JPS63176392A - Molecular beam crystal growth apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Summary] The present invention provides a molecular beam crystal growth apparatus in which the substrate holder is placed between a substrate holder that supports a substrate on which a single crystal is grown and a heater that heats the substrate. By providing heat shielding means to control the temperature of the substrate holder, the uniformity of the temperature distribution within the substrate surface is improved and the single crystal layer grown is improved.

[Industrial application field]

The present invention relates to a molecular beam crystal growth apparatus, and particularly to a molecular beam crystal growth apparatus that improves the uniformity of epitaxial growth by improving the temperature distribution of a single crystal substrate on which growth is performed.

2. Description of the Related Art Substrates in which a required single crystal layer is epitaxially grown on a single crystal substrate are widely used in semiconductor devices and the like. Various methods are used for epitaxial growth, but the molecular beam crystal growth method (MB2 method) allows the most accurate control of the crystal growth rate, composition ratio of the mixed crystal, amount of impurity doping, etc. Most suitable for precise crystal growth such as superlattice structures.

However, the MB2 method not only has a lower growth rate than other growth methods, but also has conventionally been difficult to achieve uniform growth, and there is a strong demand for improvement.

[Prior Art] In the MBE method, elements constituting a target single crystal and impurity elements to be doped are evaporated from a cell in a high vacuum of about 10-'' Torr in the form of a molecular beam, and then evaporated onto a single crystal substrate. This is a method in which a single crystal layer is grown epitaxially, and the main part of the apparatus is constructed as shown in the schematic diagram shown in FIG. 4, for example.

In the figure, 1 is a mechanism for supporting and heating the substrate, 2 is a molecular beam source cell, 3 is a liquid nitrogen shroud, and 4A is an II H
The electron gun for EED, 4B is a fluorescent screen for RHEED, and a single crystal substrate 10 for growing a single crystal is attached to a mechanism 1 for supporting and heating the substrate, for example, as described below.

Conventionally, a mechanism 1 for supporting and heating the substrate has a structure as illustrated in FIG. That is, 11 is a substrate holder made of, for example, molybdenum (MO), 12 is a spacer made of, for example, boron nitride (BN), 13 is a heat soaking plate made of, for example, BN, 14 is a heater, and 15 is a rotation mechanism. 10 is a single crystal substrate.

The single crystal substrate 10 is heated on the substrate holder 11 by radiant heat from the heater 14 to a temperature selected as the optimum substrate temperature, for example, 600 to 700 ℃ for gallium arsenide (GaAs).
°C1 Silicon (Si) is heated to about 700 to 800 °C, but the substrate temperature depends on the growth rate of the single crystal layer, the crystal state,
In order to have a large influence on the composition of the multi-component compound, impurity doping concentration, etc., it is necessary to have a temperature distribution within, for example, about ±5° C. at the above-mentioned temperature.

[Problem that the invention seeks to solve]

In the conventional mechanism for supporting and heating the substrate, the heater 1
The radiant heat from 4 also strongly heats the substrate holder 11, making it hotter than the single crystal substrate 10, and heat inflow from the substrate holder 11 to the single crystal substrate 10 causes temperature non-uniformity in which the peripheral portion becomes hotter than the central portion. This causes a problem in the uniformity of the grown single crystal layer.

[Means for solving problems]

The above-mentioned problem is solved by the molecular beam crystal growth method according to the present invention, which is provided with means for thermally shielding the substrate holder from the heater between the substrate holder that supports the substrate on which a single crystal is to be grown and the heater that heats the substrate. Solved by the device.

Note that, for example, a heat reflecting plate can be used as the heat shielding means.

[For production]

According to the present invention, as illustrated in FIG.
By appropriately controlling the temperature of 1, and therefore the amount of heat conduction between the substrate holder 11 and the substrate 10, the uniformity of the temperature distribution within the plane of the substrate 10 can be improved, and the uniformity of the growing single crystal layer can be improved. Improve.

〔Example〕

The present invention will be specifically explained below using examples.

FIG. 2 is a schematic diagram showing the mechanical parts for supporting and heating the substrate in the first embodiment of the present invention, in which 11 is a substrate holder, 12 is a spacer, 13 is a heat equalizing plate, 14 is a heater, 15 16 is a rotation mechanism, 16 is a heat reflection plate that performs heat shielding according to the present invention, and 10 is a single crystal substrate on which a single crystal is grown.

For example, Mo is used for the substrate holder 11 of this embodiment,
The diameter of the substrate mounting surface is approximately 190 mm, and six substrates each having a diameter dW of approximately 51 nut+ can be mounted rotationally symmetrically, and the inner diameter d0 of each opening is approximately 45 mm.

Further, the heat reflecting plate 16 has a structure in which, for example, four 0.1 mm thick Tantanon Ta) plates are laminated with a pinch of 0.5 mm.
The inner diameter d1 is approximately 4 at a position concentric with each opening of the substrate holder 11.
An opening of 0 mm is provided.

Note that the distance between the heater 14 and the substrate holder 11 is about 5 mm as in the conventional example, and the heat reflection plate 16 rotates together with the substrate holder 11 at a speed of, for example, about 20 rpm or less about the central axis of the substrate mounting surface as the rotation axis. be able to.

Further, FIG. 3 is a schematic diagram showing a second embodiment of the present invention, and corresponding parts are indicated by the same reference numerals as in FIG. 1. The substrate holder 11 of this embodiment has one substrate mounted thereon, similar to the conventional example.

As shown in the figure, the heat reflecting plate 16 of this embodiment is made of a Ta plate having a coaxial cylindrical shape whose axis direction is perpendicular to the substrate mounting surface of the substrate holder 11, and whose thickness, number, and pitch are similar to those of the previous embodiment. , a heater 14 is provided inside this cylinder.

In each of the above embodiments, for example, at a temperature of 680° C. suitable for MBE growth of gallium arsenide (GaAs), a temperature distribution within ±5° C. is ensured over the entire surface of the substrate 10 with a margin.

Regarding the first embodiment, the molecular beam source cell 2 is a Langmuller type with a large opening, and the molecular beam is incident on the entire surface of the substrate holder 11 with good uniformity, and a high electron mobility field effect transistor is formed on a GaAs single crystal substrate. Non-doped G for
An aAs layer, an AlGaAs layer selectively doped with Si, and a GaAs layer doped with SL were successively grown.
A uniform and good single crystal layer was obtained, with variations in the thickness of each semiconductor layer, impurity concentration, etc. between the substrates and within the plane of each substrate being within 1%.

〔Effect of the invention〕

As explained above, according to the present invention, the uniformity of a single crystal layer can be improved by molecular beam epitaxial growth, and the structure of the device is simple and easy to implement, such as a semiconductor device with a superlattice structure. Remarkable effects can be obtained in development and practical application.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle of the present invention, Figure 2 is a schematic diagram of the first embodiment of the present invention, and Figure 3 is a diagram of the second embodiment.
Fig. 4 is a schematic diagram of a molecular beam crystal growth apparatus; Fig. 5 is a schematic diagram of a conventional example of a substrate support and heating mechanism of a molecular beam crystal growth apparatus; In the figure, 1 supports the substrate. , a heating mechanism; 11 is a substrate holder; 12 is a spacer; 13 is a heat soaking plate; 14 is a heater; 15 is a rotating mechanism; 16 is a heat reflection plate that performs heat shielding according to the present invention; 2 is a molecular beam source cell; 10 indicates a single crystal substrate on which a single crystal is grown. 2nd Sensen 4 Leap 5 Cause

Claims (2)

[Claims] (1) Molecular beam crystal growth characterized in that a means for thermally shielding the substrate holder from the heater is provided between a substrate holder that supports a substrate on which a single crystal is to be grown and a heater that heats the substrate. Device. (2) The molecular beam crystal growth apparatus according to claim 1, wherein a heat reflection plate is used as the heat shielding means.