JPH0676869B2 - Image heating device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of an image heating light source of an image furnace used for crystal growth of semiconductor materials and the like.

[Conventional technology]

Figure 4 shows, for example, Solid State Physics, Vop 14, No. 10, 1979, pp. 633-
It is sectional drawing which shows the structure of the conventional image heating apparatus shown on page 640. In the figure, (1) is an ellipsoidal mirror whose inner surface is spheroidal-polished and metal plated, (2) is an elliptical mirror (1 ) A light source such as a halogen lamp or a xenon lamp installed at the first focus position, (3) is a power source connected to this light source, and (4) is placed at the second focus of the elliptical mirror (1). A sample as a sample, (5) is a quartz tube for accommodating this sample (4).

The conventional image heating device is configured as described above, and the light emitted from the light source (2) is focused on the second focus, and the temperature of the material rod (4) rises. The quartz tube (5) is provided for controlling the atmosphere by evacuating the inside or injecting gas.

[Problems 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 as small as 5 to 7 mm in diameter, so the temperature gradient on the surface of the material rod (4) is large, There were problems such as cracking.

Furthermore, the halogen and Xe lamps have a short service life of 100 hours and 1500 hours, respectively, and there is a problem that the time and effort for replacement are high.

In addition, the lamp startup and restart times are 180 seconds and 3 seconds, respectively.
It took about 00 seconds, which was very inconvenient in the heating process, that is, when the temperature was lowered to a certain temperature after heating and annealing was performed at this temperature, it was difficult to control the temperature accurately if the startup time was long.

In addition, the large shape of the lamp required a large volume for storing and transporting spare parts. This is a very difficult problem in the case of a material furnace that uses space environment.

The present invention has been made to solve such a problem, and by adopting a microwave discharge lamp as a light source, the temperature gradient is made gentle, the life is extended, and the startup and restart can be performed quickly, and the lamp shape The aim is to obtain a small image heating device.

Another object of the present invention is to make the temperature of the sample uniform by using two light sources in addition to the above objects.

[Means for Solving the Problems]

In the image heating device according to the present invention, a wire mesh is provided inside an elliptical mirror, and a plasma lamp is placed in a space formed between the wire mesh and the elliptic mirror, that is, a first focal point in a cavity resonator. It is injected to make the plasma lamp emit light.

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

[Action]

In the present invention, when the plasma lamp placed at the first focus is excited by radio waves and emits light, the light transmitted through the wire mesh is collected by the elliptical mirror and focused on the sample placed at the second focus to heat the sample. To do.

In another invention of the present invention, the light of the plasma lamp placed on each of the first focal point of the first elliptic mirror and the first focal point of the second elliptic mirror is placed on a common second focal point. The sample is focused and heated.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention,
(1) and (4) are exactly the same as the above-mentioned conventional device. (6) is a plasma lamp placed at the first focus, in which Xe, K, etc. are enclosed in a hollow sphere of ceramics. Reference numeral (7) is a supporting member for supporting the plasma lamp (6), which is made of ceramic such as aluminum nitride having good thermal conductivity. Reference numeral (8) is a shield plate made of a disc-shaped wire mesh attached to the end of the elliptical mirror (1) for shielding radio waves, and its periphery is in contact with the inside of the elliptic mirror (1) for electrical conduction. Are maintained and form a cavity resonator (9). (11) has a rectangular hole (10) in a part of the cavity resonator (9).
The waveguide is attached with its open end aligned with (0), (12) is the magnetron or klystron (hereinafter referred to as Kloestron) attached to the end of this waveguide (11), and (13) is. It is a power supply connected to the klystron (12).

In the image heating apparatus configured as described above, electric power is supplied from the power source (13) to oscillate the klystron (12) to inject a radio wave into the waveguide (11), and the cavity resonator is inserted from the hole (10). Electromagnetic energy is injected into (9) and is attracted to the plasma lamp (6). The plasma lamp (6) emits light when excited by plasma by electromagnetic waves, transmits the shield plate (8), and is focused by the elliptical mirror (1) to heat the sample (4) placed at the second focus.

In the above embodiment, the disc-shaped wire mesh (8) is attached to the inside of the elliptical mirror (1), but the shield plate (8) is formed in a cup shape having a U-shaped cross section to form the elliptical mirror (1). Even if it is attached to the end portion on the side of the first focal point, the same operation can be performed.

FIG. 2 shows another embodiment in which the cup-shaped shield plate (8) is attached to the elliptic mirror (1). The plasma lamp (6) placed at the first focus of the elliptic mirror (1) is shown in FIG. ) Is attached with a cup-shaped shield plate (8) so that the cavity resonance condition can be determined by the shape of the shield plate (8) and is not affected by the shape of the elliptical mirror (1). Benefits arise.

Now, the present invention is to attach the plasma lamp (6) and the shielding plate (8) to the first focal point of the elliptic mirror (1) as described above, but the second embodiment is similar to another invention of FIG. The elliptic mirror (14) is attached in the long axis direction of the elliptic mirror (1) so that the second focal point is shared, and the plasma lamp (6), the support (7) and the shield are attached to the end of the second elliptic mirror (14). The plate (8) is attached to form the cavity resonator (9). The light emitted from both plasma lamps (6) was focused on the second sample (4)
It is focused on and heated. Since the sample (4) is irradiated with light from all directions, a uniform temperature distribution is obtained.

Further, in the above-mentioned another invention, the same effect can be obtained even if the shield plate (8) is formed in a cup shape.

〔The invention's effect〕

As described above, according to the present invention, a disk-shaped shield plate is attached to the inside of the elliptical mirror and the end portion including the first focal point to form a cavity resonator, and a plasma lamp is placed therein to emit light.
The sample placed on the second focal point is heated, but since the diameter of the plasma lamp is as large as 10 to 30 mm, the image formed on the sample is large and hits with average intensity, which has the effect of making the sample temperature uniform. .

This is a very important effect in material production under microgravity in space. This is because when the heat distribution on the surface of the sample is non-uniform, Marangoni convection occurs and disturbs the crystal growth of the material, which hinders the effect of microgravity.
It is necessary to heat the sample at a temperature that is as uniform as possible.

In addition, the plasma lamp is small and lightweight, and because it does not use filaments, it has a long life, so it is much easier to handle and has a longer life and easier maintenance compared to conventional image heating devices that use halogen lamps. There is.

Further, another invention of the present invention has an effect that the heat distribution of the sample can be made more uniform because the sample is heated from both sides by using two plasma lamps.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the present invention, FIG. 3 is a sectional view showing another embodiment of the present invention, and FIG. FIG. 6 is a cross-sectional view showing a conventional image heating device. In the figure, (1) is an elliptical mirror, (2) is a light source, (3) is a power source, (4) is a sample, (5) is a quartz tube, (6) is a plasma lamp, (7) is a support, and ( 8) is a shield plate, (9) is a cavity resonator, (10) is a hole, (11) is a waveguide, (12) is a klystron, (13) is a power supply, and (14) is a second elliptic mirror. Is. The same reference numerals in each figure indicate the same or corresponding parts.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location // H01L 21/26 L 8617-4M H01S 3/093 8934-4M

Claims (2)

[Claims] 1. An elliptical mirror having a spheroidal anti-slope inside, a plasma lamp placed at a first focal point of the ellipsoid, a support for supporting the plasma lamp, and a first ellipse mirror. A means for injecting radio waves into a cavity resonator formed by a disk-shaped shield plate attached to the inner surface of the focus side end portion so that a circumferential edge is in contact with the shield plate and an elliptical mirror is provided. Image heating device that is equipped with. 2. An ellipsoidal mirror having a spheroidal reflecting surface inside, and a second ellipsoidal mirror sharing a second focal point of the ellipsoidal mirror.
Plasma lamps respectively placed on the first focal points of the both elliptic mirrors, a support for supporting the both plasma lamps, and a circular shape on the inner surface at the first focal point side end portions of the both elliptic mirrors. An image heating apparatus comprising: a disk-shaped shield plate attached so that the edges of the shield plate and a means for injecting radio waves into a cavity resonator formed by the shield plate and an elliptical mirror.