JPS60225421A - Evaporation source crucible for molecular beam epitaxy - Google Patents

Abstract

PURPOSE:To enable forming of a thin film which has extremely good reproducibility of distribution of film thickness due to a constant divergent angle of vapor by providing a lid with plural through holes covering an evaporated material inside an evaporation source crucible. CONSTITUTION:A lid 5 which has slits 6 is placed on a supporter 7 inside a crucible 1 and below the lid 5, a material 4 to be evaporated is placed. Vapor from the crucible passes through the lid 5 and the divergent angle theta3 does not depend upon the surface of the evaporated material 4 liquid so distribution of film thickness is only related to the lid, the shape of the crucible and the position of a substrate whereby the distribution of film thickness which has extremely good reproducibility can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an evaporation source crucible for molecular beam epitaxy that can provide a film thickness distribution with good reproducibility over a wide area with a charge amount of evaporation source material Iv1g.

[Prior art and its problems]

When forming an epitaxial film using a conventional evaporation source crucible as shown in FIG. will change.

Specifically, the divergence angle of the vapor in Figure 1 (a) is approximately θ1, and the material to be evaporated is consumed and the liquid level changes from A to Figure 1 (b).
) When the liquid level A1 is reached, the divergence angle of the vapor is approximately θ, which is clearly θ, and >θ. The film thickness distribution of the epitaxy film obtained by this method is significantly different between the two. That is, the film thickness distribution changes as the material to be evaporated is used, resulting in a lack of reproducibility.

[Purpose of the invention]

The present invention improves the drawbacks of the conventional crucibles described above, and provides an evaporation source crucible in which the divergence angle of vapor is constant regardless of the charge amount of the material to be evaporated or the amount consumed. As a result, it is possible to form thin films with extremely good reproducibility of film thickness distribution.

[Summary of the invention]

The present invention has a structure in which a lid is placed inside the evaporation source crucible to cover the material to be evaporated, and the lid is provided with a plurality of through holes [Embodiments of the Invention] Hereinafter, the present invention will be explained based on the drawings of the embodiment.

Figure 2 shows a lid (5) with a gap (6) inside the crucible opening.
) is placed on its support (7), and the material to be evaporated (4) is placed below it. When used as an evaporation source, the vapor (8) generated from the material to be evaporated (4) first reaches the lid (5), repeats re-evaporation, and then jumps out to the outside (by 8y and creeping diffusion on the lid surface). If it moves and then jumps out to the outside (8y1).
) The structure is such that the steam generated from the system does not directly escape to the outside. As described above, since the vapor from the crucible according to the present invention is substantially generated from the lid (5), the vapor divergence angle θ3 does not depend on the liquid level of the material to be evaporated (4). That is, since the film thickness distribution is related only to the lid, crucible shape, and substrate position, it is possible to obtain a film thickness distribution with extremely good reproducibility.

In addition, as mentioned above, since the lid (5) has a structure that does not allow steam to pass through directly, particles generated by bumping of the material to be evaporated (4) are also captured by the rhombus, which causes surface defects in the thin film. It is possible to prevent such particles from flying into the air. This also has the effect of obtaining an epitaxial film with fewer surface defects than K. Specifically, a lid was placed at 20 positions from the top of a crucible with an opening diameter of 20 m and a depth of 70 m, as shown in Fig. 2, and 10 m of Ga was added.
I charged f. A gap between the lids was set every two snowflakes. Pyrolytic BN was used as the crucible material and lid material. GaA with a diameter of 75 m, (001
) When epitaxial GaA3 was grown on the substrate surface at 700°C, an extremely uniform film thickness distribution and a mirror surface without surface defects were obtained at a growth rate of 1 to 3 μm/hour. The evaporation source temperature at this time is 1100-1250 for GaIC.
℃, 355-370℃ for AsK.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining a conventional example, and FIG. 2 is a sectional view for explaining an embodiment of the present invention. 1... Crucible, 2... Heater, 3... Thermocouple,
4... Evaporation object, 5... Lid, 6... Gap, 7...
- Lid support, 8...steam molecules.

Claims (2)

[Claims] (1) Molecular beam epitaxy, which is used in molecular beam epitaxy, has a structure in which a lid is placed inside the source crucible to cover the material to be evaporated, and the lid is provided with a plurality of through holes. Evaporation source crucible. (2) Claim 1, characterized in that the through-hole of the lid has a structure that prevents steam from passing through the lid without colliding with the lid.
An evaporation source crucible for molecular beam epitaxy as described in .