Abstract:
A shroud is provided. The shroud may include: a body defining a hollow space within the body, wherein the body is open at a bottom portion of the body to permit fluid communication between the hollow space and the outside of the body; an inlet and an outlet providing fluid communication through the body to the hollow space; a top portion of the body configured to provide a barrier between the hollow space and the outside of the body; and a baffle plate attached to the bottom portion of the body. A method for adding silicon to a silicon melt may be provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to pending provisional U.S. patent application entitled, Gas Shroud and Method for Decomposing a Gas, filed Nov. 2, 2011, having a Ser. No. 61/554,783, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a method and apparatus for producing bottles of silicon. More particularly, the present invention relates to a shroud used in condensing silicon from a silicon gas or liquid and a corresponding method for decomposing silicon containing gas or separating silicon from liquid silicon. 
       BACKGROUND OF THE INVENTION 
       [0003]    Processed silicon is sold primarily to two industries, a semiconductor market and the photovoltaic industry. Silicon wafers are used in the production of solar panels in the photovoltaic market and for the production of microchips in the semiconductor market. One problem that remains in these markets is a shortage of polysilicon. Currently, silicon manufactures may produce quasi-monocast ingots which may have many impurities. Such impurities in a monocast silicon ingot is a nuisance for the wafer cutting machinery. Semiconductor companies cannot accept the impurities levels of monocast silicon. Therefore, silicon boules that are pure and single crystals are desired. 
         [0004]    Accordingly, it is desirable to provide a method or apparatus that may be used in the production of silicon boules having a desired purity. 
       SUMMARY OF THE INVENTION 
       [0005]    The foregoing needs are met, to a great extent, by the present invention. In one aspect, an apparatus is provided that, in some embodiments, a method and apparatus is provided that is able to produce single crystal silicon bottles of a desired purity. 
         [0006]    In accordance with one embodiment of the present invention a shroud is provided. The shroud may include: a body defining a hollow space within the body, wherein the body is open at a bottom portion of the body to permit fluid communication between the hollow space and the outside of the body; an inlet and an outlet providing fluid communication through the body to the hollow space; a top portion of the body configured to provide a barrier between the hollow space and the outside of the body; and a baffle plate attached to the bottom portion of the body. 
         [0007]    In accordance with another embodiment of the present invention, a method for adding silicon to a silicon melt may be provided. The method may include: flowing a silicon fluid through a shroud wherein the shroud has: a body defining a hollow space within the body, wherein the body is open at a bottom portion of the body to permit fluid communication between the hollow space and the outside of the body; an inlet and an outlet providing fluid communication through the body to the hollow space; atop portion of the body configured to provide a barrier between the hollow space and the outside of the body; and a baffle plate attached to the bottom portion of the body; and separating silicon from the silicon fluid when the silicon fluid is exposed to a surface of the silicon melt. 
         [0008]    In accordance with yet another embodiment of the present invention, a shroud may be provided. The shroud may include: means for containing a fluid defining a hollow space within the means for containing a fluid, wherein the means for containing a fluid is open at a bottom portion of the means for containing a fluid to permit fluid communication between the hollow space and the outside of the means for containing a fluid; an inlet and an outlet providing fluid communication through the body to the hollow space; a top portion of the means for containing a fluid configured to provide a barrier between the hollow space and the outside of the means for containing a fluid; and a means for baffling a fluid attached to the body. 
         [0009]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0010]    In this respect, before explaining at least one embodiment of the invention in detail, it is to he understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0011]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily he utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims he regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a gas shroud in accordance with an embodiment of the invention. 
           [0013]      FIG. 2  is a perspective, cross-sectional view of a gas shroud in a crucible in accordance with an embodiment of the invention. 
           [0014]      FIG. 3  is a cross-sectional view of the gas shroud in crucible in a heating apparatus in accordance with an embodiment of the invention. 
           [0015]      FIG. 4  is a perspective view of a shroud in accordance with an embodiment of the invention. 
           [0016]      FIG. 5  is a perspective, cross-sectional view of a shroud in accordance with an embodiment of the invention. 
           [0017]      FIG. 6  is cross-sectional view of a shroud in accordance with an embodiment of the invention illustrating a warped or flexed position of the bottom baffle plate. 
           [0018]      FIG. 7  is a perspective view of a shroud in accordance with another embodiment of the invention. 
           [0019]      FIG. 8  is a perspective, cross-sectional view of the shroud shown in  FIG. 7 . 
           [0020]      FIG. 9  is a partial cross-sectional of shroud in accordance with an embodiment of the invention. 
           [0021]      FIG. 10  is a perspective, partial cross-sectional view of the shroud shown in  FIGS. 7 and 8 . 
           [0022]      FIG. 11  is a cross-sectional view of shroud shown in  FIGS. 7 ,  8  and  10  where the shroud is in a crucible in accordance with an embodiment of the invention. 
           [0023]      FIG. 12  is a close up cross-sectional view of the shroud shown  FIG. 11 . 
           [0024]      FIG. 13  is perspective view of a shroud in accordance with an embodiment of the invention. 
           [0025]      FIG. 14  is perspective view of an underside of the shroud as shown in  FIG. 13 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention allows a gas shroud to be used in condensing liquid silicon from a silicon gas source. 
         [0027]    For example, a silicon ingot may be melted in a crucible and a silicon gas such as SiI 4  may flow over the silicon melt. The heat from the silicon melt may cause the SiI 4  gas to condense the silicon out of the gas into the melt and vent iodine gas. To facilitate this process, the Sit 4  gas must be exposed to the hot silicon melt in such a way to cause the silicon in the gas to condense out into the melt and not to be deposited on other portions of the heating apparatus. Furthermore, it is desired to control and/or contain the flow of the incoming SiI 4  gas and the outgoing iodine gas. In order to facilitate this process, a gas shroud may be used. 
         [0028]      FIG. 1  illustrates a gas shroud  10  in accordance with some embodiments of the invention. A gas shroud  10  may be made of quartz. In sonic embodiments, quartz is used because it is chemically inert with respect to SiI 4  gas and the silicon melt in which the shroud  10  is partially immersed. The gas shroud  10  may be machined for a single piece of quartz or may be comprised of several pieces attached together. 
         [0029]    The shroud  10  includes atop  12  and a bottom  14 . As shown in  FIG. 2 , the bottom  14  is open. Returning to  FIG. 1 , the shroud  10  is ring shaped or in the shape of an annulus. The shroud  10  may include an inlet  16  having an opening  18  to allow fluid communication through the top  12  into a shroud  10 . The shroud  10  may also include an outlet  20  which also may include an opening  22  to permit fluid communication from the interior of the shroud  10  through the top  12 . 
         [0030]    As shown in  FIG. 2 , the shroud  10  may define a hollow interior space  24 . The interior space  24  is in fluid communication with the opening  18  of the inlet  16  and the opening  22  of the outlet  20 . The interior space  24  is also open as the bottom  14  of the gas shroud  10 . 
         [0031]    The gas shroud  10  is shown in  FIG. 2  in a cross-section in order to better show the interior space  24 . The gas shroud  10  is also shown in  FIG. 2  in a crucible  26 . The crucible  2 . 6  has a quartz liner  28  which may be used in the melting of silicon ingots as is known in the art. The gas shroud  10  has an outer diameter that is smaller than the inner diameter of the crucible  26  and the quartz liner  28 . These relative dimensions permit the gas shroud  10  to fit, at least partially, in the crucible  26  and liner  28  without contacting each other as shown in  FIG. 2 . 
         [0032]    The quartz liner  28  within the crucible  26  defines a melting chamber  30 . Silicon ingots may be melted in the melting chamber  30 . A quartz liner  28  may be used in order to eliminate or reduce chemical reactions between crucible  26  and the melted or liquid silicon. 
         [0033]      FIG. 3  shows a cross-sectional view of a gas shroud  10  and crucible  26  in a heating apparatus  32 . The heating apparatus  32  may be substantially similar to most heating apparatuses used for melting silicon ingots in a crucible  26 . However, the heating apparatus  32  shown in  FIG. 3  has additional features in accordance with some embodiments of the invention which will be explained in detail later below. 
         [0034]    The heating apparatus  32  includes a support  34  as shown in  FIG. 3  to support the crucible  26 . The support  34  is configured to support and rotate the crucible  26 . Rotation of the crucible  26  while the ingot  46  is melted is well known and will not be discussed hereby in further detail. Below or near the support  34  may be burners or other heat producing elements which will not be described in detail as they are well known in the art. 
         [0035]    In accordance with some embodiments of the invention, the operation shown in  FIG. 3  of heating the ingot  46  to produce liquid silicon also referred to as the melt  40  may he augmented, or in other words, more liquid silicon may be produced by decomposing a silicon gas into the melting chamber  30  to produce additional liquid silicon. The silicon gas used for decomposing is provided by a silicon gas supply  36 . The silicon gas in some embodiments may be SiI 4 . Other silicon containing gases may also be used. The silicon gas supply  36  is placed in fluid communication with the gas shroud  10 . As the silicon gas flows from the silicon gas supply  36  into the gas shroud  10 , the silicon gas will decompose and allow liquid or condensed silicon to enter the melt  40 . 
         [0036]    The melt  40  has a top surface  38  which is depicted in  FIG. 3  by a line and reference numeral  38 . The silicon gas flows from the gas supply  36  through a gas flow path  42  and contacts the top surface  38  of the melt  40 . The high temperatures that the silicon gas encounters causes the silicon gas to decompose condensing silicon out of the gas and adding to the material in the melt  40 . 
         [0037]    In some embodiments, the gas shroud  10  is partially submerged into the melt  40 . Part of the melt material  40  is permitted to enter into the gas shroud  10  through the opened bottom surface  14 . Thus, there is melt material  44  that is located in the gas shroud  10 . By partially submerging the gas shroud  10  into the melt  40 , the gas flow path  42  is substantially hermetically sealed as the gas cannot flow out of the opened bottom  14  into the melt material  44  in the gas shroud  10 . Thus, the gas flows from the gas supply  36  through the inlet flow conduit  48  into the inlet  16  through the opening  18  through the gas flow path  42 . While it is in the shroud  10  it encounters hot temperatures condensing the silicon out of the silicon gas, thus leaving iodine gas. The iodine gas then flows through the outlet  20  through the opening  22  into the outlet flow conduit  52 . 
         [0038]    While it would be appreciated by many of ordinary skill in the art, such process may not be a perfect process, and some silicon may remain in the gas and is vented through the outlet  20 . 
         [0039]    According to some embodiments of the invention, the gas shroud  10  may be supported by and attached to the inlet flow conduit  48  and outlet flow conduit  52 . As shown in  FIG. 3 , the inlet flow conduit  48  includes a bend  50 . In some embodiments of the invention this bend  50  may have a reduced angle from the sharp, nearly 90° angle which is shown in  FIG. 3 . In embodiments where reduced angles are used may provide advantages where, silicon may be deposited onto the sloped surface near where the bend  50  is shown in  FIG. 3  and the sloped surface is sloped toward the inlet  16  opening  18  thereby causing the silicon to flow into the gas shroud  10  and add to the melt  40 . Similarly, in some embodiments, the bend  54  and the outlet flow conduit  52  may also be a more gentler slope than that shown in  FIG. 3 . If silicon is deposited in the interior of the outlet flow conduit  52  the slope of the interior of the outlet flow conduit  52  may be such as the silicon will flow into the gas shroud  10  through the outlet  20  opening  22  and into the melt  40 . 
         [0040]    In the case of SiI 4  gas, after the silicon is distilled iodine gas remains. The iodine gas flows out of the system outlet  56  and into a depository  58  or any other desired location for the resultant gas. It should be noted that the gas shroud  10  does several things. The gas shroud  10  provides a way for SiI 4  gas to be exposed to hot temperatures, thereby allowing it to decompose and condense silicon out of the gas arid into a melt  40 . The gas shroud  10  also allows the remaining gas to be vented out of the shroud  10 . The system allows the silicon to be deposited in a desired location while still allowing the gas to be channeled appropriately. 
         [0041]    One of ordinary skill in the art will understand that the shroud  10  will remain stationary, fixed and connected to the inlet flow conduit  48  and outlet flow conduit  52  or any other connections means, while the crucible  26  will be rotated. As such, the shroud  10  is dimensioned to be small enough to fit within the crucible  26  without contacting the crucible and thereby hindering the rotation of the crucible  26 . 
         [0042]    One of ordinary skill in the art after reading this disclosure will understand that the pressure of the gas supplied to the melt  40  should be controlled. This pressure should be controlled to avoid blowing the melt  40  out of the gas shroud  10  or crucible  26 . Further, the pressure should be controlled to avoid drawing the melt  40  into the gas shroud  10  to an undesirable degree. 
         [0043]    An example of the silicon melt and gas decomposing process will be described briefly below. If Si 2 I 4  gas is flowing at an 150 kilograms per hour, its decomposition will occur at a melt surface at 4.8 kilograms of silicon per hour. This is to match the 63 millimeters per hour pull rate at a 8 inch diameter crystal. The exit will be iodine gas. The following equation below will express this and show that the mass balance works appropriately. Equations below are merely meant to be exemplary and are not limiting. 
         [0000]    
       
         
           
             
               Growth_Rate 
                
               _KX 
             
             := 
             
               63 
               · 
               
                 mm 
                 hr 
               
             
           
         
       
       
         
           
             
               
                 Dia_ingot 
                 := 
                 
                   
                     205 
                     · 
                     mm 
                   
                   = 
                   
                     8.071 
                     · 
                     in 
                   
                 
               
                
               
                 
 
               
                
               This 
                
               
                   
               
                
               is 
                
               
                   
               
                
               growth 
                
               
                   
               
                
               rate 
                
               
                   
               
                
               for 
                
               
                   
               
                
               an 
                
               
                   
               
                
               8 
                
               
                   
               
                
               inch 
                
               
                   
               
                
               diameter 
                
               
                   
               
                
               
                 ingot 
                 . 
                 
                   
 
                 
                  
                 Area_ingot 
               
             
             := 
             
               
                 π 
                 · 
                 
                   
                     
                       ( 
                       Dia_ingot 
                       ) 
                     
                     2 
                   
                   4 
                 
               
               = 
               
                 0.033 
                 · 
                 
                   m 
                   2 
                 
               
             
           
         
       
       
         
           
             
               ρ 
               solid_Si 
             
             := 
             
               2340 
               · 
               
                 kg 
                 
                   m 
                   3 
                 
               
             
           
         
       
       
         
           
             
               
                 
                   
                     mass_flow 
                     
                       solid 
                        
                       _ 
                        
                       KX 
                     
                   
                   := 
                     
                    
                   
                     Growth_Rate 
                      
                     
                       _KX 
                       · 
                       Area_ingot 
                       · 
                       
                         ρ 
                         
                           solid 
                            
                           _ 
                            
                           Si 
                         
                       
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     4.866 
                     · 
                     
                       kg 
                       hr 
                     
                   
                 
               
             
           
         
       
       
         
           
             Mass 
              
             
                 
             
              
             Growth 
              
             
                 
             
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             Rate 
              
             
                 
             
              
             for 
              
             
                 
             
              
             the 
              
             
                 
             
              
             
               Ingot 
               . 
               
                 
 
               
                
               Flow 
             
              
             
                 
             
              
             Rate 
              
             
                 
             
              
             150 
              
             
                 
             
              
             kg 
              
             
               / 
             
              
             hr 
              
             
                 
             
              
             produces 
              
             
                 
             
              
             4.8 
              
             
                 
             
              
             kg 
              
             
                 
             
              
             of 
              
             
                 
             
              
             liquid 
              
             
                 
             
              
             Si 
           
         
       
       
         
           
             Decomposition 
              
             
                 
             
              
             Surface 
              
             
                 
             
              
             Area 
           
         
       
       
         
           
             Gas 
              
             
                 
             
              
             Shroud 
           
         
       
       
         
           
             
               OD 
               gs 
             
             := 
             
               
                 
                   23. 
                   · 
                   in 
                 
                  
                 
                   
 
                 
                  
                 
                   ID 
                   gs 
                 
               
               := 
               
                 
                   
                     21.5 
                     · 
                     in 
                   
                    
                   
                     
 
                   
                    
                   Area 
                 
                 := 
                 
                   
                     
                       π 
                       · 
                       
                         ( 
                         
                           
                             OD 
                             gs 
                             2 
                           
                           - 
                           
                             ID 
                             gs 
                             2 
                           
                         
                         ) 
                       
                     
                     4 
                   
                   = 
                   
                     
                       0.034 
                        
                       
                           
                       
                        
                       
                         m 
                         2 
                       
                        
                       
                         
 
                       
                        
                       
                         V 
                         y 
                       
                     
                     := 
                     
                       
                         
                           mass_flow 
                           solid_KX 
                         
                         
                           
                             ρ 
                             solid_Si 
                           
                           - 
                           Area 
                         
                       
                       = 
                       
                         61.479 
                         · 
                         
                           mm 
                           hr 
                         
                       
                     
                   
                 
               
             
           
         
       
       
         
           
             Ro 
             := 
             
               
                 
                   
                     ( 
                     
                       
                         OD 
                         gs 
                       
                       - 
                       
                         ID 
                         gs 
                       
                     
                     ) 
                   
                   2 
                 
                 + 
                 
                   ID 
                   gs 
                 
               
               = 
               
                 565.15 
                 · 
                 mm 
               
             
           
         
       
     
         [0044]    The embodiment of the shroud  10  shown in  FIGS. 1-3  is primarily directed to embodiments where the silicon supplied to the shroud  10  is in gaseous form. In other embodiments, the silicon maybe supplied to a shroud  10  in liquid form. For example, with reference to  FIG. 3 , the silicon supply  36  may supply liquid silicon as liquid SiI 4 . Other forms of liquid silicon may also be used. 
         [0045]    The SiI 4  liquid may flow through the flow path  42  around the bend  50  and into the inlet  16  via the inlet opening  18 . In such an instance, a different type of shroud may be used as shown, for example, in  FIGS. 4-14 . These various different shrouds  10  will be discussed further below. When the liquid contacts the melt  40 , a reaction may occur. In some embodiments, some, but not necessarily all, of the silicon may come out of the SiI 4  and be added to the melt  40 . Iodine gas maybe generated as a result of some of the silicon leaving the SiI 4  liquid and flow through the interior  24  of the shroud  10  and out of the outlet  20  through the outlet opening  22  through the system outlet  56  and into a depository  58 . In some embodiments of the invention, not only iodine gas will flow out the system outlet  56  but also some SiI 4  gas and/or liquid. 
         [0046]    In embodiments where the fluid supplied to the shroud  10  is in liquid form, a shroud  10 , as shown in  FIG. 4-6  may be used,  FIG. 4  illustrates a perspective view of the shroud  10 .  FIG. 5  is a perspective cross-sectional view and FIG,  6  illustrates a cross-sectional view of the shroud  10 . As shown in FIGS,  4 - 6 , the shroud  10  includes a top  12  and bottom  14 , inlet  16  having an inlet opening  18  and outlet  20  with an outlet opening  22 . The shroud  10  may be composed of quartz as described with the shroud  10  illustrated and described with respect to  FIGS. 1-3 . 
         [0047]    The shroud  10  may be very similar to the embodiment shown in  FIGS. 1-3 , but may have an additional feature of a bottom baffle plate  60  attached to the bottom portion  14  of the shroud  10 . As shown in  FIGS. 4-6  the bottom baffle plate  60  may include a hole  62  in the baffle plate  60 . The baffle plate  60  may be attached to the lower inner wall  57  at a position opposite of the lower outer wall  59 . The purpose of the baffle plate  60  and hole  62  in the baffle plate  60  is to reduce flow or disturbance of the melt  40  which may be caused when liquid silicon is supplied to the melt  40  via the inlet  16 . The flow of the liquid coming into the melt  40  may disturb the melt  40  and cause turbulence or flow, having the shroud  10  partially submerged in the melt  40  as well as the baffle plate  60  with the hole  62  will tend to dampen any flow or disturbance in the melt  40 . 
         [0048]    In some embodiments of the invention, the high temperature of the melt  40  may cause the bottom baffle plate  60  to sag. An exaggerated illustration of the sagging is shown by dashed line  65  in  FIG. 6 . 
         [0049]    Another embodiment of the invention is illustrated in  FIGS. 7-12 . As shown in  FIGS. 7 and 8 , the shroud  10  may include a second baffle plate  64  located at a mid-position within the shroud  10 . The second baffle plate  64  may include holes  66  and maybe located above the lower baffle plate  60 . The holes  66  may be of any shape such as, but not limited to, circles, ovals, ellipses or any other suitable shape. Column  68  maybe located in an annular arrangement around the hole  62  and configured to connect the lower baffle plate  60  to the mid or second baffle plate  64  as shown in  FIGS. 8 ,  10 ,  11  and  12 . 
         [0050]    The shroud  10  of the embodiment shown  FIGS. 7 and 8  has features similar to the other shrouds including the inlet  16 , the outlet  20 , the top portion  12 , the bottom portion  14  and the hollow interior space  24  and other common features. One purpose of the additional baffle plate  64  (or in some embodiments, a series of baffle plates) is to aid in reducing movement or flow of the melt  40  by adding additional baffling to reduce any disturbance of liquid flowing into the melt  40  via the inlet  16 . 
         [0051]      FIG. 9  is a partial cross-sectional view the portion of the shroud  10  shown in  FIGS. 7 ,  8 ,  10 ,  11  and  12 . As shown in  FIG. 9 , the lower outer wall  59  may not extend as far down as the lower inner wall  57 . The difference is illustrated by Arrow A. By selecting the geometry and measurements of the lower outer wall  59  to be higher than the lower inner wall  57  certain thermodynamic advantages may be achieved. The lower outer wall  59  still does form a hollow inner space  24  and will typically be submerged within the melt  40  along with the baffle plates  60  and  64 . Also the arrangement of having the lower inner wall  57  extend below the end of the lower outer wall  59  can also be used in embodiments for only a lower baffle plate  60  or where no baffle plate is used such as the embodiment shown in  FIGS. 1 and 2 . 
         [0052]      FIG. 10  is close up partial perspective view showing the column  68  attaching the upper mid baffle plate  64  with the lower baffle plate  60  in the shroud  10 . The column  68  may be located in annular pattern around the hole  62  and in some embodiments may include a notch  72  which helps to bend the columns in a desired way as shown in dash lines  69  in  FIG. 12  when the columns are subject to heat. 
         [0053]      FIG. 11  illustrates a shroud  10  located within a crucible  26  having a quartz liner  28 . A silicon wafer or ingot  46  is also illustrated. The wafer or ingot  46  is usually placed in contact with the melt  40  (see  FIG. 3 ). The melting chamber  30  includes a portion below shroud  10  within the crucible  26  and quartz liner  28  and extends upward to approximately where the bottom of the ingot  46  resides. 
         [0054]    An enlarged partial view of the  FIG. 11  is shown in  FIG. 12 . The shroud  10  is placed within the quartz liner  28  set within the crucible  26 . 
         [0055]    The melting chamber  30  contains the melt  40 . The shroud  10  is placed partially within the melt  40 . The top surface  38  of the melt is shown by line  38 . The top surface  38  of the melt  40  is contacted by the ingot  46 , in some embodiments of the invention, the ingot  46  contacts the top surface  38  of the melt  40  at about an 11° degree angle. The shroud  10  is submerged within the melt  40  so the part of the melt  40  is located within the hollow interior space  24  of the shroud  10 . The bottom baffle plate  60  and the upper baffle plate or mid baffle plate  64  are submerged within the melt  40 . Due to the high temperature of the melt  40 , the bottom baffle plate  60  and the mid baffle plate  64  may sag. The sagging of these plates  60  and  64  are illustrated by dash lines  61  and  65  respectively. The column  68  have buckled inwardly as illustrated by dash lines  69 . 
         [0056]    Dashed lines  61 ,  65  and  69  are for illustrative purposes, and may be exaggerated. The Dashed lines  61 ,  65 , and  69  are not intended to show or illustrate an amount that the plates  60 ,  61  and columns  68  may sag. Buckling of the column  68  may be facilitated by the presence of the notches  72 . The notches  72  create weak places in the columns  68  causing the columns  68  to bend in a desired way. One of the purposes for the notches  72  is to maintain uniform axisymmetric deflection so fluid inflow does not affect for reduce) the heating uniformity. Non heating uniformity can create different melt convection currents that may affect the quality of the ingot  46  at the melt interface  38 . This could change the stress and resistivity of the ingot  46 . One of ordinary skill in the art after reviewing this disclose may determine questions of how, where, how big or even if at all to use the notices  68  to achieve a desired result. 
         [0057]    The baffle plates  60  and  64  help reduce disturbances in the melt  40  and/or dampen any disturbance in the melt  40  caused by fluid flowing into the melt  40  via the inlet  16 . To an extent, the columns  68 , holes  62  and  66  also help dampen the melt  40 . The plates  60  and  64  and columns  68  may act to dampening even when they are sagging. The baffle plates  60  and  64  wall may he by design intentionally domed or from sagging of the quartz material due to high temperatures. The additional benefit of the dome or uniformly deformed baffles  50  and  64  is assist in the rejecting entrained bubbles from the pouring of the liquid SiI 4 . The dome surfaces  61  and  65  will assist in repelling the bubbles back upwards rather making the inner wall  57  even longer. 
         [0058]      FIGS. 13-14  illustrate an alternate embodiment in accordance with the invention.  FIGS. 13 and 14  show a combined inlet/outlet  76 . The combined inlet/outlet  16  contains both an inlet passage  78  and an outlet passage  80 . By locating the inlet passage  78  and the outlet passage  80  near the same location at a combined outlet/inlet  76 , any fluid flowing into the inlet  76  has additional time to contact the surface  38  of the melt  40  and will contact additional surface  38  area of the melt  40 . Contacting more surface  38  area and having more time may help in causing a reaction of separating silicon from the silicon gas or liquid whichever the case may be. In the embodiment shown in  FIGS. 13 and 14 , the silicon fluid must travel almost 360° degrees around the shroud  10  to reach the outlet  80 , whereas in the other embodiments described above, the fluid need only travel approximately 180° degrees around the shroud  10 . 
         [0059]    As shown in  FIGS. 13 and 14 , a bottom baffle plate  60  and hole  62  are included on the shroud  10 .  FIG. 14  is a rear or bottom view of the shroud  10  illustrating the hollow interior space  24 , the bottom baffle plate  60  and the hole  62  attached to the bottom portion  14  e shroud  10 . A divider  82  divides and provides separation within the hollow interior space  24  between the inlet passage  78  and the outlet passage  80 . One of ordinary skilled in the art after reading this disclosure will appreciate that the divider  82  prevents fluid from flowing into the inlet passage  78  and directly into the outlet passage  80 . Because of the divider  82  incoming fluid must flow completely around the shroud  10  through the hollow interior space  24  to reach the outlet passage  78 . 
         [0060]    One of ordinary skilled in the art after reading this disclosure will also appreciate that embodiments having combined inlet and outlet  76  may also be used where there is no baffle plate similar to that shown in  FIG. 1  and embodiments where multiple baffle plates are used similar to that embodiment shown in  FIGS. 7-12 . 
         [0061]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.