Carbon electrode and apparatus for manufacturing polycrystalline silicon rod

Abstract

The upper electrode 31 has a hole 35 extending from an upper surface 33 to a lower surface 34, a bolt 36 is inserted from the upper surface 33 of the upper electrode 31 into the hole 35, and secured in a lower electrode 32 by a screw. A gap 51 between an inside of the hole 35 and a straight body portion of the bolt 36 allows the upper electrode 31 to slide in all directions in a placement surface (upper surface of the lower electrode 32 in contact with the lower surface 34 of the upper electrode 31 in FIG. 2 ) that is a contact surface with an upper surface of the lower electrode 32, thereby providing an effect of preventing occurrence of a crack or a break in a U rod that can be expanded and contracted in all directions during a vapor phase growth process.

1 . A carbon electrode, comprising:
 a lower electrode secured on a metal electrode that is an external electrode for electrifying a silicon core; and   an upper electrode located on the lower electrode, and comprising a securing portion of a core holder that holds the silicon core on an upper surface side,   wherein the upper electrode is slidable in all directions in a placement surface that is a contact surface with an upper surface of the lower electrode, and   wherein:
 (a) the upper electrode is located on the lower electrode so that a protrusion located in an upper part of the lower electrode is inserted into a recess located in a lower part of the upper electrode, an inner size of the recess is larger than an outer size of the protrusion, and a gap is located between the recess and the protrusion; or 
 (b) the upper electrode is located on the lower electrode so that a protrusion located in a lower part of the upper electrode is inserted into a recess located in an upper part of the lower electrode, an inner size of the recess is larger than an outer size of the protrusion, and a gap is located between the recess and the protrusion. 
   
     
     
         2 - 5 . (canceled) 
     
     
         6 . The carbon electrode according to  claim 1 , wherein the gap between the recess and the protrusion is 1 mm or more. 
     
     
         7 . The carbon electrode according to  claim 1 , wherein the upper electrode and the lower electrode comprise graphite. 
     
     
         8 . The carbon electrode according to  claim 1 , wherein a coefficient of static friction of the contact surface between the upper electrode and the lower electrode is 0.3 or less. 
     
     
         9 . An apparatus, comprising a pair of metal electrodes, wherein electric power is supplied from the pair of metal electrodes to opposite ends of a silicon core assembled into an inverted U-shape to grow polycrystalline silicon from vapor phase on the silicon core,
 wherein both opposite ends of the silicon core assembled into the inverted U-shape are respectively held by securing portions provided in carbon electrodes, and at least one of the carbon electrodes is a carbon electrode according to  claim 1 .