TWI498289B - A forming die for glass forming, a glass forming apparatus, a glass forming method, and a manufacturing method of a mask substrate - Google Patents

Description

Mold for glass forming, glass forming device, glass forming method, and method for manufacturing photomask substrate

The present invention relates to a molding die for glass forming, a glass forming device, a glass forming method, and a method of producing a photomask substrate.

Priority is claimed on Japanese Patent Application No. 2010-210686, filed on Sep. 21, 2010, the content of which is incorporated herein.

In recent years, in order to obtain an optical member having a wide area such as a large lens or a reticle or a large liquid crystal display, a glass block such as a glass ingot formed in advance is formed into a flat shape by heat and pressure molding. A method of forming an enlarged area (for example, refer to Patent Document 1).

Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-307265

Here, in the case where the glass block is subjected to heat and pressure molding, after the glass block is press-formed at a high temperature using a row die, the glass block is cooled and then taken out of the furnace. At the time of this cooling, the difference in the amount of shrinkage accompanying the temperature drop occurs between the glass and the forming mold. In other words, in the case of using a molding die having a linear expansion coefficient larger than that of the glass to be molded, when the glass and the molding die are shrunk during cooling, the amount of shrinkage of the molding die outside the difference in linear expansion coefficient is larger than that of the inner glass. As a result, excessive stress is applied, and the molding die is broken or the glass is broken.

Further, as a method of preventing such damage, the larger the size of the molding die, the larger the amount of shrinkage from a high temperature, and therefore there is a method of providing a gap for promoting the amount of shrinkage on the side of the mold. However, since a gap is provided in the molding die, there is a case where the glass which becomes a viscous body enters the gap during molding, and the necessary shape cannot be obtained. Alternatively, there may be a problem that the gap between the glass and the joint portion of the forming mold is broken to cause the forming mold to be broken or the forming mold to be damaged.

It is an object of the present invention to provide a molding die, a glass forming apparatus, a glass forming method, and a method of manufacturing a mask substrate which can prevent breakage of glass or a molding die body and shape the glass into a desired shape.

A molding die for glass molding according to a first aspect of the present invention includes: a mold main body for heating and press molding of glass; and a support member disposed so as to be movable against a movable member of the mold main body, and the mold main body is opened for opening The difference in linear expansion coefficient between the glasses is destructible based on the stress.

A molding die for glass molding according to a second aspect of the present invention is configured to have a hollow portion for accommodating a glass ingot, and surround the hollow plate with a platen, a side plate disposed thereon, and a top plate movable up and down inside the side plate a support member configured to abut the outer side of the side plate, the side plate being formed to be relatively movable relative to the platen toward the outer side thereof, and the support member is from the side plate The support member has a strength that, when the glass ingot accommodated in the hollow portion is heated and pressurized to be deformed, the shear force generated from the load of the glass ingot via the side plate cannot be broken. And the strength at which the shear force generated by the load applied by the difference between the linear expansion coefficients of the molding die and the glass ingot can be broken when the glass ingot is heated and pressure-deformed.

Moreover, the glass forming apparatus according to the third aspect of the present invention includes the molding die for glass forming, and a heating means and a pressurizing means for the glass ingot.

Further, in the glass forming method according to the fourth aspect of the present invention, the glass forming apparatus is characterized in that the glass ingot is housed in a molding die, and the glass ingot is heated and pressurized by a heating means and a pressurizing means to be deformed; When the deformed glass ingot is cooled, the load is loaded by the difference between the linear expansion coefficient of the molding die and the glass ingot, and the side plate is relatively moved relative to the platen toward the outer side thereof, whereby the shearing force acts. The support member is broken by the shearing force in response to the shearing force.

Moreover, the method for producing a photomask substrate according to a fifth aspect of the present invention includes the step of obtaining a glass molded body by the glass forming method.

According to the molding die of the embodiment of the present invention, the glass or the molding die body can be prevented from being damaged and the glass can be formed into a desired shape.

Hereinafter, an example of an embodiment of the present invention will be described.

Fig. 1 is a cross-sectional view showing the glass forming apparatus of the embodiment. Fig. 2 is a plan view showing a molding die for glass forming of the glass forming apparatus of Fig. 1. Figure 3 is a cross-sectional view taken along line A-A of Figure 2; Fig. 4 is a cross-sectional view showing a state in which a glass ingot is deformed in a molding die for molding a glass of Fig. 3; Fig. 5 is a cross-sectional view showing a state in which a pin is bent in a molding die for molding a glass of Fig. 4; 6 to 9 are perspective views showing another example of a molding die for glass forming.

The glass forming apparatus 1 of the present embodiment is formed by heating a mask substrate such as a semiconductor mask, a liquid crystal mask, or a large lens material for optics, from a composite quartz glass ingot made of a ruthenium compound. Shape device.

As shown in FIG. 1, the glass forming apparatus 1 has a heat insulating material 3 provided over the entire surface and a carbon heater (heating means) disposed on the wall of the heat insulating material 3 on the inner wall of the vacuum chamber 2 made of metal. 5. A molding die 10 for forming a glass made of carbon graphite (hereinafter referred to as a molding die 10) is provided at a central portion of the inside of the vacuum chamber 2, and a cylinder (pressurizing means) 4 is provided at an upper portion thereof.

The molding die 10 is placed on the pedestal 6 inside the vacuum chamber 2 of the glass forming apparatus 1, and has a bottom portion including the platen 14 and the bottom plate 17, as shown in Figs. 2 to 5 . The molding die 10 (mold main body) including the platen 14 and the bottom plate 17 is made of carbon graphite as described above, and has a material having a linear expansion coefficient larger than that of the glass ingot 20A. Specifically, the linear expansion coefficient of the synthetic quartz glass is about 5 × 10 ^-7 / ° C, and the linear expansion coefficient of the carbon graphite is about 2 to 5 × 10 ^-6 / ° C.

Further, the molding die 10 (mold main body) is configured to have a hollow portion 19 for accommodating the glass ingot 20A, and the table 14 and the bottom plate 17, the side plates 11 disposed thereon, and the upper side of the side plates 11 can be moved up and down The top plate 13 surrounds the hollow portion 19. In detail, the molding die 10 (mold body) is provided with a side plate 11 (movable member) formed to be relatively movable with respect to the platen 14. The side plate guide 12 fixed to the side plate 11 by bolts or the like restricts the freedom (movement) of the top plate 13 of the glass ingot 20A which is a direct pressure forming target in the vertical direction. Further, in the present embodiment, as shown in FIG. 2, a rail 18 is provided on the platen 14, and the side plate 11 is placed on the rail 18. The side plates 11 are movable relative to the platen 14 in the direction of the rails 18 (i.e., the outer side of the side panels 11).

Further, on the outer side of the side plate 11 of the platen 14, a pin (support member) 15 is disposed to abut against the side plate 11. Further, this pin 15 is supported from the outside and restricts the side plate 11. In particular, in the present embodiment, as shown in FIG. 2, a plurality of insertion holes 16 are formed in the platen 14 at a position on the outer side of the abutting side plate 11. The pin 15 can be inserted into the plurality of insertion holes 16. Further, in the present embodiment, the pin 15 is disposed in plural numbers on the four side walls 11 of the molding die 10 which are arranged in a substantially square shape in plan view. Here, two pins 15 are disposed on each of the side plates 11 .

Further, the pin 15 may be arranged in a plurality of the same type. Alternatively, the pin 15 may be configured by a combination of different materials, shapes, and diameters depending on the required strength. The plurality of insertion holes 16 are configured such that all of the insertion holes 16 can correspond to different shapes or diameters (for example, the diameter of the holes is configured to be gradually reduced from the surface side). Alternatively, the plurality of insertion holes 16 may be formed into an insertable shape or a diameter different from each other. Alternatively, the number of the pins 15 disposed on the side plates 11 may be changed (that is, the number of the pins 15 may be different between one of the side plates 11 and the other side plate 11).

The pin 15 has a strength that when the glass ingot 20A accommodated in the hollow portion 19 is heated and pressurized to be deformed, the shear force generated from the load of the glass ingot 20A via the side plate 11 cannot be broken; and When the glass ingot 20B after the heat and pressure deformation is cooled, the shear force generated by the load applied by the difference between the linear expansion coefficient of the molding die 10 and the linear expansion coefficient of the glass ingot 20A can be broken. Further, in the present embodiment, the members constituting the molding die 10 have the same linear expansion coefficients. In this case, since the width of the platen 14 is the largest, the magnitude of the shear force generated upon cooling is substantially determined by the difference in linear expansion coefficients between the platen 14 and the glass ingot 20A.

In other words, when the pin 15 has a heating and pressurizing deformation of the glass ingot 20A accommodated in the hollow portion 19, the pressure acting on the side plate 11 from the deformed glass ingot 20A cannot be broken and the strength can be withstood. When the glass ingot 20B after the deformation is cooled, since the linear expansion coefficient of the platen 14 of the carbon graphite-made molding die 10 is larger than that of the glass ingot 20B, the amount of shrinkage of the platen 14 in the lateral direction is large. As a result, the glass ingot 20B having a small amount of shrinkage is caused to load the side plate 11 disposed on the platen 14 having a large amount of contraction to the outside. The pin 15 has the strength at which the shear force generated by the load of the load can be bent. The load is loaded by the difference in linear expansion coefficient between the glass ingot 20B and the platen 14 of the forming mold 10, and the pin 15 is bent by the shear force generated by the load. As a result, the glass or the molding die 10 can be prevented from being damaged.

Further, in the upper portion of the glass forming apparatus 1, as described above, a cylinder (pressurizing means) 4 for directly pressing the top plate 13 is provided. The glass ingot 20A is pressure-molded by the cylinder 4 to an arbitrary thickness.

Next, a glass forming method and a method of manufacturing a mask substrate by the molding die 10 and the glass forming apparatus 1 including the molding die 10 will be described.

First, as shown in FIGS. 1 and 3, the platen 14, the bottom plate 17, the side plates 11, and the side plate guides 12 are arranged in combination on the pedestal 6 inside the vacuum chamber 2 of the glass forming apparatus 1. Next, the predetermined pin 15 (here, two pins 15 are disposed on each of the side plates 11) is inserted into the insertion hole 16 formed in the platen 14. Thereby, the molding die 10 mounted in a state in which the side plates 11 are supported from the outside by the pins 15 is formed. Further, in the molding die 10, the glass ingot 20A is placed in the hollow portion 19 of the molding die 10, the top plate 13 is placed on the upper portion, and then the cylinder 4 is brought into contact with the upper surface of the top plate 13.

Next, after the inside of the vacuum chamber 2 of the glass forming apparatus 1 mounted as described above is exhausted, the inside of the vacuum chamber 2 is filled with an inert gas. Next, the glass ingot 20A in the hollow portion 19 of the molding die 10 is heated by the carbon heater 5, and the temperature is raised to a temperature equal to or higher than the crystallization temperature and the softening point. At this time, it may be maintained at a constant temperature until the inside of the glass ingot 20A becomes a uniform temperature.

After reaching a predetermined temperature, the cylinder 4 is actuated to move the top plate 13 downward, and the glass ingot 20A is press-formed. Further, at the point of the start of the press forming, the forming mold 10 exhibits expansion in accordance with the ambient temperature. In addition, as the pressurization procedure of the glass ingot 20A progresses, the glass ingot 20A gradually becomes a flat shape, and is in a state of being in close contact with the side plate 11 substantially without a gap.

As the glass ingot 20A is pressurized by the top plate 13, the pressing force of the top plate 13 acts on the side plate 11 via the glass ingot 20A as a stress in the outer circumferential direction (outer direction). Since the side plate 11 is restricted from being moved outward by the pin 15, the movement is not easy. At this time, the stress due to the glass forming is transmitted to the pin 15 via the glass ingot 20A and the side plate 11. Here, when the pin 15 is bent by the above-described stress, the restriction of the side plate 11 is released, and at the same time, the glass ingot 20A flows in the circumferential direction due to the force received from the glass ingot 20A. As a result, the glass ingot 20A flows out of the area surrounded by the side plate 11, and the shape of the inner side surface of the side panel 11 cannot be obtained. Therefore, the pin 15 must be able to withstand the strength of the stress generated by the glass forming, and is configured to have such strength.

Then, as shown in FIG. 4, the glass ingot 20A is pressed to the bottom plate 17, the top plate 13, and the side plate 11 of the molding die 10, and the glass ingot 20B is formed into a thin plate shape. Cooling step. With this cooling, the forming mold 10 and the glass ingot 20B show shrinkage in accordance with the ambient temperature. Here, the forming mold 10 has a larger coefficient of linear expansion than the glass ingot 20B. Further, among the forming dies 10, in particular, the platen 14 has a larger dimension in the lateral direction than the side plate 11. Therefore, the contraction amount of the platen 14 becomes larger with respect to the side plate 11, and the shrinkage accompanying the cooling becomes remarkable. Therefore, in the opposite direction, the load is generated in the direction in which the glass ingot 20B is expanded, that is, in the direction in which the side plate 11 is extruded in the outer circumferential direction (outer direction).

The load carried by the side panel 11 is transmitted to the pin 15 provided on the outer side of the side panel 11. When the stress caused by the contraction from the side plate 11 exceeds the strength limit of the pin 15, the pin 15 is broken outward as shown in Fig. 5 . Then, the restriction of the side plate 11 is released simultaneously with the destruction of the pin 15, and the side plate 11 is moved in the circumferential direction (outer direction) to the glass ingot 20B to open the stress. At this time, since the glass ingot 20B is solidified by cooling, it does not flow out to the area surrounded by the side plate 11. Thereafter, the temperature was lowered to room temperature, and the molding die 10 was taken out from the vacuum chamber 2, and the formation of the glass was completed.

Then, the glass molded body obtained by the above-described glass forming method is appropriately subjected to a grinding process or a cutting process for a predetermined size, a cornering process for forming an end face into an R shape, and an abrasive or the like. The surface is subjected to processing such as a grinding step of finishing. As a result, a desired photomask substrate can be obtained.

As described above, according to the molding die 10 for glass molding of the present embodiment, the glass molding apparatus 1, the glass molding method, and the method of manufacturing the photomask substrate, the stress which can be broken by the stress generated by the cooling after forming (support member) (15) The excessive stress is applied to the glass to be formed, and the stress can be opened without breaking the glass, which is the object to be formed, and the linear expansion coefficient of the glass to be formed and the platen 14 of the molding die 10 can be made. The resulting stress causes the load on the forming mold 10 to be suppressed to a minimum, and the glass can be formed into a desired shape.

Further, in the present embodiment, the pin 15 (pin-shaped member, rod-shaped member) is used as the supporting member, and the pin 15 can be inserted into and removed from the plurality of insertion holes 16 formed in the platen 14. Therefore, the strength can be simply changed by changing the number or type of the configured pins 15. For example, in the present embodiment, two pins 15 of the same type are disposed on one side plate. If the number of configured pins is increased, the strength of the pin as a whole can be increased (conversely, if the number of configured pins is reduced, the strength of the pin as a whole can be reduced). Further, when a plurality of pins are arranged, it is possible to use only a plurality of thick diameters, only a plurality of diameters, a mixture of diameters and thinners, or a mixture of plural diameters or shapes. Strength changes. Further, when a plurality of pins are disposed, the load may be uniformly applied to the respective pins so as to be arranged in a substantially one row to abut the side plates. Further, it is also possible to arrange a plurality of pins at equal intervals so that the load is uniformly applied to the respective pins. Additionally and/or alternatively, the pins can be configured to be non-column or non-equal.

Further, as described above, in the present embodiment, the pin 15 which can be inserted and removed into the insertion hole 16 formed in the platen 14 is used as the supporting member. Therefore, the process of bending the pin 15 can be simplified. For example, after the glass is formed, the bent pin 15 is pulled out from the insertion hole 16 and the new pin 15 is reinserted into the insertion hole 16. Therefore, the manufacturing efficiency of the glass and the photomask substrate can be improved.

Further, when determining the strength of the pin, for example, the load applied to the side plate and the shear force generated on the pin can be obtained by mechanical simulation in advance, so that the shear force generated by the load at the time of molding cannot be broken and cooled. The strength of the pin can be determined by the way the shear force generated by the load can be broken. If the strength required for the pin is determined in this way, it can be used by selecting a desired strength from among various pins of the pre-measured strength.

The embodiments described above are described in order to facilitate the understanding of the present invention and are not intended to limit the present invention.

For example, in the above-described embodiment, quartz glass is exemplified as the glass to be molded, and carbon (carbon graphite) is exemplified as the material of the molding die. However, the present invention is not limited thereto. For example, as another glass to be molded, borosilicate glass, soda lime glass, or the like can be given. The material of the molding die may be other materials such as alumina which can be used at a high temperature.

Here, when selecting the material of the glass and the molding die, it may be determined in consideration of the composition of the glass, the molding conditions, and the like. The effect of the present embodiment can be obtained by a combination of a linear expansion coefficient of the glass which is smaller than a linear expansion coefficient of a material of a molding die (especially a platen) and a condition that the supporting member can exhibit the function of the molding die of the present invention. However, as a material of a molding die (mold main body), since carbon is excellent in alumina strength and thermal shock resistance, it is preferable to use carbon.

Further, in the present embodiment, carbon graphite is used as the material of the pin 15. As the material of the pin 15, a material other than carbon graphite may be used. For example, a material which can be used at a high temperature such as alumina may be used.

Further, in the above embodiment, the pin 15 (pin-shaped member or rod-shaped member) is used as the supporting member, but the present invention is not limited thereto. It is also possible to use a pin 15 as long as it is a member having a required strength and capable of being destroyed by a predetermined load. As the supporting member other than the pin 15, for example, as shown in FIG. 6, a plurality of insertion members 115b which are insertable and detached from the plurality of insertion holes 116 formed in the platen 114 are formed below the long plate-shaped member 115a. The long plate member 115 with the insertion member. In the molding die using the long plate member 115 with the insertion member, the long plate member 115a abutting against the side plate 111 is pressed in the outer circumferential direction (outward direction) upon cooling, and the long plate member 115a and the insertion member are pressed. The part between 115b can be destroyed.

Moreover, as a support member other than the pin 15, the form shown in FIG. 7 is mentioned. In Fig. 7, instead of the insertion hole 16, a groove 216 is formed in the platen 214 along the position of the side plate 211, and the thin plate member 215 which can be inserted and removed from the groove 216 is used as a support member. In the molding die using the thin plate-shaped member 215, one portion (abutting portion) of the thin plate-shaped member 215 abuts against the side plate 211, and is pressed in the outer circumferential direction (outward direction) upon cooling. Further, the other portion (insertion portion) of the thin plate-shaped member 215 is inserted into the groove 216 to be substantially fixed. As a result, the portion between the abutting portion of the thin plate-shaped member 215 and the insertion portion can be broken.

Moreover, as a support member other than the pin 15, the form shown in FIG. 8 is mentioned. In Fig. 8, the substantially L-shaped member 315 is a supporting member. In one example, the L-shaped bottom side portion 315b of the substantially L-shaped member 315 is fixed to the platen 314 with the longitudinal direction thereof being the outer circumferential direction (outer direction). For example, a recess 316 is formed in the platen 314 to fix the bottom edge portion 315b. Further, the side plate 311 abuts against the L-shaped upper portion 315a. That is, in one example, the substantially L-shaped member 315 has a recess 316 which is inserted into the platen 314 and is substantially fixed to the bottom edge portion 315b of the platen 314, and one end of the bottom edge portion 315b is the base portion and the bottom portion. The upper portion 315a extends in a direction in which the extending direction of the side portion 315b is orthogonal, and one of the upper portions 315a abuts against the side plate 311. In the molding die using the substantially L-shaped member 315, by pressing the upper portion 311a of the substantially L-shaped member 315 at the time of cooling, the portion between the upper portion 315a and the bottom portion 315b of the L-shape can be broken. .

Moreover, as a support member other than the pin 15, the form shown in FIG. 9 is mentioned. In FIG. 9, the substantially L-shaped long plate-shaped member 415 is a support member, and the L-shaped bottom side portion 415b of the substantially L-shaped long plate-shaped member 415 is fixed to the platen 414. For example, a recess 416 is formed in the platen 414 to fix the bottom edge portion 415b. Further, the side plate 411 abuts against the L-shaped upper portion 415a. That is, in an example, the substantially L-shaped long plate-shaped member 415 has a recess 416 inserted in the platen 414 and is substantially fixed to the bottom side portion 415b of the platen 414. The bottom edge portion 415b has a long side that extends along the side plate 411. Further, the substantially L-shaped long plate-shaped member 415 has a portion 415a extending from one of the long sides of the bottom portion 415b, and one of the upper portions 415a abuts against the side plate 411. The angle between the bottom edge portion 415b and the upper portion 415a is, for example, 90°. In the molding die using the substantially L-shaped long plate-like member 415, the upper portion 415a and the bottom portion 415b are pressed between the upper portion 415a and the bottom portion 415b by pressing the upper L-shaped long plate-like member 415 at the time of cooling. Part can be destroyed.

In the present embodiment, the glass ingot 20A is molded at a temperature equal to or lower than the crystallization temperature and the softening point temperature, but the invention is not limited thereto. The molding temperature may be at least the crystallization temperature of the glass ingot 20A. For example, it may be formed at a temperature higher than the softening point of the glass ingot 20A.

1. . . Glass forming device

2. . . Vacuum chamber

3. . . Insulation material

4. . . Cylinder (pressure means)

5. . . Carbon heater (heating means)

6. . . Pedestal

10. . . Forming mold for glass forming

11,111,211,311,411. . . Side panel

12. . . Side plate guide

13. . . roof

14,114,214,314,414. . . Platen

15. . . Pin (support member)

115. . . Long plate member (support member) with insert member

215. . . Thin plate member (support member)

315. . . R-shaped rod-shaped member (support member)

415. . . R-shaped long plate member (support member)

16,116. . . Insertion hole

216. . . groove

316,416. . . Depression

17. . . Bottom plate

18. . . track

20A, 20B. . . Glass ingot

Fig. 1 is a cross-sectional view showing the glass forming apparatus of the embodiment.

Fig. 2 is a plan view showing a molding die for glass forming of the glass forming apparatus of Fig. 1.

Figure 3 is a cross-sectional view taken along line A-A of Figure 2;

Fig. 4 is a cross-sectional view showing a state in which a glass ingot is deformed in a molding die for molding a glass of Fig. 3;

Fig. 5 is a cross-sectional view showing a state in which a pin is bent in a molding die for molding a glass of Fig. 4;

Fig. 6 is a perspective view showing another example of a molding die for glass forming.

Fig. 7 is a perspective view showing another example of a molding die for glass forming.

Fig. 8 is a perspective view showing another example of a molding die for glass forming.

Fig. 9 is a perspective view showing another example of a molding die for glass forming.

1. . . Glass forming device

2. . . Vacuum chamber

3. . . Insulation material

4. . . Cylinder (pressure means)

5. . . Carbon heater (heating means)

6. . . Pedestal

10. . . Forming mold for glass forming

11. . . Side panel

12. . . Side plate guide

13. . . roof

14. . . Platen

15. . . Pin (support member)

17. . . Bottom plate

19. . . Hollow part

20A. . . Glass ingot

Claims (12)

A molding die for glass forming, comprising: a mold body for heat and pressure forming of glass; and a support member disposed to abut against a movable member of the mold body, for opening between the mold body and the glass The difference in coefficient of linear expansion is destructible based on the stress. A molding die for glass forming according to the first aspect of the invention, wherein the die body has a plurality of holes and/or a plurality of grooves into which one of the support members can be inserted. The molding die for glass forming according to the first or second aspect of the invention, wherein the support member has a strength that cannot be broken by a shearing force generated by a load carried by the movable member in a heating and pressurizing step, and has a cooling property. The shearing force generated by the load carried by the load due to the difference in linear expansion coefficient between the mold body and the glass may destroy the strength. A molding die for glass forming according to claim 1 or 2, wherein the material of the support member contains carbon. The molding die for glass forming according to claim 1 or 2, wherein the die body has: a platen; a top plate that can be moved up and down; and a side plate as the movable member is disposed on the platen. It can move relative to the platen. A molding die for glass forming is configured to have a hollow portion for accommodating a glass ingot, a platen, a side plate disposed thereon, and a side plate The top plate that moves up and down on the inner side surrounds the hollow portion, and is characterized in that a support member is disposed on the outer side of the platen to abut the outer side of the side plate, and the side plate is formed to be relatively movable relative to the platen toward the outer side thereof And supporting the outer side of the side plate by the supporting member; the supporting member has a strength to load the glass ingot from the glass ingot when the glass ingot accommodated in the hollow portion is heated and pressurized to be deformed The strength at which the shear force generated cannot be broken; and the shear force generated by the load carried by the difference between the linear expansion coefficients of the forming mold and the glass ingot after cooling the glass ingot after heating and pressurizing deformation Destructible strength. The molding die for glass forming according to claim 6, wherein a plurality of insertion holes are formed in the platen at a position abutting the outer side of the side plate; the support member is detachable from the plurality of The pin of the insertion hole is formed. A molding die for glass forming according to claim 6 or 7, wherein the glass ingot is quartz glass. A molding die for glass forming according to claim 6 or 7, wherein the molding die is made of carbon. A glass forming apparatus comprising: a molding die for glass forming according to any one of claims 1 to 9; and a heating means and a pressurizing means for the glass ingot. A glass forming method using the tenth item of the patent application scope A glass forming apparatus for accommodating a glass ingot in a molding die; heating and pressurizing the glass ingot by a heating means and a pressurizing means; and deforming the glass ingot after the deformation, by forming the glass ingot The difference between the linear expansion coefficient of the mold and the glass ingot and the load of the load, the side plate is relatively moved relative to the platen toward the outer side thereof, whereby the shearing force acts on the supporting member, and the supporting member is destroyed corresponding to the shearing force . A method for producing a photomask substrate, comprising the step of obtaining a glass molded body by using the glass forming method of claim 11 of the patent application.