JPH0442888A - Apparatus for growing crystal - Google Patents

Abstract

PURPOSE:To prevent balance in vapor pressure from its being disturbed by providing a product drop-preventive tool between a carrier part for a raw material melt container and a reservoir. CONSTITUTION:A container 3 for containing a raw material melt is placed in the bottom of a large-diameter part (la) on a cylindrical heat-resistant container 1 having a heater 2 arranged on the outer periphery thereof. A vapor supply source 4 is sealed in the bottom of a small-diameter part (1b) to construct a reservoir 11 from the small-diameter part (1b) and the heater 2. A product drop preventive tool 6, having plural shielding plates (6a) projected from the inner wall at a regular interval in the direction to intersect the axis at right angles and provided with through-holes (6b) between the shielding plates (6a) and the inner wall surface is then inserted between the reservoir 11 and the container 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to single crystal manufacturing technology and crystal growth technology by vertical Bridgman method or vertical slow cooling method, such as C
The present invention relates to a technique that is effective for growing compound semiconductor single crystals such as dTe, in which constituent elements have greatly different vapor pressures.

[Prior Art] Conventionally, as a method for manufacturing a II-VT group compound semiconductor single crystal such as CdTe, the horizontal Bridgman method (HB method) is used.
The vertical Bridgman method, the vertical slow cooling method, etc. are used. When growing crystals from a CdTe melt using any of the above methods, the Cd vapor pressure is nearly an order of magnitude higher than the Te vapor pressure, so polycrystalline CdTe with a chemical equivalent ratio is used as a raw material to match the chemical equivalence ratio. Even if pure Cd is used, Cd will escape from the melt. As a result, the composition tends to have an excess of Te, and clusters in which the excess Te gathers may be formed in the crystal. When epitaxial growth is performed using a crystal containing such clusters as a substrate, there is a drawback that defects are generated in the epitaxial layer. Therefore, we needed a container to hold the melt and a supply source for Cd vapor (hereinafter referred to as
A method has been proposed in which a Cd reservoir (referred to as a Cd reservoir) is provided in the same system and the Ccl vapor pressure is controlled by controlling the temperature of the Cd reservoir, thereby controlling the composition of the melt.

[Problem to be solved by the invention] Using this method, it is possible to produce a crystal with few Te clusters, but it is not possible to grow a CdTe single crystal using a crystal production apparatus that applies the vertical slow cooling method as shown in Fig. 3. In this case, since the vapor pressure of Te is relatively high, some Te will escape from the melt, and this Te vapor and Cd vapor supplied from the reservoir will react between the part where the melt is placed and the Cd reservoir. and may adhere to pipe walls. This abnormally grown deposit (CdTe) 8 may fall into the Cd reservoir part 11 due to its own weight, and Te may be included in the steam replenishment source 4 (Cd), causing fluctuations in vapor pressure and making Te clusters more likely to occur. It turns out that there is a drawback.

The present invention has been made in view of the above-mentioned problems, and its purpose is to improve the vapor supply in the reservoir when growing a compound semiconductor single crystal using a vertical crystal manufacturing apparatus having a reservoir. It is an object of the present invention to provide a crystal manufacturing technology that can prevent other constituent elements from being mixed into a source element and can grow a high-quality single crystal.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a vertical crystal manufacturing apparatus equipped with a reservoir, in which between the part where a container containing the raw material melt is placed and the reservoir, For example, a product fall prevention device is provided that has a plurality of shielding plates formed so that the through parts do not overlap with each other.

[Operation] According to the above-described means, even if the reaction product adhering to the wall between the melt container placement part and the reservoir comes off, it can be prevented from falling into the reservoir by the fall prevention device, This prevents the vapor pressure from becoming unbalanced due to mixing of other elements with the element serving as the vapor supply source in the reservoir, making it possible to produce high-quality single crystals.

[Example] FIG. 1 shows an example of a crystal growth apparatus that grows crystals by applying a vertical slow cooling method.

In this embodiment, a cylindrical heat-resistant container 1 made of quartz is arranged vertically, and a heater 2 is arranged around its outer periphery. The heat-resistant container 1 consists of an upper large-diameter part 1a and a small-diameter part 1b integrally provided at the lower part of the large-diameter part 1a.A container 3 for holding the raw material melt is placed in the lower part of the large-diameter part 1a, and a small-diameter part 1b is placed in the lower part of the large-diameter part 1a. An element 4 as a steam supply source is sealed in the lower part, and a reservoir 11 is constituted by the small diameter portion 1b and the heater 2 on the outside.

On the other hand, the heater 2 is divided into a plurality of parts along the vertical direction, and the uppermost heater 2a is configured to form a temperature distribution that is high at the top and low at the bottom.

Furthermore, the heater 2b at the bottom can independently heat the element 4 as a steam replenishment source to a predetermined temperature so that the inside of the heat-resistant container 1 reaches a desired steam pressure.

A quartz cap 5 is fitted onto the top of the heat-resistant container 1 to make the inside airtight, and the cap 5 is welded to the inner wall of the heat-resistant container 1 using a burner or the like.

Moreover, when the raw material holding container 3 is installed at a predetermined position,
In order to supply gas from the lower glue reservoir 11 into the large diameter section la, a groove or an uneven surface is formed on the upper surface of the bottom wall of the large diameter section 1a, so that a gap is formed between it and the bottom surface of the container 3. It is made to occur.

In this embodiment, a substantially cylindrical product drop prevention device 6 made of quartz is installed in the middle of the small diameter portion 1b of the container 1, that is, between the steam replenishment element 4 is installed and the reservoir 11 and the raw material holding container 3. is now inserted.

As shown in FIG. 2, this product fall prevention device 6 is provided with a plurality of shielding plates 6a protruding from its inner wall at equal intervals in a direction perpendicular to the axis, and each shielding plate 6a has a tip. The shielding plates 6a have a substantially semicircular shape that protrudes outward from the center, and the shielding plates 6a are alternately arranged in opposite directions so that the gaps between the tips of the shielding plates 6a and the inner wall surface, that is, the through holes 6b do not overlap with each other. It is provided. As a result, the vapor of the constituent elements heated and generated in the reservoir 11 is quickly supplied to the upper space of the heat-resistant container 1 through the gap between the product fall prevention plates 6. The constituent element gas and the vapor pressure replenishment gas react in the space between the product drop prevention plate 6 and the container 3 placement part, and the resulting product adheres to the wall surface, and is caused by its own weight and vibration. Even if it peels off and falls, there is no risk of it getting mixed into the element 4 in the reservoir 11 because of the product fall prevention device 6. In addition, it is preferable to form a protrusion on the inner wall of the small diameter part 1b or to form the small diameter part 1b in a conical shape so that the product fall prevention tool 6 inserted into the small diameter part 1b is stopped halfway. .

As an example, a CdTe single crystal was grown using the apparatus shown in FIG.

First, Cd with a purity of 6N is placed on the bottom of the small diameter part 1b of the heat-resistant container l.
After putting in 1 og of CdTe polycrystal and inserting the product fall prevention device 6, the container 3 containing about 1.5 kg of pre-synthesized CdTe polycrystal.
was placed on the lower part of the large diameter portion 1a. Thereafter, the inside of the heat-resistant container 1 was evacuated, and the quartz cap 5 was fitted onto the upper part of the large diameter portion 1a, and welded with a burner.

After that, the heat-resistant container 1 is placed in a furnace having a heater 2, and power is supplied to the heater 2 so that the vicinity of the large diameter portion 1a becomes 1.
It has a temperature gradient of ~1.5°C/CT11, and CdTe
The temperature was raised so that the temperature distribution was such that the upper part was higher than the lower part above the melting point. Also, reservoir 11 is 77
It was heated with the heater 2b to a temperature of 5 to 805°C, and the Cd vapor pressure in the heat-resistant container 1 was set to 1.2 to 1.5 atm. Under the above conditions, the temperature distribution in the furnace was stabilized over 50 hours after the start of power supply to the heater, and then the temperature was gradually lowered while maintaining the above temperature gradient, and crystallization was performed over about 200 hours.

As a result, a CdTe single crystal with a diameter of 3 inches and a length of 60 mm was obtained. Further, when the Cd in the reservoir 11 was analyzed, it was found that Te was not contained therein. For comparison, after crystal growth under the same conditions using the conventional apparatus shown in Figure 3, which does not use a device to prevent product fall, Cd was taken out from the reservoir and analyzed.
It contained e.

Note that the product fall prevention device 6 of the above embodiment may be formed as a single piece, but it is preferable that the product fall prevention device 6 is formed into two parts along the axial direction and set in the heat-resistant container l in a joined state. You can.

In addition, instead of using a semicircular plate as the lever shielding plate 6a with an inclination to the shielding plate 6a, one or two semicircular plates may be used at positions that do not overlap with each other.
It may also be a circular plate with three or more through holes formed therein.

Furthermore, the product fall prevention device 6 may be formed integrally with the heat-resistant container 1.

In the above embodiment, the growth of a CdTe single crystal was explained as an example, but the present invention is not limited thereto. It can be applied when manufacturing by method or vertical slow cooling method.

Further, the present invention can also be used in a crystal pulling apparatus using the LEC method to which the vapor pressure control method is applied.

[! [Effect of Akira] As explained above, the present invention provides a vertical crystal manufacturing apparatus equipped with a reservoir, in which there is, for example, a penetrating portion between the partial reservoir and the container on which the container containing the raw material melt is placed. Since a product fall prevention device is provided that has a plurality of shielding plates arranged so as not to overlap, even if the reaction products attached to the wall between the melt container placement part and the reservoir come off, they will not fall. The tool prevents the element from falling into the reservoir, which prevents other elements from mixing with the element in the reservoir as a vapor supply source and causing an imbalance in vapor pressure, producing high-quality single crystals. It has the effect of being able to

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view showing an embodiment of a crystal growth apparatus according to the present invention, and FIGS. 2 (A) and (B) are a cross-sectional front view and a plan view showing an example of a product fall prevention device used therein. , FIG. 3 is a cross-sectional front view showing an example of a conventional crystal growth apparatus. l... Heat-resistant container, 2... Heater, 3... Container for holding melt, 4... Element for steam replenishment (Cd), 5...
...Cap, 6.Product fall prevention device, 11.
...Reservoir diagram

Claims (1)

[Claims] (1) A steam replenishing means is connected to a heat-resistant container arranged vertically, and the steam replenishing means supplies vapor of the constituent elements while heating a raw material holding container installed in the heat-resistant container to supply raw materials. A crystal growth apparatus for growing a single crystal after melting, characterized in that a product fall prevention means is provided above the steam supply means.