JPH02172884A - Device for pulling up single crystal rod - Google Patents

Abstract

PURPOSE:To lower the concn. of C in a single crystal to be pulled up by covering the upper part of the high-temp. part of a heater and heat insulating member with a gas guiding cylinder. CONSTITUTION:A seed crystal 13 attached to a pulling up shaft 11 is immersed into the surface of an Si melt 10 formed by charging Si materials divided to suitable sizes into a quartz crucible 2 housed in a chamber 1 and heating the materials with a heater to melt the same and an inert gas is supplied from a purging tube 9 into the chamber l and is run in an arrow direction. The seed crystal 13 is pulled up while the shaft 11 is rotated. The vapor of the carbon compd. generated from the high-temp. part of the heater 4 and heat insulating member 5 consisting of a carbon material is discharged from an aperture 6 through the spacing 8 between the gas guiding cylinder 12 and the chamber 1. The above-mentioned gas guiding cylinder 12 consists of a short cylindrical part 12a which fits airtightly to the outer peripheral part at the top end of the crucible 2 and a collared taper cylindrical part 12b constituted of an annular disk 12b-1 which opens in a funnel shape upward form the top end thereof and the top end of which extends horizontally outward.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pulling device for pulling a single crystal rod from a polycrystalline melt by the CZ (Czochralski) method.

(Prior Art) This type of pulling device includes a purge tube for supplying an inert gas in a chamber, a crucible for accommodating a crystal raw material, a heater disposed around the crucible, and a purge tube disposed around the heater. The heater may be configured by housing a heat insulating member or the like;
The heat insulating members are made of carbon materials, and some of the carbon materials are in contact with the outside of the quartz crucible, so when they are heated to high temperatures, vapors of carbon compounds such as 1CO are generated and these vapors are released. For example, in semiconductor manufacturing, high concentration of C in Si single crystals is mixed into the crystal melt in the crucible, which increases the C concentration in the single crystal rod that is pulled, causing various problems. It has an adverse effect on the electrical properties of the metal and is the main cause of various crystal defects.

Therefore, an inert gas such as Ar gas is introduced into the chamber from the purge tube to prevent the vapor of carbon compounds such as CO from coming into contact with the crystal melt in the crucible, thereby eliminating the above problem. Or is it commonly practiced?

(The problem that the invention aims to solve! 2nd floor) However, even if an inert gas is supplied into the chamber as described above, the vapor of carbon compounds such as CO generated from the high temperature parts of the heater and the heat insulating member will still enter the crucible. It is difficult to completely prevent contact with the crystal melt, and there is a limit to keeping the C5 degree in the pulled single crystal rod low.

Therefore, Japanese Patent Publication No. 57-40119 discloses a pot-shaped heat shielding [k gas rectifying cylinder] that concentrically surrounds the single crystal rod being pulled, or this structure is designed to prevent the inert atmosphere gas inside the crucible from flowing into the crucible. Immediately after exiting the outer periphery of the upper edge, the carbon comes into contact with the carbon crucible susceptor close to the outer surface of the upper edge of the crucible, and further comes into contact with the heater and other carton members, so that the carbon is A contaminated atmosphere is likely to form on top of the melt in the crucible. Therefore, this method cannot be expected to be effective in suppressing single crystal contamination of the single crystal rod being pulled.

Another example is Japanese Patent Publication No. 56-21758. This method is structurally complex and requires parts that are easily damaged and difficult to machine, and most importantly, silicon oxide is detected on the outer surface of the lower end of the critical component, the quartz gas strainer. There is a problem in that crystal pores are formed due to the falling of the crystals.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a single-crystal rod pulling device capable of lifting a single-crystal rod with a low C concentration.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a purge tube for supplying an inert gas, a crucible for accommodating a crystal raw material, a heater disposed around the crucible, In a single-crystal rod pulling device configured to house a heat insulating member placed around the heater, a purge tube that concentrically surrounds the E-drawn single-crystal rod is inserted from the top of the chamber into the crucible. a short cylindrical part that extends close to the hot water level so that the lower end edge of the purge tube is positioned below the upper end edge of the crucible, and that fits airtightly to the outer periphery of the upper end of the crucible; and the upper end of the short cylindrical part A gas guide tube is provided, which opens upward in a funnel shape, and has a flange-tapered tube section consisting of a ring-shaped disk extending horizontally outward from the upper end of the gas guide tube. It is characterized in that the gap between the outer periphery of the ring-shaped disk and the inner wall of the chamber is limited to an extent that blocks the flow of gas upward from the lower part of the chamber.

(Function) Since the upper part of the high-temperature part of the heater or heat insulating member is covered with a gas induction tube, c is generated from the high-temperature part.

The rise of the vapor of carbon compounds such as CO is blocked by the gas induction cylinder, and the vapor of carbon compounds such as CO is prevented from flowing to the crucible side and coming into contact with the crystal melt in the crucible, and as a result,
C' of the single crystal rod pulled up by the pulling device
It can be kept to a low degree.

(Example) An example of the present invention will be described below based on the accompanying drawings.

The drawing is a schematic vertical cross-sectional view of a pulling device according to the present invention, and in the drawing, l indicates a chamber, and a quartz crucible 2 is placed on a support shaft 3 and stored in the chamber 1. ing. Further, a cylindrical heater 4 made of T&S material is arranged around the crucible 2 in this chamber 1, and a cylindrical heat insulating member 5 made of carbon material is also arranged around the heater 4. An exhaust port 6 is opened at the bottom of the chamber 1.

Further, in the upper part of the chamber 1, a purge tube 9 for supplying inert gas is installed vertically extending from the upper part of the chamber 1 to near the melt surface in the crucible 2 so as to surround a pulled single crystal rod 14, which will be described later. The lower edge of the purge tube 9 is positioned below the upper edge of the crucible 2.

Incidentally, a crystal melt (in this embodiment, S1 melt) 10 is accommodated in the crucible 2. Further, a pulling shaft 11 faces into the chamber l from above through the inside of the purge tube 9, and the pulling shaft 11 is rotated and moved up and down by a drive mechanism (not shown).

However, in this embodiment, a gas guide tube 12 is arranged around the purge tube 9 and fixed to the upper outer periphery of the crucible 2. A short cylindrical portion 12 that airtightly fits on the outer periphery of the upper end.
a, and a ring-shaped disc 12b-1 that opens upward from the upper end of the short cylindrical part 12a in a funnel shape and whose upper end extends horizontally outward.
It consists of Note that this gas induction 11i12 is made of C, SiC
Or, it is made of SiC coach ink material, and the gap δ between the outer periphery of the song-shaped disc 12b-1 and the inner wall of the chamber 1 is large enough to block the flow of gas upward from the corner of the chamber 1. is limited to a small amount.

In order to pull up, for example, a single crystal rod 14 of Sl using the C7 method in the pulling device, Si material divided into appropriate sizes is put into the crucible 2, and the Si material is
A seed crystal 13 attached to a pulling shaft 11 is immersed in the surface of the Si melt 10 in the Lutuho 2, and the seed crystal 13 attached to the pulling shaft 11 is heated and melted by a heater 4. All you have to do is pull it up at the same speed.

In this case, an inert gas such as Ar gas is supplied into the chamber 1 from the purge tube 9, and this inert gas flows inside the chamber 1 in the direction of the arrow in the figure Φ.

On the other hand, vapors of carbon compounds such as CO are generated from the high-temperature parts of the heater 4 and the heat insulating member 5 made of carbon materials, or because the upper parts of the heater 4 and the heat insulating member 5 are covered by the gas guide tube 12, The vapor of carbon compounds such as CO does not rise and flow to the crucible 2 side, and the vapor of carbon compounds such as CO is discharged from the exhaust port 6 together with the inert gas without touching the Si molten MIO in the crucible 3. It is discharged to the outside of chamber 1.

As mentioned above, contact of the vapor of carbon compounds such as CO on the Si melt is prevented by the gas guide tube 12, and as a result, the single crystal rod 14 pulled up by the pulling device is suppressed to a temperature as low as 6 degrees. .

Moreover, as in this embodiment, the gas induction fa12 is changed to C, S.
Even if it is composed of iC or SiC coach ink material, SiO
Since contact between C and C can be avoided, it is possible to reliably lower the CE degree of the single crystal rod 14.

(Effects of the Invention) As is clear from the above description, according to the present invention, two chambers include a purge tube for supplying an inert gas, a crucible for accommodating the crystal raw material, and a heater disposed around the crucible. 1. In a single crystal rod pulling device which is configured by storing cut/1% members etc. arranged around the heater, pulling, F
A purge tube that concentrically surrounds the single crystal rod is extended from the upper part of the chamber to near the hot water level in the crucible, and the lower edge of the purge tube is positioned below the upper edge of the crucible; A short cylindrical part that airtightly fits around the outer periphery of the upper end of the crucible, and a link-shaped disc that opens upward from the upper end of the short cylindrical part in a funnel shape and whose upper end extends horizontally outward. A gas guide tube consisting of a flanged tapered tube section is provided, and a gap between the ring-shaped disk outer circumference of the gas guide tube and the inner wall of the chamber blocks the flow of gas upward from the lower part of the cylinder. Since the CO content of the single crystal rod being pulled is limited to a low level, it is possible to obtain the effect that the CO content of the single crystal rod being pulled can be kept low.

[Brief explanation of the drawing]

The drawing is a schematic vertical sectional view of a pulling device according to the present invention. l...Chamber, 2...Crucible, 4...Heater, 5...Insulating member, 9...Purge tube, 12...
...Gas guide tube, 12a...Short cylindrical part, 12b...
Tapered cylindrical portion with flange, 12b-1... Link-shaped disc, 14
... Medium crystalline forest. Patent applicant Shin-Etsu Semiconductor Co., Ltd.

Claims (2)

[Claims] (1) The chamber houses a purge tube for supplying inert gas, a crucible for storing crystal raw materials, a heater placed around the crucible, a heat insulating member placed around the heater, etc. In the single crystal rod pulling device,
A purge tube that concentrically surrounds the pulled single-crystal rod is extended from the upper part of the chamber to near the hot water level in the crucible, and the lower edge of the purge tube is positioned below the upper edge of the crucible; Consisting of a short cylindrical part that airtightly fits on the outer periphery of the upper end of the crucible, and a ring-shaped disc that opens upward from the upper end of the short cylindrical part in a funnel shape, and whose upper end extends horizontally outward. A gas guide tube consisting of a tapered cylindrical portion with a flange is provided, and the gap between the ring-shaped disk outer circumferential portion of the gas guide tube and the inner wall of the chamber is such that it blocks the flow of gas from the lower part of the chamber toward the h direction. A device for pulling a single crystal rod, characterized in that: (2) The single-crystal rod pulling device according to claim 1, wherein the gas guide tube is made of C, SiC, or a SiC coating material.