JP2021046344A - Semiconductor crystal manufacturing apparatus - Google Patents

Abstract

To equalize the exhaust speeds of gas flows flowing in a plurality exhaust pipes connected corresponding to a plurality of exhaust ports provided in the bottom of a chamber.SOLUTION: The semiconductor crystal manufacturing apparatus comprises: first to fourth exhaust ports for exhausting gas introduced into a chamber manufacturing a semiconductor crystal; individual exhaust pipes 31A-31D having one ends connected to the corresponding first to fourth exhaust ports; and a coupling pipe 32 connected to the other ends of the individual exhaust pipes 31A-31D. Distances to the second coupling part C21 of the coupling pipe 32 through the corresponding individual exhaust pipes 31A-31D from the first to fourth exhaust ports are substantially equal.SELECTED DRAWING: Figure 3

Description

The present invention uses, for example, the Czochralski method (hereinafter abbreviated as "CZ method") and the floating zone melting method (hereinafter abbreviated as "FZ method") single crystal growth method. The present invention relates to a semiconductor crystal manufacturing apparatus for manufacturing a semiconductor crystal.

In the CZ method, a silicon single crystal is pulled up from a silicon melt melted in a crucible provided in a chamber to produce the silicon single crystal. In this manufacturing process, _{oxygen (O 2} ) is dissolved from the pit containing _{silicon dioxide (SiO 2} ) and reacts with the silicon melt to produce silicon oxide (SiOx) or silicon dioxide (SiO ₂ ).

The silicon oxide (SiOx) or the silicon dioxide (SiO ₂ ) evaporates from the surface of the silicon melt. Hereinafter, when the silicon oxide (SiOx), silicon dioxide (SiO ₂ ), and the dopant described later that have evaporated from the surface of the silicon melt are collectively referred to, the term "evaporate" is used.

In silicon oxide (SiOx), x takes a value of 0 <x <2. Silicon oxide (SiOx) is generated because sufficient oxygen (O ₂ ) is not present in the silicon melt and in the atmosphere in the chamber as compared with the silicon atom (S), so that the silicon atom (S) is completely absent. This is because it is not oxidized.

The evaporator reaches the inner wall surface of the chamber above the surface of the silicon melt, and a part thereof adheres to the inner wall surface of the chamber. When this deposit falls and melts in the silicon melt and is incorporated into the silicon single crystal being pulled up, defects (for example, dislocation) may occur in the produced silicon single crystal.

In order to prevent such inconvenience, in the semiconductor crystal manufacturing apparatus, an inert gas is introduced from a gas introduction port provided above the chamber, and an exhaust port provided at the bottom of the chamber and an exhaust pipe connected to the exhaust port are connected. And the exhaust device is used to exhaust the inert gas and evaporation to the outside of the chamber while maintaining the pressure inside the chamber at a low pressure of several thousand Pa.

In the conventional semiconductor crystal manufacturing apparatus, a plurality of exhaust ports are provided on the bottom wall of the chamber, and a plurality of exhaust pipes arranged substantially vertically downward are connected to each exhaust port, and each exhaust pipe is connected to the other. In front of the exhaust pipe and the pressure control device, there are some that are collectively connected to each other (see, for example, Patent Document 1).

Japanese Patent No. 4423805 (Figs. 1 and 5)

The evaporation that reaches the exhaust pipe from the chamber in the high temperature atmosphere is gradually cooled as it passes through the exhaust pipe, and a part of it is exhausted to the outside, but a part of it adheres to the inner wall surface of the exhaust pipe and accumulates. I will go. The thickness of the deposits on the inner wall surface of the exhaust pipe increases as the number of times the silicon single crystal is pulled up increases.

If deposits remain on the inner wall surface of the exhaust pipe, the following various problems may occur.
(1) The deposits flow back into the chamber and mix with the silicon melt, causing defects (for example, dislocations) in the produced silicon single crystal.

(2) Since the exhaust resistance of the exhaust pipe whose inner diameter is reduced due to the deposits increases, it becomes difficult to control the pressure in the chamber, and the pressure in the chamber tends to fluctuate greatly. As a result, the pulling condition of the silicon single crystal is adversely affected, and the deposits peeled off from the inner wall surface of the exhaust pipe infiltrate into the inside of the equipment (for example, a vacuum pump) downstream of the exhaust pipe and damage the equipment. Or something.

(3) A dopant may be added to the silicon melt in order to impart desired properties to the silicon single crystal. Dopants include, for example, n-type dopants typified by arsenic (As), phosphorus (P) and antimony (Sb), and p-type dopants typified by, for example, boron (B) and aluminum (Al). ..

Since the boiling point of the n-type dopant is lower than the melting point of silicon, it easily evaporates from the surface of the silicon melt in the process of producing the silicon single crystal. As a result, the concentration of the n-type dopant in the silicon melt may be lower than the set value, and the produced silicon single crystal may not have desired properties (for example, resistivity). In order to prevent such inconvenience, when the n-type dopant is added, the pressure in the chamber is set higher than the low pressure of several thousand Pa.

However, the pressure in the chamber was set to a low pressure of several thousand Pa in order to prevent the evaporation from the surface of the silicon melt from reaching the inner wall surface of the chamber. If the pressure in the chamber is set high, the concentration of evaporation in the exhaust pipe becomes high. The amount of deposits on the inner wall surface of the exhaust pipe is larger than that in the case where the dopant is not added and in the case where the p-type dopant is added. Therefore, the possibility that the problems shown in (1) and (2) above will occur is further increased.

In the prior art described in Patent Document 1, the distance from each exhaust port provided on the bottom wall of the chamber to the pressure control device via the corresponding exhaust pipe is different. According to the knowledge, when the length of the exhaust pipe is sufficiently long, the exhaust speed in the exhaust pipe is substantially inversely proportional to the length of the exhaust pipe. Therefore, in the conventional technique described in Patent Document 1, the exhaust speed in each exhaust pipe is also different. As a result, for example, in the portion where the exhaust pipes are connected, the gas flow of the inert gas is disturbed, so that the problems shown in (1) to (3) above occur. However, the means for solving these problems is not disclosed in Patent Document 1.

An object of the present invention is to solve the above-mentioned various problems as an example, and an object of the present invention is to provide a semiconductor crystal manufacturing apparatus capable of solving these problems.

In order to solve the above problems, from each exhaust port provided at the bottom of the chamber, a plurality of individual exhaust pipes connected to the corresponding exhaust ports and a plurality of coupling pipes connected to these individual exhaust pipes are provided. After that, the distances to the joints where each coupling pipe is connected to one in order to connect to the exhaust system may be equalized. In this case, it is preferable that at least the directly connected exhaust pipes have the same or symmetrical shape and have the same inner diameter.

However, since a driving means for raising and lowering the crucible while rotating it is provided in the center of the bottom of the chamber, it is necessary to avoid interference with this. If the length of the exhaust pipe is made unnecessarily long in order to avoid interference with the drive means, a wide installation space for the exhaust pipe is required, installation costs are high, and an inert gas is attached through the longer exhaust pipe. An exhaust device having a strong suction force is required to suck the kimono.

Therefore, the findings obtained as a result of intensive research by the present inventors will be described with reference to FIG. FIG. 1 shows an example in which _{eight exhaust ports EH 1 to EH 8 are formed at the bottom of the chamber.}
First, the exhaust ports EH _{1 to EH 8} are formed at symmetrical positions about the central axis of the driving means at the bottom of the chamber. Eight individual exhaust pipe _EP 1 _{~EP 8} each one end connected to the corresponding outlet _EH 1 _{~EH 8} is a separate exhaust pipes two adjacent _{(EP 1, EP 2),} (EP 3, EP ₄ ), (EP ₅ , EP ₆ ), and (EP ₇ , EP ₈ ) are paired.

Individual exhaust pipes which are paired _{(EP 1,} EP _2), coupled with _{(EP 3, EP 4),} (EP 5, EP 6), (EP 7, EP 8) , each coupling unit _C 11 _{-C 14} In the same or symmetrical shape, the shape is symmetrical with respect to the reference plane that passes through the central axis of the driving means and passes through the corresponding coupling portions C _{11 to} C _14. It has the same inner diameter and the same dimensions. In the example of FIG. 1, the exhaust pipe EP ₁ and the exhaust pipe EP ₂ form substantially a V shape. In FIG. 1, for example, the symbol of a single line that intersects the line segment _{from the exhaust port EH 1} to the first joint portion C _{11 and the line segment that intersects the line segment from the exhaust port EH 2} to the first joint portion C ₁₁ intersect. The single line symbol indicates that these lengths are equal, that is, _{the length of the exhaust pipe EP 1 and} the length of the exhaust pipe EP ₂ are equal.

The other ends of the paired individual exhaust pipes (EP ₁ , EP ₂ ), (EP ₃ , EP ₄ ), (EP ₅ , EP ₆ ), and (EP ₇ , EP ₈ ) are the first joints C. It is combined at ₁₁ , C ₁₂ , C ₁₃ and C _{14, respectively.} Two adjacent first joints (C ₁₁ , C ₁₂ ) and (C ₁₃ , C ₁₄ ) are paired. The paired first joint (C ₁₁ , C ₁₂ ) is connected to the first joint tube CP _11. The paired first coupling (C ₁₃ , C ₁₄ ) is connected to the first coupling tube CP _12.

First coupling pipe _{CP 11} includes a branch unit _{B 11} which is connected to the first coupling part _{C 11,} one end of the corresponding, the branch unit _{B 12} having one end connected to the first coupling part _{C 12} corresponding have. The other end of the branch portion B _{11 and} the other end of the branch portion B ₁₂ are connected to the second joint portion C _21. First coupling pipe _{CP 12} includes a branch _{B 13} which is connected to the first coupling part _{C 13,} one end of the corresponding, the branches _{B 14} having one end connected to the first coupling part _{C 14} corresponding have. The other end of the branch portion B _{13 and} the other end of the branch portion B ₁₄ are connected to the second joint portion C _22.

The first coupling tube CP ₁₁ has the same or symmetrical shape so as to pass through the central axis of the driving means and to have a symmetrical shape with respect to the reference plane passing through _{the second coupling portion C 21.} .. The branch portion B ₁₁ and the branch portion B ₁₂ have the same inner diameter and the same dimensions. The first coupling tube CP ₁₂ has the same or symmetrical shape so as to pass through the central axis of the driving means and to have a symmetrical shape with respect to the reference plane passing through _{the second coupling portion C 22.} .. The branch portion B ₁₃ and the branch portion B ₁₄ have the same inner diameter and the same dimensions. In the example of FIG. 1, the first connecting tubes CP ₁₁ and CP ₁₂ form substantially V-shapes.

In FIG. 1, for example, a symbol of two lines intersecting a line segment _{from the first joint portion C 11} to the second joint portion C _{21, and from the first joint portion C 12} to the second joint portion C _21. The two-line symbol that intersects the line segment of the above indicates that these lengths are equal, that is, _{the length of the branch B 11 and} the length of the branch B ₁₂ are equal.

Two adjacent second joints (C ₂₁ , C ₂₂ ) are paired. The paired second coupling portion (C ₂₁ , C ₂₂ ) is connected to the second coupling tube CP _21. The second coupling pipe _{CP 21} includes a branch _{B 21} to be connected to the second coupling part _{C 21,} one end of the corresponding, the branch unit _{B 22} one end of which is connected to the second coupling part _{C 22} corresponding have. The other end of the branch portion B _{21 and} the other end of the branch portion B ₂₂ are connected to the third joint portion C _31. The third coupling portion C ₃₁ is connected to one end of the third coupling tube CP _31. The other end of the third coupling pipe CP ₃₁ is connected to an exhaust device (not shown).

The second coupling tube CP ₂₁ has the same or symmetrical shape so as to pass through the central axis of the driving means and to have a symmetrical shape with respect to the reference plane passing through _{the third coupling portion C 31.} .. The branch portion B ₂₁ and the branch portion B ₂₂ have the same inner diameter and the same dimensions. In the example of FIG. 1, the second connecting tube CP ₂₁ is substantially V-shaped.

In FIG. 1, the symbol of three lines intersecting the line segment _{from the second joint portion C 21} to the third joint portion C _{31 and the line from the second joint portion C 22} to the third joint portion C _31. The three-line symbol that intersects the minute indicates that these lengths are equal, that is, _{the length of branch B 21 and} the length of branch B ₂₂ are equal.

The generalization of the findings described above is as follows.
First, 2 2 n ⁽ⁿ is an integer of 2 or more) number of exhaust ports formed symmetrically positioned about the central axis of the drive means of the chamber bottom, connected to each exhaust port each end corresponding ^{n An individual exhaust pipe of a book and 2 n-1} first coupling portions to which the other ends of a pair of adjacent individual exhaust pipes are coupled are provided.

Next, 2 ^n-k- 1th (k + 1) coupling portions and 2 ^n-k- 1th coupling pipes are provided. Each k-th coupling tube has a pair of branches, each end of each branch is connected to a pair of adjacent k-th couplings, and the other ends of the branches are coupled to correspond to each other. Connect to the joint of (k + 1). k is a positive integer that increases by 1 from 1 to (n-1). For the first (k + 1) coupling portion and the kth coupling pipe, k is incremented by 1 from 1 to (n-1) to form a piping portion. Then, the nth joint portion, which is the end of the piping portion, is connected to the exhaust device. The distances from each exhaust port to the nth joint via the corresponding individual exhaust pipes are all equal.

In this regard, even if the number of exhaust ports is an odd number or an ^{even number other than 2 n} (for example, 6), the distance from each exhaust port to the exhaust device via the corresponding individual exhaust pipe is equally configured. It seems possible. However, it is difficult for each individual exhaust pipe to form a pipe configuration in the shortest distance while avoiding interference with the drive means.

In order to solve the above problems, the semiconductor crystal manufacturing apparatus according to the invention according to claim 1 has the first, second, third and fourth exhaust gas introduced into the chamber for manufacturing the semiconductor crystal. An exhaust port, a first, second, third and fourth individual exhaust pipes to which one end is connected to each of the corresponding first to fourth exhaust ports, and a pair of adjacent first and first exhaust pipes. A second coupling portion in which the other ends of the two individual exhaust pipes are coupled and connected to each other and a second coupling portion in which the other ends of the pair of adjacent third and fourth individual exhaust pipes are coupled and connected to each other. It has a first branch portion whose one end is connected to the first joint portion, and a second branch portion whose one end is connected to the second joint portion. Each of the other ends of the second branch portion is provided with a coupling pipe connected to the third coupling portion, and the corresponding first to fourth individual units are provided from the first to fourth exhaust ports. It is characterized in that the distances from the exhaust pipe to the third joint portion are substantially the same.

The invention according to claim 2 relates to the semiconductor crystal manufacturing apparatus according to claim 1, wherein the first to fourth exhaust ports are centers of driving means for moving a muffler provided in the chamber up and down while rotating. The pair of the first and second individual exhaust pipes provided at positions symmetrical with respect to the axis have a shape symmetrical with respect to the first reference plane passing through the central axis, and the pair of the first and second individual exhaust pipes have a shape symmetrical with respect to the first reference plane passing through the central axis. The third and fourth individual exhaust pipes have a shape symmetrical with respect to the first reference plane, and the pair of the first and second individual exhaust pipes is a pair of the third and fourth individual exhaust pipes. The tube is characterized in that it passes through the central axis and is provided at a position symmetrical with respect to a second reference plane different from the first reference plane.

The semiconductor crystal manufacturing apparatus according to the third aspect of the invention corresponds to 2 ⁿ (n is an integer of 2 or more) exhaust ports for exhausting the gas introduced into the chamber for manufacturing the semiconductor crystal, and one end of each exhaust port. ^{2 n} individual exhaust pipes connected to each of the exhaust ports, ^{and 2 n-1} first coupling portions connected by connecting the other ends of a pair of adjacent individual exhaust pipes. , 2 ^n−k-1 {k is a positive integer increasing by 1 from 1 to (n-1)} It has a (k + 1) th (k + 1) joint and a pair of branches, and each of the branches one end is connected to the junction of the pair k-th adjacent, 2 ^n-k-1 present the other end of each of said branches is connected to the coupling portion of the (k + 1) corresponding bound The k-th coupling pipe is provided, and the distances from each of the exhaust ports to the n-th coupling portion via the corresponding individual exhaust pipes are substantially the same.

The semiconductor crystal manufacturing apparatus according to the fourth aspect of the present invention includes a chamber for manufacturing a semiconductor crystal, an exhaust gas provided in the chamber, a heater arranged so as to surround the exhaust gas, and a heater for heating the exhaust gas. ^{2 n} (n) formed at the lower part of the upper exhaust port for exhausting the gas introduced into the chamber from the upper part of the heater and the corresponding upper exhaust port, and communicating with both of the lower exhaust port for exhausting the gas from the lower part of the heater. ^{Is an integer of 2 or more), 2 n} exhaust ports formed at the bottom of the chamber and connected to the lower end of each corresponding exhaust duct, and each end corresponding to each of the exhaust ports. Two ^{n individual exhaust pipes to be connected to each other, 2 n-1} first coupling portions to which the other ends of the pair of adjacent individual exhaust pipes are connected to each other ^{, and 2 n-k- 1} {k is a positive integer that increases by 1 from 1 to (n-1)} A pair of (k + 1) first (k + 1) joints and a pair of branches, each end of which is adjacent to each other. ^{Two n-k-1 k-th} coupling tubes that are connected to the k-th coupling portion, and the other ends of the branch portions are coupled to each other and connected to the corresponding (k + 1) -th coupling portion. It is characterized in that the distances from the upper end of each of the exhaust ducts to the nth coupling portion via the corresponding individual exhaust pipes are substantially the same.

The invention according to claim 5 relates to the semiconductor crystal manufacturing apparatus according to claim 3 or 4, wherein the ²ⁿ exhaust ports are driving means for raising and lowering a muffler provided in the chamber while rotating the muffler. The two adjacent individual exhaust pipes, which are provided at positions symmetrical with respect to the central axis of the above, have a shape symmetrical with respect to the reference plane passing through the central axis, and the other two adjacent exhaust pipes. The individual exhaust pipe is characterized in that it passes through the central axis and is provided at a position symmetrical with respect to a reference plane different from the reference plane.

The invention according to claim 6 is related to the semiconductor crystal manufacturing apparatus according to any one of claims 1 to 5, and is characterized in that a silicon single crystal to which an n-type dopant is added is manufactured.

All of the "distances from each of the first to fourth exhaust ports to the third joint via the corresponding first to fourth individual exhaust pipes" in claim 1 are physically completely equalized. This is not possible due to the dimensional tolerance of each individual exhaust pipe and the difference in the amount of material (in the case of welding, filler metal) when connecting the individual exhaust pipe and the coupling pipe. An object of the present invention is to make the exhaust speed of gas flows flowing through a plurality of exhaust pipes uniform, and if this object can be achieved, the variation in the distance can be tolerated. This also applies to claims 3 and 4.
Therefore, "substantially equal" in claims 1, 3 and 4 does not mean physically perfect equality, but equality to the extent that the exhaust velocity of the gas flow can be made uniform. To do.

According to the present invention, it is possible to make the exhaust speed of the gas flow flowing in the plurality of exhaust pipes connected corresponding to the plurality of exhaust ports provided at the bottom of the chamber uniform.

It is a conceptual diagram which shows an example of the piping structure of the semiconductor crystal manufacturing apparatus based on the knowledge of this invention. It is a conceptual diagram which shows an example of the structure of the semiconductor crystal manufacturing apparatus which concerns on Embodiment 1 of this invention. It is a perspective view which shows an example of the structure of the piping part which comprises the semiconductor crystal manufacturing apparatus shown in FIG. It is a top view which shows an example of the structure of the piping part which comprises the semiconductor crystal manufacturing apparatus shown in FIG. It is a side view which shows an example of the structure of the piping part which comprises the semiconductor crystal manufacturing apparatus shown in FIG. It is a conceptual diagram which shows an example of the structure of the semiconductor crystal manufacturing apparatus which concerns on Embodiment 2 of this invention. It is sectional drawing which shows an example of the structure of the exhaust passage of the semiconductor crystal manufacturing apparatus which concerns on Embodiment 2 of this invention. It is a top view which shows an example of the structure of the piping part which is a comparative example. It is a side view which shows an example of the structure of the piping part which is a comparative example.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1.
FIG. 2 is a conceptual diagram showing an example of the configuration of the semiconductor crystal manufacturing apparatus 1 according to the first embodiment of the present invention. The semiconductor crystal manufacturing apparatus 1 manufactures a silicon single crystal by using the CZ method. The semiconductor crystal manufacturing apparatus 1 includes a semiconductor crystal manufacturing unit 11 and a gas exhaust unit 12.

The semiconductor crystal manufacturing unit 11 is installed on the floor FC of the clean room CR. The semiconductor crystal manufacturing unit 11 includes a hollow chamber 21 having upper and lower ends open, a single crystal pulling unit 22 connected to the upper end of the chamber 21, and a gas introducing unit 23 for introducing an inert gas into the chamber 21. There is. The chamber 21 accommodates a substantially bottomed cylindrical crucible 25 that stores the silicone melt M.

The chamber 21 includes a driving means 51 that moves the crucible 25 up and down while rotating, a heater that is arranged outside the crucible 25 at predetermined intervals and heats the silicon melt M, and a heater outside the heater. Accommodates heat insulating tubes arranged at intervals. The single crystal pulling unit 22 pulls up the silicon single crystal SM by immersing the seed crystal (not shown) in the silicon melt M in the crucible 25 and then pulling it up while rotating it in a predetermined direction.

The base plate (not shown) that constitutes the bottom of the chamber 21 and is placed on the floor FC has 2 ⁿ (n is an integer of 2 or more) in order to exhaust the inert gas introduced into the chamber 21 to the outside. ) Exhaust ports 24, in the first embodiment, n = 2, that is, four exhaust ports 24A to 24D are formed, respectively. The exhaust ports 24A to 24D have a substantially circular cross-sectional shape. In FIG. 2, the exhaust ports 24A to 24D are shown directly on the floor FC and in a straight line at predetermined intervals. However, the exhaust ports 24A to 24D are actually the upper surfaces of the base plate, and in a plan view, they pass through the central axis of the drive means 51 and are positioned substantially symmetrically with respect to the reference planes RT1 and RT2 orthogonal to each other. It is formed above each of the corresponding individual exhaust pipes 31A to 31D (see FIG. 4) formed in.

In FIG. 2, the gas exhaust unit 12 is installed under the floor FC of the clean room CR and under the floor FP of the pump room PR. The exhaust ports 24A to 24D are bored under the floor FC of the base plate and the clean room CR. At each lower end of the exhaust ports 24A to 24D, there are 2 ⁿ individual exhaust pipes 31 corresponding to the exhaust ports 24A to 24D. In the first embodiment, n = 2, that is, four individual exhaust pipes 31A to Each end of 31D is connected.

The other ends of the individual exhaust pipes 31A to 31D are connected to the coupling pipe 32. The individual exhaust pipes 31A to 31D and the coupling pipe 32 constitute a piping portion 13. The other end of the coupling pipe 32 is connected to the input end of the trap 33. The output end of the trap 33 is connected to one end of the exhaust pipe 34. The trap 33 peels off from the inner walls of the individual exhaust pipes 31A to 31D and captures the peeled material that has passed through the coupling pipe 32.

The exhaust pipe 34 is piped from under the floor FC of the clean room CR to under the floor FP of the pump room PR. The exhaust pipe 34 is branched into an exhaust pipe 35 and an exhaust pipe 36 in the middle of being piped under the floor FP of the pump chamber PR. One end of the exhaust pipe 35 is connected to the input end of the main valve 37 which is opened when the silicon single crystal is manufactured and closed when the deposits are removed.

The output end of the main valve 37 is connected to the input end of the main pump 39 via the exhaust pipe 38. The output end of the main pump 39 is connected to one end of the exhaust pipe 40, and the other end of the exhaust pipe 40 is connected to the scrubber 41. The main pump 39 operates during the production of the silicon single crystal, sucks the inert gas, evaporation, and dust that have passed through the exhaust pipe 38, and supplies the inert gas, evaporation, and dust to the scrubber 41 via the exhaust pipe 40. The scrubber 41 mud deposits that have passed through the exhaust pipe 40 and the exhaust pipe 45 described later.

One end of the exhaust pipe 36 is connected to the input end of the sub valve 42 which is opened when the deposit is removed and closed when the silicon single crystal is manufactured. The output end of the sub valve 42 is connected to the input end of the blower 44 via the exhaust pipe 43. The output end of the blower 44 is connected to one end of the exhaust pipe 45, and the other end of the exhaust pipe 45 is connected to the vicinity of the other end of the exhaust pipe 40. The blower 44 operates when the deposits are removed, sucks the air, inert gas, dust and deposits that have passed through the exhaust pipe 43, and supplies the blower 44 to the scrubber 41 via the exhaust pipe 45 and the exhaust pipe 40.

Since the piping portion 13 is a feature of the first embodiment, an example of its configuration will be described with reference to FIGS. 3 to 5. FIG. 3 is a perspective view showing an example of the configuration of the piping section 13 constituting the semiconductor crystal manufacturing apparatus 1 shown in FIG. 2, FIG. 4 is a plan view showing an example of the configuration of the piping section 13, and FIG. 5 is a configuration of the piping section 13. It is a side view which shows an example. The piping portion 13 is composed of individual exhaust pipes 31A to 31D and a coupling pipe 32. The individual exhaust pipes 31A to 31D and the coupling pipe 32 have substantially a cylindrical shape and have the same inner diameter.

_{The piping portion 13 includes the distance from the exhaust port 24A to the second coupling portion C 21} of the coupling pipe 32 via the individual exhaust pipe 31A, and the second coupling portion of the coupling pipe 32 from the exhaust port 24B via the individual exhaust pipe 31B. and distance to C _21, and the distance to the second coupling part _{C 21} of the coupling tube 32 via a separate exhaust pipe 31C from the exhaust port 24C, the exhaust port 24D from the individual exhaust pipe 31D of the second coupling tube 32 via It is configured so that the distance to the joint portion C _{21 is equal to each other.}

In FIGS. 3 and 5, the individual exhaust pipe 31B is composed of a connecting portion 61B, an upper portion 62B, and a lower portion 63B. The connection portion 61B has a flange and is connected to the exhaust port 24B (see FIG. 2). One end of the upper portion 62B is connected to the connecting portion 61B and extends vertically downward. One end of the lower portion 63B is connected to the other end of the upper portion 62B, extends downward from the reference surface RT1, and the other end constitutes the vicinity of one end 71A of the branch portion 71 constituting the coupling pipe 32 and the individual exhaust pipe 31C. It is connected to the first coupling part C ₁₁ is coupled to the other end of the lower 63C for.

In FIGS. 3 and 5, the individual exhaust pipe 31C is composed of a connecting portion 61C, an upper portion 62C, and a lower portion 63C. The connection portion 61C has a flange and is connected to the exhaust port 24C (see FIG. 2). One end of the upper portion 62C is connected to the connecting portion 61C and extends vertically downward. One end of the lower portion 63C is connected to the other end of the upper portion 62C, extends downward from the reference surface RT1, and the other end constitutes the vicinity of one end 71A of the branch portion 71 constituting the coupling pipe 32 and the individual exhaust pipe 31B. is connected to the first coupling part C ₁₁ is coupled to the other end of the lower 63B to be. As shown in FIG. 5, the individual exhaust pipes 31B and the individual exhaust pipes 31C have a shape symmetrical with respect to the reference surface RT1 and form a substantially V shape centered on the reference surface RT1.

FIG. 3 shows the structure of the piping portion of the present invention in which four individual exhaust pipes 31A to 31D are connected to each of the four exhaust ports. As shown in FIG. 3, the individual exhaust pipe 31A is composed of a connecting portion 61A, an upper portion 62A, and a lower portion 63A. The connection portion 61A has a flange and is connected to the exhaust port 24A (see FIG. 2). One end of the upper portion 62A is connected to the connecting portion 61A and extends vertically downward. One end of the lower portion 63A is connected to the other end of the upper portion 62A, extends downward from the reference surface RT1 (see FIG. 4), and the other end is in the vicinity of one end 72A of the branch portion 72 constituting the coupling pipe 32 and individually. It is coupled to the other end of the lower portion 63D constituting the exhaust pipe 31D and connected to the first coupling portion C ₁₂ .

As shown in FIG. 3, the individual exhaust pipe 31D is composed of a connecting portion 61D, an upper portion 62D, and a lower portion 63D. The connection portion 61D has a flange and is connected to the exhaust port 24D (see FIG. 2). One end of the upper portion 62D is connected to the connecting portion 61D and extends vertically downward. One end of the lower 63D is connected to the other end of the upper 62D, extends downward from the reference surface RT1 (see FIG. 4), and the other end is near one end 72A of the branch portion 72 constituting the coupling pipe 32 and individually. It is coupled to the other end of the lower portion 63A constituting the exhaust pipe 31A and connected to the first coupling portion C ₁₂ . The individual exhaust pipes 31A and the individual exhaust pipes 31D have a shape symmetrical with respect to the reference surface RT1 and form a substantially V shape centered on the reference surface RT1. The combination of the individual exhaust pipes 31B and the individual exhaust pipes 31C and the combination of the individual exhaust pipes 31A and the individual exhaust pipes 31D have a symmetrical shape with respect to the reference plane RT2 (see FIG. 4).

As shown in FIGS. 3 and 4, the coupling tube 32 is composed of a branch portion 71, a branch portion 72, and a base portion 73. _{The branch portion 71 is connected to the first coupling portion C 11} by being coupled to the other end of the lower portion 63B constituting the individual exhaust pipe 31B and the other end of the lower portion 63C constituting the individual exhaust pipe 31C in the vicinity of one end 71A. ing. The branch portion 71 extends diagonally upward toward the reference plane RT2 in FIG. 4 while avoiding interference with the driving means 51, and the other end is connected to the other end of the branch portion 72 and one end of the base portion 73 to form a second branch portion 71. It is connected to the joint portion C _21.

Branch unit 72, one end 72A near connected to the first coupling part _{C 12} is coupled with the other end of the lower 63A constituting the individual exhaust pipes 31A, the other end of the lower 63D constituting the individual exhaust pipes 31D ing. The branch portion 72 extends diagonally downward toward the reference surface RT2 in FIG. 4 while avoiding interference with the driving means 51, and the other end is connected to the other end of the branch portion 71 and one end of the base portion 73 to form a second branch portion 72. It is connected to the joint portion C _21. The other end of the base 73, that is, the end of the coupling tube 32, is connected to the input end of the trap 33 (see FIG. 2). The branch portion 71 and the branch portion 72 have a shape symmetrical with respect to the reference plane RT2. As shown in FIG. 4, the coupling tube 32 has a substantially Y-shape centered on the reference plane RT2. Further, as shown in FIG. 4, the second connecting portion C ₂₁ is located on a plane orthogonal to the reference plane RT2.

As described above, in the first embodiment, in the piping portion 13 composed of the individual exhaust pipes 31A to 31D and the coupling pipe 32, the individual exhaust pipe 31B and the individual exhaust pipe 31C are symmetrical with respect to the reference plane RT1. The individual exhaust pipes 31A and the individual exhaust pipes 31D have a shape symmetrical with respect to the reference plane RT1. Further, the combination of the individual exhaust pipes 31B and the individual exhaust pipes 31C and the combination of the individual exhaust pipes 31A and the individual exhaust pipes 31D have a shape symmetrical with respect to the reference plane RT2. Further, the coupling tube 32 has a shape symmetrical with respect to the reference plane RT2.

_{Therefore, the piping portion 13 has the distance from the exhaust port 24A to the second coupling portion C 21} of the coupling pipe 32 via the individual exhaust pipe 31A and the second coupling pipe 32 from the exhaust port 24B via the individual exhaust pipe 31B. The distance to the coupling portion C ₂₁ and the distance from the exhaust port 24C to the second coupling portion C ₂₁ of the coupling pipe 32 via the individual exhaust pipe 31C, and the distance from the exhaust port 24D via the individual exhaust pipe 31D to the second coupling pipe 32. The distances of 2 to the connecting portion C ₂₁ are all equal. Moreover, the individual exhaust pipes 31A to 31D and the coupling pipe 32 have substantially a cylindrical shape and have the same inner diameter.

Therefore, when the main pump 39 is operated during the production of the silicon single crystal, the exhaust speeds in the individual exhaust pipes 31A to 31D are substantially the same. As a result, for example, in the joint portion C ₂₁ of the coupling pipe 32, the gas flow of the inert gas is hardly disturbed, so that the problems shown in (1) to (3) above may occur in Patent Document 1. It is less than the described prior art.

Further, in the first embodiment, the individual exhaust pipes 31B and the individual exhaust pipes 31C are combined, and after the individual exhaust pipes 31A and the individual exhaust pipes 31D are combined, each combination is connected to the coupling pipe 32. Therefore, the exhaust speed in each of the individual exhaust pipes 31A to 31D can be made uniform in the shortest distance while avoiding interference with the drive means 51. Further, since the individual exhaust pipes 31A to 31D and the coupling pipe 32 all have symmetrical shapes, there is an advantage that they are easy to manufacture.

Embodiment 2.
In the first embodiment, the exhaust ports 24A to 24D form the bottom of the chamber 21 shown in FIG. 2 and are formed on a base plate (not shown) mounted on the floor FC, respectively. Not limited to this. The present invention can also be applied to, for example, the semiconductor crystal manufacturing apparatus 2 shown in FIGS. 6 and 7. FIG. 6 is a conceptual diagram showing an example of the configuration of the semiconductor crystal manufacturing apparatus 2 according to the second embodiment of the present invention, and FIG. 7 is a cross-sectional view showing an example of the structure of the exhaust passage of the semiconductor crystal manufacturing apparatus 2. In FIGS. 6 and 7, the parts corresponding to the parts of FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

This semiconductor crystal manufacturing apparatus 2 is a suitable apparatus for use, for example, when adding an n-type dopant to a silicon melt. In the semiconductor crystal manufacturing apparatus 2, heaters 81 for heating the silicon melt M are arranged outside the crucible 25 composed of the graphite crucible 25A and the quartz crucible 25B at a predetermined interval, and at a predetermined interval outside the heater 81. A substantially cylindrical heat insulating cylinder 82 made of a heat insulating material is arranged so as to be separated from the heat insulating material. A substantially cylindrical inner cylinder 83 is arranged between the heater 81 and the heat insulating cylinder 82. The inner cylinder 83 is made of a carbon member (for example, graphite).

^{On the outer circumference of the inner cylinder 83, there are 2 n} (n is an integer of 2 or more) exhaust ducts 84 composed of long members having a substantially U-shaped cross section, and in the second embodiment, n = 2, that is, Four exhaust ducts 84 are joined. The four exhaust ducts 84 are arranged at four locations on the outer circumference of the inner cylinder 83 so that adjacent ones form an angle of approximately 90 ° with the central axis of the crucible 25 as the center. Each exhaust duct 84 has the same shape and the same dimensions.

The base plate 21A forming the bottom of the chamber 21 has 2 ⁿ exhaust ports 85 at locations corresponding to the four exhaust ducts 84, and in the second embodiment, n = 2, that is, four exhaust ports. 85A to 85D are formed respectively. The lower ends of the corresponding exhaust ducts 84 are connected to the exhaust ports 85A to 85D, respectively, introduced into the chamber 21, and the inert gas that has passed through the exhaust duct 84 is exhausted to the outside. In FIG. 6, only the exhaust ports 85A and 85B are shown.

As shown in FIG. 6, the upper exhaust port 83A is located above the upper end of the heater 81, and the lower exhaust port 83B is located below the lower end of the heater 81 at four locations of the inner cylinder 83 to which the four exhaust ducts 84 are joined. It is formed.

In the chamber 21, a heat insulating plate 86 extending inward is provided at the upper end of the heat insulating cylinder 82. A radiant shield 87 is provided at the inner peripheral end of the heat insulating plate 86 to prevent the growing silicon single crystal SM from being subjected to extra radiant heat from the heater 81 or the like.

The radiation shield 87 has an upper portion and a lower portion formed so as to surround the periphery of the silicon single crystal SM above and near the crucible 25, and a tapered surface so that the area of the opening gradually decreases from the upper portion to the lower portion. Is formed. By providing the radiation shield 87, the inert gas supplied into the crucible 25 from above flows through the gap between the radiation shield 87 and the silicon melt M, and is exhausted to the outside of the crucible 25.

The four exhaust ports 85A to 85D are connected to a piping portion having a structure similar to that of the piping portion 13 shown in FIGS. 3 to 5. However, since the cross-sectional shape of the exhaust duct 84 is substantially U-shaped, for example, the cross-sectional shapes of the exhaust ports 85A to 85D are formed to be substantially rectangular, and the individual exhaust pipes 31A to 31D are respectively configured. The shape of the flange of the connecting portions 61A to 61D needs to be a shape that can be closely connected to the exhaust ports 85A to 85D.

With this configuration, the same effect as that of the first embodiment can be obtained. Further, in the second embodiment, even if the deposits adhering to the vicinity of the upper exhaust port 83A of the inner cylinder 83 are peeled off by the gas flow flowing back in the exhaust duct 84 for some reason, the inside of the silicon melt M It can be prevented from being mixed in. Therefore, even when the n-type dopant is added to the silicon melt M, it is possible to prevent the concentration of the n-type dopant in the silicon melt M from increasing, and the desired properties (for example, for example) of the silicon single crystal can be prevented. , Resistivity) can be imparted.

The semiconductor crystal manufacturing apparatus according to the present invention will be further described based on examples. In this example, the effect was verified by actually conducting an experiment using the semiconductor crystal manufacturing apparatus having the configuration shown in the first embodiment.

(Comparative Examples 1 to 3)
The configuration of the piping portion of Comparative Examples 1 to 3 for comparison with the embodiment is substantially the same as the piping configuration described in Patent Document 1 instead of the piping portion 13 shown in the first embodiment. The configurations shown in 8 and 9 were adopted. The other configurations are the same as the configurations shown in the first embodiment. FIG. 8 is a plan view showing an example of the configuration of the piping portion 91 as a comparative example, and FIG. 9 is a side view showing an example of the configuration of the piping portion 91.

The piping portion 91 is composed of four individual exhaust pipes 92A to 92D and a coupling pipe 93. The individual exhaust pipe 92B has a substantially cylindrical shape, has a flange at one end, is connected to the exhaust port 24B (see FIG. 2), and extends vertically downward. The other end of the individual exhaust pipe 92B is connected to one end of the branch portion 94 constituting the coupling pipe 93.

The individual exhaust pipe 92C has a substantially cylindrical shape, has a flange at one end, is connected to the exhaust port 24C (see FIG. 2), and extends vertically downward. The other end of the individual exhaust pipe 92C is connected to the vicinity of the other end of the branch portion 94 constituting the coupling pipe 93.

The individual exhaust pipe 92A has a substantially cylindrical shape, has a flange at one end, is connected to the exhaust port 24A (see FIG. 2), and extends vertically downward. The other end of the individual exhaust pipe 92A is connected to one end of the branch portion 95 constituting the coupling pipe 93.

The individual exhaust pipe 92D has a substantially cylindrical shape, has a flange at one end, is connected to the exhaust port 24D (see FIG. 2), and extends vertically downward. The other end of the individual exhaust pipe 92D is connected to the vicinity of the other end of the branch portion 95 constituting the coupling pipe 93.

The branches 94 and 95 have a substantially cylindrical shape and extend in the horizontal direction. The other end of the branch portion 94 and the other end of the branch portion 95 are connected to both ends of the beam portion 96A constituting the base portion 96 having a substantially T-shape in a plan view. One end of the column portion 96B is connected to substantially the center of the beam portion 96A constituting the base portion 96 and extends in the horizontal direction. The other end of the pillar portion 96B is connected to the input end of the trap 33 shown in FIG. The individual exhaust pipes 92A to 92D and the coupling pipe 93 have substantially a cylindrical shape and have the same inner diameter.

Taking the semiconductor crystal manufacturing apparatus adopting the piping portion 13 according to the first embodiment as an example, three semiconductor crystal manufacturing apparatus adopting the piping portion 91 having the structures shown in FIGS. 8 and 9 are compared with Comparative Examples 1 to 1. It was set to 3. Table 1 shows the measurement results of the exhaust air velocity. In the examples of Table 1, 31A to 31C show individual exhaust pipes 31A to 31C shown in FIGS. 3 to 5. Similarly, in Comparative Examples 1 to 3 in Table 1, 92A to 92C indicate individual exhaust pipes 92A to 92C shown in FIGS. 8 and 9.

In Table 1, the values of the individual exhaust pipes 31A and 31B and the individual exhaust pipes 92A and 92B are 1.00, based on the exhaust wind speed values in these, the individual exhaust pipes 31D and 31C combined with them and the individual exhaust pipes 31D and 31C. This is to indicate the ratio of the exhaust wind speed values in the exhaust pipes 92D and 92C.

Table 1 also shows the standard deviations of the exhaust wind speed measurement value ratios of the individual exhaust pipes 31A to 31C in Examples and the standard deviations of the exhaust wind speed measurement value ratios of the individual exhaust pipes 92A to 92C in Comparative Examples 1 to 3. There is. The standard deviation is one of the numerical values representing the variation of data and random variables. Therefore, in the individual exhaust pipes constituting the semiconductor crystal manufacturing apparatus, the smaller the standard deviation, the more uniformly the inert gas or the like is exhausted, and the larger the standard deviation, the more unevenly the inert gas or the like is exhausted.

In the individual exhaust pipes 31A to 31D and the individual exhaust pipes 92A to 92D, the inner diameter of the exhaust pipe at the measurement location where the exhaust air velocity is measured is the same. Therefore, the exhaust air velocity measured value ratio shown in Table 1 is synonymous with the displacement ratio and can be read as.

In Table 1, in Comparative Examples 1 to 3, the exhaust air velocity values in the individual exhaust pipes 92D and 92C are increased by about 30%, whereas in the examples, the exhaust air velocity values are uniform in all the individual exhaust pipes 31A to 31D. It shows that there is. Therefore, according to the embodiment, the gas flow (wind speed) becomes smooth in all of the individual exhaust pipes 31A to 31D, and the rate at which defects do not occur in the produced silicon single crystal (free rate) is improved. To do.

As described above, in Comparative Examples 1 to 3 in Table 1, the exhaust air velocity values in the individual exhaust pipes 92D and 92C are about 30% higher than the exhaust air velocity values in the paired individual exhaust pipes 92A and 92C. There is. In the paired individual exhaust pipes 92A and 92D, the distance from each one end to the other end of the base 96 is shorter in the individual exhaust pipe 92D than in the individual exhaust pipe 92A. In the paired individual exhaust pipes 92B and 92C, the distance from each one end to the other end of the base 96 is shorter in the individual exhaust pipe 92C than in the individual exhaust pipe 92B. From this, it can be said that the exhaust air velocity value is almost inversely proportional to the length of the exhaust pipe.

In Table 1, the standard deviation of the exhaust air velocity of the example is 0.02, whereas the standard deviation of the exhaust air velocity of the comparative example 3 is 0.13. From this, for example, in consideration of the safety factor, if the standard deviation of the exhaust air velocity is within ± 8%, it is considered that the turbulence of the gas flow is unlikely to occur. As described above, it can be said that the exhaust air velocity value is substantially inversely proportional to the length of the exhaust pipe. Therefore, if the variation (standard deviation) in the length of the exhaust pipe is within ± 8%, the inert gas or the like is uniformly exhausted, and it is considered that the turbulence of the gas flow is unlikely to occur. Quantitatively speaking, the "substantially equal" in claims 1, 3 and 4 can be said to have a variation in "distance" within ± 8%.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design changes, etc. within the range not deviating from the gist of the present invention, etc. Even if there is, it is included in the present invention.
For example, in each of the above embodiments, an example in which the semiconductor crystal is a silicon single crystal is shown, but the present invention is not limited thereto. The semiconductor crystal may be any of silicon polycrystal, GAAs single crystal, GAAs polycrystal, InP single crystal, InP polycrystal, ZnS single crystal, ZnS polycrystal, ZnSe single crystal, and ZnSe polycrystal. Further, in each of the above-described embodiments, an example in which the present invention is applied to the case of producing a semiconductor crystal by using the CZ method has been shown, but the present invention is not limited to this, and the present invention uses the FZ method to obtain a semiconductor crystal. Of course, it can also be applied when manufacturing.

1,2 ... Semiconductor crystal manufacturing equipment, 11 ... Semiconductor crystal manufacturing part, 12 ... Gas exhaust part, 13 ... Piping part, 21 ... Chamber, 21A ... Base plate, 22 ... Single crystal pulling part, 23 ... Gas introduction part, 24, 24A to 24D, 85, 85A to 85D ... Exhaust port, 25 ... Crucible, 25A ... Graphite crucible, 25B ... Quartz crucible, 31, 31A to 31D ... Individual exhaust pipe, 32 ... Combined pipe, 33 ... Trap, 34 to 36, 38, 40, 43, 45 ... Exhaust pipe, 37 ... Main valve, 39 ... Main pump, 41 ... Crucible, 42 ... Sub valve, 44 ... Blower, 51 ... Drive means, 61A to 61D ... Connection, 62A to 62D ... Upper , 63A-63D ... Lower part, 71,72 ... Branch part, 71A, 72A ... One end, 73 ... Base part, 81 ... Heater, 82 ... Heat insulation cylinder, 83 ... Inner cylinder, 83A ... Upper exhaust port, 83B ... Lower exhaust port, 84 ... Exhaust duct, 86 ... Heat insulation plate, 87 ... Radiation shield, B _{11 to} B ₁₄ , B ₂₁ , B ₂₂ ... Branch, C _{11 to} C ₁₄ ... First joint, C ₂₁ , C ₂₂ ... Second Crucible, C ₃₁ ... 3rd joint, CP ₁₁ , CP ₁₂ ... 1st joint, CP ₂₁ ... 2nd joint, CP ₃₁ ... 3rd joint, CR ... Clean room, EH ₁ ~ EH ₈ ... Exhaust port, EP _{1 to EP 8} ... Individual exhaust pipe, FC, FP ... Floor, M ... Silicon melt, PR ... Pump chamber, RT1, RT2 ... Reference plane, SM ... Silicon single crystal.

Claims (6)

The first, second, third, and fourth exhaust ports for exhausting the gas introduced into the chamber for manufacturing the semiconductor crystal, and
The first, second, third and fourth individual exhaust pipes, each end of which is connected to the corresponding first to fourth exhaust ports, respectively.
A first coupling portion to which the other ends of the pair of adjacent first and second individual exhaust pipes are coupled and connected,
A second coupling portion to which the other ends of the pair of adjacent third and fourth individual exhaust pipes are coupled and connected,
The first and second branch portions have a first branch portion whose one end is connected to the first joint portion and a second branch portion whose one end is connected to the second joint portion. Each other end of the joint is provided with a connecting pipe to be connected to the third joint portion.
A semiconductor crystal manufacturing characterized in that the distances from each of the first to fourth exhaust ports to the third joint portion via the corresponding first to fourth individual exhaust pipes are substantially the same. apparatus. The first to fourth exhaust ports are provided at positions symmetrical with respect to the central axis of the driving means for raising and lowering the crucible provided in the chamber while rotating.
The pair of the first and second individual exhaust pipes have a shape symmetrical with respect to the first reference plane passing through the central axis.
The pair of the third and fourth individual exhaust pipes has a shape symmetrical with respect to the first reference plane.
The pair of the first and second individual exhaust pipes and the pair of the third and fourth individual exhaust pipes pass through the central axis and are different from the first reference surface. The semiconductor crystal manufacturing apparatus according to claim 1, wherein the semiconductor crystal manufacturing apparatus is provided at a position symmetrical with respect to the relative. ^{2 n} (n is an integer of 2 or more) exhaust ports for exhausting the gas introduced into the chamber for manufacturing the semiconductor crystal, and
The individual exhaust pipes of the 2 ⁿ the each end of which is connected to each of said exhaust ports corresponding,
^{2 n-1} first coupling portions to which the other ends of the pair of adjacent individual exhaust pipes are coupled and connected,
2 ^n-k-1 {k is a positive integer that increases by 1 from 1 to (n-1)}
It has a pair of branches, each end of the branch is connected to a pair of adjacent k-th joints, and the other ends of the branch are joined to correspond to the corresponding (k + 1) th joint. It is provided with a 2 ^{n-k-1 k-th} coupling tube connected to the coupling portion.
A semiconductor crystal manufacturing apparatus, characterized in that the distances from each of the exhaust ports to the nth coupling portion via the corresponding individual exhaust pipes are substantially the same. Chambers for manufacturing semiconductor crystals and
The crucible provided in the chamber and
A heater arranged so as to surround the crucible and heating the crucible,
The formed gas introduced into the chamber at the bottom of the upper outlet and the corresponding upper exhaust port for exhausting from the top of the heater, 2 with any communication of the lower exhaust port for exhausting from the lower portion of the heater ⁿ ( n is an integer of 2 or more) With two exhaust ducts,
^{Two n} exhaust ports formed at the bottom of the chamber and connected to the lower end of each corresponding exhaust duct.
The individual exhaust pipes of the 2 ⁿ the each end of which is connected to each of said exhaust ports corresponding,
^{2 n-1} first coupling portions to which the other ends of the pair of adjacent individual exhaust pipes are coupled and connected,
2 ^n-k-1 {k is a positive integer that increases by 1 from 1 to (n-1)}
It has a pair of branches, each end of the branch is connected to a pair of adjacent k-th joints, and the other ends of the branch are joined to correspond to the corresponding (k + 1) th joint. It is provided with a 2 ^{n-k-1 k-th} coupling tube connected to the coupling portion.
A semiconductor crystal manufacturing apparatus, characterized in that the distances from the upper end of each of the exhaust ducts to the nth coupling portion via the corresponding individual exhaust pipes are substantially the same. The ²ⁿ exhaust ports are provided at positions symmetrical with respect to the central axis of the driving means for raising and lowering the crucible provided in the chamber while rotating.
The two adjacent individual exhaust pipes have a shape symmetrical with respect to the reference plane passing through the central axis, and the other two adjacent individual exhaust pipes pass through the central axis. The semiconductor crystal manufacturing apparatus according to claim 3 or 4, wherein the semiconductor crystal manufacturing apparatus is provided at a position symmetrical with respect to a reference plane different from the reference plane. The semiconductor crystal manufacturing apparatus according to any one of claims 1 to 5, wherein a silicon single crystal to which an n-type dopant is added is manufactured.

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