KR20050053101A - An apparatus of manufacturing silicon single crystal ingot, a method of manufacturing using the apparatus, silicon single crystal ingots and silicon wafers using the apparatus - Google Patents

Abstract

The present invention relates to a device for growing a silicon single crystal ingot according to the Czochralski method, and its object is to provide a device for producing a single crystal ingot capable of improving ingot growth rate while achieving uniform quality in-plane of a silicon wafer. It is. In the present invention for this purpose; A crucible installed inside the chamber and containing the silicon melt; A heater for heating the crucible; A heat shield disposed between the silicon single crystal ingot and the crucible so as to surround the silicon single crystal ingot to block heat radiated from the silicon melt and the ingot; And a cylindrical heat shield attached to the closest portion with the silicon single crystal ingot in the heat shield, and surrounding the silicon single crystal ingot.

Description

A device of manufacturing silicon single crystal ingot, a method of manufacturing using the apparatus, silicon single crystal ingots and silicon wafers using the apparatus}

The present invention relates to an apparatus for growing a silicon single crystal ingot according to the Czochralski method, and more particularly, to a silicon single crystal ingot growth apparatus for achieving in-plane uniform quality of a silicon wafer and increasing ingot growth speed. will be.

When the single crystal is grown by the Czochralski method, which is a typical method for producing a single crystal ingot for a silicon wafer, the crystal quality characteristics in the single crystal largely depend on the pulling rate and cooling conditions of the crystal. Therefore, many efforts have been made to control the crystal quality by controlling the thermal environment near the growth interface.

As the silicon melt is solid crystallized, vacancy and interstitial point defects are mixed above the equilibrium concentration, and during cooling, the point defects aggregate and develop into growth defects. According to Boronkov, the formation of these defects is closely related to the V / G values, where V is the growth rate and G is the vertical temperature gradient in the crystal near the growth interface.

According to Voronkov's theory, if the V / G value exceeds a certain threshold, then the vacancy type and the interstitial type point defects prevail below that threshold. Therefore, when growing a crystal in a given hot zone, the kind and density of point defects existing in the crystal are affected by the pulling speed.

Generally, the heat dissipation at the surface of the ingot is free and the vertical temperature gradient (G) in the crystal is larger at the outer periphery than at the center of the ingot. That is, since the G value increases from the center to the outer circumference along the radial direction of the ingot, the baconsie dominant region is formed at the central portion, and the interstitial dominant region is formed at the outer peripheral portion.

However, in accordance with the trend that the wafers are required to have uniform in-plane characteristics, various hot zones have been designed to reduce the deviation of the vertical temperature gradient in the crystal radial direction, and examples thereof include Korean Patent Application 2000-71000 and Japanese Patent Publication. There are heat shields proposed in 2000-247776.

However, these conventional heat shields have been effective in reducing the radial deviation of the vertical temperature gradient, but the vertical temperature gradient of the crystal outer periphery still provides a higher ingot growth environment than the center. In particular, the vertical temperature gradient itself is not significantly improved, there is a problem that the productivity of the silicon single crystal ingot is low.

In addition, since heat transfer in the vicinity of the crystal growth interface is easy, the operating power is increased to maintain a continuous melt state, thereby increasing the cost of manufacturing the ingot.

In addition, the argon flow cross section between the ingot and the heat shield near the interface has a problem that the initial oxygen concentration, which is one of the quality indicators of the crystal, increases.

The present invention has been made to solve the above problems, and its object is to minimize the radial quality deviation by making the vertical temperature slope of the center of the growing single crystal ingot equal to or greater than the vertical temperature slope of the outer periphery.

Another object of the present invention is to provide an apparatus for producing a single crystal ingot which can improve the silicon single crystal ingot growth rate.

It is another object of the present invention to save operating power near the growth interface to reduce operating power and to provide effective control of initial oxygen concentration by argon flow optimization.

Accordingly, the present invention is characterized by providing a cylindrical heat shield surrounding the silicon single crystal ingot in the heat shield in the apparatus for producing a silicon single crystal ingot by the Czochralski method.

That is, the apparatus for producing a silicon single crystal ingot according to the present invention comprises a chamber; A crucible installed inside the chamber and containing the silicon melt; A heater for heating the crucible; A heat shield disposed between the silicon single crystal ingot and the crucible so as to surround the silicon single crystal ingot to block heat radiated from the silicon melt and the ingot; And a cylindrical heat shield attached to the closest portion with the silicon single crystal ingot in the heat shield and surrounding the silicon single crystal ingot.

Here, the heat shield may be changed in the radius of the cylinder so that the separation distance with the silicon single crystal ingot changes along the longitudinal direction of the ingot.

As described above, when the cylindrical radius of the heat shield is changed, the angle formed by the longitudinal axis of the heat shield and the silicon single crystal ingot is preferably changed within a range of -20 degrees to 20 degrees.

The height of the heat shield cylindrical is preferably 20 mm or more, more preferably 30 mm or more.

A hole is formed in the heat shield to control the flow of inert gas.

The lower surface of the heat shield cylindrical may have a concave-convex shape.

The material of the heat shield may be any one of graphite, amorphous quartz, and molybdenum, and silicon carbide (SiC) may be coated on the surface of the heat shield.

Using the apparatus of the present invention as described above, the vertical temperature gradient at the center of the silicon single crystal ingot is larger than or equal to the vertical temperature gradient at the outer periphery of the ingot, or the vertical temperature gradient at the center is Silicon single crystal ingots can be grown at or below 0.56 degrees K / cm compared to the vertical temperature gradient.

As a result, it is possible to produce silicon single crystal ingots and silicon wafers in which the oxygen concentration inside the silicon single crystal ingot has a desired value, in particular, the silicon single crystal ingot and silicon controlled within the range of 9 to 12 ppma. Wafers can be manufactured.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In general, in growing silicon single crystals by Czochralski (CZ) method, the growth and cooling conditions of the single crystal ingots are uniformly radially, and the growing single crystals are processed at the speed of a specific range to form wafers. Over 90% of the area is the same quality area, and the speed of realizing that particular quality is also improved.

Accordingly, the present invention provides an apparatus and a method for growing a silicon single crystal ingot having a uniform crystal quality characteristic in the radial direction, and thus aims to improve the pulling speed for achieving a uniform quality.

In the present invention, a silicon single crystal ingot is grown according to the Czochralski method and a silicon single crystal ingot growth apparatus as shown in FIG. 1 is used. 1 is a cross-sectional view showing the inside of a silicon single crystal ingot growth apparatus according to the present invention.

As shown in FIG. 1, the apparatus for manufacturing a silicon single crystal ingot according to the present invention includes a chamber 10, and growth of the silicon single crystal ingot is performed in the chamber 10.

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

The crucible support 25 is fixedly installed on the rotating shaft 30, which is rotated by a driving means (not shown) to raise the crucible 25 while rotating the quartz-liquid interface to have the same height. Keep it. The crucible support 25 is surrounded by a cylindrical heater 40 at predetermined intervals, and the heater 40 is surrounded by a thermos 45.

The heater 40 melts a high-purity polysilicon mass loaded in the quartz crucible 20 to form a silicon melt SM. The thermostat 45 has heat from the heater 40 toward the wall of the chamber 10. Prevents diffusion and improves thermal efficiency.

In the upper part of the chamber 10, a pulling means (not shown) for winding and pulling a cable is provided. The lower part of the cable 10 is in contact with the silicon melt SM in the quartz crucible 20 and 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). Discharge through the bottom of the chamber (10).

A heat shield 50 is installed between the silicon single crystal ingot IG and the crucible 20 so as to surround the ingot IG to block heat radiated from the ingot, and the heat shield 50 with the ingot IG. The heat shield 60 is attached to the closest part to further block heat flow to preserve heat.

The heat shield 50 is made of molybdenum (Mo), tungsten (W), carbon (C) or SiC coated graphite and can be manufactured in various shapes.

For example, the heat shield 50 has a cylindrical first shield portion provided between the ingot IG and the crucible 20, and a flange shape connected to the upper portion of the first shield portion and fixed to the upper portion of the thermal insulation tube 45. It may be composed of a second shield and a third shield formed to protrude toward the single crystal ingot connected to the lower portion of the first shield.

However, the shape of the heat shield 50 is not limited to the above-described structure, and the heat shield of any shape may be used in the present invention.

The heat shield 60 of the present invention is provided at the closest portion of the heat shield 50 with the ingot IG in any shape without being limited to the shape of the heat shield. Alternatively, the heat shield may be integrated with the heat shield.

The heat shield 60 has a cylindrical shape surrounding the ingot IG, and the cylindrical heat shield 60 is designed to maximize the temperature difference between the temperature near the growth interface and the top of the ingot by preserving heat for a basic purpose. .

The cylindrical shape of the heat shield 60 may have a vertical plane parallel to the ingot along the longitudinal direction of the ingot IG, and the radius of the cylindrical shape so that the separation distance from the ingot IG varies along the longitudinal direction of the ingot IG. It may have this changing slope.

2 is a cross-sectional view showing the heat shield 60 in which the radius of the cylinder changes along the longitudinal direction of the ingot IG, and thus the cylindrical radius of the heat shield 60 changes along the longitudinal direction of the ingot IG. In this case, the angle θ formed between the heat shield 60 and the longitudinal axis of the ingot IG is preferably -20 to 20 degrees.

The height H of the heat shield 60 cylindrical shape is preferably greater than or equal to 20 mm, more preferably greater than or equal to 30 mm. At this time, the larger the height of the heat shield 60 cylindrical shape is more effective to perform the role of the heat shield more effectively, but is limited by satisfying the condition that does not touch the silicon melt (SM) and the height condition of the heat shield is already installed height ( The upper limit of H) is determined.

The thickness of the cylindrical plate of the heat shield 60 is not particularly limited and may be a thickness that is not broken by thermal shock during single crystal ingot growth.

In addition, the heat shield 60 may be provided with a hole 65 to facilitate the flow of inert gas such as argon, and the bottom surface of the heat shield 60 may be formed in an uneven shape to be inert through the recess. It is also possible to smooth the flow of gas.

3A and 3B are perspective views of the heat shield 60. 3A shows a heat shield 60 in which a plurality of holes 65 are formed, and the number and arrangement of the holes 65 include a melt gap (a radial gas flow cross-sectional area) and an ingot gap. It can be variously changed in consideration of (ingot-gap: gas flow cross-sectional area in the vertical direction).

3B illustrates a heat shield 60 having a concave-convex shape on a lower surface thereof, and in this heat shield 60, an inert gas forms a vortex while passing through the concave-convex shape, so that a smoother evaporation of SiO gas may be achieved.

The heat shield 60 may be made of any one of graphite, amorphous quartz, and molybdenum, and may be selected and used as an appropriate material according to the purpose in consideration of emissivity and transmittance. In addition, silicon carbide (SiC) may be coated on the surface of the heat shield.

As described above, when the heat shield is installed, the heat density in the malt gap increases, thereby increasing the temperature near the growth interface and decreasing the temperature of the upper part of the ingot. Therefore, the vertical temperature gradient G rises, and in particular, the area in which the heat shield and the ingot are adjacent to each other increases as much as the cylindrical area of the heat shield, so that the vertical temperature gradient of the ingot center is almost the same as the outer circumference, or rather, the outer circumference.

For Examples 1 to 3 with a heat shield according to the present invention and a comparative example (conventional) without a heat shield, the vertical temperature gradient and the temperature gradient in the radial direction are respectively measured and the results are as follows. Table 1 shows.

Examples 1 to 3 are classified according to the area ratio of the holes in the heat shield, and specifically, in Example 1, the area of the holes in the heat shield is 18%, in Example 2, 6%, and in Example 3 3% was set.

G / Go ΔG (K / cm) Example 1 1.12 -0.56 Example 2 1.17 -0.31 Example 3 1.18 0.15 Comparative example One 0.65

In Table 1, G means a vertical temperature gradient measured through actual experiments in Examples 1 to 3, and Go means a vertical temperature gradient when no heat shield is installed as in the prior art. Therefore, in the comparative example, G / Go was 1, and in Examples 1 to 3, G / Go was all greater than 1. This means that according to Examples 1 to 3 of the present invention, the vertical temperature gradient near the growth interface is further increased as compared with the prior art.

In addition, in Table 1, delta (Δ) G means the value obtained by subtracting the vertical temperature gradient at the ingot center from the vertical temperature gradient at the outer periphery of the ingot. In Examples 1 and 2, the ΔG value is negative (-) and the vertical ingot center is vertical. The temperature gradient was higher than the vertical temperature gradient at the outer periphery of the ingot. In Example 3, the ΔG value was 0.15 K / cm, and the vertical temperature gradients of the center and the outer circumference were almost similar, which were much lower than those of the comparative example of 0.65 K / cm.

As described above, according to the present invention, the heat shield increases the temperature of the heat shield by filling radiant heat of the silicon melt in the malt gap, and maintains a similar cooling rate of the ingot adjacent to the heat shield. Therefore, since the cooling speeds of the outer periphery and the center of the ingot are similar, the vertical temperature gradient is increased as a whole, thereby minimizing the deviation in the outer periphery and the center, thereby improving the pulling speed to realize uniform quality in the radial direction.

In addition, since the heat shield fills the radiant heat of the silicon melt in the melt gap, the operating power of the heater for maintaining the melt state of the silicon melt can be reduced.

On the other hand, the heat shield serves to guide the inert gas to prevent a decrease in the flow rate to sufficiently remove the SiO gas near the growth interface. Thus, the oxygen concentration incorporated into the crystal ingot is reduced.

Oxygen concentration and operating power were measured for Examples 1 to 3 and Comparative Examples described above, and the results are shown in Table 2 below.

Oxygen concentration (ppma) Operating power ratio (P / Po) Example 1 10.8 0.948 Example 2 10.9 0.952 Example 3 11.3 0.954 Comparative example 12.5 One

In Table 2, P means the operating power measured through the actual experiment in Examples 1 to 3, Po means the operating power when the heat shield is not installed as in the prior art. Therefore, in the comparative example, P / Po is 1, and in Examples 1 to 3, all of the P / Pos are smaller than 1, thereby confirming the cost reduction.

As shown in Table 2, in the case of Examples 1 to 3 of the present invention, the oxygen concentration was lower than that of the comparative example, and the operating power was also lower than that of the comparative example.

In addition, as the area ratio occupied by the holes increases, oxygen concentration can be effectively reduced by forming a smooth gas flow while preserving heat sufficiently.

This result shows that the oxygen concentration can be controlled to a desired value by changing the hole occupancy area of the heat shield. At this time, the process variable for controlling the oxygen concentration is not limited to the hole occupancy area, and the oxygen concentration can be controlled to a desired value by changing the position of the hole, the height, the shape, or the like of the heat shield.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described embodiments, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the claims It belongs to the scope of the present invention.

As described above, in the present invention, in the apparatus for producing a silicon single crystal ingot according to the Czochralski method, the heat shield is installed in the heat shield so that the vertical temperature gradient at the center of the silicon single crystal ingot is larger than the vertical temperature gradient at the outer periphery. It has the effect of growing a silicon single crystal ingot in about the same state.

That is, in the present invention, due to the installation of the heat shield, the vertical temperature gradient deviation between the center of the ingot and the outer periphery is reduced, thus reducing the radial quality deviation of the silicon single crystal ingot and improving the silicon single crystal ingot growth rate.

In addition, the present invention has the effect of reducing the operating power by installing heat shields to preserve heat near the growth interface.

In addition, since the SiO gas in the vicinity of the growth interface is sufficiently removed by optimizing the flow of the inert gas, the oxygen concentration introduced into the ingot can be reduced, and in particular, the oxygen concentration can be controlled to have a desired oxygen concentration value.

 1 is a cross-sectional view showing the inside of a silicon single crystal ingot growth apparatus according to the present invention,

2 is a cross-sectional view showing the heat shield 60 in which the radius of the cylindrical cylinder changes in the longitudinal direction of the ingot IG in the silicon single crystal ingot growth apparatus according to the present invention.

3A and 3B are perspective views illustrating a heat shield in the silicon single crystal ingot growth apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

10 chamber 20 crucible

25: crucible support 30: rotating shaft

40: heater 45: thermos

50: heat shield 60: heat shield

65: hall

IG: silicon single crystal ingot SM: silicon melt

Claims (13)

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; A heat shield disposed between the silicon single crystal ingot and the crucible so as to enclose a silicon single crystal ingot to block heat radiated from the ingot; And A cylindrical heat shield attached to the closest portion of the heat shield with the silicon single crystal ingot and surrounding the silicon single crystal ingot. Silicon single crystal ingot manufacturing apparatus comprising a. The method of claim 1, And the heat shield is a silicon single crystal ingot manufacturing apparatus in which the radius of the cylinder is changed such that a distance from the silicon single crystal ingot varies along the longitudinal direction of the ingot. The method of claim 1, An apparatus for producing a silicon single crystal ingot, wherein an angle formed between the heat shield and the longitudinal axis of the silicon single crystal ingot is -20 degrees to 20 degrees. The method of claim 1, An apparatus for producing a silicon single crystal ingot, wherein the heat shield cylindrical portion has a height of 20 mm or more. The method of claim 4, wherein An apparatus for producing a silicon single crystal ingot, wherein the heat shield cylindrical portion has a height of 30 mm or more. The method of claim 1, A device for manufacturing a silicon single crystal ingot, wherein a hole is formed in the heat shield. The method of claim 1, An apparatus for producing a silicon single crystal ingot having a bottom surface of the heat shield cylindrical having an uneven shape. The method of claim 1, The material of the heat shield is a silicon single crystal ingot manufacturing apparatus of any one of graphite, amorphous quartz, molybdenum. The method of claim 1, Silicon single crystal ingot manufacturing apparatus is coated with silicon carbide (SiC) on the surface of the heat shield. Using the apparatus of claim 1, the vertical temperature gradient at the center of the silicon single crystal ingot is greater than or equal to the vertical temperature gradient at the outer periphery of the ingot, or the vertical temperature gradient at the center is perpendicular to the vertical temperature gradient at the outer periphery. A method for producing a silicon single crystal ingot, wherein the silicon single crystal ingot is grown in a state of less than or equal to 0.5 degrees K / cm or less. The method of claim 10, Method of producing a silicon single crystal ingot to control the oxygen concentration in the silicon single crystal ingot within the range of 9 to 12 ppma. A silicon single crystal ingot manufactured using the apparatus of claim 1 and controlled to have an internal oxygen concentration in the range of 9 to 12 ppma. A silicon wafer manufactured using the apparatus of claim 1 and controlled to have an oxygen concentration therein within a range of 9 to 12 ppma.