JPH03197386A - Preparation of compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enable to readily prepare a long single crystal by specifying the free surface area of a raw material-melted liquid in a cruicible. CONSTITUTION:A ring-like member 6 having the same outer diameter as the inner diameter (D0) of a cruicible 3 and further having an inner diameter defined by an equation: pid<2>/4<=S<=pid<2> (S is the free surface area of a raw material- melted liquid) based on the diameter d of a growing crystal is dispersed between the raw material-melted liquid 5 and a liquid sealant 4 received in the cruicible 3. A seed crystal attached to the tip of a lifting shaft 2 is immersed in the raw material-melted liquid 5 in the opening of the member 6 and the single crystal 1 is lifted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for manufacturing compound semiconductor single crystals by liquid confinement pulling method (CLEC method), and particularly relates to a method for efficiently manufacturing long single crystals. It is something. BACKGROUND OF THE INVENTION The LEC method is known to be a technique used for manufacturing single crystals of compound semiconductors such as GaAs, InP%GaP, etc., and is capable of obtaining 1-circular wafers at a high yield. L.E.
Regarding the size of the crucible diameter used in the C method, for the desired crystal diameter d, the crucible Do is 2d! 1 degree, and the crucible height is approximately equal to Do. In other words, the crucible size, the configuration of the furnace interior materials such as the heater, and even the furnace body size are determined with respect to the desired crystal diameter. On the other hand, increasing the length of the ingot to be manufactured is important for reducing the cost of the manufacturing process, and a technology is required to increase the amount of raw material charged for one single crystal manufacturing and to manufacture with high yield. [Problems to be Solved by the Invention] In the LEC method, for the purpose of increasing the length of a single crystal, a method of increasing the charge amount of raw materials for a crucible of the same diameter, or a crucible diameter A method of increasing the value is generally used. However, in these methods, it is necessary to change the equipment as the thickness of the raw material melt or the area of the melt changes. In other words, due to the relationship between the grown crystal diameter and the crucible diameter as described above, specifically, a manufacturing device for a 4-inch crucible is used for growing a 2-inch crystal, or a manufacturing device for a 6-inch crucible is used for growing a 3-inch crystal. It has been conventional practice to use manufacturing equipment such as In addition, the crucible diameter Do is D,>2 with respect to the grown crystal diameter d.
For example, when growing a 2-inch crystal from a 6-inch crucible under conditions such as d, as the free surface area of the melt increases during crystal growth, melt convection near the growth interface occurs. The growth interface shape changes, polycrystals, etc. occur during the growth, and it becomes difficult to achieve substantial lengthening. Conventionally, in order to control the diameter of a pulled single crystal, crystal growth was carried out by floating a ring-shaped jig with an inner diameter slightly larger than the diameter of the pulled crystal around the pulled crystal ( For example, JP-A-51-64482, JP-A-6
0-112696 etc.). However, these methods only focus on diameter control and do not take into account the heat dissipation balance from the surface of the raw material melt, and because there is an opening between the ring-shaped jig and the inner wall of the crucible, thermal Equilibrium has not been determined. In order to increase the length of the grown crystal in this way, it is necessary to increase the amount of raw material charge while creating a thermal environment in which single crystals can grow. Enabling this is effective for reducing device costs. It is an object of the present invention to solve these problems in a simple manner. [Means for Solving the Problems 1] The present invention provides an LEC method in which a ring-shaped jig is installed in a suspended state between the melt and the liquid sealant, and the inner diameter and tension of the ring-shaped jig are By setting the opening area (that is, the free surface area of the raw material melt in the crucible) between the upper crystal and the crucible to 1/4 This makes it possible to produce single crystals with a large diameter with a good yield.In other words, it makes it possible to grow long single crystals by effectively utilizing the increase in the amount of raw material charged due to an increase in the crucible diameter, and also enables the production of long single crystals with the same Since the diameter of the grown crystal from the manufacturing equipment can be arbitrarily selected, the degree of freedom of the manufacturing equipment is increased and it is possible to reduce the installation cost. This shows the state inside the crucible. Raw material melt 5 and liquid sealant 4
In between, the crucible 3 is housed with a ring-shaped jig 6 installed therein. The inner diameter of the ring-shaped jig 6 is determined from the relationship with the growth crystal diameter mentioned above, and the outer diameter is determined by the crucible 3.
It is desirable that the inner diameter is approximately equal to the inner diameter of the molten material 5, and that smooth movement in the vertical direction is possible as the raw material melt 5 decreases as crystal growth progresses. A seed crystal attached to the tip of the pulling shaft 2 is immersed in the raw material melt 5 at the opening of the ring-shaped jig 6, and the single crystal 1 is pulled up. A feature of the present invention is that a ring-shaped jig 6 is installed between the raw material melt 5 and the liquid sealant 4, and radiation is transmitted through the transparent liquid sealant 4 due to the heat insulation effect of the ring-shaped jig 6. By controlling the heat emitted from the surface of the raw material melt 5, it is possible to change the temperature distribution on the free surface of the raw material melt 5, which is involved in crystal growth, to a state suitable for the grown crystal diameter. It is important that the raw material melt free surface area S is set around the pulled crystal. For this reason, the outer periphery of the ring-shaped jig and the inner wall of the crucible are installed so as to be in contact with each other within a range in which the ring-shaped jig can move up and down. The relationship between the inner diameter of the ring-shaped jig and the pulled crystal diameter d is 1/4 x d''≦S≦Electrical d, where S is the free surface area of the raw material melt, which is the exposed area of the melted raw material.
Make it 1. Here, the relationship between S, D, and d is S=l/4°π(D”
-d"). The ring-shaped jig 6 used here is installed by a method of floating between the raw material melt 6 and the liquid sealant 4 by utilizing the density difference, as shown in FIG. In this case, as the crystal grows, the solid-liquid interface between the raw material melt and the growing crystal descends, so the crucible 3 is raised at a constant speed in order to keep the solid-liquid interface at the optimal position relative to the heating element. In this way, the ring-shaped jig 6 may be fixed to the furnace internal materials such as the heater placed around the crucible 3. However, if the ring-shaped jig 6 is fixed to the furnace internal materials such as the heater In the fixing method, it goes without saying that the ring-shaped jig needs to be installed in a predetermined position through crystal growth.As for the material of the ring-shaped jig 6 used,
PBN, PBN-coated graphite, etc. may be selected from the viewpoints of prevention of impurity contamination, density, etc. FIG. 2 shows the temperature distribution on the surface of the raw material melt in the conventional method Tal that does not use a jig and in the case (b) when a ring-shaped jig according to the present invention is installed. In the conventional method (a), since the temperature gradient in the radial direction of the crucible at the portion corresponding to the grown crystal diameter is low, during crystal growth,
Near the outer periphery of the crystal, as shown in FIG. 3(a), the growth interface shape locally becomes convex upward at the periphery of the crystal. for that,
Stress concentration occurs in that part, and polycrystals are likely to occur due to an increase in dislocations.In contrast, according to the method of installing the ring-shaped jig of the present invention in lb), the opening is The amount of heat dissipated through the tube increases, and as a result, a temperature distribution as shown in FIG. 2(b) can be created. As a result, the overall shape of the solid-liquid interface is smoothly convex downward as shown in Figure 3 (bl), which prevents polycrystalization due to stress concentration and enables the growth of long single crystals.1. 1 In the present invention, heat dissipation from the surface of the raw material melt is limited to only from the peripheral area of the pulled crystal, and moreover, the free surface area of the raw material melt, which is the exposed part of the raw material melt, is limited to a certain range with respect to the diameter of the pulled crystal. By setting to A GaAs single crystal was grown by the method of the present invention in which a ring-shaped jig is installed between the sealants.1
Approximately 8 kg of undoped GaAs raw material melt and liquid sealant B1 were placed in a PBN crucible with a diameter of 86 m5+ (approximately 7.3 inches).
01900 g, ring-shaped jig has a thickness of 2 mva
, the inner diameter is 120m5+ and the outer diameter is 2 from the crucible inner diameter.
- A small PBN molded body was used. In this case, the free surface area (S) of the raw material melt was 6769.8 mrr1", xd" = 18,136.6 mrn", 1/4
πd" = 4534, 2m rn'. Crystal rotation speed 10 rpm, crucible rotation speed 15 rpm.
Using a (100) oriented seed crystal, gradually raise the crucible and keep it at a constant position relative to the heating element, at a pulling rate of 9.
When a crystal with a diameter of 76 mm/hr was grown, a single crystal with a length of 250 mm+ was obtained. On the other hand, when crystal growth was performed under the same conditions using the conventional method without installing a ring-shaped jig, the length of the single crystal was 1.
It was not possible to grow crystals larger than 50 mm. Example 2 50su from a 152mm (approximately 6 inch) diameter crucible
Even when growing a GaAs single crystal with a diameter of about 2 inches, the method of the present invention can grow a single crystal with an outer diameter of 150 inches and an inner diameter of 94 inches, under conditions where the single crystal length did not exceed 100 inches in the conventional method. , by fixing a ring-shaped jig made of a PBN molded body with a thickness of 21111 mm in the crucible. It became possible to grow a single crystal of 230-1. In this case, the free surface area (S) of the raw material melt is 4974.8■-1πd2=
7850m rn', 1/4 x d'' = 1
It is 962.5 mm'. [Effects of the Invention] By producing crystals using the method of the present invention, it is possible to create a thermal environment at the growth interface suitable for the desired crystal diameter regardless of the crucible diameter used, increasing the flexibility of the production equipment. , it becomes possible to easily fabricate long single crystals.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of single crystal pulling, which is a specific example of the present invention.
FIG. 2 is a diagram schematically showing the temperature distribution on the surface of the raw material melt, and FIG. 3 is a diagram schematically showing the shape of the growth interface. In the diagram! al indicates the conventional example, (bl indicates the case of the present invention. l... Pulled single crystal 2... Pulling shaft 3... Crucible 4...・Liquid sealant 5 --- Raw material melt 6 --- Ring-shaped jig Fig. 1 Ka 2

Claims (3)

[Claims] (1) In the method of manufacturing a compound semiconductor single crystal by liquid-sealed pulling method, the opening part is only around the grown crystal, and the free surface area (S) of the raw material melt in the crucible is used, regardless of the crucible diameter D_o. π/4 for the grown crystal diameter d
A method for manufacturing a compound semiconductor single crystal, characterized in that d^2≦S≦πd^2. (2) The means for determining the free surface area of the raw material melt comprises floating a ring-shaped jig that makes sliding contact with the inner wall surface of the crucible between the raw material melt and the liquid sealant. A method for producing a compound semiconductor single crystal. (3) The means for determining the free surface area of the raw material melt is to install a ring-shaped jig that comes into sliding contact with the inner wall surface of the crucible between the raw material melt and the liquid sealant at a fixed position relative to the heating body. A method for manufacturing a compound semiconductor single crystal according to claim 2, characterized in that: