KR20080061718A - Method for determining distance of heat shield and manufacturing apparatus of silicon single crystal ingot using the same - Google Patents

Abstract

A method of determining the distance of a heat shield and an apparatus of manufacturing a silicon single crystal ingot using the same are provided to improve a yield by adjusting a distance between the heat shield and the silicon single crystal ingot. A furnace(20) is installed in a chamber(10), and is filled with a silicon solution(SM). The furnace is heated by a heater(40). A heat shield(50) is interposed between silicon single crystal ingot and the furnace to shield the heat emitted from the heater and the silicon solution. A horizontal distance between the heat shield and the silicon single crystal ingot is determined under a condition in that a vertical temperature gradient between an interface of the silicon solution and the silicon single crystal ingot is maximized.

Description

Method for Determining Distance of Heat Shield and Manufacturing Apparatus of Silicon Single Crystal Ingot Using the Same}

1 is a block diagram showing a silicon single crystal manufacturing apparatus according to the present invention;

2 is a block diagram showing a part of the simplified model of FIG. 1 for analysis;

3 is a graph showing the power and temperature gradient according to the horizontal distance d between the heat shield and the silicon single crystal ingot;

4 is a graph showing the power and temperature gradient according to the vertical distance h of the portion where the heat shield is adjacent to the silicon single crystal ingot;

5 is a graph showing a temperature gradient according to a horizontal distance d between a heat shield and the silicon single crystal ingot and a vertical distance h of a portion where the heat shield is adjacent to the silicon single crystal ingot.

<Explanation of Signs of Major Parts of Drawings>

10: chamber 20: crucible

25: crucible support 30: rotating shaft

40: heater 45: heat insulating member

50: heat shield IG: silicon single crystal ingot

SM: Silicone Melt

The present invention relates to a heat shield distance determination method and a device for manufacturing a silicon single crystal ingot using the same, and more particularly, to a heat shield distance determination method for improving productivity by increasing the growth rate of a silicon single crystal ingot and a silicon single crystal ingot using the same. It relates to a manufacturing apparatus.

In general, in the method of growing a silicon single crystal ingot according to the Czochralski method, polycrystalline silicon is loaded into a quartz crucible and melted polycrystalline silicon with heat radiated from a heater to form a silicon melt, and then silicon single crystal from the surface of the silicon melt. Grow ingots.

When growing a silicon single crystal ingot, the quartz crucible is raised while rotating the axis supporting the quartz crucible so that the solid-liquid interface is maintained at the same height, and the silicon single crystal ingot is rotated around the same axis as the rotation axis of the quartz crucible. Pull up while rotating in the opposite direction.

In addition, in order to facilitate silicon single crystal ingot growth, an inert gas such as argon (Ar) gas is introduced into the upper portion of the ingot growth apparatus, and a method of discharging the lower portion of the ingot growth apparatus is widely used.

In addition, a heat shield is provided between the silicon single crystal ingot and the crucible to surround the silicon single crystal ingot and to block the heat dissipated from the heater and the silicon melt so as to cool the silicon single crystal ingot well.

On the other hand, since the conventional heat shield itself absorbs heat and dissipates the absorbed heat, there is a problem that adversely affects the cooling of the adjacent silicon single crystal ingot.

However, up to now, it was not recognized about such a contradictory effect of the heat shield, and the horizontal distance between the heat shield and the silicon single crystal ingot consisted of about 2 cm in a batch in consideration of a decrease in thermal insulation. That is, conventionally, there is no clear standard for determining the optimal position of the heat shield to improve the growth rate of the silicon single crystal ingot in view of the effect of the heat of the heat shield itself.

SUMMARY OF THE INVENTION The present invention has been made to solve the above conventional problems, and an object of the present invention is to provide an apparatus for producing a silicon single crystal ingot which provides a reference for determining the distance between the heat shield and the silicon single crystal ingot.

Another object of the present invention is to provide an apparatus for producing a silicon single crystal ingot which determines the optimized distance between the heat shield and the silicon single crystal ingot to increase the growth rate of the silicon single crystal ingot and consequently improves the productivity of the silicon single crystal ingot. .

In order to achieve the above object, the present invention is a device for producing a silicon single crystal ingot by the Czochralski method, a chamber, a crucible installed inside the chamber and containing a silicon melt, a heater for heating the crucible And a heat shield provided between the silicon single crystal ingot and the crucible, the heat shield blocking heat emitted from the heater and the silicon melt, wherein a horizontal distance d between the heat shield and the silicon single crystal ingot is the silicon. Provided is an apparatus for producing a silicon single crystal ingot, which is determined under the condition that the vertical temperature gradient G between the interface of the melt and the silicon single crystal ingot becomes maximum.

And, the horizontal distance d between the heat shield and the silicon single crystal ingot is preferably a function of the vertical distance h of the portion adjacent to the silicon single crystal ingot. Here, the horizontal distance d between the heat shield and the silicon single crystal ingot is proportional to the vertical distance h of the portion where the heat shield is adjacent to the silicon single crystal ingot.

In addition, the horizontal distance d between the heat shield and the silicon single crystal ingot is preferably a function of the heat Q emitted from the heater.

On the other hand, the temperature gradient G is preferably calculated by the temperature difference between the interface of the silicon melt and the point raised 2 mm upward from the interface of the silicon melt.

In the heat shield distance determining method according to the present invention, the horizontal distance (d) between the heat shield and the silicon single crystal ingot is such that the vertical temperature gradient (G) between the interface of the silicon melt and the silicon single crystal ingot is maximum. Decide on the conditions.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the description of this embodiment, the same name and the same reference numerals are used for the same configuration and additional description thereof will be omitted.

First, referring to Figure 1, the overall configuration of the silicon single crystal manufacturing apparatus is as follows.

1 is a block diagram showing a process of growing a silicon single crystal by the Czochralski method, the silicon single crystal manufacturing apparatus according to the present embodiment includes a chamber 10, the silicon single crystal inside the chamber 10 Ingot growth takes place.

A crucible 20 containing silicon melt SM is installed in the chamber 10, and a crucible support 25 made of graphite is installed outside the crucible 20 so as to surround the crucible 20.

The crucible support 25 is fixedly installed on the rotation shaft 30, which is rotated by a driving means (not shown) to raise the crucible 20 while rotating, so that the solid-liquid interface maintains the same height. Do it. The crucible support 25 is surrounded by a cylindrical heater 40 at predetermined intervals, which is surrounded by a heat insulating member 45.

That is, the heater 40 is installed on the side of the crucible 25 to melt a high-purity polysilicon mass loaded in the crucible 20 to form a silicon melt SM, and the heat insulating member 45 is formed at the heater 40. Heat dissipation is prevented from spreading toward the wall of the chamber 10 to improve thermal efficiency.

An upper portion of the chamber 10 is provided with an pulling means (not shown) for winding and pulling a cable. A lower portion of the cable 10 is in contact with the silicon melt SM in the crucible 20 while being pulled up to form a single crystal ingot ( A seed crystal for growing IG) is installed. The pulling means rotates while pulling up the cable during the growth of the single crystal ingot IG, wherein the silicon single crystal ingot IG is rotated about the same axis as the rotation axis 30 of the crucible 20. Rotate in the opposite direction to the direction of pulling up.

In the upper portion of the chamber 10, an inert gas such as argon (Ar), neon (Ne), and nitrogen (N) is supplied to the grown single crystal ingot IG and the silicon melt SM, and the used inert gas is used. Discharges through the lower portion of the chamber 10.

A heat shield 50 is provided between the silicon single crystal ingot IG and the crucible 20 so as to surround the ingot IG. The silicon single crystal ingot IG is surrounded by the heater 40 and the silicon melt SM. It acts to block the heat released.

However, according to the experiments of the present inventors, the heat shield 50 absorbs heat emitted from the heater 40 or the silicon melt SM by itself and emits it to the silicon ingot IG, thereby providing a silicon single crystal ingot IG. It was confirmed to affect the cooling of the. That is, the heat shield 50 has an insulated function and has two opposite effects of helping to cool the silicon single crystal ingot IG and self heating effect.

Therefore, in order to improve the growth rate of the silicon single crystal ingot IG, the above two effects must be properly adjusted.

In the present invention, in consideration of two opposite effects of the heat shield 50, the horizontal distance between the heat shield 50 and the silicon single crystal ingot IG is determined.

Basically, if the distance between the heat shield 50 and the silicon single crystal ingot IG is too close, the heat emitted from the heat shield 50 itself adversely affects the cooling of the silicon ingot IG, as described above. If the distance between the shield 50 and the silicon single crystal ingot IG is too long, the thermal insulation of the heat shield 50 may not be possible.

According to the Voronkov equation, the quality of wafers during silicon single crystal growth is determined by V / G values. Here, V denotes a pulling rate during vertical growth of the silicon single crystal, and G denotes a temperature gradient in the single crystal in the vertical direction from the surface of the silicon melt (SM).

Therefore, increasing the value of G can increase the V, thereby increasing the growth rate, and consequently, the productivity of the silicon single crystal ingot IG can be improved.

With this in mind, in the present invention, the horizontal distance d between the silicon single crystal ingot IG and the heat shield 50 is configured to be determined under the condition that the temperature gradient G is maximized.

2 to 5, the process of determining the distance between the silicon single crystal ingot and the heat shield will be described.

First, with reference to FIG. 2, the model which simplified FIG. 1 for analysis is demonstrated.

The heat generating effect of the heat shield 150 is that the vertical distance (h) at the portion where the heat shield 150 is adjacent to the silicon single crystal ingot (IG), the calorific value of the heater 140, the heat shield 150 and the silicon single crystal ingot It is understood that it is affected by the horizontal distance (d) between (IG) and the like.

FIG. 2 is a simplified model of FIG. 1, and simplifies the shape of the heat shield 150 to exclude the effect of changing the thickness of the heat insulating material according to the distance of the heat shield 150 or the effect of the specific shape of the heat shield 150. .

That is, the heat shield 150 in the present model is simplified to a shape in which the vertical width is constant for a certain horizontal distance as shown in FIG. 2.

Based on this simplified model, computer simulation was performed under the following conditions.

Here, N3 is the model name, H / Z size is the diameter of the crucible, Change Size is the amount of polysilicon used in the silicon single crystal ingot (IG), Melt Level is between the top of the heater 140 and the interface of the silicon melt (SM) Vertical distance (l), Melt Gap is the vertical distance (g) between the bottom of the heat shield 150 and the interface of the silicon melt (SM), Pull Speed means the pulling speed of the silicon single crystal ingot (IG).

Under the conditions as shown in Table 1, the distance d between the heat shield 150 and the silicon single crystal ingot IG and the vertical distance h of the portion where the heat shield 150 is adjacent to the silicon single crystal ingot IG are changed. Computer simulations were conducted.

3 to 5 show the results of computer simulation analysis performed under the above conditions.

First, FIG. 3 shows the power and temperature gradient G according to the horizontal distance d between the heat shield and the silicon single crystal ingot.

Here, the temperature gradient G is calculated by the temperature difference between the interface of the silicon melt and the point raised 2 mm upward from the interface of the silicon melt. And, in the condition that the vertical distance (h) of the part where the heat shield is adjacent to the silicon single crystal ingot is 50 mm, the d is changed by 10 mm / 30 mm / 50 mm / 70 mm / 90 mm by 20 mm. Was performed.

As shown in (a) of FIG. 3, it can be seen that as d increases, the power value required for ingot growth increases. This is thought to be due to heat loss due to a decrease in thermal insulation as the distance (d) of the heat shield increases.

On the other hand, the temperature gradient (G) is increased as shown in (b) of FIG.

However, as the distance d of the heat shield increases, the silicon single crystal ingot is more likely to be directly received, thereby increasing the temperature of the silicon single crystal ingot. As a result, the temperature gradient G falls.

On the other hand, if the horizontal distance (d) between the silicon ingot and the heat shield becomes small, the temperature shield (G) is lowered by affecting the silicon single crystal ingot by the self-heating of the heat shield.

As described above, as the horizontal distance (d) between the silicon single crystal ingot and the heat shield increases, the temperature gradient (G) increases and decreases again at a certain point, and maximizes the temperature gradient in the middle. It can be seen that there is a distance.

Next, FIG. 4 shows the power and temperature gradient G according to the vertical distance h of the portion where the heat shield is adjacent to the silicon single crystal ingot.

Here, the horizontal distance (d) between the heat shield and the silicon single crystal ingot was analyzed by changing h to 10 mm / 30 mm / 50 mm by 20 mm in a condition of 10 mm.

As shown in FIG. 4 (a), as h increases, the power value decreases. This is because heat insulation effect by heat shield increases. As the area adjacent to the silicon single crystal ingot becomes wider, the heat generation amount increases, so that the cooling rate of the silicon ingot decreases and the power value decreases. Therefore, it can be seen that the temperature gradient G decreases as h increases as shown in FIG.

5 shows the temperature gradient according to the horizontal distance d between the heat shield and the silicon single crystal ingot and the vertical distance h of the portion where the heat shield is adjacent to the silicon single crystal ingot.

As shown in Figure 5, it can be seen that there is an optimal d having the highest temperature gradient G when changing d. As h increases, the optimal value of d with the highest temperature gradient G increases.

That is, as h increases, the heat shield calorific value that affects the silicon ingot increases, so that d, which has the highest temperature gradient G, changes.

Referring to FIG. 5, the distance d of the heat shield at which the temperature gradient G is maximum is 50 mm when h is 10 mm, 66.51 mm when h is 30 mm, and 77.81 mm when h is 50 mm. You can check it.

From the above analysis results, it can be seen that the distance d of the heat shield has an optimum value maximizing the temperature gradient G, and this optimum d increases as h increases.

And, if the curve fitting (curve fitting) of the above results, it can be expressed in the following exponential form,

.

.

Where A and B are positive constants between 0 and 1.

On the other hand, it can be expressed in the form of a polynomial unlike this, and the specific equation obtained by curve fitting the result of FIG.

.

.

As described above, the optimum d for maximizing the temperature gradient G while varying d and h can be expressed by a correlation for h, so that the optimum d can be easily determined according to the change of the h value. Will be.

The present invention is not limited to the above-described embodiments, and as can be seen in the appended claims, those skilled in the art can make modifications without departing from the spirit of the present invention, and such modifications are possible. Belongs to the scope of.

The heat shield distance determination method and the apparatus for producing a silicon single crystal ingot using the same according to the present invention having the above configuration has the following effects.

First, the present invention has the advantage of increasing the growth rate of the silicon single crystal ingot by determining the optimum distance of the heat shield.

Specifically, instead of determining the distance between the silicon single crystal ingot and the heat shield uniformly, the heat insulation effect by the heat shield is determined by considering the temperature gradient (G) in consideration of the degree of heat insulation, the power value, and the self-heating phenomenon of the heat shield. It can maintain the growth rate of the silicon single crystal ingot by minimizing the adverse effect of the heat shield self-heating while maintaining.

Second, by improving the growth rate of the silicon single crystal ingot, there is an advantage that can improve the productivity of the silicon single crystal ingot of a certain quality.

Claims (10)

In the apparatus for producing a silicon single crystal ingot by the Czochralski method, chamber; A crucible installed inside the chamber and containing a silicon melt; A heater for heating the crucible; And A heat shield provided between the silicon single crystal ingot and the crucible to block heat emitted from the heater and the silicon melt; And a horizontal distance (d) between the heat shield and the silicon single crystal ingot is determined under a condition that a vertical temperature gradient (G) between the interface of the silicon melt and the silicon single crystal ingot is maximized. The method of claim 1, The horizontal distance d between the heat shield and the silicon single crystal ingot is And the heat shield is a function of the vertical distance (h) of the portion adjacent to the silicon single crystal ingot. The method of claim 2, The horizontal distance d between the heat shield and the silicon single crystal ingot is And the heat shield is proportional to the vertical distance (h) of the portion adjacent to the silicon single crystal ingot. The method of claim 1, The horizontal distance d between the heat shield and the silicon single crystal ingot is Apparatus for producing a silicon single crystal ingot, characterized in that it is a function of the heat (Q) emitted from the heater. The method of claim 1, The temperature gradient (G) is, An apparatus for producing a silicon single crystal ingot, characterized in that it is calculated by the temperature difference between the interface of the silicon melt and the point raised 2 mm upward from the interface of the silicon melt. A chamber, a crucible installed inside the chamber and containing a silicon melt, a heater for heating the crucible, and a heat shield provided between the silicon single crystal ingot and the crucible to block heat radiated from the heater and the silicon melt. In the apparatus for producing a silicon single crystal ingot, Wherein the horizontal distance (d) between the heat shield and the silicon single crystal ingot is determined under the condition that the vertical temperature gradient (G) between the interface of the silicon melt and the silicon single crystal ingot is maximum. Heat shield distance determination method. The method of claim 6, The horizontal distance d between the heat shield and the silicon single crystal ingot is And the heat shield is a function of the vertical distance (h) of the portion adjacent to the silicon single crystal ingot. The method of claim 6, The horizontal distance d between the heat shield and the silicon single crystal ingot is And the heat shield is proportional to the vertical distance (h) of the portion adjacent to the silicon single crystal ingot. The method of claim 6, The horizontal distance d between the heat shield and the silicon single crystal ingot is A method for determining the heat shield distance of an apparatus for producing a silicon single crystal ingot, which is a function of heat (Q) emitted from the heater. The method of claim 6, The temperature gradient (G) is, A method for determining the heat shield distance of a device for producing a silicon single crystal ingot, characterized in that it is calculated by the temperature difference between the interface of the silicon melt and the point raised 2 mm upward from the interface of the silicon melt.

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