JP4711428B2 - Single crystal pulling device and its hot water leak tray - Google Patents

Description

  The present invention relates to a single crystal pulling apparatus that pulls up while growing a single crystal and a hot water leak receiving tray thereof.

  The Czochralski method (hereinafter referred to as “CZ method”) is widely used for growing silicon single crystals. In this method, the seed crystal is brought into contact with the surface of the silicon melt contained in the crucible, the crucible is rotated, and the seed crystal is pulled upward while rotating in the opposite direction. In this way, a single crystal is formed.

  As shown in FIG. 2, in the pulling method using the conventional CZ method, first, raw silicon is loaded into a quartz glass crucible 51 and heated by a heater 52 to obtain a silicon melt M. Thereafter, the seed crystal P attached to the pulling wire 50 is brought into contact with the silicon melt M to pull up the silicon crystal C.

  In general, prior to the start of pulling, after the temperature of the silicon melt M is stabilized, as shown in FIG. 3, necking is performed in which the seed crystal P is brought into contact with the silicon melt M to dissolve the tip of the seed crystal P. Necking is an indispensable process for removing dislocations generated in a silicon single crystal due to a thermal shock generated by bringing the seed crystal P into contact with the silicon melt M. The neck portion P1 is formed by this necking. The neck portion P1 is generally required to have a diameter of 3 to 4 mm and a length of 30 to 40 mm or more.

  In addition, as a process after the start of pulling, after necking is completed, a crown process for expanding the crystal to the diameter of the straight body part, a straight body process for growing a single crystal as a product, and a single crystal diameter after the straight body process are gradually reduced. The tail process is performed.

By the way, in recent years, the silicon raw material filled in the crucible has increased due to the increase in diameter and length of the silicon single crystal, and when the single filling is insufficient, the silicon raw material is refilled during the pulling of the single crystal. Recharge operation is being carried out.
However, when the single crystal becomes larger and longer and the single crystal pulling time (growth time) becomes longer, the inner surface of the crucible is dissolved by the silicon melt and the inner surface of the crucible being in contact with each other for a long time. There was a problem that the wall thickness was reduced (thinning phenomenon) and cracks and through holes were easily generated in the crucible. In other words, if a crack or a through hole occurs in the crucible, the silicon melt flows out of the crucible (referred to as hot water leakage), erodes the bottom of the chamber and the cooling water piping that cools the chamber, and causes a major accident such as a steam explosion. There was a risk of occurrence.

In order to solve such a problem, as shown in FIG. 2, conventionally, a hot water receiving tray 53 for receiving the molten silicon melt is provided below the crucible 51, and a predetermined amount of molten silicon is obtained by the receiving pan 53. The liquid can be stored.
However, for example, when the single crystal being pulled is dropped into the crucible due to the occurrence of an earthquake, the crucible is largely destroyed, and almost the entire amount of the silicon melt in the crucible may flow out. In that case, in the hot water leak receiving tray with a small storage capacity, the silicon melt that has leaked hot water cannot be stored, and the chamber may be melted by the melt overflowing from the receiving pan and the peripheral device may be damaged.

Therefore, in Patent Document 1, isotropic carbon that does not allow silicon melt to permeate is used as a material, and a hot water leak tray that can contain all of the silicon melt contained in the crucible is disclosed. Yes.
Japanese Patent No. 3741043

If all of the silicon melt in the crucible can be accommodated as in the hot water leak tray disclosed in Patent Document 1, even if all of the silicon melt in the crucible has flowed out due to damage to the crucible or the like, the entire amount is accommodated in the crucible. The peripheral device can be prevented from being damaged.
However, in recent years, there has been an increasing demand for higher quality and energy saving of single crystals. For this reason, the hot zone structure composed of a crucible, a heater and the like has been further increased in size. When the entire amount of the silicon melt is accommodated like a saucer, the size of the saucer must be increased with the increase in the size of the hot zone structure.
That is, there is a problem that not only the hot zone structure but also the size of the hot water leak tray is increased, so that the size of the chamber or the like for accommodating them is greatly increased, and the cost for manufacturing the apparatus is greatly increased.

  The present invention has been made under the circumstances as described above, and can accommodate the entire amount of silicon melt in the crucible in the hot water leak tray of the single crystal pulling apparatus, and can increase the outer size. It is an object of the present invention to provide a hot water leak receiving tray that can suppress an increase in cost associated therewith, and a single crystal pulling apparatus including the hot water leak receiving pan.

In order to solve the above-mentioned problem, the hot water leakage tray of the single crystal pulling apparatus according to the present invention is provided in the single crystal pulling apparatus that pulls the single crystal from the crucible by the Czochralski method, and flows out of the crucible. In the hot water leak tray that contains the silicon melt, the tray is formed of carbon fibers having a bulk specific gravity of 0.12 to 0.17 g / cm ³ , and the crucible of the single crystal pulling apparatus can be rotated on the inner surface of the tray. A protrusion is formed upward at a portion through which the holding shaft formed and the inert gas discharge pipe for discharging the inert gas penetrates, and two ring-shaped recessed spaces are formed concentrically by the protrusion. JP sum of capacity of the ring-shaped concave space, the sum of the volume of the carbon fibers constituting the saucer, the larger than the total volume of the silicon melt accommodated in at least the crucible Having.

With this configuration, even if the silicon melt flows out completely due to crucible damage or the like in the single crystal pulling process, the carbon fiber constituting the saucer absorbs an amount of silicon melt approximately equal to its volume. Further, by holding the silicon melt in the concave space as a tray container, all of the silicon melt that has flowed into the tray can be accommodated.
Further, the volume of the saucer vessel body (volume of the carbon fibers constituting the pan), for the sum of the recessed space formed as pan container is containable amount of the silicon melt, the increase in the silicon melt (raw material) The accompanying increase in the outer size of the tray container (recessed space) can be suppressed. As a result, an increase in the size of the chamber or the like is also suppressed, so that the cost required can be reduced.

Further, it is desirable that an impregnation layer of glassy carbon or a silicon carbide impregnation layer having a predetermined thickness is formed on the outer surface of the side and bottom of the tray.
Thus, by forming an impregnated layer of glassy carbon or an impregnated layer of silicon that has been partially siliconized, the outer surface of the side and bottom of the saucer is coated to improve its heat resistance and penetration resistance. can do. Therefore, when the silicon melt flowing into the saucer is absorbed by the carbon fiber forming material and the melt reaches the outer surface of the saucer, the soaking layer is stopped and the leakage of the melt outside the saucer is stopped. It can be avoided.

Moreover, in order to solve an above-described subject, the single-crystal pulling-up apparatus which concerns on this invention has the characteristics in providing the said hot water leak receiving tray.
By using the single crystal pulling apparatus having such a configuration, it is possible to suppress an increase in the outer size of the tray container as the silicon melt (raw material) increases, and to reduce the cost.

  According to the present invention, in the leaking pan of the single crystal pulling apparatus, the entire amount of the silicon melt in the crucible can be accommodated, and an increase in the external size and the accompanying cost increase can be suppressed. A single crystal pulling apparatus provided with a saucer and its leaking saucer can be obtained.

Embodiments of a single crystal pulling apparatus according to the present invention and a hot water leak receiving tray will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a single crystal pulling apparatus provided with a hot water leak receiving tray according to the present invention.
The illustrated single crystal pulling apparatus 1 is loaded in a furnace body 2 formed by superposing a pull chamber 2b on a main chamber 2a, a quartz glass crucible 3 provided in the furnace body 2, and a quartz glass crucible 3. The side heater 4a and the bottom heater 4b for melting the semiconductor raw material (raw material silicon) M and a pulling mechanism (not shown) for pulling up the single crystal C to be grown are provided.

  The pulling mechanism has a pulling wire 5, and a seed crystal P is attached to the tip of the wire 5, and the single crystal C is pulled while rotating in a certain direction around the wire axis. The quartz glass crucible 3 is configured to be rotatable about a vertical axis by a holding shaft 6 and is configured to rotate in a direction opposite to the rotation direction of the single crystal C by the wire 5.

  Further, in the main chamber 2a, an upper portion and a lower portion are formed so as to surround the periphery of the single crystal C above and in the vicinity of the quartz glass crucible 3, and an extra portion from the side heater 4a and the like is added to the growing single crystal C. A radiation shield 7 is provided so as not to give a radiant heat. The distance dimension (gap) between the lower end surface of the radiation shield 7 and the melt surface is set to a predetermined distance (for example, 25 mm) according to desired characteristics of the single crystal to be grown.

  Further, from above the pull chamber 2b, an inert gas G is flowed downward to adjust the atmosphere in the chamber, and after passing around the single crystal C in the quartz glass crucible 3, it is provided at the bottom of the chamber. The exhaust gas is discharged from the inert gas discharge pipe 8.

  In addition, a heat insulating member 9 is provided around the side heater 4a to block heat to the main chamber 2a. Below the bottom heater 4b, silicon that has flowed out when hot water leaks from the crucible 3 occurs. A hot water leak tray 10 according to the present invention for containing the melt M is provided.

The holding shaft 6 and the inert gas discharge pipe 8 are provided so as to penetrate the hot water leak tray 10 in the vertical direction. Specifically, as shown in FIG. 1, projections 10 b and 10 c are formed upward at a portion where the holding shaft 6 and the inert gas discharge pipe 8 penetrate on the inner surface of the tray, and the holding shaft 6 and the inert gas are formed. The silicon melt M flowing from the crucible 3 is prevented from entering the discharge pipe 8. Further, due to the protrusions 10b and 10c formed on the inner surface of the tray, the concave space capacity as the tray is the sum of two ring-shaped, so-called donut-shaped concave spaces A and B formed concentrically.

The hot water leak tray 10 is formed thick to improve the heat insulation inside and outside the furnace, and the material thereof is fibrous carbon, specifically, carbon fiber having a bulk specific gravity of 0.12 to 0.17 g / cm ^3. Is formed. That is, by forming with such a material, it functions as a heat insulating material, can sufficiently absorb the silicon melt M, and does not change its shape.

Further, in the hot water leak receiving tray 10, the total of the volume of carbon fibers constituting the outer shape and the recessed space volumes A and B formed as a receiving container is at least larger than the total volume of the silicon melt contained in the crucible. It is configured to be large.
That is, when the silicon melt flows into the leaking pan 10, the silicon melt is first absorbed by the carbon fibers constituting the pan 10, and the melt that cannot be absorbed is held in the recessed spaces A and B as the pan containers. By doing so, the entire volume of the silicon melt that has flowed out of the crucible can be accommodated.

  An impregnation layer 10a in which glassy carbon is impregnated in advance (or an impregnation layer 10a in which silicon is impregnated and partially siliconized) is formed on the outer surface of the side and bottom of the hot water receiving tray 10. Yes. That is, the outer surface of the hot-water leaking tray 10 is coated with the impregnation layer 10a so that the heat resistance and the penetration resistance are improved. Therefore, when the silicon melt that has flowed into the saucer 10 is absorbed by the carbon fiber and the melt reaches the outer surface of the saucer, exudation is stopped by the containing layer 10a, and leakage of the melt outside the saucer is avoided. Is done.

In the single crystal pulling apparatus 1 configured as described above, the raw material silicon M is first loaded into the quartz glass crucible 3, and the crystal growth process is started as follows.
First, the quartz glass crucible 3 is heated by the side heater 4a and the bottom heater 4b, and the raw material silicon M in the crucible 3 is melted.

  Further, the quartz glass crucible 3 is rotated in a predetermined direction by the rotation driving of the holding shaft 6 and the wire 5 is lowered. Then, the seed crystal P attached to the wire 5 is brought into contact with the silicon melt M, and the wire 5 is controlled to rotate in the direction opposite to the crucible 3 while being raised, and necking for melting the tip of the seed crystal P is performed. Thus, the neck portion P1 is formed.

  Thereafter, the pulling conditions are adjusted using parameters such as the power supplied to the side heater 4a and the bottom heater 4b and the single crystal pulling speed (usually a speed of several millimeters per minute), and the crown process, straight body process, tail part process, etc. Single crystal pulling steps are sequentially performed.

  In this single crystal pulling step, even if the silicon melt M flows out of the crucible 3 for some reason, such as breakage of the crucible 3, the entire amount of the melt M is accommodated in the molten metal leak tray 10 as described above. Therefore, the peripheral device is not damaged.

As described above, according to the embodiment of the present invention, in the single crystal pulling step, even if all of the silicon melt M flows out due to damage of the crucible 3 or the like, the volume of the carbon fiber constituting the tray 10 is increased. By absorbing the silicon melt of an amount substantially equal to the above, and holding the silicon melt in the recessed spaces A and B as the tray containers, the entire amount of the silicon melt flowing into the tray 10 can be accommodated.
Moreover, since the sum total of the volume of the saucer container body and the recessed spaces A and B formed as the saucer containers is an amount that can be accommodated with respect to the silicon melt, the hot zone configuration is enlarged, that is, the silicon melt (silicon raw material) Expansion of the outer size of the tray container (recessed space) accompanying the increase can be suppressed. As a result, an increase in the size of the chamber or the like is also suppressed, so that an increase in cost can be reduced.

  Subsequently, the hot water leakage tray of the single crystal pulling apparatus according to the present invention will be further described based on examples.

[Experiment 1]
In Experiment 1, a test plate made of carbon fiber, which is the material of the hot water leak tray 2 in the present embodiment, was used to verify its absorbability (permeability) with respect to the silicon melt.
Specifically, a carbon fiber test plate having a bulk specific gravity of 0.13 g / cm ³ , a length of 20 cm, a width of 20 cm, and a height of 3 cm was poured from the upper surface, and then the test plate was cooled, A test piece of 5 cm in length and 5 cm in width was cut out from the vicinity of the center of the film, and the dimensional change and weight change from before the silicon melt was poured were confirmed.

As a result of this experiment, the shape of the test piece did not change, and the weight increased from 10 g to 185 g. That is, 175 g of silicon melt permeated 10 g of carbon fiber. This coincided with the amount when approximately 100% of the silicon melt was absorbed with respect to the volume of the test piece.
Therefore, it was confirmed that when a carbon fiber hot water leaking tray having a bulk specific gravity of 0.13 g / cm ³ was used, a silicon melt substantially equal to the volume of the tray could be permeated.

[Experiment 2]
In Experiment 2, the hot-water leak tray shown in the above embodiment was actually formed, and the silicon melt storage capacity was verified.
Specifically, as a hot water leaking tray, a carbon fiber having a bulk specific gravity of 0.16 g / cm ³ , a tray having a diameter of 800 mm, a height of 230 mm, and a bottom thickness of 150 mm is prepared. A glassy carbon impregnation layer was formed on the outer surface. Then, 20 kg of the silicon melt was poured into the prepared hot-water leak pan, and the storage result and the exudation to the outer surface of the side and bottom of the pan were verified.
As a result of Experiment 2, it was confirmed that the entire amount of the poured silicon melt could be accommodated by the saucer, and it was confirmed that there was no exudation of the silicon melt on the outer surface.

  From the experimental results of the above examples, it is possible to accommodate the entire amount of the silicon melt in the crucible by using the hot water receiving tray of the single crystal pulling apparatus of the present invention, and to increase the external size and the associated costs. It was confirmed that the increase can be suppressed.

  The present invention relates to a single crystal pulling apparatus that pulls up a single crystal by the Czochralski method and a hot water leak tray, and is suitably used in the semiconductor manufacturing industry and the like.

FIG. 1 is a cross-sectional view showing a schematic configuration of a single crystal pulling apparatus provided with a hot water leak receiving tray according to the present invention. FIG. 2 is a diagram for explaining a pulling method using a conventional CZ method. FIG. 3 is a diagram for explaining formation of a neck portion in a pulling method using a conventional CZ method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single crystal pulling apparatus 2 Furnace body 2a Main chamber 2b Pull chamber 3 Quartz glass crucible (crucible)
4a Side heater 4b Bottom heater 5 Pulling wire 6 Holding shaft 7 Radiation shield 8 Inert gas discharge pipe 9 Heat insulating member 10 Hot water leak tray 10a Impregnation layer C Single crystal G Inactive gas M Raw material silicon, silicon melt P Seed crystal P1 Neck part

Claims (3)

In a single crystal pulling apparatus that is provided in a single crystal pulling apparatus that pulls a single crystal from a crucible by the Czochralski method,
The tray is formed of carbon fibers having a bulk specific gravity of 0.12 to 0.17 g / cm ³ , and a holding shaft that allows the crucible of the single crystal pulling device to rotate on the inner surface of the tray and an inert gas to be discharged. A protrusion is formed upward at a portion where the active gas discharge pipe penetrates, and two ring-shaped recess spaces are formed concentrically by the protrusion,
The total capacity of the two ring-shaped recess spaces and the total volume of the carbon fibers constituting the tray are at least larger than the total capacity of the silicon melt contained in the crucible. Single crystal pulling device for leaking water.   The glass impregnation layer or the silicon carbide impregnation layer which has a predetermined thickness dimension is formed in the outer surface in the side part of the said saucer, and a bottom part, The impregnation layer of the siliconized silicon is formed in Claim 1 characterized by the above-mentioned. The hot water leak tray of the described single crystal pulling apparatus.   A single crystal pulling apparatus comprising the hot water leak receiving tray according to claim 1 or 2.

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