JP5317462B2 - Soaking fast elevator - Google Patents

Description

  The present invention relates to a soaking fast elevating furnace that heats a vertically long single heated object or a plurality of vertically stacked complex heated objects from the periphery thereof. For example, semiconductor wafers are arranged at intervals in the vertical direction. The present invention relates to a soaking high-speed elevator for the purpose of uniformly heating these semiconductor wafers from the surroundings and testing the temperature characteristics of nuclear fuel.

  The key technology in the semiconductor manufacturing process is high-precision thermal control. As miniaturization and speeding-up of large-scale integrated circuits (VLSIs) are increasingly required, and cost reductions are required, the thin films formed by the VLSI manufacturing process will be thinner and higher quality will be required. It has become. In recent years, the heat treatment temperature of the Si wafer has also exceeded 1100 ° C., and the SiC wafer has to be heated uniformly and rapidly to about 1800 ° C.

In the early stage of the development of process technology, soaking fast elevators that process a large number of semiconductor wafers at a time were developed from a horizontal type in which a large number of semiconductor wafers are arranged vertically on a boat. However, in order to increase the diameter of the semiconductor wafer and to minimize the floor area occupied in the clean room, a vertical diffusion device has been frequently used from the middle. This vertical diffusing device stacks semiconductor wafers on a rack-like boat at intervals of 5 to 6 mm, heats the wafers from the periphery, introduces a reaction gas into them, and processes them by means of thermal CVD or only heating The thermal diffusion treatment is performed in
As another application, an elongated soaking fast elevating furnace that can be rapidly heated to about 1700 ° C. is used as a simulated fuel rod for temperature characteristic test of nuclear fuel obtained by baking and solidifying uranium oxide pellets.

As this soaking fast elevator, for example, one described in Patent Document 1 below is known. As shown in FIG. 7, a housing in which alumina-silica fiber is baked and hardened with a binder or a ceramic adhesive to form a cylindrical heat insulating molded body, or graphite fiber is baked and hardened with pitch or the like to form a cylindrical heat insulating molded body. 23, an inner tube 30 made of quartz, alumina, sialon (Si ₃ N ₄ -based ceramics made by dissolving silicon nitride alumina, SiO ₂ or the like) or a silicon carbide sintered body is disposed. The reactive gas is introduced into the inner tube 30, and a thin film is formed on the surface of the object to be heated 28 such as a semiconductor wafer arranged vertically with a space in the boat 29. The boat 29 is moved up and down by the drive mechanism 25. In order to obtain a predetermined temperature, heaters 22 and 22 ′ are provided so as to surround the inner tube 30. Further, a cooling gas passage 24 for allowing the cooling gas to pass therethrough is provided outside or inside the housing 23. FIG. 7 shows an example in which the cooling gas passage 24 is provided in the wall of the housing 23.

In such a soaking high-speed elevator, the object to be heated is heated to 600 to 1700 ° C., and a heater having high heat resistance is used. For example, as shown in FIG. 8, a heater 22 made of rod-shaped conductive silicon carbide (SiC), molybdenum silicide (MoSi ₂ ), or the like folded back in a U shape is disposed inside the housing 23 in an annular shape. FIG. 9 shows an example of a plate-like heater 22 ′. For example, Patent Document 1 described below uses a graphite heater.
On the other hand, when cooling the soaking fast elevator, the cooling gas is passed through the cooling gas passage 24 to cool the housing 23.

Another example of the housing 23 and the heater will be specifically described with reference to FIGS.
For those that change the temperature and atmosphere, but the atmosphere in the sealed metal container is an inert gas atmosphere, for example, as shown in FIG. A housing 23 is used in which a body is lined, a groove 25 is dug inside the heat insulating molded body, and a coiled heater 22 ′ made of a refractory metal such as tungsten is embedded in the groove 25.

When used in an unsealed atmospheric pressure, as shown in FIG. 11, a cylindrical heat-insulated molded body in which alumina-silica fibers are baked and hardened with a binder or a ceramic adhesive is used as an unsealed metal cover. A housing 23 in which a die 25 is formed in the heat insulating molded body, and a coiled nichrome wire, a Kanthal wire or a rod-like conductive SiC heating element 22 ″ is embedded in the groove 25 ′. used.
Conductive SiC is obtained by adding conductivity to SiC. Insulating SiC refers to other materials that are sintered with an oxide (Y ₂ O ₃ or the like) sintering aid.

  However, in the structure of the soaking high-speed elevator, the heat transfer from the heaters 22 and 22 ′ and the cooling gas passage 24 toward the center of the furnace is poor, and between the inner periphery and the outer periphery of the object 28 to be heated. Differences in temperature, so-called temperature unevenness, are likely to occur. Furthermore, since the cooling gas passage 24 is provided outside or inside the heat-insulating housing 23, heat transfer from the cooling gas to the heating chamber is poor, and it takes a long time to cool from the end of heating to room temperature. . Further, dust generated at a high temperature from the inner surface of the housing 23 is likely to diffuse into the heating furnace.

JP 2001-6857 A JP 2001-7035 A Japanese Patent Laid-Open No. 11-102915 JP-A-5-215473 JP-A-5-248770

  In view of such problems in the conventional soaking high-speed elevator, the present invention is excellent in heating and cooling efficiency of a heated object, fast heating and cooling, small temperature unevenness of the heated object, An object of the present invention is to provide a soaking fast elevating furnace in which dust generated from the inner surface does not easily reach the object to be heated.

In the present invention, in order to achieve the above object, the heater 2 is disposed between the housing 3 and the inner tube 5, and the heat reflecting plate 4 is provided behind the heater 2, that is, on the inner surface side of the housing 3. The gap between the heat reflecting plate 4 and the inner tube 5 is formed as a cooling gas passage 6 through which cooling gas passes , and the heat reflecting plate 4 is formed by a segment 13 that is stretched inside the housing 3. The heater 2 was held alongside .

That is, soaking-rapid reactor according to the present invention, the provided inner tube 5 of the tubular inside of the housing 3, thereby placing the heater 2 between the inner tube 5 and the housing 3 and place the heater 2 A gap between the inner tube 5 and the housing 3 is used as a cooling gas passage 6 through which a cooling gas passes. A cylindrical heat reflecting plate 4 is provided inside the housing 3, and the heater 2 generates heat in the housing 3. In what heats the housed article 8 to be heated, a segment 13 is stretched inside the housing 3 to form the heat reflecting plate 4, and the heater 2 is held along the inside of the segment 13 . The heat reflecting plate 4 has a high emissivity ε, such as silicon carbide, and has a heat resistance of ε = 0.6 or more, or a heat reflecting plate that is heat-reflected by coating with gold plating or tin oxide on the outside of the quartz glass. Good.

  However, in the heat reflection method using gold plating, tin oxide, or the like, even if the inner tube 5 is present due to the influence of heaters or interference of light, the temperature distribution is applied to the article 8 to be heated and the gap between the heater 2 and the inner tube 5 is increased. Care must be taken during temperature analysis.

  In such a soaking high-speed elevator according to the present invention, the heat released from the heater 2 is diffused by the inner tube 5, so that it is evenly distributed inside the inner tube 5. As described above, the heat is evenly distributed inside the inner tube 5, so that the temperature unevenness of the article to be heated 8 is less likely to occur. Furthermore, since the heat radiated from the heater 2 toward the housing 3 is reflected toward the inside of the housing 3 by the heat reflecting plate 4, the amount of heat reaching the object to be heated 8 can be increased.

  In general, the inner tube 5 limits the atmosphere of the article 8 to be heated, protects contamination from the outside, and is for heat equalization. However, in the high temperature region, if impurities (for example, alkali metal oxide) in the heat insulating molded body in the housing 3 adhere to the inner tube 5 as dust, it diffuses in the inner tube 5 and causes the object 8 to be heated. To contaminate.

  On the other hand, in the soaking high-speed elevator according to the present invention, the heat reflecting plate 4 is provided inside the housing 3 in addition to the inner tube 5 as shown in FIGS. Therefore, there is no dust from the inner peripheral surface of the housing 3. For this reason, the to-be-heated material 8 arrange | positioned inside the inner tube 5 is not polluted with dust.

As described above, the soaking high-speed elevator according to the present invention has excellent thermal responsiveness at the time of heating and cooling, and in addition to being able to heat and cool the heated object as soon as possible, uneven temperature of the heated object also occurs. Hateful. Furthermore, since dust generated from the housing 3 and impurities in the dust do not reach the inside of the inner tube 5, it is possible to avoid contamination of the heated object with dust.

In the present invention, in order to achieve the above object, in addition to disposing the heater 2 between the housing 3 and the inner tube 5, the gap between the housing 3 and the inner tube 5 serves as a cooling gas passage 6, Further, the heat reflecting plate 4 is provided on the inner surface side of the housing 3, and the heat reflecting plate 4 is formed by a segment 13 extending inside the housing 3, and the heater 2 is held along the segment 13 .
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

The soaking fast elevator is basically structured as shown in FIG. Further, FIG. 1 and FIG. 2 show the difference between the basic structure of the soaking fast elevator according to the present invention and the conventional soaking fast elevator shown in FIG .
1 and 2 both show a portion of the housing 3 in cross section. The housing 3 is made of a heat-resistant material such as alumina-silica fiber baked and hardened with a binder or ceramic adhesive to form a cylindrical heat-insulated molded body, or graphite fiber baked and hardened with pitch or the like to form a cylindrical heat-insulated molded body. It is a cylindrical one made of material. On this inner surface, the radiation coefficient ε of insulating silicon carbide (SiC) or the like is large, and the heat reflecting plate 4 itself absorbs heat once. Although the heat resistance is high and the heat conductivity is high, or the gap between the inner tube 5 and the heater 2 must be large, the outer surface of the quartz glass is coated with gold or tin oxide to reflect heat. A heat reflecting plate 4 made of what is to be stretched is stretched. Furthermore, a heater 2 made of bar-shaped SiC, molybdenum silicide (MoSi ₂ ), or the like folded back in a U shape is arranged inside the ring.

  An inner tube 5 made of quartz, alumina, sialon, SiC or the like is provided inside the heater 2. Inside the inner tube 5 is a heating chamber 7 into which a semiconductor wafer or other object to be heated 8 is introduced. In this structure, the heater 2 is disposed in the gap between the heat reflecting plate 4 and the inner tube 5 on the inner surface of the housing 3.

A gap between the heat reflecting plate 4 and the inner tube 5 on the inner surface of the housing 3 in which the heater 2 is disposed serves as a cooling gas passage 6 through which cooling gas passes. The cooling gas may flow up and down through the cooling gas passage 6 or may flow in the circumferential direction. When the housing 3 is an airtight container, an inert gas is used as the cooling gas, such as argon (Ar) or nitrogen (N ₂ ). When the housing 3 is an unsealed container, the cooling gas may be the atmosphere.

  In such a soaking high-speed elevator according to the present invention, the heat released from the heater 2 is diffused by the inner tube 5 and evenly distributed inside the inner tube 5. In addition, since the heat reflecting plate 4 is provided behind the heater 2, the heat radiated from the heater 2 toward the housing 3 is reflected toward the inside of the housing 3 by the heat reflecting plate 4, and effective use of the heat is achieved. I can plan.

  Furthermore, since the inner peripheral surface of the housing 3 is covered with the heat reflecting plate 4, dust is not generated from the inside of the housing 3, and impurities due to dust do not permeate the inner tube 5 due to thermal diffusion at high temperatures. 7 to be heated is not contaminated by dust generated from the inside of the housing 3.

  FIG. 3 is a graph showing a temperature drop with time during cooling in the soaking fast elevator described in FIGS. 1 and 2 and the soaking fast elevator described in FIG. Both are measured under the same conditions. The temperature is measured in the heating chamber 7, the outside of the heating chamber 7 and the heater 2. As is apparent from this graph, the soaking high speed elevator described with reference to FIGS. 1 and 2 has a faster temperature drop during cooling and better thermal response than the soaking fast elevator described with reference to FIG. I understand.

  In the above-described example, an example of a soaking fast elevator using the rod-shaped heater 2 folded back into a U-shape has been described. However, instead of the rod-shaped heater 2, for example, as shown in FIG. Needless to say, the present invention can also be applied to a soaking high-speed elevator using a plate-shaped heater.

FIG. 4 and FIG. 5 are diagrams showing an example of a more detailed structure of the housing 3, the heat reflecting plate 4 inside the heater 3, and the heater 2 in the soaking fast elevator according to the present invention .
In FIG. 4, a partially cylindrical segment 13, that is, a segment 13 having an arcuate end surface is stretched inside the housing 3 inside the housing 3, and this is fixed inside the housing 3 with a fixture 10 such as a bolt and a nut. The heat reflecting plate 4 is formed so as to cover the inner surface of the housing 3. The heater 2 is introduced from the outside of the housing 3 to the inside thereof, and is placed along the inside of the segment 13 forming the heat reflecting plate 4. The heater 2 is folded back into a U shape inside the segment 13, and the folded portion is held by an L-shaped pin 9 protruding from the lower end of the segment 13.

  The example of FIG. 5 is basically the same as FIG. 4, but here, a segment 13 having a flat shape, that is, a straight end 13 is used as the segment 13, and this segment 13 is stretched inside the housing 3. This is fixed to the inside of the housing 3 with a fixture 10 such as a bolt and a nut, and the heat reflecting plate 4 is formed so as to cover the inner surface of the housing 3. The heater 2 is also introduced from the outside of the housing 3 to the inside thereof, and is placed along the inside of the segment 13 forming the heat reflecting plate 4. The heater 2 is folded back into a U shape inside the segment 13, and the folded portion is held by an L-shaped pin 9 protruding from the lower end of the segment 13.

  FIG. 6 is a diagram illustrating an example of a fixing member 11 that fixes adjacent segments 13 and 13 and heaters 2 and 2 along the segments 13 and 13 in the examples of FIGS. 4 and 5. The fixing member 11 is made of a high melting point metal such as ceramics or tungsten, and is fixed between adjacent segments 13 and 13 by a fixing tool 12 such as a bolt. The adjacent segments 13 and 13 and the heater 2 along the segments 13 and 13 are fixed. 2 are fixed together.

  The soaking high-speed elevator according to the present invention is a heat treatment for film formation by a CVD method in a semiconductor wafer manufacturing process, a heat treatment furnace for annealing a metal material and a metal sputtering film, and a heating test of a uranium pellet of nuclear fuel. Can be used as a heat treatment furnace. In these fields, the time required for heating and cooling can be shortened, so that the production efficiency can be improved.

1 is a half sectional perspective view showing a part of a housing section of an embodiment of a soaking fast elevator according to the present invention. It is the cross-sectional top view which showed the part of the housing part about one Example of the soaking high speed elevator according to this invention, and showed the part. It is a graph which shows the fall of the temperature accompanying the time at the time of cooling in the soaking high speed elevator according to the said Example and the soaking fast elevator of a prior art example. 1 is a half sectional perspective view showing a part of an inner surface of a housing of an embodiment of a soaking fast elevator according to the present invention. It is the half cross-sectional perspective view which showed a part of inner surface of the housing about other Examples of the soaking high speed elevator according to this invention. FIG. 6 is a half cross-sectional perspective view illustrating a fixing means for members on the inner surface of the housing in the examples of FIGS. 4 and 5 for another embodiment of the soaking fast elevator according to the present invention. It is a whole concept vertical side view showing the conventional example of a soaking fast elevator. It is the semi-section perspective view which showed the section of the housing and showed the part about the conventional example of a soaking fast elevator. It is a perspective view which shows the other example of the heater used about the prior art example of a soaking high speed elevator. It is a perspective view which shows the other example of the heater used about the prior art example of a soaking high speed elevator. It is a perspective view which shows the other example of the heater used about the prior art example of a soaking high speed elevator.

Explanation of symbols

2 Heater 2
3 Housing 4 Heat reflector 5 Inner tube 6 Cooling gas passage 8 Object to be heated

Claims (2)

A cylindrical inner tube (5) is provided inside the housing (3), a heater (2) is disposed between the inner tube (5) and the housing (3), and the heater (2) is disposed. The gap between the inner tube (5) and the housing (3) is used as a cooling gas passage (6) through which cooling gas passes , and a cylindrical heat reflector (4) is provided inside the housing (3) , In a soaking and high-speed elevator that heats an object to be heated (8) housed in the housing (3) by the heat generated by the heater (2), a segment (13) is stretched on the inner side of the housing (3) and a heat reflecting plate ( 4), and the heater (2) is held along the inside of the segment (13) . The soaking high-speed elevator according to claim 1, wherein the heat reflecting plate (4) is made of insulating silicon carbide.

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