JPS6286155A - Ejection device for molten material vapor - 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] [Field of Industrial Application] This invention is not based on electrochemical means such as plating technology, but on forming thin films such as thin layers of substances on various substrates (metals, semiconductors, insulators, etc.). The present invention relates to an apparatus for ejecting vapor of molten substances (for example, lead, copper, gold, silver, cadmium, delurium, etc.) in comparison with a thin film deposition apparatus such as a vacuum evaporation method.

- In this type of thin film deposition apparatus, the molten material to be deposited is placed in a closed crucible with a steam outlet and heated. by forming a pressure difference of at least 10 times or more between the gas pressure (by heating) and the molten material vapor formed in the crucible, and by maintaining the molten material vapor in the crucible in a state of thermal equilibrium. Molten material vapor is injected from the steam vent into the low gas pressure atmosphere IBJ, a supercooled state is formed near the steam vent due to adiabatic expansion, and a lumpy atomic group (cluster) is created by condensation due to the supersaturated state. A high negative voltage applied to the ion extraction electrode imparts kinetic energy to the entire cluster to form a thin film layer of a predetermined material on the substrate.

[Conventional technology]

FIG. 3 is a sectional view showing a main part of a vapor ejecting device for molten material in a conventional thin film deposition apparatus. (1) is a crucible containing a predetermined molten substance (5) therein; (2) is a crucible that surrounds this crucible (1) at a predetermined interval;
(3) is a lid body that closes the upper opening of the crucible (1) and has a steam ejection hole (4) of a predetermined inner diameter in the center of the ceiling; (5a) is a lid body that closes the upper opening of the crucible (1);
) is the molten material vapor that is ejected from the vapor ejection hole (4).

Since the conventional steam ejecting device is constructed as described above, when the molten substance (5) in the crucible (1) heated by the heating filament (2) is evaporated, the vapor (5i) is evaporated. ) increases the pressure in the crucible +1) and is ejected from the steam nozzle (4), but this molten material vapor (
5a) spreads laterally due to adiabatic expansion caused by the pressure difference, and this molten material vapor (5a) is acceleratedly cooled by adiabatic expansion, forming a lumpy atomic group (cluster) of loosely bonded atoms of about 10 to 1000 atoms. This cluster is used to form a thin film of a material to be deposited (not shown).

[Problem that the invention seeks to solve]

In the conventional steam ejection device described above, the molten material (5
) If a material with a high specific gravity, such as gold, is used, contaminants of the crucible material such as carbon will increase in the IK crucible, float on the surface of the molten material, and completely cover the surface of the molten material. As a result, the amount of steam ejected is reduced and a stable supply of molten material steam (5a) cannot be provided at all times.

This invention has been made with attention to this point. Even when the specific gravity of the evaporated substance contained in the crucible is large,
It is an object of the present invention to provide a steam ejecting device that can always supply stable molten material vapor and generate a large amount of clusters.

[Means for solving problems]

In the steam ejecting device according to the present invention, a heat shield plate is disposed below the crucible at a predetermined interval.

[For production]

In this invention, since a heat shield plate is provided on the underside of the crucible, heat loss due to radiation from the bottom of the crucible can be reduced, and the bottom of the crucible can be maintained at a higher temperature than the surroundings of the crucible. By causing convection in the molten material inside the crucible, contaminants are prevented from floating over the entire surface of the molten material in the crucible.

[Embodiments of the invention]

Figures 1 and 2 both show one embodiment of the present invention, with Figure 1 being a longitudinal cross-sectional view of the steam ejecting device and Figure 2 being a cross-sectional view of the main parts. The same reference numerals as those shown in FIG. 3 refer to the same constituent members, and their explanations will be omitted.

First, in FIG. 1, (8) an ionizing electron-emitting filament that is arranged concentrically at a predetermined interval above the crucible (1) and ionizes the clusters generated from the molten material vapor (5a). The grid that accelerates the electrons emitted from (7), (9) is the upper s of this grid (8)
K is an acceleration electrode arranged at a predetermined interval to control the acceleration of ionized clusters, α0 is a material to be deposited on the surface of which a thin film of material is deposited, aυ is a vacuum chamber containing each component,
(6) A pair of parallel light shield plates arranged at a predetermined interval on the underside of the crucible (1), and this heat shield plate (
6) The distance rbJ between the bottom of the crucible (1) and the bottom of the crucible (1) is
) is 2 to 6 times larger than the distance r-J between the peripheral wall of the heating filament (2) and the heating filament (2).

Since the molten substance vapor ejecting device of the present invention is configured as described above, thermionic electrons emitted from the heating filament (2) to heat the crucible (1) are
A positive bias voltage applied between the heating filament (1) and the heating filament (2) impinges on and heats the crucible (1). The heat shield plate (6) placed under the crucible (1) reduces heat loss due to heat radiation from the underside of the crucible (1), so the bottom of the crucible (1) (1) is maintained at a higher temperature than its surroundings, causing convection in the molten material (5) within this crucible (1). Therefore, in order to push the contaminants that would otherwise be floating on the surface of the molten material (5) to the inner peripheral wall of the crucible,
Not only is the molten material vapor (5a) efficiently generated from the surface of the molten material (5), but also the crucible (5) is generated by convection.
The temperature of the molten substance (5) in 1) becomes uniform throughout;
A stable amount of steam is always obtained. As shown in Fig. 2, the distance rbJ between the first heat shield plate (6) and the bottom of the crucible (1) is determined by the distance rbJ between the bottom of the crucible (1) and the heat shield plate (6) in order to avoid collision of thermoelectrons from the heating filament (2). It is more efficient to make the distance "a" between the peripheral wall and the heating filament (2) about 2 to 6 times larger.

〔Effect of the invention〕

As described above, according to the present invention, the molten substance (5)
Since the heat shield plate (6) is arranged at a predetermined interval below the crucible (1) containing the crucible, it is possible to reduce heat loss due to radiation from the crucible bottom. By maintaining a temperature higher than the surroundings of this crucible to create convection currents in the molten material inside the crucible, contaminants were prevented from floating over the entire surface of the molten material in the crucible, so that contaminants could be removed from the surface of the molten material. This has the excellent effect of not only generating molten material vapor in a smooth manner, but also making the temperature of the molten material in the crucible uniform throughout the crucible due to convection, so that a stable amount of vapor can be obtained at all times. !
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[Brief explanation of drawings]

1 and 2 each show an embodiment of the present invention, with FIG. 1 being a longitudinal cross-sectional view of a steam ejecting device, and FIG. 2 being a cross-sectional view of the main parts. FIG. 3 is a sectional view of a main part of a conventional molten material steam ejection device. In the figure, (1) a crucible, (2) a filament for heating), (3) a lid, (4) a steam outlet, (5) a molten substance, (5a) a molten substance vapor, (6) is a heat shield plate, and the same reference numerals in the figures indicate the same or corresponding parts. Agent Patent Attorney Tadashi Sato 1st Cause Figure 2 Figure 3

Claims (4)

[Claims] (1) Underneath the crucible that is heated by a heating filament and contains a molten substance, heat shield plates are placed at predetermined intervals to reduce heat loss due to radiation from the bottom of the crucible. Features: A device for ejecting steam from molten substances. (2) The molten substance vapor ejecting device according to claim 1, wherein the heat shield plate includes a plurality of heat shield plates arranged parallel to each other at predetermined intervals. (3) The molten substance vapor ejecting device according to claim 1, wherein a vapor ejecting port having a predetermined inner diameter is formed in the center of the ceiling of the lid that closes the upper opening of the crucible. (4) The molten substance vapor ejecting device according to claim 1, wherein the distance between the heat shield plate and the bottom of the crucible is larger than the distance between the heating filament and the peripheral wall of the crucible.