TWI715122B - Purge tubes, single crystal pulling devices and methods for manufacturing a silicon single crystal - Google Patents

Abstract

The present disclosure provides a purge tube that can inspect the growth condition of a silicon single crystal. The purge tube 5 includes a cylinder part 51 with cylinder-shaped, which leads inert gas, introduced from an exterior of a chamber 21, to a silicon melt M side. The purge tube 5 also includes a collar part 52 with collar-shaped, which protrudes from a peripheral surface of the cylinder part 51 to outside. A penetrating part 522 is disposed on at least a portion of the collar part 52, inspecting the growth condition of the silicon single crystal SM through an optical inspection tool 3 disposed on the exterior of the chamber 21.

Description

Purge tube, single crystal pulling device, and manufacturing method of silicon single crystal

The invention relates to a gas purging tube, a single crystal pulling device and a manufacturing method of a silicon single crystal.

Previously, in the manufacture of silicon single crystals, imaging means outside the chamber was used to image the inside, and the conditions for the generation of silicon single crystals were controlled according to the generation conditions of the silicon single crystals (for example, refer to Patent Document 1).

The single crystal pulling device described in Patent Document 1 includes a purge tube made of quartz. The purging pipe has a transparent inspection window. With this viewing window, the CCD camera becomes able to image the formation of silicon single crystals. [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2011-246341

[The problem to be solved by the invention]

However, in the structure of Patent Document 1, since the surface of the inspection window is parallel to the plumb line (a straight line extending in the direction of gravity), the incident angle of the optical axis of the CCD camera becomes larger with respect to the surface of the inspection window. Therefore, the CCD camera images the reflected image on the surface of the inspection window, and there are cases where it cannot properly image the formation of the silicon single crystal.

The object of the present invention is to provide a purge tube, a single crystal pulling device, and a method for manufacturing a silicon single crystal, which can appropriately grasp the generation status of the silicon single crystal from the outside of the chamber. [Means to solve the problem]

The purging pipe of the present invention is a purging pipe installed in a chamber of a single crystal pulling device, and is characterized by including a cylindrical portion formed in a cylindrical shape, and guiding the inert gas introduced from the outside of the chamber to the silicon melt Liquid side; flange part, from the outer peripheral surface of the cylindrical part protruding outward into a flange shape; wherein at least a part of the flange part is provided with a penetrating part, which is provided by optical observation means provided outside the chamber , And can observe the formation of silicon single crystal.

As an optical observation method to observe the formation of silicon single crystals, the interface between the silicon single crystal and the liquid surface of the silicon melt can be exemplified by the presence of a circular meniscus (meniscus). The distance from the liquid level of the melt to the lower end of the heat shield (hereinafter, sometimes referred to as "gap"), etc. According to the present invention, the purge tube is installed on the single crystal pulling device by making the central axis of the cylindrical part parallel to the vertical line, so that the optical axis of the optical observation means can be made relative to the upper surface of the penetrating part. The incident angle is smaller than the structure of Patent Document 1 (hereinafter referred to as the “previous structure”). Therefore, it is possible to suppress the reflection component on the upper surface of the penetrating portion from being observed by the optical observation means, and it is possible to appropriately grasp the generation status of the silicon single crystal by the optical observation means.

In the case that the formation of silicon single crystals cannot be properly grasped, there may be problems such as the inability to precisely control the gaps in the production of silicon single crystals, the inability to precisely control the diameter of the silicon single crystals in production, and the inability Precisely control the pulling speed closely related to the diameter control of the silicon single crystal. Since the present invention can properly grasp the formation status of silicon single crystals, it can precisely control the gap, precisely control the diameter of the silicon single crystal, or precisely control the pulling speed, or appropriately manufacture silicon for semiconductors as described above. Single crystal.

In the purge tube of the present invention, the penetration portion is preferably formed so that the incident angle of the optical axis of the optical observation means with respect to the upper surface of the penetration portion is 45° or less.

When the incident angle is 45° or less, in the side view angle, the angle formed by the outer peripheral surface of the cylindrical portion and the upper surface of the penetrating portion includes both the case where it becomes an acute angle and the case where it becomes an obtuse angle. According to the present invention, it is possible to suppress the reflection component on the upper surface of the penetrating portion from being observed by optical observation means. In addition, the above-mentioned incident angle is preferably formed to be 22.5° or less.

In the purging pipe of the present invention, the penetration portion is preferably formed so that the incident angle becomes 0°.

When the incident angle is 0°, in addition to 0°, it also includes the range of -5° to 5°. According to the present invention, it is possible to prevent the reflection component located on the upper surface of the penetrating portion from being observed by optical observation means.

In the purging pipe of the present invention, the penetration portion is preferably formed of flat-plate quartz with a uniform thickness.

According to the present invention, the distortion of the observation result during two-dimensional observation can be suppressed, and the generation status of the silicon single crystal can be grasped more appropriately by optical observation means.

According to the present invention, the flange portion is preferably formed in the shape of an annular plate extending in a direction orthogonal to the central axis of the cylindrical portion. In particular, the flange portion is preferably formed so that the thickness becomes uniform.

According to the present invention, by making the flange part into a simple shape, the flange part can be easily manufactured.

In the purging pipe of the present invention, the outer diameter of the flange portion is preferably larger than the inner diameter of the lower end of the cylindrical or truncated cylindrical heat shield provided in the chamber.

According to the present invention, the purge pipe can be easily installed by making the collar part only directly contact the heat shield.

In the purging pipe of the present invention, the cylindrical portion is preferably formed of graphite.

According to the present invention, the weight reduction and cost reduction of the purge pipe can be achieved.

The single crystal pulling device of the present invention is characterized by comprising: a crucible containing silicon melt; a pulling part for generating silicon single crystals by contacting a seed crystal to the silicon melt and then pulling it; A cylindrical heat shielding body is arranged to enclose the silicon single crystal above the crucible; the purging pipe; a chamber that houses the crucible, the heat shielding body, and the purging pipe; a gas introduction part An inert gas is introduced from the outside of the chamber to the inside of the chamber; and an optical observation means is provided outside the chamber, and observes the generation condition of the silicon single crystal through the penetration part of the purge tube.

In the single crystal pulling device of the present invention, it is preferable to provide a purge tube support portion that supports the purge tube from below on the inner peripheral surface of the heat shield. In particular, it is preferable to support the flange portion of the purging pipe from below.

According to the present invention, the purge pipe can be easily positioned. In particular, if the collar is supported from below, the purging pipe will not be inclined and will be stable.

The method of manufacturing a silicon single crystal of the present invention is a method of manufacturing a silicon single crystal using the above-mentioned single crystal pulling device, and is characterized in that the production conditions of the above-mentioned silicon single crystal are controlled based on the observation result of the above-mentioned optical observation means.

[First Embodiment] Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.

〔Related Technology〕 First, the general structure of the single crystal pulling device is explained. As shown in FIG. 1, the single crystal pulling device 1 is an apparatus used for the CZ method (Czochralski method), and includes a pulling device main body 2, an optical observation means 3, and a control unit 4. The lifting device body 2 includes a chamber 21, a crucible 22 arranged in the chamber 21, a heater 23 that heats the crucible 22, a pulling part 24, a heat shield 25, and a crucible provided on the inner wall of the chamber 21 The heat insulating material 26 and the crucible driving part 27. In addition, as shown by the two-dot chain line, the single crystal pulling device 1 is a device used for the MCZ (Magnetic field applied Czochralski) method, and it may also have: a crucible 22 located outside the chamber 21 is clamped and arranged. A pair of electromagnetic coils 28.

The chamber 21 includes a main chamber 211 and a pulling chamber 213 connected to an upper portion of the main chamber 211 via a gate valve 212. The main chamber 211 has an upper surface formed in a formed shape, and includes a main body 211A in which the crucible 22, heater 23, heat shield 25, etc. are arranged, and a cover 211B that seals the upper surface of the main body 211A. The lid 211B is provided with an opening 211C for introducing an inert gas such as Ar gas into the main chamber 211 and a quartz window 211D for the optical observation means 3 to observe the inside of the chamber 21. A support portion 211E extending inward is provided between the body portion 211A and the cover portion 211B. The pulling chamber 213 is provided with a gas introduction port 21A for introducing an inert gas such as Ar gas into the main chamber 211. A gas exhaust port 21B for discharging the gas in the main chamber 211 is provided in the lower part of the main body 211A of the main chamber 211.

The crucible 22 includes a quartz crucible 221 and a graphite crucible 222 that houses the quartz crucible 221. The heater 23 is arranged around the crucible 22 and melts the silicon in the crucible 22. The pulling unit 24 includes a cable 241 provided at one end of the seed crystal SC, and a pulling drive unit 242 that lifts and rotates the cable 241.

The heat shield 25 is provided to surround the silicon single crystal SM, and blocks the radiant heat radiated upward from the heater 23. The heat shielding body 25 includes a truncated cone-shaped heat shielding body main body 251 formed with a diameter decreasing downward, and a supported portion 252 extending outward in a flange shape from the upper end of the heat shielding body main body 251. As shown in FIG. 2, the heat shield main body 251 is provided with a purge tube support portion 251A that continuously protrudes from the inner peripheral surface in the circumferential direction. The heat shield 25 is fixed above the crucible 22 by the supported part 252 being fixed to the supporting part 211E. The crucible driving unit 27 includes a support shaft 271 that supports the graphite crucible 222 from below, and rotates and moves the crucible 22 at a predetermined speed.

The optical observation means 3 observes the generation status of the meniscus existing on the liquid surface of the silicon melt M, or the generation status of the silicon single crystal SM such as the gap G. The optical observation means 3 includes imaging means 31 and calculation means 32. The imaging means 31 is, for example, a two-dimensional CCD camera, and the liquid surface of the silicon melt M is imaged from the outside of the chamber 21 via the window 211D. The calculation means 32 calculates the generation status of the silicon single crystal SM based on the imaging result of the imaging means 31.

The control unit 4 manufactures the silicon single crystal SM based on various information stored in the memory 41, an operator's operation, and the like. As the information stored in the memory 41, the gas flow rate or furnace pressure in the chamber 21, the power input to the heater 23, the number of revolutions of the crucible 22 or the silicon single crystal SM, etc. can be exemplified.

〔The structure of the purging pipe〕 Next, the structure of the purge tube provided in the single crystal pulling device 1 will be described. As shown in FIGS. 3(A) to (C), the purging pipe 5 includes a cylindrical portion 51 having a cylindrical shape, and a flange portion 52 that protrudes outward from the lower end of the cylindrical portion 51 in a flange shape.

The diameter of the flange part 52 becomes larger toward the downward direction, and it is formed in the shape of a truncated cone tube. The flange part 52 includes a flange body part 521 and a penetrating part 522. In the upper viewing angle, a part of the truncated cone cylindrical shape with a uniform thickness is cut away, so the flange body 521 is formed in a roughly C-shape. That is, the upper surface 521A of the flange body portion 521 becomes a curved surface. The penetration portion 522 is formed in a flat plate shape with a uniform thickness. That is, the upper surface 522A of the penetration portion 522 becomes a flat surface. The penetrating part 522 is provided by embedding the cutout part of the flange body part 521. In the side viewing angle, the angle of the outer circumferential surface of the upper surface 51A and 522A of the cylindrical portion 51 formed at an obtuse angle θ ₁ in a manner penetrating portion 522 is provided. As shown in FIG. 2, the penetration portion 522 is such that the incident angle of the optical axis P of the imaging means 31 with respect to the upper surface 522A (the angle of the optical axis P with respect to the normal line N of the upper surface 522A) becomes 45° or less Set up. In the first embodiment, the incident angle is 0°, that is, the angle θ ₂ formed by the upper surface 522A and the optical axis P is set to be 90°.

The cylindrical portion 51, the flange body portion 521, and the penetrating portion 522 are individually formed of transparent quartz. The above elements are welded so that the central axis of the cylindrical portion 51 and the central axis of the flange body 521 are aligned. Integration. In the upper viewing angle, the outer shape of the flange portion 52 is circular, and its outer diameter is larger than the inner diameter of the lower end opening of the heat shield 25. The silicon single crystal SM passes through the inside of the cylindrical portion 51 and is pulled upward.

[Structure of single crystal pulling device with purging pipe] As shown in Figs. 1 and 3, the purging pipe 5 is supported from below by the purging pipe support portion 251A protruding from the inner peripheral surface of the heat shield body 251 52, the distance M by the liquid surface of the molten silicon to penetrate portion 522 of L ₁ so as to be positioned manner. By determining this distance L ₁ , the position of the lower end of the penetrating portion 522 becomes higher than the position of the upper end of the discoloration area A of the purge tube 9 in the embodiment described later. In addition, the purge pipe 5 is positioned so that the central axis of the cylindrical portion 51 coincides with the central axis of the heat shield 25, and the central axis of the cylindrical portion 51 and the vertical line V are parallel.

A pull tube 29 may also be provided in the body 2 of the lifting device. The pull tube 29 may be formed in a cylindrical shape by metal having an inner diameter larger than the outer diameter of the cylindrical portion 51 of the purging tube 5, for example. By fixing the outer peripheral surface of the pull tube 29 to the inner peripheral surface of the opening portion 211C of the lid portion 211B, the lower end of the pull tube 29 can be located inside the heat shield 25 and the upper end portion of the flange portion 52 can be located inside. And set. In addition, in this embodiment, the purge tube 5 and the pull tube 29 may not be in contact, or both may be in contact.

〔Method of manufacturing silicon single crystal〕 Next, the manufacturing method of the silicon single crystal SM using the single crystal pulling device 1 will be described. In addition, with this manufacturing method, it is also possible to manufacture silicon single crystal SM such as 200mm, 300mm, 450mm, etc. which can obtain silicon wafers.

First, the control unit 4 of the single crystal pulling device 1 sets: the quality required in the silicon single crystal SM, such as resistance; the flow rate of inert gas to satisfy the pulling condition of oxygen concentration; the pressure inside the chamber 21; the crucible 22 Or the number of revolutions of the silicon single crystal SM; the heating conditions of the heater 23, etc. In addition, this setting condition may be input by the operator, or may be calculated by the control unit 4 based on the target oxygen concentration input by the operator.

Next, the control unit 4 heats the crucible 22 to melt the polysilicon material (silicon raw material) in the crucible 22 to generate the silicon melt M. In addition, the silicon melt M may also contain dopants for the resistance adjustment of the silicon single crystal SM. After that, the controller 4 introduces a predetermined flow rate of inert gas into the chamber 21 through the gas inlet 21A, and reduces the pressure in the chamber 21 to maintain the inert gas environment in the chamber 21 under reduced pressure. After that, the control unit 4 immerses the seed crystal SC in the silicon melt M, and while rotating the crucible 22 and the cable 241 in a predetermined direction, pulls the cable 241 to generate the silicon single crystal SM.

In the formation of the silicon single crystal SM, the silicon in the silicon melt M evaporates and reacts with oxygen to form SiO. If the SiO adheres to the inner wall of the lid portion 211B of the main chamber 211 and aggregates, the aggregate will fall into the silicon melt M through the inside of the heat shield 25, and the silicon single crystal SM may be polycrystallized . However, in this embodiment, since the entire periphery of the outer edge of the truncated cone-shaped collar portion 52 is in contact with the inner peripheral surface of the heat shielding body 25, even if aggregates fall into the heat shielding body 25, the collar portion 52 It can prevent the aggregates from reaching the silicon melt M.

In addition, in the formation of the silicon single crystal SM, the optical observation means 3 uses the imaging means 31 to image the image of the silicon melt M or the silicon single crystal SM that has penetrated the penetrating portion 522. According to the imaging result, The calculation means 32 obtains the formation status of the silicon single crystal SM. Then, the control unit 4 controls the production conditions such as the diameter of the silicon single crystal SM or the gap G in order to produce the desired silicon single crystal SM based on the production status obtained by the optical observation means 3.

[Effects of the first embodiment] According to the first embodiment, the following effects can be achieved. (1) The purge tube 5 composed of the cylindrical portion 51 and the flange portion 52 is positioned in the chamber 21 such that the central axis of the cylindrical portion 51 is parallel to the vertical line V. Therefore, the incident angle of the optical axis P of the imaging means 31 with respect to the upper surface 522A of the penetrating portion 522 can be made smaller than the previous configuration. As a result, it is possible to suppress imaging of the reflection component on the upper surface 522A of the penetrating portion 522 by the imaging means 31, and it is possible to appropriately grasp the generation status of the silicon single crystal SM from the outside of the chamber 21.

(2) In particular, since the penetration portion 522 is configured such that the incident angle of the optical axis P with respect to the upper surface 522A is 0°, it is possible to prevent the imaging means 31 from imaging the reflection component on the upper surface 522A. (3) In addition, since the thickness of the flat penetrating portion 522 is uniform, it is possible to suppress distortion of the observation result in two-dimensional observation. With the effects of (2) and (3), the imaging means 31 can image the actual conditions of the silicon melt M or the silicon single crystal SM into a substantially correct and clear image. In particular, the image of the interface between the silicon melt M and the silicon single crystal SM and the surrounding area can be clearly imaged. As a result, the generation status of the silicon single crystal SM can be accurately grasped from the outside of the chamber 21. Then, it is possible to precisely control the diameter and the gap G of the silicon single crystal SM according to the grasped generation status. That is, by using a clear image, it is possible to accurately grasp the offset relative to the target diameter or the offset relative to the target gap G, thereby making it possible to control the offset in such a way that the offset disappears.

(4) Since the outer diameter of the flange portion 52 is larger than the inner diameter of the lower end opening of the heat shielding body 25, the purge pipe 5 can be easily installed by making the flange portion 52 only directly contact the heat shielding body 25.

(5) Since the pipe 5 is driven away from the liquid surface of the silicon melt M to the penetration portion 522 of L ₁ becomes positioned manner, the penetration portion 522 can be suppressed due to radiant heat from the silicon melt M discolored. Because this discoloration is caused by the adhesion of silicon oxide (SiOx) to the penetration part 522, although it can be removed by acid cleaning such as hydrofluoric acid, the manufacturing cost increases due to the removal cost. In the above-mentioned embodiment, since the discoloration of the penetration portion 522 can be suppressed, the increase in cost can be suppressed.

[Second Embodiment] Next, the second embodiment of the present invention will be described with reference to the drawings. In addition, the same reference numerals are given to the same structures as those of the first embodiment, and the descriptions are omitted or simplified.

〔The structure of the purging pipe〕 First, the structure of the purging pipe will be explained. As shown in FIGS. 4(A) to (B), the purge pipe 7 includes a cylindrical portion 71 having a cylindrical shape, and a flange portion 72 that protrudes outward from the lower end of the cylindrical portion 71 in a flange shape. As shown in FIG. 5, the outer diameter of the flange portion 72 is characterized by being larger than the inner diameter of the lower end opening of the heat shielding body 25, and also larger than the inner diameter of the upper end opening of the heat shielding body 25.

The cylindrical portion 71 is formed of graphite. The flange 72 is formed of transparent quartz. The flange portion 72 extends in a direction orthogonal to the central axis of the cylindrical portion 71 and is formed in an annular plate shape with a uniform thickness. The outer diameter of the flange 72 is larger than the inner diameter of the lower end opening of the heat shielding body 25 and also larger than the inner diameter of the upper end opening of the heat shielding body 25. When the purge tube 7 is provided in the chamber 21, the flange portion 72 includes an area that overlaps with the optical axis P of the imaging means 31 and functions as the penetration portion 721. For example, in FIG. 4(A), although the area enclosed by the two-dot chain line serves as the penetration portion 721, the other area can be the penetration portion 721 by the installation state of the purge tube 7. With such a structure, the upper surface 721A of the penetration portion 721 can be made flat. The upper surface 72A of the flange 72 is provided with a circular positioning groove 72B along the inner edge of the annular plate shape. By inserting the lower end of the cylindrical portion 71 into this positioning groove 72B, the central axis of the cylindrical portion 71 and the central axis of the flange portion 72 are aligned so that the two are positioned. In a side view, the penetration portion 721 is provided so that the angle θ ₃ formed by the upper surface 721A and the outer peripheral surface 71A of the cylindrical portion 71 becomes a right angle.

[Structure of Single Crystal Lifting Device with Purge Tube] As shown in Figs. 5 and 6, the purge tube 7 is provided in the chamber 21 of the single crystal lifter 1A. Since the purge pipe 7 has a larger inner diameter than the upper end opening of the heat shield 25, it can be placed on the upper surface of the supported portion 252 of the heat shield 25. By placing the flange portion 72 on the upper surface of the supported portion 252 of the heat shield 25, the distance L ₂ from the liquid surface of the silicon melt M to the penetrating portion 721 can be made larger than the distance L in the first embodiment. _{1 is} longer, and the position of the lower end of the penetration portion 721 can be reliably higher than the position of the upper end of the discoloration area A of the purging pipe 9. In addition, compared with the first embodiment, the purge tube 7 can be prevented from being exposed to high temperatures, and it can be reused more times. In addition, the purge pipe 7 is positioned so that the central axis of the cylindrical portion 71 coincides with the central axis of the heat shield 25 and the central axis of the cylindrical portion 71 becomes parallel to the vertical line V. In addition, the purge pipe 7 is positioned so that a part of its upper end side is located in the opening 211C of the cover 211B. The purging pipe 7 and the opening 211C may not be in contact with each other, or both may be in contact with each other. As described above, by supporting the purging tube 7 in the chamber 21, the incident angle θ ₄ of the optical axis P of the imaging means 31 relative to the upper surface 721A of the penetrating portion 721 (the optical axis P relative to the normal line of the upper surface 721A The incident angle θ _{4 of} N is 45° or less.

〔Method of manufacturing silicon single crystal〕 Next, the manufacturing method of the silicon single crystal SM using the single crystal pulling device 1A will be described. In addition, since the manufacturing steps of the silicon single crystal SM are the same as those of the first embodiment, only the differences in the setting of the purge pipe 7 instead of the purge pipe 5 will be described.

In the formation of the silicon single crystal SM, SiO aggregates may fall into the heat shield 25 with the evaporation of the silicon melt M. In this embodiment, the outer edge of the ring-shaped flange 72 The entire periphery is located outside the upper end opening of the heat shield body portion 251, so it is possible to prevent aggregates from reaching the silicon melt M due to the flange portion 72.

In addition, in the production of the silicon single crystal SM, the imaging means 31 of the optical observation means 3 images the image that has penetrated the penetrating portion 721. Then, the control unit 4 controls the production conditions so as to produce the desired silicon single crystal SM based on the production conditions obtained by the optical observation means 3.

[Effects of the second embodiment] According to the second embodiment, in addition to the same effects as (4) and (5) of the first embodiment, the following effects can be achieved. (6) The purging pipe 7 composed of the cylindrical portion 71 and the flange portion 72 is positioned in the chamber 21 such that the central axis of the cylindrical portion 71 and the vertical line V become parallel. Therefore, the incident angle θ ₄ of the optical axis P of the imaging means 31 with respect to the upper surface 721A of the penetrating portion 721 can be made smaller than the previous structure, and the generation status of the silicon single crystal SM can be properly grasped from the outside of the chamber 21 .

(7) Since the flange portion 72 extends in a direction orthogonal to the central axis of the cylindrical portion 71 and is formed in the shape of an annular plate with a uniform thickness, the flange portion 72 can be easily manufactured.

(8) Since the cylindrical portion 71 is formed of graphite, the weight reduction and cost reduction of the purging pipe 7 can be achieved.

[Modifications] In addition, the present invention is not limited to the above-mentioned embodiment, and various improvements, design changes, etc. can be made without departing from the scope of the present invention.

For example, the angle of the outer peripheral surface 51A than the penetration portion 522 surfactant 522A of the cylindrical portion 51 formed an acute angle of θ _1, and the optical axis P with respect to the upper surface 522A of the incident angle becomes 45 ° or more provided. If the angle θ ₁ formed by the upper surface 522A and the outer peripheral surface 51A of the cylindrical portion 51 is less than 180°, that is, when the angle is not 180° as shown in the previous structure, the optical axis P can be relative to the upper surface 522A. The penetration portion 522 is provided in a manner exceeding 45° of incidence angle. Even with such a configuration, the incident angle of the optical axis P with respect to the upper surface 522A can be smaller than in the previous configuration, and it is possible to suppress imaging of the reflection component located in the penetrating portion 522 by the imaging means 31. The penetrating parts 522 and 721 may also be plate-shaped with uneven thickness. The upper surface 521A of the curved flange body part 521 may function as a penetrating part. In this case, the flange part 52 may be formed in a truncated cone shape as a whole.

The cylindrical portion 71 can also be formed of metal such as stainless steel or quartz, and regions other than the functions of the cylindrical portion 51, the flange body portion 521, and the penetration portion 721 of the flange portion 72 can also be formed of graphite or metal. The heat shield body portion 251 of the heat shield body 25 may also be cylindrical, and the purge pipe support portion 251A may not be provided in the heat shield body portion 251. [Example]

Secondly, the present invention will be explained in more detail through examples, but the present invention is not limited to these examples.

First, the purge pipe 9 as shown in FIG. 7(A) is arranged inside the heat shield 25. The purging pipe 9 is formed of quartz in a cylindrical shape, as shown in FIG. 1 of the prior art document (JP 2011-246341 A). The purging pipe 9 supports the lower end 91 of the heat shield 25 by a protrusion 259 protruding inward from the lower end of the heat shield 25.

Using the single crystal pulling device with the structure of Fig. 7(A), the multiple silicon single crystal SM is produced by the single pulling method (the method of producing one silicon single crystal using a quartz crucible), and each silicon single crystal is produced After SM, the discoloration of the purging pipe 9 was observed. At this time, the gap G is adjusted while observing the generation condition with the optical observation means 3 through the side surface portion on the lower end side of the purging pipe 9.

After the first silicon single crystal SM was manufactured, as shown in Figure 7(B), discoloration began. It can be confirmed that the color of discoloration becomes denser as the number of manufacturing increases. At the time when the silicon single crystal was produced approximately 50 hours after the start of the energization of the heater 23, the purge tube 9 was discolored to a state that was difficult to observe by the optical observation means 3. Then, the height H from the lower end 91 of the purging pipe 9 to the upper end of the discoloration area A and the discoloration position of the inner surface of the heat shield 25 are confirmed. According to the result of this confirmation, it was confirmed that the position of the lower end of the penetrating parts 522, 721 can be set higher than the position of the upper end of the discolored area A of the air purging pipe 9 and the upper end of the discolored area inside the heat shield 25 The trachea 5, 7 suppresses the possibility of discoloration. In fact, in the structures of the first and second embodiments, when the purge pipes 5 and 7 are installed at the positions based on the above-mentioned confirmation results to manufacture the silicon single crystal SM, even if it exceeds 50 hours after the heater 23 is energized, No discoloration was seen.

1. 1A: Single crystal pulling device 21: Chamber 22: Crucible 24: Lifting part 25: Heat shielding body 251A: Purge tube support part 3: Optical observation method 5, 7: purging pipe 51, 71: Cylinder part 51A, 71A: outer peripheral surface 52, 72: 锷部 522, 721: penetrating part 522A, 721A: upper surface M: Silicon melt SM: Silicon single crystal

[Fig. 1] A schematic diagram of a single crystal pulling device related to the first embodiment of the present invention. [Fig. 2] In the above-mentioned first embodiment, an enlarged view of the main part of the single crystal pulling device. [Figure 3] shows the purging pipe in the above first embodiment, (A) is a top view, (B) is a cross-sectional view, (C) is a cross-sectional view along the line IIIC-IIIC of (B). [Fig. 4] shows the purging pipe related to the second embodiment of the present invention, (A) is a top view, (B) is a cross-sectional view along the line IVB-IVB of (A). [Fig. 5] A schematic diagram of a single crystal pulling device in the second embodiment described above. [Fig. 6] An enlarged view of the main part of the single crystal pulling apparatus in the second embodiment described above. [Fig. 7] shows an embodiment of the present invention, (A) is a cross-sectional view showing the state near the surface of the silicon melt in the experimental example, and (B) is a perspective view of the purging pipe.

1: Single crystal pulling device

2: Lifting device body

21: Chamber

21A, 21B: gas inlet

211: Main Chamber

211A: Body

211B: Lid

211C: Opening

211D: Window

211E: Support

212: Gate Valve

213: Lifting Chamber

22: Crucible

221: Quartz Crucible

222: Graphite Crucible

23: heater

24: Lifting part

241: Cable

242: Lifting drive

25: Shading body

26: Insulation material

27: Crucible drive

271: Support shaft

28: Electromagnetic coil

29: pull tube

3: Optical observation method

31: Imaging means

32: Calculus

4: Control Department

41: Memory

5: purging pipe

51: Cylinder

52: 锷部

522: penetrating part

522A: Upper surface

G: gap

L ₁ : distance

M: Silicon melt

P: Optical axis

SC: Seed

SM: Silicon single crystal

V: Lead line

Claims (9)

A purging pipe is provided in a chamber of a single crystal pulling device and supported by a heat shield. The purging pipe is characterized in that it includes a cylindrical portion formed in a cylindrical shape, and the pipe is introduced from the outside of the chamber. The inert gas is guided to the molten silicon side; the flange part protrudes outward from the outer peripheral surface of the cylindrical part into a flange shape; the outer diameter of the flange part is hotter than the cylindrical shape or the truncated cone shape provided in the chamber The lower end of the shielding body has a large inner diameter; wherein, at least a part of the flange portion is provided with a penetrating portion, which can observe the formation of the silicon single crystal by an optical observation means provided outside the chamber. The purging tube described in the first item of the scope of patent application, wherein the penetration portion is formed such that the incident angle of the optical axis of the optical observation means with respect to the upper surface of the penetration portion is 45° or less. As for the purging pipe described in the second item of the scope of patent application, the penetration portion is formed so that the incident angle becomes 0°. As for the purging pipe described in the first item of the scope of patent application, the above-mentioned penetration portion is formed of flat-plate-shaped quartz with a uniform thickness. In the purging pipe described in any one of the claims 1 to 4, the collar portion is formed in the shape of an annular plate extending in a direction orthogonal to the central axis of the cylindrical portion. As for the purging pipe described in item 5 of the scope of patent application, the flange portion is formed in a way that the thickness is uniform. As for the purging pipe described in any one of items 1 to 4 in the scope of patent application, the cylindrical portion is formed of graphite. A single crystal pulling device, characterized by comprising: Crucible, which contains the silicon melt; the lifting part, which generates silicon single crystal by contacting the seed crystal to the above silicon melt and then pulling it; a cylindrical or truncated cone-shaped heat shield to enclose The above-mentioned silicon single crystal above the crucible is arranged in a manner; the purging pipe is as described in any one of items 1 to 7 in the scope of the patent application, and is supported by the above-mentioned heat shield; a chamber containing the above-mentioned crucible and the heat The shielding body and the gas purging pipe; a gas introduction part that introduces an inert gas from the outside of the chamber to the inside of the chamber; and an optical observation means provided on the outside of the chamber and passing through the penetrating part of the gas purging pipe , Observe the formation of the above-mentioned silicon single crystal. In the single crystal pulling device described in item 8 of the scope of patent application, a purge tube support portion that supports the purge tube from below is provided on the inner peripheral surface of the heat shield.

Images