JP2825938B2 - Single crystal pulling device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a single crystal pulling apparatus. More specifically, the present invention can stably grow single crystals, and has a low enzyme content and enzyme-induced stacking fault (OSF).
The present invention relates to a single crystal pulling apparatus capable of obtaining a single crystal with less occurrence of cracks.

2. Description of the Related Art As a method for producing a single crystal such as silicon, germanium, and gallium arsenide, a Czochralski method (CZ method) in which a crystal is grown from a melt in a crucible while growing the crystal is widely used.

Conventionally, when a silicon single crystal is to be obtained by the CZ method, for example, a single crystal pulling apparatus having a structure schematically shown in FIG. 3 is used.

The single crystal pulling apparatus 1 has a chamber 2 composed of a heating chamber 2a and a pulling chamber 2b as shown in FIG. In the heating chamber section 2a, a quartz crucible 5 supported by a rotating shaft 4 extending through the bottom of the chamber from a driving device 3 located outside the chamber 2 and a predetermined interval of the quartz crucible 5 are provided. A cylindrical heater 6 is provided to surround and surround. In this example, the outer periphery of the quartz crucible 5 is protected by a graphite crucible 7, and the graphite crucible 7 is supported on the rotating shaft 4 via a graphite tray 8.

On the other hand, the pulling chamber portion 2b extends above the heating chamber portion 2a along the pulling axis of the silicon single crystal body 10 pulled up and grown from the silicon melt 9 formed in the quartz crucible 5. Further, it is a portion having an inner diameter smaller than that of the heating chamber 2a.

A pull-up wire 14 having a chuck 13 for holding the seed crystal 12 is disposed in the chamber 2 at a tip portion which penetrates the upper wall of the chamber and hangs down from above. The pull-up wire 14 is provided with the pull-up wire. The wire and the pulling device 11 provided on the upper part of the tumbler portion 2b allow the ascending and descending while rotating.

In the pulling apparatus 1 having such a structure, to grow a single crystal, first, a predetermined amount of raw materials such as cubic silicon and dopants added as necessary is loaded into a quartz crucible 5 and a heater is provided. 6 to melt the raw material to form a melt 9. Then, the seed crystal 12 attached to the tip of the pulling wire 14 is immersed in the melt 9, pulled up while rotating the quartz crucible 5 and the seed crystal 12, and growing the single crystal body 10 at the lower end of the seed crystal 12. It is.

By the way, in pulling such a single crystal, silicon monooxide (SiO) and the like are evaporated from the high-temperature melt 9 formed in the quartz crucible 5. When such evaporated matter is condensed on the wall surface of the chamber 2 and falls and reaches the single crystal growth interface, there is a high possibility that the crystal is dislocated. Therefore, in the conventional single crystal pulling operation as described above, an argon gas G as an inert gas is supplied from the pulling chamber portion 2b side to the heating chamber portion.
It is attempted to suppress the occurrence of the above-mentioned dislocations by flowing down to 2a and accompanying the argon gas G to discharge the evaporant out of the system.

However, as shown in FIG. 3, in the chamber 2 of the conventional single crystal pulling apparatus 1, the heating chamber section 2a has a shape whose diameter is considerably sharply reduced immediately before the connection with the pulling chamber section 2b, that is, in the upper region. doing. For this reason, the flow of the argon gas G introduced into the heating chamber 2a from the pulling chamber 2b having a relatively small inner diameter is
It does not sufficiently reach the shoulder portion A of the heating chamber portion 2a, and a vortex flows at the shoulder portion A. Therefore, the melt 9
A portion of the evaporated material that has evaporated and rises from this portion stays at this portion where it reaches the shoulder portion A, and there is a possibility that the problem of dislocation described above may occur.

Further, in the conventional single crystal pulling apparatus 1, since the space of the heating chamber section 2a is relatively large, the dissipation of heat from the melt 9 is large. For this reason, the amount of heat of the heater 6 required to form the melt 9 increases, the wall surface temperature of the quartz crucible 5 increases, and the amount of oxygen eluted from the quartz crucible 5 increases. The oxygen content of the crystal was increased. Further, the wall surface of the chamber 2 is cooled by water cooling and the argon gas G during the pulling operation. However, as described above, the diameter of the wall from the heating chamber portion 2a to the pulling chamber portion 2b is considerably sharply reduced. The single crystal body 10 to be pulled is heated in the heating chamber 2a.
When it enters the pull-up chamber 2b from above, it is rapidly cooled. N-type silicon single crystal
The present applicants have found that when the cooling rate of each part of the crystal during pulling is increased to 5 ° C./min or more in a temperature range of 800 ° C. or less, OSF is remarkably generated. That is, the single crystal pulling apparatus having such a configuration has a problem in terms of generation of OSF.

Further, recently, in a single crystal pulling apparatus, as shown in FIG. 4, a single crystal body 10 to be pulled is used as an axis, and a lower end portion is close to a liquid surface of the melt 9 and an outer peripheral surface of the single crystal body 10 to be pulled. One provided with a conical heat insulating member 15 has been developed. Such an inverted conical heat insulating member 15 is placed in a quartz crucible 15
If provided on the upper portion, the dissipation of heat from the melt 9 or the heater 6 or the like is suppressed, and the amount of heat of the heater 6 is reduced,
Furthermore, the oxygen content in the obtained single crystal body 10 can be reduced. Further, since the inverted conical heat insulating member 15 substantially covers the upper part of the melt 9, it prevents SiO evaporating from the solution 9 from rising to the upper part of the chamber 2, and further prevents the SiO 2 evaporating from the melt 9 of the argon gas G. Since the flow near the interface can be rectified to some extent and SiO can be removed out of the system, prevention of dislocation of the single crystal body 10 as described above can be considerably expected. However, in the case where such an inverted conical heat insulating member 15 is provided, as described above, the single crystal body pulled up because heat dissipation is suppressed.
10 was quenched and the risk of OSF generation was further increased, and the rectification of the argon gas G was not sufficiently satisfactory.

Further, in the single crystal pulling apparatus, the chamber 2
There have been many proposals to provide rectifying plates 16 for rectifying the flow of the argon gas G in the heating chamber section 2a, but these rectifying plates 16 are all pulled up as in the example shown in FIG. The single-crystal body 10 was used as an axis, and the main part was a straight tubular part surrounding the single-crystal body 10. However, in such a straight tubular current plate 16, the pulled single crystal body 10 is
The single crystal body 10 is quenched when it enters inward, and the risk of OSF generation increases. This tendency becomes more conspicuous as the length of the current plate 16 is increased in order to enhance the current effect. Further, even with such a straight tubular current plate 16, the flow of the argon gas in the heating chamber portion 2a is not sufficiently rectified, and there is a possibility that the vortex flows as described above may occur. Alternatively, when the upper end of the current plate 16 is not in contact with the connection between the heating chamber 2a and the pull-up chamber 2b, this is remarkable, and there is room for improvement.

[Problems to be Solved by the Invention] Accordingly, the present invention can stably grow a single crystal, and at the same time, has a low enzyme content and an oxygen-induced stacking fault (OSF).
It is an object of the present invention to provide a novel single crystal pulling apparatus capable of obtaining a single crystal with less occurrence of cracks.

[Means for Solving the Problems] The above objects are attained by providing a heating chamber for accommodating a crucible and a heating means for the crucible, and the heating chamber extending along a single crystal pulling axis above the heating chamber. A single crystal pulling apparatus for growing a single crystal by dipping a seed crystal into a raw material melt formed in the crucible and pulling the single crystal, wherein the pulling chamber includes a pulling chamber having an inner diameter smaller than the inner diameter of the chamber. An upper end portion having an inner diameter substantially equal to the inner diameter of the pulling chamber is located at a connecting portion between the chamber portion and the heating chamber portion, and from this portion, along a pulling axis of the single crystal, is inclined downward by 20 to 70 ° from a vertical direction. Extended, and gradually expanded at least at its lower end,
The lower end of the inner diameter of 0.3 to 1.0 times the inner diameter of the heating chamber is 0.3 to 0.3 mm of the distance from the upper end of the heater to the lower end of the pulling chamber.
This is achieved by a single crystal pulling apparatus characterized by comprising a cylindrical current plate located at a distance of 0.8 times.

[Operation] As described above, in the single crystal pulling apparatus of the present invention, the upper end of the pulling chamber and the inner diameter of the pulling chamber are located at the connection between the pulling chamber and the heating chamber, and the single crystal is pulled from this portion. An inert gas such as an Ar gas supplied from the pulling chamber side is provided with a cylindrical straightening plate that extends downward along the axis and has a diameter gradually increased at least at a lower end portion thereof. The gas is rectified by the rectifying plate, and the gas flow in the pulling chamber becomes stable. For this reason, it stays in the pulling chamber.
The risk of problems such as SiO being attached to the single crystal growth interface and causing dislocations is reduced, and stable single crystal growth can be performed.

Further, since the straightening plate has a shape protruding into the space of the pulling chamber, the straightening plate functions as a heat insulating material for reducing heat discharge from the melt. Therefore, in the single crystal pulling apparatus provided with the current plate, the heating by a heating means such as a heater for forming a melt can be reduced and the temperature of the quartz crucible can be reduced. The amount of oxygen to be produced can be reduced, and a single crystal containing low oxygen can be obtained. In addition, since the rectifying plate functioning as a heat insulating material exists along the pulling direction of the single crystal, and the rectifying plate gradually reduces the diameter of the growing single crystal body. In addition, the single crystal is appropriately cooled slowly, and the generation of OSF is suppressed.

EXAMPLES Hereinafter, the present invention will be described in more detail based on embodiments.

FIG. 1 is a sectional view schematically showing the structure of a silicon single crystal pulling apparatus as one embodiment of the single crystal pulling apparatus of the present invention.

The single crystal pulling apparatus 1 of the present invention has a chamber 2 composed of a heating chamber section 2a and a pulling chamber section 2b, like the conventional single crystal pulling apparatus as described above. Here, the pulling chamber portion 2b is a portion having a smaller inner diameter than the heating chamber portion 2a and extending above the heating chamber portion 2a along the pulling axis of the silicon single crystal body 10 to be grown.

In this embodiment, a quartz crucible 5 supported by a rotating shaft 4 extending through the bottom of the chamber from a driving device 3 located outside the chamber 2 and a quartz crucible 5 inside the heating chamber portion 2a. Is provided at a predetermined interval. The outer periphery of the quartz crucible 5 is protected by a graphite crucible 7, and the graphite crucible 7 is further rotated by a rotating shaft 4 via a graphite tray 8.
Supported by

A pull-up wire 14 having a chuck 13 for holding the seed crystal 12 is provided at a tip portion of the chamber 2 which penetrates the upper wall surface of the chamber and hangs down from above. A wire pulling device 11 provided at an upper portion of the chamber section 2b enables the ascending and descending while rotating.

Further, in the single crystal pulling apparatus, an inert gas supply duct 17 is connected in the middle of the pulling chamber section 2b so that the chamber 2 can be maintained in an atmosphere of an inert gas, argon gas G, during the pulling operation. Further, a gas exhaust duct (not shown) is provided in a lower portion of the heating chamber section 2a.

Here, in the single crystal pulling apparatus 1 of the present invention, the shape, type, and the like of the quartz crucible 5, the heater 6, and the driving device 3 as described above, or the arrangement of the inert gas supply / discharge duct and the like are particularly limited. It is not something to be done. For example, as seen in an apparatus for continuously pulling a single crystal, a quartz crucible 5 is composed of an inner crucible partially having a through hole and an outer crucible surrounding the inner crucible. Double structure that can change the positional relationship,
Alternatively, a structure in which a tubular partition having a part of a through hole is disposed in a crucible and the inside of the crucible is partitioned into an inner portion and an outer portion from the annular partition may be employed. The heater 6
For example, a method using a resistance heating method or a method using an induction heating method can be used. Furthermore, in this embodiment, the quartz crucible 5 is configured to be rotated by the external driving device 3. However, a mode in which such a rotating means is not provided, or a quartz crucible is replaced with the rotating means as described above. It is also possible to adopt a mode in which a rotating magnetic field is applied to the melt 9 formed in the crucible 5 to rotate the melt 9. Furthermore, in order to keep the amount of the melt 9 constant through the single crystal pulling operation, it is possible to adopt a mode in which a raw material supply pipe for replenishing the raw material is provided in the crucible 5.

Thus, in the single crystal pulling apparatus 1 of the present invention, as shown in FIG. 1, a current plate 18 is provided in the heating chamber 2a. The rectifying plate 18 has an upper end portion having an inner diameter substantially equal to the inner diameter of the pulling chamber portion 2b located at a connection portion between the pulling chamber portion 2b and the heating chamber portion 2a, and from this portion downward along the single crystal pulling axis. It has a cylindrical shape that is elongated and has a diameter gradually increased at least at a lower end portion thereof. In the embodiment shown in FIG. 1, the straightening plate 18 has an upper straight body portion 18a having the same diameter as the upper end thereof, and a lower cone gradually expanded with a predetermined inclination from the diameter of the straight body portion 18a. Portion 18b, but in the current plate 18 according to the present invention, the straight body portion 18 as described above.
a is not necessarily required, and may be formed of only the conical portion 18b, that is, a shape whose diameter is gradually increased from the upper end to the lower end. The degree of the inclination of the conical portion 18b of the current plate 18 is determined by the inclination of the upper wall surface 19 of the heating chamber portion 2a of the chamber 2 (the inclination from the vertical direction).
Less than 20 °
70 ゜. Further, the inner diameter of the lower end portion of the current plate 18 is 0.3 to 1.0 times the inner diameter of the heating chamber 2b. Regarding the position of the current plate 18, the distance from the lower end of the pull-up chamber 2b to the lower end of the current plate 18 is 0.3 to 0.8 times the distance from the upper end of the heater 6 to the lower end of the pull-up chamber 2b.
When the shape of the current plate 18 satisfies the above-described conditions, a sufficient rectifying effect of the inert gas flowing down from the pulling chamber portion 2b side to the heating chamber portion 2a and OSF generation of the grown single crystal can be obtained. It is expected that a slow cooling effect for suppression will be provided. The material constituting the current plate 18 is not particularly limited, and its shape,
Those that obtain the optimal heat insulating effect and the like are selected from the relationship with the size and the like, for example, graphite, quartz, silicon carbide, or M
o. Metal such as Ti and stainless steel may be used.

In the embodiment shown in FIG.
Is suspended from the upper end side, but may be configured to be supported from the lower end side by a support 20 provided below as in another embodiment shown in FIG.

Growing a silicon single crystal using the single crystal pulling apparatus of the present invention having such a configuration is performed in substantially the same manner as in the case of using a conventional single crystal pulling apparatus. That is, first, a predetermined amount of a raw material such as polycrystalline silicon and a dopant to be added as necessary is loaded into a quartz crucible 5 and heated by a heater 6 to melt the raw material to form a melt 9.

When starting the lifting operation, a gas discharge duct (not shown) connected to a lower portion of the heating chamber section 2a
The gas in the chamber 2 is sucked and discharged to the outside of the system, and an argon gas G is introduced into the chamber 2 from the inert gas supply duct 17 to make the chamber 2 a reduced-pressure argon atmosphere or a normal-pressure argon atmosphere.

Then, the seed crystal 12 attached to the tip of the pulling wire 14 is immersed in the melt 9, pulled up while rotating the quartz crucible 5 and the seed crystal 12, and growing the single crystal body 10 at the lower end of the seed crystal 12. However, in the single crystal pulling apparatus 1 of the present invention, the current plate 18 having the above-described shape is provided in the heating chamber section.
2a, the flow of the argon gas G formed in the heating chamber section 2a causes the single crystal 10
, And smoothly spread outward to reach the vicinity of the upper portion of the quartz crucible 5, and the possibility of eddy currents occurring at the shoulder portion A of the heating chamber portion 2 a is extremely small. Even if it does, Si which evaporates from melt 9
O is discharged out of the system along the smooth flow, so that the possibility of dislocation of the crystal due to such an evaporant is extremely small. Further, the grown single crystal body 10 passes through the center of the current plate 18 and reaches the pulling chamber 2a.
Has a structure that is gradually expanded from above to below,
The wall surface of the current plate 18 (cooled by the argon gas G) gradually approaches the single crystal body 10 entering from below. For this reason, the single crystal body 10 is gradually cooled, and generation of OSF is suppressed. In addition, since the heat dissipation from the melt 9 or the heater 6 is suppressed by disposing the rectifying plate 18, the heating can be reduced, the temperature of the quartz crucible can be reduced, and the low oxygen content can be reduced. A single crystal can be obtained.

Although the single crystal pulling apparatus of the present invention has been described above with reference to the case of pulling a silicon single crystal as an example, the present invention
The present invention can be similarly applied to a material other than silicon, for example, a material for growing a single crystal such as germanium or gallium arsenide.

[Effects of the Invention] As described above, in the single crystal pulling apparatus of the present invention, the upper end portion having an inner diameter substantially equal to the inner diameter of the pulling chamber is located at a connection portion between the pulling chamber portion and the heating chamber portion of the chamber, A cylindrical straightening plate extending downward from this portion along the pulling axis of the single crystal and having a gradually enlarged diameter at least at its lower end portion is disposed, and is caused by evaporates generated from the melt. Stable single crystal region growth without causing the problem of dislocations in the crystal, and a single crystal with low oxygen content and low occurrence of induced stacking faults (OSF) can be obtained. Things.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing the structure of one embodiment of the single crystal pulling apparatus of the present invention, and FIG. 2 is a cross-sectional view schematically showing the structure of another embodiment of the single crystal pulling apparatus of the present invention. 3 to 5 are sectional views schematically showing the structure of a conventional single crystal pulling apparatus. DESCRIPTION OF SYMBOLS 1 ... Single crystal pulling apparatus, 2 ... Chamber, 2a ... Heating chamber part, 2b ... Pulling chamber part, 3 ... Drive device, 4 ... Rotary shaft, 5 ... Quartz crucible, 6 ... Heating Heater, 7: graphite crucible, 8: graphite tray, 9: melt, 10: single crystal, 11: wire puller, 12: seed crystal, 13: chuck, 14: Pull wire, 15… Inverted conical heat insulating member, 16… Rectangular straightening plate, 17… Inert gas supply duct, 18… Rectifying plate, 18a… Rectifying plate straight body part, 18b …… Rectifying plate 19: Upper wall surface of the pull-up chamber, 20: Rectifier support, A: Shoulder portion of the pull-up chamber, G: Argon gas.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshinori Takahashi 1-1-1, Edamitsu, Yawatahigashi-ku, Kitakyushu-city, Fukuoka Prefecture Inside Nippon Steel Corporation Equipment Engineering Division (56) References JP-A-57-123890 JP, A) JP-A-57-17495 (JP, A) JP-A-55-158197 (JP, A) JP-A-55-113695 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) C30B 1/00-35/00 H01L 21/203-21/205

Claims (1)

(57) [Claims] 1. A heating chamber for accommodating a crucible and a heating means for the crucible, and a pulling chamber having a smaller inner diameter than the heating chamber extending above the heating chamber along a single crystal pulling axis. A single crystal pulling apparatus for growing a single crystal by dipping and pulling a seed crystal into a raw material melt formed in the crucible, wherein the pulling chamber part of the chamber is connected to a heating chamber part. An upper end portion having an inner diameter substantially the same as the inner diameter of the pulling chamber is located in the portion, and is extended downward from this portion along a pulling axis of the single crystal at an inclination of 20 to 70 ° from a vertical direction, and gradually at least at a lower end portion thereof. The lower end of the inner diameter of 0.3 to 1.0 times the inner diameter of the heating chamber is expanded to 0.3 to 0.8 of the distance from the upper end of the heater to the lower end of the pulling chamber.
A single crystal pulling device comprising a cylindrical current plate located at twice the distance.