JP4148059B2 - Graphite heater for single crystal production, single crystal production apparatus and single crystal production method - Google Patents

Description

  The present invention relates to a graphite heater for producing a single crystal used when producing a single crystal by the Czochralski method, a single crystal producing apparatus using the same, and a method for producing a single crystal, and particularly to control crystal defects of a single crystal with high accuracy. In addition, the present invention relates to a single crystal manufacturing graphite heater suitable for manufacturing the single crystal with high production efficiency, a single crystal manufacturing apparatus using the graphite heater, and a single crystal manufacturing method.

  A single crystal used as a substrate of a semiconductor device is, for example, a silicon single crystal, and is mainly manufactured by a Czochralski method (hereinafter abbreviated as CZ method).

  When a single crystal is manufactured by the CZ method, for example, it is manufactured using a single crystal manufacturing apparatus 10 as shown in FIG. The single crystal manufacturing apparatus 10 includes a member for containing and melting a raw material polycrystal such as silicon, a heat insulating member for shutting off heat, and the like. Contained. A pulling chamber 12 extending upward from the ceiling of the main chamber 11 is connected, and a mechanism (not shown) for pulling the single crystal 13 with a wire 14 is provided on the upper portion.

  A quartz crucible 16 for containing the melted raw material melt 15 and a graphite crucible 17 for supporting the quartz crucible 16 are provided in the main chamber 11, and these crucibles 16 and 17 are rotated by a driving mechanism (not shown). The shaft 18 is supported so as to be movable up and down. The driving mechanism of the crucibles 16 and 17 is configured to raise the crucibles 16 and 17 by the amount corresponding to the liquid level drop in order to compensate for the liquid level drop of the raw material melt 15 accompanying the pulling of the single crystal 13.

  A graphite heater 19 for melting the raw material is disposed so as to surround the crucibles 16 and 17. In order to prevent heat from the graphite heater 19 from being directly radiated to the main chamber 11, a heat insulating member 20 is provided outside the graphite heater 19 so as to surround the periphery thereof.

  Further, a cooling cylinder 23 for cooling the pulled single crystal and a graphite cylinder 24 are provided at the lower part thereof, and the single crystal pulled up by cooling gas downstream from the upper part can be cooled. Further, an inner heat insulating tube 25 is provided at the inner lower end of the graphite tube 24 so as to face the raw material melt 15 to cut radiation from the melt surface and to release the radiant heat from the crystal upward. An outer heat insulating material 26 is provided at the lower end of the outer surface so as to face the raw material melt 15 to cut radiation from the melt surface and to keep the raw material melt surface warm.

  A commonly used graphite heater 19 is shown in FIG. The shape of this graphite heater is cylindrical, and is mainly made of isotropic graphite. In the direct current system, which is currently mainstream, two terminal portions 27 are arranged, and the graphite heater 19 is supported by the terminal portions 27. The heat generating part 28 of the graphite heater 19 has two types of slits 29, an upper slit 29 extending downward from the upper end of the heat generating part 28 and a lower slit 30 extending upward from the lower end of the heat generating part 28 so that heat can be generated more efficiently. , 30 are carved from several to several tens of places. Such a graphite heater 19 generates heat mainly from each heat generating slit portion 31 which is a portion between the lower end of the upper slit 29 and the upper end of the lower slit 30 in the heat generating portion 28.

  The raw material lump is accommodated in the quartz crucible 16 arranged in the single crystal manufacturing apparatus shown in FIG. 5 as described above, and the crucible 16 is heated by the graphite heater 19 as described above, so that the raw material in the quartz crucible 16 is obtained. Melt the mass. In this way, the seed crystal 22 fixed by the seed holder 21 connected to the lower end of the wire 14 is deposited on the raw material melt 15 which is the melted raw material lump, and then the seed crystal 22 is rotated. By pulling up, the single crystal 13 having a desired diameter and quality is grown below the seed crystal 22. At this time, after the seed crystal 22 is deposited on the raw material melt 15, so-called seed drawing (necking) is performed in which the diameter is once narrowed to about 3 mm to form a drawn portion, and then the thickening is performed until a desired diameter is obtained. The dislocation-free crystals are pulled up.

  A single crystal manufactured by such a CZ method, for example, a silicon single crystal is mainly used for manufacturing a semiconductor device. In recent years, semiconductor devices have been highly integrated and elements have been miniaturized. As device miniaturization advances, the problem of Grown-in crystal defects introduced during crystal growth becomes more important.

Here, the Grown-in crystal defect will be described.
In a silicon single crystal, when the crystal growth rate is relatively high, grown-in defects such as FPD (Flow Pattern Defect), which are attributed to voids in which vacancy-type point defects are gathered, are present in the entire crystal diameter direction. A region that exists at high density and has these defects is called a V (vacancy) region. When the growth rate is lowered, an OSF (Oxidation Induced Stacking Fault) region is generated in a ring shape from the periphery of the crystal as the growth rate is lowered, and interstitial silicon is gathered outside the ring. Defects such as LEP (Large Etch Pit), which are considered to be caused by dislocation loops, are present at a low density, and a region where these defects are present is called an I (Interstitial) region. Further, when the growth rate is lowered, the OSF ring shrinks to the center of the wafer and disappears, and the entire surface becomes the I region.

  In recent years, it has been discovered that there is an area outside the OSF ring between the V region and the I region, where neither FPD due to vacancies nor LEP due to interstitial silicon exists. This region is called an N (neutral) region. Further, it has been discovered that there is a region where defects detected by the Cu deposition process exist in a part of the N region outside the OSF region.

  These Grown-in defects are considered to be introduced by the parameter V / G, which is the ratio of the pulling rate (V) and the temperature gradient (G) near the solid-liquid interface of the single crystal. (For example, Non-Patent Document 1). That is, the single crystal can be pulled in a desired defect region or a desired defect-free region by adjusting the pulling rate and the temperature gradient so that V / G is constant. However, for example, when a single crystal is pulled up by controlling the pulling speed to a predetermined defect-free region such as the N region, the single crystal grows at a low speed, and thus an increase in manufacturing cost due to a significant decrease in productivity is inevitable. Therefore, in order to reduce the production cost of this single crystal, it is desired to increase the productivity by growing the single crystal at a higher speed. This is theoretically the temperature near the solid-liquid interface of the single crystal. This can be achieved by increasing the gradient (G).

  Conventionally, using a chamber with an effective cooling body and a hot zone structure, and further effectively blocking the radiant heat from the heater, the single crystal being pulled is cooled to near the solid-liquid interface of the single crystal A method has been proposed in which the temperature gradient (G) is increased to achieve high-speed growth (for example, Patent Document 1). These are mainly performed by changing the structure inside the furnace above the surface of the raw material melt contained in the crucible.

In addition, the heat conduction radiation member is placed under the graphite crucible, and the heat consumption of the graphite heater that surrounds the graphite crucible is efficiently obtained by receiving the radiation heat from the graphite heater and transmitting the heat by heat conduction to release the radiation heat toward the crucible. A method has been proposed to achieve high-speed growth by lowering the power and reducing the overall heat quantity, thereby reducing the radiant heat to the silicon single crystal being pulled and increasing the temperature gradient (G) near the solid-liquid interface. (For example, Patent Document 2).
However, it is difficult to say that these methods alone have sufficiently achieved high-speed growth of single crystals, and there is still room for improvement.

International Publication No. 97/21853 Pamphlet JP-A-12-53486 V. V. Voronkov, Journal of Crystal Growth, 59 (1982), 625-643.

  The present invention has been made in view of such a problem. For example, the present invention has a high breakdown voltage and excellent electrical characteristics that exist outside the OSF region and do not have a defect region detected by the Cu deposition process. When a silicon single crystal is pulled up in a predetermined defect-free region such as an N region or in a predetermined defect region, a temperature distribution is controlled with high accuracy to obtain a crystal of a desired quality, and the silicon single crystal is manufactured with high production efficiency. An object of the present invention is to provide a graphite heater for producing a single crystal, a single crystal production apparatus using the same, and a method for producing a single crystal.

The present invention has been made to solve the above-described problem, and includes at least a terminal portion to which an electric current is supplied and a cylindrical heat generating portion by resistance heating so as to surround a crucible containing a raw material melt. A graphite heater used in the case of producing a single crystal by the Czochralski method, wherein the heat generating portion has an upper slit extending downward from its upper end and a lower slit extending upward from its lower end. The upper slit is formed of two types of long and short, and the length of the lower slit is formed of two types of long and short. the number of slits, that provides a single crystal manufacturing graphite heater, characterized in that a modification of the heat generation distribution of the heat generating portion as more than the number of upper slits of said shorter.

  Thus, the length of the upper slit consists of two types of long and short, the length of the lower slit consists of two types of long and short, and the number of the shorter lower slits is the upper upper slit. By changing the heat generation distribution of the heat generating part as a larger number than the number of the above, it is possible to cause vertical convection in the raw material melt from the crucible bottom to the raw material melt surface by the heat generation distribution of the heater itself. . This vertical convection increases the temperature gradient (G) in the vicinity of the solid-liquid interface of the silicon single crystal that is being pulled up, so that the crystal growth interface easily changes to an upwardly convex shape. For example, the growth of a silicon single crystal in the N region High speed can be achieved. Further, by adjusting the convection by the heat generation distribution of the heater, the oxygen concentration in the produced single crystal can be adjusted to a wide range from low oxygen to high oxygen, and a single crystal having a desired oxygen concentration can be produced with high accuracy.

In this case, the number of the shorter bottom slit of, it is not preferable the a short 5 times or less of the range of 2 times the number of slits on the person.

  Thus, the number of the shorter lower slits is in the range of 2 to 5 times the number of the shorter upper slits, so that the surface of the raw material melt from the bottom of the crucible in the raw material melt. It is possible to moderately promote longitudinal convection to the crystal, and to make the temperature gradient (G) in the vicinity of the solid-liquid interface in the crystal substantially uniform in the radial direction. Therefore, the manufacturing margin of the predetermined defect-free region such as the N region can be expanded, and a single crystal of the predetermined defect-free region can be manufactured stably and at high speed.

In this case, the two types of upper slits and lower slits are periodically formed in the circumferential direction, and the heat generation distribution of the heat generating part is a periodic distribution of the high temperature part and the low temperature part in the circumferential direction. it rather preferable, for example, the period of the heating distribution is not preferable that one cycle is 180 °.

  As described above, the two types of upper and lower slits are periodically formed in the circumferential direction, and the heat generation distribution of the heat generating portion is such that the high temperature portion and the low temperature portion are periodically distributed in the circumferential direction. By doing so, convection in the raw material melt can be promoted not only in the vertical direction but also in the circumferential direction.

In this case, the period of the heating distribution period based on the period and lower slits based on slit, it is not preferable in which deviated in a range of more than 45 ° 135 ° or less in the circumferential direction.

  As described above, the period of the heat generation distribution is such that the period based on the upper slit and the period based on the lower slit are shifted in the range of 45 ° to 135 ° in the circumferential direction, so that the melting of the raw material from the crucible bottom. Longitudinal convection toward the surface of the liquid can be further promoted in a helical direction.

In this case, the shorter slit and lower slits on the, it is rather preferable the those from the upper end of the heat generating portion of length shorter than 50% of the length of the lower end, also, the slit on the longer and under slit, it is not preferable from the upper end of the heat generating portion is the length more than 70% of the length of the lower end.

Thus, the shorter upper slit and lower slit have a length shorter than 50% of the length from the upper end to the lower end of the heat generating portion, and the longer upper slit and lower slit. Is a length of 70% or more of the length from the upper end to the lower end of the heat generating portion, and the heat generating slit portions are provided above and below the center line that bisects the heat generating portion in the vertical direction. Easy to distribute.
The shorter upper slit and lower slit have a length of about 10% or more of the length from the upper end to the lower end of the heat generating portion, so that the heat generation efficiency can be maintained. The longer upper slit and lower slit can maintain the strength of the heater body by having a length of about 90% or less of the length from the upper end to the lower end of the heat generating portion.

Furthermore, the present invention provides a single crystal production apparatus comprising at least the above-described graphite heater for producing a single crystal , and also provides a single crystal production method for producing a crystal by the Czochralski method using the single crystal production apparatus. you.

  If a single crystal is manufactured by the CZ method using such a crystal manufacturing apparatus having the single crystal manufacturing heater of the present invention, a high-quality single crystal can be manufactured with high productivity.

  As described above, according to the present invention, for example, a predetermined region such as an N region that exists outside the OSF region and does not have a defect region detected by the Cu deposition process and has a high breakdown voltage and excellent electrical characteristics. When a silicon single crystal is pulled up in a defect-free region or a predetermined defect region, the silicon single crystal can be supplied with high production efficiency.

The present invention will be described below.
In the case of manufacturing a silicon single crystal by the CZ method, the present inventors have found that the convection caused by the temperature distribution of the raw material melt generated when the graphite heater heats the quartz crucible, and the vicinity of the solid-liquid interface of the silicon single crystal being pulled up The simulation analysis by software such as FEMAG and STHAMAS-3D was performed on the relationship with the temperature gradient (G).

  Here, FEMAG is described in the literature (F. Dupret, P. Nicodeme, Y. Ryckmans, P. Waterers, and M. J. Crochet, Int. J. Heat Mass Transfer, 33, 1849 (1990)) and STHAMAS. -3D is comprehensive heat transfer analysis software disclosed in literature (D. Vizman, O. Graebner, G. Mueller, Journal of Crystal Growth, 233, 687-698 (2001)).

  As a result of this simulation analysis, the present inventors have promoted longitudinal convection from the bottom of the graphite crucible toward the surface of the raw material melt, and further promoted this convection in a helical direction with a temperature gradient ( G) was found to be effective in increasing.

  As a means for promoting this longitudinal convection, in addition to a normal graphite heater, a method of installing a bottom heater for heating the raw material melt in the crucible from the bottom of the crucible, or a raw material melt in the crucible A method of installing a two-stage upper and lower graphite heater for heating from above and below is conceivable. However, these methods cannot be expected to provide an economic advantage because the in-furnace facilities become complicated and the power consumption increases. Therefore, the present inventors have promoted the convection in the vertical direction from the bottom of the crucible toward the surface of the raw material melt with a graphite heater alone arranged so as to surround the crucible. It was conceived that if it can be promoted in the direction, a single crystal having the target quality can be produced with good productivity and at low cost, and the present invention has been completed.

Hereinafter, although embodiment of this invention is described, this invention is not limited to these.
In the graphite heater of the present invention, the heat generation distribution of the heat generating portion is not uniformly distributed in the circumferential direction as in the prior art, and one graphite heater generates heat at the top of the crucible or the bottom of the crucible or the crucible R portion. It is designed to have a non-uniform temperature distribution with a distribution peak, and is designed so that the amount of heat generated at the bottom of the crucible or the crucible R portion is higher than the amount of heat generated at the top of the crucible. Is.

  FIG. 1 shows an example of the graphite heater of the present invention. The graphite heater has an upper slit extending downward from the upper end of the heat generating portion 28 and a lower extending upward from the lower end of the heat generating portion so that the current path of the current from the terminal portion 27 has a zigzag shape in the vertical direction at the heat generating portion 28. Slits are provided alternately. The size and arrangement of these slits are changed to change the heat generation distribution of the heat generating portion. For this purpose, four types of slits are provided here. That is, two types of slits, an upper slit A and an upper slit B longer than the upper slit A, are provided as upper slits, and a lower slit C and a lower slit D shorter than the lower slit C are provided as lower slits. Two types of slits were provided.

  Further, the number of lower slits D is designed to be larger than the number of upper slits A. The number of the lower slits D is preferably designed to be in the range of 2 to 5 times the number of the upper slits A. If it is twice or more, since the heating to the crucible bottom or the crucible R part is strong, the convection in the vertical direction from the crucible bottom to the raw material melt surface can be effectively promoted. The effect of increasing the temperature gradient (G) near the solid-liquid interface of the single crystal can be obtained. On the other hand, 5 times is sufficient, and if it exceeds this, the temperature gradient (G) in the vicinity of the solid-liquid interface may not be sufficiently increased due to weak heating to the top of the crucible. Or, because the heating to the crucible R part is strong, the convection becomes too large and the temperature gradient (G) near the solid-liquid interface in the crystal becomes non-uniform in the radial direction, and the growth rate of the single crystal cannot be stably controlled. There is.

  At this time, the upper slit A and the lower slit D are preferably designed to be shorter than 50% of the length from the upper end to the lower end of the cylindrical heating portion of the graphite heater. The lower slit C is preferably 70% or more of the length from the upper end to the lower end of the cylindrical heating portion of the graphite heater. As a result, the heat generating slit formed by the upper slit A and the corresponding lower slit C can be positioned above the center line that divides the heat generating portion into two in the height direction, and the lower slit D And the heat generating slit portion formed by the corresponding upper slit B can be positioned below the center line that divides the heat generating portion into two in the vertical direction.

Furthermore, each slit is periodically formed in the circumferential direction, and the heat generation distribution of the heat generating portion is such that the high temperature portion and the low temperature portion are periodically distributed in the circumferential direction, and one cycle is 180 °. I have to. In addition, the period based on the upper slit and the period based on the lower slit are shifted by 135 ° in the circumferential direction, and the heat generation distribution is 135 on the upper side and the lower side of the center line that bisects the heat generating part in the vertical direction. It is designed to deviate.
It should be noted that the period based on the upper slit and the period based on the lower slit are preferably shifted in the range of 45 ° or more and 135 ° or less in the circumferential direction. Longitudinal convection in the liquid surface direction can be surely promoted in a helical direction.

  FIG. 2 shows the temperature distribution of the raw material melt stored in the crucible when heated by such a graphite heater. As shown in FIG. 2A, the heat generating slit formed by the upper slit A and the lower slit C is a part of the portion corresponding to the first quadrant and the third quadrant when the crucible is viewed from directly above, and the raw material. It plays the role of heating near the surface of the melt. On the other hand, as shown in FIG. 2B, the heat generating slit portion formed by the upper slit B and the lower slit D is a part corresponding to the first quadrant and the third quadrant in the portion corresponding to the second quadrant and the fourth quadrant. It plays the role which heats the crucible bottom or the crucible R part. Therefore, the raw material melt in the crucible has a temperature distribution as shown in FIG.

  Such a temperature distribution in the raw material melt eventually promotes convection in the raw material melt from the crucible bottom to the raw material melt surface in the longitudinal direction and further in the helical direction. As a result, secondary convection immediately below the single crystal solid-liquid interface is promoted, and the temperature gradient (G) near the single crystal solid-liquid interface is increased. Therefore, the shape of the single crystal solid-liquid interface is likely to change to an upward convex shape, and the OSF disappears in a higher growth rate region, and for example, the crystal in the N region can be pulled up at a higher speed.

  In addition, since the conventional graphite heater has a uniform heat generation distribution in the circumferential direction, the oxygen concentration in the single crystal can be controlled by changing the convection of the raw material melt. I could only change the relative position of the heater in the height direction. However, in the present invention, since the heat generation distribution itself of the heat generating portion of the graphite heater can be changed according to various purposes, the convection of the raw material melt can be freely changed, and the oxygen concentration in the single crystal can be freely controlled.

  Furthermore, the present invention provides a crystal production apparatus comprising the above graphite heater for producing crystals, and also provides a method for producing a single crystal by the Czochralski method using the crystal production apparatus. In the present invention, a single crystal of a desired defect-free region such as an N region or a desired defect region can be obtained by simply setting a heater having the above-described characteristics in a single-crystal manufacturing apparatus having a conventional in-furnace structure. Can be raised at high speed to increase productivity. Further, since it is not necessary to change the design of an existing device, it can be configured very easily and inexpensively.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Example 1)
A silicon single crystal was manufactured using the single crystal manufacturing apparatus shown in FIG. A quartz crucible having a diameter of 24 inches (600 mm) was charged with 150 kg of raw material polycrystalline silicon, and a silicon single crystal having a diameter of 8 inches (200 mm) and an orientation <100> was pulled up. When pulling up the single crystal, the growth rate was controlled to gradually decrease from the crystal head to the tail in the range of 0.7 mm / min to 0.3 mm / min. Moreover, the silicon single crystal was manufactured so that the oxygen concentration was 22 to 23 ppma (ASTM'79).

  At this time, the graphite heater shown in FIG. 1 was used. That is, this graphite heater has a total length of 500 mm, and is provided with two upper slits A, eight upper slits B, four lower slits C, and eight lower slits D. The upper slit A and the lower slit D are each 200 mm in length, and the upper slit B and the lower slit C are each 400 mm in length.

The silicon single crystal thus manufactured was examined for OSF, FPD, LEP, and Cu deposition.
That is, at a crystal solidification rate of about 10% or more (in the case of the conditions of the present embodiment, the crystal straight body portion is 10 cm or more), after cutting the wafer at a length of every 10 cm in the crystal axis direction, surface grinding and polishing are performed. I went and investigated as follows.

(A) Investigation of FPD (V region) and LEP (I region):
After 30 minutes of seco-etching (no stirring), the in-plane density of the sample was measured.
(B) OSF field survey:
After heat treatment at 1100 ° C. for 100 minutes in a Wet-O ₂ atmosphere, the sample in-plane density was measured.
(C) Investigation of defects by Cu deposition process:
The processing method is as follows.
1) Oxide film: 25 nm 2) Electric field strength: 6 MV / cm
3) Energizing time: 5 minutes

As a result, the distribution state of each region became the distribution shown in FIG. That is, the growth rate at the boundary of each region was as follows.
Growth rate of boundary between V region and OSF region = 0.62 mm / min.
Growth rate of boundary between OSF region and N region where defect is detected by Cu deposition process = 0.61 mm / min.
Growth rate of the boundary between the N region where a defect was detected by the Cu deposition process and the N region where a defect was not detected by the Cu deposition process = 0.60 mm / min.
Growth rate of the boundary between the N region and the I region where no defect was detected by the Cu deposition process = 0.58 mm / min.

Next, based on the above results, the growth rate is controlled from 0.5 cm to 0.58 mm / min from the straight body 10 cm to the straight body tail so that the N region where no defect is detected by the Cu deposition process can be aimed. The silicon single crystal was pulled up (see FIGS. 4A and 4B). The pulled silicon single crystal was processed into a mirror-finished wafer to evaluate the oxide film pressure resistance. The C-mode measurement conditions are as follows.
1) Oxide film: 25 nm 2) Measuring electrode: phosphorus-doped polysilicon 3) Electrode area: 8 mm ² 4) Determination current: 1 mA / cm ²
As a result, the oxide film breakdown voltage level was 100% non-defective.

(Comparative Example 1)
The graphite heater shown in FIG. 6 was used. In this graphite heater, the total length of the heat generating part is 500 mm, and 10 upper slits and 12 lower slits are provided. The upper slits are all 400 mm long, and the lower slits are all 400 mm long. A silicon single crystal was produced under the same conditions as in Example 1 except that this graphite heater was used. In the same manner as in Example 1, OSF, FPD, LEP, and Cu deposition were investigated.

As a result, the distribution state of each region became the distribution shown in FIG. That is, the growth rate at the boundary of each region was as follows.
Growth rate of boundary between V region and OSF region = 0.50 mm / min.
Growth rate at the boundary between the OSF region and the N region where defects were detected by the Cu deposition process = 0.48 mm / min.
Growth rate of the boundary between the N region where a defect was detected by the Cu deposition process and the N region where no defect was detected by the Cu deposition process = 0.47 mm / min.
Growth rate at the boundary between the N region and the I region where no defect was detected by the Cu deposition process = 0.45 mm / min.

Next, based on the above results, the growth rate is controlled from 0.46 to 0.45 mm / min from the straight body 10 cm to the straight body tail so that the N region where no defect is detected by the Cu deposition process can be aimed. The silicon single crystal was pulled up (see FIGS. 4A and 4B). The pulled silicon single crystal was processed into a mirror-finished wafer, and the oxide film breakdown voltage characteristics were evaluated in the same manner as in Example 1.
As a result, the oxide film breakdown voltage level was 100% non-defective.

  FIG. 3 shows the distribution of various defects with respect to the growth rate in Example 1 and Comparative Example 1. According to this, when growing an N region single crystal in which no defect was detected by the Cu deposition process, in Comparative Example 1, it is necessary to grow at a low speed with a growth rate of 0.46 to 0.45 mm / min. On the other hand, in Example 1, it can be seen that the growth rate can be very high at a growth rate of 0.59 to 0.58 mm / min (see FIG. 3). Therefore, when the graphite heater of the present invention is used, productivity can be improved and manufacturing cost can be reduced.

  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.

  For example, in the embodiments of the present invention, the normal CZ method in which a magnetic field is not applied when pulling up a silicon single crystal has been described as an example. However, the present invention is not limited to this and is also applicable to an MCZ method in which a magnetic field is applied. it can.

It is the schematic which shows one example of the graphite heater of this invention. (A) Development view, (b) Side view. It is the conceptual diagram which showed the temperature distribution of the raw material melt in a crucible when a crucible is heated with the graphite heater of FIG. (A) Temperature distribution on the raw material melt surface layer side, (b) Temperature distribution on the crucible bottom side of the raw material melt, and (c) Overall temperature distribution of the raw material melt. It is explanatory drawing which shows the growth rate and crystal defect distribution of a single crystal. (a) Example 1, (b) Comparative Example 1. Single crystal growth when growing a silicon single crystal by controlling the growth rate of the N region in which no defect was detected by Cu deposition treatment, which was found by investigating the relationship between the single crystal growth rate and crystal defect distribution It is the comparison figure which compared the speed in Example 1 and Comparative Example 1 ((a), (b)). It is the schematic of a single crystal manufacturing apparatus. It is the schematic which shows an example of the conventional graphite heater. (A) Development view, (b) Side view.

Explanation of symbols

10 ... Single crystal manufacturing apparatus, 11 ... Main chamber, 12 ... Lifting chamber,
13 ... single crystal, 14 ... wire, 15 ... raw material melt, 16 ... quartz crucible,
17 ... graphite crucible, 18 ... shaft, 19 ... graphite heater, 20 ... heat insulation member,
21 ... Seed holder, 22 ... Seed crystal, 23 ... Cooling tube, 24 ... Graphite tube,
25 ... Inner insulation tube, 26 ... Outer insulation material,
27 ... Terminal part, 28 ... Heat generating part, 29 ... Upper slit, 30 ... Lower slit,
31 ... heating slit part.

Claims (9)

A terminal portion which current is supplied, a cylindrical heat generating portion is provided by resistance heating, is arranged so as to surround the crucible for accommodating a raw material melt, when manufacturing a single crystal by the Czochralski method In the graphite heater used, the heat generating portion is formed by alternately forming an upper slit extending from the upper end thereof and a lower slit extending upward from the lower end thereof to form the heat generating slit portion. The length of the slit is made up of two types of long and short, the length of the lower slit is made up of two types of long and short, and the number of the shorter lower slits is larger than the number of the shorter upper slits A graphite heater for producing a single crystal, wherein the heat generation distribution of the heat generating part is changed.   2. The graphite heater for producing a single crystal according to claim 1, wherein the number of the shorter lower slits is in the range of 2 to 5 times the number of the shorter upper slits.   The two types of upper slits and lower slits are periodically formed in the circumferential direction, and the heat generation distribution of the heat generating portion is a distribution in which a high temperature portion and a low temperature portion are periodically distributed in the circumferential direction. The graphite heater for producing a single crystal according to claim 1 or 2.   4. The graphite heater for producing a single crystal according to claim 3, wherein one cycle of the heat generation distribution is 180 °.   The period of the heat generation distribution is such that the period based on the upper slit and the period based on the lower slit are shifted in the range of 45 ° to 135 ° in the circumferential direction. A graphite heater for producing a single crystal as described in 1.   6. The shorter upper slit and lower slit have a length shorter than 50% of the length from the upper end to the lower end of the heat generating portion, according to any one of claims 1 to 5. A graphite heater for producing a single crystal as described.   7. The length of the longer upper slit and the lower slit is 70% or more of the length from the upper end to the lower end of the heat generating portion, according to claim 1. Graphite heater for single crystal production. 請 Motomeko 1 to single crystal manufacturing apparatus characterized by comprising a single crystal manufacturing graphite heater according to any one of claims 7.   A method for producing a single crystal, comprising producing a crystal by the Czochralski method using the apparatus for producing a single crystal according to claim 8.

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