JP2610056B2 - Quartz glass member for semiconductor heat treatment and method of manufacturing the same - Google Patents

Description

The present invention relates to a quartz glass member that can be suitably used for a furnace tube for heat treatment of a semiconductor wafer, other jigs, and the like, and more particularly, to a quartz glass member having a large melt viscosity. Heat resistance and mechanical strength, which are made by heating and fusing two different types of quartz glass in a laminate,
In particular, the present invention relates to a quartz glass member having a composite layer structure excellent in impact strength and an effective manufacturing method thereof.

[Conventional technology]

Conventionally, furnace tubes and wafer heat treatment jigs used for heat treatment of semiconductor wafers are, for example, not deformed in a high-temperature region of 1000 to 1300 ° C., and metal in a furnace atmosphere in a heat treatment process of semiconductor wafers. In particular, it is required to prevent contamination by alkali metals,
As such a material, particularly, high-purity quartz glass having a small content of metal impurities is used.

Despite the fact that furnace tubes and jigs for semiconductor heat treatment are provided with high-purity quartz glass material, cleaning such as regular cleaning is performed to keep the atmosphere inside the furnace always clean. I have. However, quartz glass is generally extremely vulnerable to impact, and in many cases, damage such as cracking or chipping easily occurs in a cleaning operation, making it unusable. In addition, when handling other processes, for example, inserting or removing a furnace tube into or from a furnace for heat treatment of semiconductor wafers, or removing or inserting jigs such as a wafer boat or a heat retaining tube into or out of the furnace tube, the core tube may be reduced by one dimension. Cracking and chipping easily occur due to the impact, and a disadvantage in use that care must be taken in handling is inevitable. Therefore, their handling is cumbersome and a major constraint on their use.

In particular, with the recent increase in the integration of semiconductor chips, the diameter of wafers has increased, the furnaces have also increased in size, and the corresponding quartz glass furnace tubes and related jigs have increased in size. The damage phenomenon as described above has become a more serious problem industrially.

On the other hand, as a method of improving the mechanical strength of glass,
A method of applying strain by generating strain by rapidly cooling the glass member from a high temperature is generally known.However, when this method is applied to quartz glass, a large temperature difference is required to generate sufficient strain. Therefore, it is difficult to generate controlled strain, and in particular, it has not been possible to apply stress in a certain direction. In addition, in this method, there is a risk of damage due to the distortion itself generated, and improvement in impact resistance cannot be expected. Furthermore, since quartz glass has a small coefficient of thermal expansion, it is practically extremely difficult to effectively apply stress.

[Problems to be solved by the invention]

Accordingly, it is an object of the present invention to provide a quartz glass member having improved impact resistance which can be stably used for a long period of time without being damaged by any impact. Another object of the present invention is to provide a high-purity quartz glass furnace tube which has excellent heat resistance even under high temperature conditions in heat treatment of a semiconductor wafer and does not substantially contaminate the wafer. It is to provide members such as tools. Yet another object is to provide an effective and practical method of manufacturing such a member.

[Means for solving the problem]

The present inventors have focused on the characteristics of quartz glass having a very small coefficient of thermal expansion and conducted many experiments on a method of overcoming the above technical problem, and in particular, the annealing point has a viscosity difference of 50 ° C. or more. The present inventors have found that a member obtained by heat-sealing and integrating relatively large quartz glass in a laminated shape can effectively satisfy the above-mentioned problems, and have reached the present invention.

That is, the present invention relates to a quartz glass material having a multilayer structure obtained by heating and fusing two kinds of quartz glass having different viscosities in a laminated manner, wherein the viscosity has a difference of 50 ° C. or more as an annealing point. Quartz glass is a quartz glass member for semiconductor heat treatment with improved impact resistance, which is melt-integrated into a composite layer, and holding such two kinds of laminated quartz glass having different viscosities vertically, The present invention provides an effective method for producing a material useful for semiconductor heat treatment, characterized by extending a molten portion downward while moving a heating region upward from a lower portion thereof.

The annealing point related to the viscosity difference of quartz glass in the present invention refers to ASTM C336 (Test Method for Anealing Poin).
t and Strain Point of Gl-ass by Fiber Elongatio
It can be determined by measuring the fiber elongation according to the method specified in n), and is a temperature at which the viscosity of the glass becomes 10 ^13.0 poise.

The difference between the annealing points is, as understood from the measurement contents, a means for indicating the difference in the high-temperature viscosity between the two types of quartz glass. In some cases, a controlled strain is effectively generated along the fusion surface due to the heat fusion of the two glass layers, thereby forming a stress applying layer on the composite member and obtaining the obtained composite quartz glass member. Is based on a technical discovery that the mechanical strength of the steel is greatly improved.

Therefore, the quartz glass member for semiconductor wafer heat treatment according to the present invention is a combination of a high-viscosity quartz glass layer having heat resistance and a low-viscosity, high-purity synthetic quartz glass layer whose annealing point is 50 ° C. or lower. A composite layered quartz glass member provided by fusing and integrating the joining surfaces thereof, which is extremely practical with excellent heat resistance and impact resistance.

If the difference between the annealing points is less than 50 ° C., no remarkable effect is observed on the improvement of the mechanical strength of the laminated quartz glass member, and no effective stress applying layer is formed. Although the reason is not clear, the difference of the annealing point preferable from a practical point of view is 60 to 90 ° C.
It is.

In the quartz glass member according to the present invention, of the two kinds of quartz glass having different viscosities, the higher quartz glass material is practically, for example, having a viscosity at 1,280 ° C. of 10%.
Suitable are those having a viscosity of ^12.4 poises or more, and the annealing point of the viscosity is about 1,215 ° C. Such materials are typically provided by natural quartz glass, but may be modified or derived from synthetic quartz glass and modified. Further, the quartz glass having a low annealing point combined with this is preferably a high-purity quartz glass synthesized using a silicon compound that has been refined as highly as possible as a starting material. Those produced by synthetic methods are also advantageously used. Synthetic quartz glass and its modified products usually have a viscosity at 1,280 ° C. of about 10 ^11.3 poise to 10 ^12.0 poise, and a slow cooling point of 1,120 ° C.
1,160 ° C.

In the present invention, the material having the high annealing point and the material having the low annealing point are selected and combined so that the difference between the annealing points is 50 ° C. or more. The member formed by combining two types of quartz glass having different viscosities selected may be a plate-shaped member, but is preferably a cylindrical or columnar member, and the heat-fused surface thereof is located at the center of the member. When formed on a curved surface concentric with the axis, a greater effect of improving mechanical strength, especially impact resistance, can be obtained.

In the formation of such cylindrical and columnar members, the two types of quartz glass that are combined and fused together are, depending on the type of member to be formed, for example, a target object or purpose such as a furnace core tube or various jigs, The higher cooling point is applied to the outer layer or inner layer. Further, the effect of improving the impact resistance is similarly achieved in a shape such as a half cylinder or a half cylinder.

For example, in the case of a furnace core tube, it has a high-purity synthetic quartz glass tube for the inner layer formed in advance and an annealing point higher than the quartz glass tube by 50 ° C. or more, and preferably has a viscosity at 1,280 ° C. of 10 ^12.4 poise. The above quartz glass tube for the outer layer is combined, and in the boat, a high-purity synthetic quartz glass tube for the outer layer is polymerized with a similar heat-resistant quartz glass rod for insertion into the inside having a slow cooling point higher by 50 ° C or more. The composite member is effectively manufactured by holding each polymer in a vertical shape and extending the fusion zone downward while moving the heating zone for fusion upward from the bottom.

The movement of the external heating zone relative to the polymerization member in the upward direction is only required to obtain an appropriate molten state in which the outer tube is softened and fused, and the material conditions, size, and thickness of the outer tube are required. It is selected depending on other conditions, the capacity of the heating furnace, and the like. The upward movement of the heating zone may raise the heating furnace or lower the polymerization tube. In the present invention, in parallel with the relative upward movement of this heating zone,
It is important to stretch the melted portion downward, and the formation of bubbles on the fusion surface can be effectively suppressed by appropriate stretching. The stretching speed may be negligible depending on the polymerization gap, but is usually 1.5 times or less the moving speed of the heating zone. In order to prevent air bubbles from remaining on the fusion surface, it is advantageous to make the inner layer tube or the rod-like body lower in feeding speed slightly than that of the outer layer tube.

In the method of the present invention, the gap between the quartz glass members to be polymerized is preferably smaller, and during the integration operation,
By setting the gap in a reduced pressure state or by applying a vibration having a frequency of 50 Hz or more to the outer layer tube and / or the inner layer glass body, bubbles on the fusion bonding surface can be effectively eliminated.

Next, the present invention will be described more specifically with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view for explaining one embodiment of the method of the present invention, and FIGS. 2 (a) and (b) of FIG. 2 show a composite quartz glass tube and a composite quartz according to the present invention, respectively. FIG. 2 is a schematic cross-sectional view of a glass rod.

As shown in FIG. 1, a heat-resistant quartz glass rod B whose annealing point is higher by 50 ° C. or more than that is inserted into a high-purity quartz glass tube A and polymerized. The upper ends of the tube A and the glass rod B are gripped and fixed to separate axially movable chucks 1 and 2 which can move up and down, respectively. Next, the lower end of each of the above-mentioned fixed polymer glass is heated in an induction heating furnace 3 to be melted and integrated in a sealed manner.
Is fusion bonded at one end. The drawer rod 4 is attached to a roller jig 5 that can be pulled downward at a desired take-up speed at a lower portion thereof. Further, a decompression chamber clamp jig 6 is attached to the upper end portions of the inner glass rod B and the outer tube A of the composite rod-like body so as to entirely cover the periphery of the upper end opening of the tube A so as to cover the gap between the two members. The inside thereof is maintained at a predetermined reduced pressure by a vacuum device (not shown) during the fusion-integration operation.

Next, the composite rod-shaped body fixed to the movable chucks 1 and 2 and held vertically is moved slowly downward, for example, by induction heating at a temperature of 1,800 ° C. to 2,000 ° C. or more. While passing through the heating area in the furnace 3 and sequentially melting and integrating from the lower part to the upper part, the lower drawer rod 4 is simultaneously taken up by the roller jig 5.
Usually, it is drawn downward at a take-up speed slightly higher than the feeding speed of the movable chucks 1 and 2, and is stretched to form a desired composite quartz glass rod 8 without bubbles.

During the operation, for example, the decompression chamber clamp jig 6
The gap between the two members is maintained at a reduced pressure by utilizing the method described above, or the vibrating jig 7 is applied to the quartz glass rod A and / or the tube B at a frequency of 50 Hz or more to further form bubbles on the glass fusion surface. Can be effectively eliminated.

FIG. 2 is a schematic cross-sectional view of a quartz glass member according to the present invention. FIG. 2 (a) is a cross-sectional view of a composite glass rod obtained by the method of FIG. 1, and FIG. 2 (b) is a furnace core. It is sectional drawing of a compound pipe for pipes. In the figure, A is a relatively low-cooled high-purity quartz glass tube layer, and B is a quartz glass rod whose annealing point is higher by 50 ° C. or more. C also has an annealing point of 50
It is a quartz glass tube layer which is higher than ℃.

[Operation] The composite quartz glass member for semiconductor heat treatment according to the present invention is:
Because it can be easily manufactured and has improved high impact strength, it is much easier to handle and more practical than conventional ones.

〔Example〕

Next, the features of the present invention will be described in more detail with reference to specific examples. In addition, the impact resistance in the following examples was evaluated by the measured value by the following destructive test.

Breakage test: A cylindrical glass tube member with a diameter of 110.0 mm, a wall thickness of 3.0 mm and a length of 200.0 mm was placed on a 20 mm thick earthquake-proof rubber and placed. From above vertically, the weight was 66.9 g and the diameter was 25.4. The minimum fall distance at which the glass tube breaks is measured by letting a hard ball of mm fall naturally. Therefore, in this failure test method, a relative comparison of the impact strength of each glass tube is compared with its breaking distance.

Example 1 and Comparative Example 1 An inner layer (1.2 mm thick) of a quartz glass tube having an annealing point of 1120 ° C. and a quartz glass tube having an annealing point of 1190 ° C.
The latter was heated and melted as an outer layer (1.8 mm thick), and was integrally formed with a diameter of 110.0 mm, a wall thickness of 3.0 mm, and a length of 200.0 mm.
The breakage distance of the cylindrical glass tube having a diameter of 623 mm was measured by the above-described fracture test method and was 623 mm.

For comparison, the breakage distance measured for a quartz glass tube having a prescribed shape having an annealing point of 1120 ° C. was 485 mm.

From the above, it can be seen that the specific laminated composite quartz glass member according to the present invention has improved high impact strength.

Examples 2 to 3 and Comparative Examples 2 to 3 Using a combination of various types of quartz glass having the annealing point shown in Table 1, a laminated quartz glass tube having the same thickness ratio as in Example 1 and being melted and integrated was prepared. Then, each hard ball falling distance was measured. The results are summarized in Table 1.

 For reference, those of Example 1 are also shown.

Table 1 Inner layer gradual cooling point Outer layer gradual cooling point The difference Fall distance Example 2 1160 ℃ 1245 ℃ 85 ℃ 658 mm 〃 3 1190 〃 1245 〃 55 605 〃 Comparative example 2 1145 〃 1160 〃 15 508 〃 ３ 3 1145 表1190〃 45〃 524〃 Example 1 1120〃 1190〃 70〃 623〃 As is clear from Table 1, if the difference between the annealing points of the fused and fused inner and outer layers of quartz glass is less than 50 ° C, it drops. When the distance is small and exceeds 50 ° C, the impact strength is significantly improved,
For example, it is understood that the impact strength can be improved by 100 mm or more.

Example 4 A porous quartz glass preform synthesized by a sol-gel method was formed into a tube, and sintered and heated to produce a high-purity synthetic quartz glass tube having an outer diameter of 100 mm, a wall thickness of 5 mm, and a length of 2,000 mm.

In addition, the natural crystal ingot is melted in an induction heating furnace, and extruded into a rod shape using a molybdenum molding jig by an electric melting method.
A natural quartz glass rod with an outer diameter of 85 mm, a wall thickness of 18 mm and a length of 1,500 mm was manufactured. The annealing point of each tube and rod is 1,120 ° C for synthetic quartz glass tube and 1,245 ° C for natural quartz glass rod.
g.

The lower end of the polymer in which the rod is inserted into the tube is aligned, and the upper part thereof is fixed to a vertically movable chuck, and an integrated composite rod is manufactured according to the method shown in FIG. did.

Integrated operating conditions: Heating zone temperature: 2,000 ° C Vibration jig frequency: 60 Hz Lowering speed of fixed pipe chuck: 0.3 cm / min Lowering speed of fixed rod chuck: 18.0 cm / min Lowering speed of roller jig: 18.5 cm / min In this way, an accurate diameter with respect to the central axis
An 11 mm composite quartz glass rod was obtained. When the cross section was observed with a polarizing microscope, an extremely uniform outer layer of about 2.3 mm was confirmed.

When the same integration was performed for different gaps, if the gap was within about 20% of the diameter of the inner layer rod, there was no problem such as inconvenient phenomenon of uneven wall thickness, etc. Was easily formed.

Example 5 Natural quartz powder was melt-vitrified by an oxygen-hydrogen flame, and an outer layer tube having an outer diameter of 200 mm, a wall thickness of 15 mm, and a length of 2,000 mm was prepared by the Bernoulli method. Its annealing point was about 1200 ° C. Separately, the porous glass base material manufactured by the soot method is heated and dehydrated for a long time in an anhydrous nitrogen gas atmosphere, and then sintered and vitrified to an outer diameter of 160 mm and a thickness of 160 mm.
A high-purity quartz glass tube for the inner layer of 8 mm and length of 2,000 mm was prepared. The annealing point of the tube was 1,145 ° C.

Both glass tubes were polymerized and operated in substantially the same manner as in Example 4 to produce a composite tube.

In the integration operation, while the inside of the reduced-pressure chamber clamp jig was maintained at a reduced pressure of 0.5 kg / cm ² or less, the melt-integration was performed while slightly stretching the polymerized tubular body.

As a result, a synthetic quartz glass rod having a high-precision laminated structure with no bubbles at the fusion interface between the outer tube and the inner tube was obtained.

In the above operation, without performing decompression by the decompression chamber clamp jig, when performing stretching integration without giving a vibration of 50 Hz or more, very slight but fine ripple-like bubbles were observed, No practical disadvantage was noted.

〔The invention's effect〕

Since the quartz glass member of the present invention has high impact resistance and heat resistance, it can be suitably used particularly as a member for a furnace tube or a jig for heat treatment of a semiconductor wafer, and may be damaged by a small impact or the like. Is small, the handling operability is excellent, and the service life is much longer than that of the conventional one, so that its industrial value is extremely high.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view for explaining one embodiment of the method of the present invention, and FIG. 2 is a schematic sectional view of a quartz glass tube and a quartz glass rod according to the method of the present invention. Symbols in the figure: A: High-purity quartz glass tube B: Heat-resistant quartz glass rod C: Heat-resistant quartz glass tube 1,2: Axial movable chuck 3: Induction heating furnace 4: Drawer rod 5 Roller jig 6 Decompression chamber clamp jig 7 Vibration jig 8 Composite quartz glass rod

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Koida 88 Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Prefecture Inside the Quartz Research Laboratory, Shin-Etsu Quartz Co., Ltd. (72) Inventor Hiroshi Kimura 2-13 Kitafu, Takefu-shi, Fukui Prefecture ―60 Shin-Etsu Quartz Inside the Takefu Plant (56) References: Shokai Sho 62-14722 (JP, U) Shokai Sho 56-99846 (JP, U) JP-B Showa 47-823 (JP, B1) Sakaino, Takahashi "Glass Handbook" (1975-9-30) 637

Claims (5)

(57) [Claims] A quartz glass material having a multilayer structure obtained by heating and fusing two kinds of quartz glass having different viscosities in a laminated manner, wherein the two kinds of quartz glass have a difference of 50 ° C. or more as an annealing point. A quartz glass member for semiconductor heat treatment having improved impact resistance, wherein quartz glass is melt-integrated into a composite layer. 2. A quartz glass member according to claim 1, which is a composite tube comprising an inner synthetic quartz glass layer and an outer quartz glass layer having an annealing point higher by at least 50 ° C. than the synthetic quartz glass of the inner layer. . 3. The quartz glass according to claim 1, wherein said quartz glass is a composite rod comprising an outer synthetic quartz glass layer and a quartz glass columnar layer having an annealing point higher by at least 50 ° C. than said synthetic quartz glass of said outer layer. Element. 4. A high-purity synthetic quartz glass tube is inserted inside a quartz glass tube having an annealing point higher than that of the quartz glass tube by 50 ° C. or more, and both polymerization tubes are held in a vertical state. A method for producing a quartz glass member for heat treatment of a composite tube semiconductor having improved impact resistance, characterized in that a molten portion is extended downward while moving a heating region upward from the above. 5. A quartz glass rod having an annealing point higher than that of the synthetic quartz glass tube by 50 ° C. or more is inserted inside the high-purity synthetic quartz glass tube, and the rod is held vertically, and from the lower part thereof. A method for producing a quartz glass member for heat treatment of a composite rod-like semiconductor having improved impact resistance, characterized in that a molten portion is extended downward while moving a heating region upward.