JP4068711B2 - Single crystal manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single crystal manufacturing apparatus which is used for manufacturing a semiconductor single crystal by a CZ method and is particularly suitable for pulling a large weight single crystal.
[0002]
[Prior art]
Single crystal silicon is generally manufactured using the CZ method. In the CZ method, polycrystalline silicon is filled in a quartz crucible installed in a single crystal manufacturing apparatus, and the polycrystalline silicon is heated and melted by a heater provided around the quartz crucible to obtain a melt. Then, the seed crystal attached to the seed holder is immersed in the melt, and the seed holder is pulled up while rotating the seed holder and the quartz crucible in the same direction or in the opposite direction to grow single crystal silicon to a predetermined diameter and length. .
[0003]
In the seed crystal, dislocation occurs due to thermal shock when immersed in the melt. In order to remove this dislocation, a neck portion having a diameter of about 3 to 4 mm is formed below the seed crystal by using the dash neck method, and the dislocation is released to the surface of the neck portion. Then, after confirmation of dislocation-freeness, the shoulder portion is formed to enlarge the single crystal to a predetermined diameter, and then the process shifts to the formation of the straight body portion.
[0004]
In recent years, as the diameter of a single crystal is increased or the length in the axial direction is increased for the purpose of improving the efficiency of production of semiconductor devices and improving yield, the strength of the neck portion is approaching its limit. Therefore, in the conventional crystal pulling method, there is a possibility that the neck portion is broken, and safe single crystal growth cannot be performed. As a countermeasure, an apparatus and a method for transferring the load from the neck portion to the holder during single crystal growth have been proposed. According to such an apparatus and method, since most of the weight of the single crystal is supported by the holder, the neck portion is prevented from being broken, and even when the neck portion is broken, the holder can prevent the single crystal from falling. .
[0005]
Among the various single crystal pulling devices using the single crystal holder described above, the crystal pulling device disclosed in Japanese Patent Publication No. 7-103000 hangs a plurality of gripping levers with wires, and pulls the gripping levers by raising and lowering the wires. It has a structure that opens and closes to hold the constricted portion of the single crystal. Further, as the grip lever is closed, the slide ring is lowered by its own weight to prevent the grip lever from opening. On the other hand, in the single crystal pulling apparatus disclosed in JP-A-5-270975, when the lifting ring provided above the seed holder pushes up the upper hook, the lower hook closes and holds the single crystal in conjunction with this. It has a structure.
[0006]
[Problems to be solved by the invention]
However, the single crystal pulling apparatus has the following problems.
(1) In the crystal pulling apparatus according to Japanese Patent Publication No. 7-103000, since the seed holder also serves as a holder positioning function, the holder cannot arbitrarily select a position in the furnace, and follows the seed holder. Then you have to go up and down. Therefore, when the seed crystal is immersed in the melt, the lower end of the grip lever is close to the melt and is exposed to high temperatures, which may cause malfunction due to seizure of the grip lever and the slide ring, and the growing single crystal. There is a risk of contamination. Moreover, if the dimension from the lower end of the seed holder to the constricted portion deviates from the target value, a predetermined holding operation cannot be performed. Furthermore, when the holding operation is started, the slide ring is lowered, and therefore it is impossible to open the grip lever again in the furnace. Therefore, when the single crystal is dislocated during the growth, the single crystal cannot be removed from the holder and re-dissolved, and there is no countermeasure other than taking it out of the furnace.
(2) The single crystal pulling apparatus according to Japanese Patent Laid-Open No. 5-270975 relies on the tension of the spring to close the lower hook. For this reason, when the elevating ring pushes up the upper hook, the lower hook is instantaneously moved to the final position, and the growing single crystal may be dislocated due to the vibration generated at this time. Further, like the crystal pulling apparatus according to Japanese Patent Publication No. 7-103000, the lower hook moved to the holding position cannot be opened in the furnace.
[0007]
The present invention has been made paying attention to the above-mentioned conventional problems, and the single crystal being grown by vibration due to the nail closing operation of the holder is not exposed to a high temperature when the holder holding the constricted portion formed in the single crystal is exposed to high temperature. It is an object of the present invention to provide a single crystal production apparatus provided with a single crystal holder that can open a closed nail as necessary without causing a dislocation.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a single crystal manufacturing apparatus according to the present invention includes a single crystal holding apparatus for pulling up a single crystal while holding a constricted portion formed in the single crystal. A plurality of first wire units for raising and lowering the holder body; and a plurality of second wire units for opening and closing a plurality of claws attached to the holder body in a swingable manner. After the constricted portion is held by the crystal holder, it functions as a crystal pulling shaft.
According to the above configuration, since the holder body of the single crystal holder that holds the constricted portion formed in the single crystal is raised and lowered by the plurality of first wire units, the single crystal holder can be independent regardless of the raising and lowering of the seed holder. Can be raised and lowered. Therefore, the single crystal holder can be kept at a high position away from the melt surface until the constricted portion is formed in the single crystal and the straight body portion grows to a predetermined length. Further, by operating a plurality of second wire units, the claws of the single crystal holder can be opened and closed at any time, and the claws can be freely engaged with the constricted portions. After the constricted portion is held by the single crystal holder, the single wire is continuously grown by winding the second wire unit at a predetermined speed.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the single crystal manufacturing apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view schematically showing a single crystal manufacturing apparatus according to a first embodiment of the present invention. This single crystal manufacturing apparatus includes a vacuum vessel 1 above a pull chamber (not shown), and in the vacuum vessel 1, a crystal pulling wire winding device 2, a plurality of wire winding devices 11 for raising and lowering a single crystal holder 10, and A wire take-up device 12 is installed. A seed holder 5 having a seed crystal 4 attached thereto is connected to the lower end of the crystal pulling wire 3 hanging from the crystal pulling wire winding device 2 to the center of the furnace body, and a crucible 7 for storing the melt 6 is not shown. It is installed in the main chamber so that it can rotate and move up and down.
[0010]
The single crystal holder 10 includes a holder main body 13 made of a ring-shaped plate, a plurality of links 15 having one ends rotatably attached to a plurality of support members 14 protruding from the lower surface of the holder main body 13, A claw 16 attached to the other end of each link 15 is provided. The nail | claw 16 is manufactured so that an inner side part, ie, the outer side part, may become heavier than a rocking | fluctuation center. The holder body 13 is supported by a plurality of first wire units 17 that hang from the wire take-up device 11, and a plurality of second wire units 18 that hang from the wire take-up device 12 on the upper surface of the outer portion of the claw 16. The lower end of is connected.
[0011]
The operation of the single crystal holder 10 of the first embodiment is as follows.
The crystal pulling wire 3 is rewound in the same manner as in the normal single crystal pulling, the seed crystal 4 mounted on the seed holder 5 is immersed in the melt 6 and then the neck portion 8 is wound by winding the crystal pulling wire 3. Is formed. Further, after forming the enlarged diameter portion 9a and the constricted portion 9b of the single crystal 9, the process proceeds to the formation of the shoulder portion 9c and the straight body portion 9d. During this time, the single crystal holder 10 is supported on the upper part of the main chamber by the first wire unit 17 and is rotating in the same direction at the same rotational speed as the crystal pulling wire 3. Since the second wire unit 18 is loosened, the outer part of the claw 16 is lowered and the inner part is kept open as shown in FIG. Therefore, the enlarged diameter portion 9a can pass without touching the inner tip of the claw 16.
[0012]
When the growing single crystal 9 is grown to a preset length, the wire winding device 11 and the wire winding device 12 are driven to unwind the first wire unit 17 and the second wire unit 18, The crystal holder 10 is lowered. After the inner tip of the claw 16 passes through the enlarged diameter portion 9a, the driving of the wire winding device 11 is stopped, the wire winding device 12 is driven to the winding side, and the second wire unit 18 is wound. As a result, the outer end of the claw 16 is pulled up, and the other end of the link 15, that is, the connecting portion with the claw 16 is displaced upward. As shown in FIG. It is pushed out and the nail is closed. The claw 16 is fixed at a position where the upper surface of the outer portion is in contact with the lower surface of the support member 14, and when the second wire unit 18 is further wound, the entire single crystal holder 10 is raised. The first wire unit 17 and the second wire unit 18 are wound up at a speed higher than that of the crystal pulling wire 3, and the inner tip of the closed claw 16 contacts the lower conical surface of the enlarged diameter portion 9a to hold the single crystal 9. To do. After holding the single crystal 9 with the single crystal holder 10, the first wire unit 17 and the second wire unit 18 are wound up at the same ascending speed as the crystal pulling wire 3.
[0013]
After holding the single crystal 9 by the single crystal holder 10, the majority of the weight of the single crystal 9 is held by the second wire unit 18, and the single crystal 9 is grown while holding a part by the crystal pulling wire 3. continue. The load burden ratio between the two is arbitrarily determined.
[0014]
FIG. 3 is a schematic diagram for explaining a single crystal holder in the single crystal manufacturing apparatus according to the second embodiment of the present invention, in which the left side of the center line shows a state where the nail is opened, and the right side shows a state where the single crystal is closed by closing the nail. The held state is shown. The single crystal holder 20 is swingably attached to a holder body 21 made of a ring-shaped plate, a plurality of support members 22 and stoppers 23 protruding from the lower surface of the holder body 21, and the support member 22. And a plurality of claws 24. As in the case of the first embodiment, the holder main body 21 is supported by a first wire unit 17 suspended from a plurality of wire winding devices (not shown) installed in the vacuum vessel 1. The lower end of the second wire unit 18 that hangs down from the plurality of wire winding devices is connected to the upper surface of the intermediate portion between the swing center and the tip of the claw 24.
[0015]
Next, the operation of the single crystal holder 20 of the second embodiment will be described.
As in the case of the first embodiment, the enlarged diameter portion 9a, the constricted portion 9b, the shoulder portion 9c, and a part of the straight body portion 9d are formed following the neck portion 8. The single crystal holder 20 is supported on the upper part of the main chamber by the first wire unit 17 and rotates in the same direction at the same rotational speed as the crystal pulling wire 3. Since the 2nd wire unit 18 is loosened, the front-end | tip of the nail | claw 24 turns downward and does not contact this when the enlarged diameter part 9a passes.
[0016]
When the growing single crystal 9 is grown to a preset length, the first wire unit 17 and the second wire unit 18 are rewound, and the single crystal holder 20 is lowered. After the tip of the claw 24 passes through the enlarged diameter portion 9a, the unwinding of the first wire unit 17 and the second wire unit 18 is stopped, and the second wire unit 18 is wound up. As a result, the tip of the claw 24 is pulled inward, and after the side surface of the claw 24 comes into contact with the stopper 23, the entire single crystal holder 20 is raised. As a result, the tip of the closed claw 24 abuts on the lower conical surface of the enlarged diameter portion 9 a to hold the single crystal 9. Thereafter, since the first wire unit 17 and the second wire unit 18 are wound up at the same speed as the crystal pulling wire 3, the single crystal 9 is pulled up by the single crystal holder 20. Most of the weight of the single crystal 9 is held by the single crystal holder 20.
[0017]
In the first and second embodiments, the crystal pulling wire winding device 2 and the wire winding device 12 are placed on a load sensor, and the crystal pulling wire winding device 2 is based on the detected load value. If the driving torque of the wire winding device 12 is controlled, the load distribution between the crystal pulling wire 3 and the single crystal holder 10 (or the single crystal holder 20) can be controlled to a desired ratio.
[0018]
In the first and second embodiments, the wire type single crystal manufacturing apparatus has been described. However, the present invention is also applicable to a shaft type single crystal manufacturing apparatus.
[0019]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
(1) Since the single crystal holder can be freely moved to an arbitrary position in the furnace, it is possible to select an optimal holding timing in consideration of the temperature and weight of the growing single crystal and No exposure to high temperatures.
(2) The claw closing operation of the single crystal holder and the pulling operation after holding the single crystal are performed by the same lifting mechanism, and a dedicated wire winding device is installed, so these series of operations are performed reliably. can do. Further, vibration due to the claw closing operation does not occur, and there is no possibility that the single crystal being grown is dislocated.
(3) Even after holding the single crystal with the single crystal holder, it is possible to open the closed nail, so if the single crystal held with the single crystal holder is dislocated, put it in the crucible. It is easy to return, open the nail and redissolve.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a single crystal manufacturing apparatus according to a first embodiment of the present invention, showing a state in which a nail of a single crystal holder is open.
2 is a schematic diagram showing a state where a single crystal is held by the single crystal holder of FIG. 1. FIG.
FIG. 3 is a schematic view showing an open / close state of a nail in the single crystal holder of the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Crystal pulling wire winding apparatus 3 Crystal pulling wire 9 Single crystal 9a Expanding part 9b Narrow part 10 and 20 Single crystal holders 11 and 12 Wire winding apparatuses 13 and 21 Holder main body 15 Link 16, 24 Claw 17 First wire unit 18 Second wire unit

Claims (1)

In the single crystal manufacturing apparatus provided with the single crystal holder (10) that pulls up the single crystal (9) while holding the constricted portion (9b),
A plurality of first wire units (17) for moving up and down the holder body (13) of the single crystal holder (10);
A plurality of second wire units (18) for opening and closing a plurality of claws (16) pivotably attached to the holder body (13);
The single crystal holder (10) changes the direction of the nails (16 ) to hold the constricted part (9b) ,
The second wire unit (18) functions as a crystal pulling shaft after the constricted portion (9b) is held by the single crystal holder (10).

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