JPH0397688A - Distribution cylinder for single crystal pulling up device - Google Patents

Abstract

PURPOSE:To prevent the decrease in the oxygen concn. in a single crystal and the deposition of SiO on a pulling up shaft, etc., without increasing the flow rate of an inert gas by providing a quartz window plate covering the window holes formed in the lower end part of the gas distribution cylinder made of graphite. CONSTITUTION:A sub-chamber 14 and the top end aperture of a long cylinder 40 made of graphite are connected to the top end aperture 12 part of a main chamber 10 internally provided with a crucible 22. The cylinder 40 concentrically encloses the single crystal 36 to be pulled up perpendicularly upward and has the window hole 40a for observation on the lower side surface. A cylinder 42 made of graphite, the outside diameter of which is approximately equal to the inside diameter of the cylinder 40 is also provided with the window hole 42a of the same shape as the shape of the window hole 40a on the side surface. The edge part of the quartz window plate 44 is fitted to a groove frame 42b in the edge part thereof. The cylinder 42 is fitted into the cylinder 40 in this state. The cylinder 42 is detained to the cylinder 40 by aligning the window holes 42a, 40a. Gaseous Ar is supplied form an inlet joint 14a and while the single crystal 36 is observed through the window plate 44 from the peep hole 10b, the single crystal is grown.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is used in a single crystal pulling device using the CZ method, which concentrically surrounds a single crystal that is being pulled vertically upward, and an inert gas is flowed down inside. The present invention relates to a rectifier tube for a single crystal pulling device.

[Conventional technology 1] When pulling an SSi single crystal from the 81 melt in a quartz crucible using the Ci Z method, volatile SiO is released by the reaction between the quartz crucible and the Si melt, and the edge of the crucible, Si The qi crystal is deposited on the L axis and the inner wall of the chamber.

Times Φ1′. The S10 deposited on the lifting shaft that moves upward is scraped off by the airtight seal ring on the upper lid.
It falls into the melt on the F side and causes defects in the single crystal being grown.

Therefore, a rectifying cylinder is suspended in the chamber coaxially with the pulling axis to a height of 150 to 350 mm above the melt surface, and 8r gas is allowed to flow down into the rectifying cylinder from the direction 1-, and the SiO evaporated from the melt surface is
A method has been proposed in which Ar gas is discharged from the T' part of the chamber together with Ar gas (Japanese Patent Publication No. 5, 3-65-1).
Publication No. 1).

On the other hand, by attaching a collar shaped like the lower end of this rectifying cylinder folded outward and upward, it is possible to reduce the width of crystals near the solid-liquid interface.
2. A method of increasing the downward temperature gradient to increase the crystal explantation rate, lowering the oxygen concentration in the single crystal to reduce oxidation-induced defects (OrSF) and swirl defects, and increasing the SiO evacuation effect described above. has been proposed (Japanese Unexamined Patent Publication No. 6465086).

It is preferable to form such a rectifying cylinder with graphite from the viewpoints of heat resistance, ease of processing, and cost. Therefore, automatic diameter control and good S1 single crystal growth are hindered. Therefore, the above-mentioned publication proposes forming a window hole in the lower end of the rectifier tube.

[Problems to be Solved by the Invention] However, when the window hole is formed, the flow rate of the Ar gas flowing out from the lower end opening of the rectifier tube decreases, and the above-mentioned effect is reduced. For example, the amount of oxygen evaporated from the melt surface decreases, and the oxygen concentration of the S i rQ crystal increases. Specifically, it becomes difficult to reduce the oxygen concentration to 1 8 ppma or less, making it impossible to meet the recent demands of device manufacturers who are promoting higher integration. Such problems can be solved by increasing the flow rate of Ar gas.

However, in actual practice, as shown in the experimental example below, this amount is large, for example 20 O R /+ni
It has been found that the cost is high due to the number of times n. Chamber (
Although it is possible to increase the amount of oxygen evaporation by lowering the pressure inside the furnace, the reaction between the quartz crucible and the Si melt increases, which shortens the life of the quartz crucible and increases costs.

In view of these problems, it is an object of the present invention to provide a method that allows the shape of a single crystal to be observed without increasing the flow rate of inert gas and without reducing the above-mentioned effects, and which is easy to manufacture. Significantly higher costs? ;An object of the present invention is to provide a rectifier tube for a single crystal pulling device that does not require a single crystal puller.

[Means for Solving Problem 1] In order to achieve this object, in the rectifier tube for a single crystal pulling device according to the present invention, the upper end opening is connected to the upper end opening of the main chamber in which the crucible is installed. It is equipped with a first graphite cylinder that concentrically surrounds the single crystal that is being pulled directly above the turret and has a window hole formed on the side of the F section, and a quartz window plate that covers the window hole.

A specific window plate mounting structure includes, for example, a second window plate in which a window hole corresponding to the window hole is formed, the inner diameter of which is approximately equal to the outer diameter of the cylinder.
A graphite cylinder is fitted and locked into the first cylinder with both window holes aligned, and a groove is formed in the shape of 1+ at the edge of the window hole on the joint surface of the first cylinder and the second cylinder. The structure is such that the edge of the window plate fits into the groove.

In another specific window plate mounting structure, the window plate is constituted by a cylinder whose outer diameter is approximately equal to the inner diameter of the first cylinder, and this is fitted and locked into the first cylinder. ing.

Note that a graphite collar that protrudes outward and upward may be attached to the lower end of the rectifier tube.

Further, although it is not necessary, the surfaces of the rectifier tube and this collar may be coated with SiC to further reduce deterioration.

``Effect'' Since a window hole is formed in the shotgun, immediately after lifting σ)S
i? The shape of the L1 crystal can be observed, the diameter can be optically measured, and a good S1 single crystal can be grown.

Since this window hole is covered with a window plate, all the inert gas flowing down inside the straightening cylinder passes between the bottom end of the straightening cylinder and the melt surface, so there is no need to increase the flow rate of the inert gas. , the oxygen concentration within the single crystal can be reduced, SiO precipitation on the bow 1 biaxes etc. can be prevented, and the single crystal length velocity can be increased.

In addition, the material for the rectifier tube must be heat resistant and do not emit impurities, and ceramics may be considered, but the cylinder of the main body is made of graphite, which is easy to form and inexpensive, and only the window hole part, i.e. Since only the necessary parts are covered with quartz, the entire rectifier tube is easy to manufacture and does not require a significant increase in cost.

[Example 1 Embodiments of the present invention will be described below based on the drawings.

(1) Example I FIG. 1 shows the state in which the rectifier cylinder for a single crystal pulling apparatus is used.

A subchamber 14 is connected to the upper end opening 12 of the main chamber 10 . An inlet joint 14a for gas supply is formed in the side wall of the sub-chamber 14, and an exhaust hole 10a is formed in the bottom of the main chamber 10 for sucking and discharging gas. A viewing window (not shown) is provided in which a viewing window 10b for observing the pulled single crystal and an ITV for measuring the diameter of the solid-liquid interface are arranged facing each other. A table 18 is fixed to the upper end of the vertical axis 16, and a graphite crucible 20 is placed on the table 18, and a quartz crucible 22 is fitted into the graphite crucible 20. The heater 24 is surrounded by a graphite heat insulating wall 2G. When the polycrystal S1 is placed in the quartz crucible 22 and power is supplied to the heater 24,
This S1 is melted and becomes a melt 28.

On the other hand, a seed wheat crystal 34 is held via a seed holder 32 at the lower end of a pulling shaft 30 which is moved along the center line of the subchamber l4.

Further, a rectifying tube 3 is provided at the upper end opening of the main chamber 10.
The upper end opening of an elongated graphite cylinder 40, which is the main body of No. 8, is connected. This long cylinder 40 is arranged perpendicularly and concentrically with the pull-up f*30. The length of the long cylinder 41+1:') is the distance from the lower end of the long cylinder 40 to the surface of the melt 28.
-100mm.

In addition, the inner diameter of the ellipse is the inner diameter of the rectifying tube 38 and the single crystal 36.
The shortest distance to the surface is 5 to 100+++n.

14 cylinder 400) There is a window hole 4 for observation on the side of the T part.
0a is formed. At the lower end of the long cylinder 40, a locking portion 40b is formed with a reduced diameter and facing inward in the radial direction.

As shown in FIG. 2, a window hole 42a having the same shape as the window hole 40a is also formed on the side surface of a short graphite cylinder 42 whose outer diameter is approximately equal to the inner diameter of the long cylinder 40. A groove frame 42b is formed in the window hole 42affl portion of the outer peripheral surface of the short cylinder 42, and the edge of the quartz window plate 44 is fitted into this. In this state,
The short cylinder 42 is inserted into the long cylinder 40, and the short cylinder 42 is inserted into the long cylinder 40 with the window hole 42a and the window hole 40a aligned.
It is locked by the locking part 40b. FIG. 3 shows a cross section through the window at this locking pocket.

As shown in FIG. 1, on the outer circumferential surface of the locking portion 40b, there is a hollow truncated conical graphite collar 4 having the same slope as the outer circumferential surface.
The small diameter side ends of No. 6 are joined.

Next, the operation of this embodiment configured as described above will be explained.

The pressure inside the main chamber 10 is reduced using a vacuum bomb, Ar gas is supplied from the artificial joint 14a of the subchamber 14, and the Ar gas is suctioned and discharged from the exhaust hole 10a of the main chamber 10. 8. Adjust the gas supply or discharge amount to bring the pressure inside the main chamber 10 to 100 mbar.
to a certain degree. Next, power is supplied to the heater 24 to heat and melt the polycrystalline silicon in the quartz crucible 22 to form a melt 28. Next, the pulling shaft 3'0 is lowered to immerse the seed crystal 34 in the melt 28 and pulled up to grow a single crystal 36.

At this time, the operator must open the aki fi I0 of the main chamber 10.
While observing the single crystal 36 through the window plate 44 from b, various controls are carried out so that a good single crystal 36 is grown! Adjust the settings (correct the automatic control amount).

On the other hand, the gas flows down inside the straightening tube 38, and all of it passes between the lower end of the straightening tube 38 and the surface of the melt 28, and the gas flows down into the straightening tube 38, passing between the lower end of the straightening tube 38 and the surface of the melt 28, and passing through the collar 4.
The liquid is discharged from the quartz crucible 22 by passing between the outer surface of the quartz crucible 6 and the inner surface of the quartz crucible 22, descends, and is sucked and discharged from the extraction hole 10a.

Therefore, the volatile SiO produced by the reaction between the melt 28 and the quartz crucible 22 is discharged from the discharge hole 10a along with the Ar gas flow, and is discharged from the inner peripheral surface of the quartz crucible 22 and the collar 46. It is possible to prevent 510 from being deposited on the outer surface, the single crystal 3 (;, the seed holder 32, the pulling shaft 30, etc.). Since the oxygen concentration in the single crystal 36 is lowered, oxidation-induced defects and swirl defects are reduced.

Further, since the Ar gas passes around the single crystal 36, the single crystal 36 is cooled. Furthermore, the color 46 is
Although it is heated by absorbing the radiant heat directly received from the melt 28 and the radiant heat reflected from the inner surface of the quartz crucible 22, it is cooled by Ar gas, so the temperature at the bottom of the long cylinder 40 is lower than when the collar 46 is not provided. It will be considerably lower than Therefore, the temperature gradient in the vertical direction of the single crystal 36 near the solid-liquid interface increases, and a certain longitudinal velocity of the single crystal 36 increases. ko0)
This means that the amount of oxygen taken in per unit length of the single crystal 36 is reduced, which contributes to reducing the oxygen concentration of the single crystal 36.

(2) Second embodiment FIG. 1 does not show a cross section of the lower end of the rectifying cylinder of the second embodiment.

In this rectifier tube, the rectangular window hole 40 is narrower than that in the first embodiment.
c is formed at three locations on the lower side surface of the graphite long cylindrical window 40A,
Correspondingly, a rectangular window hole 42 is also provided in the graphite short cylinder 42A.
c is formed in three places, and a window hole 42 is formed on the outer peripheral surface of each short cylinder 42A.
A groove frame 42d is formed on the c edge, and a flat rectangular quartz window plate 44A is fitted into each groove frame 42d.

In this second embodiment, since a flat window plate is used, the first
It is easier to manufacture than the embodiment, and the rectifier tube can be constructed at a lower cost.

(3) Third embodiment FIG. 5 shows the lower structure of a third embodiment of the present invention.

The long cylinder 40 has the same shape as that of the first embodiment, but instead of the short cylinder 42 and the window plate 44, a cylindrical window plate 44a made of quartz whose outer diameter is approximately equal to the inner diameter of the long cylinder 40 is attached to the long cylinder 40. It is inserted and locked inside.

This third embodiment has the advantage that the window plate 44a having the same shape can be used for any window hole shape.

(4) Experimental example Next, an experimental example will be explained.

(A) The criteria for comparison are as follows.

A: Gas flow m: 1001!/min Main chamber 10 internal pressure: 100 mbar Rectifier tube 3
Inner diameter of 8: 200 mm Initial distance from the lower end of rectifying cylinder 38 to the surface of melt surface 28: 30 mm Volume of window hole 40a: 200 cm" (necessary and sufficient area) Diameter of single crystal 36 without window plate 44: 6 inch Under the above conditions, the oxygen concentration after 10 cm of the straight body part on the third day of the single crystal was 20 ppma. Also, the distribution of oxygen concentration in the cross section of this straight body part DD = 1 0 0
(CC-CP)/Cc was 15%. Here, Co: Oxygen concentration at the center [,,: Oxygen concentration at a position 3 mm from the peripheral surface to the center side. Since the maximum acid sa level is required to be below the reference value, it is necessary to reduce the division D.

(B) Among the above standard conditions, only Ar gas meteors are
0 4! /min, the oxygen concentration is approximately 1.5
It was possible to lower ppma. However, the loss D mentioned above worsened to 20%.

(C) Under the above standard conditions (A>), when a window plate is attached to the window hole and other conditions are the same, the oxygen a degree is approximately 31ρ
It was possible to lower ma. Moreover, the above dispersion D is 13
% was slightly improved.

[Effects of the Invention] As explained above, in the straightening tube for a single crystal pulling device according to the present invention, a window hole is provided at the lower end and this window hole is covered with a window plate, so that the flow down inside the straightening tube is All of the inert gas passes between the lower end of the rectifier cylinder and the melt surface, and even without increasing the flow rate of the inert gas, it is possible to prevent Si○ from depositing on the pull axis, etc. can increase the growth rate of
Furthermore, oxidation-induced defects and swirl defects can be reduced, and since the cylinder of the main body is made of graphite, which is easy to shape and is inexpensive, and only the window hole portion, that is, the necessary portion is covered with quartz, the rectification is reduced. The cylinder as a whole has excellent effects in that it is easy to manufacture and does not require a significant increase in cost.

[Brief explanation of drawings]

1 to 3 relate to a first embodiment of the rectifying tube for a single crystal pulling device according to the present invention, FIG. 1 is a schematic vertical cross-sectional view showing the condition in which the rectifying tube is used, and FIG. FIG. 3 is an exploded perspective view showing the lower structure of FIG. FIG. 4 is a cross-sectional view showing the lower structure of the rectifier tube according to the second embodiment of the present invention. FIG. 5 is an exploded perspective view showing the lower structure of the rectifier tube according to the third embodiment of the present invention. In the figure, 10 is the main chamber I2, the opening 14 is the subchamber 22, the quartz crucible 28, the melt 30, the pulling shaft 36, the single crystal 38, the rectifying cylinder 40, the long graphite cylinders 40a, 40c, 42a, 42c are windows. Holes 42, 42A are graphite short cylinders 42b, 42d are groove frames 44, 44A, 44B are quartz window plate 46 is graphite collar

Claims (1)

[Claims] 1) A main chamber (10) in which a crucible (22) is installed;
) whose upper end opening is connected to the upper end opening (12) and concentrically surrounds the single crystal (36) that is pulled vertically upward;
A first graphite cylinder (40, 40A) with window holes (40a, 40c) formed in the lower side surface, and a quartz window plate (44, 44A, 44B) that covers the window hole. A rectifier tube for single crystal pulling equipment. 2), the outer diameter is approximately equal to the inner diameter of the cylinder, and the window hole (4
A second graphite cylinder (42, 42A) in which window holes (42a, 42c) corresponding to 0a, 40c) are formed is attached to the first cylinder (40, 40A) with both window holes aligned. Grooves (42b, 42d) are formed in the edge of the window hole on the joint surface of the first cylinder and the second cylinder, and the window plate (44) is fitted and locked in the groove.
, 44A) are fitted into the straightening tube for a single crystal pulling apparatus according to claim 1. 3) The window plate (44B) has an inner diameter similar to that of the first cylinder (44B).
2. The rectifier tube for a single crystal pulling apparatus according to claim 1, wherein the rectifier tube is a cylinder having a substantially same outer shape as the first cylinder, and is fitted and locked in the first cylinder to cover the window hole (40a).