JP2008143742A - Single crystal pulling apparatus and method of manufacturing single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single crystal pulling apparatus and a method of manufacturing a single crystal, in which the time for melting raw material silicon can be shortened and operation efficiency can be improved on the single crystal pulling apparatus. <P>SOLUTION: The single crystal pulling apparatus comprises: a rotating means for rotating a crucible 3 around the perpendicular axis; a radiation shield 6 for shielding radiation heat to a single crystal which is formed with open upper portion and lower portion to surround the periphery of the single crystal at the upper part of the crucible 3; a support means 14 for supporting the radiation shield 6 from the below; an elevation means 7a for elevating the radiation shield 6 to release the support of the support means 14; and a treatment tool 15 disposed freely rotationally movable to downward by its own weight; wherein the treatment tool 15 is fixed on the backside of the radiation shield 6 in the state that the radiation shield 6 is supported by the support means 14, rotates downward in the state that the radiation shield 6 is elevated by the elevation means 7a and is slidably attached to the crucible 3 rotating by the rotation means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a single crystal pulling apparatus and a single crystal manufacturing method for pulling up while growing a single crystal by the Czochralski method (hereinafter referred to as “CZ method”).

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. 6, 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. 7, 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 the 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.
A method for producing a silicon single crystal using this CZ method is described in, for example, Patent Document 1.
JP 2005-97049 A

  By the way, in the CZ method, in order to form the silicon melt M in the crucible 51, first, as shown in FIG. 8A, a bulk material silicon S is loaded in the crucible 51 and melted by heating the heater 52. Do the work. As shown in FIG. 8B, the raw silicon S gradually becomes a melt M by this heating process.

However, even if most of the raw material silicon S is melted and the melt M is generated in the crucible 51, the raw material silicon S does not melt on the inner peripheral surface of the crucible 51 as shown in FIG. The amount of heating of the heater 52 (current supplied to the heater 52) had to be increased in order to remain melted and completely melt.
As a result, there is a problem that the crucible 51 is deformed and the melting time is extended, and the operation efficiency is lowered.

  The present invention has been made under the circumstances as described above. In a single crystal pulling apparatus that pulls a silicon single crystal from a crucible by the Czochralski method, the raw material silicon melting time is shortened and the operation efficiency is improved. An object of the present invention is to provide a single crystal pulling apparatus and a method for manufacturing a single crystal.

In order to solve the above problems, a single crystal pulling apparatus according to the present invention is a single crystal pulling apparatus that melts raw silicon with a crucible in a furnace and pulls the single crystal from the crucible by the Czochralski method. A rotating means for rotating the crucible around a vertical axis; a radiation shield for shielding radiation heat to the single crystal; and a radiation shield for shielding the radiant heat from the single crystal; A supporting means that is supported from below, an elevating means that lifts and moves the radiation shield and releases the support by the supporting means, and a treatment treatment that is provided on the back surface of the radiation shield and is pivotable downward by its own weight. The processing jig is fixed to the back surface of the radiation shield in a state where the radiation shield is supported by the support means, Pivoted downward in a state where de is moved upward by the elevating means, characterized in that the sliding contact to the inner peripheral surface of the crucible which is rotated by said rotating means.
The processing jig is preferably made of plate-like quartz.

According to this structure, when the raw material silicon is melted, the processing jig can be rotated downward by sliding the radiation shield upward from the support means, and can be brought into sliding contact with the inner peripheral surface of the rotating crucible. .
For this reason, even if welding of the raw material silicon occurs on the inner peripheral surface of the crucible when the raw material silicon is melted, it can be removed by the processing jig.
Therefore, it is not necessary to increase the heating power of the heater in order to dissolve the raw material silicon as in the prior art, and the melting time can be shortened and the operation efficiency can be improved.
Further, deformation of the crucible due to an increase in the heating power of the heater can be avoided.

Further, it is desirable that the radiation shield includes a locking portion that engages with the processing jig rotated by its own weight, and the processing jig is fixed at a predetermined rotation position by the locking portion.
By providing the locking portion in this manner, the processing jig can be pressed against the inner peripheral surface of the crucible with an appropriate pressure.

  In order to solve the above-described problem, a method for producing a single crystal according to the present invention uses a single crystal pulling apparatus according to claim 1 or 2 to pull a single crystal from a crucible. In this manufacturing method, the raw material silicon is melted in a state in which the processing jig is rotated downward by moving the radiation shield upward and is in sliding contact with the inner peripheral surface of the rotating crucible. And a step of pulling the single crystal in a state where the radiation shield is supported by the support means and the processing jig is fixed to the back surface of the radiation shield.

By executing such steps, the welded silicon can be removed by the processing jig when the raw material silicon is melted, and the melting time can be shortened.
As a result, the entire operation time for pulling the silicon single crystal is shortened, and the operation efficiency can be improved.

  According to the present invention, in a single crystal pulling apparatus that pulls a silicon single crystal from a crucible by the Czochralski method, the single crystal pulling apparatus and single crystal that can shorten the raw material silicon melting time and improve the operation efficiency The manufacturing method can be obtained.

Embodiments of a single crystal pulling apparatus and a single crystal manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of a single crystal pulling apparatus 1 according to the present invention.
This single crystal pulling apparatus 1 includes a furnace body 2 formed by superposing a pull chamber 2b on a cylindrical main chamber 2a, a crucible 3 provided in the furnace body 2, and a semiconductor loaded in the crucible 3. And a heater 4 for melting the raw material M. A heat retaining member 13 is provided around the heater 4 along the inner wall of the main chamber 2a in order to effectively apply the heat of the heater 4 to the crucible 3. The crucible 3 has a double structure, and the inner side is constituted by a quartz glass crucible 3a and the outer side is constituted by a graphite crucible 3b.

  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 crystal P is attached to the tip of the wire 5b and pulled up while growing the single crystal C.

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 crucible 3, and extra radiant heat from the heater 4 or the like is applied to the growing single crystal C. A radiation shield 6 is provided so as not to give it.
The radiation shield 6 is formed by a horizontal annular portion 6a on the outside and an inclined annular portion 6b on the inside, and the inclined annular portion 6b is inclined linearly downward in the center direction as shown in the figure.

The radiation shield 6 is configured to be movable up and down by winding and rewinding the wire 7a (lifting means) by the lifting drive unit 7 (lifting means).
That is, when the raw material silicon is melted, the radiation shield 6 is disposed so as to move upward above the crucible 3, and when the single crystal is pulled up, the lower end thereof is disposed within the crucible 3, as shown in FIG. . Further, when pulling up the single crystal, the radiation shield 6 is supported by placing the horizontal annular portion 6 a on the support member 14 (support means) provided at the upper end of the heat retaining member 13.

Further, the radiation shield 6 will be described with reference to FIGS. FIG. 2 is a plan view of the radiation shield 6, and FIG. 3 is a partially enlarged view of the radiation shield 6.
As shown in FIGS. 2 and 3, a processing jig having a predetermined width in the circumferential direction on the back side of the radiation shield 6 and extending in the radial direction along the horizontal annular portion 6a and the inclined annular portion 6b. 15 is provided. The processing jig 15 is a plate-like body having a predetermined thickness, and the material thereof is quartz.

Further, the processing jig 15 is rotatably provided by its own weight by a support shaft 6c formed on the lower surface of the horizontal annular portion 6b. However, as shown in FIG. In the state of being placed on top, the radiation shield 6 is configured to be in close contact with and fixed to the back surfaces of the horizontal annular portion 6a and the inclined annular portion 6b.
That is, when the radiation shield 6 is placed on the support member 14, the processing jig 15 that rotates downward about the support shaft 6 c is pushed up by the support member 14, and the horizontal annular portion 6 b and the support member 14. It is fixed in a state sandwiched between and.

  On the other hand, when the raw material silicon S is melted, the radiation shield 6 is moved above the crucible 3 by the elevating drive unit 7. At this time, the processing jig 15 is not supported by the support member 14. As shown in FIG. 3 (b), it rotates downward by its own weight, and a predetermined region including its tip is brought into contact with the inner surface of the quartz glass crucible 3a.

That is, when the raw material silicon is melted, the crucible 3 is rotated so that the processing jig 15 is in sliding contact with the inner peripheral surface of the rotating crucible 3.
A locking portion 6d that engages with the rear end of the rotated processing jig 15 and restricts the degree of rotation of the processing jig 15 at the peripheral edge of the horizontal annular portion 6a provided with the processing jig 15. Is formed.

  Further, as shown in FIG. 1, the single crystal pulling apparatus 1 includes a heater control unit 9 that controls the amount of power supplied to the heater 4 that controls the temperature of the silicon melt M, and a motor 10 that rotates the quartz glass crucible 3 ( Rotation means) and a motor control unit 10a for controlling the rotation speed of the motor 10. Furthermore, a lifting device 11 for controlling the height of the quartz glass crucible 3, a lifting device control unit 11a for controlling the lifting device 11, a wire reel rotating device control unit 12 for controlling the pulling speed and the number of rotations of the grown crystal, It has. Each of these control units 9, 10 a, 11 a, 12 and the raising / lowering drive unit 7 are connected to an arithmetic control device 8 b of a computer 8.

In the single crystal pulling process using the single crystal pulling apparatus 1 configured as described above, first, a raw material silicon M melting process is performed.
A predetermined inert gas flow is formed in the furnace body 2, and the raw material silicon S 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 S of the crucible 3 is started. Is done.
When the raw material silicon S is melted, the drive of the motor 10 is controlled by the motor control unit 10a, and the crucible 3 rotates at a predetermined rotation speed.

Here, as shown in FIG. 4, the radiation shield 6 is disposed above the crucible 3, whereby the processing jig 15 is rotated downward, and a predetermined region including the tip thereof slides on the inner peripheral surface of the quartz glass crucible 3b. It will be in contact.
That is, even if the predetermined region of the processing jig 15 is in sliding contact with the inner peripheral surface of the quartz glass crucible 3b and the raw silicon S is welded to the inner peripheral surface of the crucible as shown in FIG. All is removed and dropped into the melt M.

When the silicon melt M is generated in this way, 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 attached to the wire 5b is brought into contact with the silicon melt M, and necking for melting the tip of the seed crystal P is performed to form the neck portion P1.

  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.

As described above, according to the embodiment of the present invention, when the raw material silicon is melted, since the radiation shield 6 is not supported by the support member 14, the processing jig 6 is rotated downward and rotated. The crucible 3 is in sliding contact with the inner peripheral surface of the crucible 3.
For this reason, even if welding of the raw material silicon occurs on the inner peripheral surface of the crucible 3 when the raw material silicon is melted, it is removed by the processing jig 6 and dropped into the melt M.
Therefore, it is not necessary to increase the heating power of the heater 4 in order to dissolve the raw material silicon as in the prior art, and the raw material silicon melting time can be shortened and the operation efficiency can be improved.
Further, deformation of the crucible 3 due to an increase in heating power of the heater 4 can be avoided.

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

In this experiment, a silica glass crucible with a diameter of 24 inches was filled with 150 g of raw silicon (polycrystalline silicon), and a melting experiment using the same processing jig as in the above embodiment was performed 10 times.
As a result of the experiment, welded silicon was generated on the inner peripheral surface of the crucible 3 times out of 10 times, but it could be completely removed by the processing jig.
Conventionally, although it took 8 hours on average to completely melt 150 kg of raw material silicon, the melting time was shortened on average 30 minutes in 10 experiments because no treatment to dissolve the deposited silicon was required.
Further, since it is not necessary to increase the heating power of the heater, the crucible was not deformed.

  From the experimental results of the above examples, by using the single crystal pulling apparatus of the present invention, it is possible to remove the raw silicon deposited on the inner peripheral surface of the crucible without increasing the heating power of the heater (increasing the current). It was confirmed that the raw material silicon could be melted in a short time.

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

FIG. 1 is a block diagram schematically showing the configuration of a single crystal pulling apparatus according to the present invention. FIG. 2 is a plan view of a radiation shield provided in the single crystal pulling apparatus of FIG. FIG. 3 is a partially enlarged view of a radiation shield provided in the single crystal pulling apparatus of FIG. FIG. 4 is a view for explaining a state when raw material silicon is melted in the single crystal pulling apparatus of FIG. FIG. 5 is a diagram for explaining a state at the time of single crystal pulling in the single crystal pulling apparatus of FIG. 1. FIG. 6 is a diagram for explaining a pulling method using the conventional CZ method. FIG. 7 is a diagram for explaining formation of a neck portion in a pulling method using a conventional CZ method. FIG. 8 is a diagram for explaining a state at the time of melting a conventional raw material silicon.

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 6 Radiation shield 6d Locking part 7 Lifting drive part (lifting means)
7a Wire (elevating means)
8 Computer 8a Storage device 8b Arithmetic storage device 10 Motor (rotating means)
10a Motor control unit 14 Support member (support means)
15 Processing jig C Single crystal M Silicon melt P Seed crystal P1 Neck part S Raw material silicon

Claims (4)

In a single crystal pulling apparatus that melts raw silicon with a crucible in a furnace and pulls a single crystal from the crucible by the Czochralski method,
Rotating means for rotating the crucible around a vertical axis, an upper and lower openings are formed so as to surround the periphery of the single crystal above the crucible, and a radiation shield for shielding radiation heat to the single crystal; and the radiation shield below A support means for supporting the radiation shield, an elevating means for lifting and moving the radiation shield and releasing the support by the support means, and a processing jig provided on the back surface of the radiation shield and rotatably provided by its own weight. And
The processing jig is fixed to the back surface of the radiation shield in a state where the radiation shield is supported by the support means, and rotates downward with the radiation shield being lifted and moved by the elevating means. A single crystal pulling apparatus, wherein the single crystal pulling apparatus is brought into sliding contact with an inner peripheral surface of the crucible rotated by the step.   The single crystal pulling apparatus according to claim 1, wherein the processing jig is made of plate-like quartz. The radiation shield includes a locking portion that engages with the processing jig rotated by its own weight,
The single crystal pulling apparatus according to claim 1, wherein the processing jig is fixed at a predetermined rotation position by the locking portion. In the method for producing a single crystal using the single crystal pulling apparatus according to any one of claims 1 to 3, wherein the single crystal is pulled from the crucible.
Melting the raw material silicon in a state in which the processing jig is rotated downward by moving the radiation shield upward and is in sliding contact with the inner peripheral surface of the crucible rotating the processing jig;
And a step of pulling up the single crystal in a state where the radiation shield is supported by the support means and the processing jig is fixed to the back surface of the radiation shield.

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