JP2011006313A - Scribing method and scribing apparatus for thin sheet glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scribing method which can ensure a scribe processing even if a thin sheet glass substrate has a sheet thickness of a substrate in a range of 0.1-0.4 mm.SOLUTION: The scribing method of a thin sheet glass substrate comprises: computing the relation among a sheet thickness of a substrate when forming a scribe line, a processing condition of a scan rate, and a deformation state of a substrate by stress immediately after performing laser heating and cooling, based on a thermoelastic analysis by a finite element method; setting a sheet thickness and a processing of a scan rate at which a substrate is deformed to form a concave on a laser irradiation face side; mounting the substrate after positioning a scribe-scheduled line so that the straight distance between the scribe-scheduled line and each of holes situated on both right and left sides of the scribe-scheduled line, along the scribe-scheduled line, and adjacent thereto falls within 1 mm; and performing laser irradiation and cooling in a state that the substrate is made to be adsorbed through the holes.

Description

The present invention relates to a laser scribing method for a glass substrate, and more particularly to a laser scribing method for a very thin glass substrate having a plate thickness of 0.1 mm to 0.4 mm.
The present invention also relates to a laser scribing apparatus suitable for processing a very thin glass substrate having a plate thickness of 0.1 mm to 0.4 mm.

In the present invention, “scribe” refers to processing in which a crack not penetrating the substrate is advanced in the surface direction along a scribe line set on the substrate. A crack that progresses in the surface direction by scribing forms a scribe line.
“Scribe” refers to a process that forms a crack where the tip of the crack in the depth direction (the deepest part of the crack) stays in the substrate, causing a full cut (a state where the substrate is completely divided). The processing (called full cut processing) in which a crack penetrating from the front surface to the back surface of the substrate is not included.
Therefore, in order to completely divide the substrate along the scribe line formed by scribing, a break process for extending the crack in the depth direction is performed later.

  For convenience of explanation, “progress of crack” means that the crack grows in the surface direction of the substrate. Further, the penetration of cracks in the thickness direction (depth direction) of the substrate is referred to as “crack progress”.

When the glass substrate is irradiated with a laser beam while being scanned, a compressive stress is generated in a region heated by passing the beam spot of the laser beam. And a cooling stress is produced in the cooled area | region (cooling spot) by spraying a refrigerant | coolant to the position immediately after a beam spot passes, and cooling. Thus, a stress gradient is formed by forming a region where compressive stress is generated on the substrate and a region where tensile stress is generated close to each other.
In recent years, by using this stress gradient to form a crack in a glass substrate, a processing technique for performing scribing on the surface of the substrate (see, for example, Patent Document 1) or performing full-cut processing of a glass substrate has been used. (For example, refer to Patent Documents 2 and 3).

  By the way, when placing a substrate on a table and forming a stress gradient on the substrate by heating by laser irradiation and cooling immediately after heating, the scribe line was formed as described above. There are a scribing process that requires a break process later and a full-cut process in which the substrate is divided without performing the break process.

  Of these, full-cut processing is preferable in that the process can be simplified because the substrate can be divided without performing break processing, but when compared with the processing quality such as straightness of the processing end face that is finally obtained, compared to scribe processing It is inferior.

  On the other hand, in the scribing process, the quality of the formed end face is very excellent. Moreover, since it is possible to perform a cross-scribing process that can be completely divided after forming a scribe line vertically and horizontally on the substrate, in a process of cutting a rectangular small substrate from a large area substrate in a liquid crystal panel manufacturing process, etc. Scribing is often used.

  Regarding the table on which the substrate is placed, when the placed substrate is irradiated with a laser beam and cleaved into a chip size of several mm square, a vacuum is provided by providing a number of vacuum suction holes on the table surface so that the chip is not blown away. It is disclosed to perform adsorption. In that case, it is difficult to provide a large number of vacuum suction holes on the table at intervals of 1 mm from the viewpoint of mechanical dimensional accuracy, and it is disclosed that vacuum suction is performed using a porous plate that can withstand a temperature of 500 degrees Celsius. (See Patent Document 3).

In general, in a table having a vacuum suction mechanism, a table surface made of a porous material is used as a shape of a table surface on which a substrate is placed, and a metal table surface mechanically perforated is used. There is.
The former porous table is excellent in that the substrate can be uniformly adsorbed. However, since a material such as alumina is used as the porous material, when the laser beam is irradiated directly on the table surface during laser processing, the irradiated portion is altered or discolored by heat. There is a case.

  On the other hand, a metal table that is mechanically perforated is excellent in that it does not deteriorate even when directly irradiated with a laser. However, as the distance between adjacent vacuum suction holes decreases, the number of holes to be processed increases. Especially when the distance between the holes is 2 mm or less, the cost of hole processing becomes enormous, and a large number of holes are processed with constant accuracy. It becomes difficult to do.

For example, the to adsorb the substrate is absolutely essential in the following small hole spacing 1 cm, a case of splitting the workpiece into the same order of magnitude as the hole spacing (i.e. 1 cm). In such a case, a porous table can be adequately used instead of the hole processing table, so there is no need to use a hole processing table having a 1 cm interval or less, which is difficult to manufacture, and the porous table is inexpensive. Is used. For processed products larger than 1 cm, a porous table is used, or a metal table is used that has been drilled with a hole spacing of several cm so as not to incur processing costs.
That is, a suction table surface processed with a vacuum suction hole interval of 1 cm or less is practically rarely used because of processing difficulty and cost, even if it can be manufactured and processed technically. . In particular, when the table has a hole interval of 2 mm or less, only a porous table is actually used.

International Publication Number WO 03/008352 Japanese Patent Laid-Open No. 2004-155159 JP 2001-170786 A

  In the manufacturing field of liquid crystal panels used for mobile phones, liquid crystal televisions, etc., the size of a unit substrate (processed product) to be cut is larger than 1 cm. For example, in the case of a mobile phone, the cleaving is about several cm square. For LCD TVs, a much larger substrate is used than for mobile phones. When a suction table of 1 cm square or more is used, a metal table with holes formed can be used instead of a porous table that may be altered by laser irradiation.

As for the thickness of the substrate to be processed, a glass substrate having a thickness of 1 mm or more has been used so far, but it is required to use a substrate as thin as possible in order to reduce the weight of the product. Specifically, the thickness of the substrate to be used is required to be 0.7 mm or less, more preferably in the range of 0.1 mm to 0.4 mm.
Therefore, in the glass substrate dividing processing technique, it is required to process such a thin plate substrate having a thickness of 0.4 mm or less by scribe processing instead of full cut processing.

  Whether scribe processing or full cut processing is achieved by laser irradiation depends on processing condition parameters such as heating conditions (irradiation time, irradiation power, scanning speed, etc.) and cooling conditions (refrigerant temperature, spray amount, spray position, etc.) In addition, it depends on the thickness of the glass substrate.

  Generally, when the glass substrate is thick, scribe processing can be established easily and reliably, but it is uncertain whether scribe processing will be established as the plate thickness becomes thinner than 0.7 mm. become. Further, when the thickness is 0.4 mm or less, scribing becomes difficult, and when forcibly processed, there is a tendency to form a through-crack and a full-cut processing. Hereinafter, the relationship between the thickness of the substrate and the processing mode will be described with reference to schematic diagrams.

<Thick board>
First, the case of a glass substrate having a large plate thickness will be described. The case where the plate thickness is thick here means that the substrate is sufficiently thick when the laser beam is irradiated on the upper surface of the substrate and the heat (heat) generated near the upper surface is transferred into the substrate. When the crack is formed on the surface, the heat transfer is stopped inside the substrate and the heat is not transferred to the lower surface of the substrate. Specifically, in the case of a glass substrate, heat transfer tends to stay inside the substrate when the thickness is 1 mm or more.

FIG. 9 is a schematic diagram for explaining a stress distribution generated in a substrate when a crack is developed and advanced by performing laser irradiation and cooling on a thick substrate having a plate thickness of 1 mm or more. FIG. 9A is a perspective view, and FIG. 9B is a plan view thereof.
10 (a), 10 (b), and 10 (c) show the temperature distribution and stress distribution in the AA ′, BB ′, and CC ′ sections of FIG. 9, respectively. It is a schematic diagram for demonstrating. From another viewpoint, FIGS. 10 (a), 10 (b), and 10 (c) show the time of temperature distribution and stress distribution at the same point due to the passage of the beam spot BS and the cooling spot CS. This represents a typical change.

  In FIG. 9, an elliptical beam spot BS is formed by a laser beam irradiated from a laser beam irradiation mechanism (not shown). An elliptical cooling spot CS is formed behind the beam spot BS by the refrigerant blown from a cooling mechanism (not shown). The beam spot BS and the cooling spot CS are scribed on the thick substrate GA from one end side where the initial crack TR is formed in advance toward the other end side while maintaining a positional relationship with a slight distance. Scan along the planned line SL.

  At this time, a compressive stress (indicated by a broken-line arrow in the figure) is generated in the vicinity of the upper surface of the thick substrate GA in the vicinity of the region heated by the passage of the beam spot BS due to the expansion due to the heating. Next, a tensile stress (indicated by a solid arrow in the figure) due to the temperature distribution formed in the thick plate substrate GA is generated in the vicinity of the region cooled by the passage of the cooling spot CS.

Next, the stress and strain generated in the thick substrate GA will be described with reference to FIG.
In the thick substrate GA, the heating part HR is formed inside the substrate as shown in FIG. 10 (a) by heating due to the passage of the beam spot BS of the laser beam, and the heating part HR expands locally, thereby compressing. Stress (indicated by broken arrows in the figure) is generated.

Subsequently, the cooling part CR is formed in the vicinity of the surface as shown in FIG. 10 (b) due to the cooling by the passage of the cooling spot CS after a little delay, and the cooling part CR locally contracts, whereby the tensile stress ( (Indicated by solid arrows in the figure) occurs.
In the case of the thick substrate GA, the heating portion HR is gradually transmitted to the inside of the substrate, but since the substrate is thick, it does not reach the back surface when the crack is formed, and the heating portion HR stays inside the substrate. .

  Then, as shown in FIG. 10C, when the cooling heat is gradually transmitted from the surface layer of the thick substrate GA by forming the cooling portion CR, the cooling portion CR exists in the vicinity of the upper surface of the substrate, and the heating portion is located below the cooling portion CR. HR comes to exist. Since this heating part HR is a part where compressive stress is generated, it can be rephrased as an internal compressive stress field Hin existing inside the substrate.

  The internal compressive stress field Hin is formed on the thick substrate GA, and the tensile stress is formed near the upper surface of the substrate. As a result, a strain that locally protrudes upward is generated on the thick substrate GA. A force (indicated by a one-dot chain line arrow in the figure) that bends the substrate in the same direction is generated on the upper surface of the substrate. In FIG. 10C, in order to show the direction of bending, the deformation due to the distortion generated in the thick substrate GA is exaggerated for convenience.

  As a result, a vertical crack C is formed on the upper surface of the thick substrate GA in the thickness direction (depth direction) from the upper surface of the substrate by a tensile stress and a force that causes the substrate to be convex upward. The This crack C forms a scribe line.

  In this case, since the internal compressive stress field Hin is formed in the thick plate substrate GA as described above, when the crack C reaches the internal compressive stress field, the progress is hindered, and the thick plate substrate The progress of crack C in GA stops in the vicinity of the internal compressive stress field.

  Therefore, in the thick substrate GA, it becomes difficult for the crack C to progress until it reaches the back surface, and the scribing process is performed in which a crack that does not penetrate near the upper surface of the substrate is formed. In other words, the scribe processing mode is a processing mode in which a crack is developed by a stress gradient caused by a temperature gradient between hot and cold formed in the thickness direction of the substrate.

<Thin board>
Next, the case of a thin glass substrate will be described. The case where the plate thickness is thin here means that the plate thickness of the substrate is sufficiently thin when the laser beam is irradiated on the upper surface of the substrate and the heat (thermal heat) generated near the upper surface of the substrate is transmitted into the substrate. When the substrate surface is cooled and cracks are formed, the heat reaches the lower surface. Specifically, when the plate thickness is 0.7 mm or less, particularly 0.4 mm or less, the heat applied to the upper surface of the substrate reaches the lower surface.

FIG. 11 is a schematic diagram for explaining a stress distribution generated in a substrate when a crack is developed and advanced by performing laser irradiation and cooling on a thin glass substrate having a thickness of 0.7 mm or less. FIG. 11A is a perspective view, and FIG. 11B is a plan view.
FIGS. 12A, 12B, and 12C illustrate the temperature distribution and stress distribution after laser irradiation in the DD ′, section EE ′, and section FF ′ sections of FIG. 11, respectively. It is a schematic diagram for doing.

  In FIG. 11, an elliptical beam spot BS is formed by a laser beam irradiated from a laser beam irradiation mechanism (not shown). An elliptical cooling spot CS is formed behind the beam spot BS by the refrigerant blown from a cooling mechanism (not shown). The beam spot BS and the cooling spot CS are scheduled to be divided from the one end side where the initial crack TR has been formed in advance toward the other end side while maintaining the positional relationship at a slight distance. Scan along line SL.

At this time, a compressive stress (indicated by a broken-line arrow in the figure) is generated in the vicinity of the upper surface of the thin substrate GB near the region heated by the passage of the beam spot BS due to the expansion due to the heating. Next, tensile stress (indicated by solid arrows in the figure) is generated in the vicinity of the region cooled by the passage of the cooling spot CS due to the shrinkage due to cooling.
As a result, a stress gradient is generated in the vicinity of the upper surface of the thin substrate GB, with the front (back side) being compressive stress and the rear (front side) being tensile stress.
In this case, the stress distribution near the upper surface of the thin substrate GB is less likely to cause a temperature difference in the vertical direction of the substrate due to the thin plate thickness, and as a result, cracks that tend to progress in the plane direction are likely to be formed. Become. The reason for this will be described based on the stress generated in the substrate.

FIG. 12 is a schematic diagram for explaining the stress and strain generated in the thin substrate GB.
In the thin substrate GB, the heating part HR is formed inside the substrate as shown in FIG. 12A by heating by passing the beam spot BS of the laser beam irradiated on the upper surface of the substrate, and the heating part HR expands locally. As a result, compressive stress (indicated by broken line arrows in the figure) is generated. In this case, since the thickness of the substrate is thin, the heated portion HR immediately reaches the lower surface of the substrate GB.

Next, the cooling region CR is formed in the vicinity of the surface as shown in FIG.
In the case of the thin substrate GB, the cold part CR immediately reaches the center of the substrate GB.

  When the cooling heat is further transmitted, the cooling portion CR reaches the lower surface of the thin plate 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 maintain the stress gradient caused by the temperature gradient in the thickness direction of the substrate. Therefore, scribing is difficult to achieve with a thin substrate. Even if it is true, the process window becomes narrow and stable machining is difficult.

  For this reason, in the thin-plate substrate GB, the substrate is caused by a stress gradient caused by a temperature difference generated in the front-rear direction along the division line due to the presence of the region heated to the lower surface by the beam spot BS and the region cooled to the lower surface by the cooling spot. The crack will progress. That is, in the state where the heating part HR and the cooling part CR are present from the upper surface to the lower surface of the thin plate substrate GB, tensile stress is generated from the upper surface to the lower surface of the thin plate substrate GB in the vicinity of the boundary between the heating site HR and the cooling site CR. It will be. As a result, cracks reaching from the upper surface to the lower surface of the thin plate substrate proceed in the direction from the cooling region CR to the heating region HR. Therefore, the full cut processing mode is easily established.

Having thus become scribing when the thickness of the substrate is thick, as the thickness of the substrate becomes thinner, it tends to be full-cut processing, it is difficult to scribing.
Therefore, it is necessary to increase the thickness of the glass substrate in order to enter a scribe processing mode in which a scribe line can be reliably formed while avoiding full cut processing. For the processing of very thin substrates with a plate thickness of 0.4 mm or less, slicing by scribing should either select processing conditions from a narrow process window range, or give up because scribing is difficult. It was premised on cutting by cutting.

Therefore, the present invention can surely scribe even a thin glass substrate having a thickness of 0.1 mm to 0.4 mm, which has been thought to be impossible to scribe until now. An object is to provide a scribing method.
Another object of the present invention is to widen the process window under the processing conditions capable of performing the scribe processing in the thin glass substrate having the above thickness.

  Furthermore, an object of the present invention is to provide a scribing device preferable for performing scribing of a thin film glass substrate in the range of 0.1 mm to 0.4 mm.

Heating by laser irradiation is performed to the substrate, the subsequent cooling is performed, the substrate at the time the crack immediately after cooling is formed, the tensile stress is generated in the laser irradiation surface (the substrate upper surface) side. For this reason, it has been considered that the substrate after being heated and cooled is deformed upward (convex to the laser irradiation surface side).
However, by performing the laser scribing of a plurality of glass substrates thickness is different, obtains the thickness of the impact experimentally, I went a two-dimensional thermal elastic analysis by the finite element method based on the experimental results. As a result, when the thickness of the substrate is thinner than 0.4 mm and the scanning speed of the laser beam is slow (that is, when the time difference between heating and cooling becomes large), the substrate may be recessed upward depending on the processing conditions. It was discovered that it was deformed (concave on the laser irradiation surface side). And if such processing conditions are set, it is considered that the progress of cracks and the progress of cracks are suppressed, so that no cracks are formed. Therefore, in the present invention, the following scribing method and scribing apparatus are devised.

The scribing method of the present invention made to solve the above-mentioned problem is to heat a scribe line of a thin glass substrate having a plate thickness of 0.1 mm to 0.4 mm at a temperature that does not cause thermal damage to the substrate. Of the thin glass substrate that forms the scribe line by irradiating along the scribe line while moving the laser beam in a relative manner, and then cooling, so that cracks that do not penetrate the substrate travel on the scribe line. A scribing method having the following configuration.
Based on thermoelastic analysis by the finite element method, the relationship between the processing conditions of the substrate thickness and scanning speed when forming the scribe line, and the deformation state of the substrate due to the stress immediately after the laser heating and cooling are performed Is calculated.
Based on the calculation result, the processing conditions of the plate thickness and the scanning speed are set so that the deformation state of the substrate immediately after being cooled becomes a concave on the laser irradiation surface side.
A table having a metal table surface in which a large number of holes with an interval between adjacent holes of 2 mm or less are regularly formed and a substrate suction mechanism for sucking a substrate through holes in the table surface is prepared. Then, a substrate is placed thereon.
When placing the thin-film glass substrate on the table surface, on both the left and right sides of the planned scribe line, the linear distance between each hole adjacent to the planned scribe line is within 1 mm in the vicinity of the line along the planned scribe line. as such, it placed defines the position of the scribed line, a thin film glass substrate, performing the cooling and the laser irradiation in a state of being adsorbed to the substrate on the table surface by sucking through the hole.

Here, the “temperature not causing thermal damage” refers to a temperature that is excessively heated when the beam spot passes and remains damaged such as deformation and melting that can be visually confirmed. Specifically, for example, in a soda glass substrate, it may be lower than 500 ° C. (see FIG. 5) obtained experimentally as described later.
When processing a thin glass substrate having a thickness of 0.1 mm to 0.4 mm, the substrate is attracted to the table by a substrate adsorption mechanism and fixed. Thus, the longitudinal direction of the stress gradient along the scribed line, to suppress the force to Sako transversely to scribed, preventing from becoming full cut state.

  On the other hand, in the case of a substrate that is deformed to be concave on the laser irradiation surface side, the tensile stress generated on the surface on the laser irradiation side is relaxed by the deformation of the substrate, so that cracks hardly propagate only on the surface of the substrate The crack does not progress at all, or even if the crack progresses, it becomes a full cut. However, by fixing the substrate with the substrate adsorption mechanism, it becomes possible to develop cracks (with the suppression of full cut) by eliminating the bending that has been recessed upward, and as a result, it has not been possible so far Scribe processing can be established under the appropriate processing conditions.

Here, the influence by the difference whether the table surface of a board | substrate adsorption | suction mechanism is a porous table or a metal hole processing table is demonstrated. When a porous table is used, it has an excellent effect in terms of eliminating the deflection, but as described above, if the porous table is directly irradiated with a laser beam, there is a possibility that it will be altered or discolored. is there. Therefore, adsorption is performed with a metal hole processing table which is not easily affected by laser irradiation. In that case, the bending can be eliminated in the vicinity of the hole to be adsorbed, but the force for eliminating the bending is weakened when the hole is separated from the hole. From the calculation result by the finite element method to be described later, it was found that when the linear distance between the scribe line and the hole is within 1 mm, a tensile stress is effectively applied to the substrate and the substrate can be bent. Then, it has been found that if the next suction hole is close to the scribe line and close to the scribe line, the crack can proceed along the scribe line.
Therefore, when placing the thin-film glass substrate on the hole processing table, the linear distance between each hole adjacent to the planned scribe line is within 1 mm along the vicinity of the planned scribe line on both the left and right sides of the planned scribe line. As shown, the scribing line is positioned and placed, and the thin-film glass substrate is sucked through the holes so that the substrate is adsorbed to the table surface, and the scribe processing is performed. Can be advanced.

  According to the present invention, even a thin substrate having a plate thickness of 0.1 mm to 0.4 mm can be made scribe processing instead of full cut processing, and the process window capable of scribe processing can be widened. it can. Moreover, since a metal hole processing table is used, even if the laser beam is directly irradiated onto the table surface, the table surface will not be altered or discolored.

In the above invention, the holes formed in the table surface may be regularly formed in any pattern of a triangular lattice, a square lattice, and a staggered lattice.
By forming holes on the table surface with any of these patterns, holes can be arranged on both sides of the planned scribe line along the planned scribe line so that they are lined up within 1 mm from the planned scribe line. You can be sure.

Further, in the above invention, when the substrate immediately after being cooled to set the processing conditions of the thickness and scan speed variations as a concave laser irradiation surface, the thickness of the substrate, and processing conditions of the scanning speed The relation between the deformation state of the substrate due to the stress immediately after the laser heating and cooling may be set based on the equation (1).
y <7.5x ^-2.8 (1)
Here, y is a scanning speed (mm / second), and x is a plate thickness (mm).
By setting the processing conditions from this range, a concave state can be formed.

The figure which shows the structure of the principal part of the laser scribing apparatus used in order to implement the scribing method of this invention. The figure which shows the board | substrate thickness calculated | required by the thermoelastic analysis by a finite element method, the scanning speed of a beam spot and a cooling spot, and the deformation | transformation state of a board | substrate. The data (FIG. 3 (a1) to FIG. 3 (d1)) obtained as the scanning speed V with respect to the laser output P, and the crack depth Dc with respect to the laser output P were obtained as the laser scribing processing conditions at each plate thickness h. The figure which shows data (FIG. 3 (a2)-FIG.3 (d2)). The figure which shows the result which arranged the crack depth Dc with respect to plate | board thickness. The figure which shows the result of a thermoelastic analysis. The figure which shows the temperature distribution and deformation _| transformation state of xz surface in the maximum tensile stress (sigma) _tmax generation _| occurrence _| production position of a cooling region. The figure which shows the stress distribution corresponding to FIG. The figure which arranged the maximum tensile stress (sigma) _tmax of the cooling region in order regarding plate _{| board} thickness. The schematic diagram for demonstrating the stress distribution which arises in a board | substrate when a crack progresses and advances by performing laser irradiation and cooling with respect to a thick board | substrate. The schematic diagram for demonstrating the temperature distribution and stress distribution in the A-A 'cross section of FIG. 9, B-B' cross section, and C-C 'cross section. The schematic diagram for demonstrating the stress distribution which arises in a board | substrate when a crack progresses and advances by performing laser irradiation and cooling with respect to a thin board | substrate. The schematic diagram for demonstrating the temperature distribution and stress distribution in D-D 'of FIG. 11, the cross section E-E', and the cross section F-F 'cross section. The figure which shows the relationship between the scribe plan line of a glass substrate, and the linear distance of the hole for adsorption | suction of a hole processing table. The figure which showed the relationship of the tensile stress which generate | occur | produces on the board | substrate surface immediately after cooling with respect to the linear distance from a scribe planned line to a hole with the board | plate thickness of 0.15 mm. The figure which showed the relationship of the tensile stress which generate | occur | produces on the board | substrate surface immediately after cooling with respect to the linear distance from a scribe planned line to a hole with the board | plate thickness of 0.2 mm. The figure which showed the relationship of the tensile stress which generate | occur | produces on the board | substrate surface immediately after cooling with respect to the linear distance from a scribe planned line to a hole with the board | plate thickness of 0.3 mm. The figure which showed the relationship of the tensile stress which generate | occur | produces on the board | substrate surface immediately after cooling with respect to the linear distance from a scribe planned line to a hole with the board | plate thickness of 0.4 mm. The figure which showed the relationship of the tensile stress which generate | occur | produces on the board | substrate surface immediately after cooling with respect to the linear distance from a scribe planned line to a hole with a board | substrate with a board thickness of 0.5 mm. The figure which shows the example of a pattern of hole arrangement | positioning.

The present invention will be described below with reference to the drawings.
The process up to the completion of the present invention will be described. First, a thin glass substrate (plate thickness is 0.1 mm to 0.4 mm) is subjected to laser scribing using a porous table adsorption mechanism. Has been made (Japanese Patent Application No. 2008-274768). However, when a porous table is used, there is a new problem that the porous table itself is altered when directly irradiated with laser. Thus, the present invention has been completed with further improvements.
Therefore, in explaining the present invention, it is necessary to explain the invention of laser scribing using a porous table. For convenience of explanation, first, laser scribing using a porous table as a premise of the present invention is used. The apparatus and the laser scribe processing method will be described, and then the laser scribe processing by the metal hole processing table of the present invention will be described.
[Device configuration]
An apparatus configuration for carrying out the laser scribing method will be described. Here, a general-purpose laser scribing device equipped with a substrate adsorption mechanism for a porous table is used. FIG. 1 is a diagram showing a schematic configuration of a main part of a laser scribing device LS to be used. FIG. 2 is a diagram showing the relationship between the plate thickness of the glass substrate, the scanning speed of the beam spot and the cooling spot obtained by thermoelastic analysis by the finite element method described later, and the deformation state of the substrate.

  A table 10 provided with a vacuum suction mechanism is used. On the upper surface of the table 10, a plate 11 formed of a porous member (for example, a porous ceramic such as alumina) and on which a substrate G is placed is provided (as will be described later, in the present invention, this porous Instead of a material member, a metal hole machining table is used). The table 10 is in close contact with the periphery of the plate 11 and has a bottom surface. A body 12 in which a hollow space 12a is formed between the table 11 and a flow path 13 connected to the hollow space 12a is formed. A vacuum pump 16 that depressurizes the hollow space 12a via a plug 15, a flow path 13, an external flow path 14, and an opening degree adjustment valve 16a; a flow path 13, an external flow path 14, and a pressure adjustment valve 17a. And an air source 17 for sending pressurized air to the hollow space 12a. The table 10 can suck the glass substrate G placed on the plate by operating the vacuum pump 16, and can release the suction state by sending air from the air source 17. It is.

  Above the plate 11 is a scribe that integrally scans a laser irradiation mechanism 21 that irradiates an elliptical beam spot on the substrate and a cooling mechanism 22 that jets a coolant to form an elliptical cooling spot on the substrate. A head 23 is arranged. The scribe head 23 can be controlled at a scanning speed between 10 mm / second and 500 mm / second by a scanning drive mechanism and a control unit (not shown).

[Scribe method]
A glass substrate having a plate thickness of 0.1 mm to 0.4 mm is a target. Until now, it was difficult to scribe a glass substrate in this thickness range, and it was necessary to select processing conditions from a narrow process window. In particular, it has been considered that the scribe process cannot be performed at all when the thickness of the substrate is reduced and the process window is narrowed to about 0.2 mm.
However, the experiments described below, by performing a two-dimensional thermal elastic analysis by the finite element method based on the experimental results, as shown in FIG. 2, the plate thickness and the deformation substrate is concave on the laser irradiation surface side It has been found that there are processing conditions for scanning speed. Therefore, with the processing conditions of the plate thickness and scanning speed that deforms to become concave on the laser irradiation surface side, the substrate is sucked by the substrate suction mechanism and processed within the range of the above processing conditions, so that a full cut is achieved. In addition, a force in the same direction as the tensile stress is applied to the upper surface side of the substrate. As a result, scribing can be reliably performed.

[Experiment]
To study the effect of the thickness of the glass substrate in the laser scribing, the plate thickness is 1.1 mm, 0.7 mm, 0.55 mm, the range of the laser scribing is possible machining conditions for a glass substrate of 0.4mm experiments Based on the results, a two-dimensional thermoelastic analysis by the finite element method was performed.

The experimental method will be described. A 300 mm × 400 mm soda glass substrate is fixed to a vacuum suction mechanism (see FIG. 1) to make it difficult to be fully cut. An initial crack serving as a starting point for scribing is previously provided at the end of the glass substrate with a cutter wheel. A CO ₂ laser is used as the laser light source, and it is shaped so as to form an elliptical beam spot on the glass surface. The cooling spot is formed by a water jet and is formed near the rear end of the beam spot. The positional relationship between the beam spot and the cooling spot is the same as that of the beam spot BS and the cooling spot CS shown in FIGS. 9B and 11B, and the dimensional relationship is as follows.
Beam spot long axis YA: 22 mm
Beam spot minor axis XA: 2.1 mm
Long axis YB of the cooling spot: 3.0 mm
Short axis YA of the cooling spot: 2.0 mm
Distance d between beam spot center and cooling spot center: 10 mm

FIG. 3 shows data (FIGS. 3 (a1) to 3 (d1)) obtained as the scanning speed V with respect to the laser output P, and the crack depth with respect to the laser output P. This is data (Fig. 3 (a2) to Fig. 3 (d2)) for which the depth Dc is obtained.
When the plate thickness h is 0.4 mm, as shown in FIG. 3 (d1), scribing is possible even at the maximum scanning speed of 500 mm / sec. 3 (a1) to FIG. 3 (d1), the x mark on the high speed side represents the state where the progress of the crack is stopped, and the x mark on the low speed side represents the state where the thermal damage remains on the glass substrate. Yes.

In any plate thickness, as the laser output increases, the scribing scanning speed tends to increase. In addition, the processing conditions (x mark on the low speed side) where the thermal damage occurred are almost the same regardless of the plate thickness.
As for the crack depth Dc for each laser output in FIGS. 3A2 to 3D2, the deeper one corresponds to the low speed side of the scanning speed and the shallower one corresponds to the high speed side.

The processing conditions (x mark on the high speed side) in which the crack progress stopped when the plate thickness h is 1.1 mm are wide on the low output side of the laser, but narrow on the high output side. When the scanning speed is 350 mm / second or more, scribing cannot be performed.
On the other hand, when the plate thickness h is 0.4 mm, the range of scanning speed that can be scribed on the low output side is narrow, and when the laser output is 30.4 W, scribing cannot be performed at all scanning speeds. On the other hand, the scanning speed range in which scribing on the high output side is wide is possible, and scribing is possible even at a scanning speed of 500 mm / sec.
That is, as the plate thickness h increases, scribing becomes more difficult on the high speed side of the scanning speed, and as the plate thickness h decreases, scribing becomes difficult on the low speed side.

FIG. 4 is a diagram showing the results of arranging the crack depth Dc under the five processing conditions in which thermal damage did not occur with respect to the plate thickness. The conditions under which the progress of cracks stopped and scribing could not be performed are indicated by crosses.
Under the conditions of a laser output of 71.0 W and a scanning speed of 320 mm / second, scribing cannot be performed at a plate thickness of 1.1 mm. Under the conditions of a laser output of 30.4 W and a scanning speed of 80 mm / second, the plate thickness is 0.4 mm. You cannot scribe. Except for these, scribing is possible at all plate thicknesses.

Next, based on the processing conditions obtained in the experiment, a thermoelastic analysis by the finite element method was performed by the following method, and the influence of the plate thickness on the scribing processing conditions was examined. The finite element method analysis program is Quick Welder manufactured by the Center for Computational Mechanics.
The element is divided with the laser irradiation surface as the xy coordinate, the y axis as the scribe direction, and the z axis as the plate thickness direction. In the element division, the division minimum value in the beam direction (y direction) was 3.7 μm, and the minimum winning value in the plate thickness direction (z direction) was 2.7 μm.
The physical property values of the soda glass substrate are as follows.
Density: 2520kg / m ²
Specific heat: 800J / kgK
Thermal conductivity: 1.03 W / mK
Thermal expansion coefficient: 8.7 × 10 ⁻⁶ K ⁻¹
Young's modulus: 71.6 GPa
Poisson's ratio: 0.23
Softening temperature: 720 ° C to 730 ° C
Bending strength: 49MPa

  The time step was set to 0.25 mm / V, which is a time obtained by dividing 0.25 mm by the scanning speed V. The size of the beam spot and the cooling spot was the same elliptical shape as described above, and had a Gaussian distribution.

In the two-dimensional heat conduction analysis on the xz plane, the center of the laser beam was scanned from the position y = -15 mm in the y direction, and the heating and cooling conditions were changed with time. At this time, the amount of heat input to the glass was set to 0.798 P (W) with respect to the laser output P (W) in consideration of the attenuation rate of the optical system and the reflectance of the glass. Further, the heat transfer coefficient α ₀ in the cooling region was set to 10 ⁵ W / m ² K.
Subsequently, using the obtained temperature field was carried out a two-dimensional thermal elastic analysis of x-z plane as the plane stress problems assuming _{σ yy = τ yx = τ yz} = 0. The irradiation end of the laser beam was constrained in the x direction, and the other end was constrained in the x direction and the z direction, respectively.
In the following description, T _max is the maximum temperature reached on the glass substrate surface during laser scribing, and σ _tmax is the maximum tensile stress of σ _xx generated on the glass substrate surface in the cooling region.

Thermoelastic analysis was performed on glass substrates having a thickness of 0.4 mm, 0.55 mm, 0.7 mm, and 1.1 mm under processing conditions of output and scanning speed at which laser scribing was possible.
FIG. 5 is a diagram showing the results of thermoelastic analysis. FIGS. 5A to 5D show the analysis results of plate thicknesses of 1.1 mm, 0.7 mm, 0.55 mm, and 0.4 mm, respectively.
In the drawing, the upper plot point group represents the maximum temperature T _max reached on the glass substrate surface (right vertical axis), and the lower plot point group represents the maximum tensile stress σ _tmax on the glass substrate surface (left). Vertical axis).
The x mark on the high speed side of each plot point group corresponds to the processing conditions in which the crack progress of the laser scribe stopped in the middle of FIGS. 3 (a1) to 3 (d1). Corresponds to the processing conditions that caused thermal damage.

At each plate thickness, when the laser output is constant, T _max increases as the scanning speed decreases. At any laser output, the upper limit value of T _max is almost constant (about 500 ° C.) regardless of the scanning speed. Therefore, it can be said that the glass is not thermally damaged below the upper limit of _Tmax .

On the other hand, when the laser output is constant, σ _tmax decreases as the scanning speed increases. This is the reason why the crack depth is shallow on the high speed side in FIGS. 3 (a2) to 3 (d2). The lower limit of σ _tmax at any laser output is almost constant (about 65 MPa) regardless of the scanning speed. Therefore, it can be said that the crack in laser scribing progresses above the lower limit of σ _tmax .
Thereby, from the result of the thermoelastic analysis, regardless of the plate thickness, the processing conditions capable of laser scribing can be estimated from the maximum surface temperature T _max and the maximum tensile stress σ _{tmax in the} cooling region.

Next, the influence of the plate thickness in laser scribe will be described.
6 is a diagram showing the temperature distribution and deformation of the x-z plane at the maximum tensile stress sigma _tmax generation position of the cooling zone (although one half to one end of the line to be scribed). The left end of each figure corresponds to the position directly under the scribe line. Therefore, the upper left corner is the laser incident position. On the opposite side of the scribe line, a temperature distribution and a deformed state are formed in which these figures are mirror-symmetrical due to symmetry.
The inclination in each figure represents the magnitude of the substrate deformation and the deformation direction (convex upward or concave upward). In other words, the downward-right view is an upward convex deformation state, and the upward-right view is an upward concave deformation state.

  Here, for a substrate having a plate thickness of 1.1 mm, 0.7 mm, 0.55 mm, and 0.4 mm, (a) laser output P = 30.4 W, scanning speed V = 80 mm / second, and (b) Processing conditions of laser output P = 52.8 W, scanning speed V = 80 mm / second, and (c) laser output P = 71.0 W, scanning speed V = 320 mm / second are shown.

As for the temperature distribution on the xz plane, a high temperature region remains in the glass immediately under cooling. The lower the scanning speed, the deeper the high temperature region, and heat is transferred to the inside.
Among these, in particular, under the processing conditions where the plate thickness is 0.4 mm, the laser output P is 30.4 W, and the scanning speed V is 80 mm / second, the temperature of the back surface rises to about 200 ° C. And in the board | substrate of this process condition, unlike others, it deform | transforms into a concave upward.

FIG. 7 is a diagram showing a stress distribution corresponding to FIG. A tensile stress is generated on the surface of the cooling region, a high temperature region is formed inside the substrate immediately below the cooling region, and a compressive stress field is formed.
The laser output P = 30.4W plate thickness at 0.4 mm, an internal compressive stress field depth when processing with processing conditions of the scanning velocity V = 80 mm / sec (relative depth to plate thickness) of , Deeper than other processing conditions. This is considered to be a cause of the substrate being deformed upwardly.

FIG. 8 is a diagram showing the maximum tensile stress σ _tmax in the cooling region under the five processing conditions shown in FIG. Under any processing condition, σ _tmax is convex upward, and the maximum plate thickness tends to shift to a thinner side as the scanning speed increases, and to a thicker side as the speed decreases. For example, under the processing conditions of laser output P = 71.0 W and scanning speed V = 320 mm / second, the plate thickness at which the maximum tensile stress σ _tmax is maximized approaches 0.4 mm. It is considered that the maximum tensile stress σ _tmax when the plate thickness is 1.1 mm is smaller than the lower limit value at which the crack progresses, and as a result, scribing can no longer be performed.
Further, under the conditions of laser output P = 30.4 W and scanning speed V = 80 mm / sec, the plate thickness at which the maximum tensile stress σ _tmax is maximized is 1.1 mm or more. As a result, it is considered that the maximum tensile stress σ _tmax with a plate thickness of 0.4 mm is smaller than the lower limit value at which the crack progresses, and scribing can no longer be performed.

FIG. 2 described above is a diagram showing the deformation state of the substrate (upwardly convex state and upwardly concave state) using the plate thickness and the scanning speed as parameters.
If the result of the thermoelastic analysis mentioned above is arranged, the state in which the substrate is convex upward (right side from the boundary) is divided with the following formula (1) as the boundary.
y <7.5x ^-2.8 (1)
Here, y is a scanning speed (mm / second), and x is a plate thickness (mm).

  For example, when the substrate thickness is 0.4 mm, the scanning speed is 320 mm / second, and when it is 160 mm / second, it is deformed upward, but when the scanning speed is 80 mm / second, it is concave upward. It will be transformed into.

When the thickness of the substrate is 0.1 mm to 0.4 mm, the range in which the substrate is concave in Formula (1) becomes dominant.
As a result, as described above, in the range where the concave state is formed, the substrate suction mechanism is brought into close contact with the table to suppress the deformation of the substrate into the concave state, so that a tensile stress is applied to the upper surface of the substrate. It is possible to make the cracks progress and progress easily. Therefore, a process window that can be scribed is expanded. In order to suppress the deformation of the substrate in the scribe line, it is necessary to suck the vicinity of the scribe line, but scribe processing can be performed by using a table having a vacuum suction mechanism provided with a porous member on the upper surface. Confirmed that the process window can be expanded.

  By the way, in the region that protrudes upward, if the substrate is adsorbed with an adsorption mechanism to avoid becoming a full cut state, a force in the same direction as the compressive stress is applied to the position of the planned scribe line by adsorbing the substrate. However, when scribing a thin plate substrate, it has been proved that a method using a scribing method for processing in a region that is recessed upward is significant.

(Embodiment)
The scribe processing when the substrate is adsorbed by the adsorption mechanism using the porous table has been described above. By adopting the porous table, it was possible to widen the process window for scribing the thin glass substrate of 0.1 mm to 0.4 mm.
However, as described above, if the porous table is directly irradiated with the laser beam, the table surface may be altered and discolored. Since the start and end of the planned scribe line usually come to the substrate end of the glass substrate, when the laser irradiation is performed on the vicinity of the substrate end, a part of the laser beam is irradiated directly on the porous table. . If a porous table that has been repeatedly subjected to laser irradiation is used, the adsorption performance and flatness will deteriorate at the altered portion, and the processing uniformity cannot be maintained.

Therefore, in the present invention, in the laser scribing apparatus LS shown in FIG. 1, a plate 11 is replaced with a plate made of a metal and drilled with a hole.
Conventionally, most of the hole processing tables are arranged in a square lattice or the like at intervals of 1 cm at most. When it comes to hole processing at intervals shorter (e.g. 2mm intervals) than, although the processing cost is enormous, because there is no benefit is better than the porous plate in the adsorption performance.

  However, in the case of scribing a glass substrate with a plate thickness of 0.1 mm to 0.4 mm when using a hole processing table at an interval of 1 cm, the effect of expanding the scribing process window as obtained with a porous table is It was not obtained, scribe lines could not be formed, or it shifted to full cut processing.

Then, the conditions for realizing the scribing of a glass substrate having a plate thickness of 0.1 mm to 0.4 mm using a hole processing table were examined using thermoelastic analysis by a finite element method. The scanning speed used for the analysis was scanning speed V = 200 mm / sec. Note that under the condition of the scanning speed V = 200 mm / sec, a glass substrate having a thickness of 0.3 mm or less is deformed upward in the cooling region (see FIG. 2).
As a result, as shown in FIG. 13, a linear distance L that is the shortest distance between the scribe line S of the glass substrate G and the suction holes h, h of the hole processing table T is important, and this distance is greater than or equal to a threshold value. Then, it was found by calculation that the tensile stress on the substrate surface can be increased.

  FIGS. 14 to 18 show the state immediately after cooling with respect to the linear distance L from the scribe planned line S to the hole h in each substrate having a plate thickness of 0.15 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. It is the figure which showed the relationship of the tensile stress which generate | occur | produces on a substrate surface (position of F in FIG.11 (b)).

According to this, on the condition of the analyzed scanning speed V = 200 mm / sec, the linear distance L is 1 mm for a glass substrate with a plate thickness of 0.15 mm to 0.3 mm that is deformed upward in the cooling region. It was found that the tensile stress suddenly increased below. On the other hand, in the scanning speed V = 200 mm / sec of the conditions analyzed, the glass substrate thickness which deforms in a convex state to top of 0.4mm and 0.5mm in the cooling zone, the linear distance L is 1mm or less in the opposite Then, the tensile stress decreases. Incidentally, although not shown, be a glass substrate 0.4 mm, in the conditions of the scanning speed V = 80 mm / sec (see FIGS. 2 and 7), concave shape on the glass substrate in the cooling zone If the straight line distance L is 1 mm or less, the tensile stress increases.
From the above, for thin glass substrates of 0.1 mm to 0.4 mm, the distance from the scribe line to the hole is set to 1 mm or less, and if the scanning speed is set appropriately, strong tension is applied to the scribe line. It was found that stress can be applied and scribe processing can be established.

Therefore, when a thin glass substrate is placed on a table, requirements necessary to ensure that the linear distance between the planned scribe line and the hole can be 1 mm or less on both sides of the planned scribe line. As a metal table in which a large number of holes having an interval between adjacent holes of 2 mm or less are regularly formed, the requirements can be surely satisfied.
That is, as shown in FIG. 13, if the substrate G is placed so that the scheduled scribe line S set on the thin glass substrate is positioned at the center of two adjacent holes, the scheduled scribe line S is formed on both the left and right sides. Can be 1 mm or less.

  As a property of the glass substrate, once a crack occurs, the crack progresses from several mm to several centimeters. Therefore, along the scribe planned line, an interval of several millimeters to several centimeters is provided at intervals of adjacent holes. If the holes having an interval of 2 mm or less are regularly arranged, cracks can be continuously advanced on the scribe line.

  Therefore, regular patterns such as a square lattice shown in FIG. 19A, a triangular lattice shown in FIG. 19B, and a staggered lattice shown in FIG. 19C are formed as specific hole patterns. That's fine. With these lattice shapes, if the substrate is placed so that the scribe line S is at the position shown in the figure (the position of the vertical bisector connecting the two adjacent holes h, h). And scribe processing can be surely performed. Of course, even if it is a hole pattern other than these, if the pattern which can arrange | position the hole which the space | interval of adjacent two holes is less than 2 mm regularly along a scribe planned line, the same effect can be acquired. it can.

  In practicing the present invention, it is preferable to arrange holes on the entire surface of the table so that the distance between adjacent holes is within 2 mm. In this case, the number of holes increases in proportion to the area of the table. As a result, the processing cost increases. Therefore, the present invention can be applied to only a part of the table surface. For example, when a linear scribe line is formed on the substrate, a band-like region (for example, about 1 cm in width) is provided on the table, and for the holes in the region, the interval between adjacent holes is within 2 mm. Holes may be formed, and holes other than that may be provided at intervals of several centimeters.

  In addition, in order to facilitate the alignment operation of the scribe planned line, if a reference line serving as a positioning mark is previously drawn on the table surface, it is only necessary to align the scribe planned line S on this reference line. The substrate can be easily positioned.

  The present invention is used when scribing a thin glass substrate having a plate thickness of 0.1 mm to 0.4 mm.

10: Table 11: Plate (porous member)
12: Body 16: Vacuum pump 17: Air source 21: Laser irradiation mechanism 22: Cooling mechanism 23: Scribe head LS: Laser scriber G: Glass substrate T: Table S: Scribe line P: Hole pitch L: Scribe line Distance between hole and hole

Claims (5)

Irradiation along the planned scribe line while moving the laser beam relative to the planned scribe line of a thin glass substrate with a thickness of 0.1 mm to 0.4 mm at a temperature that does not cause thermal damage to the substrate. Then, by cooling, a method for scribing a thin glass substrate that allows cracks not penetrating the substrate to progress on the scribe line,
Based on thermoelastic analysis by the finite element method, the relationship between the processing conditions of the substrate thickness and scanning speed when forming the scribe line, and the deformation state of the substrate due to the stress immediately after the laser heating and cooling are performed To calculate
Based on the calculation result, set the processing conditions of the plate thickness and the scanning speed that deforms the deformation state of the substrate immediately after being cooled becomes concave on the laser irradiation surface side,
A table having a metal table surface in which a large number of holes with an interval of 2 mm or less between adjacent holes are regularly formed and a substrate adsorption mechanism for adsorbing a substrate through the holes in the table surface is used. ,
When the thin-film glass substrate is placed on the table surface, the linear distance between each hole adjacent to the planned scribe line is 1 mm on the left and right sides of the planned scribe line, in the vicinity of the line along the planned scribe line. Set the position of the scribe line to be within,
A scribing method comprising performing laser irradiation and cooling in a state where the thin film glass substrate is adsorbed through the holes.   The scribing method according to claim 1, wherein the holes formed in the table surface are regularly formed in a pattern of any of a triangular lattice, a square lattice, and a staggered lattice. When the substrate immediately after being cooled to set the processing conditions of the thickness and scan speed variations as a concave laser irradiation surface, the thickness of the substrate, and processing conditions of the scanning speed, the laser heating and cooling and The scribing method according to claim 1, wherein the scribing method is set based on the formula (1) as a relationship with a deformation state of the substrate due to a stress immediately after the step is performed.
y <7.5x ^-2.8 (1)
Here, y is a scanning speed (mm / second), and x is a plate thickness (mm). Irradiation along the planned scribe line while moving the laser beam relative to the planned scribe line of a thin glass substrate with a thickness of 0.1 mm to 0.4 mm at a temperature that does not cause thermal damage to the substrate. Then, by cooling, a scribing device for a thin glass substrate in which a crack that does not penetrate the substrate proceeds on the scribe line,
A table provided with a metal table surface on which the substrate is placed;
The table surface is provided with a substrate suction mechanism for regularly forming a large number of holes having an interval of 2 mm or less between adjacent holes, and suctioning a substrate through the holes on the table surface. apparatus. The scribing device according to claim 1, wherein the holes formed in the table surface are regularly formed in a pattern of any of a triangular lattice, a square lattice, and a staggered lattice.