JPH1112093A - Production of silicon single crystal and production device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a silicon single crystal having a larger caliber and a longer length, and further to provide a production device of the single crystal. SOLUTION: This method for producing a silicon single crystal by growing a silicon single crystal ingot by a pulling method comprises a step for forming a Dash' s neck part 6 just under a seed crystal, a step for carrying out a diameter expansion so that the diameter may be larger than the small caliber part and smaller than the final diameter of a desired ingot, and a step for pulling the crystal of a prescribed length in the diameter to form a cylindrical portion 8 to be gripped. The method further comprises a step for gradually carrying out the diameter expansion so that the diameter may become the desired final diameter, a step for allowing a collet chuck-like gripping means 10 connected to an pulling structure 18 and 19 independent from the pulling up structure 1 and 2 of the seed crystal to grip the portion 8 to be gripped at the prescribed timing of a process after the formation of the portion to be gripped for carrying out the pulling operation of a cylindrical part, and a step for pulling the single crystal at the constant rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for producing a silicon single crystal. More specifically, the present invention provides a silicon single crystal ingot to be grown, even if the pulling weight increases due to an increase in diameter and length of the ingot.
The present invention relates to a pulling method and a pulling device capable of stably and reliably pulling.

[0002]

2. Description of the Related Art At present, silicon is a typical semiconductor that is widely used industrially as a device such as an integrated circuit (IC) and a large-scale integrated circuit (LSI).

A silicon single crystal used in the semiconductor industry or the like is a floating zone in which a polycrystalline material is used as a raw material to form a molten zone on a polycrystalline rod by induction heating and move the molten zone from a seed crystal side to grow a single crystal. Melting method (Floating Zone method,
Abbreviated as FZ method. ) Alternatively, a polycrystal is placed in a crucible and heated and melted, and the seed crystal is immersed in a melt and then pulled up to grow a single crystal ingot behind the seed crystal (abbreviated as Czochralski method or CZ method). ).

[0004] These production methods are selected depending on the use of the single crystal. The single crystal produced by the FZ method is used for high resistivity applications, and the single crystal produced by the CZ method is used for low to medium resistivity applications. However, recently, due to the progress of LSI manufacturing technology,
The number of circuits formed in a wafer in one process is increased by increasing the area of a single crystal wafer serving as a processing substrate while increasing the size of electronic circuits. The cost has been reduced.
For this reason, there is a constant demand for single crystal production technology to increase the diameter, and at the same time, a method of increasing the length of one single crystal ingot in order to increase productivity per hour during the production of a single crystal. Have been pursued.

[0005] The above-mentioned CZ method not only has an advantage that a large-diameter ingot can be easily obtained, but also has an advanced technology such as automatic diameter control and semi-continuous operation by recharging a raw material polycrystal, thereby reducing costs. The fact is that it surpasses the FZ method.

Conventionally, a pulling apparatus using the CZ method has a configuration in which a single crystal ingot grown behind a seed crystal is directly pulled up by lifting means such as a pulling wire for raising and lowering the seed crystal with respect to the melt surface. However, in this case, the weight of the single crystal ingot is received by the seed crystal or a small diameter portion called a dash's neck portion formed immediately below the seed crystal to prevent dislocation of the crystal. In particular, the dash neck has a diameter of about 3 to 4 mm and can withstand a weight of at most about 200 kg.

As described above, in the conventional lifting device, there is a limit in increasing the diameter and length of the ingot.

For this reason, the diameter of the single crystal ingot can be increased.
In order to cope with an increase in weight due to an increase in length, various improvements in a lifting mechanism have been proposed.

For example, in Japanese Unexamined Patent Publication No. Hei 5-270968, a cylindrical mold is provided which surrounds the above-mentioned dash neck portion when growing a single crystal, and the mold is made of a thermosetting resin such as a fluororesin or a silicone resin. Pour the resin and cure it,
A method of reinforcing the dashes neck is disclosed in Japanese Patent Laid-Open No. 5-27.
Japanese Patent Application Laid-Open No. 09-13808 discloses a method in which a reinforcing fiber such as carbon fiber is wound around a dashes neck portion to reinforce the dashes neck portion.
In Japanese Patent Publication No. 9-515, Japanese Patent Publication No. 7-515 discloses a method of cooling or heating a dash neck portion at the time of growing a single crystal to maintain the tensile strength of the portion at a maximum of about 600 to 800 ° C. In the so-called cone part, which expands to the desired diameter after dislocation by the dash neck part, temporarily reduces the diameter to form a cracked part, and hooks a nail-shaped locking member on this part to make the ingot A method is provided in which a single crystal is pulled by raising and lowering this gripping means separately.
In Japanese Patent No. 172981, the gripping means having a plurality of arms that can be opened and closed by a pneumatic cylinder is arranged so as to surround the single crystal ingot from the single crystal growth axis direction.
The pneumatic cylinder is actuated to grip the ingot by pressing the gripping portions provided at the distal ends of the plurality of arms against the straight body of the single crystal ingot, and the gripping means is moved up and down to lift the ingot. A method for pulling a crystal is disclosed.

[0010]

However, the reinforcement of the dashes neck portion with a thermosetting resin as disclosed in Japanese Patent Application Laid-Open No. Hei 5-270968 requires a very precise alignment for setting the formwork. And Japanese Patent Laid-Open No. 5-2
Reinforcement of a dashes neck portion by a reinforcing fiber as disclosed in JP-A-70976 is very complicated in terms of mechanism,
All of them lack operation reliability, and their reinforcing effect is not sufficient. Further, Japanese Patent Laid-Open No. 7-1
The method of controlling the temperature of the dashes neck portion disclosed in Japanese Patent No. 38089 is basically for holding the grown single crystal ingot by the strength of the dashes neck portion itself. Improvement in weight could not be expected. In addition, 7-51
In the technique disclosed in No. 5, it is necessary to form a crack portion for holding in a single crystal ingot, but there is a risk that dislocation occurs or polycrystallization occurs due to thermal stress when reducing the diameter. If these cracks are not formed uniformly in the radial direction, there is a possibility that the growth axis may be inclined when the claw-shaped locking member is engaged. Further, when a straight body of a single crystal ingot as described in Japanese Patent Application Laid-Open No. 7-172981 is gripped by a gripping mechanism, the structure of the gripping mechanism itself becomes complicated and costly, and since the straight body is gripped, In addition to the large size of the mechanism itself, it is necessary to have a strong frame structure that can withstand a large load from the lateral direction, which increases the weight of the entire device, and supports the gripping mechanism from above and allows the gripping mechanism to move up and down. However, the operation becomes large-scale using a shaft or the like, and the operation for gripping the shaft has complicated control.

As described above, various methods have been conventionally proposed in order to cope with an increase in the weight of single crystal ingots due to the increase in diameter and length, but none of them has been satisfactory.

Accordingly, an object of the present invention is to provide a novel method and apparatus for producing a silicon single crystal. The present invention also provides a method and an apparatus for manufacturing a silicon single crystal that can be stably and reliably pulled even if the weight of the silicon single crystal ingot to be grown is increased due to an increase in diameter and length. That is the task. It is still another object of the present invention to provide a method and an apparatus for manufacturing a silicon single crystal, which can be stably and reliably pulled by a relatively simple operation and a simple mechanism even if the pulling weight increases. It is assumed that.

[0013]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the above-mentioned problems, and as a result, mechanically grasps a silicon single crystal ingot to be grown separately from a seed crystal pulling mechanism. In the case of pulling up the silicon single crystal ingot, the same diameter portion having a relatively small diameter and a predetermined length (hereinafter, referred to as a short portion) is provided immediately below the dash neck portion.
Also referred to as "mini straight body." ), And this part is
The present inventors have found out that the ingot can be stably and reliably held with a relatively simple and lightweight structure by being sandwiched by a structure similar to a so-called "collet chuck", and the present invention has been accomplished.

That is, the present invention for solving the above-mentioned problems has the following features:
(1) In a method of manufacturing a silicon single crystal in which a seed crystal is immersed in a silicon melt and the seed crystal is pulled up to grow a silicon single crystal ingot at the rear end of the seed crystal, the silicon grown just below the seed crystal After forming a small-diameter portion for dislocation-free single crystal ingot, the diameter is increased to a diameter larger than the small-diameter portion and smaller than a final diameter of the desired ingot, and a certain length is pulled at the diameter. Forming a gripped portion in the shape of a cylinder, and thereafter, gradually increasing the diameter of the single crystal ingot to a desired final diameter, and pulling up the straight body of the single crystal ingot by the final diameter. At a predetermined time in the process after the formation of the grip portion, the gripped portion is gripped by a gripping means connected to a pulling mechanism independent of the seed crystal pulling mechanism. Lifting and, by raising the gripping means at a predetermined speed, a method for manufacturing a silicon single crystal, wherein the subsequent growth of a silicon single crystal ingot be carried out while supporting the single crystal ingot by the gripping means.

The present invention also provides (2) a method for producing a silicon single crystal in which a seed crystal is immersed in a silicon melt and a silicon single crystal ingot is grown at the rear end of the seed crystal by pulling up the seed crystal. Immediately below the crystal, a small diameter portion for dislocation-free silicon single crystal ingot to be grown is formed, and then expanded to a diameter larger than the small diameter portion and smaller than the desired final diameter of the ingot. After forming a cylindrical gripped portion by pulling up a certain length at the diameter, the diameter is gradually expanded to a desired final diameter, and the straight body portion of the single crystal ingot is pulled up by the final diameter to perform the above-mentioned operation. In the middle of the body pulling operation, the gripping means connected to a pulling mechanism independent of the seed crystal pulling mechanism moves the silicon crystal ingot in front of the silicon single crystal ingot. Gripping the gripped portions, said gripping means by raising at a predetermined speed, the development of subsequent silicon single crystal ingot, a method of manufacturing a silicon single crystal which is characterized in that the pulling operation of said gripping means.

Further, in the present invention, (3) it is preferable that the diameter of the gripped portion formed on the silicon single crystal ingot is about 8 to 100 mm.

Another object of the present invention is to provide (4) a silicon crystal having a crucible for containing a silicon melt and a seed crystal pulling means for allowing a seed crystal to hang up and down with respect to the silicon melt by a seed crystal pulling filament. In a single crystal manufacturing apparatus, a substantially cylindrical splitter having a plurality of cuts on the peripheral surface along the axial direction at a lower end portion, and the lower end portion is gradually expanded in diameter to form a tapered portion, and a splitter of the splitter. A single crystal gripping means comprising: a cylindrical caulking tool having an inner diameter not less than the maximum outer diameter and not less than the minimum inner diameter of the tapered portion of the splitter slidably fitted to the outer peripheral surface; Gripping portion pulling means for suspending the means so as to be able to ascend and descend from above, wherein the splitter of the single crystal gripping means is disposed substantially coaxially with the seed crystal pulling striatum; Space to the seed crystal Also achieved by an apparatus for producing a silicon single crystal, characterized in that for raising the striatum can is assumed passable freely.

[0018]

In the present invention, a silicon single crystal ingot to be grown is gripped by a mechanical gripping mechanism during the operation of pulling up the silicon single crystal ingot. Immediately below the dash neck portion of the crystal ingot, a mini straight body portion having a diameter larger than the dash neck portion and sufficiently smaller than the desired final diameter of the single crystal ingot is formed. Since the mini straight body portion is formed by expanding the diameter from the dashes neck portion, the mini straight body portion is generated when the diameter is reduced to form a cracked portion as in the technique of Japanese Patent Publication No. 7-515. There is no fear of such dislocation or polycrystallization. In addition, after the mini straight body portion, the cone portion is formed by expanding the diameter again until a desired final diameter is obtained, and a dash neck in a conventional single crystal pulling operation is generally performed. In the diameter expansion operation after the formation of the part, the diameter expansion is stopped only for a certain period of time and the lifting is performed, and the diameter control is not particularly difficult, and the formation of the mini straight body itself is easy. .

Since the mini straight body formed in this manner is gripped by the mechanical gripping means, the gripping means itself does not increase in size, and for example, has a light weight such as a structure similar to a collet chuck. Because of the simple structure, the pulling means required for raising and lowering the gripping means can be sufficiently supported and suspended by a thin linear body such as a wire, like the pulling means for pulling up the seed crystal. In addition, a straight body portion having a desired final diameter that is sufficiently larger than the mini straight body portion is formed below the mini straight body portion gripped by the gripping means. By blocking the radiant heat by the straight body, the gripping means for gripping the mini straight body also has an advantage that it is not exposed to a high-temperature environment. The risk of thermal degradation is reduced. In particular, if the holding operation by the holding means of the mini straight body is performed after the growth of the straight body having a desired final diameter is started, the gripping point is already lower than the mini straight body from the mini straight body. Also, a portion having a large diameter is formed, and the effect of blocking radiant heat as described above is advantageous since it can be expected from the beginning of gripping.

Further, during the operation of pulling the single crystal, the mini straight body portion having mechanical strength sufficiently higher than that of the dash neck portion is mechanically gripped, and the weight of the silicon single crystal ingot is supported at the portion. In order to grow the silicon single crystal ingot after that, even if the weight increased due to the increase in diameter and length of the ingot, the situation such as dropping and growing of the single crystal ingot due to breakage of the small diameter part of the ingot, There is no possibility of occurrence, and a stable and reliable lifting operation can be performed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on specific embodiments.

In the method for producing a single crystal according to the present invention, first, a predetermined amount of a raw material such as polycrystalline silicon and an optional dopant is loaded into a crucible arranged in a single crystal pulling apparatus according to a conventional method. Then, the raw material is melted by heating with a heater or the like to form a melt, the seed crystal held by the seed crystal holding means is once immersed in the melt, and thereafter,
The seed crystal is pulled up while being rotated around an axis by an elevating means connected to the seed crystal holding means, and a single crystal is grown at the lower end of the seed crystal.

In order to eliminate dislocations, the diameter is once increased to 3 to
After forming the dashes neck portion by squeezing it to about 4 mm, the diameter is gradually increased, but in the present invention, the diameter is not expanded as it is to the desired final diameter, but rather than the diameter of the dashes neck portion. When the diameter is increased to a large desired diameter, for example, about 8 to 100 mm, more preferably about 20 to 80 mm, this diameter is maintained and pulled up by a predetermined length, for example, 10 to 150 mm, and a cylindrical portion having the same diameter, that is, Form a torso. Here, the diameter of the mini straight body is set within the above range because the diameter is 8 m.
If it is smaller than m, depending on the final diameter and length of the single crystal ingot to be pulled, this mini straight body exerts enough mechanical strength to support the weight of the single crystal ingot. This is because there is a possibility that the mini straight body portion is formed in this way, and the meaning of forming the mini straight body portion and mechanically holding it as described later is reduced. On the other hand, when the diameter exceeds 100 mm, the mini straight body portion is not obtained. This is because it is necessary to increase the size and complexity of the gripping means for gripping the body, and none of them is appropriate.

The length of the mini straight body is not particularly limited. However, if the length is extremely short, stable holding by the holding means becomes difficult. Concern that the mechanical strength of the mini-straight body is reduced, in addition to the problem that the effective pull-up length becomes longer, the ratio of the substantially useful straight body having the desired diameter decreases, and the pull-up operation time becomes longer. Therefore, it is appropriate to set the length within the above range.

After the mini straight body is formed on the silicon single crystal ingot in this way, the diameter of the grown single crystal is gradually increased again to form a cone portion, and after reaching the desired diameter, the diameter is maintained. The straight body is formed by controlling the pulling speed, the melt temperature, and the like. Thus, in the present invention, at a desired time in the process after the formation of the mini-straight body portion as described above, the mini-straight body portion is gripped by a suitable gripping means described later, and the lifting / lowering means connected to the gripping means. By moving the gripping means upward, the single crystal growth after gripping is switched from lifting by the lifting means connected to the seed crystal holding means to lifting by the lifting means connected to the gripping means, Single crystal growth is continued until the ingot has a desired length.

In the present invention, immediately after the mini-body portion is formed, the mini-body portion is gripped by gripping means.
It is of course possible to perform the subsequent single crystal growing operation by switching to the pulling by the elevating means connected to the gripping means. However, immediately after the mini-straight body is formed, the surface temperature of the mini-straight body is considerably high. In addition, a portion having a sufficiently large diameter below the mini straight body portion, that is, the cone portion and the straight body portion have not been formed yet, and the mini straight body portion receives a large amount of radiant heat from the silicon melt. In such a mode, the gripping means is exposed to a high temperature for a while from the gripping point. Therefore, preferably, this gripping is performed at a stage where a cone portion and a certain straight body portion are formed below the mini-straight body portion, that is, when the mini-straight body portion moves upward in the single crystal manufacturing apparatus and its surface temperature increases. Is desirably performed at a stage in which the radiant heat from the silicon melt is blocked by the cone portion and the straight body portion to some extent. In addition, the surface temperature of the mini-straight body at the desirable holding time is particularly limited because it depends on the apparatus configuration of the single crystal manufacturing apparatus used, the diameter (final diameter) of the silicon single crystal to be grown, and the like. Although not something, for example, 400-
It is about 1000 ° C.

In the above description, in order to facilitate the explanation, in the stage until the mini-body is mechanically gripped by the mechanical gripping means, the mini-body is pulled up by the elevating means connected to the seed crystal, and Later, it has been described that the lifting is performed by the lifting / lowering means connected to the gripping means. However, it is not always necessary to perform such strict switching in practice, for example, after gripping, for example, It is also possible to make the moving speed of the elevating means of the seed crystal and the elevating means of the seed crystal side substantially the same, to disperse the load of the ingot on both sides, and to lift the ingot. Afterwards, the gripping means may be in a state of supporting at least a part of the weight of the ingot, preferably the majority of the weight of the ingot.

In the switching operation of the weight support, for a while after the holding, the moving speed of the lifting / lowering means on the seed crystal side is set to be faster than the moving speed of the lifting / lowering means on the holding means side, and the holding is gradually performed. It is necessary to increase the moving speed on the tool side and synchronize with the pulling speed of the lifting means on the seed crystal side, and then gradually reduce the pulling speed of the lifting means on the seed crystal side. Is not transmitted to the single crystal growth interface.

In the single crystal manufacturing method of the present invention, the structure of the holding means for holding the mini-rectangular body formed as described above is such that a pressing force or the like is applied in contact with the peripheral surface of the mini-rectangular body. By grasping the mini-straight body by doing so, it can sufficiently support the weight of the single crystal ingot to be grown, and at least until the grasping of the mini-straight body by the grasping means is performed. There is no particular limitation as long as it can be displaced (moved) independently of the seed crystal or the seed crystal holding means, and various forms can be adopted. Since the portion is sufficiently small, the configuration of the gripping means can be reduced in size and weight. For example, a lightweight and low-cost member such as a wire is used as a means for supporting the gripping means so as to be able to move up and down. Can do That. In particular, a desirable configuration of the gripping means includes a splitter (collet) having an enlarged diameter at the tip end and a tubular annular caulking tool that regulates the inner diameter of the splitter slidably fitted around the splitter. Has a structure similar to a so-called "collet chuck".

That is, in the single crystal manufacturing method as described above of the present invention, a single crystal manufacturing apparatus particularly preferably used is a crucible containing a silicon melt, and a seed crystal for pulling a seed crystal from the silicon melt. In a single crystal manufacturing apparatus having a seed crystal pulling means for hanging up and down by a striated body, a plurality of cuts along the axial direction are provided at a lower end portion on a peripheral surface, and the lower end portion is gradually expanded in diameter to be tapered. A substantially cylindrical splitter forming a portion, and a cylindrical caulking tool having an inner diameter equal to or less than the maximum outer diameter and the minimum inner diameter of the tapered portion of the splitter slidably fitted to the outer peripheral surface of the splitter. A single crystal gripping means comprising: and a gripper pulling means for suspending the single crystal gripping means so that the single crystal gripping means can be raised and lowered from above. Is disposed substantially coaxially with the raised umbilical member can, it is characterized in that the internal space of the seed crystal pulling umbilical member of the split element is assumed passable freely.

In the above-mentioned single crystal manufacturing apparatus of the present invention, the maximum inner diameter of the tapered portion of the splitter is the size of the mini straight body portion to be formed on the single crystal ingot in a state where the cylindrical caulking tool is not engaged. It must be at least larger than the diameter, preferably about 1 to 30 mm larger than the diameter of the mini straight body part, while the minimum inner diameter of the tapered part, in other words, by engaging the cylindrical caulking tool with the tapered part The minimum inner diameter that can be reached as a result of the reduction of the maximum inner diameter is
It is necessary that the diameter be smaller than the diameter of the mini body part, preferably about 1 to 10 mm smaller than the diameter of the mini body part.

The minimum inner diameter of the entire splitter is such that the internal space of the splitter is formed by a seed crystal pulling striated body composed of a wire, a rod, and the like, more preferably, a seed crystal holding means and a seed crystal. It must have a size that allows it to pass freely, and is not particularly presented, but is, for example, 30 mm or more.

The number of the slits formed on the splitter may be any number as long as the tapered portion formed with the split is uniformly reduced in diameter in the entire circumferential direction when the caulking tool is engaged. There is no limitation, and it is sufficient that at least one exists. However, although it depends on the minimum diameter of the tapered portion and the like, usually, about 2 to 4 pieces are desirable,
Further, it is desirable to arrange them evenly in the circumferential direction. Furthermore, it is not necessary that the slit be formed completely along the axis of the splitter, and if all the slits have substantially the same trajectory, they may be bent in the middle even if they are somewhat inclined. Such a thing may be used.

The length of the slit, that is, the length of the tapered portion is not particularly limited as long as a sufficient holding force can be exhibited when the mini straight body is gripped. It is about 10 to 200 mm. Also,
Although there is no particular limitation on the diameter expansion angle of the tapered portion, it is, for example, about 1 to 15 °.

Further, the single crystal holding means used in the single crystal manufacturing apparatus of the present invention is arranged such that the cylindrical caulking tool does not engage with the tapered portion of the splitter and the tapered portion is opened during the single crystal pulling operation. From the closed state, the inner diameter of the tapered portion of the splitter is reduced by a cylindrical caulking tool, and the state is maintained in which the mini straight body of the silicon single crystal is held. The configuration of the mechanism for changing the relative position with respect to the cylindrical caulking tool to be fitted to is not particularly limited. For example, air on the wall surface of both members or the wall surface of the extension member of both members A configuration in which the ends of elastic members such as cylinders, hydraulic cylinders, springs, etc. are fixed and displaced by expansion and contraction of the elastic members, or the splitter and the cylindrical caulking tool engage and A lock mechanism that holds this state once the part has been reduced in diameter has been provided between the two members, and one member is initially stopped at a predetermined position by the holding means in the single crystal pulling apparatus. In the meantime, when the other member is moved and both are engaged and the lock mechanism is activated, the holding mechanism of the one member is released and both are simultaneously moved. However, the mechanism using the above-mentioned elastic member is particularly preferable because of its simple configuration and easy operation. When using an elastic member as described above, it is desirable to dispose the same elastic member in at least two or more parts so that the displacement of the cylindrical caulking tool with respect to the splitter can be performed uniformly over the entire circumference.
Further, it is desirable that these plural places are provided at substantially equal intervals in the circumferential direction.

In the single crystal manufacturing apparatus of the present invention,
The structure of the elevating means for holding the single crystal holding means as described above from above and elevating it along the growth axis of the silicon single crystal to be grown can be used at least in the initial stage of silicon single crystal ingot growth (from immersion of the seed crystal in the melt). In a stage until a portion to be gripped by the gripping member is formed in the silicon single crystal ingot), the specific configuration is particularly limited as long as it functions independently of the seed crystal elevating mechanism. Wire drive system consisting of a hanging wire and its winding mechanism, chain drive system,
Any method such as a rack and pinion driving method can be used.

Further, in the single crystal pulling apparatus of the present invention, the structure other than the silicon single crystal ingot gripping means, the fusing member and the lifting / lowering means of the gripping means as described above is such that at least the silicon melt is held in the chamber. Any crucible, a seed crystal holding means, and an elevating means for raising and lowering the seed crystal holding means can be used, and various conventionally known modes can be adopted.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below more specifically based on embodiments.

FIG. 1 is a schematic view showing a main part configuration in an embodiment of a silicon single crystal manufacturing apparatus according to the present invention in use, and FIG. 2A is a configuration of a single crystal holding means in still another embodiment. (B) is a sectional view taken along line BB in FIG. (A), and (c) is a sectional view taken along line CC in (a).

In the embodiment shown in FIG. 1, similarly to the conventional silicon single crystal pulling apparatus, a crystal holding mechanism support plate (shown in FIG. 1) which is rotated around the chamber axis by driving means such as a rotation motor is provided on the upper part of the chamber. And a seed crystal pulling wire 2 attached to a seed crystal pulling motor 1 installed on the support board is extended into the chamber along the axis of the chamber. A seed crystal holding unit (seed chuck) 3 is provided at the tip of the wire 2, and the seed crystal 4 mounted thereon drives the seed crystal pulling motor 1 (and the motor for rotating the support plate). Thus, a single crystal ingot can be grown by temporarily immersing in a silicon melt formed in a crucible (not shown) arranged in the chamber and then pulling it up while rotating.

In this embodiment, the single crystal ingot gripping means 10 provided in the apparatus in this embodiment is arranged around the axis of the chamber, and has a plurality of slits 11 along the axial direction at the lower end on the peripheral surface. A substantially cylindrical collet 13 whose lower end is gradually expanded in diameter to form a tapered portion 12, and a maximum outer diameter and a minimum inner diameter of a tapered portion of the splitter slidably fitted on an outer peripheral surface of the collet 13. And a cylindrical caulking tool 14 having the above inner diameter. In the present embodiment, the cuts 11 of the collet 13 are provided at four locations at equal intervals (90 °) in the circumferential direction, similarly to the embodiment shown in FIG.

The upper end of the collet 13 is formed by a collet connecting cylinder 15 fixed to the outer peripheral surface of the collet.
The cylindrical caulking device 14 is similarly extended out of the chamber by a caulking device connecting cylinder 16. And collet connecting cylinder 1
5 is coaxially disposed inside the caulking tool connecting cylinder 16, but both are displaceably engaged by an extendable and retractable cylinder mechanism 17 having a connection end on the outer peripheral surface thereof. When the cylinder mechanism 17 is expanded and contracted by a drive source (not shown), the relative position between the collet 13 and the caulking tool 14 connected to the lower end of each connecting cylinder changes, and the lower end of the collet 14, that is, the taper The diameter of the part 12 is enlarged or reduced. In the present embodiment, the cylinder mechanisms 17 are arranged at positions 180 ° apart in the circumferential direction. FIG. 2
In the embodiment shown in FIG. 7, a similar cylinder mechanism 17 is directly connected to the wall surfaces of the collet 13 and the cylindrical caulking device 14.

At the upper end of the collet connecting cylinder 15, three single crystal holding portion pulling wires 18 are connected and suspended at equal intervals (every 120 °), and these wires 18 are connected to a single crystal holding mechanism. Attached to the drive shaft of the pulling motor 19, the single crystal ingot gripping mechanism 10
Is capable of moving up and down in the chamber independently of the seed crystal holding unit 3 connected to the seed crystal pulling motor 1 by the seed crystal pulling wire 2, and
Transmission mechanism 20 and rotation motor 2 connected to motor 6
1 is rotated around the axis of the chamber in synchronization with the seed crystal holding unit. In addition,
In the drawing, reference numeral 22 denotes a chamber and a caulking tool connecting cylinder 16.
3 shows a seal portion.

The growth of a single crystal ingot using the apparatus of the embodiment having such a configuration is performed, for example, as follows.

First, based on a conventional method, the seed crystal pulling motor 1 is driven, and the single crystal 4 held at the tip of the seed crystal pulling wire 2 is immersed once in a silicon melt.
Thereafter, the single crystal 5 is grown at the lower end of the seed crystal 4 by pulling. After the dash neck 6 is formed by narrowing the diameter once to eliminate dislocations, the diameter is slightly increased to form the mini straight body 7, and then the diameter is further increased to form the cone 8, and the desired final shape is formed. When the diameter reaches the diameter, the formation of the straight body portion 9 is started.

Until this state, the collet 14 of the single crystal ingot gripping mechanism is held in the chamber at a position where it does not engage the mini straight body 7 of the single crystal ingot.

Further, as the straight body portion is raised and the mini straight body portion 7 enters the space inside the collet 14, the cylinder mechanism 17 expands and contracts, so that the collet 13 and the caulking tool 14 are moved relative to each other. The target position is changed, and the diameter of the tapered portion 12 at the lower end of the collet 14 is reduced.
The inner surface is pressed against the peripheral surface of the mini-straight body 7 to hold the mini-straight body 7. Thereafter, while maintaining the gripping state, the single crystal gripping mechanism pulling motor 19 is operated to wind up the single crystal gripping portion pulling wire 18, and the single crystal ingot gripping mechanism 10 is pulled upward, and the single crystal gripping portion is pulled up. By controlling the pulling speed of the pulling wire 18 and the seed crystal pulling wire 2, the single crystal ingot 5 is connected to a gripping means for raising the single crystal ingot and supporting the weight while supporting the single crystal ingot. The method is switched to pulling by the lifting means, and thereafter, single crystal growth is continued until the ingot has a desired length.

[0048]

As described above, in the present invention, the silicon single crystal ingot to be grown is gripped by the mechanical gripping mechanism during the pulling operation of the silicon single crystal ingot. The portion is formed directly below the dashes neck portion of the single crystal ingot as a mini straight body portion having a diameter larger than the dashes neck portion and sufficiently smaller than the desired final diameter of the single crystal ingot. Therefore, the gripper itself required for gripping this does not increase in size, for example, a structure similar to a collet chuck,
The structure can be made lightweight, simple and easy to operate, and the gripping means is not exposed to a high-temperature environment. Therefore, even if the lifting weight is increased due to the increase in diameter and length of the ingot, there is no danger of the single crystal ingot dropping or growing being interrupted due to breakage of the dash neck portion, and stable and reliable A high lifting operation becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram schematically showing a main part configuration of an embodiment of a single crystal pulling apparatus according to the present invention in a use state;

FIG. 2A is an enlarged cross-sectional view showing a configuration of a single crystal holding means in another embodiment of the single crystal pulling apparatus according to the present invention, FIG. 2B is a cross-sectional view taken along line BB in FIG.
(C) is a sectional view taken along line CC in (a).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 seed crystal pulling motor 2 seed crystal pulling wire 3 seed crystal holding unit 4 seed crystal 5 single crystal ingot 6 dash neck 7 mini straight body 8 cone 9 straight body 10 single crystal ingot gripping mechanism 11 slit 12 collet Tapered part 13 Collet 14 Cylindrical caulking tool 15 Collet connecting cylinder 16 Caulking tool connecting cylinder 17 Cylinder mechanism 18 Single crystal gripping part pulling wire 19 Single crystal gripping mechanism pulling motor 20 Rotation transmission mechanism 21 Rotary motor 22 Seal part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Morita 46-59 Nakahara, Toba-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Plant Design Co., Ltd.

Claims (4)

[Claims] 1. A method for producing a silicon single crystal in which a seed crystal is immersed in a silicon melt and the seed crystal is pulled up to grow a silicon single crystal ingot at the rear end of the seed crystal. After forming a small-diameter portion for dislocation-free silicon single crystal ingot, the diameter is increased to a diameter larger than the small-diameter portion and smaller than a final diameter of a desired ingot, and is constant at the diameter. It is characterized by forming a cylindrical gripped portion by long pulling, and further, gradually increasing the diameter of the single crystal ingot to a desired final diameter, and raising the straight body portion of the single crystal ingot by the final diameter. At a predetermined time in the process after the formation of the gripped portion to be performed, the gripped portion is moved to gripping means connected to a pulling mechanism independent of the seed crystal pulling mechanism. Grasping I, by raising the gripping means at a predetermined speed, a method for manufacturing a silicon single crystal, wherein the subsequent growth of a silicon single crystal ingot be carried out while supporting the single crystal ingot by the gripping means. 2. A method for producing a silicon single crystal in which a seed crystal is immersed in a silicon melt and the seed crystal is pulled up to grow a silicon single crystal ingot at the rear end of the seed crystal. Forming a small-diameter portion for dislocation-free silicon single crystal ingot, and then expanding to a diameter larger than the small-diameter portion and smaller than the final diameter of the desired ingot. After forming a cylindrical gripped portion by pulling up by a certain length, the diameter is gradually increased to a desired final diameter, and the straight body portion of the single crystal ingot is pulled up by the final diameter, and the straight body portion is being pulled up. The gripping portion connected to a pulling-up mechanism independent of the seed crystal pulling-up mechanism to grip the portion to be gripped of the silicon single crystal ingot. The gripping means by raising at a predetermined speed, the development of subsequent silicon single crystal ingot, a method for manufacturing a silicon single crystal which is characterized in that the pulling operation of said gripping means. 3. The method for producing a silicon single crystal according to claim 1, wherein the diameter of the gripped portion formed on the silicon single crystal ingot is about 8 to 100 mm. 4. A silicon single crystal manufacturing apparatus comprising: a crucible containing a silicon melt; and a seed crystal pulling means for dropping a seed crystal to the silicon melt by a seed crystal pulling striatum so as to be able to move up and down. The lower end part has a plurality of slits along the axial direction on the peripheral surface, and the lower end part is gradually enlarged in diameter to form a tapered part, and the outer peripheral surface of the splitter is slidable. A single crystal gripping means having a cylindrical caulking tool having an inner diameter not less than the maximum outer diameter and the minimum inner diameter of the tapered portion of the splitter fitted to the splitter, and the single crystal gripping means can be raised and lowered from above A gripper pulling means for suspending the single crystal; the splitter of the single crystal gripping means is disposed substantially coaxially with the seed crystal pulling striatum; Striatum Apparatus for producing a silicon single crystal, characterized in that there is a capable pass.