JPH0349214A - Method for epitaxial growth - Google Patents

Abstract

PURPOSE:To grow a compound semiconductor crystal film well by irradiating with molecules, consisting of III group element molecules or V group element molecules, and then locally irradiating with light, and then irradiating with molecules, belonging to the same group as said molecules but consisting of different element. CONSTITUTION:Introduction of arsine gas into an As molecule source 14 is stopped, and the surface of a GaAs substrate 13 is irradiated with TEG molecules from a TEG molecular beam source 16 to chemically adsorb a monomolecular layer thereto. Then, the surface of the GaAs substrate 13 is irradiated with Ar laser light through a light introducing port 15 and scanned and depicted in stripe-like shape with a predetermined width. Next, when irradiation with TEI molecules from a TEI molecular beam source 17 is carried out, a monomolecular layer having In atoms is chemically adsorbed selectively to a region wherein the chemically adsorbed layer is vanished by the irradiation with the light. Further, irradiation with As molecules from the As molecule source 14 is effected. Consequently, a hetero-epitaxial layer having a GaAs monomolecular layer is formed. This process and growth of only gallium arsenide are combined and repeated to obtain a hetero-epitaxial layer having a well structure, i.e. a light guide, in a GaAs monocrystalline film.

Description

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

[Conventional technology 1] 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 characterized by the formation of a steep hetero-growth interface at the atomic level and by irradiation with a light beam, etc. This epitaxial growth method has excellent features such as localized film formation. An example of the epitaxial growth of gallium arsenide using this growth method is given in the 49th Japan Society of Applied Physics Academic Conference (Proceedings of the same, Volume 1, 4a-'W-1).
, p. 199). In this conventional example, the group III material is triethyl gallium (abbreviation: TEG, molecular formula: C
, H, L Ga), arsine (molecular formula As
Using H, ), 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 to cause local epitaxial growth. 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.

[Problems to be Solved by the Invention] However, since the conventional example described above uses a method in which growth is performed in a region irradiated with laser light, it is not possible to simultaneously form a heterointerface in the in-plane direction, and the surface that should become a heterointerface cannot be formed at the same time. There was a problem in forming a good hetero interface because of the exposure.

An object of the present invention is to provide an atomic layer epitaxial growth method that can form a good in-plane heterostructure without using a photolithography process.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides molecules containing group M elements and molecules containing group V elements on a semiconductor substrate heated while being held in vacuum, which serves as a molecular flow region. In a method of epitaxial growth by alternating irradiation, after irradiating the molecule containing the group (I) or group V element, light is locally irradiated, and then the molecule containing an element of the same group as the element contained in the molecule and different from the above element is irradiated with light. It is something that irradiates.

[Function] In the atomic layer epitaxial growth method according to the present invention, the step of irradiating molecules containing group (I) or group V elements consists of the following three steps. That is, first, a semiconductor substrate is irradiated with molecules containing element A, which is a group I or group V element, and is chemically adsorbed on the entire surface. Second, the chemically adsorbed molecules are locally released by irradiating light locally. Third, the entire surface of the substrate is irradiated with a molecule containing an element B, which is the same group as the element A contained in the molecule but different from the element, and the element B is selectively applied to the regions locally separated by the light. chemically adsorbs the molecules it contains. As a result of the above steps, it is possible to obtain a chemisorption layer in which molecules containing element B are chemically adsorbed in the area where the semiconductor substrate surface is irradiated with light, and molecules containing element A are chemically adsorbed in the area where it is not irradiated. can. By repeating the formation of chemisorption layers in this step alternately for group (I) and group V, a structure having heterojunctions in the plane and in the stacking direction can be formed. 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 adsorbed molecules are released by imparting the energy necessary for releasing them from the light to the chemisorbed molecules. Furthermore, in the third step, the reason why molecules containing element B are selectively chemisorbed to the region locally separated by light is as follows. That is, after the second step, on the surface of the semiconductor substrate, there are chemically adsorbed molecules in the area where the light was not irradiated, and there is no layer of chemically adsorbed molecules in the irradiated area. After this, when molecules containing element B are irradiated in the third step, new adsorption is hindered because regions of the molecular layer that have already been chemically adsorbed are inert to adsorption. On the other hand, adsorption occurs in areas where there is no adsorption layer. As a result, molecules containing element B can be selectively chemically adsorbed only in the region where the surface of the semiconductor substrate is irradiated with 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 Ⅰ materials include triethylgallium (molecular formula, (C,H,), Ga) and triethylindium (molecular formula, (C,H,)).

In), arsine was used as the V group material, and epitaxial growth was performed by irradiating these gases onto a gallium arsenide substrate heated and maintained at a growth temperature in a high vacuum in the following steps.

In the figure, a growth chamber 10 is equipped with a substrate holder 12 that holds a GaAs substrate 13 and heats it to the growth temperature. A radiation source 16 and a TEI molecular beam source 17 are connected. Further, the inside of the growth chamber 10 is evacuated to a high vacuum by a vacuum pump 11. The light beam has a wavelength of 545
An argon laser beam of nm wavelength was used, was deflected by a deflection optical system, and was introduced from the light beam introduction port 15.

The arsenic 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 and is thermally decomposed into arsenic molecules (molecular formula: As).

When growing a heteroepitaxial layer having InAs thin lines in a GaAs single crystal thin film, the following steps are performed. First, a GaAs substrate 13 whose surface has been cleaned by chemical etching and degassing treatment is attached to the substrate holder 12 and evacuated to a high vacuum using the vacuum pump 11. Next, the GaAs substrate 1
3, and when the substrate temperature exceeds 400° C., arsine gas is introduced into the arsenic molecular beam source 14 and an arsenic beam is irradiated to remove the oxide layer on the substrate surface. After the substrate temperature reaches the growth temperature of 450° C., TEG gas is introduced into the TEG molecular beam source 16 to grow a buffer layer to a thickness of about 100 nm. Subsequently, the substrate temperature was maintained at 350° C. and a heteroepitaxial layer was grown in the following manner. That is, first, the introduction of arsine gas to the arsenic molecular beam source I4 is stopped, and the TEG
TEG molecular beam source! The GaAs substrate 13 is irradiated from 6
One molecular layer is chemically adsorbed onto the surface of. At this time, excessive T
Since EG molecules are not adsorbed on the surface of the chemisorption layer, chemical adsorption of one molecular layer is automatically achieved. Second, light introduction port 1
The surface of the GaAs substrate 13 was irradiated with argon laser light from No. 5, and was scanned and drawn in a stripe shape with a width of 2 pm.

At this time, molecules chemically adsorbed in the area irradiated with light are desorbed. Thirdly, when one TE molecule is irradiated from the TEI molecular beam source 17, one molecule layer having In atoms is selectively chemisorbed in the region where the chemisorption layer has disappeared due to the irradiation with light. At this time, selectivity is automatically achieved because the 721 molecules do not adsorb to the surface of the chemisorption layer containing Ga atoms that was initially formed. Fourth, arsenic molecules were irradiated from the arsenic molecular beam source 14. By the above first to fourth steps, GaAs
A heteroepitaxial layer having a striped InAs monomolecular layer within the plane of the monomolecular 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 the GaAs single crystal Fj) film.

In the above embodiments, the growth method according to the present invention was used to form the group M atomic layer, but the growth method according to the present invention can also be used to form a pattern when forming the group V atomic layer.

Although triethylgallium and triethylindium were used as material compounds in the above embodiments, organometallic compounds having other organic groups such as trimethylgallium may also be used.

In the above example, an organometallic material that forms a molecular layer having an alkyl group was used as the chemisorption layer. Diethylgallium chloride (molecular formula: (C,H,), Ga(4) and diethylindium chloride (molecular formula, (COH,), [n
Alkyl chlorides such as CU, or chlorides such as gallium chloride (molecular formula: GaCjl) and indium chloride (molecular formula: InCR) may be used.

In the above embodiments, alkyl compounds of gallium and indium were used as material compounds, but organic compounds of constituent elements of compound semiconductors and impurities such as aluminum, phosphorus, arsenic, antimony, zinc, and beryllium may also be used.

[Effects of the Invention] As described above, according to the epitaxial growth method of the present invention, a petrolite film having good interface quality in a local region having a diameter of light convergence in the in-plane direction and a size of one atomic layer in the layer thickness direction. It has the effect of forming a structure.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an atomic layer epitaxial growth chamber in one embodiment of the present invention. lO...Growth chamber II...Vacuum pump 12
... Substrate holder 14 ... Arsenic molecular beam source 16 ... TEG molecular beam source

Claims (1)

[Claims] (1) In a method of epitaxial growth by alternately irradiating molecules containing a Group III element and molecules containing a Group V element onto a semiconductor substrate heated while being held in vacuum, which serves as a molecular flow region, the Group III or Group V element is 1. An epitaxial growth method, which comprises irradiating a molecule containing the molecule with light, then irradiating the molecule with light locally, and then irradiating a molecule containing an element that is the same group as the element contained in the molecule and different from the element.