JP2012528073A - Glass irradiation treatment - Google Patents

Abstract

  The glass manufacturing method includes a step of providing a glass substrate including a structure having a fast relaxation species and a slow relaxation species. The glass substrate is provided at a bulk temperature (Tb) that is lower than the strain point (Tc) of the glass substrate. The method further includes exposing the glass substrate to radiation that can excite portions of the glass structure without increasing the bulk temperature (Tb) to a temperature above the strain point (Tc). The glass substrate is exposed to radiation in a manner that results in fast relaxation species relaxation without significant relaxation of the slow relaxation species.

Description

Cross-reference of related applications

  This application is a priority of US Provisional Patent Application No. 61/182180, filed May 29, 2009 entitled "IRRADIATION TREATMENT OF GLASS", the contents of which are generally relied upon and incorporated herein by reference. Insist on the right.

  The present invention generally relates to a method for manufacturing a glass substrate, and more particularly to a method for manufacturing a glass substrate including exposing the glass substrate to irradiation.

  It is known to provide glass substrates for use in liquid crystal display (LCD) applications. During the manufacture of (LCD), it is known that thermal processes can cause compaction and the volume and dimensional properties of the glass substrate can change in an undesirable manner. The force that promotes glass compaction can be expressed in particular as the difference between the fictive temperature (Tf) and the processing temperature. By developing the fictive temperature of glass to the processing temperature, compaction occurs. The fictive temperature (Tf) before the thermal process is determined by the initial formation of the glass substrate. In general, glass substrates that are rapidly formed (eg, by fusion draw) produce a relatively high fictive temperature (Tf) that is “locked in” to the glass substrate. In order to reduce the compaction acceleration during the processing of the (LCD), a pre-compacting secondary annealing process (pre-compacting secondary annealing process) is originally aimed at lowering the fictive temperature (Tf) determined during the formation of the glass substrate. an annealing process can be performed.

Glass compaction is also affected by the resistance of the glass to dimensional changes during the thermal process. Such resistance is often expressed by the glass viscosity during the thermal process, but the strain point at which the glass melt viscosity is equal to 10 ^14.7 poise (10 ^13.7 Pascal seconds), or the glass melt viscosity is It may also be represented by an annealing point with a temperature equal to 10 ^13.18 poise (10 ^12.18 Pascal seconds). To reduce glass compaction during the thermal process, the low temperature viscosity can be increased by adjusting the glass composition from the following equation, thereby increasing the relaxation time of the glass at a given temperature.

τ (T) ≈η (T) / G
In the above equation, “G” is the shear coefficient and converts the viscosity into a relaxation time. The following equation results in a reduction in compaction by increasing the relaxation time.

Tf (t) = T + (Tf (t = 0) -T) (e- ^{t / τ (T)} )
In the above equation, Tf (t) is the fictive temperature of the glass as a function of time, T is the heat treatment temperature, and Tf (t = 0) is the glass substrate formation (based on the glass draw rate and viscosity curve). It is a fictive temperature determined during the process, and τ (T) is determined based on the glass viscosity curve. In general, the reduction of the fictive temperature during the thermal process typically results in a corresponding glass substrate compaction. Therefore, based on the input to the above equation, the compaction of the glass substrate between thermal cycles can be modeled by observing changes in the virtual temperature.

  According to one embodiment of the present invention, a method for manufacturing a glass substrate is provided. The method includes providing a glass substrate that includes a structure having a fast relaxation species and a slow relaxation species. The glass substrate is provided at a bulk temperature (Tb) that is lower than the strain point (Tc) of the glass substrate. The method further includes exposing the glass substrate to radiation that can excite portions of the glass structure without increasing the bulk temperature (Tb) to a temperature above the strain point (Tc). The glass substrate is exposed to radiation in a manner that results in fast relaxation species relaxation without significant relaxation of the slow relaxation species.

  These and other features, aspects and advantages of the present invention will be better understood by reading the following Detailed Description, with reference to the accompanying drawings.

1 is a schematic diagram of a method for manufacturing a glass substrate including an exemplary embodiment of the present invention. FIG. 3 shows the hypothetical response of fast and slow reactive species to a heating cycle when a glass substrate has not been previously exposed to radiation in accordance with an embodiment of the present invention. FIG. 4 shows the hypothetical response of fast and slow reactive species to a heating cycle performed after exposing a glass substrate to irradiation in accordance with an embodiment of the present invention. 1 represents a glass substrate that is heated after being exposed to radiation in accordance with the present invention. FIG. 5 is a graph of experimental results representing the volume change of two glass substrates during a heating cycle where only one glass substrate was previously exposed to irradiation according to the present invention.

  The invention will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. However, the present invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These illustrative embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the invention to those skilled in the art.

  The glass material processing method of the present invention can be applied to various glass materials in various forms such as glass sheets, glass plates, and glass rods manufactured by various methods such as rolling, pressing, fusion draw, slot draw, and float. It should be noted that it is applicable. However, the present invention is particularly useful for glass materials formed in a process to which a high cooling rate such as 5 ° C./second or more is applied.

  Various glass materials can be used to manufacture the glass substrate of the present invention. For example, the glass substrate consists essentially of a glass material having an annealing point of at least 640 ° C., but may consist essentially of a glass material having other annealing points and / or a variety of having a wide range of annealing points. Various glass material components may be blended together. In one example, the glass material may have an annealing point of at least 720 ° C. In yet a further example, the glass material may have an annealing point of at least 770 ° C. After the irradiation treatment according to the present invention, a semiconductor deposition step can be further performed on a glass sheet suitable for depositing a semiconductor film on the surface. Illustrative methods can produce glass substrates for various applications. In one example, a liquid crystal display (LCD) manufacturing method can incorporate a glass substrate manufactured by a method according to an embodiment of the present invention.

  Referring to FIG. 1, a schematic diagram of the method includes an exemplary embodiment of the present invention. For illustrative purposes, these illustrative aspects are shown in a single continuous production line. Of course, one or more of the illustrated steps may be performed separately or may be omitted altogether. For example, each illustrated step may be performed at a different location and / or at a different time. In one example, the sequence of steps is performed at one location. One or more subsequent steps can then be performed at different locations. Furthermore, the glass substrate may be subjected to further steps not illustrated in the illustrative schematic shown in FIG.

  As shown in FIG. 1, in this illustrative method, a processed glass material can be provided to form an initial glass substrate. For example, as shown, the glass substrate 102 can be formed from a glass material using the fusion draw method 100. In further examples, the glass substrate 102 can be formed using a float method, a down-draw method, a rolling method, and / or other glass substrate forming methods. As shown, the glass substrate is formed as a glass substrate sheet, although other substrate structures may be provided in further examples.

  In a typical method, the glass substrate can optionally be cooled at various predetermined rates after being formed by the fusion draw method 100 or other forming techniques. For example, the glass substrate can be subjected to a cooling step at an average cooling rate of at least 5 ° C./second from the softening temperature (Ts) of the glass substrate to the strain point (Tc) of the glass substrate. If set, the predetermined cooling rate can be achieved in various ways. For example, conditions can be provided that provide a favorable cooling rate to the surrounding environment. For example, the fusion draw method 100 can be performed in an atmosphere having a predetermined configuration, temperature, and / or circulation for controlling the cooling rate of the glass substrate. In a further example, an optional cooling mechanism 300, such as the illustrated fan or a device that controls the circulation of cold air around the glass surface, may be provided to facilitate cooling of the glass substrate at a predetermined rate. If provided, the cooling mechanism 300 may comprise the illustrated fan, although other cooling devices may be provided in further examples.

  As shown, the glass substrate 102 can be pulled down 104a until a sufficiently long glass substrate is provided. Once the desired length is achieved, the lower portion 102b of the glass substrate can be separated from the upper portion 102a of the glass substrate. For example, as shown, the laser device 200 can cut the glass substrate from the side with a laser beam 202 and cut off the lower portion 102b of the glass substrate. In a further example, the lower portion 102b can be cut by grinding, crushing, scoring or other separation techniques. In further examples, the glass substrate 102 may be left during various other steps explicitly set forth herein. For example, the glass substrate may be continuous from other glass forming processes, such as a fusion draw process or a float process, through the cooling process described below, the irradiation zone 500, the processing zone 600 and / or the heating zone 700, Thereafter, the lower portion 102b of the glass substrate is separated from the upper portion 102a of the glass substrate. Therefore, in the illustrative method, the glass substrate 102 is continuously supplied from the glass forming step (for example, the fusion draw method 100) before cutting the lower portion 102b from the upper portion 102a of the glass substrate 102 in the production line. Can do.

  As shown, a cooling mechanism 300 can be provided to cool the upper portion 102a of the glass substrate at a predetermined cooling rate. In addition, or alternatively, a cooling mechanism can be provided to cool the lower portion 102b at a predetermined cooling rate before or after separating the lower portion 102b of the glass substrate from the upper portion 102a of the glass substrate.

  An optional glass substrate handling apparatus 400 can be provided to transport the glass substrate to various arbitrary processing zones. For example, as shown, the handling device 400 can include any stereotaxic device 402 having an air bearing 404 that redirects and / or places the glass substrate on the conveyor mechanism 406. The glass substrate 102c may be disposed on the conveyor mechanism 406 before entering the irradiation zone 500, for example.

  Based on the glass forming technique, the glass substrate 102c includes a structure that has "frozen" relaxation properties on the substrate based on the glass substrate forming method. Without limiting the discussion to any particular theory, certain evidence set forth herein allows us to hypothetically explain the overall relaxation characteristics for fast and slow relaxation species. To do. Fast relaxed species can be considered to include a group of single species, and may include groups of multiple species that behave together as fast relaxed species. Similarly, a slow relaxed species can be considered to include a group of single species, and may include groups of multiple species that behave together as slow relaxed species.

  It is believed that the fast and slow relaxation species of the glass substrate significantly affect the dimensional changes of the glass substrate during subsequent heating cycles. By way of example, FIG. 2A represents the application of a heating cycle 114, such as rapid thermal annealing (RTA), to the glass substrate 102c before entering the irradiation zone 500, more fully described below. The y-axis represents temperature and the x-axis represents time. As shown in FIG. 2A, the heating cycle 114 includes a heating segment 114a that represents an increase in the temperature of the glass substrate. The heating cycle 114 further includes a holding segment 114b that represents a period during which the glass substrate is held at the maximum heating temperature. Finally, the heating cycle 114 includes a cooling segment 114 c that represents the glass substrate temperature drop during the heating cycle 114.

  Also shown in FIG. 2A is a hypothetical hypothetical temperature profile 110 of slow relaxation species before, during and after the heating cycle 114 is performed. Prior to the heating cycle 114, the slow relaxation species are shown to have an initial fictive temperature represented by the horizontal segment 110a. After the start of the heating cycle 114 and before the cooling segment 114c, the fictive temperature of the slow relaxation species decreases with time, as represented by the downwardly sloping segment 110b. During the cooling segment 114c, the virtual temperature of the slow relaxation species is “frozen in” to the final virtual temperature represented by the horizontal segment 110c. Comparing the horizontal segments 110a and 110c, the final virtual temperature of the slow relaxation species is lower than the initial virtual temperature of the slow relaxation species. An arrow 111a represents a decrease in the virtual temperature from the initial virtual temperature of the slow relaxation species to the final virtual temperature.

  Further, FIG. 2A shows a hypothetical hypothetical temperature profile 112 of fast relaxation species before, during and after the heating cycle 114 is performed. Prior to the heating cycle 114, the fast relaxation species is shown to have an initial fictive temperature represented by the horizontal segment 112a. During the heating segment 114a, the fictive temperature of the fast relaxed species decreases with time, as represented by the segment 112b that slopes downward. As indicated by segment 112c, the fictive temperature of the fast relaxed species eventually reaches equilibrium with the process temperature and the glass substrate between the rear portion of the heating segment 114a, the holding segment 114b and the beginning of the cooling segment 114c. Continue to bulk temperature. During the cooling segment 114c, the fast relaxed fictive temperature is ultimately “frozen” at the final fictive temperature represented by the horizontal segment 112d. Comparing the horizontal segments 112a and 112d, the final virtual temperature of the fast relaxation species is lower than the initial virtual temperature of the fast relaxation species. An arrow 113a represents a decrease in the virtual temperature from the initial virtual temperature of the fast relaxation species to the final virtual temperature. As described above, a decrease in fictive temperature tends to cause compaction of the glass substrate. Thus, as shown in FIG. 2A, it is believed that fast and slow relaxation species contribute to the compaction of the glass substrate during the heating cycle 114 when the glass substrate is not exposed to irradiation.

  In accordance with aspects of the present invention, it is desirable to affect the fast relaxation species prior to heating cycle 114 without affecting significant relaxation of the slow relaxation species and to reduce dimensional changes during subsequent heating cycles. In one example, the fast relaxation species is affected such that the initial virtual temperature of the fast relaxation species is lower than the final virtual temperature of the fast relaxation species while substantially maintaining the virtual temperature profile 110 of the slow relaxation species. It is desirable to give.

  By way of illustration, FIG. 2B is similar to FIG. 2A, but represents the application of a heating cycle 114 to the glass substrate 102d after the step of irradiating the glass substrate 102d in an irradiation zone 500, more fully described below. . As shown in FIG. 2B, the hypothetical virtual temperature profile 110 of the slow relaxation species remains substantially the same as the profile 110 illustrated in FIG. 2A. On the other hand, exposing the glass substrate 102d to radiation can be considered to substantially affect the hypothetical virtual temperature profile 112 of the fast relaxed species. In fact, prior to heating cycle 114, the initial virtual temperature represented by horizontal segment 112e, where the fast relaxation species is substantially lower than the initial virtual temperature represented by horizontal segment 112a shown in FIG. 2A. Is included. During the heating segment 114a, the fast relaxation species fictive temperature remains at the initial fictive temperature, but eventually, as represented by segment 112f, eventually the rear portion of the heating segment 114a, the holding segment 114b and the cooling segment. During the beginning of 114c, it begins to adapt to the temperature of the glass substrate. During the cooling segment 114c, the fast relaxed species virtual temperature is ultimately “fixed” to the glass substrate at the final virtual temperature represented by the horizontal segment 112g (the fast relaxed species final virtual temperature). As 112d because the temperature is determined by the cooling rate 114c of the heating cycle). Comparing the horizontal segments 112e and 112g, the final virtual temperature of the fast relaxation species is higher than the initial virtual temperature of the fast relaxation species. Arrow 113b represents an increase in the virtual temperature from the initial virtual temperature of the fast relaxation species to the final virtual temperature. As described above, there is a tendency to cause compaction of the glass substrate due to a decrease in fictive temperature. Similarly, an increase in fictive temperature tends to result in glass substrate expansion. Thus, as shown in FIG. 2B, exposing the glass substrate to radiation causes the relaxed fast relaxed species to expand and the slow relaxed species to contract, thereby partially offset each other during the heating cycle 114. This is thought to reduce the net dimensional change of the substrate.

  Referring to FIG. 1 again, the glass substrate 102d can be exposed to irradiation in a state where the bulk temperature (Tb) of the glass substrate is lower than the strain point (Tc) of the glass substrate. For example, the bulk temperature (Tb) of the glass substrate can be measured by infrared (IR) temperature reading, contact thermocouple or other measurement configuration. Thus, the measured bulk temperature (Tb) is intended to refer to the overall temperature of the glass substrate rather than a specific point of the glass substrate that may be higher or lower than (Tb).

  Illustrative aspects of the invention can provide a glass substrate 102c having a structure that includes fast and slow relaxation species. The glass substrate 102c is provided at a bulk temperature (Tb) lower than the strain point (Tc) of the glass substrate 102c. The glass substrate 102c can then be transported along the direction 104c to the irradiation zone 500 by any conveyor mechanism 406. As shown, the irradiation zone 500 can be provided with an optional housing 502 and an irradiation source 504 that supplies the irradiation 506 to the glass substrate 102d. In the irradiation zone 500, the glass substrate 102d is exposed to irradiation that can excite a portion of the glass structure without increasing the bulk temperature (Tb) of the glass substrate 102d to a temperature higher than the strain point (Tc) of the glass substrate 102d. To do. The glass substrate 102d is exposed to the irradiation 506 in a manner that results in fast relaxation species relaxation without significant relaxation of the slow relaxation species.

  Various types of irradiation can be provided from the irradiation source 504. For example, irradiation 506 can include one or more infrared irradiation, microwave irradiation, ultraviolet irradiation, and / or various combinations of these or other types of irradiation. Further, as illustrated, in a further example, non-pulsed (eg, continuous) irradiation can be provided, but irradiation 506 can be pulsed. The irradiation source 504 can be a laser device, although other irradiation devices may be used in further examples. When provided as a laser device, the irradiation 506 can be provided as one or more pulsed or non-pulsed laser beams. In one example, a 248 nm ultraviolet pulsed laser can be used in accordance with embodiments of the present invention.

  The glass substrate 102d can be exposed to the irradiation 506 at various times. In one example, any portion of the glass substrate 102d can be exposed to the irradiation 506 for up to 4 hours. For example, any portion of the glass substrate 102d can be exposed to the irradiation 506 in the range of about 4 to about 18 hours, although in further examples the exposure time can be outside this range. Still further, the glass substrate 102d can be exposed to pulsed or non-pulsed irradiation at a single interval during the exposure time, but may include multiple intermittent intervals during the exposure time.

  While being exposed to the irradiation 506, the bulk temperature (Tb) of the glass substrate 102d can be kept below a certain temperature. In one example, during the process of exposing the glass substrate 102d to the irradiation 506, the bulk temperature (Tb) of the glass substrate 102d is less than 200 ° C, such as less than 150 ° C, less than 100 ° C, less than 50 ° C, such as less than 30 ° C. Can be increased. In a further example, at the end of the step of exposing the glass substrate 102d to the irradiation 506, the bulk temperature (Tb) can be less than (Tc) -200 ° C. ((Tc) is the strain point of the glass substrate). . For example, at the end of the step of exposing the glass substrate 102d to the irradiation 506, the bulk temperature (Tb) is set to a temperature below (Tc) -300 ° C, such as (Tc) -400 ° C, eg (Tc) -500 ° C. Less than. In a further example, at the end of the step of exposing the glass substrate 102d to the irradiation 506, the bulk temperature (Tb) is set to a temperature below 300 ° C., such as below 250 ° C., below 200 ° C., below 150 ° C., for example below 100 ° C. can do. Thus, the step of exposing the glass substrate 102d to the irradiation 506 can be performed at a significantly lower temperature than a typical secondary thermal annealing process, thereby (such as deformation) a glass substrate. It will be appreciated that the risk of undesirable changes to is reduced.

  After sufficient exposure to the irradiation 506, the conveyor substrate 406 can move the glass substrate 102d along the direction 104d. Optionally, the glass substrate 102d can be moved to a processing zone 600 where the glass substrate 102e is provided with one or more layers 103 of amorphous or polycrystalline silicon. As schematically shown, layer 103 can be applied by device 602 as glass substrate 102e moves along direction 104e. Amorphous or polycrystalline silicon can also be applied by various other techniques, and can be applied to one or both sides of the glass substrate 102e. As shown, the glass substrate 102d is sent from the irradiation zone to the processing zone 600 without subjecting the glass substrate 102d to a secondary thermal annealing process. Although it is possible to perform a secondary thermal annealing step, it is advantageous to avoid it. In addition, the process of exposing the glass substrate to radiation can eliminate the need for a secondary annealing process or reduce the strength of the secondary annealing process.

  After passing through the irradiation zone 500, the glass substrate 102f can be further processed in the heating zone 700. The heating zone 700 includes a resistance heater 702 configured to increase the bulk temperature (Tb) to a temperature above 300 ° C. so that the relaxed fast relaxed species expand and the slow relaxed species contract. Also good. The heating step can be performed during or prior to display (LCD) manufacture. For example, as shown, the heating step can be performed on the production line shown in FIG. In other examples, a glass substrate may pass through the irradiation zone 500 and the processing zone 600. The glass substrate 102e can then be transported to another location where the heating process represented by the heating zone 700 is performed.

  During the heating process in the heating zone 700, the slow relaxation species shrinkage is at least partially offset by the expansion of the fast relaxation species, thus preventing unwanted dimensional changes of the glass substrate 102f (such as compaction or expansion). Can do. In one example, the slow relaxation species shrinkage is substantially equal to the fast relaxation species expansion during the process of heating the glass substrate 102f in the heating zone 700. As such, the compaction and / or expansion of the glass substrate 102f can be substantially prevented. In a further example, the slow relaxation species shrinkage is only partially compensated by the fast relaxation species expansion. In such an example, compaction may occur in the glass substrate 102f. However, such compaction will be less than the compaction that can occur in other methods that do not expose the glass substrate to irradiation in the irradiation zone. In yet a further example, the expansion of the fast relaxed species is greater than the contraction of the slow relaxed species. In such an example, the glass substrate 102f may expand.

  The irradiation range of the irradiation zone 500 and / or the heating range of the heating zone 700 can be used to control the overall dimensional change of the glass substrate 102f when heating the glass substrate 102f to a temperature higher than 300 ° C. Is recognized. For example, based on known subsequent heating steps used in (LCD) manufacturing, the glass substrate can be irradiated in a reduced manner, such as preventing compaction of the glass substrate 102f. As such, undesirable dimensional changes can be reduced and prevented.

  FIG. 3 represents a glass substrate 102f heated in a heating zone 700 at a hypothetical temperature (such as 450 ° C.) after exposure to radiation in accordance with the present invention. The y-axis represents volume change and the x-axis represents time. The expansion curve 154 represents fast relaxation species expansion, and the contraction curve 156 represents slow relaxation species compaction. The dimension curve 150 represents the overall dimensional change of the glass substrate 102f in the heating zone based on the relaxation of the relaxed fast relaxation species and the compaction of the slow relaxation species. As shown, the initial expansion of the fast relaxed species oversets the initial compaction of the slow relaxed species. Thus, the glass substrate 102 f initially expands during heating in the heating zone 700, as represented by the segment 150 a that slopes upwards of the dimension curve 150. Over time, the expansion of the fast relaxation species begins to stall and eventually stops when the virtual temperature of the fast relaxation species reaches equilibrium with the heat treatment temperature, as shown by the expansion curve 154. On the other hand, as shown by the compaction curve 156, compaction continues over time with a slow relaxed species. Thus, eventually, compaction begins to occur at the glass substrate 102f, as represented by the downwardly sloping segment 150b, and net compaction is provided, as represented by the segment 150c. Point 152 represents the time during which glass substrate 102f experiences a net zero dimensional change.

  FIG. 4 is a graph representing actual test data comparing a dimensional curve 401 with a dimensional curve 403 of a glass substrate 102c that has not been exposed to irradiation in accordance with the present invention. This test data represents the dimensional change that occurred over time when the glass substrates 102c and 102f were held in the heating zone 700 at a temperature of 450 ° C. The y-axis represents the dimensional change of the glass substrate in parts per million (ppm), and the x-axis represents the time in minutes. The dimension curve 403 shows that the compaction increases continuously between time zero and 300 minutes. On the other hand, in the dimensional curve 401 representing the glass substrate 102f, initial expansion of the glass substrate 102f and subsequent compaction of the glass substrate 102f are recognized. As shown, a net dimensional change occurs at about 45-60 minutes (point 405) after heating at 450 ° C. in heating zone 700.

  It should be noted that the zones 500, 600 and 700 may be located in the same facility, close to each other, far from each other, or in different facilities. Therefore, the irradiation treatment process, the thin film application process, and the process after the heat treatment can be performed at the same or different positions by the same or different elements.

  Accordingly, non-limiting aspects and / or embodiments of the present disclosure include:

C1. (A) providing a glass substrate comprising a structure comprising fast and slow relaxation species, and having a bulk temperature Tb lower than the strain point of the glass substrate;
(B) exposing the glass substrate to radiation that can excite a portion of the glass structure without increasing Tb to a temperature above Tc, without significant relaxation of slow relaxation species, A method of manufacturing a glass substrate, wherein the glass substrate is exposed to radiation in a manner that provides for relaxation of fast relaxation species.

C2. The method of C1, wherein Tb is increased by less than 200 ° C. in step (b).

C3. The method of C1 or C2, wherein Tb is less than Tc−200 ° C. at the end of step (b).

C4. The method of any one of C1-C3, wherein Tb is less than 300 ° C. at the end of step (b).

C5. The method of any one of C1-C4, wherein the glass substrate consists essentially of a glass material having an annealing point of at least 640 ° C.

C6. The method according to any one of C1 to C5, wherein the irradiation is selected from the group consisting of infrared irradiation, microwave irradiation, and ultraviolet irradiation.

C7. The method of any one of C1-C6 whose irradiation is a pulse in a process (b).

C8. The method of any one of C1-C7, wherein in step (b), any portion of the glass substrate is exposed to irradiation for up to 4 hours.

C9. The method of any one of C1 to C8, wherein the glass substrate is subjected to a cooling step at an average cooling rate of at least 5 ° C./second from the glass substrate softening temperature Ts to Tc before step (a).

C10. A method for producing a liquid crystal glass substrate using any one of C1 to C9.

C11. After step (b), the next step (c):
(C) The method according to any one of C1 to C10, further comprising a step of forming an amorphous or polycrystalline silicon layer on the surface of the glass substrate.

C12. The method of C11, wherein the glass substrate is not subjected to the secondary heat annealing step after the step (b) and before the step (c).

C13. The method of any one of C1-C12 comprising increasing Tb to a temperature above 300 ° C. so that after relaxation of the fast relaxed species, the relaxed fast relaxed species expand and the slow relaxed species contract .

  It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (8)

(A) providing a glass substrate having a bulk temperature Tb lower than the strain point Tc of the glass substrate, including a structure comprising a fast relaxation species and a slow relaxation species;
(B) exposing the glass substrate to radiation capable of exciting portions of the glass structure without increasing Tb to a temperature above Tc;
And the glass substrate is exposed to the irradiation in a manner that provides relaxation of the fast relaxation species without significant relaxation of the slow relaxation species.   The method according to claim 1, wherein in step (b), Tb is increased below 200 ° C.   The method according to claim 1 or 2, characterized in that the glass substrate consists essentially of a glass material having an annealing point of at least 640 ° C.   4. The method according to any one of claims 1 to 3, characterized in that in step (b) any part of the glass substrate is exposed to the irradiation for a maximum of 4 hours.   Before the step (a), the glass substrate is subjected to a cooling step at an average cooling rate of at least 5 ° C / second from the softening temperature Ts to Tc of the glass substrate. The method according to any one of the above. After step (b), the next step (c):
(C) The method according to any one of claims 1 to 5, further comprising the step of forming an amorphous or polycrystalline silicon layer on the surface of the glass substrate.   The method according to claim 6, characterized in that the glass substrate is not subjected to a secondary thermal annealing step after step (b) and before step (c).   After the relaxation of the fast relaxation species, the Tb is increased to a temperature higher than 300 ° C. so that the relaxed fast relaxation species expands and the slow relaxation species contracts, The method according to any one of claims 1 to 7.

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