JPH057251Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Summary] Regarding a molecular beam epitaxial growth apparatus, the purpose of this invention is to smoothly perform the shutter operation of the shutter provided in front of the opening of the molecular beam source. A molecular beam epitaxial growth apparatus is constructed by providing a heating source at the end position of the opening operation of a shutter provided in front of the shutter, and having a mechanism for heating the heating source by energizing it when the shutter is opened.

[Industrial application field]

The present invention relates to improvements in molecular beam epitaxial growth equipment.

Semiconductor materials used to form integrated circuits such as ICs and LSIs and optical devices such as semiconductor lasers include elemental semiconductors such as silicon (Si) and germanium (Ge), as well as gallium arsenide (GaAs) and indium phosphide ( There are compound semiconductors such as InP).

In the latter case, the single crystal thin film is grown using a molecular beam epitaxial growth apparatus or a liquid phase epitaxial growth apparatus.

[Conventional technology]

^FIG . 2 is a conceptual diagram showing the relationship between an electron beam source and a substrate to be processed in a molecular beam epitaxial growth apparatus. Molecular beam source 2, 2'
A substrate 3 to be processed is provided correspondingly.

The reason why a plurality of molecular beam sources 2 and 2' are provided is that a source for irradiating each of the constituent elements constituting the compound semiconductor in the form of a molecular beam and a source for irradiating impurity elements are required. In the figure, a Ga molecular beam and an As molecular beam are emitted from a Ga molecular beam source 2 and an As molecular beam source 2' onto a substrate 3 made of GaAs.
A case is shown in which a single crystal thin film of GaAs is epitaxially grown on a substrate 3 to be processed made of GaAs by irradiation to an atomic weight ratio of 1.

To do this, it is necessary to maintain an ultra-high vacuum in the vacuum chamber 1 in order to increase the mean free path of the molecules to be irradiated, and a soap pump or ion pump is used as an exhaust system to reduce the growth of the epitaxially grown film. Molecular beam irradiation is performed while strictly controlling the speed.

That is, the substrate holder 4 on which the substrate 3 to be processed is mounted is configured to be heated by the heater 5 provided on the back surface, but a shroud (not shown) is provided surrounding this, and the vacuum caused by the generation of gas is provided. This prevents the degree of deterioration.

Further, the molecular beam sources 2, 2' are equipped with a heater, a reflector, a shroud, etc. surrounding a crucible 7 containing a raw material 6 serving as a radiation source, and are also provided with a shutter 8 for controlling the irradiation amount.

FIG. 1 is a sectional view of the molecular beam source according to the present invention, and the left half main body 14 and shutter 8 are the same as the conventional one.

That is, there is a heater 9 made of tantalum (Ta) or the like surrounding the crucible 7, a cell is configured with a reflector 10 made of tantalum (Ta), and a shroud 11 is placed outside of the heater 9. There is. Further, a shutter 8 is provided in front of the crucible 7 to control the amount of molecular beam irradiation.

As shown in the figure, the shutter mechanism of the shutter 8 includes a rotating introducer that rotates around the rotating shaft 12 and a linear introducer that slides in a straight line, both of which are operated from outside the vacuum chamber. It is configured.

Now, since molecular beam epitaxial growth is performed by strictly controlling the irradiation dose, even when the crucible 7 is heated by the heater 9 and molecular beam irradiation is performed, the crucible 7 is covered with the shutter 8 and the processing conditions are controlled. At the same time, the shutters 8 provided in the plurality of molecular beam sources 2 and 2' are opened all at once to release the substrate 3 to be processed.
Molecular beam irradiation is performed on the

Therefore, during the time when the shutter 8 is shielding molecular beam irradiation, the raw material elements are vapor-deposited and deposited inside the shutter 8.

For this reason, the weight of the shutter 8 gradually increases and its operation becomes slow. Also, when irradiating a low melting point element such as Ga, which has a low melting point of 29.78°C, the Ga deposited on the shutter 8 will melt due to the heat from the molecular beam source. and
Since the shutter 8 is normally installed at an angle,
Ga flows in one direction and forms droplets.

When the shutter 8 is opened in this state, droplet-shaped Ga
solidifies as a result of heat being taken away by the shroud 11, and when the distance between the shutter 8 and the molecular beam cell is 1~
Because it is narrow, about 10 mm, there may be a problem that the coagulation part hits the molecular beam cell and cannot be closed.

Furthermore, even when irradiating an element such as Ga that does not have a low melting point, the weight of the shutter 8 increases and the shutter operation becomes slow.

For these reasons, it was necessary to stabilize the shutter operation.

[Problem that the invention attempts to solve]

As mentioned above, the shutter installed in the electron beam source of a molecular beam epitaxial growth device is irradiated with molecular beams during the operation of the molecular beam source, and deposition of the irradiated elements occurs. So,
The problem is that the operating speed of the shutter becomes slow, and in some cases it stops operating.

[Means for solving problems]

The above problem can be solved by heating multiple molecular beam sources installed in a vacuum chamber, irradiating the molecular beam onto a substrate to be processed that is placed opposite to the molecular beam source, and releasing the molecules onto the substrate to be processed. In a crystal growth apparatus for forming a thin film of molecular beams, a heating source is provided at the end position of the opening operation of a shutter provided in front of a molecular beam source, and the heating source is energized and heated when the shutter is opened. This problem can be solved by using a line epitaxial growth device.

[Effect]

The present invention solves this problem by heating the shutter to evaporate and scatter the deposits on the shutter.

One possible way to heat the shutter would be to install a heater in the shutter itself, but
Molecular beam epitaxial growth equipment is used for applications that require single-atomic layer growth, such as epitaxial growth of compound semiconductors with a superlattice structure, so the operating speed of the shutter must be approximately 0.1 to 0.2 seconds. From this point of view, it is not desirable to increase the weight of the shutter.

Therefore, in the present invention, a heating source is provided at the end position of the shutter opening operation, and when the shutter on which the molecular beam-forming element is deposited arrives, the heating source is energized to heat the shutter.

There are two types of shutter operating mechanisms: a rotating introducer and a linear introducer.The former allows the shutter to move in an arc, and the latter moves the shutter back and forth in a straight line. A heating source may be provided at the end position.

In addition, when heating the heater with a heat source, there is a concern that the elements deposited on the heater will scatter, adhere to the substrate to be processed, and mix with the molecular beam from the molecular beam source main body, disturbing the growth rate. However, since the material deposited on the shutter 8 is on the inside of the shutter 8 and in the opposite direction to the substrate to be processed, there is no risk of this happening.

〔Example〕

FIG. 1 is a cross-sectional view of a molecular beam source in which a heating source 15 is provided beside a main body 14 equipped with a rotating introducer 13.

Here, the heating source 15 is connected to the side wall 16 of the vacuum chamber.
It is provided at a position opposite to the main body part 14 on both sides of the rotation introducer 13 .

In the case of this embodiment, the heat-resistant insulating substrate 1
There is a heater 18 on top of the heater 6, and around it there is a reflector 1.
9, indicating a heating effect.

During operation of the molecular beam epitaxial growth apparatus, the rotating introducer 13 rotates to open the shutter, and the opening operation ends, that is, the heating source 15
When the shutter 8 reaches a position directly above the shutter 8 and stops, a switch mechanism (not shown) starts energizing the heater 18 and heats the inner surface of the shutter 8.

By using such a method, the raw material elements deposited on the shutter 8 can be removed by evaporation, and a high shutter speed can be maintained.

Note that when a linear introducer is used as a shutter, a heating source may be similarly provided at the end position of the opening operation.

[Effect of idea]

By implementing the present invention, the operating speed of the shutter can be maintained at its original value, thereby making it possible to perform epitaxial growth with high accuracy even in the case of a compound semiconductor having a superlattice structure.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the molecular beam source according to the present invention, Figure 2 is a cross-sectional view of the molecular beam source according to the present invention.
The figure is a conceptual diagram of molecular beam epitaxial growth. 2, 2' are molecular beam sources, 3 is a substrate to be processed, 7 is a crucible, 8 is a shutter, 9, 18 is a heater, 10, 1
9 is a reflector, 11 is a shroud, 13 is a rotating introducer, 14 is a main body, and 15 is a heating source.

Claims (1)

[Claims for Utility Model Registration] A plurality of molecular beam sources 2 and 2' provided in a vacuum chamber 1 are heated, and a substrate to be processed 3 provided opposite to the molecular beam sources 2 and 2' is heated. Irradiate with molecular beam,
In a crystal growth apparatus for forming a thin film made of the molecules on a substrate 3 to be processed, a heat source 15 is provided at the end position of the opening operation of the shutter 8 provided in front of the molecular beam sources 2, 2', 8. A molecular beam epitaxial growth apparatus characterized by comprising a mechanism for energizing and heating a heating source 15 when the opening of the molecular beam epitaxial growth apparatus 8 is performed.