JP2012156510A - Thermal processing furnace and liner for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal processing furnace that overcomes or mitigates a problem of backflow of material deposited near the downstream end of a gas exhaust path, and also provide a liner that may be installed in a conventional thermal processing furnace (possibly as a replacement for the originally installed liner) so as to overcome or mitigate the problem of backflow.SOLUTION: A thermal processing furnace comprises: a generally bell jar-shaped outer reaction tube having a central axis; and an open-ended inner reaction tube for accommodating a wafer boat holding a plurality of substrates. The inner reaction tube is substantially coaxially disposed within the outer reaction tube, thereby defining a gas passage between an outer wall of the inner reaction tube and an inner wall of the outer reaction tube. At least one of the outer wall of the inner reaction tube and the inner wall of the outer reaction tube is provided with a flow deflector that protrudes radially from the respective wall into the gas passage.

Description

  The present invention generally relates to a semiconductor substrate processing apparatus, and more particularly to a vertical heat treatment furnace and a liner used therein.

  In general, heat treatment furnaces or reaction furnaces are used for batch processing of semiconductor wafers in several manufacturing stages of silicon integrated circuits. Processing steps in which the furnace may be used include oxidation, diffusion, annealing, and chemical vapor deposition (CVD) and pulsed atomic layer deposition (ALD pulsed atomic layer deposition).

  A conventional vertical heat treatment furnace may include a heat resistant heating coil fed from a power source. A bell jar-shaped outer reaction tube and an inner reaction tube disposed coaxially in the outer reaction tube can be disposed inside the heating coil. The inner reaction tube is commonly referred to as a liner. The lower end of the outer reaction tube can be an open end, but the upper end of the outer reaction tube can be closed by a generally dome-shaped structure. The liner can be open at both its lower and upper ends. The lower ends of both the outer reaction tube and the liner can be supported on the flange. The flange may define a central furnace port through which a wafer boat holding a plurality of wafers enters and exits a reaction chamber formed by the inside of the liner. The wafer boat can be supported on a thermally insulating pedestal. This pedestal can be supported on a door plate that can function to seal the central furnace port of the flange. When connecting a vacuum pump to the flange, a gas supply conduit connected to a gas injector disposed inside the liner and a lower end of a gas flow path existing between the outer wall of the liner and the inner wall of the outer reaction tube And a gas discharge conduit that may be interposed between the gas exhaust line and the gas exhaust line.

  In operation, the wafer boat can be introduced into the reaction chamber and then the reaction chamber can be evacuated. Thereafter, process gas can be supplied to the reaction chamber via a gas supply conduit and a gas injector. The process gas can flow upward in the inner reaction tube while contacting a wafer provided in the inner reaction tube. When the process gas exits the upper end of the inner reaction tube and reaches the closed upper end of the outer reaction tube, it reverses its direction and flows downward through the gas flow path between the inner and outer reaction tubes and reacts by a vacuum pump. It can be discharged from the chamber via a gas discharge conduit.

  A common problem with heat treatment furnaces is contamination of the reaction chamber atmosphere with fine particles. Particles that reach the wafer being processed can render the die used for manufacturing inoperable. Contamination of the reaction chamber atmosphere can have a variety of causes.

  Patent Document 1 expresses the idea that the dome of a quartz bell jar type outer reaction tube generates a significant number of fine particles when heated. In operation, these particles can enter the upper open end of the inner reaction tube and fall from there onto the wafer boat and the wafers supported by it. In order to prevent this, Patent Document 1 teaches the use of a cover disposed at the upper end of the inner reaction tube. This cover may include multiple openings, such as multiple spiral passages, to prevent the majority of particles falling from the dome into the interior of the inner reaction tube, while allowing sufficient upward flow of process gas. .

  Patent Document 2 specifies a furnace port portion of a heat treatment furnace as a contamination source candidate, more specifically, degassing of an O-ring in the furnace port portion, leakage from a seal, and a wafer boat rotation mechanism. Since the furnace port is located upstream of the process gas flow in the reaction chamber, the process gas introduced into the reaction chamber can serve as a carrier for contaminants generated by the contamination source in the furnace port. Thus, these contaminants can deposit and / or adhere to any wafer present in the reaction chamber. Needless to say, this can hinder film growth, inhibit process reaction, and cause film quality degradation. In order to prevent contamination of the reaction chamber, Patent Document 2 teaches the use of a back diffusion preventer disposed between the reaction chamber on the furnace port side in the furnace and the space of the furnace port. Also, two individually operable gas exhaust systems, that is, a process gas exhaust system for exhausting the process gas from the reaction chamber, and a purge gas exhaust system for exhausting the purge gas from the furnace opening space are provided. . Thereby, while the furnace port part used as a contamination source is cut off from the reaction chamber by the back diffusion preventing body, a dedicated gas flow management mechanism is provided in both the reaction chamber and the furnace port space. Combining these features in this way makes it possible to prevent the diffusion of contaminants from the furnace opening space to the reaction chamber and even to the wafer.

US Pat. No. 7,736,437 US Pat. No. 6,503,079

  Applicant's work to further improve Applicant's heat treating furnace performance has revealed that there are other sources of contamination that are not yet recognized as sources of contamination in the reaction chamber atmosphere.

This source of contamination is partly due to the fact that process gas tends to form deposits when it is exhausted via a relatively cool lower furnace section that includes flanges and gas exhaust conduits. Seem. For example, when TEOS (tetraethylorthosilicate Si (OC ₂ H ₅ ) ₄ ), which can be used as a precursor in low-pressure chemical vapor deposition of a silicon dioxide (SiO ₂ ) film, is discharged from the reaction chamber together with reaction byproducts. The formation of solid and / or viscous liquid by-products is observed. These by-products are the result of low temperature combined chemical (surface) reactions in the downstream part of the furnace and accumulate on the flange and in the gas exhaust conduit. Another process that has been reported to deposit deposits downstream of the furnace is low pressure chemical vapor deposition of silicon nitride.

  By-product deposition itself near the downstream end of the gas exhaust path, ie on the flange and in the gas exhaust conduit, does not cause contamination of the reaction chamber. However, it appears that the material deposited at the downstream end of the gas discharge path can be rolled up and transported to the reaction chamber via the gas flow path by the recirculated gas flow. During normal operation of the heat treatment furnace, such a recirculated gas flow is unlikely to occur because multiple processes are generally performed at low pressure and a pressure gradient is provided and maintained along the gas discharge path by a vacuum pump. . However, there are situations where these elements do not prevent sediment backflow. For example, when one wafer boat holding processed wafers is ejected from the reaction chamber and another wafer boat holding a new batch of wafers is loaded into the reaction chamber, the reaction chamber is at atmospheric pressure. Sometimes the vacuum pump is temporarily switched off. When a new, relatively cool wafer boat and similarly cold unprocessed wafers held in it are introduced into the relatively warm reaction chamber, a significant temperature gradient is created inside the reaction chamber, in particular the outer reaction tube, It can be triggered between the liner and the wafer boat. These temperature gradients can induce pressure gradients and can result in convection on the surface of the liner. These convections can transport particles from the downstream end of the discharge path to the reaction chamber via the gas flow path. In this way, the particles can reach wafers, particularly those near the top of the wafer boat.

  One object of the present invention is to provide a heat treatment furnace in which the above-described backflow problem of material deposited at the downstream end of the gas discharge path is overcome or reduced.

  Another object of the present invention is to provide a conventional heat treatment furnace (possibly as a replacement for the liner originally installed) so as to overcome or reduce the problem of backflow of material deposited at the downstream end of the gas exhaust. It is to provide a liner that can be installed.

  One aspect of the present invention relates to a heat treatment furnace. The heat treatment furnace can include a substantially bell jar shaped outer reaction tube having a central axis. The heat treatment furnace may further include an open-ended inner reaction tube for accommodating a wafer boat holding a plurality of substrates. The inner reaction tube is disposed substantially coaxially inside the outer reaction tube, and defines a gas flow path between the outer wall of the inner reaction tube and the inner wall of the outer reaction tube. At least one of the outer wall of the inner reaction tube and the inner wall of the outer reaction tube may be provided with a flow deflector that protrudes radially from the wall into the gas flow path.

  Another aspect of the present invention relates to an inner reaction tube used by being installed in a double tube heat treatment furnace. The inner reaction tube can comprise a generally tubular wall having a central axis. The tubular wall may be provided with a flow deflector projecting radially outward therefrom.

  In the heat treatment furnace according to the present invention, a flow deflector can be provided on the inner wall of the outer reaction tube and / or the outer wall of the liner. The flow deflector can be of any suitable form (eg, one or more protrusions, ridges, (cantilever-like) deflector plates, etc.) from the wall into the gas flow path and from the furnace central axis. It can protrude almost radially. The primary purpose of this flow deflector is to carry pollutant particles and move the gas flow path upwards into the reaction chamber, somewhat turbulent or irregular, to block, eg deflect or weaken the gas flow. It is.

  In one embodiment, the flow deflector is such that the gas flow flowing in the upward direction of the central axis in the gas flow path is blocked at least once by the flow deflector regardless of the angular position of the gas flow with respect to the central axis. Can—in the direction of the central axis—can surround the inner reaction tube.

  In another embodiment, the flow deflector can protrude radially from the wall by a distance of at least 75% of the local width of the gas flow path to ensure sufficient blockage of the gas flow. In one embodiment where the flow deflector surrounds the inner reaction tube, the flow deflector may preferably protrude from the wall over at least one turn by the above distance of 75% of the local width of the gas flow path.

  In yet another embodiment, the flow deflector extends (ie, exists) in all three equal length sections that extend in the axial direction of the gas flow path and cover the entire length of the gas flow path as a whole. The deflector can extend along the axial length of the inner reaction tube or can be distributed over the entire axial length of the inner reaction tube. Dispersing or expanding such a flow deflector over the entire axial length of the gas flow path reduces the size of the axial gas flow path section where a strong upward gas flow can develop in the absence of the flow deflector. Help to minimize.

  The above and other features and advantages of the present invention will be more fully understood from the following detailed description of specific embodiments of the invention, taken in conjunction with the accompanying drawings, which are intended to illustrate the invention rather than to limit it. It will be.

  The heat treatment furnace and its liner according to the present invention overcome or reduce the problem of backflow of material deposited at the downstream end of the gas exhaust passage.

1 is a schematic cross-sectional side view of an exemplary embodiment of a heat treatment furnace according to the present invention. 1 is a schematic perspective view of an exemplary embodiment of a liner provided with a flow deflector including a plurality of generally tangentially deflecting baffles disposed at various axial positions. FIG. FIG. 6 is a schematic perspective view of another exemplary embodiment of a liner provided with a flow deflector including a plurality of generally tangentially deflecting baffles disposed at various axial positions. FIG. 6 is a schematic perspective view of an exemplary embodiment of a liner provided with a flow deflector including four baffles, each baffle extending helically along the outer wall around the central axis of the liner. 2 is a schematic perspective view of an exemplary embodiment of a liner provided with a flow deflector including two baffles, each baffle extending helically along the outer wall around the central axis of the liner. FIG.

  FIG. 1 schematically shows an exemplary vertical heat treatment furnace or reactor 1 according to the invention in a side sectional view. The furnace 1 is a double tube type and includes a substantially bell jar-shaped outer reaction tube 30 and an open-end inner reaction tube 40. The inner reaction tube 40 can also be referred to as a liner. The outer reaction tube 30 may be surrounded by a heating means such as a heat resistant heating coil 22 that is powered by a power source (not shown). The heating means can be further fixed to a heat insulating sleeve (not shown) surrounding the outer reaction tube 30. Both reaction tubes 30, 40 may have a cross-sectional shape that is generally tubular, for example, circular or polygonal. The outer diameter of the inner tube 40 can be smaller than the inner diameter of the outer reaction tube 30. Accordingly, the inner reaction tube 40 can be disposed at least partially within the outer reaction tube 30 and can extend approximately coaxially with the outer reaction tube 30 around a common central axis L. A gas flow path 20 may be defined between the inner wall 32 of the outer reaction tube 30 and the outer wall 41 of the inner reaction tube 40. When the reaction tubes 30 and 40 have the same cross-sectional shape, the gas flow path 20 may have a uniform width along its axial length. The (average) width of this gas channel can generally be in the order of a few centimeters, for example in the range of 1 to 5 centimeters. Both tubes 30, 40 can be made of quartz, silicon carbide, silicon, or another suitable refractory material.

  In the configuration shown in FIG. 1, the inner reaction tube 40 can delimit the reaction chamber 2 that can receive the wafer boat 26. Both the outer and inner reaction tubes 30, 40 can be supported by the flange 8 at their lower ends. The flange 8 can be made of stainless steel. The wafer boat 26 can enter and / or exit the reaction chamber 2 through the central furnace port 10 provided in the flange 8. A plurality of, for example between 50 and 150, wafer boats 26 that may include the same number of slots to hold semiconductor wafers 27 may be mounted on a (sleeveless) pedestal 28. The pedestal 28 itself can be mounted on a seal cap or door plate 12. The pedestal 28 functions as a heat shield for both the door plate 12 and the flange 8, and can reduce heat loss from the lower part of the furnace 1. In some embodiments, wafer boat 26 and pedestal 28 may be rotatable by motor means (not shown).

  Several elastic O-rings 14 are used in the lower part of the furnace 1, in particular between the outer reaction tube 30 and the flange 8, and between the flange 8 and the door plate 12 in order to ensure that the reaction chamber 2 is hermetically sealed. Yes. The lower part of the furnace 1 is preferably kept cooler than the temperature at the center and upper part of the reaction chamber 2 because elastic O-rings and other sealing mechanisms can be unreliable due to frequent or continuous exposure to high temperatures. Can be done.

  The furnace 1 may further include a gas injector 4. The gas injector 4 is disposed inside the reaction chamber 2 and may include a plurality of gas ejection holes 6 provided over the entire height or the axial length of the wafer boat 26. In some cases, a gas supply conduit 18 is connected to the gas injector 4 via a flange 8 so as to allow introduction of process gas, for example precursor gas and / or purge gas, into the reaction chamber 2 from the gas outlet 6. Yes.

  In order to release or discharge gas from the reaction chamber 2, a gas discharge conduit 16 is connected to the lower or downstream end of the gas flow path 20, possibly via a flange 8 (as schematically shown in FIG. 1). Can communicate. The downstream end of the gas discharge conduit 16 can be connected to the suction side of the vacuum pump 24.

  During normal operation, the gas introduced into the reaction chamber 2 from the hole 6 of the gas injector 4 flows almost upward in the reaction chamber. The gas turns at the top opening of the inner tube 40 and then flows down through the gas flow path 20 between the outer and inner tubes 30, 40 to connect to the vacuum pump 24. Head for. In FIG. 1, this gas discharge path is indicated by reference numeral 21. During discharge, the reactive gas deposits as it passes through the lower part of the furnace 1, i.e. the part containing the flange 8 and the gas discharge conduit 16 (part of the flange 8 in the embodiment of FIG. 1). Can be formed.

  By-product accumulation near the downstream end of the gas discharge path 21 does not cause contamination of the reaction chamber 2 by itself. However, under certain conditions, the material deposited at the downstream end of the gas discharge passage 21 can be rolled up and transported to the reaction chamber 2 via the gas passage 20 by the recirculation gas flow. For example, when one wafer boat 26 holding a processed wafer 27 is discharged from the reaction chamber 2 and another wafer boat holding a new batch of wafers 27 is loaded into the reaction chamber 2, the reaction chamber 2 is loaded. 2 may become atmospheric pressure, and the vacuum pump 24 may be temporarily switched off. When a new, relatively cold wafer boat 26 and a similarly cold unprocessed wafer 27 held in it are introduced into the relatively warm reaction chamber 2, a significant temperature gradient is created inside the reaction chamber, particularly outside. It can be caused between the reaction tube 40, the inner reaction tube 30 and the wafer boat 26. These temperature gradients can induce pressure gradients and / or gas density gradients, which can result in convection on the surface of the inner reaction tube 30. These convections can transport particles from the downstream end of the discharge path 21 to the reaction chamber 2 via the gas flow path 20. In this way, the particles can reach the wafers 27, in particular the wafers 27 arranged near the upper end of the newly introduced wafer boat 26.

  In order to prevent such a backflow of deposits, a flow deflector 50 may be provided on the outer wall 41 of the inner reaction tube 40 and / or the inner wall 32 of the outer reaction tube 30. The flow deflector 50 can protrude from the wall into the gas flow path 20 in a substantially radial direction with respect to the central axis L of the reaction tubes 30 and 40.

  In the heating furnace 1 of FIG. 1, a flow deflector 50 in the form of a single annular baffle plate 52 projecting radially in the gas flow path 20 is provided in both the outer reaction tube 30 and the inner reaction tube 40. . These flow deflectors 50 define a narrow Z-shaped gap through which the gas can pass between the deflector itself and the walls 32 and 41 at approximately the midpoint of the axial length of the gas flow path 20. The deflectors are provided close enough to each other. Regardless of the angular position of the gas flow with respect to the central axis, the deflecting plates 52 of these flow deflectors 50 are arranged on the inner reaction tube 40 so as to inevitably block the gas flow in the direction of the central axis L in the gas flow path 20. Surrounding or surrounding.

  It will be apparent that the annular baffle plate 52 in the embodiment of FIG. 1 surrounds the inner reaction tube 40. However, in view of more elaborate flow deflector embodiments, the following will be noted. Whether the flow deflector surrounds the inner reaction tube 40 (at least once) can be optimally determined by looking at the double tube structures 30, 40 in the direction of the central axis L. Viewed in this axial direction, it can be seen that the flow deflector surrounding the inner tube 40 is normally visible and extends over a 360 ° angle around the axis L. Thus, it is not necessary to extend the flow deflector around the tube 40 in a single axial position, like the baffle plate 52 of FIG. 1, to surround the inner tube 40. There is also no need to construct the flow deflector with a single piece. As described with reference to FIGS. 2 and 3, with a plurality of components, such as a plurality of baffles, that surround the inner tube 40 as a whole in the sense defined above and that can be provided at different axial positions, respectively. A flow deflector may be configured.

  The flow deflector 50 may preferably protrude deep enough into the gas flow path 20 to ensure efficient prevention of backflow. Strictly speaking, “sufficiently deep” means in particular the (local) width of the gas flow path 20, ie the (local) distance between the inner wall 32 of the outer reaction tube 30 and the outer wall 41 of the inner reaction tube 40. It can vary depending on the situation. In general, the flow deflector 50 may preferably protrude radially from the wall in which the flow deflector 50 is provided over a radial distance of at least 75% of the local width of the gas flow path 20. For example, if the outer and inner reaction tubes 30, 40 define a cylinder jacket-shaped gas flow path 20 having a uniform width of 25 millimeters along the central axis L, the flow deflector 50 is preferably at least 19 millimeters (ie Can extend into the gas flow path 20 by a radial distance of 0.75 × 25 mm). The flow deflector 50 protrudes into the gas flow path 20 when the inner reaction tube 40 is slightly disposed, for example, 5 mm, off-axis and the width of the gas flow path 20 changes between 20 mm and 30 mm in the tangential direction. The distance can correspondingly vary, for example between 15 mm and 23 mm.

  The outer and inner reaction tubes 30, 40 are usually manufactured separately and assembled at a later stage to form the double tube structure of the furnace 1. In order to allow such an assembly to carefully move the inner reaction tube 40 into the outer reaction tube 30, it is desirable that a gap of at least a few millimeters be between the two components. This gap may preferably be at least 2 millimeters, more preferably in the range of 2-8 millimeters. Thus, the flow deflector preferably flows over a radial distance less than or equal to the local width of the gas flow path 20 minus at least 2 millimeters, or preferably 2-8 millimeters depending on the desired gap. Can protrude radially from the wall on which is provided.

  As described above, the flow deflector can comprise a plurality of baffles. These baffles can be provided on the walls 32, 41 of the outer and / or inner reaction tubes 30, 40. Several embodiments of such a flow deflector 50 will now be described with reference to FIGS. It should be noted in advance that in the embodiment shown in FIGS. 2 and 3, the deflector plate 52 of the flow deflector 50 is provided on the outer wall 41 of the liner 40 and the liner is shown alone. . However, those skilled in the art will appreciate that a similar baffle pattern may be provided on the inner wall 32 of the outer reaction tube 30 instead or in addition.

  FIG. 2 schematically illustrates two embodiments of the liner 40. Each embodiment features a flow deflector 50 that includes a plurality of the same baffle plates 52 that project radially from the outer wall 41 of the liner at different axial positions and extend substantially tangentially along the outer wall 41 of the liner. And The two embodiments share some characteristics.

  In both embodiments, each baffle plate 52 extends along the outer wall 41 of the liner 40 in a tangential direction over an angle α of about 35 degrees with respect to the central axis L. However, in other embodiments, the angle range α of at least some of the baffle plates 52 may be smaller or larger than 35 degrees, and may be within a range of 10 to 90 degrees, for example. Furthermore, the baffle plate 52 of both embodiments extends substantially in the tangential direction, that is, does not extend in the axial direction L at all or at least largely. However, in other embodiments, one or more baffles 52 may extend along the outer wall 41 in a direction having both a tangential component and an axial component (see the embodiment of FIG. 3). .

  In either embodiment of FIG. 2, baffle plates 52 are disposed at discrete (6) axial positions that are spaced equidistantly and scattered over the axial length or height of liner 40. ing. As a result, when the liner 40 is incorporated in the heating furnace 1 similar to FIG. 1, the flow deflector 50 extends at least in the axial direction of the gas flow path 20 and covers the entire length of the gas flow path 20 as a whole. It is distributed substantially uniformly over the entire length of the gas flow path 20 so as to extend to all two equal length portions (eg, in the illustrated orientation, the lower, middle and upper portions of the gas flow path 20).

  Each axial position in each embodiment of FIG. 2 consists of the same number of baffles 52 spaced equidistantly in the tangential direction, ie six in the embodiment of FIG. 2A and three in the embodiment of FIG. 2B. Characterized by a series. Therefore, the configuration of the deflecting plates 52 at different axial positions is the same, but the series of deflecting plates present at specific axial positions is in the rotational direction with respect to the series of deflecting plates present at adjacent axial positions. The position is shifted. The series of baffle plates 52 present at different axial positions are displaced from each other in the rotational direction. When viewed in the axial direction L, the flow deflector 50—that is, considering all the baffle plates 52 as one unit— They may partially overlap each other (as viewed in the axial direction L) so as to completely surround 40. Indeed, the baffle plate 52 can be considered to surround the liner 40 multiple times. In the embodiment of FIG. 2A, the series of adjacent baffle plates 52 (in the axial direction) each surrounds the liner 40 as a whole, and in the embodiment of FIG. 2B, consists of four adjacent axial positions. The baffle plates 52 of each set make a complete round as a whole.

  Due to the fact that the flow deflector 50 is configured to surround the liner 40 multiple times, the gas flow moving in the axial direction L along the outer wall 41 of the liner 40 can be caused by the various deflectors 52 of the flow deflector 50 multiple times. Can be blocked. Furthermore, since the flow deflector 50 is substantially uniformly distributed over the entire axial length of the liner 40, there is no baffle plate 52, and therefore an outer wall 41 extending in the axial direction that tends to develop a relatively strong backflow. There is no particular part. Alternatively, the flow deflector 50 can be viewed as a labyrinth made up of a plurality of flow blocking / deflecting baffles 52 that scatter in the axial direction and develop a stream that can transport sediment.

  FIG. 3 schematically shows two other exemplary embodiments of a liner 40 according to the present invention. Both illustrated liners 40 feature a flow deflector 50 that includes a number of baffles 52 that extend helically along the outer wall 41 of the liner about a central axis L. Since each baffle 52 extends along substantially the entire axial length of the liner 40, when the liner 40 is incorporated into a furnace as shown in FIG. It extends in the axial direction of the passage 20 and extends to all three equal length portions covering the entire length of the gas passage 20 as a whole.

  The liner 40 of the embodiment of FIG. 3A includes four baffles 52, and the liner of the embodiment of FIG. 3B includes only two baffles. The baffle plate 52 of both embodiments is arranged such that the flow deflector 50 surrounds the liner 40 when viewed in the direction of the central axis L. Furthermore, the number of baffle plates 52 in both embodiments relates to the angular range α of a single baffle plate 52 relative to the central axis L when viewed in the direction of the central axis. For example, in the embodiment with four deflectors of FIG. 3A, the angle range α of each deflector 52 is (360/4 =) 90 degrees, and in the embodiment with two deflectors of FIG. 3B, The angle range α of each baffle is (360/2 =) 180 degrees. In general, in the flow deflector 50 including a plurality of baffle plates 52 extending in a spiral shape, the angle range of each baffle plate with respect to the central axis L is at least 360 / n degrees, which is extremely effective for preventing backflow. Looks like. In particular, since the number n of deflecting plates that need to be provided is relatively small, for example, four or less, the deflecting plates 52 can be manufactured economically.

  From the perspective of preventing backflow, it may be desirable to configure and use a flow deflector 50 having a relatively large number of baffles 52. However, the large number of baffle plates 52 may mean an increase in flow resistance along the discharge path 21, so that the demand for the vacuum pump 24 of the heat treatment furnace 1 may increase. The increase in flow resistance caused by the presence of a modest number of helically extending baffles 52 (ie, up to four baffles) as shown in FIG. 3 is relatively small and is a substantial problem for most applications. It was shown by numerical simulation that it was not.

  Although exemplary embodiments of the present invention have been described above with some reference to the accompanying drawings, it should be understood that the present invention is not limited to these embodiments. Those skilled in the art will understand variations of the disclosed embodiments by studying the drawings, the disclosure, and the appended claims, and can be implemented in the practice of the invention. Throughout this specification, reference to “an embodiment” or “an embodiment” refers to a particular feature, structure, or characteristic described in connection with that embodiment, which is at least one embodiment of the invention. It is included in. Thus, the appearances of the phrases “in one embodiment” or “in one embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new, unspecified embodiments.

DESCRIPTION OF SYMBOLS 1 Heat processing furnace / reaction furnace 2 Reaction chamber 4 Gas injector 6 Gas ejection hole 8 Flange 10 Central furnace port 12 Door plate 14 O-ring 16 Gas discharge conduit 18 Gas supply conduit 20 Gas flow path 21 Gas discharge path 22 Heating coil 24 Vacuum pump 26 Wafer boat 27 Substrate / wafer 28 Pedestal 30 Outer reaction tube 32 Inner wall of outer reaction tube 40 Inner reaction tube / liner 41 Outer wall of inner reaction tube 50 Flow deflector 52 Baffle plate of flow deflector L Center of both inner and outer reaction tubes Axis n Number of flow deflector deflectors α Angular range of flow deflector deflectors

Claims (17)

A substantially bell jar shaped outer reaction tube having a central axis (L);
An open-end inner reaction tube for accommodating a wafer boat holding a plurality of substrates, wherein the inner reaction tube is disposed substantially coaxially in the outer reaction tube, whereby the outer wall of the inner reaction tube and the outer wall An inner reaction tube in which a gas flow path is defined between the inner wall of the reaction tube;
In a heat treatment furnace comprising:
At least one of the outer wall of the inner reaction tube and the inner wall of the outer reaction tube is provided with a flow deflector that projects radially from the wall into the gas flow path.   The flow deflector—as viewed in the direction of the central axis (L) —is the inner reaction tube so that a gas flow in the direction of the central axis in the gas flow path is blocked at least once by the flow deflector. The heat treatment furnace according to claim 1, which surrounds   The heat treatment furnace of claim 1, wherein the flow deflector protrudes radially from the wall over a distance of at least 75% of the local width of the gas flow path.   The heat treatment according to claim 3, wherein the flow deflector protrudes radially from the wall over a distance less than or equal to a local width of the gas flow path minus 2 millimeters, preferably 2-8 millimeters. Furnace.   2. The heat treatment furnace according to claim 1, wherein the flow deflector extends in all three portions of the same length that extend in an axial direction of the gas flow path and cover the entire length of the gas flow path as a whole. .   The heat treatment furnace according to claim 1, wherein the flow deflector includes at least one baffle.   The heat treatment furnace of claim 6, wherein the flow deflector comprises a plurality of baffles extending substantially tangentially.   The baffle plates extending in a substantially tangential direction are arranged as a series of at least two baffle plates, the baffle plates included in the same series extend at the same axial position, and at least two series of baffle plates are The heat treatment furnace according to claim 7, which is provided at different axial positions.   The heat treatment furnace according to claim 6, wherein the flow deflector comprises at least one baffle extending spirally with respect to the central axis (L).   The flow deflector includes a plurality of n baffles extending spirally with respect to the central axis (L), and the angular range of each of the baffles is as viewed in the direction of the central axis. The heat treatment furnace according to claim 9, which is at least (360 / n) degrees.   An inner reaction tube for use in a heat treatment furnace having a substantially tubular wall having a central axis (L), wherein the tubular wall is provided with a flow deflector projecting radially outward from the tubular wall. Reaction tube.   The inner reaction tube of claim 11, wherein the flow deflector—as viewed in the direction of the central axis (L) —around the inner reaction tube.   The flow deflector protrudes from all three portions of the inner reaction tube of the same length extending in the axial direction of the inner reaction tube and covering the entire length of the inner reaction tube as a whole. Inner reaction tube as described.   14. An inner reaction tube according to any one of claims 11 to 13, wherein the flow deflector comprises at least one baffle extending substantially tangentially.   The flow deflector comprises a plurality of generally tangentially extending baffles arranged as a series of at least two baffle plates, wherein the baffle plates in the same series extend to the same axial position, 15. The inner reaction tube according to claim 14, wherein at least two series are provided at different axial positions.   The inner reaction tube according to any one of claims 11 to 13, wherein the flow deflector includes at least one baffle extending spirally with respect to the central axis.   The flow deflector includes a plurality of n baffles extending spirally with respect to the central axis (L), and the angular range of each of the baffles is as viewed in the direction of the central axis. The inner reaction tube of claim 16, wherein the inner reaction tube is at least (360 / n) degrees.

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