JPH0431391A - Epitaxial growth - Google Patents

Abstract

PURPOSE:To form heterogeneous structure having interface qualities suitable for a local range having a size of mono-atomic layer in the direction of film thickness by making a raw material molecule of compound semiconductor comprising two or more constituent elements adsorb on a substrate and irradiating an ungrowing range with light rays. CONSTITUTION:A GaAs substrate 13 having cleaned surface is attached to a substrate holder 12, a growing chamber 10 is evacuated into high vacuum by a vacuum pump 11 and the substrate 13 is heated. Then, a material gas of group V is introduced to a molecular beam source 14, the substrate is irradiated with the beam of group V and an oxide layer on the surface of the substrate 13 is removed. Then, one material gas of constituent elements of a compound semiconductor is fed to a molecular beam source 16 to grow a buffer layer and then introduction of the material gas of group V to the molecular beam source 14 is stopped. The substrate is irradiated with molecule of the other material gas from a molecular beam source 17, a monomolecular layer is chemically adsorbed on the surface of the substrate 13 and the substrate 13 is irradiated with energy light having such a sufficient energy to eliminate the adsorbed molecule from a light beam induction inlet 15 to eliminate the adsorbed molecule in an ungrowing range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an atomic layer epitaxial growth method for selectively growing a thin film of a compound semiconductor crystal at a desired location using a molecular beam containing a material element.

[Conventional technology]

The atomic layer epitaxial growth method, in which molecules containing material elements are alternately irradiated onto a heated semiconductor substrate held in a vacuum, is capable of forming steep hetero-growth interfaces at the atomic level, localized film formation by irradiation with light beams, etc. This is an epitaxial growth method with excellent characteristics. An example of the epitaxial growth of gallium arsenide using this growth method is presented at the 49th Annual Meeting of the Japan Society of Applied Physics (Proceedings of the same, Volume 1.4a-W-1゜p).
, 199>. In this conventional example, the group III material is triethyl gallium (abbreviated as TEG).

The molecular formula is (C2Hs)3Ga), and arsine (molecular formula ASH3) is used as the V group material. These gases are alternately irradiated onto a gallium arsenide substrate heated and maintained at the growth temperature in a high vacuum, and argon laser light is irradiated. It is locally grown epitaxially. In this conventional example, a linear pattern with a width of 0.1 mm made of gallium arsenide is formed in a region irradiated with laser light.

[Problem to be solved by the invention]

However, due to the method of growing in the area irradiated with laser light, chemically adsorbed triethylgallium remains in the area not irradiated with laser light, and subsequently reacts with the irradiated arsine to form a gallium arsenide layer. Growth selectivity between areas irradiated with laser light and areas not irradiated was not sufficient. Therefore, it was difficult to form a heterointerface in the in-plane direction.

An object of the present invention is to provide an atomic layer epitaxial growth method that does not require a photolithography step and has excellent growth selectivity and can form a good in-plane heterostructure.

[Means to solve the problem]

The present invention provides a method for epitaxial growth by alternately irradiating molecules containing Group I elements and molecules containing Group V elements onto a semiconductor substrate held and heated in vacuum, which serves as a molecular flow region, which contains elements from one group. This is an epitaxial growth method characterized by irradiating molecules, then locally irradiating light to detach the adsorbed molecules, and then irradiating molecules containing elements of the other group.

[Effect]

In the atomic layer epitaxial growth method according to the present invention, the step of growing one molecular layer consists of the following three steps. That is,
First, the semiconductor substrate is irradiated with molecules containing Group Ⅰ elements to chemically adsorb them on the entire surface. Second, the chemically adsorbed molecules are locally desorbed by irradiation with light. Thirdly, molecules containing a group V element are irradiated onto the entire surface of the substrate to react with the group (I) element chemically adsorbed in the first step to form one molecular layer. As a result of the above steps, a single molecular layer semiconductor layer is selectively formed except for the area irradiated with light in the second step. By repeating this process, a semiconductor layer having the required thickness is selectively formed.

In this growth method, growth is suppressed in non-growth regions by desorbing adsorbed molecules and removing them from the substrate surface. Therefore, selective growth characteristics sufficient to form a heterojunction in the in-plane direction can be achieved. Here, the wavelength of the light used in the second step needs to be set to a wavelength that will be absorbed by the bonds of chemically adsorbed molecules. This is because in this second step, the chemisorbed molecules are desorbed by applying the energy necessary for desorbing the chemisorbed molecules from the light. However, it is necessary to select the temperature of the semiconductor substrate at a temperature at which a single molecule of the irradiated molecule is adsorbed.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram of an atomic layer epitaxial growth chamber for explaining the present invention in detail. In this example, the group III material is dimethyl gallium chloride (molecular formula: (CH3) 2 G
aC1), dimethylindium chloride (molecular formula,
(CH3)2 IIIC1) and arsine (molecular formula, AsH3) are used as the group II material, and these gases are irradiated onto a GaAs substrate heated and maintained at the growth temperature in a high vacuum to achieve epitaxial growth in the following steps. Ta. Growth room 10
A substrate holder 12 that heats and holds the GaAs substrate 13 to a growth temperature, an As molecular beam source 14, a light beam introduction port 15,
It is equipped with a dimethyl gallium chloride molecular beam source 16 and a dimethyl indium chloride molecular beam source 17, and is evacuated to a high vacuum by a vacuum pump IJ-. The As molecular beam source 14 is equipped with a heater for thermally decomposing arsine gas, and the arsine gas is heated to 950°C by this heater.
The dimethyl gallium chloride molecular beam source 16 and the dimethyl indium chloride molecular beam source 17 are also equipped with heaters inside, and dimethyl gallium chloride gas and dimethyl indium chloride gas are heated and thermally decomposed into two As molecules. by 400
℃ and thermally decomposed to form gallium chloride molecules (molecular formula GaC1) and indium chloride molecules (molecular formula GaC1), respectively.
The molecular formula is I nCI ). Furthermore, an argon laser beam with a wavelength of 545 nm was used as the light beam, and the beam was deflected by a deflection optical system and introduced from the light beam inlet 15.

An example of forming a stripe structure made of IIIAs on the GaAs substrate 13 without a mask will be shown below. First, a GaAs substrate 13 whose surface had been cleaned by chemical etching and degassing treatment was attached to the substrate holder 12 and disposed of using the vacuum pump 11 to create a high vacuum in the growth chamber. next,
Heating of the GaAs substrate 13 is started, and the substrate temperature reaches 400°C.
At the point when the temperature exceeded 1, arsine gas was introduced into the As molecular beam source 14, and an As beam was irradiated to remove the oxide layer on the surface of the substrate. After the substrate temperature reached the growth temperature of 450° C., dimethyl gallium chloride gas was introduced into the dimethyl gallium chloride molecular beam source 16 to grow a buffer layer of about 1100 nm. Subsequently, the substrate temperature was maintained at 350° C. and a heteroepitaxial layer was grown in the following manner. That is, firstly, As
The introduction of arsine gas into the molecular beam source 14 is stopped, and indium chloride molecules are irradiated from the dimethylindium chloride molecular beam source 17 to chemically adsorb one molecular layer onto the surface of the GaAs substrate 13. At this time, excess indium chloride molecules are not adsorbed onto the surface of the chemical adsorption layer, so chemical adsorption of one molecular layer is automatically achieved. Second, the light introduction port 15
The surface of the GaAs substrate 13 was irradiated with an argon laser beam, leaving a stripe-like formation with a width of 5 μm and scanning the remaining portion. At this time, the chemically adsorbed molecules in the area irradiated with light are desorbed. Third, As molecular beam source 1
As2 molecules were irradiated from No.4. Through the above first to third steps, one molecular layer of a striped InAs epitaxial layer was formed. By repeating this process in combination with the growth of only gallium arsenide, a heteroepitaxial layer having a striped InAs quantum well structure serving as a light guide can be grown in a GaAs single crystal thin film.

In the above example, gallium chloride and indium chloride were used as the group (III) material molecules to be chemically adsorbed, and dimethyl gallium chloride and dimethyl indium chloride were used as the material compounds, but organic metals with other organic groups such as dimethyl gallium chloride Also, gallium chloride (molecular formula, G
aC1) Indium chloride (molecular formula, GaCI)
It is also possible to directly generate and introduce chlorides such as these by reacting a Group 1 material with hydrogen chloride.

In the above embodiments, alkylated compounds such as III) or gallium chloride (molecular formula, Ga
C1) Chlorides such as indium chloride (molecular formula, GaC1) may be used In the above examples, alkyl compounds of gallium and indium were used as material compounds, but aluminum, phosphorus, arsenic, antimony, zinc, beryllium, etc. Other constituent elements of compound semiconductors and impurity organic compounds and chlorides may also be used.

〔Effect of the invention〕

In the epitaxial growth method according to the present invention, it is possible to form a heterostructure having good interface quality in a local region having a size about the diameter of a light convergence in the in-plane direction and one atomic layer in the layer thickness direction.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an atomic layer epitaxial growth chamber in one embodiment of the present invention, 10...growth chamber, 11...vacuum pump, 12...
Substrate holder, 13...GaAs substrate, 14...As
Molecular beam source, 15... Light beam inlet, 16... Dimethyl gallium chloride molecular beam source, 17... Dimethyl indium chloride molecular beam source are shown, respectively.

Claims (1)

[Claims] 1. On a substrate placed in a vacuum serving as a molecular flow region, 2.
In a method for growing a compound semiconductor composed of more than one type of constituent elements, following the step of supplying raw material molecules of the compound semiconductor onto the substrate and allowing them to be adsorbed, light with sufficient energy to detach the adsorbed molecules from the substrate is emitted. An epitaxial growth method characterized by comprising a step of irradiating a non-growth region. 2. The compound semiconductor is grown by repeatedly performing the step of irradiating the substrate with raw material molecules made of a Group III compound, light, and raw material molecules made of a compound of a Group V element in this order. Epitaxial growth method.