JP3591540B2 - Synthetic quartz glass manufacturing equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention manufactures a synthetic quartz glass optical member that can be used as an optical element for ultraviolet lithography by preventing silica fine particles and the like from adhering to a synthetic quartz glass manufacturing apparatus, particularly a furnace frame or an exhaust means of the synthetic quartz glass manufacturing apparatus. To a manufacturing apparatus.
[0002]
[Prior art]
In recent years, high purity synthetic quartz glass has been used for synthetic quartz glass as an optical element for ultraviolet lithography in order to achieve high transmittance in the ultraviolet region. The flame hydrolysis method is known as one of the useful production methods.
The flame hydrolysis method is a synthesis method in which a silicon compound, which is a raw material of synthetic quartz glass , is supplied from a burner for synthesizing quartz glass into an oxyhydrogen flame, and a hydrolysis reaction is performed to synthesize and deposit silica fine particles. It is.
[0003]
Conventionally, by this flame hydrolysis method, silica particles are deposited on the target while rotating the target about the vertical axis, and synthesized while lowering the distance of the synthetic surface from the burner for synthesizing quartz glass according to the deposition rate We have been manufacturing quartz glass.
For the furnace frame and the exhaust means of the quartz glass manufacturing apparatus, a metal whose shape can be easily obtained by cutting and processing in producing these apparatuses has been used.
[0004]
[Problems to be solved by the invention]
However, in the case of the manufacturing apparatus using the above-mentioned metal, since the furnace frame and the exhaust gas have an acidic atmosphere, there is a problem that corrosion occurs and it becomes impossible to continue the synthesis. Further, regarding the furnace frame, there is a possibility that impurities may be mixed into the synthesized quartz glass. Furthermore, since the furnace frame and the exhaust means are exposed to a high temperature of about 700 ° C., there has been a problem that the synthesis cannot be continued due to deformation of the metal.
[0005]
In order to prevent these problems, it has been found that exposing the metal part in the furnace frame and the exhaust means is a negative factor in continuing the synthesis of quartz glass.
[0006]
[Means for Solving the Problems]
In light of the above problems, as a result of intensive research on metal parts exposed to an acidic atmosphere and high temperatures, the parts exposed to these acidic atmospheres and high temperatures have a heat-resistant lining that is not attacked by corrosive gas. I found out how to apply it and tried to solve the problem.
[0007]
Therefore, a furnace composed of a furnace frame and a refractory, a target for forming an ingot installed inside the furnace, a burner for synthesizing quartz glass installed with its tip directed toward the target, and a stack on the target An apparatus for producing synthetic quartz glass, comprising means for preventing corrosion of a furnace frame in an apparatus for producing synthetic quartz glass comprising exhaust means for exhausting silica particles which have not been removed (claim 1). Do.
[0008]
Similarly, there is provided a synthetic quartz glass manufacturing apparatus (claim 2) characterized in that a means for preventing corrosion of a metal portion in an exhaust means is provided.
[0009]
[Action]
In an open type synthetic quartz glass manufacturing apparatus, the furnace temperature up to a refractory is about 1500 ° C. and the synthetic surface temperature exceeds 1900 ° C. Silica fine particles not deposited on the target for forming the ingot and gas generated by the hydrolysis reaction (hereinafter, referred to as exhaust gas) are carried as exhaust gas to the abatement apparatus through an exhaust pipe (exhaust means). At this time, the inner surface temperature of the furnace frame and the evacuation means varies depending on the location, but reaches about 700 ° C. Since the exhaust gas contains acidic HCl or the like, the furnace frame and the exhaust means are filled with corrosive gas.
[0010]
The manufacturing apparatus of the present invention uses a material that is resistant to corrosion and has high heat resistance, that is, glass or ceramic, as a lining material for metal, for the furnace frame and the exhaust means. Alternatively, a carbon material is used.
Further, as the exhaust gas passes through the exhaust means, its temperature decreases, and becomes a low temperature of 80 ° C. or less where it is not necessary to take any thermal measures. Alternatively, the temperature of the exhaust path is lowered by water spraying inside or outside the exhaust path, or by forming the exhaust path in a double structure and cooling the space between the two. For this low temperature part, vinyl chloride which is excellent in workability and corrosion resistance and can reduce the cost is used. Also, in areas where the inside needs to be observed, use transparent polycarbonate, acrylic or transparent vinyl chloride. A Teflon-based resin having excellent corrosion resistance and heat resistance and elasticity is used as the sealing material and gasket.
[0011]
When glass is used as the lining material, Pyrex glass is mainly used, but other glasses can be used as long as they have high affinity for metal and high heat resistance. Also, even if the affinity with metal is low, by applying a multilayer structure lining, for example, a furnace frame that is highly resistant to heat and acid, a small coefficient of thermal expansion, and thermal shock of quartz glass. Alternatively, exhaust means can be obtained. However, since Pyrex glass is actually the most balanced in terms of cost, it is used.
[0012]
Examples of the ceramic lining material include a hydrated hardening composition containing ammonium phosphate, magnesium oxide and crystalline silica. Lining with ceramics has a great effect on improving heat resistance. When alumina or alumina-silica ceramic fiber is used as the lining material, the heat insulating property can be improved.
[0013]
Carbon is inferior in heat resistance as compared with other materials, but is excellent in workability. Therefore, according to the present invention, it is possible to continuously produce synthetic quartz glass without repairing the production apparatus , which is not possible with a metal configuration.
In addition, the silica fine particles adhere to the metal furnace frame and the exhaust means in the exhaust gas containing HCl, causing not only a problem that a hole or the like is opened due to corrosion, but also rust and a high friction coefficient. Further, the silica fine particles adhered to the surface to form a cheap surface.
[0014]
As described above, when the silica fine particles adhere and the exhaust path narrows, it becomes difficult to control the exhaust flow rate. When this phenomenon occurs, synthetic quartz glass with a highly uniform refractive index gradient in the direction perpendicular to the growth direction of the ingot and a stable refractive index distribution in the radial direction is used to vary the displacement from the furnace. Although it was difficult to obtain, that is, to reduce the variation of the refractive index in the ingot, according to the present invention, by using a glass or ceramic lining, carbon material excellent in corrosive, these silica fine particles Can be prevented, and quartz glass can be synthesized without affecting the quality.
[0015]
【Example】
[Comparative Example 1]
As a synthetic quartz glass manufacturing apparatus, a metal furnace frame was placed on a cast hearth plate, and an exhaust port was provided therein. The refractory has an inner volume of 126 l, and the lower part is open type for both the hearth plate and the refractory. Using such an apparatus, a silicon compound used as a raw material is heated and vaporized in the range of 60 to 100 ° C., and is flame-hydrolyzed from the center of a quartz glass burner together with an oxyhydrogen flame and sprayed onto a target. Then, the silica fine particles are synthesized and deposited, and the exhaust gas such as the silica fine particles not deposited on the target is guided to the abatement apparatus through the exhaust pipe which receives the exhaust port. At this time, the furnace frame and the exhaust pipe were rusted due to the influence of the exhaust gas, and a hole was formed in the exhaust pipe in about 10 days in the ordinary synthesis, so that synthesis could not be continued. In addition, when a durability test was performed on the furnace frame, it was found that a hole was opened in about 30 days and synthesis could not be continued. Further, stainless steel bolts were used as fixing bolts for the flange portion of the abatement apparatus. However, rust occurred in about 30 days, requiring replacement of the bolts, and opening and closing the flanges became very difficult.
[Example 1]
In the synthetic quartz glass manufacturing apparatus of Comparative Example 1, a ceramic lining was provided on the inside of the furnace frame, a glass lining pipe was used for an exhaust pipe, and acrylic was used for bolts of a flange portion of the detoxification apparatus, and the same synthesis was performed. (Figure 1).
[0016]
In such a case, even if the synthesis is performed continuously for 30 days, no holes are formed in the furnace frame and the exhaust pipe, and no rust is generated at all in contrast to the stainless steel bolts, so that the manufacturing apparatus can be continuously operated. there were. Also, the replacement of bolts is almost unnecessary.
According to this example, when the furnace frame and the exhaust means were subjected to glass and ceramic lining and a durability test was performed, it was confirmed that the furnace frame and the exhaust means were extremely excellent in corrosion resistance without any holes. Was. Further, since holes were not formed in the furnace frame and the exhaust pipe, the exhaust gas was not released to the atmosphere, and the safety was extremely enhanced.
[0017]
It was also confirmed that the same effect was obtained when vinyl chloride and polycarbonate were used for the flange portion of the abatement system where the exhaust gas temperature was low.
The effects of the present invention are not limited to the embodiments.
[0018]
【The invention's effect】
As described above, by applying the above-described means for preventing corrosion to the furnace frame and exhaust means associated with the synthetic quartz glass manufacturing apparatus according to the present invention, the durability of the manufacturing apparatus is increased and replacement of each part is almost impossible. This has led to significant cost savings. Further, according to the present invention, it is possible to prevent the silica fine particles from adhering to the exhaust means, so that high-quality synthetic quartz glass can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a synthetic quartz glass manufacturing apparatus used in Example 1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Burner 2 Target 3 Ingot 4 Hearth 5 Ceramic-lined furnace frame 6 Refractory 7 Detoxifier 8 Exhaust fan 9 Flange 10 Glass-lined pipe

Claims (1)

A furnace composed of a furnace frame and a refractory, a target for forming an ingot installed inside the furnace, a burner for synthesizing quartz glass installed with its tip directed to the target, and the target was not deposited on the target. In a synthetic quartz glass manufacturing apparatus comprising an exhaust means for exhausting silica fine particles, a means for preventing corrosion made of glass lining is provided at a portion of the furnace frame and the exhaust means at a high temperature of 80 ° C. or more, and a temperature of 80 ° C. An apparatus for producing synthetic quartz glass, comprising means for preventing corrosion of vinyl chloride, polycarbonate or acrylic in the following parts:

Images