KR101494527B1 - Method for optimizing crucible rotation for high quality silicon single crystal growing and high durability crucible - Google Patents

Abstract

The present invention relates to a crystal growth method of immersing a single crystal seed in a crucible containing polysilicon melt and rotating the crucible at 8 rpm to 10 rpm to grow single crystal silicon into an ingot, The oxygen concentration can be reduced and the oxygen concentration introduced into the single crystal silicon can be controlled. According to the present invention, it is possible to grow a high-quality single crystal by reducing the oxygen concentration introduced into the ingot, and in particular to prevent bubble expansion on the inner wall of the crucible.

Description

TECHNICAL FIELD The present invention relates to a crucible rotation speed optimization method for high-quality silicon single crystal growth and crucible life extension,

The present invention relates to a crucible rotation speed optimization method for growing a high quality silicon single crystal and preventing the expansion of a crucible bubble, and more particularly, to a crucible rotation speed optimization method for reducing a crucible rotation speed among various process parameters for determining whether a high quality single crystal is grown in a body growth process, And a method for optimizing a crucible rotation speed for reducing bubbles on the inner wall of a crucible generated by oxygen.

In general, a method of growing monocrystalline silicon into an ingot form includes a czochralski (CZ) method or a floating zone (FZ) method.

In the Czochralski method, polysilicon is heated and melted in a quartz crucible, a seed of monocrystal silicon is immersed in a melt, and the silicon single crystal is grown by rotating it at a predetermined speed while rotating it . The single crystal silicon ingot thus manufactured is subjected to processes such as slicing, lapping, etching, cleaning, and polishing to complete the production of the silicon wafer.

In order to grow monocrystalline silicon, polysilicon is melted. This process is called melting, and the molten polysilicon is called melt. These melts are liquids, and their internal convection and melting states are important factors in the subsequent process of contacting the seeds and pulling the single crystal.

In addition, when the ingot rises, the uniformity of the melt can not be ensured, and the melt is deposited on the inner wall of the crucible, thereby causing a process loss. For this reason, after the melting process is completed, the melt stabilization process proceeds. At this time, the crucible is rotated to homogenize the melt in the crucible.

The homogenization and stabilization of the melt convection affects the internal temperature change of the single crystal growing apparatus. When the temperature is high or low, it is disadvantageous to the ingot growth. Therefore, the control of the melt is important in order to maintain the melt convection constantly and appropriately .

Particularly, oxygen and other precipitates, which are increased by friction between the inner wall of the quartz crucible and the melt convection, migrate to the center of the crucible and adversely affect the growth of the silicon single crystal.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method for optimizing crucible rotation speed for high-quality silicon single crystal growth in a body process.

Another object of the present invention is to provide a method for stabilizing the convection of melt by controlling the quartz crucible rotation speed without using a magnet.

Yet another object of the present invention is to provide a method for minimizing the occurrence of bubbles on the crucible inner wall due to the reduction of crucible rotation speed.

According to an aspect of the present invention for achieving the above object, the present invention provides a method for producing a crystal by immersing a single crystal seed in a crucible containing a polysilicon melt, rotating the crucible at 8 rpm to 10 rpm to grow single crystal silicon into an ingot In the growth method, the oxygen concentration eluted between the inner wall of the crucible and the melt can be reduced, and the oxygen concentration introduced into the single crystal silicon can be controlled.

As described above, according to the configuration of the present invention, the following effects can be expected.

First, it is possible to grow a high-quality single crystal by minimizing the oxygen concentration and precipitate generated between the inner wall of the crucible and the melt according to the reduction of the rotational speed of the quartz crucible.

Second, as the rotational speed of the quartz crucible decreases, the amount of oxygen released from the melt decreases, thereby preventing bubbles on the inner wall of the crucible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing an oxygen concentration change showing an example of crucible rotation speed optimization for high-quality silicon single crystal growth according to the present invention. FIG.
FIG. 2 is a crucible cross-sectional photograph illustrating a crucible rotation speed optimization example for reducing crucible bubbles according to the present invention. FIG.

Brief Description of the Drawings The advantages and features of the present invention, and how to achieve them, will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Hereinafter, preferred embodiments of the crucible rotation speed optimization method for high-quality silicon single crystal growth and high durability crucible according to the present invention having the above-described structure will be described in detail with reference to the accompanying drawings.

A method for producing a high quality silicon single crystal ingot includes a step of filling a quartz crucible with a solid raw material of poly silicon, a melting step of heating and fusing a solid fuel with a heater, a stabilization step of removing air bubbles in the melt, A process of dipping a seed on a surface of a melt, a necking process of crystal-growing along a seed, a process of forming a shouldering process for controlling the vertical growth and horizontal growth rate of crystals to a desired diameter, ) Process, a body growing process for growing the ingot by keeping the diameter constant, and a tailing process for separating the ingot and the melt.

Here, various parameters of the body growth process determine whether a high quality single crystal is grown. Process parameters such as a pulling speed, an ingot rotation speed (I / R), and a crucible rotation speed (C / R) affect optimization of the silicon single crystal ingot growth.

The crucible rotation rate (C / R) of the above parameters at the time of body crystal growth is crucial to high-quality single crystal growth. Also, since the crucible rotation speed (C / R) can cause defects in the quartz crucible, it is of interest to adjust the rotation speed appropriately. For example, when a defect occurs in a quartz crucible, it may interfere with crystal growth for a long time.

In the crystal growth process, it is necessary to stably form a melt-ingot oxygen concentration gradient. The crucible rotation speed (C / R) directly affects the oxygen concentration gradient. That is, the ingot quality and the yield are different according to the increase / decrease of the crucible rotation speed (C / R). Accordingly, the present invention reduces the crucible rotation speed (C / R), thereby improving the ingot quality and softening the quartz crucible, Thereby realizing long-term crystal growth.

The present invention is characterized in that convection of the melt is stabilized by controlling the crucible rotation speed without using a magnet. For example, superconducting magnets can be used to stabilize melt convection and improve ingot quality.

As a result, the ingot quality is improved by reducing the crucible rotation speed (C / R). As the crucible rotation speed (C / R) decreases, the amount of oxygen released from the melt decreases, and the concentration of oxygen introduced into the single crystal decreases accordingly.

For example, in a crystal growth method of immersing a single crystal seed in a crucible containing a polysilicon melt and rotating the crucible to grow single crystal silicon into an ingot, the oxygen concentration eluted between the inner wall of the crucible and the melt is reduced, The oxygen concentration can be controlled.

1, the present invention reduces oxygen concentration by reducing the crucible rotation speed (C / R) by 20% to 30% (preferably 25%) and minimizing the frictional force between the inner wall of the crucible and the melt It is characterized by. The crucible rotation speed (C / R) is usually determined to be 8 rpm to 10 rpm, and the reduced crucible rotation speed (C / R) can be reduced to 5 rpm to 6 rpm.

It can be seen that the growth is body growth that keeps the diameter constant and that the oxygen concentration of the grown body is reduced over its entire length as compared to before the reduction.

On the other hand, when the crucible rotation speed (C / R) is reduced, the quartz crucible damage is reduced. After the crystal growth, quartz crucible can be confirmed in a bubble state.

On the inner wall of the quartz crucible in the single crystal growth, melt and silica as a quartz crucible component interact with each other to generate crystalline precipitates. Particularly, since the generation rate of the precipitate is increased in proportion to the crucible rotation speed (C / R), the crucible aging speed becomes even faster as the crucible rotation speed (C / R) increases. If the tear material is peeled from the inner wall of the crucible, the molten material moves to the melt surface during the convection of the melt, which is critical to the growth of high quality single crystal. Therefore, when the crucible rotation speed (C / R) is decreased, generation of precipitates is minimized.

Referring to FIG. 2, the quartz crucible may be formed in multiple layers. For example, it includes an inner transparent layer in which the melt is accommodated and an opaque layer outside the transparent layer. The transparent layer and the opaque layer function to disperse radiant heat of the melt. However, the polysilicon melt reacts with the inner wall of the silica crucible to expand the bubble in the transparent and opaque layers at the same time as oxygen is generated. Such a bubble continues to grow in the ingot lifting process and is released as a melt, and at the same time, causes the life of the quartz crucible to shorten. When such a bubble continuously grows, it is released into the melt to generate a vicious circle which interferes with the growth of high-quality single crystal. In particular, bubbles cause the crucible volume to expand and weaken the durability of the crucible.

As described above, the present invention reduces the crucible rotation speed by about 25% from among various parameters for determining high-quality single crystal growth, so that the oxygen concentration generated due to the reaction between the inner wall of the quartz crucible and the melt, The bubble expansion of the bubble is minimized. Many other modifications will be possible to those skilled in the art, within the scope of the basic technical idea of the present invention.

Claims (4)

1. A crystal growth method for growing a single crystal silicon into an ingot by immersing a single crystal seed in a crucible containing a polysilicon melt and rotating the crucible at 8 rpm to 10 rpm,
The oxygen concentration eluted between the inner wall of the crucible and the melt is reduced to adjust the oxygen concentration introduced into the single crystal silicon,
The oxygen concentration is reduced by reducing the crucible rotation speed (C / R) by 20% to 30% to minimize the frictional force between the crucible inner wall and the melt,
Wherein the reduced crucible rotation speed (C / R) is reduced from 5 rpm to 6 rpm. delete delete The method according to claim 1,
Wherein the growth is a body growth that keeps the diameter constant and the oxygen concentration of the grown body is reduced in its entire length as compared to before the reduction.

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