Flanges and devices for substrate processing

Abstract

To provide a flange with improved temperature control.SOLUTION: The disclosure relates to a flange for a process tube in an apparatus for processing substrates, e.g., a vertical furnace. The flange may be provided with an opening for in use giving access to the process chamber of the process tube, and a cooling channel allowing a cooling fluid to flow therethrough to cool the flange. A material with a heat conductivity of 0.1-40 W / m K may be at least partially provided between the cooling fluid and the rest of the flange.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a flange for a process tube in an apparatus for processing substrates. The flange may include an opening for providing access to the interior of the process tube in use, and cooling channels for allowing a cooling fluid to flow through the flange for cooling.

[0002] More particularly, the present disclosure relates to an apparatus for substrate processing, a process tube forming a process chamber and having an opening at its lower end; a heater surrounding the process tube for heating the process tube; a flange for the process tube having an opening aligned with the opening of the process tube and a seal for sealing the process chamber; and Cooling channels are provided to allow a cooling fluid to flow through the seal to cool the seal. [Background technology]

[0003] Semiconductor substrates may be processed in batches in a vertical furnace. One example of such a process is the deposition of layers of various materials on a substrate. High purity and uniformity are typically desired for the deposited layers for various reasons, including uniformity of electrical and physical properties. However, deposition results may be adversely affected by the presence of particulate matter in the furnace. In some cases, particles may be deposited on or incorporated into the layer, degrading the purity and uniformity of the deposited layer. Therefore, there is a need for processing methods and systems that can achieve consistently low particle levels to achieve consistently high-quality processing results.

[0004] The particles may be the result of the formation of reaction by-products that condense at low temperatures on one of the flanges near the opening of the process tube. Therefore, the temperature of the flange may be maintained at an elevated temperature during processing to avoid condensation. However, when the hot wafer load is removed from the reaction tube, the hot load may radiate heat to the flange, further heating the flange. Sealing O-rings that may be used to seal the flange to the tube or other parts of the furnace may overheat and begin to leak due to this elevated temperature. To avoid overheating, the flange may be provided with temperature control. Summary of the Invention

[0005] This Summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in more detail below in the Detailed Description of Example Embodiments of this Disclosure. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] It may be an object to provide a flange with improved temperature control so that overheating of the seal and / or excessive condensation of by-products may be avoided.

[0007] According to one aspect, a flange for a process tube in an apparatus for processing substrates can be provided. The flange includes an opening for providing access to a process chamber of the process tube during use, and cooling channels for allowing a cooling fluid to flow therethrough to cool the flange. A material having a thermal conductivity of 0.1 W / m K to 40 W / m K is at least partially provided between the cooling fluid and the remainder of the flange.

[0008] According to another aspect, an apparatus for substrate processing is provided, comprising: a process tube forming a process chamber and having an opening at its lower end; a heater surrounding the process tube for heating the process tube; a flange for the process tube having an opening aligned with the opening of the process tube and a seal for sealing the process chamber; and and a cooling channel that allows a cooling fluid to flow through the seal to cool the seal. A material having a thermal conductivity of 0.1 W / m K to 40 W / m K may be provided at least partially between the cooling fluid and the seal.

[0009] For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described hereinabove. It is, of course, to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner to achieve or optimize one advantage or group of advantages as taught or suggested herein, without necessarily achieving other objects or advantages that may be taught or suggested herein.

[0010] All of these embodiments are intended to be within the scope of the invention disclosed herein. These and other embodiments will be readily apparent to those skilled in the art from the following Detailed Description of Certain Embodiments, which refers to the accompanying drawings, and the invention is not limited to any particular embodiment disclosed. [Brief explanation of the drawings]

[0011] While this specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, the advantages of embodiments of the present disclosure may be more readily apparent from the following description of certain specific examples of embodiments of the present disclosure when read in conjunction with the accompanying drawings.

[0012] [Figure 1] FIG. 1 is a schematic diagram of the lower end of a process tube of a vertical furnace in a closed position. [Figure 2] FIG. 2 is a detailed cross-sectional view of a cooling channel in a flange according to one embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view of a cooling channel in a flange according to one embodiment. [Figure 4] FIG. 4 is a schematic top view on a cooling channel according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] While specific embodiments and examples are disclosed below, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments and / or applications of the invention, and obvious modifications and equivalents thereof. Therefore, it is intended that the scope of the disclosed invention should not be limited by the specific disclosed embodiments described below. The figures shown herein are not meant to be actual illustrations of any particular materials, structures or devices, but merely idealized representations used to describe embodiments of the present disclosure.

[0014] As used herein, the terms "substrate" or "wafer" may refer to any underlying material that may be used or upon which a device, circuit, or film may be formed. The term "semiconductor device structure" may refer to any portion of a processed or partially processed semiconductor structure that is, includes, or defines at least a portion of an active or passive component of a semiconductor device formed on or in a semiconductor substrate.

[0015] Semiconductor substrates may be batch processed in a vertical furnace. One example of such a process is the deposition of layers of various materials on a substrate. Some of the processes may be based on, for example, chlorides and ammonia. Chloride-based chemistries using ammonia may be susceptible to particle formation. Without being limited by theory, it is believed that particle formation may be the result of condensation of NH4Cl on cold spots of the furnace, typically on the flange. Therefore, the flange may be heated to a temperature high enough to prevent condensation of NH4Cl. Other processes may be susceptible to condensation issues and require the flange to be heated as well. The flange may be heated to a temperature of, for example, 100°C or higher, more preferably 120°C or higher, even more preferably 150°C or higher, and most preferably 180°C or higher.

[0016] In addition to being heated as described above, the flanges typically also may be cooled to prevent, for example, thermal damage to O-rings that may be used to seal the flanges. The cooling system preferably effectively prevents overheating of the substrate while preferably not overcooling the flanges, so that the flanges may be cooled below a desired temperature to prevent condensation. Considering these conflicting requirements, preferred embodiments of the present invention provide a cooling system that can effectively and uniformly cool the flanges or other furnace structures without overcooling.

[0017] The flange may include a fluid cooling system in which a fluid, preferably water, flows through a channel. The channel may be disposed in the flange cavity and partially spaced from the cavity wall. Where the channel abuts the cavity wall, there may be a primary conduit for heat transfer between the flange and the channel. Adequate cooling may be facilitated by using an effective cooling medium, such as unheated water at or below room temperature. Advantageously, such a cooling system may be particularly simple and effective. The use of limited contact between the channel and the wall has proven more reliable and simpler than using a heated cooling medium, such as warm or hot water or heated glycol, to protect the flange from overcooling. This may also help against overheating of the cooling medium, which may ultimately result in decomposition or boiling of the cooling fluid or cause deposits to form in the channels through which the cooling medium circulates.

[0018] 1, 2, 3, and 4 schematically illustrate portions of an exemplary batch reactor. The illustrated reactor may be a vertical furnace-type reactor, which has advantages for efficient heating and loading sequences, but those skilled in the art will understand that the principles and advantages disclosed herein may be applied to other types of reactors.

[0019] FIG. 1 shows a cross-sectional side view of the lower portion of a process tube 10 of a vertical furnace 100. The process tube 10 may be dome-shaped, open at the bottom end, and closed at the top (not shown). The process tube 10 may define a process chamber 12. A heater 20 may surround the process tube 10 for heating the process tube. A pedestal 30 may support a wafer boat 40 holding a plurality of wafers 50, preferably 50 or more wafers. The pedestal 30 may be thermally insulated to prevent excessive heating of the surrounding portions of the vertical furnace 100, including a door plate 90 that supports the pedestal 30.

[0020] The process tube 10 (only its bottom end is shown) may have a wide base 11 that may be supported on a flange, such as an upper flange 80 or a lower flange 82. Additional flanges that surround the process tube 10 may be used to seal it. Flanges may also be used to support other components within the process tube, such as an injector or liner.

[0021] The flanges 80, 82 may have a substantially circular opening to provide access to the interior of the process tube 10 in use, for example, for transferring a substantially circular pedestal 30 with a wafer boat 40 holding a plurality of wafers 50 into the process chamber 12. A door plate 90 seals against the lower end of the lower flange 82 when the door plate 90 is in the closed position. It will be understood that the door plate 90 may be formed from a single type of material, for example, metal, or a combination of materials, for example, metal and quartz. The door plate 90 is vertically movable and may be lifted to close the opening in the process tube 10 and flanges by sealing against the lower flange 82. The door plate 90 opens by moving downward against the lower flange 82. The upper surface of the door plate 90 supports the pedestal 30, which in turn supports the wafer boat 40. An elevator 98 may be provided, for example, to raise or lower the door plate 90, pedestal 30, and wafer boat 40 to load or unload the wafer boat 40.

[0022] Gases, including inert and reactive precursor gases, may be provided to the process chamber 12 from a gas source 95, which may include multiple containers for holding various gases. In some embodiments, the precursor gases may include ammonia (NH) and / or chloride-containing gases, such as SiH2Cl2, TiCl4, HfCl4, and / or AlCl3. The flow of precursor gases from the gas source 95 to the process chamber 12 may be controlled by a controller 94. Gas openings (not shown) may be provided in the flanges 80, 82 for providing gases from the gas source 95 to the process chamber 12, for example, using injectors.

[0023] Gas openings in the flanges can also be used to remove gases from the process chamber 12. Reactive precursor gases can produce reaction by-products that can cause condensation in cooler portions of the vertical furnace 100, such as the flanges 80, 82 and / or door plate 90.

[0024] The temperature of the door plate 90 can be difficult to control. With each removal of a wafer boat 40, the door plate 90 moves downwardly away from the high-temperature furnace 100 and cools significantly. After reloading the furnace 100 with a newly loaded boat 40, the door plate 90 heats up from the hot parts of the furnace above the door plate 90 and from the heated flanges 80, 82. The insulation value of the pedestal 30 can be adjusted, within certain limits, to increase the heat reaching the door plate 90, heating it sufficiently to prevent condensation.

[0025] 1, in addition to or as an alternative to adjusting the insulation value of the base 30 to provide sufficient heat to the door plate 90, a door plate heater 92 may be provided. The door plate heater 92 is preferably provided below the base 30.

[0026] The temperature of the door plate 90 may be monitored in a variety of ways. For example, a temperature sensor 96 is preferably provided to actively monitor and control the door plate temperature. The temperature sensor 96 is in communication with a controller 94. After the desired door plate temperature is reached, the controller 94 causes reactive gases to flow from a gas source 95 into the process chamber 12 to perform various processes, including chemical vapor deposition of films on substrates.

[0027] The upper and lower flanges 80, 82 may be equipped with electric heaters 88 to raise the temperature of the flanges and minimize condensation on the flanges. In an exemplary design of a furnace for processing 300 mm wafers, the flanges 80, 82 may be provided with over 20 heaters, each providing up to approximately 100 watts of heat. It will be understood that the number of heaters depends on the flange design, the heater design and power, the thermal insulation of the pedestal 30, and the amount of insulating material provided on the outside of the tube 10 and flanges 80, 82. For example, more heaters may be used if the heaters are not very powerful, if the pedestal 30 is highly insulated thereby minimizing heat reaching the flanges 80, 82 from the top of the furnace 100, and / or if the flanges 80, 82 have minimal insulation such that they lose a significant amount of heat. Conversely, if the heater is more powerful, if the pedestal 30 does not significantly thermally insulate the flanges 80, 82 from the top of the furnace 100, and / or if the flanges 80, 82 are sufficiently insulated from heat loss, fewer heaters may be used.

[0028] During removal of the processed wafer load, hot wafers 50 and hot wafer boat 40 may pass through the flanges 80, 82. Without precautions, the O-rings in the flanges 80, 82, which contact other surfaces and provide a vacuum seal, may overheat. Deterioration of the O-rings undesirably reduces the ability to separate the atmosphere within the process tube 10 from the ambient environment, which may result in contamination or otherwise adversely affect processing results. Therefore, cooling channels 86 may be provided to prevent overheating of the O-rings.

[0029] Channels 86 may be provided with a flowing fluid to remove heat from flanges 80, 82 and cool the O-rings in contact with those flanges. A possible fluid for channel 86 may be water. However, water boils at 100°C and has a large cooling capacity, which may cause the flanges to overcool, thereby causing condensation of reaction by-products on the substantially circular inner surfaces of flanges 80, 82 that form the openings. Designs according to some preferred embodiments may avoid these and other disadvantages and enable the use of water cooling. As shown schematically in FIG. 1, water cooling channels 86 may be provided without intimate contact with flanges 80, 82. Cooling channels 86 may be shown in more detail in FIGS. 2, 3, and 4.

[0030] Referring to FIG. 2 , a cross section of a flange 800 is shown with an outer surface 802 and an inner surface 804. The inner surface 804 may be substantially circular. It will be understood that the flange 800 may be, for example, either the upper flange 80 or the lower flange 82 of FIG. 1 . For example, if the flange 800 were the lower flange 82 of FIG. 1 , a heater 812 corresponding to the heater 88 ( FIG. 1 ) may be provided. The flange may include a top and bottom surface with recesses 810 formed therein to provide space for O-rings and allow the flange 82 to seal against adjacent structures. Such structures may be, for example, the door plate 90, the upper flange 80, and / or the tube 10 ( FIG. 1 ).

[0031] 2, walls 822 of enclosure 821 for retaining a cooling fluid define cooling channels 86. Enclosure 821 may extend partially around the periphery of flange 800, and cooling channels 86 may also extend partially around the periphery of flange 800 to facilitate uniform cooling of that flange. For example, in the illustrated embodiment, if flange 800 is circular in horizontal cross section, enclosure 821 may be partially in the shape of an annular ring. Enclosure 821 may be removable, for example, to facilitate furnace maintenance.

[0032] The flange 800 may include a space for at least partially or completely accommodating the cooling channel 86. For example, the enclosure 821 defining the cooling channel 86 may be accommodated in a recess 823 defining a space within the flange 800. The recess 823 may extend partially or completely around the flange 800. The enclosure 821 may extend along the recess 823 to enable uniform cooling of the flange 800. The recess 823 may be provided on the top, bottom, or outer surface 802 of the flange 800. The recess 823 may be larger than the enclosure 821. Thus, the recess 823, e.g., the cooling channel 86, may have an inner wall that is spaced apart from the outer wall of the enclosure 821, such that open spaces 830, 831, and 832 may exist between the enclosure 821 and the flange 800.

[0033] The space for accommodating the cooling channels 86 formed by the recesses 823 may therefore be larger than the space required for the cooling channels 86, leaving open space. The open space may be provided with a material having a thermal conductivity of 0.1 to 40, preferably 0.5 to 10, and even more preferably 1 to 6 W / m K. Alternatively or additionally, the wall 822 of the enclosure 821 forming the cooling channels 86 may be made of a material having a similar thermal conductivity of 0.1 to 40, preferably 0.5 to 10, and even more preferably 1 to 6 W / m K. A suitable cooling fluid for the cooling channels 86 may be water, by providing a material having a thermal conductivity of 0.1 to 40, preferably 0.5 to 10, and even more preferably 1 to 6 W / m K at least partially between the cooling fluid and the remainder of the flange 800. While water has a large cooling capacity, using a material having a thermal conductivity of 0.1 to 40, preferably 0.5 to 10, and even more preferably 1 to 6 W / m prevents the flange 800 from overcooling. The risk of condensation of reaction by-products on the substantially circular inner surface of flange 800 may thereby be minimized, while the risk of boiling water in cooling channels 86 may also be minimized. The material may be applied uniformly throughout recess 821 around the periphery of flange 800 with the same thickness. In this way, the thermal conductivity around the periphery of flange 800 is the same, avoiding cold and hot spots within flange 800. Advantageously, preventing overcooling in this manner is more reliable and simpler than using media with less cooling capacity, including heating and cooling media such as warm or hot water or heated glycol.

[0034] 2 allows the thermal conductivity between flange 800 and cooling channels 86 to be tailored to suit different processing requirements. For example, the size of open spaces 830, 831, and 832 between enclosure 821 and flange 800, such as cooling channels 86, can be varied to alter heat transfer between cooling channels 86 and flange 800. For example, the size of recess 823 can be increased or decreased, and / or the size of cooling channels 86 can be increased or decreased, to decrease or increase, respectively, the size of open spaces 830, 831, and 832 between flange 800 and ring 821 to decrease or increase, respectively, the thermal conductivity.

[0035] FIG. 3 is a schematic cross-sectional view of a cooling channel 86 within a flange 800 according to one embodiment. The cooling channel 86 may have a substantially circular cross-section. The cooling channel 86 may be partially or completely contained within a recess 823 that defines a space within the flange 800. A portion of the space or recess 823 may contain the cooling channel 86, while another portion may remain open to form an open space within the recess 823. The open space may be provided with a material having a thermal conductivity of 0.1 to 40 W / m, preferably 0.5 to 10 W / m, and even more preferably 1 to 6 W / m. In this manner, the material is provided, at least in part, between the cooling fluid and the remainder of the flange 800.

[0036] The space or recess 823 may have a substantially rectangular cross-section. The space for accommodating the cooling channel 86 may be provided in the recess 823 in the outer surface 802 of the flange 800. The opening of the recess 823 may be slightly smaller than the outer radius of the circular cross-section of the cooling channel 86 so that the cooling channel 86 abuts the recess opening, as shown in FIG. 3 . This helps to position the cooling channel within the recess 823. The recess opening may also be equal to or larger than the outer radius of the circular cross-section of the cooling channel so that the cooling channel fits into the recess.

[0037] The walls 822 of the cooling channels 86 may comprise a metal. The cooling channels 86 may be at least partially surrounded by a material having a thermal conductivity of 0.1 to 40 W / m K. This thermal conductivity may be lower than the thermal conductivity of the metal of the cooling channels 86.

[0038] The cooling channel 86 may have walls 822 comprising a material having a thermal conductivity of 0.1-40 W / m K. The walls 822 may include multiple layers, such as a bilayer combining a layer of material having a thermal conductivity of 0.1-40 W / m K with a metal layer, which may facilitate manufacturing or even allow for the use of off-the-shelf products.

[0039] Materials with thermal conductivities of 0.1 W / m K to 40 W / m K can be selected from a group of materials including, for example, lead (35 W / m K), glass (0.8 W / m K), concrete (0.8 W / m K), and polymers such as silicone (3 W / m K) and polytetrafluoroethylene (PTFE) (0.2 to 0.6 W / m K). Silicones, such as polysiloxanes, are silicon-containing polymers made of siloxanes (-R2Si-O-SiR2-, where R = organic groups). Polytetrafluoroethylene (PTFE) is a fluorine-containing polymer made of tetrafluoroethylene. The flange can be made of metal, such as (stainless) steel or aluminum.

[0040] 4 is a schematic top view of a cooling channel according to one embodiment. The cooling channel 86 may be provided within a recess 823 provided along the periphery of a flange 800, such as the flanges of FIGS. 1-3. The flange 800 may include an opening 841 that provides access to the interior of the process tube 10 in use.

[0041] During heating and cooling, the flange 800 may expand and contract due to thermal expansion. The cooling channels can maintain a very stable temperature and cannot significantly expand or contract. This can lead to a situation where the cooling channels 86 may be pressed harder against the flange 800 when the flange is hot. This can change the thermal conductivity and / or degrade the quality of materials and / or cooling channels 86 that have thermal conductivities between 0.1 and 40 W / m K.

[0042] For example, a constant force actuator F, such as a spring 840, may be used to apply a constant force on the cooling channel 86. This constant force may cause the cooling channel 86 to press against the flange 800 and / or materials having thermal conductivities between 0.1 and 40 W / m K with the same force over a wide temperature range of the flange 800 and around the entire circumference.

[0043] The preferred embodiments are particularly applicable to chemistries in which chlorine-containing reactants are used in combination with ammonia (NH). Examples of chlorine-containing reactants are TiCl, SiClH, HfCl, and AlCl. While the embodiments have been developed in the context of chlorine chemistry, it is envisioned that the principles described herein may be advantageously applied in other situations in which condensable reaction by-products are produced, such as in the case of organic reactant materials (e.g., alkoxymetals or alkoxysilanes).

[0044] While illustrative embodiments of the invention have been described above, in part with reference to the accompanying drawings, it should be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0045] Throughout this specification, a reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment. Furthermore, it is noted that particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new embodiments not expressly described. [Explanation of symbols]

[0046] 10 Process Tubes 11 Base 12 Process Chamber 20 Heater 30 pedestal 40 wafer boats 50 wafers 80 Upper flange 82 Lower flange 86 cooling channels 88 Heater 90 Door Plate 92 Door plate heater 94 Controller 95 Gas Source 96 Temperature Sensor 98 Elevator 100 furnace 800 flange 802 Exterior 804 Inside 810 recess 812 heater 821 Enclosure 822 Wall 823 Space or recess 830, 831, 832 open space 840 Spring 841 Opening

Claims

1. 1. A flange for a process tube in an apparatus for processing a substrate, the flange being provided with an opening that, in use, provides access to a process chamber of said process tube and cooling channels that allow a cooling fluid to flow therethrough to cool said flange; the flange has a space for at least partially accommodating the cooling channel; A flange, wherein a material having a thermal conductivity of 0.1 to 40 W / m K is provided at least partially between said cooling fluid and said flange.

2. The flange of claim 1 , wherein a material having a thermal conductivity of 0.5 to 10 W / m K is provided at least partially between the cooling fluid and the flange.

3. The flange of claim 1, wherein a material having a thermal conductivity of 1 to 6 W / m K is provided at least partially between the cooling fluid and the flange.

4. The flange of claim 1 , wherein the flange has top and bottom surfaces with recesses for O-rings.

5. The flange of claim 1 , wherein the flange has a circular inner surface that defines the opening.

6. The flange of claim 1 , wherein a portion of the space for accommodating the cooling channel remains open to form an open space.

7. The flange of claim 6, wherein the open space comprises a material having a thermal conductivity of 0.1 to 40 W / mK.

8. The flange of claim 1 , wherein the cooling channel has a circular cross-section and the space has a rectangular cross-section.

9. The flange of claim 1 , wherein the space for accommodating the cooling channel is formed within a recess in an outer surface of the flange.

10. 10. The flange of claim 9, wherein the cooling channel has a circular cross-section and the recess has a rectangular cross-section with a recess opening that is smaller than a peripheral radius of the circular cross-section of the cooling channel, whereby the cooling channel contacts the recess opening.

11. The flange of claim 1 , wherein the cooling channel is made from metal and is at least partially surrounded by a material having a thermal conductivity lower than that of metal.

12. 10. The flange of claim 9, wherein the cooling channel has a circular cross-section and the recess has a rectangular cross-section with a recess opening that is equal to or greater than a perimeter radius of the circular cross-section of the cooling channel, whereby the cooling channel fits into the recess.

13. The flange of claim 1 , wherein the cooling channels are made from a material having a thermal conductivity of 0.1 to 40 W / m K.

14. The flange of claim 1 , wherein a heater is provided in a recess in an outer surface of the flange.

15. 10. The flange of claim 1, wherein the flange comprises a gas opening for providing or removing gas from the reaction tube.

16. The flange of claim 1 , wherein the material provided at least partially between the cooling fluid and the flange is a polymer.

17. 1. An apparatus for substrate processing, comprising: a process tube forming a process chamber and having an opening at its lower end; a heater surrounding the process tube for heating the process tube; a flange for the process tube having an opening providing access to the opening of the process tube and a seal for sealing the process chamber; and cooling channels to allow a cooling fluid to flow therethrough to cool said seal; the flange has a space for at least partially accommodating the cooling channel; An apparatus wherein a material having a thermal conductivity of 0.1 to 40 W / m K is provided at least partially between said cooling fluid and said flange.

18. The device, 20. The apparatus of claim 17, further comprising a door plate configured to support a wafer boat within the process tube, the flange having top and bottom surfaces with recesses for O-rings that function as the seals to seal the process chamber.

19. The apparatus of claim 17 , wherein the apparatus is constructed and arranged to provide water as the cooling fluid through the cooling channel.

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