JPH10182288A - Receiving tray made of carbon for apparatus for pulling silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve safety over the entire part of a pulling up apparatus and to produce a large-diameter silicon single crystal by forming a film consisting of pyrolytic carbon on the inner side surface of a receiving tray made of carbon to prevent infiltration of a received silicon melt into the inside of a base material, thereby making it possible to prevent the occurrence of cracks and failures and preventing the failure and destruction over the entire part of the apparatus as well by the silicon melt. SOLUTION: The apparatus 100 for pulling up the silicon single crystal is constituted by rotatably housing and supporting a crucible 10 for melting the silicon into its hermetic body 50 by a revolving shaft, arranging a heater 12 for heating at the circumference of this crucible 10, arranging a heat insulating cylinder 30 made of, for example, graphite, on the outer side thereof and housing a thermal insulating material 40 between this cylinder and the hermetic body 50. The crucible 10 consists of double structures composed of a quartz crucible 11 in direct contact with the silicon melt and a graphite crucible 11a. The side plate of the receiving tray 20 made of carbon exists right under the heat insulating cylinder 30. The graphite base material is put into a CVD furnace and gaseous methane with H2 as a carrier is supplied into the furnace, by which the pyrolytic carbon film is formed on the front surface of the graphite base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for constructing a silicon single crystal pulling apparatus, and more particularly to a carbon tray suitable for use in a silicon single crystal pulling apparatus which is increased in size.

[0002]

2. Description of the Related Art A silicon single crystal pulling apparatus pulls a silicon single crystal from a silicon melt in a crucible in the presence of an atmospheric gas by a so-called Czochralski method. 57-15079
Is known as a “single crystal manufacturing apparatus” as disclosed in Japanese Patent Application Publication No. As shown in FIG. 6, the apparatus disclosed in this publication is configured such that “a rotary shaft 2 is introduced into a furnace body 1 from below, and a crucible 4 is mounted on an end surface of the rotary shaft 2 via a mounting table 3. Further, a heating element 5 and a heat retaining cylinder 6 are arranged around the crucible 4, so that the silicon is melted in the crucible 4 to obtain a melt 7. On the other hand, the furnace 7 is vertically arranged above the furnace body container 1. A sliding shaft 9 is provided for sliding movement, and a silicon seed crystal 8 is attached to the free end of the rotating shaft 9 so that the rotating shaft 9 is positioned above the state where the seed crystal 8 is in contact with the melt 7 in the crucible 4. Move it,
A silicon single crystal 10 that follows the seed crystal 8 is obtained. When growing a single crystal, unnecessary reaction product gas is generated in the single crystal 10.
It is necessary to eliminate this so that no reaction occurs on the liquid surface of the melt 7. For this purpose, an inert gas such as argon is supplied as an atmospheric gas to the single crystal and the liquid level from above the furnace body container 1 and discharged from the lower part of the furnace body container ”(column 2 of the above-mentioned publication). ).

[0003] The furnace body container 1 also forms a cooling layer, and the cooling layer allows the entire furnace body container 1 to be cooled. A member denoted by reference numeral 5 in FIG. 6 is a heater, and a heat insulating material is disposed between the heater and the furnace body container 1, for example, as shown in FIG.

Incidentally, the silicon single crystal manufactured by the silicon single crystal pulling apparatus described above is used as a material for forming a semiconductor element.
2. Description of the Related Art Along with high integration and high speed required for a semiconductor element, a silicon wafer manufactured from a silicon single crystal has been desired to have a large diameter. That is, as the diameter of the current silicon wafer, there are various sizes when the diameter is 100 mm or less, but 100 mm or 125 m when the diameter is 100 mm or more.
Four types of sizes, m, 150 mm, and 200 mm, are standards used internationally. And recently, the standardization of 300 mm or more is being advanced.

If the diameter of the silicon wafer is increased, the diameter of the silicon single crystal to be pulled by the silicon single crystal pulling apparatus must be naturally increased, and the silicon single crystal pulling apparatus and its constituent parts also become large. I have to change. In addition, in order to take full advantage of the large diameter silicon single crystal, the development of silicon single crystal manufacturing technology without cost increase has been desired, and safety during manufacturing has also been ensured. It is becoming important.

To increase the diameter of a silicon single crystal, FIG.
Various problems such as the development of the crucible 4 itself shown in the above, the solution of the problem caused by the convection of the molten silicon in the crucible 4, the temperature control in the silicon single crystal pulling apparatus, and the setting of the pulling conditions are solved. There must be.
Above all, what is urgently solved technically is a problem caused by a “dash neck” formed between a seed crystal for forming a silicon single crystal and a shoulder of the silicon single crystal.

Here, the basics of silicon single crystal growth when a silicon single crystal is manufactured by the silicon single crystal pulling apparatus shown in FIGS. 6 and 1 will be considered with reference to FIG. The outline is as follows. The raw material polycrystalline silicon is put into a crucible, melted at about 1500 ° C. in a silicon single crystal pulling apparatus, and held for a while. The temperature was gradually lowered so that the surface temperature of the melt became about 1420 ° C., and as shown in FIG.
A seed crystal of １２12 mm is immersed in a silicon melt to melt the surface of the seed crystal. By gradually pulling up the seed crystal while rotating, a dash neck having a diameter of about 2 to 4 mm and a length of about 50 to 100 mm is formed as shown in FIG. Then, the temperature of the melt surface was lowered slightly, and the
As shown in (c), a shoulder of silicon single crystal is formed. By adjusting the melt temperature and the pulling speed, a straight body having a diameter of about 101% of the required diameter of the silicon wafer is formed. When the straight body reaches a predetermined length, the temperature of the melt is slightly increased, and the pulling speed is also increased to make the lower end of the silicon single crystal thinner. When the silicon single crystal is cut off from the melt, heating is stopped. .

It is particularly important during the above steps. This is because, in this step, dislocations and processing defects that cause dislocations in the completed silicon single crystal must be removed. The dash neck is formed in this important step, and the dash neck is formed for the above-described reason, and thus has a very small diameter of 2 to 4 mm.

On the other hand, in order to manufacture a silicon single crystal for forming a silicon wafer having a diameter of 200 mm, in view of the actual condition in which about 100 kilograms of polycrystalline metal silicon as a material is used, for example, silicon having a diameter of 300 mm is used. To make a silicon single crystal for a wafer, about 3
It is believed that 00 kilograms of material are used. In addition, since the amount remaining in the crucible after pulling up the silicon single crystal is generally considered to be 20 to 25%, the weight of the silicon single crystal to be pulled up through the dash neck is 225 in the case of 300 mm. ~ 240
It is expected to be in kilograms.

[0010] That is, a very thin dash neck having a diameter of 2 to 4 mm corresponds to a maximum of 24 mm in the case of 300 mm.
It must support a weight of 0 kilograms, and should never give an impact such as vibration to the dash neck during the pulling of the silicon single crystal. 3mm or 4m diameter made of silicon
The dash neck of m has a tensile strength of 144 or 256 Kgf / cm ² , respectively, which means that it is very fragile.

Even if the entire silicon single crystal pulling apparatus is improved so that the dash neck is hard to break, for example, if a natural disaster such as an earthquake occurs, the dash neck will break during the pulling even if the degree is small. That could be enough. When the dash neck breaks, the silicon single crystal that was in the process of being pulled falls into the melt of the crucible, and the silicon melt melts as if the watermelon was suddenly placed in a bucket filled with water. It will scatter in the lifting device. Such accidents have already occurred, and various reports have been made.

For this reason, conventionally, as shown in FIGS. 1 and 2, a carbon saucer is arranged at the bottom of a silicon single crystal pulling apparatus to receive a silicon melt flowing down from a crucible or the like, and This is to protect the hermetically sealed body that covers the outer peripheral portion of the single crystal pulling apparatus.

However, as described above, when manufacturing a silicon single crystal for forming a large-diameter silicon wafer, a large amount of silicon melt must be formed in a crucible, so that a dash neck is formed. If the silicon single crystal falls into the silicon melt due to breakage of the silicon melt, a large amount of the silicon melt flows down from the crucible to the carbon tray. For this reason, the amount of the silicon melt that the carbon pan needs to receive also increases, and the carbon pan must receive an object having extremely large latent heat. In other words, the conventional carbon pan, which produced a small-diameter silicon single crystal, received a silicon melt having a latent heat less than its own heat capacity, so there was no significant problem. With the increase in diameter of silicon single crystals, carbon trays are forced to receive a silicon melt having latent heat exceeding its heat capacity.

As a result, the silicon melt received by the carbon pan may not be solidified in the carbon pan, and may penetrate into the base material of the carbon pan. It is anticipated that the entire carbon saucer may be damaged in the first place. Here, if there is silicon melt remaining without solidifying in the carbon pan, it flows further into the silicon single crystal pulling device due to damage of the carbon pan, and breaks down the partition wall of the cooling layer to cool down. It is quite possible that a water vapor explosion could occur.

The above is due to the broken dash neck.
There has been a problem that the silicon single crystal falls into the crucible melt and the silicon melt flows down from the crucible. However, there are other causes that the silicon melt flows down from the crucible. That is, in this type of silicon single crystal pulling apparatus,
A crucible for forming and storing the silicon melt is also an important component, but the crucible itself may be damaged, and the silicon melt in the crucible may flow down to the carbon tray.

As shown in FIG. 1, the crucible used in this type of silicon single crystal pulling apparatus is a quartz crucible on the side directly in contact with the silicon melt, and the outside of the quartz crucible is a graphite crucible. By surrounding, the quartz crucible is protected. If a crucible having such a configuration is used for a long period of time, the quartz crucible or graphite crucible may be worn out, causing cracks or cracks, or even broken in some cases.

A graphite crucible that is divided into two or three parts is mainly used. For example, if the quartz crucible is broken first, the silicon melt contained therein is removed from the divided surface of the graphite crucible. If the graphite crucible is broken down first, it will soften under high temperature and cannot support the quartz crucible containing the heavy silicon melt. It will flow down. If the sink made of carbon cannot receive the silicon melt that has flowed down sufficiently and reliably, the same problem as in the case of breakage of the dash neck occurs, and the solution is urgent.

Further, as the diameter of the silicon single crystal increases, the size of the entire silicon single crystal pulling apparatus must be increased. However, a carbon tray placed at the bottom of the silicon single crystal pulling apparatus is required. However, what has to be made large is as described above. Since the carbon tray is housed in a silicon single crystal pulling apparatus that is in a high temperature atmosphere and receives the silicon melt that has flowed down, it must have sufficient heat resistance. It must be made of carbon. And, in order to form a large-diameter saucer with a carbon material such as graphite, it is natural that a technology corresponding thereto must also be developed.

On the other hand, in this type of silicon single crystal pulling apparatus, whether the inside of the furnace body (sealed main body) can be sufficiently filled with an atmosphere containing only inert gas, that is, whether the airtightness in the furnace is sufficiently maintained or not. In order to check the condition, the gas in the furnace is evacuated by a vacuum pump, and the operation of the vacuum pump is temporarily stopped to see the situation.

However, when the vacuum pump was operated, the degree of vacuum reached a predetermined level. However, when the vacuum pump was stopped, the degree of vacuum was reduced and the airtightness was judged to be insufficient.
In some cases, the pulling device cannot be started, and in that case, it is necessary to recheck the airtightness of each part such as the closed body. This re-inspection is a work that requires a long time, but after the re-inspection, the aforementioned degree of vacuum was again reduced.

The present inventors also examined where the cause of the decrease in the degree of vacuum was, and found that the gas in the base material constituting the carbon saucer was shifted in time according to the degree of vacuum. It was found out that the cause was that it was coming out of the sealed body while producing the air. That is, since the graphite base material is a so-called porous material having a large number of pores, the gas in the pores is gradually discharged into the sealed main body having a predetermined degree of vacuum, which lowers the degree of vacuum. It was one of the causes. This phenomenon is, as the diameter of the silicon single crystal increases, the larger the carbon pan, the larger the volume of pores it has,
It is expected to be noticeable.

When a film is formed on the surface of the substrate, the above phenomenon is expected to be more remarkable. That is, when a film is not formed, the gas in the pores of the base material is exhausted from the entire surface, but when a film is formed on the surface, the gas is present on the surface of the film. It is discharged little by little through cracks and the like. In addition, it has been found that the occurrence of cracks on the surface of the coating film is greatly affected by the coefficient of thermal expansion of the substrate.

Therefore, the present inventors have proposed a technique for increasing the diameter of a silicon single crystal in accordance with the increase in the diameter of a silicon wafer, while increasing the size of the silicon single crystal pulling apparatus using existing technology, and further increasing the size of the silicon single crystal. Recognizing that improving the safety of the crystal pulling apparatus is a prerequisite, the inventors of the present invention have conducted various studies on where and how to improve the crystal, and as a result, have completed the present invention.

[0024]

SUMMARY OF THE INVENTION The present invention has been made as a result of the above studies, and the problem to be solved is that even if a large amount of silicon melt is received, it may be damaged or destroyed. There is no carbon saucer.

That is, first, the object of the invention according to claim 1 is to prevent the received silicon melt from penetrating into the base material and to prevent cracks and breakage from occurring. Of course, damage and destruction of the entire device due to the silicon melt can be prevented, and the entire silicon single crystal pulling device can be made safe. As a result, a large-diameter silicon single crystal can be manufactured. It is an object of the present invention to provide a carbon saucer that can be adapted to be applied to a silicon single crystal pulling apparatus for the same.

The object of the invention according to claim 2 is to not only achieve the object of claim 1 but also to have no adverse effect when checking the degree of vacuum in the silicon single crystal pulling apparatus. Another object of the present invention is to provide a carbon tray that can prevent cracks from being generated in a coating made of pyrolytic carbon formed on the surface of a base material.

The object of the invention according to claim 3 is to achieve not only the object of the invention according to claim 1 but also a reduction in thickness and weight of the whole, It is an object of the present invention to provide a carbon tray that can be safely installed and replaced for the silicon single crystal pulling apparatus.

The object of the invention according to claim 4 is to achieve the object of the invention according to claims 1 to 3, and to make the carbon material easy to manufacture even if it is enlarged. It is to provide a saucer.

[0029]

Means for Solving the Problems In order to solve the above problems, first, means according to the first aspect of the present invention will be described with reference numerals used in the following description of embodiments. "A carbon tray 20 that is disposed on the bottom surface of the silicon single crystal pulling apparatus 100 and receives molten silicon flowing down from above, and has a coating 22 made of pyrolytic carbon formed on at least the inner surface thereof. This is a carbon tray 20 for the silicon single crystal pulling apparatus 100.

That is, as shown in FIG. 1 or FIG. 2, the carbon tray 20 according to the first aspect is disposed so as to cover substantially the entire bottom surface of the sealed main body 50 constituting the silicon single crystal pulling apparatus 100. As shown in (b) of FIG. 3, (b) of FIG. 4, or (a) of (a) of FIG. 5, it is of a tarai shape capable of receiving a large amount of silicon melt. Further, the carbon tray 2 according to claim 1 is provided.
The carbon substrate 21 constituting 0 is formed of carbon literally such as graphite or C / C composite.

As shown in FIG. 4 or FIG. 5, the carbon tray 20 shown in FIG. 1 has, at the center thereof, a shaft insertion hole 21c through which the rotating shaft 55 passes, and the shaft insertion hole 2c.
An exhaust port 25 is provided near 1c. On the other hand, the carbon tray 20 shown in FIG. 2 schematically showing the positional relationship between the carbon tray 20 and the heater 12 and the like in the sealed main body 50 is, as shown in FIG. It has an insertion hole 21c, and is intended for the silicon single crystal pulling apparatus 100 in which degassing in the sealed main body 50 is performed from around the carbon tray 20.

The carbon tray 20 of claim 1
As shown in (b) and (c) of FIG. 3, (b) of FIG. 4, or (a) of FIG. 5, a film 22 made of pyrolytic carbon is formed on at least the inner surface thereof. It is. Of course, the coating 22 made of the pyrolytic carbon may be formed on the outer surface or the bottom surface of the carbon tray 20 and may be applied. The coating 22 made of pyrolytic carbon can block SiO gas and Si vapor scattered around the carbon pan 20 and completely prevent the carbon substrate 21 of the carbon pan 20 from being silicified. Can be made of carbon saucer 2
Cracking to zero is prevented, and durability is also improved.

According to the carbon tray 20 constructed as described above, even if the silicon melt flows down from the crucible 10, it can naturally be sufficiently received, and a large amount of the silicon melt flows down. Therefore, even if the latent heat is large, the silicon melt does not penetrate into the carbon substrate 21. The reason is that the coating 22 made of pyrolytic carbon formed on the inner surface of the carbon tray 20 blocks direct contact of the silicon melt with the carbon substrate 21 due to the gas impermeability of Pyrex glass. It is. From the above, in the carbon tray 20, the silicon melt does not penetrate into the carbon base material 21, and the generation and cracking of the carbon base material 21 are completely prevented. This completely prevents the carbon substrate 21 from being silicified.

Therefore, even if a large amount of the silicon melt flows down from the crucible 10 with the increase in the diameter of the silicon single crystal, the carbon tray 20 and the entire silicon single crystal pulling apparatus 100 are prevented from being broken. In particular, steam explosion due to water in the cooling layer in the closed body 50 is completely prevented. For this reason, the carbon tray 20 can improve the safety of the silicon single crystal pulling apparatus 100 which has been increased in size as the diameter of the silicon single crystal has increased.

In order to solve the above-mentioned problem, a means adopted by the invention according to claim 2 is that the carbon substrate 21 of the carbon tray 20 according to claim 1 is described as “average coefficient of thermal expansion from room temperature to 1000 ° C. Is 3.5 to 6.0 × 10 ⁻⁶ / ° C.
And a porosity according to the test method of JIS R7212 of 10% to 30%. "

That is, according to the carbon tray 20 according to the second aspect, since the carbon substrate 21 is made of graphite as described above, the inside of the silicon single crystal pulling apparatus 100 in which the carbon tray 20 is installed is provided. When the gas in the silicon single crystal pulling apparatus 100 is discharged to the outside by a vacuum pump to check the degree of vacuum, the gas that has permeated into the pores of the graphite base material 21 has a pressure within the sealed main body 50. It is discharged to the outside of the sealed main body 50 substantially simultaneously following the lowering. Therefore, even if the vacuum pump is stopped at the final stage of the vacuum degree check, gas does not flow out of the graphite base 21 of the carbon tray 20 into the closed main body 50. The airtightness is sufficiently maintained.

In this case, the base material 21 serving as the carbon pan 20
Has an average thermal expansion coefficient from room temperature to 1000 ° C. of 3.
It needs to be 5 to 6.0 × 10 ⁻⁶ / ° C. The reason is that if the average thermal expansion coefficient of the substrate 21 is out of the above range, the coating 22 made of pyrolytic carbon frequently peels off from the surface of the substrate 21 due to the repetition of heating and cooling. This is because cracks occur. Within the above range, there is no mismatch between the thermal expansion coefficient of the coating 22 of the pyrolytic carbon formed on the surface and the substrate 21, and generation of cracks on the surface of the coating 22 is prevented. The average coefficient of thermal expansion from room temperature to 1000 ° C. is 20 ° C. to 10 ° C.
This corresponds to a value obtained by adding a correction value of 1.32 × 10 ⁻⁶ / ° C. to the coefficient of thermal expansion of 0 ° C.

Further, the carbon tray 2 according to claim 2 is provided.
In the case of 0, the porosity of the substrate 21 according to the test method of JISR7212 must be made of a graphite material having a porosity of 10% to 30%. The reason is that when the porosity becomes 10% or less, the discharge of gas suddenly takes a long time,
It cannot be performed within a predetermined time. Also, if the porosity is 30% or more, the strength of the carbon tray 20 itself will suddenly decrease, and it will not be able to withstand vibrations in the furnace and heating and cooling cycles sufficiently.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the carbon base 21 of the carbon tray 20 according to the first aspect is formed of a C / C composite. It is.

The C / C composite constituting the base material 21 of the carbon tray 20 is high in strength and excellent in thermal shock resistance despite its light weight. Even if the diameter of the tray 20 is increased, the weight of the tray 20 is extremely reduced, high in strength, and excellent in thermal shock resistance.

Therefore, the carbon tray 2 according to claim 3 is provided.
0 means that the whole can be made thinner and lighter, and the installation and replacement work can be performed safely for the large silicon single crystal pulling apparatus 100.

Of course, also in the carbon pan 20 of the third aspect, since the coating 22 made of pyrolytic carbon is formed on at least the inner surface, the same effect as the carbon pan 20 of the first aspect is exhibited. Things.

In order to solve the above-mentioned problem, the means adopted by the invention according to claim 4 is that the carbon tray 20 according to claims 1 to 3 is referred to as “a base material to be the carbon tray 20”. 21 is constituted by graphite parts 21a to 21d, and these graphite parts 21a to 21d are formed.
d is bonded and integrated with a resin that is baked and carbonized. ”

That is, in the carbon tray 20 according to the fourth aspect, in order to increase the size of the silicon single crystal as the diameter of the silicon single crystal increases, the carbon tray 20 is formed into graphite parts such as the side frame parts 21a and the bottom plate parts 21b. It is formed separately.
That is, this kind of carbon saucer 20 can be formed by cutting out a lump of graphite material and forming it as an integral body as shown in FIG. 3, for example. As shown in (a) above, necessary graphite parts are formed of graphite material or the above-mentioned C / C composite, and these joints are bonded together with a resin to form an integral body. As a result, the production of this type of carbon tray 20 is facilitated, and the yield is increased.

The resin to which each graphite part is adhered is one that is completely carbonized or graphitized by firing the entire carbon tray 20 and has the same quality as each graphite part. As a result, as shown in FIG. 5B, the carbonized or graphitized adhesive layer 23 is formed. Therefore, the carbon pan 2 shown in FIGS.
In FIG. 0, each graphite part and the adhesive layer 23 are shown to exist independently of each other, but in fact, they are completely integrated as a graphite pan 20 made of graphite. It is.

Therefore, according to the carbon saucer 20 of the fourth aspect, the objects of the first to third aspects of the invention can be achieved, and the manufacturing thereof can be easily performed even if the size is increased. It is becoming.

[0047]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a first embodiment of a carbon tray according to the present invention; But,
4 and 5 show a carbon tray 20 according to the fourth aspect. 1 and 2 are a vertical sectional view and a partially cutaway perspective view of a silicon single crystal pulling apparatus 100 to which the carbon tray 20 according to each invention is applied.
Before describing each carbon tray 20, a schematic configuration of the silicon single crystal pulling apparatus 100 will be described as follows.

That is, the silicon single crystal pulling apparatus 100 is for manufacturing a silicon single crystal corresponding to the silicon wafer in order to manufacture a silicon wafer having a large diameter of about 300 mm or more. The carbon tray 20 according to the present invention housed and arranged at the bottom of the main body 50 needs to have a diameter of about 1000 to 1300 mm and a height of about 100 to 200 mm.

This silicon single crystal pulling apparatus 100
As shown in FIG. 1, a crucible 10 for melting silicon is rotatably housed and supported by a rotation shaft 55 in a sealed main body 50, and the crucible 10 is provided around the crucible 10. A heater 12 for heating is provided. Outside the heater 12, there is disposed a heat retaining cylinder 30 formed of, for example, graphite, and a heat insulating material 40 is accommodated between the heat retaining cylinder 30 and the sealed main body 50.

As shown in FIG. 1, the portion of the crucible 10 which is in direct contact with the silicon melt is a quartz crucible 11, and the outside of the quartz crucible 11 is, for example, a graphite crucible 11a.
It has a double structure wrapped around it.
Of course, these quartz crucibles 11 and graphite crucibles 11a
Is for a 300 mm silicon single crystal,
It has a capacity that can accommodate 300 kg or more of polycrystalline metal silicon.

Of course, the crucible 10 can be moved up and down by a device (not shown). The reason is that the silicon melt in the crucible 10 is lowered in its surface by the lifting, and the position of the heater 12 is not changed. This is because the liquid level of the silicon melt, which must maintain a proper molten state, must always be kept substantially constant.

As shown in FIG. 2, the heater 12 arranged outside the quartz crucible 11 as described above is cut into a tube made of conductive graphite alternately up and down, thereby forming a zigzag shape. In this case, a conductive path is formed. As described above, the heat retaining cylinder 30 made of a heat-resistant material such as graphite or C / C composite is disposed outside the heater 12. In the present embodiment, as shown in FIG. 1, the side plate of the carbon tray 20 according to the present invention is located immediately below the heat retaining cylinder 30.

The heat retaining cylinder 30 and the heater 12 described above are
Since the crucible 10 must be disposed at a fixed position with respect to the crucible 10 to be rotated, and an inert gas such as an argon gas must flow around the crucible 10, various members as shown in FIG. Is adopted.

That is, first, the heater 12 includes a conductive shaft 58 fixed on an electrode 54 provided on the bottom surface of the closed body 50,
And a terminal 57 thereon supports the power supply while enabling external power supply. And this heater 1
Since an inert gas passage as shown by the arrow in FIG.
An upper ring 51 is attached to an upper end of the heat retaining cylinder 30. Of course, if the heat inside the sealed main body 50 is released to the outside, the silicon single crystal pulling apparatus 100 becomes inefficient, so that the space between the heat retaining cylinder 30 and the sealed main body 50 is naturally changed to other parts. As many heat insulating materials 40 as possible are arranged inside the closed main body 50. This sealed body 50
Keeps the inside airtight and, as also shown in FIG.
It has a cooling layer made of water or the like inside.

The carbon pan 20 according to the present invention is placed on the bottom of the sealed main body 50 via a heat insulating material 40. The carbon pan 20 and the exhaust gas formed on the heat insulating material 40 are provided. During the operation of the silicon single crystal pulling apparatus 100, the gas inside the apparatus is exhausted through the opening. The supply of the inert gas into the sealed main body 50 is performed via a gas rectifying member 56 mounted on the upper part of the sealed main body 50. In addition, since it is sufficient to cover the periphery of the heater 20, the heat retaining cylinder 30 itself is partitioned by the lower ring 52 as shown in FIG.
The lower part of the lower ring 52 is a separate member.

The above silicon single crystal pulling apparatus 100
Of the members constituting the above, those directly exposed to Si vapor or SiO gas may be configured and implemented like the carbon tray 20 according to the present invention. For example, as for the upper ring 51, it is also disposed near the heater 12 and is heated, and is also exposed to a high-temperature SiO gas. Graphite or C similar to the base material of the tray 20
In addition to the formation of the / C composite, a pyrolytic carbon film may be formed on, for example, an inner lower surface of the substrate. The same applies to the lower ring 52, the terminal 57, and the conductive shaft 58.

Now, the carbon pan 20 according to the present invention, the carbon pan 20 is a sealed main body 5 serving as a heating space.
0, and is heated in the vicinity of the heater 12 as described above, so that the base material 21 is made of a carbon material as exemplified in each embodiment described later.
That is, it is formed of graphite, C / C composite, or the like. Further, since the carbon tray 20 corresponds to a silicon single crystal having a large diameter, as described above, the carbon tray 20 has a diameter of about 1000 to 1300 mm and a height of about 100 to 200 mm. It is.
As for the thickness, a material having a size corresponding to the material of the base material 21 is employed.

Since the carbon tray 20 must pass through the rotating shaft 55 supporting the crucible 10, the shaft insertion hole 2 is formed at the center thereof as shown in each figure.
4 is formed. And this carbon saucer 2
The inert gas in the closed main body 50 in which the zero is stored is discharged from the seat side of the closed main body 50 to the outside. This gas discharge is performed by the carbon pan 20 shown in FIGS. In the case of (1), it is made from the outer periphery, and FIGS.
In the case of the carbon tray 20 shown in FIG. 5, the process is performed through the exhaust port 25 provided in the carbon tray 20.

The carbon tray 20 shown in FIG. 3 is formed as a single piece from the beginning by cutting out a large lump of graphite or making it by a C / C composite. At least the entire inner surface of the carbon pan 20 is provided with a coating 22 for preventing direct contact between the base material 21 and the silicon melt flowing down into the carbon pan 20. Is formed by pyrolytic carbon. Of course, this coating 22
May be formed on the outer surface of the base material 21 and implemented.
Depending on the case, it may be formed on the entire surface of the base material 21 and carried out.

The coating 22 made of pyrolytic carbon is generally formed as follows. That is, the base material 21 having a predetermined shape is placed in a CVD furnace, for example, at 1400 ° C.
While heating to about the same, methane gas is continuously supplied into the furnace using hydrogen gas as a carrier. As a result, the methane gas is thermally decomposed, and the carbon in the methane gas adheres as a layer on the surface of the base material 21 to form a coating 22 made of pyrolytic carbon.

The carbon pan 20 shown in FIG. 4 and FIG.
According to the present invention, the base material 21 of the carbon pan 20 is not integrally formed from the beginning like the carbon pan 20 shown in FIG. The parts are made integral by an adhesive layer 23. Each of the carbon parts has various shapes depending on the properties of the carbon material constituting the base material 21 of the carbon pan 20 and the shape and configuration of the entire carbon pan 20.

In the case of the carbon tray 20 shown in FIG.
One shaft insertion part 21 for forming the shaft insertion hole 24
c and two degassing parts 2 for forming the exhaust port 25
1d, and the other is a single side frame part 21a. As shown in FIG. 4B, the side frame parts 21a are provided with the shaft insertion parts 21c and the deaeration parts 2a.
Holes suitable for placing and storing 1d are formed, and receiving step portions 27 as shown in (b) and (c) of FIG. 4 are formed around the periphery of each hole. is there. on the other hand,
As shown in (c) of FIG. 4, on the outer periphery of the lower part of the shaft insertion part 21c and the deaeration part 21d, it is suitable to be placed on the receiving step 27 on the side frame part 21a side to prevent it from falling off. An engagement flange 28 is formed.

Each carbon part configured as above is
A resin is applied to the portions that engage with each other, and the resin is used for adhesion. Then, the adhesive resin is carbonized by firing the entire integrated carbon part to form the adhesive layer 23. As a result, each carbon part becomes the base material 21 for the carbon tray 20 integrated by the adhesive layer 23.

Various resins are conceivable as a resin for forming the adhesive layer 23. In this embodiment, (a) a bicyclic resin having at least one element of oxygen, sulfur, or halogen in the molecule The above fused polycyclic aromatic compound. (B) Aromatic cross-linking agents comprising one or more aromatic rings having two or more hydroxymethyl groups or halomethyl groups. (C) an acid catalyst. A mixture of the above (a), (b) and (c), or the above (a)
(B) at least one thermosetting composition selected from thermosetting intermediate reaction products having substantially thermoplasticity obtained by heating and reacting the mixture of (c) (hereinafter simply referred to as a copna resin composition); ) And aggregate. Aggregates in this copna resin composition include carbon,
Graphite or their precursors, or natural polymers,
A carbon precursor such as a cured synthetic polymer can be used.

The above-mentioned copna resin composition is composed of an aromatic skeleton, and oxygen, sulfur or halogen in the molecule functions to increase the crosslink density. An adhesive layer 23 is obtained.

The kopna resin composition has a high carbonization yield. Particularly, when a heavy oil-based or pitch-based condensed polycyclic aromatic compound is used, the carbonization yield is dramatically increased.
Therefore, the shrinkage during carbonization is small, and even if the adhesive layer 23 has a complicated shape as shown in FIG. You can do it.

In addition, although the copna resin composition reacts in a solvent-free system, the viscosity can be freely adjusted by changing the reaction conditions, so that the impregnation can be easily performed. It has characteristics that hardly affect the rate. Therefore, by using this copna resin composition, the adhesive layer 23 whose size and shape can be freely controlled can be obtained without being limited to a special molding method.

Using the above-described copna resin composition and aggregate, bonding for each carbon part was performed, and as described above,
By firing these copna resin composition and aggregate, the carbonized or graphitized adhesive layer 23 is formed. This adhesive layer 23 is formed in a non-oxidizing atmosphere according to a conventional method.

In the case of the carbon pan 20 shown in FIG. 5, the use of the shaft insertion part 21c and the deaeration part 21d as the carbon parts is similar to the carbon pan 20 shown in FIG. Other carbon parts are divided into a cylindrical side frame part 21a and a seat plate part 21b forming a seating surface. That is, in the carbon tray 20, as shown in FIG. 5 (a), for example, a seat plate part 21b formed in a slightly thick disk shape by a graphite material, and a side wall around the seat plate part 21b. For example, a side frame part 21a whose thickness is slightly reduced by a C / C composite is used to form a schematic shape. These seat plate parts 21b and side frame parts 21a are shown in FIG. As shown in (b) of FIG. 5, they are integrated by the adhesive layer 23 formed from the above-described copna resin composition or the like.

Of course, the carbon pan 2 shown in FIGS.
At 0, the carbon parts are integrated as described above to form the base material 21, and then at least the inner surface thereof is formed of pyrolytic carbon as shown in FIG. 4 (b) and FIG. 5 (a). Is formed.

According to the above configuration, the carbon tray 2 according to claim 4, which is configured by each carbon part.
A value of 0 means that it can be very easily carried out for each carbon part if it is to be used for a silicon single crystal having a large diameter.

Examples and comparative examples will be described below.

Example 1 70 parts by weight of aggregate coke pulverized to an average particle size of 20 μm and 30 parts by weight of coal tar pitch as a binder were heated and kneaded.
It was pulverized to 0 to 200 μm to form a carbon material raw material.

Using the carbon material, a desired compact was formed by a rubber press method, and the compact was fired and graphitized to form a graphite material. The obtained graphite material has an average coefficient of thermal expansion from room temperature to 1000 ° C. of 4.8 × 10 ^−6.
/ ° C, and the porosity according to the test method of JIS R7212 was 12%.

This graphite is processed to have an inner diameter of 1010 m.
m, outer diameter 1050mm, height 200mm, bottom thickness 20m
m, a graphite substrate 21 having a shaft insertion hole in the center was obtained.

The obtained graphite substrate 21 was placed in a CVD furnace and heated to 1400 ° C., and methane gas was continuously supplied into the furnace using hydrogen gas as a carrier. Thus, a pyrolytic carbon film 22 having a thickness of 50 μm was formed on the entire surface of the graphite substrate 21. In addition, on the surface of the graphite substrate 21 on which the pyrolytic carbon film 22 is not required to be formed, a shielding member for preventing the formation of the pyrolytic carbon film 22 is arranged, and only a predetermined portion of the graphite substrate 21 is heated. You may implement so that the decomposition | disassembly carbon film 22 may be formed.

Example 2 70 parts by weight of aggregate coke pulverized to an average particle size of 20 μm and 30 parts by weight of coal tar pitch as a binder were heated and kneaded.
It was pulverized to 00 to 500 µm to form a carbon material raw material.

Using this carbon material, a graphite material was formed in the same manner as in Example 1 except for the graphitization temperature. The obtained graphite material has an average coefficient of thermal expansion of 4.1 × 10 ⁻⁶ / ° C. and a porosity of 27% according to the test method of JISR7212.
Met.

This graphite material was processed to obtain a graphite substrate 21 having the same shape as in Example 1, and a pyrolytic carbon film 22 was formed thereon in the same manner as in Example 1.

(Example 3) A carbon fiber filament was used to prepare a tarai-like body, which was repeatedly impregnated with phenol resin, cured, and fired twice to carbonize the whole, as shown in FIG. 4 comprising a C / C composite. 1300m outside diameter
A base material 21 having a thickness of 10 mm, a thickness of 200 mm, and a height of 200 mm was obtained.

Then, a pyrolytic carbon film 22 was formed in the same manner as in Example 1.

(Example 4) Using the graphite material of Example 1,
A graphite substrate 21 having the same shape as that of Example 1 was processed into a divided shape, bonded with a copna resin, and fired to obtain an integrated graphite substrate 21.

A pyrolytic carbon film 22 was formed thereon in the same manner as in Example 1.

(Comparative Example 1) The graphite material of Example 1 was processed to obtain a graphite base material having the same shape as that of Example 1 to obtain a carbon tray.

Comparative Example 2 After heating and kneading 70 parts by weight of aggregate coke pulverized to an average particle size of 10 μm and 30 parts by weight of coal tar pitch serving as a binder, the kneaded product was pulverized to 30 to 150 μm. Then, a carbon material was formed.

Using the carbon material, a desired compact was formed by a rubber press method, and the compact was fired and graphitized to form a graphite material. The average thermal expansion coefficient of the obtained graphite material was 6.5 × 10 ^−G / ° C., and the porosity according to the test method of JISR7212 was 8%.

This graphite material was processed to obtain a graphite base material having the same shape as in Example 1, and a pyrolytic carbon film was formed on the whole.

Comparative Example 3 After heating and kneading 70 parts by weight of aggregate coke ground to an average particle size of 20 μm and 30 parts by weight of coal tar pitch serving as a binder, the kneaded product was ground to 100 to 300 μm. Then, a carbon material was formed.

A desired compact was formed from the carbon material by a stamping press method, and the compact was fired and graphitized to form a graphite material. The thermal expansion coefficient of the obtained graphite material is 3.2
× ^-6 / ° C, and the porosity according to the test method of JIS R7212 was 32%.

This graphite material was processed to obtain a graphite base material having the same shape as in Example 1, and a pyrolytic carbon film was formed thereon in the same manner as in Example 1.

(Comparative Example 4) A substrate having the same shape as that of Example 3 was obtained and used as a carbon tray.

(Example 5) A substrate having the same shape as that of Example 4 was obtained and used as a carbon tray.

(Comparative Example 6) Using the graphite material of Example 1, a graphite substrate 21 having the same shape as in Example 1 was processed into a divided shape, and a graphite substrate 21 integrated by fitting was obtained. .

Thus, a pyrolytic carbon film 22 was formed in the same manner as in Example 1.

The carbon saucer 20 thus obtained is
The gas was set in the silicon single crystal pulling apparatus 100, and the gas in the sealed main body 50 having the same volume was discharged by a vacuum pump. At this time, after the degree of vacuum in the sealed main body 50 became equal to or more than a predetermined value, the time from when the vacuum pump was stopped to when the degree of vacuum in the sealed main body 50 became equal to or less than the predetermined value was measured. Life comparison was also conducted. Table 1 shows the obtained results.
Shown in

[Table 1]

Table 2 shows the results of experimentally flowing the silicon melt using the carbon trays of Example 1 and Comparative Example 1.
Shown in

[Table 2]

[0097]

As described in detail above, first, in the invention according to claim 1, as exemplified in the above embodiment,
"A carbon tray 20 disposed on the bottom surface of the silicon single crystal pulling apparatus 100 to receive molten silicon flowing down from above, and a coating 22 made of pyrolytic carbon was formed on at least the inner surface thereof. It has a structural feature, which allows the received silicon melt to not penetrate into the substrate,
Of course, cracks and breakage can be prevented,
It is also possible to prevent damage or destruction of the entire device due to the silicon melt, and to secure the entire silicon single crystal pulling device. As a result, a silicon single crystal for producing a large-diameter silicon single crystal It is possible to provide a carbon pan that can be adapted to be applied to a lifting device.

Further, in the invention according to claim 2, in the carbon tray 20 according to claim 1, the average thermal expansion coefficient of the carbon base material 21 constituting the base from room temperature to 1000 ° C. is 3. 5 to 6.0 × 10 ⁻⁶ / ° C.
The porosity according to the test method of JISR7212 is 10
% To 30%, which makes it possible to achieve the object of the first aspect of the present invention and to actively use calcined graphite which is relatively inexpensive and easy to process. It is possible to provide a carbon saucer which can be made and has no adverse effect when checking the degree of vacuum in the silicon single crystal pulling apparatus.

Further, according to the third aspect of the present invention, the carbon tray 21 according to the first aspect is characterized in that the carbon substrate 21 is made of a C / C composite. Accordingly, the object of the first aspect of the present invention can be achieved, and further, the overall thickness and weight can be reduced. It is possible to provide a carbon saucer that can safely perform the operation.

According to the fourth aspect of the present invention, the carbon tray 2 according to any one of the first to third aspects described above.
0, the base material 21 is made of graphite parts 21a to 21d.
And each of these graphite parts 21
There is a structural feature in that a to 21d are bonded and integrated with a resin that is calcined and carbonized, thereby achieving the object of the invention according to claims 1 to 3. It is possible to provide a carbon saucer that can be easily manufactured even if the size is increased.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a silicon single crystal pulling apparatus employing a carbon tray according to the present invention.

FIG. 2 is a partially broken perspective view showing a positional relationship between a heater and a carbon tray in the silicon single crystal pulling apparatus.
FIG. 2 is a partially enlarged cross-sectional view mainly showing a pyrolytic carbon coating of FIG.

FIG. 3 shows a carbon tray according to the present invention employed in the silicon single crystal pulling apparatus shown in FIG. 2, (a) is a plan view thereof, and (b) is 1 in the above (a). −
FIG. 3 is an enlarged cross-sectional view taken along line 1 and FIG. 3C is a partially enlarged cross-sectional view taken along line 2-2 in FIG.

4 shows a carbon tray according to the present invention employed in the silicon single crystal pulling apparatus shown in FIG. 1, wherein (a) is a plan view thereof, and (b) is 3 in (a) above. −
FIG. 3 is an enlarged cross-sectional view taken along the line 3, and FIG. 3C is a partially enlarged cross-sectional view of a carbon part and its periphery.

5 shows another embodiment of the carbon saucer according to the present invention employed in the silicon single crystal pulling apparatus shown in FIG. 1, wherein (a) is a longitudinal sectional view and (b) is carbon FIG. 2 is a partially enlarged cross-sectional view of a manufactured part and its periphery.

FIG. 6 is a sectional view showing a conventional silicon single crystal pulling apparatus.

FIG. 7 shows (a) a silicon single crystal pulling apparatus.
FIG. 5 is a partial perspective view showing a state in which a silicon single crystal is pulled in the order of (c) to (c).

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 silicon single crystal pulling apparatus 10 crucible 11 quartz crucible 12 heater 20 carbon saucer 21 carbon (graphite) base material 21a side frame part 21b bottom plate part 21c shaft insertion part 21d degassing part 22 pyrolytic carbon coating 23 adhesive layer 24 axis insertion Hole 25 Exhaust port 26 Chamfer 27 Receiving step 28 Engagement flange 30 Insulating cylinder 40 Insulating material 50 Sealing body

Claims (4)

[Claims] 1. A carbon pan for receiving molten silicon flowing down from above disposed on a bottom surface in a silicon single crystal pulling apparatus, wherein a coating made of pyrolytic carbon is formed on at least an inner surface of the pan. A carbon saucer for a silicon single crystal pulling apparatus. 2. The method according to claim 1, wherein the base material to be the carbon pan has an average coefficient of thermal expansion from room temperature to 1000 ° C. of 3.5 to 3.5.
2. The silicon single crystal pulling apparatus according to claim 1, wherein the silicon single crystal pulling apparatus is made of a graphite material having a porosity of 6.0 × 10 ⁻⁶ / ° C. and a porosity of 10% to 30% according to a test method of JISR7212. Saucer made of carbon. 3. The method according to claim 1, wherein the base material to be the carbon pan is C /
2. A structure comprising a C composite.
A carbon saucer for a silicon single crystal pulling apparatus according to [1]. 4. A material in which the base material to be the carbon tray is made of graphite parts, and each of the graphite parts is integrated by bonding with a resin that is baked and carbonized. A carbon tray for a silicon single crystal pulling apparatus according to any one of claims 1 to 3.