JPH11314998A - Silicon single crystal pulling equipment and pulling method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method and equipment for stably and highly reliably pulling a silicon single crystal even when the weight of the single crystal to be pulled is increased due to that a silicon single crystal ingot is made large in diameter and long in length. SOLUTION: This equipment having a crucible for receiving a melt and a seed crystal pulling means for freely elevating and lowering a seed crystal from/to the melt with a seed crystal pulling wire is also provided with a single crystal clamping means 10 which has a ring-shaped frame 12 having an inner peripheral surface that is formed as a taper face 11 donwwardly and gradually tapered, and a slider 13 placed slidably on the taper face 11 approximately in its expansion and contraction directions to expand or contract a lower end opening of the ring-shaped frame 12 by the sliding movement. In the equipment, an engagement stepped part 9a is formed in an ingot to be grown, an engaged state between the single crystal clamping means 10 an the engagement stepped part 9a is formed by bringing their surface into contact with each other at a prescribed point of time in the pulling process after formation of the engagement stepped part 9a, then the single crystal clamping means 10 is pulled up with a single crystal clamping mechanism pulling wire separately provided, and the following single crystal growth is performed while supporting the ingot with the clamping means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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.
Japanese Patent Application Laid-Open No. 62-288191 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. JP-A-63-25299
No. 1 and JP-A-3-285893,
In the so-called cone portion, which expands to the desired diameter after the dislocation is eliminated by the dash neck portion, the diameter is temporarily reduced to form a crack portion (anchoring step portion), and a locking member such as a nail or a cam is formed in this portion. There is disclosed a method in which a gripping means for gripping an ingot is separately provided by pulling a single crystal, and the single crystal is pulled up and down by raising and lowering the gripping means.

[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.

Also, Japanese Patent Application Laid-Open No. Sho 62-288191,
JP-A-63-252991 or JP-A-Heisei 3-2
In the technique disclosed in Japanese Patent No. 85893, the single crystal ingot is held by claws, cams, and the like, and the contact is point contact. As the weight of the ingot increases, the load concentrates on the contact point, There is a fear that the silicon single crystal may be broken due to the cleavage, and that the silicon single crystal may fall. In addition, fine irregularities of about several millimeters called growth stripes inevitably occur on the surface of the single crystal ingot, and this also occurs at the mooring step, as described above. There has been a concern about a decrease in gripping reliability due to one-sided contact of the member contact surface. Further, the operation mechanism of the gripping means for gripping the mooring step formed on the ingot is complicated, and the gripping means itself is not only large and complicated, but also it is difficult to accurately operate at a desired time to hold the single crystal. there were.

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 thereof, but none of them has been satisfactory.

Accordingly, it is an object of the present invention to provide a novel silicon single crystal pulling method and a silicon single crystal pulling apparatus. The present invention also provides a silicon single crystal pulling method and a silicon single crystal pulling apparatus capable of stably and reliably pulling a silicon single crystal ingot to be stably and reliably even if the weight of the silicon single crystal ingot to be grown is increased due to an increase in diameter and length. It is an object to provide The present invention further provides a relatively simple operation and a simple mechanism, even if the lifting weight is increased.
An object of the present invention is to provide a silicon single crystal pulling method and a silicon single crystal pulling apparatus that can be pulled stably and with high reliability.

[0014]

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. When pulling up, the holding means is provided with a variable member which is arranged in an annular shape so as to be movable in the direction of expansion and contraction with respect to the axis of the holding means, and furthermore, the variable member has a mooring step formed on the silicon single crystal ingot. An operation of providing an abutment surface that comes into contact with the surface of the mooring step from below and that can surround and support the peripheral surface of the mooring step, and disposing the abutting surface at a position that makes surface contact with the mooring step is arranged in an annular manner. The outer diameter of the ingot at the contact position in the temporal contact between the outer peripheral wall surface of the silicon single crystal ingot and the end portion of the variable member that protrudes along the axis into the central space of the variable member. If configured to be automatically performed by the diameter fluctuation, it found that it is possible desired good mechanical grip, and have reached the present invention.

That is, the present invention for solving the above-mentioned problems has the following features:
(1) In a silicon single crystal manufacturing apparatus having a crucible for accommodating a silicon melt and a seed crystal pulling means for allowing a seed crystal to drop vertically by a seed crystal pulling striatum on the silicon melt, At least one surface of the surface and the outer peripheral surface is a downwardly tapered annular frame body that is gradually reduced in diameter, and is attached to the annular frame body so as to be slidable on the tapered surface substantially in the expansion and contraction direction, A gripper having a slider for expanding and contracting a lower end opening of the annular frame by the sliding; and a gripper pulling means operable independently of the seed crystal pulling means. A silicon single crystal pulling apparatus characterized in that the holding means can be moved up and down along the growth axis of the silicon single crystal to be grown.

Further, according to the present invention, (2) a contact portion with a silicon single crystal formed of a bag-like body deformable by an external force provided with a filler therein is provided on an upper side surface of the slider. The apparatus for pulling a silicon single crystal according to the above (1), wherein

Further, the present invention for solving the above problems is
(3) A method for pulling a silicon single crystal using the silicon single crystal pulling apparatus according to the above (1) or (2), wherein the seed crystal is immersed in a silicon melt and the seed crystal is pulled. In growing the silicon single crystal ingot at the rear end of the seed crystal, a dashes neck portion for dislocation-free silicon single crystal ingot to be grown is formed immediately below the seed crystal, and then a dashes neck portion is formed. After gradually increasing the diameter to a first diameter smaller than the final diameter of the desired ingot to form a substantially conical mooring step upper surface portion, the diameter is smaller than the first diameter and smaller than the dashes neck. The diameter is gradually reduced again to a second diameter having a large diameter to form a lower surface portion of the mooring step portion having a substantially inverted conical shape. The mooring step is formed by gradually increasing the diameter of the single crystal ingot to a desired final diameter and raising the straight body of the single crystal ingot by the final diameter. At a predetermined time in a later process, the single crystal gripping means is held at a position where the single crystal ingot is engaged with the outer peripheral surface of the single crystal ingot, and the mooring step of the single crystal ingot is inserted into the annular frame of the gripping means from the lower end opening. The slider slides upward once by coming into contact with the upper surface portion of the mooring step and moves so as to expand the lower end opening. After the upper surface of the slider can support the lower surface portion of the mooring step by moving in the diameter reducing direction, the gripping unit is moved to a predetermined position by a pulling unit independent of a seed crystal pulling unit. speed It is pulled up, 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.

[0018]

As described above, in the present invention, when the silicon single crystal ingot to be grown is mechanically gripped and pulled up separately from the seed crystal pulling mechanism, the tapered surface as described above is used as the gripping means. Since it has a structure including an annular frame having a slider and a slider which moves along the tapered surface and makes the lower end opening of the annular frame expandable and contractable, the silicon single crystal ingot to be grown is described above. A mooring step having a desired shape is formed, and only the time-dependent contact between the mooring step and the slider is accompanied by an ingot lifting operation, so that the gripping means can automatically support the mooring step. And the contact is surface contact. Therefore, even if the lifting weight increases, the lifting can be performed stably and with high reliability. As described above, the structure of the gripping means is also simple, and it is possible to reduce the weight, size, and cost. Also, the operation required for gripping is extremely simple, and the workability is good.

Furthermore, in the present invention, if the contact surface of the slider with the ingot is constituted by a bag-like body which can be deformed by an external force containing a filler therein, a higher surface contact with the ingot is achieved. And the stability and reliability of the lifting operation are improved.

[0020]

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 a dopant to be added as required is charged 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 a pulling means connected to the seed crystal holding means, and a single crystal is grown at the lower end of the seed crystal.

Then, 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. After gradually expanding to a first diameter that is large and smaller than the desired final diameter of the ingot to form a substantially conical mooring step upper surface portion, the diameter is smaller than the first diameter and smaller than the dashes neck. Is gradually reduced again to a large second diameter to form a substantially inverted cone-shaped mooring step lower surface portion, and a mooring step to be moored by the gripping means is formed on the silicon single crystal ingot to be grown. The first diameter and the second diameter are not particularly limited, and depend on the size of the final diameter of the ingot to be grown, the length of the ingot, and the like. ~ 300m
m, more preferably about 5 to 50 mm, while the first diameter is 1.2 to 3 of the second diameter.
A diameter of about 2 times, more preferably about 2 to 12 times is generally desirable. When the second diameter is within the above range, if the diameter is smaller than 4 mm, it depends on the final diameter and length of the single crystal ingot to be pulled, but the single crystal is supported by the mooring step. When the second diameter portion is lifted, there is a possibility that the second diameter portion cannot exhibit sufficient mechanical strength to support the weight of the single crystal ingot. The reason is that the meaning of grasping is reduced, while the diameter is 300
If it exceeds mm, it is necessary to increase the size of the gripping means for gripping the mooring step, and neither is suitable. In addition, the first diameter is equal to 1 .2 of the second diameter.
When the diameter is less than 5 times, the substantially inverted conical mooring step portion lower surface portion formed by gradually reducing the diameter from the first diameter to the second diameter, that is, when supporting the single crystal ingot by the gripping means described later. This is because the area and the inclination angle of the contact surface cannot be made sufficient, and there is a possibility that stable support cannot be performed. On the other hand, the first diameter is 32 of the second diameter.
If the number is more than twice, it is necessary to increase the size of the gripping means for gripping the mooring step, which is not appropriate.

The inclination angle of the lower surface of the substantially inverted conical mooring step formed at the lower end of the mooring step is not particularly limited.
And more preferably about 60 to 90 °. That is, if the taper angle is smaller than 1 °, there is a possibility that when the lower surface is supported by the gripping means, slippage occurs between the contact surfaces and stable support cannot be performed. If the angle is larger than 160 °, the slider of the gripping means described later has an outer diameter of the ingot of the first type.
This is because, when the slider is located at a portion reduced in diameter from the diameter to the second diameter, there is a possibility that the slider does not move well in the diameter reducing direction only due to its own weight. The inclination angle of the upper surface of the substantially conical mooring step formed on the upper end side of the mooring step is not particularly limited, but for example, it is desirable that the taper angle be about 180 ° or less. In addition,
It is not always necessary to make the inclination angle of the upper surface equal to the inclination angle of the lower surface. Further, as for the shape of the mooring step, it is not always necessary to form the lower surface of the substantially inverted conical mooring step directly below the upper surface of the substantially conical mooring step to have a rhombic cross section. There is no particular problem even if a cylindrical portion having a diameter is provided.

After the mooring step 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, melt temperature, and the like.

According to the present invention, the mooring step is grasped by a grasping means described later at a desired time in the process after the formation of the mooring step, and the seed crystal is connected to the grasping means. By moving the gripping means upward by the gripper pulling means operable independently of the pulling means, the growth of the single crystal after gripping can be carried out from the pulling by the pulling means connected to the seed crystal holding means to the gripping means. The pulling is switched to pulling by pulling means connected to, and thereafter, single crystal growth is continued until the ingot has a desired length.

In the present invention, immediately after the mooring step is formed, the mooring step is gripped by gripping means.
It is naturally possible to perform the subsequent single crystal growing operation by switching to the pulling by the pulling means connected to the gripping means, but immediately after the mooring step is formed, the surface temperature of the mooring step is considerably high. In addition, a portion having a sufficiently large diameter below the mooring step portion, that is, the cone portion and the straight body portion have not been formed yet, and the mooring step portion is receiving a large amount of radiant heat from the silicon melt. Therefore, in such an embodiment, the gripping means is exposed to a high temperature for a while from the gripping time. Therefore,
Preferably, this gripping is performed at a stage where a cone portion and a certain straight body portion are formed below the mooring step portion, that is, the mooring step portion moves upward in the single crystal manufacturing apparatus and the surface temperature thereof decreases to some extent. It is desirable to perform the process at a stage where the radiant heat from the silicon melt is blocked by the cone portion and the straight body portion. The surface temperature of the mooring step at the desired gripping time is particularly limited because it depends on the configuration of the single crystal manufacturing apparatus used, the diameter (final diameter) of the silicon single crystal to be grown, and the like. Although it is not a thing, for example, it is about 400 to 1000 ° C.

In the above description, in order to facilitate the description, in the stage until the mooring step is gripped by the mechanical gripping means, the mooring step is pulled up by the pulling means connected to the seed crystal, and In, it has been described that the lifting is performed by the lifting means connected to the gripping means, but in practice, it is not always necessary to perform such strict switching, for example, after gripping, for example, on the gripping means side Assuming that the moving speed of the pulling means and the pulling means on the seed crystal side are substantially the same, it is also possible to perform pulling by dispersing the load of the ingot on both sides, in short, after gripping the mooring step. The gripping means may be in such a state that the gripping means supports 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 pulling means on the seed crystal side is set to be faster than the moving speed of the pulling means on the holding means side. It is necessary to increase the moving speed on the tool side and synchronize with the pulling speed of the pulling means on the seed crystal side, and then gradually reduce the pulling speed of the pulling means on the seed crystal side. Is not transmitted to the single crystal growth interface.

Next, a silicon single crystal pulling apparatus according to the present invention will be described.

A silicon single crystal pulling apparatus according to the present invention comprises: a crucible containing a silicon melt; and a seed crystal pulling means for allowing a seed crystal to hang up and down on the silicon melt by a seed crystal pulling filament. In the silicon single crystal manufacturing apparatus having at least one of the inner peripheral surface and the outer peripheral surface is a downwardly tapering annular frame body that gradually decreases in diameter, and on the taper surface along the expansion and contraction direction substantially along Slidably attached to the annular frame,
A gripper having a slider for expanding and contracting a lower end opening of the annular frame by the sliding; and a gripper pulling means operable independently of the seed crystal pulling means. The gripping means can be moved up and down along a growth axis of a silicon single crystal to be grown.

In the single crystal manufacturing apparatus of the present invention, the surface of the annular frame to which the slider is attached may be either the inner peripheral surface or the outer peripheral surface as described above. The inner peripheral surface side located above the surface is preferable. That is, if it is set as the inner peripheral surface side, the lower surface side of the slider can be used as a mounting surface to the annular frame body, and the contact surface of the ingot provided on the upper surface side of the slider,
This is because not only the degree of freedom of the positional relationship is increased, but also there is no possibility that a large load is applied to the connecting portion between the slider and the annular frame when the load of the ingot is supported on the upper surface side of the slider.

The connection structure for slidably mounting the slider in the direction of expansion and contraction of the tapered surface can be exemplified by, for example, a structure comprising orbital projections and fitting grooves for the projections, but is not limited to these. Various forms known in the art can be adopted without the need. In order to obtain even better sliding, members such as bearings, wheels and balls may be arranged on the connection surface, and elastic mechanisms such as springs and cylinders for promoting movement in the diameter reducing direction. Can also be added.

In the gripping means, the lower end opening of the annular frame must have a diameter at least larger than the first diameter of the mooring step to be formed on the single crystal to be grown. In the position where the diameter of the lower end opening is reduced most, the slider is reduced in diameter to at least a diameter smaller than the first diameter of the mooring step portion, and more preferably to a diameter substantially similar to the second diameter. On the other hand, at the position where the diameter is expanded most, it is necessary that the diameter is not reduced at all at the lower end opening, or even if the diameter is reduced, it is larger than the first diameter to some extent. Furthermore, the inclination angle of the tapered surface on which the slider of the annular frame is mounted is not particularly limited, but in the radially expanding direction of the slider due to the contact of the end of the slider with the upper surface of the mooring step of the ingot. Movement, and when the contact state of the end of the slider with the upper surface of the mooring step of the ingot is released, the slider is moved by its own weight in the diameter reducing direction, for example, by a taper angle. Is 10 to 160
゜, more preferably about 60 to 90 °.

The slider has a contact surface which spreads almost uniformly in the entire circumferential direction around the axis of the ingot at the position where the diameter is reduced most, that is, at the position where the lower surface of the mooring step of the ingot is supported. It is desirable to be configured so that two or more
More preferably, the number of sliders is three or four, but the number of sliders may be two as long as the contact surface of each slider is sufficiently wide. Further, the total contact surface formed by the respective contact surfaces of the plurality of sliders in a state of supporting the lower surface side of the mooring step portion of the ingot is a state that occupies substantially the entire circumferential direction of the ingot. Is naturally most preferable, but it is not necessarily required to be formed continuously over the entire circumference, and if they are substantially evenly distributed, a total of at least 30%, more preferably about 50% of the angular portion of the entire circumference is occupied. Is enough.

Also, the length of the abutment surface of the slider, when it comes into surface contact with the lower surface of the mooring step of the ingot,
There is no particular limitation as long as a sufficient holding force can be exhibited, but for example, it is about 30 to 100 mm.

The angle of inclination of the contact surface of the slider is such that the lower surface side of the mooring step is formed so that good surface contact can be made when the lower surface of the mooring step of the ingot is supported. This is equivalent to the angle to be used above. If this angle difference is, for example, 160 ° or more, surface contact becomes substantially impossible.

Further, the material constituting each member such as the slider and the annular frame of the gripping means, particularly the portion which can be brought close to the surface of the ingot, is not particularly limited as long as it has sufficient heat resistance. Although not a thing, for example, Si
It can be composed of ceramics such as C, Si ₃ N ₄ , Al ₂ O ₃ , ZrO ₂ , heat-resistant metals such as Mo, Ti, Nb, W, heat-resistant steel, carbon, silicon and the like.

Further, in the present invention, the abutment surface formed on the upper end surface side of the slider is a bag which is disposed on the upper end surface side of the slider and can be deformed by an external force containing a filler therein. It is desirable to be formed by a shape. That is, if the contact surface is formed by the surface of such a bag-like body, the load is applied to the contact surface of the gripping means, and the load is applied to the contact surface according to irregularities such as growth stripes on the surface of the ingot. The contact part is deformed and can contact the ingot evenly, and the load of the ingot can be evenly distributed over the entire contact surface without causing problems such as the occurrence of concentrated stress due to one-sided contact. Can be supported, so that stability and reliability in gripping are further improved.

The bag-like body typically has a pillow-like structure having a certain porosity and some kind of filling material arranged in a predetermined volume. For example, a plurality of granular bodies, porous bodies, fibers, It is composed of a bulky assembly and the like, and a flexible sheet or foil-like surrounding body that covers these fillers from the outside.

As the granular material, for example, a sphere is typical, but the shape is not particularly limited to a sphere unless the shape is such that a chipped piece is likely to occur due to contact between the granules. Absent. Also, the size is not particularly limited, and can be appropriately selected according to the size of the irregularities generated on the surface of the silicon single crystal ingot to be manufactured. Those having a size of about 0.5 to 1.0 mm can be suitably used. The dimensional accuracy, sphericity and the like of the granular material represented by such a spherical body are not so required.

Further, by using two or more granules having different sizes in combination,
The filling rate can be improved, and a more stable gripping force can be expected.

It is desired that the material constituting such a granular material has sufficient heat resistance and strength. For example, SiC, Si ₃ N ₄ , Al ₂ O ₃ , ZrO ₂
And heat-resistant metals such as Mo, Ti, Nb and W. Balls made of these materials are commercially available, for example, as balls for ball mills, balls for bearings, and the like, and these can be diverted.

As the porous body, for example, a metal sponge or the like as a sintered body can be exemplified. The bulky fiber assembly is a so-called “metal scoop”, which is formed by shrinking a narrow band of fiber or metal foil. And a material formed by using a heat-resistant metal foil such as carbon fiber or Ta as a raw material.

When a porous body or a bulky fiber aggregate is used, the habit is easily attached to the porous body or the bulky fiber aggregate in a single use (gripping operation), and the restoration property is poor. A configuration using rigid granular material such as a spherical body is particularly desirable because it may not be very suitable for use.

The surrounding body for holding such a filling material in a predetermined space is not particularly limited as long as it has sufficient flexibility and sufficient strength and heat resistance. Examples thereof include, but are not limited to, heat-resistant metal foils such as Ta having high ductility, heat-resistant metal fibers such as W, and nets or fabrics woven with carbon fibers. In particular, T
A net or a fabric made of a heat-resistant metal foil such as a or a heat-resistant metal fiber such as W is preferable because there is no risk of fluffing or dust generation. In addition, the thickness of the surrounding body is not particularly limited as long as it has sufficient flexibility while exhibiting sufficient strength, and depends on the material. In the case of (1), about 0.5 to 5.0 mm is appropriate.

The porosity of such a pillow-like structure depends on the size of the irregularities formed on the surface of the silicon single crystal ingot to be gripped, the granular material, the porous material, and the bulkiness of the fiber used. Although it depends on the type of packing such as the body, in an uncompressed state without applying external force,
It is desirable to be about 30 to 80%.

The method of attaching the above-described bag-like body to the upper surface of the slider is not particularly limited. For example, such a bag-like body may be screwed to the upper surface of the slider. A method of locking with an adhesive, a method of forming a mounting concave portion and fitting a bag-like body, and a method of using these in combination can be adopted.

Further, in the single crystal manufacturing apparatus of the present invention,
The structure of the pulling means for holding the above-mentioned single crystal holding means from above and moving it up and down 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). Until the holding means can support the silicon single crystal ingot), the specific configuration is not particularly limited as long as it functions independently of the elevating and lowering mechanism of the seed crystal. Instead, an arbitrary system such as a wire driving system including a hanging wire and its winding mechanism, a chain driving system, and a rack and pinion driving system can be used.

Further, in the single crystal pulling apparatus of the present invention, as a configuration other than the silicon single crystal ingot gripping means, the fusing member and the lifting / lowering means of the gripping means as described above, 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.

[0050]

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

FIGS. 1 to 3 are diagrams schematically showing the configuration of a main part of an embodiment of a silicon single crystal pulling apparatus according to the present invention in use.

As shown in FIG. 1, in this embodiment, as in the conventional silicon single crystal pulling apparatus, a quartz crucible 1a and a graphite crucible 1 surrounding the crucible 1a.
The crucible 1 made of b is installed at the center of the chamber by a rotating support shaft (not shown). On the other hand, on the upper part of the chamber, a crystal holding mechanism support plate 3 that is rotated around the chamber axis by a rotation motor 5 is provided, and a seed crystal pulling wire attached to a seed crystal pulling motor 4 installed on the support plate 5 is provided. 2 extends into the chamber along the axis of the chamber. A seed crystal holding unit (seed chuck) 6 is provided at the tip of the wire 2, and the seed crystal 7 attached thereto is driven by the seed crystal pulling motor 4 (and the rotation motor 5). Thus, the single crystal ingot 9 can be grown by immersing it in the silicon melt 8 formed in the crucible 1 and then pulling it up while rotating.

In this embodiment, however, the single crystal ingot gripping means 10 is provided in the chamber with a single crystal gripping mechanism pulling motor 24a mounted on the same support plate 3 as that on which the seed crystal pulling motor 4 is mounted. , 2
Are suspended by a plurality of single crystal gripping mechanism pulling wires 22a, 22b... Attached to the drive shafts 4b..., And can be moved up and down in the chamber independently of the seed crystal holding unit 6. In addition, it rotates around the axis in synchronization with the seed crystal holding unit.

As shown in FIG. 2, this gripping means 10
An inner peripheral surface 11 includes an annular frame 12 having a tapered surface whose diameter is gradually reduced toward the lower side, and three sliders 13 disposed on the inner peripheral surface. A length from the vicinity of the lower end opening 14 to the vicinity of the upper end opening 15 along the direction of expansion and contraction of the inner peripheral surface, provided on the inner peripheral surface of the annular frame 12 at intervals of about 60 ° in the circumferential direction. Three convex orbits 1 with
6, each of which has a substantially fan-shaped slider 13 having an outline formed by connecting two concentric arcs of different diameters having an arc width of about 60 ° with straight lines at respective ends. It is slidably attached to the convex track 16 by a fitting groove (not shown) provided in the center part on the side. Accordingly, the slider 13 can expand and contract the diameter of the lower end opening 14 by the movement by the sliding.

A pillow-like structure 17 in which a filler made of a plurality of beads and having a certain porosity is accommodated in a bag made of a highly ductile heat-resistant metal foil is joined to the upper surface of the slider 13. And forms a contact surface that can be deformed by external force.

The single crystal pulling operation using the apparatus having such a configuration is performed as follows.

First, based on a conventional method, a predetermined amount of raw materials such as polycrystalline silicon and an optional dopant is loaded into a crucible 1 arranged in a single crystal pulling apparatus and heated by a heater or the like. The raw material is melted to form a melt 8, and the melt is added to the seed crystal 7 held by the seed crystal gripper 6.
Is immersed once, and then pulled up while rotating the seed crystal around an axis by a pulling means connected to the seed crystal gripping means, to grow a single crystal 9 at the lower end of the seed crystal.

Then, in order to eliminate dislocations, the diameter is once increased to 3 to
After forming the dash neck portion by squeezing to about 4 mm, the diameter is gradually increased, and gradually increased to a first diameter larger than the diameter of the dash neck portion and smaller than the final diameter of the desired ingot. After forming the upper surface portion of the substantially conical mooring step portion, the diameter is gradually reduced again to a second diameter smaller than the first diameter and larger than the dashes neck portion, and the substantially inverted conical mooring step portion is formed. A lower surface portion is formed, and a mooring step 9a moored by the gripping means is formed on the silicon single crystal ingot to be grown.

During this period, the gripping means 10 does not allow the ingot 9 to be hung and supported by the dash neck portion, and the lifting position and the ingot surface temperature are determined by the gripping means 10.
Is placed at a position below the heat-resistant temperature of. The turning of the gripping means is synchronized with the turning of the ingot to be grown (see FIG. 3A).

The mooring step 9 is attached to the silicon single crystal ingot 9.
After forming a, the diameter of the grown single crystal is gradually increased again to form a cone portion, and after reaching the desired diameter, the pulling speed, the melt temperature, etc. are controlled so as to maintain the desired diameter. The process of forming the torso begins.

As the silicon single crystal growing operation proceeds, the single crystal ingot 9 enters from the lower end opening 14 of the holding means 10 waiting in the upper space as described above, and the lower end opening 14 is formed.
At the lower end of the slider 13 located on the side, the mooring step 9a
When the substantially conical upper end surface comes into contact, the slider 13 is pushed by the ingot 9 and slides upward on the inner surface of the annular frame 12, and as a result, the lower end opening 14 is expanded in diameter. (See FIG. 3b). When the ingot further moves upward and the lower end of the slider 13 in contact with the surface of the ingot 9 gets over the maximum diameter portion (first diameter portion) of the mooring step 9a, the lower end of the slider 13 and the surface of the ingot are moved. Is released, the slider 13 loses the force pushed upward, slides instantly downward by its own weight, returns to the reduced diameter position, and is thereby provided on the upper surface side of the slider 13. The ingot gripping state of the gripping means 10 is formed in which the surface of the pillow-like structure 17 is in surface contact with the inverted conical lower end surface of the mooring step 9a (see FIG. 3C).

In this state, the single crystal gripping mechanism pulling motors 24a, 24b,... Are operated, and the gripping means 10 is moved upward at a controlled growth rate by pulling wires 22a, 22b. Then, the pulling by the pulling means connected to the seed crystal holding means is switched to the pulling by the pulling means connected to the holding means 10, and then the single crystal is grown until the ingot has a desired length.

[0063]

As described above, according to the present invention, when the silicon single crystal ingot to be grown is mechanically gripped and pulled up separately from the seed crystal pulling mechanism, the gripping means is used. A silicon frame to be grown is composed of an annular frame having such a tapered surface and a slider which moves along the tapered surface and makes the lower end opening of the annular frame freely expandable and contractable. A mooring step having a desired shape as described above is formed on the crystal ingot, and only the time-dependent contact between the mooring step and the slider is accompanied by the ingot pulling operation, so that the gripping means automatically makes the mooring. The stepped portion can be in a supportable state, and the contact is surface contact. Therefore, even if the lifting weight increases, the lifting can be performed stably and with high reliability. . As described above, the structure of the gripping means is also simple, and it is possible to reduce the weight, size, and cost. Also, the operation required for gripping is extremely simple, and the workability is good.

Further, in the present invention, if the contact surface of the slider with the ingot is constituted by a bag-like body which can be deformed by an external force containing a filler therein, a higher surface contact with the ingot is achieved. And the stability and reliability of the lifting operation are improved.

[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;

2A is a cross-sectional view schematically showing the configuration of the gripping means of the embodiment in a used state, FIG.

FIGS. 3A to 3C are cross-sectional views illustrating an operation state of the gripping means.

[Explanation of symbols]

 1a Quartz crucible 1b Graphite crucible 1 Crucible 2 Seed crystal pulling wire 3 Crystal holding mechanism support plate 4 Seed crystal pulling motor 5 Motor for rotating support plate 6 Seed crystal holding unit 7 Seed crystal 8 Silicon melt 9 Single crystal ingot 9a Ingot Mooring step 10 monocrystalline ingot gripping means 11 inner peripheral surface of annular frame 12 annular frame 13 slider 14 lower end opening 15 upper opening 16 convex track 17 pillow-like structure 22 single crystal gripping mechanism pulling wire 24 single crystal gripping mechanism Pulling motor 44 Seed crystal pulling motor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Morita 46-59 Nakahara, Oaza, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Plant Design Co., Ltd. (72) Masao Yamamoto 1-13-122 Shimada, Hikari-shi, Yamaguchi Prefecture No. Nippon Steel Elex Co., Ltd.

Claims (3)

[Claims] 1. 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 vertically movable. An annular frame having at least one of an inner peripheral surface and an outer peripheral surface facing downward and having a tapered surface whose diameter is gradually reduced, and mounted on the annular frame so as to be slidable on the tapered surface substantially along the expansion / contraction direction. A single crystal gripping means having a slider for expanding and contracting the lower end opening of the annular frame body by sliding, further comprising a gripper pulling means operable independently of the seed crystal pulling means, An apparatus for pulling a silicon single crystal, wherein the single crystal holding means can be moved up and down along the growth axis of the silicon single crystal to be grown. 2. An upper surface side of said slider is provided with a contact portion with a silicon single crystal made of a bag-like body deformable by an external force containing a filler therein. The apparatus for pulling a silicon single crystal according to claim 1. 3. A method for pulling a silicon single crystal using the apparatus for pulling a silicon single crystal according to claim 1 or 2, wherein the seed crystal is immersed in a silicon melt and the seed crystal is pulled. In growing the silicon single crystal ingot at the rear end of the crystal, a dashes neck portion for dislocation-free silicon single crystal ingot to be grown is formed immediately below the seed crystal, and then has a diameter larger than the dashes neck portion. Is gradually increased to a first diameter smaller than the final diameter of the desired ingot to form a substantially conical mooring step upper surface portion, and then smaller than the first diameter and smaller than the dashes neck. The diameter is gradually reduced again to a second diameter having a larger diameter to form a lower surface portion of the substantially inverted conical mooring step portion. The mooring step is further formed by gradually increasing the diameter of the single crystal ingot to a desired final diameter and raising the straight body of the single crystal ingot by the final diameter. At a predetermined time in a later process, the single crystal gripping means is held at a position where the single crystal ingot is engaged with the outer peripheral surface of the single crystal ingot, and the mooring step of the single crystal ingot is inserted into the annular frame of the gripping means from the lower end opening. The slider slides upward once by contacting the upper surface portion of the mooring step portion and moves to expand the lower end opening, and then contracts again after the first diameter portion of the mooring step portion has passed. After moving in the radial direction and allowing the upper surface portion of the slider to support the lower surface portion of the mooring step, the gripping means is pulled at a predetermined speed by pulling means independent of the seed crystal pulling means. By gel,
A method for producing a silicon single crystal, wherein the subsequent growth of the silicon single crystal ingot is performed while supporting the single crystal ingot by the gripping means.