JP2011126730A - Single crystal pulling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single crystal pulling device detectable of leakage of a melt from a crucible in the single crystal pulling device with high sensitivity and high precision. <P>SOLUTION: The single crystal pulling device for producing a single crystal ingot by Czochralski process includes: a crucible that houses a source melt; a main chamber that houses a heater to heat the source melt; a leaking melt receiving vessel that is disposed at the bottom of the main chamber and houses the melt leaking from the crucible; and a leakage detector that is disposed in the leaking melt receiving vessel and detects leakage of the melt. The leakage detector includes at least two temperature measuring means measuring temperatures at positions of different heights, and a leakage detecting means detecting leakage of the melt according to changes in the measured values of the at least two temperature measuring means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to detection of leaking water in a single crystal pulling apparatus for growing a single crystal rod by the Czochralski method.

For example, an example of a conventional single crystal pulling apparatus using the Czochralski method used for manufacturing a semiconductor silicon single crystal rod will be described with reference to FIG.
As shown in FIG. 7, the single crystal pulling apparatus 101 includes a main chamber 102, a crucible 103 provided in the main chamber 102, a heater 106 disposed around the crucible 103, and a crucible holding device that rotates the crucible 103. A shaft 110 and its rotation mechanism (not shown), a seed chuck 114 for holding a silicon seed crystal 113, a wire 115 for pulling up the seed chuck 114, and a winding mechanism (not shown) for rotating or winding the wire 115. It is prepared for. The crucible 103 is provided with a quartz crucible 103a on the inner side containing the raw material silicon melt (hot water) 105 and a graphite crucible 103b on the outer side. A heater heat insulating material 107 is installed around the outside of the heater 106, and a heat insulating plate 104 is arranged below the crucible 103.

  Next, a single crystal growth method using the single crystal pulling apparatus 101 will be described. First, in a crucible 103, a high-purity polycrystalline raw material of silicon is melted by heating to a melting point (about 1420 ° C.) or higher. And the front-end | tip of the seed crystal 113 is made to contact or immerse in the approximate center part of the hot_water | molten_metal surface by unwinding the wire 115. FIG. Thereafter, the crucible holding shaft 110 is rotated in an appropriate direction, and the wire 115 is wound while being wound, and the seed crystal 113 is pulled up, whereby single crystal growth is started. Thereafter, a substantially cylindrical single crystal 112 can be obtained by appropriately adjusting the pulling rate and temperature.

  The quartz crucible 103a and the graphite crucible 103b in the single crystal pulling apparatus 101 described above both have high heat resistance, but the quartz crucible 103a has a drawback that it is poor in impact resistance. Therefore, when pulling a single crystal into the crucible 103 when pulling the single crystal, the quartz crucible 103a may be cracked by the impact, and the melt 105 may leak from there. In addition, hot water in the crucible 103 may be scattered around the crucible 103 when the polycrystalline raw material is charged. Further, when the quartz crucible 103a gradually deteriorates due to use or the single crystal 112 being pulled falls, the quartz crucible 103a and the graphite crucible 103b may be destroyed and almost the entire amount of hot water may flow out. is there.

  As described above, when the high-temperature melt 105 flows out and scatters out of the crucible 103, it reaches the bottom of the main chamber 102 from around the crucible 103, and a metal such as the bottom of the main chamber 102, the heater terminal or the crucible holding shaft 110. Will erode the parts, crucible drive, lower cooling water piping, and the like. In particular, high-temperature silicon is highly reactive and has a strong erosion action on metals, so that cooling water pipes and the like are easily eroded and there is a risk of steam explosion. Moreover, if it overflows outside the apparatus, an accident or the like may occur due to the overflow.

  Therefore, in the apparatus shown in FIG. 7, a hot water leaking tray 117 having an internal volume capable of containing all the molten raw materials is installed at the bottom of the main chamber 102, and the hot water leaking tray 117 has a change in measured temperature. An induction structure 116 is provided in which a hot water detector 118 for detecting a hot water leak is provided, a hole is formed in the heat insulating plate 104 on the upper portion thereof, and the melt directly reaches the temperature measurement position of the hot water detector 118. (See Patent Document 1).

JP 2009-215126 A

  By using a device equipped with a hot water leak detector and induction structure as described above, it has become possible to detect abnormalities correctly when a large amount of hot water leaks. Therefore, it has been found that since the amount of temperature rise due to the leaked melt is small, erroneous detection is likely to occur. For example, when the hot zone structure (in-furnace structure) is changed, the temperature measured by the hot water detector is greatly different. It was necessary to change the standard. Further, when the heater position is moved at a high speed by setting conditions before seeding or the like, since the measured temperature changes abruptly, an erroneous detection may occur in the determination based on the temperature rise.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a single crystal pulling apparatus that can detect hot water leakage from a crucible in the single crystal pulling apparatus with high sensitivity and high accuracy.

  In order to achieve the above object, the present invention provides at least a crucible for storing a raw material melt, a main chamber for storing a heater for heating the raw material melt, and a leakage from the crucible installed at the bottom of the main chamber. A single crystal pulling apparatus for producing a single crystal ingot by the Czochralski method, comprising a hot water leak tray that contains the molten melt and a hot water leak detector that is disposed in the hot water leak tray and detects a hot water leak. At least, the hot water detector has two or more temperature measuring means for measuring temperatures at different height positions, and a hot water leak detecting means for detecting a hot water leak by a change in measured values of the two or more temperature measuring means. A single crystal pulling apparatus is provided.

  As described above, the hot water detector of the single crystal pulling apparatus detects the hot water leak by detecting two or more temperature measuring means for measuring temperatures at different height positions and the change in the measured values of the two or more temperature measuring means. If there is a leak detection means, the temperature at different heights is measured by two or more temperature measurement means, and the changes in the measured values are compared, so that false detection due to temperature changes caused by factors other than hot water leaks Can be reduced, and a hot water leak can be accurately detected. For this reason, even a slight hot water leak can be detected with high accuracy, and the apparatus can manufacture a single crystal safely and efficiently.

At this time, it is preferable that the hot water leak detecting means detects a hot water leak by a change in a difference between measured values of the two or more temperature measuring means.
Thus, if the hot water detection means detects the hot water leak by a change in the difference between the measured values of two or more temperature measurement means, it becomes an apparatus that can easily perform more accurate hot water detection. .

At this time, the hot water detector has a temperature measuring means for measuring the temperature at least at a height position of −10 to +10 mm of the bottom position of the hot water tray, and +20 mm of the bottom position of the hot water tray and the heater. It is preferable to have temperature measuring means for measuring the temperature at the height position of the lower end position.
As described above, if the temperature measuring means measures the temperature at a height of −10 to +10 mm of the bottom position of the hot water receiving tray, the temperature change due to the leaked melt can be measured with high sensitivity. Since there is little influence on the measurement temperature by the leaked melt, if it is a temperature measurement means that measures the temperature from +20 mm of the bottom position of the saucer to the height position of the lower end position of the heater, it has these two temperature measurement means As a result, it becomes an apparatus capable of detecting a hot water leak with higher sensitivity and higher accuracy.

At this time, it is preferable that an induction structure for guiding the melt leaking from the crucible to one of the measurement positions of the two or more temperature measuring means is provided above the hot water leak detector.
In this way, if a guiding structure that guides the melt leaking from the crucible to any one of the two or more temperature measuring means is provided above the hot water leak detector, a slight hot water leak may occur. However, it will be a device that can perform accurate detection at an early stage.

At this time, the two or more temperature measuring means are preferably thermocouples or radiation thermometers.
Thus, if the two or more temperature measuring means are thermocouples or radiation thermometers, the temperature change can be measured with high sensitivity, and the apparatus can detect leaks more accurately.

  As described above, according to the single crystal pulling apparatus of the present invention, a single crystal can be manufactured with high sensitivity and high accuracy even in slight leaks, and a safe and efficient single crystal can be manufactured. be able to.

It is the schematic which shows an example of the embodiment of the single crystal pulling apparatus of this invention. It is the schematic which shows an example of the temperature measurement means of the hot water leak detector of the single crystal pulling apparatus of this invention. It is the schematic which shows another example of the embodiment of the single crystal pulling apparatus of this invention. It is a graph which shows the change of the measurement temperature of the temperature measurement means by the movement of a heater in a single crystal pulling apparatus. It is a graph which shows the measurement temperature of the temperature measurement means in the raw material melting | fusing in the single crystal pulling apparatus from which a hot zone structure differs. It is a graph which shows the measurement temperature of the temperature measurement means when a hot water leak generate | occur | produces during a single crystal pulling apparatus with a single crystal pulling apparatus. It is the schematic which shows the example of the conventional single crystal pulling apparatus.

Hereinafter, the single crystal pulling apparatus of the present invention will be described in detail as an example of an embodiment with reference to the drawings. However, the present invention is not limited to this.
FIG. 1 is a schematic view showing an example of an embodiment of the single crystal pulling apparatus of the present invention. FIG. 2 is a schematic view showing an example of the temperature measuring means of the leak detector of the single crystal pulling apparatus of the present invention.

  The single crystal pulling apparatus 11 of the present invention shown in FIG. 1 immerses the seed crystal 23 held in the seed chuck 24 in the raw material melt 15 in the crucible 13 by the Czochralski method, and then pulls it up with the wire 25. An apparatus for growing the single crystal 22.

In such a single crystal pulling apparatus 11 of the present invention, a crucible 13 for containing the raw material melt 15 is provided in the main chamber 12, a heater 26 for heating the raw material melt 15, and a crucible for rotating the crucible 13 up and down. The holding shaft 10 and its rotation mechanism (not shown) are provided.
The crucible 13 is provided with a quartz crucible 13a on the inner side containing the raw material melt (hot water) 15 and on the outer side thereof with a graphite crucible 13b for protecting it. A heater 26 is disposed on the outer periphery of the crucible 13, and a heater heat insulating material 19 is disposed around the outer side of the heater 26 to prevent heat from the heater 26 from being directly radiated to the inner wall of the main chamber 12.

  And the hot water leak tray 17 is installed in contact with the inner wall surface at the bottom of the main chamber 12. By fitting the hot water leak receiving tray 17 into the bottom of the main chamber 12, the hot water receiving tray 17 is in close contact with almost the entire inner wall surface of the bottom of the main chamber 12. In addition, a heat insulating plate 14 having a three-layer structure configured such that a molded heat insulating material is sandwiched between, for example, a CIP material (isotropic graphite) can be disposed between the hot water receiving tray 17 and the crucible 13.

In the single crystal pulling apparatus 11 of the present invention as described above, the hot water leak detector 27 for detecting the hot water leak is disposed in the hot water leak tray 17, and the hot water leak detector 27 is at different height positions. It has two or more temperature measuring means 18a and 18b for measuring the temperature, and a hot water leak detecting means 28 for detecting a hot water leak by changing the measured values of the two or more temperature measuring means 18a and 18b.
If it is such an apparatus 11, the temperature measurement means 18a with the lower height position to measure can measure the temperature change by the melt 15 accommodated in the molten metal leak tray 17 with high sensitivity. Further, the temperature measuring means 18b having the higher height position is not affected by the leaked melt 15 accommodated in the hot water receiving tray 17, and the change in the measured temperature is caused by the temperature measuring means 18a. It becomes small compared. On the other hand, changes in the hot zone structure and temperature changes due to the movement of the heater 26 similarly affect the measured temperatures of both the temperature measuring means 18a and 18b. Thereby, if it is this invention, the apparatus which can detect a hot water leak with a relative temperature change, reduces the erroneous detection by other disturbance factors, and can detect with high sensitivity and high accuracy even with a slight water leak. It becomes.

At this time, it is preferable that the hot water leak detecting means 28 detects the hot water leak by a change in the difference between the measured values of the two or more temperature measuring means 18a and 18b.
If it is a change of the difference of a measured value, a relative temperature change can be detected by a simple method, and a hot water leak can be detected with higher accuracy.

As the temperature measuring means 18a and 18b of the present invention, for example, a thermocouple can be used.
In this case, for example, as shown in FIG. 2, a module 20 incorporating a temperature measuring means 18 a that is a thermocouple is inserted from the outside of the bottom of the main chamber 12, and between the side surface of the module 20 and the chamber 12, the temperature The structure is such that vacuum sealing is performed at the outlet of the measuring means (thermocouple) 18a. The temperature measuring means (thermocouple) 18a is covered from above with a protective cap 30 made of stainless steel, and a spring 21 is embedded in the lower portion of the protective cap 30, whereby the upper surface of the protective cap 30 is It can be brought into close contact with the inner surface of the protective cover 29 made of CIP material screwed to the hot water receiving tray 17. The structure of the temperature measuring means 18b for measuring the temperature at a position higher than the bottom surface of the hot water pan 17 is the same, but the temperature measuring means (thermocouple) is extended by extending the protective cap 30 made of stainless steel and the protective cover 29 upward. ) 18b can be extended to a higher position where the temperature is measured.

  The thermocouples that are the temperature measuring means 18a and 18b also have a certain degree of individual difference, and the contact pressure between the protective cap 30 and the protective cover 29 also varies somewhat, so the measured temperatures of both temperature measuring means 18a and 18b There may be a certain amount of misalignment. For this reason, after 5 hours from the start of melting of the raw materials, all the raw materials are still melted, but the detection accuracy can be improved by performing zero correction of the difference value when the inside of the furnace starts to brighten. it can. Although correction is possible even at room temperature, it is desirable to perform correction at as high a temperature as possible. On the other hand, since all the raw materials are melted, the accuracy of detection of hot water leaks is low, so the above timing is preferable.

  The temperature measuring means 18a and 18b are not limited to thermocouples, and radiation thermometers that measure temperature with infrared radiation energy can also be used. In that case, an optical fiber is inserted from the outlet of the module 20 in place of the thermocouple, and the infrared radiation energy emitted from the protective cap 30 is taken into a radiation thermometer installed outside the furnace, thereby enabling temperature measurement.

In addition, as shown in FIG. 2, the temperature detector 18 a for measuring the temperature at a height position of −10 to +10 mm of the bottom surface position of the water leak receiving tray 17, and the bottom position of the water leak receiving tray 17. It is preferable to have temperature measuring means 18b that measures temperature at a height position of +20 mm to the lower end position of the heater. For example, in the case of FIG. 2, the temperature measuring means 18 a measures the temperature at a height position of −7 mm from the bottom surface position of the hot water leak tray 17, and the temperature measuring means 18 b is the position of the bottom surface position of the hot water leak tray 17. The temperature is measured at a height of +43 mm.
If the temperature measuring means 18a measures the temperature at a height of −10 to +10 mm of the bottom surface position of the hot water receiving tray 17, the temperature change caused by the melt 15 that has leaked can be measured with higher sensitivity. If the temperature measuring means 18b measures the temperature from +20 mm of the bottom surface position of the tray to the height position of the lower end position of the heater, the influence of the leaked melt 15 on the measured temperature is not so great. Differences in measurement temperature change occur more clearly. Therefore, it is possible to detect the hot water leak immediately and with high accuracy by the difference between the measured values. At this time, in the case of a single crystal pulling apparatus capable of changing the heater position, the heater position is moved by setting the upper limit of the temperature measuring means 18b as the lower end position of the movable range of the heater. Even so, the influence of the heater can be reliably prevented.

In addition, a guiding structure 16 for guiding the melt 15 leaking from the crucible 13 to one of the measurement positions of the two or more temperature measuring means 18a and 18b is provided above the hot water leak detector 27. Is preferred. As the guiding structure 16, for example, as shown in FIG. 1, weirs 31 having a height of about 10 mm are provided at the inner peripheral end and the outer peripheral end of the heat insulating plate 14 above the hot water leak detector 27, and the melt 15 leaked. Is accumulated on the heat insulating plate 14 so as to fall and be accommodated in the hot water receiving tray 17 through the through hole directly above the temperature measuring means 18a, so that the melt 15 that has fallen is stored in the temperature measuring means 18a. A guiding structure 16 can be provided that guides to reach directly.
By providing such a guiding structure 16, when a hot water leak occurs, the leaked melt 15 quickly reaches the temperature measuring means 18a, so that the hot water leak can be detected with higher sensitivity. When there are two temperature measuring means 18a and 18b as shown in FIG. 1, if the leaked melt is guided only to the temperature measuring means 18a that measures the temperature at a low position, the temperature with the temperature measuring means 18b is reduced. Since the difference in change becomes clearer, the detection of the hot water leak becomes more accurate.

  According to the single crystal pulling apparatus of the present invention as described above, even in the case of manufacturing a single crystal, even a slight leak of water can be detected with high sensitivity, and safe and efficient single crystal manufacturing can be performed.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Example)
The single crystal pulling apparatus 11 of the present invention as shown in FIGS. 1 and 2 was used to melt the polycrystalline silicon raw material.
Further, melting was performed using the single crystal pulling apparatus 11 ′ shown in FIG. 3 having the same basic structure as that of the single crystal pulling apparatus 11 shown in FIG. 1, but having a different hot zone structure. As shown in FIG. 3, the heater heat insulating material 19 ′ of the single crystal pulling apparatus 11 ′ is structured to cover the heater 26. In this case, since the hot zone is different under the same power condition as that of the single crystal pulling apparatus 11 of FIG. 1, the melting time is shortened. Therefore, in the melting of the single crystal pulling apparatus 11 ′ of FIG. The power was made smaller than that of the single crystal pulling apparatus 11 in FIG.

FIG. 5 shows the temperature measured by the temperature measuring means 18a and 18b when the raw materials are melted using these apparatuses. The measured temperature in the single crystal pulling apparatus 11 of FIG. 1 is shown as a hot zone 1, and the measured temperature in the single crystal pulling apparatus 11 ′ of FIG.
As shown in FIG. 5, since the power is set lower in the hot zone 2, the temperature measured by the temperature measuring means 18a, 18b is also lower. When detecting the occurrence of hot water leak at an absolute temperature using one temperature measuring means as in the conventional method, there is a difference of 100 ° C. or more depending on the hot zone structure as shown in FIG. It is impossible to detect. On the other hand, according to the present invention, even if the hot zones are different, the difference in temperature measured by the temperature measuring means 18a and the temperature measuring means 18b is within 30 ° C. in any hot zone.

Next, FIG. 4 shows the relationship between the measured temperature and the heater position when the position of the heater 26 is intentionally moved up and down after the melting of the single crystal pulling apparatus 11 in FIG.
As shown in FIG. 4, just by lowering the heater 26 by 100 mm, the measured temperature immediately rises by about 150.degree. After several minutes, the same temperature drop is observed when the heater position is returned to the original position. Although the temperature measuring means 18b with different height positions to be measured added in the present invention shows the same behavior, the difference from the temperature measuring means 18a is about 20 to 30 ° C. It can be seen that even if a temperature change occurs, if the method of detecting the hot water leak is based on the difference between the two, it is not necessary to perform a false detection that causes the heater movement to be a hot water leak.

Next, FIG. 6 shows the measured temperature when hot water leaks during straight body growth using the single crystal pulling apparatus 11 of FIG.
The measured temperature during the straight body growth is stable, but a temperature rise is observed due to the occurrence of hot water leakage. The leaked melt falls to the vicinity of the temperature measuring means 18a by the heat insulating plate 14 having the guiding structure 16 and releases heat around it, so that the measured temperature of the temperature measuring means 18a is rapidly increased. On the other hand, the temperature measured by the temperature measuring means 18b tends to increase due to the radiant heat generated by the melt accumulated in the hot water receiving tray 17, but not as high as the temperature measuring means 18a.

  In the conventional method, an alarm is output when the measured temperature exceeds a certain temperature reference and when a certain temperature rise rate is detected. However, the hot zone structure is changed or the heater is moved. There were many cases of false detection. In the present invention, as shown in FIG. 6, the value obtained by subtracting the measured temperature of the temperature measuring means 18b from the measured temperature of the temperature measuring means 18a has a clear change as shown in FIG. By making an alarm output when a certain reference value is exceeded, it is possible to detect a hot water leak with high accuracy. Of course, the determination of leakage of water can be made not only by the difference between the measured values, but also by taking the difference in the rate of change between the two measured values or the ratio.

  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.

10 ... crucible holding shaft 11, 11 '... single crystal pulling device,
12 ... main chamber, 13 ... crucible, 13a ... quartz crucible,
13b ... graphite crucible, 14 ... heat insulating plate, 15 ... melt, 16 ... induction structure,
17 ... Hot water leak tray, 18a, 18b ... Temperature measuring means,
19, 19 '... heater insulation, 20 ... module, 21 ... spring,
22 ... single crystal, 23 ... seed crystal, 24 ... seed chuck, 25 ... wire,
26 ... heater, 27 ... hot water leak detector, 28 ... hot water leak detection means,
29 ... Protective cover, 30 ... Protective cap, 31 ... Weir.

Claims (5)

At least a crucible for storing the raw material melt, a main chamber for storing a heater for heating the raw material melt, a hot water receiving tray for storing the melt that is installed at the bottom of the main chamber and leaks from the crucible, A single crystal pulling apparatus for producing a single crystal ingot by the Czochralski method, comprising a hot water leak detector disposed on the hot water tray and detecting a hot water leak, comprising:
The hot water leak detector has two or more temperature measuring means for measuring temperatures at different height positions, and a hot water leak detecting means for detecting a hot water leak by a change in measured values of the two or more temperature measuring means. A single crystal pulling apparatus characterized by   2. The single crystal pulling apparatus according to claim 1, wherein the hot water leak detecting means detects a hot water leak by a change in a difference between measured values of the two or more temperature measuring means.   The temperature detector for measuring the temperature at least at a height position of −10 to +10 mm of the bottom position of the molten metal tray, and +20 mm of the bottom position of the molten metal tray to the lower end position of the heater. The single crystal pulling apparatus according to claim 1, further comprising a temperature measuring unit that measures temperature at a height position of the single crystal.   The induction structure for guiding the melt leaking from the crucible to any one of the two or more temperature measuring means is provided above the hot water detector. The single crystal pulling apparatus according to any one of claims 1 to 3. The single crystal pulling apparatus according to any one of claims 1 to 4, wherein the two or more temperature measuring means are a thermocouple or a radiation thermometer.

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