JPS60264391A - Crystallizer - Google Patents

Abstract

PURPOSE:In a crystallizer where a crystal is allowed to grow, as the temperature of the melt heated is controlled in the crucible, the structure of the heater is specified to inhibit the factors relating to the qualities of the cystal from flacuating whereby crystals of good qualities are obtained. CONSTITUTION:Two or more heater elements 6, 7 are arranged vertically in plural stages, e.g., 2 stages. The heaters 6, 7 in each stages is composed of a plurality of elements and the elements are connected triangularly as anticlockwise shown in the figure and the 3 terminals of the upper heater R1(6) are connnected to three-phase power source in the order of U-V-W. Further, other 3 terminals of the lower heater R2(7) are connected to another 3-phase electric source in the order of U-W-V. Crucibles 2, 3 are heated with heaters 6, 7 and the temperature is controlled to allow the crystal on the surface of the melt to grow outside the melt 1. At this time, the melt is influenced by the magnetic field to rotate in different directions in the upper part and in the lower part to improve the quality of the crystal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a crystal manufacturing apparatus for growing crystals by solidifying component chemicals from a melt. [Prior Art and Problems thereof] In recent years, semiconductors have been As devices are used in large quantities and in a wide variety of fields, the characteristics required of semiconductor devices are diversifying, and more sophisticated structures are being required. Increasingly, a high degree of controllability and efficiency are required. Furthermore, in order to meet these demands, the crystals that form the basis of semiconductor devices are required to have a high degree of uniformity, integrity, and impurity control.

As an example of growing a crystal from a melt, a conventional apparatus will be described using a single crystal growth of gallium arsenide, which is composed of elements of groups (1) and (2) of the periodic table, by the melt-sealed Czochralski method. In FIG. 6, 1 is a crystal growth host melt, 2
3 is a crucible made of quartz or boron nitride, 3 is a carbon crucible, 4 is a sealed melt phase, and 5 is a grown crystal. Further, 8 is a ring-shaped heating element that heats the crucible from the entire circumference.

Since gallium arsenide single crystal growth involves arsenic with a high vapor pressure under temperature conditions near the freezing point of gallium arsenide, a low melting point glass substance such as boron oxide (
A sealed melt phase 4 made of B203) is provided, and crystal growth is performed while an inert gas is supplied to the inside of the growth container P to keep the inside at a pressure sufficient to suppress evaporation of arsenic. In such a situation, the factors that greatly affect the quality of the crystal are temperature and its source, heat transfer, especially the temperature of the GaAs melt, which is the mother liquid for crystal growth, and its changes, the sealing melt - near the mother liquid interface, and the mother liquid.
This is the temperature gradient near the crystal interface and near the sealing melt-air interface inside and outside the container. However, conventionally, the temperature is controlled using a single heating element, so there is a limit to controlling the temperature distribution in the direction of crystal growth.Moreover, it is not possible to control mass and heat transfer due to convection within the melt, resulting in crystallization. Unable to improve the quality of /ζ.

[Purpose of the invention]

The present invention solves the above-mentioned problems and provides a crystal manufacturing apparatus that suppresses fluctuations in factors that affect the quality of crystals and obtains high-quality crystals.

[Structure of the invention]

The present invention is characterized by arranging two or more heating elements along the outer periphery of the crucible, providing multiple stages above and below, and connecting the heating elements in the upper and lower stages to a multi-phase power source with opposite phases. This is a crystal manufacturing device.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a crucible 2 containing a melt 1 is supported by a carbon crucible 3, similar to the conventional method.

In the figure, in the present invention, two or more heating elements 6, 7 are used,
The heating elements 6 and 7 are arranged above and below the outer periphery of the crucibles 2 and 3. Although the illustration shows a case in which the heating elements are arranged in two stages, upper and lower, the present invention is not limited to this. Figure 2 (a), (
As shown in b), since there are two or more heating elements 6.7 in each stage, these heating elements R1,...R2...(6,7)
△ for each stage, connect the three terminals of the upper heating element R1 (6) counterclockwise to the three-phase power supply 9a in the order of U-V-W phases, and connect the lower heating element R2(
Connect the three terminals of 7) to the three-phase power supply 9b in the order of U-W-■ phases.

Specific examples of the heating elements 6 and 7 are shown in FIGS. 3(a) and 3(b).

As shown in the figure, each of the heating elements 6 and 7 consists of a linear carbon resistor formed in a cylindrical shape while meandering up and down, and each has a terminal 6a at a position dividing the length in the circumferential direction into three equal parts.

6b, 6c+7a, and 7b+7c are provided, and are connected to a three-phase power source through each terminal.

By heating the crucible with heating elements 6 and 7 and controlling the temperature, the crystals grown on the surface of the melt 1 are grown through the sealing melt phase 4 and grown out of the melt as crystals 5. . This point is the same as before.

In the present invention, the heating elements 6 and 7 are connected in a Δ manner, and the upper and lower stages are connected to the three-phase power supplies 9a and 9b so that the phases are opposite to each other. The current generates a three-phase rotating magnetic field in opposite directions in the crucible, and as shown in FIG. 4, under the influence of this magnetic field, the melt 1 in the crucible 2 is induced to rotate in different directions at the top and bottom. Therefore, according to the present invention, 1) the macroscopic temperature distribution in the melt and the crystal can be adjusted to a desired temperature distribution by controlling the amount of heat generated from both the upper and lower heating elements 6 and 7 and the electric power applied thereto; become. 2) Material and heat transfer due to convection within the melt is achieved by dividing the melt into upper and lower parts by a three-phase rotating magnetic field in opposite directions generated by currents of each phase applied to the heating element, as shown in Figure 5. This is suppressed by inducing rotation in different directions.

In addition, although the melt-sealed Czochralski method using a Δ-connection type two-stage three-phase heating element has been described in the embodiment, the present invention is not limited thereto. For example, the rotating magnetic field may be generated by a two-phase power source or a four-phase power source or more. Further, the present invention can be applied to, for example, the Bridgman crystal method, the ordinary Czochralski method under normal pressure or reduced pressure, and the like.

〔Effect of the invention〕

As explained above, the present invention controls the temperature by arranging heating elements divided in the circumferential direction in multiple stages above and below the outer periphery of the crucible, and generates a rotating magnetic field by connecting the heating elements to a multiphase power source. Since the movement of the melt is controlled by controlling the temperature distribution in the direction of crystal growth, it is possible to maintain better temperature uniformity in the plane perpendicular to the crystal growth.
In addition, it is possible to suppress the movement of impurities due to convection, and in particular, it has the effect of avoiding imperfections in the grown crystal caused by thermal distortion due to the steep temperature gradient near the crystal growth interface.

[Brief explanation of drawings]

゛Figure 1 is a configuration diagram showing one embodiment of the present invention, Figure 2 (a
), (b) is a wiring diagram of the heating element, FIG. 3(a) is a perspective view showing the specific structure of the heating element according to the present invention, (b) is a plan view thereof, and FIG. 4 is a rotation of the melt. FIG. 5 is a diagram showing the movement of substances in the melt, and FIG. 6 is a diagram showing the configuration of a conventional device. 2.3... Crucible, 6,7... Heating element, 9a,
9b... Three-phase power supply patent applicant NEC Corporation Figure 1 Figure 2

Claims (1)

[Claims] (1) In a crystal manufacturing device that controls the heating temperature of the molten liquid in the crucible and solidifies component chemicals in the nuclear liquid to grow crystals, two or more heating elements are arranged along the outer periphery of the crucible. 1. A crystal manufacturing apparatus characterized in that a plurality of upper and lower stages are provided, and the heating elements of the upper and lower stages are respectively connected to multiphase power supplies with opposite phases.