JPH0541356A - Crystal growth apparatus - Google Patents

Abstract

PURPOSE:To obtain a crystal growth apparatus wherein a more stoichiometric crystal growth operation is executed. CONSTITUTION:The title apparatus is featured in the following manner: wafers 3 for monitoring use are arranged in the outer circumferential part of wafers 2, to be grown, which have been arranged on a substrate plate 1 for crystal growth use; a heating means in which the growth temperature of the wafers 3 for monitoring use becomes higher than that of the wafers 2 to be grown is provided; a group III-rich growth operation is executed to the wafers 3 for monitoring use; a group V-rich crystal growth operation is executed to the wafers 2 to be grown; the wafers 2 to be grown can be grown in a more stoichiometric state; and a crystalline stoichiometry can be monitored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal growth apparatus for performing stoichiometric crystal growth.

[0002]

2. Description of the Related Art Molecular beam epitaxial growth (MBE)
Is for growing crystals by irradiating a heated substrate (wafer) such as GaAs or InP with a molecular beam, and its conceptual diagram is shown in FIG. In FIG. 3, reference numeral 1 is a crystal growth substrate plate, 2 is a growth wafer (for example, a GaAs wafer) arranged on the substrate plate 1, and 4 is a substrate plate on which the growth wafer 2 is placed. 1 is a susceptor on which 5 is placed, 5 is a heater for heating the substrate plate 1 built in the susceptor 4, 6 is a crystal growth chamber for holding the substrate plate 1 together with the susceptor 4, and 7 is a liquid nitrogen shroud , 8 is a molecular beam with which the wafer for growth 2 is irradiated, 9 is a crucible, 10 is a K-cell heater wire formed by spirally winding a tungsten wire of 0.5 to 1 mm, and 11 is housed in the crucible 9. A group V molecular beam source, 12 is also a group III molecular beam source, and 13 is a substrate plate rotating mechanism for rotating the substrate plate 1 held in the crystal growth chamber 6.

A normal MBE apparatus uses a substrate plate 1 for crystal growth on which only a wafer for growth 2 is arranged as shown in FIG. 2A, and the temperature gradient of substrate heating is shown in FIG. As described above, the outer peripheral portion of the substrate plate 1 is usually lower than the central portion of the substrate plate 1.

In FIG. 2, a substrate plate 1 capable of simultaneously growing three 3φ wafers is taken as an example.

[0005]

The conventional substrate plate 1 for crystal growth does not have a monitor function for performing more stoichiometric crystal growth, and it is customary to carry out the growth in a state where the group V molecular beam is excessive. Therefore, the crystallinity of the crystal grown under such conditions deteriorates by the amount deviated from stoichiometry.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a crystal growth apparatus having a monitor function for performing more stoichiometric crystal growth.

[0007]

A crystal growth apparatus according to the present invention comprises heating means for heating a substrate plate such that the temperature gradient of the substrate plate is higher on the peripheral side of the substrate plate than on the central part of the substrate plate. A monitor wafer is arranged on the outer peripheral portion of the substrate plate, and the monitor wafer monitors the stoichiometry of crystallinity.

[0008]

In the present invention, the monitor wafer on the outer peripheral portion of the substrate plate is heated so as to have a temperature higher than that of the wafer to be grown on the central portion of the substrate plate. The growth wafer is liable to be Group III rich (Rich) compared to the central portion of the substrate plate (the surface of the wafer becomes cloudy), and the growth of the monitor wafer becomes cloudy while the growth wafer does not become cloudy. Wafers will grow closer to stoichiometry.

[0009]

The present invention will be described below. Figure 1
(A), (b) is a figure which shows the substrate plate for crystal growth used for this invention, and the temperature gradient in the substrate plate. Here, an example of the substrate plate 1 capable of simultaneously performing crystal growth on three 3φ wafers is shown. Board plate 1
To be grown 2 in which crystals are actually grown near the center of the wafer
Are arranged, and one to three monitor wafers 3 are arranged on the outside thereof. Since the temperature gradient of the substrate plate 1 is slightly higher in the outer peripheral portion of the substrate plate 1 (about 5 to 10 ° C. than in the central portion), the group V molecular beam is uniformly irradiated in the plane of the substrate plate 1. In this state, the desorption of the group V molecules from the attachment surface is higher at a higher temperature, so that the wafer for monitoring is more than the wafer for growth 2 in the central portion of the substrate plate 1 on which the wafer for monitoring 3 is arranged. 3 is more likely to be a group III Rich. In order to obtain the above temperature distribution, for example, a carbon heater may be used as the heater 5 and the in-plane temperature distribution can be set to a desired distribution by controlling the thickness thereof.

Usually, in the case of III-V group compound crystal growth, V
The growth surface of the group Rich is a mirror surface, while the growth surface of the group Rich is cloudy from the mirror surface. Therefore, it is possible to distinguish between the group III Rich and the group V Rich from the crystal growth surface. That is, there is a temperature distribution in the surface of the substrate plate 1, and As pressure is applied so that only the monitor wafer 3 in the outer peripheral portion becomes cloudy, so that the stoichiometry of the growth wafer 2 in the inner peripheral portion is confirmed. be able to. It can be considered that it is close to stoichiometry that the perfect mirror surface can be made to the limit of the cloud point.

Stoichiometric crystal growth is the lowest V where the growth surface is free of mirror turbidity due to III group Rich.
It is feasible in the growth carried out with the supply of group molecular beams. Therefore, the growth target wafer 2 in the central portion of the substrate plate 1 is more likely to be III group Rich than the growth target wafer 2 in the peripheral portion thereof. When the surface of the wafer 2 is a mirror surface, it can be said that the crystal of the wafer for growth 2 is in a state closer to stoichiometry. By using such a method, it is possible to determine whether or not it is close to stoichiometry even in the case of group V Rich crystal growth. Note that Mo is generally used as the material of the substrate plate 1.

Further, as an actual device using the above-mentioned crystal growth apparatus, the noise figure of HEMT is lowered and β of HBT is decreased.
It is possible to realize a device having an improved (current amplification factor).

[0013]

As described above, according to the present invention, the growth wafer is arranged from the central portion of the substrate plate, and the monitor wafer for monitoring stoichiometry is arranged in the peripheral portion of the substrate plate. Since the heating means is provided so that the temperature of the peripheral portion of the substrate plate becomes higher than that of the central portion of the substrate plate, the crystallinity grown on the wafer for growth can be formed more stoichiometrically. Therefore, a device using such a crystal has an effect of activating carriers and increasing mobility.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a substrate plate of the present invention and a temperature gradient thereof.

FIG. 2 is a diagram showing a configuration of a conventional substrate plate and its temperature gradient.

FIG. 3 is a configuration cross-sectional view showing an outline of an MBE device.

[Explanation of symbols]

 1 substrate plate 2 wafer for growth 3 wafer for monitoring 4 susceptor 5 heater for heating 6 chamber for crystal growth 7 liquid nitrogen shroud 8 molecular beam 9 crucible 10 K-cell heater beam 11 V group molecular beam source 12 III group molecular beam source 13 Substrate plate rotation mechanism

Claims (1)

[Claims] 1. A substrate plate for crystal growth on which a required number of wafers for growth is arranged is held in a chamber for crystal growth, and the wafer for growth is heated and irradiated with a molecular beam to produce the substrate. In a crystal growth apparatus for growing crystals on a wafer for growth, for a monitor arranged on the outer peripheral portion of the substrate plate from the position of the wafer for growth on the substrate plate on which the wafer for growth is arranged. A wafer and a heating unit that heats the monitor wafer so that the growth temperature of the monitor wafer is higher than the temperature of the wafer to be grown, and the crystallographic stoichiometry of the wafer to be grown is measured by the monitor wafer. A crystal growth apparatus characterized by being configured to monitor.