JP3606037B2 - Raw material additional supply equipment for single crystal pulling equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for additionally supplying a solid raw material into a crucible of a single crystal pulling apparatus using, for example, the Czochralski method.
[0002]
[Prior art]
Conventionally, in a single crystal pulling apparatus using the Czochralski method, after the first single crystal is grown and pulled, a solid raw material in an amount corresponding to the decrease in the melt raw material is additionally supplied into the crucible (hereinafter referred to as recharge). Then, the technique for producing a plurality of single crystal rods from the same crucible by growing and pulling up the next single crystal and pulling it up again and repeating this is known. In the case of a small lump, there is a problem that if the solid raw material is directly put into the melt in the crucible, the melt splashes up and jumps out of the crucible or adheres to the supply pipe.
[0003]
Therefore, for example, as disclosed in JP-A-62-260791, after pulling up the original single crystal, the surface of the melt raw material remaining in the crucible is solidified to some extent, and the solid raw material is fed from the raw material supply pipe toward this solidified surface. In this technology, if the tip of the raw material supply pipe is too far from the solidification surface, the solid raw material will bounce off and jump out of the crucible, Therefore, the operator sets the distance between the tip of the raw material supply pipe and the solidified surface to be constant by visual inspection.
[0004]
[Problems to be solved by the invention]
However, setting the distance by visual inspection increases the number of man-hours for the operator and it is difficult to always set the distance constant. Therefore, the tip of the raw material supply pipe made of a quartz tube or the like is damaged, or the raw material can be supplied smoothly. There are problems such as not being able to do it.
[0005]
Therefore, in the present invention, when the surface of the melt in the crucible is solidified and the solid raw material is additionally supplied, the distance between the solidified surface and the raw material supply pipe can be always set to be constant, and the work manpower of the operator can be reduced. With the goal.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in claim 1, the surface of the polycrystalline melt material melted in the crucible is solidified, and the solid material is supplied from the material supply pipe toward the solidified surface. In the raw material additional supply device of the single crystal pulling apparatus, the solidified surface position detecting means for detecting the position of the solidified surface, the supply pipe position detecting means for detecting the position of the raw material supply pipe, and the raw material from the detection data of these means Control means for moving the supply pipe to control the distance between the solidified surface and the raw material supply pipe to a specified value was provided.
[0007]
That is, the position of the solidified surface of the crucible changes depending on the amount of melt remaining in the crucible, and the raw material supply pipe advances to a position where the tip is close to the solidified surface when supplying the raw material to the crucible. Can be moved forward and backward so that it can be moved back to a position away from the crucible.
Therefore, the position of the solidified surface is detected by the solidified surface position detecting means, the position of the raw material supply pipe is detected by the supply pipe position detecting means, and these detection data are output to the control means, and the control means outputs the detected distance from the specified distance. By obtaining the difference and controlling the movement of the raw material supply pipe so as to correct this difference, the tip of the supply pipe and the solidified surface can always be set at a constant distance, and stable raw material supply can be achieved. Further, the number of man-hours required for the operator to work visually is reduced.
[0008]
In addition, in the case of additionally supplying the solid raw material to the melt raw material, the so-called multi-pooling method (Semiconductor Silicon Crystal Technology, Fumio) in which a plurality of single crystal rods are manufactured from one crucible by repeatedly adding the raw material in a batch system. In addition to the additional supply in Shimura, P178-P189, 1989), it also includes the case of additionally supplying solid raw materials for replenishing the shortage of the melt raw material and adjusting to the desired amount at the initial charge to the crucible .
[0009]
According to a second aspect of the present invention, as the solidified surface position detecting means, an electrical continuity is generated between a hanging tool for holding the seed crystal and a crucible support member for supporting the crucible when the seed crystal is brought into contact with the solidified surface. A conductivity detecting unit for detecting the conductive state and a descent amount measuring unit for measuring the amount of descent from the reference position on the solidified surface to the conductivity detection by the conductivity detecting unit when the seed crystal is lowered are provided.
[0010]
When the seed crystal is lowered in this way, the position of the solidified surface can be detected by measuring the amount of fall of the seed crystal from the reference position to the solidified surface contact. At this time, the contact between the seed crystal and the solidified surface is determined by the conductive state between the hanger and the crucible support member, but a quartz crucible which is an insulator at ordinary temperature is generally used as a material for the crucible.
However, since this quartz crucible becomes conductive when the temperature is higher than 1000 ° C., a conductive state can be created between the hanger and the crucible support member when detecting the solidified surface. Of course, the hanger and the crucible support member are made of a conductive material. For example, a pulse generator that generates the number of pulses corresponding to the number of rotations of a drive motor that moves the seed crystal up and down can be used as the amount-of-fall measurement unit.
[0011]
According to a third aspect of the present invention, the solidified surface position detecting means is also used as a melt surface initial position setting means for setting the initial position of the melt surface as a reference position.
This melt surface initial position setting means has already been adopted in general existing equipment in order to set a constant distance between the diameter control CCD sensor or the like and the melt surface at the initial pulling time when pulling the single crystal. It is a structure, a conduction detection mechanism that detects the contact state between the seed crystal and the melt surface by electrical conduction, a descent amount measurement mechanism that measures the descent amount of the seed crystal from the reference position, or a crucible drive that moves the crucible up and down And a mechanism for measuring the amount of vertical movement of the crucible and the like (see Japanese Patent Publication No. 5-59876).
Therefore, when the solidified surface position detecting means is configured, if a part of the melt surface initial position setting means is used, the existing equipment can be utilized to the maximum, and it can be configured more inexpensively and easily.
[0012]
According to a fourth aspect of the present invention, a drive amount detector for detecting the drive amount of the drive source for advancing and retracting the raw material supply pipe is provided as the supply pipe position detecting means.
If the drive amount of the drive source is detected by this drive amount detection unit, the advance / retreat amount of the raw material supply pipe can be known, and the position of the raw material supply pipe can be detected.
For example, a motor or the like can be applied as such an advance / retreat drive source, and a rotary encoder or the like can be applied as the drive amount detection unit.
[0013]
According to the fifth aspect of the present invention, the supply of the solid raw material by the raw material supply pipe directed on the solidified surface is automated.
That is, for example, when the distance between the solidified surface and the raw material supply pipe is set to a specified value, the raw material supply device and the like are operated by the sequencer of the control means and the supply of the raw material is automatically started. Operator man-hours can be further reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings.
Here, FIG. 1 is a schematic configuration diagram of a raw material supply mechanism section of a raw material additional supply apparatus according to the present invention, FIG. 2 is an explanatory diagram of solidified surface position detecting means according to the present invention, and FIG. 3 is an explanatory diagram showing an example of recharging. is there.
[0015]
The raw material additional supply device of the single crystal pulling apparatus according to the present invention, for example, in producing a single crystal from a polycrystalline melt raw material by the Czochralski method, a plurality of single crystals from a crucible that can only be used once. In the manufacturing method based on the so-called multi-pooling method, after the first single crystal is pulled up, the surface of the melt in the crucible is solidified, and in the form of granules or nuggets in an amount suitable for the reduced melt raw material on the solidified surface It has been proposed as an improved technique for recharging solid materials such as the above.
[0016]
That is, the recharging method will be briefly described. As shown in FIG. 3A, the polycrystalline raw material in the crucible 10 is heated and melted to form a melt 11, and the melt 11 is shown in FIG. A single crystal 13 is grown by bringing the seed crystal 12 into contact and pulling it gently while rotating to produce a first single crystal rod as shown in FIG.
[0017]
Next, since the melt 11 in the crucible 10 decreases as the single crystal 13 is pulled up, recharge for the next single crystal growth is performed.
This recharge is performed by putting a granular or nugget-like solid raw material in an amount suitable for the amount of decrease in the melt into the crucible, and in order to prevent the occurrence of splashes from the melt 11 at this time, (d) As shown, after the solidified surface 11k is formed on the surface of the melt 11 in advance, as shown in (e), the solid raw material 15 is introduced from the raw material supply pipe 14 onto the solidified surface 11k.
[0018]
When the charging of the solid raw material 15 is completed, the solid raw material 15 is melted to obtain a desired amount of melt, and as shown in (f), the growth pulling by the next seed crystal 12 is started toward the melt 11. A similar cycle is repeated.
[0019]
In the recharging method as described above, the raw material additional supply device of the single crystal pulling apparatus according to the present invention accurately sets the distance between the tip of the raw material supply pipe 14 and the solidified surface 11k, and automatically performs this setting. Thus, the operator's work can be reduced. The supply pipe position detecting means 2 configured in the raw material supply mechanism section 1 as shown in FIG. 1 and the solidified surface position detecting means 3 as shown in FIG. And a control means 4 for processing the detection signals sent from the supply pipe position detection means 2 and the solidified surface position detection means 3 to control the movement of the raw material supply pipe 14.
[0020]
The supply pipe position detection means 2 can detect the position of the raw material supply pipe 14, and the solidified surface position detection means 3 can detect the position of the solidified surface 11k.
[0021]
As shown in FIG. 1, the raw material supply mechanism section 1 is configured so that a solid raw material stored in a supply tank 5 can be fed into a conduction pipe 7 through a gate valve 6. The pipe 7 has a diameter larger than that of the pipe 7 and is in communication with the conduction pipe 7, and is movable forward and backward along the outer peripheral surface of the conduction pipe 7 by an advance / retreat mechanism.
[0022]
That is, the advance / retreat mechanism includes a drive motor 8 as an advance / retreat drive source, and a ball screw 18 whose rotation is transmitted from the output shaft of the drive motor 8 via the timing belt 16 and the timing gear 17. The raw material supply pipe 14 is moved forward and backward by the rotation of 18. A rotary encoder 20 as a drive amount detection unit is attached to the output shaft of the drive motor 8 to detect the rotation angle of the drive motor 8 by converting it into an electrical pulse, and this detection data is output to the control means 4. I am doing so.
The drive motor 8 and the rotary encoder 20 constitute the supply pipe position detecting means 2 so that the position of the tip of the raw material supply pipe 14 can be known.
[0023]
On the other hand, as shown in FIG. 2, the solidified surface position detecting means 3 is configured to detect the position of the solidified surface 11k of the melt 11 remaining in the crucible 10, and is made of graphite or the like that holds the crucible 10. The susceptor 21 is supported by a conductive crucible support shaft 22, and the crucible support shaft 22 is supported by a conductive bearing 23.
[0024]
The seed crystal 12 is held by a holder 25 at the lower end of a conductive wire 24 that is a hanging tool, and the upper end of the wire 24 is wound around a drum 27 that is rotatable by driving of a motor 26. It can be moved up and down by the rotation of the drum 27.
[0025]
Electrical connection is established between the base 28 supporting the drum 27 and the seed crystal 12 and between the crucible 10 and the bearing 23, and a resistor 30 is interposed between the base 28 and the bearing 23. Wiring extending from the power source 31 is connected. Further, a comparator 32 serving as a conduction detector for comparing the reference voltage V0 supplied from the power supply 31 and the voltage V generated at the terminal of the resistor 30 when the seed crystal 12 is brought into contact with the solidified surface 11k is provided on this wiring. And the signal of the comparator 32 is sent to the control means 4.
[0026]
Here, the reference voltage V0 supplied to the comparator 32 is set to a value smaller than the generated voltage V, and V0 <V.
That is, by changing various conditions, a number of generated voltages V when the seed crystal 12 and the solidified surface 11k are brought into contact with each other are actually measured, and a reference voltage V0 that always satisfies V0 <V is obtained during the contact. A change in conductivity at the time of contact is detected with reference to V0.
[0027]
A rotating shaft of the drum 27 around which the wire 24 is wound is provided with a pulse generator 33 that generates a pulse in proportion to the amount of rotation of the drum 27 in the forward and reverse directions, and a counter 34 that counts the pulse. The counter 34 receives a detection signal of a reference position detector 35 that detects passage of the seed crystal 12 with an optical sensor or the like while the seed crystal 12 is descending. The output of the counter 34 is sent to the control means 4.
[0028]
In the solidified surface position detecting means 3 configured as described above, the reference position detector 35 detects the passage time of the seed crystal 12 while the seed crystal 12 is being lowered, and the seed crystal 12 comes into contact with the solidified surface 11k from this point. If the distance up to the point in time (detectable by the connection between the base 28 and the bearing 23) is detected by the number of pulses of the pulse generator 33 as the descent amount measuring unit, the distance H from the reference position to the solidified surface 11k is obtained. As a result, the position of the solidified surface 11k can be detected.
[0029]
When the position data of the raw material supply pipe 14 and the position data of the solidified surface 11k are input, the control means 4 performs an arithmetic process so as to obtain a difference (correction amount) from a specified value, and based on the calculated correction amount. The drive motor 8 shown in FIG.
For this reason, the distance between the raw material supply pipe 14 and the solidified surface 11k can always be set constant, and the operator's work can be reduced.
[0030]
By the way, when the distance between the raw material supply pipe 14 and the solidified surface 11k is set to be constant as described above, the control unit 4 controls the gate valve 6 or a raw material measuring feeder (not shown) to automatically supply the solid raw material. It may be started. By such automation, the operator's work process can be further reduced, and productivity can be improved.
[0031]
The solidified surface position detecting means 3 may use existing equipment of a melt surface initial position setting means (not shown). That is, the melt surface initial position setting means adjusts the position of the melt surface when the seed crystal 12 first contacts the melt 11 as shown in Japanese Patent Publication No. 5-59876. This is a mechanism for setting a distance from a monitoring CCD camera or the like for control to be constant, and such a melt surface initial position setting means has already been adopted in a general pulling device. If it is used, it can be configured more inexpensively and easily.
[0032]
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.
For example, in the above-described embodiment, the case of the multi-pooling method in which a plurality of single crystals are pulled out from one crucible is described as an example. However, first, a polycrystalline material is put into a crucible and melted. At this time, the present invention can also be applied at the time of additional supply of solid raw materials such as when a shortage of the melt amount is replenished to a desired amount.
The configuration of the raw material supply mechanism unit 1 is also arbitrary.
[0033]
【The invention's effect】
As described above, the raw material additional supply device of the single crystal pulling apparatus according to the present invention is the solidified surface position detecting means for detecting the position of the solidified surface and the supply pipe for detecting the position of the raw material supply pipe. Since the position detection means is provided and the detection data of each means is input to the control means to control the movement of the raw material supply pipe, the distance between the solidification surface and the tip of the raw material supply pipe is set to a specified value. A constant distance can always be set, and the raw material can be supplied in a stable state. In addition, the operator's work man-hours can be reduced.
According to a second aspect of the present invention, as the solidified surface position detecting means, the determination is made based on the amount of seed crystal lowered when the seed crystal is lowered, and the contact between the seed crystal and the solidified surface is detected by electrical conduction. Then, the position of the solidified surface can be accurately detected.
[0034]
Further, if the solidified surface position detecting means is also used as the melt surface initial position setting means as in the third aspect, the existing equipment can be utilized to the maximum and can be configured more inexpensively and easily.
Further, if the drive amount detection unit for detecting the drive amount of the drive source for advancing and retreating the raw material supply pipe is provided as the supply pipe position detecting means as in claim 4, the position of the raw material supply pipe can be detected accurately.
If the supply of the solid raw material is automated as in claim 5, the number of work steps for the operator can be further reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a raw material supply mechanism section of a raw material additional supply device according to the present invention.
FIG. 2 is an explanatory diagram of solidified surface position detecting means according to the present invention.
FIG. 3 is an explanatory diagram showing an example of recharging.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Raw material supply mechanism part, 2 ... Supply pipe position detection means,
3 ... Solidified surface position detecting means, 4 ... Control means, 5 ... Supply tank,
6 ... Gate valve, 7 ... Conducting tube, 8 ... Drive motor, 10 ... Crucible,
11 ... Melt, 11k ... Solidified surface, 12 ... Seed crystal, 13 ... Single crystal,
14 ... Raw material supply pipe, 15 ... Solid raw material, 16 ... Timing belt,
17 ... Timing gear, 18 ... Ball screw,
20 ... Rotary encoder, 21 ... Susceptor, 22 ... Crucible support shaft,
23 ... Bearing, 24 ... Wire, 25 ... Holder, 26 ... Motor,
27 ... Drum, 28 ... Base, 30 ... Resistor, 31 ... Power supply,
32 ... Comparator 33 ... Pulse generator 34 ... Counter
35: Reference position detector.

Claims (5)

A raw material additional supply device for a single crystal pulling apparatus that solidifies the surface of a polycrystalline melt material melted in a crucible and supplies a solid raw material from a raw material supply pipe toward the solidified surface, Solidification surface position detection means for detecting the position of the solidification surface, supply pipe position detection means for detecting the position of the raw material supply pipe, and movement control of the raw material supply pipe from the detection data of these means to control the solidification surface and the raw material A raw material additional supply apparatus for a single crystal pulling apparatus, comprising control means for setting a distance from a supply pipe to a specified value. 2. The raw material additional supply device for a single crystal pulling apparatus according to claim 1, wherein the solidified surface position detecting means is a crucible support for supporting a crucible and a hanging tool for holding the seed crystal when the seed crystal is brought into contact with the solidified surface. A conductivity detector that detects electrical conduction between the member and a conductive state, and a drop that measures the amount of descent from the reference position on the solidified surface to the conductivity detected by the conductivity detector when the seed crystal is lowered. A raw material additional supply apparatus for a single crystal pulling apparatus, comprising a quantity measuring unit. 3. The raw material additional supply apparatus for a single crystal pulling apparatus according to claim 2, wherein the solidified surface position detecting means is also used as a melt surface initial position setting means for setting the initial position of the melt surface as a reference position. The raw material additional supply apparatus of the single crystal pulling apparatus characterized by the above-mentioned. 4. The raw material additional supply device of the single crystal pulling apparatus according to claim 1, wherein the supply pipe position detection unit detects a driving amount of a forward / backward drive source of the raw material supply pipe. A raw material additional supply apparatus for a single crystal pulling apparatus, comprising a quantity detection unit. 5. The raw material additional supply device of the single crystal pulling apparatus according to claim 1, wherein the supply of the solid raw material through the raw material supply pipe toward the solidified surface is automated. Raw material additional supply equipment for single crystal pulling equipment.

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