JP2006327916A - Manufacturing device for quartz glass, and manufacturing method for quartz glass using the same device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing device for quartz glass, which can sufficiently uniformly control the amount of a liquid raw material fed to a vaporizer, sufficiently prevents the contamination of foreign materials into the quartz glass and the generation of bubbles or striae, and which efficiently and securely produces quartz glass having a sufficiently high transmittance of a light with a wave length within an ultraviolet region and having excellent homogeneity, and to provide a manufacturing method for quartz glass using the manufacturing device. <P>SOLUTION: The manufacturing device for quartz glass is provided with a liquid raw material cylinder 1, a piping 2 for a liquid raw material, one end of which is connected to the liquid raw material cylinder 1, a vaporizer 3, which is connected to the other end of the piping 2 for liquid raw material, a piping 4 for a raw material gas, one end of which is connected to the vaporizer 3, a burner 10, which is connected to the other end of the piping 4 for raw material gas, and a synthetic furnace 11, inside which the burner 10 is arranged. A flow rate control device 20 is mounted on the piping 2 for a liquid raw material, and further a pressure fluctuation buffering mechanism 21 is arranged between the liquid raw material cylinder 1 and the flow rate control device 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for producing quartz glass and a method for producing quartz glass using the apparatus.

  2. Description of the Related Art Conventionally, an exposure apparatus called a stepper is used in an optical lithography technique that exposes and transfers a fine pattern of an integrated circuit onto a semiconductor substrate or the like in the process of manufacturing a semiconductor device. In such an exposure apparatus, the wavelength of the light source is shortened from i-line (365 nm) to KrF excimer laser (248 nm) and further to ArF (193 nm) excimer laser as high-scale integrated circuits (LSIs) are highly integrated. Is underway.

  In addition, as an optical member such as a lens, mirror, or reticle of an illumination optical system or projection optical system of an exposure apparatus using a light source having a wavelength shorter than i-line, conventional optical glass has a wavelength shorter than that of i-line. Since the transmittance decreases, fluoride single crystals such as fluorite and quartz glass are used. Such quartz glass is required to have high transmittance of light having a wavelength in the ultraviolet region and high homogeneity of refractive index. In order to realize such a requirement, it is necessary to suppress the impurity concentration in the quartz glass in order to increase the transmittance, and in order to increase the homogeneity of the refractive index of the quartz glass, It is necessary to suppress a significant composition distribution (foreign matter, striae, etc.). Therefore, as a method for producing quartz glass, generally, a silicon compound as a raw material of quartz glass (a carrier gas for sending out the silicon compound is used at the same time), a support combustion gas and a combustion gas (for example, an oxygen-containing gas). , Hydrogen-containing gas) from the burner to form quartz glass fine particles (soot) in a flame, and then deposit the soot on a target made of a heat-resistant substrate, and melt and vitrify the quartz glass. Flame hydrolysis methods to obtain ingots (also referred to as “direct method” or “direct flame hydrolysis method”) have been employed. As a method and apparatus for producing quartz glass by such a flame hydrolysis method, a technique using a silicon compound in a liquid state as a raw material has been developed.

For example, in Japanese Patent Application Laid-Open No. 2001-48551 (Patent Document 1), a burner is provided that is opposed to a target disposed in a melting furnace and hydrolyzes a silicon compound in an oxygen-hydrogen flame, and a mass flow is applied to the burner. A baking tank that is communicated via the controller and vaporizes the liquid silicon compound (liquid raw material); a main tank that is communicated with the baking tank and contains the liquid silicon compound and is supplied with a pressurizing gas; and the baking A quartz having a weight detection device for detecting the weight of the silicon compound accommodated in the tank, and a flow rate control device which is controlled based on an output of the weight detection device and is provided between the baking tank and the main tank. An apparatus for producing glass is disclosed. In the manufacturing apparatus, by controlling the flow rate control device based on the output of the weight detection device, the silicon compound is supplied from the baking tank to the burner and the silicon compound is reduced from the main tank to the baking tank. To be supplied. In Japanese Patent Application Laid-Open No. 11-116247 (Patent Document 2), a raw material liquid composed of a silicon compound is introduced into a vaporizer, and a raw material gas obtained by vaporizing the liquid raw material in the vaporizer is introduced into a synthesis furnace. A method for producing quartz glass is disclosed in which the amount of the liquid material introduced into the vaporizer is controlled by a liquid mass flow meter. However, in the conventional quartz glass manufacturing apparatus and manufacturing method described in Patent Documents 1 and 2, it is not possible to sufficiently prevent foreign matters from being mixed into the quartz glass and the generation of bubbles and striae. The transmittance and homogeneity with respect to ultraviolet rays were not yet satisfactory.
JP 2001-48551 A JP-A-11-116247

  The present invention has been made in view of the above-described problems of the prior art, and the supply amount of the liquid raw material supplied to the vaporizer can be controlled sufficiently uniformly. Quartz that sufficiently prevents the generation of bubbles and striae, enables the efficient and reliable production of quartz glass with sufficiently high transmittance for light having a wavelength in the ultraviolet region and excellent in homogeneity It aims at providing the manufacturing apparatus of glass, and the manufacturing method of quartz glass.

  As a result of intensive studies to achieve the above object, the present inventors have found that the initial transmittance and homogeneity of quartz glass when irradiated with ultraviolet rays, particularly vacuum ultraviolet rays such as an ArF excimer laser having a wavelength of 193 nm, are obtained. When the quartz glass is produced by the flame hydrolysis method, contamination of the foreign material in the quartz glass and the occurrence of bubbles and striae cause unevenness in the amount of liquid raw material supplied to the vaporizer. We found out that it is caused by. And in the quartz glass manufacturing apparatus used in the conventional flame hydrolysis method, the flow rate control device such as a mass flow meter was used to control the supply amount of the liquid raw material to the vaporizer. If the pressure of the liquid source in the liquid source piping fluctuates in a pulsating manner only with the device, for example, pressure fluctuation of the pumping gas, opening / closing of the air valve when switching the source cylinder, melting of the pumping gas or generation of bubbles due to temperature change As a result, it was found that the supply amount of the liquid raw material is uneven because it cannot cope with the case where the pressure of the liquid raw material fluctuates in a pulsed manner. In addition, the non-compressibility property of the liquid material greatly affects such unevenness in the supply amount. The reason for this is that in the case of gas raw materials, the gas is compressible, so it is easy to absorb subtle fluctuations in pressure caused by some reason, but in the case of liquid raw materials, the liquid is uncompressed. This is because it cannot absorb subtle fluctuations in pressure. Further, when unevenness occurs in the supply amount of the liquid raw material to the vaporizer, unevenness also occurs in the supply amount of the raw material gas supplied from the vaporizer to the burner. Then, due to the uneven supply amount of the raw material gas, the amount of quartz glass fine particles generated in the flame (reaction part) ejected from the burner changes, and the lamination rate of the quartz glass becomes non-uniform. For this reason, a microscopic composition distribution occurs in the obtained quartz glass, and changes such as striae and bubbles occur. Therefore, as a result of further earnest research, the present inventors have provided a flow rate control device such as a mass flow meter in the quartz glass manufacturing device, and further provided a pressure fluctuation buffering mechanism between the flow rate control device and the liquid cylinder. By providing, the supply amount of the liquid raw material supplied to the vaporizer can be controlled sufficiently uniformly, and it is possible to sufficiently prevent foreign substances from entering the quartz glass and the generation of bubbles and striae, and the wavelength can be reduced. It has been found that quartz glass having a sufficiently high transmittance of light in the ultraviolet region and excellent in homogeneity can be produced efficiently and reliably, and the present invention has been completed.

That is, the quartz glass manufacturing apparatus of the present invention includes a liquid source cylinder, a liquid source pipe having one end connected to the liquid source cylinder, a vaporizer connected to the other end of the liquid source pipe, A quartz glass manufacturing apparatus comprising: a raw gas pipe having one end connected to a vaporizer; a burner connected to the other end of the raw gas pipe; and a synthesis furnace in which the burner is disposed. ,
The liquid source pipe is provided with a flow rate control device, and a pressure fluctuation buffer mechanism is further provided between the liquid source cylinder and the flow rate control device.

  In the quartz glass manufacturing apparatus of the present invention, it is preferable that the pressure fluctuation buffer mechanism controls the pressure fluctuation of the liquid raw material in the liquid raw material pipe within ± 0.05 MPa.

  In the quartz glass manufacturing apparatus of the present invention, the pressure fluctuation buffer mechanism is filled with a container provided with an inlet and an outlet for liquid raw material, a liquid chamber into which the liquid raw material flows, and a pressure fluctuation buffer fluid. It is preferable that the pressure fluctuation buffer chamber is provided with a diaphragm that partitions the inside of the container, and a pressure fluctuation buffer fluid filled in the pressure fluctuation buffer chamber.

  Further, in the quartz glass manufacturing apparatus of the present invention, the pressure fluctuation buffer mechanism is a pressure fluctuation buffer in which one or more pinholes having an inner diameter equal to or less than 1/4 times the inner diameter of the liquid raw material pipe are formed. It is preferable that the pressure fluctuation buffer plate is provided in the liquid raw material pipe, and the inner diameter of the liquid raw material pipe is between the pressure fluctuation buffer plate and the liquid raw material cylinder. It is more preferable to further include an expansion portion having an inner diameter of 5 times or more.

In addition, a liquid source supply step of supplying a liquid source made of a silicon compound to the vaporizer through the liquid source pipe, and a source gas obtained by vaporizing the liquid source with the vaporizer is supplied to the burner through the source gas pipe. The raw material gas supply step, the raw gas, the oxygen-containing gas, and the hydrogen-containing gas are ejected toward the target provided in the synthesis furnace by the burner, and quartz glass is formed on the target by a flame hydrolysis reaction. A method for producing quartz glass including a quartz glass forming step to be formed,
In the liquid source supply step, the pressure fluctuation of the liquid source in the liquid source pipe is controlled within ± 0.05 MPa.

  In the method for producing quartz glass of the present invention, it is preferable that the flow rate fluctuation of the liquid material in the liquid material pipe is controlled within ± 0.01 g / min in the liquid material supply step.

  According to the present invention, the supply amount of the liquid raw material supplied to the vaporizer can be controlled sufficiently uniformly, and sufficiently prevent the occurrence of foreign substances and bubbles and striae in the quartz glass, A quartz glass production apparatus and a quartz glass production method capable of efficiently and reliably producing quartz glass having sufficiently high transmittance for light having a wavelength in the ultraviolet region and excellent in homogeneity. It becomes possible to provide.

  Hereinafter, preferred embodiments of a quartz glass production apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing the configuration of a preferred embodiment of the quartz glass manufacturing apparatus of the present invention. The quartz glass manufacturing apparatus shown in FIG. 1 includes a liquid source cylinder 1, a liquid source pipe 2 having one end connected to the liquid source cylinder 1, and a vaporizer 3 connected to the other end of the liquid source pipe 2. A raw material gas pipe 4 having one end connected to the vaporizer 3, a burner 10 connected to the other end of the raw material gas pipe 4, and a synthesis furnace 11 in which the burner 10 is disposed. The liquid raw material pipe 2 and the raw material gas pipe 4 are each covered with a heat insulating pipe 5, and the liquid raw material cylinder 1 is covered with a heat insulating member 6.

  The synthesis furnace 11 in which the burner 10 is disposed is surrounded by a refractory 12, and a target 13 is disposed in a region covered with the refractory 12. The burner 10 is disposed on the axis of the synthesis furnace 11 so as to radiate a flame facing the target 13 disposed in the synthesis furnace 11. The target 13 is connected to a stage 14 having a rotation mechanism and a swing mechanism, and the stage 14 is connected to a vertical mechanism (not shown). Since the target 13 can be rotated, oscillated, and lowered at regular intervals by such a rotating mechanism and oscillating mechanism and an up-and-down mechanism, the upper position of the quartz glass 15 can be kept constant during the manufacturing process. .

  The liquid source pipe 2 is provided with a flow rate control device 20, and further, a pressure fluctuation buffer mechanism 21 is provided between the liquid source cylinder 1 and the flow rate control device 20.

  Further, the quartz glass manufacturing apparatus shown in FIG. 1 includes a carrier gas pipe 22, a support gas pipe 23 for supplying a support gas (eg, oxygen) other than the raw material gas, and a combustible gas (eg, hydrogen). And a combustible gas pipe 24 for supplying gas. One end of such a carrier gas pipe 22 is connected to the vaporizer 3, and one end of each of the support gas pipe 23 and the combustible gas pipe 24 is connected to the burner 10. A gas mass flow meter 25 is installed in the carrier gas pipe 22. Further, the quartz glass manufacturing apparatus shown in FIG. 1 includes a pressurized gas pipe 26 for supplying a pressurized gas to the liquid source cylinder 1, and one end of the pressurized gas pipe 26 is connected to the liquid source cylinder 1. ing. Further, a liquid source 27 is supplied to the liquid source cylinder 1.

  FIG. 2 is a schematic longitudinal sectional view showing a configuration of a preferred embodiment of the pressure fluctuation buffer mechanism 21 according to the present invention. The pressure fluctuation buffer mechanism 21 shown in FIG. 2 includes a container 32 provided with an inlet 30 and an outlet 31 for a liquid material, a liquid chamber 33 into which the liquid material flows, and a pressure fluctuation buffer chamber in which the pressure fluctuation buffer fluid is filled. 34, a diaphragm 35 for partitioning the inside of the container 32, and a pressure fluctuation buffer fluid filled in the pressure fluctuation buffer chamber 34.

  Such a pressure fluctuation buffer fluid is not particularly limited, and examples thereof include gases such as nitrogen gas, helium gas, and air, and liquids such as glycerin, water, and silicone oil. In the present embodiment, nitrogen gas is used as such a pressure fluctuation buffer fluid. Such pressure fluctuation buffer fluid has compressibility. Therefore, the pressure fluctuation buffer chamber 34 covered with the diaphragm 35 contracts due to the pressure fluctuation of the liquid raw material 27 flowing into the liquid chamber 33 and can absorb the subtle fluctuation of the pressure of the liquid raw material 27. Therefore, in this embodiment, by using the pressure fluctuation buffer mechanism 21 shown in FIG. 2, even if the pressure of the liquid raw material fluctuates in a pulse manner, the fluctuation of the pressure can be controlled.

  As such a pressure fluctuation buffer mechanism 21, the pressure fluctuation of the liquid raw material 27 in the liquid raw material pipe 2 can be controlled within ± 0.05 MPa (more preferably within ± 0.03 MPa). Is preferably used. If the range of such pressure fluctuation is out of the range of ± 0.05 MPa or less, it is not possible to sufficiently prevent the occurrence of foreign matters and striae in the resulting quartz glass, and the transmittance of the quartz glass And the homogeneity tends to decrease. Further, such a pressure fluctuation buffer mechanism 21, coupled with the flow rate control device 20, can control the flow rate fluctuation of the liquid raw material 27 within ± 0.01 g / min.

  Further, such a pressure fluctuation buffer mechanism 21 is provided at a position between the liquid source cylinder 1 and the flow rate control device 20. Thus, the reason why the pressure fluctuation buffer mechanism 21 is provided between the liquid material cylinder 1 and the flow rate control device 20 is that the pressure fluctuation on the upstream side of the flow rate control device 20 causes the flow rate fluctuation. is there.

  In the present embodiment, an accumulator (manufactured by Nippon Accumulator Co., Ltd., trade name “HN-N25KG-LL1-PVC”) is used as such a pressure fluctuation buffer mechanism 21.

  Moreover, in this embodiment, as the flow control device 20, a liquid mass flow meter (manufactured by Nippon Aera Co., Ltd., trade name “LX-1200”, specification: full scale (FS) 10 g / min, minimum control flow rate 3% FS, Accuracy ± 1% FS, operating temperature 15 to 35 ° C.) is used.

  Next, the liquid raw material 27 will be described. As the liquid raw material 27, a silicon compound having a boiling point of 50 ° C. to 200 ° C. (more preferably 70 ° C. to 130 ° C.) can be suitably used. When the boiling point is less than 50 ° C., the raw material is easily vaporized and difficult to handle, and bubbles tend to be easily generated in the liquid raw material 27 in the liquid raw material pipe 2, while the temperature exceeds 200 ° C. In the raw material gas pipe 4 for introducing the raw material gas into the synthesis furnace 11, the temperature of the raw material gas tends to be lower than the boiling point and easily reliquefied. Moreover, as such a silicon compound, it is more preferable to use alkoxysilane, alkylcyclosiloxane, or alkylsiloxane. In the present embodiment, octamethylcyclotetrasiloxane is used as such a liquid raw material 27.

  In the following, a quartz glass manufacturing method using the quartz glass manufacturing apparatus shown in FIG. 1 suitable for carrying out the quartz glass forming method of the present invention will be described.

  Such a method for producing quartz glass basically includes a liquid source supply step (A) for supplying the liquid source 27 to the vaporizer 3, a source gas supply step (B) for supplying source gas to the burner, And a quartz glass forming step (C) for forming quartz glass by a flame hydrolysis reaction. The temperature of the liquid raw material 27 used when manufacturing quartz glass is not particularly limited, but is set to room temperature in the present embodiment.

  First, the liquid raw material supply step (A) will be described. In the liquid source supply step (A), first, a liquid source 27 made of a silicon compound is supplied to the liquid source cylinder 1. The pressurized gas is supplied into the liquid source cylinder 1 in which the liquid source 27 is stored through the pressurized gas pipe 26. When the pressurized gas is supplied into the liquid source cylinder 1 in this way, the liquid source 27 is pushed out from the liquid source cylinder 1 and flows into the liquid source pipe 2. As such a pressure-feed gas, it is preferable to use a gas that is difficult to dissolve in the liquid material. In this embodiment, helium gas is used.

  Next, the liquid material 27 that has flowed into the liquid material pipe 2 passes through the pressure fluctuation buffer mechanism 21. In the pressure fluctuation buffer mechanism 21, the liquid raw material 27 flows into the liquid chamber 33 from the supply port 30, and the pressure fluctuation buffer chamber 34 contracts due to fluctuations in the pressure of the liquid raw material flowing into the liquid chamber 33. In the pressure fluctuation buffer mechanism 21, the pressure of the liquid raw material is pulsated due to such contraction of the pressure fluctuation buffer chamber 34 due to the opening and closing of the air valve at the time of changing the raw material cylinder, the melting of the pumped gas, the generation of bubbles due to the temperature change, and the like. Even when the pressure fluctuates, subtle fluctuations in pressure can be absorbed. Therefore, the pressure fluctuation of the liquid raw material 27 is reduced by passing through the pressure fluctuation buffer mechanism 21. Then, the liquid raw material whose pressure fluctuation is controlled by the pressure fluctuation buffer mechanism 21 flows again into the liquid raw material pipe 2 through the discharge port 31.

  In this embodiment, the pressure fluctuation of the liquid raw material 27 is controlled within ± 0.05 MPa. By controlling the pressure fluctuation of the liquid raw material 27 within ± 0.05 MPa in this way, it becomes possible to sufficiently prevent foreign matter from entering the quartz glass and the generation of bubbles and striae. Quartz glass having high transmittance and excellent homogeneity can be produced efficiently and reliably.

  Further, the liquid raw material 27 that has passed through the pressure fluctuation buffer mechanism 21 and again flows into the liquid raw material pipe 2 passes through the flow rate control device 20 and is supplied to the vaporizer 3. In such a flow control device 20, the supply amount of the liquid raw material 27 to the vaporizer 3 is controlled. In the present embodiment, the pressure fluctuation of the liquid raw material 27 that has flowed into the flow control device 20 is already sufficiently controlled. Moreover, in this embodiment, generation | occurrence | production of the bubble in the liquid raw material by a temperature change is prevented by making temperature of the liquid raw material used into room temperature lower than the boiling point. Therefore, the flow rate fluctuation of the liquid raw material 27 can be sufficiently controlled by the flow rate control device 20.

  Thus, in the present embodiment, the flow rate fluctuation of the liquid raw material 27 is controlled within ± 0.01 g / min by using the pressure fluctuation buffer mechanism 21 and the flow rate control device 20. When such flow rate fluctuations are out of the range of ± 0.01 g / min, it is not possible to sufficiently prevent the introduction of foreign matters and striae, and the transmittance and homogeneity of the resulting quartz glass are lowered. There is a tendency.

  In addition, in this way, the feed gas to the synthesis furnace 11 is sufficiently controlled by sufficiently uniformly controlling the supply amount of the liquid material 27 supplied to the vaporizer 3 using the pressure fluctuation buffer mechanism 21 and the flow rate control device 20. It becomes possible to indirectly control the supply amount.

  Next, the source gas supply process (B) will be described. In the raw material gas supply step (B), the liquid raw material 27 supplied to the vaporizer 3 is atomized (micronized) in the vaporizer 3, mixed with a carrier gas, and heated to produce a raw material gas. The obtained source gas is supplied to the burner 10 through the source gas pipe 4.

  In the process of generating the raw material gas, the liquid raw material 27 can efficiently receive the kinetic energy of the carrier gas by mixing the liquid raw material 27 with the carrier gas after making the liquid raw material 27 into a mist as described above. Therefore, by atomizing the liquid raw material 27, the liquid raw material 27 can be evenly diffused in the vaporizer 3, and can be efficiently vaporized.

  As the carrier gas, it is preferable to use an inert gas (including nitrogen gas). In this embodiment, nitrogen gas is used as the carrier gas. Such a carrier gas is supplied to the vaporizer 3 through the gas mass flow meter 25. The amount of carrier gas supplied to the vaporizer 3 is preferably about 1.5 to 2.0 slm (standard liters per minute), for example. The supply amount of such carrier gas can be controlled by the gas mass flow meter 25. It is not necessary to match the type of the pumping gas with the type of the carrier gas.

  In the vaporizer 3, the raw material gas is preferably heated to a temperature higher by 10 ° C. or more than the boiling point of the raw silicon compound. Thus, if the temperature of the raw material gas is set to a temperature that is 10 ° C. or more higher than the boiling point of the raw material silicon compound, re-liquefaction of the raw material gas in the raw material gas pipe 4 can be sufficiently prevented. For such heating, for example, a rubber heater or a high-frequency induction coil can be used. Even when impurities (for example, hydrocarbons) are mixed in the raw material liquid, impurities having a boiling point higher than the heating temperature remain in the vaporizer 3 without being vaporized. Therefore, the impurities can be separated in the vaporizer 3.

  In addition, while supplying the said raw material gas, the combustion support gas and combustible gas for producing | generating a flame are supplied to the burner 10 by the piping 23 for combustion support gas, and the piping 24 for combustible gas.

  Next, the quartz glass forming step (C) will be described. In the quartz glass forming step (C), the raw material gas, the oxygen-containing gas, and the hydrogen-containing gas are ejected toward the target 13 provided in the synthesis furnace 11 by the burner 10, and flame hydrolysis is performed on the target 13. This is a step of forming quartz glass by a decomposition reaction.

  In the quartz glass forming step (C), first, the raw material gas, the oxygen-containing gas, and the hydrogen-containing gas supplied to the burner 10 are injected from the burner 10 toward the target 13 in the synthesis furnace 11. At this time, the oxygen-containing gas and the hydrogen-containing gas are burned at the tip of the burner 10, and the raw material gas is decomposed and oxidized in the flame to form quartz glass fine particles (soot). Next, the soot is deposited on the upper surface of the target 13 disposed at a position facing the burner 10 inside the refractory 12 and further heated by the flame to melt the deposited soot. The quartz glass 15 can be produced by vitrification. In the production of such quartz glass, the target 13 is rotated and oscillated at a constant period by a rotation mechanism and an oscillation mechanism, and is lowered by an up-and-down mechanism so that the position of the upper part of the quartz glass being produced is lowered. Is kept at a certain height.

  The preferred embodiment of the quartz glass manufacturing apparatus of the present invention and the method of manufacturing quartz glass using the same have been described above, but the quartz glass manufacturing apparatus of the present invention is not limited to the above embodiment. Absent.

  For example, in the above-described embodiment, the pressure fluctuation buffer mechanism 21 includes a container provided with an inlet and an outlet for liquid raw material, a liquid chamber into which the liquid raw material flows, and a pressure fluctuation buffer filled with a pressure fluctuation buffer fluid. A pressure fluctuation buffer mechanism (accumulator [trade name “HN-N25KG-LL1-PVC” manufactured by Nippon Accumulator Co., Ltd.], comprising a diaphragm for dividing the inside of the container into a chamber and a pressure fluctuation buffer fluid filled in the pressure fluctuation buffer chamber. However, the pressure fluctuation buffer mechanism 21 used in the quartz glass manufacturing apparatus of the present invention is not limited to this. That is, a device capable of controlling the pressure fluctuation of the liquid material can be used as appropriate, and another pressure fluctuation buffer mechanism 21 as described below can be suitably used.

  As such another pressure fluctuation buffer mechanism 21, there is a pressure fluctuation buffer plate in which one or more pinholes having an inner diameter equal to or less than ¼ times the inner diameter of the liquid raw material pipe 2 are formed. Such a pressure fluctuation buffer plate is provided in the liquid raw material pipe 2. In such a pressure fluctuation buffer mechanism, the liquid raw material 27 flowing in the liquid raw material pipe 2 has an effect of dispersing the pressure when passing through the pressure fluctuation buffer plate, so that the pressure fluctuation of the liquid raw material 27 is controlled. It becomes possible to do. Further, in such a pressure fluctuation buffer plate, when the inner diameter of the pinhole exceeds 1/4 times the inner diameter of the liquid raw material pipe 2, the effect of dispersing the pressure tends to decrease. Moreover, as such a pressure fluctuation buffer plate, the inner diameter of the pinhole may be 1/10 to 1/20 times the inner diameter of the liquid raw material pipe 2 from the viewpoint of more efficiently controlling the pressure fluctuation. More preferred. More preferably, about 1 to 3 pinholes are provided.

  Further, as another pressure fluctuation buffer mechanism 21, the pressure fluctuation buffer plate is provided in the liquid raw material pipe 2, and an inner diameter of the liquid raw material pipe 2 is provided between the pressure fluctuation buffer plate and the liquid raw material cylinder 1. And a pressure fluctuation buffering mechanism further including an expansion portion having an inner diameter of 5 times or more. Thus, together with the pressure fluctuation buffer plate, between the pressure fluctuation buffer plate and the liquid source cylinder 1, an expansion portion having an inner diameter of 5 times or more the inner diameter of the liquid source pipe 2 is provided in the liquid source pipe 2. Thus, since the pressure is rapidly dispersed when the liquid material flows into the expansion site, the pressure fluctuation of the liquid material 27 in the liquid material pipe 2 can be controlled at a higher level. Further, in such an expanded portion, if the inner diameter of the expanded portion is less than five times the inner diameter of the liquid raw material pipe 2, it tends to be difficult to sufficiently control the pressure fluctuation. If the pressure fluctuation buffer plate is not provided in the liquid raw material pipe 2 and only the expansion portion having an inner diameter of 5 times or more of the inner diameter of the liquid raw material pipe 2 is provided, the pressure fluctuation of the liquid raw material is sufficiently increased. Since it cannot be controlled, it cannot be used as the pressure fluctuation buffer mechanism 21.

  Moreover, in the said embodiment, although the liquid mass flow meter (Nippon Aera Co., Ltd. make, brand name "LX-1200" is used as the flow control apparatus 20, the flow volume used for the quartz glass manufacturing apparatus of this invention. The control device 20 is not limited to this, and a device capable of adjusting the flow fluctuation of the liquid material can be used as appropriate.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
Quartz glass was produced by a flame hydrolysis method using the quartz glass production apparatus shown in FIG. Here, as the pressure fluctuation buffer mechanism 21 in FIG. 1, an accumulator (Nihon Accumulator Co., Ltd., trade name “HN-N25KG-LL1-PVC” in which a pressure variable buffer chamber is filled with nitrogen as a pressure variable buffer fluid. 1) as a flow rate control device 20 in FIG. 1, a liquid mass flow meter with specifications of full scale (FS) 10 g / min, minimum control flow rate 3% FS, accuracy ± 1% FS (manufactured by Nippon Aera Corporation, (Trade name “LX-1200”), octamethylcyclotetrasiloxane was used as the liquid raw material 27, and nitrogen gas was used as the carrier gas. Further, the flow rate of the oxygen-containing gas ejected from the burner 10 was controlled to be 200 slm, and the flow rate of the hydrogen-containing gas was controlled to be 550 slm. Furthermore, the flow rate of the raw material gas (octamethylcyclotetrasiloxane) ejected from the center of the burner 10 was controlled to 20 g / min, and the flow rate of the carrier gas (nitrogen gas) was controlled to 5 slm. The heating temperature of the raw material gas (octamethylcyclotetrasiloxane) in the vaporizer 3 was set to 200 ° C. Further, as the liquid raw material pipe 2, one having an inner diameter of 4.35 mm was used.

  In the production of quartz glass, first, a liquid raw material 27 (octamethylcyclotetrasiloxane) made of a silicon compound is supplied to the liquid raw material cylinder 1, and then a pumping gas (helium gas) is supplied into the liquid raw material cylinder 1. The liquid raw material 27 was allowed to flow into the liquid raw material pipe 2. Next, the liquid raw material 27 was supplied to the vaporizer 3 after passing through the pressure fluctuation buffer mechanism 21 and the flow rate control device 20. Furthermore, in the vaporizer 3, the supplied liquid raw material 27 was atomized (particulates), mixed with a carrier gas, and heated to generate a raw material gas. The raw material gas thus obtained was supplied to the burner 10. In addition, the source gas supplied to the burner 10 was injected from the burner 10 toward the target 13 together with the oxygen-containing gas and the hydrogen-containing gas. At this time, the oxygen-containing gas and the hydrogen-containing gas were burned at the tip of the burner 10, and the raw material gas was decomposed and oxidized in the flame to form quartz glass fine particles (soot). In this way, soot was deposited on the upper surface of the target 13 and further heated by the flame, and the soot deposited on the target 13 was melted to produce quartz glass 15. In the production of such quartz glass, the position of the upper part of the quartz glass being produced can be determined by rotating and swinging the target 13 with a rotation mechanism and a swing mechanism at a constant period and lowering the target 13 with a vertical mechanism. It was kept at a certain height.

  In such a manufacturing process of quartz glass, pressure fluctuation and flow fluctuation of the liquid raw material 27 were measured. For such pressure fluctuation, a digital pressure gauge (manufactured by Nagano Keiki Co., Ltd., trade name “ZT60-A36”) is installed between the pressure fluctuation buffer mechanism 21 and the vaporizer 3, and a recorder is connected to the digital pressure gauge. The flow rate fluctuation was measured by connecting a recorder to the liquid mass flow meter, and the results obtained are shown in Table 1 and FIG.

(Example 2)
Instead of using an accumulator (Nihon Accumulator Co., Ltd., trade name “HN-N25KG-LL1-PVC”) filled with nitrogen as a pressure variable buffer fluid in the pressure variable buffer chamber, the pressure variable buffer chamber is changed in pressure. Quartz glass was produced in the same manner as in Example 1 except that an accumulator (trade name “HB-N25KG-LL1-PVC” manufactured by Nippon Accumulator Co., Ltd.) supplied with glycerin as a buffer fluid was used.

  In such a manufacturing process of quartz glass, the pressure fluctuation and the flow fluctuation of the liquid raw material 27 were measured in the same manner as in Example 1. The obtained results are shown in Table 1.

(Example 3)
Without using an accumulator (Nihon Accumulator Co., Ltd., trade name “HN-N25KG-LL1-PVC”) filled with nitrogen as a pressure variable buffer fluid in the pressure variable buffer chamber, the diameter of the pressure variable buffer mechanism 21 is Quartz glass was produced in the same manner as in Example 1 except that a pressure fluctuation buffer plate provided with one 1 mm pinhole was used and the pressure fluctuation buffer plate was provided inside the liquid raw material pipe 2.

  In such a manufacturing process of quartz glass, the pressure fluctuation and the flow fluctuation of the liquid raw material 27 were measured in the same manner as in Example 1. The obtained results are shown in Table 1.

Example 4
Without using an accumulator (Nihon Accumulator Co., Ltd., trade name “HN-N25KG-LL1-PVC”) filled with nitrogen as a pressure variable buffer fluid in the pressure variable buffer chamber, the diameter of the pressure variable buffer mechanism 21 is A pressure fluctuation buffer plate having three 0.3 mm pinholes is provided inside the liquid raw material pipe 2, and an expansion portion having an inner diameter of 30 mm is further provided between the pressure variable buffer plate and the raw material cylinder 1 Quartz glass was produced in the same manner as in Example 1 except that the above was used.

  In such a manufacturing process of quartz glass, the pressure fluctuation and the flow fluctuation of the liquid raw material 27 were measured in the same manner as in Example 1. The obtained results are shown in Table 1.

(Comparative Example 1)
Quartz glass was produced in the same manner as in Example 1 except that no pressure fluctuation buffer mechanism was provided.

  In such a manufacturing process of quartz glass, the pressure fluctuation and the flow fluctuation of the liquid raw material 27 were measured in the same manner as in Example 1. The obtained results are shown in Table 1 and FIG.

(Comparative Example 2)
Without using an accumulator (trade name “HN-N25KG-LL1-PVC” manufactured by Nippon Accumulator Co., Ltd.) filled with nitrogen in the pressure-variation buffer chamber, the liquid raw material pipe 2 was provided with only an expansion portion having an inner diameter of 30 mm. Except for the above, quartz glass was produced in the same manner as in Example 1.

  In such a manufacturing process of quartz glass, the pressure fluctuation and the flow fluctuation of the liquid raw material 27 were measured in the same manner as in Example 1. The obtained results are shown in Table 1.

(Evaluation of the quartz glass obtained in Examples 1-4 and Comparative Examples 1-2)
<Measurement of bubbles in quartz glass>
The foam which generate | occur | produced in the quartz glass obtained in Examples 1-4 and Comparative Examples 1-2 was measured. The measurement and evaluation of such a foam followed the foam measurement method (JOGIS12) described in JOGIS. In measurement of such bubbles, blocks each having a size of 30 mm in length, 30 mm in width, and 10 mm in height were cut out from each quartz glass and used as samples. Moreover, the microscope (The Nikon company make, brand name "MM-40 / L3T") was used for the measurement of such a bubble. The obtained results are shown in Table 1.

<Measurement of foreign matter in quartz glass>
Foreign matters in the quartz glass obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured. The measurement and evaluation of such foreign matters were in accordance with the foreign matter measuring method (JOGIS13) described in JOGIS. In the measurement of such foreign matter, a block having a size of 30 mm in length, 30 mm in width, and 10 mm in height was cut out from each quartz glass and used as a sample. Further, in order to measure such foreign matter, a microscope (made by Nikon Corporation, trade name “MM-40 / L3T”) is used, and in addition, in order to irradiate the sample with light having an illuminance of 2 klx, parallel light of white light is used. A device capable of emitting a light beam was used. The obtained results are shown in Table 1.

<Measurement of striae in quartz glass>
Foreign matters in the quartz glass obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured. Such striae measurement and evaluation were performed according to the striae measurement method (JOGIS11) described in JOGIS. The obtained results are shown in Table 1.

  As is apparent from the results shown in Table 1 and FIG. 1, in the case where the quartz glass production apparatus of the present invention and the production method of the present invention are used (Examples 1 to 4), sufficient pressure fluctuation and flow fluctuation are obtained. It was confirmed that the liquid material could be uniformly controlled, and the supply amount of the liquid raw material to the vaporizer could be kept constant. And in such a quartz glass manufacturing apparatus of the present invention, it was confirmed that mixing of foreign matters and generation of bubbles and striae into the quartz glass were sufficiently prevented. Thus, in the quartz glass obtained in Examples 1 to 4, since there is no mixing of foreign substances and generation of bubbles and striae that cause a decrease in the transmittance and homogeneity of ultraviolet rays, It was found that the transmittance was high and the uniformity was excellent.

  On the other hand, in the case where the quartz glass manufacturing apparatus is not provided with the pressure fluctuation buffer mechanism according to the present invention (Comparative Examples 1 and 2), the pressure fluctuation and the flow fluctuation of the liquid raw material cannot be sufficiently controlled. It was confirmed that it was not possible to sufficiently prevent the occurrence of contamination, bubbles and striae.

  As described above, according to the present invention, the supply amount of the liquid raw material supplied to the vaporizer can be controlled sufficiently uniformly, and foreign matter is mixed into the quartz glass and bubbles and striae are generated. Quartz glass production apparatus capable of efficiently and reliably producing quartz glass that is sufficiently prevented and has a sufficiently high transmittance of light having a wavelength in the ultraviolet region and excellent in homogeneity, and It is possible to provide a method for producing quartz glass using the production apparatus.

  Therefore, the quartz glass production apparatus of the present invention is useful as a production apparatus for producing quartz glass having high ultraviolet light transmittance and excellent homogeneity because it is excellent in controlling the amount of liquid raw material supplied to the vaporizer. It is.

It is a schematic diagram which shows the structure of suitable one Embodiment of the manufacturing apparatus of the quartz glass of this invention. It is a schematic longitudinal cross-sectional view which shows the structure of suitable one Embodiment of the pressure fluctuation buffer mechanism concerning this invention. In Example 1 and Comparative Example 1, it is a graph which shows the state of the pressure fluctuation and flow volume fluctuation | variation of the liquid raw material supplied to a vaporizer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid raw material cylinder, 2 ... Liquid raw material piping, 3 ... Vaporizer, 4 ... Raw material gas piping, 5 ... Thermal insulation piping, 6 ... Thermal insulation member, 10 ... Burner, 11 ... Synthesis furnace, 12 ... Refractory, 13 DESCRIPTION OF SYMBOLS ... Target, 14 ... Stage, 15 ... Quartz glass, 20 ... Flow control device, 21 ... Pressure fluctuation buffer mechanism, 22 ... Carrier gas piping, 23 ... Combustion gas piping, 24 ... Combustion gas piping, 25 ... Gas Mass flow meter, 26 ... piping for pressurized gas, 27 ... liquid raw material, 30 ... introduction port, 31 ... discharge port, 32 ... container, 33 ... liquid chamber, 34 ... pressure fluctuation buffer chamber, 35 ... diaphragm.

Claims (7)

A liquid source cylinder, a liquid source pipe having one end connected to the liquid source cylinder, a vaporizer connected to the other end of the liquid source pipe, and a source gas pipe having one end connected to the vaporizer An apparatus for producing quartz glass, comprising: a burner connected to the other end of the source gas pipe; and a synthesis furnace in which the burner is disposed.
An apparatus for producing quartz glass, wherein a flow rate control device is provided in the liquid source pipe, and a pressure fluctuation buffering mechanism is further provided between the liquid source cylinder and the flow rate control device. .   The quartz glass manufacturing apparatus according to claim 1, wherein the pressure fluctuation buffer mechanism controls the pressure fluctuation of the liquid raw material in the liquid raw material pipe within ± 0.05 MPa.   The pressure fluctuation buffer mechanism divides the inside of the container into a container provided with an inlet and an outlet for liquid raw material, a liquid chamber into which liquid raw material flows and a pressure fluctuation buffer chamber filled with pressure fluctuation buffer fluid. The apparatus for producing quartz glass according to claim 1, further comprising a diaphragm and a pressure fluctuation buffer fluid filled in the pressure fluctuation buffer chamber.   The pressure fluctuation buffer mechanism is a pressure fluctuation buffer plate in which one or more pinholes having an inner diameter equal to or less than 1/4 times the inner diameter of the liquid raw material pipe are formed, and the pressure fluctuation buffer plate is the liquid raw material The quartz glass manufacturing apparatus according to claim 1, wherein the quartz glass manufacturing apparatus is provided in an industrial pipe.   5. The pressure fluctuation buffer mechanism further includes an expansion portion having an inner diameter that is not less than five times the inner diameter of the liquid source pipe between the pressure fluctuation buffer plate and the liquid source cylinder. The production apparatus for quartz glass as described in 1. A liquid source supply step for supplying a liquid source composed of a silicon compound to a vaporizer through a liquid source pipe, and a source gas for supplying a source gas obtained by vaporizing the liquid source with the vaporizer to a burner through a source gas pipe The raw material gas, the oxygen-containing gas, and the hydrogen-containing gas are ejected toward the target provided in the synthesis furnace by the supply step and the burner, and quartz glass is formed on the target by a flame hydrolysis reaction. A method for producing quartz glass, comprising a quartz glass forming step,
The method for producing quartz glass, wherein in the liquid source supply step, the pressure fluctuation of the liquid source in the liquid source pipe is controlled within ± 0.05 MPa. The method for producing quartz glass according to claim 6, wherein, in the liquid source supply step, flow rate fluctuation of the liquid source in the liquid source pipe is controlled within ± 0.01 g / min.

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