Silicon core wire

Abstract

In the silicon core wire according to a first aspect of the present invention, a male thread part formed at one end of a first thin silicon rod and a female thread part formed at one end of a second thin silicon rod may be screwed together and fastened. In the silicon core wire according to a second aspect of the present invention, a thread part formed at one end of a first thin silicon rod and a thread part formed at one end of a second thin silicon rod may be screwed together and fastened via an adapter with thread parts formed at both ends.

Claims

1. A silicon core wire, wherein a male thread part formed at one end of a first silicon rod and a male thread part formed at one end of a second silicon rod are screwed together and fastened via an adapter with female thread parts formed at both ends, wherein the adapter covers the male thread part formed at the one end of the first silicon rod and the male thread part formed at the one end of the second silicon rod from outside, and wherein the adapter is a silicon member.

2. The silicon core wire according to claim 1, wherein the first silicon rod and the second silicon rod are silicon rods collected from a polycrystalline silicon rod or a monocrystalline silicon rod.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1A and 1B are diagrams for describing a silicon core wire according to a first aspect of the present invention;

(2) FIGS. 2A and 2B are diagrams for describing a first example of a silicon core wire according to a second aspect of the present invention;

(3) FIGS. 3A and 3B are diagrams for describing a second example of a silicon core wire according to the second aspect of the present invention;

(4) FIGS. 4A and 4B are diagrams for describing a silicon core wire of Comparative Example 1; and

(5) FIGS. 5A and 5B are diagrams for describing a silicon core wire of Comparative Example 2.

DETAILED DESCRIPTION

(6) An embodiment of the present invention will be described below with reference to the drawings.

(7) FIGS. 1A and 1B are diagrams for describing a silicon core wire of a first aspect according to the present invention. FIGS. 1A and 1B, respectively, illustrate a silicon core wire before and after thin silicon rods are unified. As illustrated in these diagrams, a male thread part 15 is formed at one end of a first thin silicon rod 10, and a female thread part 25 is formed at one end of a second thin silicon rod 20. These thread parts are screwed together and fastened to be unified into one silicon core wire 100.

(8) These thin silicon rods are collected, for example, from polycrystalline silicon rods or monocrystalline silicon. Cross-sectional shape of a thin silicon rod is generally rectangular, although there is no particular limitation.

(9) The thread parts of the thin silicon rods are formed by machining, and the processed thin silicon rods are cleaned by etching to remove contamination. Because silicon of these thread parts is slightly removed by the etching, the thread parts are machined in consideration of portion to be removed by the etching so that the etched thread parts are screwed together.

(10) A screwing part is less likely to be heated abnormally with the unification using such thread parts, because the thread parts are screwed together by surface contact that allows secure fixation, and the silicon core wire is energized stably.

(11) FIGS. 2A and 2B are diagrams for describing a first example of a silicon core wire of a second aspect according to the present invention. FIGS. 2A and 2B, respectively, illustrate a silicon core wire before and after thin silicon rods are unified. In this aspect, a male thread part 15 is formed at one end of a first thin silicon rod 10, and a male thread part 25 is formed at one end of a second thin silicon rod 20. These thread parts are screwed together and fastened to be unified into one silicon core wire 100 via an adapter 30 with thread parts formed at both ends.

(12) FIGS. 3A and 3B are diagrams for describing a second example of a silicon core wire of the second aspect according to the present invention. FIGS. 3A and 3B, respectively, illustrate a silicon core wire before and after thin silicon rods are unified. In this aspect, a female thread part 15 is formed at one end of a first thin silicon rod 10, and a female thread part 25 is formed at one end of a second thin silicon rod 20. These thread parts are screwed together and fastened to be unified into one silicon core wire 100 via an adapter 30 with thread parts formed at both ends.

(13) Although thickness (width) a of a straight body part of an adapter 30 is set in consideration of an entire length of a silicon core wire 100 here, the thickness a may be zero. When a=0, the sum of lengths of the first thin silicon rod 10 and the second thin silicon rod 20 is the entire length of the silicon core wire 100. In a case where the thickness a of the straight body part of the adapter 30 is zero, there are advantages that fewer members are used for the adapter 30, and the silicon core wire is less likely to be bent during production because the number of engagement points is reduced from two to one, which enhances rigidity of the silicon core wire.

(14) Note that the adapter 30 is not limited to an adapter 30 of these aspects, and an aspect in which a male thread part is formed at one end and a female thread part is formed at another end may be used. In addition, from a viewpoint of preventing contamination, and the like, it is preferable that the above-described adapter 30 is a silicon member. Furthermore, from a viewpoint of smooth screwing, a small hole may be provided in the adapter 30 for air bleeding.

(15) [Example 1]

(16) A monocrystalline thin silicon rod was prepared, and a male thread part was formed at one end of the monocrystalline thin silicon rod. In addition, an adapter having a female thread inside as illustrated in FIGS. 2A and 2B was prepared. The adapter was provided with a small hole for air bleeding. Ten sets of two such thin silicon rods and one such adapter were prepared, and these members were cleaned by etching.

(17) The above-described two thin silicon rods were unified via the adapter to obtain a total of ten long silicon core wires, which were then used to assemble five inverted-U shaped silicon core wires.

(18) The obtained inverted-U shaped silicon core wires were set in a reacting furnace, and polycrystalline silicon rods were grown up to 130 mm in diameter by the Siemens process. The experiment process was completed without causing an accident such as abnormal growth or damage of the polycrystalline silicon rods. In addition, the hole provided for air bleeding allowed gas inside the screwing part to be replaced and reaction gas to flow into the hole, which accelerated growth of polycrystalline silicon inside the screwing part, resulting in tighter connection of the screwing parts.

(19) [Comparative Example 1]

(20) As illustrated in FIGS. 4A and 4B, monocrystalline thin silicon rods 50, 60 having one end face tapered in a projected shape 55, 65, and an adapter 70 having both end faces tapered in a recessed shape were prepared. Ten sets of two such thin silicon rods and one such adapter were prepared, and these members were cleaned by etching.

(21) The above-described two thin silicon rods were unified via the adapter to obtain a total of ten long silicon core wires, which were then used to assemble five inverted-U shaped silicon core wires. One set from among the five sets of the inverted-U shaped silicon core wires had a tapered part damaged during assembly.

(22) The four inverted-U shaped silicon core wires obtained by the assembly were set in a reacting furnace, and polycrystalline silicon rods were grown up to 130 mm in diameter by the Siemens process. One from among the four inverted-U shaped silicon core wires inclined when energized. The cause of the incline was examined and determined to be melting at a tapered part, which is considered to be attributed to abnormal heating.

(23) [Comparative Example 2]

(24) As illustrated in FIGS. 5A and 5B, two monocrystalline thin silicon rods 80, 90 were prepared, cleaned by etching, and then unified by welding. Ten thin silicon rods unified by welding, which were etched again, were prepared to assemble five inverted-U shaped silicon core wires.

(25) These five inverted-U shaped silicon core wires were set in a reacting furnace, and polycrystalline silicon rods were grown up to 130 mm in diameter by the Siemens process. One from among the five inverted-U shaped silicon core wires was damaged when energized. The cause of the damage was examined and determined to be breakage of a welded part. The breakage is considered to be a phenomenon caused by strain remained at a portion heated to a high temperature during welding.

(26) According to the present invention, a simple and less expensive long silicon core wire (thin silicon rod), having less risk of contamination and collapse, is provided.

REFERENCE SIGNS LIST

(27) 10, 20, 30, 40, 50, 60, 70, 80, 90 Thin silicon rod 15 Male thread part 25 Female thread part 30, 70 Adapter 55, 65 Tapered part 100, 200, 300 Long silicon core wire