Method for manufacturing a polysilicon rod

Abstract

Prevent the initial polysilicon rod from collapsing during the growth period while improving the resistivity of the polysilicon rod deposited at the initial stage of the growth period. The method for manufacturing the polysilicon rod (S1) is to supply a raw material gas (G1) containing chlorosilanes to a silicon core wire that is erected inside a reactor (10) and heated by energization, thereby depositing polysilicon on the surface of the silicon core wire and growing it as a polysilicon rod (S1) with a diameter of 80 mm or more. The method for manufacturing the polysilicon rod (S1) is characterized in that the number of gas exchanges, which is the amount of the raw material gas (G1) introduced into the reactor (10) with respect to the volume of the reactor (10) during the growth start period (T1) of the polysilicon rod (S1) until 1 hour has elapsed since the start of polysilicon deposition on the surface of the silicon core wire, is 8 or more and less than 35, and the raw material gas (G1) is introduced into the reactor (10).

Description

[Technical field]

[0001] The present invention relates to a method for producing a polysilicon rod. [Background technology]

[0002] 2. Description of the Related Art In the production of polysilicon used as a raw material for semiconductor elements, solar power generation cells, and the like, a method is known in which raw material gases of chlorosilanes and hydrogen are injected into a reactor to precipitate polysilicon rods.

[0003] For example, in Patent Document 1, the flow rate of chlorosilane is increased to 1 m of the silicon surface within 15 hours from the start of deposition. 2 460 kg of chlorosilane per hour (kg / (h m 2 )) and maintains it constant for the remaining required charging time. Patent Document 2 also discloses a method for manufacturing a polysilicon rod in which the amount of raw material gas is maintained at a constant flow rate in the initial stage of the deposition reaction, and then the flow rate is gradually increased until the maximum flow rate is 3 to 6 times the initial flow rate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japan Special Publication No. 2010-540395 [Patent Document 2] Japanese Patent Application Publication No. 2014-028747 Summary of the Invention [Problem to be solved by the invention]

[0005] In the method for manufacturing a polysilicon rod, including the methods described in Patent Document 1 and Patent Document 2 above, generally, the polysilicon rod deposited at the initial stage of the growth period may have a low specific resistance value. Also, at the initial stage of the growth period, the rod diameter of the polysilicon rod is thin, and depending on the degree of introduction of the mixed gas introduced into the reactor, the polysilicon rod may sway and collapse.

[0006] One aspect of the present invention aims to improve the specific resistance value of the polysilicon rod deposited at the initial stage of the growth period while preventing the collapse of the polysilicon rod at the initial stage of the growth period.

Means for Solving the Problems

[0007] In order to solve the above problems, a method for manufacturing a polysilicon rod according to one aspect of the present invention supplies a raw material gas containing chlorosilanes to a silicon core wire that is erected inside a reactor and is energized and heated, thereby depositing polysilicon on the surface of the silicon core wire and growing it as a polysilicon rod with a diameter of 80 mm or more. The raw material gas is introduced into the reactor such that the number of gas exchanges, which is the amount of the raw material gas introduced into the reactor with respect to the volume of the reactor during the growth start period of the polysilicon rod until 1 hour has elapsed since the start of the deposition of polysilicon on the surface of the silicon core wire, is 8 or more and less than 35 times.

Effects of the Invention

[0008] According to one aspect of the present invention, it is possible to improve the specific resistance value of the polysilicon rod deposited at the initial stage of the growth period while preventing the collapse of the polysilicon rod at the initial stage of the growth period.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail. However, the following description is an example of the manufacturing apparatus 1 for the polysilicon rod S1 according to the present invention and its manufacturing method, and the technical scope of the present invention is not limited to the columns of the mode for carrying out the invention and the illustrated examples.

[0011] 〔Outline of Manufacturing Method of Polysilicon Rod〕 As a method for manufacturing the polysilicon rod S1, a raw material gas G1 containing chlorosilanes is supplied to a silicon core wire (not shown) that is erected inside the reactor 10 and is energized and heated, so that polysilicon is deposited on the surface of the silicon core wire and grown as the polysilicon rod S1. In such a manufacturing method of the polysilicon rod S1, the resistivity value of the polysilicon rod S1 deposited during the growth start period T1 (see FIG. 2) of the polysilicon rod may be low until 1 hour has elapsed since the start of deposition of polysilicon on the silicon core wire surface. Further, in the growth start period T1, the rod diameter of the polysilicon rod S1 is thin, and depending on the degree of input of the raw material gas G1 input into the reactor 10, the polysilicon rod S1 may shake and collapse.

[0012] The manufacturing method of the polysilicon rod S1 according to the present invention is to set the number of gas exchanges in the reactor 10 to the number of gas exchanges found by the intensive research of the inventors of the present application, thereby preventing the collapse of the polysilicon rod S1 during the growth start period T1 and realizing an improvement in the resistivity value of the deposited polysilicon rod S1.

[0013] 〔Configuration of the manufacturing apparatus for polysilicon rod〕 FIG. 1 is a schematic diagram showing a manufacturing apparatus 1 for a polysilicon rod S1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the manufacturing apparatus 1 for the polysilicon rod S1 includes a control unit 2, a mixer 3, a reactor 10, a supply pipe 20, a supply nozzle 40, an electrode 50, and a discharge pipe 60.

[0014] Here, the diameter of the supply nozzle 40 and the number of the supply nozzles 40 installed in the reactor 10 are not particularly limited. As an example, the diameter of the supply nozzle 40 may be 14φ or more and 18φ or less, and the number of the supply nozzles 40 may be 10 to 30.

[0015] The reactor 10 includes a bottom portion 11 on which the polysilicon rod S1 is disposed, and a bell-jar type lid portion 12 that is detachably connected to the bottom portion 11. The reactor 10 accommodates a raw material gas G1 for silicon deposition with the lid portion 12 connected to the bottom portion 11. The raw material gas G1 is a mixed gas, and chlorosilanes and hydrogen (H2) are mixed by the mixer 3 and introduced into the reactor 10. The chlorosilanes are, for example, a single substance or a mixture of gaseous monochlorosilane (SiH3Cl), dichlorosilane (SiH2Cl2), trichlorosilane (SiHCl3), and tetrachlorosilane (SiCl4).

[0016] In the bottom portion 11, an inlet 111 for the raw material gas G1 to flow into the reactor 10 and an outlet 112 for discharging the exhaust gas after the reaction in the reactor 10 are formed. A through-hole H1 extending through the bottom portion 11 extends from the inlet 111. A through-hole H2 extending through the bottom portion 11 extends from the outlet 112. In FIG. 1, two inlets 111 are formed in the bottom portion 11, and one outlet 112 is formed in the bottom portion 11. However, the number of the inlets 111 and the outlets 112 formed in the bottom portion 11 is not particularly limited.

[0017] The supply pipe 20 is connected to the end of the through-hole H1 on the side opposite to the inside of the reactor 10, and supplies the raw material gas G1 to the through-hole H1. The supply nozzle 40 is a nozzle that protrudes into the reactor 10 from the inlet 111. The supply nozzle 40 is provided at the bottom 11 to allow the raw material gas G1 flowing in from the inlet 111 to reach the upper part of the reactor 10 and grow the polysilicon rod S1 uniformly. Also, the height of the tip of the supply nozzle 40 is higher than the top of the electrode 50 in order to prevent the raw material gas G1 from directly hitting the vicinity of the electrode 50. By adjusting the gas linear velocity at the tip of the supply nozzle 40, it is possible to prevent the polysilicon rod S1 from being easily broken. The supply nozzle 40 is preferably made of a material with high corrosion resistance to the raw material gas G1, for example, made of carbon.

[0018] The electrode 50 is a member that electrically connects a power source (not shown) and the silicon core wire. The deposition temperature of polysilicon is about 600 °C or higher. From the viewpoint of rapidly depositing polysilicon on the silicon core wire, the silicon core wire is electrically heated so that the temperature of the silicon core wire is maintained at about 900 to 1000 °C. At least a pair of electrodes 50 are provided at the bottom 11. The number of electrodes 50 is determined corresponding to the number of silicon core wires installed inside the reactor 10.

[0019] The discharge pipe 60 is a pipe for discharging the gas formed in the silicon deposition process to the outside of the reactor 10. The discharge pipe 60 extends between the outside of the reactor 10 and the end on the side opposite to the discharge port 112 in the through-hole H2. The gas discharged from the silicon deposition process contains chlorosilanes, hydrogen (H2), hydrogen chloride (HCl), by-products, and contaminants. The gas formed and discharged in the silicon deposition process is recovered and treated.

[0020] The control unit 2 controls the supply of the raw material gas G1 to the reactor 10. The control unit 2 controls the supply of the raw material gas G1 to the reactor 10 based on the deposition time, the diameter of the polysilicon rod S1, the gas linear velocity at the tip of the supply nozzle 40, and the like. The function of the control unit 2 may be realized by the CPU (Central Processing Unit) executing a program stored in a storage unit (not shown).

[0021] [Manufacturing method of polysilicon rod] In the manufacturing method of the polysilicon rod S1 of the present application, a raw material gas G1 containing chlorosilanes is supplied to a silicon core wire that is erected inside the reactor 10 and is energized and heated, so that polysilicon is deposited on the surface of the silicon core wire and grown into a polysilicon rod S1 with a diameter of 80 mm or more, and includes a step of introducing the raw material gas G1 into the reactor 10.

[0022] FIG. 2 is a graph showing an example of the diameter of the polysilicon rod S1 during deposition for each deposition time. The diameter of the polysilicon rod S1 is 80 mm or more, preferably 90 to 180 mm, considering its industrial utility value. The growth period is generally 50 hours or more, preferably 60 to 150 hours. As shown in FIG. 2, the polysilicon rod S1 is deposited over about 100 hours until its diameter reaches about 130 mm as an example. In the following description, the time from the start of deposition to the completion of deposition of the polysilicon rod S1 (from 0 hour to 100 hours in FIG. 2) is described as the growth period T3 (total growth period).

[0023] In this specification, unless otherwise specified, the "diameter of the polysilicon rod S1" refers to the diameter in the state where polysilicon is deposited on the core wire, and the core wire is included in the diameter of the polysilicon rod S1. This diameter can be obtained by measuring the distance between the right end and the left end of the polysilicon rod S1 with a distance measuring instrument (not shown) provided outside the reactor 10 through a viewing window (not shown) provided on the side of the bell jar type lid 12 for observing the inside of the reactor 10.

[0024] (Number of gas exchanges) <Growth start period T1> As described above, the resistivity of the polysilicon rod S1 deposited during the growth start period T1 (the period until one hour has elapsed since the start of polysilicon deposition on the surface of the silicon core wire) may be low. This is presumably due to the following reasons.

[0025] Normally, the reactor 10 is (1) filled and held with high-purity gases such as hydrogen and nitrogen when the operation is stopped, and (2) at the start of manufacturing the polysilicon rod S1, the inside air of the reactor 10 is replaced with these high-purity gases and raw material gases for purification treatment, and then polysilicon deposition is carried out.

[0026] However, even after the above purification treatment, it is difficult to discharge all the contaminants released from the inner wall of the reactor 10 and accumulated in the reactor 10 during the operation stop of the reactor 10 to the outside of the reactor 10, and some will inevitably remain inside the reactor 10. Therefore, the contaminants remaining in the reactor 10 are incorporated into the deposited polysilicon during the growth start period T1 of the polysilicon rod S1. As a result, it is presumed that the resistivity of the relevant part decreases.

[0027] Also, during the growth start period T1, the diameter of the polysilicon rod S1 is thin, and depending on the degree of input of the raw material gas G1 introduced into the reactor 10, the polysilicon rod S1 may sway and collapse. Specifically, during the growth start period T1, the silicon core wire has a diameter that is usually as thin as 5 to 15 mm, and at the end of the growth start period T1, the diameter of the polysilicon rod S1 is as thin as 6 to 18 mm.

[0028] As a result of intensive research, the inventors of the present invention have found that by setting the number of gas exchanges in the reactor 10 during the growth start period T1 to 8 or more and less than 35 times, preferably 10 or more and less than 30 times, it is possible to prevent the polysilicon rod S1 from collapsing during the growth start period T1 and improve the resistivity of the deposited polysilicon rod S1.

[0029] Conventionally, during the growth start period T1, the number of gas exchanges is usually less than 8 times. However, the inventors of the present invention have found that by increasing the number of gas exchanges to 8 times or more, pollutants generated from the reactor 10 can be appropriately discharged. As a result, the resistivity of the polysilicon rod S1 deposited during the growth start period T1 can be greatly improved.

[0030] On the other hand, when the number of gas exchanges is increased, the gas linear velocity at the tip of the supply nozzle 40 increases, and the load on the thin-diameter polysilicon rod S1 during the growth start period T1 increases. In contrast, the inventors of the present invention have found that by keeping the number of gas exchanges less than 35 times, it is possible to prevent the above load from increasing to the extent that the polysilicon rod S1 collapses.

[0031] Moreover, by increasing the number of gas exchanges and increasing the input gas amount in this way, the growth rate of the diameter of the polysilicon rod S1 increases, and it reaches a thickness at which the diameter is less likely to collapse earlier. Furthermore, the productivity of the polysilicon rod S1 is also improved. Note that during the growth start period T1, when the number of gas exchanges is 35 times or more, the collapse occurrence rate of the polysilicon rod S1 increases and the productivity deteriorates.

[0032] Here, the number of gas exchanges is the input amount of the source gas G1 into the reactor 10 with respect to the internal volume of the reactor 10 per hour ((input amount of the source gas G1 into the reactor 10) / (internal volume of the reactor 10)), and the unit is times / h.

[0033] During the growth start period T1 of the polysilicon rod S1, the linear velocity of the source gas G1 input into the reactor 10 per supply nozzle 40 is preferably 40 Nm 3 / (s·m 2 ) or less. Thereby, the effect of preventing the collapse of the polysilicon rod S1 can be further enhanced. The linear velocity of the source gas G1 per supply nozzle 40 is more preferably 35 Nm 3 / (s·m 2 ) or less.

[0034] The lower limit of the linear velocity is appropriately determined according to the diameter of the supply nozzle 40. For example, the lower limit value of the linear velocity is 5.0 Nm 3 / (s·m 2 ) or more and 20.0 Nm 3 / (s·m 2 ) or less, and is appropriately determined within this range. By setting the linear velocity of the supply nozzle 40 to a value exceeding the above range, the raw material gas G1 can be sufficiently distributed over the upper part of the reactor 10.

[0035] Note that the "linear velocity" is the gas linear velocity at the tip of the supply nozzle 40 calculated by "input gas volume / (cross-sectional area of the nozzle × number of nozzles)".

[0036] <Growth initial period T2> In the method for manufacturing the polysilicon rod S1, during the growth period T3, until the polysilicon rod S1 grows to a desired diameter of 80 mm or more, the raw material gas G1 is also introduced into the reactor 10 even after the growth start period T1. The input amount of the raw material gas G1 generally increases after the growth start period T1 until the precipitation of polysilicon is completed. During the growth period T3, the maximum value of the number of gas exchanges per hour is preferably 80 or more and 100 or less.

[0037] Note that if any one hour during the growth period T3 is defined as an arbitrary period TE, and the hour immediately before the arbitrary period TE is defined as an arbitrary period TE-1, then the input amount of the raw material gas G1 after the growth start period T1 may, depending on the passage of time since the start of precipitation, temporarily maintain the same input amount as that of the arbitrary period TE-1 or decrease the input amount of the arbitrary period TE from that of the arbitrary period TE-1.

[0038] Even after the passage of the growth start period T1 during the growth period T3, during a certain period following the growth start period T1, although not as much as in the growth start period T1, there are still slightly some contaminants remaining in the reactor 10. Therefore, there is a risk that the contaminants remaining in the reactor 10 during a certain period following the growth start period T1 will be incorporated into the precipitated polysilicon and reduce the specific resistance value.

[0039] In particular, in the initial growth period T2 (see FIG. 2) following the elapse of the growth start period T1 of the polysilicon rod S1 until its diameter reaches 30 mm, a decrease in this resistivity value is likely to occur.

[0040] Therefore, in this initial growth period T2, the introduction of the source gas G1 into the reactor 10 is carried out in such a manner that (1) the doubling rate of the number of gas exchanges per hour in the initial growth period T2 is within the range of 0.6 or more and 5.0 or less, and (2) in the hour before the diameter of the polysilicon rod S1 reaches 30 mm, the number of gas exchanges increases to 30 or more and 50 or less. This makes it possible to further reduce the incorporation of contaminants into the polysilicon while continuing to prevent the collapse of the polysilicon rod S1 even in the initial growth period T2. Here, the "doubling rate of the number of gas exchanges per hour" is calculated as "(the number of gas exchanges in an arbitrary period TE) / (the number of gas exchanges in an arbitrary period TE - 1)".

[0041] If gas exchange is carried out within the above range in the initial growth period T2, following the growth start period T1 with the number of gas exchanges being 8 or more and less than 35, it is possible to prevent the collapse of the polysilicon rod S1 and keep the resistivity value low even in the initial growth period T2.

[0042] In the initial growth period T2, gas exchange is carried out with the doubling rate of the number of gas exchanges within the range of 0.6 or more and 5.0 or less, more preferably within the range of 0.7 or more and 3.5 or less, and particularly preferably within the range of 0.8 or more and 3.4 or less.

[0043] Also, if the doubling rate of the number of gas exchanges in the initial growth period T2 is 0.6 or more, the number of gas exchanges in an arbitrary period TE can be made less than that in an arbitrary period TE - 1. However, such a decreasing period should be only temporary, and in the hour before the diameter of the polysilicon rod S1 reaches 30 mm, it is necessary to increase the number of gas exchanges to 30 or more and 50 or less, more preferably 35 or more and 45 or less.

[0044] Here, from the start of the deposition of polysilicon on the surface of the silicon core wire until reaching the end of the initial growth period T2, in other words, the time from the start of the deposition of polysilicon until the diameter of the polysilicon rod S1 reaches 30 mm is usually 10 to 30 hours.

[0045] In addition, during the initial growth period T2, the linear velocity of the source gas G1 introduced into the reactor 10 per supply nozzle is 15 Nm 3 / (s·m 2 ) or more and 150 Nm 3 / (s·m 2 ) or less. Thereby, the effect of preventing the collapse of the polysilicon rod S1 can be further enhanced. The linear velocity of the source gas G1 per supply nozzle is preferably 20 Nm 3 / (s·m 2 ) or more and 120 Nm 3 / (s·m 2 ) or less.

[0046] (Example 1) Based on FIGS. 3 to 5, Example 1 of the present invention will be described. FIG. 3 is a graph showing the relationship between the deposition time and the amount of gas introduced for the examples and comparative examples of the present invention. More specifically, FIG. 3 is a graph showing the amount of gas introduced into the reactor 10 per hour from the start of deposition.

[0047] FIG. 4 is a graph showing the relationship between the deposition time and the number of gas exchanges for the examples and comparative examples of the present invention. More specifically, FIG. 4 is a graph showing the number of gas exchanges per hour from the start of deposition. FIG. 5 is a graph showing the measurement results of the resistivity values of the polysilicon rods S1 of the examples and comparative examples of the present invention. In FIGS. 3 to 5, a1-1 represents the result of Example 1, and a1-2, b1-1, and b1-2 represent the results of Example 2, Comparative Example 1, and Comparative Example 2, which will be described later, respectively.

[0048] In Example 1, a polysilicon rod S1 was manufactured using the manufacturing apparatus 1 shown in FIG. 1. The reactor 10 can hold 10 polycrystalline silicon rods (5 pairs of inverted U-shaped polysilicon rods S1). In Example 1, 5 pairs of inverted U-shaped silicon core wires with a height of 2000 mm were erected at the bottom 11 of the reactor 10.

[0049] Each silicon core wire of the reactor 10 was energized and heated so that the temperature became about 1000°C, and a mixed gas of trichlorosilane and hydrogen was used as the raw material gas G1, and the raw material gas G1 was introduced from the supply nozzle 40, and a silicon deposition reaction by the Siemens method was carried out for 100 hours. Six supply nozzles 40 were dispersedly arranged at substantially equal intervals over the entire upper surface of the bottom 11.

[0050] As a result, as shown in the graph of FIG. 2, the diameter of the polysilicon rod S1 grew, and a polysilicon rod S1 with a diameter of 130 mm was obtained. The above diameter is the average of the 10 manufactured polysilicon rods S1. In this example, the physical properties of the subsequent polysilicon rods S1 were also evaluated as the average of 10.

[0051] In the production of the polysilicon rod S1, until 1 hour has elapsed since the start of deposition, the growth start period T1, the raw material gas G1 was introduced into the reactor 10 at an input gas flow rate of 243 Nm 3 / h as shown in a1-1 of FIG. 3.

[0052] The number of gas exchanges during the growth start period T1 was 19 as shown in a1-1 of FIG. 4. At the end of the growth start period T1, the linear velocity per supply nozzle 40 of the raw material gas G1 introduced into the reactor 10 was 30.9 Nm 3 / (s·m 2 )

[0053] During the progress of the growth start period T1, none of the growing polysilicon rods S1 toppled over. At the end of the growth start period T1, the diameter of the polysilicon rod S1 had reached 11 mm.

[0054] Following the growth start period T1, until the diameter of the polysilicon rod S1 reached 30 mm, during the initial growth period T2, the raw material gas G1 was introduced into the reactor 10 with the input gas amount as shown in a1-1 of FIG. 3 and the number of gas exchanges as shown in FIG. 4. The elapsed time from the start of precipitation until the diameter of the polysilicon rod S1 reached 30 mm was 21 hours.

[0055] During the initial growth period T2, the doubling rate of the number of gas exchanges per hour was in the range of 0.9 to 2.0. Also, in the hour before the diameter of the polysilicon rod S1 reached 30 mm, the number of gas exchanges increased to 45 times. During this initial growth period T2, the linear velocity of the raw material gas G1 introduced into the reactor 10 per supply nozzle 40 was in the range of 30.9 to 72.7 Nm 3 / (s·m 2 ). During this initial growth period T2, not a single collapse of the polysilicon rod S1 occurred.

[0056] Furthermore, following the initial growth period T2, until 100 hours elapsed from the start of precipitation, the number of gas exchanges was gradually increased so as to reach the maximum value of 95 times at 42 hours from the start of precipitation, and thereafter, with the doubling rate of the number of gas exchanges per hour in the range of 0.0 or more and 1.5 or less, the raw material gas G1 was introduced into the reactor 10. Also, in the last hour at the end of growth, the number of gas exchanges was set to 0 times. Growth was terminated when 100 hours elapsed from the start of precipitation as described above, and a polysilicon rod S1 with a diameter of about 130 mm was obtained.

[0057] After manufacturing the above polysilicon rod S1, for the obtained polysilicon rod S1, a core rod with a diameter of 19 mm was drilled out in a direction perpendicular to the length direction of the rod S1 and including the core wire portion, and the resistivity value in the length direction of the core rod was measured to obtain the resistivity value in the radial direction of the polysilicon rod S1. The results are shown as a1-1 in FIG. 5. On the horizontal axis of FIG. 5, for example, "core wire + 2 cm" indicates a state where polysilicon was deposited with a thickness of about 1 cm (i.e., a diameter 2 cm larger than the diameter of the core wire) around the core wire.

[0058] At the resistivity value of a1-1 in FIG. 5, the resistivity Xa1-1 of the polysilicon rod S1 at the end of the growth start period T1, 1 hour after the start of polysilicon deposition, was a high value of about 1700 (Ωcm). Also, the resistivity Ya1-1 of the polysilicon rod S1 at the end of the initial growth period T2 when the diameter of the polysilicon rod S1 reached 30 mm (diameter Y) was about 3600 (Ωcm), and the high resistivity was well maintained.

[0059] (Comparative Example 1) Based on FIGS. 3 to 5, Comparative Example 1 of the present invention will be described. In Comparative Example 1, the polysilicon rod S1 was manufactured in the same manner as in Example 1, except that the input amount of the source gas G1 in the growth start period T1 and the initial growth period T2 was changed as follows. Comparative Example 1 is a method for manufacturing the polysilicon rod S1 along the input gas amount generally carried out conventionally.

[0060] In Comparative Example 1, the input amount of the source gas G1 in the growth start period T1 was reduced to 88 Nm shown in b1-1 of FIG. 3 3 / h, and the number of gas exchanges in the growth start period T1 was reduced to 7 times shown in b1-1 of FIG. 4. At the end of the growth start period T1, the linear velocity per supply nozzle 40 of the source gas G1 introduced into the reactor 10 was 9.7 Nm 3 / (s·m 2 ).

[0061] Also, in the initial growth period T2, the source gas G1 was introduced into the reactor 10 with the input gas amount as shown in b1-1 of FIG. 3 and the number of gas exchanges as shown in FIG. 4. The elapsed time from the start of precipitation until the diameter of the polysilicon rod S1 reached 30 mm was 21 hours.

[0062] During the initial growth period T2, the doubling rate of the number of gas exchanges per hour was in the range of 0.9 to 1.6. Also, the number of gas exchanges in the hour before the diameter of the polysilicon rod S1 reached 30 mm increased to 27 times. During the initial growth period T2, the linear velocity of the raw material gas G1 introduced into the reactor 10 per supply nozzle was 9.7 to 37.8 Nm 3 / (s·m 2 ).

[0063] In the production of the polysilicon rod S1 of Comparative Example 1, there was no collapse of the polysilicon rod S1 at the end of the growth start period T1. At the end of the growth start period T1, the diameter of the polysilicon rod S1 had reached about 11 mm.

[0064] Subsequently, there was no collapse of the polysilicon rod S1 at the end of the initial growth period T2. At the end of the initial growth period T2, the diameter of the polysilicon rod S1 had reached about 30 mm.

[0065] Regarding the obtained polysilicon rod S1, in the same manner as in Example 1, the core rod was drilled out, and the resistivity value in the longitudinal direction was obtained and shown as b1-1 in FIG. 5. The resistivity value Xb1-1 of the polysilicon rod S1 with a diameter X at the end of the growth start period T1 was about 480 (Ωcm), which was about 28% lower than that in Example 1. Also, the resistivity value Yb1-1 of the polysilicon rod S1 at the end of the initial growth period T2 when the diameter of the polysilicon rod S1 reached 30 mm (diameter Y) was about 980 (Ωcm), which was about 27% lower than that in Example 1.

[0066] (Comparative Example 2) Based on FIGS. 3 to 5, Comparative Example 2 of the present invention will be described. In Comparative Example 2, the production of the polysilicon rod S1 was carried out in the same manner as in Example 1, except that the input amount of the raw material gas G1 in the growth start period T1 was changed as follows.

[0067] In Comparative Example 2, the input amount of the raw material gas G1 in the growth start period T1 was 518 Nm shown in b1-2 of FIG. 33 Increased to / h, and the number of gas exchanges during the growth start period T1 was increased significantly to 40 times as shown in b1-2 of FIG. 4. During the growth start period T1, the linear velocity per supply nozzle 40 of the raw material gas G1 introduced into the reactor 10 was 65.7 Nm 3 / (s·m 2 ).

[0068] In Comparative Example 2, at the end of the growth start period T1, one pair (2 rods) out of 10 polysilicon rods S1 collapsed, and as the fallen polysilicon rods S1 leaned against other polysilicon rods S1, all the polysilicon rods S1 collapsed as a result.

[0069] (Example 2) Based on FIGS. 3 to 5, Example 2 of the present invention will be described. In Example 2, the polysilicon rod S1 was manufactured in the same manner as in Example 1, except that the input amount of the raw material gas G1 during the growth start period T1 and the growth initial period T2 was changed as follows.

[0070] In Example 2, the input gas amount during the growth start period T1 was decreased to 162 Nm shown in a1-2 of FIG. 3 3 / h, and the number of gas exchanges during the growth start period T1 was decreased to 13 times as shown in a1-2 of FIG. 4. At the end of the growth start period T1, the linear velocity per supply nozzle 40 of the raw material gas G1 introduced into the reactor 10 was 20.6 Nm 3 / (s·m 2 ).

[0071] Also, during the growth initial period T2, the raw material gas G1 was introduced into the reactor 10 with the input gas amount as shown in a1-2 of FIG. 3 and the number of gas exchanges as shown in FIG. 4. The elapsed time from the start of precipitation until the diameter of the polysilicon rod S1 reached 30 mm was 21 hours.

[0072] During the initial growth period T2, the growth doubling rate of the gas exchange frequency per hour was in the range of 0.8 to 2.2. Also, the gas exchange frequency increased to 30 times in the one hour before the diameter of the polysilicon rod S1 reached 30 mm. During this initial growth period T2, the linear velocity per supply nozzle of the raw material gas G1 introduced into the reactor 10 was 20.6 to 48.7 Nm 3 / (s·m 2 ).

[0073] In the production of the polysilicon rod S1 of Example 2, there was no collapse of the polysilicon rod S1 at the end of the growth start period T1. At the end of the growth start period T1, the diameter of the polysilicon rod S1 had reached about 11 mm.

[0074] Subsequently, there was no collapse of the polysilicon rod S1 at the end of the initial growth period T2. At the end of the initial growth period T2, the diameter of the polysilicon rod S1 had reached about 30 mm.

[0075] Regarding the obtained polysilicon rod S1, similar to Example 1, the core rod was drilled out and the resistivity in the length direction was determined, which is shown as a1-2 in FIG. 5. The resistivity Xa1-2 of the polysilicon rod S1 with diameter X at the end of the growth start period T1 was a high value of about 940 (Ωcm). Also, the resistivity Ya1-2 of the polysilicon rod S1 at the end of the initial growth period T2 when the diameter of the polysilicon rod S1 reached 30 mm (diameter Y) was about 2050 (Ωcm), and the high resistivity was well maintained.

[0076] 〔Summary〕 The method for manufacturing a polysilicon rod according to Aspect 1 of the present invention is a method for manufacturing a polysilicon rod (S1) in which a raw material gas (G1) containing chlorosilanes is supplied to a silicon core wire that is erected inside a reactor (10) and is heated by energization, and polysilicon is deposited on the surface of the silicon core wire to grow into a polysilicon rod (S1) having a diameter of 80 mm or more. The raw material gas (G1) is introduced into the reactor (10) such that the number of gas exchanges, which is the amount of the raw material gas (G1) introduced into the reactor (10) with respect to the volume of the reactor (10) during the growth start period (T1) of the polysilicon rod until 1 hour has elapsed since the start of polysilicon deposition on the surface of the silicon core wire, is 8 or more and less than 35 times.

[0077] As a result of intensive research, the inventors of the present case have found that by setting the number of gas exchanges of the reactor (10) to 8 or more and less than 35 times per unit time, it is possible to prevent the polysilicon rod (S1) from collapsing during the growth start period (T1) and to improve the specific resistance value of the deposited polysilicon rod (S1).

[0078] Therefore, according to the above configuration, it is possible to prevent the polysilicon rod (S1) from collapsing during the growth start period (T1) and to improve the specific resistance value of the polysilicon rod (S1) deposited during the growth start period (T1).

[0079] The method for manufacturing a polysilicon rod according to Aspect 2 of the present invention may be implemented in the above Aspect 1 in such a manner that during the initial growth period (T2) of the polysilicon rod (S1) until the polysilicon rod (S1) reaches a diameter of 30 mm, which follows after the growth start period (T1) of the polysilicon rod has elapsed, the introduction of the raw material gas (G1) into the reactor (10) is such that (1) the doubling rate of the number of gas exchanges per hour during the initial growth period (T2) of the polysilicon rod is in the range of 0.6 or more and 5.0 or less, and (2) the number of gas exchanges increases to 30 or more and 50 or less in the 1 hour before the diameter of the polysilicon rod (S1) reaches 30 mm.

[0080] At the start of precipitation, since the diameter of the polysilicon rod (S1) is small, increasing the input gas amount may cause the polysilicon rod (S1) to collapse. According to the above configuration, as the polysilicon rod (S1) grows and thickens due to precipitation and its strength increases, the input gas amount can be increased accordingly. Thereby, it is possible to achieve both the prevention of the collapse of the polysilicon rod (S1) and the appropriate precipitation of the polysilicon rod (S1).

[0081] In the method for manufacturing a polysilicon rod according to Embodiment 3 of the present invention, in the above Embodiment 1 or 2, during the growth start period (T1), the source gas (G1) is introduced into the reaction furnace (10) by the supply nozzle (40), and the linear velocity per supply nozzle (40) of the source gas (G1) introduced into the reaction furnace (10) is 40 Nm 3 / (s·m 2 ) or less may be sufficient.

[0082] During the growth start period (T1) of the polysilicon rod (S1), if the linear velocity per supply nozzle (40) of the source gas (G1) introduced into the reaction furnace (10) is too high, it may cause the polysilicon rod (S1) to collapse. According to the above configuration, since the source gas (G1) is introduced at a linear velocity per supply nozzle (40) that can maintain the self - standing of the polysilicon rod (S1), the possibility of the polysilicon rod (S1) collapsing during the growth start period (T1) can be further reduced.

[0083] In the method for manufacturing a polysilicon rod according to Embodiment 4 of the present invention, in any one of the above Embodiments 1 to 3, during the entire growth period (growth period T3) of the polysilicon rod (S1), the maximum value of the number of gas exchanges per hour may be 80 times or more and 100 times or less.

[0084] According to the above configuration, during the entire growth period (growth period T3) of the polysilicon rod, the source gas (G1) can be introduced into the reaction furnace (10) so that the polysilicon rod (S1) does not collapse.

[0085] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, by combining the technical means disclosed in each embodiment, new technical features can be formed.

Explanation of Reference Numerals

[0086] 1 Manufacturing apparatus 10 Reactor 40 Supply nozzle G1 Source gas S1 Polysilicon rod T1 Growth start period T2 Early growth period T3 Growth period (total growth period)

Claims

1. A method for producing a polysilicon rod, comprising the steps of: supplying a source gas containing chlorosilanes to a silicon core wire which is vertically installed in a reactor and electrically heated, thereby depositing polysilicon on a surface of the silicon core wire, and growing the silicon core wire into a polysilicon rod having a diameter of 80 mm or more, the method comprising the steps of: A method for manufacturing a polysilicon rod, comprising: feeding the raw material gas into the reaction furnace so that the number of gas exchanges, which is the amount of raw material gas fed into the reaction furnace relative to the volume of the reaction furnace, is 8 times or more and less than 35 times during a period during which the growth of the polysilicon rod begins from the start of precipitation of polysilicon on the surface of the silicon core wire until one hour has elapsed.

2. 2. The method for producing a polysilicon rod according to claim 1, wherein, during an initial growth period of the polysilicon rod following the elapse of a growth start period of the polysilicon rod until the diameter of the polysilicon rod reaches 30 mm, the supply of the raw material gas into the reaction furnace is carried out in such a manner that (1) an increase rate of the number of gas exchanges per hour during the initial growth period is within a range of 0.6 to 5.0, and (2) the number of gas exchanges increases to 30 times or more and 50 times or less during the hour before the diameter of the polysilicon rod reaches 30 mm.

3. During the growth initiation period, the source gas is introduced into the reaction furnace through a supply nozzle; The linear velocity of the raw material gas fed into the reactor per the supply nozzle is 40 Nm ３ / (s.m. ２ 3. The method for producing a polysilicon rod according to claim 1, wherein the average particle diameter is 100 nm or less.

4. 3. The method for producing a polysilicon rod according to claim 1, wherein the maximum number of gas exchanges per hour is 80 to 100 times during the entire growth period of the polysilicon rod.

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