JP6287991B2 - Silicon single crystal growth equipment - Google Patents

Description

  The present invention relates to an apparatus for growing a silicon single crystal by the Czochralski (CZ) method.

  In recent years, with high integration of devices, high quality requirements for silicon single crystal wafers have become strict. The high quality requirement means that there are few or no defects near the wafer surface where the device operates. Wafers that can achieve these include epitaxial wafers, annealed wafers, defect-free crystal PW (polished wafers), and the like.

  On the other hand, there is a demand for cost reduction. Epitaxial wafers and annealed wafers add an additional process to PW and are generally expensive. A low defect / defect-free crystal PW obtained by polishing (polishing) a crystal grown while controlling defects during crystal growth can satisfy high quality requirements at a relatively low cost. For this reason, there is an increasing demand for low-defect crystals PW with reduced Grown-in defects and defect-free crystals PW with no Grown-in defects.

  The Grown-in defect is a defect formed by aggregating point defects during crystal growth. There are two types of point defects: Vacancy (vacancies) in which Si atoms at lattice points are missing, and Interstitial-Si (interstitial Si) in which Si atoms enter between lattices. The formation state of the grown-in defect varies depending on the growth rate of the single crystal and the cooling conditions of the single crystal pulled from the silicon melt. For example, it is known that vacancy becomes dominant when a single crystal is grown at a relatively high growth rate. A collection of this vacancy is called a void defect, and the name differs depending on how it is detected. Detected as When these defects are taken into the oxide film formed on the silicon substrate, it is considered that the breakdown voltage of the oxide film is caused.

  On the other hand, when a single crystal is grown at a relatively low growth rate, it is known that Interstitial-Si (hereinafter sometimes referred to as I-Si) becomes dominant. When this I-Si aggregates, LEP (Large Etch Pit), which is considered to be a cluster of dislocation loops, is detected. It is said that when a device is formed in a region where this dislocation cluster defect occurs, a serious failure such as current leakage occurs.

  Therefore, when the crystal is grown under an intermediate condition between the vacancy dominant condition and the I-Si dominant condition, there is no vacancy or I-Si, or no void defect or dislocation cluster defect is formed. A defect-free region that is present in only a small amount is obtained. Such a method for growing defect-free crystals is disclosed in, for example, Patent Document 1. Specifically, a defect-free crystal can be obtained by controlling the ratio (V / G) between the temperature gradient G and the crystal growth rate V at the crystal growth interface. If V / G is large, Vacancy concentration is dominant, and if V / G is small, I-Si is dominant. Therefore, by controlling to V / G where Vacancy excess amount and I-Si excess amount antagonize, point defect Therefore, the growth amount of grown-in defects is prevented from growing.

  However, in general, in order to prevent the growth of Grown-in defects, precise control is required, and the growth rate is also reduced. For this reason, the cost is generally high. Therefore, a technique is disclosed in which a void defect is generated by growing a crystal at a high speed capable of reducing the cost of the crystal, and this is eliminated. Patent Document 2 discloses a method of filling a void defect by injecting I-Si from the surface after oxygen is diffused out of the wafer surface layer by oxidizing the wafer cut from the crystal after non-oxidizing treatment. Is disclosed.

  Since the void defect is an assembly of vacancy, it is a defect with a hole in the crystal. It is known that an oxide film called an inner wall oxide film exists inside the hole. In the above-described technique, first, non-oxidizing heat treatment is performed, oxygen is diffused outward to reduce the oxygen concentration, and the inner wall oxide film is dissolved in an oxygen-deficient state. After the inner wall oxide film is dissolved, an oxidation process is performed, and an oxide film is formed on the surface, so that I-Si is injected, and void holes without the inner wall oxide film are filled back with I-Si. Has disappeared.

  Further, Patent Document 3 discloses that the void defect disappears only by oxidation treatment at 1200 ° C. or lower in the case of a low oxygen concentration. If the oxygen concentration is low, by setting the oxygen concentration higher than the temperature at which the equilibrium concentration is reached, the oxygen deficiency occurs, and the inner wall oxide film of the void defect is dissolved. It is disclosed that I-Si injected from the surface by oxidation reaches and void defects disappear.

  Further, in Patent Document 4, this technique is applied to oxidize a low-oxygen product wafer to eliminate void defects. However, all of these techniques are techniques in which a wafer is cut out from a crystal and then processed using a heat treatment furnace. Since these processes are steps different from the crystal growth, there is a problem that an additional cost is required and the cost is high.

  Further, claim 15 of Patent Document 5 describes that “the ingot is exposed to an oxygen atmosphere while maintaining a temperature higher than the temperature at which aggregation of intrinsic point defects occurs”. However, no specific method is mentioned, and it is presumed from the claims 12 and the like that it is separated and oxidized after the pulling. That is, the main purpose is to perform ingot heat treatment separately after the crystal growth, and eventually the cost for the additional process is increased.

JP-A-11-147786 WO2000 / 12786 WO2004 / 073057 JP 2006-344823 A JP-T-2003-517412 JP-A-6-56572 JP 2000-335995 A JP 2004-182525 A

  If the above-described oxidation treatment can be performed at the time of crystal growth, the grown-in defects can be eliminated (or not generated) at the same time as the crystal growth.

  Generally, many carbon parts are used in the CZ furnace. In the HZ (hot zone) region containing many carbon parts, when oxygen is mixed, the carbon material is oxidized and becomes brittle, and eventually becomes ash. Therefore, carbon parts cannot be exposed to an oxidizing atmosphere at high temperatures. For this reason, in general, an oxygen atmosphere is not used in the CZ method, and Patent Documents 6-8 are to some extent as prior art.

  The technique disclosed in Patent Document 6 introduces an oxidizing gas into the crucible before crystal growth. In Patent Document 7, only the Marangoni convection is confirmed by the oxygen-containing atmosphere CZ method, and the crystal grows. Not. In Patent Document 8, the main purpose is to introduce hydrogen gas. As described above, in general, it is not possible to make the oxygen-containing atmosphere in the chamber of the single crystal growth apparatus by the CZ method in terms of deterioration of components in the HZ region.

  The present invention has been made in view of the above problems, and in a silicon single crystal growth apparatus using the CZ method, it is possible to control defects in a silicon single crystal to be grown without deteriorating components in the HZ region. An object of the present invention is to provide a silicon single crystal growth apparatus that can be used.

In order to achieve the above object, the present invention has grown at least as a main chamber for storing a crucible for containing a raw material melt and a heater for heating and maintaining the raw material melt, and an upper part of the main chamber. A silicon single crystal growing apparatus by the Czochralski method having a pulling chamber in which a silicon single crystal is pulled up and accommodated,
The silicon single crystal growing apparatus has a first gas introduction port for introducing the first gas into the pulling chamber so that the atmosphere on the pulling chamber side is set as the first gas during pulling of the silicon single crystal. A first gas discharge port provided below the first gas introduction port, and
The silicon single crystal growing apparatus introduces the second gas into the main chamber so that the atmosphere on the main chamber side is a second gas different from the first gas during the pulling of the silicon single crystal. There is provided a silicon single crystal growth apparatus having a second gas inlet and a second gas outlet provided below the second gas inlet.

  Thus, if the silicon single crystal growth apparatus is capable of setting the atmosphere on the pulling chamber side as the first gas and the atmosphere on the main chamber side as the second gas, the components in the HZ region of the silicon single crystal growth apparatus are deteriorated. Without defects, defects in the silicon single crystal grown in a desired atmosphere can be controlled.

At this time, the silicon single crystal growing apparatus further includes:
It is preferable to have a cylindrical rectifying tube provided around the silicon single crystal to be grown and extending downward from the ceiling of the main chamber.

  By providing such a rectifying cylinder, the flow of gas around the grown silicon single crystal can be controlled, and the oxidizing silicon gas evaporated from the raw material melt can be effectively discharged, and the first gas And the second gas can be easily separated from each other.

At this time, the silicon single crystal growing apparatus further includes:
A gas separation plate or a gas separation brush is provided between the first gas discharge port and the second gas introduction port,
The gas separation plate and the gas separation brush are preferably made of at least one of quartz material, carbon material, silicon carbide, refractory metal, and ceramics.

  Thus, by providing the gas separation plate or the gas separation brush, the atmosphere of the first gas and the atmosphere of the second gas can be more effectively separated, and the second gas introduced from the second gas introduction port is Inhalation into the first gas discharge port can be prevented, and the atmosphere on the main chamber side can be reliably set to the second gas. In addition, if the gas separation plate and the gas separation brush are made of the materials as described above, they are stable even when exposed to high temperatures, and deterioration can hardly occur.

At this time, the silicon single crystal growing apparatus further includes:
It is preferable to have a mechanism for forming an air curtain with an inert gas between the first gas discharge port and the second gas introduction port.

  Thus, if the mechanism for forming the air curtain is provided, the first gas discharge port and the second gas introduction port are more reliably separated, and the second gas is prevented from being sucked into the first gas discharge port. Therefore, the atmosphere on the main chamber side can be reliably set to the second gas.

  At this time, the second gas is preferably an inert gas.

  Thus, if the second gas is an inert gas, heaters, crucibles, and other carbon material parts are not deteriorated by oxidation or the like, and can be used for a long time.

  At this time, the first gas is preferably an oxidizing gas.

  In this way, by using the first gas as an oxidizing gas, the atmosphere on the pulling chamber side can be used as an oxidizing gas. By oxidizing the surface of the grown silicon single crystal, I-Si implantation or the like can be performed. The Grown-in defect can be controlled.

  At this time, it is preferable that the temperature of the central portion of the silicon single crystal having the same height as the first gas discharge port is 900 ° C. or higher and 1300 ° C. or lower.

  Within such a temperature range, the grown-in defect can be effectively controlled, and deterioration of the components in the HZ region can be suppressed.

  At this time, it is preferable that the first gas has an oxygen content of 0.1% or more and 100% or less in a flow rate ratio, and components other than oxygen are inert gases.

  Within such a range of oxygen content, the surface of the silicon single crystal to be grown can be reliably oxidized, and defects in the silicon single crystal can be controlled.

  As described above, according to the present invention, it is possible to control defects in a grown silicon single crystal without requiring an additional heat treatment step after the growth of the silicon single crystal and suppressing deterioration of components in the HZ region. it can.

It is the schematic which shows an example (Example 1) of the silicon single crystal growth apparatus of this invention. It is the schematic of a collection pipe ((a)) and a supply pipe | tube ((b)). It is the schematic which shows the silicon single crystal growth apparatus (Example 2) of this invention provided with the gas separation board. It is the schematic which shows the silicon single crystal growth apparatus of this invention provided with the gas separation brush. It is the schematic which shows the silicon single crystal growth apparatus of this invention provided with the air curtain formation mechanism. It is the schematic which shows an example (comparative example 1) of the conventional silicon single crystal growth apparatus.

    Hereinafter, the present invention will be described in more detail.

  As described above, there is a demand for a silicon single crystal growing apparatus that can control defects in a silicon single crystal to be grown in a silicon single crystal growing apparatus using the Czochralski method.

As a result of intensive studies to achieve the above object, the inventors of the present invention are silicon single crystal growth apparatuses based on the Czochralski method,
A first gas introduction port for introducing the first gas into the pulling chamber and a lower portion of the first gas introduction port so that the atmosphere on the pulling chamber side is the first gas during the pulling of the silicon single crystal. Having a first gas outlet, and
A second gas introduction port for introducing the second gas into the main chamber and a second gas provided below the second gas introduction port so that the atmosphere on the main chamber side is a second gas different from the first gas. It has been found that a silicon single crystal growth apparatus characterized by having a gas discharge port can solve the above-mentioned problems, and has completed the present invention.

  Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.

  First, referring to FIG. 1, a silicon single crystal growing apparatus of the present invention will be described. FIG. 1 is a schematic view showing an example of an apparatus for growing a silicon single crystal by the CZ method of the present invention. Although FIG. 1 illustrates the silicon single crystal growth apparatus 100 by the CZ method, the present invention can also be applied to a silicon single crystal growth apparatus by the magnetic field application Czochralski method (MCZ method).

  A silicon single crystal growing apparatus 100 shown in FIG. 1 includes a main chamber 1 and a pulling chamber 2. In the main chamber 1, a quartz crucible 5 for storing the raw material melt 4, a graphite crucible 6 for supporting the quartz crucible 5, a heater 7, a heat insulating member 8 and the like are stored. On the other hand, the grown silicon single crystal 3 is pulled up and accommodated in the pulling chamber 2.

  The silicon single crystal growth apparatus 100 is provided around the silicon single crystal 3 to be grown, and extends downward from the ceiling of the main chamber 1, and has a substantially cylindrical flow straightening tube 9 that controls the gas flow. Is provided. Further, during the pulling of the silicon single crystal 3, a first gas introduction port 10 for introducing the first gas into the upper portion of the pulling chamber 2 and the first gas so that the atmosphere on the pulling chamber 2 side becomes the first gas. A first gas exhaust port 12 is provided for exhausting the first gas introduced from the introduction port 10 and flowing around the low temperature portion of the silicon single crystal 3 into the rectifying cylinder 9 or upstream from the rectifying cylinder 9.

  Furthermore, the silicon single crystal growing apparatus 100 introduces the second gas into the main chamber 1 so that the atmosphere on the main chamber 1 side is a second gas different from the first gas during the pulling of the silicon single crystal 3. A second gas inlet 14 and a second gas outlet 15 provided in the lower part of the main chamber 1 below the second gas inlet 14.

  Here, the flow of gas in a general silicon single crystal growing apparatus will be described with reference to FIG.

  FIG. 6 is a schematic view of a conventional silicon single crystal growth apparatus 500 using the CZ method. A gas inlet 51 is provided in the upper part of the chamber 50 of the silicon single crystal growth apparatus 500, and a gas outlet 52 is provided in the lower part of the chamber 50. A desired gas is supplied from the gas inlet 51, and the gas outlet 52 is exhausted by a vacuum pump (not shown). In the chamber 50, there is a raw material melt 54 which is a silicon melt in a quartz crucible 55, and the oxidizing silicon gas is evaporated from the raw material melt 54 containing oxygen eluted from the quartz crucible.

  This oxidizing silicon gas does not have a strong oxidizing power that oxidizes and weakens the carbon members in the furnace, but if it is not discharged outside the furnace, it accumulates as silicon oxide on the carbon parts in the furnace. It can no longer be used. Therefore, the inert gas introduced from the gas introduction port 51 flows down around the crystal, and further flows over the surface of the raw material melt 54 in the quartz crucible 55 and rises along the crucible wall. A gas flow is formed that passes by the side and leads to a gas outlet 52 connected to a vacuum pump. This flow makes it possible to discharge the oxidizing silicon gas outside the furnace. The heat shield member 58 cuts off radiation from the raw material melt 54 and keeps the surface of the raw material melt 54 warm.

  On the other hand, in the silicon single crystal growth apparatus 100 of the present invention schematically shown in FIG. 1, the oxidizing silicon gas evaporated from the raw material melt 4 is combined with the second gas supplied from the second gas inlet 14. While being led to the second gas discharge port 15 at the lower part of the main chamber 1, a part is also led to the first gas discharge port 12. On the other hand, the first gas supplied from the first gas inlet 10 at the top of the pulling chamber 2 is discharged from the first gas outlet 12. This makes it possible to make the atmosphere of the second gas on the main chamber 1 side storing the heater 7 and the quartz crucible 5 different from the atmosphere of the first gas on the pulling chamber 2 side. The apparatus having such a configuration can control the crystal defects as described above. In FIG. 1, the heat shield member is not installed at the tip of the rectifying cylinder, but a configuration in which the heat shield member is installed is of course applicable.

  At this time, the first gas discharge port 12 is connected to a first gas pickup tube 11 in which a plurality of holes 22 are provided at equal intervals in a ring-shaped tube 21 as shown in FIG. It is possible to uniformly collect the atmosphere of the first gas on the side. Further, the second gas introduction port 14 is also connected to a second gas supply pipe 13 in which a plurality of holes 26 are provided at equal intervals in a ring-shaped pipe 25 as shown in FIG. It is possible to supply the second gas evenly.

  Next, another silicon single crystal growth apparatus of the present invention will be described with reference to FIG.

  In the silicon single crystal growth apparatus 100 illustrated in FIG. 1, the first gas discharge port 12 (and the first gas collection tube 11) and the second gas introduction port 14 (and the second gas supply tube 13) are separated from each other. However, depending on the design, the first gas outlet 32 and the second gas inlet 34 may be close to each other as in the silicon single crystal growth apparatus 130 shown in FIG. In such a case, by separating the two, it is possible to prevent the second gas introduced from the second gas inlet 34 from being sucked into the first gas outlet 32, and the raw material melt The oxidizing silicon gas evaporating from 4 can be exhausted without problems. As a specific separation means, a gas separation plate 36 as shown in FIG. 3 can be provided between the first gas discharge port 32 and the second gas introduction port 34. In FIG. 3, a first gas collection pipe 31 is connected to the first gas discharge port 32, and a second gas supply pipe 33 is connected to the second gas introduction port 34. The first gas collection pipe 31 and the second gas supply pipe 33 have the same structure as that shown in FIGS.

  Further, instead of the gas separation plate 36 shown in FIG. 3, between the first gas exhaust port 32 and the second gas introduction port 34, as in still another silicon single crystal growth apparatus 150 of the present invention shown in FIG. 4. In addition, a structure in which a gas separation brush 37 is provided may be employed. The gas separation brush 37 may have a brush-like structure by disposing a fibrous member inside the ring-shaped member.

  At this time, since these members (the gas separation plate 36 and the gas separation brush 37) are exposed to high temperatures, quartz materials, carbon materials, silicon carbide, and high melting point metals such as molybdenum, tungsten, and titanium, which are stable at high temperatures, Furthermore, it is preferable to use ceramics that are stable at high temperatures such as boron nitride and alumina. Further, for the member exposed to the oxidizing atmosphere, it is preferable to select and use a material resistant to oxidation in consideration of the use temperature and the oxidation resistance characteristics of each material.

  Further, as another separation means, a mechanism for forming an air curtain with an inert gas such as Ar may be provided between the first gas discharge port 32 and the second gas introduction port 34. Specifically, a plurality of holes are provided inside the ring-shaped tube as in another silicon single crystal growth apparatus 170 of the present invention shown in FIG. 5, and an inert gas is directed toward the silicon single crystal 3. An ejecting air curtain forming mechanism 38 can be used. The air curtain forming mechanism 38 can have a structure in which a large number of holes are provided inside the ring-shaped tube, like the gas collection tube and the gas supply tube shown in FIG. The effect of separating the atmosphere can be further enhanced. The air curtain forming mechanism 38 can also be used in combination with the gas separation plate 36 and the gas separation brush 37.

  Next, features for operating the silicon single crystal growth apparatus of the present invention will be described. In the silicon single crystal growth apparatus (100, 130, 150, 170) of the present invention, the gas atmosphere on the main chamber 1 side in which the heater 7 and the quartz crucible 5 are housed is made an inert gas during single crystal pulling. preferable. For this reason, it is preferable that the second gas introduced into the main chamber 1 from the second gas introduction port (14, 34) is an inert gas. If it is an inert gas such as Ar gas that is often used in a conventional single crystal growth apparatus by the CZ method, the heater 7, the quartz crucible 5, and other carbon material parts are deteriorated by oxidation or the like. As usual, it can be used for a long time.

  Moreover, it is preferable that the first gas introduced into the pulling chamber 2 from the first gas inlet 10 is an oxidizing gas so that the atmosphere on the pulling chamber 2 side is the first gas. By setting the atmosphere on the side of the pulling chamber 2 to be an oxidizing gas atmosphere, it is possible to control the grown-in defects by I-Si implantation as described above.

  As a defect control by the atmosphere of the first gas on the pulling chamber 2 side, in addition to the implantation of I-Si by the oxidizing gas, it is also possible to inject the vacancy as a nitriding atmosphere such as nitrogen gas or ammonia gas It is.

  Moreover, it is preferable that the temperature of the center part of the silicon single crystal having the same height as the first gas discharge port (12, 32) is 900 ° C. or higher and 1300 ° C. or lower.

  Grown-in defects are formed by the diffusion of point defects. For this reason, if the I-Si implantation is performed at a temperature higher than the temperature at which the void defect is formed, the void defect itself is not formed. Therefore, it is preferable to change the atmosphere from the second gas to the first gas at a higher temperature. However, if the inert gas atmosphere is not used in the vicinity of the carbon member, the parts deteriorate, so an inert gas atmosphere is desired in the vicinity of the crystal growth interface. At this time, if the temperature is 1300 ° C. or lower, the deterioration of components in the HZ region hardly occurs. Therefore, the change in the atmosphere between the first gas outlet and the second gas inlet is preferably on the lower temperature side than about 1300 ° C.

  On the other hand, control of the Grown-in defect is performed by diffusion of point defects. Therefore, the effect is reduced when the diffusion coefficient of point defects is small. Although the diffusion coefficient of point defects varies depending on reports, if it is an I-Si diffusion coefficient, it will decrease by 1 to 3 digits at 900 ° C compared to 1300 ° C. Therefore, it is preferable that the temperature of the central portion of the silicon single crystal having the same height as the first gas discharge port is 900 ° C. or higher at which a point defect diffusion effect can be sufficiently obtained. At this time, for example, as shown in FIG. 1, the temperature of the central portion of the silicon single crystal having the same height as the first gas discharge port 12 is set to 900 ° C. or more by increasing the diameter of the rectifying cylinder 9 as compared with the conventional one. Can do.

  As described above, with respect to the grown-in defect, it is preferable that the temperature of the central portion of the silicon single crystal having the same height as the first gas exhaust port (12, 32) is 900 ° C. or higher and 1300 ° C. or lower. . However, when the target defect is an oxygen precipitate such as BMD (Bulk Micro Defect), the temperature of the central portion of the silicon single crystal having the same height as the first gas discharge port (12, 32) is 400 ° C. The temperature can be set to a relatively low temperature of 900 ° C. or lower.

  Moreover, it is preferable that oxygen content is 0.1% or more and 100% or less by 1st gas, and components other than oxygen are inert gas in 1st gas.

  The purpose of oxidation is to oxidize the surface of the silicon single crystal 3 and implant I-Si. For oxidation, the higher the oxygen concentration, the more effective. However, even if the atmosphere is switched between the pulling chamber 2 side and the main chamber 1 side, there is a possibility that a slight amount of oxidizing gas leaks. Therefore, it is preferable that the oxygen concentration is low in terms of deterioration of the carbon member. Actually, the surface of the silicon single crystal 3 was sufficiently oxidized even when the oxygen concentration was low. Therefore, if oxygen is mixed even at 0.1%, the effect of defect control by the implantation of I-Si is sufficiently exhibited.

Further, in order to implant or eliminate the void defect by injecting I-Si, it is more effective to grow the silicon single crystal 3 under the condition that the void defect does not become large. Doping nitrogen into the silicon single crystal 3 has an effect of reducing void defects, so doping with nitrogen is more preferable. The concentration at which the void defect reduction effect due to nitrogen is exerted is preferably 1 × 10 ¹¹ atoms / cm ³ or more, but when it exceeds 5 × 10 ¹⁵ atoms / cm ³ , the silicon single crystal 3 is dislocated due to approaching the solid solution limit. End up. Therefore, the nitrogen concentration in the silicon single crystal 3 is preferably 1 × 10 ¹¹ atoms / cm ³ or more and 5 × 10 ¹⁵ atoms / cm ³ or less.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.

Example 1
A silicon single crystal 3 was grown using the silicon single crystal growth apparatus 100 of the present invention shown in FIG. At this time, a horizontal magnetic field was applied so that the maximum magnetic field intensity on the crystal central axis was 4000 G. As shown in FIGS. 2A and 2B, the first gas discharge port 12 and the second gas introduction port 14 have the same gas discharge and supply in the cross section of the silicon single crystal growth apparatus 100. The first gas collecting pipe 11 and the second gas supply pipe 13 are provided in which a plurality of holes (22, 26) are provided at equal intervals in the ring-shaped pipe (21, 25). Since the first gas collection pipe 11 and the second gas supply pipe 13 are in close contact with the water-cooled chamber, the temperature of the pipe itself is kept relatively low. Then, Ar gas containing 3% oxygen was supplied from the first gas supply port 10. On the other hand, 100% Ar gas was supplied from the second gas inlet 14. The temperature at the center of the crystal at the same height as the first gas collection tube 11 connected to the first gas discharge port 12 was about 1170 ° C. when analyzed by the comprehensive heat transfer analysis software FEMAG.

Using this silicon single crystal growing apparatus 100, an average crystal growth rate was about 1.0 mm / min, and a silicon single crystal having a diameter of about 10.5 cm was grown with a length of the straight body of about 100 cm. As confirmed after the operation, the carbon material parts in the furnace were not oxidized. The oxygen concentration of the grown silicon single crystal was about 4 × 10 ¹⁷ atoms / cm ³ (ASTM'79). Next, this single crystal was cut into round pieces, and wafer-like samples were cut out from several places. Each sample was ground and then mirror etched with a mixed acid composed of hydrofluoric acid, nitric acid, and acetic acid. Further, the sample was immersed in a selective etching solution composed of hydrofluoric acid, nitric acid, acetic acid, and water, and the sample was left without swinging until the machining allowance by etching became 25 ± 3 μm on both sides to perform selective etching.

  Then, as a result of observing the sample which performed selective etching with the optical microscope, FPD was detected only in the center part of each sample. The diameter at which FPD was detected was about 3 to 6 cm, although it varied depending on the sample. From this, it was found that a certain range of void defects disappeared from the periphery of the sample. In the silicon single crystal pulling process, if the temperature history of high temperature is devised to extend the diffusion time of point defects (I-Si) or the conditions such as oxidation to higher temperatures are tuned, the void defects on the entire surface It was speculated that it could disappear.

(Example 2)
As shown in FIG. 3, the silicon single crystal growth apparatus 130 of the present invention equipped with a quartz gas separation plate 36 as shown in FIG. 3 is used in the single crystal growth apparatus used in Example 1, and the nitrogen concentration in the single crystal is A silicon single crystal was grown under the same conditions as in Example 1 except that nitrogen was doped so as to be in the range of 3 × 10 ¹³ atoms / cm ³ to 6 × 10 ¹³ atoms / cm ³ . When the gas separation plate 36 was confirmed after growing the single crystal, no deterioration due to the oxidizing gas was observed. The diameter of the grown silicon single crystal, the length of the straight body, and the actual values of the oxygen concentration were almost the same as those in Example 1.

  A sample was cut out from this silicon single crystal, the same processing as in Example 1 was performed, and then the FPD inspection was performed under the same conditions as in Example 1. As a result, FPD was not detected in all of the samples cut out from any position. It is considered that both the effects of suppressing the growth of void defects by nitrogen doping and the effect of implantation of I-Si by the oxidation contributed.

(Comparative Example 1)
A silicon single crystal was grown using the conventional silicon single crystal growth apparatus 500 shown in FIG. At this time, a horizontal magnetic field was applied so that the maximum magnetic field intensity on the crystal central axis was 4000 G, and the atmospheric gas was 100% Ar gas. Compared with the silicon single crystal growth apparatus 100 shown in FIG. 1, the silicon single crystal growth apparatus 500 has a large temperature gradient at the crystal growth interface, so that V / G is the same as in the first and second embodiments. A crystal having a diameter of about 10.5 cm was grown with a length of the straight body portion of about 100 cm at an average crystal growth rate of about 1.2 mm / min, which is faster than that of Example 1. A sample was cut out from this silicon single crystal, and FPD inspection was performed in the same manner as in Example 1. As a result, FPD was detected in all of the samples cut out from any position. Due to jigs and unevenness during etching, FPD observation at the outermost periphery may lack accuracy, but it is confirmed that FPD exists at least in the region from the outer periphery of the sample to 1.5 cm. It was done.

  Thus, when the silicon single crystal was grown using the silicon single crystal growth apparatus of the present invention, no defects were detected or defects were generated only in a very limited region in the center. . On the other hand, when a silicon single crystal was grown using a conventional silicon single crystal growth apparatus, defects were generated on the entire surface.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as 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.

1 ... main chamber, 2 ... pulling chamber, 3 ... silicon single crystal,
4 ... Raw material melt, 5 ... Quartz crucible, 6 ... Graphite crucible, 7 ... Heater,
8 ... Insulating member, 9 ... Rectifying cylinder, 10 ... First gas inlet, 11 ... First gas collecting tube,
12 ... 1st gas discharge port, 13 ... 2nd gas supply pipe, 14 ... 2nd gas introduction port,
15 ... second gas discharge port, 21 ... ring-shaped tube, 22 ... hole,
25 ... Ring-shaped tube, 26 ... Hole, 31 ... First gas collection tube,
32 ... 1st gas discharge port, 33 ... 2nd gas supply pipe, 34 ... 2nd gas introduction port,
36 ... Gas separation plate, 37 ... Gas separation brush, 38 ... Air curtain formation mechanism,
50 ... Chamber, 51 ... Gas inlet, 52 ... Gas outlet, 54 ... Raw material melt,
55 ... quartz crucible, 57 ... heater, 58 ... heat shield,
100 ... Silicon single crystal growing device, 130 ... Silicon single crystal growing device,
150 ... Silicon single crystal growth apparatus, 170 ... Silicon single crystal growth apparatus,
500: A conventional silicon single crystal growing apparatus.

Claims (8)

A main chamber for storing at least a crucible for storing the raw material melt and a heater for heating and maintaining the raw material melt; and a pulling chamber connected to the upper portion of the main chamber to pull up and store the grown silicon single crystal A silicon single crystal growing apparatus by the Czochralski method,
The silicon single crystal growing apparatus has a first gas introduction port for introducing the first gas into the pulling chamber so that the atmosphere on the pulling chamber side is set as the first gas during pulling of the silicon single crystal. A first gas discharge port provided below the first gas introduction port, and
The silicon single crystal growing apparatus introduces the second gas into the main chamber so that the atmosphere on the main chamber side is a second gas different from the first gas during the pulling of the silicon single crystal. A silicon single crystal growth apparatus characterized by having a second gas inlet and a second gas outlet provided below the second gas inlet. The silicon single crystal growing apparatus further includes:
2. The silicon single crystal growing apparatus according to claim 1, wherein the silicon single crystal growing apparatus is provided around a silicon single crystal to be grown and has a cylindrical flow straightening tube extending downward from a ceiling portion of the main chamber. . The silicon single crystal growing apparatus further includes:
A gas separation plate or a gas separation brush is provided between the first gas discharge port and the second gas introduction port,
3. The silicon according to claim 1, wherein the gas separation plate and the gas separation brush are made of any one or more of a quartz material, a carbon material, silicon carbide, a refractory metal, and ceramics. Single crystal growth equipment. The silicon single crystal growing apparatus further includes:
4. The apparatus according to claim 1, further comprising a mechanism for forming an air curtain made of an inert gas between the first gas discharge port and the second gas introduction port. 5. The silicon single crystal growing apparatus described.   The silicon single crystal growth apparatus according to any one of claims 1 to 4, wherein the second gas is an inert gas.   6. The silicon single crystal growth apparatus according to claim 1, wherein the first gas is an oxidizing gas.   7. The temperature of the center portion of the silicon single crystal having the same height as the first gas discharge port is 900 ° C. or higher and 1300 ° C. or lower. 7. The silicon single crystal growth apparatus described in 1. 8. The first gas according to claim 1, wherein the first gas has an oxygen content in a flow rate ratio of 0.1% to 100%, and a component other than oxygen is an inert gas. The silicon single crystal growing apparatus according to the item.

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