JPH0259484A - Device for growing single crystal - Google Patents

Abstract

PURPOSE:To clearly observe the shape of the interface between solid and melt during crystal growth by arranging an X-ray generator and an observation screen for a transmitted image so that they can be moved in directions parallel to the direction of growth of a crystal in a growth furnace. CONSTITUTION:The title device for growing a single crystal is composed essentially of a growth furnace 3 having an X-ray transmitting window, an X-ray generator 1 and an observation screen 2, etc. The generator 1 and the screen 2 are arranged so that they can be moved in directions parallel to the direction of growth of a crystal in the furnace 3. The interface between a crystal grown from a melt in the furnace 3 and the melt is irradiated with X-rays and X-rays passing through the melt are projected on the screen 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single crystal growth apparatus for growing crystals using the Czochralski method or the horizontal or vertical Bridgman method, and particularly relates to a single crystal growth apparatus for growing crystals using the Czochralski method or the horizontal or vertical Bridgman method. Relating to a single crystal growth device that is equipped with an X-ray generator and a light receiver that are movable horizontally or vertically in the body, and that allows the optical axis of both devices to be aligned with the solid-liquid interface. It is.

[Prior Art and its Problems] Conventionally, large-diameter single crystals have been produced by using the Czochralski method or the horizontal or vertical Bridgman method. . In that case, crystals with highly uniform impurity distribution are often required. It has been known that the cause of non-uniform impurity distribution is the deviation of the solid-liquid interface shape from a flat shape. Therefore, it is necessary to monitor the solid-liquid interface shape during crystal growth and control the shape.

Conventionally, as shown in FIGS. 5 and 6, an X-ray generator 1 fixed to a crystal growth apparatus and a fluoroscopic image observation screen 2 that are also fixed are used to monitor crystal growth using a fluoroscopic method. A method of observing the interface shape between the growing crystal and the melt by irradiating the crystal with X-rays is described in the "Journal of Crystal Growth"("J, Crystal Growth").
), published in 1986, vol. 76, p. 323 by Ozawa (s, Ozawa) and Futada (T, Fuk).
However, using this method, only when the solid-liquid interface 6 in the crucible 7 exists on the optical axis of the X-ray generator 1 and the observation screen 2 for fluoroscopic images, accurate The shape of the solid-liquid interface can be observed.

However, as shown in both figures, in actual crystal growth, as the melt solidifies, the position of the solid-liquid interface 6 moves from time to time.
When moves, the incident X-rays obliquely irradiate the solid-liquid interface 6,
As a result, the shape of the solid-liquid interface 6 could not be accurately seen on the observation screen 2, making it impossible to obtain a clear image of the solid-liquid interface shape.

In order to solve this problem, it is necessary to take measures to avoid moving the X-ray generator 1 and the observation screen 2 for fluoroscopic images to the position of the solid-liquid interface 6, which moves with crystal growth.

An object of the present invention is to solve such problems and to enable an X-ray generator and a fluoroscopic image observation screen attached to the side of the growth apparatus to move as the crystal grows. An object of the present invention is to provide a crystal growth apparatus that allows the shape of a solid-liquid interface to be clearly observed.

[Means for Solving the Problems] The present invention provides a growth furnace provided with a window that transmits X-rays;
A single crystal growth device comprising an X-ray generator that irradiates the interface between the crystal grown in the growth furnace and the melt, and an observation screen that projects the X-rays that have passed through the melt, This single crystal growth apparatus is characterized in that both the X-ray generator and the observation screen are movable in a direction parallel to the crystal growth direction within the growth furnace.

[Function] In the present invention, by providing an X-ray generator that can move in a direction parallel to the crystal growth direction in the growth furnace and an observation screen for fluoroscopic images, the solid-liquid Observe the shape of the solid-liquid interface as the position of the interface changes.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an embodiment of a single crystal growth apparatus using the horizontal Bridgman method in which both an X-ray generator and an observation screen are moved in the horizontal direction. In the figure, 1 is an X-ray generator, 2 is an observation screen for fluoroscopic images, 3 is a growth furnace, 4 is a rail for moving the X-ray generator, and 5 is a rail for moving an observation screen.

The growth furnace 3 is provided with a window that allows X-rays to pass through.

The X-ray generator 1 is arranged so as to face each other so as to irradiate the interface between the crystal grown in the growth furnace 3 and the melt, and the X-ray generator 1 is arranged to face each other so as to irradiate the interface between the crystal grown in the growth furnace 3 and the melt. Rail 4 has been laid. Observation screen 2 for perspective images
is also opposed to the growth reactor 3 on the side opposite to the X-ray generator 1 so that the X-rays transmitted through the melt are projected thereon, and is moved so as to be horizontally movable perpendicular to the opposing direction. A rail 5 has been installed.

Using such a system, we grew silicon crystals and observed changes in the solid-liquid interface shape as the crystals grew.

The growth material was silicon, and a single crystal 8 with a diameter of 2 inches was grown from a quartz crucible 7 with a diameter of 4 inches by the horizontal Bridgman method. The voltage and current applied to the X-ray generator at this time were 160 KV and 3 mA, respectively. Figure 2 shows the change in solid-liquid interface shape during growth.
As is clear from this, it was confirmed that even if the position of the solid-liquid interface 6 changes as the crystal grows, it is possible to obtain a clear image of the solid-liquid interface shape.

FIG. 3 is a block diagram showing another embodiment of the present invention, showing an embodiment of a single crystal growth device using the Czochralski method in which both the X-ray generator and the observation screen are moved in the vertical direction. There is. In the figure, 1 is an X-ray generator, 2 is an observation screen for fluoroscopic images, 3 is a growth furnace, 4 is a rail for moving the X-ray generator, and 5 is a rail for moving an observation screen.

The growth furnace 3 is provided with a window that allows X-rays to pass through.

In addition, at a position relative to the center of the outer wall of the growth reactor 3, 2
Two vertical movement rails 4 and 5 are laid, the movement rail 4 on the left side of the figure is for moving the X-ray generator 1, and the movement rail 5 on the right side of the figure is for observation of perspective images. It is used for moving the screen 2. The X-ray generator 1 irradiates the interface between the crystal grown in the growth furnace 3 and the melt with X-rays, and can move up and down. The observation screen 2 for perspective images is projected with the X-rays that have passed through the melt, and can also be moved up and down.

Using such a system, silicon crystals were grown using the Czochralski method under the same conditions as in the example shown in Figure 1.
When we observed the changes in the solid-liquid interface, we found that the shape of the solid-liquid interface changed as shown in Figure 4. Even if the position of the solid-liquid interface changes as the crystal grows, the shape of the solid-liquid interface changes. It was confirmed that it is possible to obtain clear images of 1q.

As described above, according to the present invention, the shape of the solid-liquid interface during crystal growth can be clearly observed by moving the X-ray generator and the observation screen for fluoroscopic images as the position of the solid-liquid interface moves. becomes possible.

In addition, although the case of a silicon single crystal was taken up and explained in the example, the present invention can also be applied to the single crystal growth of other semiconductors, and the semiconductor in that case may be InP.
It is clear that the present invention is applicable not only to compound semiconductors such as GaAs and GaAs, but also to elemental semiconductors such as germanium.

[Effects of the Invention] As explained above, according to the present invention, the X-ray generator and the observation screen attached to the side of the growth apparatus can be moved as the crystal grows, and the solid-liquid during crystal growth can be moved. It is possible to provide a single crystal growth apparatus that allows the interface shape to be clearly observed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of changes in solid-liquid interface shape according to the embodiment, FIG. 3 is a block diagram of another embodiment of the present invention, and FIG. The figure is an explanatory diagram of the change in the shape of the solid-liquid interface according to the embodiment, and FIGS. 5 and 6 are explanatory diagrams of the conventional example. 1... X-ray generator 2... Observation screen 3.
...Growth furnace 6...Solid-liquid interface 8...Single crystal 4.5...Transfer rail 7...Crucible

Claims (1)

[Claims] (1) A growth furnace equipped with a window that transmits X-rays, an X-ray generator that irradiates the interface between the crystal grown in the growth furnace and the melt, and the X-rays that have passed through the melt. In a single crystal growth apparatus comprising an observation screen for projecting a A single crystal growth device featuring: