JPH02254713A - Molecular beam generator - Google Patents

Abstract

PURPOSE:To make it possible to charge a liquid type raw material into a downward molecular beam generated by a method wherein a crucible, which is integrally formed with a molecular beam generating cylindrical body part and a conical part having an aperture from which the molecular beam is emitted to outside, is provided. CONSTITUTION:A crucible 4, which is formed by integrally constructing a cylindrical body part 4a with which a raw material 3 is heated up and generates a molecular beam, and a conical part 4c having an aperture 4b from which heated molecular beam will be emitted to outside, is provided. As a result, a liquid raw material 3 can be stored downward, and the contamination of the raw material by the flakes generating when a shutter is opened or closed can be prevented, and a high quality epitaxial growth can be conducted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to molecular beam epitaxial crystal growth (MB) of semiconductors.
E) Regarding the molecular beam generator used for.

[Conventional technology]

FIG. 3 shows a conventional molecular beam generator. The molecular beam generator shown in FIG. 3 is installed in an ultra-high vacuum growth chamber, heats a crucible 4 with a heater 1, The structure was such that a molecular beam was generated from inside the crucible 4, which evaporated 3, to the outside. Also, the heating temperature of heater 1 is the same as that of thermocouple 2.
It is controlled based on the detection signal by.

[Problem to be solved by the invention]

In FIG. 3, when a crystal is grown using, for example, Ga as a raw material using a conventional upward molecular beam generator, many well-known elliptical surface defects are generated on the crystal. this is,
This is caused by boiling of the raw material Ga source, and reducing these surface defects is a major challenge in MBE growth.

In the conventional molecular beam generator described above, since the crucible faces upward, bumping is likely to occur and it is difficult to reduce surface defects. Furthermore, since the raw material is in liquid form, it can only be fed into the molecular beam generator facing upwards, and when the shutter is opened and closed, flakes adhering to the shutter fall onto the raw material and contaminate the raw material.

[Differences between the invention and the prior art]

In contrast to the above-mentioned conventional molecular beam generator, the present invention can charge a liquid raw material into the downward molecular beam generator, furthermore, prevents raw material contamination due to flakes that occur when opening and closing the shutter, and also uses Ga as a raw material. The difference is that defects generated on the crystal surface can be reduced when using .

[Means to solve the problem]

In order to achieve the above object, the molecular beam generator according to the present invention has an integral structure of a cylindrical body for generating molecular beams and a conical part having an enlarged diameter opening for emitting the molecular beams to the outside. It has a crucible.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 is a sectional view showing a first embodiment of the present invention.

In the figure, the present invention includes a cylindrical body portion 4a that heats the raw material 3 to generate a single molecular beam, and a conical portion 4c having an enlarged diameter opening 4b that further heats the molecular beam and releases it to the outside. The 0-conical part 4c, which is equipped with the crucible 4 having an integral structure, communicates with the upper edge portion of the cylindrical body part 4a, and the diameter of the opening 4b thereof is enlarged in the forward direction. Further, the conical portion 4
A heater 1 is installed at the edge of the opening c. 2 is a thermocouple.

In the embodiment, the crucible 4 is made of pyrolytic boron nitride (PBN), and the raw material 3 in the crucible 4 is heated by a heater 1 controlled by a thermocouple 2 and released as a molecular beam. , when Ga is used as a raw material,
Particles generated by boiling from the Ga liquid level do not come out of the crucible 1, and when growing GaAs, the number of surface defects is 1000/d when grown using a conventional molecular beam generator.
The number decreased from 172 to 500 pieces/d. Also,
It is possible to install the Ruppo 4 with the opening 4b facing downward, eliminating Ga source contamination due to falling flakes that occur when the shutter is opened and closed, and the quality of the crystals is greatly improved.

(Example 2) FIG. 2 is a sectional view showing Example 2tt of the present invention.

In the figure, crucible 4 is made of pyrolytic boron nitride (
A raw material 3 made of PBN) in the cylindrical body 4a of the Lupo 4 is heated by a heater 1 controlled by a thermocouple 2 to generate molecular beams. This molecular beam is emitted to the outside of the pot 4 where it is further heated by the heater 1 controlled by the thermocouple 2 in contact with the conical portion 4c.

In this embodiment, since the conical portion 4c and the cylindrical body portion 4a can be heated independently, there is a divine intention that the controllability of the molecular beam can be improved.

〔Effect of the invention〕

As explained above, the present invention has an integral structure that includes a cylindrical body that heats the raw material and generates molecular beams, and a conical portion that has an enlarged diameter opening that further heats the molecular beams and releases them to the outside. By having a dripping crucible, liquid raw materials can be poured downward.

Due to the downward orientation, it is possible to prevent raw material contamination due to flakes that occur when opening and closing the shutter, and it is possible to grow high-quality shrimp. Furthermore, when Ga is used as a raw material, surface defects due to boiling can be eliminated, and yields can be greatly increased in device manufacturing.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view showing a second embodiment of the present invention, and FIG. 3 is a sectional view showing a conventional example. 1... Heater 2... Thermocouple 3...
Raw material 4... Crucible 4a... Cylindrical body 4c... Conical part 4b... Opening

Claims (1)

[Claims] (1) A molecular beam generating device characterized by having a crucible having an integral structure of a cylindrical body for generating molecular beams and a conical portion having an enlarged diameter opening for emitting the molecular beams to the outside.