CN111356663A

CN111356663A - Glass substrate

Info

Publication number: CN111356663A
Application number: CN201880073224.1A
Authority: CN
Inventors: 奥隼人; 山本好晴; 中塚弘树
Original assignee: Nippon Electric Glass Co Ltd
Current assignee: Nippon Electric Glass Co Ltd
Priority date: 2017-11-13
Filing date: 2018-10-17
Publication date: 2020-06-30
Also published as: TW201922661A; JP7045647B2; KR102609772B1; JP2019089667A; WO2019093087A1; KR20200078564A

Abstract

The glass substrate (1) has a first main surface (2) and a second main surface (3). The surface roughness Ra of the first main surface (2) is 0.2nm or less, the surface roughness Ra of the central region (4) of the second main surface (3) is 0.3nm or more and 1.0nm or less, and a surface-roughened region (A) exhibiting a surface roughness Ra of 0.2nm or more greater than the surface roughness Ra of the central region (4) is provided in the outer peripheral region (5) of the second main surface (3).

Description

Glass substrate

Technical Field

The present invention relates to a glass substrate.

Background

As is well known, flat panel displays (hereinafter, abbreviated as FPDs) typified by Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs), Field Emission Displays (FEDs), organic EL displays (OELDs), and the like are mainstream as image display devices in recent years. Since weight reduction of these FPDs is being promoted, there is an increasing demand for reduction in thickness of glass substrates used for the FPDs.

The glass substrate is obtained by the following steps: for example, a plate-shaped glass (a belt-shaped plate glass) formed into a belt shape by a plate-shaped glass forming method typified by various down-draw methods is cut into a predetermined size in a longitudinal direction, both end portions in a width direction (a direction parallel to a main surface of the belt-shaped plate glass and orthogonal to the longitudinal direction, hereinafter the same) of the cut plate glass are further cut, and then, polishing or the like is performed on each cut surface as necessary.

However, when an FPD is manufactured using such a glass substrate, electrostatic charging in the manufacturing process may become a problem. That is, since glass as an insulator is easily charged, when a glass substrate is placed on a mounting table and subjected to a predetermined process, the glass substrate may be charged by contact and separation between the glass substrate and the mounting table (this may be referred to as separation charging). When a conductive object approaches an electrically charged glass substrate, electric discharge occurs, and there is a possibility that various elements formed on the main surface of the glass substrate or electrode lines constituting an electronic circuit are damaged or the glass substrate itself is damaged due to the electric discharge (these are sometimes referred to as dielectric breakdown or electrostatic breakdown). In addition, the charged glass substrate is likely to adhere to the mounting table, and the glass substrate may be broken by forcibly peeling the glass substrate. These are certainly causes of display defects, and are therefore phenomena to be avoided as much as possible.

As a means for avoiding the above phenomenon, for example, a method of roughening the back surface of the glass substrate (main surface on the side in contact with the mounting surface of the mounting table) by supplying a predetermined gas to the back surface and performing a surface treatment on the back surface is conceivable (for example, see patent document 1). Since the larger the contact area between the glass substrate and the mounting surface, the larger the amount of electrification during peeling tends to be, the back surface of the glass substrate in contact with the mounting surface is roughened, thereby reducing the contact area between the glass substrate and the mounting surface and suppressing the electrification during peeling. Further, since the back surface of the glass substrate is smoother, the glass substrate is more likely to adhere to a smooth surface such as a mounting surface, and the contact area between the glass substrate and the mounting surface is reduced, the glass substrate is less likely to adhere to the mounting surface, and breakage of the glass substrate during peeling is prevented.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-80331

Disclosure of Invention

Problems to be solved by the invention

The above roughening is generally performed uniformly over the entire area of one main surface in the glass substrate. However, it is known that, in a state where the degree of roughening is uniform over the entire main surface area, the roughening may not be appropriate in consideration of the handling property of the actual glass substrate. That is, in the actual peeling step, the glass substrate is peeled from the mounting table by raising pins provided at a plurality of positions on the mounting table. At this time, the glass substrate is peeled off from the end portion thereof. When such a peeling operation is considered, if the distribution of the surface roughness is uniform, the effect of roughening may not be sufficiently obtained. In other words, there may be a surface roughness distribution suitable for an actual peeling action. In addition, considering only the ease of peeling, it is sufficient to improve the degree of roughening (surface roughness) of the back surface as a whole, but in this case, the roughening treatment takes more time than necessary, and therefore, this is not preferable in terms of productivity and further cost.

In view of the above circumstances, the present specification has a technical problem to be solved by obtaining a glass substrate having a surface roughness distribution of a main surface suitable for an actual peeling operation at low cost.

Means for solving the problems

The above object is achieved by the glass substrate of the present invention. That is, the glass substrate is a glass substrate having a first main surface and a second main surface, and is characterized in that the surface roughness Ra of the first main surface is 0.2nm or less, the surface roughness Ra of the central region of the second main surface is 0.3nm or more and 1.0nm or less, and a surface-roughened region exhibiting a surface roughness Ra of 0.2nm or more larger than the surface roughness Ra of the central region is provided in the outer peripheral region of the second main surface. The "central region" described in the present specification means a region located at the center (center of gravity) of the second main surface of the glass substrate and having a shape in which the outline of the second main surface is reduced by a reduction scale of 0.6 as a boundary. The "outer peripheral region" refers to a region located on the outer periphery of the second main surface of the glass substrate, the remaining region excluding the central region, of the second main surface. The surface roughness Ra of the central region is an average value of arithmetic mean roughness measured at the central position of the central region and at positions on the boundary between the outer peripheral region and the central region (8 positions P1 to P8 shown in fig. 1 in this specification), and the surface roughness Ra of the outer peripheral region is measured at positions on a shape formed by moving each side defining the second main surface of the glass substrate by 10mm toward the central region side (8 positions P9 to P16 shown in fig. 1 in this specification). The term "provided with a surface-roughened region" means that any one of the measurement positions in the outer peripheral region exhibits a surface roughness Ra that is 0.2nm or more greater than the surface roughness Ra in the central region.

As described above, in the present invention, the surface roughness Ra of one main surface (first main surface) of the glass substrate is set to be a size (0.2nm or less) that allows various elements, electrode lines, electronic circuits, and the like to be formed with high accuracy, the surface roughness Ra of the central region of the second main surface is set to be 0.3nm or more and 1.0nm or less, and the surface-roughened region that exhibits a surface roughness Ra larger by 0.2nm or more than the surface roughness Ra of the central region is provided in the outer peripheral region of the second main surface. Thus, the surface-roughened region located in the outer peripheral region serves as a starting point for peeling, and peeling can be smoothly started. This reduces cracking of the glass substrate, and enables safe peeling of the glass substrate. In addition, the problem that the glass substrate is not peeled off from the placing table because the glass substrate is closely contacted with the placing table can be reduced. Further, since only the glass substrate in which the surface roughness Ra of one or more surface-roughened regions included in the outer peripheral region exhibits a predetermined value or more (a value of 0.2nm or more larger than the surface roughness Ra of the central region) can be used, the area and amount of the treatment for roughening can be minimized. Thus, the roughening treatment can be performed efficiently and at low cost.

In the glass substrate of the present invention, the surface-roughened region may extend along any one of the plurality of side portions of the second main surface, and the surface roughness Ra of the outer peripheral region may decrease as it goes away from the one side portion. The phrase "the surface-roughened region extends along the side" means that the surface roughness Ra of the measurement position at a distance of 10mm from a certain side is 0.2nm or more greater than the surface roughness Ra of the central region.

As described above, when the surface-roughened region extends along any one of the side portions, the surface roughness distribution is provided such that the surface roughness Ra of the outer peripheral region decreases as it moves away from the side portion, whereby the glass substrate can be intentionally oriented in a direction in which the glass substrate is likely to peel off. Therefore, the glass substrate can be peeled off easily and safely by smoothly proceeding from the surface-roughened region serving as a starting point.

In the glass substrate of the present invention, the surface-roughened region may be provided in at least one corner portion of the plurality of corner portions of the second main surface. The phrase "the surface-roughened region is provided at the corner portion" means that, in a shape in which each side defining the second main surface of the glass substrate is moved by 10mm toward the central region, the surface roughness Ra at the measurement position at the vertex is greater than the surface roughness Ra at the central region by 0.2nm or more.

In this way, by providing the surface-roughened region in at least one of the four corners of the second main surface, the corner serves as a starting point for peeling, and thus peeling of the glass substrate can be smoothly started.

In this case, in the glass substrate of the present invention, the surface-roughened region may be provided in all of the plurality of corner portions.

In this way, by providing the surface-roughened region at all the corner portions of the plurality of corner portions, all the corner portions become starting points of peeling, and thus peeling of the glass substrate can be started smoothly.

Effects of the invention

As described above, according to the present invention, a glass substrate having a surface roughness distribution of the back surface suitable for an actual peeling operation can be obtained at low cost.

Drawings

Fig. 1 is a plan view of a glass substrate according to a first embodiment of the present invention.

Fig. 2 is a graph schematically depicting a surface roughness distribution in the second main surface of the glass substrate shown in fig. 1.

Fig. 3 is a view for explaining an example of the method for manufacturing the glass substrate shown in fig. 1, and is a schematic front view of a step of performing surface treatment on the second main surface of the glass substrate.

Fig. 4 is a graph schematically depicting the surface roughness distribution in the second main surface of the glass substrate of the second embodiment of the present invention.

Fig. 5 is a view for explaining an example of the method for manufacturing the glass substrate shown in fig. 4, and is a schematic side view in a direction orthogonal to the conveying direction of the step of performing surface treatment on the second main surface of the glass substrate.

Fig. 6 is a graph schematically depicting the surface roughness distribution in the second main surface of the glass substrate of the third embodiment of the present invention.

Fig. 7 is a flowchart for explaining an example of the method for manufacturing the glass substrate shown in fig. 6.

Fig. 8 is a graph schematically depicting the surface roughness distribution in the second main surface of the glass substrate of the fourth embodiment of the present invention.

Fig. 9 is a flowchart for explaining an example of the method for manufacturing the glass substrate shown in fig. 8.

Detailed Description

First embodiment of the present invention

A first embodiment of the present invention will be described below with reference to fig. 1 to 3.

As shown in fig. 1, the glass substrate 1 of the present embodiment is formed in a rectangular shape, and is formed of, for example, silicate glass, silica glass, or the like, preferably borosilicate glass, and more preferably alkali-free glass. In this case, as an example of the glass composition of the glass substrate 1, there can be mentioned: contains SiO in mass%₂：50％～70％、Al₂O₃：12％～25％、B₂O₃: 0% -12%, MgO: 0% -8%, CaO: 0% -15%, SrO: 0% -12%, BaO: 0 to 15 percent of glass.

The alkali-free glass as used herein means a glass containing substantially no alkali component (alkali metal oxide), and specifically means a glass containing an alkali component of 3000ppm or less. From the viewpoint of at least preventing or reducing deterioration with age, a glass having an alkali content of 1000ppm or less is preferable, a glass having an alkali content of 500ppm or less is more preferable, and a glass having an alkali content of 300ppm or less is even more preferable.

The thickness of the glass substrate 1 is set to, for example, 700 μm or less, preferably 600 μm or less, more preferably 500 μm or less, and still more preferably 400 μm or less. The reason for this is that: since the smaller the thickness dimension is, the more likely the glass substrate 1 is damaged in the peeling step, the smaller the thickness dimension is, the more effective the effects of the present invention can be enjoyed. The lower limit of the thickness dimension is not particularly limited, but may be set to 1 μm or more, preferably 5 μm or more, in consideration of handling properties after molding (e.g., handling properties at the time of peeling).

The area of the first main surface 2, i.e., the area of the second main surface 3 (both refer to fig. 2) of the glass substrate 1 is set to, for example, 0.09m²Above, it is preferably set to 0.2m²Above, more preferably 0.5m²The above is more preferably set to 1.0m²The above. The reason for this is that there is a tendency that: the larger the area of the second main surface 3, the easier it is to guidePeeling electrification is caused, and the amount of electrification at this time also increases. Therefore, the larger the area of the second main surface 3, the more effectively the effects of the present invention can be enjoyed. The upper limit of the area is not particularly set, but the area of the second main surface 3 is set to 10m, for example, in consideration of the handling property after forming, particularly the handling property at the time of surface treatment and the like²Hereinafter, it is preferably set to 6.5m²The following.

Next, the surface properties, particularly the surface roughness, of the glass substrate 1 will be described.

The surface roughness Ra of the first main surface 2 of the glass substrate 1 is 0.2nm or less. Here, the surface roughness Ra is a surface roughness according to JIS R1683: the arithmetic average roughness 2014 is measured and evaluated by an atomic force microscope (hereinafter, the same shall apply to the present specification).

Fig. 2 shows an example of the distribution of the surface roughness Ra of the second main surface 3 of the glass substrate 1. In fig. 2, the height of the bar graph indicates the magnitude of the surface roughness Ra, and numerals or symbols in parentheses above or on the sides of the bar graph indicate positions on the second main surface 3 of the glass substrate 1 shown in fig. 1, respectively (see fig. 1). As shown in fig. 2, the surface roughness Ra of the second main surface 3 is different in the central region 4 and the outer peripheral region 5. Specifically, as shown in fig. 2, surface roughness Ra of central region 4 of second main surface 3 is 0.3nm or more and 1.0nm or less, whereas surface-roughened region a exhibiting surface roughness Ra of 0.2nm or more larger than surface roughness Ra of central region 4 is provided in outer peripheral region 5 of second main surface 3.

Here, as shown in fig. 1, the central region 4 is a region located at the center (center of gravity) of the second main surface 3 and having a shape in which the outline of the second main surface 3 is reduced by a reduction scale of 0.6 as a boundary. The center of gravity of the second main surface 3 coincides with the center of gravity of a shape in which the outline of the second main surface 3 is reduced at a reduction scale of 0.6. The outer peripheral region 5 is a region of the second main surface 3 other than the central region 4 defined as described above.

In the present specification, the surface roughness Ra of the central region 4 is evaluated as an average value of arithmetic average roughness measured at the central position P0 of the central region 4 and at positions on the boundary 10 between the outer peripheral region 5 and the central region 4 (in the present specification, as shown in fig. 1, the corners P1 to P4 of the boundary 10 and the intermediate positions P5 to P8 of the corners P1 to P4). The surface roughness Ra of the outer peripheral region 5 was measured and evaluated at corner portions P9 to P12 of a shape obtained by moving the side portions 6 to 8 of the second main surface 3 of the glass substrate 1 by 10mm toward the central region side, and at intermediate positions P13 to P16 of the side portions 6 'to 8' of the shape.

The phrase "the surface-roughened region a exhibiting a surface roughness Ra greater than that of the central region 4 by 0.2nm or more is provided in the outer peripheral region 5 of the second main surface 3" means that any one of the values of the arithmetic average roughness at the measurement positions P9 to P16 of the outer peripheral region 5 is greater than the surface roughness Ra of the central region 4 (the average value of P1 to P8) by 0.2nm or more.

In the present embodiment, as shown in fig. 2, the surface-roughened region a extends along one short-side portion 8 of the plurality of side portions 6 to 8 of the second main surface 3. Here, the phrase "the surface-roughened region a extends along one side 8 of the plurality of sides 6 to 8 of the second main surface 3" means that the surface roughness Ra of the measurement positions P9, P11, and P14 of the side 8' which is located 10mm toward the central region 4 side is 0.2nm or more greater than the surface roughness Ra of the central region 4 (average value of P1 to P8).

In the present embodiment, as shown in fig. 2, the surface roughness Ra of the outer peripheral region 5 decreases as it goes away from the one short side portion 8. Therefore, in the outer peripheral region 5, the surface roughness Ra of P10, P12, and P15 is smaller than the surface roughness Ra of the central region 4. That is, a region smaller than the surface roughness Ra of the central region 4 is provided in parallel with the surface-roughened region a via the central region 4.

From the viewpoint of easiness of peeling, the larger the surface roughness Ra of the surface-roughened region a, the better, but if it is too large, the later-described surface treatment requires more time than necessary. In addition, pitch variation is likely to occur in heat treatment in the FPD manufacturing process. From the above viewpoint, the surface roughness Ra of the surface-roughened region a is preferably set to be equal to or less than Ra +0.5nm of the surface roughness Ra of the central region 4, and is preferably set to be equal to or less than Ra +0.3nm of the surface roughness Ra of the central region 4.

The glass substrate 1 having the above-described configuration is obtained by: for example, a glass substrate formed into a belt shape by a known forming method typified by various down-draw methods is cut into a predetermined size in a longitudinal direction, both end portions in a width direction of the glass substrate obtained by cutting are further cut, and then, grinding, polishing, and the like are performed on each cut surface as necessary. As various down-draw methods, an overflow down-draw method is mentioned as a suitable example. According to the overflow down-draw method, the first main surface 2 of the glass substrate becomes a forged surface, and the surface roughness Ra thereof can be easily made 0.2nm or less.

The distribution of the surface roughness Ra of the second main surface 3, which is the back surface of the glass substrate 1, can be obtained, for example, by providing a surface treatment step described below after the end surface processing step.

Fig. 3 shows a surface treatment process 20 for imparting the distribution of the surface roughness Ra shown in fig. 2 to the second main surface 3. The surface treatment process 20 includes: a conveying device 21 for conveying the glass substrate 1 in a predetermined direction X1; a surface treatment device 22 that performs a predetermined surface treatment on the second main surface 3 (the lower surface in fig. 3) of the glass substrate 1 conveyed by the conveyor 21; and a processing chamber 23 for accommodating the conveying device 21 and the surface treatment device 22.

The conveying device 21 includes, for example, a plurality of pairs of rollers 24, and can convey the glass substrate 1 positioned on the rollers 24 in a predetermined direction X1 by rotationally driving at least a part of the plurality of pairs of rollers 24. When there are remaining rollers 24 that are not rotationally driven, these remaining rollers 24 are so-called free rollers. In fig. 3, the pairs of rollers 24 are disposed before and after the conveyance direction X1 of the surface treatment apparatus 22, and may be disposed on the insertion path 25 of the surface treatment apparatus 22 as needed.

The surface treatment apparatus 22 is an apparatus for supplying a treatment gas G to the second main surface 3 of the glass substrate 1 to perform a predetermined surface treatment, and includes: an insertion path 25 through which the glass substrate 1 to be processed is inserted; one or more air supply ports 26 opening in the insertion passage 25; one or more exhaust ports 27 that open in the insertion passage 25 at a position different from the air supply port 26; a process gas generator 28 for generating a process gas G; and an exhaust gas treatment device 29 for rendering the used treatment gas G harmless. The process gas generator 28 is connected to the gas supply port 26 via a gas supply line 30, and the exhaust gas processor 29 is connected to the exhaust port 27 via an exhaust line 31.

The type and composition of the processing gas G are arbitrary as long as a predetermined surface treatment (roughening by etching) can be performed on the glass substrate 1, and an acid gas such as hydrogen fluoride gas or a gas containing a part of such a gas can be used, for example.

In the surface treatment step 20 having the above-described configuration, the treatment gas G generated by the treatment gas generation device 28 is introduced into the air supply line 30 and is discharged from the air supply port 26 located at the downstream end of the air supply line 30. When the glass substrate 1 (indicated by a two-dot chain line in fig. 3) shown in fig. 1 is inserted into the insertion passage 25 facing the gas supply port 26, the processing gas G discharged from the gas supply port 26 comes into contact with the second main surface 3 of the glass substrate 1, and a predetermined surface treatment is performed on the second main surface 3. Thereby, the second main surface 3 of the glass substrate 1 is corroded and roughened.

At this time, by appropriately setting the surface treatment conditions, the distribution of the surface roughness Ra shown in fig. 2 can be imparted to the second main surface 3. Specifically, the glass substrate 1 is conveyed in a horizontal posture with the longitudinal direction of the

long side portions

6 and 7 of the glass substrate 1 aligned with the conveyance direction X1 (see fig. 3). Thereby, the glass substrate 1 is introduced into the through-passage 25 with the short side portion 8 side (fig. 1) as the tip. Further, control is performed such that the conveyance speed of the glass substrate 1 is gradually increased or the flow rate of the processing gas G supplied to the second main surface 3 in the insertion passage 25 is gradually decreased as the introduction of the glass substrate 1 into the insertion passage 25 is started. By setting various surface treatment conditions in this manner, a distribution of the surface roughness Ra in which the surface-roughened region a extends along one short-side portion 8 (fig. 1) and the surface roughness Ra of the outer peripheral region 5 decreases with distance from the one short-side portion 8 can be given to the second main surface 3.

The process gas G supplied to the glass substrate 1 is introduced into the exhaust line 31 through the exhaust ports 27 (two in the present embodiment) facing the insertion path 25, and is introduced into the exhaust processing device 29 located on the downstream side of the exhaust line 31. The introduced process gas G is discharged to the outside of the system in a state where harmful substances are removed by the exhaust gas treatment device 29.

As described above, in the glass substrate 1 of the present invention, the surface roughness Ra of the first main surface 2 is set to be large enough (0.2nm or less) to enable various elements, electrode lines, electronic circuits, and the like to be formed with high accuracy, the surface roughness Ra of the central region 4 of the second main surface 3 is set to be 0.3nm or more and 1.0nm or less on the second main surface 3, and the surface-roughened region a exhibiting a surface roughness Ra of 0.2nm or more larger than the surface roughness Ra of the central region 4 is provided in the outer peripheral region 5 of the second main surface 3. This makes the surface-roughened region a located in the outer peripheral region 5 a starting point for peeling, and peeling can be started smoothly. This reduces cracking of the glass substrate 1, and enables safe peeling of the glass substrate 1. In addition, the problem that the glass substrate 1 is not peeled off from the mounting table due to the glass substrate 1 being in close contact with the mounting table can be reduced. Further, since only the glass substrate 1 in which the surface roughness Ra of the one or more surface-roughened regions a included in the outer peripheral region 5 exhibits a value equal to or greater than a predetermined value (a value greater than the surface roughness Ra of the central region 4 by 0.2nm or greater) can be used, the surface treatment for roughening, for example, the surface treatment with the treatment gas G shown in fig. 3, can be suppressed to a minimum region and amount. Thus, the roughening treatment can be performed efficiently and at low cost.

In the present embodiment, the distribution of the surface roughness Ra in which the surface-roughened region a extends along the side portion 8 and the surface roughness Ra of the outer peripheral region 5 decreases as it moves away from the side portion 8 is provided in the second main surface 3. By providing a predetermined deviation along the

long side portions

6 and 7 in the distribution of the surface roughness Ra in this manner, the glass substrate 1 can be intentionally made to be easily peeled off (in this case, in the direction along the long side portions 6 and 7). Therefore, the glass substrate 1 can be easily and safely peeled off by peeling smoothly from the short side portion 8 in the surface-roughened region a serving as a starting point along the

long side portions

6 and 7.

The first embodiment of the present invention has been described above, but the glass substrate of the present invention is not limited to the above-described embodiment, and various forms can be adopted within the scope of the present invention.

Second embodiment of the present invention

Fig. 4 shows an example of the distribution of the surface roughness Ra of the second main surface 3 of the glass substrate 1 according to the second embodiment of the present invention. In fig. 4, the height of the bar graph indicates the magnitude of the surface roughness Ra, and numerals or symbols in parentheses above or on the sides of the bar graph indicate positions on the second main surface 3 of the glass substrate 1 shown in fig. 1, respectively. As shown in fig. 4, in the present embodiment, in outer peripheral region 5 of second main surface 3, surface-roughened region a exhibiting surface roughness Ra greater than that of central region 4 by 0.2nm or more is also provided.

In addition to the above configuration, the present embodiment shows a distribution of the surface roughness Ra in which the surface roughened region a extends along the long side portion 7 and the surface roughness Ra of the outer peripheral region 5 decreases as it goes away from the long side portion 7. That is, the direction in which the surface-roughened region a extends and the direction in which the surface roughness Ra of the outer circumferential region 5 changes are different from those of the first embodiment.

The distribution of the surface roughness Ra of the second main surface 3 as shown in fig. 4 can be obtained, for example, by providing a surface treatment process described below after the end face machining process.

Fig. 5 shows a surface treatment process 40 for imparting the distribution of the surface roughness Ra shown in fig. 4 to the second main surface 3. As in fig. 3, the surface treatment process 40 includes: a conveying device 41 for conveying the glass substrate 1 in a predetermined direction X1; a surface treatment device 42; and a processing chamber 43 for accommodating the conveying device 41 and the surface treatment device 42.

The conveyor 41 has a pair of

rollers

44 and 45. The axes of rotation of the pair of

rollers

44, 45 are inclined with respect to the horizontal. Thus, the glass substrate 1 can be conveyed in the predetermined direction X1 in a state where the glass substrate 1 is tilted so that the long side portion 7 side is located lower than the long side portion 6 side.

In this case, the insertion path 46 of the surface treatment apparatus 42 is inclined in such a manner that the glass substrate 1 can be inserted into the insertion path 46 in an inclined state along the

short side portions

8 and 9, and that the first roller 44 side is positioned lower than the second roller 45 side. The other components are the same as those of the surface treatment device 22 shown in fig. 3, and thus detailed description is omitted.

In the surface treatment step 40 having the above-described configuration, the treatment gas G generated by the treatment gas generation device 28 (fig. 3) is introduced into the gas supply line 30 (fig. 3) and is discharged from the gas supply port 47 (fig. 5) located at the downstream end of the gas supply line 30. When the glass substrate 1 (indicated by a two-dot chain line in fig. 5) shown in fig. 1 is inserted through the insertion passage 46 facing the gas supply port 47, the process gas G discharged from the gas supply port 47 is supplied to the second main surface 3 of the glass substrate 1, and a predetermined surface treatment is performed on the second main surface 3. Thereby, the second main surface 3 of the glass substrate 1 is etched and roughened.

At this time, by appropriately setting the surface treatment conditions, the distribution of the surface roughness Ra shown in fig. 4 can be imparted to the second main surface 3. Specifically, the process gas G is supplied to the second main surface 3 (fig. 5) while the glass substrate 1 is conveyed in a state in which the longitudinal direction of the

long side portions

6 and 7 of the glass substrate 1 is aligned with the conveyance direction X1 (see fig. 3) and the long side portion 7 side is positioned lower than the long side portion 6 side. By setting the main surface treatment conditions in this manner, the degree of roughening becomes relatively higher in the region located below the second main surface 3, and the degree of roughening becomes relatively lower in the region located above the second main surface 3. Thus, in the glass substrate 1 obtained through the surface treatment step 40, as shown in fig. 4, the distribution of the surface roughness Ra in which the surface roughened region a extends along the long side portion 7 and the surface roughness Ra of the outer peripheral region 5 decreases as it goes away from the long side portion 7 can be given to the second main surface 3.

As described above, in the present embodiment, the distribution of the surface roughness Ra in which the surface-roughened region a extends along the long side portion 7 and the surface roughness Ra of the outer peripheral region 5 decreases as it goes away from the long side portion 7 is provided in the second main surface 3. By providing a predetermined deviation along the

short side portions

8 and 9 in the distribution of the surface roughness Ra in this way, the direction in which the glass substrate 1 is easily peeled off (here, the direction along the short side portions 8 and 9) can be made different from that of the first embodiment. Therefore, the glass substrate 1 can be easily and safely peeled off by easily peeling off the long side portion 7 from the surface-roughened region a serving as a starting point along the

short side portions

8 and 9.

Third embodiment of the present invention

Fig. 6 shows an example of the distribution of the surface roughness Ra of the second main surface 3 of the glass substrate 1 according to the third embodiment of the present invention. In fig. 6, the height of the bar graph indicates the magnitude of the surface roughness Ra, and numerals or symbols in parentheses above or on the sides of the bar graph indicate positions on the second main surface 3 of the glass substrate 1 shown in fig. 1, respectively. As shown in fig. 6, in the present embodiment, in outer peripheral region 5 of second main surface 3, surface-roughened region a exhibiting surface roughness Ra greater than that of central region 4 by 0.2nm or more is also provided.

In addition, in the present embodiment, the surface-roughened region a is provided at one of the four corners defining the second main surface 3. The phrase "the surface-roughened regions a are provided at the corners" means that, in the shapes 6 'to 9' formed by moving the sides 6 to 9 by 10mm toward the central region, any of the surface roughnesses Ra of the measurement positions P9 to P12 located at the apexes is larger than the surface roughness Ra of the central region 4 by 0.2nm or more (see fig. 1). In the glass substrate 1 shown in fig. 6, the surface-roughened region a is provided at the lower left corner (measurement position P11).

With respect to the distribution of the surface roughness Ra of the second main surface 3 as shown in fig. 6, it can be obtained by, for example, subjecting the glass substrate 1 to various treatments according to the flow shown in fig. 7.

Specifically, as shown in fig. 7, first, the glass substrate 1 is subjected to a surface treatment with the treatment gas G in the surface treatment step 20 shown in fig. 3, thereby roughening the entire second main surface 3 (first roughening step S1). Then, masking is performed on a region other than a predetermined corner portion (here, a corner portion including the position P11 shown in fig. 1) in the second main surface 3 of the glass substrate 1 (masking step S2). Then, the surface treatment of the surface treatment process 20 shown in fig. 3 is performed again on the glass substrate 1 in the masked state, whereby only the prescribed corner portions which are not masked are roughened again (second roughening process S3). Thus, the distribution of the surface roughness Ra provided in a predetermined one of the four corners (including the corner at the position P11) defining the second main surface 3 can be given to the second main surface 3 by the surface-roughened region a.

As described above, in the present embodiment, since the surface-roughened region a is provided in at least one of the four corners of the second main surface 3, the corner P11 located in the surface-roughened region a serves as a starting point of peeling. Therefore, the peeling of the glass substrate 1 can be smoothly started.

Fourth embodiment of the present invention

Fig. 8 shows an example of the distribution of the surface roughness Ra of the second main surface 3 of the glass substrate 1 according to the fourth embodiment of the present invention. In fig. 8, the height of the bar graph indicates the magnitude of the surface roughness Ra, and numerals or symbols in parentheses above or on the sides of the bar graph indicate positions on the second main surface 3 of the glass substrate 1 shown in fig. 1, respectively. As shown in fig. 8, in the present embodiment, in outer peripheral region 5 of second main surface 3, surface-roughened region a exhibiting surface roughness Ra greater than that of central region 4 by 0.2nm or more is also provided.

In addition, in the present embodiment, the surface-roughened regions a are provided at all four corners defining the second main surface 3. In the glass substrate 1 shown in fig. 8, the surface roughness Ra of each of the measurement positions P9 to P12 is larger than the surface roughness Ra of the central region 4 by 0.2nm or more, and the surface-roughened regions a are provided at all four corner portions (fig. 8).

With respect to the distribution of the surface roughness Ra of the second main surface 3 as shown in fig. 8, it can be obtained by, for example, subjecting the glass substrate 1 to various treatments according to the flow shown in fig. 9.

Specifically, as shown in fig. 9, first, in the surface treatment step 20 shown in fig. 3, the glass substrate 1 is subjected to a surface treatment with the treatment gas G, thereby roughening is performed over the entire area of the second main surface 3 (first roughening step S4). Then, masking is performed on the region other than all of the four corners (here, the corners including the positions P9 to P12 shown in fig. 1) among the second main surface 3 of the glass substrate 1 (masking process S5). Then, the surface treatment of the surface treatment process 20 shown in fig. 3 is performed again on the glass substrate 1 in the masked state, whereby only all four corner portions which are not masked are roughened again (second roughening process S3). Thereby, the distribution of the surface roughness Ra of all the four corner portions defining the second main surface 3 can be given to the surface-roughened region a on the second main surface 3.

As described above, in the present embodiment, since the surface-roughened region a is provided at all four corners of the second main surface 3, all the corners P9 to P12 located in the surface-roughened region a serve as starting points of peeling, and peeling can be smoothly started.

In the third embodiment, the case where the surface-roughened region a is provided at a predetermined one corner portion is exemplified, and in the fourth embodiment, the case where the surface-roughened regions a are provided at all four corner portions is exemplified, but it is needless to say that the distribution of the surface roughness Ra of the second main surface 3 where the surface-roughened regions a are provided at two or three corner portions may be given.

In the third and fourth embodiments, the surface roughness Ra of the region other than the corner portion in the outer peripheral region 5 is arbitrary, and therefore, for example, a distribution in which all or a part of the surface roughness Ra at the positions P13 to P16 shown in fig. 1 is larger than the surface roughness Ra of the central region 4 by 0.2nm or more may be adopted. If the outer peripheral edge of the peripheral region 5, that is, all the regions of the outer peripheral edge of the second main surface 3 are the surface-roughened regions a, peeling can be started more smoothly.

In the first embodiment, the distribution of the surface roughness Ra shown in fig. 2 is given to the second main surface 3 by adjusting the conveyance speed of the glass substrate 1 or the supply flow rate of the processing gas G, and in the second embodiment, the distribution of the surface roughness Ra shown in fig. 4 is given to the second main surface 3 by performing the surface treatment while conveying the glass substrate 1 in a state of being inclined in a predetermined direction, but these distributions may be formed by other methods. That is, although not shown in the drawings, the distribution of the surface roughness Ra shown in fig. 4 may be given to the second main surface 3 by appropriately setting the conveyance speed or the supply flow rate of the process gas G as in the first embodiment while conveying the glass substrate 1 in the horizontal posture in a state where the longitudinal direction of the

short side portions

8 and 9 coincides with the conveyance direction X1. Alternatively, although not shown in the drawings, the distribution of the surface roughness Ra shown in fig. 2 may be given to the second main surface 3 by supplying the process gas G to the second main surface 3 while conveying the glass substrate 1 in a state in which the longitudinal direction of the

short side portions

8 and 9 is aligned with the conveying direction X1 and the short side portion 8 side is positioned lower than the short side portion 9 side so as to be inclined.

Alternatively, the distribution of the surface roughness Ra in the first and second embodiments may be formed by a method other than the above method. For example, although not shown, a cleaning step of cleaning the glass substrate 1 with water or the like is provided as a step prior to the surface treatment steps 20 and 40, and a state is provided in which a predetermined deviation is provided for the moisture adhering to the second main surface 3 at the time of cleaning. At this time, for example, the distribution of the surface roughness Ra shown in fig. 2 can be given to the second main surface 3 by performing the surface treatment shown in fig. 3 after the adhesion state of the moisture is biased so that the more the short side portion 8 side adheres the more the moisture is and the less the short side portion 9 side adheres the less the moisture is. Alternatively, the distribution of the surface roughness Ra shown in fig. 4 can be given to the second main surface 3 by performing the surface treatment shown in fig. 3 after the adhesion state of the moisture is biased so that the more the long side portion 7 side, the more the moisture adheres, and the less the moisture adheres, the more the long side portion 6 side, the more the moisture adheres. In this case, it is estimated that the degree of surface treatment (roughening) by the treatment gas G varies depending on the degree of adhesion of moisture. Therefore, when the surface treatment is performed on the glass substrate 1 in a state where the above-described deviation is provided with respect to the adhesion state of moisture, there is no need to change the conveyance speed, the supply flow rate of the processing gas G, or the conveyance posture of the glass substrate 1. That is, even in the case where the glass substrate 1 is conveyed in a horizontal posture with a fixed conveyance speed or a fixed supply flow rate of the process gas G, the distribution of the surface roughness Ra shown in fig. 2 or 4 can be given. Of course, if the pre-cleaning is not necessary, a step of supplying moisture in, for example, a mist state may be provided before the surface treatment steps 20 and 40 only to provide the above-described deviation of the adhesion state of moisture on the second main surface 3.

Of course, as long as the surface roughness Ra of the central region 4 of the second main surface 3 is 0.3nm or more and 1.0nm or less and the surface-roughened region a exhibiting a surface roughness Ra of 0.2nm or more larger than the surface roughness Ra of the central region 4 is provided in the peripheral region 5, means for imparting the distribution of the surface roughness Ra to the second main surface 3 is arbitrary.

Although not shown in the drawings, the glass substrate 1 of the first to fourth embodiments may be configured such that the glass substrate 1 is peeled off from the mounting table by lifting pins provided at a plurality of positions on the mounting table when the FPD is manufactured. In this case, even if the plurality of pins are raised at the same time, the surface-roughened region a located in the outer peripheral region 5 becomes a starting point and peeling can be started smoothly, but it is preferable to raise the pins located in the surface-roughened region a first among the plurality of pins. If the pins located in the surface-roughened region a or the periphery thereof are raised first, the surface-roughened region a becomes a starting point more reliably, and thus peeling can be started more smoothly. Further, it is preferable to raise the pin in order of the distance from the surface-roughened region a as a starting point. When the pins are raised in the order of close distance from the surface-roughened region a as the starting point, peeling from the starting point can be more smoothly performed.

Examples

As an example of the present invention, 1000 glass substrates were manufactured, the glass substrates were alkali-free glass substrates for a display manufactured by japan electric glass company, inc (product name: OA-11), the size of the glass substrates was 2200mm × 2500mm, the thickness was 50 μm, the forming method was an overflow down-draw method, and the second main surface of the glass substrates was subjected to a surface treatment using the surface treatment process shown in fig. 5.

One glass substrate was selected from the produced glass substrates, and the surface roughness Ra of the second main surface was measured by a measuring apparatus (model: Dimension ICON, manufactured by Bruker). As a result, the surface roughness Ra of the central region (average value of P0 to P8) was 0.4 nm. The surface roughness Ra of the outer peripheral region was 0.3nm at P9, 0.3nm at P10, 0.6nm at P11, 0.6nm at P12, 0.3nm at P13, 0.4nm at P14, 0.4nm at P15, and 0.6nm at P16. Therefore, as shown in fig. 4, the second main surface 3 of the glass substrate is provided with a distribution of surface roughness Ra in which the surface roughened region a extends along the long side portion 7 and the surface roughness Ra of the outer peripheral region 5 decreases as it goes away from the long side portion 7. The obtained glass substrate was subjected to a peeling test. In the peeling test, after the glass substrate is placed on the mounting table, the plurality of pins provided in the mounting table are simultaneously raised, thereby peeling the glass substrate from the mounting table.

In comparative example, a glass substrate was produced under the same conditions as in example except that the second main surface of the glass substrate was subjected to surface treatment in a horizontal posture. As a result, the surface roughness Ra of the central region (average value of P0 to P8) was 0.4 nm. The surface roughness Ra of the outer peripheral regions (P9-P16) is 0.3-0.5 nm. Therefore, the surface-roughened region a is not formed in the second main surface of the glass substrate. The glass substrate was subjected to a peeling test.

In the peeling test of the comparative example, 50 glass substrates out of 1000 glass substrates were not peeled off from the mounting table even when the pins were raised. In contrast, in the peeling test of the example, all 1000 glass substrates were peeled off from the mounting table with the rise of the pins. That is, the problem that the glass substrate is not peeled off from the mounting table can be suppressed. From this, it was confirmed that according to the glass substrate of the present invention, the surface-roughened region a located in the outer peripheral region can be used as a starting point, and peeling can be smoothly started.

Claims

1. A glass substrate having a first main surface and a second main surface,

the first main surface has a surface roughness Ra of 0.2nm or less,

a surface roughness Ra of a central region of the second main surface is 0.3nm or more and 1.0nm or less,

in an outer peripheral region of the second main surface, a surface-roughened region exhibiting a surface roughness Ra greater than that of the central region by 0.2nm or more is provided.

2. The glass substrate according to claim 1, wherein the surface-roughened region extends along any one of the plurality of edges of the second main surface, and the outer peripheral region has a surface roughness Ra that decreases with distance from the one edge.

3. The glass substrate according to claim 1, wherein the surface-roughened region is provided at least one corner of the plurality of corners of the second main surface.

4. The glass substrate of claim 3, wherein the surface-roughened area is disposed at all corners of the plurality of corners.