Heat distribution element

Abstract

To provide a heat distribution element for substrate processing apparatuses improved so as to easily remove a heater.SOLUTION: A heat distribution element 20 for substrate processing apparatuses includes: two panel-shaped surfaces 23 having a curved and panel-shaped structure and facing each other; narrow ends 21, 21', 22 and 22' connecting the two panel-shaped surfaces; and at least one opening 28 existing in at least one of the narrow ends. At least one of the two panel-shaped surfaces is constituted so as to distribute heat; the opening 28 exists so as to at least partially penetrate the heat distribution element; and at least a part of the heater element is constituted so as to be arranged in the inside.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates generally to substrate processing apparatus and methods, and more particularly, but not exclusively, to chemical deposition or etching reactors.

[0002] Please note that this section provides useful background information, but is not an admission that the technology described herein represents the state of the art.

[0003] In chemical deposition methods such as Atomic Layer Deposition (ALD) and Atomic Layer Etching (ALE), the temperature required for surface reactions is achieved through heating. This heating is often achieved by activating heaters that are installed inside or outside the walls of the reaction chamber of the substrate processing equipment. Regardless of the material used as the heat source, it is well known that the heater surface suffers from oxidation, which can then be corroded due to chemicals leaking from the reaction chamber of the equipment. Heaters are usually fixed in the equipment structure and require a lot of effort to remove. It is difficult to replace the heater or to remove it across other parts of the equipment. This has created a need to develop an improved heater solution that allows for easy removal, or at least to provide an alternative to existing solutions. Abstract

[0004] It is an object of certain embodiments of the present invention to provide an improved substrate processing apparatus, or at least to provide an alternative solution to existing technology.

[0005] According to an exemplary aspect of the present invention, there is provided a substrate processing apparatus comprising: a reaction chamber; an outer chamber at least partially surrounding the reaction chamber and defining an intermediate space between the outer chamber and the reaction chamber; at least one heating element; at least one heat distribution element disposed within the intermediate space; at least one heating element feedthrough within the outer chamber; the at least one heating element feedthrough allowing at least a portion of the at least one heating element to pass through the intermediate space and couple to the at least one heat distribution element.

[0006] In some embodiments, the at least one heating element is a cartridge heater and is removable and replaceable.

[0007] In some embodiments, the at least one heating element is configured to be removably coupled to the at least one heat distribution element. In some embodiments, the at least one heating element is removably set at least partially inside the at least one heat distribution element. In some embodiments, the phrase removably set heating element refers to a removably set heating element, i.e., the heating element can be removed from a position in the same way that it was initially set in that position. In some embodiments, the at least one heating element is coupled to the at least one heat distribution element means that the at least one heating element is in thermal contact with the at least one heat distribution element.

[0008] In some embodiments, the at least one heating element is removably and / or interchangeably set at least partially within two different heat distribution elements.

[0009] In some embodiments, the heating element is an elongated element. In some embodiments, the at least one heating element is set such that its longitudinal axis is vertical when in an operative state. In some embodiments, the at least one heating element is set such that its longitudinal axis is horizontal or oblique when in an operative state. In some embodiments, the heating element is disposed below the reaction chamber when in an operative state. In some embodiments, the heating element is disposed above the reaction chamber when in an operative state. In some embodiments, the heating element is disposed to the side of the reaction chamber when in an operative state.

[0010] In some embodiments, the apparatus includes two or more heating elements. In some embodiments, the apparatus includes at least two, at least three, or at least four heating elements. In some embodiments, the apparatus includes more than four heating elements.

[0011] In some embodiments, the at least one heating element is an elongated rod-like element. In some embodiments, the heating element has a rotationally symmetric horizontal cross-section when oriented with its longitudinal axis in the vertical direction. In some embodiments, the heating element has a flattened vertical side facing the reaction chamber and the outer chamber when oriented with its longitudinal axis in the vertical direction.

[0012] In some embodiments, the maximum voltage applied to the heating element depends on the shape and size of the heating element. In some embodiments, the voltage is 48-240 V. In some embodiments, the maximum heating power depends on the voltage and the amount of heating wire disposed within the heating element.

[0013] In some embodiments, the maximum heating power and voltage applied to the heating element depends on the type of the heating element, for example the heating element can be a radiant heater, a conductive heater, or a convection heater.

[0014] In some embodiments, the at least one heating element is configured to be removably located at least partially within the intermediate space between the outer chamber and the reaction chamber through the heating element feedthrough of the outer chamber. In some embodiments, the at least one heating element feedthrough is located at a bottom of the outer chamber. In some embodiments, the at least one heating element feedthrough is located at a top of the outer chamber. In some embodiments, the at least one heating element feedthrough is located at a side of the outer chamber. In some embodiments, the at least one heating element feedthrough is tightened or sealed from the outside of the outer chamber to seal where the heating element enters. In some embodiments, each heating element feedthrough of the outer chamber comprises a seal between the heating element feedthrough and the heating element. In some embodiments, the seal is located on the outside of the outer chamber to seal where the heating element enters. In some embodiments, the seal is located inside the heating element feedthrough to seal where the heating element enters. In some embodiments, the seal is a flange, for example a vacuum flange. In some embodiments, the seal is a cover plate.In some embodiments, the seal includes an O-ring.

[0015] In some embodiments, the apparatus comprises a plurality of heat distribution elements at least partially surrounding a periphery of the reaction chamber. In some embodiments, a plurality of heat distribution elements means two or more heat distribution elements. In some embodiments, the apparatus comprises two or more heat distribution elements. In some embodiments, the number of heat distribution elements included in the apparatus is at least two, at least three, or at least four. In some embodiments, the apparatus comprises four quadrant heat distribution elements.

[0016] In some embodiments, the at least one heat distribution element is configured to effectively and evenly distribute, as applicable, thermal radiation, thermal convection, or thermal conduction around the reaction chamber, hi some embodiments, the heat distribution element is configured to effectively and evenly distribute, as applicable, thermal radiation, thermal convection, or thermal conduction into and through the walls of the reaction chamber.

[0017] In some embodiments, the at least one heat distribution element is configured to heat the reaction chamber to a uniform temperature. In some embodiments, the at least one heat distribution element is configured to deliver heat uniformly to the interior volume of the reaction chamber and to at least one substrate within the reaction chamber.

[0018] In some embodiments, the at least one heat distribution element is a panel-like element and / or has a curved structure. In some embodiments, the heat distribution element is a curved panel-like element. In some embodiments, the device comprises four quadrant heat distribution elements and one heating element coupled to the four quadrant heat distribution elements. In some embodiments, the device comprises four quadrant heat distribution elements and four heating elements, each coupled to two of the four quadrant heat distribution elements.

[0019] In some embodiments, the device comprises a heating element. In some embodiments, the heat distribution element is formed as a single piece. In some embodiments, the heat distribution element has the shape of a hollow, curved or circular cylinder or tube.

[0020] In some embodiments, each heat distribution element is heated by at least one heating element. In some embodiments, each heat distribution element is heated by two heating elements. In some embodiments, each heat distribution element is heated by multiple heating elements.

[0021] In some embodiments, the heat distribution element is made of aluminum.In some embodiments, the heat distribution element is made of a material selected from copper, brass, titanium, steel, ceramic, and silicon nitride.

[0022] In some embodiments, the intermediate space is configured to maintain vacuum conditions. In some embodiments, the apparatus is configured to maintain a pressure in the intermediate space, wherein the at least one heat distribution element is under a pressure of 100-0.01 mbar. In some embodiments, the apparatus is configured to maintain the pressure in the intermediate space at 10-0.1 mbar or 5-0.1 mbar during a deposition or etching processing cycle. In some embodiments, the pressure in the intermediate space is maintained at 100-0.01 mbar (more preferably 10-0.1 mbar or 5-0.1 mbar) even during a period following the processing cycle.

[0023] In some embodiments, the device comprises a sheath element between the at least one heating element and the at least one heat distribution element to protect the at least one heating element. In some embodiments, the sheath element between the heating element and the heat distribution element is configured to transfer heat from the at least one heating element to the at least one heat distribution element. In some embodiments, the sheath element between the heating element and the heat distribution element is configured to transfer heat from the at least one heating element to the at least one heat distribution element. In some embodiments, the at least one heating element is coupled to the at least one heat distribution element via the sheath element. In some embodiments, the sheath element is configured to contact the at least one heat distribution element in the operating state. In some embodiments, the sheath element is configured to contact the at least one heating element in the operating state. In some embodiments, the sheath element is configured to serve as a housing for the at least one heating element when the at least one heating element is at least partially inserted into the sheath element in the operating state. In some embodiments, the sheath element is configured to cover an entire surface of the heating element in the intermediate space to protect the heating element, hi some embodiments, the sheath element is configured to cover most of the surface of the heating element in the intermediate space.

[0024] In some embodiments, the sheath element has a longitudinal axis oriented vertically when placed around the heating element in an operational state, and the sheath element has a longitudinal axis oriented horizontally or obliquely when placed around the heating element in an operational state.

[0025] In some embodiments, the sheath element has a surface structure that supports the at least one heat distribution element.In some embodiments, the sheath element has a surface structure that supports the weight of the at least one heat distribution element.

[0026] In some embodiments, the at least one heating element is configured to be at least partially removably disposed within the sheath element. In some embodiments, the at least one heating element is configured to be at least partially retractably disposed within the sheath element. In some embodiments, the at least one heating element is configured to be at least partially within an internal lumen of the sheath element.

[0027] In some embodiments, the sheath element is an elongated sheath-like element. In some embodiments, both ends of the elongated shaft of the sheath element are open ended. In some embodiments, one end of the elongated shaft of the sheath element is closed (or blind ended). In some embodiments, the sheath element is made of aluminum. In some embodiments, the sheath element is made of stainless steel, molybdenum, or similar metals with good thermal conductivity.

[0028] In some embodiments, each heating element is covered by the sheath element in the intermediate space beyond the point of penetration through the heating element feedthrough. In some embodiments, the sheath element couples to a seal between the heating element feedthrough and the heating element. In some embodiments, the sheath element couples to a vacuum flange in the heating element feedthrough. In some embodiments, the sheath element is configured to protect the heating element in the intermediate space. In some embodiments, the sheath element is configured to support and fix the position of the heat distribution element vertically. In some embodiments, the sheath element is configured to support and fix the position of the heat distribution element horizontally as well.

[0029] In some embodiments, the at least one heat distribution element has at least one opening or hole for at least partially inserting the at least one heating element therein. In some embodiments, a heat distribution element has multiple openings or holes for at least partially inserting multiple heating elements therein. In some embodiments, the openings or holes are configured to allow at least partially inserting both the heating element and the sheath element. In some embodiments, the at least one opening or hole is configured to penetrate one narrow end of the heat distribution element. In some embodiments, the at least one opening or hole of one of the narrow ends of the heat distribution element is configured to penetrate the entire heat distribution element and is configured to penetrate two narrow ends of the heat distribution element. In some embodiments, the phrase narrow end of the heat distribution element refers to a narrow end of the heat distribution element that is not a flat, panel-like surface.

[0030] In some embodiments, two adjacent heat distribution elements are bonded and / or in thermal contact with each other through face-to-face contact of their respective narrow ends.

[0031] In some embodiments, two adjacent heat distribution elements have at least one tube or duct with said opening or hole at at least one (preferably two) of their narrow ends. In some embodiments, two adjacent heat distribution elements each have at least one tube or duct at different heights. By having tubes or ducts at different heights, they can overlap, and thus the two adjacent heat distribution elements can overlap. In some embodiments, the two adjacent heat distribution elements are coupled with the at least one heating element inserted in the overlapping tubes or ducts of the two adjacent heat distribution elements. In some embodiments, the two adjacent heat distribution elements are coupled with the axial element inserted in the overlapping tubes or ducts of the two adjacent heat distribution elements and with one heating element inserted in the axial element.

[0032] In some embodiments, the at least one heat distribution element includes at least one fastener for attaching the heating element to the heat distribution element. In some embodiments, a single heat distribution element includes multiple fasteners for attaching multiple heating elements to the single heat distribution element. In some embodiments, the at least one fastener is configured to attach both the heating element and the sheath element to the heat distribution element.

[0033] In some embodiments, the at least one heating element, in its operating state, is located at least partially within any of the following: said intermediate space; said sheath element; said at least one heat distribution element; said heating element feedthroughs;

[0034] In some embodiments, the at least one heat distribution element is spaced apart from the reaction chamber in the intermediate space. The at least one heat distribution element is in direct contact or directly connected to a wall of the reaction chamber in the intermediate space. In some embodiments, the at least one heat distribution element is located near the reaction chamber so as to at least partially cover the periphery of the reaction chamber. In some embodiments, the at least one heat distribution element is arranged with its flat panel-like surface oriented vertically near the reaction chamber. In some embodiments, the at least one heat distribution element is located below the reaction chamber so as to at least partially cover a bottom or lower part of the reaction chamber. In some embodiments, the at least one heat distribution element is arranged with its flat panel-like surface oriented horizontally below the reaction chamber. In some embodiments, the at least one heat distribution element is located above the reaction chamber so as to at least partially cover a top or upper part of the reaction chamber. In some embodiments, the at least one heat distribution element is disposed above the reaction chamber with its flat panel-like surface oriented horizontally.

[0035] In some embodiments, thermal energy is transferred from the heat distribution element on a side of the reaction chamber to the one or more heat distribution elements located above or below the reaction chamber, or from the one or more heating elements coupled to or arranged in contact with the one or more heat distribution elements located above or below the reaction chamber.

[0036] In some embodiments, the at least one heat distribution element is located on a side of the reaction chamber to cover all or most of the circumference of the reaction chamber. In such embodiments, the at least one heating element feedthrough for inserting the at least one heating element is located at the bottom or top of the outer chamber. In some embodiments, the at least one heat distribution element is located above or below the reaction chamber to cover the top or bottom of the reaction chamber. In such embodiments, the at least one heating element feedthrough for inserting the at least one heating element is located on a side of the outer chamber.

[0037] In some embodiments, the device comprises at least one horizontally arranged reflector below the reaction chamber in the intermediate space, covering at least a portion of the bottom of the reaction chamber. In some embodiments, the device comprises at least one horizontally arranged reflector above the reaction chamber in the intermediate space, covering at least a portion of the top of the reaction chamber. The at least one horizontally arranged reflector is configured to reflect thermal radiation, thermal convection, or thermal conduction, as applicable, towards the reaction chamber. In some embodiments, the device comprises a plurality of overlapping horizontally arranged reflectors above or below the reaction chamber, the reflectors forming a layer of a plurality of horizontally arranged reflectors. In some embodiments, one layer of horizontally arranged reflectors is composed of a plurality of horizontally arranged reflector units. In some embodiments, all of the plurality of horizontally arranged reflectors are located in the intermediate space between the reaction chamber and the outer chamber.

[0038] In some embodiments, the apparatus comprises at least one vertically oriented reflector at least partially surrounding the reaction chamber. In some embodiments, the apparatus comprises a plurality of vertically oriented reflectors at least partially surrounding the reaction chamber. In some embodiments, the vertically oriented reflectors overlap to form one or more layers of vertically oriented reflectors. In some embodiments, one layer of vertically oriented reflectors is composed of a plurality of vertically oriented reflector units. In some embodiments, all of the vertically oriented reflectors are located in the intermediate space between the reaction chamber and the outer chamber.

[0039] In some embodiments, the reflector is configured to reflect heat towards the area of ​​the reaction chamber that is to be heated and to prevent the heat from affecting other elements of the apparatus that are located outside the space bounded by the reflector.

[0040] In some embodiments, the at least one heating element is inserted through an opening or hole in the at least one horizontally arranged reflector. The at least one heating element is inserted through an opening or hole in a plurality of the horizontally arranged reflectors that are stacked one on top of the other. In some embodiments, the heating element is covered by the sheath element beyond the point of penetration through the at least one horizontally arranged reflector in the intermediate space. In some embodiments, the at least one heating element is inserted through an opening or hole in the at least one vertically arranged reflector. The at least one heating element is inserted through an opening or hole in a plurality of the vertically arranged reflectors that are stacked one on top of the other. In some embodiments, the heating element is covered by the sheath element beyond the point of penetration through the at least one vertically arranged reflector in the intermediate space.

[0041] In some embodiments, the at least one heating element is configured to heat all the heat distribution elements simultaneously present in the intermediate space to at least 30° C. In some embodiments, all the heating elements simultaneously present in the intermediate space are configured to cooperate with other heaters to heat all the heat distribution elements simultaneously present in the intermediate space to at least 30° C. In some embodiments, all the heating elements simultaneously present in the intermediate space are configured to cooperate with other optional heaters to heat the reaction chamber with the interior space to at least 30° C. In some embodiments, at least 80° C., or 120° C., or 200° C., or 500° C. In some embodiments, all the heating elements simultaneously present in the intermediate space are configured to cooperate with other optional heaters to heat the reaction chamber with the interior space to 150° C.-300° C.

[0042] In some embodiments, the type of heating element can vary according to the needs of a particular type of heater. In some embodiments, the heating element is a radiant heater. In some embodiments, the heating element is a convection heater. In some embodiments, the heating element is a conduction heater. In some embodiments, the heating element is an infrared (IR) heater.

[0043] In some embodiments, the at least one heat distribution element has a surface structure optimized for thermal radiation towards the reaction chamber.

[0044] In some embodiments, the at least one heat distribution element has a different surface structure on a side facing the reaction chamber than on a side facing the exterior chamber to optimize desired heat radiation and / or heat convection and / or heat conduction.

[0045] In some embodiments, the surface of the heat distribution element facing the reaction chamber is uneven, bumpy, or rough. In some embodiments, the surface of the heat distribution element facing the reaction chamber has good thermal emissivity. In some embodiments, the surface of the heat distribution element facing the reaction chamber is coated with a material that has good thermal emissivity. In some embodiments, the thickness of the coating on the surface of the heat distribution element facing the reaction chamber is optimized to maximize thermal radiation. The surface of the heat distribution element facing the exterior chamber is smooth, flat, polished, or wrinkle-free. In some embodiments, the surface of the heat distribution element facing the exterior chamber has low thermal emissivity. In some embodiments, the surface of the heat distribution element facing the exterior chamber is coated with a material that has low thermal emissivity. In some embodiments, the thickness of the coating on the surface of the heat distribution element facing the exterior chamber is optimized to minimize thermal radiation.

[0046] In some embodiments, the at least one vertically oriented reflector has a material and surface structure optimized for reflecting thermal radiation or thermal convection or thermal conduction towards the reaction chamber, and in some embodiments, the at least one horizontally oriented reflector has a material and surface structure optimized for reflecting thermal radiation or thermal convection or thermal conduction towards the reaction chamber.

[0047] According to a second exemplary aspect of the present invention, there is provided a method, comprising the steps of: providing an outer chamber at least partially surrounding a reaction chamber of a substrate processing apparatus and defining an intermediate space between the reaction chamber and an outer chamber; passing at least a portion of at least one heating element through a heating element feedthrough in the outer chamber and into the intermediate space; coupling at least one heat distribution element to the at least one heating element within the intermediate space; Includes.

[0048] In some embodiments, the method includes removably coupling the at least one heating element to the at least one heat distribution element.

[0049] In some embodiments, the method includes removably disposing the at least one heating element at least partially within the intermediate space between the outer chamber and the reaction chamber through the heating element feedthrough within the outer chamber.

[0050] In some embodiments, the method includes heating the reaction chamber to a uniform temperature with heat distributed by the at least one heat distribution element.

[0051] In some embodiments, the method for processing a substrate includes processing at least one substrate having a metal oxide by atomic layer deposition (ALD) in the reaction chamber and selecting an atomic layer deposition thickness for the at least one substrate, in some embodiments, the metal oxide is selected from Al2O3, Si3N4, SiO2, and the selected thickness is 5-15 nm, preferably 10 nm.

[0052] Although various perspectives and embodiments have been presented, they are not presented to limit the scope of the invention. The above-mentioned embodiments are merely used to illustrate certain aspects and steps that may be used in implementing the present invention. Some embodiments may be presented only with reference to certain exemplary aspects. It should be understood that some embodiments are applicable to other embodiments. In particular, the embodiments described in relation to the first perspective are also applicable to other perspectives. The above embodiments can be combined as appropriate. [Brief description of the drawings]

[0053] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic cross-sectional view of a portion of a substrate processing apparatus according to an embodiment. [Diagram 2] 1 is a perspective view of a portion of an apparatus according to an embodiment. [Diagram 3] 1 shows two perspective views of a portion of a device according to an embodiment. [Figure 4] 2 is a schematic cross-sectional view of a portion of a substrate processing apparatus in greater detail according to an embodiment; [Diagram 5] 2 is another more detailed schematic cross-sectional view of a portion of a substrate processing apparatus according to an embodiment; Detailed explanation

[0054] In the following description, an atomic layer deposition (ALD) technique and an atomic layer etching (ALE) technique are used as an example.

[0055] The basics of ALD growth mechanisms are known to those skilled in the art. ALD is a specialized chemical deposition method based on the sequential introduction of at least two reactive precursor species to at least one substrate. A basic ALD deposition cycle consists of four sequential steps: Pulse A, Purge A, Pulse B, and Purge B. Pulse A consists of a first precursor vapor, and Pulse B consists of another precursor vapor. Inert gases and vacuum pumps are used in Purge A and Purge B to purge (remove) gaseous reaction by-products and residual reactant molecules from the reaction space. A deposition sequence consists of at least one deposition cycle. The deposition sequence is organized such that the deposition cycles are repeated until a thin film or coating of the desired thickness is produced. The deposition cycles can be simple or more complex. For example, a deposition cycle can include three or more reactant vapor pulses separated by purge steps. Also, some of the purge steps can be omitted. In plasma-assisted ALD, such as PEALD (Plasma-Enhanced Atomic Layer Deposition) or Photon-Assisted ALD (Photon-Assisted ALD), one or more deposition steps are assisted by providing additional energy for surface reactions through the supply of plasma. Alternatively, one or more reactive precursors can be replaced by energy (e.g. simply light), leading to single precursor ALD processes. Pulse and purge sequences can therefore vary depending on the individual case. These deposition cycles form a timed deposition sequence controlled by a logic unit or microprocessor. Thin films grown by ALD are dense, pinhole-free and of uniform thickness.

[0056] In the context of substrate processing, at least one substrate is typically exposed to multiple, time-separated pulses of precursors in a reactor (or reaction chamber), whereby material is deposited on the substrate surface in a succession of self-saturating surface reactions. In the context of this application, the term ALD is intended to include all applicable ALD-based techniques, as well as any equivalent or closely related techniques, such as the following ALD subtypes: MLD (Molecular Layer Deposition), Plasma-Assisted ALD, e.g. PEALD (Plasma Enhanced Atomic Layer Deposition), Photon-Assisted ALD, also known as Flash Enhanced ALD or photon-enhanced ALD.

[0057] However, the present invention is not limited to ALD techniques, and may be used in a wide variety of substrate processing equipment, including chemical deposition equipment, such as chemical vapor deposition (CVD) reactors, and chemical etching equipment, such as atomic layer etching (ALE) reactors.

[0058] The basics of the ALE etching mechanism are known to those skilled in the art. In ALE, a material layer is removed from a surface using successive self-limiting reaction steps. A typical ALE etching cycle includes a modification step that forms a reaction layer and a removal step that removes only the reaction layer. The removal step uses plasma species (particularly ions) for layer removal. In the context of ALD and ALE techniques, self-saturating surface reaction means that the surface reaction in the surface reaction layer stops and self-saturates when the surface reaction fields are completely exhausted.

[0059] FIG. 1 is a schematic cross-sectional view of a portion of a substrate processing apparatus 10 according to an embodiment. The apparatus 10 is, for example, a substrate processing apparatus or reactor suitable for performing plasma ALD and / or UV-ALD deposition reactions and / or ALE etching reactions. In some embodiments, the apparatus 10 comprises a reaction chamber 11 in which at least one substrate is processed. An outer chamber 15 is provided around at least a portion of the reaction chamber 11. In some embodiments, the outer chamber 15 completely surrounds the reaction chamber 11. In some embodiments, only a portion of the reaction chamber 11 is enclosed within the outer chamber 15. An intermediate space 40 is defined between a wall of the outer chamber 15 and the reaction chamber 11. In some embodiments, the outer chamber 15 is configured to provide specific gas composition and pressure conditions in the intermediate space 40. These conditions are different from the conditions inside the reaction chamber and the conditions outside the outer chamber 15. For example, the gas composition and pressure conditions in the intermediate space 40 are set such that leakage into the reaction chamber 11 does not affect the reaction in the reaction chamber 11. In some embodiments, the gas composition of the intermediate space 40 comprises an inert gas, such as nitrogen or argon. In some embodiments, the outer chamber 15 and the reaction chamber 11 have an openable lid structure 17 at the top. In some embodiments, the lid structure 17 comprises both the lid of the outer chamber 15 and the lid of the reaction chamber 11. Thus, the intermediate space 40 and the inner space of the reaction chamber 11 are accessible through the openable lid structure 17. In some embodiments, the lid structure 17 comprises only the lid of the outer chamber 15, and the reaction chamber 11 has a separate lid structure (not shown). In some embodiments, the device 10 comprises a reactant inlet 12. The reactant inlet 12 is configured to supply one or more reactants and / or additional energy to the reaction chamber 11. The reactant inlet 12 is provided at the upper side of the reaction chamber 11 in relation to the lid structure 17. In some embodiments, the reactant inlet 12 comprises an energy source, such as a plasma source or a radiation source.

[0060] In some embodiments, the apparatus 10 includes at least one horizontally disposed reflector 35, 36 located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the apparatus 10 includes two or more horizontally disposed reflectors 35, 36 located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. The reaction chamber 11 is supported by a base 19. The base 19 includes an exhaust port for the reaction chamber 11 (not shown). The base 19 extends through at least one horizontally disposed reflector 35, 36 located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the base 19 extends downward from the bottom of the reaction chamber 11 through the outer chamber 15. In some embodiments, the apparatus 10 includes two or more horizontally disposed reflectors 35, 36 that are layered and overlapping at the bottom of the reaction chamber 11. In that case, the base 19 extends through these overlapping horizontally arranged reflectors 35, 36. In some embodiments, the device 10 includes two or more overlapping horizontally arranged reflectors 35, 36 in layers on top of the reaction chamber 11. In some embodiments, the device 10 includes at least one vertically arranged reflector 35', 36' located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the device 10 includes two or more vertically arranged reflectors 35', 36' located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the device 10 includes at least one horizontally arranged reflector 35, 36 located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15 and at least one vertically arranged reflector 35', 36' located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the apparatus 10 comprises two or more horizontally disposed reflectors 35, 36 located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15, and two or more vertically disposed reflectors 35', 36' located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15. In some embodiments, the apparatus 10 comprises at least one curved or bent reflector 35, 36, 35', 36' located in the intermediate space 40 between the reaction chamber 11 and the outer chamber 15 to at least partially surround the reaction chamber 11.In some embodiments, the apparatus 10 includes two or more curved or bent reflectors 35 , 36 , 35 ′, 36 ′ in an intermediate space 40 between the reaction chamber 11 and the outer chamber 15 to at least partially surround the reaction chamber 11 .

[0061] The reflectors 35, 36, 35', 36' are configured to reflect heat radiation, heat convection, or heat conduction, as applicable, emitted from the at least one heating element 30 and the at least one heat distribution element 20 into the reaction chamber 11 and away from the outer chamber 15 and other parts of the apparatus located behind the outer surface of the reflectors 35, 36, 35', 36'. The reflectors 35, 36, 35', 36' may each be composed of multiple reflector units. Each unit forms a single layer of reflector oriented horizontally, vertically, or both. The apparatus may further comprise another reflector on top of the reflectors 35, 36, 35', 36'.

[0062] The apparatus 10 includes at least one heating element 30 that provides heat within the apparatus 10. The at least one heating element 30 may be, for example, a cartridge heater that is set in a suitable location within the apparatus 10 and is removable and replaceable. The cartridge heater may be a tubular heating element or a heating element customized to a specific watt density depending on the intended application. For example, one cartridge heater may be designed to reach a watt density of 50 W / cm2, while another cartridge heater may be designed to reach a watt density of 100 W / cm2. The replaceability of the heating element 30 is useful when a heating element needs to be replaced with a new one, for example, due to surface oxidation. In some embodiments, the apparatus 10 includes two or more heating elements 30. The number of heating elements 30 is set according to the design of the apparatus 10 to provide adequate heat for the surface reaction in the reaction chamber. The at least one heating element 30 is preferably a rod-shaped element. The horizontal cross section of the heating element 30 when the heating element 30 is placed vertically along its long axis may have rotational symmetry or may be round. In some embodiments, the horizontal cross-section of the heating element 30 when oriented vertically along its long axis may be rotationally asymmetric, e.g., elliptical, rectangular, square, etc. In any event, at least one heating element 30 is a slim rod- or cane-like component, the thickness and shape of which are adjusted for ease of use, heat carrying capacity, and user safety.

[0063] At least one heating element 30, in its operative state, is at least partially located in an intermediate space 40 between the reaction chamber 11 and the outer chamber 15. The operative state of at least one heating element 30 means that the heating element 30 is operable in the substrate processing apparatus 10, i.e. capable of delivering heat according to its intended use. When in an operative state, a part of the heating element 30 may be located outside the outer chamber 15. Each heating element 30 is inserted into the intermediate space 40 and put into operative state through a corresponding heating element feedthrough 37, located at the bottom of the outer chamber 15. However, in alternative embodiments, the heating element feedthrough or feedthroughs 37 may be located at the side or at the top of the outer chamber 15. In some embodiments, the at least one heating element feedthrough 37 serves to provide support and fix the position of the heating element or elements 30 and / or the heat distribution element or elements 20. The heating element feedthrough 37 is preferably secured by a seal 38, as shown in Figs. 4 and 5. Thereby, environmental pressure conditions are prevented from affecting the conditions in the outer chamber 15 when the heating element 30 is in an operative state. The seal 38 sealing the heating element feedthrough 37 may, for example, comprise a cover plate or cover liner on the outside of the outer chamber 15 for sealing the inlet of the heating element 30. In some embodiments, the seal 38 is a vacuum flange sealing the inlet of the heating element 30 to the outer chamber 15. In some embodiments, the at least one heating element 30 in its operative state is entirely located within an intermediate space 40 formed between the reaction chamber 11 and the outer chamber 15. In such an embodiment, the heating element 30 is inserted in its operative state within the intermediate space 40 through the heating element feedthrough 37, and the heating element 30 is indirectly coupled to the heating element feedthrough 37 (e.g., via a wire). Such indirect coupling of the heating element 30 reduces the risk of overheating the feedthrough 37 and also reduces the risk of overheating of structures in contact with the feedthrough 37. In such embodiments, other means for supporting one or more heating elements 30 and / or one or more heat distribution elements 20 in their correct operating condition may be provided within the outer chamber 15 in place of (or in addition to) the heating element feedthrough 37.

[0064] In some embodiments, the at least one heating element 30, in its operating state, extends through at least one horizontally arranged reflector 35, 36 located in the intermediate space 40 at the top or bottom of the reaction chamber 11. The at least one horizontally arranged reflector 35, 36 is provided with one or more openings for the at least one heating element 30 to pass therethrough in a removable and / or removable manner. In some embodiments, the device 10 comprises two or more overlapping horizontally arranged reflectors 35, 36 in layers at the bottom of the reaction chamber 11. In that case, the at least one heating element 30 extends through these overlapping horizontally arranged reflectors 35, 36. In some embodiments, the at least one heating element 30 extends through at least one vertically arranged reflector 35', 36' located in the intermediate space 40 of the reaction chamber 11. At least one of the vertically-disposed reflectors 35', 36' is provided with one or more openings for removably and / or removable passage of at least one heating element 30 therethrough. In some embodiments, the apparatus 10 includes two or more layered, overlapping, vertically-disposed reflectors 35', 36' in the reaction chamber 11, where the at least one heating element 30 extends through the overlapping vertically-disposed reflectors 35', 36'.

[0065] In its operating state in the intermediate space 40, at least one heating element 30 is associated with at least one heat distribution element 20. In some embodiments, each individual heat distribution element 20 in the intermediate space 40 is associated with at least one heating element 30. In some embodiments, each individual heat distribution element 20 in the intermediate space 40 is associated with two or more heating elements 30. In some embodiments, a heat distribution element 20 in the intermediate space 40 is associated with at least one other heat distribution element 20 that is associated with at least one heating element 30. The at least one heat distribution element 20 picks up the heat radiated from the at least one heating element 30 and distributes it generally equally to the outer edge of the reaction chamber 11, thereby providing the heat required for the surface reaction occurring in the reaction chamber 11. Preferably, the material of the one or more heat distribution elements 20 has good thermal conductivity. For example, the material of the one or more heat distribution elements 20 is aluminum. In some embodiments, one or more heat distribution elements may be made, at least in part, of (or include) copper, brass, titanium, steel, ceramics, nitrides, or carbides.

[0066] In some embodiments, the surface(s) of the heat distribution element(s) 20 facing the reaction chamber 11 has a larger total surface area than the surface(s) facing the exterior chamber 15. In some embodiments, the total surface area of ​​the surface(s) of the heat distribution element(s) 20 facing the reaction chamber 11 is more than 1.5 times, preferably more than 2 times, more preferably more than 4 times the surface area of ​​the surface(s) facing the exterior chamber 15. The surface(s) of the heat distribution element(s) 20 facing the reaction chamber 11 has a high electro magnetic thermal emissivity. The surface(s) of the heat distribution element(s) 20 facing the reaction chamber 11 is coated with a material having a high electro magnetic thermal emissivity. For example, the surface(s) of the heat distribution element(s) 20 facing the reaction chamber 11 has a coating including a nitride (e.g., silicon nitride) or a carbide (e.g., tungsten carbide). In some embodiments, the thickness of these coatings is optimized to maximize thermal radiation. On the other hand, the surface of the heat distribution element(s) 20 facing the exterior chamber 15 is smooth, possibly polished, and wrinkle-free. The material of said surface has a low thermal emissivity. The surface of the heat distribution element(s) 20 facing the exterior chamber 15 is coated with a material having a low thermal emissivity. In some embodiments, the thickness of this coating is optimized to minimize thermal radiation. For example, the material of the surface of the heat distribution element(s) 20 facing the exterior chamber 15 or the coating material of said surface can be, for example, copper, gold, silver, brass, nickel, steel.

[0067] In some embodiments, the at least one heat distribution element 20 is curved, bent or arched in shape, a flat panel-like object, and is preferably configured to be placed at least partially around the reaction chamber 11. The at least one heat distribution element 20 has openings or holes 28 in its structure, which allow the heating element 30 to be located at least partially inside the heat distribution element 20. The openings or holes 28 are formed, for example, as tubes or ducts. For example, as shown in the embodiment of FIG. 2, the heating element 30 can be located in the tube or duct. In the example of FIG. 2, the tube or duct is a short connecting cylinder 25, which is provided at the narrow ends 21, 21', 22, 22' of the heat distribution element 20. Two adjacent heat distribution elements 20 each have a short connecting cylinder 25 at different positions of the narrow ends 21, 21', 22, 22'. Thus, when these two heat distribution elements 20 are placed next to each other, their respective short connecting cylinders 25 are adjacent, e.g., one above the other. This configuration makes it possible to insert a heating element 30 at a position within each of the short connecting cylinders 25 of the two adjacent heat distribution elements 20.

[0068] Other types of solutions for placing the heating element 30 in the heat distribution element or elements 20 may be used. Alternatively, as shown in FIG. 3, the openings or holes 28 may be ducts that pass completely or partially through the body of the heat distribution element 20, and the heating element 30 may be set inside such openings or holes 28. The openings or holes are arranged to pass through the narrow ends 21, 21', 22, 22' of the heat distribution element 20, and are arranged like conduits that pass completely or partially through the heat distribution element 20. In some embodiments, the openings or holes 28 only pass partially through the heat distribution element 20, and at the narrow end opposite the openings or holes 28, air openings 26 are arranged. The air openings 26 are connected to the cavity of the openings or holes 28, so that a vacuum can be provided during the operation of the device. In some embodiments, when the air openings 26 are connected to the cavity of the openings or holes 28, the diameter of the air openings 26 is smaller than the diameter of the holes 28. This is to prevent the heating element 30 from penetrating completely through the heat distribution element 20. In some embodiments, the lower narrow end 21, 21', 22, 22' of the heat distribution element 20 has at least one hole 28 for receiving the heating element 30. Thus, at least a part of the weight of the heat distribution element 20 rests on the heating element 30 that is at least partially inserted in the heat distribution element 20. In another alternative embodiment, one of the narrow ends 21, 21', 22, 22' of the heat distribution element 20 has at least one opening or hole 28 that passes completely through the face related to that narrow end for the insertion of the heating element 30. In such an embodiment, the weight of the at least one heat distribution element 20 is supported in a different way.

[0069] In some embodiments, the at least one heat distribution element 20 includes at least one fastener (not shown) for attaching one or more heating elements 30 to the heat distribution element 20. In such embodiments, the one or more heating elements 30 do not need to be set within the heat distribution element 20. Thus, the configuration of the heat distribution element 20 is configured to couple the at least one heating element 30 to the heat distribution element 20.

[0070] For example, at least one heat distribution element 20 may have a support structure in narrow end 21, 21', 22, 22' or on its panel-like surface 23 for coupling at least one heating element 30. Such a support structure may be of a hoop structure, such as a ring (not shown).

[0071] In some embodiments, a single heat distribution element 20 is provided with multiple openings or holes 28 for coupling multiple heating elements 30. In some embodiments, a single heating element 30 may be coupled to one heat distribution element 20 or to two heat distribution elements 20 simultaneously, depending on the design of the heat distribution element or elements 20.

[0072] In a preferred embodiment, the apparatus includes two or more heating elements 30 that are equally spaced around the circumference of the reaction chamber 11 to provide uniform heating of the reaction chamber. For example, the apparatus includes two heating elements 30, preferably includes three heating elements 30, and more preferably includes four heating elements 30. In some embodiments, the apparatus includes four or more heating elements 30.

[0073] In some embodiments, the apparatus 10 comprises a plurality of heat distribution elements 20 coupled to each other, each heat distribution element 20 coupled to at least one heating element 30, and these heat distribution elements 20 surround most or all of the periphery of the reaction chamber 11 within the intermediate space 40. In some embodiments, the apparatus 10 comprises a plurality of heat distribution elements 20 coupled to each other, each heat distribution element 20 coupled to at least one heating element 30, and these heat distribution elements 20 cover the top and / or bottom of the reaction chamber 11 within the intermediate space 40. In some embodiments, the apparatus 10 comprises a plurality of heat distribution elements 20 coupled to each other, each heat distribution element 20 coupled to at least one heating element 30, and these heat distribution elements 20 surround most or all of the periphery of the reaction chamber 11 and the top and / or bottom of the reaction chamber 11 within the intermediate space 40. In some embodiments, the heat distribution element 20 connects to a second heat distribution element 20 through a heating element 30. Such heating elements 30 keep the assembly of parts together. In some embodiments, the apparatus 10 includes a plurality of heat distribution elements 20 coupled together, each heat distribution element 20 connected to the other by at least one heating element 30, and these heat distribution elements 20 surround most or all of the circumference of the reaction chamber 11 within the intermediate space 40. Each heat distribution element 20 may have a shape, for example, a quarter of a cylinder, a cylindrical or arcuate quadrant, and four such heat distribution elements 20 may gather together to surround the circumference of the reaction chamber 11. The shape and number of heat distribution elements 20 to surround most or all of the circumference of the reaction chamber 11 may vary from embodiment to embodiment. In some embodiments, the apparatus 10 includes only one completely cylindrical heat distribution element 20, which heat distribution element 20 surrounds the circumference of the reaction chamber 11 within the intermediate space 40. In some embodiments, most or all of the circumference of the reaction chamber 11 is surrounded by one or more heat distribution elements 20 within the intermediate space 40. In some embodiments, substantially the entire reaction chamber 11 is enveloped (or enclosed) within the intermediate space 40 by the one or more heat distribution elements 20. The one or more heat distribution elements 20 can be installed or removed from the apparatus 10 through the openable lid assembly 17 without having to first remove the one or more heating elements 30.

[0074] In some embodiments, as depicted in Figures 4 and 5, the device comprises a sheath element 45 between the heating element 30 and the at least one heat distribution element 20. The sheath element 45 transfers heat from the heating element 30 to the one or more heat distribution elements 20 and protects the heating element 30 by covering it. In some embodiments, the sheath element 45 also provides support for the at least one heat distribution element 20. In some embodiments, the heat distribution element 20 connects to the second heat distribution element 20 through the sheath element 45. Such a sheath element 45 helps to keep the assembly of parts together. In some embodiments, the sheath element 45 protects the heating element 30 from oxidation. In some embodiments, the sheath element 45 prevents the at least one heating element 30 from being exposed to the conditions prevailing in the intermediate space 40. Preferably, the material of the sheath element 45 has good thermal conductivity. For example, the material of the sheath element 45 is aluminum. The sheath element 45 has the shape of an elongated sheath and has an inner cavity configured to tightly fit the outer surface of the heating element 30. The heating element 30 is removably set at least partially in the lumen of the elongated sheath element 45 through an opening at a first end of the sheath element 45. In some embodiments, the second end of the sheath element 45 is closed, forming a closed cap on top of the end of the heating element 30, as shown in the embodiment of FIG. 4. In some embodiments, the second end of the sheath element 45 is not closed and may be open to the lumen of the sheath element 45, as shown in the embodiment of FIG. 5. In some embodiments, the entire heating element 30 is covered by the sheath element 45 in the intermediate space 40. In some embodiments, each heating element 30 is covered by the sheath element 45 in the intermediate space 40 beyond the point where it penetrates the heating element feedthrough 37. In some embodiments, only the ends of the heating elements 30 are exposed to the conditions prevailing in the intermediate space 40. As shown in FIG. 5, the sheath element 45 together with the seal 38 tightly seals between the heating element feedthrough 37 and the heating element 30. The sheath element 45 may be coupled to the seal 38 at the interior of the heating element feedthrough 37 or at the entrance to the intermediate space 40. In some embodiments, the seal 38 is a flange, for example a vacuum flange. The seal 38 may include an O-ring that seals the connection between the sheath element 45 and the seal 38.In some embodiments, the entire sheath element 45 may be located within the space bounded by the layers of vertical reflectors 35', 36' located at the top and bottom of the reaction chamber 11. In such embodiments, a portion of the heating element 30 is exposed to the conditions prevailing in the intermediate space 40. In some embodiments, the entire sheath element 45 may be located within the space bounded by the layers of horizontal reflectors 35', 36' located at the top and bottom of the reaction chamber 11.

[0075] In some embodiments, the heating element 30, such as a cartridge heater, is in a vacuum and may be at least partially tightly inserted into the sheath element 45. In such embodiments, the sheath element 45 provides electrical insulation to the lumen. In some embodiments, the electrical contacts of the heating element 30 are provided outside the intermediate space 40 (not shown). Thus, such electrical contacts (electrical cables) are not exposed to the vacuum. In some embodiments, the sheath element 45, which at least partially covers the heating element 30, may be firmly fixed onto a seal 38, such as a vacuum flange, thereby preventing the electrical contacts of the heating element 30 from being exposed to the vacuum. In some embodiments, the portion of the heating element 30 coupled to the at least one heat distribution element 20 is configured to reach a higher temperature than the portion of the heating element 30 located outside the outer chamber 15. Thus, a person handling the at least one heating element 30 can manually hold the portion of the heating element 30 located outside the outer chamber 15 when inserting or removing it.

[0076] In some embodiments, the sheath element 45 may have a surface structure configured to support and secure a portion of the at least one heat distribution element 20. Such portion may be fixed vertically, horizontally, or vertically and horizontally. More specifically, as depicted in FIG. 4, the outer surface of the sheath element 45 may have a protrusion or bulge on which the weight of the at least one heat distribution element 20 may be supported. For example, the sheath element 45 has a protrusion or bulge at the outer end of its distal end. The heating element 30 is removably disposed in the lumen of the sheath element 45 at least partially through the distal end.

[0077] Thus, in some embodiments, when the heating element 30 is fully inserted vertically inside the sheath element 45, as it is in operation, the lower edge of the at least one heat distribution element 20 is supported on said protrusion of the sheath element 45. In alternative embodiments, said protrusion or bulge of the sheath element 45 may be located anywhere along the axial direction of the sheath element 45. In some embodiments, the support structure of the at least one heat distribution element 20 is provided by a different structural solution than the sheath element 45 and / or said parts of the at least one heat distribution element 20. For example, in embodiments where the heating element 30 is inserted vertically into the intermediate space 40 through the lid structure 17, a different assembly method is used for the heating element 30, the sheath element 45 and the heat distribution element 20.

[0078] The technical effects of one or more embodiments disclosed herein are as follows, but are not intended to limit the scope and interpretation of the claimed invention. One of the technical effects is to facilitate the removal and replacement of the heating element. For example, if the heating element has to be replaced with a new one due to oxidation of its surface, the old heating element can be easily removed and replaced with the new heating element. Another technical effect is to facilitate the removal and replacement of one or more heat distribution elements. The one or more heat distribution elements can be easily removed through the retractable lid of the device. Another technical effect is that the surface of the heat distribution element facing the reaction chamber is configured to radiate heat energy differently compared to the heat reflecting element and the surface facing the outer chamber. Another technical effect is to prevent the one or more heating elements from coming into contact with the conditions prevailing in the intermediate space, thereby preventing the surface of the heating element from being oxidized. Another technical effect is to prevent the electrical components of the one or more heating elements from coming into contact with the vacuum conditions prevailing in the intermediate space. Another technical effect is to connect one or more heat distribution elements, indirectly or directly, to one or more heating elements, thereby allowing for uniform distribution of thermal energy around the reaction chamber periphery or within the reaction chamber.

[0079] The above description provides a complete and informative description of the best mode for carrying out the invention currently contemplated by the inventors, using non-limiting examples of specific implementations and embodiments of the invention. However, as will be apparent to those skilled in the art, the details of the above-described embodiments do not limit the invention, and may be implemented in other embodiments using equivalent means without departing from the features of the invention. Moreover, features of the embodiments of the invention disclosed above may be used without corresponding other features. Thus, the above description should be taken as merely illustrative of the principles of the invention, and not as limiting thereof. The scope of the invention is limited only by the appended claims.

Claims

1. 1. A heat distribution element for a substrate processing apparatus, the heat distribution element having a curved panel-like structure and comprising: two opposing panel-like surfaces, at least one of which is configured to distribute heat; a narrow edge connecting the two opposing panel-like faces; at least one opening in at least one of said narrow ends; the opening at least partially extends through the heat distribution element and is configured to have at least a portion of a heating element disposed therein.

2. The heat distribution element of claim 1 , wherein the heat distribution element is configured to removably position the heating element at least partially within the opening.

3. The heat distribution element of claim 1 or 2, wherein the heat distribution element is configured to be a removable and replaceable heat distribution element in the substrate processing apparatus.

4. The heat distribution element of claim 1 or 2, wherein the openings extend at least partially through the heat distribution element.

5. 5. The heat distribution element of claim 4, further comprising an air opening at a narrow end opposite said opening, said air opening communicating with said opening.

6. The heat distribution element of claim 5 , wherein the air openings are configured to be smaller than the openings to prevent the heating element from penetrating the heat distribution element.

7. The heat distribution element of claim 1 or 2, wherein the openings extend completely through the heat distribution element.

8. The heat distribution element of claim 1 or 2, comprising a plurality of openings.

9. 3. A heat distribution element according to claim 1 or 2, wherein the two panel-like faces have different total areas, one being 1.5 times, 2 times or 4 times the area of ​​the other.

10. The heat distribution element according to claim 1 or 2, wherein the material of the heat distribution element is selected from the group consisting of aluminum, copper, brass, titanium, steel, ceramics, and silicon nitride.

11. The heat distribution element of claim 1 or 2, wherein at least one of the two panel-like surfaces is configured to have a high electromagnetic heat emissivity or a low electromagnetic heat emissivity.

12. 3. A heat distribution element as described in claim 1 or 2, wherein at least one of the two panel-like faces is coated with a material having a high electromagnetic heat emissivity, the material may be selected from a nitride such as silicon nitride or a carbide such as tungsten carbide.

13. 3. The heat distribution element of claim 1 or 2, wherein at least one of the two panel-like surfaces is coated with a material having low electromagnetic heat emissivity, the material may be selected from copper, gold, silver, brass, nickel, steel.

14. The heat distribution element of claim 1 or 2, wherein the curved panel-like structure is formed in the shape of a quarter cylinder, an arcuate shape, or a cylindrical shape.

15. 3. The heat distribution element of claim 1 or 2, comprising at least one fastener attaching the heating element to the heat distribution element.

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