JP2014093410A - Vertical type thermal treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent separation and fall of an upper lid thermal insulation material in a case where a body thermal insulation material surrounding the side peripheral surface of a reaction pipe over the circumferential direction thereof and the upper lid thermal insulation material closing the upper opening of the body insulation material are provided as a thermal insulation material outside the vertical reaction pipe used for thermally processing a substrate.SOLUTION: In the contact part where the underside peripheral edge part of an upper lid thermal insulation material 22 is in contact with a body thermal insulation material 21, a protective layer 23 higher in density (hardness) than the body thermal insulation material 21 is arranged. This protective layer 23 is joined (sintered) integrally with the upper lid thermal insulation material 22 so that when the upper lid thermal insulation material 22 thermally expands or contracts as the temperature of a reaction pipe 2 increases or decreases, the protective layer 23 deforms following the thermal expansion or contraction. Additionally, the protective layer 23 is formed from ceramics fiber in order to thermally insulate the reaction pipe 2, and the thickness of the protective layer 23 is set to 1 mm to 2 mm.

Description

  The present invention relates to a vertical heat treatment apparatus for performing heat treatment in a vertical reaction tube on a plurality of substrates stacked in a shelf on a substrate holder.

  For example, a vertical heat treatment apparatus is known as one of apparatuses for performing heat treatment such as thermal oxidation treatment or CVD (Chemical Vapor Deposition) treatment on a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”). This apparatus includes a wafer boat which is a substrate holder for stacking a plurality of substrates in a shelf shape, and a vertical reaction tube for airtightly storing the wafer boat. And the heat insulating material for suppressing the heat dissipation of the said reaction tube is arrange | positioned on the outer side of the reaction tube, The heater for heating the inside of a reaction tube is affixed on the internal peripheral surface of this heat insulating material. . This heat insulating material includes a substantially cylindrical main body heat insulating material configured to surround the side peripheral surface of the reaction tube in the circumferential direction, and an upper lid heat insulating material that closes the upper side opening of the main body heat insulating material. For example, it is made of ceramic fibers (cross) such as alumina (Al2O3) or silica (SiO2). Accordingly, voids are included in the heat insulating material.

  In such an apparatus, while continuously heat-treating a plurality of processing batches (lots), the temperature inside the reaction tube is repeatedly raised and lowered for each processing batch. Specifically, for example, a wafer boat loaded with a plurality of wafers is stored in an airtight manner from the lower side in a reaction tube set at a relatively low temperature of about 300 ° C., for example, and then the inside of the reaction tube is, for example, 1000 ° C. The temperature is raised to about the heat treatment temperature. Subsequently, after heat-treating the substrate at this heat treatment temperature, the temperature inside the reaction tube is lowered to the aforementioned carry-in / out temperature, and the wafer boat is carried out of the reaction tube.

  When the heat treatment is continuously performed many times in this way, a part or the whole of the above-described upper lid heat insulating material may drop and fall. In Patent Documents 1 and 2, as a technique for preventing the occurrence of cracks and falling in the top cover heat insulating material (ceiling heat insulating material or upper heat insulating material), a groove is formed on the lower surface of the top cover heat insulating material, or in the positioning portion of the top cover heat insulating material. A technique for performing a process of relaxing stress is described. Patent Document 3 describes a method of concentrically dividing a top plate on the upper side of the upper lid heat insulating material (top heat insulating material) and a technique for attaching a heat-resistant alumina cloth to the lower surface of the upper lid heat insulating material. Patent Document 4 describes a vertical heat treatment apparatus. Patent Document 5 describes a technique in which an inorganic coating layer 31 including an inorganic fiber cloth 33 is disposed on the inner surface of an inorganic molded body 32. However, in these patent documents 1 to 5, the density (hardness) of the main body heat insulating material and the upper lid heat insulating material is not studied.

JP 2009-194297 A JP 2007-73865 A JP 2003-22979 A (paragraph 0025) JP 2004-31846 A JP-A-5-215473

  The present invention has been made in view of such circumstances, and an object of the present invention is to extend the side peripheral surface of the reaction tube in the circumferential direction outside the vertical reaction tube for performing heat treatment on the substrate. To provide a vertical heat treatment apparatus that can suppress the falling off of the upper cover heat insulating material when providing the main body heat insulating material surrounded by a cylindrical shape and the upper cover heat insulating material that closes the upper opening of the main body heat insulating material as heat insulating materials. is there.

The vertical heat treatment apparatus of the present invention is
In a vertical heat treatment apparatus for performing heat treatment in a vertical reaction tube on a plurality of substrates stacked in a shelf on a substrate holder,
A heating unit for heating the substrate in the reaction tube;
A main body heat insulating material, which is disposed outside the region heated by the heating unit so as to surround the side peripheral surface of the reaction tube in a cylindrical shape along the circumferential direction, and is composed of ceramics including voids;
An upper lid heat insulating material, which is arranged so as to close the upper opening of the main body heat insulating material, and is configured to have the same density as the main body heat insulating material,
In order to suppress damage to the upper lid heat insulating material while deforming following the thermal expansion / shrinkage of the upper lid heat insulating material when the upper lid heat insulating material thermally expands / shrinks, the main body heat insulating material at the lower edge of the upper lid heat insulating material A protective layer made of a refractory material that is provided at a contact portion with the material, has a higher density than the main body heat insulating material, and is a separate member from the upper lid heat insulating material,
The protective layer is bonded to the upper lid heat insulating material using an adhesive containing an inorganic component, and then integrated with the upper lid heat insulating material by heat treatment.

The above-described vertical heat treatment apparatus may take the following aspects. That is, the protective layer is configured to have a density of 1.5 to 2 times or more the density of the main body heat insulating material.
The thickness of the protective layer is set to prevent the reaction vessel from radiating heat through the region between the main body heat insulating material and the upper lid heat insulating material, and the upper cover heat insulating material slides on the main body heat insulating material. In order to suppress moving and wear, an aspect set to 1 mm or more and 2 mm or less.
The heat treatment performed in the reaction tube is a heat treatment at 1000 ° C. or higher.
An exterior body is provided outside the main body heat insulating material and the upper lid heat insulating material,
Between these main body heat insulating material and upper lid heat insulating material and the exterior body, a buffer material having a density lower than that of the main body heat insulating material and the upper cover heat insulating material, and when the main body heat insulating material and the upper cover heat insulating material are thermally expanded. A mode in which at least one of the gap region serving as the elongation allowance is interposed.

  The present invention provides a cylindrical main body heat insulating material along the side peripheral surface of a reaction tube that performs heat treatment on a substrate, and the main body heat insulating material is disposed in an upper opening of the main body heat insulating material. A protective layer made of a heat insulating material having a density higher than that of the heat insulating material is arranged at the contact portion with the main body heat insulating material at the lower surface side peripheral portion of the upper cover heat insulating material. The protective layer is configured to be deformed following the thermal expansion and contraction of the upper lid heat insulating material when the upper lid heat insulating material is thermally expanded and contracted. Therefore, even if the temperature of the reaction tube is raised or lowered, damage to the upper lid heat insulating material due to sliding with the main body heat insulating material can be suppressed.

It is a longitudinal cross-sectional view which shows roughly an example of the vertical heat processing apparatus of this invention. It is a perspective view which shows the upper cover heat insulating material in the heat insulating material of the said vertical heat processing apparatus. It is a longitudinal cross-sectional view which shows the said heat insulating material. It is a disassembled perspective view which shows the said heat insulating material. It is a longitudinal cross-sectional view which shows typically the damage which arises in the said heat insulating material when a protective layer is not formed in the said heat insulating material. It is a longitudinal cross-sectional view which shows typically the damage which arises in the said heat insulating material when a protective layer is not formed in the said heat insulating material. It is a longitudinal cross-sectional view which shows typically the damage which arises in the said heat insulating material when a protective layer is not formed in the said heat insulating material. It is a longitudinal cross-sectional view which shows typically a mode that the surface of a heat insulating material is hardened using the adhesive agent which consists of a liquid. It is a longitudinal cross-sectional view which shows typically the said surface when the surface of a heat insulating material is hardened using the said adhesive agent. It is a longitudinal cross-sectional view which shows a mode that it replaced with the protective layer at the said heat insulating material, and provided the quartz plate. It is a longitudinal cross-sectional view which shows typically the thermal expansion / contraction of a heat insulating material when the said quartz plate is provided. It is a longitudinal cross-sectional view which shows typically the example which replaced with the protective layer instead of the protective layer at the said heat insulating material. It is a longitudinal cross-sectional view which shows typically an example of the method of forming the protective layer of this invention. It is a longitudinal cross-sectional view which shows the heat insulating material in which the said protective layer was formed. It is a longitudinal cross-sectional view which shows a mode when the heat insulating material of this invention heat-shrinks. It is a longitudinal cross-sectional view which shows typically a mode when the heat insulating material of this invention thermally expands. It is a longitudinal cross-sectional view which shows typically the damage which arises in the said heat insulating material when the heat insulating material of this invention is used. It is a perspective view which shows the heat insulating material in the other example of this invention. It is a longitudinal cross-sectional view which shows the heat insulating material in the said other example.

  An example of a vertical heat treatment apparatus according to an embodiment of the present invention will be described with reference to FIGS. First, the outline of this apparatus will be briefly described. This apparatus includes a wafer boat 1 on which a plurality of, for example, 150 wafers W are stacked in a shelf shape, and an airtight storage for the wafer boat 1 to perform heat treatment. A vertical reaction tube 2 is provided. And when this apparatus heat-processes with respect to the wafer W, even if it raises / lowers the temperature in the reaction tube 2 over many times, the ceiling surface (upper cover) of the heat insulating material 3 for thermally insulating the said reaction tube 2 The heat insulating material 22) is configured to be difficult to break (drop off). Next, a specific configuration of this apparatus will be described.

  On the lower side of the above-described reaction tube 2, a cylindrical body 4 formed in a substantially cylindrical shape is disposed in order to airtightly support the peripheral edge of the lower end of the reaction tube 2 in the circumferential direction. The cylindrical body 4 is hermetically closed at its lower end opening by a disc-shaped lid body 5. A gas nozzle 6 extending in the vertical direction along the length direction of the reaction tube 2 is accommodated in the reaction tube 2 so as to be adjacent to the wafer boat 1. The lower end portion of the gas nozzle 6 passes through the side wall portion of the cylindrical body 4 in an airtight manner, and is connected to the processing gas source 6a via the valve V and the flow rate adjusting portion M. As the processing gas source 6a, for example, an inert gas such as nitrogen (N2) gas, a silicon (Si) -based gas or ozone (O3) gas is stored depending on the type of heat treatment performed on the wafer W. The sources are arranged individually. In FIG. 1, reference numeral 6 b denotes a gas discharge hole formed on the side surface of the gas nozzle 6.

  An exhaust port 7 for evacuating the inside of the reaction tube 2 is formed at a position facing the gas nozzle 6 on the side peripheral surface of the cylindrical body 4, and an exhaust tube 8 extending from the exhaust port 7 has a butterfly An evacuation mechanism 10 such as a vacuum pump is connected via a pressure adjustment unit 9 such as a valve. In FIG. 1, reference numeral 11 denotes a rotating shaft that supports the wafer boat 1 so as to be rotatable about a vertical axis, and reference numeral 12 denotes a driving unit such as a motor disposed on the lower end side of the rotating shaft 11.

  Here, a series of sequences in the heat treatment performed on the wafer W inside the reaction tube 2 will be briefly described. First, after loading a plurality of wafers W on the wafer boat 1 at a position spaced apart from the reaction tube 2 set to a carry-in / out temperature of, for example, about 300 ° C., the wafer boat 1 is raised. And stored in the reaction tube 2 in an airtight manner. Next, the inside of the reaction tube 2 is heated to a heat treatment temperature of about 1000 ° C., for example, and a processing gas is supplied into the reaction tube 2 while rotating the wafer boat 1 around the vertical axis. A heat treatment is performed on the wafer W. Subsequently, after the inside of the reaction tube 2 is lowered to the carry-in / out temperature described above, the wafer boat 1 is lowered and the wafer W is taken out. In this way, the subsequent unprocessed wafers W are sequentially subjected to heat treatment in the same manner. During such heat treatment, heat dissipation is suppressed inside the reaction tube 2 by the heat insulating material 3 provided outside the reaction tube 2, so that heat uniformity in the horizontal and vertical directions is ensured.

  That is, on the outside of the reaction tube 2 described above, the above-described heat insulating material 3 and the heater 20 serving as a heating unit for heating the inside of the reaction tube 2 to the heat treatment temperature are arranged. Specifically, the heat insulating material 3 includes a main body heat insulating material 21 formed in a substantially cylindrical shape so as to surround the side peripheral surface of the reaction tube 2 along the circumferential direction, and an upper opening of the main body heat insulating material 21. And a disc-shaped upper lid heat insulating material 22 arranged so as to be closed. The above-described heater 20 is provided along the circumferential direction on the inner peripheral surface of the main body heat insulating material 21 and is simplified in FIG. 1, but is divided into a plurality of regions in the height direction. The temperature is individually adjustable. In addition, about the main body heat insulating material 21, you may use what united the some member which made | forms circular arc shape when it sees in the plane in the circumferential direction, and was integrated in cyclic | annular form.

  As shown in FIGS. 1 and 2, a concave portion 22a is formed in the approximate center portion of the lower end surface of the upper lid heat insulating material 22 so as to be recessed upward, and the lower end surface on the side of the concave portion 22a. Is provided with a groove portion 22b for communicating the inner region of the concave portion 22a with the outside of the apparatus. Therefore, after the heat treatment on the wafer W is completed, the gas is allowed to flow into the region between the reaction tube 2 and the heat insulating material 3 via an intake passage (not shown) and discharged from the groove 22b. The tube 2 can be forcibly cooled by air. In FIG. 1, 22 c is an exhaust pipe that is inserted into the upper lid heat insulating material 22 along the groove 22 b from the outside of the apparatus, for example. In addition, drawing about these recessed part 22a, the groove part 22b, and the exhaust pipe 22c is abbreviate | omitted in FIG.

  The main body heat insulating material 21 and the upper lid heat insulating material 22 are each composed of ceramic fibers (cloth) such as alumina and silica, and therefore each have a large number of voids therein. Therefore, it can be said that when the main body heat insulating material 21 and the upper lid heat insulating material 22 slide on each other, the main body heat insulating material 21 and the upper cover heat insulating material 22 are easily broken. In addition, the main body heat insulating material 21 and the upper lid heat insulating material 22 are configured such that the densities (bulk density) are aligned with each other, that is, the strengths are aligned with each other. 45 g / cm @ 3.

  Here, “the density is uniform” means that the density of the upper lid heat insulating material 22 is substantially the same value as the density of the main body heat insulating material 21, and the heat insulating capacity of the upper cover heat insulating material 22 is expressed by the heat insulating capacity. It refers to 90% to 110% with respect to 21 heat insulation capacity. That is, when the reaction tube 2 is set to a certain temperature, and the heat insulating material 3 such as the top cover heat insulating material 22 and the main body heat insulating material 21 is disposed outside the reaction tube 2 set to this temperature, this heat insulating material 3, the temperature of the surface on the side opposite to the reaction tube 2 is 90% to 110% of the main body heat insulating material 21 in the upper lid heat insulating material 22. In this example, the heat insulating capacity of the upper lid heat insulating material 22 is the same value as the heat insulating capacity of the main body heat insulating material 21.

  1 and 3 is an exterior body (casing) made of a metal plate such as stainless steel along the outer peripheral surfaces (side surfaces and upper surface) of the main body heat insulating material 21 and the upper lid heat insulating material 22. A side surface portion 30a and a top plate 30b provided on the peripheral surface are fixed to each other by a bolt or the like (not shown). And between the exterior body 30 and the main body heat insulating material 21 and the upper lid heat insulating material 22, the main body heat insulating material 21 and the upper cover heat insulating material 22 can be more thermally expanded than the main body heat insulating material 21 and the upper cover heat insulating material 22. Auxiliary heat insulating materials 3a having a small density (hardness) are interposed as buffer materials (brackets). The auxiliary heat insulating material 3a is composed of ceramic fibers or the like, like the main body heat insulating material 21 and the upper lid heat insulating material 22. Further, between the side peripheral surface of the auxiliary heat insulating material 3a and the exterior body 30, the thermal expansion of the auxiliary heat insulating material 3a and the heat insulating material 3 so as to surround the side peripheral surface of the auxiliary heat insulating material 3a in the circumferential direction. A gap region 3b is interposed as an expansion allowance when contracting.

  Here, in the part which contacts the main body heat insulating material 21 in the peripheral part of the lower surface side of the upper lid heat insulating material 22, as shown in FIGS. 2-4, the substantially ring-shaped protective layer 23 is arrange | positioned. This protective layer 23 is a refractory (heat insulating material) made of ceramic fibers such as alumina and silica, like the main body heat insulating material 21 and the upper cover heat insulating material 22, and therefore the main body heat insulating material 21 and the upper cover heat insulating material. 22 is included.

  The protective layer 23 is densely filled with, for example, the fibers so that the density (hardness) is higher than that of the main body heat insulating material 21 and the upper lid heat insulating material 22. Specifically, the density of the protective layer 23 is, for example, 1.0 g / cm 3 to 2.0 g / cm 3, so that the density of the main body heat insulating material 21 is 1.5 times or more, preferably 2 times or more. It has become. Here, when the protective layer 23 is formed at a higher density than the main body heat insulating material 21, since the protective layer 23 is a “refractory material” made of ceramic fibers, the protective layer 23 includes pores. It is.

  Since the protective layer 23 is thus formed of a heat insulating material, the thermal expansion / shrinkage of the protective layer 23 (a protective layer 23 including an adhesive layer 24 described later) is the same as the thermal expansion / shrinkage rate of the upper lid heat insulating material 22. It is adjusted so that it will be about the same (same value). Moreover, the thickness dimension t of the protective layer 23 is set to 1 mm or more and 2 mm or less as shown in FIG. In FIG. 1, drawing of the protective layer 23 is omitted. Moreover, FIG. 2 has shown the perspective view which looked at the upper cover heat insulating material 22 from the downward side.

The protective layer 23 is configured integrally with the upper lid heat insulating material 22 so that the upper lid heat insulating material 22 is deformed following the thermal expansion and contraction when the upper lid heat insulating material 22 is thermally expanded and contracted as the reaction tube 2 is heated and lowered. Has been. The reason why the protective layer 23 is configured in this manner will be described in detail below together with a method for forming the protective layer 23.
That is, the upper lid heat insulating material 22 has a substantially disk shape as described above, and is solid when viewed on a plane (the fibers constituting the upper lid heat insulating material 22 are also arranged in the central portion). ing. On the other hand, the main body heat insulating material 21 is hollow because the wafer boat 1 is arranged in the center when viewed in a plane. Therefore, when viewed in a plane, the length dimension of thermal expansion / contraction as the temperature of the reaction tube 2 increases and decreases is different between the main body heat insulating material 21 and the upper lid heat insulating material 22. Therefore, when the reaction tube 2 moves up and down, if the protective layer 23 is not disposed, the main body heat insulating material 21 and the upper lid heat insulating material 22 slide on each other.

  The main body heat insulating material 21 and the upper cover heat insulating material 22 have the same density and are each composed of ceramic fibers and are easily damaged. Therefore, due to the difference in density between the main body heat insulating material 21 and the upper lid heat insulating material 22 caused by manufacturing variations, or due to a slight difference in surface condition at the site where the main body heat insulating material 21 and the upper cover heat insulating material 22 are in contact, etc. There is a possibility that the upper lid heat insulating material 22 is worn preferentially and falls off.

  That is, since both the upper lid heat insulating material 22 and the main body heat insulating material 21 are made of ceramic fibers, in reality, the density and the like are likely to vary even if they are manufactured so as to have the same physical properties. Specifically, if the upper lid heat insulating material 22 is slightly higher in density than the main body heat insulating material 21, if the upper cover heat insulating material 22 and the main body heat insulating material 21 slide, as shown in FIG. The inner peripheral portion on the upper surface side of the main body heat insulating material 21 is scraped by the lower edge side outer edge portion of the upper lid heat insulating material 22. In this case, the upper lid heat insulating material 22 is unlikely to drop off. In FIG. 5, the state in which the main body heat insulating material 21 is worn is exaggerated. The same applies to FIGS. 6, 7 and 17 described later.

  On the other hand, when the main body heat insulating material 21 has a higher density than the upper cover heat insulating material 22, the lower surface side outer peripheral portion of the upper cover heat insulating material 22 is stepped by the upper surface side inner peripheral portion of the main body heat insulating material 21 when sliding, as shown in FIG. In some cases, the step portion 25 is formed. In this case, when the upper lid heat insulating material 22 is thermally expanded, stress concentrates on the step portion 25, thereby generating a crack 26 with the step portion 25 as a base point, and a part or the whole of the lower surface side of the upper cover heat insulating material 22. May fall out toward the reaction tube 2. If the upper lid heat insulating material 22 falls off as described above, it is difficult to obtain the thermal uniformity in the reaction tube 2 in the subsequent heat treatment on the wafer W.

  In addition, the density of the part of the main body heat insulating material 21 is higher than that of the upper cover heat insulating material 22, while the density of the main body heat insulating material 21 and the upper cover heat insulating material 22 is lower than the other part. When they are antagonistic to each other, as shown in FIG. 7, both the upper lid heat insulating material 22 and the main body heat insulating material 21 are scraped off. Even in this case, the upper lid heat insulating material 22 may fall off with the step portion 25 or the crack 26 as a base point.

  Here, as a technique for forming, for example, a hard film on the surface of the heat insulating material 3 (upper cover heat insulating material 22), a method of coating the surface of the heat insulating material 3 with an inorganic material can be cited. Specifically, as shown in FIG. 8, an adhesive 41 containing an inorganic binder as a component is applied to the surface of the heat insulating material 3, and then heat treatment (sintering) is performed as shown in FIG. In this method, since the powder made of ceramics contained in the adhesive 41 adheres to the ceramic fibers constituting the heat insulating material 3 and then sinters, or fibers adjacent to each other through the powder sinter, On the surface of the heat insulating material 3, a high-density layer 42 having a density (hardness) higher than that inside is formed.

  However, since the heat insulating material 3 is composed of ceramic fibers as already described in detail, the adhesive 41 penetrates into the heat insulating material 3 when a liquid adhesive 41 is used. In other words, when the adhesive 41 made of liquid is used, the heat insulating material 3 is impregnated so to speak, and as shown in an enlarged view on the lower side of FIG. The high-density layer 42 may be formed at the position. When the high-density layer 42 is thus formed inside the heat insulating material 3, a layer having a lower density than the high-density layer 42 is still exposed on the surface layer of the heat insulating material 3. Therefore, even if it is going to harden the surface of the porous heat insulating material 3 using the adhesive agent 41 which consists of liquids, the density of the surface of the said heat insulating material 3 will vary. That is, the technique of forming a film on the surface of the heat insulating material 3 using the adhesive 41 is a technique for suppressing, for example, fibers constituting the heat insulating material 3 from scattering from the inside of the heat insulating material 3 to the outside. Yes, it can be said that this is not a technique that assumes that the heat insulating materials 3 and 3 slide on each other. In FIGS. 8 and 9, the top and bottom of the heat insulating material 3 (upper cover heat insulating material 22) is inverted from that of FIG. 1 described above.

  Furthermore, as a method of suppressing the sliding between the upper lid heat insulating material 22 and the main body heat insulating material 21, instead of the high-density layer 42, as shown in FIG. The example arrange | positioned on the lower surface side of the upper cover heat insulating material 22 is given. When the plate-like body 43 is arranged in this way, the plate-like body 43 does not enter the heat insulating material 3 (upper cover heat insulating material 22) like the adhesive 41. It is interposed between the main body heat insulating material 21 over the direction. However, when raising and lowering the temperature of the reaction tube 2, the thermal expansion / contraction rate differs between the upper lid heat insulating material 22 and the plate-like body 43. Therefore, as shown in FIG. 11, since sliding occurs between the upper lid heat insulating material 22 and the plate-like body 43, the upper lid heat insulating material 22 is scraped by the plate-like body 43. That is, it can be said that the plate-like body 43 in FIG. 11 constitutes a part of the main body heat insulating material 21 because it does not thermally expand and contract integrally with the upper cover heat insulating material 22 when viewed from the upper cover heat insulating material 22. Further, when a member other than the heat insulating material 3 is arranged in the region between the upper lid heat insulating material 22 and the main body heat insulating material 21 in this way, the reaction tube 2 radiates heat through the region, so that the inside of the reaction tube 2 Good thermal uniformity cannot be obtained.

  Furthermore, when the density of the upper lid heat insulating material 22 itself is higher than the density of the main body heat insulating material 21, the heat insulating performance of the upper lid heat insulating material 22 is deteriorated. That is, the heat insulating materials 3 such as the upper cover heat insulating material 22 and the main body heat insulating material 21 have a higher heat insulating property as the voids contained therein are larger, and the heat insulating properties are deteriorated as the voids are smaller. Therefore, when the density of the upper lid heat insulating material 22 itself is increased, good temperature uniformity in the reaction tube 2 cannot be obtained. Therefore, if it is intended to obtain good heat insulation while increasing the density of the upper lid heat insulating material 22 itself, it is necessary to increase the height dimension of the upper lid heat insulating material 22, which leads to an increase in the size and cost of the apparatus. .

  Further, as shown in FIG. 12, for example, even when a substantially rod-like or plate-like core material 45 extending in the horizontal direction is embedded in the upper lid heat insulating material 22, the lower portion of such a core material 45. When the crack 26 occurs in the area, it is difficult to suppress damage and dropout of the upper lid heat insulating material 22 at the site.

  Therefore, in the present invention, the heat insulation (heat insulation) inside the reaction tube 2 is secured at the contact portion with the main body heat insulating material 21 on the lower surface side of the upper cover heat insulating material 22 and the wear of the upper cover heat insulating material 22 is suppressed. For this purpose, the protective layer 23 made of ceramic fibers or the like is disposed as described above. That is, the method for forming the protective layer 23 will be described in detail. As shown in FIG. 13, first, an adhesive containing ceramic particles such as alumina or silica is interposed between the upper lid heat insulating material 22 and the protective layer 23. An adhesive layer 24 made of an agent is interposed. Then, the upper lid heat insulating material 22 and the protective layer 23 are bonded to each other by the adhesive layer 24. Alternatively, the protective layer 23 is soaked with the adhesive layer 24 and the protective layer 23 is attached to the upper lid heat insulating material 22. Next, when heat treatment of the structure including the upper lid heat insulating material 22, the protective layer 23, and the adhesive layer 24 is performed at a heat treatment temperature of about 1200 ° C., for example, as shown in FIG. Sintering (integration) is performed through the above-described particles constituting the adhesive layer 24. 13 and 14, the upper lid heat insulating material 22 is drawn upside down with respect to FIG. 1 and the like.

  Therefore, since the protective layer 23 is made of ceramic fibers as described above and can be freely deformed, and since the thermal expansion coefficients of the protective layer 23 and the upper lid heat insulating material 22 are aligned with each other, the protective layer 23 Is deformed (thermal expansion and contraction) in accordance with the thermal expansion and contraction of the upper lid heat insulating material 22. Specifically, as shown in FIG. 15, when the reaction tube 2 in a high temperature state (heat treatment temperature) is lowered to the carry-in / out temperature described above, the upper lid heat insulating material 22 contracts in the horizontal direction. The diameter is reduced in accordance with the contraction. On the other hand, when the temperature of the reaction tube 2 at the carry-in / out temperature is raised to the heat treatment temperature, the upper lid heat insulating material 22 expands in the horizontal direction, so that the protective layer 23 increases in diameter in accordance with this expansion.

  Therefore, in performing a large number of processing batches, when the temperature rise and fall of the reaction tube 2 is repeated as shown in FIGS. 15 and 16, the protective layer 23 slides with respect to the main body heat insulating material 21. As described above, the density (hardness) of the protective layer 23 is larger than the density of the main body heat insulating material 21. Therefore, when such sliding is repeated, the inner peripheral edge of the upper end portion of the main body heat insulating material 21 is scraped and worn by the protective layer 23 as shown in FIG. As described above, the difference between the density of the main body heat insulating material 21 and the density of the protective layer 23 is 1.5 times or more, preferably 2 times or more, so that the main body heat insulating material 21 is worn. Happens selectively (preferentially). Therefore, since the wear of the upper lid heat insulating material 22 is suppressed, the stepped portion 25 and the crack 26 described above are hardly formed or not formed. Therefore, dropping off of the upper lid heat insulating material 22 is suppressed.

  Furthermore, since the protective layer 23 is made of ceramic fibers in the same manner as the main body heat insulating material 21 and the upper lid heat insulating material 22, it can be said that it forms a part of the heat insulating material 3. Furthermore, since the thickness dimension t of the protective layer 23 is set thin as described above, an area between the upper lid heat insulating material 22 and the main body heat insulating material 21 is reduced while suppressing wear of the upper lid heat insulating material 22. Therefore, heat radiation of the reaction tube 2 is less likely to occur. Therefore, it can be said that the protective layer 23 secures the heat insulating function of the reaction tube 2 by the heat insulating material 3 while suppressing the wear (drop off) of the upper lid heat insulating material 22.

  According to the above-described embodiment, when the upper lid heat insulating material 22 is disposed in the upper opening of the main body heat insulating material 21, the protective layer 23 made of the heat insulating material 3 having a density higher than that of the main body heat insulating material 21 is applied to the upper cover heat insulating material. As a separate member from 22, the upper lid heat insulating material 22 is disposed at a contact portion with the main body heat insulating material 21 at the lower surface side peripheral edge portion. And about the protective layer 23, while comprising the material and density of the said protective layer 23 so that it may deform | transform following the thermal expansion and contraction of the upper cover heat insulating material 22, it is provided in the upper cover heat insulating material 22 integrally. For this reason, it is possible to suppress damage and dropout of the upper lid heat insulating material 22 due to sliding with the main body heat insulating material 21.

  And since the density of the protective layer 23 is set to 1.5 times or more, preferably 2 times or more than the density of the main body heat insulating material 21, the main body heat insulating material 21 can be selectively worn. Further, since the protective layer 23 is made of ceramic fibers and arranged as a part of the heat insulating material 3, the thickness t of the protective layer 23 is kept within the above-described range. The wear of the upper lid heat insulating material 22 can be suppressed while maintaining the heat insulating property of 2. Therefore, when the upper lid heat insulating material 22, the main body heat insulating material 21, and the protective layer 23 each made of ceramic fibers are used as the heat insulating material 3, it can be suitably applied to a vertical heat treatment apparatus that performs heat treatment at a high temperature of 1000 ° C. or higher.

  In addition, by suppressing the wear of the upper lid heat insulating material 22 in this manner, the upper lid heat insulating material 22 is less likely to be suddenly damaged. That is, the deterioration (abrasion) of the upper lid heat insulating material 22 is not a sudden phenomenon but a phenomenon that accompanies use over time. Therefore, even if it is between the upper lid heat insulating material 22 of a certain arbitrary production lot and the other upper lid heat insulating material 22 having a different production lot from the upper lid heat insulating material 22, each upper lid heat insulating material 22 deteriorates due to aged wear. A certain period (time) to complete. Therefore, since it becomes easy to set the period which replace | exchanges the upper cover heat insulating material 22 regularly, the maintenance of an apparatus becomes easy. And since the auxiliary heat insulating material 3a that functions as a buffer material when the heat insulating material 3 thermally expands and contracts is disposed outside the heat insulating material 3 composed of the upper cover heat insulating material 22 and the main body heat insulating material 21, further. Since the gap region 3 b is provided between the auxiliary heat insulating material 3 a and the exterior body 30, it is possible to secure an expansion allowance for the heat insulating material 3 to thermally expand and contract. In addition, you may arrange | position only the clearance gap area | region 3b in the inner peripheral surface of the exterior body 30, without providing the auxiliary heat insulating material 3a. That is, at least one of the auxiliary heat insulating material 3 a and the gap region 3 b is disposed between the exterior body 30 and the heat insulating material 3.

  In the above description, the protective layer 23 is formed in the contact portion with the main body heat insulating material 21 at the lower surface side peripheral portion of the upper cover heat insulating material 22, but as shown in FIGS. 18 and 19, the lower surface side of the upper cover heat insulating material 22. You may arrange in the whole. Moreover, although the recessed part 22a and the groove part 22b were formed in the lower surface side of the upper cover heat insulating material 22 and it comprised so that forced air cooling of the reaction tube 2 was carried out, as shown in these FIG.18 and FIG.19, the upper cover heat insulating material 22 is made into a board. You may form in a shape.

Furthermore, the reaction tube 2 may be configured as a double tube structure including an inner tube and an outer tube. In this case, a slit-like exhaust port extending in the vertical direction may be formed on the side wall surface of the inner tube, or the upper surface side of the inner tube is opened, and the exhaust port and the opening on the upper surface side are formed. The atmosphere in which the wafer boat 1 is placed may be exhausted.
In addition, the upper lid heat insulating material 22, the main body heat insulating material 21, and the protective layer 23 described above are mixed with ceramic powder and binder powder made of resin, for example, instead of being made of ceramic fibers. Each of the porous bodies molded and sintered may be used. Further, the protective layer 23 is configured to include at least one of the materials (compounds) constituting the upper lid heat insulating material 22 and the main body heat insulating material 21. For example, the upper cover heat insulating material 22 and the main body heat insulating material 21 are each made of alumina or the like. The protective layer 23 may be made of a fiber such as silica.

W Wafer 1 Wafer boat 2 Reaction tube 3 Heat insulating material 20 Heater 21 Main body heat insulating material 22 Upper cover heat insulating material 23 Protective layer

Claims (6)

In a vertical heat treatment apparatus for performing heat treatment in a vertical reaction tube on a plurality of substrates stacked in a shelf on a substrate holder,
A heating unit for heating the substrate in the reaction tube;
A main body heat insulating material, which is disposed outside the region heated by the heating unit so as to surround the side peripheral surface of the reaction tube in a cylindrical shape along the circumferential direction, and is composed of ceramics including voids;
An upper lid heat insulating material, which is arranged so as to close the upper opening of the main body heat insulating material, and is configured to have the same density as the main body heat insulating material,
In order to suppress damage to the upper lid heat insulating material while deforming following the thermal expansion / shrinkage of the upper lid heat insulating material when the upper lid heat insulating material thermally expands / shrinks, the main body heat insulating material at the lower edge of the upper lid heat insulating material A protective layer made of a refractory material that is provided at a contact portion with the material, has a higher density than the main body heat insulating material, and is a separate member from the upper lid heat insulating material,
This protective layer is bonded to the upper lid heat insulating material using an adhesive containing an inorganic component, and then integrated with the upper lid heat insulating material by heat treatment.   The vertical heat treatment apparatus according to claim 1, wherein the protective layer is configured to have a density that is 1.5 times or more the density of the main body heat insulating material.   The vertical heat treatment apparatus according to claim 1, wherein the protective layer is configured to have a density that is twice or more the density of the main body heat insulating material.   The thickness of the protective layer is set to prevent the reaction vessel from radiating heat through the region between the main body heat insulating material and the upper lid heat insulating material, and the upper cover heat insulating material slides on the main body heat insulating material. The vertical heat treatment apparatus according to any one of claims 1 to 3, wherein the vertical heat treatment apparatus is set to 1 mm or more and 2 mm or less in order to suppress movement and wear.   The vertical heat treatment apparatus according to any one of claims 1 to 4, wherein the heat treatment performed in the reaction tube is a heat treatment at 1000 ° C or higher. An exterior body is provided outside the main body heat insulating material and the upper lid heat insulating material,
Between these main body heat insulating material and upper lid heat insulating material and the exterior body, a buffer material having a density lower than that of the main body heat insulating material and the upper cover heat insulating material, and when the main body heat insulating material and the upper cover heat insulating material are thermally expanded. The vertical heat treatment apparatus according to any one of claims 1 to 5, wherein at least one of a gap region serving as an elongation margin is interposed.