JPH11236290A - Raw material addition system for single crystal pulling-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the degree of freedom of operator behavior by performing automatic detection of the solidified state in the raw material addition system for solidifying the surface of a residual melt and then performing addition of the raw material, at the time of additionally supplying a solid raw material into a crucible for single crystal pulling-up. SOLUTION: This system 1 is used for solidifying the surface of a melt 11 to form a solidified surface 11k and then supplying the solid raw material onto the solidified surface 11k, in order to prevent failure due to melt splashes, etc., from being generated, at the time of additionally supplying a solid raw material to a melt 11 in a crucible 10. In the system 1, the solidified state of the solidified surface 11k is detected with a visual sensor 2 such as CCD(charge coupled device) to inform operators of the completion of solidification and concurrently, to automatically start supply of the solid raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material addition system for additionally supplying a solid raw material to a melt raw material in a crucible, for example, in a single crystal pulling apparatus by the Czochralski method.

[0002]

2. Description of the Related Art Conventionally, in a single crystal pulling apparatus based on the Czochralski method, after growing and pulling up the first single crystal, an additional amount of solid raw material corresponding to the reduced amount of melt raw material is additionally supplied into a crucible (hereinafter referred to as a crucible). , Which is called recharge)
The technique of producing a plurality of single crystal rods from the same crucible by growing and pulling up the next single crystal again and repeating this is known. However, when such a solid raw material is granular or small lump, However, when the solid raw material is directly charged into the melt in the crucible, there is a problem that the melt splashes and jumps out of the crucible or adheres to a supply pipe or the like.

Therefore, for example, Japanese Patent Application Laid-Open No. 62-260791
As in No. 2, after the initial single crystal is pulled, the surface of the melt raw material remaining in the crucible is solidified to some extent, and after supplying the solid raw material on this solidified surface, a technique of melting is adopted. In this technique, the solidification state of the surface of the melt is visually monitored by an operator.

[0004]

However, the conventional method of visually monitoring the solidification state by an operator as in the prior art causes breakage of the crucible if the solidification proceeds excessively, and takes time in the subsequent melting stage. To prevent these problems, it is necessary for the operator to continuously monitor from the occurrence of solidification until proper solidification is formed, during which time other operations cannot be performed. , Which hindered productivity improvement.

In view of the above, the present invention provides a raw material addition system capable of reducing the degree of restriction on the action of an operator and improving productivity in solidifying the surface of a raw material melt in a crucible and additionally supplying a solid raw material. The purpose is to provide.

[0006]

In order to achieve the above object, according to the present invention, there is provided a method according to claim 1, wherein a polycrystalline solid raw material is additionally supplied to a polycrystalline melt raw material melted in a crucible to a desired amount. When solidifying the surface of the melt in the crucible and supplying the solid material from above, in the material addition system of the single crystal pulling apparatus, the solidification state of the surface of the melt is detected by a visual sensor. I made it.

That is, when a melt of a material having a tetrahedral structure, such as silicon or a compound semiconductor, becomes solidified, a solidified surface is formed on the surface because the specific gravity of the solidified material is lighter than the melt. As the solidification progresses, a difference in brightness between the surrounding melt and the solidified portion appears, and the solidified portion is regarded as a dark portion. Therefore, the solidification state is determined by a visual sensor that detects, for example, the brightness of white and black. Here, as the visual sensor, a semiconductor image sensor such as a CCD (charge coupled device), a MOS (metal oxide semiconductor), or another TV camera can be applied.

If the solidification state of the melt is detected by a visual sensor and notified to the operator by, for example, a buzzer, it is not necessary for the operator to continuously monitor and the labor is reduced. Therefore, other work can be performed during that time, and the crucible is not damaged due to excessive solidification, and the safety is improved. That is,
The system of the present invention also has a function as an alarm.

In addition, as a case where a solid raw material is additionally supplied to a melt raw material, a so-called multi-pooling method (Semiconductor Silicon Crysta method) for manufacturing a plurality of single crystal rods from one crucible by repeatedly adding a raw material in a batch system.
l Technology, Fumio Shimura, P178-P189,1989) In addition to the additional supply, at the initial charge to the crucible, additional supply of solid raw material for replenishing the shortage of the melt raw material and adjusting it to the desired amount The case is also included.

According to a second aspect of the present invention, the visual sensor is also used as a visual sensor for controlling the diameter of a single crystal. Here, the visual sensor for controlling the diameter of the single crystal outputs imaging data of the crystal growth interface of the single crystal that comes into contact with the melt, and outputs control data such as a single crystal pulling speed which is one means of diameter control. However, it is possible to determine the solidification state of the liquid surface using this visual sensor. At this time, since the diameter control visual sensor is used in the existing single crystal pulling apparatus, the maximum utilization of the existing equipment is achieved.

According to a third aspect of the present invention, the supply of the solid material is automatically started by a solidification detection signal from the visual sensor, and a solidified surface is detected on the surface of the melt in the crucible. After that, all processes are now automated.

As described above, if the supply of the solid raw material is automatically performed based on the detection signal of the solidification state of the visual sensor, the work of the operator can be reduced.
If all processes are automated after the solidified surface is detected on the surface of the melt in the crucible, the labor of the operator can be further reduced and the productivity can be improved.

Here, the processing after the solidified surface is detected includes, for example, control of the start of the supply of the solid raw material, temperature control of the melt, and the like. One example of this temperature control is that the solidified surface is formed. After the raw material supply is started, the temperature is maintained at a constant temperature so that the solidification state does not proceed any further, and when the supply is started, the temperature in the crucible is prevented from dropping and the supplied solid raw material is quickly melted. The control is to increase the temperature so as to obtain the temperature.

[0014]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a system schematic diagram of a raw material addition system of a single crystal pulling apparatus according to the present invention, FIG. 2 is an example of a processing flow after detection of a solidified surface of the present system, and FIG. 3 is a description of a recharging method according to the present invention. FIG.

[0015] In the single crystal pulling apparatus according to the present invention, a raw material addition system for producing a single crystal from a polycrystalline melt raw material by, for example, the Czochralski method uses a plurality of single crystals from a crucible that can be used only once. In the manufacturing method of the so-called multi-pooling method for manufacturing crystals, after the first single crystal is pulled, the surface of the melt in the crucible is solidified, and the amount of granular or It has been proposed as an improved technique for recharging a solid material such as a nugget.

That is, the above-mentioned recharging method will be briefly described. As shown in FIG. 3A, a polycrystalline material in a crucible 10 is heated and melted to form a melt 11.
A single crystal 13 is grown by bringing the seed crystal 12 into contact with the seed crystal 12 as shown in FIG. 1B and pulling it while rotating gently to produce a first single crystal rod as shown in FIG.

Next, since the melt 11 in the crucible 10 decreases as the single crystal 13 is pulled, a recharge for growing the next single crystal is performed. This recharging is carried out by charging a granular or nugget-like solid raw material in an amount corresponding to the reduced amount of the melt into the crucible. As shown,
After forming a solidified surface 11k on the surface of the melt 11 in advance,
As shown in (e), the solid raw material 15 is supplied from the supply pipe 14 onto the solidified surface 11k.

Incidentally, if the solidification of the melt 11 proceeds excessively when the solid raw material 15 is charged, it may cause the crucible 10 to be destroyed, or it may take a long time for the next melting. Temperature control or the like for keeping the temperature constant.

When the input of the solid raw material 15 is completed,
The solid raw material 15 is melted into a desired amount of the melt 11,
As shown in (f), the growth and pulling of the next seed crystal 12 toward the melt 11 is started, and the same cycle is repeated.

In the recharging method as described above, the raw material addition system 1 of the present invention detects the solidification state of the melt 11 with a visual sensor 2 such as a CCD as shown in FIG. 3, the raw material supply device 6 and the heater heating device 7 are controlled via the supply device drive panel 4 and the main body operation panel 5, and the supply of the solid raw material 15 is automatically started. The control of the heating temperature of 11 is performed.

At this time, for example, if the switch of the main body operation panel 5 is set to manual, the control of the heater heating device 7 can be manually operated. 7 is automatically performed. For this reason, the main body operation panel 5 is provided with switches for manual operation. Incidentally, reference numeral 16 in FIG. 1 denotes a front square window provided in the chamber 17.
6, the melt 11 in the crucible 10 can be seen from the visual sensor 2. Reference numeral 18 denotes a susceptor made of carbon or the like that holds the crucible. The susceptor 18, the crucible 10, and the heater 8 are vertically movable by a lifting mechanism (not shown).

Next, an example of semi-automatic processing after the solidified surface is detected will be described with reference to FIG.
First, when the melt is solidified, the position of the crucible 10 (C
P), the position (HP) of the heater 8 is set to a predetermined position, and the heating power of the heater 8 is reduced. Here, the position (CP) of the crucible 10 is calculated based on the remaining amount of the melt 11, and the distance from the visual sensor 2 to the surface of the melt 11 is designed to be constant. The position (HP) of the heater 8 is set to the zero position.

When the temperature of the melt 11 decreases, the melt 1
1 begins to solidify, and the specific gravity of the solid
Therefore, a solidified surface 11k is formed on the melt surface. Then, the black and white lightness detected by the visual sensor 2 becomes dark due to the formation of the solidified surface 11k, and the detected lightness is replaced with, for example, a voltage value by the image processing device 3 and is applied to the sequencer of the supply device driving board 4. Output.

In the sequencer of the supply device drive panel 4, a level value corresponding to a predetermined solidification level is stored in advance.
When the output value output from the image processing device 3 matches the level value, it is considered that the solidification is completed.

When the completion of solidification is detected, the TEMP mode is turned on, and a buzzer sounds almost simultaneously to notify the operator. Here, when the TEMP mode is turned on, the thermostat operates to maintain the current temperature, and the melt 11
Is controlled so that the solidification does not proceed any further and no melting occurs.

Then, when the operator performs a stop operation of the buzzer, the mode is switched from the TEMP mode to the VOLT mode, the thermostat for constant temperature control is cut off, and manual temperature control becomes possible. Therefore, for example, to prevent the temperature of the melt from lowering due to the supply of the solid raw material,
The operator increases the heating power of the heater 8 for the purpose of melting quickly.

On the other hand, the raw material supply device 6 is operated by the drive signal output from the supply device driving panel 4, the supply pipe 14 is set at a predetermined position, and the supply of the solid raw material is automatically started. Such processing eliminates the need for the operator to continuously monitor the solidified surface 11k of the melt 11, thereby reducing labor.

In the example of the processing flow described above, a part of the processing is performed by the operator, but it is also possible to control such processing to be automated. In this case, the work of the operator can be further reduced, and another work can be performed during the recharge.

Incidentally, as the visual sensor 2, a visual sensor for controlling the diameter, which is installed in an existing pulling device, may be used. This visual sensor for diameter control monitors the crystal growth interface of the single crystal 13 in contact with the melt 11 and controls the single crystal pulling speed or heater power based on the imaging data to control the diameter. However, if this existing visual sensor is used, it can be configured at lower cost.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention. For example, in the above embodiment, the multi-pooling method in which a plurality of single crystals are pulled from one crucible has been described as an example, but the polycrystalline raw material is first charged into the crucible and melted. In this case, the present invention can be applied to additional supply of a solid raw material, for example, when a shortage of the melt is replenished to a desired amount. The type of single crystal to be pulled is arbitrary,
Further, the type of the visual sensor, the method of detecting the solidification state, and the like are also arbitrary.

[0031]

As described above, the raw material adding system of the single crystal pulling apparatus according to the present invention solidifies the surface of the melt in the crucible and supplies the solid raw material from above. In the raw material addition system described above, the solidification state of the surface of the melt is detected by the visual sensor, so that it is not necessary for the operator to continuously monitor, and the degree of freedom of the action of the operator can be increased. Further, if the sensor is used as a visual sensor for controlling the diameter of a single crystal as in the second aspect, it is possible to utilize an existing facility to make the configuration cheaper and simpler. According to a third aspect of the present invention, the supply of the solid material is automatically started by a solidification detection signal from the visual sensor, and a solidified surface is detected on the surface of the melt in the crucible as in the fourth aspect. After that, if all processes are automated, the work of the operator can be reduced, and during this time, other work can be performed, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a system schematic diagram of a raw material addition system of a single crystal pulling apparatus according to the present invention.

FIG. 2 is an example of a processing flow after detection of a solidified surface of the present system.

FIGS. 3A to 3F are explanatory diagrams of a recharging method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Raw material addition system, 2 ... Visual sensor, 3 ... Image processing device, 4 ... Supply device drive panel, 5 ... Main body operation panel, 6 ... Raw material supply device, 7 ... Heater heating device, 8 ... Heater, 10 ... Crucible, 11: melt, 11k: solidified surface, 12: seed crystal, 13: single crystal, 14: supply tube, 15: solid raw material, 16: front square window, 17: chamber, 18: susceptor.

Claims (4)

[Claims] When a solid material of a polycrystal is additionally supplied to a melt material of a polycrystal melted in a crucible to obtain a desired amount,
A material addition system of a single crystal pulling apparatus in which the surface of the melt in the crucible is solidified and the solid material is supplied from above, so that the solidification state of the surface of the melt is detected by a visual sensor. A material addition system for a single crystal pulling apparatus, characterized in that: 2. The material adding system for a single crystal pulling apparatus according to claim 1, wherein the visual sensor also serves as a visual sensor for controlling the diameter of the single crystal. . 3. The raw material addition system for a single crystal pulling apparatus according to claim 1, wherein the supply of the solid raw material is automatically started by a solidification state detection signal from the visual sensor. A raw material addition system for a single crystal pulling apparatus characterized by the following. 4. The material addition system for a single crystal pulling apparatus according to claim 1, wherein
A material addition system for a single crystal pulling apparatus, wherein all processes after a solidified surface is detected on the surface of the melt in the crucible are automated.