JP3327364B2 - Method for producing silica glass processed product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invention capable of easily and inexpensively manufacturing a processed silica glass product having a predetermined size from silica glass as a raw material. The present invention relates to an invention of a processed silica glass product used as a protective tube, a crater of a glass burner, a bubbler tube, a member for physical and chemical equipment, a heat treatment jig material also serving as a gas pipe, a member for a semiconductor heat treatment jig, and the like.

[0002]

2. Description of the Related Art Conventionally, a silica glass jig having high chemical stability and heat resistance has been used as a semiconductor jig incorporated in a wafer heat treatment apparatus. All of them require a high-purity, high-dimensional accuracy, low-cost, and quality-free manufacturing method. Burners for processing these jigs or burners for producing synthetic quartz by oxyhydrogen flame hydrolysis are also formed of silica glass, but such burners blow gas into a large-diameter outer tube. Although a configuration is made in which a plurality of inner tubes constituting the mouth are inserted, it is difficult to hermetically and accurately weld the inner tube to the outer tube via a spacing member.

On the other hand, in recent years, in a sensor for detecting a temperature, a gas concentration, and the like in a high-temperature atmosphere, a multi-hole silica glass rod having a large number of axial holes formed in an axial direction in order to improve insulation and heat resistance. A sensor device in which the sensor is inserted has been developed. In such a multi-hole silica glass rod for a sensor, in order to prevent noise of a detection signal from the sensor, high purity and high dimensional accuracy without impurities are mixed. A rod is required.

Conventionally, in order to produce a multi-hole silica glass tube for such an application, a method of preparing several tubes and then welding them to integrate them has been adopted. Therefore, the cost was large.

A bubbling cleaning device used for cleaning silicon wafers and other members for semiconductor heat treatment jigs, and a method for bubbling a raw material liquid when producing soot-like synthetic silica glass from a high-purity liquid raw material. Among the used bubbling vaporizers, a large number of inner tubes are inserted into a large-diameter outer tube, and a bubbler tube in which a number of small holes are perforated by machining a solid bar of silica glass has been developed. However, in such a bubbler tube, the small holes must be formed by welding or machining, and the following problems cannot be avoided in these methods.

[0006]

That is, in the method by machining, a processed silica glass product is manufactured from bulk silica glass by cutting, laser processing, or the like. However, in this method, silica glass is a brittle material, so Not only are cracks and breakage easily caused by shearing due to cutting, but also contamination from cutting jigs and the like occurs. Furthermore, the cutting process has a limitation on the drill length, and in particular, a long multi-hole silica glass cannot be produced. In the case of a multi-hole silica glass, not only cannot a multi-hole silica glass having a fine hole size be produced, but also a multi-hole silica glass having various dimensions and shapes cannot be continuously produced.

[0007] In order to solve such a drawback, a processing method by heat molding or heat and pressure molding has been proposed. That is, there is a method of filling a silica powder in a mold made of carbon or the like, or putting a lump, and manufacturing a silica glass processed product of a predetermined shape by heat molding or heat and pressure molding. Dimension control cannot be performed accurately. In the case of multi-hole silica glass products, various dimensions,
Not only cannot the shape of the multi-hole silica glass be continuously produced, but also problems such as contamination from the furnace occur.

[0008] In view of the above technical problems, the present invention provides a method for producing a processed silica glass product from a silica powder raw material.
An object of the present invention is to provide a method for producing a processed silica glass product having high dimensional accuracy without chipping or cracking. Another object of the present invention is to provide a method for producing a processed silica glass product which can be continuously produced without roughening, flaws, etc. on the surface of the manufactured silica glass processed product, particularly in the case of a multi-hole silica glass processed product. Is to provide. Another object of the present invention is to provide a method for producing a processed silica glass article which maintains high purity similarly to the raw material without causing contamination of impurities in the production process.

Another object of the present invention is to provide a multi-hole silica glass having a long dimension, a plate having a thickness of several mm, and extending in the axial direction such as a rod having a length of 10 m or a fiber having a length of several tens m. It is an object of the present invention to provide a method for producing a processed silica glass article that can arbitrarily generate an arbitrary profile shape as long as the shape exists.

Another object of the present invention is to provide a method for producing a processed silica glass article which can easily and arbitrarily produce a multi-hole silica glass processed article having a small diameter to a large diameter. Another object of the present invention is to provide, for example, a thermocouple insulating tube, a protective tube for various sensors, a crater of a glass burner, a bubbler tube, a physicochemical device member, a heat treatment jig material also serving as a gas pipe, and a member for a semiconductor heat treatment jig. It is an object of the present invention to provide a manufacturing method capable of easily and inexpensively manufacturing a processed silica glass product applied as the above.

[0011]

Means for Solving the Problems The invention described in claim 1 is applied to a processed silica glass product having one or more small holes in a rod. A tubular heated object was prepared by inserting one or more silica glass inner tubes having a circular or polygonal cross-sectional shape extending in the axial direction into a hollow silica glass outer tube having a cross-sectional shape extending in the axial direction. Thereafter, the particle size was adjusted to 50 to 500 microns from the tip of the gap between the outer tube and the inner tube in the object to be heated .
Filled with a powder mainly composed of amorphous silica powder composed of synthetic silica powder, and then filled with a powder composed mainly of quartz powder or other crystalline silica powder, and filled with the silica powder. Reduce the pressure between the outer and inner pipes of the
In a state where the pressure is released, the object to be heated is heated and melted along the axial direction by zone heating from the front end side and stretched and integrated.

[0012] The invention according to claim 2 is applied to a processed silica glass product having a plurality of small holes in a rod (hereinafter referred to as a multi-hole tube), and an arbitrary cross-sectional shape extends in the axial direction. After inserting a plurality of silica glass inner tubes having a circular or polygonal cross-sectional shape extending in the axial direction into the existing hollow silica glass outer tube to form a tubular body to be heated, the outer tube in the body to be heated is formed. At least a portion of the gap between the inner tube and the inner tube is filled with silica powder, and the outer tube of the body to be heated filled with the silica powder is filled.
With a reduced pressure between the inner tube and the inner tube and a positive pressure open inside the inner tube
Then, the object to be heated is heated and melted along the axial direction by zone heating from the distal end side and integrated to produce a multi-hole tube having a plurality of small holes in the rod. . In this case, in order to manufacture a multi-hole tube, a portion of the gap between the outer tube and the inner tube in the body to be heated, which is to be uniformly filled with silica glass, is filled with silica powder. The outer tube and the inner tube may be integrated by heating without a gap. Preferably, the particle size is 50 to 500 microns from the tip of the gap between the inner tube and the outer tube of the object to be heated.
It is preferable to fill a powder containing amorphous silica powder as a main component composed of a synthetic silica powder adjusted to a powder, and then to fill a powder containing quartz powder or other crystalline silica powder as a main component. .

[0013]

Further, after filling a powdery material containing amorphous silica powder as a main component from the tip of the gap between the outer tube and the inner tube of the object to be heated, quartz powder or other crystalline silica powder is added as a main component. When the powdery material is filled, it is preferable that the particle size of the crystalline silica is in the range of 10 to 1000 μm and the content ratio of fine particles having a particle size of less than 10 μm is 0.1 wt% or less.

The reason for specifying the silica powder in this way is as follows. When the zone where the silica glass is uniformly filled is filled with amorphous silica powder and zone melting is performed, such an amorphous silica powder has no so-called melting point and gradually softens from around 1600 ° C. Because of melting, a deposition gas or the like from the silica powder is entrained, and a silica glass body in which bubbles remain is formed.

On the other hand, crystalline silica powder such as quartz powder is 1730
Since it has a melting point at ℃, it can be melted at once by heating to 1730 ℃ or more, and the generation of bubbles in the molten glass can be suppressed as much as possible. However, crystalline silica powder such as quartz powder has α-type at 573 ℃. To have a transition point from the β-type to the tubular-heated body at the start of heating before the viscosity of the tubular-heated body is reduced. The object to be heated is destroyed.

Accordingly, the present invention provides a method for converting α-type to β-type by providing a powdery material mainly composed of amorphous silica powder having no transition point on the tip side where the zone is heated first. While preventing the existing tube from breaking, the viscosity of the hollow tube decreases due to the preheating of the heat zone already in the upper region, and the crystalline silica powder in that portion undergoes rapid expansion due to the transition from α-type to β-type. The crystalline silica powder such as quartz powder is filled only in the area where the tube can be prevented from being broken. It is necessary that the filling width of the amorphous silica powder is larger than the heat zone (soaking width) of the zone heating means. However, if it is too large, a substantial bubble-free area is reduced, and productivity is reduced. In order to reduce the content, the content is preferably less than 20% of the total filling amount of the powder.

The crystalline silica powder is any one of a natural quartz powder, a synthetic quartz powder and a synthetic cristobalite powder, and has a particle diameter of 10 to 1000 μm, preferably 20 to 500 μm, more preferably 50 to 500 μm. The content ratio of fine particles in the range of 200 μm and less than 10 μm is 0.1 w
It must be less than t%. The particle size is 1
If the thickness is less than 0 μm, even if a vacuum is applied, a pressure loss occurs, so that the inside of the filling region cannot be evacuated, and even if the zone is melted, bubbles are difficult to be removed, and a large amount of bubbles are contained in the fused silica glass. In addition, the heat insulation effect makes it difficult to uniformly heat and melt the central portion of the tubular object to be heated. If the particle diameter is 1000 μm or more, uniformity cannot be achieved during melting, and similarly, even if quartz powder is used, the generation of bubbles cannot be eliminated due to wide voids between the powders.

The silica powder is filled by filling the lower end of the powder-filled area of the tubular body with amorphous silica powder first, and then filling a mixed powder of amorphous silica powder and crystalline silica powder. Finally, the crystalline silica powder is preferably filled.

When a high-purity rod is manufactured, natural crystalline silica powder may not be used as described above. In such a case, the high-purity synthetic amorphous silica powder is preferably filled after a heat treatment in a hydrogen-containing atmosphere or a helium-containing atmosphere in advance. As a result, even if residual gases consisting of hydrogen and helium are present during the zone melting, they are occluded / doped in the molten glass at the time of melting, and the generation of bubbles can be prevented. Even if silica powder is used, a substantially glass-free silica glass rod can be produced.

The silica powder may be a silica powder obtained by mixing a metal or metal element compound powder in advance. In this case, it is preferable that the depressurized atmosphere in the powdery filling region at the time of heating and melting is set to a vacuum of 1 KPa or less so that entrainment and expansion of gas can be prevented.

Incidentally, the multi-hole silica rod of the present invention comprises:
It is applied as a thermocouple insulating tube, a sensor protection tube, a sealing member, a glass burner crater, a bubbler tube, a member for physical and chemical equipment, and a member for a semiconductor heat treatment jig.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be illustratively described in detail below. However, the materials, shapes, analytical values, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples, unless otherwise specified. .

First, the procedure for manufacturing a multi-hole, rod-shaped double bore tube for a thermocouple will be described with reference to FIGS. (1) Preparation of silica glass outer tube, substantially tubular body (hereinafter referred to as inner tube), etc. As shown in FIG. 2, silica glass outer tube 1 having a diameter of 40 mm, a wall thickness of 1.5 mm, and a length of 1.2 m, and Two inner tubes 2 made of silica glass having a diameter of 15 mm, a thickness of 1.5 mm, and a length of 1 m for insertion into the inside were prepared. Also, diameter 40m
m, a disk-shaped silica glass plate (bottom plate 3) with a processing dimension accuracy of ± 0.1 mm in which two holes 3a each having a diameter of 15 mm are formed symmetrically in the center, and a gas vent hole 5a in the center with the same outer diameter. Silica glass plate (cover plate 5 for degassing) and a diameter of 37
mm, and two 15 mm-diameter holes 6b were formed symmetrically at the center, and one silica glass plate (middle plate 6) provided with degassing holes 6a on both the upper and lower sides was prepared.

(2) Processing of the outer pipe and the inner pipe As shown in FIG. 1 (A), each inner pipe 2 inserted inside
One end 2a of the inner tube 2 and then open the other end 2a of the inner tube 2.
After the b side is fitted into the hole 3a of the bottom plate 3, it is welded to the bottom plate 3 with the opening end 2b opened.

Next, as shown in FIG. 1 (B), after the intermediate plate 6 is attached near the closed end on the inner tube 2 sealing end side, FIG.
As shown in (1), the inner plate 6 is inserted into the outer tube 1 from the mounting side, and the periphery of the bottom plate 3 located at the end side and the end of the outer tube 1 are hermetically welded and fixed. Finally, as shown in FIG. 1 (D), a gas vent cover plate 5 is hermetically welded and fixed to the upper end of the outer tube 1. As a result, the end 2a of the inner tube 2 in the outer tube 1 is sealed, and the other end 2b side of the inner tube 2 is opened on the bottom plate 3 of the outer tube 1. Therefore, even when the pressure is reduced through the gas vent hole 5a of the cover plate 5, the inner pipe 2 can maintain the positive pressure.

(3) Thermal distortion removal treatment of the object to be heated 10 The object to be heated 10 formed as described above is subjected to 105 heating by a heater.
After performing a heat treatment at 0 ° C. for 10 hrs to remove the heat distortion, the object to be heated is immersed in a 10 wt% aqueous solution of hydrogen fluoride for 10 minutes to wash and remove microcracks, and then dried in a clean atmosphere. Done.

(4) Preparation of Main Raw Material Silica Powder and Purification by Heating The type of silica powder is at least one of natural quartz, synthetic quartz, synthetic cristobalite, and synthetic silica glass.
The heat purification treatment is performed in an atmosphere containing chlorine gas, hydrogen chloride gas, or the like. When amorphous silica powder is used, the heat purification treatment is preferably performed in a hydrogen-containing atmosphere or a helium-containing atmosphere. The particle size of the silica powder is 10 to 1000 μm.
m is preferred. Below this, a large amount of bubbles are contained in the fused silica glass body 3. Above this, it is not uniform at the time of melting or it is difficult to remove air bubbles.

Therefore, in the present embodiment, as a crystalline silica powder as a main raw material, a natural quartz powder was adjusted to a powder having a particle size in the range of 50 to 500 μm and less than 10 μm to 0.1 wt% or less.
If necessary, in order to increase heat resistance and the like, a metal element compound powder or the like may be mixed after the purification treatment. In this case, the concentration of the specific doping element in the manufactured silica glass rod is 0.1 to 5 wt. %, The mixing ratio of the powder for doping and the silica powder of the main raw material is preferably set.

(5) Preparation of Synthetic Silica Glass Powder The synthetic silica glass powder produced by the sol-gel method has a particle diameter of 50 to 50%.
It was adjusted to 500 μm.

(6) Filling and Filling of Silica Glass Powder into Body to be Heated When crystalline silica is used as the main raw material silica powder, synthetic silica glass powder 7a is put into the lower end portion of the non-heated body and then gradually. The powder with an increased ratio of crystal powder such as crystal powder is added to the mixture. The filling length of the silica glass powder 7a at the lower end must be longer than the soaking length of the heater 8 used for melting. The reason for this is that the quartz glass powder 7b is suddenly put in without the silica glass powder 7a in the tip portion, and when the temperature is increased by the heater 8, the crystal suddenly expands at the α-type β-type transition temperature of the crystal. 1 will be destroyed. In addition, when using amorphous silica glass as the main raw material powder,
The same type of silica glass powder 7 may be sequentially filled from the tip.

Therefore, in the present embodiment, as shown in FIGS. 3A and 3B, first, 50 g of synthetic silica glass is passed through the gas vent hole 5a of the cover plate 5 through the notch 6a of the middle plate 6. powder 7a was charged, then natural crystal: synthetic silica glass = 1: 2 mixture powder 7a ₁ (weight ratio) was charged with 50 g, further natural crystal: synthetic silica glass = 1: 1 mixed powder 7a ₂ of 50g was charged, further natural crystal: synthetic silica glass = 2: the powder mixture 7a ₃ of 1 was charged 50g.
Finally, 500 g of natural crystal powder 7b was filled. As a result, the synthetic silica glass powder layer 7a was 6 cm, and the mixed powder 7a
₁ , the layer of the mixed powder 7a ₂ and the layer of the mixed powder 7a ₃ each become 6 cm, and the total of these layers is the soaking length (5 cm) of the heater 8.
I was able to make it bigger.

(7) Melting and Transparent Vitrification Using Heater 8 Next, as shown in FIG.
After evacuating the area filled with the silica powder between the inner tube 2 and the outer tube 1 from the (cylindrical portion) to 10 Torr or less, the heating target 10 including the inner tube 2 and the outer tube 1 is slowly moved. While being inserted into the heater 8 from above the heater 8, the zone melting and the drawing are performed by controlling the feeding speed into the heater 8 and the drawing speed of the silica glass melted by the heater 8, thereby forming a transparent rod-shaped. Obtain a double bore tube 9.

At this time, since the internal pressure of the inner tube 2 inserted into the outer tube 1 is open to the atmosphere or positive pressure, it is larger than that of the powder-filled area under reduced pressure. Never closes. Further, since the positive pressure is released, the internal pressure of the inner tube 2 does not needlessly increase by heating, and is heated and melted while maintaining accurate dimensional accuracy.
The diameter of the bore tube 9 is 1 / the diameter of the object to be heated 10.
In this embodiment, it is preferable to adjust the feed speed of the heated object 10 into the heater 8 and the pulling speed of the vitrified double bore tube 9 so that the outer diameter φ is 10 mm and the inner diameter φ 3 mm. Thermocouple double bore tube was made.

(8) Evaluation of physical properties The generation of air bubbles in the double bore tube 9 manufactured as described above is 10
The total area of the foam present at 0 cm ³ was 0.88 mm ² . (However, the measuring method is DIN58927 (1970)
Obey. This is the applicant's product used for semiconductor jigs:
It is at the same level as Heralux-E, and it can be said that substantially no bubbles are generated. Next, the dimensional accuracy of each of the double-bore pipes 9 manufactured as described above has an outer diameter of 10 m.
m, inner diameter φ 3 mm, outer diameter radial direction circumferential runout tolerance ± 0.1 (mm) outer diameter radial direction whole circumferential runout tolerance ± 0.2 (mm), inner bore radial direction circumferential runout tolerance ± 0.03 ( mm) and the inner diameter radial direction full-circumference runout tolerance ± 0.06 (mm). The surface condition was very smooth without any scratches.

In the impurity analysis, Table 1 shows the natural quartz powder before melting and the impurity concentration after vitrification.

[0037]

[Table 1]

From this table, it is understood that the high purity of the raw material powder is well preserved even after vitrification. Note that Li, M
g and Ti were determined by ICP mass spectrometry, and Na, K, C
a, Cr, Fe, Ni, and Cu were measured by graphite furnace heating atomic absorption spectrometry.

(Example 2) A double bore tube was prepared in the same manner as in Example 1. (1) Preparation of Outer Tube 1, Inner Tube 2, etc. Made of Silica Glass As shown in FIG. 5, an inner tube 2 and an outer tube 1 each having a diameter of 40 mm and a wall thickness of 1.5 mm are prepared as in the previous embodiment. In the case of this embodiment, the length of the inner tube 2 is made longer than that of the outer tube 1. Also, as shown in FIG. 5, the bottom plate 3 is the same as that of the above-mentioned embodiment, but the center plate 6 is not provided, and a hole 5b having a diameter of 15 mm is
And a gas vent cover plate 5 having a gas vent hole 5a at the bottom was prepared.

(2) Processing of Heated Body 10 of Silica Glass As shown in FIG. 6A, the other end of the inner tube 2 at the open end 2b side is fitted into the hole of the bottom plate 3 and then the open end 2b Is welded to the bottom plate 3 in a state where is opened. Next, as shown in FIG. 6B, after the cover plate 5 is fixed to the inner tube 2 corresponding to the length of the outer tube 1, the cover plate 5 is inserted into the outer tube 1 from the side where the cover plate 5 is attached, and The periphery of the located bottom plate 3 and the end of the outer tube 1 are hermetically welded and fixed. Finally, as shown in FIG. 6 (C), the lid plate 5 is hermetically welded and fixed in a state where the inner pipe 2 is projected from the outer pipe 1. As a result, the inner tube 2 protrudes above the outer tube 1 from the cover plate 5, and the other end 2 b side of the inner tube 2 opens on the bottom plate 3 of the outer tube 1. Even if the pressure is reduced through the gas vent hole 5a, the inner tube 2 can maintain a positive pressure. After the processing, similarly to the above-described embodiment, the heat distortion removal treatment of the silica glass heated object 10 is performed.

(3) Atmospheric heat treatment of high-purity synthetic silica glass powder Synthetic silica glass powder produced by the sol-gel method has a particle diameter of 50 to 50%.
It was adjusted to 500 μm. Heat treatment was performed at 800 ° C. for 3 hours in a H ₂ gas atmosphere in an atmosphere electric heating furnace having a tungsten mesh heater and a stainless steel jacket.

(4) Injection and Filling of Silica Glass Powder into Heated Body 10 Since amorphous silica glass is used as the main raw material powder, the same kind of silica glass powder 2 is sequentially filled from the tip portion. Just do it.

(5) Melting and Transparent Vitrification Using Heater 8 As shown in FIG. 7, the silica powder between the inner tube 2 and the outer tube 1 is filled through the gas vent hole 5a of the flange as in the previous embodiment. While the inside of the section was evacuated to 10 Torr or less, and maintained at a higher pressure in the inner tube 2, for example, a positive pressure,
By performing zone melting and drawing in the same manner as in the above embodiment,
A transparent rod-shaped double bore tube 9 is obtained. At this time, the internal pressure of the inner pipe 2 inserted therein is larger than that of the powdered material filling area under reduced pressure, and the hole of the inner pipe 2 can be maintained at a predetermined dimensional accuracy without being closed by melting. Although high-purity synthetic silica was used for the silica powder to be filled and the silica glass to be heated 10 and the like, the physical properties of the double-bore tube produced were the same as in Example 1, and the results of the impurity analysis are shown in Table 2. Shown in
From this table, it can be seen that the high purity of the raw material powder is maintained well after vitrification.

[0044]

[Table 2]

According to this embodiment, for example, FIG.
It is also possible to manufacture a large-diameter multi-hole rod 12 as shown in FIG. The arrangement cross-sectional shape of the inner tube 2 can be set arbitrarily as shown in FIG. Further, since the inner tube 2 is maintained under an open positive pressure, it is possible to perform zone heating while maintaining the shape accurately. For example, as shown in FIG. Is also possible.

Further, by changing the drawing speed, a tapered multi-hole rod can be manufactured.

[0047]

As described above, according to the present invention, when producing a processed silica glass product from a raw material of silica glass, it is possible to obtain a processed silica glass product having high dimensional accuracy without chipping or cracking. Further, according to the present invention, it is possible to obtain a processed silica glass product which can be continuously manufactured without roughening, scratches and the like on the surface of the manufactured silica glass processed product, particularly in the case of a multi-hole silica glass processed product. I can do it. According to the present invention, it is possible to obtain a processed silica glass product in which high purity is maintained in the same manner as the raw material without causing contamination of impurities in the manufacturing process. According to the present invention, a multi-hole silica glass having a long dimension, a plate having a thickness of several mm, a rod having a length of 10 m, or a fiber extending in the axial direction such as a fiber having a length of several tens of meters can be used. Any profile shape can be generated arbitrarily. According to the present invention, it is possible to easily and arbitrarily create a multi-hole silica glass product having a small diameter to a large diameter. According to the present invention, for example, it is used as a thermocouple insulating tube, a protective tube for various sensors, a crater of a glass burner, a bubbler tube, a physicochemical device member, a jig material for heat treatment which also serves as a gas pipe, a member for semiconductor industry, and the like. The processed silica glass product can be easily and inexpensively obtained.

[Brief description of the drawings]

FIGS. 1A, 1B, 1C, and 1D show manufacturing steps for manufacturing a body to be heated from the materials shown in FIGS.

FIG. 2 shows a material for a silica glass object to be heated according to an example of the present invention.

FIG. 3 shows a state in which silica glass powder is charged and filled into a body to be heated.

FIG. 4 shows a molten transparent vitrification process using a heater.

FIG. 5 shows materials for a silica glass object to be heated according to a second embodiment of the present invention.

FIGS. 6A, 6B, and 6C show a manufacturing process for manufacturing a body to be heated from the material shown in FIG. 2;

FIG. 7 shows a transparent vitrification process using a heater.

FIG. 8A shows a large-diameter multi-hole rod manufactured according to the present invention, and FIG. 8B shows various examples of its cross-sectional shape.
(C) is a square multi-hole rod manufactured by the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Bottom plate 5 Cover plate 6 Middle plate 7 Raw material silica powder 7a Amorphous silica powder 7b Quartz powder 8 Heater 10 Heated object

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanori Suzuki 88 Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Shin-Etsu Quartz Co., Ltd. Koriyama Plant (56) References JP-A-58-204830 (JP, A) 63-282134 (JP, A) Patent 3258175 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 20/00 H01L 21/22 501 G01K 1/00

Claims (3)

(57) [Claims] 1. A tube formed by inserting one or more silica glass inner tubes having a circular or polygonal cross section extending in the axial direction into a hollow silica glass outer tube having an arbitrary cross section extending in the axial direction. After forming the object to be heated, a particle size of 50 to 500 microns is measured from the tip of the gap between the outer tube and the inner tube in the object to be heated.
Filled with a powder mainly composed of amorphous silica powder composed of synthetic silica powder adjusted to the above, and then filled with a powder composed mainly of quartz powder or other crystalline silica powder, the silica powder In a state where the space between the outer tube and the inner tube of the object to be heated is filled under reduced pressure and the inside of the inner tube is opened under a positive pressure , the object to be heated is heated and melted along the axial direction by zone heating from the distal end side. A process for producing a processed silica glass product, characterized by being stretched and integrated. 2. A tube to be heated by inserting a plurality of silica glass inner tubes having a circular or polygonal cross section extending in the axial direction into a hollow silica glass outer tube having an arbitrary cross section extending in the axial direction. After the body is made, at least a part of the gap between the outer tube and the inner tube in the heated body is filled with silica powder ,
Reduce the pressure between the outer and inner pipes of the heated object filled with lica powder.
In a state where the inside of the inner tube is opened to a positive pressure , the object to be heated is heated and melted along the axial direction by zone heating from the distal end side to be integrated, and a plurality of small holes are present in the rod. A method for producing a processed silica glass product, which comprises producing a tube. 3. A synthetic silica particle having a particle size adjusted to 50 to 500 microns from a tip of a gap between an inner tube and an outer tube of the object to be heated.
Claim, characterized in that formed by filling a powdery body consisting mainly of quartz powder other crystalline silica powder of amorphous silica powder consisting of powdery subsequently filled with powdery bodies mainly 2 A method for producing a processed silica glass product according to the above.