JP3557756B2 - Fogging prevention structure of quartz window plate for observation window of rectifying cylinder for single crystal pulling device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure for preventing fogging of a quartz window plate for an observation window of a diameter detector provided in a rectifying cylinder of a single crystal pulling apparatus formed by a CZ method.
[0002]
[Prior art]
In the CZ method, as schematically shown in FIG. 5, a single crystal is formed by bringing a seed crystal 18 into contact with a Si melt 13 in a quartz crucible 12 and moving a pulling shaft 17 connected to the seed crystal 18 upward. This is a single crystal manufacturing method for forming No. 19 and is widely known. In this case, the SiO bent out to the pulling shaft 17 and the like is scraped off by the hermetic sealing of the upper cover (not shown) and falls into the lower Si melt 13. For this reason, there is a problem that dislocation occurs in the growing single crystal 19. Therefore, a hollow rectifying cylinder 1 a surrounding the single crystal 19 is provided concentrically with the pulling shaft 17, the lowermost surface thereof is disposed near the melt surface 20 of the crucible 12, and the inside of the rectifying cylinder 1 a is positioned from above. A method has been proposed in which Ar gas is allowed to flow down, and SiO evaporated from the melt surface 20 is discharged from the outside of the apparatus together with the Ar gas.
[0003]
FIG. 5 shows an outline of a known technique provided with the above-described rectifying cylinder 1a, and its detailed structure is disclosed in Japanese Patent Publication No. 6-88864. That is, the rectifying cylinder 1a comprises a graphite long cylinder 2a and a graphite short cylinder 3a fitted into an inner hole on the lower surface side thereof. Is provided. The graphite collar 21a is also disclosed in Japanese Patent Publication No. 6-39351. The graphite collar 21a increases the vertical temperature gradient of the single crystal near the solid-liquid interface, increases the crystal growth rate, and increases the single crystal. The purpose is to lower the oxygen concentration in the inside to reduce oxidation-induced defects and swirl defects, and to further enhance the SiO exhaust effect.
[0004]
The rectifying cylinder 1a has the effect as described above, but is preferably formed of graphite from the viewpoint of heat resistance, easiness of processing, and cost reduction. However, in the case of the rectifying cylinder 1a made of graphite, it is not possible to observe the shape of the Si single crystal immediately after pulling or to optically measure the diameter of the solid-liquid interface. Therefore, as shown in FIG. 5, a quartz window plate 4a for an observation window is fitted below the rectifying cylinder 1a. That is, a quartz window plate 4a for an observation window is fitted into the graphite short cylinder 3a, and a window hole 7a is formed in the graphite long cylinder 2a at a portion opposed to the quartz window plate 4a. The position, shape and size of the quartz window plate 4a for the observation window and the window hole 7a are determined by the diameter detector installed in the viewing window 23a formed above the outer cylinder of the main chamber 8a as shown in FIG. 22 makes it possible to simultaneously detect both the center and the outer periphery of the solid-liquid interface of the single crystal 19.
[0005]
[Problems to be solved by the invention]
By using the rectifying tube, the flow rate of the inert gas can be reduced, and the pressure in the furnace can be reduced to a level that does not affect the life of the crucible. However, in the case of long-term operation, the SiO evaporated from the melt surface adheres to the inner member of the furnace, and the quartz window plate for the observation window begins to fog, and the single crystal grows during pulling. The state, the shape, etc., cannot be detected accurately.
[0006]
When the single crystal 19 is visually observed from the observation window 23a, it can be observed even if the quartz window plate for the observation window is somewhat cloudy, but the diameter of the single crystal can be automatically and accurately measured using a diameter detector. Is difficult to observe. One solution to this problem is to remove the quartz window plate. However, the oxygen concentration increases, resulting in a crystal quality that does not meet the low oxygen concentration requirements recently required by device manufacturers. .
[0007]
The present invention has been made in view of the above circumstances, and can reliably prevent fogging of a quartz window plate for an observation window even during long-term operation, and can easily prevent the quartz window plate for a viewing window from being pulled up by a diameter detector. An object of the present invention is to provide a structure for preventing fogging of a quartz window plate for an observation window of a rectifying cylinder for a single crystal pulling apparatus, in which measurement of a shape and a diameter of a crystal is accurately performed.
[0008]
[Means for Solving the Problems]
The fogging prevention structure of the quartz window plate for an observation window of the rectifying cylinder for a single crystal pulling device according to claim 1, wherein the lower end face is arranged close to the surface of the crucible to observe the crystal growing state of the single crystal. A fogging prevention structure for the observation window quartz window plate in a single crystal pulling apparatus provided with a rectification tube having a window quartz window plate and a diameter detector for crystal observation, wherein the rectification tube includes the diameter detection device. An inner cylinder in which the observation window is disposed at a position facing the vessel, and an outer cylinder which is inserted into the outer periphery of the inner cylinder and forms a window hole at a position facing the observation window, At the joint between the inner cylinder and the outer cylinder at the portion where the observation window of the cylinder is provided, a gas vent passage communicating the single crystal forming chamber side in the rectification cylinder and the outside of the rectification cylinder is provided. And
[0009]
3. The fogging prevention structure for a quartz window plate for an observation window of a rectifying cylinder for a single crystal pulling device according to claim 2, wherein the gas vent passage scrapes a part of an outer surface of the inner cylinder along an axial direction. It is characterized by being formed by.
[0010]
According to the structure for preventing fogging of the quartz window plate for an observation window according to claim 1 of the present invention, a portion of the rectifying tube including the graphite inner tube and the graphite outer tube inserted into the inner tube is provided with the observation window. In order to provide a gas venting passage communicating with the single crystal forming chamber in the rectifying cylinder at the joint surface of the two, a part of the Ar gas in the rectifying cylinder passes through this gas bleeding passage. Since the Ar gas is directly blown onto the surface, the SiO having a single crystal pull width does not adhere to the quartz window plate for the observation window. Therefore, fogging is prevented.
[0011]
According to the fogging prevention structure for a quartz window plate for an observation window according to claim 2 of the present invention, the gas vent passage is formed by shaving a part of the outer surface of the graphite inner cylinder along the axial direction, so that it can be easily formed. , And is easily formed. Further, the volume of the gas escape passage can be freely changed.
[0012]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an axial sectional view showing the overall structure of a single crystal pulling apparatus to which this embodiment is applied, and FIGS. 2 to 4 are views showing an embodiment of a graphite inner cylinder and a graphite outer cylinder.
[0013]
First, the outline of the single crystal pulling apparatus will be described with reference to FIG. A sub-chamber 9 is connected to an upper opening of the main chamber 8. An inlet 10 for supplying Ar gas is formed in the sub-chamber 9, and an outlet 11 for Ar gas is formed on the bottom surface of the main chamber 8. A quartz crucible 12 is disposed substantially at the center of the main chamber 8, and the crucible 12 for storing the Si melt 13 is supported by a vertically movable rotary shaft 14 which can be raised and lowered. Around the crucible 12, a heater 15 and a graphite heat insulating wall 16 are disposed so as to surround the crucible 12. The pulling shaft 17 is vertically moved along the center line of the sub-chamber 9, and the seed crystal 18 at the lower end thereof comes into contact with the Si melt 13 in the crucible 12, and pulls and grows the single crystal 19.
[0014]
The rectifying cylinder 1 is connected to the upper opening of the main chamber 8 in a hanging manner. The distance between the lower end of the flow regulating cylinder 1 and the melt surface 20 is small, and is maintained at, for example, 5 to 100 [mm]. The rectifying cylinder 1 is composed of a graphite outer cylinder 2 having a hollow pipe shape, and a graphite inner cylinder 3 inserted at the lower end thereof and opened vertically. Note that the rectifying cylinder 1 is arranged on a concentric axis with the single crystal 19 to be pulled. Ar gas supplied into the sub-chamber 9 from the inlet 10 passes through the flow straightening tube 1, passes through a relatively narrow space between the lower end of the flow straightening tube 1 and the melt surface 20, and passes through the graphite collar 21 and the crucible. 12 and is discharged from the discharge unit 11 through the gap between the inner surface of the discharge unit 11 and the inner surface 12. Volatile SiO generated by the reaction between the Si melt 13 and the crucible 12 is carried along with the flow of Ar gas and discharged. Therefore, the deposition and adhesion of SiO are prevented.
[0015]
As shown in FIGS. 1 and 2, a graphite inner cylinder 3 has a plurality of (three in the illustrated) windows 5 for fitting a quartz window plate 4 for an observation window, which is opened only at the lower side and has a circumference. It is formed along the direction. Among these windows, the window 5a for the diameter detector 22 is formed of an elongated slit-like groove having an opening at the lower part, and as shown in FIG. 2, a quartz window plate for an observation window having the same shape as this groove. 4 is fitted. On the other hand, the outer surface of the graphite inner cylinder 3 is scraped off along the axis by an appropriate amount at a position facing the quartz window plate 4 for the observation window of the graphite inner cylinder 3. As shown in FIGS. 1, 3, and 4, a gap that penetrates in the axial direction is formed between the cut-off portion and the inner surface of the graphite outer cylinder 2. This gap corresponds to the gas release passage 6.
[0016]
As shown in FIGS. 1, 2 and 4, a window hole 7 is formed at the lower end of the graphite outer cylinder 2 at a position facing the observation window 4 of the graphite inner cylinder 3. As shown in FIG. 1, the size of the window hole 7 may be any size as long as it has an airy necessary for observing the single crystal 19 by the diameter detector 22 installed in the viewing window 23, as shown in FIG. 2 as an example. Although a shape having a bulge at the top is used, the shape is not limited to this.
[0017]
Next, the fogging prevention effect of the quartz window plate for an observation window according to the present embodiment will be described. As the single crystal 19 is pulled, the SiO gas evaporates from the crucible 12 and tends to adhere to various parts. As described above, the SiO gas is guided downward by the Ar gas introduced from the inlet portion 10 of the sub-chamber 9, and is discharged together with the Ar gas from the discharge portion 11 on the bottom surface of the main chamber.
[0018]
On the other hand, the Ar gas entering the graphite outer cylinder 2 of the rectifying cylinder 1 connected thereto from the sub-chamber 9 flows on the inner surface side of the graphite inner cylinder 3, and a part of the Ar gas flows on the outer surface of the graphite inner cylinder 3. The gas passes through the gas release passage 6 between the inner cylinder 2 and the inner surface of the graphite outer cylinder 2. During the passage, the Ar gas contacts the quartz window plate 4 for the observation window fitted to the graphite inner cylinder 3 and is blown against the quartz window plate 4. Therefore, no SiO is deposited on the quartz window plate 4 for the observation window.
By appropriately setting the supply amount of the Ar gas and the volume of the gas vent passage 6, fogging of the observation window quartz window plate 4 is completely prevented. The shape, diameter, and the like of the single crystal on the melt surface 20 are imaged by the diameter detector 22 illuminated on the quartz window plate 4 for the observation window and the window hole 7, and measured by a computer attached to the diameter detector 22. Since the fogging does not occur on the quartz window plate 4 for the observation window, the shape and diameter of the single crystal 19 can be accurately and automatically measured.
[0019]
In the above description, the quartz window plate 4 and the window hole 7 for the observation window of the graphite outer cylinder 2 and the graphite inner cylinder 3 have the shapes shown in the drawings, but, of course, are not limited thereto. In addition, the gas vent passage 6 may be any as long as the Ar gas is brought into contact with the outer surface of the quartz window plate for the observation window, and may be formed by scraping off the outer surface of the graphite inner cylinder 3 or, for example, a graphite outer plate. A recess may be formed on the inner surface of the cylinder 2.
[0020]
【The invention's effect】
According to the structure for preventing fogging of the quartz window plate for an observation window according to claim 1 of the present invention, a portion of the quartz window plate for an observation window at the joint surface between the graphite outer cylinder and the graphite inner cylinder is provided in the rectifying cylinder. By providing a gas passage for allowing a part of the introduced Ar gas to pass through, the SiO gas is not attached to the quartz window plate for the observation window in the case of long-term operation, and fogging is reliably prevented. This fogging prevention effect is sufficiently exhibited even when the supply of Ar gas is small. In addition, since the prevention of fogging is surely performed, the shape and diameter of the single crystal can be accurately and automatically measured by the diameter detector. Therefore, online management becomes possible.
According to the structure for preventing fogging of the quartz window plate for an observation window according to claim 2 of the present invention, the gas vent passage is formed by shaving off a part of the outer surface of the graphite inner cylinder. In addition, a gas vent passage having a desired volume can be formed.
[Brief description of the drawings]
FIG. 1 is an axial sectional view showing an overall schematic structure of a single crystal pulling apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing how to attach the graphite inner cylinder to the graphite outer cylinder.
FIG. 3 is a plan view showing a state where a graphite inner cylinder is assembled to a graphite outer cylinder.
FIG. 4 is a sectional view taken along line AA of FIG. 3;
FIG. 5 is a partial axial sectional view showing a schematic structure around a rectifying cylinder of a conventional single crystal pulling apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rectifying cylinder 2 Graphite outer cylinder 3 Graphite inner cylinder 4 Quartz window plate for observation window 5 Window 5a Window 6 Gas release passage 7 Window hole 8 Main chamber 9 Sub chamber 10 Inlet 11 Outlet 12 Crucible 13 Si melt 14 Elevating rotating shaft 15 Heater 16 Graphite insulating wall 17 Pulling shaft 18 Seed crystal 19 Single crystal 20 Melt surface 21 Graphite collar 22 Diameter detector 23 Viewing window

Claims (2)

The above-mentioned observation in a single crystal pulling apparatus provided with a rectifying cylinder having a quartz window plate for an observation window and a diameter detector for observing a crystal which is arranged with a lower end face close to the surface of the crucible and observes a crystal growth state of a single crystal. A fogging prevention structure for a window plate made of quartz for a window, wherein the rectifying tube includes an inner tube in which the observation window is disposed at a position opposed to the diameter detector, and the rectifying tube is inserted and attached to an outer periphery of the inner tube. An outer cylinder forming a window hole at a position opposed to the observation window, and at a joint between the inner cylinder and the outer cylinder at a portion where the observation window of the inner cylinder is disposed, A fogging prevention structure for a quartz window plate for an observation window of a rectification cylinder for a single crystal pulling device, wherein a gas vent passage communicating the single crystal formation chamber side and the outside of the rectification cylinder is provided. The quartz window plate for an observation window of a rectifying cylinder for a single crystal pulling device according to claim 1, wherein the gas vent passage is formed by scraping a part of an outer surface of the inner cylinder along an axial direction. Anti-fogging structure.

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