JPH0196086A - Compound crystal pulling device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to the production of compound crystals, such as CdTe, C! d1 zZnxTI3 , 0d1-
The present invention relates to an apparatus for pulling cadmium compound crystals such as MnXTe #OdS 8xT e 1-e and the like.

[Conventional technology]

Conventional hot-wall method-based compound crystal pulling equipment includes a device that pulls crystals from a raw material melt in a growth chamber that integrates a bell and a crucible (Japanese Patent Laid-Open No. 125585-1985).
(Japanese Patent Laid-Open No. 60-255), which similarly pulls crystals from a crucible in a growth chamber that can be separated into upper and lower
No. 692), which has a sealing portion at the portion where the pulling shaft passes through the growth chamber and at the connection portion between the upper and lower growth chambers. Liquid sealants such as E and OL are used in these seals, but the liquid that flows down the pulling shaft spreads as vapor and mixes into the raw material melt, causing problems in the pulling process. It becomes an impurity in the upper crystal.

In particular, when a cadmium compound is pulled up using the above-mentioned equipment, if the sealing agent Etas is mixed into the raw material melt, pB will be incorporated into the melt through the reaction of the following equation, and it will become an impurity in the cadmium compound crystal. This impairs the properties of the crystal.

B, O, + sea (in Pit liquid) 'F” 5 (
! do (solid) + 2E (in melt) [Problems to be solved by the invention] The present invention solves the above problems and provides means for preventing the sealant from being mixed into the raw material melt. The object of the present invention is to provide a pulling device that can easily produce high-purity compound crystals using the real wall method.

[Means for solving problems]

FIG. 1 shows a specific example of the present invention, in which inside a high-pressure vessel 1,
A growth chamber 6, which is a combination of a crucible and a bell that accommodates 2 ft of raw material melt, is placed. The crucible can be formed by housing a quartz crucible 4 in a carbon crucible 5. It is preferable that the bell has a double structure and is fixed to the crucible with a constant gap between the bells. An annular groove 7 for accommodating the liquid sealant 6 can be provided around the carbon crucible 5 either integrally with the crucible 5 or in a fitted manner. The lower end of the outer bell 8 is immersed in the liquid sealant 6 in the annular groove 7 to maintain airtightness. Further, an annular convex portion 9 is provided at the middle of the outer periphery of the carbon crucible 5 and is integrated with the inner wall of the outer bell 8 by rubbing, so that the bell can be rotatably supported by the crucible shaft 10 together with the crucible. This alignment prevents the liquid sealant evaporated from the annular groove 7 from flowing into the growth chamber 3. The lower end of the inner bell 11 forms an overlap with the upper outer periphery 12 of the carbon crucible #Y5 to maintain airtightness. An annular groove 1st for accommodating the liquid sealant 13 is provided on the outer periphery of the neck above the outer bell 8,
On the other hand, a lifting shaft 16 is placed above the neck of the inner and outer sides of Be/l/8 and 11.
A saucer 19 for penetrating the liquid sealant 17 and accommodating the liquid sealant 17 is provided separately from the bell, and an annular leg 19 of the saucer 18 is provided with a lower end immersed in the liquid sealant 13 in the annular groove 15 of the outer pel 8. (by attaching it to the bottom) it forms a seal part. Below the opening of the saucer 18 that passes through the lifting shaft 16, there is a
liquid sealant 17 from the saucer 18.
It is preferable to attach a cylinder 2o with a gap between it and the pulling shaft to prevent the liquid from flowing down. 9. The upper end of the inner bell 11 extends upward from the upper end of the outer bell 8],
It comes into contact with the bottom of the saucer 18. Further, a main heater 21 is arranged around the crucible, an auxiliary heater 22 is arranged around the sealing part of the pulling shaft 16, and a view rod 23 for monitoring the state of crystal growth is arranged in the high pressure chamber 1. It is attached through.

Note that gas-impermeable heat-resistant materials such as AtM, 811N4°day 1C, glassy carbon, and PEN can also be used as the crucible material, and these materials can be integrally molded or the surface can be coated with these materials. You can also do that.

[Function] In the conventional pulling device using the real wall method, (1) the liquid sealant flows down from the sealing part of the pulling shaft; and (2)
The problem was that sealant vapor got mixed in from the connection between the upper and lower growth chambers and the connection between the bell and the crucible.

Regarding (1), the gap between the opening of the saucer containing the liquid sealant and the pulling shaft could not be made sufficiently narrow for the following reasons. That is, since the centers of the pulling shaft and the opening cannot be perfectly aligned, some play is required between the pulling shaft and the opening to allow for the center deviation. Further, the lifting shaft and the receiving plate undergo relative sliding movement, such as rotation and vertical movement, in the opening. Although the pulling speed is about several days per hour, the rotation speed exceeds 10 revolutions per minute, so if resistance to rotation occurs, the seal part will be strained and may be damaged. Further, this resistance causes the pulling shaft to vibrate, thereby inhibiting crystal growth.

From this point of view as well, the above play is necessary.

The present invention adopts a structure in which the annular leg of the saucer is immersed in the liquid sealant in the annular groove on the upper part of the outer bell, so this structure can replace the function of the play, and as a result, the pull There is no need to increase the gap between the upper shaft and the opening of the saucer, for example, by about 100 to 200 pm.
Since it can be narrowed, it is possible to sufficiently prevent the liquid agent from flowing down. However, if this interval is made even smaller, there is a risk that the pulling shaft will pull up the tray and break the airtightness. This phenomenon depends not only on the size of the gap between the pulling shaft and the tray opening, but also on the weight and lifting speed of the tray.

Incidentally, in order to ensure a more reliable seal between the pulling shaft and the tray, a cylinder that maintains a sufficiently narrow gap with the pulling shaft may be attached below the opening of the tray.

In addition, by adopting the above-mentioned pulling shaft seal structure, the inner diameter of the neck above the bell (ft crystal) can be increased, so that the crystal can be easily pulled out through the neck after crystal formation. be able to.

As for (2), there was some luck in that the sealing agent close to the main heater was exposed to considerably higher temperatures than the sealing portion of the pulling shaft, so the sealant evaporated and flowed into the growth chamber.

In the present invention, the bell has a double structure, the lower end of the inner bell is aligned with the outer periphery of the crucible, and the lower end of the outer bell is immersed in a liquid sealing agent in an annular groove surrounding the crucible, so that a seal is generated from the annular groove. Even if the sealant vapor rises through the gap between the two bells, it condenses in the upper relatively low temperature area and flows down the gap again, so that the sealant vapor does not flow into the growth chamber. Further, an annular convex portion may be provided around the crucible and aligned with the inner wall of the outer bell to prevent the sealant vapor from rising into the gap between the bells. Furthermore, by extending the upper end of the inner bell above the upper end of the outer bell and contacting the bottom of the saucer, it is also possible to prevent sealant vapor from flowing into the inner bell, ie, into the growth chamber. This structure prevents liquid sealant from flowing into the growth chamber by the high upper end wall of the inner bell even if the liquid sealant in the annular groove above the outer bell is accidentally pushed due to the pressure difference between the high-pressure container and the growth chamber. Can be done.

The present invention thus enables smooth rotation and pulling of the pulling shaft, facilitates the removal of the growing crystal, and prevents sealant vapor and liquid sealant itself from flowing into the growth chamber. As a result, it has become possible to reliably produce high-purity compound crystals without contaminating impurities by the hot wall method.

〔Example〕

A 0dTe crystal was pulled using the apparatus shown in FIG.

The crucible has a surface 1r: diameter 6 coated with SiC.
A 4-inch quartz crucible was housed in a 4-inch carbon crucible. The inner and outer bells were made of quartz.

The quartz rutsuho is charged with about t2 yen of 0dTe raw material,
The annular groove on the outer periphery of the crucible was charged with ri200f BIO3t, the saucer was charged with 209 BIO, and the annular groove on the outer bell neck was charged with 5090E and O. The CD vapor pressure in the growth chamber is 1.2 atm, and the pressure in the high pressure vessel is 11! Make sure the gas pressure is 6 atm.

The conditions for pulling the crystal were that the rotation speed of the pulling shaft was 3 rpm, the rotation speed of the crystal shaft was 1 Orpm, and the pulling speed was 3 gourds/Hr.

The pulled Od'I'θ single crystal has a diameter of 48 m and a length of 6 c.
m, and when the B concentration was analyzed by secondary ion mass spectrometry (SIME), it was found to be 1 × 101 scW over the entire crystal.
It was 1-3 or less.

For comparison, a CdTe crystal was pulled under the same pulling conditions as above using a conventional apparatus of the type described in JP-A-54-123585.

When the obtained crystal was analyzed by S Engineering MS at BIl at 9 degrees, it was found to be 6 x 10'' to 4 x 10''tv-''.

Comparing these results, it can be seen that the CdTe crystal of the above example was able to significantly reduce the B concentration.

〔Effect of the invention〕

By employing the above configuration, the present invention can prevent the sealant from being mixed into the raw material melt, and can reliably produce high-purity compound crystals.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a crystal pulling apparatus which is a specific example of the present invention.

Claims (4)

[Claims] (1) Suitable for the hot wall method, in which a growth chamber consisting of a crucible containing a raw material melt and a bell is placed in a high-pressure container, and compound crystals are pulled up using a pulling shaft that penetrates the seal at the top of the bell. In the lifting device, an annular groove for containing a liquid sealant is provided around the crucible, the bell is composed of an inner bell and an outer bell, a substantially constant gap is provided between the two bells, and the two bells are is provided with a neck extending upwardly through the pulling shaft, the lower end of the outer bell is placed in a position to be immersed in the liquid sealant in the annular groove around the crucible, and the neck above the outer bell has an annular groove that accommodates the liquid sealant. The lower end of the inner bell is rubbed against the outer periphery of the crucible to maintain airtightness, a lifting shaft is passed through the upper part of the neck of the two bells, and a saucer for storing liquid sealant is provided around the bell. A compound crystal pulling device characterized in that the growth chamber is kept airtight by attaching an annular leg portion whose lower end is immersed in a liquid sealant in an annular groove of an outer bell neck. (2) By extending the upper end of the inner bell longer than the upper end of the outer bell and bringing it into contact with the bottom of the saucer of the pulling shaft seal,
The pulling device according to claim 1, characterized in that it prevents a sealant from entering the growth chamber. (3) A cylinder that allows the lifting shaft to be pulled up and has a gap between it and the lifting shaft that prevents the liquid sealant from flowing down is attached below the lifting shaft through-hole of the saucer. A lifting device according to claim 1 or 2. (4) The pulling according to claim 1, 2, or 3, characterized in that an annular convex portion is formed on the middle outer periphery of the crucible, and airtightness is maintained by rubbing against the inner wall of the outer bell. Device.