KR101101096B1 - Method of growing single crystal ingot and single crystal ingot grown by the same - Google Patents

Abstract

Provided are a single crystal ingot growth method and a single crystal ingot grown thereby. Provided is a method for manufacturing a single crystal substrate. The method involves applying a magnetic field to the melt contained in the crucible, generating a temperature difference between the portion in contact with the crucible and the central portion of the melt, mixing the melt, and pulling a single crystal ingot from the melt. Single crystal ingots grown using this method may have a variation in the lattice oxygen concentration of 0.7 ppma or less.

Description

Method of growing single crystal ingot and single crystal ingot grown by the same {Method of growing single crystal ingot and single crystal ingot grown by the same}

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

A silicon wafer for manufacturing a semiconductor device may be manufactured by growing single crystal silicon in an ingot form, and then slicing, etching, polishing, and cleaning the silicon. The single crystal silicon ingot can be grown using Czochralski (CZ) method or floating zone (FZ) method. Generally, large diameter silicon single crystal ingot can be manufactured and the process cost is relatively low. It is grown using the CZ method.

In the CZ method, a single seed crystal is immersed into a silicon melt contained in a quartz crucible, and pulled up at low speed to grow into a silicon single crystal ingot. Oxygen is eluted from the quartz crucible containing the silicon melt into the silicon melt. The eluted oxygen moves along the convection in the silicon melt and most of it volatilizes at the surface of the silicon melt, but part of it is introduced into the ingot and positioned between the silicon lattice.

Such interstitial oxygen atoms (Oi) may form an oxygen precipitate during heat treatment of the wafer processed from the ingot. In the semiconductor device manufacturing process, such oxygen precipitates can serve as internal gettering sites for metallic impurities. However, in the presence of interstitial oxygen above an appropriate level, it acts as a source of dislocation loops, stacking faults, and the like, which are crystal defects, which adversely affects the quality of semiconductor devices. Therefore, it is important to control the lattice oxygen concentration uniformly in high quality silicon single crystal.

A magnetic field can be used to control the concentration of interstitial oxygen atoms in the ingot. When a magnetic field is applied to the silicon melt, the convection of the silicon melt can be suppressed to reduce the oxygen atoms eluted from the quartz crucible so that the amount of oxygen inflow can be controlled. However, sometimes fluctuations in the convection in the silicon melt result in a small fluctuation of the interstitial oxygen concentration in the ingot, in which case the radial oxygen concentration distribution of the ingot may deteriorate. In this case, the yield of the silicon wafer can be lowered.

The problem to be solved by the present invention is to provide a single crystal ingot manufacturing method with improved oxygen concentration distribution.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

One aspect of the present invention to achieve the above object provides a single crystal substrate manufacturing method. The method involves applying a magnetic field to the melt contained in the crucible, generating a temperature difference between the portion in contact with the crucible and the central portion of the melt, mixing the melt, and pulling a single crystal ingot from the melt.

Power having an amplitude of 2 kW or more may be applied to a heater for supplying heat to the melt, thereby generating a temperature difference between a portion of the melt in contact with the crucible and a central portion of the melt. Electric power having an amplitude of 40 kw or less may be applied to the heater. Furthermore, power having an amplitude of 10 kw or more may be applied to the heater.

The magnetic field may be a horizontal magnetic field. The horizontal magnetic field may be a magnetic field of 1500 G or more.

Single crystal ingots grown using this method may have a variation in the lattice oxygen concentration of 0.7 ppma or less. Furthermore, the fluctuation range of the interstitial oxygen concentration may be 0.6 ppm or less.

According to the present invention, the concentration of oxygen flowing into the single crystal ingot can be made uniform by mixing the melt by generating a temperature difference between the portion where the melt is in contact with the crucible and the center of the melt. As a result, the defective rate due to the oxygen concentration unevenness in the silicon wafer can be reduced, which can lead to an improvement in yield.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

1 is a cross-sectional view showing a single crystal ingot manufacturing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the single crystal ingot manufacturing apparatus 100 includes a crucible 10 installed in the chamber 70 and a crucible support 20 supporting the same. The crucible 10 contains a silicon melt 3. The crucible 10 may be formed of a quartz material, and the crucible support 20 may be formed of a graphite material.

The quartz crucible 10 may be rotated clockwise or counterclockwise by the crucible rotation shaft 25. A seed crystal rotating shaft 23 having seed crystals is positioned on the quartz crucible 10, and the seed crystal rotating shaft 23 may rotate in a direction opposite to the rotation direction of the crucible rotating shaft 25.

The seed crystal attached to the seed crystal rotating shaft 23 is immersed in the silicon melt 3, and then the seed crystal rotating shaft 23 is pulled while rotating to grow the single crystal ingot 5. Specifically, the growth process of the single crystal ingot 5 is a necking step of growing an elongated single crystal, that is, a neck portion, from the seed crystal, and shouldering to extend the diameter from the neck portion to the target diameter. Step), a body growth step of growing the ingot axially while maintaining the target diameter, and a tailing step of separating the ingot from the silicon melt.

Adjacent to the crucible support 20 is a resistance heater 30 that heats the quartz crucible 10 is located. The heat insulating material 50 is located outside the heater 30. The resistance heater 30 melts polysilicon to supply heat necessary to make the silicon melt 3, and continuously supplies heat to the silicon melt 3 even during the ingot manufacturing process.

A magnetic field generating device 60 capable of controlling convection of the silicon melt 3 by applying a magnetic field to the silicon melt 3 may be located outside the chamber 70. The magnetic field generator 60 may be a device that generates a horizontal magnetic field in a direction perpendicular to the crystal growth axis of the ingot 5. The magnetic field generating device 60 may be a device for generating a strong magnetic field of about 1500G or more.

FIG. 2A is a diagram illustrating melt flow and temperature distribution when a horizontal magnetic field is applied to a silicon melt, and FIG. 2B is a diagram illustrating melt surface oxygen distribution when a horizontal magnetic field is applied to a silicon melt.

2A and 2B, the melt flow MeF does not appear symmetrically by the horizontal magnetic field MF and proceeds in one direction, so that the melt is divided into two parts by the shape C of the single crystal ingot in contact with the melt. You can see the division. This divides the melt surface into high oxygen and low oxygen concentrations.

When the horizontal magnetic field MF is used in this way, the convection of the melt can be controlled to control the oxygen concentration. However, instantaneous fluctuations may occur in the convection of the silicon melt, which may cause fluctuations in the interstitial oxygen concentration in the crystal growth direction. In this case, the in-plane oxygen concentration distribution may also deteriorate, leading to a decrease in product yield.

Referring back to FIG. 1, a heater power controller 35 may be connected to the resistance heater 30 to adjust the power supplied to the resistance heater 30. The amplitude of power applied to the resistance heater 30 may be adjusted using the heater power controller 35.

For example, the amplitude of the power applied to the resistance heater 30 may be relatively high, about 2 kw or more. In this case, the change amount of heat applied to the crucible 10 may be increased, and thus, the temperature at which the silicon melt 3 is in contact with the crucible 10 may change instantaneously. In this case, an instantaneous temperature difference may occur between the central portion of the silicon melt 3 and the portion where the silicon melt 3 is in contact with the crucible 10, and thus natural convection may occur. Due to this natural convection, the melt may be mixed, and the portion of high oxygen concentration and the portion of low oxygen concentration shown in FIG. 2B may be mixed. As a result, the concentration of oxygen flowing into the single crystal ingot 5 can be made uniform.

The amplitude of the power applied to the resistance heater 30 may be limited to about 40 kw or less for stable power supply. Furthermore, the amplitude of the power applied to the resistance heater 30 may be about 10 kw or more and about 40 kw or less. When the amplitude of the power applied to the resistance heater 30 is increased, the total power applied to the resistance heater 30 may be kept constant by adjusting the period of the power.

Hereinafter, preferred examples are provided to aid the understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited to the following experimental examples.

Ingot growth example 1

In growing single crystal ingots using the Czochralski method, the quartz crucible is rotated clockwise at 0.4 rpm, the crystal seed is rotated counterclockwise at 8 rpm, and the magnetic field generating device generates a horizontal magnetic field of 2000 G. It was. Further, electric power having an amplitude of 0.3 kw and a period of 4.2 s was supplied to the resistance heater to grow the body portion of the single crystal ingot.

Ingot growth example 2

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1, except that the resistive heater was supplied with electric power having an amplitude of 0.33 kw and a period of 3.8 s.

Ingot growth example 3

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1, except that power having an amplitude of 0.35 kw and a period of 3.5 s was supplied to the resistance heater.

Ingot growth example 4

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1 except that the resistance heater was supplied with electric power having an amplitude of 0.5 kw and a period of 3.3 s.

Ingot growth example 5

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1 except that the resistive heater was supplied with power having an amplitude of 2.1 kw and a period of 2.5 s.

Ingot growth example 6

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1 except that the resistance heater was supplied with power having an amplitude of 10.76 kw and a period of 2.1 s.

Ingot growth example 7

The body portion of the single crystal ingot was grown in the same manner as in Experimental Example 1 except that the resistance heater was supplied with electric power having an amplitude of 20.31 kw and a period of 1.4 s.

Ingot growth example 8

The body portion of the single crystal ingot was grown in the same manner as in Experiment 1 except that the resistance heater was supplied with electric power having an amplitude of 40.31 kw and a period of 1.1 s.

After obtaining 20 silicon wafers from the length of the body portion 20 mm of each of the single crystal ingots grown in the ingot growth examples 1 to 8, the oxygen concentration of the central portion of the silicon wafers was measured, and the average value and the variation range of the oxygen concentrations were measured. Obtained and summarized in Table 1 below. Here, the fluctuation range of the oxygen concentration is the difference between the maximum value and the minimum value of the oxygen concentration.

Ingot growth examples Power amplitude
(kw) Power cycle
T (sec) Oxygen concentration fluctuation range
(ppma) Oxygen Concentration Average
(ppma) Ingot growth example 1 (E1) 0.3 4.2 1.43 10.45 Ingot growth example 2 (E2) 0.33 3.8 1.2 10.52 Ingot growth example 3 (E3) 0.35 3.5 0.99 10.48 Ingot growth example 4 (E4) 0.5 3.3 0.8 10.46 Ingot growth example 5 (E5) 2.1 2.5 0.7 10.48 Ingot growth example 6 (E6) 10.76 2.1 0.6 10.54 Ingot growth example 7 (E7) 20.31 1.4 0.6 10.57 Ingot growth example 8 (E8) 40.31 1.1 0.62 10.50

FIG. 3 is a graph based on the values summarized in Table 1, and is a graph showing variation in oxygen concentration according to applied power amplitude.

Referring to Table 1 and FIG. 3, when the amplitude of the power applied to the resistance heater is about 2 kw or more, it can be seen that the variation in oxygen concentration is stabilized to about 0.7 ppma or less and the variation is almost saturated. This trend is more pronounced when the amplitude of the power applied to the resistive heater is about 10 kw or more.

This is because the change in the amount of heat applied to the quartz crucible increases with increasing power amplitude applied to the resistive heater, and thus, natural convection occurs in the silicon melt in which convection is suppressed by the horizontal magnetic field, and consequently, It was expected to be due to the concentration becoming uniform.

4 is a graph showing the defective rate for ingots obtained according to Ingot Growth Examples 1 and 5. FIG. Here, the defective rate is the ratio of the length of the portion where the lattice oxygen concentration is 9 to 13 ppma or more with respect to the total length of the ingot.

Referring to FIG. 4, when the power amplitude is 0.3 kw as in the ingot growth example 1, the defective rate is 2.07%, and when the power amplitude is 2.1 kw as in the ingot growth example 5, the defective rate is 0.15%. From these results, it can be seen that when the power amplitude is about 2 kw or more, the reduction of the defective rate is considerably large, which can lead to the improvement of the yield.

While the invention has been described above with reference to specific preferred embodiments, it is intended that the specific modifications and variations of the invention fall within the scope of the invention and the specific scope of the invention will be apparent from the appended claims.

1 is a cross-sectional view showing a single crystal ingot manufacturing apparatus according to an embodiment of the present invention.

FIG. 2A is a diagram illustrating melt flow and temperature distribution when a horizontal magnetic field is applied to a silicon melt, and FIG. 2B is a diagram illustrating melt surface oxygen distribution when a horizontal magnetic field is applied to a silicon melt.

FIG. 3 is a graph based on the values summarized in Table 1, and is a graph showing variation in oxygen concentration according to applied power amplitude.

4 is a graph showing the defective rate for ingots obtained according to Ingot Growth Examples 1 and 5. FIG.

Claims (8)

Applying a magnetic field to the melt contained in the crucible, The electric power applied to the heater for supplying heat to the crucible is periodically changed to generate a temperature difference between a portion of the melt contacting the crucible and a central portion of the melt, and the melt is mixed. A single crystal ingot growth method comprising pulling a single crystal ingot from the melt. The method of claim 1, Single crystal ingot growth method for applying power having an amplitude of 2kw or more to the heater. 3. The method of claim 2, Single crystal ingot growth method for applying power having an amplitude of 40kw or less to the heater. 3. The method of claim 2, Single crystal ingot growth method for applying power having an amplitude of 10kw or more to the heater. The method of claim 1, Wherein said magnetic field is a horizontal magnetic field. The method of claim 5, The horizontal magnetic field is more than 1500G single crystal ingot growth method. delete delete

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