JP7632233B2 - Heat shielding member and its part set, and single crystal manufacturing apparatus and single crystal manufacturing method using the heat shielding member - Google Patents

Description

The present invention relates to a heat shielding member and a part set thereof used in pulling single crystals by the Czochralski method (CZ method). The present invention also relates to a single crystal manufacturing apparatus and a single crystal manufacturing method using such a heat shielding member.

Most of the silicon single crystals used as substrate materials for semiconductor devices are manufactured by the CZ method. In the CZ method, a seed crystal is immersed in molten silicon contained in a quartz crucible, and the seed crystal and the quartz crucible are rotated while the seed crystal is gradually pulled up, causing a large single crystal to grow at the bottom end of the seed crystal. The CZ method makes it possible to manufacture high-quality silicon single crystal ingots with a high yield.

In order to improve the crystal quality of silicon single crystals, the CZ method uses a heat shielding member that surrounds the silicon single crystal pulled up from the silicon melt to shield it from radiant heat from the heater. With regard to heat shielding members, for example, Patent Document 1 describes a method of preventing the concentration of thermal stress in the notch by dividing the disk-shaped bottom plate of the heat shield into two parts. Patent Document 2 describes a heat shielding member in which only the bottom of the bulge can be replaced.

Patent Document 3 describes changing the distance of multiple heat radiators configured to be radially movable relative to the peripheral surface of the silicon single crystal rod in order to pull up silicon single crystal rods with different straight body diameters without replacing the heat shielding member. When forming the shoulder of the silicon single crystal rod, the multiple heat radiators are moved to a position away from the shoulder, and when forming the straight body of the silicon single crystal rod, the multiple heat radiators are moved near the straight body.

Silicon single crystals are used not only as substrate materials for semiconductor devices, but also as electrode materials for plasma etching equipment, for example. Patent Document 4 describes the use of silicon single crystals as electrode plates for plasma etching equipment.

JP 2004-323322 A JP 2004-352581 A JP 2000-7488 A JP 2003-51491 A

Unlike silicon single crystals for semiconductors, silicon single crystals for electrode materials do not have a standardized crystal diameter, and the required crystal diameter varies depending on the equipment design. For this reason, in the manufacture of silicon single crystals for electrode materials, there is a demand for efficient production of silicon single crystals with different diameters of the straight body (hereinafter simply referred to as crystal diameter) in accordance with the order volume. In order to meet such demands, traditionally, dedicated heat shielding members were prepared for each crystal diameter to be pulled. However, preparing dedicated heat shielding members for each crystal diameter increases costs due to the increase in the number of parts required, and also poses the problem of securing storage space.

Therefore, the object of the present invention is to provide a heat shielding member and a parts set thereof that enable efficient pulling of single crystals with different crystal diameters using the same CZ pulling furnace, as well as a single crystal manufacturing apparatus and single crystal manufacturing method using the heat shielding member.

In order to solve the above problems, the heat shielding member according to the present invention is used in pulling a single crystal by the CZ method, and is a member that surrounds the single crystal pulled from the melt in a crucible, and includes a substantially cylindrical insulating member and a wall member that covers the exposed surface of the insulating member, the wall member including an outer wall portion that covers at least the outer peripheral surface of the insulating member, an inner wall portion that covers the inner peripheral surface of the insulating member, and a bottom wall portion that covers the lower end surface of the insulating member, the insulating member including a substantially cylindrical first insulating portion and a substantially cylindrical second insulating portion provided inside the first insulating portion, and the second insulating portion is configured to be freely attached and detached from the first insulating portion.

According to the present invention, when pulling multiple types of single crystals with different crystal diameters, the first insulating part of the insulating member and the outer wall part of the wall member are common parts, and the opening size can be changed by omitting or replacing parts inside the first insulating part, such as the second insulating part and the inner wall part. Therefore, multiple types of single crystals with different crystal diameters can be efficiently pulled using the same CZ pulling furnace.

In the present invention, it is preferable that the outer peripheral surface of the first insulating part is covered by the outer wall part, the inner peripheral surface of the second insulating part is covered by the inner wall part, and the outer peripheral surface of the second insulating part is in close contact with the inner peripheral surface of the first insulating part. This allows the first and second insulating parts to be handled as a single insulating member, and by combining the first and second insulating parts, a heat shielding member suitable for pulling a small-diameter single crystal can be provided. In addition, by removing the second insulating part, a heat shielding member suitable for pulling a large-diameter single crystal can be provided.

In the present invention, it is preferable that the bottom wall portion is configured to be detachable from the outer wall portion, the inner wall portion is configured to be detachable from the bottom wall portion and the outer wall portion, and the second bottom wall portion is configured to be detachable from the first bottom wall portion. This makes it possible to accommodate both small-diameter single crystals and large-diameter single crystals.

In the present invention, it is preferable that the upper surface of the inner peripheral end of the bottom wall portion connected to the lower end of the inner wall portion has a tapered surface that is inclined radially outward, and the lower end of the inner wall portion abuts against the tapered surface. This can increase the adhesion between the inner wall portion and the bottom wall portion at the connection position, and the sealing state of the insulating member by the wall member can be maintained. Therefore, even if the insulating member deteriorates and turns into powder, it is possible to prevent deterioration of the yield of single crystals due to the fine powder of the insulating member leaking outward.

In the present invention, it is preferable that the lower end of the outer wall portion connected to the outer peripheral end of the bottom wall portion has a tapered surface that is inclined radially outward, and the outer peripheral end of the bottom wall portion abuts against the tapered surface. This can increase the adhesion between the bottom wall portion and the outer wall portion at the connection position, and the insulating member can be kept sealed by the wall member. Therefore, even if the insulating member deteriorates and turns into powder, it is possible to prevent deterioration of the yield of single crystals due to the fine powder of the insulating member leaking outward.

In the present invention, it is preferable that a protrusion is provided at the lower end of the outer wall portion, and a hook portion that engages with the protrusion is provided at the outer peripheral end of the bottom wall portion. In this case, too, it is possible to increase the adhesion between the bottom wall portion and the outer wall portion at the connection position, and to maintain the sealing state of the insulation member by the wall member.

In the present invention, it is preferable that the difference between the opening diameter of the heat shielding member when the first insulating section is used alone and the opening diameter of the heat shielding member when the first insulating section and the second insulating section are used in combination is 50 mm (approximately 2 inches) or more. This makes it possible to efficiently pull multiple types of single crystals with different crystal diameters using the same CZ pulling furnace.

In the present invention, the inner wall portion is preferably a substantially cylindrical first inner wall portion covering the inner circumferential surface of the first insulating portion, or a substantially cylindrical second inner wall portion covering the inner circumferential surface of the second insulating portion. By using the first inner wall portion in combination with the first insulating portion, a heat shielding member with a large opening size can be realized. Also, by combining the second inner wall portion with the first and second insulating portions, a heat shielding member with a small opening size can be realized.

In the present invention, it is preferable that the difference between the opening diameter of the first inner wall portion and the opening diameter of the second inner wall portion is 50 mm or more. This makes it possible to efficiently pull two types of single crystals with a diameter difference of 50 mm or more.

When pulling a first single crystal, the heat shielding member according to the present invention is preferably such that the second insulating section is omitted and the first insulating section is used alone, and the bottom wall section is omitted and the first inner wall section is used in combination with the outer wall section, and when pulling a second single crystal having a smaller diameter than the first single crystal, the second insulating section is used in combination with the first insulating section and the second inner wall section and the bottom wall section are used in combination with the outer wall section. In this way, the heat shielding member according to the present invention can be applied to both the CZ pulling process of the first and second single crystals having different crystal diameters.

The bottom wall portion is preferably a substantially annular first bottom wall portion covering the lower end surface of the first insulation portion, or a substantially annular second bottom wall portion covering the lower end surfaces of the first and second insulation portions. By using the first bottom wall portion in combination with the first insulation portion and the first inner wall portion, a heat shielding member with a large opening size can be formed. Also, by using the second bottom wall portion in combination with the first and second insulation portions and the second inner wall portion, a heat shielding member with a small opening size can be formed.

When pulling a first single crystal, the heat shielding member according to the present invention is preferably such that the second insulating part is omitted and the first insulating part is used alone, and the first inner wall part and the first bottom wall part are used in combination with the outer wall part, and when pulling a second single crystal having a smaller diameter than the first single crystal, the second insulating part is preferably used in combination with the first insulating part, and the second inner wall part and the second bottom wall part are preferably used in combination with the outer wall part. In this way, the heat shielding member according to the present invention can be applied to both the CZ pulling process of the first and second single crystals having different crystal diameters.

The present invention also relates to a parts set of a heat shielding member used in pulling a single crystal by the CZ method, surrounding the single crystal pulled from the melt in a crucible, comprising a substantially cylindrical first insulating part, a substantially cylindrical second insulating part detachably provided inside the first insulating part, an outer wall part covering the outer peripheral surface of the first insulating part, a first inner wall part covering the inner peripheral surface of the first insulating part, and a second inner wall part covering the inner peripheral surface of the second insulating part, characterized in that the first heat shielding member is composed of the first insulating part, the outer wall part, and the first inner wall part, and the second heat shielding member having an opening diameter smaller than that of the first heat shielding member is composed of the first insulating part, the second insulating part, the outer wall part, and the second inner wall part.

According to the present invention, the opening diameter of the heat shielding member can be changed by adding or replacing some of the components of the heat shielding member, making it possible to accommodate the pulling of multiple types of single crystals with different crystal diameters.

The heat shielding member part set according to the present invention preferably further comprises a bottom wall part covering at least the lower end surface of the second heat insulating part, and the second heat shielding member further comprises the bottom wall part. The heat shielding member part set according to the present invention may further comprise a first bottom wall part covering the lower end surface of the first heat insulating part and a second bottom wall part covering the lower end surfaces of the first and second heat insulating parts, the first heat shielding member further comprises the first bottom wall part, and the second heat shielding member further comprises the second bottom wall part. In this way, by adding or replacing the bottom wall part, it is possible to provide a heat shielding member that can handle the pulling of multiple single crystals with different crystal diameters.

In the present invention, it is preferable that the difference between the opening diameter of the first inner wall portion and the opening diameter of the second inner wall portion is 50 mm or more. This makes it possible to efficiently pull multiple types of single crystals with different crystal diameters using the same CZ pulling furnace.

The single crystal manufacturing apparatus according to the present invention is characterized by comprising a chamber, a crucible that supports the melt within the chamber, a heater that heats the melt, a crucible drive mechanism that rotates and raises and lowers the crucible, a crystal pulling mechanism that pulls the single crystal from the melt, and the heat shielding member according to the present invention described above that is installed above the melt and surrounds the single crystal pulled from the melt to shield it from radiant heat from the heater. According to the present invention, the opening size can be changed by omitting or modifying some parts. Therefore, multiple types of single crystals with different crystal diameters can be efficiently pulled using the same CZ pulling furnace.

The method for producing a single crystal according to the present invention is characterized in that in the CZ method, in which a single crystal is pulled from the melt in a crucible, the single crystal pulled from the melt is surrounded by the heat shielding member according to the present invention described above. According to the present invention, the opening size can be changed by omitting or modifying some parts, and multiple types of single crystals with different crystal diameters can be pulled efficiently.

The method for producing a single crystal according to the present invention preferably uses the heat shielding member formed by using the first insulating part alone to pull a first single crystal having a first crystal diameter, and uses the heat shielding member formed by combining the first insulating part and the second insulating part to pull a second single crystal having a second crystal diameter smaller than the first crystal diameter. This allows the opening size to be changed by omitting or modifying some parts, and allows two types of single crystals with different crystal diameters to be pulled efficiently.

In the present invention, the difference between the first crystal diameter and the second crystal diameter is preferably 50 mm (approximately 2 inches) or more. This allows two types of single crystals with different crystal diameters to be efficiently pulled using the same CZ pulling furnace.

The present invention provides a heat shielding member and a parts set thereof that enable efficient pulling of single crystals with different crystal diameters using the same CZ pulling furnace, as well as a single crystal manufacturing apparatus and single crystal manufacturing method using the heat shielding member.

FIG. 1 is a schematic cross-sectional side view showing the configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the structure of the heat shielding member according to the first embodiment of the present invention in a completed state. FIG. 3 is a schematic cross-sectional view showing the configuration of the heat shielding member according to the first embodiment of the present invention in an exploded state. FIG. 4 is a schematic cross-sectional view showing the structure of a completed heat shielding member according to the second embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing the configuration of a heat shielding member according to a second embodiment of the present invention in an exploded state. FIG. 6 is a schematic cross-sectional view showing the structure of a completed heat shielding member according to the third embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing the structure of a completed heat shielding member according to the fourth embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing the configuration of a heat shielding member according to a fourth embodiment of the present invention in an exploded state. FIG. 9 is a schematic cross-sectional view showing the structure of a completed heat shielding member according to the fifth embodiment of the present invention. FIG. 10 is a schematic cross-sectional view showing the configuration of a heat shielding member according to the fifth embodiment of the present invention in an exploded state. FIG. 11 is a schematic cross-sectional view showing the structure of a heat shielding member in a completed state according to the sixth embodiment of the present invention. FIG. 12 is a schematic cross-sectional view showing the configuration of a heat shielding member according to the sixth embodiment of the present invention in an exploded state. FIG. 13 is a schematic cross-sectional view showing the structure of a completed heat shielding member according to the seventh embodiment of the present invention. FIG. 14 is a schematic cross-sectional view showing the configuration of a heat shielding member according to the seventh embodiment of the present invention in an exploded state.

The following describes in detail a preferred embodiment of the present invention with reference to the attached drawings.

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

As shown in FIG. 1, the single crystal manufacturing apparatus 1 includes a water-cooled chamber 10, a quartz crucible 11 that holds the silicon melt 2 in the chamber 10, a graphite crucible 12 that holds the quartz crucible 11, a rotating shaft 13 that supports the graphite crucible 12, a shaft drive mechanism 14 that drives the quartz crucible 11 to rotate and elevate via the rotating shaft 13 and the graphite crucible 12, a heater 15 that is arranged around the graphite crucible 12, a heat insulating material 16 that is arranged outside the heater 15 and along the inner surface of the chamber 10, a wire 17 for pulling a single crystal that is arranged above the quartz crucible 11 and coaxially with the rotating shaft 13, a wire winding mechanism 18 that is arranged above the chamber 10, and a heat shielding member 20 that is arranged above the quartz crucible 11.

The chamber 10 is composed of a main chamber 10a and a long, cylindrical pull chamber 10b connected to the upper opening of the main chamber 10a, and the quartz crucible 11, the graphite crucible 12, the heater 15, and the heat shielding member 20 are provided in the main chamber 10a. The pull chamber 10b is provided with a gas inlet 10c for introducing an inert gas (purge gas) such as argon gas or a dopant gas into the chamber 10, and the lower part of the main chamber 10a is provided with a gas outlet 10d for discharging the atmospheric gas in the chamber 10. In addition, a sight glass (not shown) is provided in the upper part of the main chamber 10a, and the growth status of the silicon single crystal 3 can be observed through the sight glass.

The quartz crucible 11 is a container made of silica glass with a roughly cylindrical side wall and a curved bottom. The graphite crucible 12 supports the quartz crucible 11 by adhering closely to the outer surface of the quartz crucible 11 in order to maintain the shape of the quartz crucible 11 that has been softened by heating. The quartz crucible 11 and the graphite crucible 12 form a double-structure crucible that supports the silicon melt within the chamber 10.

The graphite crucible 12 is fixed to the upper end of the rotating shaft 13, and the lower end of the rotating shaft 13 passes through the bottom of the chamber 10 and is connected to a shaft drive mechanism 14 provided outside the chamber 10. The rotating shaft 13 and the shaft drive mechanism 14 constitute a crucible drive mechanism that rotates and raises and lowers the quartz crucible 11.

The heater 15 is used to heat the silicon raw material filled in the quartz crucible 11 to generate the silicon melt 2 and to maintain the silicon melt 2 in a molten state. The heater 15 is a resistance heating heater made of carbon and is provided so as to surround the quartz crucible 11 inside the graphite crucible 12. On the outside of the heater 15, a heat insulating material 16 is provided so as to surround the heater 15, thereby improving the heat retention inside the chamber 10.

Above the quartz crucible 11, there is provided a wire 17, which is the shaft for pulling up the silicon single crystal 3, and a wire winding mechanism 18 for winding up the wire 17. The wire winding mechanism 18, together with the wire 17, constitutes a crystal pulling mechanism for pulling up the silicon single crystal 3 while rotating it. The wire winding mechanism 18 is disposed above the pull chamber 10b, and the wire 17 extends downward from the wire winding mechanism 18 through the pull chamber 10b, with the tip of the wire 17 reaching the internal space of the main chamber 10a. Figure 1 shows a state in which the silicon single crystal 3 is suspended from the wire 17 during growth. When pulling up the silicon single crystal 3, the wire 17 is gradually pulled up while rotating the quartz crucible 11 and the silicon single crystal 3, thereby growing the silicon single crystal 3.

The heat shielding member 20 is provided to suppress temperature fluctuations in the silicon melt 2 to form an appropriate hot zone near the crystal growth interface, and to prevent heating of the silicon single crystal 3 by radiant heat from the heater 15 and the quartz crucible 11. The heat shielding member 20 is a roughly cylindrical graphite member that is provided to cover the area above the silicon melt 2 excluding the pulling path for the silicon single crystal 3.

The diameter of the opening 20a at the lower end of the heat shielding member 20 is larger than the diameter of the silicon single crystal 3, thereby ensuring a path for pulling up the silicon single crystal 3. In addition, the outer diameter of the lower end of the heat shielding member 20 is smaller than the diameter of the quartz crucible 11, and the lower end of the heat shielding member 20 is located inside the quartz crucible 11, so even if the upper end of the rim of the quartz crucible 11 is raised above the lower end of the heat shielding member 20, the heat shielding member 20 will not interfere with the quartz crucible 11.

As the silicon single crystal 3 grows, the amount of melt in the quartz crucible 11 decreases, but by raising the quartz crucible 11 so that the gap between the melt surface and the heat shielding member 20 remains constant, it is possible to suppress temperature fluctuations in the silicon melt 2 and control the amount of dopant evaporation from the silicon melt 2 by keeping the flow rate of the gas flowing near the melt surface constant. This makes it possible to improve the stability of the crystal defect distribution, oxygen concentration distribution, resistivity distribution, etc. in the pulling axial direction of the silicon single crystal 3.

In the production of silicon single crystal 3, first, polycrystalline silicon raw material is placed in quartz crucible 11, and the raw material in quartz crucible 11 is heated and melted by heater 15 to produce silicon melt 2. Next, a seed crystal attached to the lower end of wire 17 is lowered to contact silicon melt 2. The seed crystal is then gradually pulled up while maintaining contact with silicon melt 2 to grow silicon single crystal 3. In the crystal pulling process, the diameter is gradually increased to form a shoulder portion, and then the diameter is kept constant to form a straight body portion. After the straight body portion of the desired length is formed, the diameter is gradually reduced to separate it from silicon melt 2. This completes a silicon single crystal ingot.

Figures 2 and 3 are schematic cross-sectional views showing the configuration of a heat shielding member according to a first embodiment of the present invention, with Figure 2 being a completed view and Figure 3 being an exploded view.

As shown in Figs. 2 and 3, the heat shielding member 20 according to this embodiment includes a substantially cylindrical heat insulating member 30 and a wall member 40 that covers the exposed surface of the heat insulating member 30. A felt material made of carbon fiber can be used as the heat insulating member 30. Alternatively, alumina or the like can be used as the heat insulating member. The material of the wall member 40 can be thermally stable and high-purity graphite or graphite with a SiC coating on the surface. Alternatively, thermally stable Mo (molybdenum) or W (tungsten) can be used as the wall member.

The heat insulating member 30 is made of a first heat insulating section 31 having a substantially cylindrical shape. The outer peripheral surface 31a of the first heat insulating section 31 is a vertical surface and constitutes the outer peripheral surface 30a of the heat insulating member 30. The inner peripheral surface 31b of the first heat insulating section 31 constitutes a downwardly tapered surface. The lower end surface 31c of the first heat insulating section 31 is a horizontal surface, and furthermore, a chamfered tapered surface is provided at the corner portion on the outer peripheral side. The outer peripheral surface 31a of the first heat insulating section 31 may constitute a downwardly tapered surface.

The wall member 40 has an outer wall portion 41 that covers the outer peripheral area of the outer peripheral surface 30a and the lower end surface 30c of the insulating member 30, an inner wall portion 42 that covers the inner peripheral surface 30b of the insulating member 30, and a bottom wall portion 43 that covers the inner peripheral area of the lower end surface 30c of the insulating member 30.

The outer wall portion 41 is a substantially cylindrical member, and covers the outer peripheral surface 31a and the outer peripheral region of the lower end surface 31c of the first insulating portion 31. The inner peripheral surface of the outer wall portion 41 is in close contact with the outer peripheral surface 31a of the first insulating portion 31. The first insulating portion 31 is stored in the outer wall portion 41 by inserting the first insulating portion 31 from the upper opening of the outer wall portion 41 to the inside. The first insulating portion 21 can be easily removed from the outer wall portion 41 by lifting it upward. In this embodiment, the cylindrical shape of the outer wall portion 41 has a constant diameter from the upper end to the position of the lower tapered portion, but may be a substantially inverted truncated cone shape in which the diameter gradually decreases.

The inner wall portion 42 is a substantially cylindrical member, and is installed inside the substantially cylindrical outer wall portion 41, covering the inner circumferential surface 31b of the first heat insulating portion 31. The first inner wall portion 42X having a shape that fits the inner circumferential surface 31b of the first heat insulating portion 31 is used as the inner wall portion 42, and the outer circumferential surface of the first inner wall portion 42X is in close contact with the inner circumferential surface 31b of the first heat insulating portion 31. The upper end portion of the first inner wall portion 42X abuts against the inner circumferential surface near the upper end portion of the outer wall portion 41, and covers the upper end surface 31d of the first heat insulating portion 31 that constitutes the upper end surface 30d of the heat insulating member 30. The lower end portion of the first inner wall portion 42X abuts against the upper surface near the inner circumferential end portion of the bottom wall portion 43. The first inner wall portion 42X has a flat shape that is inclined diagonally from the upper end portion to the lower end portion, but may have a step along the way.

Normally, the opening diameter of the heat shielding member 20 becomes smaller as it goes downward, and is smallest near the bottom end. The opening shape of the heat shielding member that has a large effect on pulling the single crystal is the opening diameter near the bottom end close to the solid-liquid interface, so the opening diameter of the inner wall portion 42 refers to the minimum value of the opening diameter near the bottom end. The same applies to the opening diameters of the heat shielding member 20 and other parts.

The bottom wall portion 43 is a substantially annular member, and is installed inside the substantially cylindrical outer wall portion 41 to cover the inner peripheral region of the lower end surface 31c of the first heat insulating portion 31. A large-diameter first bottom wall portion 43X that matches the size of the first heat insulating portion 32X is used as the bottom wall portion 43. It is preferable that the upper surface of the first bottom wall portion 43X is in close contact with the lower end surface 31c of the first heat insulating portion 31. The first bottom wall portion 43X is placed on the upper surface of the inner peripheral end (lower end) of the outer wall portion 41, and forms a circular bottom plate. A step is provided in the first bottom wall portion 43X, and this step fits into the inner peripheral end of the outer wall portion 41, thereby positioning and fixing the first bottom wall portion 43X to the center of the heat shielding member 20.

In the installed state of the first inner wall portion 42X, it is preferable that the lower end portion of the first inner wall portion 42X is in close contact with the inner peripheral end portion of the first bottom wall portion 43X. In order to ensure such a close contact state, it is preferable that the lower end surface of the first inner wall portion 42X is formed with a tapered surface 42t that is inclined obliquely upward toward the center in the radial direction in the installed state. Similarly, it is preferable that the upper surface of the inner peripheral end portion of the first bottom wall portion 43X is also formed with a tapered surface 43t with approximately the same inclination angle as the lower end surface of the first inner wall portion 42X. In this way, the tapered surface 42t of the lower end portion of the first inner wall portion 42X is engaged in surface contact with the tapered surface 43t of the inner peripheral end portion of the first bottom wall portion 43X, thereby sealing the storage space of the heat insulating member 30.

A similar tapered surface is preferably provided at the connection position between the outer wall portion 41 and the first bottom wall portion 43X. That is, a tapered surface 41u is formed on the upper surface of the inner peripheral end of the outer wall portion 41, and a tapered surface 43u with approximately the same inclination angle as the tapered surface 41u is formed on the bottom surface of the outer peripheral end of the first bottom wall portion 43X. This makes it possible to firmly connect the two and seal the storage space of the insulating member 30.

Since the insulating member 30 gradually deteriorates and turns into powder, if the insulating member 30 is not sealed properly by the wall member 40, the powder of the insulating member 30 will leak out and adversely affect the yield of the single crystal. However, if the joints between the multiple parts that make up the wall member 40 are tightly sealed, the leakage of the powder can be prevented.

As shown in FIG. 3, the heat shielding member 20 according to this embodiment is completed by installing each part inside the outer wall portion 41 in a predetermined order. Each part simply needs to be housed inside the outer wall portion 41, and no special fixing means are required. This makes it extremely easy to remove and replace each part.

As described above, the heat insulating member 30 according to this embodiment is composed only of the first heat insulating section 31, and the wall member 40 is composed of the first inner wall section 42X and the first bottom wall section 43X corresponding to the first heat insulating section 31, thereby forming a heat shielding member 20 having a relatively large opening size. If it is desired to form a heat shielding member 20 having a relatively small opening size, it is necessary to add or change parts.

Figures 4 and 5 are schematic cross-sectional views showing the configuration of a heat shielding member according to a second embodiment of the present invention, with Figure 4 being a completed view and Figure 5 being an exploded view.

As shown in Figures 4 and 5, the heat shielding member 20 according to this embodiment is a modified example of the first embodiment shown in Figures 2 and 3, and the heat insulating member 30 is composed of a combination of a first heat insulating section 31 and a second heat insulating section 32. The first heat insulating section 31 is the same as that used in the first embodiment. The second heat insulating section 32 is a substantially cylindrical member provided on the inner periphery side of the first heat insulating section 31, and is configured to be detachable from the first heat insulating section 31. In other words, the heat insulating member 30 according to this embodiment is obtained by adding the second heat insulating section 32 to the first heat insulating section 31, which is a common part with the first embodiment.

The outer peripheral surface 32a of the second insulating section 32 is a tapered surface that fits the inner peripheral surface 31b of the first insulating section 31 and is in close contact with the inner peripheral surface 31b. The inner peripheral surface 32b of the second insulating section 32 is a tapered surface with an inclination angle close to the outer peripheral surface 32a and constitutes the inner peripheral surface 30b of the insulating member 30. When the second insulating section 32 is inserted inward from the top opening of the first insulating section 31, the outer peripheral surface 32a of the second insulating section 32 is in close contact with the inner peripheral surface 31b of the first insulating section 31, and the two become integrated. The second insulating section 32 can be easily removed from the first insulating section 31 by lifting it upward.

In this embodiment, the second insulating section 32 is a relatively large member that extends over a wide area from the upper end to the lower end of the first insulating section 31, but it may also be a relatively small member that is provided only at the lower end of the first insulating section 31.

The wall member 40 includes an outer wall portion 41 that covers the outer peripheral area of the outer peripheral surface 30a and the lower end surface 30c of the insulating member 30, an inner wall portion 42 that covers the inner peripheral surface 30b of the insulating member 30, and a bottom wall portion 43 that covers the inner peripheral area of the lower end surface 30c of the insulating member 30. Here, the outer wall portion 41 is the same as that used in the first embodiment, and, like the first insulating portion 31, is a component common to the first and second embodiments.

The inner wall portion 42 is a second inner wall portion 42Y having a shape that fits the inner peripheral surface 32b of the second insulating portion 32, and the bottom wall portion 43 is a second bottom wall portion 43Y for a small diameter that is adapted to the use of the second insulating portion 32. Therefore, the shape of the second inner wall portion 42Y is slightly different from that of the first inner wall portion 42X, and the shape of the second bottom wall portion 43Y is slightly different from that of the first bottom wall portion 43X.

The outer peripheral surface of the second inner wall portion 42Y is in close contact with the inner peripheral surface 32b of the second insulating portion 32, and the upper surface of the second bottom wall portion 43Y is in close contact with at least the lower end surface 32c of the second insulating portion 32. The upper end portion of the second inner wall portion 42Y abuts against the inner peripheral surface near the upper end portion of the outer wall portion 41, and covers the upper end surface 31d of the first insulating portion 31 and the upper end surface 32d of the second insulating portion 32, which constitute the upper end surface 30d of the insulating member 30. The lower end portion of the second inner wall portion 42Y abuts against the upper surface near the inner peripheral end portion of the bottom wall portion 43. The inner wall portion 42 has a flat shape that slopes diagonally from the upper end portion to the lower end portion, but may have a step along the way.

As explained using Figures 2 and 3, when the first insulating section 31 is used alone, the opening size of the heat shielding member 20 can be made large, and it can be preferably used for pulling silicon single crystals with a large crystal diameter. On the other hand, when the first insulating section 31 and the second insulating section 32 are combined as in this embodiment, the opening size (diameter of the opening 20a) of the heat shielding member 20 can be made small, and it can be preferably used for pulling silicon single crystals with a small crystal diameter.

In this way, two types of inner wall portions 42 of the heat shielding member 20 are prepared: a first inner wall portion 42X that matches the shape of the inner peripheral surface 31b of the first insulating portion 31, and a second inner wall portion 42Y that matches the shape of the inner peripheral surface 32b of the second insulating portion 32, and one of them is selectively used according to the usage state of the second insulating portion 32. Similarly, two types of bottom wall portions 43 of the heat shielding member 20 are prepared: a first bottom wall portion 43X that matches the bottom shape when the first insulating portion 31 is used alone, and a second bottom wall portion 43Y that matches the bottom shape when the first insulating portion 31 and the second insulating portion 32 are used in combination, and one of them is selectively used according to the usage state of the second insulating portion 32.

The difference between the opening diameter _R1 when the opening size of the heat shielding member 20 is increased and the opening diameter _R2 when the opening size is decreased is preferably 50 mm (about 2 inches) or more. This is because, when the diameter difference between two types of silicon single crystals having different crystal diameters is less than 50 mm, it is possible to pull silicon single crystals of substantially the same quality by finely adjusting other crystal pulling conditions without changing the opening size of the heat shielding member 20. In this way, the opening size of the heat shielding member 20 must be changed when the diameter difference between the two types of silicon single crystals is relatively large, making it difficult to make the quality of the two types of silicon single crystals substantially the same, and when the diameter difference between the straight body parts of the two types of silicon single crystals is 50 mm or more.

The upper limit of the difference in the opening diameter is not particularly limited. Therefore, for example, in order to pull up a silicon single crystal with a diameter of approximately 200 mm and a silicon single crystal with a diameter of approximately 400 mm in the same CZ pulling furnace, it is possible for the difference between the large opening diameter and the small opening diameter of the heat shielding member 20 to be 200 mm or more.

The first insulating section 31 and the second insulating section 32 constituting the insulating member 30, and the outer wall section 41, the first inner wall section 42X, the second inner wall section 42Y, the first bottom wall section 43X, and the second bottom wall section 43Y constituting the wall member 40 constitute a parts set of a heat shielding member corresponding to two types of opening sizes. The first insulating section 31 and the outer wall section 41 are basic parts common to large and small diameters, and the second insulating section 32 is an additional part used only for small diameters. The first inner wall section 42X and the first bottom wall section 43X are optional parts used only for large diameters, and the second inner wall section 42Y and the second bottom wall section 43Y are optional parts used only for small diameters.

As described above, when pulling up a large-diameter (e.g., 395 mm) silicon single crystal, the first insulating section 31 is used alone as the insulating member 30, the first inner wall section 42X that fits the first insulating section 31 is used as the inner wall section 42, and the first bottom wall section 43X that covers the lower end surface of the first insulating section 31 is used as the bottom wall section 43.

On the other hand, when pulling up a small-diameter (e.g., 320 mm) silicon single crystal, both the first insulating section 31 and the second insulating section 32 are used as the insulating member 30, and the second inner wall section 42Y that fits into the second insulating section 32 is used as the inner wall section 42, and the second bottom wall section 43Y that covers the lower end surfaces of the first insulating section 31 and the second insulating section 32 is used as the bottom wall section 43.

As described above, the heat shielding member 20 according to this embodiment is configured so that some of its components are shared while other components can be replaced, added, or omitted to change the opening size. This allows two types of silicon single crystals with different crystal diameters to be pulled using the same CZ pulling furnace, thereby reducing the variation in quality between the two types of silicon single crystals with different crystal diameters.

In addition, the method for producing single crystals according to this embodiment uses a heat shielding member 20 (first heat shielding member) constructed using only the first insulating section 31X when pulling up a silicon single crystal with a large crystal diameter, and uses a double-structure heat shielding member 20 (second heat shielding member) constructed by combining the first insulating section 31 and the second insulating section 32 when pulling up a silicon single crystal with a small crystal diameter. Therefore, two types of silicon single crystals with different crystal diameters can be pulled up using the same CZ pulling furnace, and the quality variation between the two types of silicon single crystals with different crystal diameters can be reduced.

Figure 6 is a schematic cross-sectional view showing the configuration of a heat shielding member according to a third embodiment of the present invention.

As shown in FIG. 6, the heat shielding member 20 according to this embodiment is a further modified example of the heat shielding member according to the second embodiment shown in FIG. 4 and FIG. 5, and the heat insulating member 30 is a combination of a first heat insulating section 31, a second heat insulating section 32, and a third heat insulating section 33. The first heat insulating section 31 and the second heat insulating section 32 are the same as those used in the second embodiment. The third heat insulating section 33 is a substantially cylindrical member provided on the inner periphery side of the second heat insulating section 32, and is configured to be detachable from the second heat insulating section 32. In other words, the heat insulating member 30 according to this embodiment is obtained by adding the second heat insulating section 32 and the third heat insulating section 33 to the first heat insulating section 31, which is a common part with the first embodiment.

It is preferable that the difference between the opening diameter _R2 (see FIG. 4) when the third insulating part 33 is not used and the opening diameter _R3 when the opening size is reduced by using the third insulating part 33 be 50 mm (about 2 inches) or more. This is because, when the diameter difference between two types of silicon single crystals having different crystal diameters is less than 50 mm, it is possible to pull silicon single crystals of substantially the same quality by finely adjusting other crystal pulling conditions without changing the opening size of the heat shielding member 20.

The outer peripheral surface 33a of the third insulating section 33 is a tapered surface that fits the inner peripheral surface 32b of the second insulating section 32 and is in close contact with the inner peripheral surface 32b. The inner peripheral surface 33b of the third insulating section 33 is a tapered surface with an inclination angle close to the outer peripheral surface 33a and constitutes the inner peripheral surface 30b of the insulating member 30. When the third insulating section 33 is inserted inward from the top opening of the second insulating section 32, the outer peripheral surface 33a of the third insulating section 33 is in close contact with the inner peripheral surface 32b of the second insulating section 32, and the two become integrated. The third insulating section 33 can be easily removed from the second insulating section 32 by lifting it upward.

In this embodiment, the third insulating section 33 is a relatively large member that extends over a wide area from the upper end to the lower end of the first insulating section 31 and the second insulating section 32, but it may also be a relatively small member that is provided only on the lower ends of the first insulating section 31 and the second insulating section 32.

The wall member 40 includes an outer wall portion 41 that covers the outer peripheral area of the outer peripheral surface 30a and the lower end surface 30c of the insulating member 30, an inner wall portion 42 that covers the inner peripheral surface 30b of the insulating member 30, and a bottom wall portion 43 that covers the inner peripheral area of the lower end surface 30c of the insulating member 30. Here, the outer wall portion 41 is the same as that used in the first embodiment, and, like the first insulating portion 31, is a component common to the first to third embodiments.

The inner wall portion 42 is a third inner wall portion 42Z having a shape that fits the inner peripheral surface 33b of the third insulating portion 33, and the bottom wall portion 43 is a third bottom wall portion 43Z having an even smaller opening size that is adapted to the use of the third insulating portion 33. Therefore, the shape of the third inner wall portion 42Z is slightly different from that of the second inner wall portion 42Y, and the shape of the third bottom wall portion 43Z is slightly different from that of the second bottom wall portion 43Y.

The first insulating section 31, the second insulating section 32, and the third insulating section 33 constituting the insulating member 30, and the outer wall section 41, the first inner wall section 42X, the second inner wall section 42Y, the third inner wall section 42Z, the first bottom wall section 43X, the second bottom wall section 43Y, and the third bottom wall section 43Z constituting the wall member 40 constitute a parts set of a heat shielding member corresponding to three types of opening sizes. The first insulating section 31 and the outer wall section 41 are basic parts common to the large diameter, medium diameter, and small diameter, the second insulating section 32 and are additional parts common to the medium diameter and small diameter, and the third insulating section 33 is an additional part used only for the small diameter. The first inner wall portion 42X and the first bottom wall portion 43X are optional parts used only for large diameters, the second inner wall portion 42Y and the second bottom wall portion 43Y are optional parts used only for medium diameters, and the third inner wall portion 42Z and the third bottom wall portion 43Z are optional parts used only for small diameters. In this way, according to this embodiment, the options for the opening size of the heat shielding member 20 can be further expanded.

Figures 7 and 8 are schematic cross-sectional views showing the configuration of a heat shielding member according to a fourth embodiment of the present invention, with Figure 7 being a completed view and Figure 8 being an exploded view.

As shown in Figures 7 and 8, the heat shielding member 20 according to this embodiment is characterized in that the bottom wall portion 43 is omitted as a component of the large-diameter heat shielding member. That is, the wall member 40 is composed of an outer wall portion 41 that covers the entire outer peripheral surface 30a and lower end surface 30c of the heat insulating member 30, and a first inner wall portion 42X that covers the inner peripheral surface 30b of the heat insulating member 30.

Figures 9 and 10 are schematic cross-sectional views showing the configuration of a heat shielding member according to a fifth embodiment of the present invention, with Figure 9 being a completed view and Figure 10 being an exploded view.

As shown in Figures 9 and 10, the heat shielding member 20 of this embodiment is a modified example of the heat shielding member of the fourth embodiment shown in Figures 7 and 8, in that the heat insulating member 30 is composed of a combination of a first heat insulating section 31 and a second heat insulating section 32, and the wall member 40 further includes a bottom wall section 43 in addition to an outer wall section 41 and a second inner wall section 42Y.

In this way, the bottom wall portion can be omitted when the opening size of the heat shielding member 20 is to be increased, and a bottom wall portion can be added when the opening size of the heat shielding member 20 is to be decreased. In this case, the first insulating portion 31 and the outer wall portion 41 can be used as common parts, and by adding the second insulating portion 32 and the bottom wall portion 43 and replacing the inner wall portion 42, it is also possible to accommodate small diameters.

Figures 11 and 12 are schematic cross-sectional views showing the configuration of a heat shielding member according to a sixth embodiment of the present invention, with Figure 11 being a completed view and Figure 12 being an exploded view.

As shown in Figures 11 and 12, the heat shielding member 20 according to this embodiment is characterized in that a key-shaped engagement portion is provided at the connection position between the outer wall portion 41 and the inner wall portion 42 to strengthen the connection between them. Specifically, a protrusion 41v that protrudes upward is formed on the lower end (inner peripheral end) of the outer wall portion 41, and the lower end of the inner wall portion 42 is engaged and fixed to the protrusion 41v provided on the lower end (inner peripheral end) of the outer wall portion 41. When the inner wall portion 42 is installed inside the outer wall portion 41, the lower end of the inner wall portion 42 engages with the protrusion 41v of the outer wall portion 41, and the two are firmly connected.

The connection points of the parts that make up the wall member 40 preferably have hook-shaped ends that engage with each other to prevent fine powder caused by deterioration of the internal insulation member 30 from falling out, thereby maintaining an airtight state inside the wall member 40. Since the insulation member 30 gradually deteriorates and turns into powder, if the insulation member 30 is not sealed properly by the wall member 40, the fine powder of the insulation member 30 will leak out and have a negative effect on the yield of the single crystal. However, if the joints between the multiple parts that make up the wall member 40 are tightly sealed, the leakage of the fine powder can be prevented.

Figures 13 and 14 are schematic cross-sectional views showing the configuration of a heat shielding member according to the seventh embodiment of the present invention, with Figure 13 being a completed view and Figure 14 being an exploded view.

As shown in Figs. 13 and 14, the heat shielding member 20 according to this embodiment is a modified example of the heat shielding member according to the sixth embodiment shown in Figs. 11 and 12, and is characterized in that the heat insulating member 30 is composed of a combination of the first heat insulating portion 31 and the second heat insulating portion 32, and the wall member 40 further includes a bottom wall portion 43 in addition to the outer wall portion 41 and the second inner wall portion 42Y. In addition, in order to strengthen the connection between the outer wall portion 41 and the bottom wall portion 43, a key-shaped engagement portion is provided at the connection position between the two. Specifically, a protrusion 41v that protrudes upward is formed at the lower end (inner peripheral end) of the outer wall portion 41, and a hook portion 43v that engages with the protrusion 41v of the outer wall portion 41 is formed at the outer peripheral end of the bottom wall portion 43. When the bottom wall portion 43 is installed inside the outer wall portion 41, the hook portion 43v engages with the protrusion 41v, and the two are firmly connected.

The connection points of the parts that make up the wall member 40 preferably have hook-shaped ends that engage with each other to prevent fine powder caused by deterioration of the internal insulation member 30 from falling out, thereby maintaining an airtight state inside the wall member 40. Since the insulation member 30 gradually deteriorates and turns into powder, if the insulation member 30 is not sealed properly by the wall member 40, the fine powder of the insulation member 30 will leak out and have a negative effect on the yield of the single crystal. However, if the joints between the multiple parts that make up the wall member 40 are tightly sealed, the leakage of the fine powder can be prevented.

The heat shielding member 20 according to this embodiment can achieve the same effect as the heat shielding members according to the first and second embodiments. That is, the opening size can be changed in three stages by removing or replacing some of the components. Therefore, the same CZ pulling furnace can be used to pull three types of silicon single crystals with different crystal diameters, and the quality variation of the three types of silicon single crystals with different crystal diameters can be reduced.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention, and it goes without saying that these are also included within the scope of the present invention.

For example, in the above embodiment, the first insulation section 31, the second insulation section 32, and the third insulation section 33 are each configured as a single component, but may be made up of a combination of multiple components divided in the height direction.

The inner peripheral surface of the inner wall portion 42 that constitutes the inner peripheral surface of the heat shielding member 20 is a flat surface that slopes diagonally from the upper end to the lower end, but a step may be provided along the way. For example, by providing a step that functions as a handle on part or the entire circumference of the inner peripheral surface of the inner wall portion 42, the workability of attaching and detaching the inner wall portion 42 can be improved. Such a step may be provided on the first to third insulating portions 31 to 33 that constitute the insulating member 30, and can be provided on all parts housed inside the outer wall portion 41 of the wall member 40.

Furthermore, in the above embodiment, a heat shielding member used in the production of silicon single crystals by the CZ method is given as an example, but the present invention is not limited to silicon single crystals and can be applied to the production of various single crystals.

1 Single crystal manufacturing apparatus 2 Silicon melt 3 Silicon single crystal 10 Chamber 10a Main chamber 10b Pull chamber 10c Gas inlet 10d Gas outlet 11 Quartz crucible 12 Graphite crucible 13 Rotating shaft 14 Shaft drive mechanism 15 Heater 16 Insulating material 17 Wire 18 Wire winding mechanism 20 Heat shielding member 20a Opening 30 Insulating member 30a Outer peripheral surface 30b of insulating member Inner peripheral surface 30c of insulating member Lower end surface 30d of insulating member Upper end surface 31 First insulating part 31a Outer peripheral surface 31b Inner peripheral surface 31c Lower end surface 31d Upper end surface 32 Second insulating part 32a Outer peripheral surface 32b Inner peripheral surface 32c Lower end surface 32d Upper end surface 33 Third insulating part 33a Outer peripheral surface 33b Inner peripheral surface 33c Lower end surface 33d Upper end surface 40 Wall member 41 Outer wall portion 41u Tapered surface 41v Protrusion portion 42 Inner wall portion 42X First inner wall portion 42Y Second inner wall portion 42Z Third inner wall portion 42t Tapered surface 43 Bottom wall portion 43X First bottom wall portion 43Y Second bottom wall portion 43Z Second bottom wall portion 43t Tapered surface 43u Tapered surface 43v Hook portion

Claims (12)

A heat shielding member used in pulling a single crystal by a CZ method, surrounding the single crystal pulled from a melt in a crucible, comprising:
A substantially cylindrical heat insulating member;
a wall member covering an exposed surface of the heat insulating member;
The wall member is
An outer wall portion covering at least an outer peripheral surface of the heat insulating member;
An inner wall portion covering an inner circumferential surface of the heat insulating member;
A bottom wall portion covering a lower end surface of the heat insulating member,
The heat insulating member is
A substantially cylindrical first insulation portion;
A substantially cylindrical second insulation part is provided inside the first insulation part,
The second heat insulating section is configured to be detachable from the first heat insulating section ,
The inner wall portion includes a first inner wall portion that covers an inner circumferential surface of the first heat insulating portion when the first heat insulating portion is used alone, and a second inner wall portion that covers an inner circumferential surface of the second heat insulating portion when the first heat insulating portion and the second heat insulating portion are used in combination,
A heat-shielding member characterized in that the difference between the opening diameter of the heat-shielding member when the first insulation section is used alone and the opening diameter of the heat-shielding member when the first insulation section and the second insulation section are used in combination is 50 mm or more . The outer peripheral surface of the first heat insulating portion is covered by the outer wall portion,
The inner circumferential surface of the second heat insulating portion is covered by the inner wall portion,
The heat shielding member according to claim 1 , wherein when the first insulation section and the second insulation section are used in combination, an outer peripheral surface of the second insulation section is in close contact with an inner peripheral surface of the first insulation section. The bottom wall portion is configured to be detachable from the outer wall portion,
The heat shielding member according to claim 1 or 2, wherein the inner wall portion is configured to be detachable from the bottom wall portion and the outer wall portion. The heat shielding member according to any one of claims 1 to 3, wherein the upper surface of the inner peripheral end of the bottom wall portion connected to the lower end of the inner wall portion is provided with a tapered surface that is inclined radially outward, and the lower end of the inner wall portion abuts against the tapered surface. The heat shielding member according to any one of claims 1 to 4, wherein the lower end of the outer wall portion connected to the outer peripheral end of the bottom wall portion is provided with a tapered surface that is inclined radially outward, and the outer peripheral end of the bottom wall portion abuts against the tapered surface. The heat shielding member according to any one of claims 1 to 5, wherein a protrusion is provided at the lower end of the outer wall portion, and a hook portion that engages with the protrusion is provided at the outer peripheral end of the bottom wall portion. A parts set for a heat shielding member used in pulling a single crystal by a CZ method, surrounding the single crystal pulled from a melt in a crucible, comprising:
A substantially cylindrical first insulation portion;
A substantially cylindrical second insulation part that is detachably provided inside the first insulation part;
An outer wall portion covering an outer peripheral surface and a lower end surface of the first heat insulating portion;
A first inner wall portion covering an inner circumferential surface of the first heat insulating portion;
A second inner wall portion covering an inner circumferential surface of the second heat insulating portion ;
A bottom wall portion covering a lower end surface of the second heat insulating portion,
The first heat shielding member is composed of the first heat insulating portion, the outer wall portion, and the first inner wall portion,
A heat-shielding member parts set, characterized in that a second heat-shielding member having an opening diameter smaller than that of the first heat-shielding member is composed of the first insulation portion, the second insulation portion , the outer wall portion, the second inner wall portion and the bottom wall portion . 8. The parts set for a heat shielding member according to claim 7, wherein a difference between an opening diameter of the first inner wall portion and an opening diameter of the second inner wall portion is 50 mm or more. A parts set for a heat shielding member used in pulling a single crystal by a CZ method, surrounding the single crystal pulled from a melt in a crucible, comprising:
A substantially cylindrical first insulation portion;
A substantially cylindrical second insulation part that is detachably provided inside the first insulation part;
An outer wall portion covering an outer peripheral surface of the first heat insulating portion;
A first inner wall portion covering an inner circumferential surface of the first heat insulating portion;
A second inner wall portion covering an inner circumferential surface of the second heat insulating portion;
A first bottom wall portion covering a lower end surface of the first heat insulating portion;
A second bottom wall portion covering the lower end surfaces of the first and second heat insulating portions,
the first heat shielding member is composed of the first heat insulating portion, the outer wall portion, the first inner wall portion, and the first bottom wall portion,
A heat-shielding member parts set, characterized in that a second heat-shielding member having an opening diameter smaller than that of the first heat-shielding member is composed of the first insulation portion, the second insulation portion, the outer wall portion, the second inner wall portion and the second bottom wall portion. 10. The parts set for a heat shielding member according to claim 9 , wherein a difference between an opening diameter of the first inner wall portion and an opening diameter of the second inner wall portion is 50 mm or more. 7. A single crystal manufacturing apparatus comprising: a chamber; a crucible for supporting the melt within the chamber; a heater for heating the melt; a crucible drive mechanism for rotating and raising and lowering the crucible; a crystal pulling mechanism for pulling the single crystal from the melt; and a heat shielding member according to any one of claims 1 to 6 , which is installed above the melt, surrounds the single crystal pulled from the melt, and shields it from radiant heat from the heater. A method for producing a single crystal by the CZ method, in which a single crystal is pulled up from a melt in a crucible, characterized in that the single crystal pulled up from the melt is surrounded by a heat shielding member according to any one of claims 1 to 6 .

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