KR20180101586A - Manufacturing method of silicon single crystal - Google Patents

Abstract

A method of manufacturing a silicon single crystal by a Czochralski method is disclosed in which the occurrence of an epitaxial defect occurs when used as a substrate material of an epitaxial silicon wafer while preventing a decrease in the single crystalization ratio due to crystal warpage or cutting separation from a melt .
[MEANS FOR SOLVING PROBLEMS] A method for manufacturing a quartz crucible comprising a body part growing step for growing a body part (3c) having a constant crystal diameter and a step for raising a step part (3d) with a gradually reduced crystal diameter, Pulled up from the silicon melt 2 by using the water cooling body 18 disposed inside the heat shield 17 above the lower end 17b of the heat shield 17 disposed above the silicon monocrystals 3 ). In the tail portion growing step, the silicon single crystal 3 is pulled up at the same pulling speed as the pulling speed at the termination of the body portion growth from the start to the end of the growth of the tail portion 3d.

Description

Manufacturing method of silicon single crystal

The present invention relates to a method of producing a silicon single crystal by a chiral key method (hereinafter referred to as a CZ method), and more particularly to a method of growing a tail portion of a silicon single crystal ingot.

Background Art Epitaxial silicon wafers are widely used as substrate materials for semiconductor devices. The epitaxial silicon wafer is obtained by forming an epitaxial layer on the surface of a bulk silicon substrate. Since the epitaxial silicon wafer has high crystal completeness, it is possible to manufacture a semiconductor device of high quality and high reliability.

Most of the silicon single crystal serving as the substrate material of the epitaxial silicon wafer is produced by the CZ method. In the CZ method, a raw material such as polycrystalline silicon is filled in a quartz crucible, and the silicon raw material is heated and melted in the chamber. Then, the seed crystal adhered to the lower end of the pulling axis is lowered from above the quartz crucible, brought into contact with the silicon melt, and the seed crystals are gradually raised while rotating the seed crystal and the quartz crucible, A large diameter single crystal is grown under the termination definition.

As a method of manufacturing an epitaxial silicon wafer, for example, Patent Document 1 discloses a method of manufacturing a silicon single crystal ingot in which the temperature range of 1030 to 920 占 폚 during pulling is set at a cooling rate of 1.0 占 폚 / min or more, The silicon single crystal is grown at a cooling rate of 0.5 deg. C / min or less, and then an epitaxial layer is formed on the surface of the wafer cut out from the single crystal. An epitaxial defect due to OSF (hereinafter, referred to as an " epitaxial defect ") is generated by rapidly passing through a temperature region (1030 to 920 ° C) in which nuclei of OSF (Oxygen induced stacking fault) ) Can be suppressed.

In the single crystal pulling up process, a necking process for finely contraction of the crystal diameter by a dash neck method in order to disjoint single crystals, a step for gradually increasing the crystal diameter, a body portion growing process for growing crystal while a crystal diameter is kept constant, and a tail portion growing process for gradually reducing the crystal diameter and forming a conical tail portion are performed in sequence. Among these processes, the step of growing the crystal grains is a process in which the thermal balance between the melt and the single crystal at the crystal growth interface is collapsed, a sharp thermal shock is applied to the crystal, and quality defects such as slip dislocation and oxygen precipitation abnormality are prevented This is a necessary step for cutting and separating the single crystal from the melt.

Regarding the tail portion growing process, for example, Patent Document 2 discloses that the pulling rate of the terminal cone portion of the ingot (the tail portion) is set at a relatively constant speed equivalent to the pulling speed of the second half of the ingot body portion (body portion) Crystal silicon ingot having a uniform heat history (heat history) is produced by increasing the power (heat amount) supplied to the heater, or decreasing the crystal rotation speed or the crucible rotation speed, if necessary have.

(Patent Document 1) Japanese Patent Application Laid-Open No. 2010-30856 (Patent Document 2) Japanese Patent Laid-Open No. 10-95698

In Patent Document 1, a single crystal pulling apparatus provided with a water-cooled body is used, and the pulling rate at the time of growing the single crystal and the temperature gradient in the pulling axis direction of the single crystal immediately after crystallization are controlled. However, the portion used as the substrate material of the epitaxial silicon wafer is a body portion (straight body portion) in which the crystal diameter is kept constant, and the tail portion is a portion not used as a wafer product. Therefore, although the cooling condition of the body portion is described in Patent Document 1, the specific pulling conditions such as the pulling speed, the heater power, and the rotating speed of the single crystal in the tees are not described.

In the cultivation of the tail portion, control is generally performed in which the pulling speed of the single crystal is increased to gradually shrink the crystal diameter. The tailing shrinkage can be easily performed by increasing the pulling rate of the single crystal, and further, the period of growing the tail portion is shortened, leading to a reduction in the manufacturing cost. Also, as described above, the tail portion is a portion that is not a wafer product, and even if the crystal quality of the tee itself deteriorates by raising the pulling speed, it does not become a problem. For this reason, in the conventional general tail portion growing process, control for increasing the pulling speed of the single crystal is being performed, and in Patent Document 1, it is considered that the condition that tends to tail taper is adopted.

However, when the pulling speed of the single crystal is increased in the step of growing the single crystal, there is a risk that the crystal deflection (bending) or the single crystal is suddenly cut off from the silicon melt and thus the single crystal is damaged.

Patent Document 2 discloses that the pulling-up speed of the tail portion is maintained at a relatively constant speed equivalent to the pulling-up speed of the latter half of the body portion. As described above, the control for keeping the pulling speed of the tail portion constant is considered to have a relatively constant cooling rate and residence time over the entire body portion of the single crystal at a glance.

However, when the pulling speed of the tail portion is set to the same speed as that of the body portion, the pulling speed of the single crystal is slower than that of the conventional tail portion growing process, so that the silicon single crystal pulled up from the silicon melt stays in the OSF nucleation temperature region The time actually becomes longer, and there is a fear that the epitaxial defect is increased.

In addition, the crystal diameter gradually decreases in the step of raising the tail portion, so that the distance D between the heat shield 17 and the silicon single crystal 3 is widened as shown in Fig. 8 and the heat from the silicon melt 2, The silicon single crystal 3 is diffused upward as indicated by a white arrow, and the temperature of the periphery of the silicon single crystal 3 immediately after crystallization is increased. Under such an environment, when the tail portion 3d of the silicon single crystal 3 is slowly pulled up at the same pulling speed as that of the body portion 3c, the influence of the high temperature around the silicon single crystal 3 becomes larger. That is, the time taken for the silicon single crystal 3 pulled up from the silicon melt 2 to stay in the OSF nucleation temperature region becomes longer, and the epitaxial defect is increased.

Furthermore, unlike the case where the body portion 3c is pulled up, the state of the frame portion 3d is reduced due to a decrease in the crystal diameter and the state of pulling up the crystal instantaneously. In addition, since the amount of the melt in the crucible is small, the melt is retained (held) in the bottom of the crucible, so that the state of the melt in the crucible also changes momentarily with the progress of pulling of the tail portion 3d, easy. Therefore, when the frame portion 3d is pulled up at the same speed as that of the body portion 3c, the time required until the completion of the pulling up of the frame portion 3d becomes very long, There is a problem that it is increased.

It is therefore an object of the present invention to provide a method for manufacturing a silicon single crystal capable of suppressing the occurrence of an epitaxial defect when used as a substrate material of an epitaxial silicon wafer while preventing deterioration of the single crystalization ratio due to crystal warpage or cutting- And to provide a method.

In order to solve the above problems, a manufacturing method of a silicon single crystal according to the present invention is a manufacturing method of a silicon single crystal by a Czochralski method for pulling up a silicon single crystal from a silicon melt in a quartz crucible, And a step of raising a tail portion in which a crystal portion having a gradually decreasing crystal diameter is grown. The method of manufacturing a quartz crucible according to any one of claims 1 to 3, The silicon single crystal being pulled up from the silicon melt by using a sieve to cool the silicon single crystal, and in the step of raising the tail portion, the step of raising the tail portion is completed, And the silicon single crystal is pulled up.

As the crystal diameter gradually decreases in the tail portion growing process, the lateral gap between the heat shield and the single crystal is gradually widened so that the heat shielded by the heat shield is diffused upward, and the silicon single crystal is not cooled well . Further, in the case of stopping the rise of the quartz crucible in order to avoid contact between the heat shield and the crucible in the tail portion growing process, the distance between the heat shield and the melt surface is gradually widened by the lowering of the melt surface, The radiant heat of the light emitting diode is more likely to spread upward. Therefore, the crystal quality of the body part in the vicinity of the tees is influenced by heat and is different from the crystal quality of the top side. That is, the stay time in the temperature range of 1020 to 980 占 폚 becomes long and becomes a slow cooling state, and crystal containing a large OSF nucleus, which easily causes an epitaxial defect, is obtained.

However, according to the present invention, since the water cooling body is provided around the lifting path above the heat shield, the lifting speed of the single crystal is not increased, and the period during which the silicon single crystal immediately after crystallization stays in the OSF nucleation temperature region can be shortened have. Therefore, it is possible to manufacture a silicon single crystal capable of suppressing the decrease in the single crystalization ratio due to crystal defects or crystals being separated from the melt and separating, and suppressing the occurrence of epitaxial defects at the time of forming the epitaxial layer.

In the step of raising the tessellation, it is preferable that the temperature range from 1020 ° C to 980 ° C of the body portion of the silicon single crystal is passed within 15 minutes. As described above, the silicon single crystal pulled up from the silicon melt quickly passes through the OSF nucleation temperature region, so that the OSF nucleus size in the silicon single crystal can be reduced. Therefore, when the epitaxial layer is formed on the surface of the silicon wafer cut out from the single crystal ingot, generation of epi-defects due to OSF can be suppressed.

The method for manufacturing a silicon single crystal according to the present invention is characterized in that the power of the heater for heating the silicon melt is gradually increased from the start to the end of the growth of the tail portion and at the same time, It is preferable that the power is set to be not less than 1.1 times and not more than 1.5 times the power of the heater at the start of cultivation of the tail portion. According to this, tail shrinkage can be realized while avoiding crystal bending or cutting and separation of the single crystal from the silicon melt.

It is preferable that the quartz crucible is elevated so that the interval between the heat shield and the silicon melt becomes constant in the teeming step. The quartz crucible is elevated up to the end of the tail finishing step to keep the height position of the melt surface constant so that the influence of radiant heat from the quartz crucible can be suppressed and expansion of the OSF nucleation temperature region can be suppressed.

It is preferable that the rotational speed of the quartz crucible or the silicon single crystal is kept constant in the step of raising the tail portion, and it is also preferable to apply a magnetic field to the silicon melt. Since the amount of the melt in the quartz crucible is small and the melt is retained in the bottom of the crucible, the effect of the change in the rotational speed of the quartz crucible is susceptible to the melt and the state of the melt is unstable. By keeping the speed constant, it is possible to stabilize the melt state and reduce the risk of the dielectric loss of the silicon single crystal. Likewise, by stabilizing the rotation speed of the silicon single crystal or by applying a magnetic field to the silicon melt, stabilization of the melt state in the step of raising the tail portion can be achieved, and the risk of dielectric loss of the silicon single crystal can be reduced. Further, the rotation speed of the quartz crucible and the silicon single crystal should be substantially constant, and variation within ± 2 rpm is acceptable.

According to the present invention, there is provided a method of manufacturing a silicon single crystal capable of suppressing the occurrence of an epi-defect when used as a substrate material of an epitaxial silicon wafer while preventing a decrease in the single crystalization ratio due to crystal bending or cutting separation from the melt can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view schematically showing a configuration of a single crystal manufacturing apparatus according to a first embodiment of the present invention; FIG.
2 is a flow chart for explaining a method of manufacturing a silicon single crystal according to an embodiment of the present invention.
3 is a schematic cross-sectional view showing the shape of a silicon single crystal ingot.
4 is a schematic cross-sectional view showing the pull-up state of the single crystal during the tail portion growing process.
FIG. 5 is a sequence diagram showing changes in pulling rate and heater power of a single crystal.
6 is a side sectional view schematically showing a configuration of a single crystal producing apparatus according to a second embodiment of the present invention.
7 is a graph showing the relationship between the pull-up position of the single crystal and the passing time of the OSF nucleation temperature region (1020 to 980 ° C region) of the single crystal.
Fig. 8 is a schematic view for explaining a conventional problem in the teat portion growing process. Fig.

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

1 is a side sectional view schematically showing a configuration of a single crystal manufacturing apparatus according to a first embodiment of the present invention.

1, the single crystal manufacturing apparatus 1A includes a chamber 10, a quartz crucible 11 for holding the silicon melt 2 in the chamber 10, a quartz crucible 11 A rotating shaft 13 for supporting the susceptor 12; a shaft driving mechanism 14 for rotating and raising and rotating the rotating shaft 13; and a susceptor 12 A heat insulating material 16 disposed along the inner surface of the chamber 10 as an outer side of the heater 15 and a heat shielding material 17 disposed above the quartz crucible 11 A water cooling body 18 provided inside the heat shield 17 above the lower end of the heat shield 17 and a water cooling body 18 provided above the quartz crucible 11 and provided with a single crystal impression And a wire winding mechanism 20 disposed above the chamber 10. The wire winding mechanism 20 includes a wire winding mechanism 19 and a wire winding mechanism 20 disposed above the chamber 10. [

The single crystal manufacturing apparatus 1A further comprises a magnetic field generating device 21 disposed outside the chamber 10, a CCD camera 22 for photographing the inside of the chamber 10, and an image picked up by the CCD camera 22 And a control section 24 for controlling the shaft driving mechanism 14, the heater 15 and the wire winding mechanism 20 on the basis of the output of the image processing section 23.

The chamber 10 is composed of a main chamber 10a and an elongated cylindrical pool chamber 10b connected to the upper opening of the main chamber 10a. The chamber 10 includes a quartz crucible 11, a susceptor 12, (15) and a heat shield (17) are provided in the main chamber (10a). A gas inlet 10c for introducing an inert gas (purge gas) such as argon gas into the chamber 10b is provided in the pull chamber 10b. A gas for discharging the inert gas is provided in the lower portion of the main chamber 10a. And an outlet 10d is provided. An observation window 10e is provided on the upper portion of the main chamber 10a so that the growth condition (solid-liquid interface) of the silicon single crystal 3 can be observed from the observation window 10e.

The quartz crucible 11 is a container made of quartz glass having a cylindrical sidewall portion and a curved bottom portion. The susceptor 12 is kept in close contact with the outer surface of the quartz crucible 11 so as to surround the quartz crucible 11 in order to maintain the shape of the quartz crucible 11 softened by heating. The quartz crucible 11 and the susceptor 12 constitute a crucible having a dual structure for supporting the silicon melt in the chamber 10.

The susceptor 12 is fixed to the upper end of the rotating shaft 13 extending in the vertical direction. The lower end of the rotating shaft 13 is connected to a shaft driving mechanism 14 provided on the outside of the chamber 10 through the center of the bottom of the chamber 10. The susceptor 12, the rotating shaft 13, and the shaft driving mechanism 14 constitute a rotating mechanism and a lifting mechanism of the quartz crucible 11.

The heater 15 is used to melt the silicon raw material filled in the quartz crucible 11 to produce the silicon melt 2. [ The heater 15 is a resistance heating heater made of carbon and is provided so as to surround the quartz crucible 11 in the susceptor 12. Further, the outer side of the heater 15 is surrounded by the heat insulating material 16, whereby the warmth in the chamber 10 is enhanced.

The heat shield 17 prevents temperature fluctuations of the silicon melt 2 to form an appropriate hot zone in the vicinity of the solid-liquid interface and also prevents the heat of the heater 15 and the quartz crucible 11 Is provided to prevent the heating of the silicon single crystal (3). The heat shield 17 is a graphite member that covers the upper region of the silicon melt 2 except for the pulling path of the silicon single crystal 3 and has a reverse truncated conical shape whose diameter is reduced downward.

A circular opening 17a having a diameter larger than the diameter of the silicon single crystal 3 is formed at the bottom center of the heat shield 17 so that the lifting path of the silicon single crystal 3 is secured. As shown in the figure, the silicon single crystal 3 is pulled upward through the opening 17a. Since the diameter of the opening 17a of the heat shield 17 is smaller than the diameter of the quartz crucible 11 and the lower end of the heat shield 17 is located inside the quartz crucible 11, the heat shield 17 does not interfere with the quartz crucible 11 even if the upper end of the rim is raised above the lower end of the heat shield 17. [

The amount of the melt in the quartz crucible 11 decreases with the growth of the silicon single crystal 3 and the quartz crucible 11 is elevated so that the interval (gap? G) between the melt surface and the heat shield 17 becomes constant, The evaporation amount of the dopant from the silicon melt 2 can be controlled by suppressing the temperature fluctuation of the silicon melt 2 and keeping the gas flow rate in the vicinity of the melt surface (purge gas guiding path) constant. Therefore, it is possible to improve the stability of the crystal defect distribution, the oxygen concentration distribution, the resistivity distribution, etc. in the pull axis direction of the single crystal.

The water-cooling body 18 is disposed inside the heat shield 17 above the lower end 17b of the heat shield 17. The water- Like the heat shield 17 and the like, the water cooling body 18 is provided so as to surround the pulling path of the silicon single crystal 3. The water-cooling body 18 is preferably made of a metal having good thermal conductivity, such as copper, iron, stainless steel (SUS), or molybdenum, and is preferably capable of maintaining the surface temperature from room temperature to about 200 캜 Do. The details will be described later. The cooling of the silicon single crystal 3 immediately after the crystallization can be promoted by the presence of the water-cooling body 18.

A wire 19 as a pulling axis of the silicon single crystal 3 and a wire winding mechanism 20 for winding the wire 19 are provided above the quartz crucible 11. The wire winding mechanism 20 has a function of rotating the single crystal together with the wire 19. [ The wire retracting mechanism 20 is disposed above the pull chamber 10b and the wire 19 extends downward from the wire retracting mechanism 20 through the pull chamber 10b, Reaches the inner space of the main chamber 10a. Fig. 1 shows a state in which the silicon single crystal 3 is suspended on the wire 19 during the growing. At the time of pulling the single crystal, the seed crystal is immersed in the silicon melt 2, and the single crystal is grown by gradually pulling the wire 19 while rotating the quartz crucible 11 and the seed crystal.

A gas inlet 10c for introducing inert gas into the chamber 10 is provided in the upper portion of the pull chamber 10b and a gas inlet 10c for exhausting the inert gas in the chamber 10 is provided at the bottom of the main chamber 10a. And an outlet 10d is provided. The inert gas is introduced into the chamber 10 from the gas inlet 10c, and the introduction amount thereof is controlled by the valve. The inert gas in the sealed chamber 10 is exhausted from the gas outlet 10d to the outside of the chamber 10 so that SiO gas or CO gas generated in the chamber 10 is recovered to clean the inside of the chamber 10 . Although not shown, a vacuum pump is connected to the gas outlet 10d through a pipe. By controlling the flow rate of the inert gas in the chamber 10 with the vacuum pump, the chamber 10 is maintained in a constant reduced pressure state .

The magnetic field generating device 21 applies a horizontal magnetic field or a vertical magnetic field to the silicon melt 2. By applying a magnetic field to the silicon melt (2), melt convection in a direction orthogonal to the magnetic force lines can be suppressed. Therefore, the elution of oxygen from the quartz crucible 11 can be suppressed, and the oxygen concentration in the silicon single crystal can be reduced.

An observation window 10e for observing the inside of the main chamber 10a is provided at an upper portion of the main chamber 10a and a CCD camera 22 is provided outside the observation window 10e. The CCD camera 22 takes an image of the boundary portion between the silicon single crystal 3 and the silicon melt 2 through the opening 17a of the heat shield 17 from the observation window 10e during the single crystal pulling process. The CCD camera 22 is connected to the image processing section 23 and the photographed image is processed in the image processing section 23 and the processing result is used for control of the pulling condition in the control section 24. [

2 is a flow chart for explaining a method of manufacturing a silicon single crystal according to an embodiment of the present invention. 3 is a schematic cross-sectional view showing the shape of a silicon single crystal ingot.

As shown in Figs. 2 and 3, in the production of the silicon single crystal 3, the silicon raw material in the quartz crucible 11 is heated to produce the silicon melt 2 (step S11). Thereafter, the seed crystal adhered to the tip end portion of the wire 19 is lowered and immersed in the silicon melt 2 (step S12).

Then, the seed crystal is pulled up slowly while maintaining contact with the silicon melt 2, and the single crystal is pulled up to grow the single crystal. In the step of pulling up a single crystal, a necking step (step S13) for forming a neck part 3a in which a crystal diameter is narrowly reduced (reduced) for non-electrification (step S13) and a step for forming a shoulder part 3b (Step S15) of forming a body portion 3c with a constant crystal diameter maintained, and a stepped portion 3d having a gradually decreasing crystal diameter (Step S16) are successively carried out, and the single crystal is finally cut off from the melt surface to complete the teat portion growing process. As described above, the silicon monocrystalline ingot 3 having the neck portion 3a, the shoulder portion 3b, the body portion 3c, and the frame portion 3d in order from the upper end (top) of the single crystal to the lower end (bottom) Is completed.

An image of the boundary between the silicon single crystal 3 and the silicon melt 2 is formed by the CCD camera 22 in order to control the diameter of the silicon single crystal 3 and the liquid surface position of the silicon melt 2 during the single crystal pull- And the diameter of the single crystal at the solid-liquid interface and the gap (gap? G) between the melt surface and the heat shield 17 are calculated from the photographed image. The control unit 24 controls the pulling conditions such as the pulling speed of the wire 19 and the power of the heater 15 so that the diameter of the silicon single crystal 3 becomes the target diameter. The control unit 24 also controls the height position of the quartz crucible 11 so that the interval between the melt surface and the heat shield 17 becomes constant.

4 is a schematic cross-sectional view showing the pull-up state of the single crystal during the tail portion growing process.

As shown in Fig. 4, since the silicon single crystal 3 is cut and separated from the silicon melt 2 in the non-electric potential state, the crystal diameter gradually decreases with the progress of pulling up in the tail portion growing step, The distance D between the silicon single crystal 3 and the silicon single crystal 3 is gradually widened. The width of the heat radiation path extending upward from the silicon melt 2 is widened and the heat is more easily diffused to the upper side than the lower end 17b of the heat shield 17. Therefore, The temperature of the space above the space becomes higher. Thus, the upper portion of the heat shield 17 is heated, and the heat shield 17 itself becomes a heat source, and the silicon single crystal 3 immediately after the crystallization is heated. In this state, the silicon single crystal 3 can not quickly pass through the temperature range (OSF nucleation temperature region) of 1020 to 980 DEG C in which the OSF nucleus is likely to be formed in the single crystal, and the pulling rate of the silicon single crystal 3 is slowed It becomes more difficult in case.

In this embodiment, however, since the water-cooling body 18 is provided on the inner side 17i of the heat shield body 17 above the lower end 17b of the heat shield body 17, the lower ends 17b ) Can be lowered and the width of the crystal growth direction in the temperature region of 1020 to 980 캜 can be narrowed. Therefore, even when the pulling speed of the silicon single crystal 3 is made slower than the conventional one, the time for the silicon single crystal 3 to stay in the temperature range of 1020 to 980 占 폚 can be shortened and the OSF nucleation temperature region is quickly passed, The size of the OSF nuclei can be made very small.

Fig. 5 is a sequence diagram showing changes in the pulling rate of the silicon single crystal 3 and the power of the heater 15. Fig.

As shown in Fig. 5, the pulling speed of the silicon single crystal 3 is constantly controlled from the body portion 3c to the tail portion 3d. In addition, a constant pulling rate during the tail portion growing process means that the variation rate with respect to the pulling rate at the beginning of the tail portion growing process is within ± 3%.

In the conventional general tail portion growing process, the pulling speed is increased faster than the body portion growing process, and the power of the heater 15 is supplementarily increased to shrink the crystal diameter finely. However, in the present embodiment, the tail shrinkage is achieved by changing only the power of the heater 15 without changing the pulling speed. Thus, by keeping the pulling rate constant from the start to the end of the growth of the tail portion 3d, it is possible to prevent the generation of dielectric wirings of the single crystal due to crystal warpage or cutting separation from the melt.

When the pulling speed of the tail portion 3d is set at the constant speed and the pulling speed of the body portion 3c, it is difficult to control the tail shrinkage. However, since the power of the heater 15 is increased and the silicon melt 2 is hard to solidify It is easy to shrink the tail by creating the situation. When the power of the heater 15 is increased, the influence of the radiant heat becomes stronger. In the absence of the water-cooling body 18, the OSF nucleation temperature region of 1020 to 980 캜 is widened as described above. However, by providing the water-cooling body 18 as described above, the OSF nucleation temperature region can be narrowed, and the passage time (stay time) of the OSF nucleation temperature region of the silicon single crystal 3 can be shortened.

As described above, the power of the heater 15 during the tail portion growing process is larger than that of the heater 15 at the end of the body portion growing process. Particularly, the power of the heater 15 is gradually increased from the start of the teat portion cultivation, and the power of the heater 15 at the teat partial cultivation termination is preferably 1.1 to 1.5 times at the beginning of the teat portion cultivation. In this way, the power of the heater 15 in the tail portion growing process is gradually increased, and the power of the heater 15 at the end of the tail portion growing is made to fall within the range of 1.1 to 1.5 times at the start of the growing , The tail shrinkage can be realized even when the pulling speed of the tail portion 3d is set at a constant speed with the body portion 3c. Further, crystal warpage and dielectric loss can be prevented.

It is preferable to gradually raise the quartz crucible 11 so as to keep the liquid surface position of the silicon melt 2 constant. Conventionally, since the remaining amount of the silicon melt 2 in the quartz crucible 11 is decreased as much as possible to increase the single crystallization rate, the step of growing the tessellation is carried out, so that the quartz crucible 11 is placed at a sufficiently high position When the quartz crucible 11 is further raised, the quartz crucible 11 interferes with the heat shield 17. Therefore, it is necessary to stop the rising of the quartz crucible 11 at the start of the teeming step or in the middle of the step of growing the crystal, so that the distance between the melt surface and the heat shield 17 is widened by the lowering of the melt surface, It is easily influenced by the radiant heat from the quartz crucible 11, and there is a problem that the OSF nucleation temperature region is expanded.

However, in the present embodiment, the tee portion growing process is started before the silicon melt 2 is sufficiently consumed, and the quartz crucible 11 is raised until the end of the tee portion growing process to keep the height position of the melt surface constant , The influence of the radiant heat from the quartz crucible 11 can be suppressed, and the expansion of the OSF nucleation temperature region can be suppressed.

During crystal growth, the crystal diameter gradually decreases and the crystal pulling state changes instantaneously, so that the silicon single crystal (3) is liable to cause dielectric loss. In the case where the pulling speed during the partial cultivation is made slower than the conventional one, the time for the partial cultivating process becomes long, and the risk of genetic wasting further increases. In order to minimize the risk of genetic wasting under these conditions, it is preferable to keep the rotational speeds of the silicon single crystal 3 and the quartz crucible 11 constant in the tail portion growing process. These rotational speeds may be the same as or different from the rotational speed in the body part growing step. Thus, the convection of the silicon melt 2 in the quartz crucible 11 can be stabilized, and the melt temperature can be stabilized.

It is preferable to operate the magnetic field generating device 21 to apply a horizontal magnetic field or a vertical magnetic field to the silicon melt 2 even in the teeming process. By doing so, convection of the silicon melt 2 in the quartz crucible 11 can be further stabilized. Since the tail portion 3d of the silicon single crystal 3 is not used as a product and the commercialized region is the body portion 3c, a magnetic field is applied in the tail portion growing step S16 to adjust the oxygen concentration level and the in- There is no need to control the quality of determination of distribution, etc. It is important to quickly cut off the silicon melt 2 from the silicon melt 2 so as not to deteriorate the quality of the body portion 3c of the silicon single crystal 3 that has been cultivated so far in the tail portion growing step S16. However, in the case where a magnetic field is applied during the tail portion growth, the convection of the silicon melt 2 in the quartz crucible 11 can be stabilized and the melt temperature can be stabilized, thereby preventing crystal warpage and dielectric loss. .

6 is a side sectional view schematically showing a configuration of a single crystal producing apparatus according to a second embodiment of the present invention.

6, the monocrystal production apparatus 1B is characterized in that the water-cooling body 18 is made of a cylindrical member sufficiently long as compared with the first embodiment, and the upper end of the main chamber (the lower end of the pull chamber) And reaches the inside 17i of the heat shield 17 surrounded by the one-dot chain line in the figure. That is, the water-cooling body 18 is provided so as to cover the lifting path of the silicon single crystal 3 as long as possible.

The lower end 17b of the heat shielding body 17 is located above the lower end 17b of the heat shielding body 17 because the water cooling body 18 is present on the inside 17i of the heat shielding body 17 above the lower end 17b of the heat shielding body 17. [ The temperature of the high temperature region after passing through the openings of the crystal grains can be reduced and the width of the crystal growth direction in the temperature region of 1020 to 980 ° C can be narrowed. Therefore, even when the pulling speed of the silicon single crystal 3 is made slower than the conventional one, the time for the silicon single crystal 3 to stay in the temperature range of 1020 to 980 占 폚 can be shortened and the OSF nucleation temperature region is quickly passed, The size of the OSF nuclei can be made very small.

As described above, in the method of manufacturing the silicon single crystal according to the present embodiment, the water-cooling body 18 is disposed inside the heat shield 17 above the lower end 17b of the heat shield 17, The silicon single crystal 3 immediately after crystallization is cooled by the water cooling body 18 and the tail portion 3d is lifted up at a constant speed with the body portion 3c in the step of growing the tail portion, It is possible to manufacture a silicon single crystal of high quality with a very small amount of OSF nuclei, which causes an epitaxial defect while preventing breakage or cutting off from the melt.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and alternative arrangements included within the spirit and scope of the appended claims. Needless to say.

Example

The rate of single crystalization and the occurrence of epi-defects were evaluated in accordance with the difference between the pulling rate of the single crystal and the presence or absence of the water-cooling body 18 in the tail growing process. In this evaluation test, Samples 1 to 6 of a silicon single crystal ingot having a diameter of 300 mm were pulled up using the single crystal manufacturing apparatus 1A shown in Fig. At this time, the pulling speed of the body part was set to 1.0 mm / min, and the pulling of the single crystal was performed while the quartz crucible was elevated so that the interval between the melt surface and the lower end of the heat shielding body became constant not only during the body part growing, .

In the samples 1 and 2, the pulling speed of the tail portion 3d was set to be higher (1.1 times) than that of the body portion 3c. In the samples 3 and 4, the pulling speed of the tail portion 3d was set to be the same as the body portion 3c. In the samples 5 and 6, the pulling speed of the tail portion 3d was lower than that of the body portion 3c by 0.9 times. Respectively. In Samples 1, 3 and 5, pulling was performed using the single crystal manufacturing apparatus 1A from which the water cooling body 18 was removed, and in the samples 2, 4 and 6, the water cooling body 18 was grounded. (1A).

Then, Samples 1 to 6 of the silicon single crystal ingot thus obtained were processed to prepare a silicon wafer (polished wafer) having a thickness of 775 탆, and an epitaxial layer having a thickness of 4 탆 was formed on the surface of the silicon wafer. To prepare a corresponding epitaxial silicon wafer. Then, the number of epitaxial defects of each epitaxial silicon wafer was measured by a particle counter.

Table 1 is a table showing the results of evaluation tests of the single crystallization rate and the epi-defects of Samples 1 to 6.

Sample Impression speed Presence or absence of cooling body Monocrystallization rate Epitaxial defect
Occurrence One high speed none × - 2 high speed has exist × - 3 Constant velocity none More than 75% 5 to 10 / wf 4 Constant velocity has exist More than 75% 5 pieces / wf  under 5 sleaze none More than 75% Greater than 10 / wf 6 sleaze has exist More than 75% Greater than 10 / wf

As shown in Table 1, in the sample 1 produced by raising the pulling speed of the tail portion 3d to be higher than that of the body portion 3c without using the water cooling body 18, the cutting from the silicon melt of the tail portion 3d Separation occurred, and the single crystalization ratio deteriorated. Further, in the sample 2 produced using the water-cooling body 18 and the pulling speed of the stepped portion 3d higher than that of the body portion 3c, cutting separation of the stepped portion 3d from the silicon melt occurred, The rate deteriorated. Therefore, it was not possible to evaluate the occurrence status of the epi-defects of the samples 1 and 2. The sample 3 in which the pulling speed of the tail portion 3d was set at a constant speed with the body portion 3c without using the water cooling body 18 had a single crystalization rate of 75% or more, and the number of the epi- / wf. The sample 4 in which the water-cooling body 18 was used and the pulling speed of the tail part 3d was set at the constant speed with the body part 3c had a single crystalization rate of 75% or more and the number of the epi- , And it was confirmed that the quality criteria of the epitaxial defect were satisfied.

In Samples 5 and 6, in which the pulling speed of the tail portion 3d was made lower than that of the body portion 3c, the single crystalization ratio was 75% or more regardless of whether the water-cooling body 18 was used or not. However, 10 / wf.

From the above results, it can be seen that both of the single crystalization rate and the quality of the epitaxial defect can be satisfied in the sample 4 in which the water-cooling body 18 is used and the pulling speed of the tail portion 3d is set to the constant speed of the body portion 3c .

Next, a simulation was performed on the influence of the interval between the melt surface and the heat shield 17 on the temperature gradient of the crystal growth direction of the single crystal under the condition of the sample 4 described above.

7 is a graph showing the relationship between the pull-up position of the single crystal and the passing time of the OSF nucleation temperature region (1020 to 980 ° C region) of the single crystal. The abscissa of the graph in Fig. 7 represents the distance from the bottom of the single crystal (the lower end of the frame portion 3d), and the ordinate represents the passage time of the OSF nucleation temperature region.

7, the quartz crucible 11 is raised against the condition that the gap (gap G) between the melt surface and the heat shield 17 is enlarged, that is, the lowering of the melt surface, and the melt surface and the heat shield 17 are not controlled to be constant, it can be seen that the pass time of the OSF nucleation temperature region of the single crystal becomes longer as the pull-up position is closer to the bottom. Since the pulling speed of the tail portion 3d is constant, the passage time of the OSF nucleation temperature region is long, which means that the OSF nucleation temperature region expands in the pulling axis direction as the pulling position approaches the bottom.

On the contrary, under the condition that the interval between the melt surface and the heat shield 17 is made constant, the passing time of the OSF nucleation temperature region of the single crystal is not so long even if the pulling position is close to the lower end of the tail portion 3d . From the above results, it was confirmed that the expansion of the OSF nucleation temperature region can be suppressed by keeping the interval between the melt surface and the heat shield 17 constant in the teed portion growing process.

Next, the influence of the difference in the output of the heater 15 during the tail finishing step on the quality of the single crystal was evaluated. When the power of the heater 15 at the beginning and the end of the teeming are respectively CkW and DkW, the heater power ratio D / C is varied within a range from 0.9 to 1.8 in the evaluation test. The other pulling conditions were the same as those in the evaluation test of the above-described single crystal ratio and the epitaxial defect.

Table 2 shows the results of the evaluation test of the crystal growth condition according to the difference in the heater power ratio.

As shown in Table 2, when the heater power ratio D / C was less than 1.1, tail shrinkage could not be achieved. Further, when the heater power ratio D / C exceeds 1.5, crystal bending (bending) occurs, and the frame portion 3d can not be trimmed into a neat cone shape. On the other hand, when the heater power ratio D / C is in the range of 1.1 to 1.5, tail shrinkage can be performed and the tail portion 3d can be grown.

From the above results, it can be seen that the heater power ratio D / C at the end of the teat partial cultivation at the start of the teat portion cultivation is 1.1 to 1.5, and the heater power during the teat portion cultivation is higher than the silicon content When a single crystal is grown, a tail portion of a neat shape can be grown, and crystal bending or cutting and separation of the single crystal from the silicon melt does not occur.

1A, 1B: Single crystal manufacturing apparatus
2: Silicon melt
3: Silicon single crystal (ingot)
3a: neck portion
3b: Shoulder portion
3c:
3d: teabag
10: chamber
10a: main chamber
10b: full chamber
10c: gas inlet
10d: gas outlet
10e: Observation window
11: Quartz crucible
12: susceptor
13: rotating shaft
14: Shaft driving mechanism
15: Heater
16: Insulation
17: Thermal Shield
17a: opening of the heat shield
17b: the bottom of the heat shield
17i: inside of heat shield
18: water-cooled
19: Wire
20: wire winding mechanism
21: magnetic field generator
22: CCD camera
23:
24:

Claims (7)

1. A method for producing a silicon single crystal by a Czochralski method for pulling up a silicon single crystal from a silicon melt in a quartz crucible,
A body part growing step of growing a body part having a constant crystal diameter,
And a step of raising a tail portion in which the crystal diameter is gradually decreased,
Cooling the silicon single crystal pulled up from the silicon melt by using a water-cooling body disposed inside the heat shield above the lower end of the heat shield disposed above the quartz crucible,
Wherein in the step of raising the silicon single crystal, the silicon single crystal is pulled up at a pulling rate equal to the pulling rate at the termination of the body portion growth from the start to the end of the growth of the tail portion. The method according to claim 1,
Wherein the body part of the silicon single crystal is allowed to pass a temperature region of from 1020 to 980 占 폚 in less than 15 minutes in the step of raising the tail part. The method according to claim 1 or 2,
The power of the heater for heating the silicon melt is gradually increased from the start to the end of the cultivation of the tail portion and the power of the heater at the time of termination of the cultivation of the tail portion is increased Wherein the power of the heater is set at 1.1 times or more and 1.5 times or less the power of the heater. 4. The method according to any one of claims 1 to 3,
Wherein the quartz crucible is raised so that a gap between the heat shield and the silicon melt is made constant in the teeming step. 5. The method according to any one of claims 1 to 4,
Wherein the rotating speed of the quartz crucible is kept constant in the step of raising the tessellation. 6. The method according to any one of claims 1 to 5,
Wherein the rotating speed of the silicon single crystal is kept constant in the step of growing the single crystal. 7. The method according to any one of claims 1 to 6,
Wherein the magnetic field is applied to the silicon melt in the step of raising the tessellation.

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