JP2011037681A - Method for stopping rotation of crystal and apparatus for stopping rotation of crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stopping rotation of a crystal, by which rotation of a grown crystal can be safely stopped while preventing wire cut or breakage of a wire rope in the production of a single crystal by Czochralski method. <P>SOLUTION: The method aims to stop rotation of a pulled crystal 16 when the single crystal 16 is produced by bringing a seed crystal 17 attached to the tip of a wire rope 19 into contact with a melt 13 of a raw material substance and pulling the seed crystal 17 while rotating, wherein rotation of the single crystal 16 is stopped by reducing the crystal rotation speed at an angle deceleration rate of not more than 0.53 rad/s<SP>2</SP>, when the crystal is rotated under the condition satisfying at least one of a rotation moment M of the wire rope 19 of M&ge;23.5 N&times;mm and a rotation angle &theta; of the wire rope 19 of &theta;&ge;40&deg;. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for stopping rotation of a grown single crystal and an apparatus for stopping rotation of a single crystal in the production of a single crystal by the Czochralski method.

  Conventionally, when a single crystal is produced by the Czochralski method (CZ method, MCZ method) in which a seed crystal is brought into contact with a melt of a raw material substance in a crucible and the seed crystal is rotated and pulled to grow a single crystal, There was no control of stopping the rotation of the pulled crystal.

  However, the present inventor has examined the stopping of crystal rotation. When the rotation of the wire rope and the rotation angle are large when stopping the crystal rotation, the grown crystal is excessively applied to the suspended wire rope. It has been clarified that twisting and untwisting occur in the worst case, and in the worst case, the wire rope may be cut or broken and the pulled crystal may fall.

  Therefore, in the production of single crystals by the Czochralski method, it is necessary to develop a crystal rotation stopping method that can safely stop the rotation of the grown crystal while preventing the wire rope from being broken or broken. there were. It has also been demanded to develop an apparatus for safely stopping the rotation of the grown crystal.

An object of the present invention is to advantageously solve the above-mentioned problems, and the crystal rotation stopping method of the present invention brings a seed crystal placed at the tip of a wire rope into contact with a melt of a raw material, When a single crystal is produced by pulling up while rotating the seed crystal, the rotation of the pulled crystal is stopped, and the rotation moment M of the wire rope is M: 23.5 N · mm or more (M ≧ 23.5 N · mm) ) And the rotation angle θ of the wire rope θ: 40 ° or more (θ ≧ 40 °), the crystal is rotated at an angular deceleration of 0.53 rad / s ² or less. The rotation speed is decreased to stop the rotation of the crystal. As described above, when the rotation moment M is 23.5 N · mm or more and when the rotation angle θ of the wire rope is 40 ° or more, the rotation speed of the crystal is 0.53 rad / s. If it is decreased at an angular deceleration of ² or less, the wire rope can be prevented from being broken or broken. Therefore, for example, when a heavy silicon ingot having a diameter of 450 mm is manufactured, rotation of the grown crystal can be safely stopped. If the wire rope rotation moment M is less than 23.5 N · mm (M <23.5 N · mm) and the wire rope rotation angle θ is less than 40 ° (θ <40 °), the crystal Since wire strand breakage and the like are unlikely to occur when rotation is stopped, the rotation of the crystal can be stopped by decreasing the crystal rotation speed at an arbitrary angular deceleration.

In the present invention, the rotation moment M of the wire rope can be calculated according to the following formula (I), and the rotation angle θ of the wire rope can be calculated according to the following formula (II).
M = α × W × sin (a _n ) (I)
θ = M × l / (Gr × Ip) (II)
Wherein, alpha is a constant, W is the mass of the crystal grown, a _n is twisted angle of wire rope, l is the wire rope length, Gr is modulus of transverse elasticity of the wire rope, Ip is the cross section of the wire rope two Next pole moment. ]

  Here, in the crystal rotation stopping method of the present invention, the angular deceleration is preferably constant.

The crystal rotation stopping device of the present invention brought the seed crystal placed at the tip of the wire rope into contact with the melt of the raw material, and pulled up while rotating the seed crystal to produce a single crystal. An apparatus for stopping the rotation of the crystal, the crystal mass measuring means for measuring the mass of the pulled crystal, the wire rope length measuring means for measuring the length of the wire rope hanging the pulled crystal, A calculation means for calculating the rotation moment M of the wire rope and the rotation angle θ of the wire rope using the mass of the crystal measured by the crystal mass measurement means and the length of the wire rope measured by the wire rope length measurement means; However, at least one of the rotation moment M: 23.5 N · mm or more (M ≧ 23.5 N · mm) and the rotation angle θ: 40 ° or more (θ ≧ 40 °). In the case of rotating under the condition satisfying the above condition, it is characterized by comprising crystal rotation stopping means for stopping the rotation of the crystal by decreasing the crystal rotation speed at an angular deceleration of 0.53 rad / s ² or less. As described above, when the rotation moment M is 23.5 N · mm or more and when the rotation angle θ of the wire rope is 40 ° or more, the rotation speed of the crystal is 0.53 rad / s. ^If a crystal rotation stopping means for stopping the rotation of the crystal by decreasing it at an angular deceleration of ² or less is provided, it is possible to prevent the wire rope from being broken or broken. Therefore, when the crystal rotation stopping device of the present invention is used, for example, when a heavy silicon ingot having a diameter of 450 mm is manufactured, rotation of the grown crystal can be stopped safely. If the wire rope rotation moment M is less than 23.5 N · mm (M <23.5 N · mm) and the wire rope rotation angle θ is less than 40 ° (θ <40 °), the crystal Since wire strand breakage and the like are unlikely to occur when rotation is stopped, the rotation of the crystal can be stopped by decreasing the crystal rotation speed at an arbitrary angular deceleration.

  According to the present invention, in the production of a single crystal by the Czochralski method, a crystal rotation stopping method capable of safely stopping the rotation of the grown crystal while preventing the wire rope from being cut or broken, and A crystal rotation stop device can be provided.

It is explanatory drawing which shows the structure of an example of the single crystal manufacturing apparatus which can apply the crystal rotation stop method of this invention. (A) is explanatory drawing which looked at a part of wire rope of the single-crystal manufacturing apparatus shown in FIG. 1 from the front, (b) is sectional drawing which follows the AA line of Fig.2 (a). . It is explanatory drawing explaining the structure of the wire rope rotation mechanism of the single crystal manufacturing apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, an example of a single crystal manufacturing apparatus to which the crystal rotation stopping method of the present invention can be applied is a cylindrical silicon ingot having a diameter of 450 mm, for example. )), A crucible 12 for containing polycrystalline silicon as a raw material of single crystal silicon in a chamber 11 and a crucible 12 as shown in FIG. A crucible rotating to rotate the heater 14 for heating the raw material in the inside into a melt 13 and the crucible 12 provided in the lower part of the crucible 12 in the circumferential direction (clockwise as viewed from above the apparatus in FIG. 1). A wire rope 19 having a mechanism 15 and a seed crystal holder (seed chuck) 18 for holding a seed crystal 17 for growing a single crystal 16 attached to the tip; Winding the ear rope 19 in a direction opposite to the direction of rotation of the crucible 12 (counterclockwise in FIG. 1 when viewed from above the apparatus) to rotate the single crystal 16, the seed crystal 17 and the seed crystal holder 18. And a crystal rotation / pull-up mechanism 20 that pulls up while pulling.

Here, the wire rope 19 has, for example, a concentric twisted structure twisted angle a _n as shown in FIG. 2 (a). Specifically, the wire rope 19 is surrounded by a single core wire 23 (wire diameter: d) as shown in FIG. 2 (b) as a cross-section along the line AA in FIG. 2 (a). And 6 strands 24 (strand diameter: d) are twisted together.

  The crystal rotation / lifting mechanism 20 includes a wire rope winder 21 that winds the wire rope 19 to pull up the single crystal 16, the seed crystal 17, and the seed crystal holder 18, and the wire rope winder 21 installed therein. The wire rope rotating mechanism 25 (not shown in FIG. 1) as shown in FIG. 3, which rotates the housing 22 to rotate the wire rope 19, and the wire rope rotation speed and the crystal pulling distance are detected. Detection means (not shown).

  Here, a detection means consists of encoders, for example, and can detect the rotation speed of a wire rope and the distance which pulled up the crystal.

  The wire rope rotation mechanism 25 rotates the housing 22 by transmitting the rotation output of the power source (motor 28) to the housing 22 via the rotation shaft of the housing 22, and the wire rope 19 (housing) Rotation speed control means 26 for controlling the rotation speed of 22) is provided. Here, since the wire rope rotating mechanism 25 is provided with an uninterruptible power supply (UPS) 32 that can supply power even in the event of a power failure, the device does not stop suddenly even in the event of a power failure. The rotation speed control means 26 and the detection means also function as wire rope length measurement means, calculation means, and crystal rotation stop means of the crystal rotation stop device of the present invention when stopping the rotation of the grown crystal.

  The rotation speed control means 26 includes a motor 28 whose rotation is controlled by a controller 27, an input pulley 29 that receives the rotation of the motor 28, an output pulley 30 that outputs the rotation to the rotation shaft of the housing 22, and an input pulley. 29 and a belt 31 wound around the output pulley 30. Then, the rotation of the motor 28 that operates at the number of rotations determined by the controller 27 is transmitted to the rotation shaft of the housing 22 through the input pulley 29, the belt 31, and the output pulley 30, so that the housing 22 (wire The rotational speed of the rope 19) is controlled by the rotational speed control means 26.

  Here, in the single crystal manufacturing apparatus 10, the seed crystal 17 installed at the tip of the wire rope 19 is brought into contact with the raw material melt 13 in the crucible 12, and the seed crystal 17 is rotated in the circumferential direction at 10 rpm, for example. The single crystal silicon 16 is manufactured by pulling up. The crystal rotation speed at the time of crystal pulling is controlled by controlling the rotation speed of the wire rope 19 by the rotation speed control means 26. That is, the crystal rotation speed can be regarded as the same as the rotation speed of the wire rope 19. The crystal can be pulled by winding the wire rope 19 with the wire rope winder 21 of the crystal rotation / pickup mechanism 20, and the winding amount of the wire rope 19 (distance where the crystal is pulled) is: As described above, the detection can be performed using the encoder as the detection means.

  Then, the crystal pulled up while rotating as described above is stopped from rotating as follows in a state of being separated from the melt.

  First, the mass W of the crystal pulled up by a crystal mass sensor (not shown) as crystal mass measurement means is measured, and the winding amount l 'of the wire rope 19 is detected by an encoder (detection means). Then, the information on the mass W and the winding amount l ′ is sent to the controller 27, and the controller 27 suspends the pulled crystal by subtracting the winding amount l ′ from the total length L of the wire rope 19. The length l (l = L−l ′) of the wire rope is obtained. That is, the encoder and controller 27 functions as a wire rope length measuring unit.

Next, in the controller 27 that also functions as a calculation means, the rotation moment M and the rotation angle θ of the wire rope 19 are calculated using the crystal mass W and the wire rope length l.
Here, the crystalline mass: W, the effective cross-sectional area of the wire rope: A (in the present embodiment, since the wires of the seven ^{7 × (d / 2) 2} π), of the wire rope strands angle: and a _n Then, the tensile stress σ of the wire rope is
σ = W / A
The vertical load W _n of the wire rope is
W _n = σ × A × cos (a _n )
The rotation force T of the wire rope is
T = W _n × tan (a _n )
It becomes.
Accordingly, when the rotation moment M of the wire rope is constant: α and moment radius: R (wire rope radius: D / 2), the controller 27 represents the following formula:
M = α × T × R = α × W × sin (a _n )
Can be used to calculate.
In addition, the rotation angle θ of the wire rope is expressed by the following formula in the controller 27 when the transverse elastic modulus of the wire rope is Gr, the cross-sectional secondary pole moment of the wire rope is Ip, and the length of the wire rope is l.
θ = M × l / (Gr × Ip)
Can be used to calculate.
The cross-sectional secondary pole moment Ip of the wire rope is given by the following formula when the wire diameter is d and the constant is determined by the twisted configuration of the wire rope: γ.
^{Ip = γ × π × d 4} /32
Can be expressed as

When the pulled crystal is rotated under a condition satisfying at least one of the rotation moment M ≧ 23.5 N · mm and the rotation angle θ ≧ 40 °, the angle reduction is 0.53 rad / s ² or less. The crystal rotation speed is decreased by the rotation speed control means 26 so that the rotation speed is reached (the controller 27 controls the rotation speed of the motor 28), and the rotation of the crystal is stopped. On the other hand, when the pulled crystal is rotated under the condition that the rotation moment M <23.5 N · mm and the rotation angle θ <40 °, the rotation speed control means 26 can rotate the crystal at an arbitrary angular deceleration. The rotation speed is decreased to stop the rotation of the crystal. Here, the rotation speed control means 26 functions as crystal rotation stopping means. The angular deceleration is a negative acceleration, that is, a rate of decrease of the angular velocity per unit time. In the present invention, it is preferable to decrease the crystal rotation speed with a constant angular deceleration.

  Thus, in the single crystal manufacturing apparatus 10, the crystal mass sensor, encoder, controller and rotation speed control means function as a crystal rotation stop device, and the crystal rotation is stopped in consideration of the rotation moment M and the rotation angle θ of the wire rope 19. By doing so, it is possible to prevent the wire rope 19 from being broken and shorten the life of the wire rope 19, and to prevent the wire rope 19 from being broken and to safely stop the crystal rotation.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.

Example 1
In the single crystal manufacturing apparatus, the rotation speed M of the wire rope M = 69.6 N · mm, the rotation speed θ of the wire rope θ = 86 °, the crystal rotation speed of the silicon single crystal rotating is reduced to 0.52 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Comparative Example 1)
In the single crystal manufacturing apparatus, the rotational speed of the wire rope is M = 69.6 N · mm, the rotation speed of the wire rope is θ = 86 °, and the crystal rotation speed of the silicon single crystal is reduced by an angular deceleration of 0.58 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, the wire was broken.

(Comparative Example 2)
In the single crystal manufacturing apparatus, the rotational speed of the silicon single crystal rotating at the wire rope rotation moment M = 69.6 N · mm and the wire rope rotation angle θ = 86 ° is the angular deceleration 1.05 rad / s ^2. The wire rope was broken when it was attempted to stop the rotation of the crystal.

(Reference Example 1)
In the single crystal manufacturing apparatus, the rotation speed M of the wire rope is M = 13.9 N · mm, the rotation speed of the wire rope is θ = 17 °, and the crystal rotation speed of the silicon single crystal is reduced by an angular deceleration of 0.73 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Reference Example 2)
In the single crystal manufacturing apparatus, the rotation rate of the wire rope is M = 13.9 N · mm, the rotation rate of the wire rope is θ = 17 °, and the crystal rotation speed of the silicon single crystal is 1.05 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Reference Example 3)
In the single crystal manufacturing apparatus, the rotation speed M of the wire rope is M = 13.9 N · mm, the rotation speed of the wire rope is θ = 17 °, and the crystal rotation speed of the silicon single crystal is 1.57 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Example 2)
In the single crystal manufacturing apparatus, the rotation rate of the wire rope is M = 164.2 N · mm, the rotation rate of the wire rope is θ = 46 °, and the crystal rotation speed of the silicon single crystal is 0.05 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Example 3)
In the single crystal manufacturing apparatus, the rotation speed of the wire rope is M = 164.2 N · mm, the rotation speed of the wire rope is θ = 46 °, and the crystal rotation speed of the silicon single crystal is reduced by 0.52 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Comparative Example 3)
In the single crystal manufacturing apparatus, the rotation speed of the wire rope is M = 23.5 N · mm, the rotation speed θ of the wire rope is θ = 29 °, and the crystal rotation speed of the silicon single crystal is reduced by 0.58 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, the wire was broken.

(Reference Example 4)
In the single crystal manufacturing apparatus, the rotation speed of the wire rope is M = 23.0 N · mm, the rotation speed of the wire rope is θ = 29 °, and the crystal rotation speed of the silicon single crystal is 0.58 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

(Comparative Example 4)
In the single crystal manufacturing apparatus, the rotation speed of the wire rope is M = 23.0 N · mm, the rotation speed θ of the wire rope is θ = 40 °, and the crystal rotation speed of the silicon single crystal is reduced by an angular deceleration of 0.58 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, the wire was broken.

(Reference Example 5)
In the single crystal manufacturing apparatus, the rotation speed of the wire rope is M = 23.0 N · mm, the rotation speed of the wire rope is θ = 38 °, and the crystal rotation speed of the silicon single crystal is reduced by an angular deceleration of 0.58 rad / s ^2. The rotation of the crystal was stopped. When the state of the wire rope was visually observed after the rotation of the crystal was stopped, no wire breakage or the like occurred.

DESCRIPTION OF SYMBOLS 10 Single crystal production apparatus 11 Chamber 12 Crucible 13 Melt 14 Heater 15 Crucible rotation mechanism 16 Single crystal 17 Seed crystal 18 Seed crystal holder 19 Wire rope 20 Crystal rotation and pulling mechanism 21 Wire rope winder 22 Case 23 Core element Wire 24 Wire 25 Wire rope rotation mechanism 26 Rotational speed control means 27 Controller 28 Motor 29 Input pulley 30 Output pulley 31 Belt 32 Uninterruptible power supply

Claims (3)

A method of stopping the rotation of the pulled crystal when the single crystal is produced by bringing the seed crystal placed in contact with the melt of the raw material into contact with the tip of the wire rope and pulling the seed crystal while rotating.
The wire crystal rotation moment M: 23.5 N · mm or more (M ≧ 23.5 N · mm) and the wire rope rotation angle θ: 40 ° or more (θ ≧ 40 °). When rotating, the crystal rotation stopping method is characterized in that the rotation of the crystal is stopped by decreasing the crystal rotation speed at an angular deceleration of 0.53 rad / s ² or less.   2. The crystal rotation stopping method according to claim 1, wherein the angular deceleration is constant. A device that stops the rotation of the pulled crystal when the seed crystal placed at the tip of the wire rope is brought into contact with the melt of the raw material, and the seed crystal is pulled while rotating to produce a single crystal,
A crystal mass measuring means for measuring the mass of the pulled crystal;
Wire rope length measuring means for measuring the length of the wire rope that suspends the pulled crystal;
A calculation means for calculating the rotation moment M of the wire rope and the rotation angle θ of the wire rope using the mass of the crystal measured by the crystal mass measurement means and the length of the wire rope measured by the wire rope length measurement means;
The crystal rotates under conditions that satisfy at least one of the rotation moment M: 23.5 N · mm or more (M ≧ 23.5 N · mm) and the rotation angle θ: 40 ° or more (θ ≧ 40 °). A crystal rotation stopping means for stopping the rotation of the crystal by decreasing the crystal rotation speed at an angular deceleration of 0.53 rad / s ² or less,
A crystal rotation stopping device comprising:

Images