JP2021127278A - Method for producing silicon single crystal - Google Patents

Abstract

To provide a method for producing a silicon single crystal whereby it is possible to keep an oxygen level required for improving the slip resistance by thermal stress in the crystal and to prevent the occurrence of internal rearrangement when pulling up the silicon single crystal.SOLUTION: In a step for growing a straight barrel portion of a silicon single crystal, a correlational formula between the oxygen level A(×1018atoms/cm3) in the single crystal and the single crystal pulling-up speed B (mm/min) is expressed as: B=-1/4A+0.75, and the oxygen level in the single crystal is controlled to A or more and the single crystal-pulling up speed is controlled to B or more.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a silicon single crystal in which a silicon single crystal is pulled up by the Czochralski method (CZ method), and in particular, a method for producing a silicon single crystal capable of suppressing internal dislocations (dislocations) during the pulling up of the silicon single crystal. Regarding the method.

In the growth of a silicon single crystal by the CZ method, the quartz rubo 51 installed in the chamber 50 as shown in FIG. 9 is filled with polysilicon as a raw material, and the polysilicon is provided by a heater 52 provided around the quartz rubo 51. After heating and melting to obtain a silicon melt M, the seed crystal (seed) P attached to the seed chuck is immersed in the silicon melt, and the seed chuck and the quartz rut 51 are rotated in the same direction or in the opposite direction. This is done by pulling up the seed chuck.

Generally, prior to the start of pulling, after the temperature of the silicon melt M stabilizes, the seed crystal P is brought into contact with the silicon melt M to perform necking to dissolve the tip of the seed crystal P. Necking is an indispensable step for removing dislocations generated in a silicon single crystal due to a thermal shock generated by contact between the seed crystal P and the silicon melt M.
The neck portion P1 is formed by this necking. Further, the neck portion P1 is generally required to have a diameter of 3 to 4 mm and a length of 30 to 40 mm or more.

In addition, as the steps after the start of pulling, after the necking is completed, a step of forming a shoulder portion C1 that spreads the crystal to the diameter of the straight body portion, a step of forming a straight body portion C2 that grows a single crystal to be a product, and a process of forming the straight body portion. A step of forming a tail portion (not shown) is performed in which the diameter of the single crystal after the step is gradually reduced.

By the way, if a crystal is dislocated during the step of pulling up a silicon single crystal, the wafer cut out from the dislocated crystal contains many dislocations and cannot be used for manufacturing a device.
In response to such a problem, Patent Document 1 (Japanese Patent Laid-Open No. 2006-347853) describes dislocations caused by thermal stress by including a gas of a hydrogen atom-containing substance in the atmospheric gas for growing a single crystal. A method for growing a silicon single crystal that suppresses the formation of a silicon single crystal is disclosed.

Specifically, the partial pressure of the hydrogen molecule of the gas of the hydrogen atom-containing substance in the atmospheric gas is set to 40 to 400 Pa, and the concentration of the oxygen gas in the atmospheric gas is set to the hydrogen molecule of the gas of the hydrogen atom-containing substance. When the converted concentration is α and the oxygen gas concentration is β, the volume ratio satisfies α-2β ≧ 3%.

According to the method disclosed in Patent Document 1, since the hydrogen element in the gas of the hydrogen atom-containing substance enters between the lattices of the silicon crystal, it is the same as increasing the concentration of the interstitial atoms of the silicon crystal, and silicon. It is possible to reduce the number of interstitial atoms incorporated into the crystal from the silicon melt in the process of solidification.
As a result, slip dislocations originating from dislocation clusters (defects of about 10 μm formed as agglomerates of excess interstitial silicon) generated by thermal stress can be suppressed.

In Patent Document 2 (Japanese Unexamined Patent Publication No. 2002-187996), when a single crystal is pulled up by applying a magnetic field, when the single crystal being grown is dislocated, the conditions for producing the single crystal without applying a magnetic field are described. A method is disclosed in which the output of the heater is increased to dissolve the dislocated single crystal, and then a magnetic field is applied again and the output of the heater is used as the single crystal production condition to raise the single crystal again.

According to this method, when the single crystal is pulled up after meltback (remelting) without applying a magnetic field, foreign matter on the surface of the melt is suppressed from being taken into the single crystal, and in the shoulder forming step. It is possible to suppress dislocations, and a significant improvement in yield is achieved.

Japanese Unexamined Patent Publication No. 2006-347853 JP-A-2002-187996

By the way, in general, as the pulling speed of a single crystal decreases, the amount of interstitial atoms introduced tends to increase, and the amount of strain introduced into the crystal tends to increase. On the other hand, the slip resistance tends to increase as the amount of oxygen introduced into the crystal increases.
Here, when the amount of strain in the crystal increases and the balance between strain and slip resistance is lost, dislocations are introduced from the central portion of the crystal where the stress is large. Since such dislocations occur inside the crystal (called internal dislocations), the crystal habit lines that are indicators of dislocations / no dislocations do not disappear on the crystal surface, and to confirm the dislocations, after slicing into a wafer shape. Needs inspection.
However, in the inventions disclosed in Patent Documents 1 and 2, the dislocations that can be determined based on the presence or absence of the crystal habit line are used as a reference, and the internal dislocations are not considered.

The inventor of the present application focused on the relationship between the crystal pulling speed, which affects the amount of strain, and the crystal oxygen concentration, which affects the slip resistance for maintaining balance with strain. We have found that internal dislocations of crystals can be suppressed by controlling the crystal oxygen concentration and the pulling rate during the growth of the crystals, and have arrived at the present invention.

The present invention has been made under the above-mentioned circumstances, and it is intended to secure an oxygen concentration in the crystal for improving slip resistance and prevent the occurrence of internal dislocations when pulling up a silicon single crystal. It is an object of the present invention to provide a method for producing a silicon single crystal capable of producing a single crystal.

The method for producing a silicon single crystal according to the present invention, which has been made to solve the above problems, is a method for producing a silicon single crystal in which the silicon single crystal is pulled up by the Czochralski method, and is a straight body portion of the silicon single crystal. In the growing step, the correlation equation between the oxygen concentration A (× 10 ¹⁸ atoms / cm ³ ) in the single crystal and the single crystal pulling speed B (mm / min) was set to B = -1 / 4A + 0.75. It is characterized in that the oxygen concentration in the single crystal is controlled to A or higher and the single crystal pulling speed is controlled to B or higher.

As described above, according to the present invention, the oxygen concentration in the crystal and the pulling speed in the growth of the straight body of the crystal are controlled to be equal to or higher than the respective threshold values determined based on their correlation equations, and the silicon single crystal is grown. bottom.
As a result, an oxygen concentration that improves slip resistance can be secured in the crystal, and a pull-up speed that is equal to or higher than the threshold value determined by the correlation equation is secured, so that the amount of interstitial atoms introduced is suppressed and the inside of the crystal is suppressed. It becomes difficult for strain to accumulate in the crystal, and the occurrence of internal dislocations caused by strain in the crystal can be suppressed.

The lower limit of the oxygen concentration in the crystal is preferably 0.4 × 10 ¹⁸ atoms / cm ³ , and the upper limit is preferably ^{1.8 × 10 18} atoms / cm ^3.
Further, it is desirable that the thermal stress at the crystal shaft portion of the straight body portion is 18 MPa or less in terms of Mises stress. When the oxygen concentration and the pulling speed are controlled to be equal to or higher than the respective threshold values determined based on the correlation equation, the thermal stress of the crystal shaft portion can be set to a small thermal stress of 18 MPa or less of the Mises stress.

According to the present invention, a method for producing a silicon single crystal capable of ensuring an oxygen concentration in the crystal for improving slip resistance due to thermal stress and preventing the occurrence of internal dislocations when pulling up the silicon single crystal. Can be provided.

FIG. 1 is a cross-sectional view of a single crystal pulling device in which the method for producing a silicon single crystal according to the present invention is carried out. FIG. 2 is a flow showing a flow of a method for producing a silicon single crystal by the single crystal pulling device of FIG. FIG. 3 is a graph for explaining the method for producing a silicon single crystal of the present invention. FIG. 4 is a graph showing the results of Experiment 1 of the present invention. FIG. 5 is a photograph showing the results of Examples and Comparative Examples of the present invention. FIG. 6 is a graph showing the results of Experiment 2 of the present invention. FIG. 7 is a graph showing the results of Experiment 3 of the present invention. FIG. 8 is a simulation image showing the results of the examples of the present invention. FIG. 9 is a cross-sectional view for explaining a process of pulling up a silicon single crystal by the Czochralski method.

Hereinafter, the method for producing a silicon single crystal according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a single crystal pulling device in which the method for producing a silicon single crystal according to the present invention is carried out. FIG. 2 is a flow showing a flow of a method for producing a silicon single crystal by the single crystal pulling device of FIG.

The single crystal pulling device 1 includes a furnace body 10 formed by superimposing a pull chamber 10b on a cylindrical main chamber 10a, and is provided in the furnace body 10 so as to be rotatable and elevating around a vertical axis. It includes a carbon susceptor (or graphite susceptor) 2 and a quartz glass crucible 3 (hereinafter, simply referred to as a crucible 3) held by the carbon susceptor 2.

The crucible 3 has a straight body portion 3a and a bottom portion 3b formed under the straight body portion 3a, and is capable of rotating around a vertical axis with the rotation of the carbon susceptor 2.
Further, below the carbon susceptor 2, a rotary drive unit 14 such as a rotary motor that rotates the carbon susceptor 2 about a vertical axis, and an elevating drive unit 15 that moves the carbon susceptor 2 up and down are provided.
A rotation drive control unit 14a is connected to the rotation drive unit 14, and an elevating drive control unit 15a is connected to the elevating drive unit 15.

Further, the single crystal pulling device 1 includes a side heater 4 by resistance heating that melts the semiconductor raw material (raw polysilicon) loaded in the crucible 3 into a silicon melt M (hereinafter, simply referred to as melt M). It is provided with a pulling mechanism 9 that winds up the wire 6 and pulls up the single crystal C to be grown. A seed crystal P is attached to the tip of the wire 6 of the pulling mechanism 9.

A heater drive control unit 4a for controlling the amount of power supplied is connected to the side heater 4, and a rotation drive control unit 9a for controlling the rotation drive thereof is connected to the pulling mechanism 9.
Further, in the single crystal pulling device 1, a magnetic field application electromagnetic coil 8 is installed outside the furnace body 2. When a predetermined current is applied to the magnetic field application electromagnetic coil 8, a horizontal magnetic field having a predetermined strength is applied to the silicon melt M in the crucible 3. An electromagnetic coil control unit 8a that controls the operation of the electromagnetic coil 8 for applying a magnetic field is connected to the electromagnetic coil 8.

That is, in the present embodiment, the MCZ method (Magnetic field applied CZ method) in which a magnetic field is applied into the melt M to grow a single crystal is carried out, thereby controlling the convection of the silicon melt M and causing the single crystal. It is designed to stabilize the crystallization.

Further, above the melt M formed in the crucible 3, a radiation shield 7 surrounding the circumference of the single crystal C is arranged. The radiant shield 7 has openings formed at the upper and lower portions, shields excess radiant heat from the side heater 4 and the melt M, etc. with respect to the growing single crystal C, and rectifies the gas flow in the furnace. ..
The gap between the lower end of the radiation shield 7 and the surface of the melt is controlled so as to maintain a predetermined distance according to the desired characteristics of the single crystal to be grown.

Further, a cylindrical water-cooled body 12 is arranged inside the radiation shield 7. Cooling water is supplied to the water-cooled body 12 by the cooling water supply means 12a, and is configured to maintain a predetermined temperature by circulating the water-cooled body 12.

Further, the single crystal pulling device 1 includes a computer 11 having a storage device 11a and an arithmetic control device 11b, and includes a rotation drive control unit 14a, an elevating drive control unit 15a, an electromagnetic coil control unit 8a, and a rotation drive control unit 9a. , The cooling water supply means 12a are connected to the arithmetic control device 11b, respectively.

In the single crystal pulling device 1 configured as described above, for example, when growing a single crystal C having a diameter of 300 mm, the single crystal pulling device 1 is pulled as follows. That is, the raw material polysilicon (for example, 350 kg) is first loaded in the crucible 3, and the crystal growth step is started based on the program stored in the storage device 11a of the computer 11.

First, the inside of the furnace body 10 is made into a predetermined atmosphere (mainly an inert gas such as argon gas), and the raw material polysilicon loaded in the crucible 3 is melted by heating by the side heater 4 to be a molten liquid M. (Step S1 in FIG. 2). Further, the crucible 3 is rotated at a predetermined rotation speed (rpm) at a predetermined height position (step S2 in FIG. 2).

Next, a predetermined current is passed through the magnetic field application electromagnetic coil 8, and a horizontal magnetic field is started to be applied into the melt M at a magnetic flux density (for example, 2500 Gauss) set in the range of 1000 to 4000 Gauss (step of FIG. 2). S3).
Further, the wire 6 is lowered, the seed crystal P is brought into contact with the melt M, necking is performed to dissolve the tip portion of the seed crystal P, and the neck portion P1 is started to be formed (step S4 in FIG. 2).
When the neck portion P1 is formed, the pulling conditions are adjusted with the power supplied to the side heater 4, the pulling speed, the magnetic field application strength, and the like as parameters, and the seeds are seeded at a predetermined rotation speed in the direction opposite to the rotation direction of the rutsubo 3. The crystal P starts rotating.

Then, the crystal diameter is gradually increased to form the shoulder portion C1 (step S5 in FIG. 2), and the process proceeds to the step of forming the straight body portion C2 to be the product portion (step S6 in FIG. 2).
Here, in the growth of the straight body portion C2, the computer 11 sets the horizontal axis x as the crystalline oxygen concentration A (× 10 ¹⁸ atoms / cm ³ ) and the vertical axis y as the pulling speed B (mm) as shown in FIG. When / min) is set, the values of A and B determined by the correlation equation B = -1 / 4A + 0.75 of the linear function are used as the threshold value, and the pulling speed and the crystalline oxygen concentration are set so that each value is higher than that. To control.

Specifically, the crystal oxygen concentration value is set to be, for example, the target oxygen concentration value of the wafer to be a product, and when A is set as the oxygen concentration target value, the oxygen concentration value A (× 10) is expressed in the correlation equation. ^The pull-up speed value B = -1 / 4A + 0.75 (mm / min) in which 18 atoms / cm ^{3) is substituted is set as the pull-up speed threshold.} That is, the computer 11 performs the pull-up control so that the oxygen concentration becomes the target value A or more, and also performs the pull-up control at the pull-up speed B or more.

When the single crystal C having the crystal oxygen concentration A is grown in this way, by controlling the pulling speed to B or higher, the amount of interstitial atoms introduced is suppressed and strain is less likely to be accumulated inside the crystal, and the crystal is in the crystal. The occurrence of internal dislocations caused by the distortion of is suppressed.
The range of the crystalline oxygen concentration A is preferably 0.4 (× 10 ¹⁸ atoms / cm ³ ) or more and less than 1.8 (× 10 ¹⁸ atoms / cm ³ ). This is because, for the crystal oxygen concentration A, if the limit of the low oxygen concentration is 0.4 (× 10 ¹⁸ atoms / cm ³ ) and 1.8 (× 10 ¹⁸ atoms / cm ³ ) or more, the crystal is being pulled up. This is because there is a risk of dislocation.
Further, it is desirable that the range of the pulling speed B is 0.3 (mm / min) or more and less than 1.1 (mm / min). This is because if the pulling speed B is less than 0.3 (mm / min), the rate of dislocations during crystal pulling increases, and if it is 1.1 (mm / min) or more, the crystal may be deformed. Because there is.

Oxygen in the single crystal is introduced as follows. When the silicon melt M flows in contact with (along) the side wall of the crucible 3, the silicon at the melting point is chemically active, so that the silicon melt M reacts with the quartz component of the crucible 3 and forms the side wall of the crucible 3. It dissolves and O (oxygen) is incorporated into the silicon melt M.

In order to control the oxygen concentration in the single crystal grown from the silicon melt M into which O (oxygen) has been introduced, the internal pressure of the furnace is preferably adjusted (increasing the internal pressure decreases the crystalline oxygen concentration). This makes it possible to control the flow (convection) of the silicon melt M.

Further, by adjusting the temperature of the water-cooled body 12, the temperature of the straight body portion C2 to be grown is cooled from, for example, 1412 ° C. to 800 ° C., and the thermal stress of the crystal shaft portion is suppressed to, for example, 18 MPa or less by the Mises stress. NS.
In this way, the thermal stress inside the crystal is suppressed to a low level, and the crystal oxygen concentration is controlled to be equal to or higher than the target value A in the growth of the straight body portion C2, so that the amount of crystal oxygen introduced is secured and the slip resistance is improved.

As the formation of the straight body portion C2 of the silicon single crystal C progresses, the carbon susceptor 2 accommodating the crucible 3 is moved upward, and the position of the molten liquid surface M1 with respect to the fixed position radiation shield 7 and the side heater 4 is maintained. ..
Further, for example, the natural convection of the melt M is suppressed by applying a magnetic field having a magnetic flux density set in the range of 1000 to 4000 Gauss, more preferably 2000 to 3000 Gauss). If the magnetic flux density of the horizontal magnetic field is set low in the range of 800 to 1000 Gauss, the melt M becomes unstable and crystal deformation is likely to occur.

Then, when the straight body portion C2 is formed to a predetermined length, the process proceeds to the final tail portion step (step S7 in FIG. 2). In this tail portion step, the contact area between the lower end of the crystal and the melt M is gradually reduced, the single crystal C and the melt M are separated, and a silicon single crystal is produced.

As described above, according to the present embodiment, the oxygen concentration in the crystal and the pulling speed in the growth of the crystal straight body portion are controlled to be equal to or higher than the respective threshold values determined based on their correlation equations, and silicon. A single crystal was grown. Further, in growing the straight body portion, the thermal stress of the crystal shaft portion is suppressed to a Mises stress of 18 MPa or less.
As a result, the oxygen concentration for improving the slip resistance can be secured in the crystal, and the pulling speed equal to or higher than the threshold value determined by the correlation formula is secured, so that the amount of interstitial atoms introduced is suppressed. Therefore, strain is less likely to be accumulated inside the crystal, and the occurrence of internal dislocations caused by strain in the crystal can be suppressed.

The method for producing a silicon single crystal according to the present invention will be further described based on Examples.
(Experiment 1)
In Experiment 1, in the single crystal pulling device having the configuration shown in the above embodiment, 360 kg of raw material polysilicon was put into the crucible and the silicon single crystal having a diameter of 307 mm was pulled. In order to suppress the natural convection of the silicon melt, the magnetic flux density of the horizontal magnetic field applied during pulling was set to 2500 Gauss.

Further, the temperature of the water-cooled body surrounding the single crystal was adjusted so that the distance from the surface of the single crystal to the surface of the water-cooled body was 55 mm, and the Mises stress was adjusted to 18 MPa or less. The magnetic field strength was 3000 Gauss.
Ar gas was used as the inert gas, and the flow rate of the inert gas was set to 130 l / min. The pressure inside the furnace was set to 15 to 80 Torr. Further, the rotation speed of the crucible was set to 0.5 rpm, and the rotation speed of the single crystal was set to 9.5 rpm (the rotation directions were opposite to each other).

Moreover, in Experiment 1, 110 pulling trials were carried out.
Then, the target crystalline oxygen concentration was set for each trial, and the pulling speed was changed in various ways to pull the crystal oxygen. The results of each trial in Experiment 1 are shown in the graph of FIG.
In the graph of FIG. 4, the vertical axis y is the average pulling speed (mm / min), the horizontal axis x is the oxygen concentration in the center of the crystal (10 ¹⁸ atoms / cm ³ ), and the average pulling speed and the center of the crystal in each trial. It is a plot of the oxygen concentration of.
In each trial, the obtained single crystal was processed into an etched wafer and exposed to oblique light to confirm the presence or absence of internal dislocations due to surface transmission. Then, in each trial, as shown in FIG. 4, those without internal dislocations are indicated by ◇, and those with internal dislocations are indicated by ×.

From the graph of FIG. 4, in the correlation equation y = -1 / 4x + 0.75 (y is the average pulling speed (mm / min), x is the oxygen concentration in the center of the crystal (10 ¹⁸ atoms / cm ³ )). When the value A of y when x = B was set as the threshold value of the average pulling speed and the crystal oxygen concentration was B or higher and the pulling speed A or higher, it was found that there was no internal dislocation.

Note that FIG. 5A shows a photograph when there is no internal dislocation when the presence or absence of internal dislocation is inspected, and FIG. 5B shows a photograph when there is internal dislocation. In the example of the result shown in FIG. 5B, several cross-shaped reflections having a size of about 5 to 20 mm are observed, but since the crystal habit lines have not disappeared, they can be confirmed as internal dislocations.

As a result of this experiment 1, as shown in the graph of FIG. 4, when the single crystal is pulled up above the value of y when the target oxygen concentration is substituted into x of the correlation equation y = -1 / 4x + 0.75, the inside is inside. It was confirmed that no dislocation occurred.

(Experiment 2)
In Experiment 2, among the conditions of Experiment 1, the conditions of the magnetic flux density affecting the flow (convection) of the silicon melt, the flow rate of the inert gas, the pressure in the furnace, the rutsubo, and the rotation speed of the single crystal were changed. Other conditions are the same as the conditions of Experiment 1.
Specifically, the magnetic flux density was 2000 Gauss, and the flow rate of the inert gas was 130 l / min. The pressure inside the furnace was set to 15 to 80 Torr. Further, the rotation speed of the crucible was set to 0.5 rpm, and the rotation speed of the single crystal was set to 9.5 rpm (the rotation directions were opposite to each other).

The results of each trial in Experiment 2 are shown in the graph of FIG. In the graph of FIG. 6, the vertical axis y is the average pulling speed (mm / min), the horizontal axis x is the oxygen concentration in the center of the crystal (10 ¹⁸ atoms / cm ³ ), and the average pulling speed and the center of the crystal in each trial. It is a plot of the oxygen concentration of. In each trial, those without internal dislocations are indicated by ◇, and those with internal dislocations are indicated by ×.
As a result of Experiment 2, as shown in the graph of FIG. 6, when the single crystal is pulled up above the value of y when the target oxygen concentration is substituted for x in the correlation equation y = -1 / 4x + 0.75, internal dislocations occur. Did not occur.

(Experiment 3)
In Experiment 3, among the conditions of Experiments 1 and 2, the conditions of the magnetic flux density affecting the flow (convection) of the silicon melt, the flow rate of the inert gas, the pressure in the furnace, the rutsubo, and the rotation speed of the single crystal were changed. .. Other conditions are the same as those of Experiments 1 and 2.
Specifically, the magnetic flux density was 3000 Gass, and the flow rate of the inert gas was 130 l / min. The pressure inside the furnace was set to 15 to 80 Torr. Further, the rotation speed of the crucible was set to 2.0 rpm, and the rotation speed of the single crystal was set to 9.5 rpm (the rotation directions were opposite to each other).

The results of each trial in Experiment 3 are shown in the graph of FIG. In the graph of FIG. 7, the vertical axis y is the average pulling speed (mm / min), the horizontal axis x is the oxygen concentration in the center of the crystal (10 ¹⁸ atoms / cm ³ ), and the average pulling speed and the center of the crystal in each trial. It is a plot of the oxygen concentration of. In each trial, those without internal dislocations are indicated by ◇, and those with internal dislocations are indicated by ×.
As a result of Experiment 3, as shown in the graph of FIG. 7, when the single crystal is pulled up above the value of y when the target oxygen concentration is substituted for x in the correlation equation y = -1 / 4x + 0.75, internal dislocations occur. Did not occur.

From the results of Experiments 1 to 3 above, in order to suppress the occurrence of internal dislocations, the correlation equation between the ^{average pulling rate (mm / min) and the oxygen concentration in the center of the crystal (10 18} atoms / cm ^{3) y = -1.} / 4x + 0.75 can be defined, and internal dislocations do not occur when the target oxygen concentration is substituted for x in the correlation equation y = -1 / 4x + 0.75 and the single crystal is pulled up above the value of y. Was confirmed.

(Experiment 4)
In Experiment 4, among the trials of Experiment 1, the thermal stress generated inside the crystal was confirmed by simulation under the conditions that the pulling speed was 0.55 mm / min and the crystal oxygen concentration was 1.1E18 atoms / cm ^3.
In this simulation, the comprehensive heat transfer analysis software CGSim_Basic manufactured by STR was used, and the parameters were a coefficient of thermal expansion of 2.6 × 10 ^-6 K- ¹ , Young's modulus of 185 GPa, Poisson ratio of 0.28, and density of 2330 kg / m ³ . I set it.
FIG. 8 shows the simulation result. In FIG. 8, it was confirmed that the thermal stress was as small as 18 MPa at the crystal shaft portion near 150 mm above the solid-liquid interface, and the slip resistance could be improved.

From the results of the above experiments 1 to 4, it was confirmed that according to the present invention, it is possible to prevent the occurrence of internal dislocations caused by strain during the growth of the straight body portion of the single crystal.

1 Single crystal pulling device 2 Carbon susceptor 3 Quartz glass crucible (crucible)
4 Side heater 6 Wire 7 Radiation shield 8 Electromagnetic coil for applying magnetic field 9 Pulling mechanism 10 Furnace 11 Computer 11a Storage device 11b Arithmetic control device 12 Water cooler 14 Rotating drive unit 15 Lifting drive unit C Silicon single crystal M Silicon melt C1 Shoulder Part C2 Straight body part

Claims (3)

It is a method of manufacturing a silicon single crystal that pulls up a silicon single crystal by the Czochralski method.
In the straight body growing step of the silicon single crystal,
The correlation equation between the oxygen concentration A (× 10 ¹⁸ atoms / cm ³ ) in the single crystal and the single crystal pulling speed B (mm / min) was set to B = -1 / 4A + 0.75.
A method for producing a silicon single crystal, which comprises controlling the oxygen concentration in the single crystal to be A or higher and the single crystal pulling speed to be B or higher. The first aspect of claim 1, wherein the lower limit of the oxygen concentration in the crystal is 0.4 × 10 ¹⁸ atoms / cm ³ , and the upper limit is 1.8 × 10 ¹⁸ atoms / cm ^3. A method for producing a silicon single crystal. The method for producing a silicon single crystal according to claim 1 or 2, wherein the thermal stress at the crystal shaft portion of the straight body portion is 18 MPa or less in terms of Mises stress.

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