JP2008019128A - Apparatus for producing single crystal, method for producing single crystal, and single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing a single crystal by which the convection of a silicon melt can be controlled during pulling and the quality difference of the single crystal depending on the residual amount of the silicon melt can be reduced. <P>SOLUTION: In the apparatus 30 for producing the single crystal, a convection control member 35 being a plate-like body nearly parallel to the bottom surface of a crucible is provided so as to be positioned between the bottom surface of the crucible and the solid-liquid interface so that the convection range just below the solid-liquid interface having an effect on the quality of a single crystal 3 being grown becomes within a distance Lb in the vertical direction in the silicon melt 4 when the depth La, defined as the distance between the surface 4a of the silicon melt 4 and the bottom surface of the crucible, exceeds the distance Lb. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is capable of controlling the convection of the silicon melt at the time of pulling, and can reduce the quality difference of the single crystal depending on the amount of the remaining silicon melt, and the single crystal production thereof The present invention relates to a method for producing a single crystal using an apparatus and a single crystal.

  A silicon single crystal is grown by heating a polycrystalline silicon raw material contained in a crucible with a heater to form a silicon melt, and pulling it up from the silicon melt by the Czochralski method (hereinafter abbreviated as “CZ method”). It is manufactured by. In a silicon single crystal grown by the CZ method, a defect called a Grown-in defect is formed during crystal growth, and is detected when a silicon single crystal obtained after crystal growth is evaluated.

It is known that R-OSF (Ring-Oxidation induced Stacking Fault) may appear in the longitudinal section of a silicon single crystal grown while gradually reducing the pulling rate. The region where R-OSF appears shrinks from the outer peripheral side of the crystal to the inside as the pulling rate is reduced. The grown-in defects observed after crystal growth are different between the inside (crystal region pulled at a high speed) and the outside (crystal region pulled at a low speed) from the R-OSF. In the crystal region pulled at a high speed, a void defect (a void type defect) called COP (crystal originated particle) or FPD (flow pattern defect) is detected. In addition, in the crystal region pulled at a low speed, interstitial Si aggregates accompanied by dislocations are generated, and interstitial Si defects (dislocation cluster defects) are detected.
In addition, there is a defect-free region in which no Grown-in defect is detected between the R-OSF and the interstitial Si defect region. The void defect in the silicon single crystal is a deterioration factor of the initial oxide film breakdown voltage characteristic of the wafer. In addition, interstitial Si defects in the silicon single crystal also degrade device characteristics. Therefore, crystal growth in a defect-free region is desired because of the quality characteristics of the silicon single crystal.

Conventionally, a method of pulling up in a magnetic field (MCZ method) is known as a method for obtaining a uniform silicon single crystal that can suppress convection of a silicon melt (see, for example, Patent Document 1).
JP-A 64-24090

  However, the conventional technique cannot sufficiently suppress the convection of the silicon melt that changes according to the amount of the remaining silicon melt. In particular, when producing a silicon single crystal using the pulling method in a magnetic field, the amount of silicon melt in the crucible gradually changes (decreases), so the difference in strength of the magnetic field depending on the position in the silicon melt (solid-liquid interface) The difference in magnetic field strength between the position and the bottom of the crucible is large when the amount of residual silicon melt is large, and is small when the amount of residual liquid is small, and the amount of change in convection of the silicon melt due to the amount of residual silicon melt. Becomes larger. This convection in the silicon melt affects the temperature distribution near the solid-liquid interface, the shape of the solid-liquid interface (convex upward, etc.) due to this temperature distribution, or the surface of the crucible wall. It has been found that the oxygen concentration in the silicon melt, dopants, how impurities such as bubbles are incorporated into the single crystal, and as a result, the crystal quality in the single crystal are affected. For this reason, in the conventional technique, even if the pulling is performed under the same pulling conditions from the start to the end of pulling, the single crystal grown in the first half of the pulling and the single crystal grown in the second half of the pulling have a single crystal defect state, The quality of single crystals such as the oxygen concentration and dopant concentration of these materials greatly differed, and a single crystal having a desired quality could not be obtained, resulting in a significant decrease in yield.

  Specifically, for example, when a crystal of a defect-free region is manufactured while applying a cusp magnetic field, if the amount of silicon melt accommodated in the crucible is increased, the defect-free region is not formed immediately after the start of pulling. . In addition, when a crystal having a predetermined oxygen concentration or dopant concentration is produced while applying a cusp magnetic field, the in-plane distribution (Radial gradient of oxygen, ORG; Radial gradient of resistance, ; RRG) and the like change.

  The present invention has been made in view of the above circumstances, can control the convection of the silicon melt at the time of pulling, and reduce the quality difference of the single crystal depending on the residual amount of the silicon melt. It is an object of the present invention to realize a single crystal manufacturing apparatus, a single crystal manufacturing method using the single crystal manufacturing apparatus, and a single crystal.

The single crystal production apparatus of the present invention is a single crystal production apparatus for growing while pulling up a silicon single crystal from a silicon melt contained in a crucible,
When the depth La, which is the distance between the surface of the silicon melt and the bottom surface of the crucible, exceeds the vertical distance Lb, the solid that affects the quality of the single crystal grown in the silicon melt. A convection control member, which is a plate-like body substantially parallel to the bottom surface of the crucible, is provided between the bottom surface of the crucible and the solid-liquid interface so that the convection range immediately below the liquid interface is within the distance Lb. It is characterized by being able to.
Moreover, it is preferable that the said convection control member of this invention is a planar view circular shape centering on the central axis of the said silicon single crystal pulled up.
Further, the convection control member of the present invention may be at a position including at least the range where the silicon single crystal exists in plan view.
Further, the present invention may comprise magnetic field applying means for controlling the convection of the silicon melt.
In the present invention, the distance Lb may be set as a range in which a rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying unit is 40% or less.

The method for producing a single crystal according to the present invention is a method for producing a silicon single crystal using any of the single crystal production apparatuses described above,
Installing the convection control member, which is a plate-like body substantially parallel to the bottom surface of the crucible, at a position of the distance Lb from the solid-liquid interface;
When the depth La, which is the distance between the surface of the silicon melt and the bottom surface of the crucible, exceeds the distance Lb, immediately below the solid-liquid interface that affects the quality of the single crystal grown in the silicon melt. The convection range is controlled so as to be within the distance Lb.
The method for producing a single crystal of the present invention includes a step of producing a silicon melt by melting a silicon raw material in the crucible, a step of disposing the convection control member at a predetermined position in the silicon melt, and the silicon It is preferable to start the single crystal pulling step after sequentially performing the step of adjusting the temperature of the melt to the pulling start temperature.
Further, according to the present invention, in the single crystal pulling step, the silicon single crystal can be pulled while applying a magnetic field to the silicon melt by the magnetic field applying means.
In addition, the present invention may be a method in which the distance Lb is set as a range in which the rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying unit is 40% or less.
The single crystal manufacturing method described above can be a method of pulling up a single crystal having a defect-free region.

  In order to solve the above problems, the single crystal of the present invention is manufactured by any one of the above-described single crystal manufacturing apparatuses or any of the above-described single crystal manufacturing methods.

  According to the single crystal manufacturing apparatus of the present invention, the single crystal manufacturing apparatus grows the silicon single crystal while pulling it up from the silicon melt accommodated in the crucible, and the quality of the single crystal grown in the silicon melt is improved. The convection control member, which is a plate-like body substantially parallel to the bottom surface of the crucible, has a distance between the silicon melt surface and the bottom surface of the crucible so that the convection range immediately below the influential solid-liquid interface is within the vertical distance Lb. Convection region in the vicinity of the solid-liquid interface that has a direct influence on crystal growth by being provided so as to be positioned between the bottom surface of the crucible and the solid-liquid interface when the depth La taken is greater than the distance Lb. It is possible to control the oxygen concentration, dopant concentration, temperature state, etc. that have a direct influence on the solid-liquid interface within a predetermined range by regulating the convection of the liquid within the depth direction distance Lb It becomes, as a result, it is possible to reduce adverse effects on the single crystal pulling due to the silicon melt depth changes.

In the silicon melt, a main convection that rises along the quartz crucible body and falls near the center of the quartz crucible due to a temperature difference in the melt. In the conventional pulling apparatus in which no convection control device exists, the main convection is almost the only large convection generated in the silicon melt. On the other hand, in the silicon single crystal pulling apparatus according to the present invention, by providing a convection control member, for example, as shown in FIGS. 1 and 3, near the solid-liquid interface in the silicon melt, the direction opposite to the main convection is provided. It is possible to generate secondary convection flowing through
By this secondary convection, the atoms in the melt are well convectively mixed and diffused, and the effective diffusion coefficient D is greatly increased. Moreover, the temperature gradient Gm of the melt also increases. Therefore, systematic supercooling can be easily suppressed.

The plan view shape of the convection control member and the surface irregularity shape thereof are determined by setting the diameter dimension and the height of the convex portion according to the diameter of the silicon single crystal and the maximum depth La of the silicon melt. Secondary convection can be reliably generated in the vicinity of the solid-liquid interface. Further, at least the impurity concentration (dopant) concentration of the silicon melt near the solid-liquid interface is prevented from becoming higher than that of other portions of the silicon melt, and the silicon single crystal ingot is dislocated. Even if it is not, the uniformity of impurities (dopant) in the silicon single crystal ingot is desired, and the wafer surface resistivity distribution (RRG) and wafer surface oxygen distribution (ORG) when processing into a silicon wafer are desired. The shape is set to fall within the range.
RRG is defined as follows.
RRG = (wafer center resistivity ρ0−wafer side resistivity ρS) / wafer center resistivity ρ0
In general,
RRG (IN10) = (wafer center resistivity ρ0−wafer inside 10 mm resistivity ρS) / wafer center resistivity ρ0
RRG (IN5) = (wafer center resistivity ρ0−wafer inside 5 mm resistivity ρS) / wafer center resistivity ρ0
Etc. are used.
In the present invention, RRG (IN5) is used as RRG.

  In the single crystal manufacturing apparatus of the present invention, the depth La of the silicon melt is the vertical distance between the lowermost part of the convection control member and the melt surface from the start of the pulling to the start of the pulling. By controlling so that the position of the convection control member with respect to the melt surface does not change when it is at least within a predetermined range up to less than Lb, the depth La of the silicon melt is the distance Lb. Since the convection of the silicon melt is controlled so as to be in a certain state, the convection of the silicon melt at the time of pulling up can be controlled as shown below.

That is, when a single crystal is manufactured using the single crystal manufacturing apparatus of the present invention, the amount of silicon melt remaining is large, and the depth of the silicon melt, which is the distance between the bottom of the crucible and the surface of the melt. The position of the convection control member relative to the melt surface when the thickness La is deeper than the vertical distance Lb between the lowermost portion of the convection control member and the melt surface at the start of pulling By controlling so as not to change, it is possible to control so that the silicon melt depth La is the distance Lb.
Therefore, when a single crystal is manufactured using the single crystal manufacturing apparatus of the present invention, fluctuations in the convection of the silicon melt from the start of the pulling up to the point where the distance is less than the distance Lb due to the decrease in the silicon melt accompanying the pulling. Very little. As a result, it is possible to reduce the quality difference and the solid-liquid interface shape of the single crystal depending on the amount of the remaining silicon melt, and it is possible to manufacture a single crystal having a desired quality with a high yield.

  Moreover, in the single crystal manufacturing apparatus of the present invention, the predetermined range is the entire range in which the depth La of the silicon melt is less than the distance Lb from the start of the pulling, so that the silicon melt In all ranges when the depth La of the silicon melt is deeper than the distance Lb, the convection of the silicon melt can be controlled to be in the state when the depth La of the silicon melt is the distance Lb. In this case, most of the pulled single crystal is preferable because the quality difference of the single crystal depending on the remaining amount of the silicon melt is small.

In the present invention, the convection control member is circular in plan view with the central axis of the silicon single crystal to be pulled up as a center, so that when the convection control member contacts the crucible bottom, the entire circumference of the convection control member is By contacting the crucible almost simultaneously, the impact can be reduced, and the convection of the silicon melt can be well controlled so as to be in the state when the depth La of the silicon melt is the distance Lb. Here, in this invention, when the said convection control member does not rotate synchronizing with a crucible, it is preferable that the crucible rotation at the time of raising made into object is set to about 0.1-10 rpm. Further, when the convection control member rotates in synchronization with the crucible, an arbitrary crucible rotation number can be selected.
Moreover, in the single crystal pulling apparatus of the present invention, a convection control member rotating means that enables the convection control member to rotate in synchronization with the crucible can be provided.

Further, the convection control member of the present invention has a shape including at least a certain range of silicon single crystal (range of solid-liquid interface) in a plan view, and more specifically, the convection control member has a substantially circular shape in a plan view. When the diameter of the silicon single crystal is Dd, the minimum diameter of the convection control member is at least in the range of Dd to 1.8 Dd. Further, the maximum diameter of the convection control member can be a dimension that is substantially the same as the inner diameter of the crucible, that is, a shape that is located almost entirely inside the crucible in plan view so as not to contact the crucible wall. As a result, at least the convection in the convection region in the vicinity of the solid-liquid interface that directly affects crystal growth can be regulated to be within the depth direction distance Lb, thereby reducing the adverse effect on the single crystal to be pulled up. It becomes.
Furthermore, the convection control member has a shape that is located almost entirely inside the crucible, thereby maximizing the free surface of the melt when the convection control member comes into contact with the quartz crucible (the melt surface between the outside of the crystal and the inside of the quartz crucible). , Rapid increase in oxygen concentration is prevented. Usually, oxygen dissolved from quartz is evaporated from the melt free surface by 90% or more. Therefore, if the melt free surface decreases rapidly, the oxygen concentration in the melt rapidly increases and the oxygen concentration in the crystal to be pulled up also increases rapidly. It is expected to be.

Further, in the present invention, when the magnetic field applying means for controlling the convection of the silicon melt is provided, the convection of the silicon melt can be effectively suppressed by applying the magnetic field, and the residual liquid of the silicon melt Since the amount of change in convection of the silicon melt due to the amount can be reduced, a single crystal having a desired quality such as a defect state of the single crystal and a dopant concentration in the single crystal can be manufactured with a high yield.
In the present invention, the distance Lb can be set as a range in which the rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying means is 40% or less. The convection that directly affects the crystal quality can be controlled by applying a magnetic field, and the difference in magnetic field strength due to the difference in depth from the silicon melt surface can be reduced. It becomes possible to prevent variations in single crystal quality.
The rate of change during the pulling of the magnetic field distribution is preferably set to 40% or less, more preferably 30% or less, or 20% or less.

The method for producing a single crystal according to the present invention is a method for producing a silicon single crystal using any of the above-described single crystal production apparatuses, wherein the convection control is a plate-like body substantially parallel to the bottom surface of the crucible. When the depth La, which is the distance between the surface of the silicon melt and the bottom surface of the crucible, is positioned below the distance Lb in the vertical direction from the solid-liquid interface, In the liquid, the convection region in the vicinity of the solid-liquid interface that directly affects the crystal growth is controlled by controlling the convection range immediately below the solid-liquid interface that affects the quality of the grown single crystal within the vertical distance Lb. The convection is controlled within a range within the depth direction distance Lb to prevent the oxygen concentration, the dopant concentration, the temperature state, etc. directly affecting the solid-liquid interface from changing from the predetermined ranges. Control It becomes possible to, as a result, it is possible to reduce adverse effects on the single crystal pulling due to the silicon melt depth changes that occur with the single crystal pulling.
In the method for producing a single crystal according to the present invention, the position of the convection control member relative to the melt surface is less than the distance Lb due to the decrease in the silicon melt accompanying the pulling of the silicon melt depth La from the start of the pulling. Since the silicon single crystal is pulled up while being controlled so as not to change until the time becomes, a single crystal having a small quality difference depending on the remaining amount of the silicon melt can be manufactured.

In the method for producing a single crystal, a step of melting a silicon raw material in a crucible to produce a silicon melt, a step of disposing a convection control member at a predetermined position in the silicon melt, a silicon melt And the step of adjusting the temperature so as to become the pulling start temperature, and then starting the single crystal pulling step, so that the convection control member can melt the silicon raw material or the silicon melt as shown below. Therefore, it is possible to prevent the temperature adjustment of the pulling start temperature from being hindered, and it is possible to efficiently produce a single crystal.
For example, it is not preferable to melt the silicon raw material after disposing the convection control member in the crucible because the convection control member may be softened because the melting temperature is higher than the pulling temperature. In fact, the quartz crucible may be softened when the silicon raw material is melted, which is not preferable when the convection control member is made of quartz. Therefore, at least after the melting of the silicon raw material, the convection control member should be immersed in the silicon melt. In addition, when the convection control member is disposed in the silicon melt after the step of adjusting the temperature by lowering the temperature from the melting temperature so that the temperature of the silicon melt becomes the pulling start temperature, the temperature is increased by disposing the convection control member. The starting temperature may fluctuate. Therefore, it is preferable to set the temperature at which the convection control member is pulled up after being immersed in the silicon melt.
On the other hand, after the silicon raw material is melted in the crucible, the convection control member is disposed at a predetermined position in the silicon melt, and then the temperature of the silicon melt is adjusted so as to be the starting temperature. The temperature of the silicon raw material (melt), which is high immediately after melting, and then drops to the starting temperature of pulling up, is naturally lowered by placing a convection control member in the silicon melt, and when the silicon raw material is melted Since it will naturally approach the pulling start temperature lower than the temperature, the pulling start temperature can be reached in a short time compared to the case where no convection control member is arranged in the silicon melt, and the total amount of single crystal pulling Thus, the production time of the single crystal can be efficiently performed.
Note that the convection control member can be disposed at a position in the crucible before the melting step, for example, by lowering the silicon raw material melting temperature.
Further, in the pulling process, a convection control member suspension process in which the convection control member is not in contact with the crucible bottom, and a convection control member placement process in which the convection control member is placed on the crucible bottom and rotates together with the crucible. Can have.

  In addition, since the height position of the convection control member can be finely controlled by providing the position adjusting means, the formation state of the secondary convection is set more precisely and affected by the vortex flow in the melt. The dopant concentration / distribution and temperature gradient / state can be controlled more precisely. As a result, the crystal state of the single crystal to be pulled can be controlled more precisely.

Further, in the method for producing a single crystal, when the silicon single crystal is pulled up while applying a magnetic field to the silicon melt by magnetic field applying means, the convection of the silicon melt is effectively prevented. In addition, the amount of change in the convection of the silicon melt due to the amount of residual silicon melt can be reduced.
In the present invention, the distance Lb can be set as a range in which the rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying means is 40% or less. It is possible to control the convection of the portion that directly affects the crystal quality by applying a magnetic field, and to reduce the difference in magnetic field strength due to the difference in depth from the silicon melt surface.
For this reason, the convection in the convection region in the vicinity of the solid-liquid interface that directly affects the crystal growth is almost uniformly controlled in the magnetic field in the range within the distance Lb in the depth direction, and the oxygen concentration and dopant in the single crystal are controlled. Concentration, affected solid-liquid interface shape, oxygen concentration in nearby silicon melt, dopant concentration, temperature state, etc. are determined as the silicon melt depth (solid-liquid interface) changes depending on the pulling length. It is possible to prevent the defect distribution range from disappearing and to control each parameter. As a result, it is possible to reduce the adverse effect on the single crystal to be pulled due to the change in the depth of the silicon melt caused by the single crystal pulling.
The rate of change during the pulling of the magnetic field distribution is preferably set to 40% or less, more preferably 30% or less, or 20% or less.

In the present invention, it is also possible to set the above parameters in the single crystal to be pulled so as to change depending on the pulling length. In this case, the distance Lb from the solid-liquid interface to the convection control member is pulled up. By changing the length Lb and controlling the setting of the distance Lb over time, the shape of the solid-liquid interface can be set, the gradient of oxygen concentration, COP concentration, resistivity, etc. in the axial direction or non-uniform distribution It is also possible to pull up a single crystal having
At this time, for example, when applying a cusp magnetic field, if Lb is reduced,
Solid-liquid interface (lower convex → upper convex)
Oxygen concentration (decrease)
COP concentration (decrease)
Dopant concentration (increase)
Resistivity (decrease)
There is a change trend,
For example, when applying a cusp magnetic field, when Lb is increased,
Solid-liquid interface (upward → downward)
Oxygen concentration (increase / decrease)
COP concentration (increase)
Dopant concentration (decrease)
Resistivity (increase)
There is a tendency to change. Therefore, in consideration of these, the value of Lb can be set sequentially as the pulling length increases. Of course, the control of these parameters includes the temperature conditions, the structure of the insulation material in the furnace, the rotation of the crucible and the single crystal, the pulling speed, the furnace pressure, the gas flow rate in the furnace, the gas composition, the magnetic field type and the application conditions, etc. It is preferable to carry out in conjunction with other parameters.

  In addition, when pulling up a single crystal having a defect-free region using the above-described method for producing a single crystal, a single crystal having a small quality difference depending on the amount of silicon melt remaining can be obtained. Even a single crystal having a defect-free region in which it was difficult to obtain can be manufactured with high yield. Or it becomes possible to obtain the above single crystals by controlling Lb.

  According to the single crystal production apparatus and the single crystal production method of the present invention, it becomes possible to produce a single crystal having desired characteristics by preventing the occurrence of a quality difference depending on the residual amount of silicon melt, A single crystal having a desired quality can be manufactured with a short working time and high yield.

Hereinafter, the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic cross-sectional view of a single crystal manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram for explaining the convection control member provided in the single crystal manufacturing apparatus shown in FIG. 1, and FIG. 2 (a) is a diagram in which the convection control member is cut in a diametrical direction at a portion where a support piece is provided. It is sectional drawing, (b) is a top view of a convection control member.

  In FIG. 1, the code | symbol 30 has shown the single crystal manufacturing apparatus. In the main chamber 1 of the single crystal manufacturing apparatus 30, a quartz crucible 5 that stores the silicon melt 4 and a graphite crucible 6 that protects the quartz crucible 5 are supported by a holding shaft 13 so as to be rotatable and movable up and down by a crucible drive mechanism 21. Has been. The heater 7 and the heat insulating material 8 are arranged so as to surround the quartz crucible 5 and the graphite crucible 6. A pulling chamber 2 for accommodating and taking out the grown silicon single crystal 3 is connected to the upper portion of the main chamber 1, and the silicon single crystal 3 is rotated by a wire 14 at the upper portion of the pulling chamber 2. A pulling mechanism (not shown in FIG. 1) is provided.

  In addition, a gas rectifying cylinder 11 is provided inside the main chamber 1 to block radiation from the silicon melt 4 to the silicon single crystal 3 and rectify the gas in the main chamber 1. A heat shield member 12 is installed at the lower part of the cylinder 11 so as to face the entire surface of the silicon melt 4 so as to cut off radiation from the surface of the silicon melt 4 and to keep the surface of the silicon melt 4 warm. Yes.

  A magnetic field generator (magnetic field applying means) 17 that applies a magnetic field to the quartz crucible 5 is provided outside the main chamber 1 so as to surround the main chamber 1. The magnetic field generator 17 generates, for example, a horizontal magnetic field toward the quartz crucible 5 and is composed of an electromagnetic coil or the like. The magnetic field generator 17 can be configured to apply a horizontal magnetic field to the quartz crucible 5, but a cusp magnetic field, which is a magnetic field configuration formed when a current in the reverse direction is passed through a pair of circular coils, is applied to the quartz crucible. 5 may be provided.

  A convection control member 35 is disposed in the silicon melt 4. The convection control member 35 controls the convection of the silicon melt 4 so that the depth La of the silicon melt 4 is the distance Lb between the convection control member 35 and the melt surface 4a. is there. The position of the convection control member 35 with respect to the melt surface 4a is such that the depth La of the silicon melt 4 is decreased from the start of pulling up so that the depth La of the silicon melt 4 is the lowest part of the convection control member 35 at the start of pulling up. It is controlled by a position control means to be described later so as not to change until the time when it becomes less than the vertical distance Lb between the liquid surface 4a and the melt surface 4a. In the present embodiment, the lowermost portion of the convection control member 35 is a central portion 35a that intersects the central axis of the silicon single crystal 3 on the lower surface of the convection control member 35, as shown in FIG.

  Further, as shown in FIG. 2A, the convection control member 35 is substantially plate-shaped made of quartz, which is the same material as the quartz crucible 5, and is centered on the central axis 15 of the silicon single crystal 3. A bottom portion 35b that curves downward with a predetermined curvature, and a bottom corner portion that is integrated with the bottom portion 35b and curved upward from the edge of the bottom portion 35b with a smaller curvature than the bottom portion 35b. 2c, and has a circular shape in plan view with the center axis 15 of the silicon single crystal 3 to be pulled up as the center 15, and does not come into contact with the quartz crucible 5 when moved up and down. Have a diameter slightly smaller than the inner diameter of the quartz crucible 5.

Although the dimension of the convection control member 35 is not specifically limited, For example, it can be set as the dimension shown below.
The inner diameter φ of the convection control member 35 is 0.1 to 1.0φ ₀ and preferably 0.7 to 0.9φ ₀ when the inner diameter of the quartz crucible 5 is φ ₀ . The curvature R of the bottom 35b of the convection control member 35 is 0.1 to 1.8R ₀ , preferably 0.7 to 1.2R _{0 when the} curvature of the bottom of the quartz crucible 5 is R _0, and preferably 0.7 to 1.2R _0. It is more desirable that the outer surface shape of this is substantially the same as the inner surface shape of the bottom of the quartz crucible 5. Curvature r of the bottom corner portion 35c of the convection control member 35, 0.1~1.8r ₀ when the curvature of the bottom corner portion of the quartz crucible 5 and r _0, and preferably from 0.7～1.2R ₀ . The thickness t1 of the convection control member 35 is 1 to 100 mm, and preferably 5 to 30 mm. The height of the convection controlling member 35 H1 is the height of the quartz crucible 5 is a 0.1～1.8H ₀ When H _0, and preferably from 0.7~1.2H _0.

  The shape of the convection control member 35 is not limited to the above shape, and for example, a conical surface shape, a paraboloid shape, or a spherical shape may be formed on the bottom surface in the convection control member 35. By using the bottom surface in the convection control member 35 having such a shape, the convection immediately below the solid-liquid interface is controlled to a desired state, and the shape of the solid-liquid interface at the time of pulling is made upward or downward convex. Furthermore, the height of the convex portion can be adjusted, and the quality of the target silicon single crystal 3 such as defect distribution and oxygen concentration can be controlled appropriately. Depending on the pulling conditions, the bottom surface in the convection control member 35 having such a shape can be used to further control the convection of the silicon melt during pulling.

As shown in FIGS. 1 and 2A, the convection control member 35 is supported by a support piece 36 formed integrally with the convection control member 35. The support piece 36 is made of quartz similar to the convection control member 35, and extends vertically from the upper end of the bottom corner portion 35 c of the convection control member 35. At the upper end of the support piece 36, as shown in FIG. 2A, a joint 36 b is formed that is bent at a substantially right angle toward the inside of the quartz crucible 5. Further, the support pieces 36 are formed at two locations facing each other across the central axis 15 of the silicon single crystal 3.
The length H2 from the upper end of the support piece 36 to the upper end of the bottom corner portion 35c is not particularly limited. For example, when the depth La of the silicon melt 4 at the start of pulling is L ₀ , 0.1 to 1.8L ₀ , preferably 0.2 to 1.8 L ₀ .
Further, the thickness t2 of the support piece 36 is 1 to 300 mm, and is desirably thicker than the thickness t1 of the convection control member 35, and specifically, 5 to 80 mm.
In addition, as shown to Fig.2 (a), although the support piece 36 and the convection control member 35 may be formed integrally, each shall consist of a separate member and it uses appropriate fixing means. It may be fixed.

  Further, as shown in FIGS. 1 and 2A, the lower end portion of the substantially C-shaped attachment member 36a is hooked on the joint 36b of the support piece 36 so that the joint 36b is placed from below the joint 36b. It is detachably attached. The lower end of the wire 31 penetrating the gas rectifying cylinder 11 and the main chamber 1 is attached to the upper end portion of the attachment member 36a. The attachment member 36a is formed from W (W alloy), Mo (Mo alloy), or the like. Further, the thickness and size of the attachment member 36a are not particularly limited as long as they have sufficient strength to support the load applied when the support piece 36 is attached.

  The convection control member 35 is a wire support that supports the support piece 36, the attachment member 36 a, the wire 31, and the wire 31 penetrating the gas rectifying cylinder 11 at an appropriate position in a plane above the gas rectifying cylinder 11. A member 37, a support jig 34 such as a pulley for supporting the wire 31 penetrating the main chamber 1 inside the main chamber 1 and feeding it in a predetermined direction, and a wire 31 provided outside the main chamber 1 are wound. It is supported by two position adjusting means including a motor 32 that rotationally drives the rotated gear 33 so as to be movable in the vertical direction.

  In the present embodiment, the single crystal pulling apparatus 30 includes two position adjusting means. However, the number of position adjusting means is not particularly limited, and may be three or more. When the number of position adjusting means is three or more, three or more support pieces 36 are provided point-symmetrically with respect to the center point of the convection control member 35 that coincides with the center of the quartz crucible 5, so that the convection control member 35 is provided. However, if the number of position adjusting means increases, the number of contamination factors in the chamber increases and the contamination factors mixed in the silicon melt increase. For this reason, it is desirable that the number of position adjusting means is two or three. Furthermore, although the convection control member 35 is supported by the wire 31, the convection control member 35 can also be supported by a bar-shaped member having a rectangular cross section extending in the vertical direction. In this case, the convection control member 35 and the rod-shaped member are connected, a rectangular cross-section through hole is provided in the gas rectifying cylinder and the main chamber instead of the rotation support jig, and the rotation around the rod-shaped member is regulated By making it possible to move up and down, one position adjusting means can be provided.

The depth La of the silicon melt 4 varies depending on the decrease in the silicon melt 4 accompanying the pulling. The depth La of the silicon melt 4 at the start of pulling is determined by the diameter and length of the silicon single crystal 3 to be pulled up, the shape of the quartz crucible 5 and the like, and is not particularly limited. In the case of pulling up the single crystal 3, it is 0 to 1000 mm, preferably 5 to 800 mm.
The vertical distance Lb between the lowermost part of the convection control member 35 and the melt surface 4a at the start of pulling is the convection range directly below the solid-liquid interface that affects the quality of the grown single crystal. is set as the vertical distance, for example, the depth La of the silicon melt 4 at the pulling start is the 0.1～1.0L ₀ When L _0, is preferably a 0.3～1.0L ₀ The The distance Lb is preferably set as a range in which the rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying means is 40% or less. The rate of change during the pulling of the magnetic field distribution is preferably set to 40% or less, more preferably 30% or less, or 20% or less.

  Further, an inert gas such as argon gas can be introduced from the gas inlet 10 provided at the upper part of the pulling chamber 1, and after passing between the silicon single crystal 3 being pulled and the gas rectifying cylinder 11, The heat shielding member 12 and the melt surface 4 a of the silicon melt 4 can be passed between and discharged from the gas outlet 9.

  In order to grow a silicon single crystal by the CZ method using such a single crystal pulling apparatus 30, first, a silicon raw material is accommodated and filled in the quartz crucible 5, and the heater 7 is used in the quartz crucible 5. A silicon raw material is heated and melted to obtain a silicon melt 4. Next, in a state of being supported by two position adjusting means including a support piece 36, an attachment member 36 a, a wire 31, a wire support member 37, a support jig 34, and a motor 32 so as to be movable in the vertical direction. The convection control member 35 is disposed at a position Lb added from the surface of the silicon melt 4 as a predetermined position in the silicon melt 4. The position of the convection control member 35 with respect to the melt surface 4a is adjusted by a position adjusting means. The adjustment by the position adjusting means is performed by operating the motor 32 and rotationally driving the gear 33 in the forward direction or the opposite direction.

  Subsequently, the magnetic field generator 17 is operated to start application of a magnetic field such as a horizontal magnetic field into the quartz crucible 5, and the temperature of the silicon melt 4 is raised to a starting temperature. The timing for starting the application of the magnetic field can be appropriately selected according to the target quality of the silicon single crystal 3 to be grown. The strength of the applied magnetic field is preferably set to 1000 G or more when the maximum strength is a horizontal magnetic field at the time of pulling up. In addition, the cusp magnetic field is preferably set so that the magnetic field strength at the intersection (substantially a plane circle) between the neutral surface and the inner surface of the quartz crucible is about 50G. Further, the height position of the magnetic field center can be in the range from the upper end to the bottom of the quartz crucible 5 at the time of pulling up, and when it is in the vicinity of the melt surface 4a of the silicon melt 4, the convection of the silicon melt is effective. It is desirable that it can be suppressed. Here, the height position of the magnetic field center means the height position of the center of the magnetic field generating coil in the case of a horizontal magnetic field, and in the case of a cusp magnetic field, the vertical and horizontal magnetic field components are zero. Means a position. In addition, it can be changed appropriately before or after the completion of melting according to the characteristics of the single crystal to be pulled up (start timing, strength, maximum strength position height, etc.) and the filling and melting state of the silicon raw material. .

Thereafter, the single crystal pulling step is started as shown below.
That is, the quartz crucible 5 is rotated at a predetermined speed by the crucible drive mechanism 21, the seed crystal 16 fixed to the wire 14 is immersed in the silicon melt 4 in the quartz crucible 5, and gently pulled up while rotating to seed the seed Then, the silicon single crystal 3 having a substantially cylindrical straight body portion is grown by expanding the diameter to a desired diameter. The crystal rotation can be set to an arbitrary value depending on the characteristics of the crucible and the pulled crystal.
In the present embodiment, the pulling up of the silicon single crystal 3 is first performed as a convection control member suspension process in which the convection control member 35 is not in contact with the bottom of the quartz crucible 5, and the cusp magnetic field from the magnetic field generator 17 into the quartz crucible 5. And the position of the convection control member 35 disposed in the silicon melt 4 with respect to the melt surface 4a is determined by the decrease in the silicon melt 4 accompanying the pulling of the depth La of the silicon melt 4 from the start of the pulling. Control is performed so as not to change until the time when the distance becomes less than Lb.

  In the present embodiment, the vertical height of the melt surface 4 a during the pulling of the silicon single crystal 3 is controlled by the crucible drive mechanism 21 to be constant. Therefore, the position of the convection control member 35 relative to the melt surface 4a during the pulling of the silicon single crystal 3 is determined by the crucible drive mechanism 21 so that the depth La of the silicon melt 4 is increased from the start of the pulling of the silicon melt 4 accompanying the pulling. Control is performed so as not to change until the time when the distance becomes less than the distance Lb. The crucible drive mechanism 21 can be controlled using position control means (not shown). The position control means includes, for example, the position of the quartz crucible 5, the position of the convection control member 35 measured by a CCD camera, the position of the melt surface 4a of the silicon melt 4, the pulling length of the silicon single crystal 3, the temperature in the chamber The position of the quartz crucible 5 in the vertical direction is moved by the crucible drive mechanism 21 in accordance with information such as the surface temperature of the silicon melt 4 and the gas flow rate.

  In the present embodiment, the method of controlling the position of the convection control member 35 relative to the melt surface 4a during the pulling of the silicon single crystal 3 by the crucible drive mechanism 21 has been described as an example. The position of the convection control member 35 with respect to the melt surface 4a during the pulling may be adjusted by the position adjusting means.

  Thereafter, the growth of the silicon single crystal 3 is continued, and when the depth La of the silicon melt 4 becomes less than the distance Lb as shown in FIG. 5 As the convection control member placement process in which the convection control member 35 is placed on the bottom and rotates together with the quartz crucible 5, the outer surface of the bottom 35 b of the convection control member 35 is placed on the inner surface of the bottom of the quartz crucible 5. As a result, the load of the convection control member 35 loaded on the wire 31 of the position adjusting means moves to the quartz crucible 5. When the silicon single crystal 3 is further grown and the silicon melt 4 is reduced, the tension of the wire 31 of the position adjusting means is relaxed, and a gap is formed between the joint 36b of the support piece 36 and the lower end of the mounting member 36a. When the quartz crucible 5 is rotated by the crucible drive mechanism 21, the support piece 36 is detached from the attachment member 36a. When the support piece 36 is removed from the attachment member 36a, the convection control member 35 and the support piece 36 rotate in conjunction with the rotation of the quartz crucible 5 under the control of the crucible drive mechanism 21 in a state of being integrated with the quartz crucible 5. It will be a thing. The attachment member 36a removed from the support piece 36 has a height that does not hinder the growth of the silicon single crystal 3 by adjusting the length of the wire 31 by rotating the gear 33 by the motor 32. Can be moved to a position.

  Thereafter, the growth of the silicon single crystal 3 is continued, and after the growth of the silicon single crystal 3 is completed, the convection control member 35 is raised from the inner surface of the bottom portion of the quartz crucible 5 by heating with the heater 7, thereby convection. The control member 35 and the quartz crucible 5 are separated. The convection control member 35 separated from the quartz crucible 5 can be used again by being cooled by an appropriate cooling method.

In the present embodiment, the amount of the remaining silicon melt 4 during pulling of the silicon single crystal 3 is large, and the depth La of the silicon melt is such that the silicon single crystal 3 on the lower surface of the convection control member 35 at the start of pulling. The convection of the silicon melt 4 when the distance in the vertical direction between the central portion 35a intersecting the central axis of the melt and the melt surface 4a is deeper than Lb, the depth of the silicon melt 4 is controlled by the convection control member 35. It is controlled so as to be in a state when La is the distance Lb.
Therefore, in this embodiment, the fluctuation of the convection of the silicon melt 4 from the start of the pulling up to the time when the amount of the silicon melt 4 being pulled becomes less than the distance Lb becomes very small. As a result, it becomes possible to reduce the quality difference of the single crystals depending on the amount of the remaining liquid of the silicon melt 4, and it is possible to manufacture single crystals having a desired quality with high yield.

(Second embodiment)
FIG. 4 is a schematic sectional view of a single crystal manufacturing apparatus according to the second embodiment of the present invention. FIG. 5 is a diagram for explaining the convection control member provided in the single crystal manufacturing apparatus shown in FIG. 4. FIG. 5A is a diagram in which the convection control member is cut in the diametrical direction at the portion where the support piece is provided. It is sectional drawing, (b) is a top view of a convection control member, FIG.5 (c) is a perspective view of Fig.5 (a).
In the single crystal manufacturing apparatus shown in FIG. 4, the only difference from the single crystal manufacturing apparatus shown in FIG. 1 is the point relating to the position adjusting means for supporting the convection control member 35. The means will be described in detail, and the single crystal manufacturing apparatus and members shown in FIG.

In this embodiment, as shown in FIG. 4, the convection control member 35 is provided at the uppermost portion of the support piece 18, the joining member 18 b, the support ring 18 a, the attachment member 36 a, the wire 31, and the pulling chamber 2. The rotary plate 38 and the motor 32 that is provided on the outer surface of the rotary plate 38 and rotates the gear 33 around which the wire 31 is wound are supported by two position adjusting means so as to be movable in the vertical direction. Yes.
The support piece 18 is made of quartz as in the configuration shown in FIG. 1, and extends upward from the upper end of the bottom corner portion 35c of the convection control member 35 as shown in FIGS. 5 (a) to 5 (c). Is formed. In addition, one end of a rod-shaped joining member 18b is fixed at two locations facing each other across the central axis 15 of the silicon single crystal 3 at the upper end of the support piece 18. A support ring 18a is fixed to the other end of the joining member 18b.

  The joining member 18b is formed from quartz, graphite, Mo, or the like. The width and thickness of the joining member 18b are not particularly limited as long as the joining member 18b has sufficient strength to support a load applied when the support ring 18a is attached to the attachment member 36a.

Further, as shown in FIG. 4, the support ring 18 a has an outer diameter smaller than the inner diameter of the convection control member 35, and has a ring shape with a rectangular cross section having an inner diameter larger than the outer diameter of the silicon single crystal 3. Is. Specifically, the inner diameter D of the support ring 18a is set such that the mounting member 36a can be attached and detached without affecting the single crystal 3. For example, when the outer diameter of the silicon single crystal 3 is D ₀ , the inner diameter D is 0.1. It is a ~10D _0, and preferably from 1~2D _0.
The support ring 18a is made of quartz, graphite, Mo, or the like. The thickness of the support ring 18a is not particularly limited as long as it has sufficient strength to support a load applied when the support piece 36 is attached. Specifically, for example, the horizontal thickness t3 of the support ring 18a is 1 to 300 mm, and preferably 5 to 80 mm.

The cross-sectional shape of the support ring 18a can be rectangular, but is not limited to the rectangular shape, and can be hooked on the substantially C-shaped attachment member 36a, and the attachment member can be loosened by loosening the tension of the wire 31. Any shape can be used as long as it can be removed from 36a, for example, a circular cross section. If the cross-sectional shape of the support ring 18a has a circular shape, the diameter phi ₃ in the cross section of the support ring 18a is a 1 to 300 mm, it is desirable that is 5～80Mm.

  The fixing between the support piece 18 and the joining member 18b and the fixing between the support ring 18a and the joining member 18b may be performed by any method and are not particularly limited. Further, the convection control member 35, the support piece 18, the joining member 18b, and the support ring 18a may be made of separate members, and they may be fixed to each other by using appropriate fixing means. A member formed by integrating two or more members may be used.

  Further, as shown in FIGS. 5A and 5C, the attachment member 36a is attached to the support ring 18a so that the lower end portion of the substantially C-shaped attachment member 36a is connected to the support ring 18a from below the support ring 18a. It is detachably attached by hooking it so as to be placed. Further, as shown in FIG. 4, the lower end of the wire 31 that penetrates the rotating plate 38 is attached to the upper end portion of the attachment member 36a.

As shown in FIG. 4, the rotating plate 38 is provided at the uppermost part of the pulling chamber 2 and rotates around the central axis 15 of the silicon single crystal 3. The rotating plate 38 includes an outer peripheral portion 38a and a central portion 38b provided on the inner side of the outer peripheral portion 38a, and the outer peripheral portion 38a and the central portion 38b are individually rotatable.
The outer peripheral portion 38a of the rotating plate 38 is controlled by a position control means (not shown) that controls the crucible driving mechanism 21 so as to rotate synchronously at the same speed in the same direction as the rotation of the quartz crucible 5. The convection control member 35 rotates about the central axis 15 of the silicon single crystal 3 in conjunction with the rotation of the outer peripheral portion 38a.
As shown in FIG. 4, a gear 40 around which a wire 14 for suspending the silicon single crystal 3 is wound and a motor 41 that rotates the gear 40 are provided on the outer surface of the central portion 38 b. Yes. The wire 14 passes through the central portion 38b of the central axis 15 of the silicon single crystal 3 so as to support the silicon single crystal 3, and rotates around the central axis 15 in conjunction with the rotation of the central portion 38b. ing.

In order to grow a silicon single crystal by the CZ method using the single crystal pulling apparatus 30 shown in FIG. 4, first, the silicon raw material is melted to form the silicon melt 4 in the same manner as in the first embodiment, and the support is performed. In a state of being supported by two position adjusting means including a piece 18, a joining member 18b, a support ring 18a, a mounting member 36a, a wire 31, a rotating plate 38, and a motor 32 so as to be movable in the vertical direction. The convection control member 35 is disposed at a predetermined position in the silicon melt 4.
Subsequently, in the same manner as in the first embodiment described above, application of a horizontal magnetic field into the quartz crucible 5 is started, and the temperature of the silicon melt 4 is adjusted so as to become the starting temperature.

Thereafter, as shown below, the pulling is started.
That is, as the convection control member suspension process, the quartz crucible 5 is rotated at a predetermined speed by the crucible drive mechanism 21 and the outer peripheral portion 38a of the rotating plate 38 is rotated to rotate the quartz crucible 5 at the same speed in the same direction as the rotation of the quartz crucible 5. Synchronously, the convection control member 35 is rotated about the central axis 15 of the silicon single crystal 3, the seed crystal 16 fixed to the wire 14 is immersed in the silicon melt 4 in the quartz crucible 5, and the center of the rotating plate 38 is After rotating the portion 38b and rotating the wire 14 at a predetermined speed in the direction opposite to the rotation of the quartz crucible 5 while gently pulling the neck portion to squeeze the neck portion, a silicon single piece is formed in the same manner as in the first embodiment described above. Crystal 3 is grown.
Also in the present embodiment, the pulling up of the silicon single crystal 3 applies a horizontal magnetic field from the magnetic field generator 17 into the quartz crucible 5 and also with respect to the melt surface 4 a of the convection control member 35 disposed in the silicon melt 4. The position is controlled in such a manner that the depth La of the silicon melt 4 does not change from the start of the pulling up until the point where the depth La becomes less than the distance Lb due to the decrease in the silicon melt 4 accompanying the pulling.

  Thereafter, the growth of the silicon single crystal 3 is continued, and when the depth La of the silicon melt 4 becomes less than the distance Lb as shown in FIG. As the control member placing step, the outer surface of the bottom portion 35b of the convection control member 35 is placed on the inner surface of the bottom portion of the quartz crucible 5 in the same manner as in the first embodiment described above. The load of the convection control member 35 loaded on the quartz crucible 5 moves to the quartz crucible 5. When the silicon single crystal 3 is further grown and the silicon melt 4 is reduced, the tension of the wire 31 of the position adjusting means is relaxed, and a gap is generated between the support ring 18a and the lower end of the mounting member 36a. The support ring 18a is removed from the attachment member 36a. When the support ring 18 a is removed from the attachment member 36 a, the convection control member 35, the support piece 18, the joining member 18 b, and the support ring 18 a are integrated with the quartz crucible 5 and controlled by the crucible drive mechanism 21. It will rotate in conjunction with the rotation of. Further, the attachment member 36a removed from the support ring 18a has a height that does not hinder the growth of the silicon single crystal 3 by adjusting the length of the wire 31 by rotationally driving the gear 33 by the motor 32. Can be moved to a position.

  Also in this embodiment, the residual amount of the silicon melt 4 during pulling of the silicon single crystal 3 is large, and the depth La of the silicon melt is such that the silicon single crystal 3 on the lower surface of the convection control member 35 at the start of pulling. The convection of the silicon melt 4 when the distance in the vertical direction between the central portion 35a intersecting the central axis of the melt and the melt surface 4a is deeper than Lb, the depth of the silicon melt 4 is controlled by the convection control member 35. It is controlled so as to be in a state when La is the distance Lb. Therefore, the fluctuation of the convection of the silicon melt 4 from the start of the pulling up to the time when the amount of the silicon melt 4 being pulled becomes less than the distance Lb becomes very small.

Further, in this embodiment, the convection control member 35 is rotated about the central axis 15 of the silicon single crystal 3 at the same speed in the same direction as the rotation of the quartz crucible 5, so that the crucible rotation is about 1 rpm. Even in the case of a high rotational speed condition, for example, a rotational condition of about 1 to 10 rpm, the convection region can be obtained without damaging the characteristics of the single crystal 3 affected by the crucible rotational speed with parameters other than convection control. It is possible to pull up by controlling the depth below the depth Lb.
In the present embodiment, the pulling process is performed in synchronization with the rotation state of the quartz crucible 5 and the rotation state of the convection control member 35. However, the diameter size control and pulling speed control of the single crystal 3 to be pulled up are controlled by the crucible rotation speed. In the case of adjusting by means of, for example, not only the crucible rotation speed but also the rotation state of the convection control member 35 can be controlled, so that finer control can be performed, and V / G (mm ² / ° C./min described later) ) Range control and the like can be performed more finely. As a result, a single crystal having a predetermined characteristic such as a defect-free crystal can be easily manufactured.
Furthermore, in the present embodiment, the support piece 18, the joining member 18 b, the support ring 18 a, and the wire 31 are far away from the heater 7 on the single crystal 3 side of the heat shield member 12, that is, inside the heat shield member 12. By being located on the side, when the pulling is performed at the same temperature state, the thermal load on these members can be reduced, and it is possible to provide a margin for the heat-resistant temperature.

"Experiment 1"
Using the single crystal pulling apparatus 30 shown in FIG. 1, the relationship between the yield and the solidification rate when the silicon single crystal 3 having a diameter of 200 mm was grown by the CZ method was obtained by simulation analysis.
The yield here refers to the pass rate when the pulling rate V when growing the silicon single crystal is within the range of V ₀ ± 0.01 (mm / min) as the pass rate, the solidification rate of 0.025. The value obtained every time. This is because when the pulling speed is within the above range, a single crystal capable of manufacturing a defect-free wafer without crystal defects such as COP is pulled in the actual pulling.
Specifically, for example, if the maximum speed at which a _COP does not occur during a test is defined as V _COP and the minimum speed at which no LD (large dislocation) occurs is defined as V _LD , the pulling speed V ₀ = ( V _COP + V _LD ) / 2.
The pulling conditions excluding the pulling speed V were conditions for growing a silicon single crystal having a defect-free region over the entire length of the pulling length (solidification rate) as shown below.
That is, the distribution difference ΔG = −0.03 to 0.03G _{0 in} the radial direction of the crystal temperature gradient G (° C./mm) in the pulling axis direction near the solid-liquid interface when growing a silicon single crystal (where G ₀ is V / G (mm ² / ° C./min), which is the ratio between the pulling rate V (mm / min) and the crystal temperature gradient G (° C./mm) when growing a silicon single crystal ) Radial distribution difference Δ (V / G) = − 0.005 to 0.005, and using a condition optimized to obtain the highest pass rate when the solidification rate is 5%, a silicon single crystal The pulling conditions were not changed according to the solidification rate during pulling.
The specific conditions are
Lb = 180mm
La (initial value) = 400 mm
La (end value) = 30 mm
Crucible inner diameter = 600mm
Lifting length = 3000mm
Crystal rotation = 10 rpm
Crucible rotation = 1 rpm

"Experimental example 2"
The yield when the silicon single crystal 3 is grown by the CZ method in the same manner as in Experimental Example 1 using the single crystal pulling apparatus similar to that in Experimental Example 1 except that the convection control member 35 and the position adjusting means are not provided. The relationship between the solidification rate and the solidification rate was obtained by simulation analysis. The pulling conditions here were the same as in Experimental Example 1 except for Lb.

"Experiment 3"
The yield when the silicon single crystal 3 is grown by the CZ method in the same manner as in Experimental Example 1 using the single crystal pulling apparatus similar to that in Experimental Example 1 except that the convection control member 35 and the position adjusting means are not provided. The relationship between the solidification rate and the solidification rate was obtained by simulation analysis. The pulling conditions here were optimized so as to obtain the highest pass rate when the solidification rate was 95%.
The specific conditions are
La (initial value) = 400 mm
La (end value) = 30 mm
Crucible inner diameter = 600mm
Lifting length = 3000mm
Crystal rotation = 10 rpm
Crucible rotation = 1 rpm

The results of Experimental Examples 1 to 3 are shown in FIG. FIG. 7 is a graph showing the relationship between the pass rate and the solidification rate in the silicon single crystals of Experimental Examples 1 to 3.
As shown in FIG. 7, in Experimental Example 1, a high pass rate of 70% or more was obtained regardless of the solidification rate, and the difference in the pass rate depending on the solidification rate was small.
Also, from FIG. 7, in Experimental Example 2 using conditions optimized so that the highest pass rate can be obtained when the solidification rate is 5%, the pass rate gradually decreases as the solidification rate increases. Compared with Experimental Example 1, the difference in the pass rate depending on the solidification rate was very large. In Experimental Example 3 using conditions optimized to obtain the highest pass rate when the solidification rate is 95%, the pass rate gradually increases as the solidification rate increases. Compared with 1, the difference in the pass rate depending on the solidification rate became very large.
As described above, in Experimental Example 1 including the convection control member 35 and the position adjusting means, compared with Experimental Example 2 and Experimental Example 3 that do not include the convection control member 35 and the position adjusting means, the pass rate depends on the solidification rate. Since the difference is small, it was confirmed that the quality difference of the single crystal depending on the residual amount of the silicon melt can be reduced by providing the convection control member 35 and the position adjusting means.

"Experimental example 4"
Using the single crystal pulling apparatus 30 shown in FIG. 1, the relationship between the specific resistance and the solidification rate when an arsenic dopant silicon single crystal 3 having a diameter of 150 mm was grown by the CZ method was determined by simulation analysis.
The pulling conditions excluding the pulling speed V were not changed according to the solidification rate during pulling of the silicon single crystal.
The specific conditions are
Lb = 100mm
La (initial value) = 300 mm
La (end value) = 30 mm
Crucible inner diameter = 450 mm
Lifting length = 3000mm
Crystal rotation = 10 rpm
Crucible rotation = -10 rpm

"Experimental example 5"
The ratio when the silicon single crystal 3 is grown by the CZ method in the same manner as in Experimental Example 4 using the same single crystal pulling apparatus as in Experimental Example 4 except that the convection control member 35 and the position adjusting means are not provided. The relationship between resistance and solidification rate was obtained by simulation analysis. The pulling conditions here were the same as in Experimental Example 1 except for Lb.

  The results of Experimental Example 4 to Experimental Example 5 are shown in FIG. FIG. 8 is a graph showing the relationship between the specific resistance and the solidification rate of the silicon single crystals of Experimental Example 4 to Experimental Example 5 when the maximum value of the specific resistance of Experimental Example 5 is 100. As shown in FIG. 8, in the experimental example 4 provided with the convection control member 35 and the position adjusting means, the resistivity depending on the solidification rate is compared with the experimental example 5 not provided with the convection control member 35 and the position adjusting means. Since the difference is small, it was confirmed that the quality difference of the single crystal depending on the residual amount of the silicon melt can be reduced by providing the convection control member 35 and the position adjusting means.

FIG. 1 is a schematic cross-sectional view of a single crystal manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a view for explaining a convection control member provided in the single crystal manufacturing apparatus shown in FIG. FIG. 3 is a schematic cross-sectional view for explaining a method of manufacturing a silicon single crystal using the single crystal manufacturing apparatus shown in FIG. FIG. 4 is a schematic sectional view of a single crystal manufacturing apparatus according to the second embodiment of the present invention. FIG. 5 is a diagram for explaining a convection control member provided in the single crystal manufacturing apparatus shown in FIG. 4. FIG. 6 is a schematic cross-sectional view for explaining a method for manufacturing a silicon single crystal using the single crystal manufacturing apparatus shown in FIG. FIG. 7 is a graph showing the relationship between the pass rate and the solidification rate in the silicon single crystals of Experimental Examples 1 to 3. FIG. 8 is a graph showing the relationship between the specific resistance and the solidification rate in the silicon single crystals of Experimental Examples 4 to 5.

Explanation of symbols

1: main chamber, 3: silicon single crystal, 2: pulling chamber, 4: silicon melt, 4a: melt surface, 5: quartz crucible, 6: graphite crucible, 7: heater, 11: gas rectifying cylinder, 12 : Heat shield member, 13: holding shaft, 15: central shaft, 17: magnetic field generator (magnetic field applying means), 18, 36: support piece, 18b: joining member, 18a: support ring, 21: crucible drive mechanism, 30 : Single crystal manufacturing apparatus, 14, 31: Wire, 32, 41: Motor, 33, 40: Gear, 34: Rotation support jig, 35: Convection control member, 36b: Joint, 36a: Mounting member, 37: Wire support Member, 38: rotating plate 38, 38a: outer peripheral portion, 38b: central portion.

Claims (11)

A single crystal manufacturing apparatus for growing a silicon single crystal while pulling it up from a silicon melt contained in a crucible,
When the depth La, which is the distance between the surface of the silicon melt and the bottom surface of the crucible, exceeds the vertical distance Lb, the solid that affects the quality of the single crystal grown in the silicon melt. A convection control member, which is a plate-like body substantially parallel to the bottom surface of the crucible, is provided between the bottom surface of the crucible and the solid-liquid interface so that the convection range immediately below the liquid interface is within the distance Lb. A single crystal manufacturing apparatus.   The single crystal manufacturing apparatus according to claim 1, wherein the convection control member has a circular shape in a plan view centered on a central axis of the silicon single crystal to be pulled up.   3. The single crystal manufacturing apparatus according to claim 1, wherein the convection control member is at a position including at least a range where the silicon single crystal exists in a plan view.   The single crystal manufacturing apparatus according to any one of claims 1 to 3, further comprising a magnetic field applying unit that controls convection of the silicon melt.   The single crystal manufacturing apparatus according to claim 4, wherein the distance Lb is set as a range in which a rate of change during pulling of the magnetic field distribution applied by the magnetic field applying unit is 40% or less. A method for producing a silicon single crystal using the single crystal production apparatus according to any one of claims 1 to 5,
Installing the convection control member, which is a plate-like body substantially parallel to the bottom surface of the crucible, at a position of the distance Lb from the solid-liquid interface;
When the depth La, which is the distance between the surface of the silicon melt and the bottom surface of the crucible, exceeds the distance Lb, immediately below the solid-liquid interface that affects the quality of the single crystal grown in the silicon melt. The single crystal manufacturing method is characterized in that the convection range is controlled to be within the distance Lb. Melting the silicon raw material in the crucible to produce a silicon melt;
Disposing the convection control member at a predetermined position in the silicon melt;
The method for producing a single crystal according to claim 6, wherein the single crystal pulling step is started after sequentially performing the step of adjusting the temperature of the silicon melt to the pulling start temperature.   The method for producing a single crystal according to claim 6 or 7, wherein, in the single crystal pulling step, the silicon single crystal is pulled while applying a magnetic field to the silicon melt by the magnetic field applying means.   9. The method for producing a single crystal according to claim 8, wherein the distance Lb is set as a range in which the rate of change during pulling up of the magnetic field distribution applied by the magnetic field applying means is 40% or less.   The method for producing a single crystal according to claim 6, wherein the single crystal having a defect-free region is pulled up. A single crystal produced by the single crystal production apparatus according to any one of claims 1 to 5 or the single crystal production method according to any one of claims 6 to 10.

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