JP2011006278A - Purification treatment apparatus and purification treatment method of quartz glass workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purification treatment apparatus for increasing surface cleanliness of a quartz glass workpiece such as a quartz glass tool and a purification treatment method using the apparatus.SOLUTION: The purification treatment apparatus includes: a housing; a cylindrical purification treatment vessel made of quartz glass disposed within the housing; a heater which is disposed outside the purification treatment vessel and heats the inside of the purification treatment vessel to form a heat zone; a bottom opening for storage and takeoff of a quartz glass workpiece; a closing means to close the bottom opening in a tightly sealed state; a holding means to hold the quartz glass workpiece in a vertically movable state; a gas introduction part disposed in the lower end of the purification treatment vessel and for introducing a gas into the purification treatment vessel; and a gas exhaust passage for discharging the gas in the purification treatment vessel to the outside of the housing, wherein the quartz glass workpiece held by the holding means can be subjected to purification treatment in the purification treatment vessel.

Description

The present invention relates to a purification apparatus and a purification method for a quartz glass processed product such as a quartz glass jig used in the semiconductor industry.

A quartz glass jig used for the semiconductor industry is processed into a desired shape from a natural quartz glass material by fire processing or the like, subjected to strain relief annealing, and then washed and commercialized.

In the quartz glass jig manufactured in this way, metal impurities diffuse from the surface to the depth of 100 μm in the high-temperature heat treatment step in the processing step, and the depth that cannot be removed by the surface cleaning process in the final step. It will be contaminated. These metal impurities are released during high-temperature heat treatment in the semiconductor manufacturing process and adhere to the silicon wafer, causing defects and the like. In particular, release of metal impurities such as Na, K, Li, Mg, Ca, Cr, Fe, Ni, and Cu, which is a problem in the semiconductor industry, is not preferable.

As countermeasures, attempts have been made to clean the indoor atmosphere of the quartz glass jig manufacturing process, to make a burner for fire processing with quartz glass, or to use an annealing furnace whose furnace wall is made of a special clean material. Has been made.
In the quartz glass jig obtained by the above method, the contamination of the surface layer portion is surely reduced, and even when used for the semiconductor industry, there are few defects in the silicon wafer, and the effect was confirmed. However, even when all of these measures are taken individually or individually, the cost and labor are extremely burdensome in terms of sales and manufacturing.

Therefore, HCl and other Cl are available as purification methods that can improve surface cleanliness easily and reliably at low cost for quartz glass processed products such as quartz glass jigs used in the semiconductor industry. Methods using the contained gas have been proposed (Patent Documents 1 to 5). However, at present, no proposal has been made yet for a purification apparatus for actually carrying out the purification method for these processed quartz glass products efficiently.

JP 2003-012333 A JP 2004-059412 A JP 2003-323246 A JP 2006-306675 A JP 2006-315886 A

An object of the present invention is to provide a purification apparatus for improving surface cleanliness and a purification method using the apparatus for a quartz glass processed product such as a quartz glass jig used in the semiconductor industry and the like. It is in.

In order to solve the above-described problems, a purification apparatus for a processed quartz glass product of the present invention includes:
A housing having a through hole in the top wall and a bottom wall opening in the bottom wall;
Made of cylindrical quartz glass provided inside the casing with the lower end portion inserted in a sealed state into the bottom wall opening of the casing and the lower end hanging downward from the bottom wall of the casing A purification vessel;
A heater that is provided outside the purification container and that heats the interior of the purification container to form a heat zone;
A bottom opening for storing and taking out a quartz glass processed product provided by opening the bottom of the purification processing container in order to store and take out the quartz glass processed product to be purified from the purification processing container. ,
A closing means for closing the bottom opening in a sealed state;
Before the purification treatment, the quartz glass processed product can be stored in the purification processing container from below, and the quartz glass processed product is not purified directly in contact with the purification processing container during the purification treatment. A holding means that can be held in the heat zone of the processing vessel and can move up and down after the purification process is completed, so that the quartz glass processed product after the purification process can be carried out downward,
A gas introduction part provided at a lower end of the purification treatment container and for introducing gas into the purification treatment container;
The exhaust port opened in the upper part of the purification container and the through-hole opened in the top wall of the casing are formed to communicate with each other, and the gas in the purification container is exhausted to the outside of the casing. And a gas exhaust for
The processed quartz glass product held by the holding means can be purified in the purification vessel.

When the lower end portion of the purification treatment container is inserted into the bottom wall opening of the housing, the bottom wall opening and the purification treatment container are brought into a sealed state so that the bottom wall opening is brought into contact with the bottom wall opening. It is preferable to provide an O-ring having elasticity on the surface and a cooling mechanism for cooling the installation portion of the O-ring.

The cylindrical purification vessel has a two-stage structure in which an upper stage cylindrical body and a lower stage cylindrical body are connected in series, and the inner diameter of the lower stage cylindrical body exceeds the inner diameter of the upper stage cylindrical body. It can be set as the structure which is.

It is preferable that one or more gas introduction portions for introducing the gas are arranged in a range including a lower center portion of the purification treatment container.

The holding means for holding the quartz glass processed product includes a top plate on which the quartz glass processed product is placed, a bottom plate disposed below the top plate with a predetermined interval, and the top plate and the bottom plate. A structure having a plurality of struts attached at a predetermined interval therebetween, and a heat shield means comprising a plurality of opaque plates stacked with a predetermined interval between the top plate and the bottom plate via the struts. It is preferable to do this.

  As the closing means, the quartz glass processed product is raised in a state where it is placed on the upper surface of the top plate of the holding means, and the quartz glass processed product is stored in the purification processing container, It is possible to employ a configuration in which the bottom opening is closed in a sealed state by the outer peripheral portion of the bottom plate contacting the peripheral edge of the bottom opening of the purification treatment container in a sealed state.

The purification method for a processed quartz glass product of the present invention is a purification method for a processed quartz glass product using the purification apparatus for the processed quartz glass product of the present invention,
A process for storing a processed quartz glass product to be purified in the purification container from the bottom opening of the purification container, a process for closing the bottom opening in the purification container, and the inside of the purification container are not performed. Replacing with active gas;
A temperature raising step of raising the temperature in the purification treatment vessel from room temperature to a predetermined purification treatment temperature while flowing a purification treatment gas into the purification treatment vessel;
A purification process step of performing a purification process over a predetermined time at a predetermined purification temperature while continuously flowing the purification gas into the purification container;
A step of lowering the gas to a gas switching temperature while flowing the purification gas into the purification container after the purification process is completed;
A step of switching the purification gas to an inert gas when the temperature in the purification vessel reaches a gas switching temperature;
Cooling the inert gas into the purification container while lowering the quartz glass processed product to a temperature at which it can be removed;
When the temperature in the purification container reaches a temperature that can be taken out, the step of taking out the processed quartz glass product from the bottom opening of the purification container;
It is characterized by having.

  As the purification treatment gas, a gas containing HCl or Cl can be used. It is preferable that the purification treatment temperature is 900 ° C. or more and 1300 ° C. or less, and the purification treatment time is 30 minutes or more. The gas switching temperature after the purification treatment may be 800 ° C. or higher and 850 ° C. or lower.

The purifying gas inflow operation into the purifying container of the purifying gas is used for the purifying gas used in the purifying process together with the introduction of the purifying gas from the gas introduction part of the purifying gas. It is preferable that the exhaust gas is exhausted from the exhaust section and controlled so that the pressure in the purification container is higher than the atmospheric pressure and lower than 1 kPa during the purification gas inflow operation.

According to the apparatus for purifying a processed quartz glass product of the present invention, the surface layer of the processed quartz glass product generated during the semiconductor processing process or the like for a processed quartz glass product such as a quartz glass jig used in the semiconductor industry or the like. The effect is achieved that most of the contamination can be removed and the surface cleanliness can be improved easily and reliably. According to the purification method for a processed quartz glass product of the present invention, there is an advantage that the purified silica glass product can be efficiently purified using the apparatus of the present invention.

It is sectional explanatory drawing which shows the state which stores the quartz glass processed goods in the purification processing container, and is performing the purification process in the purification processing apparatus of the quartz glass processed goods of this invention. It is sectional explanatory drawing which shows the state which carried out the quartz glass processed goods below from the purification processing container in the purification processing apparatus of the quartz glass processed goods of this invention. It is an expanded sectional explanatory view of the arrow A part of FIG. FIG. 4 is an enlarged cross-sectional explanatory view showing a state where the holding means is lowered downward from the state of FIG. 3. It is upper surface explanatory drawing which shows the structure of a set base. It is decomposition | disassembly side surface explanatory drawing of a set base. It is side surface explanatory drawing which shows the state which assembled each member shown in FIG. 6, and was set as the set base. It is a graph which shows the relationship between processing time and processing temperature about the pattern of the basic purification process in the purification processing method of the quartz glass processed goods of this invention. It is a schematic explanatory drawing which shows an example of the pressure management mechanism in the purification processing apparatus of this invention. It is explanatory drawing which shows an example of the state of the flow of the purification process gas in the case of performing the purification process of one quartz glass processed goods by the purification processing apparatus of this invention. It is explanatory drawing which shows an example of the state of the flow of the purification process gas in the case of performing the purification process of another quartz glass processed goods by the purification processing apparatus of this invention. It is explanatory drawing which shows an example of the state of the flow of the purification process gas in the case of performing the purification process of another quartz glass processed goods by the purification processing apparatus of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings, but these embodiments are exemplarily shown, and various modifications can be made without departing from the technical idea of the present invention. Not too long.

  FIG. 1 is a cross-sectional explanatory view showing a state in which a quartz glass processed product is stored in a purification processing container in a purification apparatus for a quartz glass processed product according to the present invention and is purified. FIG. 2 is a cross-sectional explanatory view showing a state in which the processed quartz glass product is transported downward from the purification processing container in the purification apparatus for the processed quartz glass product of the present invention. 1 and 2, reference numeral 10 denotes a purification apparatus for a processed quartz glass product according to the present invention. The purification processing apparatus 10 includes a base frame 11 and the casing 12 installed on the base frame 11. The housing 12 includes a top wall 14, a side wall 16, and a bottom wall 18, and a hollow interior 20 is formed therein. A through hole 22 is formed in the top wall 14, and a bottom wall opening 24 is formed in the bottom wall 18.

Reference numeral 26 denotes a cylindrical quartz glass purification treatment vessel, which has an exhaust port 28 opened at the top thereof and a bottom opening 30 formed at the bottom thereof. The purification vessel made of quartz glass 26 is inserted in the bottom wall opening 24 of the housing 12 with its lower end portion sealed, and the lower end portion hangs downward from the side wall 16 of the housing 12. It is provided so as to be positioned in the hollow interior 20 of the housing 12. The bottom opening 30 is provided for storing and taking out a quartz glass processed product G to be purified from the purification container 26. When performing the purification process, the bottom opening 30 needs to be closed in a sealed state. However, as the closing means for performing the closing action, a configuration described later can be adopted.

As shown in FIGS. 1 and 2, the cylindrical purification container 26 has a two-stage structure in which an upper cylindrical body 26a and a lower cylindrical body 26b are connected to each other, and the lower cylindrical cylinder is formed. It is preferable that the inner diameter of the body 26b is larger than the inner diameter of the upper cylindrical body 26a. The internal space of the purification container 26 formed by the upper cylindrical body 26a is a heat zone, and the processed quartz glass product G is stored in the heat zone. The range of the upper cylindrical body 26a of the purification container 26 is preferably made of transparent quartz glass so that heater heat from the heater 32 described later can be effectively transmitted to the heat zone as radiant heat and transmitted heat. On the other hand, the range of the lower cylindrical portion 26b is preferably made of opaque quartz glass for thermal protection of the first O-ring 56, the second O-ring 70, and the third O-ring 76, which will be described later, and has a low heat transmittance. . Radiant heat can be shielded by using opaque quartz glass, and opaque quartz glass has a characteristic that heat is difficult to transfer because it contains bubbles inside.

A plurality of heaters 32 are provided on the inner surface of the side wall 16 of the housing 12. The heater 32 functions to heat the inside of the purification processing container 26 from the outside of the purification processing container 26 to form a heat zone.

Reference numeral 34 denotes a holding means for holding the processed quartz glass product G. The holding means 34 has a set pedestal 35 on which the quartz glass processed product G is set and placed, and the quartz glass processed product G is kept warm. The set pedestal 35 has a top plate 36 on which the quartz glass processed product G is placed on the upper surface, and a bottom plate 38 installed below the top plate at a predetermined interval. A plurality of support columns 40 are attached between the top plate 36 and the bottom plate 38 at a predetermined interval. A plurality of opaque plates 42 are provided in a stacked state between the top plate 36 and the bottom plate 38 via the support column 40 at a predetermined interval. The plurality of opaque plates 42 act as heat shield means. Reference numeral 41 denotes a short receiving column which is erected at an appropriate position on the upper surface of the bottom plate 38, and supports and mounts a plurality of opaque plates 42 located on the upper side from below as will be described later.

Side pillars 44 are erected adjacent to the base frame 11. A movable support plate 46 is attached to the side column 44 so as to be movable up and down. The set pedestal 35, that is, the holding means 34 is placed on the upper surface of the movable support plate 46. By moving the movable support plate 46 up and down, the set pedestal 35, that is, the holding means 34 moves up and down. ing.

Since the holding means 34 has the above-described configuration, the quartz glass processed product G can be stored in the purification processing vessel 26 from below before the purification process, and the quartz glass processing is performed during the purification process. The quartz glass processed product G can be held in the heat zone of the purification container 26 so that the product G does not come into direct contact with the purification container 26, and after the purification process, the quartz glass processed product after the purification process. G can be carried out downward.

Reference numeral 48 denotes a gas introduction part for introducing a gas such as a purification process gas and an inert gas into the purification process container 26, and is provided at the lower end portion of the set base 35. The gas introduction part 48 will be described in detail later together with the structure of the set base 35. Reference numeral 50 denotes a gas exhaust unit for exhausting gases such as a purification process gas and an inert gas in the purification process container 26 to the outside of the casing 12. The gas exhaust part 50 is formed by communicating an exhaust port 28 opened in the upper part of the purification treatment container 26 with a through hole 22 opened in the top wall 14 of the housing 12.

  FIG. 3 is an enlarged cross-sectional explanatory view of the portion A in FIG. 4 is an enlarged cross-sectional explanatory view showing a state in which the holding means is lowered downward from the state of FIG. As means for closing the bottom opening 30 of the purification container 26, that is, as the closing means described above, as shown in FIGS. 3 and 4, a quartz glass processed product G is placed on the top surface 36 of the holding means 34. In a state where the quartz glass processed product G is stored in the purification processing container 26 while being raised, the peripheral portion of the bottom plate 38 of the holding means 34 is the lower end of the wall 26c of the purification processing container 26. It is possible to adopt a configuration in which the bottom opening 30 is closed in a sealed state by contacting the peripheral member 52 provided in the portion in a sealed state.

  As shown in FIGS. 3 and 4, a bottom plate annular groove 54 is formed on the upper surface of the peripheral portion of the bottom plate 38 of the holding means 34. The bottom plate annular groove 54 has a first O having heat resistance and elasticity. A ring 56 is fitted. On the other hand, the peripheral member 52 described above is provided at the peripheral portion of the bottom opening 30 of the purification container 26. The peripheral member 52 contacts the outer surface member 58 provided in contact with the outer surface of the lower end portion of the wall body 26c of the purification treatment container 26, and the lower surface of the lower end portion of the wall body 26c of the purification treatment container 26. The lower surface member 60 provided in contact with the lower surface member 60 and a stepped auxiliary member 64 provided so as to form a receiving stepped portion 62 on the outer surface side of the lower surface member 60 are configured. The receiving step portion 62 abuts and receives the peripheral portion of the bottom plate 38 of the holding means 34 through the first O-ring 56 in a sealed state, and closes the bottom opening portion 30 in a sealed state.

  As shown in FIGS. 3 and 4, the outer surface member 58 has a narrow first step portion 66 on the inner surface side and a wide second step portion 68 on the upper portion of the first step portion 66. Is provided. A second O-ring 70 is fitted to the first step portion 66. Reference numeral 72 denotes a fixing member disposed on the second step portion 68 and serves to fix the second O-ring 70 fitted to the first step portion 66. The outer surface member 58 is installed in contact with the outer surface of the lower end portion of the wall 26c of the purification container 26 in a sealed state via the second O-ring 70, and the sealed state is maintained.

  A lower surface member annular groove 74 is formed outside the upper surface of the lower surface member 60, and a third O-ring 76 having heat resistance and elasticity is fitted into the lower surface member annular groove 74. The lower surface member 60 is installed in contact with the lower surface of the lower end portion of the wall 26c of the purification container 26 in a sealed state via the third O-ring 76, and the sealed state is maintained. On the other hand, an annular receiving groove 78 is formed inside the upper surface of the lower surface member 60, and a cooling mechanism 80 such as a water cooling mechanism is provided in the annular receiving groove 78. The cooling mechanism 80 functions to prevent thermal degradation of the second O-ring 70. As the material of the first O-ring 56, the second O-ring 70, and the third O-ring 76, it is preferable to use a heat-resistant fluoro rubber, for example, Viton (registered trademark) rubber.

  FIG. 5 is an explanatory top view showing the structure of the set base. FIG. 6 is an exploded side view of the set base. FIG. 7 is an explanatory side view showing a state where the members shown in FIG. 6 are assembled into a set base. As described above, the set pedestal 35 has a top plate 36 and a bottom plate 38 disposed below the top plate 36 with a predetermined interval, and a predetermined interval is provided between the top plate 36 and the bottom plate 38. A plurality of columns 40 (a total of five columns including one inner column 40a and four outer columns 40b in the example of FIGS. 5 to 7) are provided. A plurality of (15 in the example of FIGS. 5 to 7) opaque plates 42 are provided in a multilayered manner with a predetermined distance between the top plate 36 and the bottom plate 38 via the support column 40. In addition, a plurality of (four in the example of FIGS. 5 to 7) receiving posts 41 are provided on the upper surface of the bottom plate 38.

  As shown in FIG. 6, the set pedestal 35 can be disassembled into an upper pedestal member 35a and a lower pedestal member 35b. The upper pedestal member 35a includes the top plate 36 and a plurality of upper opaque plates 42a (12 in the example of FIG. 6). The lower pedestal member 35b includes the bottom plate 38 and a plurality of long columns 40 provided on the top surface of the bottom plate 38, as well as a plurality of short receiving columns 41 provided on the top surface of the bottom plate 38, and the like. It is composed of a plurality of (three in the example of FIG. 6) lower opaque plates 42b attached to the columns 40 and the receiving columns 41. As shown in FIG. 6, a through hole 82 is formed at a position corresponding to the column 40 of the top plate 36 and the plurality of upper opaque plates 42 a, and by inserting the column 40 into the through hole 82, The upper opaque plate 42a is attached to the support column 40, and the upper base member 35a is installed on a plurality of short receiving columns 41. As a result, as shown in FIG. 7, the set pedestal 35 is formed with the upper pedestal member 35a being inserted on the lower pedestal member 35b.

  As shown in FIG. 5, the support column 40 has a plurality of inner support columns 40a positioned at the center of the top plate 36 (and the bottom plate 38) and a plurality of columns positioned in the periphery of the top plate 36 (and the bottom plate 38). In the example of FIG. 5, it is composed of four outer struts 40b. The inner support column 40a has an inner ventilation through hole 48a extending over the entire length of the support column. Further, at least one outer strut 40b (all four in the example of FIG. 5) has an outer ventilation through hole 48b extending over the entire length of the strut. The inner ventilation through hole 48a and the outer ventilation through hole 48b function as the gas introduction portion 48 described above, and perform a function of introducing a gas such as a purification gas and an inert gas into the purification chamber 26. As described above, the purifying gas may be guided to the central portion of the set pedestal 35 by the inner vent through hole 48a, and the purifying gas may be guided to the peripheral portion of the set pedestal 35 by at least one outer vent through hole 48b. Therefore, as shown in FIGS. 10 to 12 to be described later, the purification gas can be uniformly guided to both the inside and the outside of the quartz glass processed product G to be purified, which is effective. There is an advantage that the purification process can be performed. In FIG. 6, reference numeral 36 a is a top plate through-hole opened in the top plate 36. 6 and 7, reference numeral 38 a is a bottom plate substrate provided on the bottom plate 38.

Next, the method for purifying a processed quartz glass product according to the present invention will be described with reference to FIG. 8. The method for purifying a processed quartz glass product according to the present invention is a purification apparatus for a processed quartz glass product according to the present invention described above. Therefore, the apparatus will be described using the reference numerals used in the examples shown in FIGS. 1 to 7. FIG. 8 is a graph showing the relationship between the treatment time and the treatment temperature for the basic purification treatment pattern in the purification method for a processed quartz glass product of the present invention.

  The method for purifying a quartz glass processed product according to the present invention includes a step of storing a quartz glass processed product G to be purified in a purification processing vessel 26 from a bottom opening 30 of the purification processing vessel 26, and the purification processing. A step of closing the bottom opening 30 of the vessel 26, a step of replacing the inside of the purification treatment vessel 26 with an inert gas, and a flow of the purification treatment gas into the purification treatment vessel 26 while flowing in the purification treatment vessel 26. A temperature raising step (step 1 in FIG. 8) for raising the temperature from room temperature to a predetermined purification temperature, and a predetermined purification temperature at a predetermined purification temperature while continuously flowing the purification gas into the purification vessel 26 And a step of lowering the temperature to the gas switching temperature while allowing the purification treatment gas to flow into the purification treatment container 26 after completion of the purification treatment. Step 3) in FIG. 8, a step of switching the purification gas to an inert gas when the temperature in the purification chamber 26 reaches a gas switching temperature, and the inert gas in the purification chamber 26. The step of lowering the quartz glass processed product G to a temperature at which the quartz glass processed product G can be taken out while flowing in, and when the temperature in the purification processing container 26 reaches the temperature that can be taken out, the quartz glass processed product G is And a step of taking out from the bottom opening 30 of the purification container 26.

  As the purification treatment gas, a gas containing HCl or Cl can be used. It is preferable that the purification treatment temperature is 900 ° C. or more and 1300 ° C. or less, and the purification treatment time is 30 minutes or more. The gas switching temperature after the purification treatment may be 800 ° C. or higher and 850 ° C. or lower.

The purifying gas inflow operation into the purifying container of the purifying gas is used for the purifying gas used in the purifying process together with the introduction of the purifying gas from the gas introduction part of the purifying gas. It is preferable that the exhaust gas is exhausted from the exhaust part and controlled so that the pressure in the purification treatment container 26 is higher than atmospheric pressure and lower than 1 kPa during the purification gas inflow operation. The gas replacement operation in the purification processing container 26 and the operation of inflow of the purification processing gas into the purification processing container 26 during the purification process, which will be described later, are performed by the pressure management in the purification processing container 26 and the opening / closing operation of the gas exhaust unit 50.

The pressure management in the purification apparatus in the apparatus of the present invention is performed by, for example, the mechanism shown in FIG. FIG. 9 is a schematic explanatory diagram showing an example of a pressure management mechanism in the purification apparatus of the present invention. 9, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals.

As shown in FIG. 9, the gas introduction part 48 communicates with the gas introduction passage 49. The gas introduction passage 49 is provided with a flow meter 84 for measuring and displaying the gas flow rate, an introduction valve 86 and an introduction gas pressure gauge 88. On the other hand, the gas exhaust part 50 communicates with the gas exhaust passage 51. The gas exhaust passage 51 is provided with an exhaust pressure gauge 90 and an exhaust valve 92. The exhaust pressure gauge 90 and the exhaust valve 92 are connected via a pressure adjustment indicator 94. By controlling each of the above devices, the pressure in the purification treatment container 26 can be controlled to be higher than atmospheric pressure and lower than 1 kPa.

The purification method of the present invention removes contamination of the surface layer of the quartz glass jig, that is, purifies the quartz glass jig by heat-treating the quartz glass workpiece, for example, the quartz glass jig, in a purification gas, eg, hydrogen chloride gas atmosphere. Is the method. As a specific purification process, the purification temperature is set and controlled by a program temperature regulator. The processing procedure sets a processing temperature, a processing time, a processing gas amount, and the like with a simple pattern of temperature increase → temperature maintenance → temperature decrease.

The basic pattern of the purification process is as shown in FIG. In Step 1, the temperature in the purification vessel is raised from room temperature to 1100 ° C. over about 2 hours. When hydrogen chloride gas is used as the purification treatment gas, the gas flow rate is preferably about 10 L / min. In step 2, in a state where purifying gas is introduced after step 1 (about 10 L / min), the temperature is maintained at 1100 ° C. for 2 hours and 30 minutes. In step 3, after the completion of step 2, the heating is stopped (with the heater turned off) in the state where the purification gas is similarly introduced (about 10 L / min) and natural cooling is performed. The temperature is lowered from 1100 ° C. to 800 ° C. in about 2 hours. In Step 4, an inert gas (for example, nitrogen gas) is flowed instead of hydrogen chloride gas (about 7 L / min), and the natural gas is continuously cooled while replacing the inert gas (nitrogen). The temperature is lowered to 200 ° C. Then, the inside of the purification container is opened, and the quartz glass processed product is taken out using clean gloves or resin tweezers after waiting for 20 to 30 minutes until the temperature of the purified quartz glass processed product drops to a temperature that can be handled.

In addition, it is necessary to replace the purification container with an inert gas such as nitrogen from the day before the purification process. Unlike a general atmospheric furnace, the purification container used in the present invention has airtightness in the furnace, and has a structure in which outside air does not enter during heat treatment. When the quartz glass processed product to be purified is set in the purification container, the working environment atmosphere is mixed in the purification container because the purification container is opened to the atmosphere. Accordingly, the atmosphere gas mixed by replacing the inside of the purification processing container with an inert gas, for example, nitrogen is excluded. For example, when the internal volume of the purification container is 650 L, nitrogen substitution in the purification container is completed by introducing nitrogen (6.5 m ³ ) 10 times the volume.

When the quartz glass processed product G to be purified is set in the purification apparatus, the purification container 26 is opened, so that an external atmospheric gas containing contaminants is taken into the purification container 26. It will be. Contaminants taken into the purification container 26 include air, moisture in the air, other dust, dust, and the like, but the purification process is performed by replacing the interior of the purification container 26 with an inert gas such as nitrogen. The amount of contaminants in the container 26 is reduced.

  As described above, in the present invention, by using the inner ventilation through hole 48a and the outer ventilation through hole 48b, the purification gas is supplied to both the inside and the outside of the quartz glass processed product G that is the object of the purification treatment. It is possible to guide, and the purification process can be effectively performed. FIG. 10 is an explanatory diagram showing an example of the state of the flow of the purification process gas when the purification process of one quartz glass product is performed by the purification apparatus of the present invention. FIG. 11 is an explanatory view showing an example of the state of the flow of the purification gas when another purification process for quartz glass is performed by the purification apparatus of the present invention. FIG. 12 is an explanatory view showing an example of the state of the flow of the purification process gas when the purification process of another quartz glass processed product is performed by the purification apparatus of the present invention. As shown in the flow of the purification gas shown in FIGS. 10 to 12, even if the shape of the processed quartz glass product is variously changed, effective purification is performed according to the present invention. is there. Even in the case of the purification treatment of the quartz glass processed product G having the branch pipe shown in FIG. 12, the purification process gas is normally passed through the branch pipe which is difficult to be washed with water by introducing the purification treatment gas from the inner ventilation through hole 48a. There is an advantage that becomes possible.

  According to the present invention, it is possible to remove contamination elements up to a detection lower limit (10 ppb or less) by performing a purification treatment on the processed quartz glass product G regardless of whether the material is natural quartz glass or synthetic quartz glass. Is possible. Examples of contaminating elements to be removed include Li, Na, K, Cu, and Ni.

The present invention will be described more specifically with reference to the following examples. However, it is needless to say that the examples are shown by way of example and should not be interpreted in a limited manner.

Example 1
Using a purification apparatus having the same structure as the purification apparatus shown in FIG. 1 and FIG. 2, the purification process was performed on the natural quartz glass processed product and the synthetic quartz glass processed product according to the following procedure.
First, the internal atmosphere of the purification container of the purification apparatus to be used was replaced with nitrogen from the day before the purification process. The procedure of the purification treatment was performed according to the pattern shown in FIG. First, the temperature in the purification container was raised from room temperature to 1100 ° C. over about 2 hours. Hydrogen chloride gas was used as the purification treatment gas, and the gas flow rate was set to about 10 L / min. Subsequently, it was maintained at 1100 ° C. for 2 hours and 30 minutes in a state where a purification gas was introduced (about 10 L / min). Thereafter, the heating was stopped (with the heater turned off) in a state where the purification gas was similarly introduced (about 10 L / min), and natural cooling was performed. The temperature was lowered from 1100 ° C. to 800 ° C. in about 2 hours. Subsequently, nitrogen gas was flowed in place of hydrogen chloride gas (about 7 L / min), and nitrogen was replaced in the purification vessel, followed by natural cooling, and the temperature was lowered to 200 ° C. in about 16 hours. Then, the inside of the purification container was opened, and the quartz glass processed product was taken out using clean gloves after waiting for 20 to 30 minutes until the temperature of the purified quartz glass processed product fell to a manageable temperature. Concentrations of contamination elements (Li, Na, K, Cu, Ni) were measured on the surface layers 20 μm to 30 μm of the natural quartz glass processed product and the synthetic quartz glass processed product thus purified. As a result, it was found that any element of Li, Na, K, Cu, and Ni was not detected in the purified natural quartz glass processed product and synthetic quartz glass processed product, and was below the detection limit (10 ppb).

G: quartz glass processed product, 10: purification apparatus, 11: base frame, 12: housing, 14: top wall, 16: side wall, 18: bottom wall, 20: hollow interior, 22: through hole, 24: Bottom wall opening, 26: quartz glass purification treatment vessel, 26a: upper stage cylindrical body, 26b: lower stage cylindrical body, 26c: wall body, 28: exhaust port, 30: bottom opening, 32: heater, 34: Holding means, 35: set base, 35a: upper base member, 35b: lower base member, 36: top plate, 36a: top plate through hole, 38: bottom plate, 38a: bottom plate substrate, 40: support, 40a: inner support, 40b: outer support column, 41: receiving column, 42: opaque plate, 42a: upper opaque plate, 42b: lower opaque plate, 44: side column, 46: movable support plate, 48: gas introduction part, 48a: inner ventilation through hole 48b: outer ventilation through hole, 49: gas introduction 50: gas exhaust part, 51: gas exhaust passage, 52: peripheral member, 54: bottom plate annular groove part, 56: first O-ring, 58: outer surface member, 60: lower surface member, 62: receiving step part, 64: Step assisting member, 66: first step, 68: second step, 70: second O-ring, 74: lower surface member annular groove, 76: third O-ring, 78: groove, 80: cooling mechanism, 82: penetration Hole: 84: Flow meter, 86: Introduction valve, 88: Introduction gas pressure gauge, 90: Exhaust pressure gauge, 92: Exhaust valve, 94: Pressure adjustment indicator.

Claims (11)

A housing having a through hole in the top wall and a bottom wall opening in the bottom wall;
Made of cylindrical quartz glass provided inside the casing with the lower end portion inserted in a sealed state into the bottom wall opening of the casing and the lower end hanging downward from the bottom wall of the casing A purification vessel;
A heater that is provided outside the purification container and that heats the interior of the purification container to form a heat zone;
A bottom opening for storing and taking out a quartz glass processed product provided by opening the bottom of the purification processing container in order to store and take out the quartz glass processed product to be purified from the purification processing container. ,
A closing means for closing the bottom opening in a sealed state;
Before the purification treatment, the quartz glass processed product can be stored in the purification processing container from below, and the quartz glass processed product is not purified directly in contact with the purification processing container during the purification treatment. A holding means that can be held in the heat zone of the processing vessel and can move up and down after the purification process is completed, so that the quartz glass processed product after the purification process can be carried out downward,
A gas introduction part provided at a lower end of the purification treatment container and for introducing gas into the purification treatment container;
The exhaust port opened in the upper part of the purification container and the through-hole opened in the top wall of the casing are formed to communicate with each other, and the gas in the purification container is exhausted to the outside of the casing. A gas exhaust passage for,
A quartz glass processed product purification apparatus, wherein the quartz glass processed product held by the holding means can be purified in the purification container. When the lower end portion of the purification treatment container is inserted into the bottom wall opening of the housing, the bottom wall opening and the purification treatment container are brought into a sealed state so that the bottom wall opening is brought into contact with the bottom wall opening. 2. The purification apparatus according to claim 1, further comprising a cooling mechanism for installing an O-ring having elasticity on a surface and cooling a portion where the O-ring is installed. The cylindrical purification vessel has a two-stage structure in which an upper stage cylindrical body and a lower stage cylindrical body are connected in series, and the inner diameter of the lower stage cylindrical body exceeds the inner diameter of the upper stage cylindrical body. The purification apparatus according to claim 1 or 2, wherein The purification apparatus according to any one of claims 1 to 3, wherein one or more gas introduction parts for introducing the gas are arranged in a range including a lower central part of the purification process container. The holding means for holding the quartz glass processed product includes a top plate on which the quartz glass processed product is placed, a bottom plate installed below the top plate with a predetermined interval, and between the top plate and the bottom plate. A plurality of support posts attached at predetermined intervals, and heat shielding means comprising a plurality of opaque plates stacked at predetermined intervals between the top plate and the bottom plate via the support posts. The purification apparatus according to any one of claims 1 to 4.   The outer peripheral portion of the bottom plate of the holding means is in a state where the quartz glass processed product is raised while being placed on the top surface of the top plate of the holding means and the quartz glass processed product is stored in the purification treatment container. 6. The purifying apparatus according to claim 5, wherein the purifying apparatus acts as a closing means for closing the bottom opening in a sealed state by contacting the peripheral edge of the bottom opening of the purifying container in a sealed state. . A method for purifying a quartz glass workpiece using the purification apparatus according to any one of claims 1 to 6,
A process for storing a processed quartz glass product to be purified in the purification container from the bottom opening of the purification container, a process for closing the bottom opening in the purification container, and the inside of the purification container are not performed. Replacing with active gas;
A temperature raising step of raising the temperature in the purification treatment vessel from room temperature to a predetermined purification treatment temperature while flowing a purification treatment gas into the purification treatment vessel;
A purification process step of performing a purification process over a predetermined time at a predetermined purification temperature while continuously flowing the purification gas into the purification container;
A step of lowering the gas to a gas switching temperature while flowing the purification gas into the purification container after the purification process is completed;
A step of switching the purification gas to an inert gas when the temperature in the purification vessel reaches a gas switching temperature;
Cooling the inert gas into the purification container while lowering the quartz glass processed product to a temperature at which it can be removed;
When the temperature in the purification container reaches a temperature that can be taken out, the step of taking out the processed quartz glass product from the bottom opening of the purification container;
A method for purifying a processed quartz glass product, comprising:   The purification method according to claim 7, wherein the purification treatment gas is a gas containing HCl or Cl. 9. The method for purifying a quartz glass processed product according to claim 7, wherein the purification treatment temperature is 900 ° C. or more and 1300 ° C. or less, and the purification treatment time is 30 minutes or more. The method for purifying a quartz glass processed product according to any one of claims 7 to 9, wherein a gas switching temperature after the purification treatment is 800 ° C or higher and 850 ° C or lower. The purifying gas inflow operation into the purifying container of the purifying gas is used for the purifying gas used in the purifying process together with the introduction of the purifying gas from the gas introduction part of the purifying gas. The exhaust gas from the exhaust passage is used, and the pressure in the purification container is controlled to be higher than atmospheric pressure and lower than 1 kPa during the purification process gas inflow operation. The purification method of the quartz glass processed goods of description.

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