JPH0268486A - image heating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in an image heating light source for an image furnace used, for example, in crystal growth of semiconductor materials.

[Conventional technology]

Figure 4 is an example of solid state physics Vop lshima A10゜1 97
9. This is a sectional view showing the configuration of the conventional image heating device shown on pages 633 to 640.
1) is an elliptical mirror whose inner surface is polished into a spheroid and plated with gold; (21 is a light source such as a halogen lamp or xenon lamp installed at the first focal point of the elliptical mirror fil; (3)
is a power supply connected to this light source, (4) is a sample as a specimen placed at the second focus of the elliptical mirror (11), and (5) is a quartz tube that houses this sample (4).

The conventional image heating device fIL is configured as described above,
The light emitted by the light source (2) is focused on a second focal point.

The temperature of the material rod (4) increases. The quartz tube (5) is provided to control the atmosphere by evacuating the inside and injecting gas.

[Problem to be solved by the invention]

In the conventional image heating device as described above, the light source (2) is a halogen lamp or Xe lamp, and the size of the light emitting part is small with a diameter of 5 to 7 m, so the temperature gradient on the surface of the material rod (4) is large. , there were problems such as cracks occurring.

The lifespan of halogen and Xe lamps is approximately 100 hours each.
There was a problem that the time required for replacement was short (1,500 hours), which increased the labor and cost of replacement.

Furthermore, the lamp startup time and restart time are approximately 180 seconds and 300 seconds, respectively, which is very inconvenient in the heating process. After heating the drum, it is cooled to a certain temperature, and when annealing is performed at this temperature, if the startup time is long, it is difficult to accurately control the temperature.

Furthermore, the shape of the lamp is large, requiring a large volume for storing and transporting spare parts. This becomes a very difficult problem in the case of material reactors for use in the space environment.

This invention was made to solve these problems, and by employing a microwave discharge lamp as a light source, the temperature gradient can be reduced, the lifespan can be extended, startup and restart can be performed quickly, and the shape of the lamp can be changed. The aim is to obtain a small image heating device.

In addition to the above object, another invention of the present invention uses two light sources and aims to make the temperature of the sample uniform.

[Means to solve the problem]

The image heating device according to the present invention stretches a wire mesh inside an elliptical mirror, places a plasma lamp in the space created between this and the elliptical mirror, that is, the first focal point of the cavity resonant volume, and generates waves. It is injected to cause a plasma lamp to emit light.

In addition, in an image heating device according to another invention of the present invention, two elliptical mirrors are combined to form a bielliptic mirror, and a plasma lamp is placed at the first focus of each, and the temperature distribution of the sample following the second focus is This is to make it uniform.

[Effect]

In this invention, when the plasma lamp placed at the first focal point is excited by radio waves and emits light, the light transmitted through the wire mesh is focused by an elliptical mirror and focused on the sample placed at the second focal point, heating the sample. do.

Further, in another invention of the present invention, the light of the plasma lamp placed at each of the first focus of the first elliptical mirror and the first focus of the second elliptical mirror is placed at a common second focus. The light is focused on the sample and heated.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention. (
11 and (4) are exactly the same as the conventional device described above. (6) is a plasma lamp placed at the first focus, with Xe, K, etc. inserted into a hollow ceramic sphere. Reference numeral (7) denotes a support for supporting the plasma lamp (6), and is made of ceramics with good thermal conductivity such as aluminum nitride. (8) is a shielding plate made of a disk-shaped wire mesh attached to the end of the elliptical mirror (1) and shielding 11 waves, and its peripheral part is in contact with the inside of the elliptical mirror fil to ensure electrical continuity. When maintained, a cavity resonator (9) is formed. αυ is a waveguide that is installed by making a rectangular hole in a part of the cavity resonator (9) with its open end aligned with this hole α, (+2 is installed at the end of this waveguide αυ) The klystron αe is a power supply connected to the klystron a3.

In the image heating device configured as described above, power is supplied from the power source U to oscillate the klystron α2, injecting radio waves into the waveguide (11+), and injecting electromagnetic energy from the hole α1 into the cavity resonator (9). and plasma lamp (6
) to be absorbed. The plasma lamp (6) emits light due to plasma excitation by electromagnetic waves, passes through the shielding plate (8), is focused by the elliptical mirror (1), and heats the sample (4) placed at the second focal point.

In the above embodiment, the disk-shaped wire mesh (8) is replaced with an elliptical mirror (1).
Although the shielding plate (8) is attached to the inside of the elliptical mirror (1), the same operation can be performed by forming the shielding plate (8) into a cup shape with a U-shaped cross section and attaching it to the end of the elliptical mirror (1) on the first focal point side.

Figure 2 shows another embodiment in which a cup-shaped shielding plate (8) is attached to the elliptical mirror (1).
) A cot-shaped shielding plate (8) is attached to accommodate the plasma lung (6) placed at the first focus of the cavity, and the cavity resonance conditions can be determined by the shape of the shielding plate (8). Advantages arise depending on the shape of the elliptical mirror (11).

Now, in this invention, as mentioned above, the plasma lamp (6) and the shielding plate (8) are attached to the first focus of the elliptical mirror fil, but as in another invention shown in FIG. α
4 is installed in the long sleeve direction of the elliptical mirror fi+, sharing the second focal point, and a plasma lamp (6) is attached to the end of the second elliptical mirror α4.
A cavity resonator (9) is constructed by attaching a support (7) and a shielding plate (8). The light emitted from both plasma lamps (6) is focused onto the sample (4) placed at the second focal point and heats it. Since the sample (4) is irradiated with light from all directions, a uniform temperature distribution is achieved.

Furthermore, in the above-mentioned other invention, the same effect can be obtained even if the shielding plate (8) is made into a concave shape.

〔Effect of the invention〕

As explained above, this invention is the inside of an elliptical mirror.

A cavity resonator is constructed by placing a disc-shaped shielding plate at the end including the first focal point, and a plasma lamp is placed inside this cavity to emit light and heat the sample placed at the second focal point. Since the plasma lamp has a large diameter of 10 to 30 cm, the image formed on the sample is large and hits the sample with an average intensity, which has the effect of making the temperature of the sample uniform.

This is an extremely important effect in material manufacturing under microgravity in space. This is because if the heat distribution on the surface of the sample is uneven, Marangoni convection occurs, disrupting the crystal growth of the material and inhibiting the effects of microgravity.
It is necessary to heat the sample at as uniform a temperature as possible.

Additionally, plasma lamps are small and lightweight.

Since it does not use a filament, it has a long life and is robust, so it is extremely easy to handle, has a long life, and has the effect of simplifying maintenance compared to conventional image heating devices using halogen lamps.

Another aspect of the present invention uses two plasma lamps to heat the sample from both sides, which has the effect of making the heat distribution of the sample more uniform.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of this invention, FIG. 2 is a sectional view showing another embodiment of this invention, FIG. 3 is a sectional view showing another embodiment of this invention, and FIG. 4 is a sectional view showing another embodiment of this invention. 1 is a sectional view showing a conventional image heating device. In the figure, (1) is an elliptical mirror, (2) is a light source, and (3) is a power source. (4) is the sample, (5) is the quartz tube, (6) is the plasma lamp, (7) is the support, (8) is the shielding plate, (9) is the cavity resonator, and QQ is the hole. all is a waveguide, α2 is a klystron, aj is a power supply,
84 is a second elliptical mirror. In addition, the same reference numerals in each figure indicate the same or different parts. Figure 1 Figure 2

Claims (2)

[Claims] (1) An elliptical mirror having a spheroidal reflecting surface inside, a plasma lamp placed at the first focal point, a support for supporting the plasma lamp, and an end portion on the first focal point side of the elliptical mirror, It is characterized by comprising a disc-shaped shielding plate attached so that its inner surface is in contact with a circumferential edge, and a means for injecting radio waves into a cavity resonator formed by the shielding plate and an elliptical mirror. Image heating device. (2) An elliptical mirror with a spheroidal reflecting surface inside, a second elliptical mirror that shares this second focal point, a plasma lamp placed at the first focal point of both, and support for both plasma lamps. a disc-shaped shielding plate attached so that its inner surface is in contact with the circumferential edge of the first focal point side end of both elliptical mirrors; and the shielding plate and the elliptical mirror. An image heating device characterized by comprising means for injecting radio waves into a cavity resonator.