JP2002255682A - Apparatus for producing semiconductor single crystal and method of producing semiconductor single crystal using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing a semiconductor single crystal, having uniform quality over whole crystal and having small dispersion by forming a uniform and stable cooling atmosphere. SOLUTION: In the apparatus for producing the semiconductor single crystal, a forced cooling tube 11 for circulating a cooling fluid W is arranged above a raw melt so as to surround the semiconductor single crystal 3 being pulled from the raw melt stared in a crucible, and the single crystal is grown by a Czochralski method while removing radiant heat from the semiconductor single crystal 3 by the forced cooling tube 11. When the cooling fluid W is circulated through the forced cooling tube 11, the cooling fluid W is introduced to the lower part, close to the raw melt 4, of the forced cooling tube 11, and then circulated through the tube from the lower part of the tube toward the upper end part of the tube while being urged to flow in the peripheral direction by a peripheral direction circulation correction part 33 provided inside the forced cooling tube 11 in circulating the cooling fluid W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal manufacturing apparatus for growing a semiconductor single crystal by the Czochralski method (hereinafter, referred to as CZ method) and a method for manufacturing a semiconductor single crystal using the same.

[0002]

2. Description of the Related Art Conventionally, a silicon single crystal grown by the CZ method has been processed into a silicon semiconductor wafer and used in many cases as a substrate of a semiconductor device. In the production of a silicon single crystal by the CZ method, see Japanese Patent Application Laid-Open No. 3-97688.
As disclosed in Japanese Unexamined Patent Application Publication No. 57-40119 and Japanese Patent Application Laid-Open No. 57-40119, in order to remove the radiant heat of the silicon single crystal pulled up from the raw material melt contained in the crucible and to increase the growth rate, A cylindrical or conical member is arranged so as to surround the single crystal grown directly above the raw material melt,
A method of pulling a silicon single crystal is often used.

[0003] In particular, a cooling cylinder having a cylindrical shape arranged so as to surround a grown crystal has a large rectifying effect on the inert gas downstream from above the melt surface, and efficiently removes evaporates from the raw material melt. Since the crystal is discharged outside the furnace and dislocations of the grown crystal due to evaporates or the like can be prevented, the apparatus configuration is widely used in a silicon single crystal manufacturing apparatus. These cylindrical cooling cylinders and conical heat shield screens are arranged directly above the high-temperature raw material melt at 1400 ° C. or higher, efficiently absorbing radiant heat from the grown crystal, and Since it is necessary to block the radiant heat from the heater and the raw material melt to heat the liquid, most of them are generally made of graphite materials and high melting metals such as stainless steel and molybdenum with high thermal conductivity. .

However, for example, in a cooling cylinder made of a graphite material as disclosed in JP-A-3-97688,
By arranging the cooling cylinder so as to surround the pulled single crystal, the cooling effect of the grown crystal is increased, but because it does not actively absorb the radiant heat from the single crystal,
There was naturally a limit to increasing the crystal growth rate. In particular, when growing a large silicon single crystal having a diameter of more than 200 mm, the heat capacity of the grown crystal itself becomes large, so a more efficient cooling method is required.

Therefore, recently, as one method for solving this problem, Japanese Patent Application Laid-Open Nos. 61-68389 and 4-317149, or Japanese Patent Application No. 12-21 is disclosed.
As shown in No. 241, a cooling fluid such as water is circulated through the above-described cooling cylinder or heat shielding screen to actively absorb radiant heat generated from the grown crystal and transfer heat to the outside of the growing furnace. Accordingly, an apparatus for producing a silicon single crystal having a forced cooling cylinder in which the cooling efficiency of the single crystal is increased as much as possible has been developed.

[0006]

In general, in a forced cooling cylinder provided with a cooling mechanism for flowing the cooling fluid and transferring the radiant heat from the grown crystal to the outside of the furnace, the path for flowing the cooling fluid is generally a forced cooling cylinder. Make a gap with the wall of the double structure,
A well-known jacket type in which a cooling fluid flows through the gap, and a method of cooling a forced cooling cylinder by welding a seamless pipe or the like to the wall of the forced cooling cylinder and flowing the cooling fluid through the pipe are well known.

However, in the case of the jacket type having the cooling cylinder wall having a double structure, when the cooling fluid is allowed to flow through the forced cooling cylinder, a short-cut of the cooling fluid easily occurs in the cooling cylinder, and the high temperature of the forced cooling cylinder is reduced. There is a problem in that the cooling fluid stays at a certain part, and a part where the temperature becomes high is easily formed. This deteriorates the cooling efficiency of the single crystal, and
It also leads to damage due to overheating of the forced cooling cylinder.

On the other hand, in the case of a pipe-type cooling structure,
There is also a problem that temperature unevenness tends to occur between a portion where the cooling pipe of the forced cooling cylinder is welded and a portion where the cooling pipe is not welded, and it is difficult to obtain a uniform cooling effect over the entire forced cooling cylinder.
In addition, since heat conduction from the cooling pipe to the joint is involved, cooling efficiency as high as that of the jacket method cannot be expected, and there is a problem that the cooling effect tends to be insufficient or uneven.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor single crystal to be grown that can be cooled with high efficiency without unevenness, to increase the productivity of the semiconductor single crystal, and to form a uniform and stable cooling atmosphere. An object of the present invention is to provide an apparatus capable of manufacturing a semiconductor single crystal having stable quality and a small variation over the whole, and a method of manufacturing a semiconductor single crystal using the same.

[0010]

In order to solve the above-mentioned problems, an apparatus of the present invention surrounds a semiconductor single crystal pulled from a raw material melt contained in a crucible above a raw material melt. In a semiconductor single crystal manufacturing apparatus that forms a single crystal by the Czochralski method while removing a radiant heat from a semiconductor single crystal pulled up by the forced cooling cylinder and arranging a forced cooling cylinder for flowing a cooling fluid in the form, When the cooling fluid flows through the cylinder, the cooling fluid is guided to the lower end portion of the forced cooling cylinder close to the raw material melt, and thereafter, by a circumferential flow correcting portion provided in the forced cooling cylinder, the circumferential direction of the cylinder is reduced. The cooling fluid is circulated from the lower end of the cylinder to the upper end while promoting the flow.

Further, a method of manufacturing a semiconductor single crystal according to the present invention comprises growing a single crystal by a Czochralski method while removing radiant heat from a semiconductor single crystal pulled up by a forced cooling cylinder using the above apparatus. Features.

When a cooling fluid such as cooling water is allowed to flow through the forced cooling cylinder, if a water stagnation portion is formed, the temperature of the portion where the cooling water is stagnated becomes high and the forced cooling cylinder is damaged, The temperature distribution becomes uneven and uniform crystal cooling becomes difficult,
It may be difficult to pull a single crystal at a stable quality and at a high speed. Therefore, in the present invention, the cooling fluid is circulated from the lower end to the upper end of the cylinder while promoting the flow in the cylinder circumferential direction by the circumferential flow correcting portion provided in the forced cooling cylinder. The cooling fluid can be uniformly circulated in both the circumferential direction and the axial direction of the cylinder, so that excessive heating and forced cooling of the forced cooling cylinder due to stagnation of the cooling fluid or the like can be effectively prevented or suppressed. Further, since the cooling fluid flows from the lower end side of the forced cooling cylinder, the lower part of the single crystal pulled up from the melt, which becomes higher in temperature, has a lower temperature (that is, heat absorption by cooling has not progressed). Since the cooling fluid is supplied, the cooling efficiency can be increased. Further, since the cooling fluid whose temperature has been raised to some extent by the cooling of the lower portion is supplied to the upper portion of the single crystal, it is possible to prevent the temperature gradient in the axial direction of the single crystal being pulled from becoming excessively steep. it can. The circumferential flow straightening section can further enhance the above-described effect by providing the cooling fluid as a guide that guides the cooling fluid from the lower end of the cylinder to the upper end thereof along a spiral path.

The forced cooling cylinder has a jacket structure in which an annular cooling fluid circulation gap is formed between the inner cylinder member and the outer cylinder member, and a cooling fluid inlet and a cooling fluid outlet communicating with the fluid circulation gap are provided. It can be configured as having. The forced cooling cylinder having the jacket structure allows the cooling fluid to come into contact with the entire surface of the inner cylinder member, so that the cooling efficiency is high, but a short circuit (shortcut) of the cooling fluid easily occurs in the cooling fluid circulation gap in the jacket. In particular, stagnation of the cooling fluid was particularly likely to occur. Therefore, in the case where the jacket structure is adopted in the present invention, the circumferential flow correcting portion is provided with a cooling fluid by a circumferential partition surface intersecting with the cylinder axis while allowing the cooling fluid to flow from the lower end to the upper end of the cylinder. It is configured to include a partition wall that partitions the circulation gap. As a result, the short-circuit of the cooling fluid, and furthermore, the stagnation of the cooling fluid is extremely unlikely to occur, and it is possible to prevent cooling unevenness and further improve the cooling efficiency. In this case, if the partition wall of the forced cooling cylinder having the jacket structure is provided in a form that partitions the cooling fluid flow gap into a spiral flow path, the effect can be further enhanced.

Next, it is desirable that the welded portion for joining the components of the forced cooling cylinder should not be provided on the surface of the raw material melt and on the surface facing the semiconductor single crystal pulled up from the raw material melt. When making a cooling cylinder, the components of the cooling cylinder are joined by welding, but this welded part tends to deteriorate when exposed to high-temperature heat radiation from a single crystal or a heater, etc. It can also lead to tube damage. However, by not providing the welded portion on the surface of the raw material melt and the surface facing the semiconductor single crystal pulled up from the raw material melt,
For example, the above-described problem can be effectively prevented by configuring the cooling cylinder having the jacket structure so that all the welded portions are formed on the side of the cooling fluid flow gap.

[0015] For example, conventionally, 140 mm is near the surface of the raw material melt.
It was difficult to arrange a cooling cylinder because it was exposed to a high temperature of 0 ° C or more, and it was considered that it was difficult to effectively cool the high temperature portion of the single crystal near the raw material melt surface. There were also restrictions on the position of the cylinder. However, by adopting this structure, the degree of freedom of the arrangement position is increased, and it is possible to easily improve the furnace layout for adjusting the temperature distribution and make the furnace compact. Specifically, by not providing a welded portion on a surface exposed to a high temperature, for example, a surface expected to be heated to 500 ° C. or more by thermal radiation, the durability and reliability of the forced cooling cylinder are improved. be able to. In addition, a forced cooling cylinder can be disposed (extended) at a higher temperature portion (position closer to the surface of the raw material melt) in the furnace. This enhances the effect of removing radiant heat from the single crystal. Also, since there is no welded portion on the inner surface of the forced cooling cylinder (the surface facing the crystal, there is an advantage that the unevenness of the inner surface is eliminated and the rectifying action of the inert gas is not hindered. Even if the semiconductor single crystal pulled up from the liquid is physically opposed to the semiconductor single crystal, a welded portion is naturally provided in a portion where there is no concern that the temperature rises above the temperature because it is sufficiently far away in the spirit of the present invention. It does not prevent you from being
In the present specification, such a portion is not considered to belong to the “surface of the raw material melt and the surface facing the semiconductor single crystal pulled from the raw material melt” in the claims.

Further, in order to measure the temperature of the cooling fluid flowing inside the forced cooling cylinder, one or more temperature sensors can be mounted inside the forced cooling cylinder. As a result, the internal temperature of the forced cooling cylinder can be monitored, and the occurrence of excessive temperature rise or the like can be detected at an early stage. In this case, it is desirable that the temperature sensor be installed at least at a position closest to the melt and at which the temperature of the cooling fluid flowing through the lower end of the forced cooling cylinder, which is particularly likely to cause excessive temperature rise, is measured.

Further, further, the temperature of the cooling fluid flowing through the forced cooling cylinder is measured by a temperature sensor, and the flow rate of the cooling fluid and / or (for example, It is also possible to grow the single crystal by adjusting the temperature (with a heater or the like). For example, when abnormal temperature rise of the cooling fluid is recognized by the measurement with the temperature sensor, the cooling capacity can be increased by increasing the flow rate of the cooling fluid, and the normal temperature can be maintained. Further, by adjusting the flow rate and / or temperature of the cooling fluid, a more stable cooling atmosphere can be formed, and a single crystal with more uniform quality can be grown.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
An example in which the invention is applied to the production of a silicon semiconductor single crystal by the CZ method will be described with reference to the drawings. The present invention is not limited to the growth of silicon single crystals only. For example, the apparatus of the present invention can be used for growing other single crystals such as compound semiconductors.

FIG. 1 is a schematic sectional view showing an example of a semiconductor single crystal manufacturing apparatus according to the present invention (hereinafter also referred to simply as a single crystal manufacturing apparatus). The single crystal manufacturing apparatus 20 includes a raw material, for example, a raw material melt 4 as in a general single crystal manufacturing apparatus.
Crucibles 5 and 6 containing polycrystalline silicon and heating
A heater 7 for melting is stored in the main chamber 1, and a pulling mechanism (not shown) for pulling a grown single crystal is provided above the pulling chamber 2 connected to the main chamber 1. ing.

A pulling wire 16 is wound out of a pulling mechanism mounted on the upper portion of the pulling chamber 2, and a seed holder 18 for mounting a seed crystal 17 is connected to the tip of the pulling wire 16. The seed crystal 17 attached earlier is immersed in the raw material melt 4 and the pulling wire 1
The silicon semiconductor single crystal (hereinafter, also simply referred to as a single crystal) 3 is formed below the seed crystal 17 by winding the 6 by a pulling mechanism.

The crucibles 5 and 6 have a structure in which a quartz crucible 5 for directly accommodating the raw material melt 4 is provided inside, and a graphite crucible 6 for supporting the quartz crucible 5 is provided outside. The crucibles 5 and 6 are instructed by a crucible rotation shaft 19 that can rotate and move up and down by a rotation drive mechanism (not shown) attached to a lower portion of the single crystal manufacturing apparatus 20. In order to keep the melt surface at a constant position so that the crystal quality does not change due to the change in the crystal, the crucible is raised by an amount corresponding to the decrease in the melt as the single crystal 3 is pulled while rotating in the opposite direction to the crystal. I have.

Further, a heater 7 is arranged so as to surround the crucibles 5 and 6, and outside the heater 7 is provided to prevent heat from the heater 7 from being directly radiated to the main chamber. A heat insulating member 8 is provided so as to surround the periphery. In addition, an inert gas such as an argon gas is introduced into the chambers 1 and 2 from a gas inlet 10 provided in the upper part of the pulling chamber 2 for the purpose of discharging impurities generated in the furnace outside the furnace. After passing through the upper portion of the single crystal 3 and the melt 4 being pulled, the gas flows through the inside of the chambers 1 and 2, and is discharged from the gas flow port 9. The main chamber 1 and the pulling chamber 2 are made of a metal having excellent heat resistance and heat conductivity such as stainless steel, and are water-cooled through a cooling pipe (not shown).

Next, in the single crystal production apparatus 20, the forced cooling cylinder 11 is provided so as to extend from at least the ceiling of the main chamber 1 toward the surface of the raw material solution so as to surround the single crystal 3 being pulled. ing. A cooling fluid W is introduced into the forced cooling cylinder 11 from an introduction pipe 12 forming a cooling fluid introduction passage forming part.
After circulating through the inside 1 to forcibly cool the forced cooling cylinder 11, the cooling fluid is discharged from the cooling fluid outlet 30 (FIG. 2) to the outside. In addition, as the cooling fluid W, a liquid or a gas conventionally used as a cooling fluid can be used, but it is preferable to use water from the viewpoint of handling properties, cost, etc., in addition to the cooling properties. . In addition, if the flow rate and temperature of the cooling fluid flowing through the forced cooling cylinder 11 are adjusted as necessary, the amount of heat removed from the forced cooling cylinder 11 can be changed. It is possible to create a cooling atmosphere. This will be described later.

The forced cooling cylinder 11 (an inner cylinder member 35 described later,
The material of the outer cylinder member 32 and the partition wall portion 33; see FIG. 2 is not particularly limited as long as it has heat resistance and is excellent in heat conductivity. SUS304)), nickel, copper, titanium, molybdenum, tungsten, or an alloy containing these metals. The metal or alloy may be covered with titanium, molybdenum, tungsten, or a platinum group metal. By using such a metal or alloy, the heat resistance of the forced cooling cylinder 11 becomes very excellent and the thermal conductivity also becomes very high, so that after absorbing the heat radiated from the single crystal rod, Since the cooling fluid such as water circulating in the forced cooling cylinder 11 is efficiently transmitted to lower the temperature around the crystal, the cooling rate of the single crystal can be improved.

Further, the single crystal production apparatus 20 has a cooling auxiliary member 13 which extends downward from the forced cooling cylinder 11 and has a cylindrical or reduced diameter. In the present embodiment, a cylindrical cooling auxiliary member 13 extending from the lower end of the forced cooling cylinder 11 to the vicinity of the raw material melt surface is provided. The cooling auxiliary member 13 surrounds the periphery of the high temperature single crystal 3 immediately after being pulled up, and has an effect of cooling the single crystal 3 by blocking radiant heat from the heater 7 or the melt 4 or the like. In addition, the forced cooling cylinder 11 is prevented from approaching directly above the melt surface, ensuring safety, and has a rectifying effect on the inert gas downstream from above the melt to near the crystal.

As the material of the cooling auxiliary member 13, a material having very excellent heat resistance and high thermal conductivity is preferable, and specifically, graphite, molybdenum or tungsten is preferable. Particularly, graphite is suitable because it efficiently shields radiant heat from a heater, a melt, and the like, and has relatively high thermal conductivity. Further, a material whose surface is coated with a protective film (for example, a pyrolytic carbon film or a silicon carbide film) may be used. In this way, adverse effects due to the attachment of the evaporant to the cooling auxiliary member are reduced, durability is improved, and impurity contamination of the cooling auxiliary member can be further suppressed.

By using the cooling auxiliary member 13 made of a material having excellent heat resistance and high thermal conductivity as described above, the heat absorbed by the cooling auxiliary member 13 is
1 and further discharged outside through a cooling fluid circulating in the forced cooling cylinder 11. And forced cooling cylinder 1
1 and the cooling auxiliary member 13 are provided in combination, so that the very high temperature single crystal 3
However, first, the radiant heat from the heater 7 or the like is blocked by the cooling auxiliary member 13 to be effectively cooled, and further raised to be opposed to the forced cooling cylinder 11 and at least to the ceiling of the main chamber 1 by the forced cooling cylinder 11. Since it is cooled, it is efficiently cooled over a wide range of the crystal. Therefore, the amount of heat flowing out of the crystal is reliably removed and the cooling effect is maximized, so that the crystal can be pulled at a very high growth rate.

Hereinafter, features of the present invention in the forced cooling cylinder 11 will be described in detail. 2A and 2B show details of the structure of the forced cooling cylinder 11, in which FIG. 2A is a longitudinal sectional view and FIG. 2B is a transverse sectional view. Its structural feature is that when flowing the cooling fluid W, the cooling fluid W is forced into a forced cooling cylinder 1 close to the raw material melt.
1, and then the cooling fluid W is circulated from the lower end of the cylinder toward the upper end of the forced cooling cylinder 11 while promoting the flow in the circumferential direction of the cylinder by the circumferential flow correcting section 33 provided in the forced cooling cylinder 11. It is in the point which was made.

In the present embodiment, the forced cooling cylinder 11 has an annular cooling fluid flow gap C between a cylindrical inner cylinder member 31 and a cylindrical outer cylinder member 32 arranged concentrically therewith.
L is formed, and has a water jacket structure provided with a cooling fluid inlet 36 and a cooling fluid outlet 30 communicating with the medium flow gap CL. The circumferential flow correcting portion 33 allows the flow of the cooling fluid W from the lower end to the upper end of the cylinder, while partitioning the cooling fluid flow gap CL by a circumferential partition surface intersecting with the cylinder axis. Hereinafter, the partition wall 33 will be described).

The forced cooling cylinder 1 having a jacket structure
As shown in FIG. 3, the first partition wall 33 is provided in a form that partitions the cooling fluid flow gap CL into a spiral flow path 34. As shown in FIG. 1, the forced cooling cylinder 11 is arranged on the ceiling of the main chamber 1, and more specifically, is arranged so as to straddle the lifting chamber 2 and the main chamber 1. The connection position of the supply path of the cooling fluid to the forced cooling cylinder 11 by the introduction pipe 12 is set at the upper end of the forced cooling cylinder 11 so that the introduction pipe 12 is not directly exposed to the radiant heat of the melt 4 or the pulled single crystal 3. In the present embodiment, the lower end portion of the lifting chamber 2 and the introduction tube 12 are set outside the lifting chamber 2.

As shown in FIG. 4A, the partition wall 33
The edge of one side in the width direction is joined and integrated with the outer peripheral surface of the inner cylindrical member 31 by a fillet-shaped welded portion Y.
This welded portion Y faces the cooling fluid flow gap CL side,
It is not exposed on the surface facing the pulled-up high-temperature single crystal 3 or the melt 4 (FIG. 1) (hereinafter referred to as a heat-exposed surface). On the other hand, the opposite edge is in close contact with the inner peripheral surface of the outer tubular member 32, but as shown in FIG.
If the leakage of the cooling fluid W does not become so large between the upper and lower flow paths 34 adjacent to each other with 3 interposed therebetween,
Some clearance may be provided between the inner peripheral surface of the outer cylinder member 32 and the partition wall 33.

On the other hand, as shown in FIG. 2A, an annular bottom surface forming member 31b for closing the bottom of the cooling fluid flow gap CL is also provided.
The lower end surface of the inner cylindrical member 31 is joined by a fillet-shaped welded portion Y facing the cooling fluid flow gap CL.
That is, the forced cooling cylinder 1 including the welded portion of the partition wall 33
In No. 1, a structure in which no weld is formed on the heat-exposed surface is realized.

As shown in FIG. 2, the cooling fluid from the introduction pipe 12 flows down, for example, through a downflow passage 35 formed in the inner cylinder member 35, and then opens at the lower end of the inner cylinder member 35. The fluid flows into the medium flow gap CL from the fluid inlet 36. Then, as shown in FIG. 5 (b), it rises toward the upper part of the cylinder while circulating in the spiral flow path 34 formed by the partition wall 33, and cools at the upper end of the outer cylinder member 32. From the fluid outlet 30 to the forced cooling cylinder 11
Is discharged outside. FIG. 5A shows the transition of the position in the cylinder axis direction and the circumferential direction when the cooling fluid flowing into the forced cooling cylinder 11 moves in the circulation path 34. First, after flowing down in the flow-down passage portion 35 in the direction of the cylinder axis O (see FIG. 2) at a certain position in the circumferential direction, each time the lapping along the partition wall 33 with a constant gradient is repeated, the flow continues in the cylinder axis direction. FIG. 5 schematically and conceptually shows how the image gradually rises (FIG. 5). In addition, in FIG.
Is a guide partition wall for guiding the cooling fluid W toward the cooling fluid outlet 30.

In order to facilitate the arrangement of the partition wall 33, the partition wall 33 may be configured as shown in FIG.
That is, a plurality of fin-shaped segments 40 each having a fixed axial position are arranged at regular intervals, and the space adjacent to each segment 40 is defined by the segment 40.
Are connected to each other in the form of a cutout in the circumferential direction, and the adjacent segments 40 are successively connected to each other by the connecting wall 41 at the cutout position. Thereby, the step-like flow path 34 formed by the segment 40 and the connecting wall 41 can be formed. As shown in FIG.
The cooling fluid W gradually rises in the axial direction of the cylinder every time the circulation is repeated. Reference numeral 133 denotes a partition wall for preventing the cooling fluid W flowing from the cooling fluid inlet 36 from flowing backward.

In the forced cooling cylinder 11 having the jacket structure as described above, the cooling fluid W can be brought into contact with the entire surface of the inner cylinder member 31, so that the cooling efficiency is high. Further, in the present invention, the cooling fluid flow gap C is formed by the spiral partition wall 33.
By partitioning at L, short-circuiting (short-cut) of the cooling fluid W can be effectively prevented, and thus the cooling fluid in both the circumferential direction and the axial direction of the forced cooling cylinder 11 along the spiral-shaped flow path 34. Can be distributed uniformly. As a result, it is possible to prevent cooling unevenness and improve cooling efficiency.

As shown in FIG. 6 (for ease of understanding, the flow path 34 is linearly developed and drawn), the cooling medium W flowing out of the cooling fluid outlet 30 is returned to the return line. By returning to the distribution channel 34 via 51, a circulating flow can be formed. This circulating flow can be formed by a pump 52 as a liquid sending means disposed on the circulating path. Further, the cooling fluid whose temperature has been raised can be cooled by the cooling tower 60 serving as a radiator on the return pipe line 51.

Next, returning to FIG. 2, the temperature of the cooling fluid W flowing inside the forced cooling cylinder 11 is measured by a temperature sensor 57 provided inside the forced cooling cylinder 11, specifically, in the cooling fluid flow gap CL. Can be measured. When an excessive temperature rise or the like occurs in the forced cooling cylinder 11, the temperature can be immediately detected by the temperature sensor 57. Since the excessive temperature rise is likely to occur at the lower end of the forced cooling cylinder 11 facing the melt 4, if the temperature sensor 57 is arranged at the lower end of the corresponding cooling fluid flow gap CL, the excessive temperature rise will occur. It becomes easier to detect the temperature rise. However, as shown by a dashed line in the figure, the cooling fluid circulation gap CL has an axial middle position or an upper end portion.
If a plurality of temperature sensors 57 are arranged in a distributed manner and each temperature is detected, it is possible to perform a more sensitive overheating detection and to know the temperature distribution in the forced cooling cylinder 11. Therefore, it is also possible to monitor the occurrence of uneven cooling or the like. As the temperature sensor, a known sensor such as a thermistor can be used in addition to the thermocouple.

Further, as shown in FIG.
Control unit 5 constituted by a computer or the like
0, and if the detected temperature deviates from a predetermined target value, the control unit 50 automatically controls a temperature adjusting mechanism provided in advance so that the detected temperature of the temperature sensor 57 approaches the target value. The temperature of the cooling fluid can be adjusted. As a particularly useful aspect among them, a control mode in which when an excessive temperature rise of the cooling fluid is detected, the temperature is reduced to an appropriate temperature range can be exemplified. In the embodiment shown in FIG. 6, when the temperature sensor 57 detects an excessive temperature rise,
The control unit 50 operates to increase the flow rate of the cooling fluid W flowing in the forced cooling cylinder 11 to promote cooling. Specifically, a bypass path 53 is provided in a form branched from the main circulation path MC of the cooling fluid W, and the flow distribution ratio between the main circulation path MC and the bypass path 53 is adjusted by the valve 54. . Here, the main circulation path M
C and the bypass path 53 respectively
Is provided to adjust the flow rate distribution ratio by adjusting the opening amount and / or opening time of the valves 54, 54, but the present invention is not limited to this.

The temperature of the cooling fluid can be adjusted by, for example, forced overheating by a heater, in addition to the flow rate adjustment. In this case, it is of course possible to combine heater heating and flow rate adjustment. For example, if a more subtle and quick temperature adjustment is required, besides the flow adjustment,
Alternatively, it may be more convenient to employ heater heating in addition to flow rate adjustment. In the case of excessive temperature rise, it is effective to increase the flow rate of the cooling fluid. On the other hand, when the temperature of the forced cooling cylinder is too low, it may not be possible to cope with the decrease in the flow rate alone.

FIG. 7 shows an example in which a heater 56 is provided in the flow path 34, and the heater 56 can be heated by the power supply 55. The control unit 50 controls the heater 5 of the power supply 55 so that the temperature detection value of the temperature sensor 57 approaches the target temperature.
6 to adjust the power output. In this embodiment, the flow rate is also adjusted by adjusting the operation of the valve 54, but this may be omitted. Also, the heater 56
Is disposed over substantially the entire length of the flow path 34, but the heater 56 may be provided only in a part of the flow path 34 suitable for heating the cooling fluid. For example, when the temperature near the lower end portion of the forced cooling cylinder 11 becomes a problem, similarly to the temperature sensor 57, only in the section corresponding to the portion (that is,
Only near the end near the inlet 36 of the distribution channel 34),
A heater 56 may be provided.

The heating of the cooling fluid W by the heater 56 may be performed outside the flow path 34. For example, FIG. 8 shows a case in which a temperature adjustment chamber 34a is provided on the upstream side of the flow path 34, a heater 56 is disposed in the temperature adjustment chamber 34a, and the temperature of the cooling fluid W is preliminarily adjusted by the heat generated from the temperature. I try to lead inside.

Further, when the temperature distribution of the cooling cylinder becomes uneven, there may be a case where it is desired to finely adjust the local temperature in order to eliminate the unevenness. Therefore, as shown in FIG. 9, the heaters 56 are dispersedly arranged along the circulation path 34,
If the output can be controlled independently of each other, such a response can be easily performed. In this case, the temperature sensors 57 are distributed and arranged along the circulation route 34, and the heater 56 at a predetermined position is determined in accordance with the position of the temperature sensor 57 at which the deviation of the detected temperature value from the target value becomes large.
Output is selectively adjusted.

The present invention is not limited to the embodiments described above, and various improvements or modifications can be made without departing from the concept described in the claims. It belongs to the technical scope of the present invention. For example, as shown in FIG.
Instead of employing a jacket structure, a forced cooling cylinder 111 having a structure in which a spirally wound metal cooling pipe 113 is fixedly welded to the outer peripheral surface of the inner cylindrical member 111a, for example, may be employed. In this case, the cooling fluid is introduced into the cooling pipe 113 from the inlet 112 on the lower end of the cooling cylinder 111 and discharged from the outlet 114 on the upper end.

On the other hand, when the jacket structure is adopted, the circulation path 34 is not necessarily limited to a spiral path. FIG. 10B shows an example of such a case, in which flange-shaped partition walls 143 separated from each other are arranged at predetermined intervals in the axial direction of the forced cooling cylinder 11.
A flow hole 143 a (or a narrow gap formed between the outer cylinder member 32 and the outer edge of the partition wall 143) may be formed in the hole. Adjacent partition wall 143,
By forming an annular space between 143, fluid flow in the circumferential direction is promoted, and since the partition wall 143 is intermittently arranged in the axial direction, shortcuts and the like are also suppressed.

[0045]

The results of experiments conducted to confirm the effects of the present invention will be described below. See Figure 1 for single crystal growth.
This was performed using the apparatus shown in FIG. Specifically, caliber 60c
After filling 150 kg of polycrystalline silicon, which is a raw material of silicon single crystal, into a quartz crucible having a diameter of m and melting it by heating a heater, a silicon single crystal having a constant diameter with a constant diameter of 200 mm was pulled up. As shown in FIG. 2, the temperature sensor 5 attached to the lower end of the forced cooling cylinder 11
7, the cooling water temperature during the crystal pulling was monitored. Note that the detection target temperature of the temperature sensor was 30 ° C. The result is shown in FIG. In other words, it can be seen that, by employing the apparatus of the present invention, the temperature of the cooling water changes while the temperature variation is stable at 5 ° C. or less during the growth of the single crystal, and a substantially constant cooling effect is obtained. In particular, it can be seen that there is almost no temperature change during the growth of the single crystal constant diameter portion, and the crystal is grown in a stable atmosphere.

FIG. 12 shows the axial direction (longitudinal direction) of the inner surface of the cooling cylinder under substantially the same conditions as when the constant-diameter portion is pulled up, measured by temperature sensors arranged at appropriate intervals in the axial direction.
FIG. The solid line is a case where the apparatus of the present invention is used, and the broken line is a comparative example using a forced cooling cylinder having a jacket structure without a partition wall. According to this, when the apparatus of the present invention is used, the temperature is lower over the entire area in the axial direction than in the comparative example, and a uniform and good cooling effect is obtained. The temperature gradient in the axial direction is also gentler in the apparatus of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a semiconductor single crystal manufacturing apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view and a transverse sectional view showing an example of a detailed structure of a forced cooling cylinder in the apparatus of FIG.

FIG. 3 is a perspective view showing an internal structure of a forced cooling cylinder of FIG. 2;

FIG. 4 shows a relationship between a partition wall and an inner cylinder member and an outer cylinder member.
The figure shown with a modification.

FIG. 5 is an operation explanatory view of the forced cooling cylinder of FIG. 2 and a forced cooling cylinder of a modified example thereof.

FIG. 6 is a diagram conceptually showing an example of an apparatus in which temperature adjustment of a forced cooling cylinder can be controlled by adjusting a flow rate of a cooling fluid.

FIG. 7 is a diagram conceptually illustrating an example of an apparatus in which temperature adjustment of a forced cooling cylinder can be controlled by a heat generation amount of a heater.

FIG. 8 is a diagram showing a modification of the arrangement of heaters in the apparatus shown in FIG. 7;

FIG. 9 is a diagram showing another modified example.

FIG. 10 is a schematic sectional view showing some modified examples of the forced cooling cylinder.

FIG. 11 is a graph showing a measurement result of a change in temperature change of a cooling fluid in an experiment performed in an example.

FIG. 12 is a graph showing a measurement result of a vertical temperature distribution on the inner surface of a forced cooling cylinder in an experiment performed in an example, in comparison with a comparative example.

[Explanation of symbols]

 Reference Signs List 3 semiconductor single crystal 4 raw material melt 5, 6 crucible 11 forced cooling cylinder 20 semiconductor single crystal manufacturing device 30 cooling fluid outlet 31 inner cylinder member 32 outer cylinder member 33 partition wall (circumferential flow correcting part) 36 cooling fluid inlet Y welding Part 57 Temperature sensor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryoji Hoshi 150 Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture F-term in Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa Research Laboratory 4G077 AA02 BA04 CF10 EG15 EG25 FE11 HA12

Claims (9)

[Claims] 1. A forced cooling cylinder for circulating a cooling fluid is disposed above a raw material melt so as to surround a semiconductor single crystal pulled up from the raw material melt contained in a crucible, and the semiconductor single crystal pulled up by the forced cooling cylinder is disposed. In a semiconductor single crystal manufacturing apparatus for growing a single crystal by the Czochralski method while removing radiant heat from a crystal, when flowing a cooling fluid through the forced cooling cylinder, the cooling fluid is forced into a forced cooling cylinder close to a raw material melt. To the lower end portion, and thereafter, the cooling fluid is allowed to flow from the lower end portion of the cylinder toward the upper end while promoting the flow in the circumferential direction of the cylinder by a circumferential flow correcting portion provided in the forced cooling cylinder. An apparatus for manufacturing a semiconductor single crystal, comprising: 2. The forced cooling cylinder has an annular cooling fluid circulation gap formed between an inner cylinder member and an outer cylinder member, and has a cooling fluid inlet and a cooling fluid outlet communicating with the cooling fluid circulation gap. The circumferential flow straightening section has a circumferential partitioning surface that intersects the cylinder axis while allowing the cooling fluid to flow from the lower end to the upper end. 2. The semiconductor single crystal manufacturing apparatus according to claim 1, further comprising a partition wall for partitioning the flow gap. 3. The device according to claim 1, wherein the circumferential flow straightening unit is provided to guide the cooling fluid from a lower end of the cylinder to an upper end thereof along a spiral path.
Or the semiconductor single crystal manufacturing apparatus according to 2. 4. The semiconductor single crystal manufacturing apparatus according to claim 3, wherein the partition wall of the forced cooling cylinder having the jacket structure is provided so as to partition the cooling fluid flow gap into a spiral flow path. 5. The method according to claim 1, wherein a welded portion for joining each component of the forced cooling cylinder is not provided on the surface of the raw material melt and the surface facing the semiconductor single crystal pulled up from the raw material melt. 5. The apparatus for producing a semiconductor single crystal according to any one of items 4 to 4. 6. In order to measure the temperature of the cooling fluid flowing through the inside of the forced cooling cylinder, the inside of the forced cooling cylinder is
The semiconductor single crystal manufacturing apparatus according to any one of claims 1 to 5, wherein a temperature sensor is attached at more than one place. 7. The semiconductor single crystal manufacturing apparatus according to claim 6, wherein said temperature sensor is attached at least at a position for measuring a temperature of a cooling fluid flowing through a lower end portion of said forced cooling cylinder. 8. A single crystal using a Czochralski method while removing radiant heat from the semiconductor single crystal pulled up by the forced cooling cylinder, using the semiconductor single crystal manufacturing apparatus according to claim 1. A method for producing a semiconductor single crystal, comprising: 9. The temperature of the cooling fluid flowing through the forced cooling cylinder is measured by the temperature sensor, and the flow rate and / or temperature of the cooling fluid is adjusted so that the temperature of the cooling fluid becomes a predetermined temperature. The method for producing a semiconductor single crystal according to claim 8, wherein the single crystal is grown.