JPH0541597B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an FZ apparatus, particularly for crystal growth.
Regarding automatic FZ equipment.

[Prior art]

Conventionally, crystal synthesis in an FZ apparatus has not been automatically controlled, and images have only been observed on a screen through a hole provided in one part of a spheroidal mirror.

Therefore, in order to grow crystals, it was necessary to constantly monitor images and manually adjust the lamp power or gap.

〔the purpose〕

The present invention solves the above problems, and its purpose is to provide an FZ apparatus that can stably grow crystals for a long time (10 hours or more).

〔overview〕

The FZ device (infrared focused heating single crystal manufacturing device) of the present invention has a plurality of polarizing filters installed in the middle of an optical system such as a lens, a prism, a half mirror, and a reflecting mirror, and a plurality of polarizing filters are installed in a part of the spheroidal mirror. The image of the molten zone is formed from the hole through the optical system onto the optical sensor, and the signal from the optical sensor is processed to automatically grow the crystal. It is characterized by high control accuracy.

Figure 1 shows an overview of the previous FZ device.

Here, 1 is a spheroidal mirror, 2 is a halogen 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 10 is a lower shaft, 11 is a lens (including a prism), and 12 is a screen.

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

The power of the halogen lamp 2 is turned on, 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 through the gas inlet 4 and exhausted through the gas exhaust port 5.

In the light condensing section, the tip of the raw material rod 6 and the tip of the seed crystal 7 are brought into molten contact to form a molten zone 8.
At this time, the upper shaft 9 and the lower shaft 10
are rotated in the same direction or in opposite directions, and the upper and lower shafts move downward at the same time.

The state of the light condensing section is projected onto the screen 12 via the lens 11 (including the prism) and the reflecting mirror, and while constantly monitoring the projected image, the lamp power or the gap between the raw material rod and the seed crystal is adjusted. Crystal growth is performed while making adjustments.

Figure 2 shows an overview of the optical system of the previous FZ device.
Here, a is a plan view and b is a side view.

21 is a melting zone, 22 is a lens (including a prism),
23 is a reflecting mirror, 24 is a screen, and 25 is a front panel.

FIG. 3 shows a block diagram of the automatic control system used in the FZ device of the present invention.

Here, 31 is an optical system, 32 is a sensor section, 33 is a controller section, 34 is a key input section, and 35 is a DA
Converter, 36 is an AD converter, 37 is a display unit, 38
39 is a lamp power control section, and 40 is a gap adjustment section.

The image of the melted zone passes through the optical system 31 and is sent to the sensor section 3.
2, the control section 39 adjusts the lamp power to control the temperature of the melting zone, or the gap adjustment section 40 adjusts the height of the melt.

The lamp power or gap is fed back to the control unit 33 via the AD converter 36.

On the other hand, the key input section 34 inputs various initial constants, and the display section 37 displays the lamp power and the like at that time. Furthermore, in the printer section 38,
The lamp power, melting zone diameter, melting zone height, etc. are printed out at predetermined intervals.

When performing automatic control, the signal-to-noise ratio of the signal from the optical sensor has an extremely large effect on subsequent calculation processing, and a high signal-to-noise ratio is an essential condition. Furthermore, the level of light intensity may change during growth, and it is desirable to be able to easily adjust it.

〔Example〕

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

4 and 5 show plan views of the optical system of the apparatus of the present invention.

Here, 41 and 51 are melting zones, 42 and 52 are polarizing filters, 43 and 53 are lenses (including prisms), 44 and 54 are optical sensors, 45 and 5
5 is the front panel, 56 is the half mirror, 57
is a reflecting mirror, and 58 is a screen.

FIG. 6 shows a signal waveform obtained by an oscilloscope when a line sensor is used as an optical sensor and arithmetic processing is performed.

Here, 61 is a direct value of the light amount level of the sensor, and 62 is a signal obtained by converting this into a binary value.

A is a case where two polarizing filters are superimposed at substantially right angles and there is an insufficient amount of light, b is an appropriate value, and c is a case where two polarizing filters are superimposed at substantially parallel positions and there is an excess amount of light.

In case a, the binary signal is cut off in the middle as shown in The judgment becomes inaccurate.

Since the required power differs depending on the crystal material, the brightness of the melting zone changes, but with the present invention, the level of light intensity can be adjusted simply by rotating the polarizing filter and changing the angle at which the two filters overlap. This allows you to smoothly adjust the amount of light even while driving.

〔effect〕

As described above, according to the present invention, even if the material of the crystal changes, an appropriate signal level can be obtained, and the crystal can be grown stably for a long time.
Therefore, not only gemstone single crystals such as ruby, sapphire, and alexandrite, but also YIG, YAG, and GGG.
It can also be used for industrial single crystals such as
High-quality single crystals without bubbles or defects can be grown.

[Brief explanation of the drawing]

Figure 1 shows an overview of the conventional FZ device. Figure 2 shows an overview of the optical system of a conventional FZ device. FIG. 3 shows a block diagram of the automatic control system used in the FZ device of the present invention. FIG. 4 shows an outline of the optical system of the FZ device of the present invention. FIG. 5 shows an outline of another optical system of the FZ device of the present invention. Figure 6 shows the present invention.
When using a line sensor in FZ equipment,
Shows the signal waveform.

Claims (1)

[Claims] 1 An image of the molten zone is formed on an optical sensor through an optical system such as a lens, prism, half mirror, or reflector through a hole provided in a part of the spheroidal mirror, and the diameter or external shape of the molten zone is determined. In an infrared condensed heating single crystal manufacturing apparatus that automatically controls the temperature by feeding back the lamp power or the height of the melting zone, the optical system is provided with a plurality of polarizing filters. Crystal manufacturing equipment.