Silicon seed rod assembly of polycrystalline silicon, method of forming the same, polycrystalline silicon producing apparatus, and method of producing polycrystalline silicon
A silicon seed rod assembly used for producing polycrystalline silicon by means of a vapor deposition method includes two rod-shape silicon seed rods; and a silicon connection member bridging the silicon seed rods, wherein an opening-end peripheral edge of a through-hole on one side surface of the connection member is sharper than that on the other side surface thereof, and an opening-end peripheral surface on the one side surface thereof is formed into a flat contact surface disposed in a direction perpendicular to a perforation direction of the through-hole, and wherein a upper end portion of the silicon seed rod is inserted into the through-hole so that the contact surface comes into contact with the support surface of the silicon seed rod.
1. A method of forming a silicon seed rod assembly which is used for producing polycrystalline silicon by a vapor deposition method and includes two rod-shape silicon seed rods and a silicon connection member bridging the silicon seed rods, comprising the steps of:
forming a support surface at a step portion between an upper end portion and a main body portion of each silicon seed rod so as to be disposed in a direction perpendicular to a longitudinal direction of the upper end portion;
forming a pair of through-holes by perforating the silicon connection member from one side surface thereof by a drill in a direction perpendicular to the one side surface;
setting the two silicon seed rods positioned to be in an inclined state on a pair of electrodes provided in a reaction furnace, wherein a horizontal distance between the two silicon seed rods gradually increases in a direction from a base end portion to the upper end portion of the silicon seed rods; and
inserting each upper end portion of each silicon seed rod into each through-hole of the silicon connection member so as to make the upper end portions of the two silicon seed rods to be close to each other and so as to form a curvature in the two silicon seed rods, wherein the one side surface comes into contact with the support surface of the silicon seed rod;
wherein a distance L 1 between the upper end portions of the two silicon seed rods before insertion into the connection member is larger than a distance L 2 between the pair of through-holes formed in the connection member;
whereby causing a stretching force of the silicon seed rods acting on the silicon connection member in a longitudinal direction of the silicon connection member.
2. A method of producing polycrystalline silicon comprising the steps of:
forming a silicon seed rod assembly by uprightly supporting silicon seed rods by a pair of electrodes, respectively, disposed in a bottom portion in a reaction furnace and by providing a silicon connection member between upper end portions of the silicon seed rods;
heating the silicon seed rods by supplying current to the electrodes;
reacting the raw gas supplied to the reaction furnace; and
depositing polycrystalline silicon on surfaces of the silicon seed rods,
wherein the step of forming the silicon seed rod assembly includes the steps of:
forming a support surface at a step portion between an upper end portion and a main body portion of each silicon seed rod so as to be disposed in a direction perpendicular to a longitudinal direction of the upper end portion;
forming a through-hole by perforating the connection member from one side surface thereof by means of a drill in a direction perpendicular to the one side surface;
setting the two silicon seed rods positioned to be in an inclined state on the electrodes provided in the reaction furnace, wherein a horizontal distance between the two silicon seed rods gradually increases in a direction from a base end portion to the upper end portion of the silicon seed rods; and
inserting each upper end portion of each silicon seed rod into each through-hole of the silicon connection member so as to make the upper end portions of the two silicon seed rods to be close to each other and so as to form a curvature in the two silicon seed rods, wherein the one side surface comes into contact with the support surface of the silicon seed rod;
wherein a distance L 1 between the upper end portions of the two silicon seed rods before insertion into the connection member is larger than a distance L 2 between the pair of through-holes formed in the connection member;
whereby causing a stretching force of the silicon seed rods acting on the silicon connection member in a longitudinal direction of the silicon connection member.
3. The method of forming a silicon seed rod assembly according to claim 2 , wherein, the two silicon seed rods come into pressing-contact with the silicon connection member.