JP2004315256A - Method and apparatus for manufacturing single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a single crystal by which the efficiency of additionally filling work of a polycrystalline raw material can be improved in a multi-pooling method, and the weight measurement of a single crystal rod, which have been required due to that the growing single crystal rod is made large in diameter and heavy in weight recently, can easily and inexpensively be automated and mechanized. <P>SOLUTION: The method for manufacturing a single crystal is based on a Czochralski method, at least two single crystal rods are manufactured from one crucible by repeatedly performing at least a process for growing a single crystal rod from a raw material melt accommodated in a crucible, a process for measuring the weight of the grown single crystal rod within a furnace by a weight-detecting means installed in a single crystal manufacturing apparatus, a process for providing the polycrystalline raw material based on the measured weight, a process for taking the grown single crystal rod out of the furnace of the single crystal manufacturing apparatus, a process for additionally filling the provided polycrystalline raw material into the crucible, and a process for melting the polycrystalline raw material additionally filled in the crucible so as to prepare a raw material melt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a single crystal by the Czochralski Method (CZ method), and more particularly, to a method for producing a single crystal capable of increasing the efficiency of an additional filling operation of a polycrystalline raw material in a multi-pooling method. It relates to a manufacturing method. Further, the present invention relates to a single crystal manufacturing apparatus used in such a single crystal manufacturing method.
[0002]
[Prior art]
As a method for obtaining a single crystal from a polycrystalline raw material of a semiconductor such as silicon, germanium, GaP, GaAs, and LnP, the Czochralski method is known. In the Czochralski method, a polycrystalline raw material is melted in a crucible to form a raw material melt, and a single crystal rod is obtained by bringing a single crystal into contact with the raw material melt and slowly pulling it up while rotating. As a method for pulling a seed crystal, there are a method using a shaft and a method using a wire.
[0003]
FIG. 2 shows a general configuration example of a single crystal manufacturing apparatus using a wire.
As shown in this figure, the single crystal manufacturing apparatus includes a main chamber 1 having a crucible accommodating at least a raw material melt, a pulling chamber 2 for taking out a grown single crystal rod, and a chamber for shutting off between the chambers. An isolation valve 3 is provided.
[0004]
In the main chamber 1, a crucible 4, a heating element 5 and a heat insulating material 6 arranged so as to surround the crucible 4 are provided, and a crucible holding shaft 7 for rotating the crucible 4 and a rotating mechanism 8 are provided. is set up. Above the pulling chamber 2, there is a box 9 for accommodating a wire winding mechanism (pulling means) for rotating and winding the wire 10. At the tip of the wire 10 unwound from the wire winding mechanism, a seed crystal 11 is provided. Is locked. The seed holder 12 can reach the raw material melt in the main chamber 1 through the pulling chamber 2 and the isolation valve 3 and is configured to be rotatable up and down.
[0005]
The pulling chamber 2 is configured to be openable for taking out the grown single crystal rod, and to isolate the main chamber 1 from outside air when the pulling chamber 2 is opened, the isolation valve 3 is connected to the pulling chamber 2 and the main chamber 1. And is located between.
[0006]
Next, a method for manufacturing a single crystal by the above-described single crystal manufacturing apparatus will be described.
First, the crucible 4 is filled with a desired high-purity polycrystalline raw material, and heated to a temperature higher than the melting point of the polycrystalline raw material (about 1420 ° C. in the case of silicon) by the heating element 5 to obtain a raw material melt. . Next, by unwinding the wire 10, the tip of the seed crystal 11 is brought into contact with or immersed in the approximate center of the surface of the raw material melt. Thereafter, the crucible holding shaft 7 is rotated in an appropriate direction, the wire 10 is slowly wound up while rotating, and the seed crystal 11 is pulled up, thereby starting the growth of a single crystal rod. Thereafter, a substantially cylindrical single crystal rod can be obtained mainly by appropriately adjusting the pulling speed and the temperature.
[0007]
When the growth of the single crystal rod is completed, the seed holder 12 is raised by a wire winding mechanism (not shown) stored in the upper box 9, and the grown single crystal rod is moved into the pulling chamber 2. When the grown single crystal rod is housed in the pulling chamber 2 together with the seed holder 12, the isolation valve 3 is closed, and the pulling chamber 2 and the main chamber 1 are shut off. After the inside of the pulling chamber 2 is brought to the atmospheric pressure, a door (not shown) for taking out a single crystal rod of the pulling chamber 2 is opened. Then, the grown single crystal rod is taken out of the furnace of the single crystal manufacturing apparatus.
[0008]
Here, a multi-pooling method of manufacturing a plurality of single crystal rods from one crucible by additionally filling a crucible with a polycrystalline material after growing the single crystal rod is known (for example, see Non-Patent Document 1). .). Normally, in this method, when the removal of the grown single crystal rod is completed, first, the single crystal rod is moved to a dedicated weighing machine using a dedicated carriage on which the single crystal rod is placed, and the weight of the single crystal rod is measured. Next, a polycrystalline raw material is prepared based on the measured weight. Next, the prepared polycrystalline raw material is additionally charged into a crucible, and the additionally filled polycrystalline raw material is melted to obtain a raw material melt. Then, the seed crystal 11 is lowered by lowering the seed holder 12 by the wire winding mechanism, and the single crystal rod is grown again.
[0009]
As described above, in the multi-pooling method, the weight measurement of the grown single crystal rod is usually performed after removing the single crystal rod from the furnace of the single crystal manufacturing apparatus. Therefore, after the weight measurement outside the furnace, the weight of the polycrystalline raw material to be additionally charged (recharged) can be determined for the first time. Therefore, it takes a long time to additionally charge the raw material, and a more efficient method has been required.
[0010]
Further, in recent years, as the diameter and weight of the grown single crystal rod have been increased, it has been necessary to increase the size of a dedicated trolley and a weighing scale on which the single crystal rod is mounted. With this increase in size, it becomes difficult to perform weight measurement work manually, so that it has been necessary to promote automation, mechanization, and efficiency of the weight measurement of the single crystal rod.
[0011]
[Non-patent document 1]
Semiconductor Semiconductor SiliconTechnology, Fumi Shimura, p178-179, 1989.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and has made it possible to increase the efficiency of an additional filling operation of a polycrystalline raw material in a multi-pooling method, and to increase the diameter and weight of a grown single crystal rod in recent years. It is an object of the present invention to provide a single crystal manufacturing method that enables simple and inexpensive automation and mechanization of the weight measurement of a single crystal rod, which is required as a result, and a single crystal manufacturing apparatus used for the method.
[0013]
[Means for Solving the Problems]
The present invention has been made in order to solve the above problems, and is a method for producing a single crystal by the Czochralski method, at least, a step of growing a single crystal rod from a raw material melt contained in a crucible Measuring the weight of a single crystal rod grown by a weight detecting means provided in a single crystal manufacturing apparatus in a furnace, preparing a polycrystalline raw material based on the measured weight, and a single crystal manufacturing apparatus. The step of removing the grown single crystal rod from the furnace, the step of additionally filling the prepared polycrystalline raw material in the crucible, and the step of melting the polycrystalline raw material additionally charged in the crucible to obtain a raw material melt, A method for producing a single crystal, comprising producing two or more single crystal rods from a crucible is provided (claim 1).
[0014]
Thus, the weight of the grown single crystal rod is measured in the furnace, a polycrystalline raw material is prepared based on the measured weight, and after the grown single crystal rod is taken out of the furnace, the prepared polycrystalline raw material is removed. By additionally filling the crucible, less time loss is required compared to the case where the weight of a single crystal rod is measured outside the furnace as in the conventional case, and two or more single crystal rods can be efficiently manufactured. be able to. In addition, compared to the case where the weight of a single crystal rod is measured outside the furnace as in the past, there is less equipment that needs to be installed when automating the weight measurement of the single crystal rod and promoting mechanization. It can be simple and cheap. Further, the work load on the operator can be reduced with the efficiency of the additional filling operation and the automation and mechanization of the weight measurement.
[0015]
In this case, in the step of additionally filling the polycrystalline raw material, the surface of the raw material melt remaining in the crucible after growing the single crystal rod in advance is solidified, and the polycrystalline raw material is added on the surface of the solidified raw material melt. It is preferable to fill (claim 2).
[0016]
In this way, the surface of the raw material melt remaining in the crucible after growing the single crystal rod is solidified in advance, and the surface of the solidified raw material melt is additionally filled with the polycrystalline raw material, so that the polycrystalline raw material is crucible. There is no danger that the raw material melt will be scattered from the crucible by the impact when the raw material is put into the furnace and the amount of the raw material melt will be reduced or the inside of the furnace will be contaminated.
[0017]
In this case, in the step of preparing the polycrystalline raw material, a dopant is further prepared, and in the step of additionally filling the polycrystalline raw material, the dopant can be additionally charged together (claim 3).
[0018]
When there is a dopant to be added to the single crystal, as described above, in the step of preparing the polycrystalline raw material, further preparing the dopant, and in the step of additionally filling the polycrystalline raw material, adding the dopant together By filling, work efficiency can be improved.
[0019]
In this case, in the step of measuring the weight of the grown single crystal rod, it is preferable that measurement conditions are the same between two or more single crystal rods to be manufactured (claim 4).
[0020]
In this way, in the step of measuring the weight of the grown single crystal rod, by making the measurement conditions the same between the two or more single crystal rods to be manufactured, the variation in the measured value of the weight between the single crystal rods is reduced. It can be kept small.
[0021]
In this case, it is preferable that the weight detecting means is adjusted under the same conditions as those for measuring the weight of the grown single crystal rod.
[0022]
In this way, by adjusting the weight detecting means under the same conditions as those for measuring the weight of the grown single crystal rod, the grown single crystal rod measured in the furnace with respect to the true value of the weight of the grown single crystal rod The error of the measured value of the weight and the variation of the measured value can be reduced.
[0023]
In this case, in the step of measuring the weight of the grown single crystal rod, the pressure in the furnace of the single crystal manufacturing apparatus is kept constant, and the pulling and rotation of the grown single crystal rod are stopped to measure the weight of the grown single crystal rod. (Claim 6).
[0024]
Thus, in the step of measuring the weight of the grown single crystal rod, the pressure in the furnace of the single crystal production apparatus is kept constant, and the pulling and rotation of the grown single crystal rod are stopped to reduce the weight of the grown single crystal rod. By measuring, the error of the measured value with respect to the true value and the variation of the measured value can be further reduced, and the measurement accuracy can be further improved.
[0025]
In this case, the step of measuring the weight of the grown single crystal rod by the weight detection means is performed after the after-heating after the step of growing the single crystal rod, and the grown single crystal rod is removed from the furnace of the single crystal manufacturing apparatus. It is preferable that the isolation valve be closed before the removal step (claim 7).
[0026]
As described above, the step of measuring the weight of the grown single crystal rod by the weight detecting means is performed after the after-heating after the step of growing the single crystal rod, and the step of measuring the weight of the grown single crystal rod from the furnace of the single crystal manufacturing apparatus. Before closing the isolation valve before the step of taking out, the measurement conditions can be made the same between two or more single crystal rods to be manufactured without adding extra operation and equipment, and The pressure in the furnace of the crystal manufacturing apparatus can be kept constant, and the pulling and rotation of the growing single crystal rod can be stopped. Therefore, it is possible to suppress the error of the measured value from the true value and the variation of the measured value.
[0027]
In this case, the weight detecting means can be a load cell (claim 8).
[0028]
The method for producing a single crystal of the present invention, even if the weight of the single crystal rod is measured in a furnace using the weight detection means as a load cell, it is possible to reduce the error with respect to the true value of the measured value and the variation of the measured value, The weight can be measured with high accuracy, and the weight can be measured very easily.
[0029]
In this case, the single crystal can be silicon (claim 9).
[0030]
In recent years, the production method of the single crystal of the present invention has been increasing in diameter and weight, and the weight of the polycrystalline raw material to be additionally filled has increased, and the automation of the measurement of the weight of the single crystal rod and the mechanization have been strongly demanded. It is particularly effective for producing a silicon single crystal.
[0031]
In this case, the grown single crystal rod can have a diameter of 200 mm or more (claim 10).
[0032]
As described above, even if the grown single crystal rod has a diameter of 200 mm or more, the method for producing a single crystal of the present invention can automatically and mechanically measure the weight of the single crystal rod. Can be greatly reduced.
[0033]
Further, the present invention is a single crystal production apparatus used when producing a single crystal by the Czochralski method, at least a crucible containing a raw material melt, a heating element for heating the raw material melt, and a wire Alternatively, a pulling means for pulling a single crystal from the raw material melt while rotating it by a shaft, a weight detecting means for measuring the weight of the grown single crystal pulled by the wire or the shaft, and a measurement result by the weight detecting means are stored. Storage means, calculating means for calculating the amount of the polycrystalline raw material and / or dopant to be additionally charged into the crucible from the measurement result by the weight detecting means, and a display unit for displaying the result calculated by the calculating means. There is provided a single crystal manufacturing apparatus characterized by comprising (claim 11).
[0034]
By configuring the single crystal manufacturing apparatus in this way, it is possible to measure the weight in the furnace. Therefore, compared with the conventional case where the weight of the single crystal rod is measured outside the furnace, the time loss can be reduced, and two or more single crystal rods can be manufactured efficiently. Further, automation and mechanization of the weight measurement of the single crystal rod for determining the weight of the polycrystalline raw material or the like to be additionally filled can be performed simply and inexpensively. In particular, in recent years, the growing single crystal rod has been increasing in diameter and weight, and the single crystal manufacturing apparatus is effective in reducing the work load on the operator.
[0035]
In this case, it is preferable that the weight detecting means is a load cell.
[0036]
Thus, by using the load cell as the weight detecting means, the configuration can be made simple and inexpensive, and the weight of the single crystal rod can be accurately measured in the furnace of the single crystal manufacturing apparatus.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
The present invention relates to a method for producing a single crystal by the Czochralski method, wherein at least a step of growing a single crystal rod from a raw material melt accommodated in a crucible, and a weight detecting means provided in the single crystal production apparatus Measuring the weight of the single crystal rod grown in the furnace, preparing a polycrystalline raw material based on the measured weight, and taking out the grown single crystal rod from the furnace of the single crystal manufacturing apparatus. Repeating the steps of additionally charging the prepared polycrystalline raw material into a crucible and the step of melting the polycrystalline raw material additionally charged into the crucible into a raw material melt to produce two or more single crystal rods from the crucible. And a method for producing a single crystal characterized by the following.
[0038]
Here, FIG. 3 is a flowchart showing an example of steps of a method for manufacturing a single crystal. FIG. 3A shows a process according to the manufacturing method of the present invention, and FIG. 3B shows a process according to the conventional manufacturing method.
In the conventional method for producing a single crystal, as shown in FIG. 3B, the single crystal rod was grown, after-heated, the isolation valve was closed, and the single crystal rod was removed. The weight of the single crystal rod was measured outside the furnace, a polycrystalline raw material was prepared based on the measured weight, and the crucible was additionally filled with the polycrystalline raw material. On the other hand, in the method for producing a single crystal according to the present invention, as shown in FIG. 3A, a step of growing a single crystal rod, after-heating, closing of an isolation valve, and a step of removing the single crystal rod are performed. After the after-heating and before closing the isolation valve, the weight of the grown single crystal rod is measured in the furnace, and the polycrystalline raw material is added to the crucible immediately after the step of removing the single crystal. This is a flow of preparing a polycrystalline raw material based on the weight measured in the furnace so that it can be filled. Therefore, as compared with the conventional case where the weight of the single crystal rod is measured outside the furnace, the present invention requires less time loss and efficiently manufactures two or more single crystal rods. be able to. Further, since the weight of the single crystal rod is measured in the furnace, there is less equipment required to be installed when the automation of the weight measurement of the single crystal rod and the mechanization are promoted as compared with the conventional method. Further, since the efficiency of the additional filling operation and the automation and mechanization of the weight measurement can be performed, the work load on the operator can be reduced.
[0039]
In the step of additionally filling the polycrystalline raw material, the surface of the raw material melt remaining in the crucible after growing the single crystal rod is solidified in advance, and the polycrystalline raw material is additionally filled on the surface of the solidified raw material melt. Is preferred. In this way, before the step of measuring the weight of the grown single crystal rod in the furnace, the step of preparing the polycrystalline raw material, and the step of removing the grown single crystal rod from the furnace of the single crystal manufacturing apparatus, etc. If the surface of the raw material melt remaining is solidified, the raw material melt scatters from the crucible due to impact when the polycrystalline raw material is charged into the crucible, the amount decreases, or the inside of the furnace is contaminated, Eliminates the risk that the resistivity will deviate from the desired one.
[0040]
Further, when there is a dopant to be added to the single crystal, in the step of preparing the polycrystalline raw material, further preparing a dopant, and in the step of additionally filling the polycrystalline raw material, additionally filling the dopant together In this way, work efficiency can be improved.
[0041]
Here, as a weight detecting means that can be used in the method of the present invention, for example, a load cell can be mentioned.
For the load cell, for example, by automatically determining the amount of melting of the rod-shaped polycrystalline silicon to be additionally charged into the crucible by measuring a change in weight with the load cell, the supply of the rod-shaped raw material can be automatically and accurately performed. A method for melting rod-shaped polycrystalline silicon, which can obtain a raw material melt at a certain level at all times, is disclosed. (See, for example, JP-A-8-301687). In addition, there is disclosed an arrangement in which a plurality of load cells for small loads are arranged to improve the accuracy of weight measurement (for example, see Japanese Patent Application Laid-Open No. Hei 9-175893). Further, a measuring device capable of reducing the load cell capacity by reducing the force applied to the load cell to be smaller than the actual crystal weight, and capable of accurately and smoothly measuring the crystal weight is disclosed (for example, Japanese Patent Application Laid-Open No. H11-157556). See JP-A-2000-344597.).
[0042]
However, when the weight is measured in the furnace of a single crystal manufacturing device using a load cell, errors in the true value of the measured value and variations in the measured value are large depending on the measurement conditions, and accurate weight measurement of the single crystal rod is reliably performed. May not be done. Therefore, in order to surely measure the weight accurately, it is necessary to measure the weight with a weighing scale after removing the single crystal rod from the furnace as in the past.
[0043]
In order to solve this, in the present invention, in the step of measuring the weight of the grown single crystal rod, the measurement conditions are the same between two or more single crystal rods to be manufactured. As a result, the error of the measured value with respect to the true value and the variation of the measured value can be suppressed to some extent.
[0044]
Furthermore, the present inventors investigated the measurement conditions for more accurately measuring the weight in the furnace of the single crystal manufacturing apparatus using the load cell.
FIG. 4 is a graph showing an error with respect to a true value of a measured value and a degree of variation of the measured value when the weight of the grown single crystal rod is measured in a furnace under each measurement condition. The vertical axis indicates (measured value−true value) / true value (%), and the horizontal axis indicates the number of single crystal bars measured. FIG. 4 (a) shows the result of adjusting the load cell under atmospheric pressure and measuring the weight in the furnace while pulling and rotating the single crystal rod. In FIG. 4B, the load cell was adjusted under the atmospheric pressure, but the pulling and rotation of the single crystal rod were stopped, and the weight was measured in the furnace. Further, FIG. 4 (c) shows the load cell adjusted by the furnace pressure at the time of weight measurement, the pulling and rotation of the single crystal rod being stopped, and the weight measured in the furnace.
Here, the true value refers to a value obtained by removing the single crystal rod from the furnace and measuring the weight of the single crystal rod with a weighing scale outside the furnace.
[0045]
As can be seen from FIG. 4 (a), when the load cell is adjusted at atmospheric pressure and the weight is measured in the furnace while pulling and rotating the single crystal rod, errors and variations increase. As can be seen from FIG. 4 (b), the load cell was adjusted at atmospheric pressure. However, when the pulling and rotation of the single crystal rod were stopped and the weight was measured in the furnace, the variation was considerably small. , The error is large. Therefore, it can be seen that it is effective to perform the measurement in a state where the pulling and the rotation of the single crystal are stopped in order to reduce the dispersion of the measured values.
[0046]
Further, as can be seen from FIG. 4 (c), when the load cell is adjusted at the furnace pressure at the time of the weight measurement, the pulling and rotation of the single crystal rod are stopped, and the weight is measured in the furnace, an error and a variation are caused. Can be kept fairly small. Therefore, the error of the measured value to the true value is most affected by the furnace pressure, and it is effective to adjust the load cell with the furnace pressure at the time of measuring the weight of the grown single crystal in order to keep the error small. I understand.
[0047]
From the above, in the present invention, the weight detecting means is adjusted under the same conditions as those for measuring the weight of the grown single crystal rod. Thereby, the error of the measured value of the weight of the grown single crystal rod measured in the furnace and the variation of the measured value with respect to the true value of the weight of the grown single crystal rod can be reliably suppressed.
[0048]
Further, in the step of measuring the weight of the grown single crystal rod, the pressure in the furnace of the single crystal production apparatus is kept constant, and the pulling and rotation of the grown single crystal rod are stopped to measure the weight of the grown single crystal rod. Is preferred. As a result, the error of the measured value with respect to the true value and the variation of the measured value can be further reduced, and the measurement accuracy can be further improved.
[0049]
Further, the step of measuring the weight of the grown single crystal rod by the weight detecting means is performed after after heating after the step of growing the single crystal rod, and the grown single crystal rod is removed from the furnace of the single crystal manufacturing apparatus. By setting the isolation valve before closing before the process, the measurement conditions can be made the same between two or more single crystal rods to be manufactured without adding any extra operation and equipment, and the single crystal is manufactured. The pressure in the furnace of the apparatus can be kept constant, and the pulling and rotation of the grown single crystal rod can be stopped. Therefore, the variation of the measured value of the weight between two or more single crystal rods can be reduced, and the error of the measured value with respect to the true value can be reduced.
[0050]
Further, the workability can be further improved by using systematically acquired data such as data obtained by measuring the weight of a single crystal rod from a single crystal manufacturing apparatus to a server or the like to share the data.
[0051]
In addition, the method for producing a single crystal of the present invention has been increasing in diameter and weight in recent years, and the weight of a polycrystalline raw material to be additionally filled has increased, and the weight measurement of a single crystal rod has been automated and mechanized. Is particularly effective for producing a silicon single crystal which is strongly required.
[0052]
Further, even if the grown single crystal rod has a diameter of 200 mm or more, in the method for producing a single crystal of the present invention, the weight of the single crystal rod can be measured automatically and mechanically. Can be reduced.
[0053]
Further, the present invention is a single crystal production apparatus used when producing a single crystal by the Czochralski method, at least a crucible containing a raw material melt, a heating element for heating the raw material melt, and a wire Or a pulling means for rotating and pulling a single crystal rod from the raw material melt by a shaft, a weight detecting means for measuring the weight of the grown single crystal rod pulled by the wire or the shaft, and a measurement result by the weight detecting means. Storage means for storing, a calculation means for calculating the amount of the polycrystalline raw material and / or dopant to be additionally charged into the crucible from the measurement result by the weight detection means, and a display unit for displaying the result calculated by the calculation means And a single crystal production apparatus characterized by comprising:
[0054]
If a load cell is used as the weight detecting means, it can be configured simply and inexpensively, and the weight of the single crystal rod can be accurately measured in the furnace of the single crystal manufacturing apparatus.
[0055]
The above single crystal manufacturing apparatus will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing one example of the single crystal manufacturing apparatus of the present invention.
In this single crystal manufacturing apparatus, at least a crucible 4 containing a raw material melt and a heating element 5 for heating the raw material melt are provided in a main chamber 1. Further, an isolation valve 3 for shutting off the pulling chamber 2 and the main chamber 1 is provided. Above the pulling chamber 2, there is a box 9. The box 9 is provided with pulling means 14 for pulling a single crystal rod 13 from the raw material melt while rotating the single crystal rod 13 with a wire 10, and a growing unit pulled up from the wire 10. A load cell 15 for measuring the weight of the crystal rod 13 is housed therein. Further, the measurement result of the weight of the single crystal rod by the load cell 15 is sent to the control means. In the control means, the measurement result is stored by the storage means, and the amount of the polycrystalline raw material and / or dopant to be additionally charged into the crucible is obtained from the measurement result by the calculation means. The calculation result is displayed on the display unit.
[0056]
By configuring the single crystal manufacturing apparatus in this manner, automation and mechanization of the weight measurement of the single crystal rod for obtaining the weight of the polycrystalline raw material or the like to be additionally filled can be performed simply and inexpensively. In particular, in recent years, the growing single crystal rod has been increasing in diameter and weight, and the single crystal manufacturing apparatus is effective in reducing the work load on the operator.
[0057]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Example 1)
A silicon single crystal rod having a diameter of 200 mm was grown using the single crystal manufacturing apparatus shown in FIG. The step after growing the single crystal rod was in accordance with the step shown in FIG. That is, after the after-heating after the step of growing the single crystal rod, the whole single crystal rod 13 is arranged so as to be in the pulling chamber 2, and the single crystal rod is loaded by the load cell 15 in the wire winding mechanism 14 of the box 9. Was measured in the furnace. At this time, pulling and rotation of the single crystal were stopped. Thereafter, the isolation valve 3 was closed, and the grown single crystal rod 13 was taken out of the furnace of the single crystal manufacturing apparatus. In parallel with this, the polycrystalline raw material and the dopant are prepared based on the measured weight, and the power applied to the heating element 5 is lowered to reduce the surface of the raw material melt remaining in the crucible. It has been solidified. Therefore, immediately after taking out the grown single crystal, the crucible is additionally charged with the prepared polycrystalline raw material and dopant, and the polycrystalline raw material additionally charged into the crucible is melted to obtain a raw material melt, and the silicon single crystal rod is grown again. Started.
[0058]
The load cell 15 always detects the weight of the silicon single crystal rod. However, the load cell 15 closes the isolation valve 3 under the same conditions as those for measuring the weight of the single crystal rod, that is, after the after-heating. It was adjusted at the previous furnace pressure (55 mbar). The measurement result by the load cell 15 is stored by the storage means, and the measurement result is processed by the calculation means to determine the amounts of the polycrystalline raw material and the dopant to be additionally charged into the crucible. Then, the calculation result was displayed on the display unit.
Since the measured value of the weight of the single crystal measured in this state can be measured with sufficiently high accuracy, the single crystal manufactured by adding the amount of the polycrystalline raw material and the dopant to be additionally charged indicated on the display unit And the quality such as resistivity was also sufficiently satisfied.
[0059]
(Comparative Example 1)
A single-crystal silicon rod having a diameter of 200 mm was grown using an ordinary single-crystal manufacturing apparatus as shown in FIG. However, the step after growing the single crystal rod was in accordance with the step shown in FIG. That is, after taking out the grown single crystal rod, the single crystal rod was moved to a dedicated weighing scale using a special carriage on which the single crystal rod was placed, and the weight of the single crystal rod was measured. Then, a polycrystalline raw material and a dopant were prepared based on the measured weight. Then, the prepared polycrystalline raw material and dopant were additionally charged into a crucible, the additionally filled polycrystalline raw material was melted to obtain a raw material melt, and the growth of a silicon single crystal rod was started again.
In this case, after removing the grown single crystal rod, it took about one hour more time than in Example 1 before starting to additionally fill the crucible with the polycrystalline raw material and the dopant.
[0060]
As can be seen from Example 1 and Comparative Example 1, the production time of the single crystal of the present invention can be shortened as compared with the case where the weight of the grown single crystal is measured outside the furnace, and the measured value can be reduced. Can be sufficiently accurate. In addition, there is no need for a special trolley for mounting a single crystal rod and a special weighing scale, etc., which were necessary when measuring outside the furnace as in the prior art. This is particularly advantageous for measuring a single crystal rod having a large diameter and a large weight.
[0061]
Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention, and any device having the same operation and effect can be realized by the present invention. It is included in the technical scope of the invention.
[0062]
【The invention's effect】
As described above, according to the present invention, by accurately measuring the weight of a single crystal rod in a furnace, time loss can be reduced and the production of two or more single crystal rods can be efficiently performed. Can be performed. In addition, the number of facilities that need to be installed when promoting the automation and mechanization of the weight measurement of a single crystal rod can be reduced, so that the configuration can be simple and inexpensive. Further, the work load on the operator can be reduced with the efficiency of the additional filling operation and the automation and mechanization of the weight measurement.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing one example of a single crystal manufacturing apparatus of the present invention.
FIG. 2 is a schematic cross-sectional view showing one example of a general single crystal manufacturing apparatus.
FIG. 3 is a flowchart illustrating an example of steps of a method for manufacturing a single crystal.
(A) steps according to the production method of the present invention,
(B) Steps related to a conventional manufacturing method.
FIG. 4 is a graph showing an error with respect to a true value of a measured value and a degree of variation of the measured value when a weight of a single crystal rod grown under each measurement condition is measured in a furnace.
(A) Adjust the load cell under atmospheric pressure, measure while pulling and rotating the single crystal rod,
(B) The load cell was adjusted under atmospheric pressure, but the pulling and rotation of the single crystal rod were stopped, and the measurement was performed.
(C) The load cell was adjusted at the furnace pressure at the time of weight measurement, and the pulling and rotation of the single crystal rod were stopped to measure.
[Explanation of symbols]
1 ... main chamber, 2 ... pulling chamber,
3… Isolation valve, 4… Crucible,
5: heating element, 6: heat insulating material, 7: crucible holding shaft, 8: rotating mechanism,
9 ... box, 10 ... wire, 11 ... seed crystal, 12 ... seed holder,
13: single crystal rod, 14: pulling means (wire winding mechanism),
15 ... Load cell.

Claims (12)

A method for producing a single crystal by the Czochralski method, wherein at least a step of growing a single crystal rod from a raw material melt accommodated in a crucible and a method of growing by a weight detecting means provided in a single crystal manufacturing apparatus. Measuring the weight of the single crystal rod in the furnace, preparing a polycrystalline raw material based on the measured weight, removing the grown single crystal rod from the furnace of the single crystal manufacturing apparatus, It is characterized in that two or more single-crystal rods are produced from the crucible by repeating a step of additionally filling a crystal raw material into a crucible and a step of melting a polycrystalline raw material additionally filled in the crucible to obtain a raw material melt. Single crystal production method. In the step of additionally filling the polycrystalline raw material, the surface of the raw material melt remaining in the crucible after growing the single crystal rod is solidified, and the polycrystalline raw material is additionally charged on the surface of the solidified raw material melt. The method for producing a single crystal according to claim 1, wherein: 3. The method according to claim 1, wherein in the step of preparing the polycrystalline raw material, a dopant is further prepared, and in the step of additionally filling the polycrystalline raw material, the dopant is additionally charged together. 4. Single crystal production method. 4. The method according to claim 1, wherein in the step of measuring the weight of the grown single crystal rod, measurement conditions are the same between two or more single crystal rods to be manufactured. 5. Single crystal production method. The method for producing a single crystal according to any one of claims 1 to 4, wherein the weight detecting means is adjusted under the same conditions as those for measuring the weight of the grown single crystal rod. In the step of measuring the weight of the grown single crystal rod, the pressure in the furnace of the single crystal manufacturing apparatus is kept constant, and the pulling and rotation of the grown single crystal rod are stopped to measure the weight of the grown single crystal rod. The method for producing a single crystal according to any one of claims 1 to 5, characterized in that: The step of measuring the weight of the grown single crystal rod by the weight detecting means is performed after the after-heating after the step of growing the single crystal rod, and before the step of removing the grown single crystal rod from the furnace of the single crystal manufacturing apparatus. The method for producing a single crystal according to any one of claims 1 to 6, wherein the method is performed before the isolation valve is closed. The method for producing a single crystal according to claim 1, wherein the weight detecting means is a load cell. The method for producing a single crystal according to claim 1, wherein the single crystal is silicon. The method for producing a single crystal according to any one of claims 1 to 9, wherein the grown single crystal rod has a diameter of 200 mm or more. A single crystal manufacturing apparatus used for manufacturing a single crystal by the Czochralski method, comprising at least a crucible containing a raw material melt, a heating element for heating the raw material melt, and a wire or shaft. Pulling means for pulling while rotating the single crystal rod from, and weight detecting means for measuring the weight of the grown single crystal rod pulled by the wire or shaft, and storage means for storing the measurement result by the weight detecting means, It is characterized by comprising arithmetic means for calculating the amount of the polycrystalline raw material and / or dopant to be additionally charged into the crucible from the measurement result by the weight detecting means, and a display unit for displaying the result calculated by the arithmetic means. Single crystal manufacturing equipment. The single crystal manufacturing apparatus according to claim 11, wherein the weight detecting means is a load cell.

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