JPS61122193A - Epitaxial growth with molecular beam - Google Patents

Abstract

PURPOSE:Accurate control of crystal growth is effected by detecting the energy emitted from the base surface and adjusting the opening of the vessel containing the substances to be vaporized or the heating temperature depending on the change in the detected energy. CONSTITUTION:A temperature controller for heating the base is set in the ultravacuum chamber 1 and vessels 4, 5 for containing the substances to be vaporized is set beneath the base 2. Shutters 6, 7 are set above the vessels 4, 5 so that they can close or open the vessels 4, 5. A viewing port 8 is set on the vacuum chamber 1 and an infrared radiation thermometer is set outside the port to detect the infrared energy radiated from the surface of the base 2. The growth of the atomic layer is known from the detection to control the opening of the shutters and opening time. Or the heating temperature of the substances to be vaporized is adjusted. Thus, the epitaxial growth of compound semiconductor with molecular beams can be accurately controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a molecular beam epitaxial growth method for controlling crystal growth of compound semiconductors.

(Prior Art) In the conventionally known molecular beam epitaxial growth method, the intensity of the molecular beam is measured, and the heating temperature and the opening time of the evaporation source storage container are adjusted so that the intensity is constant. The film thickness and single atomic layer growth were controlled.

Furthermore, the opening time and opening diameter of the evaporation source storage container are actually controlled based on empirical factors.

Furthermore, as a method to control the growth of a single atomic layer, reflection-type high-speed electron diffraction has traditionally been used, in which electrons are ejected into the growth layer and reflected, and the growth status of the atomic layer is determined by the reflected electrons. Are known.

(Problems to be solved by the present invention) In the conventional method of measuring the intensity of molecular beams as described above,
Since the crystal growth formed on the substrate is not directly controlled, but is controlled based on an indirect element such as the intensity of the molecular beam, there is a problem that it inevitably lacks accuracy.

In addition, the method of controlling the opening diameter and opening time of the evaporation source storage container is not MI control based on direct information on the surface of the substrate, but is similar to that used for measuring molecular beam intensity in terms of accuracy. There was a problem.

Furthermore, when reflection-type high-speed electron diffraction is used, when the substrate is irradiated with electrons, trace amounts of carbon compounds remaining in the vacuum are decomposed and carbon is deposited on the substrate. This often left problems in quality control, such as impairing the purity of the atomic layer and causing lattice defects in the atomic layer.

The present invention aims to provide a molecular beam epitaxial growth method that enables more accurate control by directly detecting the conditions on the substrate.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an evaporation chamber that installs a substrate in an ultra-high vacuum chamber and houses an evaporation source for an atomic layer to be grown on the surface of the substrate. In the molecular beam epitaxial growth method, in which a source storage container is provided and the material in the container is evaporated to grow an atomic layer on the substrate, infrared energy emitted from the substrate surface is detected, and the evaporation is performed according to changes in the detected energy. Crystal growth is controlled by adjusting the opening diameter, opening time, heating temperature, etc. of the source storage container.

(Action of the present invention) A change in the amount of infrared radiation energy from the outermost atomic layer of the substrate is detected to control single atomic layer crystal growth.

(Effects of the present invention) According to the present invention, crystal growth can be controlled by directly detecting changes in the state of the substrate, which increases accuracy and eliminates the problem of carbon adhesion as in the past. .

(Embodiment of the present invention) Inside the ultra-high vacuum chamber 1, a temperature controller 3 for heating the GaAs substrate 2 is provided, and an evaporation source storage container 4.5 is provided below the GaAs substrate 2.

One container 4 stores gallium Ga, and the other container 5 stores arsenic As. Furthermore, this container is heated by a heater (not shown) to evaporate gallium Ga and arsenic As, which are evaporation sources, and the GaAs substrate 2 is heated.
crystals grow on the surface of

Above the container 4.5 containing the evaporation source as described above,
A shutter 6.7 is provided to open and close the opening, and this shutter 6.7 can adjust the opening time of the container 4.5 and also adjust the opening diameter.

Further, the ultra-high vacuum chamber 1 is provided with a viewing port 8, and an infrared radiation thermometer 9 is provided outside the viewing port 8.

This infrared radiation thermometer 9 is for detecting infrared energy emitted from the surface of the GaAs substrate 2.

In other words, any material, if its temperature is above absolute zero, emits infrared radiation corresponding to its temperature. Therefore, if a predetermined atomic layer grows on the surface of the substrate 2, the atomic layer The infrared rays will be emitted according to the absolute temperature (W).
T' K), W=6σT4 ((is emissivity, σ
is expressed as Stefan Polzmann's constant).

The infrared radiation thermometer 9 detects the temperature of the infrared rays corresponding to the atomic layer and determines the growth status of the atomic layer.

Therefore, in order to grow crystals on the substrate 2, first,
The GaAs substrate 2 is heated to about 600° C. by the temperature controller 3 to remove the oxide layer on the surface of the substrate. When the oxide layer is removed in this way, the arsenic on the substrate 2 is scattered, so sufficient arsenic is irradiated to replenish it.

The outermost atomic layer on the surface of the substrate 2 from which the oxide layer has been removed in this way is an arsenic atomic layer lO, as shown in FIG. 2(a).
becomes.

Next, the shutter 6 of the evaporation source storage container 4 is opened and the GaA
s Start growth. In this case, Ga atoms fly onto the arsenic atomic layer 10, which is the outermost atomic layer on the surface of the substrate 2 before growth, and form a gallium atomic layer 11.

In addition, since As atoms are attached only to the locations where the gallium atomic layer 11 exists, by alternately opening and closing the shutters 6.7, the arsenic atomic layer 11 is removed, as shown in FIGS. The lO and gallium atomic layers 11 will grow alternately 6 and in the above growth process,
The heating temperature of the substrate 2 is kept constant by a temperature controller 3. However, the infrared emissivity from the surface differs depending on whether the atomic layer on the surface is an arsenic atomic layer 10 or a gallium atomic layer 11.

Therefore, by detecting this infrared energy with the infrared radiation thermometer 9, it is possible to grasp the growth status of the atomic layer. The atomic layer growth can be controlled by controlling the aperture diameter and opening time of the shutter 6.7, the heating temperature of the evaporated substance, etc. in consideration of the growth state of the atomic layer detected in this way.

FIG. 3 shows actual measurement results, and the fluctuation period of the output of the infrared radiation thermometer 9 is clarified. From the number of these fluctuation cycles, it is possible to determine the number of atomic layers that have grown.

In the above embodiment, an atomic layer is grown on a GaAs substrate, but it is natural that the above method can be applied to all compound semiconductors such as Zn5e and InP, as well as to different metals.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a schematic diagram of a molecular beam epitaxial apparatus, FIGS. 2(a) to (C) are cross-sectional views of a substrate on which atomic layers have been grown, and FIG. It is a graph showing the intensity change of the infrared radiation energy of & layer. 1... Ultra-high vacuum chamber, 2... Substrate, 4.5... Evaporation source storage container, 10.11... Atomic layer.

Claims (1)

[Claims] A substrate is installed in an ultra-high vacuum chamber, and an evaporation source storage container is provided to store an evaporation source for an atomic layer to be grown on the surface of the substrate. In the line epitaxial growth method, detecting infrared energy emitted from the substrate surface,
A molecular beam epitaxial growth method that controls crystal growth by adjusting the opening diameter, opening time, heating temperature, etc. of the evaporation source storage container according to changes in detected energy.