JPH06112142A - Manufacture of superlattice semiconductor - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor device having the superlattice structure industrially at a molecule layer unit by a novel method. CONSTITUTION:Ultraviolet ray are applied to the surface of a substrate. Under this state, at least two kinds of raw material gases are alternately introduced on the surface of the substrate from the outside of a growing cell through at least two nozzles, whose tip openings face the vicinity of the surface of the semiconductor substrate. The specified number number of molecule layers are grown at 1-several molecule-layer unit for the first semiconductor only by the opening and closing of valves, which are arranged for the respective nozzles, and the evacuation of the growing cell in the first step. The spcified number of molecule layers are grown at 1-several molecule-layer unit for the second semiconductor, whose component element is different from that of the frist semiconductor. in the second step. The superlattice structure is formed by repeating the first and second steps by the specified number of times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a superlattice of a molecular layer unit having a self-stop function.

[0002]

2. Description of the Related Art A semiconductor device having a superlattice structure is known as one in which different semiconductors are periodically formed in order to realize characteristics that cannot be obtained by a single semiconductor. However, this superlattice structure semiconductor device must have a structure in which a periodic potential is provided in the one-dimensional direction of the crystal that is sufficiently longer than the lattice constant of the host crystal and shorter than the mean free path of electrons. Therefore, it is difficult to manufacture, and so far, the manufacturing has stopped at the laboratory stage and has not been industrialized. As a semiconductor manufacturing method, a molecular beam epitaxial method (hereinafter abbreviated as MBE method), a crystal growth method using an organic metal (hereinafter abbreviated as MO-CVD method), an atomic layer epitaxial method (hereinafter referred to as an ALE method) are conventionally used. Although abbreviated) and the like are known, it is not easy to form a superlattice structure or it is not possible to form a superlattice structure due to poor film thickness controllability and crystallinity.
That is, in the case of the MBE method, it is difficult to completely satisfy the stoichiometric composition (stoichiometry) because the molecular beam source is applied to the substrate for growth, and the atoms adsorbed on the substrate are subjected to liquid phase growth. As described above, since the crystal surface does not move freely, there is a drawback that a good crystal structure cannot be obtained.

In the MO-CVD method, Japan. J. A
ppl. Phys. 19, (1980) L551 to L5
54, etc., an example of forming a superlattice structure is shown, but the thickness of the boundary layer (transition layer) between different semiconductors is 60Å (about 20
It is difficult to control the grown film thickness with the accuracy of each molecular layer as shown in (Molecular layer), a high substrate temperature of 600 ° C. is required, and the thermal decomposition reaction causes the crystallinity to be originally high. It had the drawback of being bad. The ALE method, as disclosed in Japanese Patent Application Laid-Open No. 55-130896, alternately introduces a vapor containing a component element of a compound semiconductor onto the surface of a glass substrate to form a thin film by an exchange surface reaction. Since it is amorphous, the lattice constant is not defined, and there is a drawback that a superlattice structure cannot be formed. Also A
The LE method has a drawback that only 1/3 molecular layer or less can be grown in one cycle of alternate steam introduction. Furthermore, in the ALE method, II
It has a defect that the IV compound semiconductor and Si cannot grow.

[0004]

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to provide a method capable of industrially precisely manufacturing a semiconductor device having a superlattice structure in units of molecular layers by a novel method.

[0005]

According to the present invention, at least one molecular layer is formed in one cycle of gas introduction by alternately introducing a gas containing a crystal component element from the outside into a growth tank evacuated to a vacuum under predetermined conditions. The growth film thickness is controlled on a molecular layer basis, and a crystal satisfying the stoichiometric composition is grown to obtain a superlattice semiconductor device which can be designed by the number of molecular layers.

[0006]

EXAMPLES Examples of the present invention will be described below with reference to GaAs-Ga _1-x.
A case of manufacturing a superlattice semiconductor device of Al _x As _1-y P _y will be described as an example.

FIG. 1 is a block diagram of a crystal growth apparatus according to an embodiment of the present invention. In the figure, 1 is a growth tank, the material is metal such as stainless steel, 2 is a gate valve, 3
Is an exhaust device for evacuating the growth tank 1 to an ultrahigh vacuum, and 4 is G such as GaCl ₃ or TMG (trimethylgallium).
Nozzle for introducing a compound gas containing a, 5 is a nozzle for introducing a compound gas containing As such as AsH ₃ , 6 is TMA
Nozzle for introducing a compound gas containing Al such as (trimethylaluminum), 7 is a nozzle for introducing a compound gas containing P such as PH ₃ and PCl ₃ , and 8, 9, 10, 11 are valves for opening and closing the nozzle. , Gas source 12 (GaCl
₃ ), 13 (AsH ₃ ), 14 (TMA, etc.), 15 (P
H ₃ etc., 16 is a heater for heating the substrate, a tungsten (W) wire enclosed in quartz glass and wiring is not shown, 17 is a thermocouple for temperature measurement, Reference numeral 18 denotes a GaAs substrate, and the tip end openings of the nozzles 4, 5, 6 and 7 face the GaAs substrate surface direction and are arranged as close to the substrate surface as possible. Reference numeral 19 is a pressure gauge for measuring the pressure in the growth tank.

With this structure, GaA is formed on the GaAs substrate 18.
In the case of epitaxially growing s, first, the gate valve 2 is opened, and the inside of the growth tank 1 is evacuated to about 10 ⁻⁷ to 10 ⁻⁸ Pascal (hereinafter abbreviated as Pa) by the ultrahigh vacuum evacuation device 3. Next, the GaAs substrate 18 is set to 300-800.
° C. Preferably after heating by the heater 16 to 300 to 500 ° C., pressure in the growth chamber 1 TMG12 is 10 ^-1 to
In the range of 10 ⁷ Pa, the number of molecules is sufficiently larger than the number of molecules necessary for forming the one-molecule adsorption layer, and the valve 8 is opened for 0.5 to 10 seconds to introduce the one-molecule adsorption layer. Next, after exhausting the excess TMG remaining for the formation of the adsorption layer for one molecule from the growth tank 1,
H ₃ 13 is introduced by opening the valve 5 for 2 to 200 seconds, which is sufficiently larger than the number of molecules necessary for forming a monomolecular adsorption layer within a range where the pressure in the growth tank 1 is 10 ⁻¹ to 10 ⁷ Pa. The excess AsH ₃ 13 remaining for forming the one-molecule adsorption layer is then exhausted.
GaAs is formed by the exchange surface reaction accompanying this gas introduction cycle.
A monolayer can grow with a self-terminating function. By repeating this gas introduction cycle a desired number of times, GaAs having a desired number of molecular layers can be formed without using a special film thickness monitor.

Subsequently, the GaA thus grown
In the case of heteroepitaxially growing Ga _1-x Al _x As _1-y P _y on the s molecular layer, Ga and Al of group III are introduced in the same manner as the growth of GaAs, and then As and P of group V are added.
By introducing, one molecular layer can be grown, and by repeating this, a desired number of molecular layers can be obtained.

FIG. 2 shows Ga _{1 -x} Al _x As formed by the above-mentioned molecular layer epitaxial growth or heteroepitaxial growth.
_1-y P _y This is a process for manufacturing a superlattice semiconductor device. First, as shown in FIG.
The aAs layer 21 has a predetermined number of molecular layers, for example, 3 for each molecular layer.
Epitaxially grow on the 0 molecular layer. Then, as shown in FIG. 3B, Ga _{1 -x is formed} on the GaAs layer 21.
The Al _x As _1-y P _y layer 22 is heteroepitaxially grown by controlling a predetermined number of molecular layers, for example, 40 molecular layers in a molecular layer unit. Further, by repeating the above operation for a predetermined cycle, for example, 100 cycles, a superlattice structure is formed. FIG. 3C shows three GaAs layers 2.
In this example, 1 and Ga _1-x Al _x As _1-y P _y layers 22 are alternately grown in molecular layer units. At this time, the composition of the mixed crystal of Ga _1-x Al _x As _1-y P _y for lattice matching with GaAs is x = 0.3 and y = 0.01. In the superlattice structure thus formed, as shown in FIG.
The electrodes 23 and 24 are formed by vacuum-depositing an e-alloy of several hundred liters. This is formed, for example, by heat treatment at 450 ° C. in a H ₂ gas flow for 1 minute. As a result, the superlattice diode 25
Can be manufactured. As shown in FIGS. 2C and 2D, Ga
There is no transition layer between the As layer 21 and the Ga _1-x Al _x As _1-y P _y layer 22, and the superlattice structure can be accurately manufactured in a molecular layer unit.

By the way, in manufacturing the superlattice semiconductor as described above, by irradiating the substrate with ultraviolet rays during the growth, the growth temperature can be lowered to a low temperature such as 300 ° C. or lower, and the crystal quality is improved. be able to. As the ultraviolet ray source, a mercury lamp, a Xe lamp, an excimer laser, an argon ion laser, or the like can be used, and a window may be provided in the growth tank 1 to irradiate the substrate 18 from the outside.

In the above embodiment, Ga _{1 -x} A
The superlattice semiconductor device of l _x As _1-y P _y has been described. However, by introducing a gas containing impurities into the growth tank, impurities are added to GaAs and Ga _1-x Al _x As _1-y P _y . It goes without saying that you can do it. In this case, GaAs, G
As a gas containing an n-type impurity for both a _1-x Al _x As _1-y P _y , hydrides and fluorides of Group VI Te and Se such as H ₂ S can be used. Further, as p-type impurities, a gas such as ZnCl ₃ or demethylzinc may be used as a group III or V gas.
It can be introduced with the tribe gas.

In addition to the above embodiments, the combination of semiconductors forming the superlattice is InAs-GaSb, GaSb-.
AlSb, InAs-AlSb, InP-In _1-x Ga _x
P _1-z As _z , InP-In _1-x Ga _x As, GaAs-G
aAs _1-x P _x , GaP-GaP _1-x As _x , GaAs-G
a _1-x In _x As, GaP-AlP, GaSb-InS
b, Ge-GaAs, Si- GaP, Si-Si 1-x G
e _x , CdTe-HgTe, PbTe-Pb _1-x Sn _x T
e, PbTe-Pb _1-x Ge _x Te, etc. combination, p-type and n
Shaped semiconductor combinations, three semiconductor combinations, eg In
It can be applied to As-GaSb-AlSb and the like.

[0014]

As described above, according to the present invention, since a semiconductor crystal film has a self-stopping function and can be grown in a molecular layer unit with good crystallinity at a low temperature, the conventional MO-
It becomes possible to industrially produce a superlattice semiconductor device having no transition layer between different semiconductors existing in the case of a superlattice structure formed by a vapor phase growth method such as a CVD method. According to the present invention, there is no need to use an inert gas other than a raw material gas such as a carrier gas in ordinary vapor phase growth or a gas phase diffusion barrier in the ALE method, and the apparatus configuration is simplified. Further, according to the present invention, since the growth is performed by the self-stop function, only gas introduction cycles are counted, and a film thickness monitor is not required. Therefore, the configuration and operation of the device are easy, and it is possible to control the molecular layer unit, which is an industrial advantage. large.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a crystal growth apparatus according to an embodiment of the present invention.

2A to 2D are explanatory views of the manufacturing process of the superlattice semiconductor device manufactured by the apparatus of FIG.

[Explanation of symbols]

1 Growth Tank 2 Gate Valve 3 Exhaust Device 4,5,6,7 Nozzle 8,9,10,11 Valve 12,13,14,15 Gas Source 16 Heater 17 Thermocouple 18,20 GaAs Substrate 19 Pressure Gauge 21 GaAs Layer 22 Ga _1-x Al _x As _1-y P _y layer 23, 24 electrode 25 superlattice diode

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[Procedure amendment]

[Submission date] November 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

In the MO-CVD method, Japan. J. A
ppl. Phys. 19, (1980) L551 to L5
54, etc., an example of forming a superlattice structure is shown, but the thickness of the boundary layer (transition layer) between different semiconductors is 60Å (about 20
It is difficult to control the grown film thickness with the accuracy of each molecular layer as shown in (Molecular layer), a high substrate temperature of 600 ° C. is required, and the thermal decomposition reaction causes the crystallinity to be originally high. It had the drawback of being bad. The ALE method, as disclosed in Japanese Patent Application Laid-Open No. 55-130896, alternately introduces a vapor containing a component element of a compound semiconductor onto the surface of a glass substrate to form a thin film by an exchange surface reaction. Since it is amorphous, the lattice constant is not defined, and there is a drawback that a superlattice structure cannot be formed. Also A
The LE method has a drawback that only 1/3 molecular layer or less can be grown in one cycle of alternate steam introduction. Furthermore, its in the ALE method
Japanese Patent Application Laid-Open No. 51-77589
In principle, there is a drawback that a single element semiconductor such as Si cannot grow. Furthermore, the ALE method
Since the raw material gases that can be used are limited, alternating raw material gases
III-V compound semiconductor cannot grow due to introduction
It had drawbacks.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

[0005]

According to the present invention, a gas containing a crystal component element is alternately introduced from the outside into a growth tank which is evacuated to a vacuum, and a single molecule adsorption layer is interposed therebetween.
By using the exchange surface reaction , at least one molecular layer is formed in one cycle of gas introduction, the growth film thickness is controlled in units of molecular layers, and by growing crystals satisfying the stoichiometric composition, it is possible to design by the number of molecular layers. The feature is that a lattice semiconductor device can be obtained.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

FIG. 2 shows Ga _1-x Al _x A formed by the above-described molecular layer epitaxial growth or heteroepitaxial growth.
₁ shows a manufacturing process of an s _1-y P _y superlattice semiconductor device. First, as shown in FIG.
The gas introduction cycle is repeated 30 times with the GaAs layer 21 having a predetermined number of molecular layers, for example, 30 molecular layers on a molecular layer basis.
And epitaxially grow. Then, as shown in FIG.
_{The 1-x} Al _x As _1-y P _y layer 22 is also provided with a predetermined number of molecular layers, for example, 40 molecular layers in a gas introduction cycle in a molecular layer unit.
Heteroepitaxial growth is repeated 40 times . Furthermore, the above GaAs layer 21 and Ga _1-x A
The superlattice structure is formed by repeating the operation of alternately stacking the l _x As _1-y P _y layers 22 at a predetermined cycle, for example, 100 cycles. In the same figure (c), three layers of G are shown.
aAs layer 21 and Ga _1-x Al _x As _1-y P _y layer 22
In this example, and are alternately grown in a molecular layer unit. At this time, Ga _1-x Al _x for lattice matching with GaAs
The composition of the mixed crystal of As _1-y P _y is x = 0.3, y = 0.0.
Set to 1. On the superlattice structure thus formed, as shown in FIG. 4D, an Au—Ge alloy is vacuum-deposited by several hundred Å to form electrodes 23 and 24. This is, for example, 4
It is formed by heat treatment at 50 ° C. for 1 minute in an H ₂ stream. Thereby, the superlattice diode 25 can be manufactured. Figure 2
As shown in (c) and (d), the GaAs layer 21 and Ga are
_There is no transition layer between the _1-x Al _x As _1-y P _y layer 22 and the superlattice structure can be accurately manufactured in molecular layer units.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

As described above, according to the present invention, since a semiconductor crystal film has a self-stopping function and can be grown in a molecular layer unit with good crystallinity at a low temperature, the conventional MO-
It becomes possible to industrially produce a superlattice semiconductor device having no transition layer between different semiconductors existing in the case of a superlattice structure formed by a vapor phase growth method such as a CVD method. According to the present invention, there is no need to use an inert gas other than a raw material gas such as a carrier gas in ordinary vapor phase growth or a gas phase diffusion barrier in the ALE method, and the apparatus configuration is simplified. Further according to the present invention, minute by self-limiting feature
Since the growth is carried out in units of child layers, only gas introduction cycles are counted and a film thickness monitor is not required. Therefore, the configuration and operation of the apparatus are easy, and control can be performed in units of molecular layers. Further in the present invention
According to this, single-element semiconductivity, which was impossible in principle by the ALE method
Since it is possible to form a superlattice of the body, Si-
A superlattice such as Si _1-x Ge _x can be formed in molecular layer units.
Wear. Further, according to the present invention, it cannot be used in the ALE method.
Gas with low vapor pressure such as TMG, TEG, GaCl ₃
Can be used, so that the most applied superlattice structure is I
Since a superlattice of II-V compound semiconductors can be realized,
The economic advantage is great. Further, according to the present invention, ultraviolet light is irradiated.
By doing so, light energy can cause surface reactions such as surface migration.
Superlattice with high crystal quality such as promoting and high hole mobility
Because it can be realized, it is extremely fast and operates with high efficiency.
A lattice semiconductor device can be realized.

Claims (1)

[Claims] 1. A tip opening is directed toward the vicinity of the surface of a semiconductor substrate, and at least two nozzles are provided through each of the two nozzles.
An exchange surface reaction on the surface of the substrate is performed by alternately introducing different kinds of source gas from the outside of the growth tank to the surface of the substrate, opening and closing valves provided in each of the nozzles, and evacuating the growth tank. And a monomolecular layer containing less semiconductor single crystal is formed in one cycle of the exchange surface reaction, and at the same time, ultraviolet light is irradiated onto the substrate surface to improve the crystal quality of the semiconductor single crystal. A method of obtaining a single crystal having a desired number of molecular layers by repeating a cycle, comprising: (i) growing a first semiconductor in a predetermined number of molecular layers in a unit of one to several molecular layers; A superlattice is formed by alternately repeating a predetermined number of molecular layer growth steps of a second semiconductor having a constituent element different from that of the first semiconductor in a unit of one to several molecular layers on the first semiconductor. Specialized in forming semiconductor structures A method for manufacturing a superlattice semiconductor device.