JPS60191093A - Manufacture of single crystal - Google Patents

Abstract

PURPOSE:To grow the titled crystal stably for many hours by measuring the diameter, height, and external shape of the molten zone by using plural line sensors, and feeding the measured values back to the lamp power in the manufacture of single crystals by the Fz method. CONSTITUTION:A raw material rod 6 is set to the upper shaft 9, and a seed crystal 7 is set to the lower shaft 10. The power of a halogen lampe 2 is increased, and the light of the halogen lamp 2 is concentrated on the central part of a quartz tube 3 by a rotary ellipsoidal mirror 1. An atmospheric gas is introduced at this time from an introducing port 4, and discharged from a discharge port 5. The raw material rod 6 and the seed crystal 7 are melted at the concentrated part, and brought into contact with each other to form a molten zone 8 which is moved downward while rotating the upper and lower shafts 9 and 10 to grow the crystal. The diameter, height, and external shape of the molten zone 8 in said operation are measured by using plural line sensors, and the measured values are fed back to the lamp power to control the growth of the crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a single crystal by the FZ method (floating zone method), and particularly to improvements in automatic control.

[Prior art]

Conventionally, automatic control in the FZ method has hardly been performed, and a crystal manufacturing method using a single line sensor or a Rin area sensor has been proposed.

However, using a single line sensor does not provide enough information from the melting zone. When a father-type area sensor is used, the resolution in the diametrical direction is as low as one-fifth that of a line sensor.

For the above reasons, it cannot be said that controllability is necessarily excellent, and it is impossible to stably grow crystals for a long period of time.

〔the purpose〕

The present invention is intended to solve the above problems, and its purpose is to provide a method for producing a single crystal that allows stable crystal growth for a long period of time (10 hours or more).

〔overview〕

The single crystal manufacturing method of the present invention uses a combination of a plurality of 2-in sensors or a line sensor and an area sensor,
It is characterized by measuring the diameter, height, and external shape of the molten zone and feeding this back to the lamp power or the height of the molten zone.

FIG. 1 shows the main points of the yz method of the present invention.

Here, 1 is a spheroidal mirror, 2 is a norogen lamp, 3 is a quartz tube, 4 is a gas inlet, 5 is a gas outlet, 6 is a raw material rod, 7 is a seed crystal, 8 is a molten zone, and 9 is an upper part The shaft 10 is a lower shaft.

The raw material rod 6 is set on the upper shaft 9, and the seed crystal 7 is set on the lower shaft 10.

The power of the halogen lamp 2 is increased, and the spheroidal mirror 1 focuses the light from the halogen lamp onto the center of the quartz tube 3. At this time, atmospheric gas is introduced from the gas inlet 4 and exhausted from the gas exhaust port 5.

The tip of the raw material rod 6 and the tip of the seed crystal 7 are brought into molten contact in the light condensing section to form a molten zone 8.

At this time, the upper shaft 9 and the lower shaft 1o are rotated in the same direction or in opposite directions, and the upper and lower shafts simultaneously move downward, thereby growing a crystal.

The block diagram of the system of the present invention is shown in Fig. 2.
1 is an optical system, 22 is a sensor section, 23 is a controller section,
Reference numeral 24 designates a key power section, 25 a DA converter, 26 an AD converter, 27 a display section, 28 a part of the printer, 29 a lamp power control section, and 50 a gap adjustment section.

The image of the melted zone passes through the optical system 21, reaches the sensor section 22, and is subjected to calculation processing by the controller section 23. The processed signal passes through the DA converter 25, and the lamp power controller 29 adjusts the lamp power to control the temperature of the melting zone. Alternatively, the height of the melt may be adjusted using the gap adjustment section 50.

The lamp power or gap is fed back to the controller section 23 again through the AD converter 26.

On the other hand, the key input section 24 inputs various initial constants, and the display section 27 displays the lamp power and the like at that time. Furthermore, in the printer part 28, the lamp power,
Print out the molten zone diameter, molten zone height, etc.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

[Example-1] Fig. 3 is a front view of the melted zone, and shows a case where two sensors are used vertically and horizontally.

In Figure 3, 31 is a raw material rod, 32 is a grown crystal, 3S
64 and 35 indicate the bath melting zone, and 2-in sensor measurement parts.

A line sensor 34 that measures the diameter of the melted zone is set at a location 0.5 to 5 mm directly above the solid-liquid interface, and a line sensor 34 that measures the height of the melted zone. 35 is set approximately at the center of the melting zone.

In this case, since the position of the solid-liquid interface of most crystals fluctuates over time, it is difficult for the line sensor 54 alone to keep the line sensor in the melting zone, and in extreme cases it may protrude to the crystal side. Then, it is no longer possible to maintain the shape of the molten zone, and crystal growth becomes impossible.

Therefore, the 2-inch sensor 55 that measures the height of the melting zone is
By working simultaneously, the height of the melting zone is maintained,
It becomes possible to keep the sensor 34 at a predetermined position in the melting zone, and stable crystal growth becomes possible for a long period of time.

[Example 2] The fs4 diagram is a front view of the melted zone, and shows the case where three line sennas are used.

In Fig. 4, 41 is a raw material rod, 42 is a grown crystal, and 43 is a raw material rod.
44, 45, and 46 indicate the molten zone, and 2-in sensor measurement parts.

For the same reason as in Example 1, it is impossible to grow crystals using only the line sensor 44, but by using three line sensors,
By calculating the curvature of the molten zone, it is possible to determine the height of the molten zone.

Therefore, it is possible to keep the line sensor 44 at a predetermined position in the molten zone, and stable crystal growth for a long period of time is possible.

[Example 3] FIG. 5 is a front view of the molten zone, showing a case where a line sensor and an area sensor are used in combination.

In Fig. 5, 51 is a raw material rod (152 is a grown crystal, 5
3 indicates the melting zone, and 54 and 55 indicate the measurement parts of the twin sensor and the area sensor, respectively.

For the same reason as in Example 1, with only the line sensor 54,
Although crystal growth is impossible, the approximate shape of the molten zone can be determined by the area sensor 55, and the line sensor 54 can then be kept at a predetermined position in the molten zone, allowing stable crystal growth for a long time. becomes.

In this embodiment, the case where two to six line sensors or area sensors are used in combination has been described as an example, but even if more than that are used, sufficient effects can be obtained.

〔effect〕

As described above, according to the present invention, not only single crystals for gemstones such as ruby, sapphire, alexandrite, etc.
It is possible to grow industrial single crystals such as YAG, GGG, etc. stably for a long time, reducing costs through unmanned operation, and improving the quality of crystals through stable growth (removal of uneven color, bubbles, defects, etc.) This has the effect of greatly contributing to

[Brief explanation of the drawing]

Figure 1 shows the present invention? An overview of the Z method is shown. FIG. 2 shows a block diagram of the system of the present invention. FIG. 3 shows a front view of a melting zone section showing an embodiment of the invention. FIG. 4 shows a front view of a melt zone showing another embodiment of the present invention. FIG. 85 shows a front view of a melt zone showing still another embodiment of the present invention. Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] Light emitted from a high-temperature light source, such as a halogen lamp, is focused using a reflecting mirror or lens, and in the focusing section, the raw material rod and the seed crystal are combined via the molten zone to form the C1 floating zone. In the 70-ting zone method, in which crystals are deposited on the seed crystal by forming a floating zone and moving the floating zone at a constant speed, a plurality of line sensors or a combination of a line sensor and an area sensor are used, A single crystal manufacturing method characterized by growing a crystal by measuring the diameter, height, external shape, etc. of a molten zone and feeding this back to the lamp power or the height of the molten zone.