JPH0525835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to improvements in molecular beam epitaxy equipment.

[Conventional technology]

Molecular beam epitaxy equipment is regarded as important as an epitaxial equipment for semiconductor devices that requires a steep interface and high controllability of film thickness, and a conventional molecular beam epitaxy equipment is shown in FIG. 3. In the figure, the molecular beam epitaxy apparatus includes a bell jar 12 which is a reaction chamber, a molecular beam source crucible 1 housed inside this, a substrate holder 3 for heating a substrate 2, and a substrate holder 3 for adsorbing impurity gas. liquid nitrogen cooling traps 4a and 4b, a vacuum exhaust system 5, a leak valve 6, and a substrate transfer gate valve 7a connected to the bell gear 12.
It is equipped with Further, the molecular beam source crucible 1 is equipped with a heating heater 8, a thermocouple 9, and a heat radiation plate 10a, and has a structure in which the inside of the crucible 1 can be controlled to a desired temperature. Further, a crucible flange 11 is attached to this molecular beam source crucible 1, and this crucible flange 11 is detachably attached to a crucible port flange 13 fixed to a bell gear 12.

In the conventional molecular beam epitaxy apparatus described above, when filling the molecular beam source crucible 1 with the molecular beam source material 14, nitrogen gas is supplied from the leak valve 6 to the bell jar 1.
Break the vacuum by introducing the molecular beam into the molecular beam source crucible 1.
was taken out into the atmosphere by removing the crucible flange 11 from the crucible port flange 13, and the molecular beam source material 14 was filled into the molecular beam source crucible 1 in the atmosphere.

[Problem that the invention seeks to solve]

Since the conventional molecular beam epitaxy apparatus is configured as described above, it has the following drawbacks.

() By breaking the vacuum, the molecular beam source crucible 1, substrate holder 3, liquid nitrogen cooling trap 4
Components such as a and 4b are contaminated, which adversely affects the crystallinity and reproducibility of the epitaxial film.

() A growth preparation period of a uniform week is required due to the steps necessary to start crystal growth again after breaking the vacuum, that is, baking the bell jar 12, vacuum heat treatment of the molecular beam source crucible 1 and the molecular beam source material 14, etc. Therefore, production efficiency is low.

() Contaminants in the atmosphere of the molecular beam source material 14 cannot be completely removed by vacuum heat treatment alone, and this problem is particularly noticeable for oxides of group elements, and furthermore, impurity gases during heat treatment cause growth. Released into the chamber, these impair the crystallinity of the epitaxial film and also cause defects on the surface of the epitaxial film.

The present invention has been made to solve these conventional problems, and it is possible to perform epitaxial growth without exposing the inside of the growth chamber to the atmosphere, improve the reproducibility and production efficiency of epitaxial films, and improve the production efficiency of epitaxial films. The purpose of the present invention is to provide a molecular beam epitaxy device that can greatly improve the quality of the coating film.

[Means for solving problems]

The present invention is a molecular beam epitaxy device in which a molecular beam source material highly purified by vacuum heat treatment or heat treatment in a hydrogen atmosphere is filled into a molecular beam source crucible using an air lock method without being exposed to the atmosphere. It has been established.

[Effect]

In the molecular beam epitaxy apparatus according to the present invention, the molecular beam source material is highly purified in advance in a dedicated device for highly purifying the molecular beam source material or in a molecular beam source supply device provided separately from the reaction chamber, Thereafter, it is filled into a molecular beam source crucible in a reaction chamber without being exposed to the atmosphere.

〔Example〕

Examples of this invention will be described below as molecular beam source materials.
This will be explained using a diagram, taking Ga as an example.

1 and 2 show an embodiment of the present invention.
In the figure, the same reference numerals as in FIG. 3 indicate the same or equivalent parts, 30 is a molecular beam source supply device, and the molecular beam source processing chamber 16, which is a closed container thereof, is connected to the bell gear 12 via a gate valve 7b. has been done. 2
0 is a vacuum exhaust valve, 21 is a crucible extraction port for molecular beam source processing, and 19 is a gas supply device for supplying hydrogen gas into the processing chamber 16, which includes a hydrogen introduction valve 19a and a hydrogen discharge valve 19.
Consists of b.

Also, in the molecular beam source processing chamber 16, there is a processing crucible 15, and a PBN heating furnace 17 for heat-treating the molecular beam source material 14 placed in the crucible 15.
A heating device 17 consisting of a heating heater 17b, a heat radiation plate 17c, and a liquid nitrogen trap 4c for adsorbing gas released during heat treatment are provided.
A small hole 1 is provided at the bottom of the processing crucible 15.
5a is formed, which means that when the molecular beam source material 14 is melted, it is transferred to the molecular beam source crucible 1.
It is intended to be dropped inside.

Further, 22a is a moving rod that moves the processing crucible 15, and this is connected to an internal magnet 22b, and this internal magnet 22b is connected to an external magnet 22.
A crucible insertion device 22 is magnetically coupled to the processing crucible 15 and moves the processing crucible 15 by moving the external magnet 22c.

Next, the operation will be explained.

First, in order to highly purify the molecular beam source material, open the extraction port 21 and take out the processing crucible 15, fill it with Ga which is the molecular beam source material 14,
This processing crucible 15 is set in the processing chamber 16 again. Then, open the vacuum valve 20 and
6 is evacuated to a degree of vacuum on the order of 10 ^-9 torr, and after evacuation, a current is applied to the temperature rising heater 17b until the evaporation source material Ga is approximately
Raise the temperature until it reaches 950℃. After about 1 hour, open the hydrogen introduction valve 19a to supply hydrogen gas to the processing chamber 1.
6, and at the same time open the vacuum exhaust valve 20.
Close. When the hydrogen gas pressure in the molecular beam source processing chamber 16 exceeds atmospheric pressure, the hydrogen release valve 19
Open b. Then depending on the amount of Ga, e.g.
Heat treatment is performed on 10 g of Ga for 24 hours. After a predetermined period of time has elapsed, the supply of electricity to the temperature-raising heater 17b is stopped and the evaporation source material Ga is cooled and solidified, thereby making the molecular beam source material 14 highly purified.
Thereafter, the hydrogen release valve 19b is closed, and the hydrogen introduction valve 19a is also closed, and the vacuum exhaust valve 20 is turned on again to evacuate the molecular beam source processing chamber 16 to a level of 10 ^-9 torr.

Next, in order to fill the molecular beam source crucible 1 with the highly purified molecular beam source material 14, the processing chamber 1 is filled with the highly purified molecular beam source material 14.
6 is evacuated, the molecular beam source transfer gate valve 7b is opened, and the processing crucible 15 is inserted into the molecular beam source crucible 1 by operating the external magnet 22c.
Then, by energizing the heater 18, the temperature inside the molecular beam source crucible 1 is raised to a temperature higher than the melting point of Ga. Then, the liquefied Ga is transferred to the processing crucible 15.
It falls through a small hole 15a provided at the bottom of the molecular beam source crucible 1 and is filled into the molecular beam source crucible 1 (see FIG. 2). After filling, operate the external magnet 22c to open the processing crucible 15.
When the molecular beam source material is returned to the molecular beam source processing chamber 16 and the molecular beam source transfer gate valve 7b is closed, the loading of the molecular beam source material is completed.

In this embodiment, the sealed processing chamber 1
In step 6, the molecular beam source material is highly purified in advance and is supplied into the molecular beam source crucible 1 without being exposed to the atmosphere, resulting in the following effects.

() Atmospheric air is not introduced into the bell gear 12, and therefore the constituent members in the bell gear 12 can be prevented from being contaminated, and the crystallinity and reproducibility of the epitaxial film will not be adversely affected.

() The preparatory steps required before restarting crystal growth can be significantly reduced, improving production efficiency.

() The molecular beam source material is not contaminated with the atmosphere, and there is no need for heat treatment within the bell gear 12, so that no contaminants are brought into the bell gear 12 or impurity gases are released into the bell gear 12. Therefore, deterioration of the crystallinity of the epitaxial film and generation of surface defects can be prevented.

Although the above embodiments have been explained using group elements as examples, the present invention is not limited to the above-mentioned group elements and can use all elements, and molecular beam source materials other than the group elements are melted in the molecular beam source crucible 1. It will be filled as a solid without any problems.

In addition, in the above embodiment, heat treatment was performed in a hydrogen atmosphere, but for molecular beam source materials that do not require hydrogen treatment, such as As and P, the molecular beam source processing chamber 16
High purity may be achieved by vacuum heating, and the processing temperature may be set to a temperature that allows evaporation of the oxide of the molecular beam source material.

In addition, when filling the processing crucible 15 in the molecular beam source processing chamber 16 with molecular beam source material that has been highly purified in advance, after filling the molecular beam source material, the molecular beam source processing chamber 16
After being evacuated to a predetermined degree of vacuum, it may be immediately introduced into the molecular beam source crucible 1 without heat treatment.

Furthermore, the concept of the present invention is applicable not only to molecular beam epitaxy but also to the purification of a deposition source in vacuum evaporation, electron beam evaporation, sputtering evaporation, and the like.

〔Effect of the invention〕

As described above, according to the molecular beam epitaxy apparatus according to the present invention, since the molecular beam source processing apparatus is provided that fills highly purified molecular beam source material without exposing it to the atmosphere, the inside of the growth chamber is exposed to the atmosphere. This has the effect of making it possible to perform epitaxial growth without any problems, improving the reproducibility of epitaxial growth and mass productivity, and producing a high-quality epitaxial film with few surface defects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a molecular beam epitaxy apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the filling state of the molecular beam source material into a molecular beam source crucible, and FIG. 3 is a diagram showing a conventional molecular beam epitaxy apparatus. FIG. 2 is a cross-sectional view of the device. 1... Molecular beam source crucible, 2... Substrate, 7b...
Gate valve (opening/closing lid), 12... Belgear (reaction chamber), 14... Molecular beam source material, 15... Processing crucible, 15a... Small hole, 16... Molecular beam source processing chamber (closed container), 17... Heating device, 19... Atmospheric gas supply device, 22... Crucible insertion device, 30...
...Molecular beam source supply device.

Claims (1)

[Scope of Claims] 1. A molecular beam epitaxy apparatus for growing crystals of a molecular beam material from a molecular beam source crucible on a substrate in a reaction chamber, comprising: a port for transporting the substrate to the reaction chamber; a closed container connected via a gate valve; a small hole for the molecular beam source material disposed in the closed container, which must contain the molecular beam source material, melt, and drop into the molecular beam source crucible; a processing crucible provided at the bottom thereof; an atmospheric gas supply device for supplying hydrogen gas into the sealed container; a heating device provided in the sealed container to heat the processing crucible; a crucible insertion device for inserting a molecular beam source material into the molecular beam source crucible, and a molecular beam source supply device for supplying molecular beam source material and the reaction chamber into the molecular beam source crucible without exposing the interior of the reaction chamber to the atmosphere. Features of molecular beam epitaxy equipment.