JPH06263587A - Molecular beam epitaxial growth apparatus - Google Patents

Abstract

PURPOSE:To obtain a shutter mechanism causing little leakage of element through the shutter, enabling the growth of an epitaxial film having excellent characteristics in high vacuum, capable of decreasing the cleaning frequency of the shutter and enabling the growth of crystal at high throughput by providing a position-correction mechanism for adjusting the gap between a cell divider and a shutter blade surface from the outside of the growth chamber. CONSTITUTION:The growth chamber 10 of an epitaxial growth apparatus is maintained to a high vacuum of about 10E to 10 Torr. The wall of the growth chamber 10 is provided with usually about 5 sets of molecular beam source cells 20. The crucible 21 has opened bottom and a molecular beam is radiated toward a substrate. The mixing of the radiated molecular beams is prevented by a cell divider 30. A shutter blade 40 is placed between the opening of the crucible 21 and the substrate in such a manner as to be movable with a shutter- driving mechanism 50 to a position to expose the radiation face of the molecular beam. The shutter-driving mechanism 50 is fixed to the growth chamber 10 through a position-correction mechanism 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molecular beam epitaxy apparatus used for epitaxial growth of compound semiconductors, and more particularly to improvement of a shutter mechanism for blocking molecular beams.

[0002]

2. Description of the Related Art The molecular beam epitaxial (MBE) method is
This is a method of performing epitaxial growth by irradiating a molecular beam on a substrate in an ultrahigh vacuum, and is an epitaxial growth method with excellent controllability of the thickness and composition of the grown film. Generally, the thickness and composition of the growth film are controlled by providing a shutter mechanism at the opening of a cell (molecular beam cell) for generating a molecular beam and turning the molecular beam on and off.

Therefore, the operation and structure of the shutter mechanism greatly affects the reproducibility of film thickness and composition. In addition, when the shutter is not sufficiently shielded, especially in the case of a shutter provided in a molecular beam cell of an element having a relatively high vapor pressure such as arsenic, an excessive molecular beam is released into the growth chamber to deteriorate the degree of vacuum. However, the characteristics of the epitaxial growth film are deteriorated.

The conventional shutter mechanism is composed of a shutter blade provided in the opening (radiation surface) of the molecular beam cell and moving in parallel to the radiation surface, and a cell divider partitioning the radiation surface of each molecular beam cell. The shutter blade can be moved from outside the vacuum container by the solenoid. It is desirable that the distance between the shutter blade and the cell divider in the closed state is made as narrow as possible in order to reduce the leakage of the molecular beam from the molecular beam cell.

[0005]

However, it is difficult to make the gap between the shutter blade and the cell divider narrow and to completely seal the cell. If this distance is narrowed, elements released from the molecular beam cell are deposited on these surfaces, so that the distance between the shutter blade and the cell divider is filled, and the shutter blade cannot move. In such a case, it is necessary to open the growth chamber of the high vacuum container and clean the shutter, and it takes a long time to obtain the high vacuum required for the epitaxial growth again, and the throughput is significantly reduced.

The present invention has been made in order to prevent the above-mentioned drawbacks. The element leakage from the shutter is small, an epitaxial film having excellent characteristics can be grown under a high vacuum, and the frequency of cleaning the shutter is high. The objective is to provide a shutter mechanism that can grow at low and high throughput.

[0007]

The present invention provides (a) a growth chamber evacuated to a high vacuum, (b) a molecular beam source cell provided in the growth chamber, and (c) the molecular beam source cell. A cell divider fixed in the vicinity of the radiation surface of (d) a shutter blade that can be moved to a position where the radiation surface of the molecular beam source cell is covered and a position where it is not covered, and (e) the cell divider and the A position correction mechanism capable of adjusting the interval between the shutter blades from the outside of the growth chamber is included. The molecular beam source cell is particularly effective when an element having a relatively high vapor pressure such as arsenic is used as a raw material.

[0008]

[Operation and effect] Since the distance between the cell divider and the shutter blade can be adjusted from the outside of the growth chamber, a position correction mechanism is included, so when the source element adheres to the cell divider or shutter blade, the distance between them can be adjusted from outside the growth chamber. It can be unfolded, and the two will not come into contact with each other to cause damage. Also, the distance between the two can be adjusted at all times, and this distance can be made sufficiently narrow even during epitaxial growth, so there is little leakage of the raw material elements. Therefore, continuous growth is possible for a long period of time, and epitaxial growth is possible in a clean high vacuum, so that the characteristics of the grown film are excellent.

[0009]

EXAMPLE FIG. 1 ((a) is a front view showing a shutter mechanism of an epitaxial growth apparatus which is an example)
(B) is a side view), which will be described in detail below.

The growth chamber 10 of the epitaxial growth apparatus is
A vacuum pump is provided and maintained at a high vacuum of about 10E-10 Torr. A molecular beam source cell 20 is provided on the wall surface of the growth chamber 10. The molecular beam source cell 20 is provided with more than the composition of the growing epitaxial film, usually about 5 sets. The molecular beam source cell 20 is made of Al, Ga, I
It is composed of a conical crucible 21 having an open bottom surface, a heater for heating the crucible 21, and the like. The raw material element is heated to a temperature higher than its melting point by the heater, and a molecular beam is radiated from the opening of the crucible 21 toward the substrate. The substrate is fixed on a substrate holder having a heating mechanism.

A cell divider 30 is provided for separating the molecular beams so that the molecular beams radiated from the opening of the crucible 21 of each molecular beam source cell 20 are not mixed. The cell divider 30 is made of a refractory metal such as Ta and is fixed near the molecular beam source cell 20 in the growth chamber 10. The shutter blade 4 is provided between the opening of the crucible 21 and the substrate.
0 is provided. In FIG. 1, the shutter is closed, and the opening of the crucible 21, which is the radiation surface of the molecular beam, is covered by the shutter blade 40 and the cell divider 30, and the molecular beam does not reach the substrate. The shutter blade 40 is moved by the shutter driving mechanism 50 provided on the wall surface of the growth chamber 10 in a direction parallel to the radiation surface of the molecular beam to a position where the radiation surface is not covered, so that the molecular beam from each molecular beam cell 20 is moved. The line can be turned on and off. The shutter drive mechanism 50 moves the solenoid slug 52 placed in the vacuum chamber by electrically driving an electromagnet 51 provided outside the vacuum, and aims at the shutter blade 40 connected to the solenoid slug 52. Can be moved to a position.

The shutter drive mechanism 50 is fixed to the growth chamber 10 via a position correction mechanism 60. The position correction mechanism 60 includes a pair of flanges 62 connected by a metal bellows seal 61 and an adjusting screw 63 that can adjust the position between the flanges 62. Therefore, the shutter blade 4 can be viewed from the viewing window provided in the growth chamber 10.
While observing the distance between 0 and the cell divider 30, it becomes possible to set the position appropriately by the adjusting screw 63 of the position correcting mechanism 60. The position correction mechanism 60 determines the positional relationship between the growth chamber 10 and the shutter driving mechanism 50.
Other mechanisms may be used as long as they can be moved while maintaining a vacuum of 0.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a shutter mechanism of an epitaxial growth apparatus that is an embodiment ((a) is a front view and (b) is a side view).
Is.

[Explanation of symbols]

 10 growth chamber 20 molecular beam source cell 21 crucible 30 cell divider 40 shutter blade 50 shutter drive mechanism 51 electromagnet 52 solenoid slug 60 position correction mechanism 61 metal bellows seal 62 flange 63 adjustment screw

Claims (1)

[Claims] 1. A growth chamber that is evacuated to a high vacuum, (b) a molecular beam source cell provided in the growth chamber, and (c) is fixed near the radiation surface of the molecular beam source cell. Cell divider,
(d) a shutter blade that can be moved to a position that covers the radiation surface of the molecular beam source cell and a position that does not cover the radiation surface, and (e) the distance between the cell divider and the shutter blade can be adjusted from outside the growth chamber. A molecular beam epitaxial growth apparatus comprising a position correction mechanism.