JPS63303888A - Single crystal growth device - Google Patents

Abstract

PURPOSE:To stably grow a single crystal without the break caused by resonance by providing a vertically movable wire winder above a pull chamber through a vacuum bellows and adjusting the effective length of wire according to the number of revolutions of seed crystal. CONSTITUTION:The seed crystal 16 is soaked in a multiple crystal molten liquid 14 in a crucible 13, and the single crystal 18 is pulled up to the grown while being revolved to the direction shown by arrow A by a wire 15 wound with a wire winder 31 provided above the pull chamber 11. In the above- mentioned single crystal growth device 30, the wire winder 31 is connected to the pull chamber 11 with a vacuum bellows 40 between so as to be capable of vertical movement. The wire winder 31 is ascended and descended by the vertical movement of a frame 32 provided with an elevator mechanism 34 along a supporting pillar 33. By this movement, the effective length of wire 15 is adjusted according to the number of revolutions of the seed crystal 16 to avoid the resonance state. By this method, the simple crystal 18 is stably grown without the break of neck part.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a single crystal growth apparatus in which the effective length of the wire can be changed appropriately in accordance with the rotation speed of the seed crystal by configuring the wire winding section to be able to rise and fall. The length is such that a resonance phenomenon does not occur, and the single crystal can be grown stably without the risk of breakage at the neck portion.

[Industrial application field]

The present invention relates to a single crystal growth apparatus, and particularly to a single crystal growth apparatus using the Czochralski method.

One of the characteristics of single crystals is stacking faults (oxydation).
Stacking Fault; O3 has density.

A crystal processing technique called intrinsic gettering is sometimes used in wafer processing. In the case of 9, a certain level of stacking fault density is required within the single crystal. Here, the stacking fault density required differs depending on the IC to be manufactured and, in some cases, depending on the user.

Therefore, it is necessary to grow a single crystal having a predetermined stacking fault density.

According to the growth method using the Czochralski method, it is said that the crystal rotation number Re is related to the stacking fault density. However, by conducting repeated experiments, the present inventor has determined that the relationship between the crystal rotation number Rc and the stacking fault density is , the line Ir in Figure 4
It was confirmed that there is a relationship shown.

When growing a single crystal with a stacking fault density of Dl, it is necessary to set the crystal rotation speed to Rc+.

In FIG. 5, 1 is a seed crystal and 2 is a wire.

By rotating the upper end of the wire 2 in the six directions of arrows RC+, the seed crystal 1 is rotated in the same direction.

At this time, the seed crystal 1 and the wire 2 become a pendulum 3,
The seed crystal 1 draws a circle with a radius (swing) r centered on the vertical axis 4, and the wire 2 makes a conical pendulum motion, drawing a cone centered on the vertical axis 4. The frequency of the conical camera movement is Rc+
It is.

On the other hand, the photographer 3 has a natural frequency f. natural frequency f
is expressed by the following equation.

Here, 9 is the gravitational constant, and 2 is the effective length of the wire 2.

When the above-mentioned frequency Rc+ coincides with the eigenvalue frequency f, the pendulum 3 enters a resonant state, the swing r increases, and single crystal growth becomes substantially impossible.

Therefore, in manufacturing a single crystal ingot, it is necessary to suppress the runout r.

Here, since the crystal rotation speed Rc+ cannot be changed due to the relationship with the stacking fault density, it is necessary to suppress the above-mentioned swing r to a small value without changing the crystal rotation speed Rc+.

[Conventional technology]

The configuration of a conventional single crystal growth apparatus is shown in FIG.

In the figure, 10 is a furnace body, and 11 is a pull chamber.

Reference numeral 12 denotes a wire winding section, which is provided at the upper part of the pull chamber 11.

A crucible 13 is provided inside the furnace body 10, and polycrystalline silicon is heated and melted therein. 14 is a silicon polycrystalline melt.

15 is a wire, and 16 is a seed crystal suspended from the wire 15.

17 is a drum, which rotates in the direction of arrow B and carries the wire 15.
It winds up and rotates in the six directions of the arrow.

The seed crystal 16 rises while rotating, and the silicon single crystal 18 is grown and pulled into the pull chamber 11.

Reference numeral 19 denotes a photographic prevention member, which is provided in the pull chamber 11 so as to be movable up and down while being guided by the inner peripheral surface thereof. This member 19 has a ring 19a in the center, and the wire 15 passes through the ring 19a.

Further, the member 19 is initially located at the lower end of the pull chamber 11 as shown in FIG. 6, and moves upward as the single crystal 18 is pulled.

The vicinity of the lower end of the wire 15 is restricted to the center of the pull chamber 11 by the ring 19a, and the seed crystal 16 rises while its deflection is restricted, and the single crystal 18 is grown.

[Problem that the invention seeks to solve]

Depending on the rotation speed of the drum 17 in the direction of arrow A, the seed crystal 1
A resonance phenomenon may occur in which the vibration frequency of the swing of the pendulum 20 coincides with the natural frequency of the pendulum 20 formed by the wire 15 and the seed crystal 16.

In this case, the seed crystal 16 and the single crystal 18 try to make a large conical pendulum movement, and a force acts to swing them outward.

Since the swing of the single crystal 18 is forcibly restricted by the ring 19a when centrifugal force is acting on the single crystal 18 in this way, the load on the neck portion 18a of the single crystal 18 is increased, causing the neck portion 18a of the single crystal 18 to break. There was a serious problem in that accidents could occur.

Further, the anti-shake member 19 is slidably provided within the pull chamber 11, and there is also the problem that the structure is complicated.

[Means for solving problems]

In the present invention, a seed crystal at the tip of a wire is immersed in a raw material melt in a crucible, the wire is wound up by a wire winding section above a pull chamber, and the seed crystal is pulled up while rotating to grow a single crystal. In the apparatus, a vacuum bellows is provided between the pull chamber and the wire winding section to enable the wire winding section to move up and down, and the seed crystal is provided in order to determine the effective length of the wire so as to avoid a resonance condition. The structure includes means for raising and lowering the wire winding section according to the number of rotations.

[Effect]

The vacuum bellows allows the wire take-up to be raised and lowered while maintaining a vacuum within the pull chamber.

The elevating means changes the effective length of the wire by elevating and lowering the wire winding section.

The effective length of the wire is determined to avoid resonance conditions.

As a result, no matter what value the number of rotations of the seed crystal is set, resonance phenomena can be avoided, and the single crystal can be grown stably without the risk of breaking at the neck portion.

〔Example〕

FIG. 1 shows a single crystal manufacturing apparatus 2230 according to an embodiment of the present invention.
shows. FIG. 2 shows the state when the effective length of the wire is changed. In each figure, parts corresponding to those shown in FIG. 6 are designated by the same reference numerals, and their explanations will be omitted.

31 is a wire winding section, which is supported by a U-shaped frame 32.

The frame 32 is fitted onto a column 33 and is moved up and down along the column 33 by a hydraulically driven lifting mechanism 34 .

The wire winding section 31 includes a rotating section 31a and a non-rotating section 31b.
Therefore, a magnetic seal 35 is provided to maintain a vacuum state between the two.

The rotating part 31a is an upper arm part 32a of the frame 32.
It is rotatably supported at the tip of the A drum 17 is provided within the rotating portion 31a. The non-rotating part 31b is the frame 3
It is fixed to the lower arm part 32b of 2. The rotating part 31a is rotated in the direction of the arrow by a motor 36 attached to the non-rotating part 31b via a gear mechanism 37, and the internal drum 17 is also rotated in the same direction.

40 is a vacuum bellows, which is provided between the lower non-rotating part 31b of the wire winding part 31 and the pull chamber 11, and is expandable and retractable.

As can be seen from the above, the frame 3 is
2 moves up and down in the direction of arrow X+ and X2, and the wire winding section 3
1 moves up and down with the expansion and contraction of the vacuum bellows 4o and while keeping the inside of the pull chamber 11 and the furnace body 10 in vacuum, and the effective length of the wire 16 is varied.

Note that the photograph prevention member 19 shown in FIG. 6 is not provided.

Next, the operation of the above device 30 will be explained.

First, a case will be described in which a single crystal with a stacking fault density of D+ is grown.

In this case, based on FIG. 4, the wire winding portion 31 is
is rotated in the direction of arrow A, and the drum 17 is also rotated in the direction of arrow B. The wire 17 is wound around the drum 17 while rotating, and the seed crystal 16 and the grown single crystal 18 are pulled up while rotating at a rotation speed Rc+ in the direction of the arrow.

As a result of experiments, the present inventor has confirmed that the above-mentioned resonance phenomenon occurs only in the initial stage of pulling a single crystal.

Therefore, the effective length of the wire at the initial stage of pulling is determined by the natural frequency f of the pendulum 20, which is determined by the crystal rotation speed R.
The length is determined so that it does not match the frequency Rc+ of the seed crystal 16 generated by c+.

FIG. 2 shows the case where the effective length of the wire is increased to 21 and the natural frequency f is lowered so that f<Rc+.

That is, by driving the elevating mechanism 34, the frame 32 rises in the direction of arrow X1 along the support column 33, and the wire winding section 3
1 rises while stretching the vacuum bellows 40. This increases the effective length of the wire to 21.

This avoids a resonance state, and the seed crystal 16 is pulled up with a small deflection. As a result, single crystal 1
8 grows stably without the risk of breakage at its neck portion 18a, and a single crystal 18 having a small change in diameter and a desired stacking fault density D+ is obtained.

Note that even if the effective length of the wire 15 is changed, the pull chamber 1
1 and the inside of the furnace body 1o both maintain a vacuum state.

Moreover, contrary to the above, as shown in FIG.
The frame 32 is lowered, the wire winding part 31 is lowered in the x2 direction of the arrow, and the effective length of the wire 15 is shortened to 22.
Resonant drums can also be avoided by increasing the natural frequency f of the pendulum 20 so that f>Rc+.

In this case as well, the single crystal 18 is grown stably without the risk of breakage, as in the above case.

Further, the operation when manufacturing a single crystal with stacking fault density D2 will be explained.

In this case, according to FIG. 4, the crystal rotation speed Rc is set to RC2.
(See FIG. 1) The effective length of the wire is determined so that the natural frequency of the photographic element deviates from the vibration frequency of the vibration due to rotation of the seed crystal at the rotation speed RC2.

As a result, a single crystal is manufactured in a state where a resonance state is avoided.

In addition, the present inventor has experimentally determined that the crystal rotation speed is 20 rp.
m, the effective length of the wire is 200c! ! i and the crystal rotation speed is 30 rom.
It was confirmed that a resonance state occurs when the effective length of the wire is 150. Therefore, the crystal rotation number is 20
rpm, the wire winding portion 31 may be set at a height such that the effective length of the wire is, for example, 250 cta. When the crystal rotation speed is 30 ram, the wire winding portion 31 may be set at a height such that the effective length of the wire is, for example, 200 mm.

[Effects of the Invention] According to the present invention, since the effective length of the wire can be changed, it is possible to avoid the occurrence of a resonance phenomenon even when the rotation speed of the seed crystal is set to any value, and the desired length can be changed. It is possible to stably grow a single crystal having a stacking fault density of 100 mL without the risk of breakage at the neck portion.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a single crystal growth apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing a state in which the effective length of the wire is lengthened in the apparatus of FIG. 1, and FIG. 3 is a diagram similar to that shown in FIG. Figure 4 is a diagram showing the relationship between stacking fault density and crystal rotation speed, Figure 5 is a diagram explaining the conical pendulum motion of the seed crystal, FIG. 6 is a diagram showing a conventional single crystal growth apparatus. In the figure, 10 is a furnace body, 11 is a pull chamber, 13 is a crucible, 14 is a polycrystalline silicon melt, 15 is a wire, 16 is a seed crystal, 17 is a drum, 18 is a silicon single crystal, 18a is a neck part, 20 is a A pendulum, 30 is a single crystal growth device, 31 is a wire winding part, 31a is a rotating part, 31b is a non-rotating part, 32 is a frame, 33 is a column, 34 is a hydraulically driven lifting mechanism, 35 is a magnetic seal, 36 is a 37 is a gear mechanism, and 40 is a vacuum bellows. Sake early crystal beniou 1 30 meals & I be long bag 1 distorted and active groaning quantity broom 1 figure Oze 5 wise 1;
Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A seed crystal at the tip of a wire is immersed in a raw material melt in a crucible, the wire is wound up by a wire winding section above a pull chamber, and the seed crystal is pulled up while rotating;
In the apparatus for growing a single crystal, the pull chamber (11) and the wire winding section (31) are provided.
), and in order to determine the effective length of the wire so as to avoid a resonance state, a vacuum bellows (40) is provided between the A single crystal growth apparatus characterized by being provided with means (32, 33, 34) for raising and lowering a winding section.