JPH1081581A - Single crystal pulling up apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal-lifter which can safely lift up the single crystal with no occurrence of falling of the single crystal, when the single crystal of a heavy weight is produced. SOLUTION: This single crystal-lifter is equipped with a wire type main lifter 21 for forming the reversed cone shape of connection part 6 on the single crystal to be pulled up, a holding mechanism 11 for gripping the connection part 6 through the connection part and a wire-type sub-lifter 22 for lifting the holding mechanism 11. In this case, a means for inhibiting the holding mechanism 11 from inclining is set to the sub lifter 22 to lift the holding mechanism synchronously with the pulling-up speed of the main lifter 1. The motor for driving the main lifter and the sub-lifter is preferably controlled by the speed control as well as by the tension control. Further, the holding mechanism is preferably provided with a connection part having a clamp nail 13, a link lever 14, a pin or a long hole and has a shape matching to the connecting part to be connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulling apparatus for producing a single crystal by the Czochralski method (hereinafter, referred to as "CZ method"). The present invention relates to a single crystal pulling device that can be safely pulled up without dropping.

[0002]

2. Description of the Related Art There are various methods for producing a single crystal. Among them, the CZ method is widely applied in a method capable of industrial mass production for growing a silicon single crystal.
In the production of a single crystal by this method, the seed crystal is brought into contact with the surface of the melt of the crystal raw material contained in the crucible, and the crucible is rotated, and the seed crystal is pulled upward while rotating in the opposite direction. Thereby, a single crystal in which the melt is solidified grows at the lower end of the seed crystal.

In the case of producing a single crystal by the CZ method, it is necessary to completely remove dislocations generated by heat shock when the seed crystal is brought into contact with the melt so that the dislocation does not reach the body of the single crystal. There is. Usually, as this measure, in order to eliminate dislocations from the crystal surface and make the single crystal dislocation-free,
A so-called "dash neck processing" for narrowing the diameter into an elongated shape is employed. At this time, the diameter of the dashes neck necessary for eliminating dislocations is about 3 mm, and its length is required to be 30 mm.

Conventionally, the weight of a single crystal manufactured by the CZ method has been limited to about 20 to 30 kg. However, in recent years, there has been a strong demand for more efficient semiconductor manufacturing. And the weight of the single crystal is 100 kg
In many cases. The weight of the single crystal is borne by the narrowed dash neck portion. However, as described above, even if the weight of the manufactured single crystal increases, the load that can be borne is limited. If the single crystal becomes too heavy and torsional or bending stress is applied during pulling, the dash's neck of the single crystal will break, and the single crystal will fall into the melt in the crucible, further damaging the pulling equipment. , Outflow of molten liquid, explosion of steam, etc. may occur, leading to personal injury.

Therefore, an improved pulling device has been proposed for the purpose of preventing an accident such as a drop during pulling which is expected to occur frequently with an increase in the weight of a single crystal (FIG. 1). For example, JP-A-3-285893, JP-A-3-285893
295893). That is, by forming an engaging step on the upper part of the single crystal and adopting a structure in which the engaging step is engaged and gripped by a plurality of claws or a plurality of grip holders having claws, The single crystal is prevented from falling. For this reason, the use of the proposed pulling apparatus makes it possible to pull up a single crystal reliably and safely even when pulling a heavy single crystal.

[0006]

In the lifting apparatus disclosed in Japanese Patent Application Laid-Open Nos. 3-285893 and 3-295893, as described above, the engaging step formed on the single crystal is formed by a claw,
Alternatively, a gripping holder having claws is engaged and gripped. At this time, eliminating a deviation between the center position of the pulled single crystal and the pulling axis is an important management item in terms of quality.
Therefore, in the above-described lifting device, a plurality of claws or a plurality of grip holders are provided as a countermeasure for them, and the positional deviation is eliminated by fine adjustment of each nail or the grip holder, and the engagement / step at the engagement step portion is performed. The grip is secure.

However, since the pulling of the single crystal is performed in a closed vacuum chamber, the operation of the claw or the gripping holder must be controlled from the outside so as to match the engaging step of the single crystal which is constantly rising and rotating. It is very difficult to fine-tune by remote control. Therefore, the adjustment of the position where the engagement step portion is engaged and gripped tends to be inconvenient, and once a displacement occurs, not only does the quality of the pulled single crystal significantly deteriorate, but also the single crystal is pulled during the pulling. In addition, the single crystal may be greatly inclined due to the torsion, and the nail or the grip holder may be disengaged to drop the single crystal.

SUMMARY OF THE INVENTION The present invention solves the above-described problems of the conventional pulling apparatus, and ensures engagement and gripping at an engaging step provided on a single crystal, thereby achieving a heavy weight single crystal. It is an object of the present invention to provide a single crystal pulling apparatus which can appropriately manufacture a single crystal without causing a fall accident even when pulling a single crystal and is excellent in safety.

[0009]

SUMMARY OF THE INVENTION The present invention relates to FIGS.
As shown in FIG. 6 and FIG. 8, the following single crystal pulling apparatus is the gist.

That is, a wire-type main pulling means for forming an inverted conical engaging step on a single crystal which is pulled up while being rotated, and the engaging step of the single crystal is gripped via an engaging member. A single crystal pulling apparatus including a holding mechanism and a wire-type sub-pulling-up means for raising and lowering the holding mechanism, wherein the sub-pulling-up means raises and lowers the holding mechanism via a tilt preventing means of the holding mechanism, and A single crystal pulling apparatus characterized in that the holding mechanism is raised in synchronization with the pulling speed of a main pulling means (see FIGS. 1 and 6).

In the above-mentioned lifting device, it is desirable that one of the main lifting means and the sub-lifting means is of a speed control type and the other is of a tension control type. By adopting such a control method,
The single crystal can be pulled while adjusting the pulling speed of the single crystal and the load sharing of the main pulling means and the sub-pulling means.

As the engaging member of the above-mentioned holding mechanism, a member having a self-clamp function for canceling the unevenness of the circumferential shape of the engaging step portion by the action of the link lever or the clamp lever is used. Thereby, even if the shape of the engaging step is not uniform, the engaging step of the single crystal can be held by surface contact, and a single crystal falling accident can be avoided, which is desirable. Here, the "engaging member having a self-clamping function" is, as shown in FIG. 1, FIG. 3 or FIG. 6, easily opened if it is pushed upward by the action of the link lever 14 or the clamp lever 15, and If it is pushed down, it will close,
Refers to an engaging member (for example, a clamp claw 13, a link lever 14, a pin 34, or a long hole 35) that sufficiently engages and grips the engaging portion.

Further, in the above-described pulling device, the main pulling means and the sub pulling means may be structured so as to be independently liftable and lowerable by the turning action of the ball screw (see FIG. 8). By adopting such a configuration, it is not necessary to provide a means for preventing the holding mechanism constituted by an equalizer or the like from tilting.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In a single crystal pulling apparatus of the present invention, a seed crystal is brought into contact with a melt surface by a main pulling means, pulled up while rotating, and subjected to a dashes neck treatment. After the engagement step is formed, the shoulder is formed and the single crystal body is pulled up. On the other hand, the weight of the single crystal increases with the progress of pulling, but before reaching the limit of the load that can be borne by the dash neck portion, the process shifts to holding the single crystal by the sub pulling means.

As a specific operation, when the holding mechanism, which has been waiting above, is lowered by the lowering operation of the sub-pulling means, the engaging member provided on the holding mechanism is engaged with a single crystal inverted conical engagement. In a state of being pushed up by the step and being opened, the large diameter portion of the engaging step is passed. When the weight of the single crystal is applied to the engaging member after passing through the large diameter portion of the engaging step, the engaging member exerts a self-clamping function by the action of the link lever or the clamp lever. At this time, the inclination prevention means of the holding mechanism such as an equalizer ensures that the single crystal is firmly held at the engaging step, and that the single crystal to be pulled is not displaced.

When the holding and holding of the single crystal by the holding mechanism is completed, the holding mechanism is raised by synchronizing the pulling speeds of the main pulling means and the sub-pulling means. Further, the drive motor of the main pulling means is of a speed control type, and the drive motor of the sub pulling means is of a tension control type, so that the pulling speed and load sharing of the single crystal can be controlled.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples (Examples 1 to 3) of a single crystal pulling apparatus according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a longitudinal sectional view for explaining an overall configuration example of Embodiment 1 of the present invention. As shown in FIG. 1, a crucible 1 is provided at a central position in a vacuum chamber (not shown), and a melt 2 in which polycrystalline silicon as a raw material is melted is held therein. A seed crystal holder 10 and a holding mechanism 11 are disposed above the crucible 1, and a main pulling means 21 for rotating and pulling up the silicon single crystal 3 and a means for raising and lowering the holding mechanism 11 are further provided above the crucible 1. Sub-raising means 22 are provided, and these constitute a lifting mechanism 20.

In the first embodiment, one main wire 18 wound by the main pulling means 21 and two sub wires 19 wound by the sub pulling means 22 are provided vertically. Is lifted and lowered independently.
The pulling mechanism 20 including the main pulling means 21 and the sub pulling means 22 is rotated in a predetermined direction by a structure (not shown) to rotate the single crystal at a constant speed in the pulling process.

A seed crystal holder 10 is attached to the lower end of the main wire 18, while two sub wires 19 are attached.
The holding mechanism 11 is disposed at the tip of the holding mechanism 11 via an equalizer 16. The equalizer 16 used here functions as a means for preventing the holding mechanism 11 from tilting.

FIG. 2 is a cross-sectional view of the holding mechanism and the equalizer indicated by arrows AA in FIG. Reference numeral 12 in the drawing denotes a holding holder of the holding mechanism. The equalizer 16 is supported by the holding holder 12 via a pin 17 and is vertically suspended by two sub-wires 19. With such a structure, if there is a difference between the winding and unwinding of the two sub-wires 19, the equalizer 16 is tilted, but the holding holder 12 supported by the pins 17 is The tilt is absorbed because it is constantly held horizontally by the action.

FIGS. 3A and 3B are views for explaining the structure of the engaging member provided in the holding mechanism in the first embodiment. FIG. 3A shows the entire structure, and FIGS. 2 shows details of the section. As is apparent from the figure, the engaging member is provided at the lower end of the inner surface of the holding holder 12 and is constituted by two upper and lower link levers 14 for one clamp claw 13. The attachment of the link lever 14 to the holding holder 12 and the attachment of the clamp claw 13 and the link lever 14 need only be rotatably supported.

At least one of the connections between the upper and lower link levers 14 is provided with an elongated hole 34 having a diameter larger than that of the pin 34, as shown in detail A of FIG. 3B. Even if the shape of the engaging step is not uniform, the engaging surface of the clamp claw can be uniquely aligned with the engaging step, so that even a heavy single crystal can be reliably gripped. Further, as shown in FIG. 3 (c), if a large number of teeth-like or wavy protrusions are formed on the engagement surface of the clamp claw, the single crystal can be more reliably gripped. The material of the clamp claw is desirably a high melting point metal such as molybdenum which has excellent high-temperature strength and does not become a contamination source. Further, it is desirable that the contact angle θ between the wavy projection and the engaging step shown in FIG.

By employing the structure shown in FIG. 3 as the engaging member, the weight of the single crystal can be
When a load is applied to the link 13 and the link lever 14, a self-clamping function is exhibited by the action of the link lever, and the engagement step portion of the single crystal can be sufficiently gripped. In addition, the number of engaging members provided on the inner surface circumference of the holding holder 12 must be plural, and it is necessary to provide three or more in order to prevent displacement.

Next, a specific operation procedure will be described. At the start of pulling a single crystal, the sub-pulling means 22 stands by while holding the holding mechanism 11 upward. On the other hand, the seed crystal 9 is attached to the seed crystal holder 10 provided at the tip of the main pulling means 21, and the seed crystal 9 is brought into contact with the center of the liquid surface of the silicon melt 2. Thereafter, the main pulling means 21 is operated to slowly raise the seed crystal 9 while rotating the seed crystal 9, thereby forming a dashes neck (seed drawing portion) 8. Next, the diameter of the single crystal is increased by slowing down the pulling speed of the single crystal to form a large-diameter portion 7, and then the diameter of the single crystal is gradually reduced and narrowed down to the constricted portion 5, and the cross-sectional shape is inverted conical. An engaging step 6 is formed.

After forming the engaging step 6, the shoulder 4 is formed by increasing the diameter of the single crystal again, and thereafter, the pulling speed and the rotation speed are adjusted to the steady conditions to adjust the single crystal body 3 having a predetermined diameter. Move to lifting.

When the weight of the single crystal to be pulled reaches a certain weight after the transition to the steady single crystal pulling, for example,
When the length of the single crystal body 3 becomes 1 m, the holding mechanism 11 waiting above is lowered. In the descending stage, as described above, the clamp claw 13 that contacts the large diameter portion 7 of the single crystal is pushed up and opened to pass through the large diameter portion 7.
Thereafter, the clamp claw 13 is moved to the engagement step 6 by the self-clamp function by the action of the link lever, the pin and the elongated hole.
Is securely engaged and gripped. After that, the sub-lifting means 22
The holding mechanism 11 is synchronized with the pulling speed of the main pulling means 21.
To rise. Here, the holding mechanism 11 is lifted by gripping the single crystal with the clamp claw 13 serving as the engaging member, after the weight of the single crystal reaches a certain weight, that is, at least in the latter half of the pulling process. I just need.

FIG. 4 is a diagram for explaining a control method of the pulling drive motor in the wire type pulling device of the present invention. A holding mechanism that synchronizes the main lifting means 21 and the sub lifting means 22
When raising 11, the main motor 23 of the main pulling means 21 is controlled by speed, and the sub motor 24 of the sub pulling means 22 is
Is desirably tension control.

By employing such a control method of the pulling drive motor, the weight of the single crystal can be shared by the holding mechanism of the sub pulling means as shown in FIG.
Therefore, interference between the control systems of the pulling drive motors can be prevented, the pulling speed and the load ratio between the main motor and the sub motor can be accurately controlled, and stable single crystal pulling without shock can be achieved.

(Embodiment 2) FIG. 6 is a longitudinal sectional view for explaining a configuration example of Embodiment 2 of the present invention. Compared with the first embodiment, the configuration of the crank lever 15 provided as an engaging member in the holding mechanism 11 is different, but the other configurations of the second embodiment are the same as those of the first embodiment.

FIG. 7 is a view for explaining the structure of the engaging member provided in the holding mechanism in the second embodiment. The engaging member is provided at the lower end of the inner surface of the holding holder 12, and the plurality of clamp levers 15 are rotatably supported on the shaft. For this reason, the crank lever 15 can be pivoted upward to a substantially vertical state around a fulcrum provided on the holding holder 12, but once a load is applied downward, the crank lever 15 is clamped by the self-clamp function. The lever 15 can sufficiently engage and grip the engaging step of the single crystal. For this reason, if the engaging member of the second embodiment is used, the clamping mechanism is simple, and the single crystal is clamped at the end face of the clamp lever, so that the length of the tapered portion of the engaging step of the single crystal is relatively small. Can be shorter.

The operation and operating method of the apparatus in the single crystal pulling step, for example, the control method of the pulling drive motor shown in FIG. 4 can be the same as that in the first embodiment.

(Embodiment 3) FIG. 8 is a view for explaining a configuration example of a third embodiment of the apparatus of the present invention. In this configuration, the main pulling means 21 and the sub pulling means 22 include the main ball screw 30 and the sub It is characterized in that it can be moved up and down independently by the turning action of the ball screw 31.

In the configuration of the third embodiment, the main lifting means 21 as the lifting mechanism 20 includes the main lifting base 27 and the sub lifting means
Numeral 22 raises and lowers the sub lifting base 28 respectively. A main ball screw 30 covered with a frame 33 is attached to a main elevating base 27 provided in the main lifting means 21,
It moves up and down by the operation of the main motor 23. Further, the main elevating base 27 supports the seed crystal holder 10 below the main elevating base 27 via the shaft 25. In the pulling process, the single crystal pulled up by the rotation of the crystal rotating motor 32 can be rotated.

On the other hand, the sub-elevating base 28 provided on the sub-elevating means 22 is provided with the sub-ball screw 31 installed on the main elevating base 27, and is elevated by the rotation of the sub-motor 24. A hollow shaft 26 is attached to the sub-elevation base 28 via a bearing 29 in a freely rotatable state, and the holding mechanism 11 is fixed to a tip of the hollow shaft 26. An engaging member is provided at the lower end of the inner surface of the holding holder 12 of the holding mechanism 11, and its structure may be any of those shown in the first and second embodiments.

A third embodiment of the apparatus of the present invention is constituted by passing a shaft 25 attached to a main elevating base 27 through a hollow shaft 26 attached to a sub-elevating base 28. With such a configuration, the main pulling means 21 and the sub pulling means 22 can be easily tuned, and the seed crystal holder 10 and the holding mechanism 11 supported by the fitted shaft 25 and hollow shaft 26 can be easily adjusted. The position adjustment becomes good, and the center position of the single crystal can be matched with the pulling axis.

[0037]

According to the single crystal pulling apparatus of the present invention, it is possible to secure the engagement and gripping at the engaging step provided on the single crystal and to pull a heavy single crystal. However, a single crystal can be safely manufactured without a fall accident.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an example of the overall configuration of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the holding mechanism and the equalizer indicated by arrows AA in FIG.

FIGS. 3A and 3B are diagrams illustrating a structure of an engagement member provided in a holding mechanism according to the first embodiment. FIG.
(c) is a diagram for explaining the details.

FIG. 4 is a diagram illustrating a control method of a lifting drive motor in the lifting device of the present invention.

FIG. 5 is a diagram showing a transition of a load imposed on a holding mechanism in the lifting device of the present invention.

FIG. 6 is a longitudinal sectional view illustrating a configuration example of a device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a structure of an engagement member provided in a holding mechanism according to a second embodiment.

FIG. 8 is a diagram illustrating a configuration example of a third embodiment of the device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Crucible, 2 ... Melt, 3 ... Single crystal body 4 ... Single crystal shoulder, 5 ... Constriction part 6 ... Engagement step part, 7 ... Large diameter part 8 ... Dashes neck (seed drawing part) 9 ... Seed crystal , 10 ... seed crystal holder 11 ... holding mechanism, 12 ... holding holder 13 ... clamp claw, 14 ... link lever 15 ... clamp lever, 16 ... equalizer 17 ... pin, 18 ... main wire, 19 ... sub wire 20 ... pull up Mechanism, 21… Main lifting means 22… Sub lifting means, 23… Main motor 24… Sub motor, 25… Shaft, 26… Hollow shaft 27… Main lifting base, 28… Sub lifting base 29… Bearing, 30… Main Ball screw 31… Sub ball screw 32… Crystal rotation motor 33… Frame, 34… Pin 35… Long hole, 36… Protrusion

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[Procedure amendment]

[Submission date] September 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 3

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

As the engaging member of the above-mentioned holding mechanism, a member having a self-clamp function for canceling the unevenness of the circumferential shape of the engaging step portion by the action of the link lever or the clamp lever is used. Thereby, even if the shape of the engaging step is not uniform, the engaging step of the single crystal can be held by surface contact, and a single crystal falling accident can be avoided, which is desirable. Here, the "engaging member having a self-clamping function" is, as shown in FIG. 1, FIG. 3 or FIG. 6, easily opened if it is pushed upward by the action of the link lever 14 or the clamp lever 15, and If it is pushed down, it will close,
Refers to an engaging member (for example, a clamp claw 13, a link lever 14, a pin 34, and a long hole 35) that sufficiently engages and grips the engaging portion.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

FIG. 2 is a cross-sectional view of the holding mechanism and the equalizer indicated by arrows AA in FIG. Reference numeral 12 in the drawing denotes a holding holder of the holding mechanism. The equalizer 16 is supported by the holding holder 12 via a pin 17 and is vertically suspended by two sub-wires 19. With such a structure, if there is a difference between the winding and unwinding of the two sub-wires 19, the equalizer 16 is tilted, but the holding holder 12 supported by the pins 17 is The tilt is absorbed because it is constantly held in the vertical direction by the action.

Claims (5)

[Claims] 1. A wire-type main pulling means for forming an inverted conical engaging step on a single crystal which is pulled up while being rotated, and gripping the engaging step of the single crystal via an engaging member. A single crystal pulling apparatus including a holding mechanism and a wire-type sub-pulling-up means for raising and lowering the holding mechanism, wherein the sub-pulling-up means raises and lowers the holding mechanism via a tilt preventing means of the holding mechanism, and A single crystal pulling apparatus, wherein the holding mechanism is raised in synchronization with a pulling speed of a main pulling means. 2. A wire-type main pulling means for forming an inverted conical engaging step on a single crystal which is pulled up while being rotated, and gripping the engaging step of the single crystal via an engaging member. A holding mechanism, a single crystal pulling apparatus including a wire-type sub pulling means for raising and lowering the holding mechanism, wherein the main pulling means, one drive motor of the sub pulling means is a speed control system, the other A single crystal pulling apparatus characterized in that the drive motor of (1) is of a tension control type. 3. A wire-type main pulling means for forming an inverted conical engaging step on a single crystal which is pulled up while being rotated, and gripping the engaging step of the single crystal via an engaging member. A holding mechanism, a single crystal pulling device including a wire-type sub pulling means for raising and lowering the holding mechanism, the holding mechanism has a clamp claw, a link lever, a pin or a long hole,
An apparatus for pulling a single crystal, wherein an engaging member matching the shape of an engaging step to be engaged is provided. 4. A single crystal pulling apparatus according to claim 3, wherein a large number of tooth-like or wavy projections are formed on the engagement surface of said clamp claw. 5. The single crystal pulling apparatus according to claim 3, wherein the main pulling means and the sub pulling means can be independently raised and lowered by a turning action of a ball screw.