JPS6297319A - Molecular beam crystal growing apparatus - Google Patents

Abstract

PURPOSE:To enable the crystal growth of high throughput by observing and evaluating the crystal substrate mounted on a fixed substrate supporter during the crystal growth to enable the control of the crystal growth over the crystal substrates mounted on rotary substrate supporters, thereby maintaining the uniformity of crystal growth. CONSTITUTION:A fixed substrate supporter 9 is fixed, the teeth cut in the outer periphery thereof engage with the teeth cut in the outer peripheries of rotary substrate supporters 10-12, and the teeth cut in the outer peripheries of the rotary substrate supporters 10-12 respectively engaged with the teeth cut in the inner periphery of a substrate supporter 8, thereby rotating the substrate supporter 8. With this, the rotary substrate supporters 10-12 revolved both on their axis and round the fixed substrate supporter 9. That is, so-called planetary movement is performed. By radiating an electron beam from an electron gun 6 to the substrate mounted on the fixed substrate supporter 9, the oscillation of the diffraction signal of an reflected electron beam is observed. From this oscillation period, the growth rate of the atomic layer order is controlled.

Description

[Detailed Description of the Invention] [Summary] When creating crystalline materials for devices using the molecular beam crystal growth (MBE) method, simultaneous observation during crystal growth is possible to control film thickness, crystal composition ratio, etc. A substrate support with a unique structure is proposed.

[Industrial application field]

The present invention relates to a molecular beam crystal growth apparatus, and more particularly to a structure of a substrate support that enables precise control of molecular beam crystal growth through simultaneous observation during crystal growth.

The MBE method has many features, such as the ability to easily form heterojunctions, the ability to grow highly uniformly, the ability to easily grow thin film multilayer structures (superlattice structures), and the ability to control film thickness on the order of atomic layers.

Taking advantage of this feature, the MBE method can be applied to high electron mobility transistors (HEMTs), hetero bipolar transistors (
It is widely used to create materials for optical devices such as high-speed transistors such as HBT), single-layer or multilayer quantum wells (SQLor MQW), and superlattice avalanche photodiodes (APD).

In order to fabricate the above-mentioned devices, it is necessary to control the film thickness with high precision, and for this reason, an apparatus with a structure that allows monitoring during crystal growth is desired.

[Conventional technology]

In the MBE method, as a simultaneous observation method for controlling film thickness, crystal composition ratio, etc., there is a method of evaluating molecular beam intensity with a beam flux monitor.

However, with this method, the evaluation is indirect, and crystal growth cannot be precisely controlled.

In addition, as an indirect control method, the substrate is taken out from the apparatus and the thickness is measured using a tarry step or the like before and after crystal growth. This method involves post-observation, and of course precise control is not possible.

Furthermore, as a method for simultaneous observation, reflection electron diffraction (RH
I! When the HD) method is used, control on the order of atomic layers is possible based on the period of the reflected diffraction signal (one period corresponds to one atomic layer). However, with this method, the substrate must be fixed during crystal growth when electron beam irradiation and reflection diffraction signals are simultaneously observed. This method will now be explained with reference to FIG.

FIG. 2 is a schematic diagram of a conventional MBE device having a structure that can be monitored by RHEBD.

In the figure, 1 is the furnace body of the MBE apparatus, 2 is the rotating part of the substrate support, 3 is the heater part of the substrate support, 4 is the crystal substrate, and 5.5' is the molecular beam source cell [gallium (Ga), arsenic (As)), 6 is an electron gun, and 7 is a screen.

In crystal growth using this apparatus, first, the crystal substrate 4 is raised to a desired temperature (550 to 750°C). Next, the temperature of the molecular beam source cell 5.5' is raised to emit each molecule. RHE
When performing simultaneous observation using ED, the rotation of the crystal substrate 4 is stopped, an electron beam is emitted from the electron gun 6 to the center of the crystal substrate 4, and this diffraction image is transferred onto the screen 7. The growth rate can be determined by the strength of the signal on the screen and the vibration period (one period corresponds to one atomic layer).

In this case, as described above, the rotation of the substrate is stopped during monitoring, so this substrate cannot be used as a device manufacturing substrate.

[Problem that the invention seeks to solve]

Monitoring crystal growth through simultaneous observation using conventional equipment required the rotation of the substrate to be stopped, making it impossible to precisely control crystal growth.

[Means for solving problems]

The solution to the above problem is to use a fixed substrate supporter (9) installed at the center of the molecular beam, a fixed substrate supporter (9) placed around the fixed substrate supporter (9), and a fixed substrate supporter (9) that rotates on its axis.
A rotating substrate support (10) that can revolve around the
, (11), and (12) is installed in the furnace body (1), and the fixed substrate support (8) is installed in the furnace body (1) during crystal growth.
A book that enables control of crystal growth on crystal substrates placed on rotating substrate supports (10), (11), and (12) by observing and evaluating crystal substrates placed on rotating substrate supports (10), (11), and (12). This is achieved by the molecular beam crystal growth apparatus according to the invention.

[Effect]

The present invention utilizes an MBE apparatus that includes a fixed substrate support for a monitor substrate in the center of the substrate support, and a rotating substrate support for a plurality of device substrates having a mechanism capable of rotating and revolving around the substrate support. This enables monitoring and observation without stopping the rotation of the device substrate during growth, allowing precise control of crystal growth.

〔Example〕

FIG. 1 is a schematic diagram of an MBB device having a structure that can be monitored by RHEED according to the present invention.

In order to explain the main parts of the device, the figure shows a substrate support part in a perspective view, and the entire device is shown in a side sectional view.

In the figure, 1 is the furnace body of the MBB device, 2 is the rotating part of the substrate support, 4 is the crystal substrate, and 5.5' is the molecular beam source cell (G
a, As), 6 is an electron gun, 7 is a screen, 8 is a substrate supporter, a fixed substrate supporter 9 and a rotating substrate supporter 10.
11.12.

The fixed substrate support 9 is fixed, and the teeth cut on its outer periphery mesh with the teeth cut on the outer periphery of the rotating substrate supports 1o, 11.12. The teeth cut into the inner circumference of the substrate support 8 mesh with the teeth cut on the inner circumference of the substrate support 8, and by rotating the substrate support 8, the rotating substrate supports 10, 11, and 12 rotate around the fixed substrate support 9. It is now possible to perform so-called planetary motion, revolving around the Earth.

This example has a substrate support 8 capable of growing three substrates in one patch, and three device substrate supports move planetarily around a fixed substrate support 9.

Since the fixed substrate support 9 for monitoring is fixed, simultaneous observation and measurement is possible even during crystal growth.

By emitting an electron beam from the electron gun 6 to the substrate placed on the fixed substrate supporter 9, the vibration of the reflected electron beam diffraction signal can be observed. The growth rate on the order of atomic layers can be controlled by this vibration period.

As a result, the film thickness and crystal composition ratio can be instantly known during growth, making precise control possible.

In the examples of the present invention, RHEED was used as the evaluation method, but it is also applicable to optical evaluation methods such as ellipsometry.

〔Effect of the invention〕

As described in detail above, according to the present invention, the device substrate continues to rotate even during monitoring, so that the uniformity of crystal growth can be maintained. Furthermore, unlike conventional methods, there is no monitor growth, and observation data can be immediately fed back to the growth control system during growth, making highly controlled, high-throughput crystal growth possible.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an MBE device according to the present invention having a structure that can be monitored by R)IEED, and FIG. 2 is a schematic diagram of a conventional MBI' device having a structure that can be monitored by RHEED. In the figure, 1 is the furnace body of the MIE apparatus, 2 is the rotating part of the substrate supporter, 3 is the heater part of the substrate supporter, 4 is the crystal substrate, 5.5' is the molecular beam source cell (Ga % As) 6 is the 7 is a screen, 8 is a substrate supporter, 9 is a fixed substrate supporter, and 10.11.12 is a rotating substrate supporter. Patent appearance artificial, 2 technique i director Tatsuki Todoroki g: 40 masters E trick grass 1 field

Claims (1)

[Claims] Fixed substrate support (9) installed at the center of the molecular beam
and rotating substrate supports (10), (11), (12) arranged around the fixed substrate support (9) and capable of rotating and revolving around the fixed substrate support (9).
A substrate supporter (8) having a substrate support (8) is installed in the furnace body (1),
During crystal growth, the crystal substrate placed on the fixed substrate support (9) is observed and evaluated, and the rotating substrate support (10), (11)
), (12) A molecular beam crystal growth apparatus characterized in that it is possible to control crystal growth on a crystal substrate placed on the crystal substrate.