JP2004307266A - Method and apparatus for forming quartz glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming quartz glass whose residual strain is little and which is homogeneous by controlling abnormal molding such as buckling when heating and pressure molding of a quartz glass block. <P>SOLUTION: The quartz glass block 25 is contained in a mold 15, heated and formed to be a specified shape by being pressurized between a moving pressure part 23 and an opposed part 18. The quartz glass block 25 is pressurized while the temperature of the pressure part 23 side is controlled to be higher than the opposed part 18 side in its temperature distribution. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a forming method and a forming apparatus for forming a uniform quartz glass into a predetermined shape by pressurizing while holding and heating quartz glass in a mold.
[0002]
[Prior art]
A projection exposure apparatus (or an optical lithography apparatus) is mainly used for transferring an integrated circuit pattern such as an IC or an LSI. The projection optical system used in this apparatus is required to have a wider exposure area and higher resolution over the entire exposure area as the integration of integrated circuits becomes higher. In order to improve the resolution of the projection optical system, the exposure wavelength is shortened or the numerical aperture (NA) of the projection optical system is increased.
[0003]
The exposure wavelength has been shortened from g-line (436 nm) to i-line (365 nm), KrF (248 nm) and ArF (193 nm) excimer lasers. In order to further increase the integration, methods of using an F ₂ (157 nm) excimer laser, an X-ray, and an electron beam as a light source are currently being studied. In this, a reduction projection exposure apparatus using F ₂ excimer laser, which can be made by utilizing the heretofore design concepts have been suddenly attracted attention.
[0004]
In general, optical glass used as an illumination optical system or a lens member of a projection optical system of a reduction projection exposure apparatus using a light source having a wavelength longer than the i-line has a sharp decrease in light transmittance in a wavelength region shorter than the i-line. In particular, in the wavelength region of 250 nm or less, almost no optical glass transmits light. Therefore, only quartz glass and calcium fluoride crystal can be used as a material of a lens constituting an optical system of a reduction projection exposure apparatus using an excimer laser as a light source. These two materials are indispensable materials for performing chromatic aberration correction in an imaging optical system of an excimer laser.
[0005]
A reticle is another important element for printing a circuit on a wafer in a reduction projection exposure apparatus. As a material used for this reticle, not only excimer laser durability but also thermal expansion due to heat generation of the substrate becomes a major problem. Therefore, a method called a direct method that has good durability and a small coefficient of thermal expansion (flame hydrolysis) A method for producing a transparent quartz glass by the method described above) is used.
[0006]
In the direct method, a combustible gas (oxygen-containing gas, for example, oxygen gas) and a combustible gas (hydrogen-containing gas, for example, hydrogen gas or natural gas) are mixed and burned in a quartz glass burner, and the center of the burner is burned. A high-purity silicon compound (for example, silicon tetrachloride gas) is diluted with a carrier gas (usually oxygen gas) as a raw material gas and ejected, and the raw material gas is reacted (hydrolyzed) by burning the surrounding oxygen gas and hydrogen gas. Reaction) to generate quartz glass fine particles, and the quartz glass fine particles are deposited on a target formed of an opaque quartz glass plate which is arranged below the burner and rotates, swings and pulls down, and simultaneously the oxygen gas In addition, a quartz glass ingot is obtained by melting and vitrification by the heat of combustion of hydrogen gas.
[0007]
According to this method, since a quartz glass ingot having a relatively large diameter is easily obtained, an optical member having a desired shape and size can be manufactured by cutting a block from the ingot.
[0008]
In recent years, in order to obtain an optical member having a large area, such as a large lens or reticle, or a large liquid crystal display, a preformed quartz glass block such as an ingot is formed into a flat shape by heating and pressing. A molding method for enlarging the area is used.
[0009]
In this molding method, while the quartz glass block is housed in a mold and heated, the molding is performed by pressing with a pressurizing plate, and then the mold is gradually cooled or further annealed to perform the annealing on the one facing surface. A molded article having a predetermined shape with an enlarged area can be obtained.
[0010]
As a method for performing such heat and pressure molding, for example, heat and pressure molding is performed to a temperature of 1700 ° C. or more in a helium gas atmosphere having an absolute pressure of 0.1 Torr or more and an atmospheric pressure or less in a graphite mold. Then, a method of rapidly cooling to 1100 to 1300 ° C is known. In addition, a method of press-molding at 1600 ° C. to 1700 ° C. using a graphite mold having a structure for relaxing stress caused by a difference in thermal expansion coefficient between quartz glass and a mold material of the mold (see Patent Document 1 below). ) Or a molding apparatus in which the graphite mold has a vertical structure of two or more divisions (see Patent Documents 2 and 3 below). Furthermore, there is also known a method in which a coating layer made of quartz powder is provided on the inner surface of a graphite mold and pressed at 1550 ° C. to 1700 ° C. (see Patent Document 4 below).
[0011]
[Patent Document 1]
Japanese Patent Publication No. 4-54626.
[0012]
[Patent Document 2]
JP-A-56-129621.
[0013]
[Patent Document 3]
JP-A-57-67031.
[0014]
[Patent Document 4]
JP-A-2002-22020.
[0015]
[Problems to be solved by the invention]
However, in the conventional heat and pressure molding, a quartz glass lump is held in a chamber heated to a predetermined temperature by a heater capable of uniformly heating, and the quartz glass is heated to a moldable temperature by holding the mold for a predetermined time. I was For this reason, when a cylindrical or prismatic quartz glass block is formed by pressing in the longitudinal direction, substantially the entire quartz glass block is uniformly heated to a moldable temperature and softened. A phenomenon in which a quartz glass block is deformed and broken at an intermediate portion or a lower portion, so-called buckling, may occur.
[0016]
However, when buckling occurs and is formed from the middle part or lower part of the quartz glass block, the buckling part becomes a boundary surface, many bubbles are generated, and the residual strain of the obtained quartz glass increases, It has been found that optical inhomogeneity is likely to occur.
[0017]
In particular, when forming large-sized lenses, mirrors, and optical members such as reticles required for batch exposure of a large area these days, a larger quartz glass lump is used to form a large molding apparatus in a chamber of a large-sized molding apparatus. Heating had to be carried out for a longer time, buckling was liable to occur, and optical inhomogeneity was likely to occur.
[0018]
In view of the above, the present invention provides a molding method and a molding apparatus capable of suppressing molding abnormalities such as buckling and molding uniform quartz glass with little residual strain when a quartz glass block is heated and pressed. The purpose is to:
[0019]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above problem, heats the quartz glass lump in a mold, and presses the quartz glass lump between the opposed part by moving a pressing unit. In the method of forming into a predetermined shape, the quartz glass block is pressurized by the pressurizing unit in a state where the temperature distribution of the quartz glass block is controlled to be higher at the pressurizing unit side than at the opposing unit side.
[0020]
According to a second aspect of the present invention, in addition to the configuration of the first aspect, the width of the temperature distribution of the quartz glass block is 5 ° C. or more and 50 ° C. or less.
[0021]
Further, the invention according to claim 3 is a mold having a hollow portion capable of accommodating a quartz glass lump, a pressing portion movably disposed in the hollow portion, and the quartz glass accommodated in the hollow portion. Heating means for heating the lump, and moving the pressurizing portion to the bottom side while heating the quartz glass lump by the heating means, thereby pressing the quartz glass lump to form a predetermined shape. The apparatus is characterized in that the heating means heats the pressurized portion side of the quartz glass block to a temperature higher than the bottom side of the mold.
[0022]
According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the heating means is disposed on a side surface of the mold, and independently generates a calorific value on the pressing portion side and the bottom portion side. And is configured to be adjustable.
[0023]
Further, the invention according to claim 5 is the bottom heater according to claim 3 or 4, wherein the heating means is disposed on a bottom surface side of the mold and heats a bottom portion of the quartz glass block. It is characterized by having.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described.
[0025]
FIG. 1 shows a molding apparatus according to this embodiment.
[0026]
This molding apparatus 10 is used to adjust the refractive index of an ingot of synthetic quartz glass manufactured from a silicon compound such as silicon tetrachloride, silane, or organosilicon as a raw material or a part thereof, or Ge, Ti, B, F, Al, or the like. From a synthetic quartz glass ingot to which a component to be changed is added or a quartz glass lump such as a part thereof, for example, a substrate for a reticle (photomask) such as a large-sized liquid crystal mask or a semiconductor mask, or a large-sized imaging optical system. This is an apparatus for forming a plate-like body having a wide surface such as a lens material and other large glass blocks.
[0027]
In the molding apparatus 10, a heat insulating material 12 provided over the entire inner wall of a metal vacuum chamber 11 and a plurality of carbon heaters 13 a and 13 b as heating means provided in vertical walls of the heat insulating material 12 are provided. A mold 15 having a hollow portion 21 is provided at a substantially central portion inside the vacuum chamber 11. Here, the carbon heaters 13a and 13b are each configured to be capable of adjusting the amount of heat generated independently, and are arranged vertically around the entire periphery of the side surface of the mold 15.
[0028]
The mold 15 includes a bottom 18 having a bottom plate 16 and a receiving plate 17, and a side wall 20 formed in a cylindrical shape on the top of the bottom 18. The hollow portion 21 is formed by the cylindrical side wall 20 and the bottom 18. Is formed.
[0029]
In the hollow portion 21, a top plate 23 as a pressing portion having a shape corresponding to the shape of the hollow portion 21 is disposed, and a pressing surface 23b (upper surface) of the top plate 23 is disposed outside the vacuum chamber 11. By pressing with a cylinder rod 26 of a hydraulic cylinder as a forming means, it is possible to move to the bottom portion 18 side of the mold 15 as an opposing surface.
[0030]
The hydraulic cylinder provided with the cylinder rod 26 is configured to move by being pressurized by adjusting the hydraulic pressure supplied from the outside, but is not shown in detail.
[0031]
The mold 15 and the top plate 23 have heat resistance and strength against the temperature and pressure at the time of forming the massive quartz glass 25, and hardly mix impurities even when contacting the massive quartz glass 25 at the time of molding. It is formed of a material, and here is entirely formed of graphite.
[0032]
Next, a case where the bulky quartz glass 25 is formed by the method of this embodiment using the forming apparatus 10 having the above-described configuration will be described. First, the mold 15 is formed by combining the bottom plate 16, the receiving plate 17, and the side wall 20 in the vacuum chamber 11. Then, a massive quartz glass 25 is arranged in the hollow portion 21 of the mold 15. In this embodiment, a synthetic quartz glass ingot is used as the bulk quartz glass 25. In order to shorten the lead time, before being housed in the hollow portion 21 of the mold 15, the preheating is performed at a temperature of less than 300 ° C. It is preferable to use one that has been used.
[0033]
Then, the top plate 23 is disposed above the massive quartz glass 25 housed in the hollow portion 21, and further, the pressing portion 23 a of the cylinder rod 26 of the hydraulic cylinder is brought into contact with the pressing surface 23 b of the top plate 23. I do. Then, the inside of the vacuum chamber 11 is replaced with an inert gas, and the pressure inside the vacuum chamber 11 is set to, for example, 1 × 10 ⁴ Pa to 1 × 10 ⁵ Pa.
[0034]
Next, the bulk quartz glass 25 accommodated in the mold 15 and the hollow portion 21 thereof is heated by the carbon heaters 13a and 13b. At the time of this heating, first, the carbon heaters 13a and 13b are caused to generate heat, and the inside of the vacuum chamber 11 is heated at a heating rate of 500 to 1000 ° C./hr. Then, the calorific value of the carbon heater 13a on the upper side of the mold 15, that is, on the top plate 23 side is increased, and the temperature of the massive quartz glass 25 on the top plate 23 side (ie, upper side) is increased to the receiving plate 17 side (that is, the upper side). , Lower part), the calorific values of the carbon heaters 13a and 13b are controlled.
[0035]
In this state, by keeping the inside of the massive quartz glass 25 sufficiently long, for example, for 15 to 45 minutes, the width of the temperature distribution of the massive quartz glass 25, that is, the top of the top plate 23 side The temperature difference between 25a and bottom surface 25b on the bottom 18 side of mold 15 can be set to 5 ° C or more and 50 ° C or less. Here, if the temperature distribution of the massive quartz glass 25 is less than 5 ° C., the sufficient buckling suppressing effect is reduced. On the other hand, if the temperature distribution is higher than 50 ° C., the sufficient buckling suppressing effect is obtained. Since the temperature gradient in the pressing direction of 25 is too large, the pressing deformation of the quartz glass 25 occurs in a narrow range, and as a result, the time required for the pressing deformation becomes long, and various problems occur. For example, contamination by impurities becomes large, and a cycle time required for one molding becomes long, thereby lowering production efficiency and further reducing homogeneity of refractive index.
[0036]
Furthermore, in this molding, it is preferable to raise the temperature of the whole quartz glass 25 to a molding temperature from the crystallization temperature to the softening point, specifically from 1570 ° C. to 1670 ° C. At the time of pressurizing the vicinity of the top 25a of the massive quartz glass 25 at the stage, it is sufficient that at least the top 25a side has reached the molding temperature.
[0037]
Then, while the massive quartz glass 25 is heated in this way, the cylinder rod 26 is moved downward by controlling and controlling the oil pressure to the hydraulic cylinder, and the top plate 23 is pressed by the pressing portion 26a of the cylinder rod 26. The pressing surface 23b is pressed. Accordingly, the top plate 23 moves in the pressing direction on the bottom portion 18 side of the mold 15, and the massive quartz glass 25 is pressed between the top plate 23 and the bottom portion 18 of the pressing surface 23 a.
[0038]
Then, since the quartz glass 25 has a higher temperature at the top 25a side than at the bottom section 25b side, the top section 25a is more easily deformed than the bottom section 25b side, and when pressed by the pressing surface 23a of the top plate 23, the top section 25a side Will be sequentially transformed.
[0039]
At this time, the top plate 23 can be more easily deformed from the top 25a side by setting the descending speed of the top plate 23 to, for example, 5 to 15 cm / min.
[0040]
Further, the pressure applied from the top plate 23 during molding is preferably such that the pressure of the top plate 23 is reduced in the early stage of molding and is set to the maximum pressing force in the final stage. the pressure in terms of per unit area of the pressing surface 23a of the 0.3~1.5Kg / cm ^2, at the final stage of molding can be 1.0~5.0Kg / cm ^2. With such a range, deformation can be easily performed from the top 25a side.
[0041]
Then, at the stage where the quartz glass 25 is formed into a plate having a predetermined shape, the pressing by the top plate 23 is completed. Thereafter, the plate-shaped quartz glass 25 is cooled while being placed in the mold 15, and the formed body is removed from the vacuum chamber 11 to complete the forming.
[0042]
As described above, when the massive quartz glass 25 is molded, the massive quartz glass 25 accommodated in the hollow portion 21 of the mold 15 is heated at a higher temperature than the top portion 25a of the top plate 13 side than the bottom portion 18 side of the mold 15. Since the heating is performed by the carbon heaters 13a and 13b so that the top plate 23 side of the massive quartz glass 25 is easily formed from the bottom 18 side, when the massive quartz glass 25 is pressed by the top plate 23 during molding, the top plate 23 It can be formed sequentially from the side. For this reason, the bulk quartz glass 25 in the hollow portion 21 is less likely to buckle during molding, and the residual distortion of the resulting plate-like quartz glass 25 can be suppressed, and a uniform plate-like body can be obtained.
[0043]
In this case, since the carbon heaters 13a and 13b whose heating values can be independently adjusted are arranged in the pressing direction on the side surface of the mold 15, the massive quartz glass housed in the hollow portion 21 of the mold 15 is provided. 25 is easily heated so as to form a temperature distribution in the pressing direction.
[0044]
In the first embodiment, an example in which the molding is performed at a temperature equal to or higher than the crystallization temperature and equal to or lower than the softening point is described. However, the molding temperature may be equal to or higher than the crystallization temperature of the quartz glass 25. It is also possible to mold at higher temperatures.
[0045]
Further, in the above description, an example is shown in which two carbon heaters 13a and 13b having different heating values are used as the heating means. However, three or more heaters can be arranged. In addition, one heater is arranged on the side surface of the mold 15 to partially vary the amount of heat generated, or one heater having a uniform amount of heat is used to shield the bottom surface 25b side with a shield plate or the like to heat the heater. It is also possible to vary the amount.
[0046]
[Embodiment 2]
In the molding apparatus according to the second embodiment, as shown in FIG. 2, a carbon heater 13 disposed on the side of the mold 15 on the top plate 23 side and a ring A bottom heater 27 for heating the bottom surface 25b of the massive quartz glass 25 buried in the shape is provided. The other configuration is the same as that of the first embodiment.
[0047]
Even in such a molding apparatus 10, by adjusting the amount of heat generated by the carbon heater 13 and the bottom heater 27, the top 25 a side of the massive quartz glass 15 is heated to be higher than the bottom 25 b side. Buckling can be suppressed in the bulk quartz glass 25 being formed.
[0048]
Moreover, when the bottom heater 27 for heating the bottom surface 25b of the quartz glass 25 is provided, the inside of the massive quartz glass 25 is easily heated, and the massive quartz glass 25 having a large cross section orthogonal to the pressing direction is provided. Even so, the inside can be easily heated and molding can be facilitated.
[0049]
In the second embodiment, the carbon heater 13 disposed on the side surface of the mold 15 is such that a uniform amount of heat is obtained over the entire surface. However, as shown in FIG. It is also possible to arrange a carbon heater.
[0050]
【Example】
Hereinafter, examples will be described.
[0051]
Example 1
Using a molding apparatus as shown in FIG. 1, a lump of quartz glass 25 made of a synthetic quartz glass ingot having a diameter of 50 cm and a height of 70 cm is converted to a plate-like quartz having a square shape of 100 cm on a side and a thickness of 13.7 cm. Glass 25 was formed.
[0052]
In this molding, after the pressure in the vacuum chamber 11 is reduced to 0.67 Pa by a vacuum pump, pure nitrogen gas is filled to a pressure of 10 kPa, and then the mass of quartz is increased at a heating rate of 400 ° C./hr. The temperature of the mold 15 at the portion corresponding to the top 25a of the glass 25 is 1640 ° C., the temperature of the mold 15 at the portion corresponding to the bottom portion 25b is 1620 ° C., and the distribution width is controlled to be 20 ° C. Then, it was kept for 40 minutes.
[0053]
At this time, the temperature of the mold 15 was measured by a two-color thermometer.
[0054]
Thereafter, the top plate 23 was pressed by the cylinder rod 26 at an initial load of 5 ton and a press speed of 1 mm / sec to form an ingot. When the press load became 25 tons, the pressurization was terminated and the system was cooled.
[0055]
Observation of distortion of the obtained plate-like body by the crossed Nicols method revealed no distortion due to buckling during molding.
[0056]
Example 2
Using a molding apparatus as shown in FIG. 2, the temperature of the mold 15 corresponding to the top 25a is 1650 ° C., the temperature of the mold 15 corresponding to the bottom 25b is 1600 ° C., and the distribution width is 50 ° C. A plate-shaped quartz glass 25 was formed in the same manner as in Example 1 except that the temperature was raised to be as follows.
[0057]
Observation of distortion of the obtained plate-like body by the crossed Nicols method revealed no distortion due to buckling during molding.
[0058]
Example 3
Except that the temperature of the mold 15 corresponding to the top 25a was 1650 ° C., the temperature of the mold 15 corresponding to the bottom 25b was 1550 ° C., and the distribution width was 100 ° C. A quartz glass 25 in the shape of a body was formed.
[0059]
Observation of distortion of the obtained plate-like body by the orthogonal crossed Nicols method showed that no distortion due to buckling during molding could be confirmed, but some contamination of impurities was observed compared to before molding. Was. In addition, deterioration in the homogeneity of the refractive index was recognized.
[0060]
Comparative Example 1
Except that one carbon heater having a size corresponding to the carbon heaters 13a and 13b is mounted, the same molding apparatus as that of FIG. 1 is used, and the temperature is raised by uniformly heating the carbon heater. A plate-shaped quartz glass was formed in the same procedure as in 1. During this molding, the temperature of the mold 15 corresponding to the top 25a was 1670 ° C., the temperature of the mold 15 corresponding to the bottom 25b was 1667 ° C., and the distribution width was 3 ° C.
[0061]
When the obtained plate-like body was observed for distortion by the orthogonal crossed Nicols method, streak-like distortion caused by buckling during molding was confirmed. In addition, a number of air bubbles were continuously formed in the vicinity of the streak-like strain generation site. This part is assumed to be a buckling part.
[0062]
Comparative Example 2
A plate-like quartz glass was formed in the same manner as in Example 1 except that the temperature of the mold 15 at the portions corresponding to the top portion 25a and the bottom portion 25b was both 1630 ° C.
[0063]
When the obtained plate-like body was observed for distortion by the crossed Nicols method, streak-like distortion caused by buckling during molding was confirmed. Further, a large number of air bubbles connected in a plane were generated in the vicinity of the streak-like strain generation site as in Comparative Example 1.
[0064]
【The invention's effect】
As described in detail above, according to the first aspect of the present invention, the temperature distribution of the quartz glass block is adjusted such that the temperature of the pressurizing section is higher than that of the opposing section and pressurized. The pressure portion side is more easily formed than the opposing portion side, and it is possible to form the pressure portion in order from the pressure portion side. Therefore, buckling of the quartz glass lump is less likely to occur during molding, and it is easy to uniformly form quartz glass while suppressing residual strain.
[0065]
Furthermore, according to the second aspect of the present invention, since the width of the temperature distribution of the quartz glass block is 5 ° C. or more and 50 ° C. or less, it is possible to more reliably suppress buckling during molding.
[0066]
According to the third aspect of the present invention, the heating means for heating the quartz glass block accommodated in the hollow portion of the mold heats the pressurized portion side of the quartz glass block to be higher than the bottom side. Therefore, when the pressing portion is moved to the bottom side of the mold at the time of molding and the quartz glass block is pressed, it is possible to form the quartz glass block in order from the pressing portion side. For this reason, the quartz glass lump is unlikely to buckle in the hollow portion of the mold during the molding, and the residual distortion of the quartz glass molded into a predetermined shape is suppressed, so that the molded body can be easily homogeneously molded.
[0067]
Furthermore, according to the invention as set forth in claim 4, since the heating means is arranged on the side surface of the mold and the amount of heat generation can be adjusted independently on the pressing portion side and the bottom portion side, the mold It is easy to adjust the temperature of the quartz glass block accommodated in the hollow portion.
[0068]
According to the fifth aspect of the present invention, since the bottom heater that is arranged on the bottom surface side of the mold and heats the bottom portion of the quartz glass block is provided, it is easy to heat the inside of the quartz glass block, Even in the case of a quartz glass block having a large cross section orthogonal to the pressing direction, the inside can be heated and molding is easier.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a part of a molding apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a schematic longitudinal sectional view showing a part of a molding apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Forming apparatus 11 Vacuum chamber 13, 13a, 13b Carbon heater 15 Mold 18 Bottom part 20 Side wall part 21 Hollow part 23 Top plate (pressure plate)
25 Quartz glass block 26 Cylinder rod (forming means)
27 Bottom heater

Claims (5)

In the method of housing the quartz glass block in a mold and heating and moving the pressing section, the quartz glass block is pressed between the opposing section and formed into a predetermined shape,
A method of forming quartz glass, wherein the quartz glass block is pressurized by the pressurizing section while controlling the temperature distribution of the bulk of the quartz glass so that the temperature of the pressurizing section is higher than that of the opposing section. The method for forming quartz glass according to claim 1, wherein the width of the temperature distribution of the quartz glass block is 5 ° C or more and 50 ° C or less. A mold having a hollow portion capable of accommodating a quartz glass lump, a pressurizing portion movably disposed in the hollow portion, and heating means for heating the quartz glass lump accommodated in the hollow portion, While heating the quartz glass block by the heating means, by moving the pressing unit to the bottom side of the mold, the quartz glass block is pressurized and formed into a predetermined shape,
An apparatus for forming quartz glass, wherein the heating means heats the pressurized portion side of the quartz glass block to be higher in temperature than the bottom portion side. 4. The quartz according to claim 3, wherein the heating unit is disposed on a side surface of the mold, and is configured to be capable of independently adjusting a calorific value on the pressing unit side and the bottom side. 5. Glass forming equipment. The quartz glass forming apparatus according to claim 3, wherein the heating unit includes a bottom heater arranged on a bottom side of the mold to heat a bottom portion of the quartz glass block.

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