z-axis slide mechanism 14 that adjusts the position of the condensing point of the laser beam by changing the position of the direction, and is arranged between the condensing lens 13 and the substrate to be divided 4 so as to be orthogonal to the optical axis, and laser A quartz glass plate 16 for correcting the aberration of the beam and an imaging device 22 positioned on the opposite side of the condenser lens 13 with the dichroic mirror 12 interposed therebetween are provided.

  The laser beam irradiation apparatus 10 includes a main computer 30 that controls the above-described components. The main computer 30 includes image processing for processing image information captured by the imaging device 22 in addition to a CPU and various memories. Part 34 is provided. The imaging device 22 incorporates a coaxial incident light source and a CCD (solid-state imaging device), and the visible light emitted from the coaxial incident light source passes through the condenser lens 13 to be focused. The main computer 30 is connected to an input unit 35 for inputting data of various processing conditions used during laser processing and a display unit 36 for displaying various information during laser processing. Further, a laser control unit 31 that controls the output, pulse width, and pulse period of the laser light source 11, a lens control unit 32 that drives the Z-axis slide mechanism 14 to control the position of the condenser lens 13 in the Z-axis direction, A stage control unit 33 that drives a servo motor (not shown) that moves the X-axis slide unit 20 and the Y-axis slide unit 21 along the rails 18 and 19 is connected.

  The Z-axis slide mechanism 14 that moves the condensing lens 13 in the Z-axis direction has a built-in position sensor capable of detecting the moving distance, and the lens control unit 32 detects the output of the position sensor and collects the light. The position of the lens 13 in the Z-axis direction can be controlled. Therefore, if the condensing lens 13 is moved in the Z-axis direction so that the focus of the visible light emitted from the coaxial incident light source of the imaging device 22 coincides with the surface of the division target substrate 4, the thickness of the division target substrate 4 is increased. Can be measured.

  As the laser light source 11, for example, a so-called femtosecond laser that emits a laser beam using titanium sapphire as a solid light source with a pulse width of femtosecond is used. In this case, the pulse laser beam has wavelength dispersion characteristics, the center wavelength is 800 nm, the pulse width is about 300 fs (femtosecond), the pulse period is 5 kHz, and the output is about 1000 mW. Instead of this, the laser light source 11 is a picosecond pulse laser (center wavelength: 800 nm, pulse width: 3 ps, average output: 1 W) or YAG laser (wavelength: 355 nm, pulse width: 35 ns, average output: 10 W). It is also possible to use it.

  The condenser lens 13 is, for example, an objective lens having a magnification of 100 times, a numerical aperture (NA) of 0.8, and a WD (Working Distance) of 3 mm. The condenser lens 13 is supported by a stand arm 14 a extending from the Z-axis slide mechanism 14. A rotating arm 15a extends from the motor 15 that moves with the Z-axis slide mechanism 14, and a quartz glass plate 16 is attached to the end of the rotating arm 15a. Accordingly, the lens control unit 32 drives the Z-axis slide mechanism 14 and also drives the motor 15 to rotate the rotating arm 15a around the Z-axis, so that the quartz glass is formed on the front surface of the opening 13a of the condenser lens 13. The plate 16 can be inserted.

  In addition, the laser beam irradiation apparatus of this embodiment is equipped with a reflection type distance measuring device (not shown). This reflection type distance measuring device is, for example, a distance to the upper surface of the dust-proof quartz substrate 2 of the substrate to be divided 4 shown in FIG. 2, and a distance to the lower surface of the dust-proof quartz substrate 2 (a distance to the upper surface of the adhesive layer 3). ), The distance to the upper surface of the element quartz substrate 1 (the distance to the lower surface of the adhesive layer 3), and the distance to the lower surface of the element quartz substrate 1 can be measured, whereby each substrate or adhesive layer can be measured. Can be detected.

  In the present embodiment, the stage 17 is supported by the Y-axis slide unit 21, but the positional relationship between the X-axis slide unit 20 and the Y-axis slide unit 21 is reversed to place the stage 17 on the X-axis slide unit 20. May be supported. Moreover, it is preferable to support the stage 17 on the Y-axis slide part 21 via the θ table. According to this, it becomes possible to make the division | segmentation object board | substrate 4 into a more perpendicular | vertical state with respect to an optical axis.

  In this laser beam irradiation apparatus 10, as described above, a laser beam is irradiated mainly on the quartz substrates 1 and 2 of the division target substrate 4, a modified region is generated at the focal portion, and this is formed in the thickness direction of a predetermined cross section. After a plurality of layers are formed, an external force is applied to divide. When a plurality of modified regions are formed in the thickness direction of the substrate to be divided 4, for example, as described in Patent Document 2, layers of the modified regions are formed in order from the laser beam irradiation direction. At that time, the quartz glass plate 16 is used as the aberration correction means, and as described in, for example, Japanese Patent Application Laid-Open No. 2007-021556, the condensing region of the laser beam is lengthened, that is, a region having a high energy density is used. It has been practiced to lengthen the modified region in the thickness direction.

  FIG. 4 shows a general aberration correction concept that lengthens the condensing region of the laser beam. In this example, aberration correction is performed such that, for example, the laser beam outside the aperture of the condenser lens 13 is condensed on the front side in the irradiation direction and the inner laser beam is condensed on the front side in the irradiation direction. In this case, the condensing region of the laser beam becomes long, and in the condensing region, the energy density on the near side in the laser beam irradiation direction tends to be large and the energy density on the far side in the irradiation direction tends to be small. FIG. 5 shows the shape of the modified region generated by such aberration correction. As is apparent from the figure, the modified region on the front side in the laser beam irradiation direction with a large energy density has a large cross-sectional area, and the modified region on the front side in the laser beam irradiation direction with a small energy density has a small cross-sectional area. Such a modified region shape facilitates breakage of the substrate when the substrate is divided by applying a bending moment from the upper side to the left and right ends of FIG. 5, for example.

  However, when the laser beam condensing region having the shape corrected in this way is applied to the adhesive layer 3 as shown in FIG. 6, for example, bubbles are generated as shown in FIG. As described above, since the modified region is formed from the laser beam irradiation direction ahead of the division target substrate 4, the laser is irradiated after the modified region is formed ahead of the adhesive layer 3 in the laser beam irradiation direction. The upper end portion of the beam condensing region, that is, the portion on the front side in the irradiation direction and having a large energy density is likely to be applied to the adhesive layer 3. That is, in normal aberration correction that simply lengthens the light collection region, a portion with a large energy density is likely to be applied to the adhesive layer 3 to generate bubbles.

  The generation mechanism of this bubble has not been completely elucidated yet, but when the laser beam is condensed in the adhesive layer 3, the pressure of the portion increases, and when it develops in the adhesive layer 3, It is considered that the substrates 1 and 2 are lifted from the adhesive layer 3 and bubbles enter. Incidentally, the bubbles are generated and propagated between the adhesive layer 3 and the substrates 1 and 2 and reach the TFT pixel region, causing display defects. In order to avoid the generation of such bubbles, it is conceivable that the laser beam is not focused immediately below the adhesive layer 3, that is, in the vicinity of the upper surface of the element quartz substrate 1, and the modified region is not generated. However, if there is no modified region in the vicinity of the upper surface of the element quartz substrate 1, for example, even if an attempt is made to divide the left and right end portions of the division target substrate 4 in FIG. The substrate 4 to be divided cannot be divided at a predetermined dividing surface only by shifting from the quartz substrate 1. Moreover, as a result of earnest examination about the bubble generation mechanism or the bubble suppression method, it has been clarified that even if the laser beam is focused on the adhesive layer 3, if the energy density is small, bubbles are hardly generated. .

  Therefore, in the present embodiment, for example, as shown in FIG. 8, the laser beam outside the opening of the condenser lens 13 is condensed in the irradiation direction and the inner laser beam is condensed in the irradiation direction front side. By performing aberration correction, a condensing region is formed such that the energy density is small on the front side in the laser beam irradiation direction and the energy density is large on the front side in the laser beam irradiation direction. However, in such aberration correction, in practice, the energy density gradually decreases further in the laser beam irradiation direction. FIG. 9 shows the shape of the modified region in which the condensing region is generated by such aberration correction. As is clear from the figure, the modified region on the front side in the direction of laser beam irradiation with a small energy density has a small cross-sectional area, and the modified region on the front side in the direction of laser beam irradiation with a large energy density has a large cross-sectional area, from which energy is increased. As the density gradually decreases, the cross-sectional area gradually decreases.

  Accordingly, for example, as shown in FIG. 10, when the modified region is generated immediately below the adhesive layer 3, that is, in the vicinity of the upper surface of the element quartz substrate 1, the laser beam is corrected by performing the aberration correction as described above. A modified region is generated by forming a condensing region where the energy density is small on the front side of the irradiation direction and the energy density is increased on the front side of the laser beam irradiation direction. Increase area. Since the position of the upper surface of the element quartz substrate 1 is accurately detected by the reflection-type distance measuring device described above, the upper end portion of the condensing region, that is, the rearmost end portion in the irradiation direction is not covered with the adhesive layer 3. This is easy, and even if the rear end portion in the irradiation direction of the light condensing region is applied to the adhesive layer 3, no bubble is generated because the energy density of the portion is small.

  As described above, according to the substrate dividing method of the present embodiment, the pair of substrates 1 and 2 is divided by irradiating the pair of substrates 1 and 2 bonded through the adhesive layer 3 with laser light. This is a substrate dividing method, in which the energy density of laser light is corrected so that the energy density in the adhesive layer 3 or in the vicinity of the adhesive layer 3 is small and the energy density in the laser beam irradiation direction ahead of the adhesive layer 3 is large. Therefore, the pair of substrates 1 and 2 can be divided without generating bubbles in the adhesive layer 3.

Further, a plurality of modified regions are formed in the thickness direction of the pair of substrates 1 and 2 by irradiating the pair of substrates 1 and 2 with laser light, and an external force is applied to the pair of substrates 1 and 2. Since the substrates 1 and 2 are divided, the pair of substrates 1 and 2 can be reliably divided without generating bubbles in the adhesive layer 3.
Further, since the laser light is any one of a femtosecond laser, a picosecond pulse laser, or a YAG laser, the substrate can be divided using a laser suitable for dividing the substrate.
Further, since the display device substrate is divided from the pair of substrates 1 and 2 by the substrate dividing method of the present embodiment, the display device can be manufactured using a substrate having no bubbles in the adhesive layer.

It is a top view of the division | segmentation target board | substrate for TFT elements to which this invention is applied. It is explanatory drawing of the laser scribing method with respect to the division | segmentation target board | substrate of FIG. It is a schematic block diagram of the laser beam irradiation apparatus used for the laser scribing method of FIG. It is explanatory drawing of the general laser beam aberration correction for lengthening a condensing area | region. It is explanatory drawing of the modification | reformation area | region produced | generated by the aberration correction of FIG. It is explanatory drawing of the laser scribing method by the laser beam which has the condensing area | region of FIG. It is explanatory drawing of the bubble which generate | occur | produces in an adhesive bond layer. It is explanatory drawing of the laser beam aberration correction which shows one Embodiment of the laser scribing method of this invention. FIG. 9 is an explanatory diagram of a modified region generated by the aberration correction of FIG. 8. It is explanatory drawing of the laser scribing method by the laser beam which has the condensing area | region of FIG.

Explanation of symbols

1 quartz substrate for element, 2 quartz substrate for dust prevention, 3 adhesive layer, 4 substrate to be divided, 10 laser beam irradiation device.

Claims (4)

A substrate dividing method for dividing a pair of substrates by irradiating a pair of substrates bonded via an adhesive layer with laser light,
Aberration correction of the laser beam is performed so that the energy density in the adhesive layer or in the vicinity of the adhesive layer is small and the energy density ahead of the laser beam irradiation direction is larger than the adhesive layer. Substrate dividing method.   By irradiating the pair of substrates with the laser light, a plurality of modified regions are formed in the thickness direction of the pair of substrates, and the pair of substrates is divided by applying an external force to the pair of substrates. The substrate dividing method according to claim 1.   3. The substrate dividing method according to claim 1, wherein the laser beam is any one of a femtosecond laser, a picosecond pulse laser, and a YAG laser.   4. A method for manufacturing a display device, wherein a substrate for a display device is divided from the pair of substrates by the substrate dividing method according to claim 1.

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