TWM586870U - Mid-filament spacer - Google Patents

Abstract

A mid-filament spacer or heating subsystem with mid-filament spacers as described herein prevents undesirable electrical coupling between portions of a heating coil.

Description

Heating wire intermediary spacer

This work is generally about semiconductor manufacturing technology, and more specifically, about chemical vapor deposition (CVD) processing and associated equipment used to hold semiconductor wafers during processing.

In the manufacture of light-emitting diodes (LEDs) and other high-performance devices such as laser diodes, optical detectors and field-effect transistors, chemical vapor deposition (CVD) processes and materials such as gallium nitride A thin film stack is grown on a sapphire or silicon substrate. The CVD tool includes a processing chamber, which is a sealed environment that allows the injected gas to react on a substrate (typically in the form of a wafer) to grow a thin film layer. An example of the current product line for such manufacturing equipment is the TurboDisc®, EPIK®, and PROPEL® series of metal organic chemical vapor deposition (MOCVD) manufactured by Veeco Instruments Inc. of Plainview, New York. system.

To achieve the desired crystal growth, various process parameters such as temperature, pressure, and gas flow rate are controlled. Different layers are grown using different materials and process parameters. For example, a device formed of a compound semiconductor such as a III-V semiconductor is generally formed by growing a continuous layer of a compound semiconductor using MOCVD. During this process, the wafer is exposed to a combination of gases, typically including metal organic compounds as a source of Group III metals, and including when the wafer is maintained at high temperatures. Source of Group V elements flowing on the surface of the wafer at the same time. In general, metal organic compounds and Group V sources are combined with a carrier gas (such as nitrogen) that is significantly less involved in the reaction. An example of a III-V semiconductor is gallium nitride, which can be formed by reacting an organic gallium compound and ammonia on a substrate having an appropriate lattice spacing. An example of the substrate is a sapphire wafer. During the deposition of gallium nitride and related compounds, the wafer is typically maintained at a temperature of about 1000-1100 ° C.

In the MOCVD process, when crystal growth occurs by chemical reaction on the surface of the substrate, special attention must be paid to process parameter control to ensure that the chemical reaction proceeds under the required conditions. Even small changes in process conditions may adversely affect device quality and manufacturing yield. For example, if an indium gallium nitride layer is deposited, changes in the surface temperature of the wafer will cause changes in the composition and band gap of the deposited layer. Because indium has a relatively high vapor pressure, the deposited layer will have a lower proportion of indium and a larger band gap in those regions where the surface temperature in the wafer is higher. If the deposited layer is an active light emitting layer of an LED structure, the radiation wavelength of the LED formed by the wafer will also change to an unacceptable degree.

In a MOCVD processing chamber, a semiconductor wafer on which a thin film layer is to be grown is placed on a fast-rotating rotary conveyor (called a wafer carrier) so that its surface is uniformly exposed to the atmosphere in the reaction chamber for semiconductor material deposition. The rotation speed is approximately 1,000 RPM. As the wafer carrier rotates, the gas is directed down onto the top surface of the wafer carrier and flows toward the outer periphery of the wafer carrier over the entire top surface. The used gas is evacuated from the reaction chamber through a port placed below the wafer carrier. The wafer carrier is maintained at a desired high temperature by a heating element (typically a resistive heating element) disposed below the bottom surface of the wafer carrier. These heating elements are maintained at a temperature higher than the desired temperature on the wafer surface, and the gas distribution device is generally maintained at a temperature much lower than the desired reaction temperature in order to prevent the gas from reacting prematurely. Therefore, heat is transferred from the heating element to the bottom surface of the wafer carrier and flows upward through the wafer carrier to individual wafers.

The airflow on the wafer varies depending on the radial position of each wafer, with the outermost wafer being subjected to higher flow rates due to its faster speed during rotation. Even on each individual wafer, there may be temperature inhomogeneities, that is, cold spots and hot spots. One variable that affects the formation of temperature heterogeneity is the shape of the recesses in the wafer carrier. In general, the recess shape forms a ring shape in the surface of the wafer carrier. When the wafer carrier rotates, the outermost edge of the wafer (ie, the edge furthest from the axis of rotation) is subjected to a considerable centripetal force such that the wafer is pressed against the inner wall of the corresponding recess in the wafer carrier. Under these conditions, there is close contact between these outer edges of the wafer and the edges of the recesses. The increase in heat conduction to these outermost portions of the wafer can lead to greater temperature non-uniformity, further exacerbating the problems described above. Efforts have been made to minimize temperature non-uniformity by increasing the gap between the wafer edge and the inner wall of the recess, including wafers designed to be flat on a portion of the edge (ie, "flat" wafers). This flat portion of the wafer generates voids and reduces contact points with the inner wall of the recess, thereby alleviating temperature unevenness. Other factors that affect the uniformity of heating throughout the wafer held by the wafer carrier include the heat transfer and emissivity characteristics of the wafer carrier, and the layout of the wafer recesses.

In order to continuously and uniformly generate the desired temperature, the heater coil may be positioned below the base. The heater coil may be made of a suitable conductive material whose resistivity, cross-section, and length are set such that the coil generates substantially uniform heat at the portion of the pedestal for wafer growth. Due to the thermal expansion of the heater coil, if the coil is heated too fast, unevenly, or heated to a sufficiently high temperature, parts of the coil may contact each other. When each part of the coil contacts other parts of the coil, an arc or discharge may occur, which may damage the coil, cause some sections of the coil to be short-circuited (not heated), or otherwise damage the equipment or cause poor coil performance.

The heater coil is supported by a base having an insulating element. The arrangements described herein prevent unwanted contact between portions of the heater coil that are intended to be electrically isolated from each other.

10‧‧‧ Reaction Room

12‧‧‧Gas distribution device

14‧‧‧Processing gas supply unit

16‧‧‧Processing gas supply unit

18‧‧‧Processing gas supply unit

20‧‧‧Coolant system

22‧‧‧Exhaust system

24‧‧‧ shaft

26‧‧‧Center axis

28‧‧‧ device

30‧‧‧Joint

32‧‧‧Rotary drive mechanism

34‧‧‧Heating element

36‧‧‧ opening

38‧‧‧ Front Room

40‧‧‧ gate

40'‧‧‧Open position

42‧‧‧First Wafer Carrier

44‧‧‧Second wafer carrier

46‧‧‧Subject

48‧‧‧ top surface

52'‧‧‧ bottom surface

54‧‧‧ wafer

56‧‧‧ Recess

58‧‧‧Temperature distribution system

60‧‧‧Temperature Monitor

134‧‧‧Heating element

172‧‧‧columns

174‧‧‧ Heating wire intermediary spacer

176A‧‧‧Anode

176B‧‧‧Anode

274‧‧‧Heating wire intermediary spacer

280‧‧‧columns

282‧‧‧ flange

284‧‧‧ tenon

286‧‧‧carriage

288A‧‧‧Insulation cap

288B‧‧‧Insulation cap

374‧‧‧ Heating wire intermediary spacer

380‧‧‧column

382‧‧‧ flange

384‧‧‧ tenon

386‧‧‧carriage

388A‧‧‧Insulation cap

388B‧‧‧Insulation cap

474‧‧‧ Heating wire intermediary spacer

480‧‧‧columns

482‧‧‧ flange

484‧‧‧ tenon

486‧‧‧carriage

488‧‧‧Insulation cap

Considering the following specific implementations of various embodiments of the present invention in conjunction with the drawings, the present invention can be more fully understood. In the drawings: FIG. 1 is a schematic diagram of a MOCVD processing chamber according to the embodiment.

Fig. 2 is a plan view of a heater coil having a plurality of heating wire intermediary spacers according to an embodiment.

Fig. 3 is a detailed view of the heater coil of Fig. 2, showing the heating wire intermediary spacer in more detail.

Fig. 4 is a perspective view of a heating wire intermediary spacer according to an embodiment.

FIG. 5 is a front view of the heating wire intermediary spacer depicted in FIG. 4, and a rear view thereof is the same.

FIG. 6 is a left side view of the heating wire intermediary spacer depicted in FIG. 4, and a right side view thereof is the same. FIG.

FIG. 7 is a top view of the heating wire intermediary spacer depicted in FIG. 4.

FIG. 8 is a bottom view of the heating wire intermediary spacer depicted in FIG. 4.

FIG. 9 is a partial cross-sectional view of the heating wire intermediary spacer depicted in FIG. 4.

Fig. 10 is a perspective view of a heating wire intermediary spacer according to a second embodiment.

Fig. 11 is a front view of the heating wire intermediary spacer depicted in Fig. 10, and a rear view thereof is the same.

12 is a left side view and a right side view of the heating wire intermediary spacer depicted in FIG. 10 It's the same.

FIG. 13 is a top view of the heating wire intermediary spacer depicted in FIG. 10.

FIG. 14 is a bottom view of the heating wire intermediary spacer depicted in FIG. 10.

FIG. 15 is a partial cross-sectional view of the heating wire intermediary spacer depicted in FIG. 10.

Fig. 16 is a perspective view of a heating wire intermediary spacer according to a third embodiment.

FIG. 17 is a front view of the heating wire intermediary spacer depicted in FIG. 16, and a rear view thereof is the same.

18 is a left side view of the heating wire intermediary spacer depicted in FIG. 16, and a right side view thereof is the same.

FIG. 19 is a top view of the heating wire intermediary spacer depicted in FIG. 16.

FIG. 20 is a bottom view of the heating wire intermediary spacer depicted in FIG. 16.

FIG. 21 is a partial cross-sectional view of the heating wire intermediary spacer depicted in FIG. 16.

FIG. 1 illustrates a chemical vapor deposition apparatus according to an embodiment of the present invention. The reaction chamber 10 defines a customized environment space. The gas distribution device 12 is arranged at one end of the chamber. This end with the gas distribution device 12 is referred to herein as the "top" end of the reaction chamber 10. This end of the chamber is usually, but not necessarily, placed on top of the chamber in a normal gravity reference frame. Therefore, the downward direction as used herein refers to the direction away from the gas distribution device 12; and the upward direction refers to the direction of the room toward the gas distribution device 12, regardless of whether these directions are aligned with the upward and downward directions of gravity. Similarly, the "top" and "bottom" surfaces of the components are described herein with reference to the reference system of the reaction chamber 10 and the gas distribution device 12.

The gas distribution device 12 is connected to sources 14, 16 and 18, such as metal organic compounds, for supplying processing gases (e.g., carrier gas and reaction gas) to be used during wafer processing. And the source of Group V metals. The gas distribution device 12 is arranged to receive various gases and direct the process gas flow in a generally downward direction. The gas distribution device 12 is also desirably connected to a coolant system 20 arranged to circulate liquid through the gas distribution device 12 in order to maintain the temperature of the gas distribution device at a desired temperature during operation. A similar coolant arrangement (not shown) may be provided to cool the walls of the reaction chamber 10. The reaction chamber 10 is also equipped with an exhaust system 22 arranged to remove exhaust gas from the interior of the chamber 10 through a port (not shown) at or near the bottom of the chamber in order to allow the gas to pass through in a downward direction. The gas distribution device 12 flows continuously.

The rotating shaft 24 is arranged indoors so that the central shaft 26 of the rotating shaft 24 extends in the upward and downward directions. The rotating shaft 24 is mounted to the chamber by a conventional passing device 28 with bearings and seals (not shown), so that the shaft 24 can rotate around the central shaft 26 while being held between the shaft 24 and the wall of the reaction chamber 10 seal. The rotating shaft has an engaging portion 30 at its top end, that is, an end 30 closest to the gas distribution device 12 in the rotating shaft. As discussed further below, the bonding portion 30 is an example of a wafer carrier holding mechanism suitable for releasably bonding a wafer carrier. In the particular embodiment depicted, the joint 30 is a generally frusto-conical element that tapers toward the top end of the shaft and is capped at a flat top surface. A frustoconical element is an element having the shape of a frustum of a cone. The rotation shaft 24 is connected to a rotation driving mechanism 32, such as an electric motor driver, which is arranged to rotate the rotation shaft 24 about the central axis 26.

The joints 30 can also be any number of other configurations. For example, the shape of the end portion is a square or a rounded square, a series of columns, an oval shape, or other circular shapes having an aspect ratio other than 1: 1. Various other bonding, spline, or interlocking arrangements can be used between the rotating shaft 24 and the joint 30 to maintain the rotational joint between their components and prevent unwanted slippage. In embodiments, a bonding, spline, or interlocking arrangement may be used, as A desired amount of thermal expansion or contraction of the tube joint 30 or the shaft 24 occurs, but these devices still maintain a desired level of rotational engagement between the joint 30 and the shaft 24.

The heating element 34 is installed in the room and surrounds the rotating shaft 24 below the joint 30. The reaction chamber 10 is also provided with an entrance opening 36 leading to the front chamber 38 and a door 40 for closing and opening the entrance opening. The door 40 is only schematically depicted in FIG. 1 and is shown to be movable between a closed position shown by a solid line and an open position shown by a dashed line at 40 ′ where the door will react the chamber 10 The interior is isolated from the anterior chamber 38. The door 40 is equipped with appropriate control and actuation mechanisms for moving the door 40 between an open position and a closed position. The apparatus depicted in FIG. 1 may also include a loading mechanism (not shown) capable of moving the wafer carrier from the front chamber 38 into the chamber and engaging the wafer carrier with the rotating shaft 24 in an operating condition, and The wafer carrier can be moved from the rotation shaft 24 into the front chamber 38.

The equipment also includes a plurality of wafer carriers. In the operating conditions shown in FIG. 1, the first wafer carrier 42 is disposed in the operating position inside the reaction chamber 10, and the second wafer carrier 44 is disposed in the front chamber 38. Each wafer carrier includes a body 46 substantially in the form of a disk (see FIG. 2) having a central axis. The main body 46 is formed symmetrically about an axis. In the operating position, the axis of the wafer carrier body coincides with the central axis 26 of the rotating shaft 24. The body 46 is ideally formed of a material that does not contaminate the process and can withstand the temperatures encountered during this process. For example, a larger portion of the disc may be formed substantially or completely from materials such as graphite, silicon carbide, or other refractory materials. The body 46 generally has a planar top surface 48 and a bottom surface 52 'that extend in a manner substantially parallel to each other and substantially perpendicular to a central axis of the disc. The body 46 also has one or more wafer holding features suitable for holding a plurality of wafers.

In a typical MOCVD process, a wafer carrier 42 carrying a wafer thereon is loaded into the reaction chamber 10 from the front chamber 38 and placed in the operation position shown in FIG. 1. In this condition In this case, the top surface of the wafer faces upward toward the gas distribution device 12. The heating element 34 is actuated, and the rotation driving mechanism 32 is used to rotate the rotating shaft 24 about the axis 26, and thus rotate the wafer carrier 42 about the axis 26. Generally, the rotating shaft 24 rotates at a rotation speed of about 50-1500 rpm. The process gas supply units 14, 16 and 18 are actuated to supply gas through the gas distribution device 12. The gas is transmitted downward toward the wafer carrier 42, on the top surface 48 of the wafer carrier 42 and on the wafer 54, and downwardly around the periphery of the wafer carrier to the outlet and exhaust system 22. Therefore, the top surface of the wafer carrier and the top surface of the wafer 54 are exposed to a processing gas including a mixture of various gases supplied from various processing gas supply units. Most commonly, the processing gas at the top surface is mainly composed of a carrier gas supplied from a carrier gas supply unit 16. In a typical chemical vapor deposition process, the carrier gas may be nitrogen, so the processing gas at the top surface of the wafer carrier is mainly composed of nitrogen, and carries a certain amount of a reactive gas component.

The heating element 34 transfers heat to the bottom surface 52 ′ of the wafer carrier 42 mainly by radiant heat transfer. The heat applied to the bottom surface 52 'of the wafer carrier 42 flows upward through the body 46 of the wafer carrier to the top surface 48 of the wafer carrier. The heat transferred upward through the body is also transferred upward to the bottom surface of each wafer through the gap, and is transferred upward to the top surface of the wafer 54 through the wafer. Heat is radiated from the top surface 48 of the wafer carrier 42 and the top surface of the wafer to the cooler elements of the processing chamber, for example, to the walls of the processing chamber and the gas distribution device 12. Heat is also transferred from the top surface 48 of the wafer carrier 42 and the top surface of the wafer to the processing gas transferred on these surfaces.

In the depicted embodiment, the system includes several features designed to evaluate the heating uniformity of the surface of each wafer 54. In this embodiment, the temperature distribution system 58 receives temperature information from the temperature monitor 60 that can include temperature and temperature monitoring location information. In addition, the temperature distribution system 58 receives wafer carrier position information, which in one embodiment may come from the rotary drive mechanism 32. Based on this information, the temperature analysis system 58 constructs the wafer carrier 42 Temperature curve of the recessed portion 56. This temperature curve represents the heat distribution on the surface of each of the recesses 56 or the wafer 54 contained therein.

FIG. 2 is a plan view of the heating element 134. The heating element 134 may be used in a MOCVD system, such as in place of the heating element 34 described above with respect to FIG. 1. The heating element 134 is a serpentine coil that can be heated by applying a voltage. In an embodiment, such as in the embodiment shown in FIG. 2, different portions of the heating element 134 may be supplied with voltage by different voltage sources. As shown in FIG. 2, the heating element 134 is composed of five separate parts that are separately powered in a CVD system to provide heat.

The heating element 134 is supported by a series of posts 172 and a heating wire intermediary spacer 174. In FIG. 2, the post 172 is arranged to support the heating element 134 from the bottom, but in alternative embodiments, the post 172 may be positioned to prevent the heating element 134 from twisting, falling, or substantially preventing movement in unwanted directions. In any of the areas. The column 172 does not completely block the movement of the heating element 134, because a certain movement is necessary in consideration of the thermal expansion or contraction of the heating element 134, and the heating element can be operated at temperatures of hundreds or even thousands of degrees Celsius. The posts 172 may include electrically insulating components that prevent electrical contact between the heating element 134 and other components of the CVD system.

The heating wire intermediary spacer 174 is more restrictive to the movement of the heating element 134 than the column 172. The heating wire intermediary spacer 174 is arranged along a path defined by the heating element 134. The heating wire intermediary spacer 174 extends at least partially circumferentially around the heating element 174. In some embodiments, the heating wire interposer 174 may include both conductive and resistive components, as described in more detail below.

FIG. 3 is a detailed view of a portion of the heating element 134 supported by the post 172 and the heating wire intermediary spacer 174. FIG. 3 further depicts an anode supplying power to the heating element 134 176A and 176B. In an embodiment, an anode and a corresponding cathode are disposed at opposite ends of each section of the heating element 134 (eg, the five sections described above with respect to FIG. 2) to power the heating element 134.

4-8 are detailed views of one embodiment of the heating wire intermediary spacer 274. The heating wire mediation spacer 274 is similar to the heating wire mediation spacer 174 depicted in FIGS. 2 and 3 and described above. Generally speaking, throughout the present invention, similar parts are described with reference numerals using a factor of 100 iterations. The heating wire intermediary spacer 274 includes a post 280, a flange 282, a tenon 284, a bracket 286, and insulating caps 288A and 288B.

The post 280, the flange 282, and the tenon 284 are structurally designed to hold the bracket 286 at a distance from an adjacent surface (e.g., the heating element 134 of FIGS. 2 and 3 is positioned on the upper plate). Any one or more of the post 280, the flange 282, or the tenon 284 may be made of an insulating material to electrically isolate the bracket 286 from adjacent surfaces.

FIG. 9 is a partial cross-sectional view of the heating wire intermediary spacer 274 previously described with respect to FIGS. 4-8. In the cross section shown in FIG. 9, the insulating cap 288B is equally divided (as shown by the hatching). As shown in FIG. 9, the bracket 286 passes through the insulating cap 288B, and the insulating cap 288B is held in place on the bracket 286. The bracket 286 is structurally designed to partially surround the electric resistance heating element, such as the heating element described above with respect to FIGS. 1-3.

In an embodiment, the bracket 286 may be made of metal or another conductive material, while the post 280, the flange 282, and / or the tenon 284 may be made of an electrically insulating material. Thus, the bracket 286 is electrically isolated from adjacent surfaces (eg, a board with a mortise into which a tenon 284 can be inserted as shown and described with respect to FIGS. 2-3). When the heated coil held by the bracket 286 expands, contracts, or otherwise deforms, unwanted electrical contact may be formed between the coil and adjacent portions of the coil. The bracket 286 prevents excessive movement of the coil, and the insulating caps 288A and 288B prevent Direct electrical contact. Thus, even if the coil is in contact with one of the insulating caps 288A or 288B, and even if the entire heating wire intermediary spacer is in electrical contact with an adjacent portion of the coil, a gap between the two sections of the coil that prevents arcing or electrical contact from occurring is maintained. . Therefore, the heater coil is not damaged and a desired uniform current is maintained without short circuits or undesired discharges between different parts of the coil.

In an embodiment, the insulating caps 288A and 288B may be made of aluminum oxide (Al ₂ O ₃ ), zirconia (ZrO ₂ ), talc, cordierite or boron nitride (BN), and other related materials. Each of these materials is capable of withstanding temperatures in excess of 1000 ° C while having a desirable high relative permittivity.

These materials can be used or have an expansion coefficient high enough to be used in a CVD or MOCVD system, an expansion coefficient close enough to the bracket 286 to maintain mating contact during heating, and high enough to prevent over the insulating cap 288A or 288B Other materials with a permittivity of an arc or discharge between sections of the electrical coil. Temperature requirements and the possibility of materials contaminating the reactor and / or process make modern refractories such as high-purity alumina more attractive.

Figures 10-15 depict alternative designs of heating wire intermediary spacers 374. As shown in FIGS. 10-15, the heating wire intermediary spacer 374 includes a post 380, a flange 382, a tenon 384, and a bracket 386, each of which is substantially similar to that described above with respect to FIGS. 4-9. Correspondences (280, 282, 284, and 286). Figures 10-15 also depict insulating caps 388A and 388B, which are similar to those of Figures 4-9 The insulating caps 288A and 288B have different shapes, so that the insulating coils held in the bracket 386 and the bracket 386 can contact each other. Therefore, the materials constituting the insulating caps 388A and 388B may not need to be resistant to deformation due to physical contact with neighboring coils, as the coils will come into contact with the bracket 386.

16-21 depict alternative designs of heating wire intermediary spacers 474. As shown in FIGS. 16-21, the heating wire intermediary spacer 474 includes a post 480, a flange 482, a tenon 484, and a bracket 486, each of which is substantially similar to that described above with respect to FIGS. Correspondences (280/380, 282/382, 284/384 and 286/386). 16-21 also depict an insulating cap 488, which is a one-piece cap fitted around the bracket 486.

The examples are intended to be illustrative and not restrictive. Additional embodiments are within the scope of the patent application. In addition, although aspects of the present invention have been described with reference to specific embodiments, those skilled in the art should recognize that changes can be made in form and detail without departing from the scope of the present invention as defined by the scope of the patent application .

Claims (15)

A heating wire intermediary spacer includes:
Plural bars
A bracket that is structurally designed to at least partially surround the heater coil; and an insulating spacer that is mechanically coupled to the bracket and is structurally designed to prevent the heater coil from being at least partially surrounded by the bracket Electrical contact occurs between the first portion and the second portion of the heater coil that is not at least partially surrounded by the bracket. The heating wire intermediary spacer of claim 1, further comprising a second insulating spacer, the second insulating spacer being mechanically coupled to the bracket and structurally designed to prevent the first portion of the heater coil from the Electrical contact occurs between third portions of the heater coil that are not at least partially surrounded by the bracket. The heating wire intermediary spacer of claim 1, wherein the plurality of columns include two columns. The heating wire intermediary spacer of claim 1, wherein each of the plurality of posts is coupled to the flange. A heating wire intermediary spacer as claimed in claim 4, wherein each of the flanges is coupled to a tenon. The heating wire intermediary spacer of claim 5, wherein for each column:
The bracket is coupled to a first end of the post;
A first end portion of the flange is coupled to a second end portion of the post opposite the first end portion of the post;
A first end of the tenon is coupled to a second end of the flange opposite to the first end of the flange,
And the tenon structure is designed to cooperate with the tenon in the adjacent structure. If the heating wire intermediary spacer of claim 6, wherein at least one of the posts, the flanges, and the tenons comprises an electrically insulating material. The heating wire intermediary spacer of claim 1, wherein the insulating spacer comprises an electrically insulating material. The heating wire intermediary spacer of claim 8, wherein the electrically insulating material is one of alumina, zirconia, block talc, cordierite, and boron nitride. A heating subsystem for chemical vapor deposition, wherein the heating subsystem includes:
Conductive heater coils arranged in a serpentine shape;
A plurality of heating wire intermediary spacers arranged along the heater coil, each of the heating wire intermediary spacers comprising:
Plural bars
A bracket structurally designed to at least partially surround the heater coil; and an insulating spacer that is mechanically coupled to the bracket and structurally designed to prevent the heater coil from being at least partially surrounded by the bracket Electrical contact occurs between a first portion of the and a second portion of the heater coil that is not at least partially surrounded by the bracket. The heating subsystem of claim 10, wherein the heater coil comprises a plurality of heater coil segments. The heating subsystem of claim 10, wherein each of the plurality of heating wire intermediary spacers further includes a second insulating spacer, the second insulating spacer is mechanically coupled to the bracket and is structurally designed to prevent the heater Electrical contact occurs between the first portion of the coil and a third portion of the heater coil that is not at least partially surrounded by the bracket. The heating subsystem of claim 10, wherein each of the plurality of posts is coupled to a flange, and wherein each of the flanges is coupled to a tenon. The heating subsystem of claim 10, wherein the insulating spacer comprises an electrically insulating material. The heating subsystem of claim 14, wherein the electrically insulating material is one of alumina, zirconia, talc, cordierite, and boron nitride.