Patent Application
20140353147
Disclosed herein are embodiments relating to a manufacturing apparatus. More specifically, disclosed herein is an electrode utilized within the manufacturing apparatus.
Manufacturing apparatuses for the deposition of a material on a carrier body are known in the art. Such manufacturing apparatuses comprise a housing that defines a chamber. Generally, the carrier body is substantially U-shaped having a first end and a second end spaced from each other. Typically, a socket is disposed at each end of the carrier body. Generally, two or more electrodes are disposed within the chamber for receiving the respective socket disposed at the first end and the second end of the carrier body, respectively. The electrode also includes a contact region, which supports the socket and, ultimately, the carrier body to prevent the carrier body from moving relative to the housing. The contact region is the portion of the electrode adapted to be in direct contact with the socket and that provides a primary current path from the electrode to the socket and into the carrier body.
A power supply device is coupled to the electrode for supplying an electrical current to the carrier body. The electrical current heats both the electrode and the carrier body. The electrode and the carrier body each have a temperature with the temperature of the carrier body being heated to a deposition temperature. A processed carrier body is formed by depositing the material on the carrier body.
As known in the art, variations exist in the shape of the electrode and the socket to account for thermal expansion of the material deposited on the carrier body as the carrier body is heated to the deposition temperature. One such method utilizes a flat head electrode and a socket in the form of a graphite sliding block. The graphite sliding block acts as a bridge between the carrier body and the flat head electrode. The weight of the carrier body and the graphite sliding block acting on the contact region reduces the contact resistance between the graphite sliding block and the flat head electrode. Another such method involves the use of a two-part electrode. The two-part electrode includes a first half and a second half for compressing the socket. A spring element is coupled to the first half and the second half of the two-part electrode for providing a force to compress the socket. Another such method involves the use of an electrode defining a cup with the contact region located within a portion of the cup. The socket is adapted to fit into the cup of the electrode and to contact the contact region located within the cup of the electrode. Alternatively, the electrode may define the contact region on an outer surface thereof without defining a cup, and the socket may be structured as a cap that fits over the top of the electrode for contacting the contact region located on the outer surface of the electrode.
A fouling of the electrode occurs on the exterior surface of the electrode outside of the contact region on the portion of the electrode that is disposed within the chamber due to the buildup of deposits. The deposits result in an improper fit between the socket and the electrode over time. The improper fit causes small electrical arcs between the contact region and the socket that result in metal contamination of the material deposited on the carrier body. The metal contamination reduces the value of the carrier body as the material deposited is less pure. Additionally, the fouling reduces the heat transfer between the electrode and the socket resulting in the electrode reaching higher temperatures to effectively heat the socket and ultimately the carrier body. The higher temperatures of the electrode result in accelerated deposition of the material on the electrode. This is especially the case for electrodes that comprise silver or copper as the sole or main metal present therein.
Additionally, a fouling of the electrode occurs on the exterior surface of the electrode, on the portion of the exterior surface that is outside of the chamber. Such fouling is different from the type of fouling that occurs on the portion of the electrode that is disposed within the chamber, which is attributable to the material used for deposition. The fouling of the exterior surface of the electrode that is outside of the chamber may be caused by industrial conditions outside of the manufacturing apparatus, or may merely be attributable to oxidation due to the exposure of the electrode to air. This is especially the case for electrodes that comprise silver or copper as the sole or main metal present therein.
The electrode must be replaced when one or more of the following conditions occur: first, when the metal contamination of the material being deposited upon the carrier body exceeds a threshold level; second, when fouling of the exterior surface of the electrode in the chamber causes the connection between the electrode and the socket to become poor; and third, when excessive operating temperatures for the electrode are required due to deposition of the material on the electrode. The electrode has a life determined by the number of the carrier bodies the electrode can produce before one of the above occurs.
In view of the foregoing problems related to fouling of the electrode, there remains a need to at least delay the fouling of the electrode to improve the productivity of the electrode and to thereby increase useful life of the electrode.
According to an embodiment, provided is an electrode for use with a manufacturing apparatus to deposit a material onto a carrier body with the carrier body having a first end and a second end spaced from each other with a socket disposed at each end of the carrier body. The electrode includes a shaft having a first end and a second end. The electrode also includes a head disposed on one of the ends of the shaft for coupling with the socket. The shaft and the head have an exterior surface having a contact region adapted to contact the socket. The electrode further includes an exterior surface and an exterior coating disposed on the exterior surface outside of the contact region, the exterior coating having an electrical conductivity of at least 9×106 Siemens/meter and corrosion resistance higher than silver in a galvanic series based upon room temperature sea water as an electrolyte.
The following is a brief description of the drawings wherein like elements are numbered alike and which are exemplary of the various embodiments described herein.
The to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a manufacturing apparatus 20 for deposition of a material 22 on a carrier body 24 is shown in
Typically, with methods of chemical vapor deposition known in the art, such as the Siemens method, the carrier body 24 is substantially U-shaped and has a first end 54 and a second end 56 spaced and parallel to each other. A socket 57 is disposed at each of the first end 54 and the second end 56 of the carrier body 24.
The manufacturing apparatus 20 includes a housing 28 that defines a chamber 30. Typically, the housing 28 comprises an interior cylinder 32, an outer cylinder 34, and a base plate 36. The interior cylinder 32 includes an open end 38 and a closed end 40 spaced from each other. The outer cylinder 34 is disposed about the interior cylinder 32 to define a void 42 between the interior cylinder 32 and the outer cylinder 34, typically serving as a jacket to house a circulated cooling fluid (not shown). It is to be appreciated by those skilled in the art that the void 42 can be, but is not limited to, a conventional vessel jacket, a baffled jacket, or a half-pipe jacket.
The base plate 36 is disposed on the open end 38 of the interior cylinder 32 to define the chamber 30. The base plate 36 includes a seal (not shown) disposed in alignment with the interior cylinder 32 for sealing the chamber 30 once the interior cylinder 32 is disposed on the base plate 36. In one embodiment, the manufacturing apparatus 20 is a Siemens type chemical vapor deposition reactor.
The housing 28 defines an inlet 44 for introducing a gas 45 into the chamber 30 and an outlet 46 for exhausting the gas 45 from the chamber 30. Typically, an inlet pipe 48 is connected to the inlet 44 for delivering the gas 45 to the housing 28 and an exhaust pipe 50 is connected to the outlet 46 for removing the gas 45 from the housing 28. The exhaust pipe 50 can be jacketed with a cooling fluid such as water or a commercial heat transfer fluid.
At least one electrode 52 is disposed through the housing 28 for coupling with the socket 57. In one embodiment, the at least one electrode 52 includes a first electrode 52 disposed through the housing 28 for receiving the socket 57 of the first end 54 of the carrier body 24 and a second electrode 52 disposed through the housing 28 for receiving the socket 57 of the second end 56 of the carrier body 24. It is to be appreciated that the electrode 52 can be any type of electrode known in the art such as, for example, a flat head electrode, a two-part electrode or a cup electrode. Further, the at least one electrode 52 is at least partially disposed within the chamber 30. In one embodiment, the electrode 52 is disposed through the base plate 36.
The electrode 52 comprises an electrically conductive material having a minimum electrical conductivity at room temperature of at least 14×106 Siemens/meter or S/m. For example, the electrode 52 can comprise at least one of copper, silver, nickel, Inconel and gold, each of which meets the conductivity parameters set forth above. Additionally, the electrode 52 can comprise an alloy that meets the conductivity parameters set forth above. Typically, the electrode 52 comprises electrically conductive material having a minimum electrical conductivity at room temperature of about 58×106 S/m. Typically, the electrode 52 comprises copper and the copper is typically present in an amount of about 100% by weight based on the weight of the electrode 52. The copper can be oxygen-free electrolytic copper grade UNS 10100.
Referring also to
In one embodiment, the electrode 52 includes a shaft 58 having a first end 61 and a second end 62. When present, the shaft 58 further defines the exterior surface 60 of the electrode 52. Generally, the first end 61 is an open end of the electrode 52. In one embodiment, the shaft 58 has a circular cross sectional shape resulting in a cylindrically-shaped shaft and defines a diameter D1. However, it is to be appreciated that the shaft 58 can have a rectangular, a triangular, or an elliptical cross sectional shape without deviating from the subject invention.
The electrode 52 can also include a head 72 disposed on one of the ends 61, 62 of the shaft 58. It is to be appreciated that the head 72 can be integral to the shaft 58. Typically, when the head 72 is present, the head 72 further defines the exterior surface 60 having the contact region 80. It is to be appreciated by those skilled in the art that the method of connecting the socket 57 to the electrode 52 can vary between applications without deviating from the subject invention. For example, in one embodiment, such as for flat head electrodes (not shown), the contact region can merely be a top, flat surface on the head 72 of the electrode 52 and the socket 57 can define a socket cup (not shown) that fits over the head 72 of the electrode 52 for contacting the contact region. Alternatively, although not shown, the head 72 may be absent from the ends 61, 62 of the shaft 58. In this embodiment, the electrode 52 may define the contact region on the exterior surface 60 of the shaft 58, and the socket 57 may be structured as a cap that fits over the shaft 58 of the electrode 52 for contacting the contact region 80 located on the exterior surface 60 of the shaft 58.
In another embodiment, as shown in
A first set of threads 84 can be disposed on the exterior surface 60 of the electrode 52. Referring back to
Referring back to
Referring again to
The electrode 52 has a temperature, which is modified by passage of the electrical current there through, resulting in a heating of the electrode 52 and thereby establishing an operating temperature of the electrode. Such heating is known to those skilled in the art as Joule heating. In particular, the electrical current passes through the electrode 52, through the socket 57 and into the carrier body 24 resulting in the Joule heating of the carrier body 24. Additionally, the Joule heating of the carrier body 24 results in a radiant/convective heating of the chamber 30. The passage of electrical current through the carrier body 24 establishes an operating temperature of the carrier body 24.
Referring to
The circulating system 98 includes a coolant in fluid communication with the channel 64 of the electrode 52 for reducing the temperature of the electrode 52. In one embodiment, the coolant is water; however, it is to be appreciated that the coolant can be any fluid designed to reduce heat through circulation without deviating from the subject invention. Moreover, the circulating system 98 also includes a hose 100 coupled between the electrode 52 and a reservoir (not shown). Referring only to
The coolant within the circulating system 98 is under pressure to force the coolant through the inner tube 101 and the outer tubes 102. Typically, the coolant exits the inner tube 101 and is forced against the terminal end 94 of the interior surface 62 of the electrode 52 and subsequently exits the channel 64 via the outer tube 102 of the hose 100. It is to be appreciated that reversing the flow configuration such that the coolant enters the channel 64 via the outer tube 102 and exits the channel 64 via the inner tube 101 is also possible. It is also to be appreciated by those skilled in the art of heat transfer that the configuration of the terminal end 94 influences the rate of heat transfer due to the surface area and proximity to the head 72 of the electrode 52. As set forth above, the different geometric contours of the terminal end 94 result in different convective heat transfer coefficients for the same circulation flow rate.
Referring to
The specific type of material used for the exterior coating 106 may depend upon the specific location of the exterior coating 106. For example, the source of corrosion and, thus, fouling may be different depending upon the specific location of the exterior coating 106. When the exterior coating 106 is disposed on the exterior surface 60 of the head 72 outside of the contact region 80, the exterior coating 106 is disposed within the chamber 30 and, thus, is exposed to the material 22 that is used to deposit on the carrier body 24. Under such circumstances, it may be desirable for the exterior coating 106 to provide resistance to corrosion in a chloride environment during the harvesting of polycrystalline silicon and to further provide resistance to chemical attack via chlorination and/or silicidation as a result of exposure to the material 22 that is used during the deposition process. Suitable metals that may be used for the exterior coating 106 on the head 72 of the electrode 52 outside of the contact region 80 include gold, platinum, and palladium. Typically, the exterior coating 106 comprises gold due to an excellent combination of electrical conductivity and resistance to corrosion from various sources. The exterior coating 106 may include other metals so long as at least one of gold, platinum, and palladium are included in the exterior coating 106. For example, in one embodiment, the exterior coating 106 may further include at least one of silver, nickel, and chromium, such as a nickel/silver alloy. Typically, the exterior coating 106 includes substantially only gold, platinum, and/or palladium. However, when one or more of the other metals are present, the total amount of gold, platinum, and palladium is typically at least 50% by weight based on the total weight of the exterior coating 106. When the exterior coating 106 is disposed on the exterior surface 60 of the shaft 58, the exterior coating 106 may include the same or different metals from those included in the exterior coating 106 on the head 72 outside of the contact region 80. In one embodiment, the exterior coating 106 on the shaft 58 includes different materials from the exterior surface 60 of the head 72, thereby allowing the exterior coating 106 on the shaft 58 to be tailored to resist corrosion from different sources than the cause of corrosion on the exterior surface 60 of the head 72. In another embodiment, the shaft 72 may be free from a coating disposed on the exterior surface 60 thereof. In yet another embodiment, the exterior surface 60 of the head may be free from a coating, with the exterior coating 106 only disposed on the exterior surface 60 of the shaft 58.
The exterior coating 106 typically has a thickness of from 0.0254 mm to 0.254 mm, more typically from 0.0508 mm to 0.254 mm and most typically from 0.127 mm to 0.254 mm.
The electrode 52 can be coated in other locations other than the exterior surface 60 for extending the life of the electrode 52. Referring to
Additionally, it is to be appreciated that the electrode 52 may further include an anti-tarnishing layer disposed on the channel coating 104. The anti-tarnishing layer is a protective thin film organic layer that is applied on top of the channel coating 104. Protective systems such as Technic Inc.'s Tarniban™ can be used following the formation of the channel coating 104 of the electrode 52 to reduce oxidation of the metal in the electrode 52 and in the channel coating 104 without inducing excessive thermal resistance. For example, in one embodiment, the electrode 52 can comprise silver and the channel coating 104 can comprise silver with the anti-tarnishing layer present for providing enhanced resistance to the formation of deposits compared to pure silver. Typically, the electrode 52 comprises copper and the channel coating 104 comprises nickel for maximizing thermal conductivity and resistance to the formation of deposits, with the anti-tarnishing layer disposed on the channel coating 104.
Without being bound by theory, the delay of fouling attributed to the presence of the channel coating 104 extends the life of the electrode 52. Increasing the life of the electrode 52 decreases production cost as the electrode 52 needs to be replaced less often as compared to electrodes 52 without the channel coating 104. Additionally, the production time to deposit the material 22 on the carrier body 24 is also decreased because replacement of electrodes 52 is less frequent compared to when electrodes 52 are used without the channel coating 104. The channel coating 104 results in less down time for the manufacturing apparatus 20.
In one embodiment, the electrode 52 includes a contact region coating 110 disposed on the contact region 80 of the electrode 52. The contact region coating 110 generally comprises a metal. For example, the contact region coating 110 can comprise at least one of silver, gold, nickel, and chromium. Typically, the contact region coating 110 comprises nickel or silver. The contact region coating 110 has a thickness of from 0.00254 to 0.254 mm, more typically from 0.00508 mm to 0.127 mm and most typically from 0.00508 mm to 0.0254 mm. Selection of the specific type of metal can depend on the chemical nature of the gas, thermal conditions in the vicinity of the electrode 52 due to a combination of the temperature of the carrier body 24, current flowing through the electrode 52, cooling fluid flow rate, and cooling fluid temperature may all influence the choice of metals used for various sections of the electrode. For instance, when the exterior coating 106 is disposed on the head 72 outside of the contact region 80, the exterior coating 106 can comprise nickel or chromium due to chlorination resistance while the use of silver for the contact region coating 110 may be chosen for silicidation resistance over natural resistance to chloride attack. Further, because silver is more electrically conductive than nickel or chromium, the silver may be more appropriate for the contact region coating 110 than nickel or chromium whereas electrical conductivity is of lesser importance outside of the contact region 80.
The contact region coating 110 also provides improved electrical conduction and minimizes a copper silicide buildup within the contact region 80. The copper silicide buildup prevents a proper fit between the socket 57 and the contact region 80 which can lead to a pitting of the socket 57. The pitting causes small electric arcs between the contact region 80 and socket 57 that results to metal contamination of the polycrystalline silicon product.
It is to be appreciated that the electrode 52 can have at least one of the channel coating 104 and the contact region coating 110 in any combination in addition to the exterior coating 106. The channel coating 104, the exterior coating 106 and the contact region coating 110 can be formed by electroplating. However, it is to be appreciated that the each of the coatings can be formed by different methods without deviating from the subject invention. Also, it is to be appreciated by those skilled in the art of manufacturing high purity semiconductor materials, such as polycrystalline silicon, that some plating processes utilize materials that are dopants, e.g. Group III and Group V elements (excluding nitrogen for the case of manufacturing polycrystalline silicon), and choice of the appropriate coating method can minimize the potential contamination of the carrier body 24. For example, it is desired that areas of the electrode typically disposed within the chamber 32, such as the head coating 108 and the contact region coating 110, have minimal boron and phosphorous incorporation in their respective electrode coatings.
A typical method of deposition of the material 22 on the carrier body 24 is discussed below and refers to
Once the carrier body 24 is processed, the electrical current is interrupted so that the electrode 52 and the carrier body 24 stop receiving the electrical current. The gas 45 is exhausted through the outlet 46 of the housing 28 and the carrier body 24 is allowed to cool. Once the operating temperature of the processed carrier body 24 has cooled the processed carrier body 24 can be removed from the chamber 30. The processed carrier body 24 is then removed and a new carrier body 24 is placed in the manufacturing apparatus 20.
The methods disclosed herein include at least the following embodiments:
An electrode for use with a manufacturing apparatus to deposit a material onto a carrier body with the carrier body having a first end and a second end spaced from each other with a socket disposed at each end of the carrier body. The electrode includes a shaft having a first end and a second end. The electrode also includes a head disposed on one of the ends of the shaft for coupling with the socket. The shaft and the head have an exterior surface having a contact region adapted to contact the socket. The electrode further includes an exterior surface and an exterior coating disposed on the exterior surface outside of the contact region, the exterior coating having an electrical conductivity of at least 9×106 Siemens/meter and corrosion resistance higher than silver in a galvanic series based upon room temperature sea water as an electrolyte.
the electrode of Embodiment 1, wherein said head is integral to said shaft.
the electrode of Embodiment 1, wherein said electrode defines a cup with said contact region located within a portion of said cup.
the electrode of Embodiment 1, wherein said exterior coating is disposed on at least one of said shaft and said head outside of said contact region.
the electrode of Embodiment 4, wherein said exterior coating is disposed on said head outside of said contact region.
the electrode of Embodiment 5, wherein said shaft is free from a coating disposed on said exterior surface thereof.
the electrode of Embodiment 1, wherein said head comprises copper.
the electrode of Embodiment 1, wherein said exterior coating comprises at least one of gold, platinum, and palladium.
the electrode of Embodiment 8, wherein said exterior coating further comprises at least one of silver, nickel, and chromium.
the electrode of Embodiment 8, wherein said exterior coating has a thickness of from 0.0254 to 0.254 mm.
the electrode of Embodiment 1, wherein said exterior contact region coating has a thickness of from 0.0254 mm to 0.254 mm.
the electrode of Embodiment 1, wherein said exterior coating has a thickness of from 0.0254 to 0.254 mm.
The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “Or” means “and/or.” The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The notation “±10%” means that the indicated measurement can be from an amount that is minus 10% to an amount that is plus 10% of the stated value. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of “less than or equal to 25 wt %, or 5 wt % to 20 wt %,” is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group.
The suffix “(s)” is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., the colorant(s) includes at least one colorants). “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.
All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.
While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.
This application claims priority to, and all advantages of, U.S. patent application Ser. No. 12/937,802, filed Oct. 14, 2010, PCT International Patent Application No. PCT/US09/002294, filed on Apr. 13, 2009, and U.S. Provisional Patent Application No. 61/044,687, filed on Apr. 14, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61044687 | Apr 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12937802 | Oct 2010 | US |
| Child | 14460843 | US |
