JP4974770B2 - How to replace the crucible - Google Patents

Description

The present invention relates to a crucible exchanging method that moves to the vicinity of a single crystal pulling apparatus installed at a predetermined position and attaches or removes a crucible to the single crystal pulling apparatus.

The CZ method is widely used for the growth of silicon single crystals. This method pulls up a single crystal while growing it from a silicon melt contained in a quartz glass crucible.
Specifically, as shown in FIG. 7, a crucible 51 capable of rotating around a vertical axis is provided in the furnace body 50, and a heater 52 for heating the silicon melt M is provided around the crucible 51. .

  Then, the seed crystal P attached to the pulling wire 53 is brought into contact with the surface of the melt M, the crucible 51 is rotated, and the seed crystal P is pulled upward while rotating in the opposite direction. A silicon single crystal C is formed at the lower end of P.

  In general, prior to the start of pulling, after the temperature of the melt M is stabilized, as shown in FIG. 8, necking is performed in which the seed crystal P is brought into contact with the 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 thermal shock generated by contact between the seed crystal P and the 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 diameter of a single crystal to be pulled has been increased, and for example, the diameter size of a crucible for growing a silicon single crystal having a diameter of 8 inches or more is required to be 22 inches or more, and the surrounding hot zone is also large. It has become.
For this reason, compared with the conventional small-diameter pull-up furnace, the heat-retaining effect in the furnace is improved, and the natural cooling time after the heater power is turned off becomes longer, so that the production efficiency is lowered.

That is, in the case of a large-diameter hot zone, the natural cooling time is 8 hours to 12 hours, which is 10% or more of the operation time. Furthermore, since the cleaning time is increased and 1 to 3 hours are required, it has been desired to shorten these times.
The natural cooling time is the time from when the heater power is turned off until the worker can perform operations such as removal of silicon oxide adhered to the crucible, etc. The time required for the surface temperature of the silicon residue to be about 100 ° C. or less is a standard.

With respect to such a problem, Patent Document 1 (Japanese Patent Laid-Open No. 9-202694) discloses that at a thermal conductivity of 800 ° K., at least about 55 × 10 ⁻⁵ g. cal. Disclosed is a method in which a gas (for example, helium gas) of / (second · cm ² ) (° C./cm) is caused to flow into the furnace, thereby cooling the inside of the furnace.
JP-A-9-202694

  However, in the cooling method of the lifting furnace disclosed in Patent Document 1, helium gas, which is a preferable gas for flowing into the furnace, is expensive, and it is necessary to increase the supply device. There was another problem that the cost increased.

The present invention has been made under the circumstances as described above. In the crucible exchanging method in which the crucible is attached to or removed from the single crystal pulling apparatus by moving to the vicinity of the single crystal pulling apparatus. it is possible to shorten the time from after the crystal pulling until the next single crystal pulling begins, and to provide a crucible exchange method capable of improving the production efficiency while suppressing the cost.

In order to solve the above-described problem, a crucible exchanging method according to the present invention is a crucible exchanging method for exchanging a crucible with respect to a single crystal pulling apparatus including a pull chamber and a main chamber, and the pulling operation of the single crystal After the step of natural cooling until the silicon residue reaches 450 to 550 ° C., and after the natural cooling step, the pull chamber is removed from the main chamber and the single crystal pulling apparatus is opened, and the single crystal After the step of opening the pulling device, a base that can be attached to and detached from the tip of the single crystal pulling wire in the single crystal pulling device, and a crucible that can be rotated with respect to the base and can be gripped. The grip member has a bending strength of 70 MPa or more and a compressive strength of 120 MP. Attaching the crucible handling device provided with the carbon fiber reinforced carbon composite material (C / C composite) as described above to the tip of the single crystal pulling wire in the opened single crystal pulling device; After the step of attaching the crucible handling device to the tip of the crystal pulling wire, the crucible after pulling the single crystal is gripped using the crucible handling device, and the crucible handling device is moved above the carriage together with the pull chamber, Removing the crucible from the single crystal pulling device, lowering the single crystal pulling wire, and placing the crucible on a carriage by the crucible handling device releasing the holding of the crucible; After the step of removing the crucible from the crystal pulling apparatus, another cleaned crucible filled with raw silicon is placed in the Grasping with the crucible handling device, moving the crucible handling device together with the pull chamber, and mounting the other crucible in the single crystal pulling device; and mounting the other crucible in the single crystal pulling device After the step, the step of attaching the pull chamber to the main chamber and closing the single crystal pulling apparatus is performed.

According to such a configuration, the crucible in a high temperature state can be held via the carbon fiber reinforced carbon composite material (C / C composite member), and the crucible can be easily carried out of the chamber.
In addition, if the crucible carried out is in a high temperature state, the cleaning operation cannot be performed immediately. Therefore, by setting another crucible that has been cleaned and filled with raw material silicon in the chamber, the subsequent raw material silicon melting You can move to work immediately.
Thereby, it is possible to shorten the time from the single crystal pulling up to the start of the next single crystal pulling, and to improve the production efficiency.
Moreover, since the above-mentioned effect can be obtained only by using the carbon fiber reinforced carbon composite material (C / C composite) at the contact portion with the crucible, the cost is higher than that of the conventional apparatus and method using helium gas or the like every time. The increase can be greatly suppressed.

According to the present invention, a crucible exchanging method using a crucible handling apparatus that moves to the vicinity of a single crystal pulling apparatus installed at a predetermined position and attaches or removes a crucible to the single crystal pulling apparatus. The crucible exchanging method can be obtained in which the time from the single crystal pulling to the start of the next single crystal pulling can be shortened, and the production efficiency can be improved while suppressing the cost.

Embodiments of a crucible exchanging method according to the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the overall structure of a single crystal pulling apparatus 1 crucible handling device used Oite the present invention is applied.
This single crystal pulling apparatus 1 includes a furnace body 2 formed by stacking a detachable pull chamber 2b on a cylindrical main chamber 2a, and a crucible 3 provided on a support shaft 15 in the furnace body 2. And the heater 4 for melting the semiconductor raw material M loaded in the crucible 3.

The crucible 3 is an assembly having a double structure, and is composed of a quartz glass crucible 3a on the inside and a graphite crucible 3b on the outside.
Further, as described above, the pull chamber 2b is configured to be detachable from the main chamber 2a. At the time of detachment, the arm 13 attached to the pull chamber 2b is gripped by an articulated robot or the like (not shown), and the pull chamber 2b is It is attached and detached by turning and moving up and down.

Further, a pulling mechanism 5 for pulling up the single crystal C is provided above the furnace body 2. The pulling mechanism 5 includes a winding mechanism 5a driven by a motor and a pulling wire 5b wound on the winding mechanism 5a. It consists of. A seed chuck 14 is provided at the tip of the wire 5b, and the seed crystal P is held by the seed chuck 14 and pulled up while growing the single crystal C.
Moreover, in the furnace body 2, it is comprised so that the inert gas G may be always flowed from upper direction toward the downward direction over the pulling process of the single crystal C.

  Further, the single crystal pulling apparatus 1 rotates the crucible 3 (support shaft 15) and the heater controller 9 that controls the amount of power supplied to the heater 4 that controls the temperature of the silicon melt M, as shown in FIG. The motor 10 and the motor control part 10a which controls the rotation speed of the motor 10 are provided. Furthermore, a lifting / lowering device 11 for controlling the height of the quartz glass crucible 3 by the lifting / lowering movement of the support shaft 15, a lifting / lowering device controller 11 a for controlling the lifting / lowering device 11, and a wire for controlling the pulling speed and the number of rotations of the grown crystal. And a reel rotation device controller 12. Each of these control units 9, 10 a, 11 a, 12 is connected to an arithmetic control device 8 b of the computer 8.

Next, the crucible handling device used in the present invention will be described. FIG. 2 is a cross-sectional view of the crucible handling device 19.
As shown in FIG. 6, the crucible handling device 19 is provided with a base 21 and a pair of grips provided so as to be rotatable about the joint 21 a with respect to the base 21 and having a contact portion with a predetermined width with respect to the crucible 3. And a member 22.
The joint portion 21a is provided with a stepping motor (not shown) for opening and closing the pair of grip members 22 with respect to the object to be grasped (the crucible 3). The stepping motor is driven by a command from the arithmetic control device 8b. Control is made.

Further, a C / C composite member 23 that is a carbon fiber reinforced carbon composite material is provided on the inner surface of the grip member 22, that is, a contact portion with the crucible 3. Even the crucible 3 at 550 ° C. can be easily gripped by the grip 22. The C / C composite member used here is required to have a bending strength of 70 MPa or more and a compressive strength of 120 MPa or more.
Further, a protrusion 20 is provided at the center of the upper surface of the base 21, and the crucible handling device 19 can be supported by the wire 5 b when the protrusion 20 is detachably held by the seed chuck 14. ing.

Next, a single crystal pulling process using the single crystal pulling apparatus 1 shown in FIG. 1 and a subsequent crucible exchange process will be described.
First, in the single crystal pulling step, a raw material silicon M1 melting step is performed.
An inert gas G is supplied into the furnace body 2, and raw silicon is loaded into the crucible 3. Next, based on the program stored in the storage device 8a of the computer 8, first, the heater control unit 9 is operated by the command of the arithmetic control device 8b to heat the heater 4, and the melting operation of the raw silicon of the crucible 3 is started. The
When the raw material silicon is melted, the motor control unit 10a controls the driving of the motor 10, and the crucible 3 rotates at a predetermined rotation speed.

When the silicon melt M is generated by melting the raw material silicon, the single crystal pulling operation is started.
That is, the elevator controller 11a and the wire reel rotating device controller 12 are further operated by the command of the arithmetic control device 8b, the height position of the rotating crucible 3 is adjusted, and the winding mechanism 5a is operated. Then, the wire 5b is lowered.
Then, the seed crystal P held by the seed chuck 14 is brought into contact with the silicon melt M at the tip of the wire 5b, and necking P1 is formed by melting the tip of the seed crystal P.

  Thereafter, the pulling conditions are adjusted by parameters of the power supplied to the heater 4 and the single crystal pulling speed (usually a speed of several millimeters per minute) according to the command of the arithmetic control device 8b, and the crown process, the straight body process, the tail part A single crystal pulling step such as a step is sequentially performed.

Next, the crucible exchange process after pulling the single crystal will be described based on the flow of FIG. 3 and the process diagrams of FIGS.
First, as shown in FIG. 4A, when the pulling operation of the single crystal C is completed, the heater 4 is turned off (step ST1 in FIG. 3).

Next, the silicon residue is naturally cooled until it reaches 450 to 550 ° C. (step ST2 in FIG. 3). As shown in FIG. 4B, the arm 13 is held by an articulated robot or the like (not shown) and the pull chamber 2b is main. The chamber 2a is removed (step ST3 in FIG. 3).
Next, as shown in FIG. 4C, the crucible handling device 19 is held on the seed chuck 14, and the high temperature crucible 3 is gripped by the crucible handling device 19. At this time, the support shaft 15 is raised so that the crucible 3 can be easily gripped. Then, as shown in FIG. 4D, the crucible 3 is removed from the support shaft 15 and moved together with the pull chamber 2b above the carriage 30 as shown in FIG. 5A.

  Then, as shown in FIG. 5 (b), the crucible handling device 19 that holds the used crucible 3 with the wire 5b lowered is moved onto the carriage 30, and the crucible handling device 19 releases the holding of the crucible 3. Thus, the crucible 3 is placed on the carriage 30 and carried out by the carriage 30 (step ST4 in FIG. 3).

When the used crucible 3 is carried out, as shown in FIG. 6A, a new crucible 3 filled with the silicon raw material M1 is gripped by the crucible handling device 19, and the pull chamber 2b is located above the main chamber 2a. Moved.
6B, a new crucible 3 is placed on the support shaft 15 (step ST5 in FIG. 3), and the pull chamber 2b from which the crucible handling device 19 is removed from the seed chuck 14 is the main chamber. Placed on 2a, the chamber 2 is closed (step ST6 in FIG. 3). Thereby, the melting operation of the raw material silicon M1 for the next single crystal pulling operation becomes possible.

As described above, according to the embodiment of the present invention, after pulling the single crystal, the crucible 3 is held by the crucible handling device 19 via the C / C composite member 23 in a state where the pull chamber 2b is lifted and the chamber is opened. By doing so, even if the crucible 3 is still at a high temperature (450 to 550 ° C.), it can be easily carried out of the chamber 2.
Further, if the crucible 3 carried out is in a high temperature state, the cleaning operation cannot be performed immediately. Therefore, another crucible 3 that has been cleaned and filled with the raw material silicon M1 is held by the crucible handling device 19 and the chamber 2 If it is set inside, it is possible to immediately shift to the subsequent raw material silicon melting operation.
Thereby, it is possible to shorten the time from the single crystal pulling up to the start of the next single crystal pulling, and to improve the production efficiency.
Further, the crucible handling apparatus 19 according to the present invention can obtain the above-mentioned effect only by using the C / C composite member 23 at the contact portion with the crucible 3, so that a conventional helium gas or the like is used every time. The cost increase can be greatly suppressed as compared with the method.

  In the above embodiment, the base 21 of the crucible handling device 19 is detachably held by the seed chuck 14 located at the tip of the single crystal pulling wire 5b. The handling device of the invention is not limited to the configuration, and for example, the base 21 may be detachable from the pull chamber 2b.

  Subsequently, the crucible handling apparatus according to the present invention will be further described based on examples. In this example, the effect was verified by actually performing experiments using the single crystal pulling apparatus and the crucible handling apparatus having the configuration described in the above embodiment.

In this experiment, a quartz glass crucible with a diameter of 24 inches was filled with 120 g of raw silicon (polycrystalline silicon), and a single crystal with a diameter of 200 mm was pulled up.
The flow rate of the inert gas (Ar gas) flowing into the furnace (inside the chamber) was 80 L / min, and the furnace pressure was constant at 90 Torr.

The chamber is opened 4.5 hours after the start of natural cooling, the pull chamber is raised with the crucible at about 500 ° C, and a crucible handling device whose C / C composite is in contact with the crucible is attached to the seed chuck. The crucible was removed and cleaned, and a crucible filled with raw material silicon was attached.
In addition, the used C / C composite member used the thing whose bending strength is 70 Mpa or more and whose compressive strength is 120 Mpa or more.
As a result of this experiment, it took 0.5 hour to remove the used crucible, 0.5 hour to install the crucible filled with raw material silicon, and 0.5 hour to lightly clean the crucible after mounting. The work was completed in 6 hours.

Comparative example

In the comparative example, similarly to the example, a quartz glass crucible having a diameter of 24 inches was filled with 120 g of raw silicon (polycrystalline silicon), and a single crystal having a diameter of 200 mm was pulled up.
The flow rate of the inert gas (Ar gas) flowing into the furnace (inside the chamber) was 80 L / min, and the furnace pressure was constant at 90 Torr.
After pulling the single crystal, the heater power was turned off to perform natural cooling, and the temperature near the silicon residue surface was measured with a thermocouple attached to the tip of the seed chuck.
As a result, the temperature reached 500 ° C. after 4.5 hours from the start of natural cooling and reached 100 ° C. after 11 hours.

  From the experimental results of the above examples, by using the crucible handling apparatus of the present invention, it is possible to greatly shorten the time from the single crystal pulling up to the start of the next pulling process, and to improve the production efficiency. I confirmed that I could do it.

  The present invention relates to a crucible handling apparatus and a crucible exchange method for mounting or removing a crucible on a single crystal pulling apparatus, and is suitably used in the semiconductor manufacturing industry and the like.

FIG. 1 is a block diagram showing an overall configuration of a single crystal pulling apparatus to which a crucible handling apparatus according to the present invention is applied. FIG. 2 is a cross-sectional view of the crucible handling apparatus according to the present invention. FIG. 3 is a flow showing the procedure of the crucible exchange step after pulling the single crystal. FIG. 4 is a process diagram showing each state of the crucible exchange process after pulling a single crystal. FIG. 5 is a process diagram showing each state of the crucible exchange process after pulling a single crystal. FIG. 6 is a process diagram showing each state of the crucible exchange process after pulling a single crystal. FIG. 7 is a diagram for explaining a pulling method using the conventional CZ method. FIG. 8 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 Crucible 4 Heater 5 Pulling mechanism 5b Wire 8 Computer 8a Storage device 8b Arithmetic storage device 10 Motor 10a Motor controller 13 Arm 14 Seed chuck 15 Support shaft 19 Crucible handling device 21 base 22 grip member 23 C / C composite member (carbon fiber reinforced carbon composite material)
C Single crystal M Silicon melt P Seed crystal P1 Neck part S Raw material silicon

Claims (1)

A crucible exchanging method for exchanging a crucible for a single crystal pulling apparatus comprising a pull chamber and a main chamber,
After the pulling of the single crystal is completed, naturally cooling until the silicon residue reaches 450 to 550 ° C .;
After the natural cooling step, the pull chamber is removed from the main chamber and the single crystal pulling device is opened;
After the step of opening the single crystal pulling apparatus, a base that is detachable with respect to a distal end portion of the single crystal pulling wire in the single crystal pulling apparatus, and the crucible provided so as to be rotatable with respect to the base A carbon fiber reinforced carbon composite material (C) having a bending strength of 70 MPa or more and a compressive strength of 120 MPa or more at a contact portion of the grip member with the crucible. Attaching the crucible handling device provided with the / C composite to the tip of the single crystal pulling wire in the opened single crystal pulling device;
After the step of attaching the crucible handling device to the tip of the single crystal pulling wire, the crucible after pulling the single crystal is gripped using the crucible handling device, and the crucible handling device is moved above the carriage together with the pull chamber. Removing the crucible from the single crystal pulling apparatus, lowering the single crystal pulling wire, and placing the crucible on a carriage by releasing the crucible handling by the crucible handling apparatus ;
After the step of removing the crucible from the single crystal pulling apparatus, another cleaned crucible filled with raw material silicon is gripped by the crucible handling apparatus, the crucible handling apparatus is moved together with the pull chamber, and the other crucible is moved. Mounting a crucible in the single crystal pulling apparatus;
After the step of mounting the additional crucible in the single crystal pulling apparatus, the step of mounting the pull chamber in the main chamber and closing the single crystal pulling apparatus;
A crucible exchanging method comprising:

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