JP6521037B2 - Method of fusing glass substrate by laser light - Google Patents

Description

  The present invention relates to a glass substrate fusion bonding method, and more particularly, to a glass substrate fusion bonding method in which glass substrates are fused by irradiating a laser beam on the stacked glass substrates and a laser processing apparatus using the same.

  For example, in an apparatus for IT equipment, a device in which two glass substrates are stacked is used. Patent Document 1 discloses a method and an apparatus for bonding such two stacked glass substrates.

  In the method of bonding glass substrates disclosed in Patent Document 1, first, a frit wall is formed by presintering a frit on the surface of a glass substrate as a back plate. Then, a glass substrate as a cover plate is superimposed on the back plate on which the frit wall is formed. Thereafter, laser light is irradiated to the frit wall. As a result, the frit wall is heated by the laser light and becomes difficult, the frit wall is bonded to both the back plate and the cover plate, and the two plates are bonded.

  Patent Document 2 discloses a method of bonding two glass substrates using short pulse laser light. Here, a high energy short pulse laser beam is condensed in the vicinity of a gap between two glass substrates, and multiphoton absorption is caused to bond the two glass substrates.

JP 2012-533853 gazette International Publication 2011/115242

  For example, in a liquid crystal display device, a predetermined gap is secured between two glass substrates, and in this state, the space between the two glass substrates is sealed. In order to realize such a configuration, first, a spacer is disposed between the two glass substrates, and then the two glass substrates are fused by the method as shown in Patent Document 1 or 2. Sealing is conceivable.

  However, the above method requires a spacer material between the two glass substrates. Further, in the method of Patent Document 1, it is necessary to pre-sinter the frit on the surface of the back plate once. In order to pre-sinter the frit, the cover plate or frit needs to be placed in an oven or furnace and heated, which complicates the process.

  Furthermore, although short pulse laser light is used in the method of Patent Document 2, short pulse laser light is expensive. Further, in the method of Patent Document 2, in order to generate the multiphoton absorption phenomenon, it is necessary to make the spot diameter of the laser light smaller. Therefore, a complicated device is necessary for the focusing optical system and the focal position control. It becomes.

  An object of the present invention is to make it possible to bond both glass substrates in a state in which a predetermined gap is secured between two glass substrates using a simple process and an optical system and without using a spacer material. It is in.

  The glass substrate fusing method by laser light according to the first aspect of the present invention is a method of fusing the glass substrates by irradiating the stacked glass substrates with the laser beam and comprising the following steps.

  First step: The first glass substrate is placed on a work table.

  Second step: The first glass substrate is irradiated with a laser beam having a wavelength of 2.7 μm or more and 6.0 μm or less to form a convex portion with a predetermined height on the surface of the first glass substrate.

  Third step: The second glass substrate is superimposed on the first glass substrate with the convex portion of the first glass substrate as a spacer.

  Fourth step: A region other than the convex portion is irradiated with laser light to fuse the first glass substrate and the second glass substrate.

  In this method, first, the first glass substrate placed on the work table is irradiated with laser light having a wavelength of 2.7 μm or more and 6.0 μm or less, whereby the inside of the first glass substrate is heated and the laser light The irradiated portion melts and expands to form a convex portion on the surface of the first glass substrate. Next, a second glass substrate is superimposed on the first glass substrate on which the convex portion is formed, with the convex portion as a spacer. Then, the same laser beam as the previous laser beam is irradiated to the area other than the convex portion. As a result, the portions of the first and second glass substrates irradiated with the laser light are melted, and the two glass substrates are joined through a gap substantially corresponding to the height of the convex portion.

  Here, without using a spacer material or a frit, and using the same laser beam in the step of forming the convex portion and the step of fusing the two glass substrates, a gap is opened between the two glass substrates to make both glasses Substrates can be bonded. This simplifies the process. In addition, since the two glass substrates are fused without using the multiphoton absorption phenomenon, it is not necessary to control the condensing position with high accuracy, and the apparatus configuration is simplified.

  The glass substrate fusing method by laser light according to the second aspect of the present invention is the method of the first aspect, wherein in the second step and the fourth step, a laser beam having a wavelength of 2.7 μm to 5.0 μm is treated as a glass substrate Irradiate.

  Here, since a mid-infrared laser beam having a relatively high transmittance to glass is used, even if the thickness of one glass substrate to be irradiated with the laser beam is relatively thick, the laser beam reaches the other glass substrate. It can reach and stably fuse the glass substrate.

  The glass substrate fusing method by laser light according to the third aspect of the present invention is the method of the first or second aspect, wherein in the second step and the fourth step, the laser light is irradiated along the lines to be fused. Scan.

  Here, two glass substrates can be fused along a continuous line to be fused. Therefore, the space formed between the two glass substrates can be sealed.

  The glass substrate fusing method by laser light according to the fourth aspect of the present invention is any one of the first to third aspects, wherein continuous oscillation laser light is applied to the glass substrate in the second step and the fourth step. Irradiate.

  Here, since a continuous wave laser beam is used, a uniform continuous melting portion can be formed along a line to be fused, and two glass substrates can be fused easily and firmly.

  The glass substrate fusing method by laser light according to a fifth aspect of the present invention is the method of any of the first to third aspects, wherein in the second step and the fourth, the quasi continuous oscillation laser having a repetition frequency of 1 MHz or more Light is applied to the glass substrate.

  Here, since laser light of pseudo continuous oscillation is used, it is possible to easily form a substantially uniform continuous molten portion as in the case of laser light of continuous oscillation.

  The glass substrate fusing method by laser light according to the sixth aspect of the present invention is the method according to any one of the first to third aspects, wherein in the second step and the fourth step, pulsed laser light having a repetition frequency of 10 kHz or more is used. Irradiate the glass substrate.

  Here, since a pulse laser beam having a repetition frequency of 10 kHz or more is used, it is possible to form a melt portion in which the melt portions formed for each pulse of the pulse laser are overlapped and made continuous.

  The glass substrate fusion bonding method by laser light according to a seventh aspect of the present invention is the method according to any one of the first to sixth aspects, wherein in the third step, the second glass substrate is pressed against the first glass substrate Without overlapping.

  Here, there is no need to press the two glass substrates against each other, and the apparatus configuration is simplified.

The glass substrate fusing method by laser light according to the eighth aspect of the present invention is any one of the first to seventh aspects, wherein Er: Y ₂ O ₃ , Er: ZBLAN in the second and fourth steps. , Er: YSGG, Er: GGG, Er: YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, Cr: ZnS, Fe: ZnSe, Fe: ZnS, Mid-Infrared of Semiconductor Laser The glass substrate is irradiated with any laser light selected from the laser light group.

  The glass substrate fusing method by laser light according to a ninth aspect of the present invention is any one of the first to eighth side methods, wherein the glass substrate has an internal absorptivity of 5% to 95% of laser light.

  The apparatus for processing a glass substrate by laser light according to the tenth aspect of the present invention is an apparatus for irradiating the stacked glass substrates with laser light to fuse the glass substrates together. This apparatus includes a work table on which a glass substrate is mounted, a laser oscillator, and a laser light irradiation mechanism. The laser oscillator oscillates a laser beam having a wavelength of 2.7 μm to 6.0 μm. The laser light irradiation mechanism irradiates the surface of the first glass substrate mounted on the work table with the laser light from the laser oscillator to form a convex portion of a predetermined height on the surface of the first glass substrate. Further, in the laser light irradiation mechanism, the region other than the convex portion is irradiated with the laser light in a state in which the second glass substrate is superimposed on the first glass substrate with the convex portion of the first glass substrate as a spacer. The substrate and the second glass substrate are fused.

  A laser processing apparatus according to an eleventh aspect of the present invention is the apparatus according to the tenth aspect, wherein the laser oscillator oscillates laser light of mid-infrared light having a wavelength of 2.7 to 5.0 μm.

  A laser processing apparatus according to a twelfth aspect of the present invention is the apparatus according to the tenth or eleventh aspect, wherein the laser beam from the laser beam irradiation mechanism is moved relative to the glass substrate to fuse the laser beam. It further comprises a scanning mechanism that scans along the line.

  A laser processing apparatus according to a thirteenth aspect of the present invention is the apparatus according to any of the tenth to twelfth aspects, wherein the laser oscillator continuously oscillates the laser beam.

  A laser processing apparatus according to a fourteenth aspect of the present invention is the apparatus according to any of the tenth to twelfth aspects, wherein the laser oscillator performs pseudo continuous oscillation of laser light having a repetition frequency of 1 MHz or more.

  In a laser processing apparatus according to a fifteenth aspect of the present invention, in the apparatus according to any of the tenth to twelfth aspects, the laser oscillator oscillates pulsed laser light having a repetition frequency of 10 kHz or more.

A laser processing apparatus according to a sixteenth aspect of the present invention is the apparatus according to any of the tenth to fifteenth aspects, wherein the laser oscillator is Er: Y ₂ O ₃ , Er: ZBLAN, Er: YSGG, Er: GGG, Er : YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, Cr: ZnS, Fe: ZnSe, Fe: ZnS, any one selected from the group of mid-infrared laser beams of semiconductor lasers Laser light is emitted to the glass substrate.

  In the present invention as described above, both glass substrates can be bonded by securing a predetermined gap between the two glass substrates using a simple process and an optical system.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the laser processing apparatus by one Embodiment of this invention. The figure which shows the relationship of the wavelength of the laser beam and the transmittance | permeability with respect to an alkali free glass. The figure which shows the relationship between the wavelength of the laser beam with respect to soda glass, and the transmittance | permeability. The microscope picture of the convex part formed in the glass substrate, and its conceptual diagram. The table | surface which shows the focus position of a laser beam, the relationship between scanning speed, and a convex part dimension. The schematic diagram at the time of laminating | stacking and fusing two glass substrates.

[Laser processing equipment]
A laser processing apparatus according to an embodiment of the present invention is shown in FIG. The laser processing apparatus includes a work table 1 on which a glass substrate G is mounted, a laser oscillator 2, an optical system 3, and a table moving mechanism 4 as a scanning mechanism.

The laser oscillator 2 oscillates laser light of mid-infrared light having a wavelength of 2.7 μm to 6.0 μm. Here, as the laser oscillator 2, Er: Y ₂ O ₃ , Er: ZBLAN, Er: YSGG, Er: GGG, Er: YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, A laser beam selected from Cr: ZnS, Fe: ZnSe, Fe: ZnS, and a mid-infrared laser beam group of a semiconductor laser and having a wavelength of 2.7 to 6.0 μm is emitted as described above As long as it is Further, here, laser light of continuous oscillation is emitted.

  The optical system 3 includes a plurality of reflection mirrors 6 a, 6 b and 6 c and a condenser lens 7. The condensing lens 7 is set to condense the laser light near the surface of the glass substrate G as an example.

  The table moving mechanism 4 is a mechanism for moving the work table 1 in the X and Y directions orthogonal to each other. The table moving mechanism 4 can scan laser light along a line to be fused.

[Method of processing glass substrate]
In the case where the second glass substrate G2 is bonded to the surface of the first glass substrate G1 at a predetermined interval using the above-described laser processing apparatus, the following process is performed.

[First and second steps]
First, the first glass substrate G1 is set at a predetermined position on the work table 1. Next, laser light of mid-infrared light as described above is condensed on the first glass substrate G1 on the work table 1 in the vicinity of the surface of the first glass substrate G1 and is further fused. Scan along the line. The focal position point of the laser light is not limited to the surface of the first glass substrate G1.

  A convex part is formed in the irradiation part of the laser beam in the 1st glass substrate G1 so that the surface may swell by continuous irradiation and scanning of the above laser beams. The height and width of the convex portion can be adjusted by the focal position and the scanning speed of the laser light.

  In particular, by using mid-infrared laser light having a wavelength of about 3 μm, the laser light is absorbed while being transmitted to the inside of the glass substrate. For this reason, the distribution of heat distribution is reduced from the surface to the inside of the glass substrate, and thermal damage to the glass substrate can be suppressed, and projections with a predetermined height can be easily formed in the laser beam irradiated portion.

<Transmittance and wavelength>
FIG. 2 shows the relationship between the wavelength of laser light and the transmittance of a glass substrate of alkali-free glass (for example, OA10 (product name: manufactured by Nippon Electric Glass Co., Ltd.)) having a thickness of 0.2 mm. Further, FIG. 3 shows the relationship between the wavelength of laser light and the transmittance of a soda glass glass substrate having a thickness of 0.5 mm.

  As apparent from FIG. 2, for a non-alkali glass having a thickness of 0.2 mm, for example, the transmittance is “0” for a CO 2 laser having a wavelength of 10.6 μm, so the laser light is absorbed on the surface of the substrate It will be done. In the case of a YAG laser having a wavelength of 1 μm or a green laser having a wavelength of 532 nm, the transmittance is 90% or more, and about 10% of the non-transmissive laser light is also reflected on the surface and not absorbed inside the substrate. And if it is a laser beam with a wavelength of 2.8 micrometers, it will be absorbed substantially uniformly inside a substrate, can fuse the inside of a substrate, and can form a convex part on the surface of a glass substrate.

  Further, in the soda glass having a thickness of 0.5 mm in FIG. 3, the laser light having a wavelength of 2.8 μm is absorbed while being transmitted to the inside of the substrate, and thus the substrate is the same as the alkali-free glass in FIG. The inside can be melted to form a projection of a predetermined height on the surface.

  The difference between the transmittance values in the graphs shown in FIG. 2 and FIG. 3 is due to the difference in the thickness of the sample, and if the thickness is the same, transmission between alkali-free glass and soda glass is possible. There seems to be no difference in rates.

  From the above, it is possible to use a laser beam having a wavelength of 2.7 μm or more and 6.0 μm or less for many glass substrates (in particular, a glass substrate having an internal absorptivity of 5% or more and 95% or less). It is surmised that a projection with a predetermined height can be easily formed on the portion irradiated with the laser light. In addition, even when the thickness of the substrate to be irradiated with the laser light is relatively thick, the convex portion can be formed on the glass substrate by using the laser light having a wavelength of 2.7 μm or more and 5.0 μm or less.

<Experimental Example: Formation of Convex Portion>
FIGS. 4A and 4B show how convex portions are formed on the surface of the glass substrate when the glass substrate is irradiated with the above-described mid-infrared laser light. FIG. 4 (a) is a photomicrograph of a cross section of a portion irradiated with a laser beam, and FIG. 4 (b) is a conceptual view thereof. The glass substrate and the laser irradiation conditions in this experiment are as follows.

Substrate: Alkali-free glass (OA10 = product name: manufactured by Nippon Electric Glass Co., Ltd.), size = 100 mm × 125 mm × t 0.2 mm
Laser light: Er: ZBLAN fiber laser, wavelength 2.7 μm, output 7 W, continuous oscillation In this experiment, the laser light was scanned at different speeds in the direction perpendicular to the paper surface of FIG. As a result, the convex portions were continuously formed along the scanning line, and the dimensions were 10 μm wide × 1 μm high to 40 μm wide × 8 μm high. Here, as shown in the conceptual view of FIG. 4B, it is considered that three layers of an expanded portion, an altered portion, and a heat affected portion are formed on the glass substrate.

  FIG. 5 collectively shows how convex portions are formed when the focal position is changed to +0.4 mm to −0.4 mm and the scanning speed is changed to 15 mm / s to 35 mm / s. ing. In the figure, "+0.4 mm" to "-0.4 mm" indicate the focal position of the laser light, "0 mm" indicates the surface of the glass substrate, and "-" indicates the position inside the substrate. The numerical unit in the table is "μm". Also, in the figure, “F” is the fluctuation width of height, that is, the difference between the maximum value and the minimum value of the height in the measurement line (approximately the same as the center line of the processing line) set at the center of the expansion width. .

  The following can be understood from FIG.

  (A) The case where the focal position of the laser light is set to the substrate surface (0 mm) is the easiest to expand. However, if the focal position is in the range of +0.4 mm to -0.4 mm, a convex portion with a desired height can be formed on the surface of the glass substrate by appropriately controlling the scanning speed of the laser light. .

  (B) When the scanning speed is increased, the processed marks can be observed but the convex portions due to expansion are not formed. That is, in order to form the convex portion, it is necessary to give a certain amount of heat to the substrate.

  (C) The expansion size is larger when the focal position of the laser light is set to “−” (inside of the substrate). In FIG. 5, the actual focal position is not shown because the refractive index of the glass is not taken into consideration.

  (D) When the focal position of the laser light moves away from the surface of the glass substrate, the height fluctuation width increases.

  From the above, if the focal position is set in the vicinity of the surface of the glass substrate by using the laser light of the wavelength as described above, the convex portion of the desired height can be stably stabilized by controlling the scanning speed. It can be seen that it can be formed into

[Third to fourth steps]
Next, as shown in the schematic view of FIG. 6, the second glass substrate G2 is superimposed on the first glass substrate G1 on which the convex portion B is formed by causing the convex portion B to function as a spacer. Then, the region R other than the convex portion B is irradiated with the laser light under the same laser light irradiation conditions as the conditions under which the convex portion B is formed. As a result, the laser beam irradiation region R of the first glass substrate G1 expands in the same manner as when the convex portion B is formed, and the tip of the expanded portion and the back surface of the second glass substrate G2 (first glass substrate G1 And the opposite surface) are fused and joined.

[Use]
The method as described above is effective in the case of fusing and sealing two laminated glass substrates with a predetermined gap therebetween. That is, by continuing and closing the fusion line, the space inside the region R of FIG. 6 is sealed.

[Feature]
(1) It is possible to open a gap between two glass substrates and join them without using a separate spacer material.

  (2) Two glass substrates can be fused without using a frit.

  (3) The same laser beam can be used in the step of forming the convex portion and the step of fusing the two glass substrates, and the process for fusing becomes simple.

  (4) There is no need to control the condensing position with high accuracy, and the apparatus configuration is simplified.

  (5) By irradiating the glass substrate with a laser beam of mid-infrared light, a convex portion with a desired height can be precisely measured without controlling the output of the laser light or heating and pressing in a later step. It can be formed.

  (6) The height of the convex portion can be controlled by adjusting the focal position and the scanning speed of the laser light.

  (7) The laser beam is absorbed while penetrating to the inside of the glass substrate, and hence is uniformly heated from the surface to the inside of the glass substrate. Therefore, a convex part can be formed in the surface of a glass substrate, controlling heat damage of a glass substrate.

[Other embodiments]
The present invention is not limited to the embodiments as described above, and various changes or modifications are possible without departing from the scope of the present invention.

  Although the continuous wave laser light is used in the above embodiment, a pseudo continuous wave laser light having a repetition frequency of 1 MHz or more or a pulse laser light having a repetition frequency of 10 kHz or more may be irradiated.

1 work table 2 laser oscillator 3 optical system 4 table moving mechanism B convex portion G1, G2 glass substrate

Claims (4)

It is a fusion method of a glass substrate which irradiates a laser beam to a piled glass substrate and fuses glass substrates,
A first step of placing a first glass substrate on a worktable;
A second step of forming a convex portion of a predetermined height on the surface of the first glass substrate by irradiating the first glass substrate with a laser beam having a wavelength of 2.7 μm or more and 6.0 μm or less;
A third step of stacking a second glass substrate on the first glass substrate using the convex portion of the first glass substrate as a spacer;
A region having a gap between the first glass substrate and the second glass substrate other than the convex portion is irradiated with a laser beam having the wavelength to expand a region of the first glass substrate irradiated with the laser beam. A fourth step of fusing the distal end portion of the expanded portion of the first glass substrate and the surface of the second glass substrate facing the first glass substrate ;
The glass substrate fusion | melting method by the laser beam provided with.   The glass substrate fusing method according to claim 1, wherein a laser beam having a wavelength of 2.7 μm or more and 5.0 μm or less is irradiated to the glass substrate in the second step and the fourth step.   The glass substrate fusing method according to claim 1 or 2, wherein in the second step and the fourth step, scanning is performed along a line to be fused while irradiating the laser beam.   The glass substrate processing method by the laser beam according to any one of claims 1 to 3, wherein the first and second glass substrates have an internal absorptivity of 5% to 95% of laser light.