JP5623001B2 - Glass substrate - Google Patents

Description

  The present invention relates to a glass substrate used for a flat display panel, and in particular, the longitudinal dimension is 300 mm or more and the lateral dimension is 300 mm or more, and the average value of the plate thickness is in the range of 0.3 to 4.0 mm. It relates to the thickness characteristics or surface flatness of the glass substrate inside.

  As is well known, a plasma display panel {PDP}, a field emission display panel {FED [including surface emission display (SED): the same applies hereinafter]}, a liquid crystal display {LCD}, an electroluminescence display {ELD}, etc. A flat display panel is manufactured by facing two glass substrates on the surface of which elements or structures such as fine electrodes and partition walls are formed.

  This type of glass substrate is a large original glass substrate formed by a known method typified by a float method, a fusion method (overflow down draw method), or a slot down draw method, and has a rectangular shape with four sides. It is obtained by cutting as follows. Among these forming methods, for example, the float method has an advantage that a large-sized glass substrate can be stably mass-produced at a low cost, and thus is frequently used as a method for producing a glass substrate for PDP or LCD. Has reached.

  Specifically, this float method supplies molten glass melted in a melting furnace to a float bath in which molten tin is stored, floats the molten glass on the molten tin in the float bath, and naturally spreads the molten glass. The large original glass substrate is obtained through a belt-like glass ribbon by being drawn out to a layer (conveying path) arranged on the downstream side of the float bath.

  And, for the glass substrate for the flat display panel obtained by cutting four sides of such a large original glass substrate, various films are uniformly applied to the surface, and then a photo process method It is customary to form an element or a structure on the glass substrate by exposing and developing using the above. Therefore, a high flatness is required for the surface on which elements and the like are formed in this type of glass substrate, and the characteristic of the thickness of the glass substrate is an important factor in order to satisfy the requirement.

  According to Patent Document 1, the short side dimension is 300 to 3000 mm, the long side dimension is 300 to 3000 mm, and the average plate thickness is based on the thickness characteristics of the glass substrate for such a flat display panel. For a glass substrate having a thickness of 1.5 to 3.0 mm, the difference between the maximum thickness and the minimum thickness is set to 20 μm or less, and the maximum thickness and the minimum in the thickness measurement range over a length of 100 mm. It is disclosed that the difference in plate thickness from the plate thickness is 10 μm or less (further 5 μm or less).

JP 2004-87382 A

  By the way, as described in paragraph [0024] and FIG. 1 of the above document, the glass substrate disclosed in the above-mentioned Patent Document 1 scans over the entire width in the direction along one side with a laser thickness gauge. Thus, the maximum and minimum plate thickness differences between the entire width of the glass substrate and 100 mm units are obtained. That is, the glass substrate disclosed in the same document obtains the maximum and minimum difference in plate thickness only in a cross section having a single directionality, and the minimum unit of the plate thickness measurement range is 100 mm. ing.

  In this way, in the method of obtaining the plate thickness difference only with a cross section having a single directionality, the plate thickness difference in two dimensions (both the X coordinate and the Y coordinate orthogonal to this) in the plane of the glass substrate is calculated. For example, the plate thickness difference in the X direction can be determined from an arbitrary point in the plane, but the plate thickness difference in the Y direction cannot be determined. Therefore, even if it is determined that the plate is a good part because the maximum value of the plate thickness difference in the measurement unit in the X direction is within the allowable range with respect to an arbitrary point in the plane, the plate in the measurement unit in the Y direction. If the thickness difference deviates from the permissible range, the judgment that it is a good quality part is wrong. Note that even if the thickness difference is obtained by a cross section having two directions, if the thickness difference is individually obtained by a separate cross section, the difference between the surroundings based on an arbitrary point It is impossible to grasp the maximum value of the plate thickness difference at this point, and therefore it is not possible to recognize the original unjustified plate thickness change occurring locally. In addition, as disclosed in the same publication, if the minimum unit of the thickness measurement range is 100 mm, an undue change in thickness that is locally caused by the minimum unit being too large can be accurately recognized. In addition, it is possible to overlook a place where such an inappropriate thickness change exists.

  As described above, if the plate thickness difference with respect to the surroundings can not be accurately grasped based on an arbitrary point in the plane of the glass substrate, exposure in the photo process for forming the above-described elements and structures on the glass substrate It is difficult to accurately perform the above. That is, in the case of exposure / development by this photo process, there are many requests that an exposure machine that requires exposure with a shallow depth of focus must be used because the elements to be formed are fine. In particular, in such a case, simply by measuring the plate thickness difference at the cross section having one direction as described above, and by measuring the plate thickness difference with the minimum unit of the plate thickness measurement range being 100 mm, From the standpoint of optimizing the focal length of the exposure device with respect to the surface of the glass substrate, that is, suppressing exposure deviation, it is difficult or impossible for the flatness of the surface of the glass substrate to have a high degree of precision to meet it.

  In view of the above circumstances, the present invention is difficult in the past by making the directionality for measuring the thickness difference from an arbitrary point of the glass substrate and by optimizing the minimum unit of the thickness measurement range. Alternatively, it is a technical problem to provide a glass substrate having flatness that can be sufficiently dealt with even for applications that have been impossible.

The present invention, which was created to solve the above technical problems, has a longitudinal dimension of 300 mm or more and a transverse dimension of 300 mm or more, and an average value of the plate thickness is 0.3 to 4.0 mm. In the glass substrate manufactured by the float method in the range, when any position in the plane is a reference point and the directions along two orthogonal sides are the X direction and the Y direction, A point and B point 20 mm apart on both sides, C point and D point 20 mm apart on both sides in the Y direction from the reference point, and 20 mm respectively on both sides in the X direction from the reference point and from the reference point The absolute value of the difference between the total thickness of E point, F point, G point and H point, 20 mm apart on both sides in the Y direction, and the thickness of the reference point was 3 μm or less. Characterized in that the exposed and developed by film is formed on the surface and photo-processes are those elements or structure is formed. Examples of the glass substrate include glass substrates for flat display panels such as PDP, FED, LCD, or ELD. In the following, “everything” is referred to as “arbitrary”.

  According to such a configuration, the thickness of each point separated by a unit length in eight directions at intervals of 45 ° around the arbitrary position in the plane of the glass substrate, and the plate of the reference point Since the absolute value of the difference from the thickness is set to 3 μm or less, is there an undue thickness change in the local area of the glass substrate compared to the case where the thickness difference is obtained only in one direction? No is reliably detected without being overlooked. Moreover, the separation length from the reference point to the eight surrounding points is 20 mm for the points A, B, C, and D, and for the points E, F, G, and H, √ Since both are 2 × 20 mm and are appropriately shortened, an undue thickness change that can locally occur on the glass substrate is precisely detected. In other words, the detection of the plate thickness difference in the entire area of the glass substrate is performed for each area composed of four elements with 20 × 20 mm (20 mm square) as one element. As described above, since the plate thickness difference (absolute value) with respect to eight points that are equiangularly spaced from an arbitrary reference point and separated by a reasonable short distance in the eight surrounding directions is 3 μm or less, the surface of the glass substrate is highly advanced. For example, it is difficult or impossible in the past, and it can be used for various purposes as represented by, for example, a countermeasure for suppressing exposure deviation in the photo process for the surface of the glass substrate described later. It becomes possible. That is, when the difference in thickness (absolute value) with respect to the above eight points exceeds 3 μm, there is a portion where an inappropriate thickness change occurs in the glass substrate. The use of the glass substrate is limited by causing trouble when performing the forming process or the like, but if it is 3 μm or less, such a problem can be avoided.

  In this case, the average value of the plate thickness in the glass substrate may be in the range of 1.3 to 4.0 mm.

  If it does in this way, the effect similar to the above-mentioned matter can be obtained precisely about the glass substrate for flat display panels illustrated above except LCD.

In the present invention, as described above, the glass substrate in which the absolute value of the difference between the thickness of each of the total eight points and the thickness of the reference point is 3 μm or less has a film formed on the surface thereof. is it and what exposure by a photo process developed by element or structure is formed.

  In this way, since the plate thickness difference (absolute value) with respect to the eight directions around the arbitrary position in the plane of the glass substrate is 3 μm or less, the element or the structure is placed on the glass substrate. It is possible to accurately perform exposure in the photo process for forming. That is, in the case of exposure / development by this photo process, an exposure machine that requires exposure with a shallow depth of focus may be inevitably used because of the fine elements to be formed. In particular, in such a case, measurement of a plate thickness difference having eight directions from any reference point, and measurement of a plate thickness difference in which the minimum unit of the plate thickness measurement range is 20 mm (or √2 × 20 mm). Since the measurement result is 3 μm or less, the flatness of the surface of the glass substrate is commensurate with the optimization of the focal length of the exposure device with respect to the surface of the glass substrate, that is, the suppression of exposure deviation. It will have sufficient altitude.

As described above , the glass substrate having the above configuration is manufactured by the float process.

  According to this float method, since the molten glass floats on the molten tin of the float bath, the molten glass naturally naturally has an advantage that a glass ribbon having a stable thickness can be obtained. Thus, it is extremely advantageous to obtain a glass substrate having a good plate thickness characteristic.

  In addition, the glass substrate having the above configuration can be used for a plasma display, a field emission display, or a liquid crystal display to maximize its effects, and a flat display panel can be manufactured using this glass substrate. If so, a panel with excellent quality can be obtained.

  As described above, according to the present invention, as the plate thickness characteristic of the glass substrate, there is a plate thickness difference (absolute value) with respect to each point separated by a short distance in the surrounding eight directions at an equal angle from an arbitrary reference point in the plane. Since it is 3 μm or less, the surface of the glass substrate has a high degree of flatness, which is representative of measures to prevent exposure deviation in the photo process on the surface of the glass substrate, which has been difficult or impossible in the past. As described above, it is possible to cope with various applications.

  Hereinafter, a glass substrate according to an embodiment of the present invention will be described with reference to the drawings. The glass substrate is used for PDP, FED, LCD, or ELD.

As shown in FIG. 1, a glass substrate 1 according to an embodiment of the present invention is manufactured by a float process, and has a longitudinal dimension a of 300 mm or more (specifically, 400 mm) and a lateral direction. The dimension b is 300 mm or more (specifically, 500 mm), and the average value of the plate thickness is in the range of 0.3 to 4.0 mm (preferably 1.3 to 4.0 mm).

  The feature of the glass substrate 1 is that an arbitrary position in the plane is a reference point O and the directions along the two orthogonal sides 2 and 3 are the X direction and the Y direction, respectively. A point and B point 20 mm apart on both sides, C point and D point 20 mm apart on both sides in the Y direction from the reference point O, and 20 mm respectively on both sides in the X direction from the reference point O and from the reference point O The absolute value of the difference between the thickness of each of the eight points, E point, F point, G point, and H point, which are 20 mm apart on both sides in the Y direction, and the reference point O is 3 μm or less. There is.

  Specifically, the difference between the thickness of the reference point O and the thickness of the A point, the difference between the thickness of the reference point O and the thickness of the B point, the thickness of the reference point O and the thickness of the C point. The difference between the thickness of the reference point O and the thickness of the D point, the difference between the thickness of the reference point O and the thickness of the D point, the thickness of the reference point O and the thickness of the E point The difference between the thickness of the reference point O and the thickness of the F point, the difference between the thickness of the reference point O and the thickness of the G point, the difference between the thickness of the reference point O and the thickness of the H point, That is, the absolute values of these eight differences are all 3 μm or less.

  The distances from the reference point O to the points A, B, C, and D are all 20 mm, and from the reference point O, points E, F, G, and H. The separation lengths up to are all √2 × 20 mm. Further, the eight points above the reference point O are arranged at an equal angle of 45 °.

  Therefore, 20 × 20 mm (20 mm square) in this glass substrate 1 is taken as one element, and a group of four parts consisting of four elements is regarded as one plate thickness high quality area. And even if the reference point O is set at any position on the glass substrate 1, the reference point O and the points A to H satisfy the above relationship.

  The surface of the glass substrate 1 is a surface on which a film is formed and exposed or developed by a photo process to form an element or a structure. The surface of the glass substrate 1 is a flat surface that does not cause exposure misalignment even when the element to be formed is fine and exposure with a shallow depth of focus is required.

  According to the glass substrate 1 having such a plate thickness characteristic, the plate thickness of each point separated by a unit length in eight directions at intervals of 45 ° around the arbitrary position in the plane as a reference point O. Since the absolute value of the difference between the thickness of the reference point O and the thickness of the reference point O is 3 μm or less, there is no undue change in thickness in the local area of the glass substrate 1. The increase in the number of inspections ensures that the inspection is performed without being overlooked. Moreover, the separation length from the reference point O to the eight surrounding points is 20 mm for the points A, B, C and D, and for the points E, F, G and H, Since √2 × 20 mm, both of which are appropriately shortened, an undue thickness change that may occur locally on the glass substrate 1 is closely inspected. Therefore, the surface of the glass substrate 1 has a high degree of flatness, and the occurrence of an exposure shift in the photo process with respect to the surface of the glass substrate 1 is suppressed.

  As Examples 1 to 5 of the present invention, a glass substrate for a PDP having a vertical dimension of 400 mm and a horizontal dimension of 500 mm and a plate thickness (average thickness) of 1.8 mm is obtained by a float method. Made using. The glass material is PP-8C manufactured by Nippon Electric Glass Co., Ltd. In forming these glass substrates according to Examples 1 to 5 by the float method, {firstly, the temperature distribution in the glass flow direction in the float bath, and secondly, in the direction orthogonal to the glass flow direction in the float bath. Temperature distribution, third, temperature of the molten glass dough flowing into the float bath, fourth, temperature distribution in the width direction in the layer (conveying path) immediately downstream of the float bath, fifth, transport of the layer Regarding the six forming conditions of the roundness of the roll and, sixthly, the rotational speed unevenness of the layered transport roll, the present inventors not only individually adjust the conditions but also relate the conditions to each other. In consideration of the characteristics, it was adjusted precisely. And about the glass substrate which concerns on Examples 1-5 obtained by this, the difference of the plate | board thickness of the reference | standard point O already demonstrated based on FIG. 1 and the plate | board thickness of A point-H point is 20 mm square. For each area composed of four elements as one element, measurement was made with an ultrasonic thickness measuring machine over the entire area of each glass substrate, and the absolute value of the maximum value is shown in Table 1 below. Further, as Comparative Examples 1 and 2, the above-mentioned six molding conditions remain the same as before (each condition is not precisely adjusted in consideration of the reciprocal relationship), and the glass has the same vertical and horizontal dimensions and thickness as above. The absolute value of the maximum value obtained for each glass substrate in the same manner as described above is shown in Table 1 below.

  Further, FIG. 2A is a schematic perspective view schematically showing a change in the plate thickness over the entire area of the glass substrate with the 20 mm square as one unit in Example 1, and FIG. FIG. 4 is a schematic perspective view schematically showing a change in a difference in plate thickness over the entire area of a glass substrate, with a 20 mm square as a unit in Example 1. FIG. 3A is a schematic perspective view schematically showing a change in the thickness of the glass substrate over the entire area of the glass substrate with the 20 mm square as a unit in Comparative Example 1, and FIG. It is a schematic perspective view which represented typically the change of the difference of the plate | board thickness over the whole region of a glass substrate by making 20mm square into 1 unit about the comparative example 1. FIG.

  In addition to the above measurements, the glass substrates according to Examples 1 to 5 and Comparative Examples 1 and 2 are sucked and held on the surface plate of the exposure machine, and the reference point O and the points A to H shown in FIG. The height difference from the point is measured by a stylus type surface roughness measuring device over the entire area of each glass substrate for each area consisting of four elements with a 20 mm square as one element, and the absolute value of the maximum value is calculated. The results are shown in Table 1 below. Such a measurement was performed for the following reason. That is, the flatness of the element formation surface of the glass substrate is considered that the glass substrate is almost ideally adsorbed on the surface plate of the exposure machine during the exposure in the photo process, and the cause of the warp of the glass substrate is removed. Therefore, it is substantially determined by the difference in thickness (uneven thickness) of the glass substrate. Therefore, it is necessary to use a glass substrate with a small deviation in thickness obtained by limiting to a partial area in response to the request from the depth of focus of the exposure apparatus described above.

  According to Table 1 above (see also FIGS. 2 (a) and 2 (b)), any of Examples 1 to 5 has a plate thickness difference (part) of four elements with 20 mm square as one element. The unevenness) is 3.0 μm or less over the entire area of the glass substrate and can be determined to be good, and the maximum difference in height indicating the flatness of the glass substrate adsorbed by the surface plate of the exposure machine is 3 It was confirmed that no exposure deviation occurred even with an exposure apparatus having a depth of focus of 0.0 μm or less and a shallow focal depth.

  On the other hand, according to Table 1 above (see also FIGS. 3A and 3B), in Comparative Examples 1 and 2, the partial thickness deviation of the glass substrate was more than 3 μm (more than 4 μm). The maximum height difference indicating the flatness of the glass substrate adsorbed by the surface plate of the exposure machine is 4.5 μm or more, and an exposure machine with a shallow depth of focus was used. In this case, it was confirmed that the probability of occurrence of exposure deviation increases.

It is a principal part schematic plan view which shows the plate | board thickness measurement area of the glass substrate which concerns on embodiment of this invention. FIG. 2A is a schematic perspective view schematically showing a change in the thickness of the glass substrate according to the first embodiment of the present invention over the entire area of the glass substrate with a 20 mm square as a unit, and FIG. These are the schematic perspective views which represented typically the change of the difference of the plate | board thickness over the whole region of a glass substrate about 20 mm square as a unit about the glass substrate which concerns on Example 1 similarly. FIG. 3A is a schematic perspective view schematically showing a change in thickness of the glass substrate according to Comparative Example 1 over the entire area of the glass substrate with a 20 mm square as a unit, and FIG. About the glass substrate which concerns on the comparative example 1, it is a schematic perspective view which represented typically the change of the difference of the plate | board thickness over the whole region of a glass substrate by making 20mm square into 1 unit.

Explanation of symbols

1 Glass substrate 2 Side 3 Side A Plate thickness difference measurement point B Plate thickness difference measurement point C Plate thickness difference measurement point D Plate thickness difference measurement point E Plate thickness difference measurement point F Plate thickness difference measurement point G Thickness difference measuring point H Thickness difference measuring point O Reference point a Longitudinal dimension b Lateral dimension

Claims (1)

In the glass substrate manufactured by the float method in which the vertical dimension is 300 mm or more and the horizontal dimension is 300 mm or more, and the average value of the plate thickness is in the range of 0.3 to 4.0 mm,
When any position in the plane is a reference point, and the directions along two orthogonal sides are the X direction and the Y direction, respectively, the points A and B that are 20 mm away from the reference point on both sides in the X direction, Points C and D that are 20 mm apart on both sides in the Y direction from the reference point; points E and F that are 20 mm apart on both sides in the X direction from the reference point and 20 mm apart on both sides in the Y direction from the reference point , The absolute value of the difference between the total thickness of each of the eight points of G point and H point and the thickness of the reference point is 3 μm or less,
A glass substrate, wherein a film is formed on the surface and an element or a structure is formed by exposure and development by a photo process.

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