JP4529976B2 - Method for producing silicon single crystal - Google Patents

Description

The present invention relates to a method and an apparatus for manufacturing a silicon single crystal by the FZ method, and particularly to a method and an apparatus for efficiently manufacturing a silicon single crystal having a high resistivity.

  Conventionally, high resistivity using a silicon single crystal (hereinafter sometimes referred to as FZ single crystal) manufactured by a floating zone (FZ) method for a power device such as a high voltage power device or a thyristor. Silicon wafers have been used. Further, particularly in recent years, semiconductor devices for mobile communication and state-of-the-art C-MOS devices are required to reduce parasitic capacitance. It has been reported that signal transmission loss and parasitic capacitance in a Schottky barrier diode can be effectively reduced by using a high resistivity substrate. Therefore, there is an increasing demand for a high resistivity FZ silicon single crystal wafer having a resistivity of 3000 Ω · cm or more as a substrate used for such device applications.

When a silicon single crystal rod is manufactured by the FZ method, the tip of a polycrystalline silicon raw material rod is melted by high-frequency induction heating using a heater coil or the like in an inert gas atmosphere such as argon and brought into contact with a seed crystal. After acclimation, the partial melting zone (melting part) is usually moved from the lower part of the raw material bar to the upper part to grow a single crystal having the same crystal axis as the seed crystal below the melting part. . At this time, as a doping method of the dopant, argon gas containing phosphine (PH ₃ ) in the case of N-type single crystal and diborane (B ₂ H ₆ ) in the case of P-type single crystal is used by using a nozzle. There is a gas doping method in which the molten portion is blown, and the resistivity of the silicon single crystal can be controlled by this (for example, WOLFGANG KELLER, ALFRED MUHLBAUER, “Floating-zone silicon”, published by MARCEL DEKER INC., Pp. 82). -92).

  Incidentally, the Siemens method is known as a method for producing polycrystalline silicon which is a raw material in the FZ method. In this method, a raw material gas composed of a mixed gas of trichlorosilane and hydrogen is brought into contact with a red-hot polycrystalline silicon core rod, and silicon generated by thermal decomposition of the source gas is deposited on the surface of the core rod, and gradually. This is a manufacturing method in which a polycrystalline silicon rod having a large diameter is grown. In this case, an apparatus is used in which a number of silicon core rods are erected on a sealed bell jar (reactor). A single lot of polycrystalline silicon rods produced by a single reaction in a normal bell jar unit is used.

Conventionally, when a high resistivity FZ silicon single crystal having a resistivity of 3000 Ω · cm or more is used, when the single crystal is grown, the polycrystalline silicon rod produced as described above is used as a raw material rod, such as gas doping. Non-doped single crystal production by FZ method is performed without adding impurities, and the conductivity type and resistivity of the silicon single crystal thus produced are measured and evaluated, and the target conductivity type and resistivity are adapted from the evaluation results. A silicon single crystal was selected and used.

  An object of the present invention is to provide a method and an apparatus for efficiently and stably producing a silicon single crystal having a desired resistivity, particularly 3000 Ω · cm or more.

  In order to achieve the above object, the present invention is a method for producing a silicon single crystal by the FZ method, which is produced based on the measured value after measuring the conductivity type and resistivity of polycrystalline silicon used as a raw material rod in advance. The conductivity type, concentration, and gas flow rate of the dopant gas are determined so that the resistivity of the single crystal is a desired value, and the resistivity silicon having the desired value is obtained by FZ method while gas doping the determined dopant gas. Provided is a method for producing a silicon single crystal, characterized by producing a single crystal.

  Thus, after measuring the conductivity type and resistivity of the polycrystalline silicon used as the raw material rod in advance, the conductivity type of the dopant gas so that the resistivity of the single crystal manufactured based on the measured value becomes a desired value. If the concentration and gas flow rate are determined and the determined dopant gas is gas-doped, even if the resistivity of the silicon single crystal to be manufactured has a desired high resistivity, the target conductivity type and Since the resistivity can be reliably controlled, an efficient and stable high resistivity silicon single crystal can be manufactured.

In this case, the desired value can be 3000 Ω · cm or more.
In this way, even if the resistivity of the silicon single crystal to be manufactured is a high resistivity of 3000 Ω · cm or more in particular, it becomes possible to reliably control the target conductivity type and resistivity. An efficient and stable high resistivity silicon single crystal can be produced.

In this case, the measurement performed in advance is to manufacture a silicon single crystal by the FZ method using polycrystalline silicon of the same lot as the polycrystalline silicon as a raw material rod, and measure the conductivity type and resistivity using the silicon single crystal. It is preferable.
As described above, in the measurement performed in advance, a silicon single crystal is manufactured by the FZ method using polycrystalline silicon of the same lot as the polycrystalline silicon as a raw material rod, and the conductivity type and resistivity are measured using the silicon single crystal. If it carries out, it will become possible to control to the target conductivity type and resistivity more accurately.

In this case, when the resistivity of the polycrystalline silicon measured in advance is higher than the target resistivity of the silicon single crystal to be manufactured, the target resistivity is obtained by gas doping with a dopant having the same conductivity type as that of the polycrystalline silicon. In the case where it is lower, it is preferable to manufacture a silicon single crystal having a desired resistivity by gas doping with a dopant having a conductivity type opposite to that of the polycrystalline silicon.
Thus, when the resistivity of the polycrystalline silicon measured in advance is higher than the target resistivity of the silicon single crystal to be manufactured, the dopant of the same conductivity type as that of the polycrystalline silicon is gas-doped accordingly, The resistivity can be reliably reduced by the amount of doping of the material, and if it is lower than the target resistivity, the dopant of the conductivity type opposite to that of the polycrystalline silicon is gas-doped accordingly, and a very small amount of compensate is used. It is possible to reliably increase the resistivity, and as a result, it is possible to easily and efficiently manufacture a silicon single crystal having a target conductivity type and a desired resistivity, particularly 3000 Ω · cm or more. Become.

The dopant is preferably PH ₃ or B ₂ H _6, and gas doping is preferably performed by spraying a gas containing the dopant from a nozzle close to the FZ melting portion.
Thus, if the dopant is PH ₃ or B ₂ H ₆ and the gas containing the dopant is blown from a nozzle adjacent to the FZ melted portion and gas doping is performed, more excellent resistivity control can be performed. This eliminates the possibility of defective resistivity, and makes it possible to manufacture an extremely stable silicon single crystal.

Moreover, it is preferable to produce a silicon single crystal while introducing an inert gas from above the melting portion and exhausting from below.
In this way, if an inert gas such as argon is introduced from above the melting part and a silicon single crystal is produced while exhausting from below, the dopant gas is blown onto the melting part and gas doping is performed above the melting part. Since it is possible to prevent the dopant from adhering to the surface of the raw material rod, it is possible to stabilize a silicon single crystal having a uniform resistivity distribution in the axial direction of the crystal rod even at a desired value, particularly a high resistivity of 3000 Ω · cm or more Can be manufactured.

Moreover, it is preferable to manufacture a silicon single crystal by installing a gas rectifying cylinder above the melting part.
Thus, if a gas rectification | straightening cylinder is installed above the said fusion | melting part and a silicon single crystal is manufactured, the adhesion of the dopant to the raw material rod surface can be prevented more reliably.

  The present invention is also a method for producing a silicon single crystal by the FZ method, wherein an inert gas is introduced from above the melting portion of FZ and exhausted from below, and a gas containing a dopant is brought close to the melting portion. A silicon single crystal manufacturing method is provided, wherein a silicon single crystal is manufactured by performing gas doping by spraying from a nozzle.

  As described above, if the inert gas is introduced from above the melting part of the FZ and exhausted from below, the gas containing the dopant is blown from the nozzle adjacent to the melting part to perform gas doping, the dopant gas is melted into the melting part. It is possible to prevent dopants from adhering to the surface of the raw material rod above the melted portion when gas doping is performed on the silicon, so that a single crystal with a uniform resistivity distribution in the axial direction of the crystal rod can be stabilized regardless of the resistivity. And can be manufactured efficiently.

In this case, it is preferable to manufacture a silicon single crystal by installing a gas rectifying cylinder above the melting portion.
Thus, if a gas rectification | straightening cylinder is installed above the said fusion | melting part and a silicon single crystal is manufactured, the adhesion prevention of the dopant to the raw material rod surface can be performed more reliably.

  The present invention also relates to an apparatus for producing a silicon single crystal by the FZ method, at least in the vicinity of a molten portion of FZ, and a nozzle for performing gas doping by blowing a gas containing a dopant to the molten portion; An apparatus for producing a silicon single crystal is provided, comprising a gas supply / exhaust mechanism for introducing gas from above the melting portion and exhausting gas from below.

  As described above, at least in the vicinity of the FZ melting portion, a nozzle for performing gas doping by spraying a gas containing a dopant to the melting portion, an inert gas is introduced from above the melting portion, and exhausted from below. If it is an FZ single-crystal manufacturing apparatus provided with the supply / exhaust mechanism for performing this, when dopant gas is sprayed on a fusion | melting part and gas doping is performed, it will be able to prevent that a dopant adheres to the raw material stick | rod surface above a fusion | melting part. Therefore, a silicon single crystal having a uniform resistivity distribution in the axial direction of the crystal rod can be manufactured stably and efficiently regardless of the resistivity.

In this case, it is preferable that a gas rectifying cylinder installed above the melting part is provided.
Thus, if it has a gas baffle installed above the above-mentioned fusion part, it will become a manufacturing device which can perform adhesion prevention of a dopant to a raw material stick surface more certainly.

In accordance with the present invention, after measuring the conductivity type and resistivity of polycrystalline silicon as a raw material rod in advance, the conductivity type of the dopant gas so that the resistivity of the single crystal produced based on the measured value becomes a desired value. If the concentration and gas flow rate are determined and the determined dopant gas is doped, the desired high resistivity silicon single crystal can be produced efficiently and stably.
In addition, according to the present invention, if an inert gas is introduced from above the melting part of FZ and exhausted from below, a gas containing a dopant is blown from a nozzle adjacent to the melting part and gas doping is performed. However, a silicon single crystal having a uniform resistivity distribution in the axial direction of the crystal rod can be stably and efficiently manufactured.
Moreover, the manufacturing apparatus according to the present invention is a manufacturing apparatus capable of stably and efficiently manufacturing a silicon single crystal having a uniform resistivity distribution in the axial direction of the crystal rod regardless of the resistivity.

It is the schematic which shows an example of the FZ single crystal manufacturing apparatus used for manufacture of the silicon single crystal which concerns on this invention. It is the figure which showed the resistivity distribution of the crystal axis direction of Example 1,2. It is the figure which showed the resistivity distribution of the crystal axis direction of Example 3, 4. FIG. It is the figure which showed the resistivity distribution of the crystal axis direction of Example 5, 6. FIG. 6 is a diagram showing a resistivity distribution in a crystal axis direction of Comparative Example 1. FIG. An example of a resistivity histogram when an undoped FZ single crystal having a diameter of 150 mm is manufactured using N-type polycrystalline silicon of a plurality of different lots as a raw material rod is shown.

Hereinafter, the present invention will be described in detail.
As described above, particularly when a high resistivity FZ silicon single crystal having a resistivity of 3000 Ω · cm or more is manufactured, a silicon single crystal is manufactured by a non-doped FZ method from a polycrystalline silicon raw material rod, and thus manufactured. The conductivity type and resistivity of the silicon single crystal were measured and evaluated, and a silicon single crystal suitable for the intended conductivity type and resistivity was selected from the evaluation results and used.

  However, polycrystalline silicon is doped with impurities (dopants) from trichlorosilane, hydrogen, and bell jar during production to determine its conductivity type and resistivity. However, the type and contamination of this dopant are unstable and polycrystalline. Varies between lots that react with silicon. Therefore, after manufacturing an FZ single crystal using this polycrystalline silicon as a raw material rod, the conductivity type and resistivity of the FZ single crystal rod were measured. FIG. 6 shows an example of a resistivity histogram when 301 non-doped N-type FZ single crystals having a diameter of 150 mm are manufactured using polycrystalline silicon of different lots as a raw material rod. Thus, FZ single crystals manufactured from different lots of polycrystalline silicon have extremely large variations in resistivity. For example, when a device with a resistivity of 5000 to 10000 Ω · cm is manufactured, the average resistivity of the silicon wafer (the resistivity of the silicon single crystal) needs to be 6500 to 7700 Ω · cm in consideration of the in-plane resistivity distribution. Only 13% of the total silicon single crystal meets this requirement.

  Therefore, the resistance of the raw material determined by unstable factors at the time of manufacturing, such as manufacturing a number of silicon single crystals in advance and selecting the single crystal that matches the target conductivity type and resistivity from the evaluation results It has become a very low cost, high cost manufacturing method that is rate dependent.

  In addition, when the silicon single crystal is manufactured by the FZ method while controlling the resistivity by gas doping, the resistivity distribution is non-uniform in the axial direction of the crystal rod, and the silicon single crystal having the target resistivity is stably manufactured. There were cases where it was not possible. The reason for this is that a part of the dopant gas sprayed to the melted part adheres to the surface of the raw material rod above the melted part, and the amount of adhesion increases as the crystal growth process proceeds. This was thought to be due to the gradual increase in the amount of dopant produced.

  In view of the recent increase in demand for a high resistivity FZ silicon single crystal having a resistivity of 3000 Ω · cm or more in recent years, the present inventors have developed a material rod for solving the above problems. After preliminarily measuring the conductivity type and resistivity of the crystalline silicon, the conductivity type, concentration, and concentration of the dopant gas are adjusted so that the resistivity of the single crystal produced based on the measured value is a desired value, particularly 3000 Ω · cm or more. The inventors have conceived that if the gas flow rate is determined and the determined dopant gas is doped, the target conductivity type and resistivity can be reliably controlled. In addition, if an inert gas is introduced from above the melting portion of FZ and exhausted from below, and a gas containing a dopant is blown from a nozzle adjacent to the melting portion and gas doping is performed, The inventors have conceived that the dopant can be prevented from adhering to the surface of the raw material rod and completed the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a schematic view showing an example of an FZ single crystal manufacturing apparatus used for manufacturing a silicon single crystal according to the present invention.
The FZ single crystal manufacturing apparatus 1 of the present invention includes at least a dope gas nozzle 22 for performing gas dope and a gas for introducing an inert gas such as argon (Ar) gas into the chamber 26 from above and exhausting it from below. A supply mechanism 28a and an exhaust mechanism 28b are provided. In FIG. 1, the supply mechanism 28 a also supplies the dope gas to the nozzle 22, but it may be supplied separately. Moreover, it is preferable to provide the gas rectification cylinder 24.

Next, a method for producing a silicon single crystal according to the present invention will be described.
First, in the present invention, a silicon single crystal is manufactured by the FZ method. In this case, after measuring in advance the conductivity type and resistivity of polycrystalline silicon used as a raw material rod, the single crystal manufactured based on the measured value The conductivity type, concentration, and gas flow rate of the dopant gas are determined so that the resistivity of the above becomes a desired value, and a silicon single crystal is manufactured by the FZ method while gas doping the determined dopant gas. At this time, a silicon single crystal is preferably manufactured by the FZ method using polycrystalline silicon of the same lot as a raw material rod, and the conductivity type and resistivity are measured using the silicon single crystal.

  Since the resistivity when a non-doped FZ single crystal is manufactured using a polycrystalline silicon rod as a raw material rod is almost the same value between the same lots, as described above, one polycrystalline silicon rod is representatively represented from the same lot. By selecting and measuring the conductivity type and resistivity of the FZ single crystal manufactured using it as the raw material rod, the resistivity when the non-doped FZ single crystal is manufactured using other polycrystalline silicon rods of the same lot as the raw material rod is accurate. Can be predicted. Therefore, when other polycrystalline silicon rods of the same lot are used as raw material rods, the type of gas-doped dopant is determined so as to obtain the target conductivity type and resistivity from the resistivity measurement results, and the dopant concentration and The gas flow rate can be calculated and determined. As a result, it is possible to eliminate the variation in resistivity caused by the influence of the dopant that was originally included in the polycrystalline silicon raw material rod indefinitely.

  Next, the part of the polycrystalline silicon rod where melting starts is processed into a cone shape, and the surface is etched to remove the processing distortion. Thereafter, the silicon raw material rod 2 is set by fixing with screws or the like to the upper holding jig 6 of the upper shaft 4 installed in the chamber 26, and the seed crystal 12 is attached to the lower holding jig 10 of the lower shaft 8.

  Next, the lower end of the cone portion of the silicon raw material rod 2 is preheated with a carbon ring (not shown). Thereafter, an inert gas, for example, Ar gas containing nitrogen gas is supplied from the upper portion of the chamber 26 by the gas supply mechanism 28a, and exhausted by the exhaust mechanism 28b at the lower portion of the chamber 26, for example, the furnace pressure is 0.05 MPa, Ar gas The flow rate is 20-30 l / min, and the nitrogen concentration in the chamber is 0.1-0.5%. After the silicon raw material rod 2 is heated and melted by the induction heating coil (high frequency coil) 14, the tip of the cone portion is fused to the seed crystal 12, the dislocation is made free by the diaphragm 16, and the upper shaft 4 and the lower shaft 8 are rotated. While the silicon raw material rod 2 is lowered at a speed of, for example, 2.3 mm / min, the melting zone (melt) 18 which is a melting part is moved from the lower end to the upper end of the silicon raw material rod, and the zoning is performed. In particular, a silicon single crystal 3 of 3000 Ω · cm or more is grown below the melting zone 18. The growth is performed while gas doping the dopant gas determined as described above.

The gas doping can be performed by blowing a doping gas of the conductivity type, concentration and gas flow determined as described above from the doping gas nozzle 22 adjacent to the FZ melting zone 18 according to a known method. The dopant gas is not limited, but if diborane (B ₂ H ₆ ) or phosphine (PH ₃ ) is used, excellent resistivity control can be performed, and there is no fear of resistivity failure. These dopant gases can be diluted with Ar gas to obtain a dope gas having a predetermined concentration.

  At this time, when the resistivity of the silicon raw material rod 2 measured in advance is higher than the target resistivity of the silicon single crystal to be manufactured, the dopant of the same conductivity type as that of the silicon raw material rod 2 is gas-doped, and when the resistivity is lower than the target resistivity. It is preferable to dope a dopant having a conductivity type opposite to that of the silicon raw material rod 2. For example, when the resistivity of the silicon raw material rod 2 is 5000 Ω · cm or more, an FZ single crystal having a resistivity of 3000 Ω · cm or more can be manufactured by gas doping with a dopant of the same conductivity type. In the case of 1000 Ω · cm or more and less than 3000 Ω · cm, an FZ single crystal having a resistivity of 3000 Ω · cm or more can be produced by gas doping with an opposite conductivity type dopant. In this case, by adjusting the doping amount, the conductivity type of the silicon single crystal can be made the same as or opposite to that of the polycrystalline silicon rod.

Note that when the gas flow in the furnace is supplied from the lower part of the chamber and exhausted from the upper part as in the past, a gas flow is generated from the lower part to the upper part in the chamber, so a part of the dope gas sprayed on the melting zone. Adheres to the surface of the raw material rod above the melting zone, so that when the dopant having the same conductivity type as that of the raw material rod is doped, the resistivity decreases significantly with growth. On the other hand, when compensating with a dopant having a conductivity type opposite to that of the raw material rod, the resistivity rises with growth.
Therefore, as described above, if Ar gas containing nitrogen gas is supplied from above the melting zone 18 at the upper portion of the chamber and exhausted from the lower portion of the chamber, the dope gas will not adhere to the surface of the raw material rod above the melting zone. Therefore, the resistivity distribution in the axial direction can be made uniform.

  Further, if the gas flow straightening cylinder 24 is installed above the melting zone, the flow of gas from the upper side to the lower side is rectified, so that it is possible to more reliably prevent the dopant from adhering to the surface of the raw material rod, and the axial direction The resistivity distribution can be made more uniform.

  When the single crystal is grown, the axis 4 serving as the center of rotation when growing the silicon raw material rod 2 is shifted from the axis 8 serving as the center of rotation of the single crystal of the single crystal during the single crystallization (eccentricity). It is preferable to grow a single crystal. By shifting both the centers in this way, the molten state is agitated during single crystallization, and the quality of the single crystal to be produced can be made uniform, which is preferable. What is necessary is just to set eccentricity according to the diameter of a single crystal, for example.

Further, if the atmosphere in the chamber 26 is filled with nitrogen as described above, the silicon single crystal 3 is doped with nitrogen to prevent crystal defects such as FPD and swirl defects from being formed during the growth of the silicon single crystal 3. This is preferable because a higher quality silicon single crystal can be grown. In this case, it is preferable to set the nitrogen concentration in the atmosphere to 0.1 to 0.5% because nitrogen at a concentration appropriate for preventing the above-described defect formation is doped. Further, instead of nitrogen gas, a compound gas containing nitrogen such as ammonia, hydrazine, or nitrogen trifluoride may be used. At this time, the concentration of nitrogen doped in the silicon single crystal is, for example, about 3 × 10 ¹⁴ atoms / cm ³ .

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto.
Example 1
A single-crystal silicon rod with a diameter of 130 mm was selected, and a silicon single crystal was manufactured by using this as a raw material rod by the non-doped FZ method. The conductivity type and resistivity were measured. The rate was 24200 Ω · cm. Based on this measurement result, by using a polycrystalline silicon rod of the same lot as the polycrystalline silicon rod as a raw material rod, by gas doping of PH ₃ gas (Ar diluted PH ₃ gas) of the same conductivity type as the raw material rod diluted with Ar gas, A silicon single crystal having the same N-type conductivity as the material rod having a diameter of 154 mm and a straight body length of 26 cm and a target resistivity of 7000 Ω · cm was manufactured by the FZ method.

At this time, Ar gas containing nitrogen gas was supplied at 20 l / min from the upper part of the chamber above the melting zone, and exhausted from the lower part of the chamber to set the furnace pressure to 0.05 MPa and the nitrogen concentration to 0.30%.
Then, according to the conditions determined from the measured values, Ar diluted PH ₃ gas of 0.5 cc / min with a concentration of 20 ppm is added to Ar gas at 5000 cc / min so as to have a target conductivity type and resistivity (N type, 7000 Ω · cm). A silicon single crystal was grown by the FZ method at a growth rate of 2.3 mm / min while this mixed gas was sprayed from a nozzle to the melting zone at 500 cc / min to perform gas doping.

  Then, after manufacturing the silicon single crystal, a wafer is taken from a part having a straight body length of 0 cm, 12 cm, and 26 cm, and after heat treatment at 1200 ° C. for 100 minutes in dry oxygen, a 2.5 mm pitch in any two orthogonal directions. Then, the resistivity ρ of all points was measured by a four-probe measurement method, and the axial resistivity distribution was evaluated.

At this time, the resistivity ρ of each part is defined as the average value of all the wafer points in each part, the maximum value of ρ of the part is defined as ρmax, the minimum value is ρmin, and the axial resistivity distribution is defined by the following equation. .
Axial resistivity distribution = (ρmax−ρmin) / ρmin × 100%
Furthermore, the lifetime was also measured at a position of the straight body 26 cm.
As a result, the obtained single crystal was N-type conductivity, the resistivity was 6890-7440 Ω · cm, and the axial resistivity distribution was 8.0% (see FIG. 2). The lifetime was 1000 μsec.

(Example 2)
A silicon single crystal was produced under the same production conditions as in Example 1 except that a gas flow straightening tube was installed, and the same crystal quality characteristics as in Example 1 were evaluated.
As a result, the obtained single crystal was N-type conductivity, the resistivity was 6650-6800 Ω · cm, and the axial resistivity distribution was 2.3% (see FIG. 2). The lifetime was 1000 μsec.

(Example 3)
A single-crystal silicon rod having a diameter of 105 mm was selected from the lot, and a silicon single crystal was manufactured by using this as a raw material rod by the non-doped FZ method, and its conductivity type and resistivity were measured. The rate was 1150 Ω · cm. Based on this measurement result, a polycrystalline silicon rod of the same lot as the polycrystalline silicon rod is used as a raw material rod, and by gas doping of Ar diluted B ₂ H ₆ gas having the opposite conductivity type to that of the raw material rod, a diameter of 105 mm and a straight cylinder length of 105 cm A silicon single crystal having the same N conductivity type as that of the raw material rod and a target resistivity of 7500 Ω · cm was manufactured by the FZ method.

At this time, Ar gas containing nitrogen gas was supplied at a rate of 20 l / min from the upper part of the chamber above the melting zone, and exhausted from the lower part of the chamber to set the furnace pressure to 0.05 MPa and the nitrogen concentration to 0.10%.
Then, in accordance with the conditions determined from the actual measurement values, Ar diluted B ₂ H ₆ gas of 1.0 cc / min at a concentration of 20 ppm was added to Arcc to reach a target conductivity type and resistivity (N type, 7500 Ω · cm). A silicon single crystal was grown by the FZ method at a growth rate of 2.4 mm / min while gas doping was performed by spraying this mixed gas at a rate of 500 cc / min from a nozzle to the melting zone.

And after manufacturing a silicon single crystal, the wafer was extract | collected from the site | part of straight cylinder length 0cm, 30cm, 60cm, 105cm, and the resistivity and axial direction resistivity distribution were evaluated with the same measuring method as Example 1. FIG. The lifetime was also measured at a position of 105 cm in the straight body.
As a result, the obtained single crystal was N-type conductivity, the resistivity was 7125-8150 Ω · cm, and the axial resistivity distribution was 14.4% (see FIG. 3). The lifetime was 800 μsec.

Example 4
A silicon single crystal was produced under the same production conditions as in Example 3 except that a gas flow straightening tube was installed, and the same crystal quality characteristics as in Example 3 were evaluated.
As a result, the obtained single crystal had an N-type conductivity, a resistivity of 7420-8114 Ω · cm, and an axial resistivity distribution of 9.4% (see FIG. 3). The lifetime was 900 μsec.

(Example 5)
A single-crystal silicon rod having a diameter of 105 mm was selected from a lot, and a silicon single crystal was produced by using this as a raw material rod by the non-doped FZ method, and its conductivity type and resistivity were measured. The rate was 2300 Ω · cm. Based on this measurement result, a polycrystalline silicon rod of the same lot as the polycrystalline silicon rod is used as a raw material rod, and a raw material having a diameter of 105 mm and a straight body length of 105 cm is obtained by gas doping of Ar diluted PH ₃ gas having a conductivity type opposite to that of the raw material rod. A silicon single crystal having an N-type conductivity type opposite to the rod and a target resistivity of 7000 Ω · cm was manufactured by the FZ method.

At this time, Ar gas containing nitrogen gas was supplied at a rate of 20 l / min from the upper part of the chamber above the melting zone, and exhausted from the lower part of the chamber to set the furnace pressure to 0.05 MPa and the nitrogen concentration to 0.10%.
Then, in accordance with the conditions determined from the actual measurement values, Ar diluted PH ₃ gas 4.6 cc / min with a concentration of 20 ppm was added to Ar gas 5000 cc / min so as to achieve the target conductivity type and resistivity (N type, 7000 Ω · cm). A silicon single crystal was grown by the FZ method at a growth rate of 2.4 mm / min while gas doping was performed by blowing this mixed gas from a nozzle to the melting zone at 500 cc / min.

And after manufacturing a silicon single crystal, the wafer was extract | collected from the site | part of straight cylinder length 0cm, 30cm, 60cm, 105cm, and the resistivity and axial direction resistivity distribution were evaluated with the same measuring method as Example 1. FIG. The lifetime was also measured at a position of 105 cm in the straight body.
As a result, the obtained single crystal was N-type conductivity, the resistivity was 6620-6930 Ω · cm, and the axial resistivity distribution was 4.7% (see FIG. 4). The lifetime was 1000 μsec.

(Example 6)
A silicon single crystal was produced under the same production conditions as in Example 5 except that a gas flow straightening tube was installed, and the same crystal quality characteristics as in Example 5 were evaluated.
As a result, the obtained single crystal was N-type conductivity, the resistivity was 6920-7140 Ω · cm, and the axial resistivity distribution was 3.2% (see FIG. 4). The lifetime was 900 μsec.

(Comparative Example 1)
Using polycrystalline silicon with a diameter of 130 mm as a raw material rod, the conductivity type and resistivity are not actually measured. By non-doping, a silicon single unit having a diameter of 154 mm and a straight body length of 30 cm and a target resistivity of 7500 Ω · cm is used. Crystals were produced.

At this time, Ar gas containing nitrogen gas was supplied at 30 l / min from the upper part of the chamber above the melting part and exhausted from the lower part of the chamber to set the furnace pressure to 0.05 MPa and the nitrogen concentration to 0.30%.
A silicon single crystal was grown by the FZ method at a growth rate of 2.3 mm / min.

And after manufacturing a silicon single crystal, a wafer was taken from a part having a straight body length of 0 cm, 10 cm, 20 cm, and 30 cm, and the resistivity, axial resistivity distribution, and lifetime were measured in the same manner as in Example 1. .
As a result, the resistivity of the N-type conductivity was 9430 to 10206 Ω · cm, which was a value greatly deviating from the target resistivity. The axial resistivity distribution was 5.9% (see FIG. 5). The lifetime was 900 μsec.
As described above, the resistivity was greatly deviated from the target resistivity, but the axial resistivity distribution was small because Ar gas was supplied from above and exhausted from below.

The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.
For example, when the resistivity of the polycrystalline silicon measured in advance is the same as the target resistivity of the silicon single crystal to be manufactured, the gas flow rate of the dopant gas can be determined to be zero, and the silicon single crystal can be manufactured by the FZ method.

Claims (6)

A method for producing a silicon single crystal by the FZ method, in which the conductivity type and resistivity of the polycrystalline silicon used as a raw material rod are determined by using the polycrystalline silicon of the same lot as the polycrystalline silicon as a raw material rod. The dopant is manufactured so that the resistivity of the single crystal manufactured based on the measured value becomes a desired value after measuring in advance by measuring the conductivity type and the resistivity using the silicon single crystal. A silicon single crystal having a desired resistivity is manufactured by FZ method while determining a conductivity type, a concentration and a gas flow rate of a gas and gas doping the determined dopant gas. Method.   2. The method for producing a silicon single crystal according to claim 1, wherein the desired value is 3000 Ω · cm or more. 3. The method for manufacturing a silicon single crystal according to claim 1 , wherein when the resistivity of the polycrystalline silicon measured in advance is higher than a target resistivity of the silicon single crystal to be manufactured, the same as that of the polycrystalline silicon. A silicon single crystal whose resistivity becomes the desired value by gas doping with a dopant of the conductivity type, and when the dopant is lower than the target resistivity, by gas doping with a dopant of the conductivity type opposite to that of the polycrystalline silicon. A method for producing a silicon single crystal, characterized by comprising: 4. The method for producing a silicon single crystal according to claim 1 , wherein the dopant is PH ₃ or B ₂ H _6, and a gas containing the dopant is supplied from a nozzle close to a fusion zone of FZ. A method for producing a silicon single crystal, characterized by performing gas doping by spraying. 5. The method for producing a silicon single crystal according to claim 1 , wherein the silicon single crystal is produced while introducing an inert gas from above the melting portion and exhausting from below. A method for producing a silicon single crystal. 6. The method of manufacturing a silicon single crystal according to claim 1 , wherein a silicon single crystal is manufactured by installing a gas rectifying cylinder above the melting portion. Manufacturing method.

Images