JP5330731B2 - Processing method for bonded glass substrates - Google Patents

Abstract

The invention provides a processing method for glass adhering substrate capable of maintaining excellent end plane quality and intensity with small thickness. The processing method comprises the following steps: (a) forming required deep scribe at a separating position by laser scribe process for each single side face of the two pieces of glass substrates before adhering; (b) adhering the two pieces of glass substrates using the single side faces with scribes as internal sides; and (c) etching external sides of the adhered two pieces of glass substrates, thinning each substrate until to the depth of the scribes, thereby separating each substrate using the scribes as end planes.

Description

The present invention relates to a method for processing a laminated glass substrate using laser scribing.
Here, laser scribing is a process in which a beam spot formed on a substrate is relatively moved by irradiation with a laser beam, the substrate is locally heated below the softening temperature, and then cooled (natural cooling or forced cooling). In this process, a temperature difference in the depth direction is generated in the substrate, and a scribe line is formed using a stress gradient caused by the temperature difference.

  The scribe line refers to a linear crack formed on the substrate surface. In the following description, a scribe line refers to a crack of a finite depth in which the lower end of the crack is stopped in the substrate, and a crack that penetrates the substrate (a crack that completely divides the substrate) is a scribe line. It shall not be included.

  Flat panel displays (hereinafter referred to as FPDs) such as liquid crystal displays and plasma displays are formed by forming a plurality of unit display substrates, each of which becomes an FPD, on a large-area bonded glass substrate, and then each unit display substrate. It is mass-produced to be divided into two.

  For example, in a liquid crystal display, two large area glass substrates (mother substrates) are used, a color filter (CF) is patterned on one substrate, and a TFT (Thin Film Transistor) that drives the liquid crystal on the other substrate. ) And patterning terminal portions for external connection. Then, these two substrates are bonded to each other with the respective pattern formation surfaces inside, thereby forming a large-area bonded substrate. Thereafter, a liquid crystal display is manufactured through a process of dividing a large-area bonded substrate into individual unit display substrates.

The dividing process of cutting out the unit display substrate from the large-area bonded substrate has been performed by various processing methods so far.
For example, with respect to a large-area bonded substrate, a process of cutting a scribe line on the bonded substrate by moving the cutter wheel while pressing, and a step of mechanically breaking by applying a bending moment along the formed scribe line; A dividing method for performing the above in a predetermined order is used (see Patent Document 1).
The dividing method that combines the press-contact process of the cutter wheel and the break process by applying a bending moment adjusts the blade edge shape and press-contact load of the cutter wheel, regardless of whether the substrate to be divided is thin or thick. By doing so, it is possible to reliably perform division.

As another method, (1) a step of forming a scribe line by laser scribing before bonding to a pair of mother glass for FPD and mother glass for TFT substrate, (2) A step of bonding the mother glass for the CF substrate and the mother glass for the TFT substrate on which the scribe line is formed (the surface on which the scribe line is formed may be bonded to the inside or the outside may be bonded to the outside) (3) After that, a dividing method is disclosed in which the mother glass for the CF substrate and the mother glass for the TFT substrate are each sequentially divided (see Patent Document 2).
According to this method, since it is not necessary to form a scribe line in a state where the mother glasses are bonded to each other, it is difficult to be affected by the sealing material to which the two mother glasses are attached, and the formation of the scribe line is stably and accurately performed. It can be carried out.
In addition, according to this method, since the scribe line is formed by laser scribing without generating cullet, even if the scribe line is formed in the process before the bonding process, the bonded surface is caused by cullet generation. There is no problem.
Furthermore, the end surface quality and end surface strength of the scribe line formed by laser scribing are extremely superior to those of other processing methods, and the end surface quality of the divided surface can be improved.

  As another method, a cutting and separating method using an etching process is disclosed (see Patent Document 3). According to this, after performing the process which condenses a laser inside glass and changes the inside of glass, an etching process is performed. In the etching step, the etching rate of the altered region can be increased by allowing the etchant to enter the altered region (microcrack region). Accordingly, it is disclosed that glass is cut and separated without performing long-time etching.

That is, according to Patent Document 3, as shown in FIG. 2A, when the glass plates 21 and 22 bonded with the sealing agent 26 are brought into contact with the etching solution, the glass plates 21 and 22 are etched. When the etching eventually reaches the altered region 23 inside the glass plates 21 and 22, microcracks are formed in the altered region 23, and the etching solution enters the microcracks, so that the etching rate of the altered region 23 is reduced. It becomes faster than the altered region and is etched faster than others. Then, when the altered region 23 is etched, complete cutting and separation are performed as shown in FIG.
According to Patent Document 3, as shown in FIG. 2C, when the scribe line 28 is formed in advance on the single glass plate 27 by wheel cutter or laser irradiation, the scribe line 28 is used in the subsequent etching process. When the lower end of the film is etched (that is, the inside of the scribe line is etched) and eventually reaches the altered region 29, the etching rate increases. Then, as shown in FIG. 2D, it is disclosed that the altered region 29 is etched together with the scribe line 28 to be completely separated.
Japanese Patent Laid-Open No. 6-48755 JP 2004-157145 A JP 2005-219960 A

  In the flat panel display (FPD), the market needs to make the display thinner. In order to reduce the thickness of the FPD, it is required to reduce the thickness of the FPD laminated glass substrate.

  In general, a glass substrate tends to increase the difficulty of dividing a substrate as the thickness of the substrate is reduced. When the manufacturing process includes a dividing step of cutting out the unit display substrate (small area bonded glass substrate) from the large area bonded glass substrate, the dividing step is also included in order to reduce the thickness of the bonded glass substrate. It is necessary to consider.

The dividing method combining the press-contacting process by the cutter wheel described in Patent Document 1 and the breaking process by applying a bending moment is performed by adjusting the blade edge shape and press-contacting load of the cutter wheel according to the thickness of the substrate. Even if the thickness is thin or thick, it is excellent in that division can be performed reliably.
However, due to the pressure contact of the cutter wheel, chips may be generated, and cracks may be generated on the cut end face, and there are differences in end face strength and end face quality compared to the end face formed by laser scribing. Further, it is necessary to apply mechanical force with a break bar or the like during the breaking process after the scribe line is formed, and cullet may occur at this time.

  On the other hand, according to the method described in Patent Document 2, that is, by forming a scribe line by laser scribing, then bonding the substrate glass together, and then dividing the substrate glass, the method is stable and accurate. Not only can a scribe line be formed, but also the end face strength and end face quality are far superior to the end face by the cutter wheel.

  However, this laser scribing process becomes difficult to use as the substrate thickness decreases. That is, in order to form a scribe line on a glass substrate by laser scribing, in principle, it is necessary to generate a temperature difference in the depth direction inside the substrate and create a stress gradient based on the temperature difference. In a glass substrate having a plate thickness of 1 mm or more, it is easy to generate a temperature difference inside the substrate by a beam spot, and a scribe line can be formed because a stress gradient can be easily formed inside the substrate, but the plate thickness is reduced. As a result, it becomes difficult to generate a temperature difference in the depth direction. Specifically, when the plate thickness is 1 mm or less, the laser irradiation conditions capable of forming a scribe line are gradually limited. When the plate thickness is further reduced to about 0.4 mm or less, the laser irradiation causes a depth direction. It is very difficult to generate the temperature difference, and as a result, the conditions under which a scribe line can be formed by laser scribing is extremely narrow and not suitable for practical use.

The reason why it becomes difficult to form a scribe line when the thickness of the substrate is reduced will be described by comparing with the case where the thickness is large. First, the case of the glass substrate GA having a large plate thickness will be described. 3A shows the temperature at the cross section of the substrate when a laser is irradiated (heating), FIG. 3B shows the temperature after jetting and cooling with a refrigerant, and FIG. It is a schematic diagram for demonstrating distribution.
In the thick substrate GA, the heating portion HR is formed inside the substrate by heating due to the passage of the beam spot as shown in FIG. 3A, and the heating portion HR expands locally, thereby compressing stress (FIG. (Shown by the middle dashed arrow). In the drawing, for the sake of convenience of explanation, the deformation generated in the substrate GA is exaggerated.

Subsequently, the cooling part CR is formed in the vicinity of the surface as shown in FIG. 3 (b) due to the cooling by the passage of the cooling spot (area where the refrigerant is injected) after a little delay, and the cooling part CR is locally contracted. As a result, a tensile stress (indicated by a solid arrow in the figure) is generated.
In the case of the thick substrate GA, since the substrate is thick, the heating portion HR does not reach the back surface when the cooling portion CR is formed, and the heating portion HR remains in the substrate.

  And as shown in FIG.3 (c), the cooling site | part CR exists in the board | substrate upper surface vicinity, and the heating site | part HR comes under it. Since this heating part HR has a compressive stress, the internal compressive stress field Hin exists inside the substrate.

  The internal compressive stress field Hin is formed on the substrate GA, and the tensile stress is formed in the vicinity of the upper surface of the substrate GA. As a result, a strain that locally protrudes on the thick plate substrate GA is generated. A force for deflecting the substrate in the same direction (indicated by a one-dot chain line arrow in the figure) is generated on the upper surface of the substrate.

  As a result, scribe lines C (cracks) perpendicular to the thickness direction (depth direction) from the upper surface of the substrate are formed on the upper surface of the substrate GA due to tensile stress and a force that causes the substrate to be convex upward. It is formed.

As described above, since the internal compressive stress field Hin is formed inside the substrate GA, when the tip of the scribe line C (crack) reaches the internal compressive stress field, the substrate GA advances deeper than that. This prevents the scribe line C (crack) from stopping.
Therefore, a scribe line C (crack) having a finite depth is formed in the laser scribe process on the substrate GA. The scribe line C (crack) formed in this way has excellent end face quality and is in an ideal state as a dividing surface.

Next, the thin glass substrate GB will be described. FIG. 4A shows a cross section of the substrate a little after FIG. 4B when laser irradiation (heating), FIG. 4B shows cooling after jetting a coolant after heating. It is a schematic diagram for demonstrating temperature distribution.
In the substrate GB, the heating portion HR is formed inside the substrate as shown in FIG. 4A due to the heating due to the passage of the beam spot, and compressive stress (indicated by a broken line arrow in the figure) is generated, but the plate thickness is thin. For this reason, the heating part HR immediately reaches the back surface. A part of the heated portion HR that has reached the back surface is removed from the bottom surface, and the generated compressive stress is weakened.

  Next, as shown in FIG. 4B, the cooling portion CR is formed in the vicinity of the surface by the cooling heat due to the passage of the cooling spot CS, and the cooling portion CR immediately reaches the center of the substrate GB. At this time, the heating part HR is weakened or almost disappeared.

  When the cooling heat is further transmitted, the cooling portion CR reaches the lower surface of the substrate GB as shown in FIG. As described above, in the thin substrate GB, the heat and cold are quickly transmitted from the upper surface to the lower surface of the thin substrate GB, so that it is difficult to form a temperature gradient in the depth direction of the substrate, and a stress gradient caused by the temperature gradient is generated. It is difficult to generate. Even if a stress gradient in the thickness direction of the substrate can be formed, since the plate thickness is thin, the ranges of hot and cold are narrow, and the magnitudes of the compressive stress and tensile stress are also limited. Therefore, in the case of a thin substrate GB, it is difficult to form a scribe line.

  Furthermore, in the case of the method described in Patent Document 2, even if a scribe line can be formed by laser scribing, it is necessary to perform a breaking process after the scribe line is formed, as in the method of Patent Document 1. If a bending moment is mechanically applied at this time, cullet may still be generated.

  On the other hand, the method described in Patent Document 3, that is, the method of performing the step of etching the glass after condensing the laser inside the glass and modifying the inside of the glass, suppresses the occurrence of cullet. it can. Further, the glass substrate can be thinned by etching.

  However, as shown in FIG. 2, an altered region 23 (microcrack region) damaged by intense laser irradiation is formed inside the glass. Then, since the etchant enters the altered region 23 and is divided by being etched, the altered region 23 may remain as a processed end face. In this case, the end face strength and end face quality are the end faces by laser scribing. It will be inferior to.

  If the etching is continued until the altered region 23 is completely removed, the influence of the altered region 23 can be eliminated. For this purpose, however, the altered region 23 is surely removed even after the glass substrate is divided. It is necessary to erode up to.

Therefore, the present invention, when performing processing to divide individual regions to be unit display substrates from a large area bonded glass substrate in which a plurality of regions to be unit display substrates (small area bonded substrates) are formed, It is an object of the present invention to provide a processing method capable of forming a thin unit display substrate while forming a split surface having excellent end surface quality and end surface strength.
It is another object of the present invention to provide a processing method capable of producing a laminated glass substrate having a thin plate thickness that has never been achieved while maintaining excellent end surface quality and end surface strength.

  The processing method of the present invention made to solve the above-mentioned problems is that the processing is performed in a state where two glass substrates are bonded together with a narrow gap therebetween, and a scribe line formed by laser scribing processing Is made by skillfully utilizing the fact that the scribe surfaces are in close contact with each other (compressive stress is often applied and is in a blind crack state), and it is difficult for liquid or the like to enter inside. .

That is, in the method for processing a bonded glass substrate of the present invention, the following steps are performed.
First, (a) a scribe line in a blind cracked state having a desired depth by laser scribe processing at one of the side surfaces of each of the two glass substrates before bonding, each having a plate thickness of 0.4 mm to 2 mm. The process of forming is performed. When a functional element or the like (for example, a TFT film or a color filter (CF) in a liquid crystal display) is formed on a glass substrate, one side on the side where laser scribing is performed is a surface on which the functional element or the like is formed. deep. This prevents the functional elements and the like from being etched in a later process. Further, the depth of the scribe line formed by the laser scribing process is the value of the plate thickness when the plate is thinned and divided in the subsequent process, and this depth is set to a desired value. Subsequently, (b) a process of bonding the two glass substrates so that the gap width between the glass substrates is 10 μm or less with the one side surfaces on which the scribe lines are formed facing inward. Bonding can be performed using a sealing agent. Subsequently, (c) the outer surface (surface opposite to the bonded surface) of the two bonded glass substrates is etched. Etching may be wet etching or dry etching.

  When etching a laminated glass substrate, there are many fresh etching solutions and etching gases with high etching ability near the outer surface of the laminated glass substrate, but the bonded surface side (surface on which the scribe line is formed) The gap between the surfaces is narrow, and it tends to stay even if an etching solution or etching gas enters. Therefore, etching hardly proceeds as compared with the outer surface. In addition, the scribe lines in the cracks formed by laser scribing are not easily etched because the scribe surfaces are in close contact with each other and it is difficult for an etchant or the like to enter the inside. Therefore, the bonded glass substrate is substantially unilaterally etched from the outer surface, and the thinning of the substrate proceeds. When the etching proceeds and the sheet is thinned to a depth reaching the scribe line, the scribe line becomes an end face and is divided. Thereby, the laminated glass substrate made into the thin plate from which the scribe line formed by the laser scribe process becomes an end surface is obtained. Note that the scribe lines may be formed deeper and etching may be continued until the two glass substrates have a desired thickness even after the laminated glass substrate is thinned and divided.

  According to the present invention, since the end surface of the bonded glass substrate (unit display substrate) divided into small areas is formed by the end surface at the time of laser scribing, a thin plate having a processed surface with excellent end surface quality and end surface strength A laminated glass substrate can be manufactured.

Further, in step (a), since the thickness of each glass substrate before forming the scribing line on 0.4Mm～2mm, by laser scribing as described above to be able to form a scribe line However, by using a glass substrate with a thickness in this numerical range, laser scribing can be performed and the bonded glass substrate can be divided in an appropriate etching time. become able to.

In the step (b), the gap width between the glass substrates is set to 10 μm or less, so that the gap width between the glass substrates is sufficiently narrow, so that the etching solution or the etching gas that has entered the gap is not replaced and stays. Therefore, erosion on the bonded surface side can be suppressed, and erosion from the outer surface can be unilaterally advanced.

Moreover, you may make it the depth of the scribe line to form be 0.01 mm-0.2 mm in the (a) process of the said invention.
According to this, since the thickness of the thinned and divided glass substrate is determined by the depth of the scribe line, setting the depth of the scribe line in this range has made it difficult to divide in the past. A thin laminated glass substrate can be produced.

In the above invention, the two glass substrates before being bonded each have an end material region at the periphery of the substrate, and a scribe line is formed at the boundary with the end material region of each substrate in the step (b). It may be.
According to this, due to the presence of the end material region on the periphery of the substrate, the etching solution or the like that has entered the gap between the glass substrates after bonding is more likely to stay, and the progress of etching from the inside is further suppressed. The etching from the outer surface is surely performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a procedure of a method for processing a bonded glass substrate according to an embodiment of the present invention. Here, a manufacturing process of a liquid crystal display will be described as an example.

  As shown in FIG. 1A, a CF mother glass substrate 1 in which color filters (CF) are patterned in a matrix, and a TFT mother glass substrate 2 in which thin film transistors (TFTs) are patterned in a matrix. Is prepared. In addition to the color filter (CF), the CF mother glass substrate 1 is provided with a counter electrode, a positioning alignment mark, and the like. The TFT mother glass substrate 2 is provided with a pixel in addition to the thin film transistor (TFT). Electrodes, alignment marks for positioning, and the like are provided.

  Subsequently, as shown in FIG. 1 (b), each color filter (CF) and each thin film transistor (TFT) are divided into the mother glass substrate 1 for CF and the mother glass substrate 2 for TFT by laser scribing. For this purpose, scribe lines 3 and 4 are formed. The scribe lines 3 and 4 are formed all around the respective patterns of the color filter (CF) and the thin film transistor (TFT), and the scribe lines 3 and 4 are also formed on the side closer to the substrate end. Is preferred. Further, it is preferable that the edge material region 5 is provided in the peripheral portion of the mother substrates 1 and 2 so that the pattern formation position of the color filter (CF) and the thin film transistor (TFT) is not too close to the substrate edge.

The type of laser used for processing is not particularly limited as long as it can form a scribe line. For example, a CO ₂ laser can be used.
If the thickness of the substrate before processing is too thin, laser scribing cannot be performed. Also, if the substrate is too thick, a scribe line can be formed, but it takes a long time to make a thin plate in the etching process described later, so 0.4 mm to 2 mm, more preferably 0.4 mm to Set to about 1 mm.

  The laser irradiation conditions during processing are made constant, and the depth of each scribe line is made constant. The depth of the scribe line is adjusted not only by adjusting the laser power and beam spot shape according to the thickness of the plate to be thinned, but also by the thickness of the substrate before processing. If the substrate plate thickness before processing is in the range of 0.4 mm to 2 mm, the depth of the scribe line can be set to 0.01 mm to 0.2 mm by selecting the irradiation conditions.

Subsequently, as shown in FIG. 1 (c), a sealing agent 6 is applied to the surface on which either one of the CF mother glass substrate 1 or the TFT mother glass substrate 2 is formed, and the scribe line 3, The surfaces on the side where 4 is formed are bonded together.
The gap width between the mother substrates 1 and 2 to be bonded is set to a value suitable for liquid crystal injection. Specifically, it is about 1 μm to 10 μm, preferably 3 μm to 7 μm. If the gap width is 10 μm or less, there is no particular problem. However, as the gap width is narrowed, the amount of the etchant entering the gap decreases in the subsequent process, and the etchant entering the gap is less likely to be replaced. Etching of the surface on which the scribe line is formed can be further suppressed.

Subsequently, as shown in FIG. 1 (d), the bonded substrates 1 and 2 are immersed in an etching solution 7. As the etching solution 7, a commercially available product for glass etching such as a fluoride solution (hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, etc.) can be used.
Both the substrates 1 and 2 are etched on the outer surfaces 1a and 2a (the surface opposite to the bonding surface), and the inner surfaces 1b and 2b are inhibited from being etched. Further, the scribe lines 3 and 4 formed by the laser scribe process remain hardly eroded because the scribe surface is in close contact and the etching solution is difficult to enter inside.

  Then, the etching proceeds and the outer surface side is removed to the depth of the scribe lines 3 and 4, so that the unit display substrate 8 is divided as shown in FIG. By taking out from the etching solution 7 at the same time as being divided, as shown in FIG. 1 (f), the end faces of the scribe lines 3 and 4 remain almost as they are, and the unit display substrate 8 having excellent end face quality and end face strength is formed. . Moreover, the thickness of the unit display substrate 8 can be reduced to the depth of the scribe lines 3 and 4 (for example, 0.01 mm to 0.2 mm).

  Although the terminal region is not provided in the above-described embodiment, the terminal region can be formed by changing the position of the scribe line between the two substrates as in the conventional example shown in FIG.

  The processing method of the present invention can be used for thinning a laminated glass substrate.

The figure which shows the processing method of the bonded glass substrate which is one Embodiment of this invention. The figure which shows the processing method by the conventional etching. The figure which shows the laser scribing process of the board | substrate of a thick board. The figure which shows the laser scribing process of a thin board | substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mother glass substrate for CF 2 Mother glass substrate for TFT 3 Scribe line 4 Scribe line 5 End material region 6 Sealing agent 7 Etching solution 8 Unit display substrate CF Color filter TFT Thin film transistor

Claims (3)

(A) A scribe line in a blind crack state with a desired depth is formed on one side of each of the two glass substrates before bonding with a plate thickness of 0.4 mm to 2 mm by laser scribe processing at a planned division position. And a process of
(B) bonding the two glass substrates so that the gap width between the glass substrates is 10 μm or less with the one side surfaces on which the scribe lines are formed facing inside;
(C) A process comprising a step of etching the outer side surfaces of the two glass substrates bonded together to thin each substrate to the depth of the scribe line, thereby dividing each substrate with the scribe line as an end surface. A method for processing a laminated glass substrate.   The method for processing a laminated glass substrate according to claim 1, wherein in the step (a), a depth of a scribe line to be formed is 0.01 mm to 0.2 mm. Two glass substrates prior to bonding has a mill ends regions on the substrate periphery, respectively, according to claim 1 or claim scribe line is formed in the step (b) at the boundary between the end material region of the substrate The processing method of the bonded glass substrate of 2 .