JP6513842B2 - Apparatus for producing silicon core wire and polycrystalline silicon rod for producing polycrystalline silicon rod - Google Patents

Description

  The present invention relates to a polycrystalline silicon rod manufacturing technique, and more particularly, to prevent a silicon core wire from being broken or toppled over when depositing polycrystalline silicon on a silicon core wire by a CVD reaction, thereby ensuring stable polycrystalline silicon. It relates to the technology for enabling the production of rods.

  The Siemens method and the union carbide method are known as a manufacturing method of the polycrystalline silicon used as a raw material of the monocrystal silicon substrate for semiconductor manufacture, and the silicon substrate for solar cell manufacture.

  Needless to say, the Siemens method is a method in which a source gas containing chlorosilane is brought into contact with a heated silicon core wire (silicon starter filament), and polycrystalline silicon is vapor-phase grown on the surface of the silicon core wire by a CVD reaction.

  In the union carbide method, a gas containing monosilane (substantially chlorine free gas) is used as a raw material, and in the same manner as the Siemens method, polycrystalline silicon is brought into the gas phase on the silicon core surface by CVD reaction by contacting it with a heated silicon core. It is a method to make it grow (for example, refer to JP, 2010-269994, A (patent documents 1)).

  In recent years, attempts have been made to reduce the manufacturing cost of polycrystalline silicon by increasing the diameter of polycrystalline silicon rods and increasing the deposition rate of polycrystalline silicon. In order to increase the deposition rate of polycrystalline silicon, it is necessary to make the "film" formed on the surface of the growth layer of polycrystalline silicon extremely thin and to increase the deposition reaction temperature. Here, the "film" is an extremely thin area in which the source gas flows in a laminar flow on the surface of the polycrystalline silicon rod.

  In the case of supplying the source gas into the reactor so as to satisfy the high-speed growth conditions, kinetic energy of the gas inevitably increases. There is also a circumstance that the diameter of the silicon core wire is only a few millimeters, and under high speed growth conditions, the connection portion with the graphite chuck which is the holding member of the end of the inverted U-shaped silicon core wire is easily broken.

  In addition, since a voltage of several thousand volts is applied to the conduction to heat the silicon core wire to 700 to 1200 ° C., the connection portion (contact portion) between the silicon core wire and its holding member (graphite chuck) and the silicon core wire are energized. In the connection portion (contact portion) between the metal electrode to be used and the support member used to connect the holding member, sparks and the like are easily generated. This becomes remarkable as the specific resistance difference or the contact resistance between the silicon core wire and the holding member or between the holding member and the support member increases.

  When such a spark or the like occurs, the silicon core wire is locally fused or structurally damaged, and the connection strength significantly decreases. In the worst case, silicon is released at the initial stage of the precipitation reaction. The core may fall over or be damaged.

  When such breakage, fall, or breakage of the silicon core wire occurs, the subsequent precipitation reaction of polycrystalline silicon becomes impossible, and various methods have been proposed to prevent such inconvenience.

  JP-A-2009-256191 (patent document 2): "The polycrystalline silicon deposited on the surface of the electrode holding the silicon core rod supports the weight of the rod while preventing peeling off from the silicon core rod. The silicon core rod provided in the furnace is electrically heated, and the raw material gas supplied into the furnace is reacted to generate polycrystalline silicon on the surface of the silicon core rod. Polycrystalline silicon reaction furnace, wherein the bottom plate portion of the furnace is connected to an electrode holder provided in an electrically insulated state with respect to the bottom plate portion, and the electrode holder, and the silicon core rod is held upward The invention of a polycrystalline silicon reactor is disclosed which is characterized in that a core rod holding electrode is provided, and an uneven portion exposed to the atmosphere in the furnace is provided on the outer peripheral surface of the core rod holding electrode. The upper end portion of the core rod holding electrode is provided with a tapered portion whose diameter decreases upward, and the taper angle of the tapered portion is 70 ° or more and 130 ° or less. While it is easy to deposit polycrystalline silicon over the entire area of the outer peripheral side surface of the core rod holding electrode, polycrystalline silicon deposited in the tapered portion is peeled off because the slope is not made to be steeper than necessary. There is nothing to do. "

  JP-A-2010-235438 (Patent Document 3) is an invention directed to "providing an apparatus for producing polycrystalline silicon capable of producing a silicon product excellent in workability and high quality", which is "reaction" A polycrystalline silicon manufacturing apparatus for depositing polycrystalline silicon on the surface of a silicon core rod by bringing a raw material gas into contact with a silicon core rod along a vertical direction heated in a furnace, the lower end portion of the silicon core rod In the core rod holding portion, the holding hole has a shape in which the cross section along the horizontal direction has a plurality of corner portions; A screw hole communicating with the outer surface of the core rod holding portion is formed in the corner portion described above, and a fixing screw for fixing the silicon core rod is screwed into at least one of these screw holes. " A polycrystalline silicon manufacturing apparatus according to the present invention, "according to the present invention, the deflection of the pair of silicon core rods is not sufficiently corrected even when the connecting member is attached, or Adjust the standing position and posture of the silicon core rod according to the dimensional difference between the silicon core rod and the holding hole by changing the screw hole to which the fixing screw is screwed, etc. when there is a tilt or the like. Therefore, the deflection of the pair of silicon core rods connected by the connecting member can be corrected by the simple operation of changing the screwing position of the fixing screw.

  In view of the situation that "the electrical resistance between the holding portion and the silicon core rod is reduced and the silicon seed is efficiently heated" is proposed in JP 2010-235440 A (patent document 4). , “For the purpose of providing a polycrystalline silicon manufacturing apparatus capable of efficiently heating a silicon seed and producing high quality silicon products”, “raw material gas is applied to the silicon core rod along the vertical direction heated in the reactor. A polycrystalline silicon manufacturing apparatus for depositing polycrystalline silicon on the surface of the silicon core rod by contacting the core rod, wherein the core rod is made of a conductive material in which a holding hole into which the lower end portion of the silicon core rod is inserted is formed. And a holding section, wherein the silicon core rod is formed in a polygonal shape in cross section, and in the core rod holding section, the holding hole has a cross section intersecting in the vertical direction. It is a polygon corresponding to a core rod, and a screw hole communicating with the outer surface of the core rod holding portion is formed, and the screw hole is fixed to press the side surface of the silicon core rod to the inner surface of the holding hole. The invention of a polycrystalline silicon manufacturing apparatus having a structure in which a screw is screwed in is disclosed, "According to this invention, the side surface of the silicon core rod is in surface contact with the inner surface of the holding hole of the core rod holding portion. The electric resistance between the silicon core rod and the core rod holding portion is small, and power can be efficiently supplied to the silicon core rod.

  However, in the inventions disclosed in Patent Documents 2 to 4 described above, the structure of the holding member (graphite chuck) is complicated and the time required for the setting operation is also long, and a small number of screws for fixing the holding member are used. There is a disadvantage that a current of an excessive density flows locally and it is easy to spark due to looseness, biased excessive tightening, or the like.

  JP 2011-195438 A (patent document 5) aims at "providing an electrode with a significantly reduced overturning probability compared to an electrode of a conventional structure type", "a conical tip or a pyramid. A carbon-made electrode, the electrode comprising means for accommodating a filament rod, the sides of the conical tip or the pyramidal tip being raised at least one The invention of "electrode characterized in that it is surrounded by an edge" is disclosed.

  However, in addition to the fact that the one disclosed in Patent Document 5 has to be expensive because the electrode shape is complicated, Patent Document 5 is most important for preventing overturning and the like in the initial stage of deposition of polycrystalline silicon. There is no mention of how to devise the contact portion between the filament rod and the electrode.

  JP-A-2011-195439 (Patent Document 6) is an electrode made of carbon for the purpose of "providing an electrode whose falling probability is significantly reduced as compared with an electrode of a conventional structure". “The electrode consists of at least two different regions with different inherent thermal conductivities, the outer region (A) forms the base of the electrode and supports one or more inner regions, the innermost The invention of "electrode" is disclosed, characterized in that the region (B) of the upper part protrudes from the region (A) and has a lower inherent thermal conductivity than the region (A).

  And, according to Patent Document 6, "At the beginning of growth, and hence when the rod diameter is small, the rod legs initially grow only on the inset with low thermal conductivity. Because of the thermal conductivity, heat dissipation through the inset (region B) is low, and at the start of growth, little heat is dissipated across the electrode and across its electrode holder, Even if the rod diameter is still small, high temperatures can be obtained at the connection of the electrodes to the silicon rod: there is no cold area at the rod legs where an etching process can occur because of the excessively low temperature. Quickly and without error merge with the electrode tip in region (B), thereby reducing the rod diameter before or during the deposition process Debt is to be completely blocked. ".

  However, the electrode disclosed in Patent Document 6 has a complicated shape because it has regions having different inherent thermal conductivities, and as in Patent Document 5, prevention of fall of the initial stage of deposition of polycrystalline silicon, etc. is prevented. There is no mention of how to devise the contact portion between the filament rod and the electrode, which is the most important.

  Patent No. 2671235 (patent document 7) "suitable for mounting the said starter filament in the production of polycrystalline silicon rods by pyrolyzing gaseous silicon compounds on long starter filaments A graphite-made chuck having a hydrogen-impermeable outer covering layer, said "chuck made of graphite" on the electrode for supplying a current for heating the starter filament. A graphite chuck is disclosed that is characterized by having a lower groove suitable for mounting a graphite chuck.

  However, in the chuck structure disclosed in Patent Document 7, the contact resistance between the groove provided at the top end of the conical graphite chuck and the starter filament is large, and the probability of breakage or falling is extremely high.

  Japanese Patent No. 3909242 (patent document 8) describes that “the lower surface of the deposition apparatus has a current passage and an electrode holder which are electrically connected and fixed to the substrate of the deposition apparatus, and the electrode holder is disposed above the current passage. The problem is solved by a device having a top surface connected to a carbon electrode and in which a support can be fitted to this carbon electrode, wherein the carbon electrode has a thermal conductivity greater than 145 W / m · K and It is characterized by having a coefficient of thermal expansion adapted to the coefficient of thermal expansion of silicon. "The invention of an apparatus for depositing semiconductor material is disclosed.

  And, according to Patent Document 8, according to the above-mentioned invention, "during testing, it was shown that the polysilicon rod is inclined due to the breakage of the rod leg in many cases. A general carbon electrode and the above-mentioned material The occurrence of breakage of the rod legs could be significantly reduced only by exchanging with the carbon electrode having the characteristics: tilting of the polycrystalline silicon rod by the ruptured rod legs is prevented by the device according to the invention ". It is assumed.

  However, Patent Document 8 also does not mention how to devise the contact portion between the filament rod and the electrode, which is most important for preventing a fall or the like in the initial stage of deposition of polycrystalline silicon.

  As disclosed in JP 2012-521950 A (Patent Document 9), “a rod that incorporates a fine silicon rod and makes electrical contact with the silicon rod in a silicon deposition reactor in particular, and supports a rod end of the thin silicon rod Provided with a holder, the rod holder comprising at least three contact elements arranged around a support space supporting a thin silicon rod, each contact element supporting space so as to contact the thin silicon rod electrically and mechanically The invention of a contact-type clamping device is disclosed which forms a directionally facing contact surface and the contact surfaces of adjacent contact elements are spaced apart.

  However, the one disclosed in Patent Document 9 has to be expensive because the clamp structure is complicated.

  Japanese Patent Publication No. 2014-504582 (Patent Document 10) describes “a chuck comprising a first section comprising a well and a filament channel and a second section comprising an electrode channel”, wherein “the well is Defined by a plurality of slats extending circumferentially from the bottom surface of the well to one end of the first section, “each of the plurality of slats is separated by a window, each window being adjacent The invention of "a chuck having a well supporting a rod made during chemical vapor deposition" is disclosed, extending at least partially along the length of the slat.

  However, the chuck structure disclosed in Patent Document 10 does not take into consideration the swaying of the supported silicon core wire (filament) in the furnace, and is not suitable for the production of a polycrystalline silicon rod having a large diameter. Conceivable.

Unexamined-Japanese-Patent No. 2010-269994 JP, 2009-256191, A JP, 2010-235438, A JP, 2010-235440, A JP, 2011-195438, A JP, 2011-195439, A Patent No. 2671235 specification Patent No. 3909242 Specification JP 2012-521950 gazette Japanese Patent Application Publication No. 2014-504582

  As described above, all of the prior art can not sufficiently meet the recent demands for increasing the diameter of polycrystalline silicon rods and high speed deposition of polycrystalline silicon (for example, 13 μm / min or more). It is a fact.

  The present invention has been made in view of such problems, and the purpose of the present invention is to locally melt the silicon core wire due to generation of sparks or the like when depositing polycrystalline silicon on the silicon core wire by the CVD method. And to prevent structural damage, and in particular, to provide a technology that contributes to stable production by preventing tipping and breakage of the silicon core wire at the initial stage of the precipitation reaction.

  In order to solve the above problems, a silicon core wire according to the present invention is a silicon core wire serving as a seed for depositing polycrystalline silicon by a CVD reaction, and a side inserted into a holding member provided in a reaction furnace At the end of the head, there is a tapered portion that has a positive taper angle.

  Preferably, the taper of the tapered portion is 1/100 (taper angle 0.5729 °) or more and 1/10 (taper angle 5.725 °) or less, more preferably 1/80 (taper angle 0.7162) Or more and 1/20 (taper angle 2.864 °) or less, more preferably 1/60 (taper angle 0.9548 °) or more and 1/35 (taper angle 1.6366 °) or less .

  In addition, preferably, the taper length of the tapered portion is 20 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and still more preferably 20 mm or more and 60 mm or less.

  The apparatus for manufacturing a polycrystalline silicon rod according to the present invention further includes a holding member of a silicon core wire serving as a seed for depositing polycrystalline silicon by a CVD reaction, and the holding member inserts the end portion of the silicon core wire. The inner surface of the hole has a taper with a positive taper angle when the opening side of the hole is upward and the end insertion direction of the silicon core wire is downward.

  Similarly to the above, preferably, the taper of the tapered portion is 1/100 (taper angle 0.5729 °) or more and 1/10 (taper angle 5.725 °) or less, more preferably 1/80 (a taper angle). The taper angle is 0.7162 ° or more and 1/20 (taper angle 2.864 °) or less, and more preferably 1/60 (taper angle 0.9548 °) or more 1/35 (taper angle 1.6366) °) or less.

  In addition, as in the above, preferably, the taper length of the tapered portion is 20 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and still more preferably 20 mm or more and 60 mm or less.

  The above-described polycrystalline silicon rod manufacturing apparatus includes a support member used for connection between the metal electrode for energizing the silicon core wire and the holding member, and the lower end portion of the holding member has a positive taper angle. When the inner surface of the hole into which the lower end of the holding member is inserted has the opening side of the hole upward and the lower end insertion direction of the holding member downward. The taper angle may have a positive taper.

  The above-mentioned polycrystalline silicon rod manufacturing apparatus further includes a support member used for connection between the metal electrode for energizing the silicon core wire and the holding member, and the holding member is a recess provided at the lower end portion. When the opening side of the recess is a lower side, the inner surface has a taper with a positive taper angle, and the support member is a protrusion that receives the recess of the holding member, The surface of the projection may have a taper having a positive taper angle.

  Preferably, at least one of the holding member and the support member is made of graphite.

  In the present invention, the contact portion of the silicon core wire and the holding member holding the end is designed to have a taper. In such a storage state, the silicon core wire is held by its own weight instead of being fixed by an external force such as a screw. As a result, even when the difference in specific resistance between the material of the silicon core wire and the holding member is large, the substantial difference in contact resistance becomes small, and generation of sparks and the like when depositing polycrystalline silicon is suppressed. Overturning and breakage are prevented.

FIG. 1 (A) is a view showing an example of a silicon core wire according to the present invention, and FIG. 1 (B) is an enlarged view of a tapered portion. FIG. 2: is a schematic explanatory drawing which shows an example of a structure of the reaction furnace which is a manufacturing apparatus of the polycrystalline silicon stick which concerns on this invention. FIG. 3 (A) is a view of a core wire holder for holding a silicon core wire, and an embodiment of an adapter for mounting the core wire holder, and FIG. 3 (B) is an end of the silicon core wire inserted into the core wire holder. It is a figure which shows a mode that it does. FIG. 4 (A) is a view of another embodiment of a core holder for holding a silicon core and an adapter for mounting the core holder, and FIG. 4 (B) is an end of the silicon core on the core holder. It is a figure which shows a mode that it inserts.

  Hereinafter, with reference to the drawings, an apparatus for manufacturing a silicon core wire and a polycrystalline silicon rod according to the present invention will be described.

  The inventors of the present invention have found that providing a suitable gradient at the connecting portion of the silicon core wire and the member holding the end thereof is caused by the generation of a spark or the like when depositing polycrystalline silicon on the silicon core wire by the CVD method. We have found that it is effective in preventing local fusion and structural damage of the core wire.

  FIG. 1A is a view showing an example of a silicon core wire according to the present invention, wherein the silicon core wire 100 has an inverted U-shape, and taper portions (10a, 10b) having positive taper angles at both ends thereof. have.

  FIG. 1B is an enlarged view of the tapered portion 10, where the tapered length of the tapered portion is L, the taper angle is θ, and the taper is [(α + 1) −α] / L (= 1 / L). It is defined. The taper of the taper portion 10 is preferably set to 1/100 (taper angle θ = 0.5729 °) or more and 1/10 (taper angle 5.725 °) or less, more preferably 1/80 (taper angle 0) Is set to 1/20 (taper angle 2.864 °) or less, more preferably 1/60 (taper angle 0.9548 °) to 1/35 (taper angle 1.6366 °) Set to The taper length L is preferably 20 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and still more preferably 20 mm or more and 60 mm or less.

  FIG. 2: is a schematic explanatory drawing which shows an example of a structure of the reaction furnace 200 which is a manufacturing apparatus of the polycrystalline silicon stick which concerns on this invention. The reaction furnace 200 shown in this figure is an apparatus for depositing polycrystalline silicon on the surface of the silicon core wire 100 by the CVD reaction by the Siemens method to obtain the polycrystalline silicon rod 120, and is constituted by the base plate 25 and the bell jar 21. Ru.

  The base plate 25 is provided with a metal electrode 30 for supplying a current to the silicon core wire 100, a gas nozzle 29 for supplying a process gas such as nitrogen gas, hydrogen gas or trichlorosilane gas, and an exhaust port 28 for discharging exhaust gas. . Further, the base plate 25 is provided with an inlet portion 26 and an outlet portion 27 of a refrigerant for cooling itself.

  The bell jar 21 has a refrigerant inlet 23 and an outlet 24 for cooling itself, and further has a viewing window 22 for visually confirming the inside from the outside.

  The metal electrode 30 is for supplying electricity to the silicon core wire 100, has an inlet 31 and an outlet 32 of a refrigerant for cooling itself, and is attached to the base plate 25 through the insulator 35, In the upper part, an adapter (supporting member of core wire holder 34) 33 provided between metal electrode 30 and core wire holder (holding member) 34 for holding end 10 of silicon core wire 100 can be mounted. It has become.

  That is, the core holder 34 is fixed to the upper part of the adapter 33, the end 10 of the silicon core 100 is fixed to the core holder 34, and the adapter 33 and the core are supplied with electricity from the metal electrode 30 to the silicon core 100. It will be done via the holder 34.

  FIG. 3A is a view showing an example of one embodiment of a core holder 34 holding the silicon core 100 and an adapter 33 on which the core holder 34 is placed. FIG. It is a figure which shows a mode that the edge part 10 of 100 is inserted.

  The core wire holder 34, which is a holding member of the silicon core wire, is provided with a hole for inserting the end 10 of the silicon core wire, and the inner surface of the core wire holder 34 has the opening side of the hole upward. When the insertion direction is downward, a taper having a positive taper angle is provided.

  This taper is preferably 1/100 (taper angle 0.5729 °) or more and 1/10 (taper angle 5.725 °) or less, as described above, to receive the end 10 of the silicon core wire described above. Is more preferably 1/80 (taper angle 0.7162 °) or more and 1/20 (taper angle 2.864 °) or less, and still more preferably 1/60 (taper angle 0.9548 °) or more And is less than or equal to 1/35 (a taper angle of 1.6,366 °).

  Similarly to the above, the taper length is preferably 20 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and still more preferably 20 mm or more and 60 mm or less.

  In the aspect shown in this figure, the core wire holder 34 (holding member) has a taper whose lower end portion has a positive taper angle. On the other hand, the adapter 33 (supporting member) used to connect the metal electrode 30 for energizing the silicon core wire 100 and the core wire holder 34 (holding member) is a hole for inserting the lower end portion of the core wire holder 34 (holding member) When the opening side of the hole is upward and the lower end insertion direction of the holding member is downward, the inner surface has a positive taper angle. The lower end portion of the core holder 34 (holding member) is inserted into the hole of the adapter 33 (supporting member) to fix the silicon core 100.

  The taper (taper angle) and taper length are set in a range sufficient to firmly hold the core holder 34 holding the silicon core.

  FIG. 4A is a view of another example of the core wire holder 34 for holding the silicon core wire 100 and the adapter 33 for mounting the core wire holder 34, and FIG. 4B is a view of the core wire holder 34 with silicon. It is a figure which shows a mode that the edge part 10 of the core wire 100 is inserted.

  Also in this embodiment, the core wire holder 34, which is a holding member of the silicon core wire, is provided with a hole for inserting the end 10 of the silicon core wire, and the inner surface of the silicon core wire is the opening side of the hole is the upper side. When the insertion direction of the end portion 10 of the is the downward direction, it has a taper which is a positive taper angle.

  This taper is also preferably 1/100 (taper angle 0.5729 °) or more and 1/10 (taper angle 5.725 °) or less to receive the end portion 10 of the silicon core wire described above. And more preferably 1/80 (taper angle 0.7162 °) or more and 1/20 (taper angle 2.864 °) or less, still more preferably 1/60 (taper angle 0.9548 °) Above, it is set to 1/35 (taper angle 1.6366 degrees) or less.

  Similarly to the above, the taper length is preferably 20 mm or more and 100 mm or less, more preferably 20 mm or more and 80 mm or less, and still more preferably 20 mm or more and 60 mm or less.

  In the embodiment illustrated in FIG. 4A, the core wire holder 34 (holding member) is provided with a recess at its lower end, and when the opening side of the recess is downward, the taper angle of the inner surface is plus Has a taper.

  On the other hand, on the upper part of the adapter 33 (supporting member) used for connection between the metal electrode 30 for energizing the silicon core wire 100 and the core wire holder 34 (holding member), a convex for receiving the recess of the core wire holder 34 (holding member) The surface of the convex portion has a taper having a positive taper angle. The concave portion of the lower end portion of the core holder 34 (holding member) receives the convex portion of the adapter 33 (supporting member), and the silicon core wire 100 is fixed.

  These tapers (taper angles) and taper lengths are also set in a range sufficient to firmly hold the core holder 34 holding the silicon core.

  As described above, the apparatus for manufacturing a polycrystalline silicon rod according to the present invention includes the holding member 34 of the silicon core wire 100 serving as a seed for depositing polycrystalline silicon by the CVD reaction, and the holding member 34 is silicon The inner surface of the hole into which the end 10 of the core wire 100 is inserted has a taper with a positive taper angle when the opening side of the hole is up and the end insertion direction of the silicon core 100 is down. Have the characteristic of

  The holding member 34 and the support member 33 may be metallic, but at least one is preferably made of graphite.

Example 1
The silicon core wire 100 was set in the reaction furnace 200 in the mode shown in FIG. The height (length) of the silicon core wire 100 is 1850 mm, and the cross section has a rectangle with one side of 7 mm. The end portion 10 of the silicon core wire 100 is provided with a tapered portion having a taper of 1/50 (a taper angle of 1.1459 °) and a taper length of 45 mm.

  The cross section of the opening of the core holder 34 for accommodating the end 10 of the silicon core 100 is rectangular, and the opening has a taper of 1/50 (a taper angle of 1.459 °) and a taper length of 40 mm. The silicon core wire 100 is processed and held by its own weight.

  After replacing the inside of the reaction furnace 200 with hydrogen, a voltage of 2000 V was applied to the silicon core wire 100 to conduct electricity (ignition). Thereafter, a raw material gas obtained by diluting trichlorosilane with hydrogen is supplied into the furnace, the surface temperature of the silicon core wire 100 is maintained at 1100 ° C., polycrystalline silicon is deposited at a deposition rate of 13 μm / min, and polycrystalline 45 mm in diameter A silicon rod 120 was manufactured.

  Although 10 batches of polycrystalline silicon rods were produced under the above conditions, no local melting or structural damage of the silicon core wire due to the occurrence of sparks or the like was observed, and there was no falling or breakage of the silicon core wire 100.

Example 2
Ten batches of 45 mm diameter polycrystalline silicon rods 120 were manufactured under the same conditions as in Example 1 except that polycrystalline silicon was deposited at a deposition rate of 15 μm / min. No local melting or structural damage was observed, and the silicon core wire 100 did not fall or break.

Comparative Example 1
The silicon core wire used has a height (length) of 1850 mm, and a cross section has a rectangular shape with one side of 7 mm. As in the prior art, this silicon core wire is not provided with a taper at its end. The end of this silicon core wire was inserted into the opening of the core wire holder and fixed by screwing from the side. In the opening of the core holder, as in Example 1, the opening having a rectangular cross section is processed into a tapered shape having a taper of 1/50 (a taper angle of 1.1459 °) and a taper length of 40 mm. There is.

  After replacing the inside of the reaction furnace 200 with hydrogen, a voltage of 2000 V was applied to the silicon core wire to conduct (ignition) electricity. Thereafter, a raw material gas prepared by diluting trichlorosilane with hydrogen is supplied into the furnace, the surface temperature of the silicon core wire is maintained at 1100 ° C., and polycrystalline silicon is deposited at a deposition rate of 13 μm / min. I made a stick.

  When a plurality of batches of polycrystalline silicon rods were manufactured under the above conditions, the silicon core wires were tipped over in the fifth batch due to local melting and cutting of the silicon core wires due to the generation of sparks.

Comparative Example 2
A plurality of batches of polycrystalline silicon rods 45 mm in diameter were produced under the same conditions as in Comparative Example 1 except that polycrystalline silicon was deposited at a deposition rate of 15 μm / min. As a result of the melting, the silicon core wire fell over in the eighth batch.

[Example 3]
The silicon core wire 100 was set in the reaction furnace 200 in the mode shown in FIG. The height (length) of the silicon core wire 100 is 2000 mm, and the cross section has a rectangle with one side of 7 mm. The end portion 10 of the silicon core wire 100 is provided with a tapered portion having a taper of 1/50 (a taper angle of 1.1459 °) and a taper length of 45 mm.

  The cross section of the opening of the core holder 34 accommodating the end portion 10 of the silicon core 100 is rectangular, and the opening has a taper of 1/50 (a taper angle of 1.459 °) and a taper length of 45 mm. The silicon core wire 100 is processed and held by its own weight.

  After replacing the inside of the reaction furnace 200 with hydrogen, a voltage of 2000 V was applied to the silicon core wire 100 to conduct electricity (ignition). Thereafter, the source gas obtained by diluting trichlorosilane with hydrogen is supplied into the furnace, the surface temperature of the silicon core wire 100 is maintained at 1100 ° C., the deposition rate is 15 μm / min up to 45 mm in diameter, and thereafter the deposition rate is 14 μm / min. Maintained, a polycrystalline silicon rod 120 with a diameter of 145 mm was manufactured.

  Although 10 batches of polycrystalline silicon rods were produced under the above conditions, no local melting or structural damage of the silicon core wire due to the occurrence of sparks or the like was observed, and there was no falling or breakage of the silicon core wire 100.

Example 4
Ten batches of polycrystalline silicon rods 120 with a diameter of 145 mm were produced under the same conditions as in Example 3 except that the taper of the tapered portion of silicon core wire 100 was changed to 1/35 (taper angle 1.6366 °). There was no local melting or structural damage to the silicon core wire due to the occurrence of sparks or the like, and there was no falling or breakage of the silicon core wire 100.

  As described above, in the present invention, the contact portion of the silicon core wire and the holding member holding the end thereof is designed to have a taper. In such a storage state, the silicon core wire is held by its own weight instead of being fixed by an external force such as a screw. As a result, even when the difference in specific resistance between the material of the silicon core wire and the holding member is large, the substantial difference in contact resistance becomes small, and generation of sparks and the like when depositing polycrystalline silicon is suppressed. Overturning and breakage are prevented.

  The present invention prevents local melting and structural damage of the silicon core wire due to the generation of sparks and the like when depositing polycrystalline silicon on the silicon core wire by the CVD method, and in particular, the silicon core wire at the initial stage of the precipitation reaction. To provide technology that contributes to stable production by preventing overturning and breakage.

DESCRIPTION OF SYMBOLS 10 edge part 21 bell jar 22 peephole 23, 26, 31 refrigerant inlet part 24, 27, 32 refrigerant outlet part 25 base plate 28 exhaust port 29 gas nozzle 30 metal electrode 33 adapter (support member)
34 core holder (holding member)
35 insulator 100 silicon core 120 polycrystalline silicon rod 200 reactor

Claims (4)

An apparatus for producing polycrystalline silicon rods,
A holding member of a silicon core wire serving as a seed for depositing polycrystalline silicon by a CVD reaction ,
The silicon core wire is a silicon core wire having a rectangular cross section, a taper angle of 0.5729 ° to 5.725 ° and a taper length of 20 mm to 100 mm at an end . ,
The cross section of the opening of the holding member is rectangular, and the inner surface of the hole into which the end of the silicon core wire is inserted has the opening side of the hole upward and the end insertion direction of the silicon core downward. , Has a taper that results in a positive taper angle,
The taper angle of the tapered portion is 0.5729 ° to 5.725 °, and the taper length of the tapered portion is 20 mm to 100 mm,
A nozzle for supplying a source gas so that the deposition rate of polycrystalline silicon is in the range of 13 to 15 μm / minute on the surface of the silicon core wire;
Production equipment for polycrystalline silicon rods. And a support member used for connection between the metal electrode for energizing the silicon core wire and the holding member,
The holding member has a taper whose lower end portion has a positive taper angle,
The support member has a taper with a positive taper angle when the inner surface of the hole into which the lower end of the holding member is inserted has the opening side of the hole upward and the lower end insertion direction of the holding member downward. The manufacturing apparatus of the polycrystalline-silicon rod of Claim 1 which it has. And a support member used for connection between the metal electrode for energizing the silicon core wire and the holding member,
The holding member is a recess provided at the lower end portion, and has a taper whose inner surface has a positive taper angle when the opening side of the recess is downward.
The support member is a convex portion for receiving the concave portion of the holding member, and the surface of the convex portion has a taper with a positive taper angle.
The manufacturing apparatus of the polycrystalline-silicon rod of Claim 1.   The apparatus for producing a polycrystalline silicon rod according to claim 2, wherein at least one of the holding member and the support member is made of graphite.